CN108237323A - A kind of method and apparatus that can effectively reduce/eliminate agitating friction welded blank residual stress - Google Patents

Abstract

A method and device capable of effectively reducing/eliminating the residual stress of a friction stir welded plate, characterized in that a number of heat source points are arranged on the friction stir welding backing plate at the position opposite to the weld seam and on both sides, forming an array arrangement, each The heat source point is heated by a high-frequency induction coil to generate heat, so that the heat source generated by the heat source point matches the heat generated by the friction stir welding process. The array point heat source can produce different residual stresses for different types of plates due to different temperature conductivities. Perform temperature control. During the welding process, the temperature distribution generated by the stirring head in the FSW process is simulated by controlling the point heat sources arranged in an array, so that the temperature distribution of the welding plate is uniform, the temperature gradient in the welding plate is reduced, and the thermal gradient is reduced. the residual stress. After the welding is completed, control the heat generation of the point heat source to keep the temperature of the welding plate and eliminate the mechanical residual stress in the joint.

Description

A method and method for effectively reducing/eliminating residual stress in friction stir welded plates device

technical field

The present invention relates to a device for friction stir welding, especially a device for effectively reducing/eliminating the residual stress of friction stir welding plates, specifically a backing plate used in friction stir welding, through which the backing plate The use can effectively reduce/eliminate the residual stress of the friction stir welding plate, and the device is especially suitable for the control of the residual stress of the friction stir welding of dissimilar plates.

Background technique

Friction stir welding (FSW) is a new solid-phase joining technology invented by The Welding Institute (TWI) in 1991 (US 5460317). FSW uses frictional heat as the welding heat source. In the FSW welding process, a cylindrical welding head is inserted into the joint of the workpiece. Through the high-speed rotation of the welding head, it rubs against the material of the welding workpiece, so that the material temperature of the joint Elevation softens while friction stirring the material to complete the weld. During the friction stir welding process, the uneven temperature distribution of the plates leads to thermal deformation of the material. Due to the different material properties of the different plates, the heat transfer efficiency of the heat generated during welding is different in different plates, which is more likely to cause thermal deformation; the mechanical properties of the stirring head The effect leads to the plastic deformation of the plate, so there is a large residual stress in the plate during the friction stir welding process, and the existence of the residual stress of the plate greatly reduces the fatigue resistance and corrosion resistance of the joint.

In order to reduce the residual stress of the joint, the invention patent "Friction Stir Welding Surface Residual Stress Control Method and Device" (Patent Publication No.: CN101774079B) relates to an incubator that moves with the stirring head, and the welding seam and base metal after welding Insulation, and then into the furnace for cooling, in order to reduce the residual stress of the friction stir welding surface. However, although this method reduces the generation of residual stress, the efficiency is low; due to the limitation of the incubator, this method is only suitable for welding small parts and simple straight line welding, and the effect is not obvious for large parts and complex structural parts.

The invention patent "A Friction Stir Welding Device" (Patent Publication No.: CN103433616B) relates to a friction stir welding device. The device installs a cryogenic treatment box and a low temperature tempering box above the weld seam of the workpiece, and reduces the welding temperature by cooling and heating cycles. The thermal stress generated in the process improves the dimensional stability of the weldment and improves its mechanical properties. However, this method only reduces the thermal stress in the welding process, and has no effect on the remaining stress in the joint. At the same time, the process and device of this method are very complicated, which greatly reduces the welding efficiency.

Invention patent "A Method and Device for Reducing Residual Stress of Friction Stir Welding Plates" (Patent Publication No.: CN106862753A), the device sets several heat source points on the backing plate for friction stir welding at the position opposite to the weld seam, which can reduce the stress at the same time. The residual stress of the plate after welding. However, this device does not take into account the difference in material properties between dissimilar plates, and the effect of reducing the residual stress after welding of dissimilar plates is not obvious.

Contents of the invention

The object of the present invention is to solve the problem of residual stress of welded plates common in the existing friction stir welding technology, to invent a method that can reduce the residual stress of friction stir welded plates, especially dissimilar plates, and to provide a corresponding welding backing plate device.

