Ball spline

Abstract

The utility model provides a ball spline which comprises a spline shaft, an outer cylinder, a first end cover, a ball throwing cover plate, a second end cover and a plurality of balls. The spline shaft is sleeved with the outer cylinder in a displaceable mode, the first end cover and the second end cover are arranged on the two opposite end faces of the outer cylinder respectively, the first end cover is provided with a bead throwing opening, and the bead throwing cover plate is arranged on the outer side face of the first end cover and detachably arranged on the first end cover. And the balls circularly run among the spline shaft, the outer cylinder, the first end cover, the ball throwing cover plate and the second end cover. Therefore, according to the ball spline disclosed by the utility model, the ball can be loaded through the ball throwing opening after the ball throwing cover plate is taken down, so that the assembly efficiency is improved, and the effect of automatic assembly is further realized.

Description

Technical Field

[0001] The utility model relates to a ball spline, in particular to a ball spline which is convenient for installing balls. Background Art

[0002] When installing the balls, the traditional ball spline needs to hold the outer cylinder with one hand first, and then use the other hand to place the balls one by one, so that the balls are easy to fall during the process of loading the balls. For example, the ball spline disclosed in the JP 5222609 patent case does not have a design of a ball-dropping port, and the rotating plate and the end cover need to be removed before the ball loading operation can be carried out, and the balls are also easy to fall during the loading of the balls. In addition, when loading the balls, if the ball spline disclosed in the TW M593483 patent case chooses to first set the second end cover on the second end of the outer cylinder, and then set the first inner cover on the first end of the outer cylinder, the balls can be filled. After filling, the first outer cover is covered on the first inner cover and fixed by the first fixing structure, and the assembly is completed. However, the first end cover and the second end cover also do not have a design of a ball-dropping port, and the balls are also easy to fall during the loading of the balls. In other words, the efficiency of loading the balls of the traditional ball spline still needs to be improved. Utility Model Content

[0003] The main purpose of the utility model is to provide a ball spline, which is convenient for ball loading, so as to improve assembly efficiency and achieve the effect of automatic ball loading.

[0004] In order to achieve the above-mentioned main purpose, the ball spline provided by the utility model includes a ball spline, an outer cylinder, a first end cover, a ball casting cover plate, a second end cover, and a plurality of balls. The outer peripheral surface of the spline shaft has an outer rolling groove extending along its axial direction; the outer cylinder has a first outer end face, a second outer end face and an axial hole penetrating the first outer end face and the second outer end face, and the outer cylinder is displaceably sleeved on the spline shaft with the axial hole. In addition, the outer cylinder also has a non-load channel, an inner rolling groove and two first return parts. The non-load channel passes through the first outer end face and the second outer end face, and the inner rolling groove and the outer rolling groove together form a load channel. Each of the first return parts has a connection between the inner rolling groove and the non-load channel; the first An end cover is arranged on the first outer end surface of the outer tube, and the first end cover has a ball-dropping port connected to the non-load channel; the ball-dropping cover plate is detachably arranged on the first end cover and has a second reflux portion, the second reflux portion is embedded in the ball-dropping port of the first end cover, and together with one of the first reflux portions forms a first reflux channel connecting the load channel and the non-load channel; the second end cover is arranged on the second outer end surface of the outer tube, and together with the load channel, the non-load channel and the first reflux channel forms a circulation channel for the balls to run. On the other hand, the center of the load channel and the axis of the spline shaft form a first connecting line, the non-load channel and the axis of the spline shaft form a second connecting line, the first connecting line and the second connecting line have a first angle, the two ends of the ball-dropping port have a curvature center, the curvature centers and the axis of the spline shaft form a third connecting line and a fourth connecting line, respectively, the third connecting line and the fourth connecting line have a second angle, and the first angle and the second angle satisfy the following relationship: 0<θ 2 ≦ , where θ 1 is the first angle, θ 2 is the second angle.

