CN109899473B

CN109899473B - Ball screw pair and sealing structure

Info

Publication number: CN109899473B
Application number: CN201910191335.9A
Authority: CN
Inventors: 赵洁
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-03-14
Filing date: 2019-03-14
Publication date: 2022-06-03
Anticipated expiration: 2039-03-14
Also published as: CN109899473A

Abstract

The invention discloses a ball screw pair and a sealing structure, wherein the sealing structure is used for sealing the ball screw pair, and a connector is arranged at the end part of a nut or the end part of a nut assembly of the ball screw pair; providing a sealing assembly fixedly connected with the connector, wherein the inner surface of the sealing assembly is provided with a sealing thread, and the sealing thread is screwed with a lead screw of the ball screw pair to form a contact type sealing sliding pair; the nut assembly refers to an assembly formed by matching two nuts. According to the invention, the sealing capability of the ball screw pair can be improved.

Description

Ball screw pair and sealing structure

Technical Field

The invention relates to a ball screw pair and further relates to a sealing structure of a nut on the ball screw pair.

Background

The known ball screw assembly (GB/T17587.3-1998) consists of a screw (also called a screw), a nut (also called a nut), rolling elements, a pre-compression piece, a reverser and a dust catcher, wherein the rolling elements are balls, which is the origin of the name of the ball screw. The basic principle of the ball screw assembly is that arc-shaped spiral grooves are processed on a screw and a nut, the screw and the nut are matched to form a spiral raceway, balls are filled in the raceway, and the friction between the screw and the nut is rolling friction.

When the screw rod is used as the driving component, the nut can be converted into linear motion along with the rotation angle of the screw rod according to the thread pitch of the corresponding specification, and the driven component can be connected with the nut through the nut seat, so that the linear motion of the driven component is realized. The balls located in the raceways are used for load transfer between the nut and the screw. Compared with the traditional trapezoidal lead screw (namely a lead screw and nut sliding pair), the ball lead screw pair has the characteristics of small friction force and high transmission efficiency based on rolling friction, so that the ball lead screw pair is widely applied to the fields of machine tools and the like. However, the contact angle α of the conventional ball screw pair is generally not greater than 45 °, thereby limiting the improvement of the axial rigidity and the transmission efficiency of the ball screw pair.

In order to improve the bearing capacity and transmission efficiency of the ball screw assembly, chinese patent document CN108757871A discloses a ball screw assembly having balls as rolling elements interposed between a screw shaft (i.e., a screw) and a screw nut (i.e., a nut). In chinese patent document CN108757871A, both the outer cylindrical surface of the screw shaft and the inner cylindrical surface of the screw nut have threads, the threads of the screw shaft and the threads of the screw nut are disposed in an axially intersecting manner, that is, the helical teeth of the screw shaft are located between helical tooth grooves of the screw nut, the helical teeth of the screw nut are located between helical tooth grooves of the screw shaft, and a plurality of balls are located in helical channels on both sides of the helical teeth of the screw shaft and the helical teeth of the nut, wherein either one of the ball tracks can be used as a load-running ball track of the balls, and the other ball track can be used as a no-load return ball track of the balls, and since the contact angle between the balls and the helical track can be generally greater than 45 °, the axial rigidity and the transmission efficiency of the ball screw assembly can be improved compared to the conventional ball screw assembly.

Although chinese patent document CN108757871A proposes a new type of nut screw pair to increase the axial rigidity and transmission efficiency of the nut screw pair, it does not relate to the sealing problem of the ball screw pair, and if the sealing problem cannot be solved, the reliability of the use cannot be guaranteed.

The inventors of the present invention have further studied the sealing problem of the tapered roller screw pair, and have proposed an invention patent application having an application number of "2019101608604" and an invention name of "tapered roller screw pair and sealing structure" on 3.3.2019, and have also further studied the possibility of using the sealing structure in the ball screw pair.

Regarding the sealing of the ball screw assembly, typically, as in chinese patent document CN108138924A, it indicates a general assembly structure of the screw device, and a sealing ring mounted on the nut for preventing foreign matters from entering the interior of the nut, the sealing ring is relatively short in the axial direction of the nut and is substantially sheet-shaped, and the sealing capability is greatly limited by its own axial structure.

For example, chinese patent document CN107532698A discloses a ball screw for reducing fine particles entering the nut based on the pressure difference between the inside and outside of the sealed cavity of the nut, in which two ends of the nut are assembled with sealing members, and the side of the nut is provided with an air inlet hole, so that the pressure inside the nut is higher than the pressure outside, thereby preventing the fine particles from entering the nut. The sealing component is a contact sealing component, but the structure of the contact sealing component is not described in detail, and the contact sealing component is a component of a shaft seal structure, and a hole part of the contact sealing component is made of relatively flexible materials to keep contact, similar to a shaft seal. Because the nut in the screw nut lead screw mechanism usually belongs to a reciprocating part, the movement interference problem needs to be considered for parts such as a gas distribution pipeline and the like arranged on the nut, and the design difficulty of products is increased. For the shaft seal type structural member, the wear resistance of the shaft seal type structural member needs to be considered, the axial length of the shaft seal type structural member is relatively small, and relatively high sealing capacity is realized mainly by contact.

Disclosure of Invention

The invention aims to provide a ball screw pair with relatively high sealing capacity and further provides a sealing structure adaptive to the ball screw pair.

According to an embodiment of the present invention, a sealing structure is provided for sealing a ball screw pair, wherein a connector is provided at a nut end portion or a nut assembly end portion of the ball screw pair;

providing a sealing assembly fixedly connected with the connector, wherein the inner surface of the sealing assembly is provided with a sealing thread, and the sealing thread is screwed with a lead screw of the ball screw pair to form a contact type sealing sliding pair;

the nut assembly refers to an assembly formed by matching two nuts.