The present invention mainly adopts the addition of an array point heat source at the bottom of the welding plate, and each heat source point of the array type point heat source can be individually controlled. By controlling the heat production of the array point heat source at different times, the additional The array point heat source is consistent with the temperature field generated by the heat source of the stirring head during the welding process, reducing/eliminating the residual stress caused by the heat generated by the stirring head. Insulate the welded area until the welding process is completed, reduce the temperature gradient in the welded plate, and reduce the residual stress caused by the thermal gradient, and the different material properties of different plates lead to different residual stresses distributed on both sides of the weld. At this time The temperature can be controlled everywhere by an array of point heat sources. After the welding is completed, the heat production of the heat source is controlled to keep the welded plate warm, so as to eliminate the mechanical residual stress in the joint, thereby reducing/eliminating the residual stress of the welded joint.

One of technical solutions of the present invention is:

A method that can effectively reduce/eliminate the residual stress of a friction stir welded plate, which is characterized in that a number of heat source points are arranged on the back plate for friction stir welding at the position opposite to the weld seam and on both sides to form an array arrangement, and each heat source point Using high-frequency induction coil heating to generate heat, so that the heat source generated by the heat source point matches the heat generated by the friction stir welding process. The array point heat source can control the temperature according to the different residual stresses of different plates due to different material properties. , during the welding process, the temperature distribution generated by the stirring head in the FSW (Friction Stir Welding) process is simulated by controlling the point heat sources arranged in an array, so that the temperature distribution of the welding plate is uniform and the temperature gradient in the welding plate is reduced , to reduce residual stress due to thermal gradients. After the welding is completed, control the heat generation of the point heat source to keep the temperature of the welding plate and eliminate the mechanical residual stress in the joint.

The heat at the heat source point comes from the conduction of heat generated by the high-frequency induction coil heating the iron core, and the time required to heat the iron core from room temperature (20°C) to 500°C by controlling the high-frequency induction heater coil through the controller for 15s.

The backing plate is provided with the same number of slots as the heat source points, one end of the slot is the edge of the backing plate, and the other end is an arc suitable for the size of the high-frequency induction heater coil, and the center of the arc is located directly below the heat source point. When slotting, take the center of the arc as the dot and reserve the diameter to match the size of the coil and the thickness of the plate. The cylinder is used as a heating core; the high-frequency induction heater coil is installed in the slot, and the size and heating requirements of the high-frequency induction heater coil Related, the high-frequency induction heater coil is wound by a copper pipe passing through the cooling water, and the high-frequency induction heater coil is connected to the control box; an infrared thermometer is placed outside the tank to measure the heating temperature of the high-frequency induction coil, and the temperature measurement point It is located 1-10mm away from the surface of the backing plate from the cylinder.

The backing plate is steel plate, titanium alloy plate, tungsten alloy plate or molybdenum alloy plate.

The diameter of the heat source point is determined by the size of the stirring head, and the radius range is 0.1mm-100mm; the number of heat source points is determined by the length of the plate to be welded, and the range is 1-100; the heat source points are arranged in an array, The distance between two heat source points ranges from 5mm to 500mm.

The size of the high-frequency induction heating coil is related to heating requirements, the diameter is 25mm-100mm, the outer diameter of the copper pipe passing through the cooling water is 10mm-30mm, and the inner diameter is 5mm-15mm. The high-frequency induction heating coil is connected to the control box .

The second technical scheme of the present invention is:

A device capable of reducing the residual stress of friction stir welded plates, which includes a backing plate 1, characterized in that the backing plate 1 is provided with a plurality of heat source points 2 at positions opposite to the weld seam, and the plurality of heat source points 2 are arrayed arrangement; each heat source point 2 is formed by heating the iron core with a high-frequency induction heating coil 3, and the heating power and heating time of the high-frequency induction heating coil 3 are controlled by a controller 7; each heat source point can be controlled separately, and the array arrangement can Different heat source distributions are formed; the iron core is located at the lower part of the heat source point, and the high-frequency induction heating coil 3 formed by the copper pipe 6 passing through the cooling water is wound on the iron core, and the inlet of the copper pipe 6 passing through the cooling water The section and the outlet section are all located in the groove 4, and the iron core is formed by a round pile body 5 located at one end of the groove 4; an infrared thermometer 8 is installed outside the groove 4, and the infrared thermometer 8 is electrically connected with the controller 7 .

