Reverse ball screw pair

Abstract

The invention discloses a reverse ball screw pair. The reverse ball screw pair comprises a lead screw, a nut arranged outside the lead screw in a sleeving mode and a plurality of balls located between the lead screw and the nut. The reverse ball screw pair is further provided with a reverser, a ball return groove is formed in the surface of the lead screw, and the reverser is embedded into the surface of the lead screw corresponding to the ball return groove so as to cover the ball return groove. According to the reverse ball screw pair, the structures of the screw and the reverser can be simplified, and the production efficiency is improved; all the balls are in a closed loop, the reliability of the system can be improved, all the balls participate in effective loads, the rigidity can be improved, and the service life can be prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical transmission, and in particular to a reverse ball screw pair. Background Art

[0002] Ball screws are the most commonly used transmission elements in tool machinery and precision machinery. Their main function is to convert rotational motion into linear motion, or torque into axial repetitive force, while having the characteristics of high precision, reversibility and high efficiency. Due to their small friction resistance, ball screws are widely used in various industrial equipment and precision instruments. Ball screws can be divided into external circulation and internal circulation according to the circulation mode. The outer circulation is when the ball sometimes loses contact with the screw during the circulation process; the inner circulation is when the ball always keeps contact with the screw.

[0003] The existing internal circulation ball screw pair usually includes a screw, a nut, multiple balls and multiple return devices. The return device bridges the two adjacent raceways of the screw to form a circulation groove, so that the balls in a circulation groove circulate between the nut and the screw. Multiple circulation grooves arranged regularly along the axial direction of the screw are set between the nut and the screw, and multiple return devices are set on the surface of the screw corresponding to each circulation groove, and each return device corresponds to two interfaces for the balls to enter and leave the screw raceway. During the manufacturing process, it was found that the process of processing the return ball groove or installing the return device at the corresponding position on the surface of the screw is relatively cumbersome, and the product reliability is poor due to the large number of interfaces. In addition, the regular arrangement of multiple circulation grooves in the axial direction of the screw reduces the number of balls with effective load, reduces the rigidity and life of the reverse ball screw pair, and is not conducive to large-scale production.

[0004] Therefore, it is necessary to improve the existing internal circulation reverse ball screw pair. Summary of the invention

[0005] The invention provides a reverse ball screw pair with a compact structure and a prolonged service life.

[0006] Specifically, the present invention is implemented through the following technical solutions: a reverse ball screw pair, including a screw, a nut sleeved outside the screw and a plurality of balls located between the screw and the nut, the balls are continuously arranged in parallel in a ring shape; a return device is also provided, the outer surface of the screw is provided with an external thread groove and the inner side is provided with a return ball groove, the above-mentioned balls move in the external thread groove and the return ball groove, the return device is embedded in the screw corresponding to the return ball groove to cover the return ball groove, the return ball groove includes an inlet end and an outlet end, and when viewed from the axial direction, the inlet end or the outlet end forms an arc connection with the connection of the external thread groove.

[0007] In a preferred embodiment, a plurality of short grooves are provided on the surface of the return device, and the plurality of short grooves and the external thread groove of the lead screw together form a ball groove, and both ends of the ball groove are respectively connected to both ends of the return ball groove to form a closed loop.

[0008] In a preferred embodiment, the ball return groove includes two widened areas respectively located at the axial ends of the screw and a narrow groove area located between the two widened areas, and the widened area is connected to the corresponding external thread grooves of the screw to form the above-mentioned inlet end and outlet end.

[0009] In a preferred embodiment, the return device includes heads located at both ends of the axis and a connecting portion located between the two heads, the heads cover the widened area, the connecting portion covers the narrow slot area, and the head of the return device is provided with an interface connected to the inlet end and the outlet end.

[0010] In a preferred embodiment, the short groove is provided on the surface of the connecting portion, and both ends of the short groove are respectively connected to corresponding external thread grooves of the lead screw to form the ball groove together with the external thread groove of the lead screw.

[0011] In a preferred embodiment, the width of the short groove is greater than the width of the external thread groove.

[0012] In a preferred embodiment, the head is provided with a protrusion which protrudes into the internal thread of the nut.

[0013] In a preferred embodiment, the inner side surface of the return device is concavely formed into a groove corresponding to the ball return groove, and the ball return groove and the groove together accommodate the balls.

[0014] In a preferred embodiment, the length of the internal thread of the nut is longer than the length of the external thread of the lead screw.

[0015] In a preferred embodiment, when viewed from the axial direction, the bead return groove corresponding to the groove is arc-shaped.

[0016] The reverse ball screw pair of the present invention can simplify the structure of the screw and the screw return device, and improve production efficiency; all balls are in a closed loop, which can improve the reliability of the system, and all balls participate in the effective load, which can improve the rigidity and extend the service life.