The above sealing structure, optionally, the sealing assembly is an integral structure; or

The seal assembly includes:

the sealing seat is a pipe sleeve piece, and one end of the sealing seat is connected with the nut;

the spiral sealing ring is a sealing sleeve embedded in the sealing seat, and the inner surface of the sealing sleeve provides the sealing thread.

Optionally, the spiral sealing ring is in interference fit with the sealing seat.

Optionally, the seal seat and the spiral seal ring further have:

the sealing seat is provided with a radial fastening screw hole for locking and fixing the sealing seat and the spiral sealing ring; or:

the seal receptacle is equipped with the retaining ring in the one end that deviates from the nut to be used for the spiral sealing washer at the axial spacing of seal receptacle.

Optionally, the retainer ring is a spring retainer ring; or:

the retaining ring is designed as a screw sealing retaining ring, one end of which is connected to the end of the sealing seat facing away from the nut.

Optionally, the helical sealing collar has a helical groove of the same shape as the screw thread, which is screwed to the screw thread with a fitting clearance for forming a non-contact sealing structure.

Optionally, the connection structure between the spiral sealing retainer ring and the sealing seat is as follows:

the spiral sealing retainer ring is provided with an assembling part and a positioning part, wherein the assembling part is an end cover with internal threads, and the assembling part is provided with at least two arc-shaped assembling holes;

the positioning part is an internal thread sleeve body extending from the assembling part to the side where the sealing seat is located, and the sleeve body extends into the sealing seat and is used for axially positioning the spiral sealing ring;

correspondingly, the end part of the sealing seat is provided with a screw hole, a screw is provided, and the spiral sealing check ring is assembled on the sealing seat through the arc-shaped assembling hole.

Optionally, the outer diameter of the positioning part is smaller than the inner diameter of the sealing seat, so as to form a radial adjusting gap of the spiral sealing retainer ring;

accordingly, the arc-shaped assembling hole is a smooth hole, and the width of the arc-shaped hole is larger than the major diameter of the screw for assembling the assembling portion.

Optionally, the outer surface of the helical sealing ring has an external thread;

correspondingly, the inner surface of the sealing seat is provided with an internal thread matched with the external thread.

Optionally, one end of the sealing assembly connected with the nut connector is a stepped hole;

correspondingly, the connector is provided with a step shoulder, and a shaft hole is formed between the step shoulder and the step hole for matching;

wherein, the sealing assembly is provided with a fastening screw hole at the step hole;

and providing a fastening screw screwed into the fastening screw hole for locking the sealing assembly and the connector.

Optionally, at least one sealing ring is arranged on the matching surface of the step shoulder and the step hole.

Alternatively, the shape of the thread groove of the sealing thread is the same as the shape of the screw thread teeth of the screw.

Optionally, a spiral channel is formed on each of two sides of the nut thread of the ball screw pair;

correspondingly, the side thread of the nut extends into the side screw groove of the screw rod, a spiral channel is determined by the side screw thread and the side screw thread which determines the spiral groove on one axial side, and another spiral channel is determined by the other side screw thread and the other side screw thread which determines the spiral groove on the other axial side;

balls are continuously arranged in the spiral channel along the direction of the channel;

correspondingly, reversers are fitted at both ends of the raceway.

According to an embodiment of the invention, the ball screw pair with the sealing structure is also provided.

According to the embodiment of the invention, the two ends of the ball screw pair are respectively provided with the spiral sealing structures based on the sliding friction structure, and the sliding pair formed by matching the spiral sealing ring and the screw rod of the sealing assembly provides relatively reliable contact type sealing, so that the leakage amount of the lubricant can be reduced, and meanwhile, the fine dust is prevented from entering the ball screw pair.

Drawings

Fig. 1 is an axial sectional view of a ball screw assembly according to a first embodiment of the present invention.

Fig. 2 is a schematic axial cross-section of a screw according to a first, second, third and fourth embodiment of the invention.

Fig. 3 is a schematic axial cross-sectional view of the spiral seal ring according to the first, second, third and fourth embodiments of the present invention.

Fig. 4 is a schematic structural diagram of the external shape of the spiral sealing ring in the first, second, third and fourth embodiments of the present invention.

Fig. 5 is a schematic axial cross-sectional view of a spiral sealing gasket according to the first and second embodiments of the present invention.

Fig. 6 is a schematic structural diagram of the external shape of the spiral sealing retainer ring in the first and second embodiments of the invention.

Fig. 7 is a schematic axial cross-sectional view of a spiral seal ring, a spiral retainer ring and a lead screw according to the first and second embodiments of the present invention.

Fig. 8 and 9 are schematic diagrams of fit clearances between the spiral sealing retainer ring and the screw rod in the first embodiment and the second embodiment of the invention.

Fig. 10 is an axial cross-sectional view of the seal holder according to the first embodiment of the present invention.

Fig. 11 is a schematic external view of the seal seat according to the first embodiment of the present invention.

Fig. 12 is a schematic axial cross-sectional view of a seal holder, a spiral seal ring and a spiral retainer ring according to the first embodiment of the present invention.

Fig. 13 is a schematic radial cross-sectional view of a screw, a seal holder and a spiral seal ring according to the first, second, third and fourth embodiments of the present invention.

FIG. 14 is a schematic view of the mounting seal assembly end of the nut and the reverser in accordance with the first and third embodiments of the present invention.

Fig. 15 and 16 are schematic structural views of the mounting seal assembly end of the nut in the first and third embodiments of the invention.

Fig. 17, 18 and 19 are schematic structural views of the ball reverser in the first and third embodiments of the present invention.

Fig. 20 is a schematic view showing a structure of a packing between the bottom of the ball reverser and the nut in the first and third embodiments of the present invention.

