JP7698210B2 - Manufacturing device for hollow curved parts and manufacturing method for hollow curved parts - Google Patents

Description

The present invention relates to a manufacturing device for hollow bent parts and a manufacturing method for hollow bent parts.

As is well known, metal strength members, reinforcing members, or structural members having a hollow, curved shape and used in automobiles, various machines, etc., are required to be lightweight and strong. Conventionally, this type of hollow curved part has been manufactured, for example, by cold bending, welding of pressed products, punching of thick plates, and even forging. However, these manufacturing methods have limitations on how light and strong the hollow curved parts can be manufactured, and it has not been easy to achieve this.

In recent years, the production of this type of hollow curved part using the so-called tube hydroforming method has been actively considered, as disclosed in, for example, Non-Patent Document 1. However, as described on page 28 of Non-Patent Document 1, the tube hydroforming method faces challenges such as the development of materials to be used and the expansion of the freedom of shapes that can be formed, and further development is necessary in the future.

In view of the above situation, the present inventors have previously disclosed an invention relating to a hot bending apparatus in Patent Document 1. Fig. 7 shows one embodiment of the invention in Patent Document 1, and is an explanatory diagram showing a schematic configuration of the hot bending apparatus 100.
7, in this hot bending apparatus 100, a steel pipe (hereinafter, referred to as hollow material Pm) supported by support means 101 (a pair of support means 101a, 101b) so as to be freely movable in its axial direction is fed from upstream to downstream by a feed device (not shown) in the direction of arrow F, while bending is performed downstream of the support means 101a, 101b to manufacture a steel hollow curved part Pp. That is, downstream of the support means 101a, 101b, the hollow material Pm is rapidly heated by the high-frequency heating coil 102 to a temperature range where it can be partially quenched, and the hollow material Pm is rapidly cooled by a water cooling device 103 arranged downstream of the high-frequency heating coil 102. Then, the tip of the hollow material Pm is gripped by gripping means 104 (a pair of gripping means 104a, 104b), and the position of the gripping means 104 is changed in a three-dimensional direction (or in a two-dimensional direction in some cases) to apply a bending moment to the heated portion of the hollow material Pm, thereby bending the hollow material Pm. With this hot bending device 100, it is possible to manufacture a high-strength hollow curved part Pp with high work efficiency.

International Publication No. 2006/093006 International Publication No. 2011/024741 JP 2021-16890 A

Automotive Technology Vol. 57, No. 6, 2003 pages 23-28 Tube Forming, Corona Publishing, 1st edition, 3rd printing, November 15, 2002, pages 51-55

There are various shapes of hollow curved parts used in automobiles, various machines, etc. Among them, there are many hollow curved parts having an extremely small bend, for example, where the bend radius of the bend is 1 to 2 times or less than the diameter of the metal tube (the length of the side in the bending direction in the case of a rectangular cross section).
However, when bending a metal pipe using the method of Patent Document 1 so that the bending radius is, for example, 1 to 2 times the diameter of the metal pipe (the length of the side in the bending direction in the case of a rectangular cross section) or less, there is a risk that wrinkles or folds will occur on the inner periphery of the bent part, or that the plate thickness on the outer periphery of the bent part will be significantly reduced, leading to breakage. For this reason, it has been difficult to manufacture a hollow bent part having a small bend.
Furthermore, in the cold bending of hollow bent parts, tensile stress acts on the outer periphery of the bent part, resulting in a reduction in plate thickness, as described in Non-Patent Document 2. Similarly, the method of Patent Document 1 is also a bending process, so a reduction in plate thickness on the outer periphery of the bent part is unavoidable.

In order to solve these problems, the present inventors disclosed an invention relating to a hot shear bending apparatus in Patent Document 2.
As shown in Fig. 8, the hot shear bending processing device 200 includes a first support means 201 (a pair of support means 201a, 201b), a heating means 202, a cooling means 203, and a gripping means 204. The pair of support means 201a, 201b support the metal hollow material Pm at a first position A1 while relatively feeding the hollow material Pm in its longitudinal direction. The heating means 202 partially heats the hollow material Pm at a second position B1 downstream of the first position A1 along the feeding direction of the hollow material Pm. The cooling means 203 cools (forced cooling or natural cooling) the heated portion of the hollow material Pm at a third position C1 downstream of the second position B1 along the feeding direction of the hollow material Pm. The gripping means 204 applies a shear force to the heated portion of the hollow material Pm by moving the hollow material Pm in two or three dimensions while positioning it at a fourth position D1 that is downstream of the third position C1 along the feed direction of the hollow material Pm. Thus, this hot shear bending apparatus 200 makes it possible to apply shear processing and heat treatment to the heated portion of the hollow material Pm. This shear bending apparatus 200 makes it possible to mass-produce high-strength hollow bent parts Pp at low cost, having bent portions with a bending radius of 1 to 2 times the diameter of the metal tube (the length of the side in the bending direction in the case of a rectangular cross section) or less.
According to the invention of Patent Document 2, it becomes possible to manufacture a hollow bent part Pp that has high strength yet a small bending radius, and this leads to a significant reduction in the weight of many mechanical parts, including automobiles.

Furthermore, Patent Document 3 discloses a shear bending device 300 shown in Figure 9 and a method for manufacturing a hollow bent part using this device. In the shear bending device 300, the shear angle applied to the hollow material Pm is set to θ (degrees), and the inclination angle of the heating device 301 and the cooling device 302 relative to the feed direction of the hollow material Pm is set to α (degrees). This configuration makes it possible to partially increase the product plate thickness of the hollow bent part Pp while also reducing its weight to meet various design needs.

In the hot bending or hot shear bending described above, bending is performed by applying a bending force or shear force by the gripping means to an area (hereinafter referred to as the deformation area) that has become hot due to heating from the heating means and has reduced deformation resistance. Here, if the distance from the deformation area to the gripping means that applies the bending force or shear force is L, the relationship between the distance L and the processing force is as shown in Figure 10(a). Also, the relationship between the distance L and the moment acting on the deformation area is as shown in Figure 10(b).

As shown in Fig. 10(b), the hot bending deformation to obtain a predetermined bending radius is caused by a moment Mb. The moment Mb is applied by moving the gripping means that grips the tip of the hollow material Pm along a predetermined trajectory. Here, in hot bending, the moment Mb required to obtain a predetermined bending deformation is Mb = Wb x L, where Wb is the processing force and L is the distance between the gripping means and the deformation area. Therefore, in hot bending, as shown in Fig. 10(a), the processing force Wb decreases as the distance L increases.
On the other hand, as shown in Fig. 10(a), deformation in hot shear bending is caused by the processing force Ws by the gripping means. In hot shear bending, the processing force Ws required to obtain a predetermined bending deformation is constant regardless of the distance L. Therefore, in hot shear bending, as shown in Fig. 10(b), the moment Ms increases as the distance L increases.

Therefore, in hot shear bending, as the gripping means moves downstream due to the processing force Ws, the hollow material elastically deforms with the support means as a fulcrum, and the deflection due to the elastic deformation increases. If the elastic deflection increases, the hollow material may come into contact with the heating means, or the manufacturing of hollow bent parts may become difficult. Since the part of the hollow material downstream of the heating means also elastically deforms, the relative position between the heating means and the hollow material changes from the original position. In this case, the specified deformation is not applied, and the product precision deteriorates. Furthermore, the gripping means may receive a large moment from the hollow material and rotate as a rigid body. In this case, the specified shear deformation cannot be applied, and the product precision deteriorates. In addition, in order to avoid the rigid body rotation of the gripping means, it is necessary to increase the rigidity of the equipment, which causes the equipment to become larger.

For the reasons explained above, there is a demand for processing technology that can achieve higher processing accuracy when manufacturing hollow bent parts using shear bending processing.

The present invention was made in consideration of the above circumstances, and aims to provide a manufacturing device and manufacturing method for hollow bent parts that can perform shear bending processing with high processing accuracy.

