Ball screw pair and nut reverser thereof

Abstract

The utility model discloses a ball screw pair and a nut reverser thereof, the nut reverser comprises a nut and a reverser, the nut is provided with a central through hole and a straight groove extending outwards in the radial direction from the central through hole, and the reverser is inserted into the straight groove to be fixed. The reverser is provided with a matching surface facing the central through hole and a mounting surface facing the straight groove; a plurality of first bead passing grooves are formed in the inner wall face of the center penetrating hole, a plurality of second bead passing grooves are formed in the matching face, and the first bead passing grooves and the second bead passing grooves jointly form bead passing grooves. The inner wall of the straight groove comprises two opposite cambered surfaces and a transition surface connected with the two cambered surfaces, and the cambered surfaces protrude towards the interior of the straight groove; the mounting surface is attached to the inner wall of the straight groove. A bead return groove is formed in the mounting surface, and the top and the bottom of the bead return groove are respectively communicated with the corresponding first bead passing grooves, so that the bead return groove and the bead passing grooves form a closed loop. According to the ball screw pair, the machining and mounting difficulty of the ball screw pair can be reduced, meanwhile, the structure can be more compact, and the overall precision can be improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to mechanical drive technical field especially relates to a ball screw pair and nut return device thereof. BACKGROUND

[0002] The ball screw pair comprises a screw rod, a nut return device, and a plurality of balls arranged between the screw rod and the nut, the nut return device comprises a nut and a return device, the return device (also called a reverse device or a ball return device) is fixed to the nut to connect the circulating loop of the balls, so that each circulating loop is a closed loop, and the balls make infinite circulating movement between the nut return device and the screw rod.

[0003] A nut return device of a ball screw pair is disclosed in Chinese utility model patent publication CN206290664U, which comprises a nut and two return devices, a thread raceway matched with the screw rod is arranged on the inner wall of the central through hole of the nut, a ball backflow groove is arranged between the top surface and the bottom surface of the nut, and the top surface and the bottom surface of the nut are respectively provided with grooves in communication with the backflow groove. The two return devices are respectively fixed in the grooves on the top surface and the bottom surface of the nut through pressing blocks, the balls rolling to the top of the thread raceway enter the backflow groove under the guidance of the top return device, and then enter the bottom of the thread raceway under the guidance of the return device at the bottom through the backflow groove, thereby forming the external circulation of the balls. The guide groove of the return device for guiding the balls needs to be precisely matched with the end of the thread raceway of the nut, which requires high machining precision of the nut. In addition, the assembly process of the return device is prone to errors, so that the overall precision of the ball screw pair cannot be easily guaranteed, and the precision and feel cannot be guaranteed when the ball screw pair is mass produced.

[0004] Therefore, it is necessary to improve the existing ball screw pair and nut return device thereof. UTILITY MODEL CONTENTS

[0005] The utility model provides a ball screw pair and nut return device thereof which are compact in structure and convenient to manufacture.

[0006] Specifically, the utility model is through following technical scheme realizes: a nut returner, it includes nut and returner, the nut is equipped with center through -hole and with the center through -hole radially outward expansion and extension straight slot, the returner inserts the straight slot and fixes, the returner is equipped with the matching surface of facing the center through -hole and the installation surface of facing the straight slot, the inner wall surface of center through -hole is equipped with a plurality of first pass the bead groove, the matching surface is equipped with a plurality of second pass the bead groove, a plurality of first pass the bead groove with a plurality of second pass the bead groove jointly form pass the bead groove, the inner wall of straight slot includes opposite two arc surfaces and the transition surface of connecting two arc surfaces, the arc surface presents to the straight slot interior convex appearance, the installation surface is equipped with opposite two outer sides and the connecting surface of connecting two outer sides, the outer side is attached corresponding arc surface, the connecting surface is attached transition surface, the installation surface is equipped with the bead groove that extends up and down, the top and bottom of bead groove extend to each outer side and communicate with corresponding first pass the bead groove respectively, make bead groove and pass the bead groove form closed loop.

[0007] In a preferred embodiment, the bead groove includes an arcuate top end, an arcuate bottom end, and a straight segment connecting the top end and the bottom end, the top end and the bottom end extend laterally on the two outer sides, respectively, and the straight segment extends vertically on the connecting surface.

[0008] In a preferred embodiment, the arc surface is tangent to the outer contour line C of the bead groove.

[0009] In a preferred embodiment, the straight slot extends through the nut.

[0010] In a preferred embodiment, the nut is provided with two straight slots, and one returner is arranged in each straight slot.

