Bearings – Linear bearing – Combined with seal or guard
Reexamination Certificate
1999-11-30
2002-08-20
Bucci, David A. (Department: 3682)
Bearings
Linear bearing
Combined with seal or guard
C384S049000
Reexamination Certificate
active
06435719
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a linear guide device, comprising a guide rail with a longitudinal axis and at least one guideway, and a runner assembly guided at the guideway, of which there is a least one, in the direction of the longitudinal axis.
Contaminants on the guideway may impair the smooth running and guide precision of the runner assembly and cause premature wear. These contaminants may come from hot chips which are produced in cutting machine tools and come to lie on the guideways, in which case there is even a risk of the chips burning into the guideways. Other contaminants are particles of dirt and dust, which may settle on the guideways. If they mix with coolants or lubricants, this may produce an abrasive mixture which, if it enters the runner assembly, may cause abrasion at the guideways and the guide members of the runner assembly. Although conventional runner assemblies are frequently sealed off all round from the guide rail, the possibility of contaminants entering the interior of the runner assembly cannot be entirely ruled out. For it is often not possible to prevent microroughness in the guide rail surface and at the sealing elements which are used. The contaminants may then penetrate through such microroughness to the interior of the runner assembly.
STATEMENT OF THE PRIOR ART
It is known to cover the guide rail by a bellows which is coupled in terms of movement to the runner assembly in order to provide protection against contaminants, as presented, for example, in a prospectus of the company Deutsche Star entitled “Schienenführungstische” (“Rail guide tables”), number RD 82501/06.96. However the material of the bellows may easily scorch because of hot chips, which is why telescopically retractable and extensible covering mechanisms have been resorted to for applications in which a high incidence of hot chips is to be expected. However these mechanisms entail a high expenditure. The bellows and telescopic covering also require storage space, which reduces the available travel of the runner assembly.
Also known from DE 43 34 311 A1 is a covering solution in which a guide rail is mounted in a U-shaped profiled housing on the bottom thereof and the longitudinal opening of the housing is closed by a cover strip which lies against the mutually opposite side walls of the housing. This solution offers reliable protection against the penetration of contaminants into the interior of the housing, although depends on the presence of the U-shaped profiled housing and is therefore only suitable for special applications.
OBJECT OF THE INVENTION
The object of the invention is to present a covering solution which is suitable for a broad field of application of the linear guide devices and which affords reliable protection against contaminant-induced impairments of the guide quality of the linear guide device.
SUMMARY OF THE INVENTION
A linear guide device comprises a guide rail with a longitudinal axis and at least one guideway. A runner assembly is guided at the guideway, of which there is a least one, in the direction of the longitudinal axis.
The guideway is covered—in the direction of the longitudinal axis—on both sides of the runner assembly substantially over the respective entire usable remaining length by a cover strip which lies against at least one cover strip contact zone of the guide rail or is so close to said cover strip contact zone as to prevent contaminations to reach said cover strip contact zone without “real body contact”. The cover strip preferably lies, however, directly against the guide rail. There is as a result very little dependence on the constructional installation conditions of the linear guide device, irrespective of whether this is constructed with or without a U-housing for example. In addition, as it is not necessary for the cover strip to be compressed and expanded like bellows, it may be made of a material which is sufficiently insensitive to hot chips. The covering solution according to the invention entails a distinctly lower construction expenditure than the above-mentioned telescopic coverings.
The cover strip contact zones and the guideway may basically correspond, at least in part. Optimum adaptation of the cover strip contact zone to the requirements of the cover strip, especially as regards the tightness of the system, without having to take account of the specific configuration of the guideway, can be achieved by the cover strip contact zone and the guideway differing, at least in part.
Optimum preservation of the guideway is achieved if the cover strip covers the guideway in contact-free fashion and lies against cover strip contact zones of the guide rail which are located transversely to the longitudinal axis on both sides of the guideway. This can easily be achieved by disposing the guideway in a depression in the guide rail which is covered by the cover strip and is formed between the cover strip contact zones.
Generally speaking, the opposite cover strip contact zones will comprise large-side contact zones against which the cover strip lies at its large side which faces the guideway., In this case it is advisable for the large-side contact zones to be formed by plane, coplanar contact faces. The cover strip can thus lie flatly and tightly against the guide rail.
However it is also possible for at least one cover strip contact zone to be formed as a narrow-side contact zone against which the cover strip lies at its narrow sides. There is no possibility of the aligning function of the narrow-side contact zones causing the cover strip to slip and possibly expose the guideway locally, in particular when mutually opposite narrow-side contact zones are formed at the guide rail for both narrow sides of the cover strip.
The linear guide device may be installed in such a way that the cover strip lies against a—in the installed position vertically lower side of the guide rail and is consequently at risk of separating from the guide rail, if it is not tensioned with sufficient tautness, and allowing dirt to penetrate to the guideway. It is expedient, in particular—although not exclusively—in a case of this kind to provide securing means at the guide rail and/or at the cover strip which secure the cover strip to the guideway outside of the region of the runner assembly in the covering position. This may be achieved, for example, by the possibility of frictionally clamping the cover strip between mutually opposite narrow-side contact zones. Alternatively to or in addition to this, it may be possible to positively secure the cover strip in its covering position at the guide rail by, for example, undercutting the narrow-side contact zones for the engagement of the narrow sides of the cover strip. The cover strip may be retained with some play in the undercuts of the narrow-side contact zones. However it may also be clamped at its narrow sides or/and at its large sides. The cover strip may also be secured by locking means which, rather than passing over the entire length of the guide rail, are formed just locally and distributed over the length of the guide rail.
The runner assembly may be constructed in end regions with strip curvature means which give the cover strip a forced curvature facilitating its entry between mutually opposite narrow-side contact zones and therefore reducing the distance between the narrow sides of the cover strip. The curvature of the cover strip may be of assistance in enabling it to be easily introduced into undercuts of the guide rail by way of its longitudinal edges. It is in this case possible for the cover strip to completely uncurve again after being introduced into the undercuts. If, on the other hand, the cover strip is to be frictionally clamped at its narrow sides, it is advisable to adapt the width of the cover strip to the securing means such that the cover strip is pre-curved in the covering position.
According to a further variant, the securing means may also be achieved by the possibility of retaining the cover strip in the covering position through magnetic means.
The
Dütsch German
Riedel Gerhard
Baker & Botts LLP
Bucci David A.
Hansen Colby
Rexroth Star GmbH
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