Ball spline with reinforced bushing

Abstract

The present invention relates to a ball spline with a reinforced bushing portion, comprising: a spline shaft, which is in the shape of a rod and is formed with one or more track grooves extending in a recessed manner along the length direction; a nut portion, which is inserted into the spline shaft and is formed movably along its length direction; a plurality of balls, which are formed and circulate between the nut portion and the spline shaft, and the nut portion comprises: a nut, which is a hollow body inserted into the spline shaft; a retaining ring, which is formed on both sides of the nut in the length direction and is a hollow body inserted into the spline shaft, and more than one spline portion is formed on the nut portion, a portion of the balls change direction in the spline circulation grooves of the retaining rings on both sides in the length direction, and circulate between the track groove and the load track groove, and in the non-load circulation portion, and the remaining portion of the balls contacts and transmits with the outside of the spline shaft, and circulates along the reinforced bushing portion.

Description

Technical Field

[0001] The present invention relates to a ball spline, and more particularly to a ball spline having a reinforced bushing portion that improves the rigidity of a spline shaft and prolongs its life. Background Art

[0002] Ball splines are a type of linear motion bearing that accurately transmits linear motion in the fields of automation and semiconductor industries.

[0003] like Figure 1 As shown, the previous ball spline 10 is formed with a load track groove 2 for accommodating the ball 1 and leaving one side of the ball 1 exposed. The ball 1 circulating along the load track groove 2 enters the non-load circulation hole 5 along the circulation groove 4 of the retaining ring 3 to form an infinite track to allow the ball 1 to circulate.

[0004] The curvature radius of the cross section of the load track groove 2 in the nut 6 that accommodates the ball 1 is formed in an arc shape that is larger than the radius of the ball 1. However, the ball 1 is accommodated after two identical arcs are formed on the left and right sides of the central axis of the central circle, so that the two tangent points formed on the left and right sides of the central axis of the central circle of the ball 1 are in contact with the load track groove 2. When the ball 1 is accommodated in the load track groove 2, the two tangent points that the ball 1 is in close contact with increase the angle from the center of the ball 1 to prevent the ball 1 from escaping from the load track groove 2, and in order to smoothly circulate the ball 1 when the load track groove 2 moves along the circulation groove 4 of the retaining ring 3 to the non-load circulation hole 5, a curved surface is formed at the front end of the load track groove 2. When the ball 1 moves, it moves along the curved surface, so that no impact occurs, and noise or vibration can be prevented.

[0005] When the spline shaft 8 is inserted into the nut 6, a track groove 9 is formed by extending and recessing the spline shaft 8 along the length direction so that the balls 1 protruding into the inner diameter of the nut 6 can be inserted, so that the spline shaft 8 can accurately and softly move forward and backward in the nut 6 with the help of the balls 1. The forward and backward movement is performed regardless of the length of the spline shaft 8 due to the circulation of the balls 1.

[0006] The cross section of the raceway groove 9 formed in the spline shaft 8 may also be formed in an arc shape, but it is processed in the same manner as the processing of the load raceway groove 2 so that the ball 1 vibrates at four contact points (four-point contact).

[0007] Figure 1 Reference numeral 7 denotes a seal formed between the nut 6 and the retainer 3 , and 4 a denotes a circulation protrusion formed on the retainer 3 and protruding inward.

[0008] exist Figure 1 The nut 6 combined with the retainer 3 in the ball spline 10 shown in the figure can reciprocate along the spline shaft 8 in the length direction thereof, but cannot rotate the spline shaft 8.

[0009] Figure 2 A cross-sectional view showing the spline shaft and balls of a ball spline.

[0010] The conventional ball spline 10 is Figure 2 When a load is applied in the "A" direction, the deformation angle of the nut 6 increases, and pressure is applied to the lower part of the track groove 9, the tangent point 9a between the ball 1 and the track groove 9. The rigidity of the spline shaft 8 weakens, and the ball spline 10 shakes, resulting in a shortened service life.