In order to solve the above problems, the present invention employs the following means.
(1) A manufacturing apparatus for a hollow curved part according to one aspect of the present invention comprises:
a feed section for moving a hollow metal workpiece in its longitudinal direction;
a support means for supporting the workpiece while restricting movement of the workpiece in a direction perpendicular to the longitudinal direction and allowing movement of the workpiece in a feed direction along the longitudinal direction;
a heating coil disposed downstream of the support means in the feed direction so as to surround the workpiece and heat the workpiece;
a cooling section that cools the workpiece downstream of the heating coil in the feed direction;
a gripping means for gripping the workpiece at a gripping position downstream of the cooling portion in the feed direction;
An operation unit that moves the gripping means;
A control unit that controls the feeding unit, the heating coil, the cooling unit, the gripping means, and the operation unit;
Equipped with
An apparatus for applying a shear bending process to the workpiece by moving the gripping means in a two-dimensional direction or a three-dimensional direction by the operating unit,
The control unit:
From the start to the end of the shear bending process,
so that a distance from a most downstream end position in the feed direction of a support range of the workpiece by the supporting means to a center position in the feed direction of a support range of the workpiece by the gripping means is limited within a predetermined distance,
The gripping means and the operating unit are controlled.

According to the manufacturing device for hollow curved parts described in (1) above, the workpiece is partially heated by the heating coil to form a heated portion. Then, the workpiece is supported by the support means on the upstream side and held by the holding means on the downstream side with the heated portion sandwiched therebetween, and the holding means is moved in two-dimensional or three-dimensional directions by the operation unit. By moving the holding means by the operation unit, a shear bending process is applied to the heated portion of the workpiece. From the start to the end of this shear bending process, the control unit limits the distance from the most downstream end position of the support range of the workpiece by the support means to the center position of the support range of the workpiece by the holding means to within a predetermined distance. As a result, the distance between the heated portion of the workpiece and the holding means is shortened. In this way, by holding the workpiece at a position close to the heated portion and shear bending the workpiece, the force point is closer to the action point, and the deflection caused by the bending moment according to the distance between the force point and the action point is reduced. As a result, compared to the conventional case where the workpiece is gripped at its downstream end and subjected to shear bending, the distance between the heated part and the gripping means is shortened, suppressing the bending of the workpiece at this part, and the processing accuracy of the hollow bent part is improved.
In addition, when a sliding type that does not require control or a roller type that only restricts movement in the direction perpendicular to the feed direction of the steel pipe is used as the support means, the support means is not included in the control object of the control device. On the other hand, when the support means itself also has the function of a feed section that feeds the workpiece, the support means is also included in the control object of the control device.

(2) In the manufacturing apparatus for a hollow curved part described in (1) above,
When the average width dimension of the workpiece before the shear bending process is w (mm), the predetermined distance may be set to 20 x w (mm) or less.
According to the manufacturing device for a hollow curved part described in (2) above, the distance between the supporting means and the gripping means can be appropriately shortened to effectively suppress deflection of the workpiece in this portion, and then shear bending can be performed.

(3) The manufacturing apparatus for a hollow curved part according to (1) or (2) above may be configured as follows:
The gripping means
a first gripping state that allows the workpiece to move relative to the gripping means along the longitudinal direction;
a second gripping state in which the workpiece is restricted from moving relative to the gripping means in the longitudinal direction;
The switchable configuration is
The control unit switches the gripping means between the first gripping state and the second gripping state.
According to the manufacturing device for hollow curved parts described in (3) above, when the workpiece is quenched as a straight tube without shear bending, the control unit sets the gripping means to the first gripping state. The gripping means in this first gripping state guides and supports the workpiece so as to allow only relative movement along its longitudinal direction. This allows the workpiece to be quenched while being fed while continuing to support a portion of the workpiece close to the heated portion, thereby suppressing the occurrence of deflection. In addition, before the shear bending process is performed, the control unit switches the gripping means from the first gripping state to the second gripping state, thereby restricting the relative movement of the workpiece with respect to the gripping means. This allows the shear bending process to be performed after keeping the distance between the support means and the gripping means short and suppressing deflection of the workpiece in this portion.

(4) The manufacturing apparatus for a hollow curved part according to (3) above may be configured as follows:
The gripping means
a roller configured to be movable toward and away from the outer peripheral surface of the workpiece and to be in rolling contact with the outer peripheral surface of the workpiece in the first gripping state;
a clamper configured to be movable toward and away from the outer peripheral surface and to come into contact with the outer peripheral surface of the workpiece in the second gripping state;
Equipped with.
According to the manufacturing device for hollow curved parts described in (4) above, in the first gripping state, the workpiece can be guided in the longitudinal direction by the rolling of the rollers without changing the gripping position, while the movement in the radial direction perpendicular to the longitudinal direction can be restricted. Meanwhile, in the second gripping state, the movement of the workpiece along the longitudinal direction can also be restricted by the contact of the clamper.

(5) In the manufacturing apparatus for a hollow curved part according to any one of (1) to (4),
The gripping means and the operating portion may each be provided in a plurality of units.
According to the hollow curved part manufacturing device described in (5) above, instead of the gripping means that moves downstream while holding the workpiece after shear bending, another gripping part can grip the workpiece within the predetermined distance and perform the next shear bending process. Therefore, it is possible to process an extremely long hollow curved part or to perform multiple shear bending processes.

(6) A method for manufacturing a hollow curved part according to one aspect of the present invention includes the steps of:
a feeding step of supporting a hollow metal workpiece at a support position midway along its longitudinal direction while feeding the workpiece in a feed direction along the longitudinal direction while restricting movement of the workpiece in a direction perpendicular to the longitudinal direction;
a heating step of partially heating the workpiece by a heating coil disposed so as to surround the workpiece at a heating position downstream of the support position to form a heated portion;
a cooling step of cooling the workpiece at a cooling position downstream of the heating position;
a shear bending process in which a gripping portion of the workpiece is gripped by a gripping means at a gripping position downstream of the cooling position, and the gripping means is moved in a two-dimensional direction or a three-dimensional direction to shear-bend the workpiece;
having
From the start to the end of the shear bending process,
The distance from the most downstream end position in the feed direction of the support range of the workpiece at the support position to the center position in the feed direction of the gripped portion at the gripping position is limited to within a predetermined distance.

According to the manufacturing method of hollow bending parts described in (6) above, the workpiece is partially heated by a heating coil to form a heated portion. Then, the workpiece is supported at the support position on the upstream side with the heated portion sandwiched therebetween, while the downstream side is held by the holding means, and the holding means is moved in two or three dimensional directions. This movement of the holding means imparts shear bending to the heated portion of the workpiece. From the start to the end of this shear bending process, the distance from the most downstream end position of the support range of the workpiece at the support position to the center position of the held portion at the holding position is limited to within a predetermined distance. As a result, the distance between the heated portion of the workpiece and the holding means is shortened. In this way, by holding the workpiece at a position close to the heated portion and shear bending it, the force point is closer to the action point, and the deflection according to the distance between the force point and the action point is reduced. As a result, compared to conventional methods of gripping the workpiece at its downstream end and shear bending it, the distance between the support position and the gripping means can be shortened to reduce bending of the workpiece in this area, thereby improving the machining accuracy of the hollow bent parts produced.

(7) In the method for manufacturing a hollow curved part described in (6) above,
When the average width dimension of the workpiece before the shear bending process is w (mm), the predetermined distance may be set to 20 x w (mm) or less.
According to the manufacturing method of the hollow curved part described in (7) above, the distance between the support position and the gripping means is appropriately shortened, and the deflection of the workpiece in this portion is effectively suppressed, and then the shear bending process can be performed.

(8) In the method for manufacturing a hollow curved part described in (6) above,
The predetermined distance may be set based on a shear load of the workpiece.
According to the manufacturing method of the hollow curved part described above in (8), it is possible to more effectively suppress the deflection according to the shape and material of the workpiece.