[0005] As can be seen from the above, the ball spline of the utility model can easily assemble the ball throwing cover plate to the first end cover or remove it from the first end cover. When the ball throwing cover plate is removed, the ball throwing operation can be carried out through the ball throwing port. After the bead loading operation is completed, the ball throwing cover plate can be reassembled to the first end cover, thereby improving the assembly efficiency and achieving the effect of automatic assembly. In addition, by 0<θ 2 ≦ The relationship formula can ensure that beads are not easily dropped when being loaded.

[0006] The detailed structure, features, assembly or use of the ball spline provided by the present invention will be described in the detailed description of the implementation method later. However, those skilled in the art should understand that the detailed description and the specific embodiments listed in the implementation of the present invention are only used to illustrate the present invention, and are not used to limit the scope of the patent application of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a three-dimensional diagram of the ball spline according to the first embodiment of the present invention.

[0008] Figure 2 It is a partial three-dimensional exploded view of the ball spline according to the first embodiment of the utility model.

[0009] Figure 3 It is a partial three-dimensional exploded view of the ball spline of the first embodiment of the utility model at another viewing angle.

[0010] Figure 4 This is an axial cross-sectional view of the ball spline according to the first embodiment of the present invention.

[0011] Figure 5 It is a three-dimensional view of the ball casting cover plate of the first embodiment of the present utility model.

[0012] Figure 6 It is a partial cross-sectional view of the ball spline of the first embodiment of the utility model, mainly showing that the second engaging portion of the ball casting cover plate is engaged with the first engaging portion of the first end cover.

[0013] Figure 7 A partial enlarged view of the ball casting cover plate and the first end cover provided for the ball spline of the first embodiment of the utility model.

[0014] Figure 8 This is an end view of the spline shaft and the first end cover of the first embodiment of the utility model.

[0015] Fig. 9 This is an end view of the spline shaft and the ball casting cover plate of the first embodiment of the utility model.

[0016] Fig.10 It is a three-dimensional view of a ball spline according to the second embodiment of the present invention.

[0017] Fig.11 It is a three-dimensional exploded view of the first end cover and the ball casting cover plate of the second embodiment of the utility model.

[0018] Fig.12 It is a partial cross-sectional view of the ball spline according to the second embodiment of the present invention.

[0019] Fig.13 It is a three-dimensional view of a ball spline according to the third embodiment of the present invention.

[0020] Fig.14 It is a three-dimensional exploded view of the first end cover and the ball casting cover plate of the third embodiment of the utility model.

[0021] Fig.15 It is a three-dimensional view of the ball casting cover plate of the third embodiment of the present utility model.

[0022] Fig.16 It is a partial cross-sectional view of the ball spline according to the third embodiment of the present invention.

[0023] Description of reference numerals:

[0024] 10: Ball spline

[0025] 12: Ball spline

[0026] 14: Ball spline

[0027] 20: Spline shaft

[0028] 21: Outer surface

[0029] 22: External rolling groove

[0030] A: Axial

[0031] C: Axis

[0032] 30: Outer cylinder

[0033] 31: First outer end surface

[0034] 32: Second outer end surface

[0035] 33: Shaft hole

[0036] 34: Non-load channel

[0037] C2: Center of the non-loaded channel

[0038] 35: Inner rolling groove

[0039] 36: First reflux section

[0040] 37: First reflux tank

[0041] 38: First positioning hole

[0042] 39: Screw hole

[0043] 40: First end cap

[0044] 41: First guide part

[0045] 42: First inner side

[0046] 422: First positioning column

[0047] 43: First outer side

[0048] 432: First positioning groove

[0049] 44: Bead Throwing Port

[0050] 442: Curved end

[0051] C3: Center of curvature

[0052] 45: First piercing

[0053] 46: Second positioning hole

[0054] 47: Outer ring

[0055] 48: First engagement portion

[0056] 48': First engagement section

[0057] 482: Groove

[0058] 484: Ribs

[0059] 49: First half reflow trough

[0060] 50: Bead casting cover

[0061] 51: Arc

[0062] 512: Inner surface

[0063] 514: External surface

[0064] 516: Countersunk hole

[0065] 518: Inner circumference

[0066] 52: Second reflux section

[0067] 53: Second half reflux tank

[0068] 54: Second engagement portion

[0069] 54': Second engagement section

[0070] 55: Cantilever

[0071] 56: Hook

[0072] 57: Second reflux tank

[0073] S1: First screw

[0074] 60: First dust sheet

[0075] 61: First Lip

[0076] 62: Second positioning column

[0077] 63: First positioning block

[0078] 64: Outer periphery

[0079] 65: Second dust cover

[0080] 66: Second lip

[0081] 67: Fourth positioning column

[0082] 68: Second positioning block

[0083] 69: Gap

[0084] 70: Second end cap

[0085] 71: Second guide part

[0086] 72: Second inner side

[0087] 722: The third positioning column

[0088] 724: The third reflux tank

[0089] 73: Second outer side

[0090] 732: Second positioning slot

[0091] 74: Second piercing

[0092] 75: The third positioning hole

[0093] S2: Second screw

[0094] 80: Ball

[0095] D: ball diameter

[0096] 81: Load channel

[0097] C1: Center of the load channel

[0098] 82: First reflux channel

[0099] 83: Second reflux channel

[0100] 84: Circulation Channel

[0101] 90: Bead cover

[0102] 91: Ring

[0103] 912: Inner surface

[0104] 914: External surface

[0105] 916: Countersunk hole

[0106] L1: First connection

[0107] L2: Second connection

[0108] L3: The third link

[0109] L4: The fourth link

[0110] θ 1 : The first angle

[0111] θ 2 : The first angle DETAILED DESCRIPTION

[0112] The applicant first explains that throughout the entire specification, including the embodiments described below and the claims, the terms related to directions are based on the directions in the drawings. Secondly, in the embodiments and drawings to be described below, the same element numbers represent the same or similar elements or their structural features.

[0113] See also Figures 1 to 4 The ball spline 10 of the first embodiment of the present invention includes a spline shaft 20, an outer cylinder 30, a first end cover 40, two ball casting covers 50, a first dustproof sheet 60, a second end cover 70, a second dustproof sheet 65, and a plurality of balls 80.

[0114] The spline shaft 20 has an outer circumferential surface 21 and four outer rolling grooves 22 . The four outer rolling grooves 22 are provided on the outer circumferential surface 21 in pairs of two and extend along the axial direction A of the spline shaft 20 .

[0115] The outer cylinder 30 has a first outer end face 31, a second outer end face 32 and an axial hole 33 penetrating the first and second outer end faces 31 and 32. The outer cylinder 30 is sleeved on the spline shaft 20 with the axial hole 33 in a displaceable manner. The outer cylinder 30 also has four non-load passages 34, four inner rolling grooves 35 and eight first return portions 36, wherein the non-load passages 34 are arranged adjacent to the axial hole 33 and penetrate the first outer end face 31 and the second outer end face 32 in a manner parallel to the axial hole 33; the inner rolling grooves 35 are arranged in pairs on the hole wall of the axial hole 33 and form a load passage 81 together with the outer rolling grooves 22 of the spline shaft 20 (such as Figure 4 ); four first reflux portions 36 are provided on the first outer end surface 31, and another four first reflux portions 36 are provided on the second outer end surface 32. Each first reflux portion 36 has a first reflux groove 37, and the two ends of each first reflux groove 37 are respectively connected to one end of the inner rolling groove 35 and one end of the non-load channel 34. In addition, the first and second outer end surfaces 31, 32 of the outer cylinder 30 have two first positioning holes 38 and two screw holes 39, respectively.