The groove 4 is located on the bottom surface of the backing plate 1, one end of which is connected to the edge of the backing plate, and the other end is opposite to the heat source point 2, and the cylinder 5 as an iron core is positioned at the other end of the groove and is opposite to the heat source point; The cylinder is integrally connected with the backing plate or connected by welding; the slot 4 is used for the wiring of the high-frequency induction heating coil 3 .

The diameter of the heat source point is determined by the size of the stirring head, and the radius range is 0.1mm-100mm; the number of heat source points is determined by the length of the plate to be welded, and the range is 1-100; the distance between the two heat source points ranges from 5mm-500mm.

The size of the high-frequency induction heating coil is related to the heating requirements, the diameter is 25mm-100mm, the outer diameter of the copper pipe passing through the cooling water is 10mm-30mm, and the inner diameter is 5mm-15mm.

The temperature measuring point of the infrared thermometer is located at a distance of 1-10 mm from the cylinder 5 to the surface of the backing plate.

Beneficial effects of the present invention:

Using the backing plate for friction stir welding of the present invention to carry out friction stir welding can reduce/eliminate the residual stress of the welding plate, improve the performance of the welded joint of the plate, and realize high-quality friction stir welding. At the same time, using the device of the present invention to perform friction stir welding does not require additional devices and procedures to eliminate welding residual stress, and the device of the present invention is especially suitable for FSW of heterogeneous plates, which reduces production costs and improves production efficiency.

Description of drawings

Fig. 1 is a schematic diagram of the arrangement of heat source points in the present invention.

Fig. 2 is a schematic diagram of the structure in use state of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiment one.

As shown in Figure 1.

A method that can effectively reduce/eliminate the residual stress of friction stir welded plates, the key of which is to set a number of heat source points at the position opposite to the weld seam and on both sides of the backing plate for friction stir welding to form an array arrangement, each heat source The point uses high-frequency induction coil heating to generate heat, so that the heat source generated by the heat source point matches the heat generated by the friction stir welding process. Its array point heat source can produce different residual stress for different types of plates due to different material properties. Control and maintain a certain amount of heat until the end of the entire welding process, reduce the temperature gradient between the welding area of the stirring head and the welded area, after the welding is completed, control the heat production of the heat source, keep the welding plate warm, and eliminate the heat in the joint Mechanical residual stress, reduce and eliminate the residual stress of welded joints.

As shown in Figure 1, specific measures include the following:

1. Select the heat source point 2 along the center line of the length direction on the steel plate 1. The size of the heat source point 2 is determined by the size of the stirring head. The number of heat source points 2 is determined by the length of the plate to be welded. The heat source points are arranged in an array. The distance between the two heat source points is 5mm-500mm, the best is 20mm-200mm; the heat of the heat source point comes from the conduction of heat generated by the high-frequency induction coil 3 heating the iron core (that is, the cylinder 5), and the high-frequency induction heating coil 3 The time required to heat the iron core from room temperature (20°C) to 500°C is 15s.

2. Open slots 4 corresponding to the number of heat source points on the backing plate. One end of the slot 4 is the edge of the backing plate, and the other end is an arc that matches the size of the high-frequency induction heating coil 3. The center of the arc is located directly below the heat source point 2. , When slotting, take the center of the arc as the dot to reserve a diameter suitable for the size of the coil and the thickness of the plate. The cylinder 5 is used as a heating iron core.

3. Install the high-frequency induction heating coil 3 in the groove 4. The size of the high-frequency induction heating coil 3 is related to the heating requirements, and the diameter is 25mm-100mm. The coil is replaced by a copper tube 6 passing through cooling water. The outer diameter is 10mm-30mm, the inner diameter is 5mm-15mm, and the high-frequency induction heating coil 3 is connected with the control box 7 .

