JP2012026546A - Ball spline - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball spline which can improve lubricity without adding a new member.SOLUTION: A lubricant reservoir 21 opened to the radially outer side is disposed on a part between return passages 19 adjacent to each other of a retainer 15. The return passage 19 and the lubricant reservoir 21 are communicated to each other by means of a plurality of grooves 22 disposed at a desirable interval in the longitudinal direction. The return passage 19 and a main passage 18 are communicated to each other by means of a plurality of grooves 24 disposed at a desirable interval in the longitudinal direction on a wall 23 which separates the return passage 19 and the main passage 18 from each other.

Description

  The present invention relates to a ball spline.

  The ball spline includes a shaft provided with a plurality of spline tracks, and a ball spline outer cylinder fitted to the shaft via a ball. The ball spline outer cylinder is opposed to each spline track of the shaft. An outer cylinder main body having a plurality of spline tracks forming a passage, and a cage forming a plurality of return passages that are fitted to the inner periphery of the outer cylinder main body and communicate with each main passage between the outer cylinder main body and the outer cylinder main body. What it has is well known, and improving its lubricity is a challenge. Patent Document 1 describes improving lubricity by providing a lubricant supply member.

JP 2008-215482 A

  The ball spline of Patent Document 1 requires another member called a lubricant supply member in order to improve lubricity, and thus has a problem that the number of parts and assembly man-hours increase, resulting in an increase in cost.

  An object of the present invention is to provide a ball spline that can improve lubricity without adding a new member.

  A ball spline according to the present invention includes a shaft provided with a plurality of spline tracks, and a ball spline outer cylinder fitted to the shaft via a ball, and the ball spline outer cylinder faces each spline track of the shaft. The outer cylinder main body having a plurality of spline raceways forming a main passage and a plurality of return passages fitted into the inner periphery of the outer cylinder main body and communicating with each main passage are formed between the outer cylinder main body and the outer cylinder main body. In a ball spline having a container, a lubricant reservoir that opens radially outward is provided in a portion between adjacent return passages of the cage, and the return passage and the lubricant reservoir have their lengths. It is characterized by being communicated by a plurality of grooves provided at a required interval in the direction.

  Like the conventional cage, the cage is formed with a pocket and a return passage for suppressing the movement of the ball in the main passage in the radially inward direction. In addition, a lubricant reservoir and a plurality of grooves are formed. As a result, the lubricant (grease) can be supplied without a separate lubricant supply member.

  A plurality of spline tracks are provided in pairs, one that receives clockwise rotation and one that receives counterclockwise rotation. For example, a plurality of (for example, three) ball receiving portions are provided on the outer periphery of the shaft, and spline tracks are formed on the clockwise and counterclockwise sides of the ball receiving portions, respectively. Correspondingly, on the inner periphery of the outer cylinder body, a spline track that faces the clockwise spline track of the ball receiving portion from the clockwise direction and a counterclockwise spline track of the ball receiving portion counterclockwise. Spline tracks facing each other from the direction side are formed.

  The retainer has, for example, a return passage and a substantially cylindrical retainer body fitted to the inner periphery of the outer cylinder body, and a communication passage that connects the return passage and the main passage of the retainer body. And a cage lid that is abutted against the cage body from one end side. In this case, the ball rolls between the spline track formed on the shaft and the spline track formed on the outer cylinder body (main passage), and passes through the return passage of the cage body and the communication passage of the cage lid. , It is returned (circulated) back to the main passage. The cage may not be a divided product composed of a cage body and a cage lid, but may be an integrated product.

  When multiple pairs (for example, 3 pairs) of spline tracks are provided, the cage has multiple thick portions where return passages are formed between adjacent pairs of spline tracks. It is preferable that a plurality of lubricant reservoirs are provided at predetermined intervals in the circumferential direction by forming lubricant reservoirs at all of the plurality of locations.

  The lubricant reservoir is formed in a concave shape that is surrounded by walls on the four sides and opens radially outward, and the wall forming the return passage is removed at a predetermined interval in the length direction thereof, whereby the lubricant reservoir and A groove communicating with the return passage is formed.

  According to the ball spline of the present invention, the lubricant in the lubricant reservoir flows out into the return passage and lubricates the ball. As the lubricant in the return passage passes through the return passage, a part of the lubricant is pushed back into the lubricant reservoir, and there is little lubricant that stays in the return passage and resists the passage of the ball. Thus, the circulation resistance reduction effect is enhanced, and the lubricant can be supplied over a long period of time.

  The return passage and the main passage are preferably communicated with each other by a plurality of grooves provided at predetermined intervals in the length direction on the wall separating them. In this way, the lubricant in the return passage is partially supplied to the main passage by the ball passing through the return passage, and the lubricant is supplied to the place where the improvement of lubricity is most needed, The lubricity is further improved.

  The outer cylinder main body is made of carbon steel such as S45C and S55C or SAE4150 steel, but is not limited thereto. The cage is made of, for example, PEEK, but is not limited to this.