[0011] In a preferred embodiment, the gap between the installation surface of the returner and the inner wall surface of the straight slot is 0.05 mm.

[0012] In a preferred embodiment, the returner is manufactured by metal powder forming technology or by plastic mold injection molding process.

[0013] The utility model is implemented by the following technical scheme: a ball screw pair, comprising a screw rod, a plurality of balls, and the above-mentioned nut returner, the screw rod passes through the center through-hole of the nut, a plurality of balls are located between the screw rod and the nut returner and circulate and roll in the closed loop.

[0014] In a preferred embodiment, the screw rod is provided with a threaded groove, and the top and bottom of the returner are respectively provided with positioning protrusions inserted into the threaded groove.

[0015] This invention can reduce the difficulty of processing and installing ball screw assemblies, while making the structure more compact and improving overall precision.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the present invention. Attached Figure Description

[0017] Figure 1 This is a three-dimensional assembly diagram of a ball screw pair in one embodiment of the present invention;

[0018] Figure 2 for Figure 1 A partially cut-out three-dimensional composite view of the ball screw assembly shown.

[0019] Figure 3 for Figure 1 A three-dimensional view of several balls in the ball screw assembly shown.

[0020] Figure 4 for Figure 1 A three-dimensional assembly diagram of the nut reversing mechanism of the ball screw pair shown;

[0021] Figure 5 for Figure 4 A 3D view of the nut of the nut reversing device shown;

[0022] Figure 6 for Figure 5 The top view of the nut shown;

[0023] Figure 7 for Figure 4 A perspective view of the nut reversing mechanism shown.

[0024] Figure 8 for Figure 7 A three-dimensional view of the reflector from another angle;

[0025] Figure 9 for Figure 1 The diagram shows a closed loop for the ball screw pair to supply the ball movement.

[0026] Explanation of reference numerals in the attached figures:

[0027] Ball screw assembly 100, screw 1, threaded groove 11, nut return device 2, nut 21, center through hole 211, straight groove 212, arc surface 213, transition surface 214, return device 22, mating surface 221, mounting surface 222, outer surface 223, connecting surface 224, positioning rib 225, closed loop 23, ball passage groove 231, first ball passage groove 231A, second ball passage groove 231B, return ball groove 232, top end 2321, bottom end 2322, ball 3. Detailed Implementation

[0028] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this invention. Rather, they are merely examples of apparatuses, systems, devices, and methods consistent with some aspects of this invention.

[0029] refer to Figures 1 to 3 As shown, the ball screw assembly 100 of this utility model includes a screw 1, a nut return device 2, and a plurality of balls 3 located between the screw 1 and the nut return device 2. When the screw 1 rotates, the nut return device 2 moves linearly relative to the screw 1, and the plurality of balls 3 circulate between the screw 1 and the nut return device 2, reducing the friction between the nut return device 2 and the screw 1, thereby achieving higher motion efficiency.

[0030] Combination Figure 4 As shown, the nut return device 2 includes a nut 21 and two return devices 22 fixed inside the nut 21. In this embodiment, the lead screw 1 adopts a double thread groove 11. The nut return device 2 needs to provide two closed loops 23 for a number of balls 3. Each closed loop 23 includes a ball-passing groove 231 and a ball-returning groove 232 connected end to end. The nut return device 2 provides one return device 22 for each closed loop 23, and the two return devices 22 have identical structures. If the lead screw 1 is changed to a single thread, then the nut return device 2 only needs to provide one return device 22.

[0031] Combination Figure 5 and Figure 6 As shown, the nut 21 has a central through hole 211 through which the lead screw 1 passes, and two straight grooves 212 extending radially outward from both sides of the central through hole 211. The two straight grooves 212 are connected to the central through hole 211 and are symmetrically arranged. The straight grooves 212 penetrate the nut 21 vertically and are approximately V-shaped with their openings facing the central through hole. The inner wall of the central through hole 211 has several first ball-passing grooves 231A for the rolling of the ball 3. The cross-section of the first ball-passing grooves 231A is larger than the diameter of the ball 3. The inner wall of the straight groove 212 is a smooth surface, and includes two opposing arc surfaces 213 and a transition surface 214 connecting the two arc surfaces 213. The two arc surfaces 213 protrude towards the interior of the straight groove 212.