4. Place an infrared thermometer 8 on the outside of the slot, and the temperature measuring point 9 is located at a distance of 1-10mm from the cylinder 5 to the surface of the backing plate.

Example 2.

As shown in Figure 1.

It is used in friction stir welding and can effectively reduce/eliminate the residual stress of friction stir welding plates, which includes a steel backing plate 1 (it can also be a titanium alloy plate, a tungsten alloy plate, a molybdenum alloy plate and other metal dissimilar material plates) , as shown in Figure 1, the size of the backing plate 1 is 800mm×400mm×30mm, and 12 circular areas are selected on the backing plate 1 along the centerline of the length direction and on both sides as the heat source point 2, and the diameter of the circular area is 10mm. The heat source point 2 in the middle is located at the geometric center of the backing plate surface, 12 heat source points 2 are arranged in an array, and the distance between the two heat source points 2 is 100mm (can also be selected between 5mm-500mm); the heat source point 2 It comes from the conduction of heat generated by the high-frequency induction coil heating the cylindrical iron core 5. The time required for the high-frequency induction heating coil 3 to heat the iron core 5 from room temperature (20°C) to 500°C is 15s; the diameter of the high-frequency induction heating coil 3 The high-frequency induction heating coil 3 is a copper tube 6 with an outer diameter of 10 mm and an inner diameter of 5 mm, and cooling water is passed through the copper tube 6; in order to install the high-frequency induction heating coil 3, five grooves 4 are opened on the backing plate, The groove width is 30mm and the height is 25mm. One end of the groove 4 is the edge of the backing plate, and the other end is an arc with a diameter of 30mm. The center of the arc is located directly below the heat source point 2. When slotting, the center of the arc is used as a dot to reserve a diameter of 10mm. , long 25mm cylinder 5 is used as iron core, and during specific implementation, iron core also can be formed by welding, screwing, riveting; Place infrared thermometer 8 outside the slot hole, temperature measuring point 9 is positioned at iron core 5 5mm away from the surface of the backing plate; the copper tube 6 and the infrared thermometer 8 are connected to the control box 7, and the control box 7 controls the temperature of the heat source according to the control strategy.

as shown in picture 2. Before the friction stir welding, the 6mm thick 2024 aluminum alloy 11 and Q235A steel 12 dissimilar plates to be welded are placed on the backing plate 1, and the position of the stirring head 10 is adjusted so that it is placed above the first heating point 2. Welding is carried out according to the heat source temperature control strategy formulated according to the welding parameters of 6mm thick aluminum alloy/steel dissimilar materials. With the rotation and feeding motion of the stirring head 10, the heat generated by the high-frequency induction coil 3 causes the heat source point out of the welding path to produce a temperature field that changes with the stirring and feeding motion under the action of the control strategy. The temperature field generated by the heat source remains consistent, reducing the residual stress caused by the uneven heat generated by the stirring head. In the welded area, the temperature of the aluminum alloy sheet is kept at 450°C by controlling the point heat sources on both sides, and the temperature of the steel is kept at 900°C until the welding process is completed. Due to the use of different sheets, the material properties of the two metals are different. The point heat source needs to be cooled to different degrees to reduce the temperature gradient between the welding area and the welded area of the stirring head 10, and reduce the residual stress caused by the thermal gradient. After the welding is completed, control the heat production of the point heat source on the aluminum alloy side to keep the temperature of the aluminum alloy welding plate at 200°C and keep it warm for 0.5 hours; control the heat production of the heat source point on the steel side to keep the temperature of the steel plate at 600°C , and keep it warm for 1 hour to eliminate the mechanical residual stress in the joint.

Friction stir welding through the backing plate used in friction stir welding that can reduce/eliminate the residual stress of the friction stir welded plate can essentially reduce the generation of residual thermal stress, eliminate the residual mechanical stress in the joint, and more effectively reduce the friction stir welded joint. Internal residual stress, especially suitable for FSW of dissimilar plates, shortens the annealing time, improves the quality and production efficiency of plate friction stir welded joints.

