Ball spline

Abstract

A ball spline includes a spline shaft, a nut, a ball retainer, and a ball. A protruding block is arranged on the inner circumferential face of the nut. A ball circulation channel of the ball retainer comprises a load section, a non-load section and two rotation sections which are located between the load section and the non-load section and are connected with the load section and the non-load section. In the rotation section, the center shaft of the transition section connected with the load section and the center shaft of the bending section connected with the transition section are connected on a connection point. And a first included angle between the inclined surface of the bump in the extending direction of the spline shaft and the horizontal shaft is theta1. The center axis of the bending section is tangent to the center axis of the transition section at the joint point to form a tangent line, a second included angle between the tangent line and the center axis of the load section is theta 2, and theta 2 is larger than theta 1.

Description

Technical Field

[0001] The utility model relates to a ball spline, in particular to a ball spline that can improve the smoothness of ball rolling. Background Art

[0002] The ball spline mainly consists of a nut, a spline shaft, balls and a cage. By means of the infinite cyclic rolling of the balls between the nut and the spline shaft, the nut can perform high-precision linear movement along the spline shaft.

[0003] However, for existing ball splines, such as those disclosed in patents with publication numbers TWM618447U and JP6393496B2, most of them do not have a buffer design for the ball return structure. Therefore, the balls in rolling are likely to impact the components contacted on the return path, resulting in poor operation smoothness of the ball spline. Summary of the Utility Model

[0004] To solve the problems of the prior art, the purpose of the utility model is to provide a ball spline. By making a buffer design for the ball return structure, the impact of the balls on the return structure on the return path is reduced, thereby improving the operation smoothness of the ball spline.

[0005] To achieve the above purpose, a ball spline provided by an embodiment of the utility model includes: a spline shaft, on the outer peripheral surface of which a first rolling groove is provided; a nut sleeved on the spline shaft, on the inner peripheral surface of which a convex block is provided. The convex block includes a top surface facing the spline shaft and an inclined surface connecting the top surface and located in the extending direction of the spline shaft. A second rolling groove is recessed in the top surface, and the first rolling groove corresponds to the second rolling groove; a ball cage sleeved on the spline shaft and located between the spline shaft and the nut, the ball cage being provided with a ball circulation channel. The ball circulation channel includes a load section, a non-load section, and two turning sections located between the load section and the non-load section and connecting the load section and the non-load section. Each turning section includes a first section connecting the load section and a second section connecting the non-load section and the first section. The first section includes a transition section connecting the load section and a bending section connecting the second section and the transition section, and the central axis of the transition section and the central axis of the bending section are joined at a connection point; a plurality of balls provided in the ball circulation channel and located between the spline shaft and the nut, and accommodated in the first rolling groove and the second rolling groove; wherein, a first included angle θ1 is formed between the inclined surface of the convex block and a horizontal axis parallel to the extending direction. The central axis of the bending section is tangent to the central axis of the transition section at the connection point to form a tangent line, and a second included angle θ2 is formed between the tangent line and the central axis of the load section. And the ball spline meets the following condition: θ2 > θ1.

[0006] Optionally, the ball spline further satisfies the following condition: 2° < θ2 – θ1 < 20°. Even more, the ball spline further satisfies the following condition: 2° < θ2 – θ1 < 15°.

[0007] Optionally, a concave fillet is provided at the connection between the inclined surface of the protrusion and the inner peripheral surface of the nut. Optionally, the radius of curvature of the concave fillet is 1.0 mm to 2.0 mm.

[0008] Optionally, a convex fillet is provided at the connection between the inclined surface of the protrusion and the top surface. Optionally, the radius of curvature of the convex fillet is 2.0 mm to 2.5 mm. Description of the Drawings

[0009] After studying the detailed description in conjunction with the following drawings, other aspects and advantages of the present utility model will be found:

[0010] Figure 1 is a schematic external view of a ball spline according to an embodiment of the present utility model;

[0011] Figure 2 is Figure 1 exploded view of the ball spline;

[0012] Figure 3 is Figure 1 cross-sectional view of the ball spline;

[0013] Figure 4 is Figure 1 cross-sectional view of the ball spline;

[0014] Figure 5 is a top view of a ball retainer of a ball spline according to an embodiment of the present utility model;

[0015] Figure 6 is Figure 3 partial enlarged view of the ball spline;

[0016] Figure 7 is Figure 2 cross-sectional view of the nut of the ball spline;

[0017] Figure 8 is Figure 7 partial enlarged view of the nut; and

[0018] Figure 9 is Figure 5 partial enlarged cross-sectional view of the ball retainer of the ball spline.