[0032] refer to Figure 7 and Figure 8As shown, the returner 22 is roughly triangular column, inserted into and fixed in the straight slot 212 from top to bottom, and is provided with a matching surface 221 and a roughly V-shaped mounting surface 222, the matching surface 221 and the mounting surface 222 roughly form a triangle, the matching surface 221 faces the central through hole 211, and the mounting surface 222 faces the inner wall surface of the straight slot 212, the surface where the matching surface 221 is located is defined as the inner side of the returner 22, and the surface where the mounting surface 222 is located is defined as the outer side of the returner 22. The returner 22 is inserted into the straight slot 212 with a gap, the gap between the mounting surface 222 and the inner wall surface of the straight slot 212 is controlled to be about 0.05 mm, so that the returner 22 does not fall freely in the straight slot 212 with slight damping, and the returner 22 can freely float within a certain range.

[0033] In combination Figure 4 As shown, the matching surface 221 is provided with a plurality of second ball passing grooves 231B, the cross section of the second ball passing groove 231B is larger than the diameter of the ball 3, and the two ends of the second ball passing groove 231B are respectively tangent to and communicate with the corresponding first ball passing groove 231A, so that the ball 3 can smoothly roll through the returner 22. The plurality of first ball passing grooves 231A of the nut 21 and the plurality of second ball passing grooves 231B of the returner 22 jointly form the above-mentioned ball passing groove 231.

[0034] The mounting surface 222 includes two opposite outer sides 223 and a connecting surface 224 connecting the two outer sides 223, and the ball returning groove 232 is arranged on the mounting surface 222 of the returner 22, the ball returning groove 232 includes an arc-shaped top end 2321, an arc-shaped bottom end 2322 and a straight line segment 2323 connecting the top end 2321 and the bottom end 2322, the top end 2321 and the bottom end 2322 respectively extend transversely on the two outer sides 223, and the straight line segment 2323 extends vertically on the connecting surface 224, the top end 2321 of the ball returning groove 232 communicates with a corresponding first ball passing groove 231A at the top of the nut 21, and the bottom end 2322 of the ball returning groove 232 communicates with a corresponding first ball passing groove 231A at the bottom of the nut 21, so that the ball returning groove 232 communicates with the corresponding ball passing groove 231 to form a closed loop 23 with the head and tail closed.

[0035] The matching surface 221 of the returner 22 is respectively provided with a positioning convex rib 225 at the top end 2321 and the bottom end 2322 of the ball returning groove 232, Figure 2 As shown, the positioning convex rib 225 is inserted into the threaded groove 11 of the lead screw 1, and by virtue of the mutual matching of the positioning convex rib 225 and the threaded groove 11, the returner 22 can freely float within a certain range, so that the ball 3 can automatically align the ball returning groove 232, and the ball 3 can realize the circulating rolling in the closed loop 23.

[0036] Reference Figure 5 , Figure 8 and Figure 9As shown, when the reverser 22 of the nut 21 is inserted into the straight groove 212 of the nut 21, the outer side surface 223 of the reverser 22 is attached to the arc surface 213 of the straight groove 212, the connecting surface 224 of the reverser 22 is attached to the transition surface 214 of the straight groove 212, and the straight groove 212 of the nut 21 is covered by the outer side cover to keep the ball 3 in the ball return groove 232.

[0037] Figure 9 As shown, the top view of the closed loop 23 of the ball screw pair 100 of the utility model is shown, the left and right sides are the ball passing groove 231, the upper and lower sides are the ball return groove 232, and the virtual straight line is the intersection of the ball passing groove 231 and the ball return groove 232. The arc surface 213 forms part of the outer contour line of the ball return groove 232, and the arc surface 213 and the outer contour line C of the ball passing groove 231 have a circular tangent point P, and the arc surface 213 and the top end 2321 and the bottom end 2322 of the ball passing groove 231 each have a circular tangent point P. The ball 3 moves counterclockwise and spirally rises along the ball passing groove 231, reaches the top circular tangent point P, and then enters the top end 2321 of the ball return groove 232 from the ball passing groove 231 through the circular tangent point P, and then enters the straight line segment 2323 and reaches the bottom end 2322 again to enter the ball passing groove 231 again. Among them, when the ball 3 passes through the circular tangent point P, due to the effect of centrifugal force, the ball 3 automatically separates from the ball passing groove 231 and enters the arc surface 213 with inertia, and the shape of the arc surface 213 is basically consistent with the movement trend of the ball 3, so that the movement of the ball 3 is more smooth. When the ball 3 enters the nut 21 from the reverser 22, it is the opposite process, which will not be repeated here.

