Process and device for injection-molding plastics

• US 4,420,452 A
• Filed: 06/26/1981
• Issued: 12/13/1983
• Est. Priority Date: 06/26/1981
• Status: Expired due to Fees

• Current Assignee: Stamicarbon B.V. (Maire Tecnimont SpA)
• Original Assignee: Stamicarbon B.V. (Maire Tecnimont SpA)
• Inventors: Schlosser, Willem, van Dalen, Hendrik
• Primary Examiner(s): Pavelko, Thomas P.
• Application Number:
  US06/277,854
• Time in Patent Office: 900 Days
• Field of Search: 264/328.8, 264/328.12
• US Class Current: 264/328.8
• CPC Class Codes: B29C 2045/0032 sequential injection from multiple gates, e.g. to avoid weld lines
• CPC Class Codes: B29C 45/0025 Preventing defects on the moulded article, e.g. weld lines, shrinkage marks preventing defects on the preformed parts or layers B29C45/14836

Abstract

Process and device for injection molding plastics. The injection material charge is introduced into the mold to obtain an uninterrupted flow front by initially injecting the material into the mold through at least one first gate and through a subsequent gate or gates only after the flow front passes the subsequent gate(s). An injection molding device having separately and variously controllable valves located in the supply lines interconnecting an injection molding apparatus, mold and gates.

Claims

1. A process for the injection-molding of plastic material consisting essentially in:

initially introducing the material charge into a mold having a plurality of entry gates through less than all of said gates, and subsequently introducing the material through at least one additional entry gate only after said flow front has passed said additional gate.

2. Process according to claim 1, wherein said introduction through said first gate is continued until all of said charge is introduced into said mold.

3. Process according to claim 1, wherein said injection through said first gate is stopped after the said flow front has passed at least one subsequent gate.

4. Process according to any of claims 1, 2 or 3, wherein more than one gate is used for said initial introduction.