JPS59187112A - Ball bearing for linear movement shaft - Google Patents

Abstract

PURPOSE:To improve a load carrying capacity and safety by a method wherein linear grooves in a ball holder and the second linear grooves are formed such that differences in depth in a diametral direction are moved in sequence along the inclined surface and the connection surfaces of the outer cylinder. CONSTITUTION:An inner circumference of a circular holder 2 is formed to have a diameter d slightly larger than an operating shaft. A concave surface 17 at the outer circumference is formed in such a way as it may be fitted to the projected part 18 of the outer cylinder without any clearances therebetween, and also the linear grooves 22 and the second linear grooves 23 are formed such that a difference in depth in a diametral direction connects both grooves and it is moved in sequence along the inclined surface 7 of the outer cylinder 1 and the connected surface. Thus, it is possible to make an inclined angle 26 of the inclined surface 7 small, to enable the balls to be rolled smoothly, to increase an axial length of the projection 8 of the outer cylinder 1, shorten a circumferential space 27 and to increase the number of grooves 22 and 23, so that a load carrying capacity and a stability can be improved.

Description

[Detailed description of the invention] The present invention relates to a ball bearing for linear movement.

Ball bearings that support shafts that move in the axial direction are used in many machines and are already widely available on the market.

However, conventional ball bearings of the above type have many problems. In other words, (11) If the ball cage is made by press working from a thin steel plate, in order to fix the cage to the outer cylinder, both ends of the outer cylinder must be fixed from the inside by caulking, etc. This causes deformation, making it impossible to maintain precision, and in order to obtain caulking strength, the ring width must be increased. The load on

(2) If the inner convex portion of the outer cylinder is formed by press working, etc., the difference in diameter between the convex portion and the inner peripheral surface without the convex portion must be adjusted to allow smooth movement of the ball. ! Since it must be continuous only on the sloped surface extending in the direction of the line III, the inclination angle of the sloped surface must be made steep in order to form a predetermined length on the inner convex portion, which is the raceway surface. If the slope is steep, it will interfere with the smooth transfer movement of the ball.

(3) If an attempt is made to make the inclination angle of the inclined surface gentler in order to smooth the transfer motion of the ball, the orbit length will be significantly shortened due to the length of the outer cylinder, and the orbital radius of the ball will become larger, causing the ball to move outward. The number of ball rows installed on the inner side of the cylinder is reduced.

(4) When the ball holder is made from a thin steel plate by press working, there is a problem in that it is time-consuming to assemble the balls together with the outer cylinder, making it unsuitable for mass production.

Various proposals have been made to solve the above problems.

For example, in the ball bearing disclosed in Japanese Patent Publication No. 41-1244, a thick-walled pipe is used for the outer cylinder, and the inner unevenness is formed by broaching or slotting, and the ball retainer is integrally formed by deep drawing of a thin steel plate. However, the drawback is that it requires a large number of man-hours and advanced processing technology, and normal circular transfer cannot be realized. In addition, since the concentricity of the ball retainer with the outer cylinder is set at the initial stage of outer cylinder machining, it is affected by later hardening, grinding, etc., and the accuracy of the inner periphery of the outer cylinder is not guaranteed. There is a drawback that concentricity is unstable because the convex portion on the outer periphery of the cage is fitted into the concave portion.

The bushing disclosed in Japanese Patent Publication No. 44-2361 has a concave portion extending in the axial direction and having arcuate portions whose depth gradually increases and decreases in the radial direction at both ends at required locations on the inner periphery of the cylindrical outer tube; A convex portion extending in the remaining axial direction that forms the transfer surface of the ball is formed, and the cage is formed as a thick-walled cylindrical body by powder metallurgy or the like, and the cage is fitted into a recess on the inner periphery of the outer cylinder. The retainer has an outer circumferential shape that can be aligned with the outer cylinder and positioned in the circumferential direction, and metal rings are fitted to both ends of the outer cylinder to fix the positional relationship between the retainer and the outer cylinder. Similar to the prior art described above, this bushing has the drawbacks that the concentricity between the outer cylinder and the ball holder is unstable, and the positioning in the circumferential direction is also unstable.

Furthermore, in the ball bushing disclosed in JP-A-51-10246, the outside of the polygonal pipe is machined into a circular shape, the locking edges of the ball retainer are formed at both ends of the inner circumference, and the retainer is formed with the outside facing outward. It has the same shape as the inner cylinder polygon and is integrally molded from a highly elastic material, and is fixed to the outer cylinder by pressing the locking edges formed at both ends of the outer cylinder. In this pole bushing, the axial convex part on the inner circumference of the outer cylinder, which is the rolling surface of the balls, has a narrow width, and it is necessary to ensure the positional relationship between the outer cylinder and the retainer. Due to the unstable positioning in the circumferential direction, there is a misalignment between the length of the ball holder that holds the balls that contact the convex part and the actuating shaft at the same time and the convex part of the outer cylinder, which prevents the originally smooth transfer of the balls. The disadvantage is that it cannot be obtained.