  The ball spline is preferably combined with a ball screw, a screw shaft provided with a ball screw raceway and an axially extending spline raceway, and a rotatable ball screwed to the ball screw raceway of the screw shaft via a ball. A screw nut and a ball spline outer tube that is fitted to the spline track via a ball and guides the axial linear motion of the screw shaft are included. When the screw shaft moves linearly in the vertical direction, the lubricant (grease) may drop downward, which may reduce the lubricity. The ball spline according to the present invention is more useful in such usage. It will be something.

  According to the ball spline of the present invention, a lubricant reservoir that opens radially outward is provided in a portion between adjacent return passages of the cage, and the return passage and the lubricant reservoir are required in the length direction thereof. The lubricant in the lubricant reservoir flows out into the return passage and lubricates the ball. That is, lubricity can be improved without a separate lubricant supply member. Also, the lubricant in the return passage is partly pushed back into the lubricant reservoir when the ball passes through the return passage, stays in the return passage, and resists the passage of the ball. As a result, the circulation resistance reduction effect is enhanced, and the lubricant can be supplied over a long period of time.

FIG. 1 is a longitudinal sectional view showing an embodiment of a ball spline according to the present invention. FIG. 2 is a transverse sectional view (sectional view taken along line II-II in FIG. 1). FIG. 3 is an enlarged perspective view of a main part.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the left and right refer to the left and right in FIG.

  1 to 3 show an embodiment in which a ball spline according to the present invention is applied to a ball screw with a ball spline.

  Ball screw with ball spline is for steel screw shaft (shaft) (1), ball screw nut (2), ball spline outer cylinder (3), many screw balls (4) and many splines. Has a ball (5).

  The screw shaft (1) is a solid shaft with a circular cross section, and on the outer peripheral surface of the screw shaft (1), a ball screw raceway (6) and a plurality of linear spline raceways (7) extending in the axial direction (left-right direction). ) And are formed.

  The ball screw nut (2) includes a cylindrical metal nut body (8) and a pair of annular synthetic resin end caps (9) attached to both axial end faces of the nut body (8). ing. The end cap (9) is composed of a short cylindrical ring having the same shape, and is fixed to both end surfaces in the axial direction of the nut body (8) using a coupling tool such as a bolt (not shown). The ball screw nut (2) is fitted on the outer periphery of the screw shaft (1) with a slight gap in the radial direction.

A ball screw raceway (10) corresponding to the ball screw raceway (6) is formed on the inner peripheral surface of the nut body (8). The space between the ball screw raceway (10) of the nut body (8) and the ball screw raceway (6) of the screw shaft (1) facing this is the main passage (11) where the ball (4) rolls. It has become. A return passage (12) is formed in the peripheral wall of the nut body (8). The return passage (12) includes a through-hole having a circular cross section that penetrates the nut body (8) over the entire length in the axial direction.
A groove-shaped direction changing path (13) for communicating the main passage (11) and the return passage (12) is formed on the end face of each end cap (9) on the nut body (8) side.

  The screw ball (4) is disposed in the main passage (11), the return passage (12), and the direction changing passage (13), and the screw ball (4) rolling on the main passage (11) is a screw shaft. It is designed to guide the relative rotation of (1) and the ball screw nut (2). A screw ball circulation path is constituted by the main path (11), the return path (12), and the direction changing path (13).

  The ball spline outer cylinder (3) includes a substantially cylindrical metal outer cylinder main body (14) and a substantially cylindrical retainer (15) fixed to the inner periphery of the outer cylinder main body (14). . The ball spline outer cylinder (3) is fitted to the outer periphery of the screw shaft (1) with a slight gap in the radial direction.

  A plurality of linear spline tracks (16) facing the spline track (7) of the screw shaft (1) are formed on the inner peripheral surface of the outer cylinder main body (14).

  The cage (15) includes a substantially cylindrical cage body (15a) and a cage lid (15b) that is abutted against the cage body (15a) from the right end side.

  The spline raceway (7) of the screw shaft (1) and the spline raceway (16) of the outer cylinder body (14) are paired with those that receive clockwise rotation and those that receive counterclockwise rotation. Three pairs are provided.

  A pocket (17) for holding a spline ball (5) that rolls between both spline raceways (7) (16) in a portion of the cage (15) corresponding to the spline raceway (16) of the outer cylinder body (14). ) Is formed. A space between the spline raceways (7) and (16) facing each other through the pocket (17) serves as a main passage (18) in which the spline ball (5) rolls. The retainer (15) is formed with a return passage (19) communicating with both left and right ends of the main passage (18) between the outer cylinder main body (14).

  The pocket (17) of the cage (15) has a tapered shape in which the opening on the radially outer side is larger than the opening on the radially inner side, and the radially intermediate portion is the spline ball (5). The spline ball (5) is held at a position where the main passage (18) can roll, and further movement inward in the radial direction is prevented.