[0038] The manufacturing process of the nut reverser 2 is as follows:

[0039] 1. Use a wire cutting machine to process a plurality of first ball passing grooves 231A and a straight groove 212 at the center through hole 211 of the nut 21;

[0040] 2. Use injection molding process or powder injection molding process to manufacture the reverser 22;

[0041] 3. Insert the reverser 22 into the straight groove 212 of the nut 21 with a gap;

[0042] 4. Place a plurality of balls 3 in the closed loop 23 formed by the nut reverser 2, and rotate the screw 1 into the nut 21, and the positioning protrusion 225 of the reverser 22 naturally slides into the thread groove 11 of the screw 1 to play a coarse positioning role.

[0043] The ball screw pair 100 and the nut reverser 2 thereof have the following advantages:

[0044] 1. The complexity of processing and installation is reduced. The complex process of the blind groove and the through hole in the nut along the spiral line in the prior art is simplified to only need to process a straight groove 212 at the center through hole 211 of the nut 21.

[0045] 2. Reducing the number of processing and installation of the number of returner, make the structure of the ball screw pair 100 more compact and reliable. Corresponding to each closed loop only need a returner 22, reducing the number of interface between the thread groove 11 and the ball groove 231, improve the overall reliability and unique "triangle" shape make the ball screw pair 100 internal structure more compact.

[0046] 3. Improve the overall accuracy of the ball screw pair 100. Because the returner 22 and the nut 21 straight groove 212 using clearance fit, returner 22 positioning boss 225 in the screw 1 thread groove 11 positioning, make the returner 22 can freely float within a certain range, to ensure that the ball 3 can automatically align the ball groove 232. The new technology avoids the error in the prior art assembly, make the ball screw pair 100 run more smoothly flexible, quiet, efficient.

[0047] 4. Through the returner 22 mold, with metal powder forming technology to manufacture returner 22 or with plastic mold injection molding process can mass production of the product, meet the needs of mass production.

[0048] The above is only the preferred embodiment of the present application, and is not intended to limit the present application, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application, should be included in the scope of protection of the present application.

Claims

1. A nut backer comprising a nut and a backer, characterized by: The nut is provided with a central through hole and a straight slot extending radially outward from the central through hole, the reverser is inserted into the straight slot and fixed, the reverser is provided with a matching surface facing the central through hole and a mounting surface facing the straight slot; the inner wall surface of the central through hole is provided with a plurality of first ball passing grooves, the matching surface is provided with a plurality of second ball passing grooves, and the plurality of first ball passing grooves and the plurality of second ball passing grooves jointly form a ball passing groove; the inner wall of the straight slot includes two opposite arc surfaces and a transition surface connecting the two arc surfaces, and the arc surfaces are convex towards the inside of the straight slot; the mounting surface is provided with two opposite outer sides and a connecting surface connecting the two outer sides, the outer sides are fitted with the corresponding arc surfaces, and the connecting surface is fitted with the transition surface; the mounting surface is provided with a return ball groove extending upward and downward, and the top and bottom of the return ball groove extend to the respective outer sides and are in communication with the corresponding first ball passing grooves, so that the return ball groove and the ball passing groove form a closed loop.

2. The nut backer-out of claim 1, wherein: The return ball groove includes an arc-shaped top end, an arc-shaped bottom end, and a straight line segment connecting the top end and the bottom end, the top end and the bottom end extend transversely on the two outer sides respectively, and the straight line segment extends vertically on the connecting surface.

3. The nut backstop of claim 2, wherein: The arc surface is tangent to the outer contour line C of the ball passing groove.

4. The nut backstop of claim 3, wherein: The straight slot penetrates the nut upward and downward.

5. The nut backer of claim 3, wherein: The nut is provided with two straight slots, and one reverser is arranged in each straight slot.

6. The nut backstop of claim 3, wherein: The gap between the mounting surface of the reverser and the inner wall surface of the straight slot is 0.05mm.

7. The nut backstop of claim 3, wherein: The reverser is manufactured by metal powder forming technology or plastic mold injection molding process.

8. A ball screw pair, characterized by: The nut reverser includes a screw rod, a plurality of balls, and a nut reverser according to any one of claims 1 to 7, the screw rod passes through the central through hole of the nut, the plurality of balls are located between the screw rod and the nut reverser and circulate and roll in the closed loop.

9. Ball screw pair according to claim 8, characterized in that The screw rod is provided with a threaded groove, and the top and bottom of the reverser are respectively provided with positioning convex ribs inserted into the threaded groove. The screw rod is provided with a threaded groove, and the top and bottom of the reverser are respectively provided with positioning convex ribs inserted into the threaded groove.

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