Methods of moulding of plastics articles

• US 4,490,315 A
• Filed: 10/31/1983
• Issued: 12/25/1984
• Est. Priority Date: 02/04/1982
• Status: Expired due to Fees

• Current Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Huszarik, Fred A., Charlebois, Leonard J.
• Primary Examiner(s): Woo, Jay H.
• Assistant Examiner(s): Housel, James C.
• Application Number:
  US06/547,422
• Time in Patent Office: 421 Days
• Field of Search: 264/40.1, 264/40.2, 264/272.11, 264/276, 264/328.12, 264/328.9, 425/146, 425/149
• US Class Current: 264/40.1
• CPC Class Codes: B29C 45/14 incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles B29C45/1671 takes precedence
• CPC Class Codes: B29C 45/7613 the termination of flow of material into the mould
• CPC Class Codes: B29C 70/72 Encapsulating inserts having non-encapsulated projections, e.g. extremities or terminal portions of electrical components B29C70/742 takes precedence

Abstract

A method of moulding by low pressure moulding wherein a passage from the mould cavity is bridged by the molten material during filling and in which the moulding pressure is too low to cause the material to flow down the passage. After the mould is completely filled, the pressure increases to cause penetration of the molten material along the passage to a switch operating position to operate a switch to stop further flow of material into the mould.

Claims

1. A method of moulding an article in the form of an encapsulation around an object which is deformable or crushable under a certain compressive load, comprising causing molten plastics material to flow at a low pressure into a mould cavity containing the object and, during filling, causing the material to extend across and bridge an open passage extending from the cavity and permitting the commencement of formation of a skin on the material bridging the passage, said skin being thinner than skin contacting surfaces of the mould, and filling the cavity to effect an increase in pressure in the molten material, which pressure is below that required to deform or crush the object but is sufficient to cause rupture of said thinner skin and to force a flow of the molten material along the passage to a switch operating location and operate a switch to cease futher flow of material into the mould.