It is an object of the present invention to correct the above-mentioned conventional drawbacks and to provide a high-performance, highly reliable ball bearing that can be easily mass-produced.

The details of the present invention will be explained based on embodiments shown in the drawings.

1 to 3, the ball bearing has an outer cylinder 1, a ball retainer 2, balls or steel balls 3, and a retaining ring 4. As shown in FIGS. The outer cylinder 1 has retaining ring grooves 5 near both ends of the outer periphery into which a retaining ring is inserted in order to prevent the bearing from moving when mounted on a mechanical device or the like.

As shown in FIGS. 4 and 5, convex portions 8 and four portions 9 extending in the axial direction are formed on the inner circumference of the outer cylinder 1 by broaching, slotting, etc., precision casting, sintering, etc. A groove 6 into which the retaining ring 4 is fitted is formed near both ends of the inner circumference.

Both parts of the convex part 8 in the axial direction are formed by the inclined surface 7 so that the end inner circumferential surface 1
0 smoothly. If the diameter of the surface of the convex part 8 is Dl, and the diameter of the deepest part of the concave part 9 is D2, the diameter D3 of the inner circumferential surface 10 of the end part is between the convex part 8 and the concave part 9, as shown by D3≦(D2 +01)/2. diameter.

The recess 9 has a connection surface 1 in the circumferential direction with the adjacent end inner circumferential surface 1o.
4 ties smoothly. The connecting surface 14 is formed as a curved surface having its center at a point 13 eccentric from the center 12 of the outer cylinder 1.

Both circumferential side surfaces of the convex portion 8 intersect with the inner circumferential surface at edge ridges 15 and 16. Radiation surface 18 passing through the center 12 of t11
．． 19.

As shown in FIGS. 6 and 7, the ball holder 2 has an inner periphery with a diameter d slightly larger than the operating shaft, and a concave surface 17 on the outer periphery has almost no gap ( The concave surface 17 of the ball holder 2 is formed so as to be fitted into the outer cylinder 1.
is disposed adjacent to both sides of a convex portion 20 having side surfaces formed in close contact with both side surfaces 18 and 19 of the convex portion 8, and when the convex portion 20 is attached to the outer cylinder 1, the convex portion 20 is attached to the concave portion of the outer cylinder 1. 9 so that there is a sufficient gap between them. Straight grooves 22 and 23 having a width slightly larger than the diameter of the steel balls 3 inserted into the recesses 17 and the projections 20 are formed on the outer peripheral surface of the ball holder 2.
is formed parallel to the axis. The straight groove 22 is formed so as to penetrate toward the inner periphery. The length of the straight groove 22 in the axial direction is formed to be the same length as the convex portion 8 of the outer cylinder 1. The inner peripheral end of the straight groove 22 transitions to an opening whose width is narrower than the width of the outer peripheral opening due to the curved surface 21 .

The second straight groove 23 parallel to the straight groove 22 is formed as a bag-shaped groove that does not open on the inner circumferential surface and is bored along an axis that is inclined with respect to the radial direction. The groove 22 and the second groove 23 have both ends connected to each other by an arcuate groove 25 .

An arcuate track 28 is formed on the inner surface of the outer cylinder 1, starting from the convex portion 8, passing through the inclined surface 7 and the connecting surface 14, the depth of which gradually changes, and reaching the concave portion 9. The track 28 smoothly connects both ends of a parallel straight path passing through the convex portion 8 and the concave portion 9 to form a circular trajectory.

The arcuate track 28 includes the inclined surface 7, the connecting surface 14, and the end inner peripheral surface 1.
It is formed as a circular arc with the intersection point 24 where 0 intersects as the apex.

The opening on the inner circumferential side of the arcuate groove 25 of the ball holder 2 is a straight groove 22
The width of the ball gradually narrows from the width of
formed in such a way that it migrates to the bottom of the

As shown in FIG. 8, the retaining ring 4 is formed as a wide ring punched out from a thin plate by press working.The retaining ring 4 is formed as a wide ring by punching out a thin plate by pressing.The retaining ring 4 is made by eliminating the shrinkage margin in advance when fitting into the groove 6 of the outer cylinder 1, and improving elasticity by hardening or nitriding. It's a carry-on.

