Tom C Bly

US Patent:

47097574, Dec 1, 1987

Filed:

Nov 24, 1986

Appl. No.:

6/934437

Inventors:

Tom C. Bly - Erie PA

Assignee:

Johnson Service Company - Milwaukee WI

International Classification:

F28F 900
B29C 4544

US Classification:

165173

Abstract:

A process for forming a plastic part having a tubular portion that is continuous and without any flash/mismatch due to mold parting lines in which an injection mold is provided having a cavity formed with a cylindrical surface portion and a core member removably inserted endwise into the cylindrical portion. A molten plastic material is injected into the cavity so that it extends into the cylindrical portion and around the core member. The core member is then withdrawn in an axial direction from the cylindrical portion after the plastic material therein has solidified enough to retain its tubular shape but before it has completely cooled to thereby enable the plastic material to shrink radially inwardly away from the cylindrical surface. Thereafter, the molded tubular shape and the cylindrical mold surface are moved relative to each other in an axial direction so that they are moved away from each other and the tubular portion is withdrawn from the mold, with the tubular portion yielding or flexing to whatever extent is necessary in order to clear the mold.