JPH05321932A - Hollow track base for direct-acting bearing - Google Patents

Abstract

PURPOSE:To smoothly run direct-acting bearings on a pair of track bases witch are only a little out of parallelism by composing the long track bases for slidably supporting bearing main bodies through a number of balls of hollow structure cylindrical bodies which are thin to deform within the elastic limit to absorb a parallelism error. CONSTITUTION:Two bearing main bodies 5 are mounted on each of a pair of direct-acting bearing hollow track bases 1 to slide freely through a number of balls 6, and the bearing main bodies 5 are fixed to a lower surface of a table 7. The track bases 1 are installed on an installation surface 2 almost in parallel, and a differential gap in order of micron is referred to as X. When the table 7 is moved, the bearing main body mounted on the base 1 applies a transverse load on the track base 1. The track base 1 is thus deflected transfersely to absorb the differential gap X in order of micron. The bearing main body 6 can thus run smoothly on the track base 1 without receiving large effects. As the table 7 passes, the track base returns to an original position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow raceway for linear motion bearings, and more particularly to a hollow raceway for linear motion bearings suitable for being installed in parallel with two mounting surfaces.

[0002]

2. Description of the Related Art Since a linear motion bearing uses a rolling guide, it is possible to greatly reduce frictional resistance as compared with a conventional sliding guide device using a sliding guide.
Further, by applying a preload, it can be used with high precision and high rigidity. For these reasons,
Linear motion bearings have been used for various purposes in recent years.

A typical method of using such a linear motion bearing is as follows. First, a pair of rail bearing rails are installed substantially parallel to the mounting surface. On each track, one or a plurality of saddle-shaped bearing bodies are mounted via a large number of balls. These bearing bodies are fixed to a moving object such as a table. The object to be linearly reciprocated is mounted on this moving object.

[0004]

As described above, the distance between the saddle-shaped bearing bodies fitted to the linear motion bearing raceways fixed to the moving object such as the table is the same as those of the moving object such as the table. It is fixed because it is fixed at. Therefore, in order for the moving object such as the table to smoothly reciprocate, the distance between the pair of linear motion bearing bearings must be constant over the entire stroke range.

However, the parallelism of the pair of bearings for linear motion bearings is impaired for various reasons. For example, even if the accuracy of the mounting surface itself is poor, the mounting bolts are tightened irregularly, or the tightening order is bad, a deviation in units of microns occurs. If the rail bearings for linear motion bearings are not precisely parallel, the linear motion bearings will not move smoothly,
The motion accuracy of the moving object is impaired.

[0006]

SUMMARY OF THE INVENTION The present invention is based on the background of the above-mentioned prior art and solves its drawbacks, that is, even if a pair of rails themselves are not parallel in a precise sense,
It is an object of the present invention to provide a hollow raceway for a linear motion bearing in which the motion of the linear motion bearing can be made smooth.

According to the present invention, a plurality of rolling grooves formed in the axial direction are provided on the outer peripheral surface, and a saddle-shaped bearing main body is rotatably supported by a large number of balls running along the rolling grooves. A long hollow bearing for linear motion bearings, characterized by comprising a hollow cylindrical body that is thin enough to deform within the elastic limit and absorb two-row parallel error. To

[0008]

The hollow bearing for linear motion bearings of the present invention is, of course,
The saddle-shaped bearing body has a rigidity enough to withstand a load, a moment, or an impact applied via a plurality of balls. Since the hollow bearing for linear motion bearings of the present invention is a tubular body having a thin hollow structure, it can be bent in the horizontal direction while maintaining a predetermined rigidity. Therefore,
When the paired bearing bodies move along the hollow bearing for linear motion bearings, the deviation of parallelism in micron units is absorbed by the deformation within the elastic limit.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The hollow raceway for linear motion bearings of the present invention will be described in detail below with reference to the drawings.

As shown in FIGS. 1 and 2, a pair of linear bearing hollow raceways 1, 1 are installed on a mounting surface 2 in substantially parallel with a bolt 3 and a taper give 4. Several methods have been proposed as methods for installing the pair of hollow bearings 1 for linear motion bearings 1, 1 substantially parallel to the mounting surface 2. For example, there are a straight edge method, a table running method, a method of copying the hollow bearing base 1 for linear motion bearing on the reference side, and a method using a jig. Hollow way for each linear motion bearing 1
Each of the two bearing bodies 5 and 5 is mounted on each of them via a large number of balls 6 so as to be freely slidable. A total of four bearing bodies 5 can be mounted on the table 7 using suitable means.
Fixed on the underside of.

