JPS636508Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention comprises an outer cylinder mounted on a spline shaft so as to be movable without rotation via a group of balls housed in the outer cylinder. This relates to ball spline bearings.

BACKGROUND TECHNOLOGY Conventional ball spline bearings, for example,
Figure (see Japanese Patent Application No. 46-49508), Figure 13 (Japanese Patent Application No.
46-70319), a wide and deep groove with a U-shaped cross section is formed on the inner peripheral surface of the outer cylinder, and the loaded and non-loaded parts of the ball are arranged in the circumferential direction of the inner peripheral surface. Although these were provided alternately, each of these had drawbacks that will be described later.

In a first conventional example shown in FIG. 12, load grooves 41 having a U-shaped cross section and non-load grooves 42 having a deeper U-shaped cross section are alternately recessed in the inner peripheral surface of an outer cylinder 40. A load path 45 is formed in the load groove 41 in which a load is supported between the outer cylinder 40 and the spline shaft 44 via a group of balls 43, and a load path 45 is formed in the non-load groove 42 to support the load between the outer cylinder 40 and the spline shaft 44. retainer 4 fitted into
Return passages 47 and 47 are formed in recesses in 6 and 46, respectively.

In the second conventional example shown in FIG.
and wide no-load grooves 50 are alternately recessed, and a retainer 52 for holding a group of balls 51 is fitted into both the grooves 49, 50.

Problems to be Solved by the Invention In the first conventional example, the unloaded groove 42 in which the return path 47 is formed is deeper than the load groove 41 in which the load path 45 is formed. When the outer surface of the outer cylinder 40 is made into a cylindrical shape, the wall thickness of the outer cylinder 40 in the portion where the no-load groove 42 is provided becomes thinner, so if the strength of the entire outer cylinder 40 is to be maintained at a predetermined value, It is necessary to increase the wall thickness of the outer cylinder 40 in which the no-load groove 42 is provided,
Therefore, the outer diameter of the outer cylinder 40 as a whole becomes large, resulting in a disadvantage that the ball spline bearing becomes large. In addition, since the load path 45 groups are unevenly distributed within the load grooves 41 at three locations as shown in FIG.
When a load is applied from the outer surface of the outer cylinder 40 at the part of the no-load groove 42 provided between the outer cylinders 41 and 41, the bending of the outer cylinder 40 increases, causing bending strain in the axial direction of the outer cylinder 40. This causes problems with accuracy as a ball spline bearing, and the outer cylinder 40
When the spline bearing moves back and forth on the spline shaft 44, it also causes an increase in sliding resistance, so from this point of view as well, it was inevitable to increase the size of each member of the spline bearing, especially the outer cylinder 40, in order to improve its strength.

The retainers 46, 46 are made of molded bodies such as plastic or sintered metal, and are divided into three parts, including the load groove 41 and the non-load groove 42 formed on the inner peripheral surface of the outer cylinder 40. Since the ball 43 group is fitted as an endless circulation path, a pitch shift between the load path 45 and the return path 47 actually occurs. Since the circulation resistance increases during the endless circulation of the ball spline bearing, the frictional resistance as a ball spline bearing increases. In addition, since the number of parts increases, the number of processing and assembly steps increases, which also contributes to increased costs.
Furthermore, when the outer cylinder 40 and the retainer 46 are made of different materials, based on the difference in coefficient of thermal expansion, when a ball spline bearing is used in a high temperature atmosphere,
In particular, the above-mentioned pitch deviation becomes large, and the contact state and rolling state of the balls 43 with the retainer 46 change, resulting in an increase in frictional resistance as a ball spline bearing.

Further, in the second conventional example, the retainer 52
is made by press forming a steel plate, and in addition to the drawbacks of the conventional example, there is a drawback that the retainer 52 resonates when the ball spline bearing vibrates.
Vibration tends to cause fretting at the point of contact with the outer cylinder 48, causing a reduction in the life of the bearing.

As mentioned above, the conventional type has a small load capacity and is large in proportion to its load capacity, and does not have the above-mentioned disadvantages.
There has been a desire for a highly practical ball spline bearing that has a large load capacity, low frictional resistance, a smaller shape, and is less expensive.

