JP2019157936A - Finite ball spline - Google Patents

Abstract

To increase rated load by increasing the number of rolling elements; and a lubricant reservoir groove is formed by a finite ball spline in the raised part, where a holding hole is formed, so as to smooth rolling element lubrication.SOLUTION: The finite ball spline comprises: a spline shaft 1 having at least a pair of raceway grooves 7; an external cylinder 2 that is inserted into the spline shaft 1 via a ball 9 having a raceway groove 8 facing the raceway groove 7; and a ball bearing cage 3 disposed between the external cylinder 2 and the spline shaft 1 and formed with holding holes 11 for holding balls 9, respectively. The holding hole 11 is formed in a pair of arc planar raised parts 5 extending in the longitudinal direction; and grooves 10 serving as lubricant reservoirs communicating with the holding holes 11 are formed in the raised parts 5 between the holding holes 11 so as to extend in the longitudinal direction.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a finite type ball spline provided with a cage.

  Conventionally, as a finite stroke type motion guide device, in general, a stationary member having a rolling groove of a rolling element, and a rolling groove of the rolling element at a position opposite to the rolling groove of the stationary member and the rolling member. A movable member assembled to the stationary member via a large number of rolling elements rolling on the running groove, and a rolling element cage arranged between the stationary member and the movable member to align the rolling elements. A finite ball spline is known. In such a finite ball spline, for example, the rolling element cage has a long rolling element holding hole that is rotatably accommodated as a set of two rolling elements that roll in the same rolling groove. The rolling element holding hole is formed so that the opening width in the longitudinal direction of one opening facing the fixed side member side or the moving side member is smaller than the diameter of two rolling elements. (For example, refer to Patent Document 1).

  Also known is a linear motion bearing with a rotary bearing that linearly reciprocates a shaft body with high accuracy. The linear motion bearing with a rotary bearing includes a linear motion bearing in which a shaft body is accommodated in a cylindrical body so as to be non-rotatably slidable, and is spaced from each other along the longitudinal direction of the cylindrical body. It is composed of two or more rotary bearings that are mounted. In the linear motion bearing with a rotary bearing, the diameter of the outer peripheral surface of the cylindrical body is constant in the length direction of the cylindrical body, and the rotary bearing has a circumferential groove formed on the outer peripheral surface of the cylindrical body, Accommodates a plurality of arranged rolling elements, an annular rolling element holder that rotatably holds a part of each rolling element protruding to the outer peripheral side, and each rolling element portion protruding from the cage It is comprised from the cyclic | annular body which equipped the inner peripheral surface with the surrounding groove (for example, refer patent document 2).

JP 2011-163506 A JP 2010-112554 A

  However, in the above-mentioned finite stroke type motion guide device, since two balls are held by one holding hole, the balls come into contact with each other in the opposite directions of rotation at the contact portions of adjacent balls. There is a possibility that the durability may be reduced due to problems such as wear of the ball, and there is a problem with ball lubrication because the lubricity with respect to the ball is not considered.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and a cage for holding a ball as a rolling element is disposed between a spline shaft and an outer cylinder, and a holding hole for holding the ball is provided in the cage. Formed in ridges that are spaced apart at a predetermined interval, and formed grooves in the ridges that communicate the holding holes. The ball is lubricated through the groove to improve durability, and it is possible to increase the number of balls of rolling elements by reducing the dimension between the holding holes and increase the rated load without changing the longitudinal dimension of the cage. It is to provide a finite ball spline characterized by the above.

According to the present invention, there is provided a spline shaft including at least a pair of first raceway grooves, each of which is formed in a longitudinal direction on both sides of the outer peripheral surface facing the radial direction and in which a ball as a rolling element rolls; Opposing second raceway grooves are formed on the inner circumferential surface in the longitudinal direction, and are respectively formed between the outer cylinder and the spline shaft, and an outer cylinder through which the spline shaft is inserted through the ball. In a finite ball spline consisting of a cylindrical cage formed with a plurality of holding holes each holding a ball,
The cage has ridges extending in the longitudinal direction and spaced apart at predetermined intervals on the inner and outer peripheral surfaces. The ridges are respectively rolled into the first track groove and the second track groove. The holding holes for holding the balls are formed, and the protruding portions between the holding holes are each provided with a groove extending in the longitudinal direction and serving as a lubricant reservoir portion communicating with the holding hole. The present invention relates to a finite ball spline that is formed.

  Further, the groove formed in the raised portion provided in the cage is formed on an outer circumferential arc surface of the raised portion.

  The diameter of the holding hole formed in the raised portion on the inner peripheral surface side of the cage is formed smaller than the diameter of the ball.

  The first raceway groove and the second raceway groove are formed in a Gothic arch shape.

  In addition, fitting grooves into which retaining rings are fitted are formed on the inner peripheral surfaces of both ends of the outer cylinder. Further, a mounting screw hole for mounting a mating member is formed on the outer peripheral surface of the outer cylinder.

