Method and apparatus for controlling injection molding machines

Claim 2

In a method for controlling an injection molding machine for injecting resin into a metal mold wherein a pressure holding step is controlled in multiple stages by actuating a screw, the improvement comprising the step of switching holding pressures at respective transfer points in accordance with a temperature of said injected resin or said metal mold detected by a temperature sensor provided for said metal mold coinciding with a preset holding pressure transfer point temperature.

Claim 3

Apparatus for controlling an injection molding machine including a metal mold and a screw actuated by an injection cylinder for injecting a molten resin into said metal mold, said control apparatus comprising: a temperature sensor provided for said metal mold; a temperature setter preset with a plurality of holding pressure transfer point temperatures; a comparator which produces a pressure transfer signal when a temperature detected by said temperature sensor coincides with one of said holding pressure transfer point temperatures; a pressure setter preset with holding pressures corresponding to said pressure transfer point temperatures; a pressure controller inputted with said pressure transfer signal and an output signal of said pressure setter; and a pressure control valve which controls a pressure of said injection cylinder in accordance with the output signal one of said holding pressures of said pressure setter when said pressure controller is supplied with said pressure transfer signal.

Claim 4

Apparatus for controlling an injection molding machine including a metal mold and a screw actuated by an injection cylinder for injecting a molten resin into said metal mold, said control apparatus comprising: a temperature sensor provided for said metal mold; a temperature setter preset with a plurality of holding pressure transfer point temperatures; a comparator which produces a pressure transfer signal when a temperature detected by said temperature sensor coincides with one of said holding pressure transfer point temperatures; a pressure setter preset with holding pressures corresponding to said pressure transfer point temperatures; a pressure controller inputted with said pressure transfer signal and an output signal of said pressure setter; and a pressure control valve which controls a pressure of said injection cylinder in accordance with the output signal one of said holding pressures of said pressure setter when said pressure controller is supplied with said pressure transfer signal.