[0116] The first end cover 40 is sleeved on the spline shaft 20 and has four first guide parts 41 embedded in the four outer rolling grooves 22 of the spline shaft 20 to guide the balls 80 and remove foreign matter remaining in the outer rolling grooves 22. The first end cover 40 has a first inner side surface 42 facing the outer cylinder 30 and a first outer side surface 43 facing away from the outer cylinder 30, wherein the first inner side surface 42 has two first positioning columns 422, and the two first positioning columns 422 of the first end cover 40 are inserted into the two first positioning holes 38 of the outer cylinder 30, so that the first end cover 40 is positioned on the first outer end surface 31 of the outer cylinder 30, and the first outer side surface 43 has four first positioning grooves 432, and the four first positioning grooves 432 are arranged in pairs of two. The first end cover 40 further has four ball-dropping openings 44, four first through-holes 45 and four second positioning holes 46. The ball-dropping openings 44, the first through-holes 45 and the second positioning holes 46 all penetrate the first inner side surface 42 and the first outer side surface 43. The ball-dropping openings 44 are connected to the non-load passages 34 (such as Figure 8 As shown in the figure, the first end cover 40 is not connected to the load channel 81. The first through hole 45 is located between two adjacent ball-dropping ports 44, and the four second positioning holes 46 are arranged in pairs of two on two opposite sides of the first positioning groove 432. In addition, the first end cover 40 also has an outer ring surface 47, four first engaging portions 48 and four first semi-reflow grooves 49. The outer ring surface 47 connects the first inner side surface 42 and the first outer side surface 43. The first engaging portion 48 is a groove that penetrates the first inner side surface 42 and the outer ring surface 47 in this embodiment. The first semi-reflow groove 49 is arranged on the first inner side surface 42 and adjacent to the ball-dropping port 44 (as shown in the figure). Figure 7 as shown).

[0117] like Figure 2 and Figure 5 As shown, each ball casting cover plate 50 has an arc portion 51, two second return portions 52, and two second engaging portions 54. The arc portion 51 has an inner surface 512 facing the first end cover 40, an outer surface 514 facing away from the first end cover 40, and a countersunk hole 516 penetrating the inner and outer surfaces 512, 514; the two second return portions 52 are arranged on the inner surface 512 of the arc portion 51 and are located on two opposite sides of the countersunk hole 516, and the two second return portions 52 are embedded in two of the ball casting ports 44 of the first end cover 40. In addition, each second return portion 52 has a second half return groove 53, and the second half return groove 53 of the ball casting cover plate 50 is connected to the first half return groove 49 of the first end cover 40 to form a second return groove 57 (as shown in FIG. 1 ). Figure 7 As shown in FIG. 1 ), the second reflux groove 57 and one of the first reflux grooves 37 of the outer cylinder 30 together form a first reflux channel 82 (as shown in FIG. 1 ) connecting the load channel 81 and the non-load channel 34. Figure 4as shown in the figure); two second engaging portions 54 are provided at both ends of the inner surface 512 of the arc portion 51 and on two opposite sides of the two second return portions 52. In this embodiment, the second engaging portion 54 has a cantilever 55 and a hook 56. One end of the cantilever 55 is connected to the inner surface 512 of the arc portion 51, and the other end of the cantilever 55 is connected to the hook 56, and the hook 56 protrudes outward from the cantilever 55. When assembling with the first end cover 40, each ball cover plate 50 first hooks and engages the two second engaging portions 54 with the two first engaging portions 48 of the first end cover 40, and embeds each second return portion 52 into each ball inlet 44 of the first end cover 40. Finally, two first screws S1 are passed through the two counterbore holes 516 of the two ball cover plates 50 and the two first through holes 45 of the first end cover 40 and screwed into the two screw holes 39 of the outer cylinder 30. In this way, the two ball cover plates 50 are assembled on the first outer side surface 43 of the first end cover 40 in a symmetric manner.

[0118] It should be supplemented and explained here that, as Figure 7 shown, after the second return portion 52 of the ball cover plate 50 is embedded into the ball inlet 44 of the first end cover 40, there is a gap G between the second return portion 52 of the ball cover plate 50 and the ball inlet 44 of the first end cover 40. The gap G satisfies the following relationship: 0 < G ≦ 0.1D, where G is the gap and D is the diameter of the ball 80. Through the above relationship, it can be ensured that the ball 80 maintains good smoothness during return. If the gap G exceeds 0.1 times the diameter of the ball, it is easy to cause the ball 80 to have a jerky situation during return.