The parameters of this embodiment are designed according to the specific welding dissimilar materials. During specific implementation, those skilled in the art can properly adjust each specific parameter according to the technical inspiration of the present invention to realize low-application friction stir welding.

The parts not involved in the present invention are the same as the prior art or can be realized by adopting the prior art.

Claims (6)

1. a kind of method that can effectively reduce/eliminate agitating friction welded blank residual stress, it is characterized in that in agitating friction weldering It connects and several hot source points is set with weld seam relative position and both sides, and arrange by array on backing plate, it is dotted to form array Heat source, each hot source point generate heat using radio-frequency induction coil heating, the heat source that hot source point generates are made to be taken over agitating friction weldering The heat that journey generates matches, and array point-like heat source is for xenogenesis plank because generating different remnants during material properties difference The characteristics of stress, controls into trip temperature；In the welding process, existed by the way that array point-like heat source is controlled to simulate FSW process stirring-heads The Temperature Distribution generated in welding process makes welded blank uniformity of temperature profile, reduces the temperature gradient in welded blank, subtracts Few residual stress generated because of thermal gradient；After the completion of welding, the quantity of heat production of hot source point is controlled, welded blank is made to keep setting Temperature, eliminate connector in mechanical residual stress.

2. the according to the method described in claim 1, it is characterized in that hot source point（2）By high-frequency induction heating coil（2）Add Hot iron core and formed, high-frequency induction heating coil（3）By controller（7）Control its heating power and heating time；Each heat source Point can be controlled individually, and can form different heat sources by array arrangement is distributed.

3. method according to claim 1 or 2, it is characterized in that size of the diameter of the hot source point by stirring-head It determines, radius 0.1mm-100mm；The quantity of hot source point is by needing the length of welded blank to determine, ranging from 1-100 It is a；The spacing range of two hot source points is 5mm-500mm；The size of the high-frequency induction heating coil and heating requirements phase It closes, a diameter of 25mm-100mm, the outer diameter for leading to the copper pipe of cooling water is 10mm-30mm, internal diameter 5mm-15mm；Described is infrared The temperature measuring point of temperature measurer, which is located at, to be formed on the cylinder of high-frequency induction heating iron-core coil, and temperature measuring point is from pad surfaces 1-10mm.

4. according to the method described in claim 1, it is characterized in that the backing plate is steel plate, titanium alloy sheet, tungsten alloy plate or molybdenum Alloy sheets.

5. a kind of device that can effectively reduce/eliminate agitating friction welded blank residual stress, it includes backing plate（1）, it is special Sign is the backing plate（1）Multiple hot source points are equipped with weld seam relative position（2）, multiple hot source points（2）It arranges in array； Each hot source point（2）By high-frequency induction heating coil（3）It heats iron core and is formed, high-frequency induction heating coil（3）By controller （7）Control its heating power and heating time；The iron core is located at hot source point lower part, by the copper pipe for leading to cooling water（6）It is formed High-frequency induction heating coil（3）It is wrapped on the iron core, leads to the copper pipe of cooling water（6）Inducer and the equal position of outlet section In slot（4）In, iron core is by being located at slot（4）The circle pile body of one end（5）It is formed；In the slot（4）Infrared radiation thermometer is installed outside （8）, infrared radiation thermometer（8）With controller（7）Electrical connection.

6. device according to claim 5, it is characterized in that being provided with identical with hot source point quantity be used on the backing plate The slot of high-frequency induction heating coil windings, one end of slot is backing plate edge, and the other end is mutually fitted for high-frequency induction heating coil size The circular arc answered, center of arc are located at immediately below hot source point, retain diameter and coil size by dot of center of arc in fluting With the cylinder that sheet metal thickness is adapted as heating iron core；High-frequency induction heating coil is mounted in slot, high-frequency induction heating The size of coil is related to heating requirements, and high-frequency induction heating coil is formed by the copper pipe coiling for leading to cooling water and connected with control cabinet It connects；Infrared radiation thermometer is placed on the outside of slot, measures radio-frequency induction coil heating temperature, temperature measuring point is located at cylinder apart from backing plate At the 1-10mm of surface.