JP2808785B2 - Linear motion rolling guide device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion rolling guide device used for a feed table device or the like that supports a moving table so as to be able to linearly move with respect to a bed.

[Conventional technology]

As shown in FIGS. 3 and 4, one guide rail 1 is fixed to the bed 2 and the other guide rail 3 is fixed to the moving table 4 side. A linear motion rolling guide device is known in which the movable table 4 is smoothly linearly moved relative to the bed 2 via the two guide rails 1 and 3 by the rolling of the roller 5 interposed therebetween. The rollers 5 are held between the guide rails 1 and 3 by a holder 6. The rollers 5 in FIGS. 3 and 4 are of a cross-roller type in which adjacent axes intersect at an angle of 90 degrees, but linear rollers in which the axes of the rollers are parallel are also available. It is known.

[Problems to be solved by the invention]

However, between the guide rails 1, 2 and the roller 5,
Since it is not constrained in the longitudinal direction of the guide rails 1, 3,
Due to the reciprocating movement of the moving table 4, the relative positions of the rails 1 and 3 and the cage 6 slightly shift, and finally the cage 6
Occurs from the rails 1 and 3 (microslip phenomenon). Therefore, for the purpose of preventing the microslip phenomenon, rack teeth are formed on the guide rails 1 and 3 and teeth such as pinions are formed on the outer periphery of the roller 5 so that the two mesh with each other. Means for correcting the movement of the above are well known, but these have the problems that they complicate the structure, increase the cost, and over-constrain each part.

The present inventors have conducted various experiments and analyzes to determine the cause of the microslip phenomenon, and as a result, the cause of the phenomenon is a slip between the roller and the two guide rails that are in rolling contact with the roller. I found that.

Therefore, the present invention, based on the above findings, prevents the structure from becoming complicated and costly without adding extra members, and without causing a large-scale change in the structure of each member, the microslip The purpose is to prevent.

[Means for solving the problem]

In the linear motion rolling guide device according to the present invention, the circumferential surface roughness of the outer peripheral surface of the roller is made substantially equal to or slightly larger than the axial surface roughness of the outer peripheral surface.

In particular, the circumferential surface roughness of the outer peripheral surface of the roller,
It is preferable that the center line average roughness is 0.05 to 0.10 μm.

[Action]

By the way, when the roller and the retainer held between the guide rails move, the external load and the preload become uneven due to gravity, inertia, etc., and micro slip occurs due to the resistance difference based on this. Since the rail and the roller are in contact with each other, a force for suppressing the micro-slip is also exerted between the rail and the roller due to the frictional force. FIG. 1 schematically shows this suppressing force,
For convenience of explanation, the roller 5 is modeled and shown in a pinion shape, and the guide rails 1 and 3 are similarly shown in a rack shape.

In the first place, the microslip occurs when the relative movement amounts of the roller 5 and the guide rails 1 and 3 at the time of forward and backward reciprocation are different. Such a phenomenon can be prevented if the roller 5 performs only a predetermined rolling motion and no slippage occurs between the roller 5 and the guide rails 1 and 3. Therefore,
As shown in FIG. 1, if the contact portions between the roller 5 and the guide rails 1 and 3 are engaged, no relative slip occurs. If the sliding frictional force at the contact portion between the roller 5 and the guide rails 1 and 3 is increased as described above, the frictional force becomes a micro-slip suppressing force.

However, as a linear motion rolling guide device, in addition to increasing the frictional force between the roller 5 and the guide rails 1, 3, the radial load of the roller 5 must be supported between the two, and furthermore, the rolling must be performed. As shown in FIG. 1, the teeth cannot be engaged between the roller 5 and the guide rails 1 and 3 because the smoothness of the guide must be ensured.

Thus, the present invention increases the frictional force against the rolling of the roller by making the circumferential surface roughness on the outer peripheral surface of the roller substantially equal to or slightly larger than the axial surface roughness on the outer peripheral surface. At the same time, the support of the radial load and the smoothness of the rolling guide were ensured.