[0119] The first dust-proof sheet 60 is sleeved on the spline shaft 20 and has four first lips 61 embedded in the four outer rolling grooves 22 of the spline shaft 20 to remove foreign matters remaining in the outer rolling grooves 22. In addition, the inner surface of the first dust-proof sheet 60 has four second positioning posts 62 and four first positioning blocks 63. The four second positioning posts 62 of the first dust-proof sheet 60 are inserted into the four second positioning holes 46 of the first end cover 40, and the four first positioning blocks 63 of the first dust-proof sheet 60 are inserted into the four first positioning grooves 432 of the first end cover 40, so that the first dust-proof sheet 60 is fixed to the first end cover 40 and positioned between the two ball cover plates 50. Moreover, the contour of the outer peripheral edge 64 of the first dust-proof sheet 60 matches the contour of the inner peripheral edge 518 of the two arc portions 51, making the overall structure relatively simple.

[0120] The second end cover 70 is sleeved on the spline shaft 20 and has four second guide portions 71 embedded in the four outer rolling grooves 22 of the spline shaft 20 to guide the balls 80 and remove foreign matter remaining in the outer rolling grooves 22. The second end cover 70 has a second inner side surface 72 facing the outer cylinder 30 and a second outer side surface 73 facing away from the outer cylinder 30, wherein the second inner side surface 72 has two third positioning columns 722 and four third reflux grooves 724, and the second outer side surface 73 has four second positioning grooves 732, and the four second positioning grooves 732 are arranged in pairs of two. The two third positioning columns 722 of the second end cover 70 are inserted into the other two first positioning holes 38 of the outer cylinder 30, so that the second end cover 70 is positioned on the second outer end surface 32 of the outer cylinder 30. The third reflux groove 724 of the second end cover 70 and the other first reflux groove 37 of the outer cylinder 30 jointly form a second reflux channel 83 connecting the load channel 81 and the non-load channel 34. The second reflux channel 83 and the load channel 81, the non-load channel 34 and the first reflux channel 82 jointly form a circulation channel 84 for the ball 80 to run (such as Figure 4 In addition, the second end cover 70 also has two second through holes 74 and four third positioning holes 75, and the second through holes 74 and the third positioning holes 75 all penetrate the second inner side surface 72 and the second outer side surface 73, wherein the four third positioning holes 75 are arranged in pairs of two at two opposite sides of the second positioning groove 732. During assembly, two second screws S2 are inserted through the two second through holes 74 of the second end cover 70, and then screwed into the other two screw holes 39 of the outer cylinder 30, so that the second end cover 70 is fixed to the second outer end surface 32 of the outer cylinder 30.

[0121] The second dustproof sheet 65 is sleeved on the spline shaft 20 and is embedded in the four outer rolling grooves 22 of the spline shaft 20 with four second lips 66 to remove foreign matter remaining in the outer rolling grooves 22. The inner surface of the second dustproof sheet 65 has four fourth positioning columns 67 and four second positioning blocks 68. The four fourth positioning columns 67 of the second dustproof sheet 65 are inserted into the four third positioning holes 75 of the second end cover 70, and the four second positioning blocks 68 of the second dustproof sheet 65 are inserted into the four second positioning grooves 732 of the second end cover 70, so that the second dustproof sheet 65 is fixed to the second outer side surface 73 of the second end cover 70. In addition, the second dustproof sheet 65 also has two notches 69, and the two notches 69 are for the two second screws S2 to pass through and are mutually engaged with the two second screws S2.

[0122] As can be seen from the above, the ball spline 10 of the first embodiment of the utility model can easily assemble the ball throwing cover plate 50 to the first end cover 40 or remove it from the first end cover 40 by utilizing the cooperation of the first locking portion 48 and the second locking portion 54. When the ball throwing cover plate 50 is removed, the beads can be loaded through the ball throwing port 44. After the bead loading operation is completed, the ball throwing cover plate 50 can be reassembled to the first end cover 40, thereby improving the bead loading efficiency and achieving the effect of automated assembly.