[0017] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a three-dimensional exploded view of a reverse ball screw pair in one embodiment of the present invention;

[0019] Figure 2 for Figure 1 The three-dimensional combined cutaway diagram of the reverse ball screw pair shown;

[0020] Figure 3 for Figure 2 The three-dimensional exploded view of the lead screw and the return device shown;

[0021] Figure 4 for Figure 3 A perspective view of the return device shown;

[0022] Figure 5 for Figure 3 The three-dimensional combination diagram of the lead screw and the ball shown;

[0023] Figure 6 This is a schematic diagram of the ball return groove path, which can also be understood as the line connecting the center points of the ball in the ball return groove;

[0024] Figure 7 for Figure 6 Axial schematic diagram shown.

[0025] Description of reference numerals:

[0026] Screw 1, external thread groove 11, ball return groove 12, widened area 121, narrow groove area 122, entrance end 123, ball groove 13, return device 2, head 21, connecting part 22, short groove 23, protrusion 24, groove 26, interface 27, nut 3, internal thread 31, ball 4. DETAILED DESCRIPTION

[0027] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices, systems, equipment, and methods consistent with some aspects of the present invention.

[0028] refer to Figure 1As shown, the reverse ball screw pair of the present invention is an external circulation type, including a screw 1, a returner 2, a nut 3 and a ball 4. The returner 2 is embedded in the surface of the screw 1, and the nut 3 is sleeved outside the screw 1 and the returner 2. The screw 1 is provided with an external thread and an external thread groove 11 located between adjacent external threads. The nut 3 is provided with an internal thread 31 that matches the external thread, wherein the length of the internal thread 31 of the nut 3 is longer than the length of the external thread of the screw 1. The balls are continuously arranged in parallel in a ring shape, and the balls 4 are arranged between the screw 1 and the nut 3 and circulate and roll between the screw 1 and the nut 3. When the screw 1 rotates and drives the nut 3 to move linearly, the balls 4 can reduce the friction between the screw 1 and the nut 3. The steel balls 4 of the present invention are arranged in an annular shape, which is more conducive to increasing the number of steel balls, reducing the pressure on each steel ball 4, and extending the service life. In this embodiment, the annular structure is a closed loop composed of a multi-layer external thread groove 11 and a return ball groove 12 connecting the two ends of the multi-layer external thread groove. The ball 4 moves in the closed loop, which is more conducive to increasing the number of balls 4 compared to the prior art.

[0029] refer to Figure 2 and Figure 3 As shown, the outer surface of the screw 1 is provided with the above-mentioned external thread groove 11 and the inner side is recessed with a return ball groove 12, and the above-mentioned ball 4 moves in the external thread groove 11 and the return ball groove 12, and the return ball groove 12 is formed on the surface of the screw 1 and extends along the axial direction. The return ball groove 12 includes two widened areas 121 respectively located at the axial ends of the screw 1 and a narrow groove area 122 located between the two widened areas 121, and the widened area 121 is connected with the corresponding external thread groove 11 on the surface of the screw 1.

[0030] refer to Figures 2 to 4 As shown, the shape of the return device 2 is roughly consistent with the profile of the ball return groove 12 of the screw 1, including the head 21 at both ends of the axial direction and the connecting portion 22 located between the two head 21. The return device 2 is embedded in the surface of the screw 1 corresponding to the ball return groove 12, covering the ball return groove 12, the head 21 covers the widened area 121, and the connecting portion 22 covers the narrow groove area 122. The head of the return device is provided with an interface 27 connected to the inlet end 123 and the outlet end, so that the return device 2 exposes the inlet end and the outlet end of the two ends of the ball return groove 12, ensuring that the ball 4 can enter and exit the ball return groove 12 normally, and the return device 2 can keep the ball 4 in the ball return groove 12 rolling in the ball return groove 12.

[0031] Please refer to Figures 6 and 7 again. The ball return groove 12 includes an inlet end and an outlet end 123. When viewed from the axial direction, the inlet end or the outlet end 123 is connected to the external thread groove 11 in an arc. For ease of understanding, the external thread groove 11 and the inlet end 123 can be understood as the path taken by the center of gravity of the steel ball 4. In this embodiment, the widening area 121 is connected to the corresponding external thread groove 11 of the lead screw 1 to form the inlet end and the outlet end 123. The present invention forms an arc connection between the inlet end or the outlet end 123 and the external thread groove 11, which is conducive to improving the smoothness of the rotary motion of the steel ball 4, reducing the wear of the steel ball 4, and increasing the service life.

