Bearings – Linear bearing – Recirculating
Patent
1985-11-13
1986-12-30
Levy, Stuart S.
Bearings
Linear bearing
Recirculating
384 45, F16C 3106
Patent
active
046325735
DESCRIPTION:
BRIEF SUMMARY
FIELD OF ART
The present invention relates to a linear motion ball bearing used for guiding portions which perform a linear motion such as a machine tool table, a positioning table, etc.
BACKGROUND ART
According to a conventional linear motion ball bearing of this type, generally a ball return hole is formed axially in a bearing body to let balls circulate in an axial direction, and a machining for curved surface is performed to connect end portions of the return hole and a loaded ball groove formed in the bearing body, and further a return cap having a ball turning groove for changing the direction of ball by 180.degree. is applied to each end portion. Besides, in order to prevent balls from falling off when the bearing body is pulled out from a rail base, it is necessary to provide a ball retainer separately.
It has been proposed to use a side face of a bearing body as part of a ball return hole in place of forming a ball return hole axially in the bearing body, as disclosed in Japanese Patent Laid-Open Publication No. 58225/84. Even in this proposed construction, however, it is still necessary that each end portion of the ball return hole and a loaded ball groove formed in the bearing body be covered with a return cap having a ball turning groove. Besides, a separate provision of a ball retainer is also required as before.
Thus, these conventional techniques are disadvantageous in that the number of parts increases and troublesome machinings are required.
DISCLOSURE OF THE INVENTION
The present invention is characterized by upper and lower members each having opposed C-shaped grooves and an intermediate member having upper and lower opposed grooves including C-shaped portions cooperating with the grooves in the upper and lower members to provide C-shaped ball circulation paths, and connecting portions of approximately quarter-circular cross section, for connecting end portions of the C-shaped grooves. The upper, lower and intermediate members are fitted laminatedly on a leg portion of a bearing body which has loaded ball grooves formed therein.
The thus laminatedly fitted upper, lower and intermediate members form an endless ball circulation path conjointly with the loaded ball grooves formed in the leg portion of the bearing body. Consequently, it it not necessary to form a ball return hole in the bearing body, nor is it necessary to perform a curved surface machining for changing the direction of ball. Further, it is not necessary to separately provide a return cap for changing the direction of ball at each bearing end portion.
Besides, the grooves formed in the intermediate member for connecting end portions of the C-shaped grooves fulfill the function as a ball retainer which holds balls between it and the loaded ball grooves formed in the bearing body, thus preventing balls from falling off even when the bearing body is pulled out from a rail base.
Consequently, not only the number of parts is reduced but also it becomes no longer necessary to form a ball return hole in the bearing body or perform a machining for curved surface at the ball inlet/outlet portion, and hence the manufacturing cost is reduced.
Further, by forming the ball direction changing portion in the shape of an ideal arc of a large diameter, the resistance of ball against direction changing is greatly reduced. In addition, by applying a resin coating into the grooves of the upper, lower and intermediate members, it is made possible to render the balls easier to slip and reduce noise.
Also in the manufacturing process, the assembly becomes extremely easy, and it is possible to fabricate the upper, lower and intermediate members according to a precision casting or forging, or by plastics. Also from this point it is possible to reduce the manufacturing cost.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 to 3 are top, front and side views, respectively, showing upper and lower members and an intermediate member as assembled with respect to a bearing body,
FIGS. 4 and 5 are top and side views, respectively, of the upper and lower
REFERENCES:
patent: 3304133 (1967-02-01), Strassberg
patent: 3467447 (1969-09-01), Newman
patent: 3758176 (1973-09-01), Stapley
patent: 3845993 (1974-11-01), Schiler
patent: 4547025 (1985-10-01), Isert
Hannon Thomas R.
Levy Stuart S.
Tsubakimoto Precision Products Co. Ltd.
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