(9) In the method for manufacturing a hollow curved part according to any one of (6) to (8) above,
Before the start of the shear bending process,
The gripping means may be switched from a first gripping state in which the workpiece is gripped while allowing movement along the longitudinal direction, to a second gripping state in which movement of the workpiece is restricted along the longitudinal direction.
According to the manufacturing method of the hollow curved part described in (9) above, when the workpiece is hardened as a straight tube without shear bending, the gripping means is in the first gripping state, and the workpiece can be hardened while being fed while continuously supporting a portion of the workpiece close to the heated portion, thereby suppressing the occurrence of warping. In addition, before the shear bending process, the gripping means is switched from the first gripping state to the second gripping state, thereby restricting the relative movement of the workpiece with respect to the gripping means. This shortens the distance between the support position and the gripping means, suppressing the warping of the workpiece in this portion, and then the shear bending process can be performed.

The manufacturing apparatus and method for hollow bent parts according to the above-mentioned aspects of the present invention allow shear bending to be performed with high processing accuracy.

1 is a schematic diagram showing a schematic configuration of a manufacturing apparatus for a hollow curved part according to a first embodiment of the present invention; This shows a case where a shear bending process is applied to a hollow material at a midpoint in the longitudinal direction by a method for manufacturing a hollow bent part using the manufacturing device. This shear bending process proceeds in the order from (a) to (f). FIG. 5 is a schematic diagram showing a schematic configuration of a manufacturing apparatus for a hollow curved part according to a second embodiment of the present invention. FIG. 2 is a perspective view of a gripping means provided in the manufacturing apparatus. This shows a case where a shear bending process is applied to a hollow material at a midpoint in the longitudinal direction by a method for manufacturing a hollow bent part using the manufacturing device. This shear bending process proceeds in the order from (a) to (f). 10A to 10F are diagrams showing a method for manufacturing a hollow curved part according to a third embodiment of the present invention, in which a hollow material is subjected to shear bending at two intermediate positions in the longitudinal direction. The shear bending process proceeds in the order of steps (a) to (f). FIG. 1 is an explanatory diagram showing a schematic configuration of a bending device disclosed in Patent Document 1. FIG. 1 is an explanatory diagram showing a schematic configuration of a shearing device disclosed in Patent Document 2. FIG. 10 is an explanatory diagram showing a schematic configuration of another shear processing device disclosed in Patent Document 3. 1A and 1B are diagrams comparing hot shear bending and normal hot bending, in which (a) shows the change in processing force depending on the gripping position, and (b) shows the change in moment depending on the gripping position.

The following describes the hollow bending member manufacturing apparatus and manufacturing method according to each embodiment of the present invention with reference to the drawings. In the following description, an example is given of the case where a hollow steel square tube having a rectangular cross-sectional shape is used as the workpiece (hereinafter, hollow material Pm) and a hollow bending member Pp is manufactured.

[First embodiment]
First, a manufacturing apparatus for a hollow curved member to which the present manufacturing method is applied (hereinafter, manufacturing apparatus 10) will be described, followed by a description of the manufacturing method.

[Manufacturing device for hollow bending member]
FIG. 1 is a schematic diagram showing the configuration of a manufacturing apparatus 10 according to the present embodiment.
The manufacturing apparatus 10 performs hot shear bending (hereinafter simply referred to as shear bending) on the hollow material Pm to obtain a hollow curved member Pp as shown in FIG. 2(f) described later. The hollow material Pm is a long steel square tube having a closed cross-sectional shape perpendicular to its longitudinal direction. The hollow material Pm to be processed in this embodiment is not limited to a square tube, and may be a tube having a cross-sectional shape of, for example, a circle, an ellipse, or various other irregular shapes. The hollow material Pm having a rectangular cross-section may have a cross-sectional shape of either a square or a rectangle. The hollow material Pm may be a metal tube other than a steel tube.

As shown in FIG. 1, the manufacturing apparatus 10 includes a feed device (feed section) 11, a support device (support means) 12, a heating device 13, a cooling device (cooling section) 14, a shear force applying device 15, and a control device (control section) 16.
(1) Feeding device 11
1, the feed device 11 feeds the hollow material Pm supported by the support device 12 in its longitudinal direction (to the left on the paper surface along the arrow F) at a predetermined feed speed. The feed device 11 is exemplified by a type using an electric servo cylinder, but is not limited to a specific type, and a type using a ball screw, a type using a timing belt or a chain, etc. can also be used.
After the portion of the hollow material Pm where the supporting device 12 is installed has passed the first position A, the hollow material Pm is further fed in the direction of the arrow F by the feeding device 11 .

(2) Support device 12
The support device 12 includes multiple sets of rolls 12a, 12b (two sets in the example of FIG. 1 ). One set of rolls 12a supports the hollow material Pm by sandwiching it between them. Similarly, the set of rolls 12b supports the hollow material Pm by sandwiching it between them. Another set of rolls 12a is disposed adjacent to the downstream position of the set of rolls 12b. The hollow material Pm is supported at the first position A by these rolls 12a, 12b.
Note that the supporting device 12 may have a different configuration as long as it can support the hollow material Pm so as to be freely fed along the feed direction F. For example, the supporting device 12 may be configured to support the hollow material Pm by sliding without including the rolls 12a and 12b.
The support device 12 is fixedly disposed on a mounting base (not shown). However, the present invention is not limited to this embodiment, and the support device 12 may be supported by, for example, an end effector (not shown) of an industrial robot.
Also, by rotating the rolls 12a, 12b, the support device 12 may have a feeding function for feeding the hollow material Pm, and the feed device 11 may be omitted. In this case, the support device 12 serves both as a feed section for moving the hollow material Pm in its longitudinal direction and as a support means for supporting the hollow material Pm.

(3) Heating device 13
The heating device 13 is disposed so as to perform heating at a second position B downstream of the first position A in the feed direction F of the hollow material Pm. The heating device 13 heats the entire circumference of a cross section of a portion in the longitudinal direction of the hollow material Pm fed via the supporting device 12. An induction heating device is used as the heating device 13. This induction heating device has a heating coil 13a that performs high-frequency induction heating of the hollow material Pm.
The heating coil 13a of the heating device 13 is disposed at a predetermined distance from the outer surface of the hollow material Pm so as to surround the entire periphery of the cross section of the hollow material Pm in a portion of the longitudinal direction. The hollow material Pm is rapidly heated in part by the heating device 13 at its heated portion H. The position of the maximum temperature reached in the heated portion H is slightly downstream of the downstream end face of the heating coil 13a, and moves slightly upstream or downstream depending on various conditions such as the way in which cooling water is applied from the cooling device 14 described later. Therefore, the most downstream end position P1 of the heating coil 13a is used as a reference position corresponding to the position of the maximum temperature reached in the heated portion H. This most downstream end position P1 is the most downstream position in the feed direction F when the outer shape of the heating coil 13a is viewed along the central axis CL.
An installation means (not shown) of the heating device 13 may be capable of disposing the heating coil 13a at the second position B so that the tilt angle can be freely adjusted. In other words, the installation means of the heating device 13 may include a rotation means (not shown) that tilts the heating coil 13a at a set angle with respect to the feed direction F of the hollow material Pm.

When the hollow material Pm is a round tube, the cross-sectional shape of the heating coil 13a of the heating device 13 is preferably circular. Specifically, the shape of the heating coil 13a when viewed from the center axis CL along the longitudinal direction of the hollow material Pm is preferably a concentric shape with a uniform clearance from the outer peripheral surface of the hollow material Pm. On the other hand, when the hollow material Pm has an irregular cross-sectional shape including a rectangle, the shape of the heating coil 13a when viewed from the center axis CL of the hollow material Pm is preferably a shape with a clearance suitable for heating from the outer peripheral surface of the hollow material Pm. The center axis CL is the center axis of the hollow material Pm at the position of the support device 12.

As an example of a means for installing the heating device 13, an end effector of a well-known industrial robot can be used, but other installation means can also be used. A single-arm robot or an existing device having an arm and a motor can also be used.

(4) Cooling device 14
The cooling device 14 cools the hollow material Pm at a third position C that is downstream of the second position B along the feed direction F of the hollow material Pm. The cooling device 14 rapidly cools a portion of the hollow material Pm that is located downstream of the portion heated at the second position B. As a result of this cooling, the region of the hollow material Pm between the heated portion H heated by the heating device 13 and the cooled portion cooled by the cooling device 14 becomes high temperature and has significantly reduced deformation resistance.

