Work holders – Relatively movable jaws – Plural jaw pairs
Reexamination Certificate
2000-06-15
2001-11-27
Hail, III, Joseph J. (Department: 3723)
Work holders
Relatively movable jaws
Plural jaw pairs
C269S045000, C269S075000
Reexamination Certificate
active
06322063
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a clamping apparatus for workpieces, especially body parts with one or more tensioner, which can be positioned on a said clamping table. The tensioners have a plurality of tensioner parts, which are guided adjustably in relation to one another along at least one axis and which have a positioning device (
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) with a vertical adjustment device and a fixing device for the mutual adjustment.
BACKGROUND OF THE INVENTION
Such a clamping apparatus has been known from DE-A 197 16 874. It comprises one or more tensioners, which can be positioned on a clamping table and with which the workpiece, e.g., body parts of vehicles, can be clamped. The workpiece can then be welded or machined in another way by an industrial robot or the like. The tensioners are of a multipart design and comprise a foot part, a middle part and a head part, which are guided adjustably relative to another along at least one axis. A positioning apparatus with vertical adjustment apparatus and a fixing device are present for the mutual adjustment. The vertical adjustment apparatus comprises one or more adjusting screws between the parts of the tensioner. The foot part may also be fastened to the clamping table via a spacer placed under it. The fixing device comprises an elongated hole guide with two clamping screws. Moreover, the positioning apparatus may also comprise an angle adjustment apparatus with an additional pivot bearing between the parts of the tensioner. As an alternative, it is also possible to use a bent middle part. The lower adjusting screw for the vertical adjustment apparatus is reserved for the supplier and is used to set a fixed basic length of the clamping unit specified by the user. Only the upper adjusting screw between the middle part and the head part is then accessible to the customer and user. He can then perform a fine adjustment within a narrow range by apparatus of this adjusting screw. The tensioners are accurately positioned according to the user's specifications and hold the workpiece in the specified position. Inaccurate workpieces (pilot run) as well as warping during machining may make it necessary to adjust the clamping points. This adjustment can be carried out by the customer with the prior-art tensioner only with the upper adjusting screw and in a range limited by the screw. The inaccuracies inherently existing in adjusting screws must be accepted here. The tensioner as a whole can be adjusted vertically continuously by apparatus of the adjusting screws.
WO 96/38265 shows another clamping unit, which comprises a bracket, a clamping frame, a centering piece and a support that can be fastened thereto. This clamping unit has a fixed, predetermined length, which is determined by the length of the support cut as needed. The support may assume different angular positions in relation to the foot-side bracket, which can be achieved by dividing the clamping frame and the centering piece into mutually independent components and by apparatus of correspondingly shaped connection surfaces.
U.S. Pat. No. 2,497,943 discloses another clamping unit for sewing machines, typewriters, electric motors or the like for repair purposes. It has a pivotable bracket with clamping jaws for this purpose, which can be adjusted by apparatus of a spindle.
Clamping pallets for workpieces on machine tools or gaging machines have been known from DE-A 195 36 341, DE-A 42 43 370 and DE-A 38 01 813. The tensioners have clamping claws, which are vertically adjustable by apparatus of adjusting screws, toothed plates or the like. Finally, a clamping unit with a plurality of clamping parts that are angularly adjustable in relation to one another has been known from GB-A 1 466 434.
SUMMARY AND OBJECTS OF THE INVENTION
The object of the present invention is therefore to provide a more flexible clamping apparatus.
According to the invention, a clamping apparatus is provided for workpieces, especially body parts. The clamping apparatus comprising one or more tensioners, which can be positioned on a clamping table. The tensioners have a plurality of tensioner parts, which are guided adjustably in relation to one another along at least one axis and which have a positioning apparatus with a vertical adjustment device and a fixing device for the mutual adjustment. The vertical adjustment has a coarse adjustment device and a fine adjustment device, wherein the coarse adjustment device has a grid-like mount and a hinge pin on one tensioner part and the fine adjustment device has a support and optionally one or more fitting plates and a fixing device for supporting the hinge pin on the other tensioner part.
In the clamping apparatus, the individual tensioners have a multipart design in themselves and are adjustable along at least one translatory and/or rotary axis, i.e., especially vertically and/or in at least one lateral direction and/or in at least one angle. For an exact adjustment, they have a positioning means and a fixing device, wherein these means may be structurally separate or combined. As a result, the tensioners can be adjusted vertically and/or angularly as desired to compensate distortion and warping phenomena. The tensioners are thus changed in themselves. Disassembly and repositioning of the tensioners is not necessary.
The clamping apparatus has the advantage that a small number of standard elements are sufficient for a broad field of application. Continuous vertical, lateral and/or angular adjustment is possible with high accuracy and reproducibility.
Two possibilities of adjustment, namely, a coarse adjustment and a fine adjustment for highly accurate adjustment that nevertheless covers a broad range, are possible for vertical adjustment. A grid-like mount with a stepwise adjustment in greater increments in combination with suitable, accurately fitting supports offers advantages at least for the vertical adjustment in terms of handling, precision and the manufacturing and assembly efforts. The supports may be designed as disks and have an additional lateral mobility for the lateral adjustment.
The clamping apparatus makes possible a simple adjustment at the manufacturer or at the site of installation. Furthermore, it is possible to prepare the foot part and the adjusting part of the tensioners from simple stock parts without project-specific machining. The accurate setting of the tensioners is performed only by means of the positioning and fixing device.
The preferred fixing device with the clamping apparatus has the advantage that it can also be used as a positioning device for the lateral adjustment at the same time. By placing a wedge part or a pressure piece against a corner area of the component member or adjusting part being guided, force is introduced obliquely, which ensures better fixation. As a result, it is possible, in particular, to support the adjusting part in a plurality of directions or axes. Additional fixations may be eliminated. The adjusting part can be accurately positioned by means of distance plates and fitting plates. Moreover, the position of the adjusting part can be statically defined.
The fixing device allows tolerance errors on the component members and the parts of the clamping apparatus and as a result it always ensures reliable fixation in the correct position. By inserting distance plates and fitting plates, shim rings or other similar positioning elements, particularly accurate mutual positions of the component members can also be set and secured.
For the lateral adjustment, additional lateral mobilities may be available at the other positioning means. These may be advantageously provided in the area of the supports and hinge pins. Furthermore, it is favorable to arrange a positive-locking plug-in connection between the support and the hinge pin and, in addition, to provide a fixation. This is practical for accurate positioning and prevents the loss of parts during disassembly or reassembly.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed
Hail III Joseph J.
Kuka Schweissanlagen GmbH
McGlew and Tutle, P.C.
Shanley Daniel
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