[0019] Description of the Symbol Marks in the Drawings:

[0020] 10: Spline shaft

[0021] 11: Outer peripheral surface

[0022] 12: First rolling groove

[0023] 20: Nut

[0024] 21: Inner peripheral surface

[0025] 22: Protrusion

[0026] 23: Top surface

[0027] 24: Inclined surface

[0028] 25: Second rolling groove

[0029] 26: Convex fillet

[0030] 27: Concave fillet

[0031] 30: Ball retainer

[0032] 31: Ball circulation channel

[0033] 311: Edge

[0034] 32: Load section

[0035] 33: Non-load section

[0036] 34: Rotary section

[0037] 341: First section

[0038] 342: Second section

[0039] 343: Transition section

[0040] 344: Bending section

[0041] 40: Ball

[0042] 50: Spacer

[0043] 60: Snap ring

[0044] A: Extension direction

[0045] C 1: Central axis

[0046] C2: Central axis

[0047] C3: Central axis

[0048] C4: Central axis

[0049] C5: Central axis

[0050] L: Tangent

[0051] P 1: Connection point

[0052] P2: Connection point

[0053] P3: Junction point

[0054] P4: Junction point

[0055] V: Horizontal axis

[0056] R1: Radius of curvature

[0057] R2: Radius of curvature

[0058] θ1: First included angle

[0059] θ2: Second included angle Detailed implementation manner

[0060] Refer to Figures 1 to 9 As shown in the figure, a ball spline provided by an embodiment of the present utility model includes a spline shaft 10, a nut 20, a ball retainer 30, a plurality of balls 40, two gaskets 50 and two snap rings 60.

[0061] A first rolling groove 12 is provided on the outer peripheral surface 11 of the spline shaft 10.

[0062] The nut 20 is sleeved on the spline shaft 10, and a convex block 22 is provided on the inner peripheral surface 21 of the nut 20. The convex block 22 includes a top surface 23 facing the spline shaft 10 and two opposite inclined surfaces 24 connecting the top surface 23 and located in the extending direction A of the spline shaft 10. A second rolling groove 25 is recessed in the top surface 23, and the second rolling groove 25 corresponds to the first rolling groove 12 of the spline shaft 10 to accommodate the balls 40, so that the balls 40 are located between the spline shaft 10 and the nut 20.

[0063] The ball retainer 30 is sleeved on the spline shaft 10 and is located between the spline shaft 10 and the nut 20. The ball retainer 30 is provided with a ball circulation channel 31 for accommodating the balls 40 to circulate therein. The ball circulation channel 31 includes a load section 32, a non-load section 33 located on the opposite side of the load section 32, and two opposite turning sections 34 located between the load section 32 and the non-load section 33 and connecting the load section 32 and the non-load section 33.

[0064] Each rotating section 34 includes a first section 341 connecting the load section 32 and a second section 342 connecting the first section 341 and the non-load section 33. The first section 341 includes a transition section 343 connecting the load section 32 and a bending section 344 connecting the transition section 343 and the second section 342. The central axis C1 of the load section 32 is connected to the central axis C2 of the transition section 343 at the connection point P1. The central axis C2 of the transition section 343 is connected to the central axis C3 of the bending section 344 at the connection point P2. The central axis C3 of the bending section 344 is connected to the central axis C4 of the second section 342 at the connection point P3. The central axis C4 of the second section 342 is connected to the central axis C5 of the non-load section 33 at the connection point P4.

[0065] A first included angle θ1 is formed between the inclined surface 24 of the convex block 22 and the horizontal axis V in the parallel extension direction A. The central axis C3 of the bending section 344 is tangent to the central axis C2 of the transition section 343 at the connection point P2 to form a tangent line L. A second included angle θ2 is formed between the tangent line L and the central axis C1 of the load section 32, and θ2 > θ1. Specifically, the relationship between the first included angle θ1 and the second included angle θ2 also meets the following conditions: 2° < θ2 – θ1 < 20°, and preferably also meets the following conditions: 2° < θ2 – θ1 < 15°. Here, the central axis C1 and the central axis C2 are located at the center between the opposite two edges 311 of the ball circulation channel 31.

[0066] Two gaskets 50 and two snap rings 60 are sleeved on the spline shaft 10 and arranged at the opposite ends of the nut 20.

[0067] Through the design of the ball circulation channel 31, the impact of the balls 40 on the ball retainer 30 when rolling to the turning point of the ball circulation channel 31 can be effectively reduced, thereby improving the smooth operation of the ball spline.

[0068] In addition, in this embodiment or other embodiments, a convex fillet 26 may optionally be provided at the connection between the inclined surface 24 and the top surface 23 of the convex block 22. The radius of curvature R1 of the convex fillet 26 is 2.0 mm to 2.5 mm. Thus, when the ball 40 rolls from the second rolling groove 25 on the top surface 23 of the convex block 22 to the inclined surface 24 of the convex block 22, or when the ball 40 rolls from the inclined surface 24 of the convex block 22 to the second rolling groove 25 on the top surface 23 of the convex block 22, the impact of the ball 40 on the ball retainer 30 can be effectively reduced, thereby improving the smooth operation of the ball spline.