Fig. 21 is a schematic view of the nut, ball reverser and ball combination in the first and third embodiments of the invention.

FIG. 22 is a schematic view of the seal assembly and nut assembly of the first embodiment of the present invention.

Fig. 23 is an axial sectional view of a ball screw assembly according to a second embodiment of the present invention.

FIG. 24 is an axial cross-sectional view of a seal holder according to a second embodiment of the present invention.

FIG. 25 is a schematic external view of a seal holder according to a second embodiment of the present invention.

Fig. 26 is a schematic axial cross-sectional view of a seal holder, a spiral seal ring and a spiral retainer ring according to a second embodiment of the present invention.

Fig. 27 and 28 are schematic structural views of the mounting seal assembly end of the nut in the second and fourth embodiments of the invention.

Fig. 29 and 30 are schematic structural views of the ball reverser in the second and fourth embodiments of the present invention.

Fig. 31 is a schematic view showing a structure of a packing between the bottom of the ball reverser and the nut in the second and fourth embodiments of the present invention.

Fig. 32 is a schematic view of the nut, ball reverser and ball in accordance with the second and fourth embodiments of the present invention.

FIG. 33 is a schematic view of the seal assembly and nut assembly of the second embodiment of the present invention.

Fig. 34 is an axial sectional view of a ball screw assembly according to a third embodiment of the present invention.

Fig. 35 is an axial cross-sectional view of a ball screw assembly according to a fourth embodiment of the present invention.

In the figure, 1, a screw rod; 1a, 1b. a first side; 1c. a first top surface; 1d, a first bottom surface; 2. a nut; 2a, a first action surface; 2b, wedge surface; 21. a first screw hole; 22. a first O-shaped seal groove; 23. a first notch; 24. a second screw hole; 26. a first seal groove; 27. a first oil filler hole; 3. a ball bearing; 4. an inverter; 4a, a reverse guide action surface; 4b, positioning a surface; 41. a second O-shaped seal groove; 42. a third screw hole; 44. a second seal groove; 5. a sealing seat; 5a, a second action surface; 5b. a third acting surface; 51. sealing seat internal threads; 52. a third O-shaped seal groove; 53. a second notch; 54. a fourth screw hole; 55. a fifth screw hole; 56. a third notch; 6. a spiral seal ring; 61. a first helical groove; 6a, 6b. second side; 6c. a second bottom surface; 6d, a central hole wall of the spiral sealing groove; 62. a second helical groove; 7. a retainer ring; 7a, 7b. a third side; 7c. a third bottom surface; 7d, a fourth acting surface; 71. a third helical groove; 72. an arc-shaped hole; an O-shaped seal ring; 9. 10, fastening screws; 11. a gasket; delta₁、Δ₂A radial gap; delta₃、Δ₄Axial clearance.

Detailed Description

The ball screw pair is called as a ball screw nut pair, the thread raceway profile of the conventional ball screw pair is a single arc or a double arc, and the contact angle of the ball in the raceway is usually 45 degrees. The rolling track profile of the ball screw pair disclosed in chinese patent document CN108757871A is based on a structure in which the threads of the screw and the nut are arranged in an axial direction in a crossed manner, that is, the threads of the screw are inserted into the thread groove of the nut, and the threads of the nut are inserted into the thread groove of the screw, so that two spiral ball movement channels are formed on both sides of one thread, and the side surface of the thread is used as the rolling track surface of the ball, which can significantly increase the contact angle between the ball and the rolling track, thereby improving the axial rigidity and the transmission efficiency of the ball screw pair.

The invention is a sealing device designed on the basis of the ball screw pair disclosed in the Chinese patent document CN108757871A, and improves the structure of the ball screw pair according to the sealing requirement, and the application range is described by taking the ball screw pair disclosed in the Chinese patent document CN108757871A as an example. Here, the entire contents of chinese patent document CN108757871A are incorporated herein by reference.

It will be appreciated by those skilled in the art that the balls 3 are distributed within the confines of the nut 2 and that the sealing arrangement needs to be provided at both ends of the nut 2 or nut assembly.

The first embodiment:

a first embodiment of a ball screw assembly and a seal structure thereof according to the present invention will be described below with reference to fig. 1 to 22.

First, the basic structure of the ball screw assembly is described in the foregoing, but a ball screw assembly in which the screw threads of the screw and the nut are arranged to intersect in the axial direction can be found in chinese patent document CN108757871A, which describes in more detail a ball screw assembly having dual raceways, and the basic structure is completely the same except that the sealing structure is different, and the rest is only the difference in terms of names.

As shown in fig. 1 and 2, the conventional lead screw and the lead screw 1 shown in fig. 1 and 2 both adopt a basic external thread structure, and the difference is that the thread form of the external thread is different, the thread form depth of the conventional lead screw is relatively small, and the conventional lead screw is used for partially accommodating the ball 3, while the thread form of the lead screw 1 shown in fig. 1 and 2 has enough depth to completely accommodate the ball 3.

In addition, the raceway of the conventional screw is not only shallow but also relatively simple, the depth of the raceway is smaller than the radius of the balls 3, and the profile of the raceway is arc-shaped. The raceway shown in fig. 1 on the side of the screw 1 cannot carry the balls 3 independently and needs to cooperate with the threads on the nut 2 to define the raceway.

The screw thread 1 side and the nut 2 side form a raceway of the ball 3 by the thread side, and therefore, the thread height is larger than the diameter of the ball 3. Meanwhile, the ball 3 is not directly contacted with the first bottom surface 1d shown in fig. 2 and the thread bottom of the nut 2 side by the roller path determined by the thread of the screw 1 side and the thread of the nut 2 side, and the movement interference is reduced.