Means for Solving the Problems The present invention provides that the spline shaft is a column whose cross section perpendicular to the axis is a substantially truncated equilateral triangle with an arcuate portion, and whose truncated top surface has a large width and is partially cylindrical. Six rolling raceways are recessed in the axial direction at approximately equal intervals with a center angle of approximately 60° on both side edges of the three side surfaces of the equilateral triangular prism shape and on the boundary line with the truncated top surface of the partially cylindrical shape. Six load tracks are recessed in the inner circumferential surface of the cylinder, directly facing the six rolling tracks, and the load tracks and the rolling tracks each rollably sandwich a group of balls.
Load paths are formed at nearly equal intervals with center angles of about 60 degrees, and the outer cylinder has load paths facing each side of the equilateral triangular prism of the spline shaft.
Two return paths for the ball group are formed adjacent to each other in the axial direction and parallel to each other at a position intermediate between the two load tracks,
Are the load path and return path equidistant from the axis?
By adopting a configuration in which the return path can be formed closer to the axis than the load path, the above-mentioned problems can be solved.

Effects The present invention has the above-mentioned configuration, so that the load paths are formed at nearly equal intervals, and the return paths are formed at positions facing each of the three sides of the spline shaft whose cross section is a substantially truncated equilateral triangle. Since the load applied to the outer cylinder is distributed almost equally to the balls in each load path, and the return path can be formed closer to the axis than the load path, the wall thickness of the outer cylinder can be reduced. There is no need to make the bearing particularly thick, the outer diameter can be made small, and it can be made lightweight.Moreover, the accuracy of the ball spline bearing is improved, there are no vibration problems, sliding resistance is reduced, and the number of parts can be reduced. Decreased,
It has also become possible to reduce costs.

Embodiment In the first embodiment shown in FIGS. 1 to 6, both straight paths, a load path 2 and a return path 3, are provided in the outer cylinder 1, and as shown in FIG. ，
Six sets of endless circulation paths 5, 5 are formed by connecting both ends of the outer cylinder 1 to allow four groups of balls to circulate endlessly. This is a ball spline shaft loaded onto a spline shaft 6 so as to be able to run freely in the axial direction without moving. The column has a substantially truncated equilateral triangular shape with a partially cylindrical truncated top surface 7, 7 having a large width b. On the boundary line with the partially cylindrical truncated top surface 7, six shallow partially cylindrical rolling tracks 9, 9 are recessed in the axial direction at approximately equal intervals with a center angle of approximately 60 degrees.
The truncated top surface 7 may be a part of a cylindrical surface, as shown in the illustrated example, or may be a flat surface.

Further, six load raceways 10, 10 are recessed in the inner peripheral surface of the outer cylinder 1, directly facing each of the six rolling raceways 9, 9 of the spline shaft 6. six load paths 2 each holding four groups of balls in a rolling manner by the rolling track 9;
2 are formed at nearly equal intervals with center angles of about 60 degrees, and the outer cylinder 1 has both load tracks at positions facing each of the equilateral triangular prism-shaped side surfaces 8, 8 of the spline shaft 6. Ball 4 in the middle position between 10 and 10
Two return paths 3, 3 of the group are formed adjacent to each other in the axial direction in parallel, and the load path 2 and the return path 3 can be formed at the same distance from the axis, or the return path can be formed closer to the axis than the load path. It is said that

In this embodiment, as shown in FIG.
Three shallow U-shaped wide load grooves 11, 11 are formed on the inner peripheral surface of the spline shaft 6, extending over the truncated top surface 7 of the spline shaft 6 and the rolling raceways 9, 9 on both sides of the top surface 7, respectively. The load grooves 11 are recessed in opposing widths.
Load raceways 10, 10 that directly oppose the rolling raceways 9, 9 of the spline shaft 6 are recessed on both side edges of the spline shaft 6, and between the three load grooves 11, 11 on the inner peripheral surface of the outer cylinder 1, the load raceways 10, 10 are recessed. U-shaped non-load grooves 12, 12, which are narrower and less deep than the load groove 11, are recessed to face each side surface 8, 8 of the spline shaft 6, and are formed on the inner circumferential surface of the outer cylinder 1. A cage 13 is fitted over each load groove 11, 11 and each non-load groove 12, 12, and as shown in FIG. The return passages 3, 3 are formed as holes in the retainer 13 in the no-load groove 12, and as shown in FIG.
The direction change paths 5, 5 are also recessed in the cage 13. The 4 groups of balls are provided in a protruding manner within the cage inner circumferential surface 14 only while in the load path 2, and roll within the cage 13 while in the direction change path 5 and the return path 3.

As shown in FIG. 4, the retainer 13 is
The retaining rings 16, 16 are fitted into the ring grooves 17, 17 formed near both ends of the inner circumferential surface of the outer cylinder 1, as shown in FIGS. 4 to 6. A container 13 is locked to the outer cylinder 1 at both ends.