The cooling device 14 may be any device capable of obtaining the desired cooling rate, and is not limited to a specific type of cooling device. In general, it is desirable to use a water-cooling device that cools the hollow material Pm by spraying cooling water toward a predetermined position on the outer circumferential surface of the hollow material Pm. In this embodiment, multiple cooling water spray nozzles 14a are disposed immediately downstream of the heating device 13, away from the outer surface of the hollow material Pm, so as to surround a portion of the cross section of the hollow material Pm in the longitudinal direction. Cooling water is sprayed from these cooling water spray nozzles 14a toward the outer surface of the hollow material Pm.

Of the heated portion H of the hollow material Pm heated by the heating device 13 , the portion located downstream thereof is rapidly cooled by cooling water sprayed from the cooling device 14 .
This makes it possible to increase the strength of a part or the whole of the bent portion of the hollow material Pm that has been shear-bent, for example, to a tensile strength of 1500 MPa or more.

The installation means of the cooling device 14 is not limited to a specific installation means, as long as it can place the cooling device 14 at the third position C. In order to manufacture a hollow bending member Pp having high dimensional accuracy by the manufacturing apparatus 10 of this embodiment, it is desirable to set the area between the heated part H heated by the heating device 13 and the cooled part cooled by the cooling device 14 as small as possible by setting the distance between the second position B and the third position C as short as possible. For this purpose, it is desirable to place the cooling water injection nozzle 14a close to the heating coil 13a. Therefore, it is desirable to place the cooling water injection nozzle 14a at a position immediately after the heating coil 13a. Furthermore, the cooling device 14 may be fixed to the installation means of the heating device 13. In this case, it is also possible to tilt both the cooling water injection nozzle 14a and the heating coil 13a at the same tilt angle while maintaining the relative positional relationship between each cooling water injection nozzle 14a and the heating coil 13a.

An installation means for the cooling device 14 may be provided separately from the installation means for the heating device 13. In this case, the installation means (not shown) for the cooling device 14 can arrange each cooling water jet nozzle 14a so that the inclination angle can be freely adjusted at the third position C. In other words, the installation means for the cooling device 14 can incline the cooling device 14 at a set angle with respect to the feed direction F of the hollow material Pm.
The cooling device 14 can be installed, for example, on an end effector of a conventional industrial robot, but other installation means can also be used. A single-arm robot or an existing device having an arm and a rotating means such as a motor can also be used.

(5) Shear force applying device 15
The shear force applying device 15 is disposed downstream of a third position C along the feed direction F of the hollow material Pm. The shear force applying device 15 grips the hollow material Pm at a midpoint in the longitudinal direction and moves this gripping position in two-dimensional or three-dimensional directions. Specifically, the gripping position of the hollow material Pm in the shear force applying device 15 is moved in an inclined direction between the feed direction F along the longitudinal direction of the hollow material Pm and a direction perpendicular to the longitudinal direction of the hollow material Pm, as viewed in a cross section including the central axis line CL. As a result, the shear force applying device 15 applies a shear force to at least a part of the region between the heated portion H heated by the heating device 13 and the cooled portion cooled by the cooling device 14 in the hollow material Pm, thereby performing shear bending on the hollow material Pm.

1, the shear force applying device 15 has a pair of arms 15A and 15B and a base (not shown). Instead of having both arms 15A and 15B, the shear force applying device 15 may have only one of the arms 15A and 15B.
The arm 15A has gripping means 15Aa, 15Ab that grip the hollow material Pm at a fourth position D1 that is downstream of the third position C along the feed direction F of the hollow material Pm, and an arm portion (operation portion) 15Ac that supports the gripping means 15Aa, 15Ab and moves their positions in two-dimensional or three-dimensional directions. The arm portion 15Ac is supported by the base. The gripping means 15Aa, 15Ab grip the hollow material Pm between them by approaching each other. On the other hand, the gripping means 15Aa, 15Ab release their grip on the hollow material Pm by moving away from each other.

When the gripping means 15Aa, 15Ab are closed to grip the hollow material Pm, the longitudinal center position of the support range where the gripping means 15Aa, 15Ab contact the hollow material Pm is defined as the gripping position P2. The distance parallel to the feed direction F between the downstream end position P0 along the feed direction F where the roll 12a of the support device 12 contacts the hollow material Pm and the gripping position P2 is shown in FIG. 1 using the symbol L'. During shear bending, this distance L' is maintained within a predetermined distance by the arm 15Ac receiving instructions from the control device 16 described later and adjusting the position of the gripping means 15Aa, 15Ab.

The deformation resistance of a cross section in a portion of the longitudinal direction of the hollow material Pm is significantly reduced by being heated by the heating device 13. For this reason, by moving the positions of the pair of gripping means 15a, 15b in two-dimensional or three-dimensional directions at a fourth position D1 that is downstream of the third position C along the feed direction F of the hollow material Pm, it is possible to apply a shear force to a region in the hollow material Pm between the heated portion H heated by the heating device 13 and the cooled portion cooled by the cooling device 14.
When a shear force acts on the hollow material Pm, it is bent at a midpoint in the longitudinal direction as shown in Fig. 1. In this embodiment, a shear force is applied to the heated portion of the hollow material Pm, rather than a bending moment being applied to the heated portion as in the invention disclosed in Patent Document 1. This makes it possible to manufacture a hollow bent part having a bent portion with an extremely small bend radius, for example, 1 to 2 times the diameter of the metal tube (the length of the side in the bending direction in the case of a rectangular cross section) or less.

The arm 15B has the same configuration as the arm 15A. Fig. 1 shows a state in which the hollow material Pm is released from gripping at a fifth position D2 that is downstream of the fourth position D1 along the feed direction F of the hollow material Pm.
The arm 15B has gripping means 15Ba, 15Bb capable of gripping the hollow material Pm, and an arm portion 15Bc (operation portion) that supports the gripping means 15Ba, 15Bb and moves their positions in two-dimensional or three-dimensional directions. The arm portion 15Bc is supported by the base, similar to the arm portion 15Ac. The gripping means 15Ba, 15Bb are capable of gripping the hollow material Pm between them by approaching each other. On the other hand, the gripping means 15Ba, 15Bb release their grip on the hollow material Pm by moving away from each other as shown in FIG. The hollow material Pm is gripped by either one of the arms 15A or 15B. That is, when shear bending is performed on the hollow material Pm, one of the arms 15A and 15B grips the hollow material Pm at the fourth position D1, and the other releases the grip of the hollow material Pm and retreats to a position other than the fourth position D1. When the hollow material Pm is fed in the feed direction F while being quenched as a straight tube, one of the arms 15A and 15B that gripped the hollow material Pm at the fourth position D1 moves in the feed direction F away from the fourth position D1 while maintaining the gripped state. Then, the other of the arms 15A and 15B moves to the fourth position D1 in preparation for the next shear bending.

(6) Control device 16
The control device 16 controls various operations of the above-mentioned feeding device 11, supporting device 12, heating device 13, cooling device 14, and shear force applying device 15. When a sliding type that does not require operational control is used as the supporting device 12, the supporting device 12 is excluded from the objects to be controlled.
The control device 16 controls the feed amount and feed speed of the hollow material Pm by giving instructions to the feed device 11. On the other hand, when the feed device 11 is omitted and the feed function is provided to the support device 12, the control device 16 controls the rotation amount and rotation speed of the rolls 12a, 12b by giving instructions to the support device 12. This controls the feed amount and feed speed of the hollow material Pm.
The control device 16 controls the power output flowing through the heating coil 13a to control the temperature of the heated portion H. The control device 16 may control the heating coil 13a to be inclined with respect to the hollow material Pm, as necessary.
The control device 16 controls the supply pressure or supply flow rate of the cooling water supplied to each cooling water jet nozzle 14a to control the temperature of the cooled portion. The control device 16 may control each cooling water jet nozzle 14a to be inclined with respect to the hollow material Pm as necessary.
The control device 16 controls each of the arms 15A and 15B individually. That is, the control device 16 controls the position and inclination of each of the gripping means 15Aa, 15Ab and the gripping means 15Ba, 15Bb by controlling the arm 15Ac. The control device 16 also controls the opening and closing operations (gripping state and gripping release state) of each of the gripping means 15Aa, 15Ab and the gripping means 15Ba, 15Bb.
The above is one example of the control device 16, and when the same hollow curved parts Pp are mass-produced, the control amount can be set to a predetermined pattern.