With this device, the straight line of the ball holder: A22 and the second straight groove 23
Since the difference in depth in the diametrical direction connects both grooves and gradually transitions along the inclined surface 7 and the connecting surface 14 of the outer cylinder 1, the first portion along the inclined surface and the first portion along the connecting surface Since the depth changes in two steps with the second portion, the inclination angle 26 of the inclined surface 7 is smaller than that of the conventional one, and the ball can be smoothly transferred without having to run away at a steep angle. Therefore, the arcuate groove 25 provided in the ball holder 2 can be formed with the minimum radius that does not interfere with the smooth transfer of the balls, so the axis of the convex portion 8 of the outer cylinder 1, which becomes the perfect transfer surface that comes into contact with the operating shaft. The length in the direction can be increased by about 15 to 20% compared to the conventional one, and the load capacity as a bearing is improved.

Furthermore, the circumferential distance 27 between the contact points that contact the operating shaft and the contact points that do not contact the operating shaft can be shortened, and the contact groove 22 provided on the outer periphery of the ball holder 2. 23: It is possible to increase the number of 25, that is, the number of samples, which improves the load capacity and improves stability.

The center orbit of the ball rolling along the arcuate groove 25 of the ball holder 2 increases in depth from the convex portion 8 of the outer cylinder 1 along the inclined surface 7.
The tangent 11 between the inclined surface 7 and the inner surface 10 of the end portion passes through an intersection 24 at right angles to the tangent 29 between the connecting surface 14 and the inner surface 10 of the end portion, and the depth gradually increases along the connecting surface 14. The ball naturally rolls the smoothest.

The ball cage 2 is heat-treated to obtain the necessary hardness after machining, and then finished by polishing, lapping, etc., and has a convex portion 8 concentric with the outer circumferential surface 31 of the outer cylinder, and the cage 2.
Since the concave part 17 formed between the convex part 20 on the outer periphery of The curved surfaces 2 on both sides of the opening of the straight groove 22 to the inner periphery of the cage are narrowed to such an extent that the members do not come into contact with each other, so that the straight groove 22 comes into contact with the operating shaft.
The remaining portion 30 due to No. 1 is large (as a result, the strength of the cage is improved and the load capacity of the bearing is improved.

Since the concave portion 17 on the outer periphery of the ball holder 2 fits perfectly into the convex portion 8 of the outer cylinder 1, the ball holder and the outer cylinder are completely fixed in the circumferential direction, so that there is no contact with the operating shaft. Rolls smoothly without meandering or tilting with respect to the center in the axial direction.

According to the present invention, each member can be sufficiently mass-produced using conventional processing techniques, and since the retaining ring has a cutout for shrinkage on the outer periphery when fitting, assembly is easy and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a ball bearing according to the present invention, and FIG.
Figure 3 is a side view of Figure 1, Figure 4 is a cross-sectional view of the outer cylinder, Figure 5 is a side view of the outer cylinder, Figure 6 is a front view of the ball holder, FIG. 7 is a sectional view taken along the line -■ in FIG. 6, and FIG. 8 is a perspective view of the retaining ring. ■...Outer cylinder 2...Ball holder 3...Ball 4...Retaining ring 7...Slanted surface
8... Convex portion 9... Concave portion 10...
・End inner peripheral surface 12... Outer cylinder center 13... Eccentric point 11-

Claims (1)

[Claims] In a ball bearing for a linear movement shaft, which has an outer cylinder, a ball holder attached to the outer cylinder, steel balls, and a retaining ring for fixing the ball holder to the outer cylinder, Convex portions and concave portions extending in the axial direction are formed alternately in the circumferential direction, and both ends of the convex portion in the axial direction are smoothly connected to inner circumferential surfaces of both ends having a diameter intermediate between the convex portion and the concave portion by inclined surfaces, The inner circumferential surfaces at both ends and the concave portion adjacent in the circumferential direction are smoothly connected by an arcuate surface centered at a point eccentric from the center of the outer cylinder, and both side surfaces of the convex portion are formed as surfaces substantially perpendicular to the convex surface. The trajectory of the ball row is formed by the parallel linear trajectory on the convex surface and the concave surface, and the arc-shaped trajectory with the apex at the intersection of the slope at about f, the inner surface of the end, and the connection surface, and An uneven surface is formed on the outer periphery of the cage to fit into the convex part and the recessed part of the outer cylinder, and a linear groove penetrating the inner circumference is formed on the concave surface of the outer periphery of the spherical cage, and a non-penetrating groove parallel to the straight groove is formed on the convex part. Two straight grooves are formed, both ends of the drawing line groove are connected by an arcuate groove, and the arcuate groove is arranged so as to correspond to the arcuate ball array trajectory of the outer cylinder. ball bearing.