[0011] To solve this problem, when the track groove 9 is additionally formed on the spline shaft 8 , the rigidity of the spline shaft 8 is weakened, and there is a problem that the cost for forming the track groove 9 is increased. Summary of the invention

[0012] Technical problem to be solved by the invention

[0013] The present invention is proposed to solve the above-mentioned conventional problems, and its purpose is to provide a ball spline with a reinforced bushing portion formed therein to prevent damage to the track groove caused by contact between the spline shaft and the ball, thereby improving the rigidity of the spline shaft and extending the life.

[0014] Technical solutions to the problem

[0015] In order to achieve the above-mentioned object, the present invention provides a ball spline with a reinforced bushing portion, comprising: a spline shaft, which is in the shape of a rod and is formed with one or more track grooves extending in a concave manner along the length direction; a nut portion, which is inserted into the spline shaft and is formed to be movably formed along the length direction thereof; a plurality of balls, which are formed and circulated between the nut portion and the spline shaft, and the nut portion comprises: a nut, which is a hollow body inserted into the spline shaft; a retaining ring, which is formed on both sides of the nut in the length direction and is a hollow body inserted into the spline shaft,

[0016] Furthermore, at least one spline portion is formed on the nut portion, and the spline portion includes: a load track groove, which is formed in a concave manner along the length direction on the inner surface portion of the nut and is opposite to the track groove; a non-load circulation portion, which is formed in parallel with the load track groove along the length direction; a spline circulation groove, which is formed in the retaining ring, one side is opposite to the end of the load track groove, and the other side is opposite to the end of the non-load circulation portion and is formed in a curved concave manner. A part of the ball changes direction at the spline circulation grooves of the retaining rings on both sides in the length direction, and circulates between the track groove and the load track groove, and the non-load circulation portion.

[0017] The nut portion is further formed with one or more reinforcing bushing portions arranged in parallel with the spline portion, and the remaining portion of the balls contacts the outer surface of the spline shaft to transmit and circulate along the reinforcing bushing portions.

[0018] In the above, the track groove is formed in plurality, the spline portion and the reinforcement bush portion are formed in plurality respectively, and the spline portion and the reinforcement bush portion are formed alternately.

[0019] In the above, the track grooves are formed in two opposite directions, the spline parts are also formed in two, and the reinforcing bushing parts are formed in two between the spline parts.

[0020] In the above, the reinforced bushing portion includes: a bushing track groove, which is formed in a concave manner along the length direction on the inner surface of the nut and is opposite to the outer surface of the spline shaft; a bushing circulation portion, which is formed along the length direction side by side with the bushing track groove; a bushing circulation groove, which is formed on the retaining ring, one side is opposite to the end of the bushing track groove, and the other side is bent and concave opposite to the end of the bushing circulation portion,

[0021] The multiple balls circulating along the reinforced bushing part change direction in the bushing circulation grooves of the retaining rings on both sides in the length direction, and circulate along the outer surface of the spline shaft and the bushing track groove and the bushing circulation part.

[0022] In the above, the preload applied to the balls between the outer surface of the spline shaft and the bushing raceway groove is assembled so as to be smaller than the preload applied to the balls between the raceway groove and the load raceway groove.

[0023] Effects of the Invention

[0024] The ball spline with a reinforced bushing portion of the present invention is formed with a reinforced bushing portion, which can support the load applied by the ball of the reinforced bushing portion to the radial direction of the nut, and prevent pressure from occurring between the track groove and the ball. Thus, it has the following effects: it can prevent damage to the track groove caused by contact between the spline shaft and the ball, prevent deformation of the spline shaft, and increase the life of the ball spline. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A perspective view showing a ball spline of the prior art;

[0026] Figure 2 A cross-sectional view showing a spline shaft and a ball of a ball spline of the prior art;

[0027] Figure 3 A partially omitted perspective view is provided to show the ball spline with a reinforced bushing portion of the present invention;

[0028] Figure 4 A perspective view showing a nut formed in a ball spline of the present invention;

[0029] Figure 5 is a three-dimensional view of a retainer formed in a ball spline of the present invention;

[0030] Figure 6A partially cutaway perspective view showing a modified example of the ball spline of the present invention;