[Method of manufacturing hollow bending member]
A method for manufacturing the hollow curved member Pp from the hollow material Pm using the above-mentioned manufacturing apparatus 10 will be described below with reference to FIG.
In this embodiment, a hollow bending part Pp shown in Fig. 2(f) is manufactured from a hollow material Pm shown in Fig. 2(a) using the manufacturing device 10. The hollow bending part Pp is subjected to shear bending at one location in the longitudinal direction. Note that the control device 16 and the arm portion 15Bc are omitted in Fig. 2.

As shown in Fig. 2(a), first, a hollow material Pm, which is a straight hollow tube made of metal, is set in a manufacturing device 10. That is, the hollow material Pm is supported by a supporting device 12 at a first position A, the rear end side of the hollow material Pm is set in a feeding device 11, and the front end side of the hollow material Pm is gripped by gripping means 15Ba, 15Bb. Meanwhile, the gripping means 15Aa, 15Ab are in a standby state, and therefore are not shown in Fig. 2(a).
At this time, the heating coil 13a of the heating device 13 is disposed at a second position B downstream of the first position A, and each cooling water injection nozzle 14a of the cooling device 14 is disposed at a third position C downstream of the second position B. In addition, the heating coil 13a and each cooling water injection nozzle 14a are disposed so as to be perpendicular to the central axis CL in both a side view and a plan view.
Under the above settings, the heating device 13 starts heating the hollow material Pm.

2(a) and 2(b), the hollow material Pm is supported at a first position A and fed in a feed direction F, which is the longitudinal direction of the hollow material Pm (feeding process), the hollow material Pm is partially heated at a second position B to form a heated portion H (heating process), and at least a portion of the hollow material Pm located downstream of the heated portion H is cooled at a third position C (cooling process). At this time, the gripping means 15Ba and 15Bb move in the feed direction F in synchronization with the feed speed of the hollow material Pm. Therefore, the hollow material Pm is quenched as a straight tube while being fed in the feed direction F without being subjected to shear bending or normal bending.

Next, as shown in FIG. 2(c), when the hollow material Pm reaches the position where shear bending processing is performed, the gripping means 15Aa, 15Ab, which have been in a standby state, are moved to a fourth position D1, and a midpoint in the longitudinal direction of the hollow material Pm is gripped at this position. At this time, the control device 16 controls the gripping position so that the distance L' parallel to the feed direction F between the most downstream position P0 along the feed direction F where the roll 12a of the support device 12 contacts the hollow member Pm and the gripping position P2 is limited to within a predetermined distance.

From the start to the end of the shear bending process, the control device 16 controls the gripping means 15Aa, 15Ab and the arm portion 15Ac, so that the distance L' is continuously adjusted to within the predetermined distance. When the average width dimension of the hollow material Pm before the shear bending process is w (mm), it is advisable to set the predetermined distance to 20 x w (mm) or less, preferably 10 x w (mm) or less. In this case, the distance between the heated portion H and the gripping means 15Aa, 15Ab is appropriately shortened to effectively suppress the deflection of the hollow material Pm in this portion, and then the shear bending process can be performed. Alternatively, the predetermined distance may be set based on the shear load of the hollow material Pm. In this case, the deflection can be suppressed more effectively according to the shape and material of the hollow material Pm.

After the gripping means 15Aa, 15Ab grip the hollow material Pm at the fourth position D1, the gripping means 15Ba, 15Bb at the fifth position D2 are opened to release the grip. After the gripping is released, the gripping means 15Ba, 15Bb are moved so as not to interfere with the hollow material Pm and are placed in a standby state. For this reason, the gripping means 15Ba, 15Bb in a standby state are not shown in Figures 2(d) to 2(f).

As shown in FIG. 2(d), at the fourth position D1, the gripping position of the hollow material Pm is moved in two or three dimensions by the arm 15Ac (shear bending process). Specifically, in the shear bending process, the gripping position is moved in an inclined direction between the feed direction F along the longitudinal direction of the hollow material Pm and a direction perpendicular to the longitudinal direction of the hollow material Pm, as viewed in a cross section including the central axis CL of the hollow material Pm.

At this time, the shear bending processing location is cooled by cooling water from each cooling water injection nozzle 14a, so quenching is also performed at the same time. From the start to the end of the shear bending processing, the distance L' is limited to a predetermined distance by the control device 16. In this way, by gripping the hollow material Pm at a position close to its heated part H and performing the shear bending processing, the force point of the force applied by the gripping means 15Aa, 15Ab becomes close to the action point of the hollow material Pm that receives the shear bending, and the deflection according to the distance between these force points and the action point is reduced. As a result, compared to the conventional case where the hollow material Pm is gripped at its downstream end and shear bending processing is performed, the distance between the heated part H and the gripping means 15Aa, 15Ab is shortened, and the deflection of the hollow material Pm in this part is suppressed, and then the shear bending processing can be performed. Therefore, the processing accuracy of the hollow bent part Pp to be manufactured is improved.

After the shear bending process is completed, as shown in Fig. 2(e), the gripping means 15Aa, 15Ab, while gripping the hollow material Pm, are moved in the feed direction F in synchronization with the feeding operation of the feed device 11. As a result, the hollow material Pm is hardened in a range upstream of the portion where the shear bending process was applied.
When the hardening of the hollow material Pm is completed, the heating by the heating coil 13a is stopped, and the machined hollow curved part Pp is removed from the manufacturing device 10 and thrown down, as shown in FIG. 2(f).
As described above, the hollow curved part Pp is manufactured by a series of steps including the feeding step, the heating step, the cooling step, and the shear bending step. This hollow curved part Pp has little deflection and has high processing accuracy because the distance L' parallel to the feeding direction F from the most downstream position P0 along the feeding direction F where the roll 12a of the support device 12 contacts the hollow member Pm to the gripping position P2 is limited to within the predetermined distance from the start to the end of the shear bending process.

[Second embodiment]
Next, a manufacturing apparatus and a manufacturing method for a hollow curved part according to the second embodiment will be described below with reference to FIGS.

[Manufacturing device for hollow bending member]
The manufacturing apparatus for hollow bending members according to this embodiment (hereinafter, manufacturing apparatus 20) differs from the manufacturing apparatus 10 of the first embodiment described above only in the configuration of the shear force applying device 15. Therefore, by using the same product numbers as those of the manufacturing apparatus 10 for the other components, duplicate descriptions thereof will be omitted.
As shown in FIG. 3, the manufacturing apparatus 20 includes the feeding device (feeding section) 11, the supporting device (supporting means) 12, the heating device 13, the cooling device (cooling section) 14, a shear force applying device 25, and the control device (control section) 16.

The shear force applying device 25 of the present embodiment is disposed at a fourth position D downstream of the third position C along the feed direction F of the hollow material Pm.
The shear force applying device 25 grips the hollow material Pm at a midpoint in the longitudinal direction and moves this gripping position in two or three dimensions. Specifically, the gripping position of the hollow material Pm in the shear force applying device 25 is moved in an inclined direction between the feed direction F along the longitudinal direction of the hollow material Pm and a direction perpendicular to the longitudinal direction of the hollow material Pm, as viewed in a cross section including the central axis line CL. In this way, the shear force applying device 25 applies a shear force to at least a part of the region of the hollow material Pm between the heated part H heated by the heating device 13 and the cooled part cooled by the cooling device 14, thereby performing shear bending on the hollow material Pm.