Furthermore, by making the surface roughness in the circumferential direction on the outer peripheral surface of the roller 0.05 to 0.10 μm in the center line average roughness, the sliding friction force at the contact point between the roller and the guide rail is maximized, Straightness as a rolling guide device can be secured.

〔Example〕

The roller 5 shown in FIG. 3 is used in a cross-roller type or linear roller type linear rolling guide device described in the section of the prior art, which is surface-treated by tumbling. The center line average roughness in the circumferential direction and the axial direction is uniform at about 0.07 μm.

In contrast, the conventional roller surface has an axial centerline average roughness of about 0.06 μm and a circumferential centerline average roughness of about 1/3 of 0.02 μm. In other words, according to the conventional roller surface processing method, the circumferential surface roughness is inevitably reduced to about 1/3 of the axial surface roughness by grinding and superfinishing in addition thereto. Have been. This can be presumed to be caused by performing the processing while rotating the roller in the circumferential direction.

As described above, the micro-slip suppressing force is controlled by the roller 5.
The circumferential sliding friction of the surface is relevant. However, the conventional roller has an extremely small center line average roughness in the circumferential direction with respect to the center line average roughness in the axial direction. The function of the roller 5 of this embodiment is more excellent.

By the way, the surface roughness in the axial direction hardly affects the suppressing force of the microslip, but when the surface roughness in the axial direction is large, the contact state between the roller 5 and the guide rails 1 and 3 becomes uneven,
The preload applied to the roller 5 is likely to be uneven or skewed, which causes micro-slip. For this reason, the surface roughness in the axial direction cannot be significantly increased. From these conditions, it is desirable that the surface roughness of the roller 5 does not greatly differ between the axial direction and the circumferential direction.

Further, when the surface roughness is excessively large in both the axial direction and the circumferential direction, the microslip suppressing force is improved, but the contact state between the roller 5 and the guide rails 1 and 3 is not uniform as described above. On the contrary, micro-slip is promoted, and performance such as straightness of the forward / backward trajectory and durability are lowered. Therefore, it is not suitable as a linear motion rolling guide device.

As a result of experiments and research, the inventors set the surface roughness in the circumferential direction on the outer peripheral surface of the roller to 0.05 to 0.10 μm in the center line average roughness as described above, while reducing this surface roughness. By making the surface roughness substantially equal to or slightly larger than the axial surface roughness of the outer peripheral surface, it is possible to completely suppress micro-slip in a normal use range without deteriorating performance such as the straightness and durability. Successful.

By the way, in the linear motion rolling guide device using the conventional roller, microslip occurred at a rate of 70%. However, when the roller 5 of this embodiment was used, no microslip occurred. Even before and after the surface roughness value,
Circumferential surface roughness is 0.05 to 0.10 in center line average roughness
If it was μm, microslip did not occur.

[Effects of the Invention] As described above, according to the present invention, by specifying the surface roughness of the roller, micro-slip can be suppressed without adding a special mechanism. In addition, roller surface processing simply adds a simple processing step such as tumbling to the conventional surface processing, which can reduce the cost and, as a result, compared to the case where a special mechanism is added. A linear motion rolling guide device can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic view for explaining a micro-slip suppressing force, FIG. 2 is a perspective view showing a roller of the present invention, FIG. 3 is a perspective view showing a relationship between the roller and a guide rail, and FIG. It is sectional drawing of a rolling guide apparatus. 1,3 ... guide rail, 5 ... roller.

Claims (2)

(57) [Claims] 1. A linear motion rolling guide device comprising two parallel guide rails relatively moving in an axial direction and a roller rolling between the two guide rails, wherein a circumferential direction of an outer peripheral surface of the roller is provided. A linear motion rolling guide device characterized in that the surface roughness is substantially equal to or slightly larger than the surface roughness in the axial direction of the outer peripheral surface. 2. The linear motion rolling guide device according to claim 1, wherein the surface roughness of the outer circumferential surface of the roller in the circumferential direction is 0.05 to 0.10 μm in center line average roughness.