Work holders – With fluid means – Vacuum-type holding means
Patent
1995-04-25
1997-09-30
Watson, Robert C.
Work holders
With fluid means
Vacuum-type holding means
B25B 1100
Patent
active
056719108
DESCRIPTION:
BRIEF SUMMARY
This invention relates to vacuum plates.
BACKGROUND OF THE INVENTION
Vacuum plates are well known in the engineering field as means for holding a workpiece securely in place whilst a machining operation is performed on it. They may take various shapes. For example, they may be generally flat, rectangular tables, which afford a substantially horizontal support surface workpieces. Alternatively, they may be of circular shape, affording a substantially upright support surface upon which a workpiece is secured, in the manner of a chuck.
In fact, such a latter configuration may be referred to as a "vacuum chuck", but for the sake of convenience, in this specification, the term "vacuum plate" is used to refer to all possible configurations of support means which retain a workpiece or other article in position by means of a vacuum--whether for machining, any other operation, or simply holding and/or transport. Although the term "vacuum" is used here conveniently, it is usually the case in practice that a perfect vacuum is never achieved--an average pressure of around 0.1 bar is more usual.
In the published specification of our PCT patent application No. WO 92/10336, we disclose a number of vacuum plate systems each of which comprises a base plate for providing a source of vacuum distributed over an area of the plate, and a support plate which is disposed between the base plate and a workpiece to be held by the vacuum plate system.
Various support plates are disclosed, and their purpose generally is to transfer a vacuum as effectively as possible from a base plate to a workpiece, in order to hold the workpiece as firmly as possible whilst, for example, a machining operation is performed upon it. A useful advantage of the support plates is that they may be cut into during a machining operation, and replaced and/or recycled.
A number of interesting features are disclosed also of the base plates, intermediate plates and/or pressure supply arrangements. All or any of the many features disclosed in our above-mentioned specification WO 92/10336 may be combined, where practicable, with the features of the present specification, and the reader's attention is specifically directed to our above-mentioned specification WO 92/10336, the contents of which are incorporated herein by reference.
BRIEF DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention aim to provide improved support plates and vacuum plate systems incorporating such support plates.
According to a first aspect of the present invention, there is provided a support plate adapted to be disposed between a base plate of a vacuum plate system and a workpiece to be held by the vacuum plate system, the support plate comprising: contact respectively with a said base plate and workpiece; vacuum, in use, between said reverse and working surfaces; and to form, in use, a seal with a contact surface of a respective workpiece: projections has a closed shape and seals of a smaller size are interposed between seals of a larger size.
Said closed shape may be a circular shape.
A plurality of said holes may be provided in said sheet of material.
Each of said holes may be located within a respective one of said closed shapes.
At least one of said closed shapes may not have a respective said hole within it.
Preferably, said projections are formed integrally in said sheet.
According to a second aspect of the present invention, there is provided a support plate adapted to be disposed between a base plate of a vacuum plate system and a workpiece to be held by the vacuum plate system, the support plate comprising: contact respectively with a said base plate and workpiece; vacuum, in use, between said reverse and working surfaces; and into that surface.
A respective said network of open grooves may be formed in each of said reverse and working surfaces to open into the respective surface.
Preferably, said hole opens into at least one said network of grooves.
At least one said network may comprise a rectangular array of grooves.
The invention extends to a suppo
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Davies David
Petrie Laurence R.
Carne Charles N.
Carne James C.
Davies David
Petrie Laurence R.
Watson Robert C.
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