As shown in Figures 3 and 4, the shear force applying device 25 has gripping means 25A, 25B that grip the hollow material Pm at a fourth position D that is downstream of the third position C along the feed direction F of the hollow material Pm, an arm (operation unit) 25C that supports the gripping means 25A, 25B and moves their positions in two or three dimensions, and a base (not shown) that supports the arm 25C. Note that multiple sets of gripping means 25A, 25B and arm 25C may be provided.

As shown in FIG. 4, the gripping means 25A has a main body 25Aa, a pair of support rollers 25Ab, a pair of clampers 25Ac, and a drive mechanism (not shown).
The main body 25Aa is a long housing that is long along the longitudinal direction of the hollow material Pm, and has the support rollers 25Ab, the clampers 25Ac, and the drive mechanism built in. A semi-cylindrical recess a for passing the hollow material Pm is formed in the lower part of the main body 25Aa.
The pair of support rollers 25Ab are rotatably disposed at the center of the main body 25Aa in the longitudinal direction thereof. Each support roller 25Ab is supported in a state where it protrudes into the recess a of the main body 25Aa.
A pair of clampers 25Ac are disposed at both longitudinal ends of the main body 25Aa with a pair of support rollers 25Ab interposed therebetween. Each clamper 25Ac is supported within the main body 25Aa so as to be able to move toward and away from the outer circumferential surface of the hollow material Pm. Each clamper 25Ac is able to move in and out of the recess a of the main body 25Aa by receiving the force of the drive mechanism.
The drive mechanism operates upon receiving instructions from the control device 16. Specifically, the drive mechanism switches between a state in which each clamper 25Ac protrudes beyond each support roller 25Ab in the recess a and a state in which each clamper 25Ac is housed within the main body 25Aa. When each clamper 25Ac is housed within the main body 25Aa, each support roller 25Ab abuts on the outer circumferential surface of the hollow material Pm in a freely rolling manner. Conversely, when each clamper 25Ac protrudes beyond each support roller 25Ab in the recess a, these clampers 25Ac abut on the outer circumferential surface of the hollow material Pm in a relatively immovable manner. For example, fluid pressure (hydraulic pressure, air pressure) can be used as the drive source of the drive mechanism.

The gripping means 25B has the same configuration as the gripping means 25A, that is, the gripping means 25B has a main body 25Ba, a pair of support rollers 25Bb, a pair of clampers 25Bc, and other driving mechanisms (not shown).
The main body 25Ba is a long housing that is long along the longitudinal direction of the hollow material Pm and has the same shape and dimensions as the main body 25Aa. The main body 25Ba houses the support rollers 25Bb, the clampers 25Bc, and the other drive mechanisms. A semi-cylindrical recess b is formed in the upper part of the main body 25Ba to pass the hollow material Pm through.
The pair of support rollers 25Bb are rotatably disposed at the longitudinal center of the main body 25Ba. Each support roller 25Bb is supported by the other driving mechanism so as to be movable in and out of the recess b of the main body 25Ba.
A pair of clampers 25Bc are disposed at both longitudinal ends of the main body 25Ba with a pair of support rollers 25Bb interposed therebetween. Each clamper 25Bc is supported within the main body 25Ba so as to be able to move toward and away from the outer peripheral surface of the hollow material Pm. Each clamper 25Bc is able to move in and out of the recess b of the main body 25Ba by receiving the force of the drive mechanism.
The other driving mechanism operates upon receiving instructions from the control device 16. Specifically, the other driving mechanism switches between a state in which each clamper 25Bc protrudes from each support roller 25Bb in the recess b and a state in which each clamper 25Bc is housed in the main body 25Ba. When each clamper 25Bc is housed in the main body 25Ba, each support roller 25Bb abuts on the outer circumferential surface of the hollow material Pm so as to be freely rollable. Conversely, when each clamper 25Bc protrudes from each support roller 25Bb in the recess b, these clampers 25Bc abut on the outer circumferential surface of the hollow material Pm so as not to be able to move relatively. For example, fluid pressure (hydraulic pressure, air pressure) can be used as the driving source of the driving mechanism.

The gripping means 25A, 25B having the above configuration are supported by the arm 25C in a state where the recesses a, b are arranged to face each other. The hollow material Pm can be inserted into the cylindrical space formed by the recesses a, b. With the hollow material Pm inserted between the gripping means 25A, 25B, the clampers 25Ac and 25Bc are housed in the main body 25Aa and the main body 25Ba by the drive mechanism and the other drive mechanism, so that the hollow material Pm can be gripped between the support rollers 25Ab and 25Bb so as to be movable along its longitudinal direction. Although the support rollers 25Ab and 25Bb in this embodiment are driven rollers, if a configuration is adopted in which the support rollers 25Ab and 25Bb are rotated by a motor (not shown) in accordance with the feed amount of the hollow material Pm, the surface quality of the hollow material Pm can be improved.
On the other hand, when the hollow material Pm is inserted between the gripping means 25A, 25B, and the drive mechanism and the other drive mechanism cause each clamper 25Ac and each clamper 25Bc to protrude beyond each support roller 25Ab and each support roller 25Bb within the recesses a, b, the hollow material Pm can be gripped between each clamper 25Ac and each clamper 25Bc so that it cannot move along its longitudinal direction.

Thus, the gripping means 25A, 25B are configured to be freely switchable between a first gripping state that permits relative movement of the hollow material Pm with respect to the gripping means 25A, 25B along the longitudinal direction, and a second gripping state that restricts relative movement of the hollow material Pm with respect to the gripping means 25A, 25B along the longitudinal direction. The control device 16 is capable of switching the gripping means 25A, 25B between the first gripping state and the second gripping state.
When the hollow material Pm is not subjected to shear bending, the gripping means 25A, 25B are placed in the first gripping state and fixed in a fixed position. This makes it possible to support the hollow material Pm movably along the feed direction F without moving the gripping means 25A, 25B.
On the other hand, when shear bending is applied to the hollow material Pm, the gripping means 25A, 25B are put into the second gripping state, and the gripping position is moved in two-dimensional or three-dimensional directions by the arm 25C. As a result, the hollow material Pm is subjected to shear bending.

As shown in FIG. 3, when the gripping means 25A, 25B are in the second gripping state, the longitudinal center position of the support range where the clampers 25Ac and 25Bc contact the hollow material Pm is the gripping position P2. FIG. 3 shows the distance parallel to the feed direction F between the most downstream position P0 along the feed direction F where the roll 12a of the support device 12 contacts the hollow material Pm and the gripping position P2 as L'. During shear bending, the arm 25C receives instructions from the control device 16 and adjusts the position of the gripping means 25A, 25B, so that this distance L' is maintained within a predetermined distance.

By moving the positions of the pair of gripping means 25A, 25B in two or three dimensions at a fourth position D that is downstream of the third position C along the feed direction F of the hollow material Pm, it is possible to apply a shear force to a region in the hollow material Pm between the heated portion H heated by the heating device 13 and the cooled portion cooled by the cooling device 14. When a shear force acts on the hollow material Pm, it bends at a midpoint in the longitudinal direction as shown in FIG.
In this embodiment, the arm portion 25C is used to move the positions of the gripping means 25A and 25B, but instead, a combination of a ball screw and a servo motor may be used.

[Method of manufacturing hollow bending member]
A method for manufacturing the hollow curved member Pp from the hollow material Pm using the above-mentioned manufacturing apparatus 20 will be described below with reference to FIG.
In this embodiment, a hollow bending part Pp shown in Fig. 5(f) is manufactured from a hollow material Pm shown in Fig. 5(a) using a manufacturing device 20. This hollow bending part Pp is subjected to shear bending at one location in the longitudinal direction. Note that the control device 16 and the arm portion 25C are omitted in Fig. 5.

