Injection-molding machine for synthetic plastic material

US4120631A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Volkmar Leutner · Friolzheim, DE
• Roman Romes · Friolzheim, DE

Key dates

• Filing date: Mar 8, 1976
• Grant date: Oct 17, 1978
• Expiry date: Mar 8, 1996

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B29C45/77
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

The injection-molding machine is operative when activated for performing a complete injection-molding cycle. The machine includes a mold defining a mold cavity, a plastifying and injecting screw, and an hydraulic cylinder-and-piston unit for driving the screw. During the course of a single injection-molding cycle, negative-feedback control of the pressure in the mold cavity undergoes an automatic transition into negative-feedback control of the pressure in the hydraulic cylinder of the cylinder-and-piston unit. The transition is selected to be abrupt or gradual, and if gradual there will be a transitional interval during which a composite negative-feedback control of both the mold cavity and hydraulic cylinder pressures is occurring.