Control method

Abstract

For example, to provide a control method that allows molding to continue and obtain a good molded product even if the holding time in the holding pressure process is extended. [Solution] The control method for maintaining thrust in a ball screw driven by an electric motor according to the present invention is: The first control is performed from the start of loading until the first effective load rate in the electric motor reaches a predetermined first load rate, The system includes a second control that controls the electric motor as a second effective load after reaching a first load factor. If we let θ1 be the rate of increase of the first effective load factor, and θ2 be the rate of increase of the second effective load factor, The condition θ1 > θ2 is satisfied. In the second control, preferably, The electric motor is controlled so that a predetermined second high torque and a second low torque with a torque value smaller than the second high torque are alternately applied.

Claims

1. A control method for maintaining thrust in a ball screw driven by an electric motor, A first control from the start of loading until the first effective load rate in the electric motor reaches a predetermined first load rate, The system includes a second control that controls the electric motor to a second effective load ratio after reaching the first load ratio, A control method that satisfies θ1 > θ2, where θ1 is the rate of increase of the first effective load factor and θ2 is the rate of increase of the second effective load factor.

2. In the second control, The electric motor is controlled so that a predetermined second high torque and a second low torque with a torque value smaller than the second high torque are alternately applied. The control method according to claim 1.

3. In the first control, The electric motor is controlled so that a constant torque, the same as the second high torque, is applied. The control method according to claim 2.

4. In the first control, The electric motor is controlled so that a predetermined first high torque and a first low torque with a torque value smaller than the first high torque are alternately switched. The control method according to claim 1.

5. In the second control, The second high torque and the second low torque are such that the load time of the second high torque and the load time of the second low torque are the same, or the load time of the second low torque is longer than the load time of the second high torque. The control method according to claim 2.

6. In the second control, The second high torque has the same torque value as the first high torque in the first control. The second low torque has a torque value smaller than the first low torque in the first control. The control method according to claim 3.

7. In the first control, If the load time for the first high torque and the first low torque is denoted as tα, In the second control, The load time for the second high torque is the same as tα, and the load time for the second low torque is longer than tα. The control method according to claim 2.

8. In the second control, The second high torque value in the second high torque is the same as the first high torque value in the first control. The second low torque value in the second low torque is lower than the first low torque in the first control. The control method according to claim 2.

9. In the second control, The load time for each of the repeated second high torques decreases as the second effective load ratio increases. The control method according to claim 2.

10. The maintenance of the thrust in the ball screw is performed during the holding pressure process of injection molding. In the second control, The ratio of the load time under the second high torque to the load time under the second low torque, or The low torque value obtained by lowering only the second low torque while maintaining the first high torque value is: This is calculated based on the period from the point at which the first load factor is reached until the completion of the predetermined set pressure holding time. The control method according to claim 2.

11. The maintenance of the thrust in the ball screw is performed during the holding pressure process of injection molding. If the set holding pressure time for one cycle of the holding pressure process is ts, the first holding pressure time in the first control is tp, and the second holding pressure time in the second control is (ts - tp), Based on the first load factor, the ratio of the first holding time tp to the second holding time (ts - tp) is determined. The control method according to claim 1.

12. The control of the second high torque and the second low torque in the second control is performed by switching control of the forward speed of the ball screw. The control method according to claim 2.

13. The thrust in the ball screw is applied during the holding pressure process in injection molding, or during the ejection of the molded product from the mold by injection molding. The control method according to claim 1.

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