Injection molding apparatus
AssigneeSiemag Siegener Maschinenbau GmbH
InventorsDieter Alwes, Helmut Eckardt, Hans Peter Leiste, Robert Albert Melcher
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Abstract
The invention is concerned with an injection molding apparatus in which thermoplastic material mixed with an expanding agent is kept in a plastic state below the reaction temperature of the agent and is passed generally continuously through an inter-connecting passage to a transfer cylinder; by flowing through the passage, the mass is heated above the reaction temperature and the built-up pressure prevents foaming of the thermoplastic until it is injected into a mold.
Claims28
Injection molding apparatus, comprising
- a. a screw-type extruder driven by a motor, the extruder having a housing containing heating elements,
- b. an accumulator having a cylindrical chamber whose axis is spaced from the extruder, the accumulator having a loading piston lying in the chamber, the accumulator also having a wall containing heating elements,
- c. an intermediate housing extending between the extruder and the accumulator, the walls of the housing defining a treatment chamber being provided with heating means, and
- d. a treatment element lying in the treatment chamber to define a thin annular passage therebetween,
- the end of the treatment chamber and the end of the treatment element adjacent the accumulator being provided with generally pointed surfaces, and the element being axially adjustable in the treatment chamber to accurately determine the thickness of the passage therebetween.
Apparatus for the fabrication of plastic-foam bodies with injection moldings having an extruder by which the thermoplastic mixed with an expansion media is plasticized below the reaction temperature of the media and is introduced continuously to a transfer cylinder through a connecting canal, having a rotating body independent of the extruder surrounded closely by a housing, having a motor by which the rotating body is driven and by which the thermoplastic mass is pressed with an axial component through a thin gap formed between the rotating body and the housing, having means whereby the thermoplastic during passing is heated above the reaction temperature, and having means whereby the built-up pressure within the transfer cylinder prevents a foaming of the plastic mass until it is injected into the mold,
- characterized by the fact that the rotating body (108) and the surrounding housing (105) are formed with conical surfaces over at least the portions which form the aforementioned gap (111) and that the rotating body is mounted on an adjustable support so that the axial relationship between the body and the housing can be changed to adjust the gap.
Dependencies are inferred from the claim text.