[0031] Figure 7 It is a cross-sectional view showing a spline shaft and balls of a ball spline according to the present invention. DETAILED DESCRIPTION

[0032] The ball spline with a reinforced bushing portion of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] Figure 3 A partially omitted perspective view is provided to show the ball spline with a reinforced bushing portion of the present invention; Figure 4 A perspective view showing a nut formed in a ball spline of the present invention; Figure 5 is a three-dimensional view of a retainer formed in a ball spline of the present invention; Figure 6 A partially cutaway perspective view showing a modified example of the ball spline of the present invention; Figure 7 It is a cross-sectional view showing a spline shaft and balls of a ball spline according to the present invention.

[0034] Below, we will Figure 3 The extending direction of the spline shaft (110) is recorded as "length direction".

[0035] like Figure 3 As shown, the ball spline 100 with a reinforced bushing portion according to the present invention includes: a rod-shaped spline shaft 110; a nut portion, which is inserted into the spline shaft 110 and can move along the length direction of the spline shaft 110; and a plurality of balls 150, which are formed and circulated between the nut portion and the spline shaft 110.

[0036] The nut portion includes: a nut 120, which is a cylindrical hollow body inserted into the spline shaft 110; and a retainer 130, which is formed on both sides of the nut 120 in the length direction and is a hollow body inserted into the spline shaft 110. The nut portion may further include a Figure 1 Reference numeral 7 shown in the figure denotes a ring-shaped seal.

[0037] The nut 120 is made of high carbon steel such as bearing steel. Figure 4 Reference numeral 123 denotes a flange protruding outward in the radial direction from one or both ends of the nut 120 in the longitudinal direction.

[0038] The retainer 130 is formed into a donut shape without the inner diameter of the disk. The retainer 130 can be made of engineering plastic (nylon 6, nylon 66, or glass fiber contained therein), or can be made of metal such as bearing steel like the nut 120. A hollow body, i.e., a seal, not shown in the figure, can be included between the nut 120 and the retainer 130. Figure 1As shown, the retainer 130 can be combined with the nut 120 by bolts.

[0039] The spline shaft 110 is formed with one or more track grooves 111 that are recessed and extend in the length direction. The spline shaft 110 can be manufactured by recessing the track grooves 111 on the outer surface of a rod having a circular cross section. The track grooves 111 are separated from each other in the circumferential direction to form a plurality of track grooves. Figure 2 As shown, the track grooves 111 may be formed with two at positions facing away from each other. A shaft mounting portion 113 with a reduced radius may be formed at the end of the spline shaft 110. A keyway (not shown) is formed in the shaft mounting portion 113, and a secondary gear or the like is mounted thereon.

[0040] One or more spline portions and a reinforcing bushing portion are formed on the nut portion.

[0041] The spline portion includes: one or more load track grooves 125, which are formed concavely in the length direction in the inner surface 121 of the nut 120, which is the hollow part into which the spline shaft 110 is inserted; and one or more non-load circulation parts 127, which are formed in the length direction in parallel with the load track grooves 125. The load track grooves 125 and the non-load circulation parts 127 are formed in the same number as the track grooves 111 formed in the spline shaft 110. The non-load circulation parts 127 form through holes in the nut 120 along the length direction thereof. The load track groove 125 is formed at a position opposite to the track groove 111.

[0042] A curved and concave spline circulation groove 133 is formed on the inner side of the retaining ring 130 facing the nut 120. There are more than one spline circulation groove 133. The number of the spline circulation grooves 133 is the same as the number of the track grooves 111. One side of the spline circulation groove 133 is opposite to the end of the load track groove 125, and the other side is opposite to the end of the non-load circulation part 127.

[0043] Some of the plurality of balls 150 change direction in the spline circulation grooves 133 of the retainer 130 on both sides in the longitudinal direction, are transmitted between the track groove 111 and the load track groove 125, and circulate along the non-load circulation portion 127. The circulation of the balls 150 is a well-known technology, so the description thereof is omitted.