  In the finite ball spline according to the present invention, as described above, in order to hold the ball as the rolling element in the cage, the holding holes are formed in the raised portions provided at predetermined intervals in the longitudinal direction. Since a groove is formed to communicate with the holding hole adjacent to the outer circumferential arc surface, and the groove is formed in the lubricant reservoir to lubricate the ball, the adjacent holes do not come into contact with each other by the holding hole. In addition, problems such as wear due to contact between balls can be avoided. Furthermore, since the adjacent holding holes of the cage are communicated with each other by a groove and configured as a lubricant reservoir, the lubricant that temporarily accumulates excess lubricant supplied to the finite ball spline in the groove and lubricates the ball Since the lubricant accumulated in the lubricant reservoir is supplied to the holding hole and attached to the ball as appropriate, the lubrication state can be maintained over a long period of time and durability can be further improved. It can be improved. In addition, this finite ball spline does not provide a groove to be a lubricant reservoir for each holding hole, but allows the holding holes to communicate with each other by forming a groove between adjacent holding holes in the common reservoir for lubricant. By doing so, the space | interval between holding holes can be narrowed, the number of balls which are rolling elements can be increased and the rated load can be increased without changing the dimensions of the cage.

It is a perspective view which shows one Example of the finite ball spline by this invention. 1 shows the finite ball spline of FIG. 1, (A) is a side view showing the finite ball spline of FIG. 1, and (B) is an end view of (A). It is an expanded sectional view showing a finite ball spline in line segment AA of Drawing 2 (B). It is a perspective view which shows the outer cylinder integrated in the finite ball spline of FIG. It is a top view which shows the retaining ring fitted by the fitting groove formed in the both ends of the outer cylinder which comprises the finite ball spline of FIG. It is a perspective view which shows the holder | retainer integrated in the finite ball spline of FIG. 6 shows the cage of FIG. 6, (A) is a side view showing the cage, [B] is a cross-sectional view showing the cage in the line segment BB described in (A), and (C) is (A). It is sectional drawing which shows the holder | retainer in line segment CC as described in. 6 shows the cage of FIG. 6, (A) is a side view showing the cage in a state where a ball as a rolling element is held in the holding hole, and [B] is a holding in the line segment DD described in (A). It is sectional drawing which shows a container. It is a fragmentary sectional view which shows the area | region of the code | symbol E of the finite ball spline of FIG.

  The finite ball spline according to the present invention can be used by being incorporated in, for example, a high-precision finite stroke ball spline that can be applied to a semiconductor manufacturing apparatus, an inspection / measurement apparatus, or the like. This finite ball spline has a small variation in sliding resistance value, and can realize light and smooth sliding even when a vertical shaft is used. In addition, this finite ball spline can exhibit high positioning accuracy stably in the stroke direction, and is preferable for application to various devices for chip mounters, vertical shafts, and high tact operation.

  An embodiment of the finite ball spline according to the present invention will be described below with reference to FIGS. The finite ball spline according to the present invention generally has a pair of raceway grooves 7 (first raceway grooves 7) that are formed on both sides of the outer peripheral surface 19 in the radial direction and that extend in the longitudinal direction and roll the balls 9 as rolling elements. ) And a raceway groove 8 (second raceway groove) opposite to the raceway groove 7 are formed in the inner circumferential surface 20 in the longitudinal direction, and the spline shaft 1 is inserted through the balls 9. The outer cylinder 2 and the cylindrical body 13 are arranged between the outer cylinder 2 and the spline shaft 1 and are formed with a plurality of holding holes 11 for holding the balls 9 respectively. 3 has a feature. The finite ball spline is formed as a two-row ball spline in which a pair of raceway grooves 7 and 8 are formed. In addition, the track grooves 7 and 8 provided in the spline shaft 1 and the outer cylinder 2 are not limited to a pair, and can be appropriately provided, for example, two pairs.

  In this finite ball spline, the retainer 3 has, in particular, raised portions 5 extending in the longitudinal direction and spaced apart at predetermined intervals on the inner and outer peripheral surfaces 14 and 15. In this finite ball spline, in particular, the raised portion 5 is formed with holding holes 11 for holding the balls 9 that roll into the raceway grooves 7 and the raceway grooves 8, respectively. Are characterized in that grooves 10 extending in the longitudinal direction are formed, which extend in the longitudinal direction and serve as lubricant reservoirs communicating with the holding holes 11. The depth of the groove 10 formed in the raised portion 5 can be set as appropriate in consideration of the strength of the cage 3. For example, the raised portion 5 has an inner circular arc surface 16, an outer circular arc surface 18, If the raised portion 5 is a virtual circle formed by the inner circumferential side arc surface 16 and the outer circumferential side arc surface 18, the depth can be set not to exceed the outer circumferential side arc surface 18. It is preferable.

