Method of controlling injection molding machine

• US 20060022363A1
• Filed: 10/03/2005
• Published: 02/02/2006
• Est. Priority Date: 04/07/2003
• Status: Abandoned Application

• Current Assignee: Sumitomo Heavy Industries Limited
• Original Assignee: Sumitomo Heavy Industries Limited
• Inventors: Konno, Takeshi, Amano, Mitsuaki, Sato, