JP2000352420A - Linear bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten a withstand load when a moment load is applied and reduce the generation of backlash by accommodating a pair of slide bearings with a linear ball bearing interposed between them at both ends in a housing, and setting the inside diameter of each slide bearing larger than the outline of a shaft inserted in the bearing. SOLUTION: Linear ball bearings 10, 10 and slide bearings 20, 20 are disposed such that a pair of linear ball bearings are interposed between a pair of slide bearings, and with an oiling member 30 interposed between the linear ball bearings, they are inserted in a housing 1. The oiling member 30 disposed between the respective linear ball bearings 10, 10 is shaped like a ring which can be inserted in the housing 1, and provided with an annular oil groove 32 disposed in the outer periphery, and with an annular oil groove 31 surrounding the outer periphery of the shaft of the bearing, both grooves being communicated with each other by an oil hole 33. The inside diameter of each slide bearing 20, 20 is set larger than the outside diameter of the shaft inserted in the bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear bearing used for a linear guide in various machine tools, industrial machines, and the like, and more particularly, to an improved linear ball bearing.

[0002]

2. Description of the Related Art Conventionally, a linear ball bearing in which a ball is in rolling contact with a shaft has been favorably used as a linear bearing because of its small static and dynamic friction coefficients. Here, a linear ball bearing is a structure in which a plurality of balls to be moved in the axial direction are accommodated in a freely circulating manner, and a cylindrical retainer exposed from an inner ball exposure hole is inserted into an outer cylinder. The bearing moves linearly through the rolling of the ball with respect to the shaft inserted into the bearing.

[0003]

Usually, a linear ball bearing is accommodated in a housing for mounting a member to be linearly guided with respect to a shaft and used for use. However, depending on circumstances of a machine to be used, it is required. In some cases, the length of the housing becomes longer. In this case, the linear ball bearing mechanism using only rolling contact has a problem in that the rolling contact area is extremely small, so that the load resistance when a moment load is applied is weak, rattling is likely to occur, and the absorbing power against shock and vibration is small. was there.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and accommodates a plurality of balls to be moved in the axial direction in a freely circulating manner.
A linear ball bearing, in which a cylindrical cage exposed from an inner ball exposure hole is inserted in an outer cylinder, is housed in a housing, and a pair of sliding bearings are sandwiched between both ends in the housing with the linear ball bearing interposed therebetween. The sliding bearing is housed and the inner diameter of the sliding bearing is set to be larger than the outer diameter of the shaft inserted into the bearing.

[0005]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a view showing an example of the linear bearing of the present invention. The greatest feature of the present invention is that the linear bearing is a composite of a linear ball bearing and a sliding bearing. Here, a long linear bearing having two linear ball bearings connected on an axis is taken as an example. .

Reference numeral 10 in the figure denotes a linear ball bearing. This linear ball bearing has a conventionally known structure in which a retainer 12 for accommodating a ball B is inserted into an outer cylinder 11. That is, a cylindrical retainer 12 having a plurality of endless groove-shaped ball circulation paths 13 including a ball exposure hole 14 opened to the inner periphery in the shape of a long hole in the axial direction is provided on the ball circulation path with a plurality of balls B is accommodated in the outer cylinder 11 and inserted and fixed in the outer cylinder 11, thereby adopting a structure in which the ball circulates infinitely in a ball circulation path covered by the inner peripheral wall surface of the outer cylinder. In this case, in order to prevent the inserted retainer 12 from dropping from the outer cylinder 11, it is necessary to hold both ends of the retainer with a ring-shaped end member fitted on the inner periphery of the outer cylinder. Become. However, in this embodiment, one end of the retainer abuts on a ring-shaped end member 16 whose outer peripheral end is fitted into a fitting groove 17 formed in an annular shape on the inner periphery of the outer cylinder. The outer peripheral end is brought into contact with the ring-shaped seal member 40 which is fitted into the fitting groove 18 engraved annularly on the inner periphery, and this also serves as an end member. Details of the seal member 40 will be described later.

In the figure, reference numeral 20 denotes a sliding bearing, one of which is provided at each of the inner peripheral ends of the housing 1. The sliding bearing 20 employs an oil-containing sliding bearing in this embodiment, and is formed in a tubular shape that can be inserted into the housing 1 (see FIG. 6).

The above linear ball bearings 10, 10
The slide bearings 20, 20 are inserted into the housing 1 with a pair of linear ball bearings sandwiched between a pair of slide bearings and an oil supply member 30 described below sandwiched between the linear ball bearings. The ends of the respective members are brought into contact with each other, and the outer peripheral end is fitted into a fitting groove 3 which is annularly engraved on the inner periphery of the housing at the end on the housing opening side of each slide bearing to prevent the sliding bearing from falling off. The ring-shaped housing end member 2 to be contacted.