As shown in FIG. 5(a), first, a hollow material Pm, which is a straight hollow tube made of metal, is set in the manufacturing device 20. That is, the hollow material Pm is supported by the support device 12 at the first position A, the rear end side of the hollow material Pm is fixed to the feed device 11, and the front end side of the hollow material Pm is gripped by the gripping means 25A, 25B. At this time, since the clampers 25Ac and 25Bc of the gripping means 25A, 25B are housed in the main bodies 25Aa, 25Ba, the clampers 25Ac and 25Bc are not in contact with the outer circumferential surface of the hollow material Pm. On the other hand, the support rollers 25Ab and 25Bb are in contact with the outer circumferential surface of the hollow material Pm to support the hollow material Pm. Therefore, with the gripping means 25A, 25B fixed in position, the hollow material Pm can be fed along the feed direction F.
Furthermore, the heating coil 13a of the heating device 13 is disposed at a second position B downstream of the first position A, and each cooling water injection nozzle 14a of the cooling device 14 is disposed at a third position C downstream of the second position B. Moreover, the heating coil 13a and each cooling water injection nozzle 14a are disposed perpendicular to the central axis CL in both a side view and a plan view.
Under the above settings, the heating device 13 starts heating the hollow material Pm.

That is, as shown in Figures 5(a) and 5(b), the hollow material Pm is supported at a first position A and fed in a feed direction F, which is the longitudinal direction of the hollow material Pm (feeding process), the hollow material Pm is partially heated at a second position B to form a heated portion H (heating process), and at least a portion of the hollow material Pm located downstream of the heated portion H is cooled at a third position C (cooling process). Even at this time, the outer peripheral surface of the hollow material Pm is supported only by the support rollers 25Ab and 25Bb. Therefore, with the gripping means 25A and 25B fixed in place, the hollow material Pm can be fed along the feed direction F while restricting movement in a direction perpendicular to the central axis CL.

Next, as shown in FIG. 5(c), when the hollow material Pm reaches the position where the shear bending process is performed, the clampers 25Ac and 25Bc are protruded into the recesses a and b. As a result, the clampers 25Ac and 25Bc come into contact with the outer peripheral surface of the hollow material Pm, and the support rollers 25Ab and 25Bb move away from the outer peripheral surface of the hollow material Pm. Therefore, instead of the support rollers 25Ab and 25Bb, the clampers 25Ac and 25Bc support the hollow material Pm. In this way, before the start of the shear bending process, the gripping means 25A and 25B are switched from a first gripping state in which the hollow material Pm is gripped while allowing it to move along the longitudinal direction to a second gripping state in which the movement along the longitudinal direction of the hollow material Pm is restricted. In addition, the restriction on movement of the hollow material Pm in a direction perpendicular to the central axis CL is the same in both the first and second gripping states.

As shown in Figure 5 (c), when the hollow material Pm is supported by each clamper 25Ac and each clamper 25Bc, the control device 16 controls the gripping position P2 so that the distance L' parallel to the feed direction F between the most downstream position P0 along the feed direction F where the roll 12a of the support device 12 contacts the hollow material Pm to the gripping position P2 is limited to within a predetermined distance.
Then, from the start to the end of the shear bending process, the control device 16 controls the gripping means 25A, 25B and the arm portion 25C, so that the distance L' is adjusted to within the predetermined distance. When the average width dimension of the hollow material Pm before the shear bending process is w (mm), it is preferable to set the predetermined distance to 20 x w (mm) or less, preferably 10 x w (mm) or less. In this case, the distance between the heated portion H and each clamper 25Ac and each clamper 25Bc is appropriately shortened, and the shear bending process can be performed after effectively suppressing the deflection of the hollow material Pm in this portion. Alternatively, the predetermined distance may be set based on the shear load of the hollow material Pm. In this case, the deflection can be suppressed more effectively according to the shape and material of the hollow material Pm.

As shown in FIG. 5(d), at the fourth position D, the gripping position P2 of the hollow material Pm is moved in two or three dimensions by the arm 25C (shear bending process). Specifically, the shear bending process moves the gripping position P2 in an inclined direction between the feed direction F along the longitudinal direction of the hollow material Pm and a direction perpendicular to the longitudinal direction of the hollow material Pm, as viewed in a cross section including the central axis CL of the hollow material Pm.

At this time, the shear bending processing area is cooled by cooling water from each cooling water injection nozzle 14a, so quenching is also performed at the same time. From the start to the end of the shear bending processing, the distance L' is limited to a predetermined distance by the control device 16. In this way, by gripping the hollow material Pm at a position close to its heated part H and performing the shear bending processing, the force point of the force applied by the gripping means 25A, 25B becomes close to the action point of the hollow material Pm that receives the shear bending, and the deflection according to the distance between these force points and the action point is reduced. As a result, compared to the conventional case where the hollow material Pm is gripped at its downstream end and shear bending processing is performed, the distance between the heated part H and the gripping means 15Aa, 15Ab can be shortened to suppress the deflection of the hollow material Pm at this part, and then the shear bending processing can be performed. Therefore, the processing accuracy of the hollow bent part Pp to be manufactured is improved.

After the shear bending process is completed, as shown in Fig. 5(e), the gripping means 25A, 25B, while gripping the hollow material Pm, are moved in the feed direction F in synchronization with the feeding operation of the feed device 11. As a result, the hollow material Pm is hardened in a range upstream of the portion where the shear bending process was applied.
When the hardening of the hollow material Pm is completed, the heating by the heating coil 13a is stopped, and the machined hollow curved part Pp is removed from the manufacturing device 20 and thrown down, as shown in FIG. 5(f).
As described above, the hollow curved part Pp is manufactured by a series of steps including the feeding step, the heating step, the cooling step, and the shear bending step. This hollow curved part Pp has little deflection and has high processing accuracy because the distance L' parallel to the feeding direction F from the most downstream position P0 along the feeding direction F where the roll 12a of the support device 12 contacts the hollow member Pm to the gripping position P2 is limited to within the predetermined distance from the start to the end of the shear bending process.

[Third embodiment]
Next, a method for manufacturing a hollow curved part according to the third embodiment will be described below with reference to Fig. 6. Note that since the device configuration is the same as the manufacturing device 10 described in the first embodiment, the same product numbers as those shown in Fig. 1 will be used to omit redundant description.

[Method of manufacturing hollow bending member]
In this embodiment, a hollow bending part Pp shown in Fig. 6(f) is manufactured from a hollow material Pm shown in Fig. 6(a) using the manufacturing device 10. The hollow bending part Pp is subjected to shear bending at two locations in the longitudinal direction. Note that the control device 16 and the arm portion 15Bc are omitted in Fig. 6.

As shown in Figures 6(a) and 6(b), the tip of the hollow material Pm is held by the holding means 15Ba, 15Bb, and the first shear bending process is performed. This first shear bending process is performed, for example, by carrying out the process described in Figure 2. Therefore, from the start to the end of the shear bending process, the distance L' is set to within the predetermined distance by the control device 16.
As shown in Fig. 6(b), even after the shear bending process is completed, the quenching is continued. That is, while supporting the hollow material Pm at the first position A, the hollow material Pm is fed in the feed direction F, which is the longitudinal direction of the hollow material Pm (feeding process), the hollow material Pm is partially heated at the second position B to form the heated portion H (heating process), and at least a part of the hollow material Pm located downstream of the heated portion H is cooled at the third position C (cooling process). At this time, the gripping means 15Ba and 15Bb are moved in the feed direction F in synchronization with the feed speed of the hollow material Pm. Therefore, the range of the hollow material Pm upstream of the portion where the first shear bending process was applied is quenched as a straight pipe while being fed in the feed direction F without being subjected to shear bending or normal bending.

Next, as shown in FIG. 6(c), when the hollow material Pm reaches the position where the second shear bending process is performed, the gripping means 15Aa and 15Ab, which were in a standby state, are moved to the first position A. Then, as shown in FIG. 6(d), the hollow material Pm is gripped at a midpoint in the longitudinal direction at the first position A. At this time, the control device 16 controls the arm portion 15Ac so as to limit the distance L' parallel to the feed direction F between the most downstream position P0 along the feed direction F where the roll 12a of the support device 12 contacts the hollow member Pm to the gripping position P2 within the predetermined distance. After the hollow material Pm is appropriately gripped by the gripping means 15Aa and 15Ab, the gripping means 15Ba and 15Bb, which were gripping the tip of the hollow material Pm at the fifth position D2, are opened to release the grip of the hollow material Pm. In this way, from FIG. 6(c) to FIG. 6(d), the gripping position of the hollow material Pm is switched from the fifth position D2 to the fourth position D1. The gripping means 15Ba, 15Bb that have released the grip are moved so as not to interfere with the hollow material Pm, etc., and are placed in a standby state. For this reason, the gripping means 15Ba, 15Bb in the standby state are not shown in FIG. 6(e) and FIG. 6(f).