As shown in FIG. 2, instead of the rolling tracks 9, 9 of the spline shaft 6, rolling tracks 9a, 9 are arranged at equal intervals around the axis.
By forming 9a, it is also possible to form six completely equally spaced load paths.

As shown in FIGS. 1 and 6, on the inner circumferential surface of the outer cylinder 1, a protrusion 18 is provided between the load groove 11 and the non-load groove 12.
18 is provided in a protruding manner, and is formed on the load track 10 on the load groove 11 side of the protruding portion 18, and the protruding strip 18 prevents rotation of the retainer 13 fitted to the inner circumferential surface of the outer cylinder 1. are doing.

FIG. 7 shows an example of application of the first embodiment described above. As is clear from comparison with FIG. 1, in this application example, one of the load grooves 11 of the outer cylinder 1 in the first embodiment and two sets of endless circulation paths located on both sides of the load groove 11 are used. The outer cylinder 19 including the outer cylinder 1 and 1/3 of the retainer 13 are removed, and 1/3 of the spline shaft 6 including one of the truncated top surfaces 7 of the spline shaft 6 in the first embodiment is mounted on a pedestal. 20 rail body 2
1, an infinite linear motion bearing can be formed in which the support body 22, which is supported and engaged with the outer cylinder body 19 through four groups of balls, can travel in a straight line on a long rail body 21. .

Next, a second embodiment shown in FIGS. 8 to 11 will be described. This embodiment also has two straight paths, a load path 24 and a return path 25, inside the outer cylinder 23, and direction change paths 26, 26 that connect both ends of the straight paths 24, 25 to allow the four groups of balls to circulate endlessly. A ball spline in which six sets of endless circulation paths are formed, and the outer cylinder 23 is mounted on a spline shaft 6 so as to be freely movable in the axial direction without rotation via four groups of internally installed balls. The spline shaft 6 is a bearing, and the spline shaft 6 has a substantially truncated equilateral triangular shape with a circular arc portion in cross section perpendicular to the shaft, and a partially cylindrical truncated top surface 7 with a large width. The partially cylindrical truncated top surface 7 is formed at both side edges of the three side surfaces 8, 8.
Six rolling raceways 9, 9 are recessed in the axial direction at approximately equal intervals with a center angle of approximately 60° on the boundary line,
The six rolling tracks 9,
Six load raceways 28, 28 are recessed directly facing the load raceway 9, and the load raceway 28 and the rolling raceway 9,
Six load paths 24, 24 each holding four groups of balls in a rollable manner are formed at nearly equal intervals with center angles of approximately 60 degrees, and the outer cylinder 23 is provided with the Each side of an equilateral triangular prism 8,8
Two return paths 25 for four groups of balls are formed adjacent to each other in the axial direction and parallel to each other in the intermediate position between the load paths 28 and 28, and in this embodiment also, the return paths 25 for the four groups of balls are formed in parallel to each other in the axial direction. The return path 25 can be formed at the same distance from the axis or closer to the axis than the load path 24.

In this embodiment, unlike the previous embodiment, the load track 28 and the return path 25 are directly recessed in the inner peripheral surface of the outer cylinder 23, and as shown in FIG. , each of which has protruding road edges 29, 29 whose width is narrower than the diameter of the ball 4, so that the ball 4 is exposed nearly halfway and can roll, and does not escape.

In this embodiment, the direction change path 26 is the outer cylinder 23.
However, it is difficult to form the load track 28 and the return path together, and as shown in FIGS. 10 and 11, side tubes 30,
30 is provided separately, and the side tube 30 is screwed onto the outer tube 23 with a bolt 31, and direction change paths 26, 26 are formed in the side tube 30.

In this embodiment, since both straight paths, the load track 28 and the return path 25, are formed directly on the inner circumferential surface of the outer cylinder 23, the straight paths 28 and 25 are located close to each other at equal distances from the axis. It is also possible to form the return path 25 closer to the axis than the load track 28. In this case, the side surface 8 of the spline shaft 6,
8 is the return path 2 as shown in FIGS. 8 and 9.
It is possible to make the inner cylindrical side surface 8a projecting as long as it does not come into contact with the 4 groups of balls in 5,
The bending strength of the spline shaft 6 is increased.

Unlike the previous example, this example does not use a cage, so the number of parts is smaller, the assembly work is easier, and there is no pitch deviation in the straight path between the cage and the outer cylinder. , the frictional resistance factor that may occur between the balls and the retainer part can be reduced. Since both the straight paths of the load track 28 and the return path 25 can be processed simultaneously by broaching the outer cylinder, both straight paths can be processed with high precision, further improving the accuracy with which the ball spline bearing is maintained. In addition, since there is no cage, there is less wear on the contact surfaces between the bearing parts, which can reduce the fretting between the outer cylinder and the cage that often occurs with conventional ball spline bearings. No reduction in service life occurs.