[0044] The ball 150 contacts the track groove 111 at two points and contacts the load track groove 125 at two points, thereby forming a four-point contact transmission. Alternatively, the track groove 111 and the load track groove 125 may be in an arc shape with a larger radius of curvature than the radius of the ball 150 to form a two-point contact transmission. This is a well-known technology in the past, so the details thereof are omitted.

[0045] like Figure 4As shown, expanded track expansion parts 125a are formed at both ends in the length direction of the load track groove 125. When the ball 150 moves to the track expansion part 125a, the clearance of the ball 150 between the track expansion part 125a and the track groove 111 increases, and the ball 150 can smoothly move to the spline circulation groove 133 of the retaining ring 130, thereby suppressing or preventing the damage of the track groove 111 and the load track groove 125 caused by the ball 150.

[0046] The reinforcing bushing part is formed between the track grooves 111 of the spline shaft 110. A plurality of reinforcing bushing parts are formed. The reinforcing bushing parts and the spline parts are formed alternately.

[0047] In the following description, it is taken as an example that the track grooves 111 are opposite to each other and separated by an angle of 180° to form two, the spline parts are formed in two, and the reinforcing bushing parts are formed between the spline parts to form two.

[0048] The reinforcing bushing portion includes: one or more bushing track grooves 125-1 formed concavely along the length direction on the inner surface portion 121 of the nut 120; and one or more bushing circulation portions 127-1 formed along the length direction in parallel with the bushing track groove 125-1 at a position separated from the bushing track groove 125-1. The bushing track groove 125-1 is formed opposite to the outer surface of the spline shaft 110. The bushing circulation portion 127-1 may form a through hole in the nut 120 along the length direction thereof.

[0049] A bushing circulation groove 133-1 that is curved and recessed is formed on one side of the retaining ring 130 facing the nut 120. More than one bushing circulation groove 133-1 is formed. The bushing circulation groove 133-1 is formed between the spline circulation grooves 133. One side of the bushing circulation groove 133-1 is opposite to the end of the bushing track groove 125-1, and the other side is opposite to the end of the bushing circulation portion 127-1.

[0050] The remaining part of the multiple balls 150 changes direction in the bushing circulation groove 133-1 of the retaining ring 130 on both sides in the length direction, is transmitted to the outside of the spline shaft 110 and between the bushing track groove 125-1, and changes direction in the bushing circulation groove 133-1, is guided to the bushing circulation part 127-1, and moves and circulates along the bushing circulation part 127-1.

[0051] like Figure 4As shown, an expanded track expansion portion is formed at both ends of the bushing track groove 125-1 in the length direction. When the ball 150 moves to the track expansion portion, the clearance of the ball 150 in the track expansion portion 125a becomes larger, and it can smoothly move to the bushing circulation groove 133-1 of the retaining ring 130, thereby suppressing or preventing the bushing track groove 125-1 from being damaged by the ball 150.

[0052] like Figure 5 As shown, the inner surface 131 of the retainer is formed in a cylindrical shape, the spline circulation groove 133 and the bushing circulation groove 133-1 are open to the inner surface 131 of the retainer, and an inner surface opening 135 is formed on the inner diameter side to open to the inner surface 131 of the retainer. Therefore, no structure protruding inward from the inner surface 131 of the retainer is formed on the inner side of the retainer 130 in the radial direction, and the retainer 130 does not interfere with the track groove 111 when moving, and damage to the retainer 130 caused by interference with the track groove 111 can be prevented.

[0053] The diameter of the ball 150 formed in the ball spline 100 with a reinforced bushing portion of the present invention is larger than the interval between the load track groove 125 and the track groove 111 of the nut 120, and larger than the interval between the bushing track groove 125-1 and the outer surface of the spline shaft 110. Therefore, preload occurs between the load track groove 125 and the track groove 111 and between the bushing track groove 125-1 and the outer surface of the spline shaft 110.