Then, as shown in Figures 6(e) and 6(f), a second shear bending process is performed. The shear bending process area is also cooled with cooling water from each cooling water injection nozzle 14a, so quenching is performed at the same time. From the start to the end of the shear bending process, the distance L' is limited to within a predetermined distance by the control device 16. Therefore, the distance between the heated part H and the gripping means 15Aa, 15Ab is shortened, and the shear bending process can be performed while suppressing the deflection of the hollow material Pm in this part.

When the shear bending process is completed, as shown in FIG. 6( f ), the heating by the heating coil 13 a is stopped, and the processed hollow curved part Pp is removed from the manufacturing apparatus 10 and thrown down.
As described above, the hollow curved part Pp is manufactured by a series of steps including the feeding step, the heating step, the cooling step, and the shear bending step. In this hollow curved part Pp, the distance L' parallel to the feeding direction F between the most downstream position P0 along the feeding direction F where the roll 12a of the support device 12 contacts the hollow member Pm and the gripping position P2 is limited to within the predetermined distance at the two shear bending locations from the start to the end of the shear bending. Therefore, the hollow curved part Pp has little deflection and has high processing accuracy.
The above-described embodiments have been described with reference to the case where only hot shear bending is performed. However, it is also possible to manufacture a hollow bent part Pp by combining this shear bending process with, for example, a conventional hot bending process as shown in FIG. 7.

An embodiment of a manufacturing method using the manufacturing apparatus for a hollow curved part will be described below.
In this example, a plurality of hollow curved parts Pp were manufactured, each having a height H of 20 mm, a width w of 20 mm, a plate thickness t of 1.0 mm, and a total length TL of 2000 mm, made of 0.2% carbon steel. The manufacturing method for manufacturing each hollow curved part Pp is as shown in Table 1 below using the corresponding drawing number. In addition, the maximum temperature reached in the heated part H was all set to 950°C. The distance L' was as shown in Table 1.
The dimensional error between the target product dimensions and each of the manufactured hollow curved parts Pp was measured. Products with a dimensional error in the range of -0.5 mm to +0.5 mm were defined as good products, and those outside the range were defined as defective products, and the ratio of the number of defective products to the total number was calculated.
As shown in Table 1, it was confirmed that the defect rate could be reduced compared to the conventional example under all conditions, as shown in Examples 1 to 5 of the present invention. In particular, good results were obtained when L'/w<20 (i.e., L'<20×w). Furthermore, significantly good results were obtained when L'/w<10 (i.e., L'<10×w).

The hollow bending member Pp manufactured by the manufacturing method according to the present invention is applicable to, for example, the applications (i) to (vii) exemplified below.
(i) Structural members of automobile bodies, such as front side members, cross members, side members, suspension members, roof members, A-pillar reinforcements, B-pillar reinforcements, bumper reinforcements, etc.; (ii) Strength members and reinforcing members of automobiles, such as seat frames and seat cross members; (iii) Exhaust system parts, such as exhaust pipes of automobiles; (iv) Frames and cranks of bicycles and motorcycles; (v) Reinforcing members and bogie parts (bogie frames, various beams, etc.) of vehicles such as trains.
(vi) Frame parts and reinforcing members for ship hulls, etc. (vii) Strength members, reinforcing members or structural members for home appliances

10, 20 Manufacturing device for hollow curved parts 11 Feeding device (feeding section)
12 Support device (support means)
13a Heating coil 14 Cooling device (cooling section)
15Aa, 15Ab, 15Ba, 15Bb, 25A, 25B Gripping means 15Ac, 15Bc, 25C Arm part (operation part)
16 Control device (control unit)
25Ab, 25Bb Support roller (roller)
25Ac, 25Bc Clamper D, D1 Grip position F Feed direction H Heated part L' Distance P0 Downstream end position P2 Center position in the longitudinal direction of the range where the gripping means contacts the hollow material (gripping position)
Pm Hollow material (workpiece material)
Pp Hollow bending parts

Claims (9)

a feed section for moving a hollow metal workpiece in its longitudinal direction;
a support means for supporting the workpiece while restricting movement of the workpiece in a direction perpendicular to the longitudinal direction and allowing movement of the workpiece in a feed direction along the longitudinal direction;
a heating coil disposed downstream of the support means in the feed direction so as to surround the workpiece and heat the workpiece;
a cooling section that cools the workpiece downstream of the heating coil in the feed direction;
a gripping means for gripping the workpiece at a gripping position downstream of the cooling portion in the feed direction;
An operation unit that moves the gripping means;
A control unit that controls the feeding unit, the heating coil, the cooling unit, the gripping means, and the operation unit;
Equipped with
An apparatus for applying a shear bending process to the workpiece by moving the gripping means in a two-dimensional direction or a three-dimensional direction by the operating unit,
The control unit:
From the start to the end of the shear bending process,
so that a distance from a most downstream end position in the feed direction of a support range of the workpiece by the supporting means to a center position in the feed direction of a support range of the workpiece by the gripping means is limited within a predetermined distance,
A manufacturing apparatus for a hollow curved part, comprising: a control unit for controlling the gripping means and the operating unit; The manufacturing apparatus for a hollow curved part according to claim 1, characterized in that the specified distance is set to 20 x w (mm) or less when the average width dimension of the workpiece before the shear bending process is w (mm). The gripping means
a first gripping state that allows the workpiece to move relative to the gripping means along the longitudinal direction;
a second gripping state in which the workpiece is restricted from moving relative to the gripping means in the longitudinal direction;
The switchable configuration is
The control unit switches the gripping means between the first gripping state and the second gripping state.
3. The manufacturing apparatus for a hollow curved part according to claim 1 or 2. The gripping means
a roller configured to be movable toward and away from the outer peripheral surface of the workpiece and to be in rolling contact with the outer peripheral surface of the workpiece in the first gripping state;
a clamper configured to be movable toward and away from the outer peripheral surface and to come into contact with the outer peripheral surface of the workpiece in the second gripping state;
4. The apparatus for manufacturing a hollow curved part according to claim 3, further comprising: 5. The manufacturing apparatus for a hollow curved part according to claim 1, further comprising a plurality of the gripping means and a plurality of the operating parts. a feeding step of supporting a hollow metal workpiece at a support position midway along its longitudinal direction while feeding the workpiece in a feed direction along the longitudinal direction while restricting movement of the workpiece in a direction perpendicular to the longitudinal direction;
a heating step of partially heating the workpiece by a heating coil disposed so as to surround the workpiece at a heating position downstream of the support position to form a heated portion;
a cooling step of cooling the workpiece at a cooling position downstream of the heating position;
a shear bending process in which a gripping portion of the workpiece is gripped by a gripping means at a gripping position downstream of the cooling position, and the gripping means is moved in a two-dimensional direction or a three-dimensional direction to shear-bend the workpiece;
having
From the start to the end of the shear bending process,
A method for manufacturing a hollow curved part, characterized in that a distance from a downstream end position in the feed direction of a support range of the workpiece at the support position to a central position in the feed direction of the gripped portion at the gripping position is limited to within a predetermined distance. The method for manufacturing a hollow curved part according to claim 6, characterized in that, when the average width dimension of the workpiece before the shear bending process is w (mm), the specified distance is set to 20 x w (mm) or less. The method for manufacturing a hollow curved part according to claim 6, wherein the predetermined distance is set based on a shear load of the workpiece. Before the start of the shear bending process,
The method for manufacturing a hollow curved part according to any one of claims 6 to 8, characterized in that the gripping means is switched from a first gripping state in which the workpiece is gripped while allowing movement along the longitudinal direction, to a second gripping state in which the workpiece is gripped and the movement along the longitudinal direction is restricted.

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