Specifically, the screw 1 side is provided with an external thread, the nut 2 side is provided with an internal thread, the thread forms of the internal thread and the external thread are matched, as can be clearly seen in fig. 1, the thread large part on the nut 2 side is positioned between the adjacent threads on the screw 1 side and is arranged in the middle, and the raceway of the ball 3 is determined between the adjacent threads on the nut 2 side and the screw 1 side.

As can be seen from fig. 2, the

first side surfaces

1a, 1b of the screw thread 1 have a raceway portion, in other words, both side surfaces of the screw thread 1 are provided with raceway portions. Suitably, as can be seen from fig. 1, the two side faces of the nut 2-side thread, which partially project between the adjacent threads on the screw 1 side, also each form a raceway portion.

Further, the nut 2 side raceway portion and the screw 1 raceway portion define an integral raceway for making the running route of the balls 3.

Each raceway forms a closed loop at both ends of the thread of the nut 2, so that the raceways form a complete closed loop.

In some applications, the balls 3 also have an outer circulation structure, i.e. they are not directly formed into a closed loop on the thread pair, but are conveyed from one end to the other end by providing an external connecting channel on, for example, the nut 2, thereby connecting the two ends of the raceway into a closed loop. The invention is also applicable to the method, namely, the raceway is opened in an open loop, an external channel is matched at the open loop, and two ends of the open loop are connected to form a complete closed loop.

In the case of a closed-loop raceway constructed directly in the thread pair part, the raceway is correspondingly helical, and a reverser 4 is provided at the end of the internal thread of the nut 2 for communication between the two raceways in which the balls 3 circulate during rolling. This structure is described in more detail in chinese patent document CN108757871A, and is not described in detail here.

The counter-guide-acting surface 4a on the reverser 4 is located inside the nut 2 and faces the end of the internal thread of the nut 2, so that the balls 3 can pass back from either side of the internal thread of the nut 2 into the other side of the internal thread of the nut 2.

In the structure shown in fig. 1, two ends of the nut 2 are respectively provided with a connector, the connectors shown in the figure are in a shaft head structure, the end of the nut 2 of the sealing seat 5 is sleeved on the shaft head, and then a jackscrew (i.e., a set screw) is used for locking.

The sealing assembly is constructed by taking the sealing seat 5 as a base body, and for the sealing assembly, the sealing assembly can be a single body structure, such as polytetrafluoroethylene or modified polytetrafluoroethylene with better sealing and wear-resisting properties, and a component for forming a polytetrafluoroethylene layer by spraying on a rigid body piece.

The sealing assembly can also be a split structure, and the split structure is favorable for reducing the overall cost by assembling to form the assembly, so that the whole sealing assembly is not required to be made of the same expensive material, and the material selection margin is large.

The arrangement shown in figure 1 is provided with only one nut 2 and in connection with a nut screw mechanism, in some applications there will be double nuts which fit together and it will be necessary to seal the two ends of the nut assembly formed by the assembly of the double nuts. Correspondingly, the two ends of the nut assembly are provided with connectors, and the rest of the structure is the same as the structure of the single nut 2.

In the construction shown in fig. 1, the sealing assembly is a multi-piece construction assembly, which in the figure comprises a sealing seat 5, a helical sealing ring 6, a collar 7 (the inner part of the collar 7 as a whole is also a helical construction forming a sliding fit with the screw spindle 1) and an O-ring 8.

The spiral sealing ring 6 and the sealing seat 5 are both of pipe sleeve structures, the sealing assembly is equivalent to the splicing nut 2, although the total length of the nut 2 is increased on the whole, the sealing reliability is better, and therefore the sealing device has better working conditions and longer service life.

Correspondingly, a thread pair is formed between the sealing assembly for splicing the nut 2 and the screw rod 1, and the thread pair formed between the sealing assembly and the screw rod 1 is in sliding friction relative to the ball screw pair. As described above, since the nut 2 is the main bearing portion, the positive pressure between the seal assembly and the screw 1 is relatively small, the generated friction force is also relatively small, and the effect on the efficiency of the ball screw pair is relatively small when the ball screw pair is formed as a sliding friction pair.

The part of the sealing assembly for forming the friction pair has better sealing performance and can meet the requirements of dynamic sealing, and the sealing in the screw nut and screw mechanism belongs to common sealing, but not belongs to high-temperature sealing (the working temperature is higher than 120 ℃) or pressure sealing, so the technical requirements are relatively low, and the materials based on the dynamic sealing can be used.

When the first part forming the friction pair and the second part connected with the nut 2 are of a split structure, the second part can be a rigid part, such as a metal part, and the first part adopts a flexible wear-resistant sealing element, such as a felt ring, a framework oil seal, a resin or nylon sealing element, and the like, and the dynamic sealing elements are suitable for a contact type sliding sealing structure.

The second part is fixedly connected with the nut 2, and the formed sealing structure belongs to static sealing, so that the sealing capability is easy to guarantee.

In the structure shown in fig. 1, an O-ring 7 is further provided between the second part, i.e. the sealing seat 5, and the joint surface of the nut 2, so as to improve the sealing capability of the static seal.

The O-shaped sealing ring 7 can be made of rubber or resin material.

With regard to the constraint of the balls 3, i.e. their confinement in the raceways so that they run along the raceways, the profile of the balls 3 is spherical, which is relatively simple to constrain, as shown in fig. 2, grooves are formed in the first side faces 1a, 1b, which grooves extend along the thread profile, also substantially helical. The cross-sectional radius of curvature of the groove is slightly larger than the radius of curvature of the ball 3.

As shown in fig. 3, the spiral seal ring 6 is of a pipe sleeve structure, and a spiral groove is formed in the pipe sleeve, namely, a first spiral groove 61 shown in fig. 3, and the shape and the pitch of the first spiral groove 61 are the same as those of the spiral teeth of the screw rod 1.

