Control system and a control method for injection molding machines

Abstract

A control system for injection molding machines comprises a memory means (16) for storing set values. Further, a signal input for the transmission of actual values to the control system is provided. A first control means (18) is used for the transmission of a control field with consideration to previous values. A second control means (20) is provided for the transmission of a correction value, in particular with consideration to a deviation of the actual value from the set value. A correlation means (22) serves to correlate the control field values with the correction value for outputting a control variable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The following is a detailed description of a preferred embodiment of the present invention with reference to the accompanying drawings.

In the Figures:

FIG. 1 is a schematic diagram of speed plotted against time when using a PID controller of the prior art,

FIG. 2 is a functional diagram of a control system according to the present invention, and

FIG. 3 is a schematic diagram of time plotted against speed when using the control system of the present invention.

Claims

1. A control system for injection molding machines, especially for speed and/or position control, comprising a memory means (16) for storing set values,a signal input for the transmission of actual values to the control system,a first control means (18) for the transmission of a control field with consideration to previous values,a second control means (20) for the transmission of a correction value, anda correlation means (22) for the correlation of the control field values with the correction value for outputting a control variable.

2. The control system of claim 1, wherein the first control means (18) considers control field values, set values and/or actual values of a previous cycle when determining a current control field.

3. The control system of claim 2, wherein, when determining a current control field, the first control means (18) considers a difference between set and actual values caused by a previous control field.

4. The control system of claim 1, wherein the first control means (18) comprises an ILR controller.

5. The control system of claim 1, wherein the second control means (20) determines the correction value with consideration to a current difference between set and actual values.

6. The control system of claim 1, wherein the second control means (20) comprises a PID controller.

7. The control system of claim 1, wherein the second control means (20) transmits a correction value only when a threshold value is overshot/undershot.

8. The control system of claim 1, wherein the correlation means (22) prefers a correction value over the control field value.

9. The control system of claim 1, wherein the memory means (16) is connected with a control means for determining the set values.

10. The control system of claim 9, wherein the control means comprises a FPGA.

11. A control method for an injection molding machine, wherein set values and actual values are determined,a control field is determined with consideration to previous values,a correction value is determined, andthe control field value is correlated with the correction value for outputting a control variable.

12. The control method of claim 11, wherein the current control field is determined with consideration to a difference between set and actual values caused by a previous control field.

13. The control method of claim 11, wherein a correction value is determined with consideration to a current difference between set and actual values.

14. The control method of claim 11, wherein the correction value is determined only after a threshold value has been overshot/undershot.

15. The control method of claim 11, wherein the correction value is preferred upon correlation of the control field values with the correction value.