[0069] In this embodiment or other embodiments, a concave fillet 27 may optionally be provided at the connection between the inclined surface 24 of the projection 22 and the inner peripheral surface 21 of the nut 20. The radius of curvature R2 of the concave fillet 27 is 1.0 mm to 2.0 mm. Thus, when the ball 40 rolls from the inclined surface 24 of the projection 22 to the inner peripheral surface 21 of the nut 20, or when the ball 40 rolls from the inner peripheral surface 21 of the nut 20 to the inclined surface 24 of the projection 22, the impact of the ball 40 on the nut 20 can be effectively reduced, thereby improving the smooth operation of the ball spline.

[0070] The following is a simulation analysis of the impact force between the ball and the fitting for different relationships between the first included angle θ1 and the second included angle θ2, and the results are shown in Table 1 below.

[0071]

[0072] It can be seen from the simulation analysis results in Table 1 above that when θ2 > θ1, especially when θ2 - θ1 > 2°, the impact of the ball 40 on the fitting can be effectively reduced.

[0073] Preferably, when 2° < θ2 - θ1 < 20°, and even 2° < θ2 - θ1 < 15°, the effect of reducing the impact is better.

[0074] In summary, the present utility model buffers the ball circulation passage 31 of the ball retainer 30, especially the upward section (i.e., the first section 341) of the ball circulation passage 31, and slopes the projection 22 of the nut 20 in the extending direction A of the spline shaft 10, so that when the ball 40 passes through these paths, the impact on these fittings can be reduced, thereby effectively improving the smooth operation of the ball spline. Even more, the present utility model also reduces the impact on the nut 20 and the ball retainer 30 when the ball 40 rolls along the slope by providing rounded corners at the opposite ends of the slope of the projection 22 in the extending direction A of the spline shaft 10, thereby effectively improving the smooth operation of the ball spline.

[0075] Although the present utility model is disclosed as the foregoing embodiments, these embodiments are not intended to limit the present utility model. Without departing from the spirit and scope of the present utility model, any changes, modifications and combinations of various embodiments are within the scope of the patent protection of the present utility model. For the scope of protection defined by the present utility model, please refer to the attached patent application scope.

Claims

1. A ball spline, characterized in that: The ball spline comprises: A spline shaft, wherein a first rolling groove is provided on an outer peripheral surface of the spline shaft; A nut is sleeved on the spline shaft, a convex block is provided on the inner circumference of the nut, the convex block includes a top surface facing the spline shaft and an inclined surface connected to the top surface and located in the extension direction of the spline shaft, the top surface is concavely provided with a second rolling groove, and the first rolling groove corresponds to the second rolling groove; A ball retainer is sleeved on the spline shaft and located between the spline shaft and the nut, and the ball retainer is provided with a ball circulation channel, the ball circulation channel includes a load section, a non-load section, and two rotation sections located between the load section and the non-load section and connecting the load section and the non-load section, each of the rotation sections includes a first section connecting the load section and a second section connecting the non-load section and the first section, the first section includes a transition section connecting the load section and a curved section connecting the second section and the transition section, and the central axis of the transition section is connected to the central axis of the curved section at a connection point; as well as A plurality of balls are arranged in the ball circulation channel and between the spline shaft and the nut, and are accommodated in the first rolling groove and the second rolling groove; Among them, the first angle formed between the inclined surface of the protrusion and the horizontal axis parallel to the extension direction is θ1, the central axis of the bending section is tangent to the central axis of the transition section at the connection point to form a tangent line, the second angle formed between the tangent line and the central axis of the load section is θ2, and the ball spline meets the following conditions: θ2>θ1.

2. The ball spline according to claim 1, characterized in that: The ball spline also meets the following condition: 2°<θ2–θ1<20°.

3. The ball spline according to claim 2, characterized in that: The ball spline also meets the following conditions: 2°<θ2–θ1<15°.

4. The ball spline according to claim 1, characterized in that: A concave fillet is provided at a connection between the inclined surface of the protrusion and the inner peripheral surface of the nut.

5. The ball spline according to claim 4, characterized in that: The curvature radius of the concave fillet is 1.0 mm to 2.0 mm.

6. The ball spline according to claim 1, characterized in that: A convex fillet is provided at a connection between the inclined surface and the top surface of the protrusion.

7. The ball spline according to claim 6, characterized in that: The radius of curvature of the convex fillet is 2.0 mm to 2.5 mm.

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