Work holders – Operator supported – Handle manipulation for jaw actuation
Reexamination Certificate
2001-04-16
2003-06-17
Wilson, Lee D. (Department: 3723)
Work holders
Operator supported
Handle manipulation for jaw actuation
C269S003000, C269S170000
Reexamination Certificate
active
06578837
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to clamps and, more specifically, clamping having a first jaw connected to a rod that passes through a housing which incorporates a second jaw. The housing also includes an actuating handle for moving the two jaws together towards a clamping position.
A clamping tool of the type in question in the form of a clamp is known from German Patent Application DE 39 17 473. This known clamp has a movable clamping jaw which is fitted at the end of a push rod. This clamping jaw engages through a housing which carries a second, fixed clamping jaw. A grip projects from the housing. By means of a handle, which is arranged pivotably on the housing and can be moved towards the grip, the push rod can be displaced such that the movable clamping jaw is moved in a stepwise manner towards the fixed clamping jaw. On the handle side, in the direction of the two clamping jaws, the previously known clamp has a releasable detent against reverse displacement, in the form of a clamping lever. This is intended to prevent the movable clamping jaw from being able to be displaced in the opposite direction. A free end of the lever forming the return displacement detent projects out of the housing there and can be pivoted in order to release the return displacement detent. In the released position, the two clamping jaws can be moved apart in opposite directions. The plane which is defined by the jaw surface of the fixed clamping jaw and runs substantially transversely to the direction of extent of the push rod is located directly in front of the free end of the lever of the return displacement detent lever. This results, in the case of unfavourable spatial conditions, in the position of the workpiece located in the said plane adversely affecting actuation of the lever. Furthermore, in the case of a clamp of this kind, the fact that the free end of the push rod can be displaced rearwards in a stepwise manner in relation to the grip upon actuation is disadvantageous.
If the clamp is used, for example, in such a manner that the clamping-jaw plane is located in the horizontal, and if the clamp is to be placed in position from above, then the free push-rod end projects upwards into the space in a disruptive manner. Although this clamp allows use in a large number of clamping circumstances, reliable release of the clamping jaws is not guaranteed in specific clamping circumstances, in particular in the abovementioned clamping circumstances. There is also only a small actuating path available for the clamping lever.
From U.S. Pat. No. 3,427,016, a further clamp is known. In this, a rotatable, toothed rod is fitted parallel to the push rod and has one end of a pivotable handle engaging in it. The two clamping jaws can be moved towards one another by engagement in the teeth. In this case, the two clamping jaws are located to the rear of the actuating handle. Although a catch is fitted in the housing, the catch acting as return displacement detent, this is not itself intended to be releasable. In order to release the return displacement detent, the toothed rod has to be rotated by engagement on a lever fitted to the movable jaw. It is also the case with this clamp that the release of the return displacement detent leaves room for improvement.
A clamp is also known from Utility Model 87 03 379.8. In this case, although the release lever of the return displacement detent is remote from the movable jaws, the problem mentioned in the introduction arises if clamping surfaces located in the horizontal plane are to be clamped from above.
A further clamp is known from GB 21 78 689. The handleability of this clamp corresponds approximately to that of Utility Model 87 03 379.8.
From U.S. Pat. No. 2,688,351, a clamp is already known in which the pull rod, on one side, provides a toothing arrangement in which there engages a catch which can be displaced by a handle, the handle being displaceable towards the grip, in order thus for the movable jaw, located at the end of the pull rod, to be displaced towards the fixed jaw, which is fitted to the housing. As detent against return displacement, this clamping tool has a second detent catch, which is encapsulated in the housing, engages in the toothing arrangement by spring bias and, for rearward displacement of the movable clamping jaw, has to be displaced out of the toothing arrangement. This displacement is effected by transverse pivoting.
The invention is based on the problem of developing a clamp of the type in question such that reliable release of the clamping is possible for all clamping circumstances, and that it can be placed in position in a more functionally advantageous manner during clamping.
The object is achieved by the invention specified in Claim
1
. Subsidiary claims provide advantageous. According to the invention, it is provided first and foremost that a release lever acts on the return displacement detent, and that both the handle and the release lever are located on that side of the grip which is directed away from the clamping zone between the two clamping jaws.
On account of this configuration, although the release lever is located in a position remote from the clamping zone, it is, at the same time, at a defined spacing from that side of the workpiece which is directed towards the release lever. Even in unfavourable clamping circumstances in which that surface of the workpiece which is directed towards the release lever extends beyond the push rod to the grip side or actuating-member side of the push rod, reliable actuation of the release lever is possible. On account of an aligned arrangement of the rear side of the grip in relation to the clamping surface of the fixed clamping jaw, this grip, in certain clamping operations, can even perform a workpiece-supporting function. Located between the rear side and the fixed clamping jaw is a rearwardly projecting slot from which the push rod projects. Since the handle is located between release lever and grip and the grip is located nearest the clamping zone or the workpiece, it is even possible for the handle to be used as a second grip for the purpose of actuating the release lever. For this purpose, in particular an approximately triangular clearance located between the handle and grip has proven advantageous. Furthermore, the handle actuation, directed counter to the push-rod displacement, makes for favourable pivoting of the release lever and handle on the housing. The pivot points for the two levers are located on the same side of the push rod, to be precise such that in order to actuate the release lever, rather than having to clasp the grip, all that is required is to clasp the handle protecting freely from the housing. The fixed clamping jaw is located on the opposite side of the pivot points or of the grip portions. It is advantageous if the release lever is associated with that end of the housing which is located opposite the fixed jaw.
A second aspect of the invention relates to development of the release lever. The release lever is configured such that the first clamping jaw is displaced rearwards in a stepwise manner above the second clamping jaw by actuation of the release lever. This configuration ensures proper single-handed use of the clamping tool. In a preferred configuration, the return displacement detent has a slide which can be latched or clamped to the pull or push rod. This slide can be displaced freely over the pull or push rod by the release lever counter to the force of a return spring. When actuation of the release lever is completed, the slide is then displaced into a clamping or latching position and is displaced back by the return spring, the pull or push rod being carried along in the process. The return spring preferably acts on one side of the slide and thus produces, in the absence of counter-clamping or counter-support of the opposite side, a tilted position. In order to be able to slidingly displace the slide over the pull or push rod, it is advantageous if an arm of the release lever presses on the slide at the eng
Blank Stefan
Degen Klemens
Noniewicz Zbigniew
Schüller Hans-Jürgen
Bell Boyd & Lloyd LLC
Wilson Lee D.
wolfcraft GmbH
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