[0123] It is necessary to add that, Figure 8 As shown, the center C1 of the load channel 81 and the axis C of the spline shaft 20 form a first connecting line L1, and the center C2 of the non-load channel 34 and the axis C of the spline shaft 20 form a second connecting line L2. There is a first angle θ between the first connecting line L1 and the second connecting line L2. 1 , and then Fig. 9 As shown, the ball-dropping port 44 has two arc-shaped ends 442, each of which has a curvature center C3. The curvature centers C3 and the axis C of the spline shaft 20 respectively form a third connecting line L3 and a fourth connecting line L4. The third connecting line L3 and the fourth connecting line L4 have a second angle θ between them. 2 , the first angle θ 1 and the second angle θ 2 Satisfies the following relationship: 0<θ 2 ≦ The above relationship can ensure that the ball 80 can be stably loaded into the non-load channel 34 from the ball injection port 44. 2 Exceed , indicating that the opening angle of the ball-dropping port 44 is too large, which makes it easy for beads to fall during the bead loading process. On the other hand, by designing that the ball-dropping port 44 is only connected to the non-load channel 34, it can be ensured that the ball 80 will not directly hit the second half reflux groove 53 when entering and exiting the load channel 81, so as to increase the service life of the ball-dropping cover 50 and prevent the ball 80 in the load channel 81 from falling out of the ball-dropping port 44. It is worth mentioning that in this embodiment, the projection of the ball-dropping port 44 at the axial direction A perpendicular to the spline shaft 20 does not overlap with the projection of the load channel 81 at the axial direction A perpendicular to the spline shaft 20, thereby also preventing the ball 80 from falling into the load channel 81 during bead loading.

[0124] See also Fig.10 The structure of the ball spline 12 of the second embodiment of the present invention is substantially the same as that of the first embodiment, except that the first engaging portion 48' and the second engaging portion 54' are slightly different. Fig.11 and Fig.12As shown, the first engaging portion 48' has a groove 482 and a rib 484 disposed in the groove 482, and the second engaging portion 54' has a cantilever 55 and a hook 56, and the hook 56 protrudes inward from the end of the cantilever 55 and is engaged with the rib 484. In this way, the ball spline 12 of the second embodiment of the present invention can also easily complete the disassembly and assembly of the ball throwing cover plate 50 by utilizing the cooperation of the first engaging portion 48' and the second engaging portion 54', so as to achieve the purpose of improving the ball loading efficiency.

[0125] Please continue reading Fig.13 The structure of the ball spline 14 of the third embodiment of the present invention is substantially the same as that of the first embodiment, except that the number of the ball casting cover plate 90 is one. Figures 14 to 16 As shown, the ball casting cover plate 90 has a ring portion 91, four second return portions 52, and two second engaging portions 54. The ring portion 91 has an inner surface 912 facing the first end cover 40, an outer surface 914 facing away from the first end cover 40, and two countersunk holes 916 penetrating the inner and outer surfaces 912, 914; the four second return portions 52 are provided on the inner surface 912 of the ring portion 91 and are arranged in pairs at two opposite sides of the countersunk holes 916; the two second engaging portions 54 are provided on the inner surface 912 of the ring portion 91 and are arranged at two opposite sides of each pair of second return portions 52. In this embodiment, the second engaging portion 54 has a cantilever 55 and a hook 56, one end of the cantilever 55 is connected to the inner surface 912 of the ring portion 91, and the other end of the cantilever 55 is connected to the hook 56, and the hook 56 protrudes outward from the cantilever 55. Therefore, the ball spline 14 of the third embodiment of the present invention can also easily complete the disassembly and assembly of the ball throwing cover plate 90 by utilizing the cooperation of the first engaging portion 48 and the second engaging portion 54, so as to achieve the purpose of improving the ball loading efficiency.

[0126] It is worth mentioning that no matter which of the above embodiments is used, the first engaging portion 48, 48' and the second engaging portion 54, 54' only need to be at least one in number to achieve the effect of mutual engagement. However, in fact, it is the best structural configuration to provide one second engaging portion 54, 54' on each of the two opposite sides of the second return portion 52. This can enhance the structural stability of the ball throwing cover plate 50, 90, making it difficult for the ball throwing cover plate 50, 90 to separate from the first end cover 40 when subjected to the impact force from the ball 80.