Effects of the invention By adopting the configuration described in the claims for utility model registration, the present invention allows the load paths to be formed at more equal intervals (equal pitch), preventing pitch deviation, and reducing the circulation resistance of the balls. Therefore, the wear resistance as a ball spline bearing is low, and it is possible to maintain a more uniform load capacity against loads applied to the spline shaft from any direction, thereby reducing the strength of the outer cylinder. Since the return path is formed in a position where the outer cylinder is not exposed to a load, the deflection of the outer cylinder is made more uniform, especially against loads from any direction, so the wall thickness of the bearing outer cylinder can be made thinner, and parts Since there are fewer parts, it is possible to reduce assembly and processing man-hours, which reduces costs.Since there are no parts that resonate with the vibration of the bearing, there is no fretting between parts, and the life of the bearing can be extended. It is possible to achieve an effect that is not available in the conventional methods in that it is possible to realize an increase in the amount of water.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the first embodiment, Figure 2 is an end view of the spline shaft embodiment, Figure 3 is a perspective view of the same as above, and Figure 4 is the first embodiment with the spline shaft removed. 5 is a partial vertical sectional view of the load path, FIG. 6 is a longitudinal sectional view of the axial center of the outer cylinder only, FIG. 7 is a cross-sectional view of an application example, and FIG. FIG. 9 is an enlarged cross-sectional view of the same part, FIG. 10 is a cross-sectional view of only the outer cylinder in FIG. The elevation view, FIGS. 12 and 13 are cross-sectional views of the conventional example. 1, 23: Outer cylinder, 2, 24: Load path, 3, 2
5: return path, 4: ball, 5, 26: direction change path, 6: spline shaft, 7: truncated top surface, 8: side surface, 9: rolling raceway, 10, 28: load raceway, 1
1: Load groove, 12: No-load groove, 13: Cage, 1
4: Inner peripheral surface of cage, 15: Outer surface of spline shaft,
30: Side tube.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. An endless circulation path in the outer cylinder, consisting of both straight paths, a load path and a return path, and a direction change path that connects both ends of the straight paths to allow a group of balls to circulate endlessly. In the ball spline bearing, the outer cylinder is mounted on a spline shaft so as to be freely movable in the axial direction without rotating through a group of balls contained therein. The right-angled cross section is a substantially truncated equilateral triangle with a circular arc portion remaining, and the truncated crest is partially cylindrical and has a large width on the truncated crest. Six rolling tracks are recessed in the axial direction at approximately equal intervals with a center angle of approximately 60° on the boundary line with the surface, and the six rolling tracks at approximately equal intervals are formed on the inner circumferential surface of the outer cylinder. Directly facing the track, six load tracks are similarly spaced at approximately equal intervals, and the six load tracks that rollably sandwich a group of balls are formed by the load tracks and the rolling track. omitted
They are formed at nearly equal intervals of 60 degrees, and the outer cylinder has a return path for a group of balls at a position midway between the two load tracks, at a position facing each side of the equilateral triangular prism of the spline shaft. are formed adjacent to each other in parallel in the axial direction, and the load path and the return path can be formed equidistant from the axis, or the return path can be formed closer to the axis than the load path. Ball spline bearing. 2. Three shallow U-shaped wide load grooves are recessed in the inner circumferential surface of the outer cylinder, each extending across the truncated top surface of the spline shaft and the rolling raceway on both sides of the top surface, and having a width that faces each other. , a load raceway that directly faces the rolling raceway of the spline shaft is recessed on both side edges of the load groove, and a load raceway narrower than the load groove is provided between the three load grooves on the inner circumferential surface of the outer cylinder. Further, U-shaped no-load grooves that are not deeper are recessed to face each side of the spline shaft, and a retainer is fitted to the inner circumferential surface of the outer cylinder over each of the load grooves and each no-load groove. , the inner peripheral surface of the retainer is formed into a hole of approximately the same shape as the entire outer surface of the spline shaft, and a return path is recessed in the retainer in the no-load groove, and a direction change path is also provided. A ball spline bearing according to claim 1, wherein the cage is recessed. 3 Utility model registration in which both the load track and the return path are directly recessed into the inner circumferential surface of the outer cylinder, and a side cylinder is installed with direction change paths bored at both ends of the outer cylinder in the direction of travel. A ball spline bearing according to claim 1.