An oil supply member 30 disposed between the linear ball bearings 10, 10 is formed in a ring shape which can be inserted into the housing 1, and has an annular oil groove 32 on the outer periphery and a bearing shaft on the inner periphery. An annular oil groove 31 surrounding the outer periphery of S is provided, and both are connected by an oil hole 33 (see FIG. 7). On the other hand, a lubrication hole 4 penetrates from the outer periphery of the housing toward an oil groove 32 on the outer periphery of the lubrication member at a location where the lubrication member 30 is inserted in the housing 1, and lubrication from a grease pump or the like is provided in an opening of the lubrication hole. A nipple 5 is provided for opening a ball valve (not shown) by pressure.

In this embodiment, each sliding bearing 2
Seal members 40, 40 are arranged on both sides of 0, 20 (see FIG. 6). The seal member 40 is made of an elastic material such as plastic, and is formed into a ring shape in which the inner peripheral end 41 slides on the outer periphery of the shaft S. Here, the inner peripheral end is narrowed down into a skirt shape. The inner peripheral end is configured to contact the outer periphery of the shaft with a biasing force. The seal member 40 on the outer side (opening side of the housing) of the slide bearing 20 is provided by fitting an outer peripheral end thereof into a fitting groove 21 formed in an annular shape on the inner periphery of the slide bearing, and an inner (opposite side) seal is provided. The member is a sliding bearing 2 as described above.
The end member is provided at the inner peripheral end of the linear ball bearing 10 which comes into contact with the bearing.

In the above construction, the sliding bearings 20, 2
The inside diameter of 0 is set to be larger than the outside diameter of the shaft S inserted into the bearing (see FIG. 5, which is exaggerated in the drawing). That is, in a normal state, the bearing is guided by rolling contact between the shaft S and the ball B of the linear ball bearings 10, 10. Then, a moment load acts on the bearing due to some external force, and the sliding bearings 20 and 20 come into contact with the shaft S at a stage where the bearing is bent, so that the rolling contact and the sliding contact are used together. Therefore, the degree of the size of the inner diameter of the sliding bearings 20, 20 with respect to the outer diameter of the shaft S is determined by the possibility of this bending, but the value is in any case small.

[0012]

The linear bearing of the present invention having the above configuration has the following specific effects. Because the rolling contact area is combined with a slide bearing with a large contact area against a linear ball bearing with an extremely small contact area,
A linear bearing that has high load resistance when a moment load is applied, hardly causes backlash, and has a large absorbing power against impact and vibration. In the above case, the inner diameter of the sliding bearing is set to be larger than the outer diameter of the shaft inserted into the bearing, so the bearing is guided only by linear ball bearings with a small static and dynamic friction coefficient unless an excessive moment load is applied. Therefore, the running resistance does not increase with respect to the conventional linear bearing. Since an annular oil groove surrounding the outer circumference of the shaft is provided between the linear ball bearings, the linear ball bearing and the slide bearing are always supplied with oil via the shaft. Since a ring-shaped seal member is provided at both ends of each slide bearing, the inner peripheral edge of which is in sliding contact with the outer periphery of the shaft, the inner seal member prevents wear powder from entering the linear ball bearing due to sliding wear. The outer sealing member achieves a double shielding effect that prevents external dust from entering the bearing.

[Brief description of the drawings]

FIG. 1 is a sectional view of a linear bearing according to the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a plan view of the retainer.

FIG. 4 is a sectional view of the same.

FIG. 5 is an enlarged sectional view of a main part of the above.

FIG. 6 is a perspective view of a seal member and a slide bearing according to the first embodiment;

FIG. 7 is a perspective view of the oil supply member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 10 Linear ball bearing 11 Outer cylinder 12 Cage 20 Sliding bearing

Claims (4)

[Claims] 1. A linear ball bearing having a plurality of balls to be moved in an axial direction circulatingly accommodated therein and a cylindrical retainer exposed from an inner peripheral ball exposing hole inserted in an outer cylinder. It is housed in a housing, and a pair of slide bearings are housed at both ends in the housing with a linear ball bearing interposed, and the inner diameter of this slide bearing is set larger than the outer diameter of the shaft inserted into the bearing. And linear bearing. 2. The linear bearing according to claim 1, wherein ring-shaped seal members whose inner peripheral ends are in sliding contact with the outer periphery of the shaft are arranged on both sides of each slide bearing. 3. The linear bearing according to claim 1, wherein the slide bearing is an oil-impregnated slide bearing. 4. A plurality of linear ball bearings are connected to each other on an axis, and an annular oil groove surrounding the outer circumference of the shaft is arranged between the linear ball bearings. The linear bearing according to any one of claims 1 to 3, which supplies: