Method and apparatus for producing thick-walled molded parts
AssigneeKrauss-Maffei Kunstofftechnik GmbH
InventorBernd Klotz
Life of this patent
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Abstract
The invention relates to a method and apparatus for making thick-walled plastic parts, in particular blanks for optical lenses. In accordance with the invention, a two-phase production process is proposed in order to make thick-walled lenses with high optical quality and homogenous material properties, wherein in a first phase, a thin lens is first made through injection molding, and in a second step the lens is enlarged, i.e. “inflated”, until the final thickness through continued injection of plastic material.
Claims15
A method of making thick-walled molded plastic parts, in particular thick-walled optical lenses, through provision of a die with variable cavity, comprising the steps of:
- a) closing the die and adjusting the cavity to a first size which corresponds to the dimension of a thin-walled molded part;
- b) injecting plastic material to completely charge the cavity, while maintaining the first size of the cavity;
- c) continuing to inject plastic material, while expanding the cavity to a second size which is greater than the first size and corresponds to the dimension of a desired thick-walled molded plastic part,
- d) forming a thick-walled molded plastic part;
- and
- e) opening the die and removing the thick-walled molded plastic part.
A method of making a plastic part;
- comprising the steps of:
- injecting plastic material into a cavity of a die in a first process phase, while maintaining the cavity at a first size;
- and
- continuing to inject plastic material into the cavity in a second process phase while expanding the cavity to a second size which is greater than the first size to form a finished article.
Apparatus for making thick-walled molded plastic parts, in particular thick-walled optical lenses, comprising:
- a first die platen;
- second die platen;
- and
- a compression ram which is movable linearly in one of the die platens via an adjustable stroke, and which together with the first and second die platens defines a variable cavity, wherein in a first position of the compression ram, the cavity has a minimum size,
- wherein at least one of the die platens has a groove which surrounds an end of the compression ram, said groove extending at least along the stroke of the compression ram in parallel relationship to a movement path of the compression ram and communicating with the cavity.
Apparatus for making a plastic part, comprising:
- a first die platen;
- second die platen;
- and
- a compression ram which together with the first and second die platens defines a cavity for receiving plastic material, said compression ram being movably received in one of the die platens for adjusting a size of the cavity between a minimum size and a maximum size,
- wherein at least one of the die platens has a groove which surrounds a cavity-proximate end of the compression ram and is fluidly connected to the cavity to receive plastic material to thereby insulate the cavity-proximate end of the compression ram from the die platens.
Dependencies are inferred from the claim text.