[0054] The spacing between the bushing track groove 125-1 and the outer surface of the spline shaft 110 is larger than the spacing between the load track groove 125 and the track groove 111, so that the preload applied to the ball 150 between the outer surface of the spline shaft 110 and the bushing track groove 125-1 is smaller than the preload applied to the ball 150 between the track portion 111 and the load track groove 125. The reinforcing bushing portion is assembled with a smaller preload than the spline portion, so that the preload becomes smaller, and, as Figure 7 As shown, a phase of 90° is formed with the spline portion, so that the load supporting capacity in the right-angle direction is maximized. No track groove 111 is formed in the right-angle direction, but a reinforced bushing portion is provided for support, thereby preventing the rigidity of the spline shaft 110 from being reduced due to the processing of the track groove 111.

[0055] Therefore, the ball spline 100 of the present invention is formed with a reinforcing bushing portion to improve the radial load ( Figure 7 The rigidity in the "A" direction) is increased, thereby having the effect of extending the life of the ball spline.

[0056] The ball spline with a reinforced bushing portion of the present invention has been described with reference to the embodiments illustrated in the accompanying drawings, but they are only exemplary, and those skilled in the art of the present invention should understand that various modifications and other equivalent embodiments may be made therefrom. Therefore, the true technical protection scope should be defined according to the technical ideas of the claims.

[0057] Industrial Applicability

[0058] The ball spline with a reinforced bushing portion of the present invention has a greater rigidity and a longer service life.

Claims

1. A ball spline (100) having a reinforced bushing portion, characterized in that: include: A spline shaft (110) is in the shape of a rod and is formed with one or more track grooves (111) extending in a concave manner along the length direction; A nut portion inserted into the spline shaft (110) and formed to be movable along the length direction thereof; A plurality of balls (150) are formed and circulated between the nut portion and the spline shaft (110), The nut portion comprises: A nut (120) which is a hollow body inserted into the spline shaft (110); The retaining ring (130) is formed on both sides of the nut (120) in the length direction and is a hollow body inserted into the spline shaft (110). Furthermore, at least one spline portion is formed on the nut portion. The spline portion comprises: A load track groove (125) is formed concavely on the inner surface (121) of the nut (120) along the length direction and is opposite to the track groove (111); a non-load circulation portion (127) formed along the length direction in parallel with the load track groove (125); A spline circulation groove (133) is formed on the retaining ring (130) and is formed in a curved and concave manner with one side facing the end of the load track groove (125) and the other side facing the end of the non-load circulation part (127). A portion of the balls (150) changes direction in the spline circulation grooves (133) of the retaining rings (130) on both sides in the length direction, and moves in a circulation manner between the track groove (111) and the load track groove (125), and along the non-load circulation portion (127). The nut portion is also formed with one or more reinforcing bushing portions arranged in parallel with the spline portion, and the remaining portion of the balls (150) are in contact with the outer surface of the spline shaft (110) to transmit and circulate along the reinforcing bushing portions; The reinforcing bushing portion comprises: A bushing track groove (125-1) is formed concavely on the inner surface (121) of the nut (120) along the length direction and is opposite to the outer surface of the spline shaft (110); A bushing circulation portion (127-1) formed along the length direction in parallel with the bushing track groove (125-1); The bushing circulation groove (133-1) is formed on the retaining ring (130), with one side facing the end of the bushing track groove (125-1) and the other side facing the end of the bushing circulation part (127-1) in a bent and concave manner. A plurality of balls (150) circulating along the reinforced bushing portion change direction in the bushing circulation groove (133-1) of the retaining ring (130) on both sides in the length direction, and circulate along the outer surface of the spline shaft (110) and between the bushing track groove (125-1) and the bushing circulation portion (127-1); The preload applied to the ball (150) between the outer surface of the spline shaft (110) and the bushing track groove (125-1) is smaller than the preload applied to the ball (150) between the track groove (111) and the load track groove (125).

2. The ball spline (100) with a reinforced bushing portion according to claim 1, characterized in that: The track groove (111) is formed in plurality, the spline portion and the reinforcement bushing portion are formed in plurality respectively, and the spline portion and the reinforcement bushing portion are formed alternately.

3. The ball spline (100) with a reinforced bushing portion according to claim 2, characterized in that: The track grooves (111) are formed in two opposite directions, the spline parts are also formed in two, and the reinforcing bushing parts are formed in two between the spline parts.

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