Plastic article or earthenware shaping or treating: apparatus – Press forming apparatus having opposed press members
Patent
1985-06-02
1986-05-20
Woo, Jay H.
Plastic article or earthenware shaping or treating: apparatus
Press forming apparatus having opposed press members
72701, 100258R, 425411, B29C 3300
Patent
active
045898367
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic press, and more particularly to a hydraulic press having adjustable supports for providing a platen surface thereof with a predetermined configuration during the pressing operation.
Known hydraulic presses may often be referred to as either of two basic types. In the one type they have a heavy frame, generally consisting of parallel frames made from steelplate with a fixed platen or table, and a movable platen or table actuated by force generating means. The other type includes two heavy plate or pressure beam structures, each of which can carry or form a platen or press table. The structures can be moved towards, or away from each other with the aid of force-generating means and yokes or C-shaped links. Although hereinafter briefly described, FIGS. 1a, 1b and FIG. 2 in the accompanying drawing are preliminarily referred to in this connection.
In FIG. 1 there are illustrated plate frames 1 with top portions 3 and bottom portions 5, while the numerals 7 and 9 respectively denote a fixed and movable platen, the latter being actuated by hydraulic cylinders 11. In FIG. 2 the numerals 21 and 23 respectively denote top and bottom pressure plate structures with respective top and bottom platens 25 and 27, while 29, 31 denote a yoke keeping the pressure plates 23 and 21 together. The plates 21 and 23 can be urged towards each other with the aid of the yoke and hydraulic cylinders 33.
When forces are applied with the aid of the corresponding hydraulic cylinders the FIG. 1a frames 1 and the FIG. 2 members 21, 23 deflect in a manner exaggeratedly illustrated in FIGS. 3 and 4, respectively. In many cases this results in considerable drawbacks, e.g. in pressing records which must have a very uniform thickness, moulding goods in moulds which must be kept parallel, deep-drawing sheet in presstools, shearing, edge folding of plates, tubes etc.
Different measures have been proposed for reducing the deflection exemplified in FIGS. 3 and 4. The frames, pressure beam structures etc. can be made very stiff by increasing their material content, but this is an expensive solution that also increases the weight of the press. The surfaces can also be given an initial curvature by uneven heating of the frames, such as to keep deflection within acceptable limits when the force is applied. This is however a solution that is relatively expensive, especially from an operational standpoint and is furthermore only usable in a restricted number of applications. It has also been suggested to float the platen on a hydrostatic bed, which likewise is an expensive solution in this case also requiring extra safety measures.
SUMMARY OF THE INVENTION
The present invention provides a generally utilizable principle for satisfying prevailing desires regarding the shape of the platen pressing surface during pressing in a high pressure press. A hydraulic press in accordance with the invention includes a frame with platens, at least one of the latter being carried or formed by a pressure plate structure adapted for enabling transmission of the pressing force to the object to be pressed between the platens. The inventive press is distinguished in that the pressure plate structure carrying or forming the platen is essentially carried solely by supports, positioned between the defining edges of the structure, these supports being positonally adjustable, such that the surface of the platen assumes a predetermined shape during the pressing operation.
In most cases, the desired pressing surface is as flat as possible, or follows the shape of the other platen, which ensures uniform thickness of the item produced as far as possible.
It should be emphasized that the pressure plate structure is to be free in respect of movements in the pressing direction in relation to the press frame, i.e. not clamped or supported by it other than with the adjustable supports mentioned above. It is further emphasized that carrying the pressure plate structure on the press frame with the aid of
REFERENCES:
patent: 3136181 (1964-06-01), Eckold
patent: 3195183 (1965-07-01), Phillips
patent: 3426116 (1969-02-01), Walters
patent: 3446879 (1969-05-01), Atkin
patent: 3570060 (1971-03-01), Stephenson
Fjellman Press AB
Fortenberry J.
Woo Jay H.
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