[0032] The outer surface of the connecting portion 22 of the return device 2 is provided with a plurality of short grooves 23, and the two ends of each short groove 23 are connected and continuous with the external thread groove 11 corresponding to the surface of the screw 1, which is equivalent to filling the missing part of the external thread groove 11 on the surface of the screw 1 due to the setting of the return ball groove 12. The short grooves 23 on the surface of the return device 2 and the external thread groove 11 on the surface of the screw 1 together form a ball groove 13 on the surface of the screw 1 between the two outlet and inlet ends 123 at both ends of the return ball groove 12. The two ends of the ball groove 13 are connected with the two ends of the return ball groove 12 through the outlet and inlet 123 respectively, forming a closed loop, and the balls 4 can circulate and roll in the closed loop. The width of the short groove 23 can be slightly larger than the width of the external thread groove 11, which is convenient for connection. Figure 5 As shown, for example, the ball 4 rolls along the ball groove 13 on the surface of the screw 1 from the left end of the ball groove 13 to the right end of the ball groove 13, and can enter the return ball groove 12 through the inlet end 123 at the right end, and return to the left end of the ball groove 13 through the return ball groove 12 and the left end outlet end 123, and enter the ball groove 13 again, and repeat the cycle.

[0033] The head 21 of the return device 2 is provided with a protrusion 24 that protrudes into the internal thread 31 of the nut 3. The protrusion 24 can prevent the ball from escaping from the closed loop. The inner side surface of the return device 2 is concavely provided to form a groove 26 corresponding to the return groove 12. The return groove 12 and the groove 26 accommodate the ball 4 together. When viewed from the axial direction, the return groove corresponding to the groove 26 is an arc shape (see FIG. 2 ). Figure 6 shown).

[0034] The reverse ball screw pair of the present application can use three-dimensional modeling technology to manufacture the screw 1 and the return device 2, digitize the screw 1 and the return device 2 products, simplify the structure of the screw 1 and the return device 2, reduce unnecessary processing steps and processing time, and use simulation processing technology to reduce production and processing time. The reverse ball screw pair of the present application reduces the production and installation of required parts and ensures the efficiency of large-scale production.

[0035] All the balls 4 of the reverse ball screw pair of the present application are in a closed loop, and there are only two inlet and outlet ends 123 in this closed loop, which greatly reduces the unreliability and can ensure the long-term operation of the system. All the balls 4 of the reverse ball screw pair of the present application participate in the payload, and there is no ineffective raceway, which can improve the rigidity and extend the service life.

[0036] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A reverse ball screw pair, comprising a screw, a nut sleeved outside the screw, and a plurality of balls between the screw and the nut, wherein the balls are arranged in a continuous and parallel manner in a ring shape; characterized in that: A return device is also provided. The outer surface of the screw is provided with an external thread groove and the inner side is provided with a return ball groove. The above-mentioned ball moves in the external thread groove and the return ball groove. The return device is embedded on the screw corresponding to the return ball groove to cover the return ball groove. The return ball groove includes an inlet end and an outlet end. When viewed from the axial direction, the inlet end or the outlet end forms an arc-shaped connection with the connection between the external thread groove.

2. The reverse ball screw pair according to claim 1, characterized in that: A plurality of short grooves are arranged on the surface of the return device, and the plurality of short grooves and the external thread groove of the lead screw together form a ball groove, and two ends of the ball groove are respectively connected with two ends of the return ball groove to form a closed loop.

3. The reverse ball screw pair according to claim 2, characterized in that: The ball return groove includes two widened areas respectively located at the axial ends of the lead screw and a narrow groove area located between the two widened areas. The widened area is connected with the corresponding external thread grooves of the lead screw to form the above-mentioned inlet end and outlet end.

4. The reverse ball screw pair according to claim 3, characterized in that: The return device includes heads located at two axial ends and a connecting portion located between the two heads, the heads cover the widened area, the connecting portion covers the narrow slot area, and the head of the return device is provided with an interface connected to the inlet end and the outlet end.

5. The reverse ball screw pair according to claim 4, characterized in that: The short groove is arranged on the surface of the connecting portion, and both ends of the short groove are respectively connected to the corresponding external thread grooves of the lead screw to form the ball groove together with the external thread groove of the lead screw.

6. The reverse ball screw pair according to claim 5, characterized in that: The width of the short groove is greater than the width of the external thread groove.

7. The reverse ball screw pair according to claim 4, characterized in that: The head is provided with a protrusion which protrudes into the internal thread of the nut.

8. The reverse ball screw pair according to claim 1, characterized in that: The inner side surface of the return device is concavely provided with a groove corresponding to the ball return groove, and the ball return groove and the groove together accommodate the ball.

9. The reverse ball screw pair according to claim 1, characterized in that: The length of the internal thread of the nut is longer than the length of the external thread groove of the lead screw.

10. The reverse ball screw pair according to claim 8, characterized in that: When viewed from the axial direction, the bead return groove corresponding to the groove is arc-shaped.

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