Bearings – Linear bearing – Recirculating
Reexamination Certificate
2001-09-14
2003-02-18
Footland, Lenard A. (Department: 3682)
Bearings
Linear bearing
Recirculating
Reexamination Certificate
active
06520681
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a linear motion guide unit adapted for use in various types of machinery such as diverse industrial robots, semiconductor manufacturing machines, machine tools, and so on.
2. Description of the Prior Art
Most linear motion guide units used extensively in diverse fields of machinery such as various industrial robots, semiconductor manufacturing apparatus, precision machines, machine tools, and so on are in general comprised of a track rail and a slider, which fits over and conforms to the track rail for sliding movement. The slider is chiefly composed of a carriage and end caps. In most sliders ever used, the carriage is usually jointed together with the end caps by tightening machine screws and so on. Among the more recent advances in sliders, on the other hand, is known a slider in which the components: carriage and end caps are joined together in a fitting relation with no use of any fastener.
A linear motion guide arrangement is disclosed in, for example Japanese Patent No. 2936116, in which the snap connection means are used to secure the carriage member and the reversing bodies to the guide carriage housing. Thus, there is disclosed a construction in which no fixing screw is used for jointing together components and parts. In detail, the reversing bodies are secured to the fore-and-aft ends of the carriage, one to each end, with the projections of the reversing bodies coming into engagement with the grooves on the upper side of the carriage. The combination of the carriage and reversing bodies is accommodated in the guide carriage housing with the fore-and-aft outside end faces being covered with the guide carriage housing and held in position by the snap connection means. With the linear motion guide arrangement recited earlier, moreover, there is provided a recirculating-ball circuit including a return guide raceway formed in the carriage and curved ball guides formed in the reversing bodies, one to each body. Engagement of the grooves on the upper side of the carriage with the projections of the reversing bodies serves to bring the curved ball guides into alignment with the return guide raceway, thereby establishing the recirculating-ball circuit. In addition, the sealing plates are applied to the end surfaces of the end plates of the guide carriage housing and locked by snapping any locking nose of the sealing plates into the associated locking recess in the end plates of the guide carriage housing.
Disclosed in Japanese Utility Model Laid-Open No. 133122/1986 is a linear guide means in which a slider body has mounted on fore-and-aft ends thereof with end caps, one to each end, and the resulting combination fits in a carriage housing with being encircled with the housing. Then, bolts are screwed to unite together all the slider body, end caps and housing. In the prior linear guide means recited just above, the turnarounds and the return passages provided for the recirculating-ball circuits are formed in separate components, that is, the turnarounds are made in the end caps, one to each cap, while the return passages are constituted with the combined slider body and carriage housing. End seals to be kept in sliding contact with a tack rail are formed integrally with the carriage housing. Nevertheless, the linear guide means needs more than one fastener such as a bolt to join together all the slider body, end caps and carriage housing into an unit. As the turnarounds and the return passages provided for the recirculating-ball circuits are formed in separate components, that is, the turnarounds are made in the end caps, while the return passages are formed between the slider body and the carriage housing, accurate alignment in position of the turnarounds with the associated return passages is inevitable to ensure the recirculating-ball circuits allowing the rolling elements to run smoothly through there. Besides, the end caps and the carriage housing are made of the same synthetic resins.
In Japanese Patent No. 2846050 there is disclosed a linear sliding-motion bearing system having a slider that is comprised of a block of a thick plate provided underneath with a pair of widthwise opposing legs, an annular frame formed in a tetragonal configuration in top plan view so as to fit over the legs and having therein non-loaded raceway grooves allowing rolling elements to run through there with less subject to load, and a pair of elongated plates made therein with non-loaded raceway grooves, one to each plate. On assembly to complete the slider unit, the annular frame is secured around the legs by locking projections of the annular frame in recesses made on the outside faces of the legs. Then, the paired elongated plates are each fastened to the annular frame by inserting pins at four corners of the annular frame into holes in the elongated plates. With the linear sliding-motion bearing system constructed as stated earlier, since the annular frame is secured to the legs in a way the projections of the annular frame click into the associated recesses formed on the outside faces of the legs, there is no need to use any fastener such as a bolt or the like. Besides, the end seals are constructed to fit snugly in grooves formed in both the annular frame and the paired elongated plates. The linear sliding-motion bearing system recited above, though so constructed as to use no fastener such as a bolt in the assembly process, is adversely bulky in size because of the legs jutting out from the underneath of the thick plate. The non-loaded raceways provided between the confronting annular frame and elongated plates result in rendering the slider large in widthwise dimension. Any attempt to reduce the slider in width will result in rendering the legs slim in their breadth, thus raising a major disadvantage of reducing the slider in rigidity or stiffness. Besides, the recesses in which projections of the annular frame fit to join together them are formed in inner corners near the roots of the legs, while the annular frame is made considerably thick. This construction will plague the workers with a troublesome exertion of bending forcibly the projections to bring them into interlocking engagement with the inner recesses.
Another linear guide arrangement is disclosed in Japanese Patent laid-Open No. 248018/1992, in which a sliding block is composed of first and second block members, which are fastened together by screws.
In Japanese Patent No. 2775129 there is disclosed a linear guide arrangement in which a slider is constituted with a first member made therein with non-loaded passages for recirculating-ball circuits, a second member made with load raceway grooves, and third members arranged on forward and aft ends of the second member, one to each end, in a manner fitting in the first member together with the second member. With the linear guide arrangement recited just above, the first member is provided therein with the non-loaded area: return passages and turnarounds for the recirculating-ball circuits, whereas the second member is grooved to provide the load raceways. Thus, these members are made with drilled or cored holes in which fasteners fit to join together the members to complete the circulating-ball circuits.
SUMMARY OF THE INVENTION
The present invention, therefore, has as its primary object to overcome the problems as stated earlier and particularly to provide a linear motion guide arrangement adapted for use in machinery as diverse as semiconductor manufacturing machines, assembly machines and so on, which are made in a wide range of size. The present invention is more particular envisaged to provide a linear motion guide unit that is most preferable for use in very small machines. To this end, the linear motion guide unit of the present invention includes a slider constructed with a carriage, end caps and a carriage frame, each of which has any engaging means that may come into mutually fitting relation with a complementary engaging means of any counterpart, thus allowing to complete a co
Browdy and Neimark
Footland Lenard A.
Nippon Thompson Co. Ltd.
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