Plastic article or earthenware shaping or treating: apparatus – Female mold including tamping means or means utilizing mold... – Including means imparting diverse motion
Patent
1993-08-05
1994-12-20
Bushey, Charles S.
Plastic article or earthenware shaping or treating: apparatus
Female mold including tamping means or means utilizing mold...
Including means imparting diverse motion
264302, 264310, 264319, 425144, 425435, B29C 4100
Patent
active
053741803
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATION
This a national phase application of PCT/EP 92/02734 filed Nov. 27, 1992 and based, in turn, on German application P41 42 109.4 filed Aug. 19, 1992 under the International Convention. This invention relates to a device for producing plastic molded sheets by alternatively heating and cooling mold surfaces.
BACKGROUND OF THE INVENTION
A device of this type is known from German Open Application 34 17 727, in which mold or the casting form is heated in a furnace and after reaching the operating temperature is fed to the next operating station, the changing station in which the mold is coupled with a receptacle containing a liquid thermoplastic synthetic resin.
The heating of the mold with hot circulating air requires a high energy expense and is time consuming, since apart from the quantities of air required to heat the molding, also associated holding elements must be heated. The heating with circulating air also has the drawback that residue particles from previous operating steps pass from the mold which has been cooled and from which the plastic molded sheet has been separated into the circulating air and can be deposited again on the molding surfaces of the mold.
From French Patent 1 600 351 it is also known, further, to heat a biaxially rotatable closed mold from the exterior by means of an infrared radiator so that the pulverulent plastic found in the molding is distributed uniformly over the inner surface of the mold, is there melted and, upon cooling down of the mold, can be removed as a plastic molded sheet. This type of operation also requires a high cost and is time consuming with respect to the sequence of heating and cooling.
OBJECTS OF THE INVENTION
It is therefore the object of the present invention to provide a device; with a rapid succession between heating and cooling of the mold; and another object is to provide the mold which can withstand rapidly alternating thermal expansions.
SUMMARY OF THE INVENTION
According to the invention, the device includes the walls which are comprised of nongalvanically formed material of the hollow chamber fillable with the heating and cooling medium and which have bulges for compensating the thermal expansion.
In a device for producing synthetic plastic molded sheets by means of a mold rotatable about one or more axes of rotation, in which a thermoplastic synthetic resin powder melts upon a heated mold surface in the form of a film and after cooling of the mold wall can be removed in the form of a plastic molded sheet, the heating and cooling being effected in alternating sequence by means of liquid heating and cooling medium admitted into a hollow chamber of the mold. To compensate for thermal stresses between the housing walls defining the hollow chamber and the mold wall, bulges are provided in the housing wall to compensate stresses. The thermal stresses arise primarily because of the different materials of the mold wall and the housing wall. The mold wall is comprised of a galvanic material, for example, a copper-nickel alloy, while the housing wall is comprised of normal steel sheets.
The device is also formed with a closed mold chamber and two axes of rotation.
BRIEF DESCRIPTION OF THE DRAWING
The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the following single drawing in which the sole FIG. is a partial sectional view of the deice according to the invention.
SPECIFIC DESCRIPTION
The drawing shows a mold 1 comprised of a mold wall 2 which is composed of a material formed in a galvanic process, for example a nickel-copper alloy. According to this process, the mold surface 3 can be provided with a pitting as, for example, is customary for dashboards of an automobile.
Behind the mold wall 2 there is provided a hollow chamber 4 which is partly enclosed by the mold wall 2 and in the remainder by the housing wall 5 which is a steel sheet. The housing wall 5 which is sealingly fashioned on the mold wall 2 compr
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patent: 3454988 (1969-07-01), Cremer
patent: 3502135 (1970-03-01), Wertli
patent: 3565986 (1971-02-01), Byall
patent: 3978910 (1976-09-01), Gladwin
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patent: 4867660 (1989-09-01), Nagase et al.
patent: 5032076 (1991-07-01), Jackson, Jr.
patent: 5106285 (1992-04-01), Preston
patent: 5221539 (1993-06-01), Pallerberg et al.
Bushey Charles S.
Krauss Maffei Aktiengesellschaft
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