Since the spiral seal ring 6 does not need to consider the problem of constructing the raceway, the structure thereof can now form the thread of the tube seal, the thread of the spiral seal ring 6 as a whole adopts a trapezoidal thread structure, and the side surface of the thread of the spiral seal ring 6 is provided with the spiral groove as described above, and for the fitting seal, as shown in fig. 3, the side surface of the thread of the spiral seal ring 6 is provided with the spiral ridge which is fitted to the spiral groove of the side surface of the thread of the screw 1.

As shown in fig. 4, the spiral seal ring 6 has a second spiral groove 62 on the outer circumferential surface thereof, and the pitch thereof is the same as that of the first spiral groove 61. The seal formed between the peripheral surface of the spiral sealing ring 6 and the sealing seat 5 belongs to static seal, the requirement is relatively low, pure pipe threads can be adopted, and the sealing interface can be coated with a sealing glue.

As shown in fig. 5 and 6, the retainer 7 is formed as an end cap having a central hole for the screw 1 to pass through, and an arc-shaped hole 72 serving as a fitting hole for the retainer 7 to be fitted to the end of the seal holder 5 by a screw.

The securing ring 7 has an end-cap-like mounting portion, i.e. a portion provided with a mounting hole (arc-shaped hole 72) and a portion having a fourth active surface 7d in the drawing, which is denoted as a positioning portion, which projects into the sealing seat 5 for axial positioning of the spiral sealing ring 6.

The positioning part is of a pipe sleeve structure, and the outer diameter of the positioning part is smaller than the inner diameter of the sealing seat 5, so that the radial adjustment of the retainer ring 7 can be obtained.

And a third spiral groove 71 with the same shape as the spiral tooth of the screw rod is arranged in the central hole of the retainer ring 7, and is used for non-contact sealing of the ball screw rod pair under the condition of realizing positioning and locking.

As shown in fig. 7, the internal thread of the spiral sealing ring 6 is completely matched with the external thread surface of the screw rod 1 to form a sliding pair, specifically: two second side surfaces 6a and 6b of a first spiral groove 61 of the internal thread of the spiral sealing ring 6 are respectively in close contact with first side surfaces 1a and 1b of the external thread of the screw rod 1, a second bottom surface 6c of the first spiral groove 61 is in close contact with a first top surface 1c of the external thread of the screw rod 1, and a central hole wall 6d (crest) of the spiral sealing ring 6 is in close contact with a first bottom surface 1d (root) of the external thread of the screw rod 1.

As shown in fig. 8 and 9, the third spiral groove 71 of the retainer 7 is engaged with but not contacted with the spiral teeth of the screw rod 1, the retainer 7 is a spiral sealing retainer in the figure, the size of the third spiral groove 71 is larger than that of the spiral teeth of the screw rod, and the fit clearance between the retainer 7 and the screw rod 1 has a radial clearance delta₁、Δ₂And axial clearance delta₃、Δ₄The sizes of the two gaps are preferably 0.2-0.3 mm. Radial clearance delta₁、Δ₂Is adjusted by adjusting the radial eccentricity of the retainer ring 7 relative to the axial center of the screw 1, and the maximum value of the eccentricity is defined by the size of the gap between the third acting surface 5b and the fourth acting surface 7d. Axial clearance delta₃、Δ₄Is adjusted by adjusting the rotation angle of the retaining ring 7 around the axis of the screw rod 1 relative to the nut 2, and the value of the rotation angle is larger than the axial clearance of the screw rod pair of the screw nut.

The retainer ring 7 of the sealing assembly is matched with the screw rod 1 at the axial outer side of the contact type sealing element to form a non-contact type sealing structure, so that the sealing assembly has scraping capability on large hard pollutants attached to the surface of the screw rod 1, but cannot play a sealing role on fine dust. In the working condition environment with larger particle pollutants, the adoption of the spiral sealing check ring can also allow the axial length of the contact type spiral sealing ring to be properly reduced, so that the friction torque of the sealing sliding pair is reduced.

The arcuate hole 72 produces a circumferential adjustment in the presence of the aforementioned axial clearance delta₃、Δ₄The size of the axial gap can be adjusted by the arc-shaped hole 72. With a defined lead of the spindle 1, the axial play Δ is defined₃、Δ₄Is determined by the arc angle of the arcuate aperture 72.

And for a radial clearance delta₁、Δ₂It is determined based on the fit of the screw with the arc-shaped hole 72 and the fit of the retainer ring 7 with the seal holder 5. Generally, the arc-shaped assembling holes are usually unthreaded holes, the aperture of each unthreaded hole is larger than the major diameter of the assembling screw, an assembling allowance is formed between the assembling screw and the matched arc-shaped assembling hole, and meanwhile,the outer diameter of the inner part of the securing ring 7 projecting into the sealing seat 5 is smaller than the inner diameter of the sealing seat 5, i.e. a gap remains between the third active surface 5b and the fourth active surface 7d, so that the radial gap Δ is formed₁、Δ₂Can be adjusted.

The assembly holes shown in fig. 6 are arc-shaped holes 72, and the assembly allowance is also present, namely, the width of the arc-shaped holes 72 is larger than the major diameter of the assembly screws. Based on mechanical design criteria and the aforementioned radial clearance delta₁、Δ₂Can be substantially adapted. If the amount of adjustment allowed is large, the arcuate aperture 72 may be widened based on mechanical design criteria.

The material of the retainer ring 7 can be QAL10-3-1.3 aluminum bronze pipe.

In fig. 1 and 23, the retainer 7 is provided with an assembly structure, and in some embodiments, a resilient retainer may be used instead of the retainer 7.

As shown in fig. 10 and 11, the seal holder 5 has a skeleton structure, is a pipe set with relatively high rigidity, and has an inner surface that may be smooth or threaded, and in the structure shown in fig. 10 and 11, the seal holder 5 has an internal thread having the same shape and pitch as the external thread of the spiral seal ring 6, that is, the second spiral groove 62 in fig. 4, and the two are connected by a thread forming foundation.