Claims

1. A ball spline, characterized in that: Include: A spline shaft having an outer peripheral surface and an outer rolling groove provided on the outer peripheral surface, wherein the outer rolling groove extends along the axial direction of the spline shaft; An outer cylinder, having a first outer end face, a second outer end face and an axial hole penetrating the first outer end face and the second outer end face, the outer cylinder is sleeved on the spline shaft with the axial hole in a displaceable manner, the outer cylinder also has a non-load passage, an inner rolling groove and two first return parts, the non-load passage penetrates the first outer end face and the second outer end face, the inner rolling groove and the outer rolling groove together form a load passage, and each of the first return parts connects the inner rolling groove and the non-load passage; A first end cover is disposed on the first outer end surface of the outer tube, and the first end cover has a bead throwing port, and the bead throwing port is connected to the non-load passage; A bead throwing cover plate is detachably mounted on the first end cover, and the bead throwing cover plate has a second reflux portion, the second reflux portion is embedded in the bead throwing port of the first end cover, and together with one of the first reflux portions forms a first reflux channel connecting the load channel and the non-load channel; a second end cover, disposed on the second outer end surface of the outer cylinder, and forming a circulation channel together with the load channel, the non-load channel and the first reflux channel; as well as A plurality of balls are disposed in the circulation channel; The center of the load channel and the axis of the spline shaft form a first connecting line, the center of the non-load channel and the axis of the spline shaft form a second connecting line, a first angle is formed between the first connecting line and the second connecting line, the two ends of the ball-dropping port respectively have a curvature center, the curvature centers and the axis of the spline shaft respectively form a third connecting line and a fourth connecting line, a second angle is formed between the third connecting line and the fourth connecting line, and the first angle and the second angle satisfy the following relationship: 0<θ2≦ , where θ1 is the first angle and θ2 is the second angle.

2. The ball spline according to claim 1, characterized in that: The first end cover has a first clamping portion, and the ball throwing cover has a second clamping portion. The second clamping portion of the ball throwing cover is detachably arranged on the first clamping portion of the first end cover.

3. The ball spline according to claim 2, characterized in that: The ball casting cover plate also has a ring portion, which has an inner surface facing the first end cover, and the second clamping portion is arranged on the inner surface of the ring portion.

4. The ball spline according to claim 3, characterized in that: The ball casting cover plate has two second engaging parts, which are arranged on the inner surface of the ring part in a manner opposite to each other and are located on both sides of the second reflux part.

5. The ball spline according to claim 3 or 4, characterized in that: It also comprises a dustproof sheet, which is arranged on the first end cover and surrounded by the ring portion of the ball casting cover plate, and the contour of the outer peripheral edge of the dustproof sheet matches the contour of the inner peripheral edge of the ring portion.

6. The ball spline according to claim 2, characterized in that: The invention comprises two ball throwing cover plates, each of which has an arc portion, each of which has an inner surface facing the first end cover, and each of which has a second clamping portion on the inner surface.

7. The ball spline according to claim 6, characterized in that: Each of the ball casting cover plates has two second engaging portions, and the second engaging portions are arranged at two ends of the arc portion and located at two sides of the second return flow portion.

8. The ball spline according to claim 1, characterized in that: The first reflow parts are respectively arranged on the first outer end surface and the second outer end surface, each of the first reflow parts has a first reflow groove, and the two ends of each first reflow groove are respectively connected to one end of the inner rolling groove and one end of the non-load channel; the first end cover has a first half reflow groove adjacent to the ball throwing port, and the second reflow part has a second half reflow groove, the first half reflow groove is connected to the second half reflow groove to form a second reflow groove, and the second reflow groove and one of the first reflow grooves together form the first reflow channel; the second end cover has a third reflow groove, and the third reflow groove and another first reflow groove together form a second reflow channel connecting the load channel and the non-load channel, and the second reflow channel forms the circulation channel together with the load channel, the non-load channel and the first reflow channel.

9. The ball spline according to claim 1, characterized in that: There is a gap between the second return part of the ball-inserting cover plate and the ball-inserting port of the first end cover, and this gap satisfies the following relational expression: 0 < G ≦ 0.1D, where G is this gap and D is the diameter of the ball.

10. The ball spline according to claim 1, characterized in that: The projection of the ball-inserting port in the axial direction perpendicular to the spline shaft does not overlap with the projection of the load channel in the axial direction perpendicular to the spline shaft.

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