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Apparatus and method for injection moulding with ventilation means

  • US 7,850,883 B2
  • Filed: 10/08/2003
  • Issued: 12/14/2010
  • Est. Priority Date: 10/08/2002
  • Status: Expired due to Fees
First Claim
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1. A method for forming a product from a mass comprising at least natural mono-or polymers, the method comprising:

  • introducing said mass into a mold cavity in fluid communication with an overdose space and a deaeration channel and heating the mass therein, wherein a blowing agent is activated during the introduction and heating of the mass in the mold cavity such that a portion of the mass flows through openings into said overdose space, reducing a pressure inside the mold after the mold is substantially filled with the mass, by reducing the pressure below the boiling pressure of the blowing agent,deaerating the mold cavity via said overdose space and said deaeration channel andregulating the pressure in the mold from said deaeration channel such that in a controlled manner mass flows into the overdose space and in a controlled manner the blowing agent is activated for forming cells in the mass, wherein the mold cavity is used with at least two openings which connect to the overdose space, wherein, in the at least two openings, different pressures and/or flow resistances are independently generated such that flow of the mass from an injection opening in the direction of a first of said openings is carried out at a different speed than flow of it in the direction of the other of said two openings.

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