Furthermore, one end of the seal holder 5 connected to the nut 2 is provided with a second acting surface 5a, a third O-shaped seal groove 52, a second notch 53 and a plurality of fourth screw holes 54 distributed along the circumferential direction, and the fourth screw holes are used for fixedly connecting the seal holder 5 and the nut 2; at least three fifth screw holes 55 distributed along the circumferential direction are formed at one end of the sealing seat 5 facing away from the nut, and are used for fixedly connecting the sealing seat 5 with the retainer ring 7.

When the sealing seat 5 is a smooth hole in the pipe sleeve, an interference fit (also called interference connection) can be adopted between the sealing seat and the spiral sealing ring 6.

In order to improve the reliability of the assembly, a jackscrew hole is formed in the side surface of the sealing seat 5 under the condition of adopting interference fit, and the jackscrew is used for further fixing.

In addition, as mentioned above, the sealing assembly may be an integral structure, such as a nylon sleeve or a resin sleeve, which is internally threaded to form a sliding pair with the screw rod 1.

As shown in fig. 12, the second spiral groove 62 of the spiral sealing ring 6 is attached to the spiral tooth 51 of the sealing seat 5, and may be fixedly coupled by gluing or the like in some embodiments; at the end of the spiral seal 6 remote from the nut 2, a stop ring 7 is provided for the stop of the spiral seal 6 at this end, and accordingly the end face of the spiral seal 6 is in contact with the stop ring 7.

As shown in fig. 13, in the effective sealing range, the internal thread of the spiral seal ring 6 completely fits the external thread of the screw shaft 1, and the external thread of the spiral seal ring 6 completely fits the internal thread of the seal holder 5, so that the lubricant inside the ball screw pair can be prevented from leaking from between the seal holder 5 and the screw shaft 1, and foreign matter such as external dust can be prevented from entering the inside of the ball screw pair from between the seal holder 5 and the screw shaft 1. The effective sealing length of the spiral sealing ring 6 in the axial direction of the screw 1 is determined according to the use requirement of the ball screw, when the ball screw is required to have lower friction torque, the effective sealing length of the spiral sealing ring 6 can be properly reduced, for example, the effective sealing length is 0.2-0.6 times of the lead of the screw thread, and when the sealing effect of the ball screw is required to be improved, the effective sealing length of the spiral sealing ring 6 can be properly increased, for example, the effective sealing length is 1.0-2.0 times of the lead of the screw thread.

As shown in fig. 15 and 16, the nut 2 includes, at its end portion: 1) a first acting surface 2a of the fixed seal holder 5, wherein the first acting surface 2a is provided with a first O-shaped seal groove 22 and a plurality of first screw holes 21 distributed along the circumference; 2) the first notch 23 and the second screw holes 24, 25 of the fixation inverter 4. The first acting surface 2a is matched with the second acting surface 5a of the sealing seat; the first O-shaped sealing groove 22 is matched with a third O-shaped sealing groove 52 on the sealing seat 5 and is used for accommodating the O-shaped sealing ring 8; the side surface of the first notch 23 is a wedge-shaped surface 2b for axially positioning the reverser 4 on the nut 2; the bottom of the first notch 23 is provided with a first sealing groove 26 for placing the sealing gasket 11 between the reverser 4 and the nut 2; a first oil hole 27 is formed in the flange of the nut 2.

As shown in fig. 17, 18, 19, and 21, a reverse guide acting surface 4a for guiding the ball 3 in the reverse direction is provided inside the reverser 4; a positioning surface 4b is arranged on one side of the reverser 4, and the positioning surface 4b is matched with a wedge-shaped surface 2b on the nut 2 to realize the axial positioning of the reverser 4; a second O-shaped sealing groove 41 is formed in the outer cylindrical surface of the end part of the reverser 4 and used for placing an O-shaped sealing ring 8 so as to realize sealing between the reverser 4 and the sealing seat 5; the bottom of the reverser 4 is provided with a second sealing groove 44 for placing a sealing gasket 11 to realize the sealing between the reverser 4 and the nut 2; two third screw holes 42, 43 are provided in the reverser 4 for fixing the reverser 4 to the nut 2.

As shown in fig. 20, the gasket 11 is matched in shape and size to the second seal groove 44 and the first seal groove 26.

As shown in fig. 22, the retainer ring 7 is fixed to the end of the seal holder 5 by a plurality of circumferentially distributed set screws 9, and the seal holder 5 is fixed to the end of the nut 2 by a plurality of circumferentially distributed set screws 10, and in order to avoid interference between the reverser 4 and the seal holder 5, the protruding portion of the reverser 4 is placed in the second notch 53 of the end of the seal holder 5.

Second embodiment:

as shown in fig. 23 and 32, the screw 1 has threads on its outer cylindrical surface and the nut 2 has threads on its inner cylindrical surface, which are correspondingly formed with external threads and internal threads, and the threads of the screw 1 and the nut 2 are arranged in an axially crossing manner, i.e., the thread portion of the nut 2 is interposed between adjacent threads of the screw 1 for defining a raceway.

