Patent ID: 6013211
Filing Date: 2000-01-11
Classification: B29C

Abstract:
A method of controlling a clamping force of a mold consisting of a movable mold half fixed to a movable plate and a stationary mold half fixed to a stationary plate, in a mold clamping apparatus including a mold clamping device and a hydraulic device, said mold clamping device having a mold closing chamber and a mold clamping chamber for moving said movable plate toward said stationary plate, and a mold opening chamber for moving said movable plate away from said stationary plate, said mold closing, clamping and opening chambers being independent of each other, said hydraulic device including pumping means, a servo valve and a switch valve, said pumping means initially delivering a pressurized working fluid to said mold closing chamber through said servo valve, to move said movable plate toward said stationary plate for thereby closing said mold, and then delivering said pressurized working fluid to said mold clamping chamber through said switch valve as well as said servo valve, to force said movable mold half against said stationary mold half for thereby clamping said mold, said method comprising the steps of:obtaining a mold clamping force for clamping said mold, on the basis of a sum of a first force based on a pressure in said mold closing chamber and a second force based on a pressure in said mold clamping chamber; andfeedback-controlling said servo valve such that said mold clamping force coincides with a desired value.