  The spline ball (5) is disposed in the main passage (18) and the return passage (19), and the spline ball (5) rolling in the main passage (18) is connected to the screw shaft (1) and the ball spline. It guides the relative linear motion of the tube (3). The main passage (18) and the return passage (19) constitute a spline ball circulation path.

  A total of six spline ball circulation paths are provided, and a pair of main passages (18) are provided close to each other, and one pair of main passages (18) is on the counterclockwise side. Is provided with a return passage (19) on the counterclockwise side, and a return passage (19) is provided on the clockwise side for the one on the clockwise side, so that a pair of spline ball circulation paths is formed. A total of three pairs are arranged at equal intervals in the circumferential direction.

  With the above configuration, the retainer (15) has three thick portions where the return passages (19) are formed, and the retainer (15) has adjacent return passages (19). Lubricant reservoirs (21) are provided at all three of the thick portions in between.

  Both ends in the axial direction of the lubricant reservoir (21) are positioned inward of the axial ends of the cage (15), and both edges in the circumferential direction are inward of the return passage (19). By being positioned, the four sides are formed in a concave shape surrounded by walls and opened radially outward.

  The lubricant reservoir (21) and the return passage (19) are communicated with each other by a plurality of grooves (22) provided at predetermined intervals in the length direction. The return passage (19) and the main passage (18) are communicated with a wall (23) separating them through a plurality of grooves (24) provided at a predetermined interval in the length direction.

  According to the ball spline of the present invention, the lubricant reservoir (21) is filled with grease (lubricant), and this grease has a plurality of grooves (22 that communicate the lubricant reservoir (21) and the return passage (19). ) To flow into the return passage (19) and lubricate the spline balls (5). Part of the grease in the return passage (19) is pushed back to the lubricant reservoir (21) by the spline ball (5) passing through the return passage (19), and thereby the return passage (19). The amount of grease that stays inside and becomes resistant to the passage of the spline balls (5) is reduced, the effect of reducing the circulation resistance is increased, and the lubricant can be supplied over a long period of time. The grease in the return passage (19) also has a plurality of spline balls (5) passing through the return passage (19) so that a part of the grease communicates with the return passage (19) and the main passage (18). It flows to the main passageway (18) through the groove (24), whereby grease is supplied to the place where the improvement of lubricity is most needed, and the lubricity is further improved. Thus, grease can be supplied by the lubricant reservoir (21) and grooves (22) and (24) provided in the cage (15), and excellent lubricity can be secured without a separate lubricant supply member. .

  By rotating the ball screw nut (2) in the above state, the screw shaft (1) moves linearly in the axial direction without rotating, with the ball spline outer cylinder (3) as a guide. At this time, in the part of the ball screw nut (2), the screw ball (4) rolling in the main passage (11) is changed in direction by the direction changing path (13) of one end cap (9). Screw nut (4) that has been introduced into the return passage (12) of the nut body (8), moved in the return passage (12) toward the other end cap (9), and moved through the return passage (12). Is changed in the direction change path (13) of the other end cap (9) and introduced into the main path (11). Thus, the screw ball (4) is circulated through the screw ball circulation path. In the part of the ball spline outer cylinder (3), the spline ball (5) rolling on the main passage (18) is introduced from one end of the main passage (18) into the return passage (19) and returned. The inside of the passage (19) moves toward the other end of the main passage (18) and is introduced into the other end of the main passage (18). As a result, the spline ball (5) is circulated through the spline ball circulation path.

  The above ball screw with ball spline fixes the ball spline outer cylinder (3) so that it does not rotate or move to a fixed position in the axial direction, and rotates the ball screw nut (2) at a fixed position in the axial direction. It is used in a supported state so as not to move.

(1) Screw shaft (shaft)
(3) Ball spline outer cylinder
(5) Spline ball (ball)
(7) Spline track
(14) Outer cylinder body
(15) Cage
(16) Spline track
(18) Main passage
(19) Return passage
(21) Lubricant reservoir
(22) Groove
(23) Wall
(24) Groove

Claims (2)

A shaft provided with a plurality of spline tracks and a ball spline outer cylinder fitted to the shaft via a ball are provided, and the ball spline outer cylinder forms a main passage so as to face each spline track of the shaft. An outer cylinder main body having a plurality of spline tracks, and a cage that is fitted to the inner periphery of the outer cylinder main body and forms a plurality of return passages communicating with the main passages between the outer cylinder main body and the outer cylinder main body. In ball spline,
A lubricant reservoir that opens radially outward is provided in a portion between adjacent return passages of the cage, and the return passage and the lubricant sump are a plurality of portions provided at predetermined intervals in the length direction. A ball spline characterized by being connected by a groove.   2. The ball spline according to claim 1, wherein the return passage and the main passage are communicated with each other by a plurality of grooves provided at predetermined intervals in a length direction on a wall separating the return passage and the main passage.

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