Furthermore, a plurality of balls 3 are positioned in the roller path determined by the screw rod 1 and the nut 2, are restrained by the roller path and flow along the roller path; the two ends of the thread of the nut 2 are respectively provided with an inverter 4, and an inverse guide action surface 4a on the inverter 4 is positioned on the inner side of the nut 2 and faces the end part of the thread of the nut 2, so that the ball 3 can reversely enter the other side raceway of the thread of the nut 2 from any side raceway of the thread of the nut 2; at least one end of the nut 2 is provided with a sealing device and a sealing assembly, wherein the sealing device comprises a spiral sealing ring 6, a sealing seat 5, an O-shaped sealing ring 8 and a check ring 7; the spiral sealing ring 6 and the sealing seat 5 are both of pipe sleeve structures, and the screw rod 1 penetrates through the nut 2, the spiral sealing ring 6 and the sealing seat 5 to form a thread pair; the sealing seat 5 is fixedly connected with the nut 2; the spiral sealing ring 6 is fixed in the sleeve of the sealing seat 5 and is tightly contacted with the thread of the screw rod 1 and the surface of the thread tooth groove; an O-ring seal 8 is provided between the mating surfaces of the nut 2 and the seal holder 5.

As can be seen from fig. 2, the

first side surfaces

In some applications, the balls 3 also present an outer circulation configuration, i.e. not directly forming a closed loop on the thread pair, but by providing an external connecting channel, for example on the nut 2, feeding the balls from one end to the other, thus connecting the two ends of the raceway in a closed loop. The invention is also applicable to the method, namely, the raceway is opened in an open loop, an external channel is matched at the open loop, and two ends of the open loop are connected to form a complete closed loop.

In the case of a closed-loop raceway constructed directly in the thread pair, the raceway is correspondingly helical, and at the end of the internal thread of the nut 2 there is provided a reverser 4 for communication between the two raceways in which the balls 3 circulate during rolling. This structure is described in more detail in chinese patent document CN108757871A, and is not described in detail here.

The counter guide surfaces 4a on the reverser 4 are located inside the nut 2 and face the end of the internal thread of the nut 2, so that the balls 3 can pass back from either side of the internal thread of the nut 2 into the other side of the internal thread of the nut 2.

As shown in fig. 8 and 9, the spiral groove 71 of the retainer ring 7 is engaged with but not in contact with the spiral teeth of the screw shaft 1, the retainer ring 7 is a spiral sealing retainer ring in the figure, the size of the spiral groove, namely the third spiral groove 71, is larger than that of the spiral teeth of the screw shaft, and the fit clearance between the retainer ring 7 and the screw shaft 1 has a radial clearance delta₁、Δ₂And axial clearance delta₃、Δ₄The sizes of the two gaps are preferably 0.2-0.3 mm. Radial clearance delta₁、Δ₂The size is adjusted by adjusting the radial eccentricity of the retainer ring 7 relative to the axis of the screw 1, and the maximum value is limited by the size of the gap between the third acting surface 5b and the fourth acting surface 7d. Axial clearance delta₃、Δ₄Is adjusted by adjusting the rotation angle of the retaining ring 7 around the axis of the screw rod 1 relative to the nut 2, and the value of the rotation angle is larger than the axial clearance of the screw rod pair of the screw nut.

And for a radial clearance delta₁、Δ₂It is determined based on the cooperation of the screw with the arc-shaped hole 72 and the cooperation of the retainer ring 7 with the seal holder 5. Generally, the arc-shaped assembly holes are usually unthreaded holes, the aperture of each unthreaded hole is larger than the major diameter of each assembly screw, an assembly allowance is formed between each assembly screw and the corresponding arc-shaped assembly hole, meanwhile, the outer diameter of the part, extending into the sealing seat 5, of the retainer ring 7 is smaller than the inner diameter of the sealing seat 5, namely, a gap is reserved between the third acting surface 5b and the fourth acting surface 7d, and therefore, the radial gap delta is formed₁、Δ₂Can be adjusted.

The assembly holes shown in fig. 6 are arc-shaped holes 72, and the assembly allowance is also present, namely, the width of the arc-shaped holes 72 is larger than the major diameter of the assembly screws. Based on mechanical design criteria and the aforementioned radial clearance delta₁、Δ₂Can be substantially adapted. If the allowable adjustment amount is large, the arc-shaped hole 72 can be widened on the basis of the mechanical design criteria.

The material of the retainer ring 7 can be QAL10-3-1.3 aluminum bronze pipe.

As shown in fig. 24 and 25, the seal holder 5 has a seal holder female screw 51 in the center hole thereof, and the shape and pitch thereof are respectively the same as those of the second spiral groove 62 of the spiral seal ring 6; one end of the seal holder 5 is of a flange structure, and a third O-ring seal groove 52 and a plurality of fourth screw holes 54 distributed circumferentially are formed in the second acting surface 5a.

At least three fifth screw holes 55 distributed along the circumferential direction are formed at one end of the sealing seat 5 facing away from the nut, and are used for fixedly connecting the sealing seat 5 with the retainer ring 7.

A plurality of third recesses 56 are formed in the outer cylindrical surface of the sealing seat, which are distributed in the circumferential direction, and the third recesses 56 are located and distributed in the same circumferential direction as the fourth screw holes 54, for receiving the screw caps of the adapted set screws and facilitating the assembly operation of the set screws. The provision of the third notch 56 enables the radial dimensions of the end of connection of the nut 2 and the seal seat 5 to be reduced.

As shown in fig. 26, the second spiral groove 62 of the spiral sealing ring 6 is attached to the spiral tooth 51 of the sealing seat 5, and may be fixedly coupled by gluing or the like in some embodiments; a retainer ring 7 is arranged at one end of the spiral sealing ring 6 far away from the nut 2 and used for limiting the spiral sealing ring 6 at the end, and correspondingly, the end face of the spiral sealing ring 6 is in contact with the retainer ring 7.

