Method and equipment for injection compression molding

Abstract

Abstract PURPOSE:To mold continuously a molded product of excellent accuracy by applying dwell evenly to the whole surface of a cavity and making a shrinkage quantity constant, by a method wherein a closed loop is controlled by adjusting an injection mechanism so that a mold inner pressure is increased gradually up to a target value of the mold inner pressure at the time of filling according to a pattern of a function established beforehand. CONSTITUTION:In a pressurizing process, closed loop control is performed through a comparator 31, a contact point 32b, a control instrument 33, an amplifier 34 and a servo valve 36 so that a pressure turns into a low mold clamping pressure established beforehand through instructions of an instruction instrument 30 for a mold clamping pressure by closing a mold 1. In the next filling process, the closed loop control is performed by a adjusting a quantity of oil to be supplied to an injection cylinder 12 so that inner pressure Pm turns to a pattern wherein the same increases gradually within a period of time until the arrival of the pressure to the target value of the mood inner pressure at the time of the filling from a starting pressure for control established beforehand through instructions of an instruction instrument 15 of a mold inner pressure. In a dwell process, the closed loop control is performed during a dwell time by adjusting the mold clamping force so as to hold a dwell target value the mood inner pressure similar to that in a compression process. A quantity of molten resin with which a cavity is filled can be made constant by controlling the mold inner pressure so that the same coincides with the pattern established beforehand, in the filling process.

Inventors

• 👤 Koji Kubota
• 👤 浩司 久保田
• 👤 Hiroshi Asai
• 👤 浅井　博

Bibliographic Details