Bearings – Linear bearing – Combined with seal or guard
Reexamination Certificate
1999-04-07
2001-01-09
Hannon, Thomas R. (Department: 3682)
Bearings
Linear bearing
Combined with seal or guard
C384S013000, C384S045000
Reexamination Certificate
active
06170986
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a linear rolling guide device suitable for relatively small equipment including office automation and measuring equipment.
In the conventional design a linear motion rolling guide assembly has a rail and a slider, through the rolling of a plurality of rows of rolling elements, riding and sliding on the rail.
The slider includes a steel body with an elongation extending downwards on both sides of a steel plate. A plurality of pairs of longitudinally arranged grooves, provided as tracks of the rolling elements, are formed on inside faces of the elongation. A plurality of pairs of holes as return passages of the rolling elements is drilled through the elongation. Two end caps, including the turnaround channel, which connects the track of rolling elements and the return holes, are mounted on both end faces of the steel body by fixing screws.
The smaller the hole is, the more difficult it is to drill. To overcome the manufacturing difficulty designs of return hole, formed by an open groove and a closure, member are provided, see the U.S. Pat. No. 4,637,739, and European patents EP 0 494 682 A2 and EP 0 474 948 A1.
EP 0 494 682 A2 and EP 0 474 948 A1, taught an alternative design which simplifies the manufacture and mounting complexity.
In the EP 0 494 682 A2 the disclosed interlocking design by using a snapping means, which is integrally formed on the longitudinal end of the closure member of the return track, to fix two monolithically end caps with a return track. The space of the snap means is limited by the shape of the closure member, which is also constrained laterally by the mounting holes for the connection of the surrounding part designed to slide relative to the rail, and vertically by the fitting edge for the surrounding part. A firm interlocking of the snap means, especially for the small size linear rolling guide device, is difficult to achieve.
In DE 195 38 665 A1 another snapping design is disclosed. A casement enfold the bottom of the steel body and form the ball return tracks space in between, two end caps are inserted vertically from top into the axial space between the endplate of the casement and the end face of the steel body. These two end caps press the steel body down to the casement by the projection overhead and are fastened vertically on the casement by using a snapping mean on the endplate of the casement and the outside face of the end cap. The casement provides positioning surfaces for the steel body and the end caps, respectively. A disadvantage of this is the indirect positioning between the end caps and the steel body. This elnarges the misalignment between the return channel and the turn-around channels of the rolling elements and causes an unsatisfactory rolling element re-circulation.
The conventional and economical fabrication of the precision plastic injection molding can achieve an positioning and form accuracy of ca. ±0.02 mm relative to a length 0.5~1.5 mm; and the minimal fillet radius/chamfer can achieve an accuracy of 0.1 mm. Any higher accuracy requirement will substantially increase the manufacturing cost. Such inaccuracy and the minimum fillet limit the minimization of the linear motion rolling guide device. A firm and accurate interlocking is secured only if the fitting surfaces of the parts to be attached together are large enough and are precisely conformed to each other. The smaller the linear motion rolling guide device is, the smaller is the fitting surface. This also limits the maximum extent of minimization of the dimensions.
SUMMARY OF THE INVENTION
Therefore, the object of this invention is to provide a linear guide device to solve the above mentioned problems and to furthermore minimize the dimensions thereof without increasing the manufacturing cost.
According to the above-mentioned object there is provided a linear motion rolling guide device including a longitudinal extended rail, a plurality of rows of rolling elements, a slider. By means of the rolling of the rolling elements between the raceway on the right-and-left side of the rail and the opposite facing race way on the slider, the linear motion rolling guide device slides relative to the rail. The slider further includes a steel body with an elongation extending downward on both sides of a base plate. The outside surface of the elongation, provided as the fitting and positioning surface for the attachment of the side frames, has a forcipiform with an opening laterally towards outside.
A pair of injection molded side frames are provided each has a longitudinally arranged profiled member having the same length as the steel body and two transversely arranged end plates on both end of the profiled member in one single mold. The profiled member, bilaterally engaged into the forcipiform of the elongation, are vertically fixed to the steel body when the fitting profile are laterally and fixedly attached to the outside surface of the elongation. The full use of the outside surface of the elongation as fitting surface provides a firmer attachment between the side frames and the steel body. This design can further minimize the dimensions of the linear rolling guide device, compared to those without full use of the outside surface as fitting surface. At least one longitudinally arranged all-round closed hole is formed inside the profiled member as the return passage of the rolling elements.
The endplates longitudinally constraining the steel body in between are formed by a transversely arranged base plate, perforated by the return passage and has at least one convex half-roundness on the base plate, stretching from the inside surface of the return passage without any misalignment in between and provided as the internal guiding surface of the turnaround channel.
Two end caps are externally attached to the endplates, each has at least one pair of concave half-roundness. The two end caps, together with the convex half-roundness, form a closed turnaround channel. The end of the concave half-roundness aligns to the end of the return passage more precisely by direct positioning between the end caps and the side frames. This brings a smoother running of the rolling element re-circulation.
The steel body, the side frames, and the end caps have means for attachment and positioned to each other.
Such means of attachment is preferably formed by an interlocking means on the endplates, such as tenon, and a pair of its counterparts on the end caps, such as slots. The end caps interlock the two side frames crossly together by engaging the interlocking means on the endplates with their counterparts on the end caps. As a result the two opposed side frames are forced to approach each other to within a certain distance defined by the distance between the two counterparts. The width of the two opposed outside surface of the elongation of the steel body is designed to meet the distance between the two opposing side frames so that the side frames are firmly attached to and clamp the steel body bilaterally tightly with a certain pressure. The end caps are also transversely and fixedly fixed and positioned to the side frames through the engagement of the interlocking means and their counterparts. The engagement between the positioning means, preferably the same as the interlocking means, on the endplates and their inter-fitting means, preferably the same as the counter parts, on the end caps, brings a direct positioning between the end caps and the side frames. A pair of snap means is longitudinally integrated on the endplates, preferably direct on the counterparts, such as tenon, for saving space, to interlock the end caps on the front and rear end of the slider longitudinally without using screws.
The side frames are fabricated by an injection molding process from engineering plastic or with metallic powder having a molding die with additional bilaterally sliding dies. The through holes as return passage of the rolling elements are injection molded by a through pin having the same form as and a length slightly longer than the throu
Chang Kuei-Hsin
Chen Shyuan-Jye
Hong Chih-Chieh
Hsu Ming-Che
Chieftech Precision Co., Ltd.
Hannon Thomas R.
Liauh W. Wayne
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