The hollow raceway 1 for linear motion bearings of the present invention is shown in FIG.
As best shown in FIG. 1, it is composed of a hollow cylindrical body. The tubular body is of unitary construction in the preferred embodiment shown and has a longitudinally long rectangular cross section. Therefore, for example, when the linear bearing hollow raceway 1 receives an external force in the lateral direction, it deforms within its elastic limit as depicted by the chain double-dashed line. Then, when the external force disappears, it returns to the original position drawn by the solid line. On the other hand, when the linear bearing hollow raceway 1 receives an external force in the vertical direction, this external force is supported by the mounting surface 2 via the thin wall portion. Since the hollow cylindrical body has a structure with extremely high rigidity with respect to the cross-sectional area, it can be made into a considerably thin cylindrical body while maintaining desired rigidity.

A cooling medium such as cooling water or a coolant can be directly inserted into the hollow portion of the direct bearing hollow raceway 1 or a heat pipe can be inserted. As a result, it is possible to avoid the deformation of the linear bearing hollow raceway 1 due to the temperature change.

Each of the linear bearing hollow raceways 1 also has four rows of rolling grooves 8 on the outer peripheral surface thereof, two rows on one side surface. The surface of each rolling groove 8 is subjected to surface treatment such as induction hardening, carburizing and hardening.

Referring to FIG. 1, a pair of linear bearing hollow raceways 1, 1 are installed substantially parallel to a mounting surface 2. Let X be the difference in micron-order spacing between the pair of linear bearing hollow raceways 1, 1. When the table 7 moves in the direction of the arrow, the bearing bodies 5 and 5 mounted on the linear motion bearing hollow raceways 1 apply a lateral load to the linear motion bearing hollow raceways 1. As a result, the hollow raceway for each linear motion bearing 1
2 bends in the lateral direction as shown in FIG. 2 to absorb the difference X in the micron-order interval. Therefore, the bearing bodies 5, 5
Can smoothly travel on the linear bearing hollow raceways 1, 1 without being greatly affected. Table 7
After passing, the linear bearing hollow raceways 1, 1 return to their original positions and wait for the next passage of the table 7.

3 and 4 show another embodiment of the hollow bearing for linear motion bearings according to the present invention. As shown in the drawings, in these embodiments, the hollow bearings of the linear motion bearings have a hollow section and a cross section having an oval shape, respectively.

[0016]

As described above, the hollow bearing for linear motion bearings of the present invention has a hollow cylindrical body which is thin enough to deform within the elastic limit and absorb a two-row parallel error. With this configuration, it is possible to bend in the horizontal direction while maintaining a predetermined rigidity. Therefore, when the pair of bearing bodies move along the linear bearing hollow raceway, the deviation of the parallelism in the unit of micron is absorbed by the deformation within the elastic limit. As a result, the bearing body can travel smoothly over the entire stroke of the hollow bearing for linear motion bearing.

[Brief description of drawings]

FIG. 1 is a plan view of an installed state of a typical linear motion bearing.

FIG. 2 is a cross-sectional view of a linear motion bearing including an embodiment of a hollow bearing for linear motion bearings according to the present invention, and the right side of the bearing body is omitted for the sake of clarity.

FIG. 3 is a cross-sectional view of another embodiment of the hollow bearing for linear motion bearing according to the present invention.

FIG. 4 is a cross-sectional view of still another embodiment of a hollow bearing for linear motion bearing according to the present invention.

[Explanation of symbols]

 1 Hollow rail for linear motion bearing 2 Mounting surface 3 Bolt 4 Taper give 5 Bearing body 6 Ball 7 Table 8 Rolling groove

Claims (4)

[Claims] 1. A saddle-shaped bearing main body is rotatably supported by a plurality of rolling grooves formed in an axial direction on an outer peripheral surface and a large number of balls running along the rolling grooves. A long linear bearing hollow raceway, which is characterized by comprising a hollow cylindrical body that is thin enough to deform within the elastic limit and absorb two-row parallel error. Hollow bearing for linear motion bearings. 2. The hollow bearing for linear motion bearings according to claim 1, further comprising a structure for directly passing a cooling medium through the hollow portion. 3. The hollow bearing for linear motion bearing according to claim 1, wherein a heat pipe is inserted into the hollow portion. 4. The hollow bearing for linear motion bearing according to claim 1, wherein the cross section of the cylindrical body is basically a vertically long rectangle.