In effective sealing range, the internal thread of spiral seal ring 6 and the external thread of lead screw 1 laminate completely to the external thread of spiral seal ring 6 and the internal thread of seal receptacle 5 laminate completely, thereby can prevent that the inside emollient of ball from leaking between seal receptacle 5 and lead screw 1, can prevent simultaneously that foreign matters such as outside dust from getting into inside the ball is vice from between seal receptacle 5 and the lead screw 1. The effective sealing length of the spiral sealing ring 6 in the axial direction of the screw 1 is determined according to the use requirement of the ball screw. When the ball screw is required to have a low friction torque, the effective sealing length of the spiral seal ring 6 can be appropriately reduced, for example, to a value of 0.2 to 0.6 times the lead of the screw thread, and when the sealing effect of the ball screw is required to be improved, the effective sealing length of the spiral seal ring 6 can be appropriately increased, for example, to a value of 1.0 to 2.0 times the lead of the screw thread.

As shown in fig. 27 and 28, the nut 2 includes, at its end portion: 1) a flange for fixing the seal holder 5, which has a first O-ring seal groove 22 and a plurality of first screw holes 21 circumferentially distributed on the first acting surface 2 a; 2) the first notch 23 and the second screw holes 24, 25 of the fixation inverter 4. The first acting surface 2a is matched with the second acting surface 5a of the sealing seat; the first O-shaped sealing groove 22 is matched with a third O-shaped sealing groove 52 on the sealing seat 5 and is used for accommodating the O-shaped sealing ring 8; the side surface of the first notch 23 is a wedge-shaped surface 2b for axially positioning the reverser 4 on the nut 2; at the bottom of the first recess 23 there is a first sealing groove 26 for placing the sealing gasket 11 between the reverser 4 and the nut 2.

As shown in fig. 29, 30, and 32, a reverse guide acting surface 4a for guiding the ball 3 in the reverse direction is provided inside the reverser 4; a positioning surface 4b is arranged on one side of the reverser 4, and the positioning surface 4b is matched with a wedge-shaped surface 2b on the nut 2 to realize the axial positioning of the reverser 4; a second O-shaped sealing groove 41 and two third screw holes 42 and 43 are formed in the end face of the reverser 4, the second O-shaped sealing groove 41 is used for placing an O-shaped sealing ring 8 to realize sealing between the reverser 4 and the sealing seat 5, and the two third screw holes 42 and 43 are used for realizing the fixation of the reverser 4 on the nut 2; at the bottom of the reverser 4 there is a second sealing groove 44 for placing a sealing gasket 11 to achieve a seal between the reverser 4 and the nut 2.

As shown in fig. 31, the gasket 11 is matched in shape and size to the second seal groove 44 and the first seal groove 26.

As shown in fig. 33, the reverser 4 is fixed in the first notch 23 of the end of the nut 2.

As shown in fig. 34, the retainer ring 7 is fixed to the end of the seal holder 5 by a plurality of circumferentially distributed set screws 9; the seal holder 5 is fixed to the end of the nut 2 by a plurality of circumferentially distributed set screws 10.

Third and fourth embodiments:

as shown in fig. 35, which will be referred to as third and fourth embodiments, respectively, the retainer rings 7 of the first and second embodiments are replaced with ordinary circlips, while the spiral seal ring 6 and its contact seal structure are retained. Because the elastic retainer ring does not have the sealing function, compared with the first embodiment and the second embodiment, the two embodiments reduce the capability of the sealing device for scraping off larger hard particle pollutants adhered to the surface of the screw rod, but can simplify the structure and be suitable for a cleaner working condition environment without the larger hard particle pollutants.

The present invention is not limited to the above four embodiments, and may also include other embodiments that can implement the structure and function thereof, for example, when two nuts are mounted on a single screw in pairs, a sealing assembly is disposed at each distal end of the two nuts.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention and do not limit the scope of the present invention, and various modifications and improvements of the present invention may be made by those skilled in the art without departing from the spirit of the present invention as defined by the appended claims.

Claims

1. A sealing structure is used for sealing a ball screw pair and is characterized in that a connector is arranged at the end part of a nut or the end part of a nut assembly of the ball screw pair;

the nut assembly is formed by matching two nuts;

the sealing assembly is of an integrated structure; or

The seal assembly includes:

the spiral sealing ring is a sealing sleeve embedded in the sealing seat, and the inner surface of the sealing sleeve provides the sealing thread;

the spiral sealing ring is in interference fit with the sealing seat;

still have between seal receptacle and the spiral sealing ring:

a retainer ring is arranged at one end of the sealing seat, which is far away from the nut, so that the spiral sealing ring is axially limited on the sealing seat;

the retainer ring is constructed as a spiral sealing retainer ring, and one end of the spiral sealing retainer ring is connected with one end of the sealing seat, which is far away from the nut;

the spiral sealing retainer ring is provided with a spiral groove which has the same shape as the spiral tooth of the lead screw, and the spiral groove and the spiral tooth of the lead screw are screwed and leave a fit clearance so as to form a non-contact sealing structure.

2. The seal structure of claim 1, wherein the connection structure between the spiral sealing retainer ring and the seal seat is:

correspondingly, the end part of the sealing seat is provided with a screw hole, and a screw sealing retainer ring is assembled on the sealing seat through an arc-shaped assembling hole.

3. The seal of claim 2, wherein the locating portion has an outer diameter less than an inner diameter of the seal housing for forming a radial adjustment clearance of the spiral sealing slinger;

4. A sealing structure according to any one of claims 1 to 3, wherein the outer surface of the spiral sealing ring has external threads;

5. The seal structure of claim 1, wherein the end of the seal assembly connected to the nut connector is a stepped bore;

6. The seal structure of claim 5, wherein the mating surface of the stepped shoulder and the stepped bore is provided with at least one seal.

7. The seal structure of claim 1, wherein the shape of the thread groove of the seal thread is the same as the shape of the screw thread teeth of the lead screw.

8. The seal structure of claim 1, wherein a spiral channel is formed on each side of the nut thread of the ball screw pair;

accordingly, reversers are fitted at both ends of the channel.

9. A ball screw assembly having the seal structure according to any one of claims 1 to 8.