Method of controlling hydraulic press

• US 5,071,603 A
• Filed: 12/13/1988
• Issued: 12/10/1991
• Est. Priority Date: 12/14/1987
• Status: Expired due to Fees

• Current Assignee: Klaus Schmidt
• Original Assignee: Klaus Schmidt
• Inventors: Imanishi, Etujiro, Nakagawa, Noriharu, Ueda, Hiroshi, Fukuda, Yoshihiro, Takeuchi, Naoki, Kondo, Hiroaki, Kurumaji, Masanobu, Kajiyama, Kazuyuki, Sano, Tutomu
• Primary Examiner(s): Heitbrink, Jill L.
• Application Number:
  US07/283,925
• Time in Patent Office: 1,092 Days
• Field of Search: 264/40.1, 264/40.5, 264/40.7, 264/328.7, 425/149, 425/150
• US Class Current: 264/40.5
• CPC Class Codes: B29C 2043/5808 pressure or compressing force
• CPC Class Codes: B29C 43/58 Measuring, controlling or regulating for bank adjustment in calendering B29C43/245
• CPC Class Codes: B30B 15/20 controlling the speed of the ram, e.g. the speed of the approach, pressing or return strokes
• CPC Class Codes: B30B 15/22 controlling the degree of pressure applied by the ram during the pressing stroke
• CPC Class Codes: B30B 15/26 Programme control arrangements

Abstract

A method of controlling a hydraulic press wherein changing over from velocity control to pressure control can be effected at an optimum point of time in accordance with a condition of material being filled. When a movable mold half of a metal mold is moved by a hydraulic cylinder to compression mold a work within a cavity defined in the metal mold, the velocity of movement of the mold half by the hydraulic cylinder is controlled until pressurization of the work is started, but after starting of the pressurization, the pressurizing force of the hydraulic cylinder is controlled. During the velocity control, a parameter which varies as the compression proceeds is successively detected during the velocity control, and changing over from the velocity control to the pressure control is effected at a point of time when the detected parameter coincides with a preset value--that is, when the work is fully filled in the cavity. A device for controlling a hydraulic press is also disclosed wherein optimal pressure control can be assured in accordance with a current condition of material for molding.

Claims

1. In a method of controlling a hydraulic press wherein, when at least one of a pair of metal mold halves is moved by a hydraulic cylinder to compression mold a work within a cavity defined between said metal mold halves, the velocity of movement of said at least one metal mold half by said hydraulic cylinder toward the work is controlled until pressurization of the work is started, but after starting of the pressurization, the pressurizing force of said hydraulic cylinder is controlled, the improvement wherein:

(a) a position of a movable member which is moved by said hydraulic cylinder is successively detected during the velocity control, and

(b) changing over from the velocity control to the pressure control is effected at a point of time when the detected position of said movable member coincides with a preset value.

2. In a method of controlling a hydraulic press wherein, when at least one of a pair of metal mold halves is moved by a hydraulic cylinder to compression mold a work within a cavity defined between said metal mold halves, the velocity of movement of the metal mold half by said hydraulic cylinder is controlled until pressurization of the work is started, but after starting of the pressurization, the pressurizing force of said hydraulic cylinder is controlled, the improvement wherein changing over from the velocity control to the pressure control is effected at a point of time when said hydraulic cylinder is moved to a position of a predetermined stroke value Z₀ and an internal pressure P of said cavity is detected upon such changing over and is compared with a predetermined preset internal pressure P₀ to obtain a stroke modifying amount VZ for modifying the internal pressure P of said cavity to the predetermined internal pressure P₀ in accordance with an equation