US 6,013,211 AGranted

Method and apparatus for controlling mold clamping force based on detected hydraulic pressures

AssigneeKabushiki Kaisha Meiki Seisakusho

InventorMitsunori Seki

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Abstract

Mold clamping method and apparatus wherein a mold closing chamber of a mold clamping device is supplied with a pressurized fluid delivered from a hydraulic power source through a servo valve, to close a mold, and a mold clamping chamber independent of the mold closing chamber is also supplied with the pressurized fluid through the servo valve and a switch valve opened upon completion of the mold closing action, to thereby clamp the mold, and wherein a controller is provided to obtain a mold clamping force on the basis of a sum of a first force based on a fluid pressure in the mold closing chamber and a second force based on a fluid pressure in the clamping chamber, and feedback-control the servo valve such that the obtained mold clamping force coincides with a desired value.

Claims11

Dependent claims

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;
and
feedback-controlling said servo valve such that said mold clamping force coincides with a desired value.

A mold clamping system for controlling a clamping force of a mold consisting of a movable mold fixed to a movable plate and a stationary mold fixed to a stationary plate, said mold clamping system including a mold clamping apparatus and a control device, said mold clamping apparatus including a mold clamping device and a hydraulic device, said molding clamping device having a mold closing chamber and a mold clamping chamber for moving said movable plate toward said stationary plate, said mold closing and clamping chambers being independent of each other, said hydraulic device including a pumping means, a servo valve and a switch valve, said control device controlling said servo valve and said switch valve such that a pressurized working fluid is initially delivered from said pumping means to said mold closing chamber through said servo valve, to move said movable plate toward said stationary plate for thereby closing said mold, and is then delivered 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, wherein said control device comprises:

a position sensor for detecting a closed position of said mold;
a first pressure sensor for detecting a pressure of the working fluid in said mold closing chamber;
a second pressure sensor for detecting a pressure of the working fluid in said mold clamping chamber;
and
a controller for opening said switch valve, upon detection of said closed position of said mold by said position sensor, to deliver the pressurized working fluid from said pumping means to said mold clamping chamber as well as said mold closing chamber, said controller including clamping force obtaining means for obtaining a mold clamping force for clamping said mold, on the basis of a sum of a first force based on the pressure detected by said first pressure sensor and a second force based on the pressure detected by said second pressure sensor, and servo valve controlling means for feedback-controlling said servo valve such that said mold clamping force coincides with a desired value.

2 more elements

Dependencies are inferred from the claim text.