CONTROL DEVICE AND CONTROL METHOD FOR INJECTION MOLDING MACHINE
First Claim
1. A control device for an injection molding machine that injects a melted resin filled in a barrel into a cavity of a mold by driving a motor to move forward a screw in the barrel, wherein the control device, which is provided in the injection molding machine, generates a current command for driving the motor based on operation information of the motor and a pressure detection value of the melted resin, the control device comprising:
- a pressure controller that calculates a speed command by performing a transfer characteristic computation including a computation element that applies at least a proportional gain on a deviation between a predetermined pressure command and the pressure detection value;
a speed controller that calculates the current command such that a speed of the motor follows a speed command calculated by the pressure controller;
a pressure-keeping-operation determining unit that determines whether the injection molding machine is performing a pressure keeping operation;
an elastic constant identifier that acquires, when the pressure-keeping-operation determining unit determines that the pressure keeping operation is in progress, the pressure detection value and the operation information of the motor and identifies an elastic constant that is a proportion of a change of the pressure detection value with respect to a displacement of a position of the motor based on the acquired pressure detection value and the operation information of the motor; and
a control-parameter setting unit that calculates the proportional gain of the pressure controller such that a product of the proportional gain of the pressure controller and the elastic constant identified by the elastic constant identifier is smaller than a speed control bandwidth of the speed controller, and sets the calculated proportional gain to the pressure controller.
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Accused Products
Abstract
To execute a stable pressure control, in a control device for an injection molding machine, a filling/pressure-keeping determining unit determines whether the injection molding machine is performing a pressure keeping operation, an elastic constant identifier acquires, when the filling/pressure-keeping determining unit determines that the pressure keeping operation is in progress, a pressure detection value and a position detection value as operation information of a motor and identifies an elastic constant K based on the acquired pressure detection value and the position detection value, and a pressure-control control-parameter setting unit calculates a proportional gain Ka of a pressure controller such that a product of the proportional gain Ka of the pressure controller and the elastic constant K is smaller than a speed control bandwidth ωsc of a speed controller, and sets the calculated proportional gain Ka to the pressure controller.
7 Citations
12 Claims
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1. A control device for an injection molding machine that injects a melted resin filled in a barrel into a cavity of a mold by driving a motor to move forward a screw in the barrel, wherein the control device, which is provided in the injection molding machine, generates a current command for driving the motor based on operation information of the motor and a pressure detection value of the melted resin, the control device comprising:
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a pressure controller that calculates a speed command by performing a transfer characteristic computation including a computation element that applies at least a proportional gain on a deviation between a predetermined pressure command and the pressure detection value; a speed controller that calculates the current command such that a speed of the motor follows a speed command calculated by the pressure controller; a pressure-keeping-operation determining unit that determines whether the injection molding machine is performing a pressure keeping operation; an elastic constant identifier that acquires, when the pressure-keeping-operation determining unit determines that the pressure keeping operation is in progress, the pressure detection value and the operation information of the motor and identifies an elastic constant that is a proportion of a change of the pressure detection value with respect to a displacement of a position of the motor based on the acquired pressure detection value and the operation information of the motor; and a control-parameter setting unit that calculates the proportional gain of the pressure controller such that a product of the proportional gain of the pressure controller and the elastic constant identified by the elastic constant identifier is smaller than a speed control bandwidth of the speed controller, and sets the calculated proportional gain to the pressure controller. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A control method for an injection molding machine that injects a melted resin filled in a barrel into a cavity of a mold by driving a motor to move forward a screw in the barrel, the control method being implemented by a control device included in the injection molding machine, the control device calculating a speed command by performing a transfer characteristic computation including a computation element that applies at least a proportional gain on a deviation between a predetermined pressure command and a pressure detection value of the melted resin and calculating a current command for driving the motor such that a speed of the motor follows the calculated speed command, the control method comprising:
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a pressure-keeping operation determining step of determining whether or not the injection molding machine is performing a pressure keeping operation; an elastic constant identifying step including, when it is determined that the injection molding machine is performing the pressure keeping operation, acquiring the pressure detection value and the operation information of the motor and identifying an elastic constant that is a proportion of a change of the pressure detection value with respect to a displacement of a position of the motor based on the acquired pressure detection value and operation information of the motor; and a control parameter setting step including calculating the proportional gain such that a product of the proportional gain and the elastic constant identified at the elastic constant identifying step is smaller than a speed control bandwidth of the speed controller and setting the calculated proportional gain to a proportional gain for calculating the speed command.
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Specification