  In this finite ball spline, in other words, the raised portions 5 are formed corresponding to the number of balls 9 spaced along the axial direction of the cage 3, and the balls 9 are placed on these raised portions 5. A holding hole 11 for holding is formed. The balls 9 are held in the holding holes 11 of the cage 3 so that one ball 9 is held in one holding hole 11 so that adjacent balls 9 do not contact each other. In addition, a groove 10 serving as a lubricant reservoir is formed between the holding holes 11 of the raised portion 5 on the outer peripheral surface 15 side of the cage 3 so that the adjacent holding holes 11 can share the groove 10. The holding holes 11 communicate with each other through a groove 10. This finite ball spline is configured so that the balls 9 are individually held in the holding holes 11 and the adjacent balls 9 are not in contact with each other by the above-described configuration. Can be prevented. Furthermore, the groove 10 formed between the holding holes 11 of the cage 3 functions as a lubricant reservoir, temporarily storing excess lubricant, and accumulating as the lubricant decreases. Since the lubricant is appropriately supplied to the balls 9, a good lubrication state can be maintained for a long period of time, and durability can be improved and a long-life finite ball spline can be provided.

  Further, on the inner peripheral surface 20 of the outer cylinder 2, fitting grooves 12 are formed at both end portions 17, and C-ring-shaped retaining rings 4 are fitted into the fitting grooves 12. This finite ball spline is configured in a finite type by restricting the movement of the cage 3 so that the retaining ring 4 fitted in the fitting groove 12 of the outer cylinder 2 does not come out in the longitudinal direction of the cage 3. That is, the finite ball spline is configured to move finitely as the ball 9 moves between the retaining rings 4 along the raceway grooves 7 and 8. The cage 3 can be produced by appropriately selecting a metal or resin material.

  Further, in this finite ball spline, the groove 10 formed in the raised portion 5 provided in the cage 3 is formed on the outer peripheral side arc surface 18 of the raised portion 5. Further, the diameter of the holding hole 11 formed in the raised portion 5 on the inner peripheral surface 14 side of the cage 3 is formed smaller than the diameter of the ball 9, and the ball 9 is inward at the periphery of the holding hole 11. Dropout is regulated. In this finite ball spline, the raceway grooves 7 and 8 are formed in a Gothic arch shape. The outer cylinder 2 is formed with mounting screw holes 6 for mounting a mating member spaced apart at predetermined intervals in the axial direction.

  This finite ball spline is preferable for use in a relative reciprocating movement part of an inspection / measurement device, a semiconductor manufacturing device, a machine tool, various assembly devices, various robots, an inspection device and the like.

DESCRIPTION OF SYMBOLS 1 Spline shaft 2 Outer cylinder 3 Cage 4 Retaining ring 5 Raised part 6 Mounting screw hole 7 Track groove (1st track groove)
8 Track groove (second track groove)
9 Ball 10 Groove 11 Holding hole 12 Fitting groove 13 Cylindrical body 14, 20 Inner peripheral surface 15, 19 Outer peripheral surface 16 Inner peripheral arc surface 17 End 18 Outer peripheral arc surface

Claims (6)

A spline shaft that extends in the longitudinal direction on both sides of the outer peripheral surface facing the radial direction and has a first raceway groove on which a ball as a rolling element rolls, and a second that faces the first raceway groove. A raceway groove is formed on the inner peripheral surface in the longitudinal direction and is formed between the outer cylinder through which the spline shaft is inserted, and is disposed between the outer cylinder and the spline shaft and holds the balls. In a finite ball spline consisting of a cylindrical cage with a plurality of holding holes to be
The cage has ridges extending in the longitudinal direction and spaced apart at predetermined intervals on the inner and outer peripheral surfaces. The ridges are respectively rolled into the first track groove and the second track groove. The holding holes for holding the balls are formed, and the raised portions between the holding holes are respectively formed with grooves that serve as lubricant reservoirs extending in the longitudinal direction and communicating with the holding holes. A finite ball spline.   2. The finite ball spline according to claim 1, wherein the groove formed in the raised portion provided in the retainer is formed in an outer circumferential arc surface of the raised portion.   3. The finite ball according to claim 1, wherein a diameter of the holding hole formed in the raised portion on the inner peripheral surface side of the cage is smaller than a diameter of the ball. spline.   The finite ball spline according to any one of claims 1 to 3, wherein the first raceway groove and the second raceway groove are formed in a Gothic arch shape.   The finite ball spline according to any one of claims 1 to 4, wherein a fitting groove into which a retaining ring is fitted is formed on the inner peripheral surface of both ends of the outer cylinder. .   The finite ball spline according to any one of claims 1 to 5, wherein a mounting screw hole for mounting a mating member is formed on an outer peripheral surface of the outer cylinder.

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