Tubular bearing for linear motion

Bearings – Linear bearing – Recirculating

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Details

384 43, F16C 2906

Patent

active

046627634

DESCRIPTION:

BRIEF SUMMARY
FIELD OF ART

The present invention relates to a bearing for linear motion used for guiding portions which perform a linear motion such as a machine tool table and a positioning table.


BACKGROUND ART

As shown in Japanese Patent Publication No. 38812/82, etc., conventional linear motion bearings of this type are of a construction in which a bearing body is machined to form a ball return hole in its axial direction so that balls may circulate in the axial direction, end portions of the return hole being curved to let the balls change their direction, and both outside end portions thereof are covered with return caps each formed with a direction changing groove for effecting a 180.degree. direction change.
Such construction is disadvantageous in that the number of parts increases and troublesome machinings are required.


DISCLOSURE OF THE INVENTION

The present invention is characterized in that a ball circulation path is formed using a two-part split tube of opposed J shape, whereby the insertion of balls is effected easily and the ball circulation mechanism is simplified remarkably. Moreover, return caps which have heretofore been required become unnecessary, and a secondary machining such as slitting to the bearing body also becomes unnecessary. Additionally, the necessity of curving ball inlet and outlet portions of the bearing body is eliminated.
Besides, since pressed projections and portions contiguous thereto can be inserted up to the inner part of a rail base groove, not only the ball scooping action becomes smoother, but also by forming a ball direction changing part in an ideal arcuate shape, the resistance of ball to direction changing is decreased to a remarkable extent. Further, by applying a resin coating to the tube interior, balls become easier to slide.
The present invention is also characterized in that a two-part split tube of opposed U shape having a belt-like connection and a two-part split tube of opposed J shape are combined to form a ball circulation path, whereby it becomes unnecessary to use a ball retainer.
The present invention further provides a tube mounting cover having a tube fitting groove formed in its inner surface. By putting this cover on end faces of the bearing body and, if necessary, also on side faces thereof, not only the positioning of tube can be done easily, but also the tube protection and the noisereducing effect can be attained. Moreover, it is possible to produce a bearing having a planar appearance not different from conventional ball bearings for linear motion despite using a tube.
Further, in the above mounting cover, by integrally forming a side cover and an end face cover and putting a pair of such covers on both end faces of the bearing body, the positioning of tube can be done easily and the tube holding space can be reduced.
Besides, it becomes unnecessary to machine bolt holes in the bearing body for the mounting of cover, and the total number of parts can be decreased.
Lastly, in the present invention a lubricant feed port is formed in part of the inner peripheral wall of tube so that lubricant can be fed easily into the tube.


BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate embodiments of the present invention, in which
FIG. 1 is a longitudinal sectional view of a first embodiment, with a lower half portion thereof omitted;
FIG. 2 is a sectional view in the direction of line II--II of FIG. 1;
FIG. 3 is partial perspective view of the first embodiment;
FIG. 4 is a view corresponding to FIG. 1, illustrating a second embodiment;
FIG. 5 is a sectional view in the direction of line V--V of FIG. 4;
FIG. 6 is a partial perspective view of the second embodiment;
FIGS. 7 and 8 are sectional views corresponding to FIGS. 1 and 4, respectively, illustrating module type embodiments;
FIG. 9 is a longitudinal sectional view of a ball retainer integral type embodiment, with a lower half portion omitted;
FIG. 10 is a sectional view in the direction of line X--X of FIG. 9;
FIG. 11 is a partial perspective view of this embodiment;
FIG. 12 is a view cor

REFERENCES:
patent: 253679 (1882-02-01), Bussing
patent: 750771 (1904-01-01), Keil
patent: 1185114 (1916-05-01), McIlwain
patent: 2672379 (1954-03-01), McVey
patent: 3044835 (1962-07-01), Hurd
patent: 3304133 (1967-02-01), Strassberg
patent: 4095854 (1978-06-01), Teramachi
patent: 4417771 (1983-11-01), Teramachi
patent: 4547024 (1985-10-01), Teramachi

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