Bearings – Linear bearing – Combined with seal or guard
Reexamination Certificate
2001-06-27
2003-10-07
Footland, Lenard A. (Department: 3682)
Bearings
Linear bearing
Combined with seal or guard
C384S044000
Reexamination Certificate
active
06629779
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a linear displacement guide, comprising a guide rail and a slide supported via roller elements on the guide rail, with the guide rail being provided with a groove extending essentially in a longitudinal displacement direction and being provided with through openings for screws to fasten the rail, wherein the linear displacement guide is provided with a cover means to be arranged on the guide rail, and which can be secured to the guide rail to cover the through openings in the region of the groove. The cover means is designed to be a cover band with a center section and two adjoining clamping legs that are angled relative to the center section. The cover band can be attached to the guide rail by fitting the two clamping legs against the side walls of the groove and the cover band rests with the edge regions outside of the groove on a top surface of the rail.
Linear displacement guides of this type are used for the straight-line guidance of machine components, for example as required for the movement of the translational shafts in a machine tool. Even though the linear guides are frequently used in an extremely dirty environment and under unfavorable conditions, e.g. high temperatures, they are expected to be highly precise. Preventing the roller elements from becoming dirty is one essential precondition since this adversely affects the wear and the guidance accuracy.
For that and other reasons, seals are frequently installed on the fronts of the slides. These seals glide along the top surface and the side surfaces of the rail and, in the process, strip the dirt from the rail. This operation is designed to prevent the dirt from reaching the carriage inside.
In order to fasten the guide rails to a support, these are provided with through bores extending orthogonal to their top surfaces, which are designed to accommodate fastening elements such as screws. Since the fastening elements as a rule do not completely fill the through bores, dirt is often deposited there, which frequently enters the carriage inside despite the sealing lips. In addition, edges are formed on the surface because of the bores. If the sealing lips are guided directly over these edges, it can result in additional wear of the sealing lips. Dust and dirt furthermore easily collects along the edges, which cannot be removed reliably with the sealing lips and eventually damages the sealing lips.
Numerous types of covers for the through bores are already known for avoiding this type of dirt accumulation.
Thus, it is known to press plastic caps into the through bores, which are aligned with the surface of the guide rail. Another type of cover is disclosed in German Reference A 38 12 505 where the guide rail is provided on the surface with a longitudinal groove into which a plate in the shape of a strip is inserted.
A cover band with two legs is proposed in German Reference 43 11 641 C 1, which legs together with the center section respectively enclose a bending angle of preferably 70°. The two legs are intended to engage in undercuts in side surfaces of the guide rail. Since the undercut angles for the rail are larger than the bending angles, it is designed to effect a resilient contact pressure of the cover band against the rail. One disadvantage of this linear displacement guide is that it must meet relatively high requirements with respect to the production accuracy of the cover band. If the bending angle is too small, then the cover band is not securely fixed in place. If the bending angle is too large, the danger exists that the band can no longer be installed on the rail or only with great difficulty.
A two-part cover band is disclosed in German Reference 195 24 810 A1, which is to be inserted into a longitudinal groove of a guide rail. For this, a lower portion of the cover band engages in the groove and is clamped with side holding bars against the edges of the groove. The upper part of the cover band is inserted into a broad upper portion of the groove and is designed to be flush with the top of the rail, so that a top surface which is on the whole flat is formed. This solution also poses high requirements to the production accuracy of the linear displacement guide, in particular for fitting the upper part of the cover band exactly into the groove.
Thus, it is the object of the invention to create a cover for a linear displacement guide, which is designed to cover the openings for securing the rail and is not critical with respect to production tolerances, but should still ensure a secure covering.
SUMMARY OF THE INVENTION
The above object generally is achieved according to a first aspect of the invention by a linear displacement guide, comprising a guide rail and a slide supported via roller elements on the guide rail, with the guide rail being provided with a groove extending essentially in a longitudinal displacement direction and with through openings for screws to fasten the rail, wherein the linear displacement guide is provided with a cover means to be arranged on the guide rail, and which can be secured to the guide rail to cover the through openings in the region of the groove. The cover means is designed to be a cover band with a center section and two adjoining clamping legs, which are angled relative to the center section, and the cover band can be attached to the guide rail by fitting the two clamping legs against the side walls of the groove and the cover band resting with the edge regions outside of the groove on a top surface of the rail.
The above object generally is achieved according to a second aspect of the invention by a linear displacement guide, comprising a guide rail and slide supported via roller elements on the guide rail, with the guide rail being provided with a groove extending essentially in a longitudinal displacement direction and through openings for screws to fasten the rail, and the linear displacement guide is provided with a cover means to be arranged on the guide rail, and which can be secured to the guide rail to cover the through openings in the region of the groove. The cover means is designed to be a cover band with a center section and two adjoining clamping legs, which are angled relative to the center section; and the cover band can be attached to the guide rail by fitting the two clamping legs against the side walls of the groove. The center section of the cover band to be inserted into the groove is provided with a curved section that is directed away from the groove.
The cover band for the linear displacement guides according to the invention, which covers the complete groove, should be fastened inside the groove by “snap-together fastening” between the wall surfaces of the groove in the guide rail on the one hand and the clamping legs of the cover band on the other hand. It is particularly favorable if the snap-together fastening causes an at least slight elastic deformation of the center section in the form of a curvature. The curvature preferably should be convex, meaning pointing away from the groove. It may also be useful if the length of the bendable center section amounts to a multiple of the clamping leg length. In that case, larger production tolerances of the groove or cover band can lead to differently large elastic deformations of the center section. However, the operation of the linear guide is not hampered because even larger tolerances lead only to a relatively slight additional lift or deflection owing to the geometric conditions.
The cover band according to another preferred embodiment can comprise two parts, consisting of at least two sheet metal strips. The two sheet metal strips can be connected with suitable connecting techniques, e.g. gluing, soldering or welding. One cover strip is preferably arranged above a fastening strip and rests on one surface of the rail top. The clamping legs are provided on the fastening strip that is narrower as compared to the cover strip.
In addition, it has proven advantageous if at least some sections, preferably however the partial surfaces on the rail
Mischler Ernst
Rotzetter Heinz
Footland Lenard A.
Kunitz Norman N.
Schneeberger Holding AG
Venable LLP
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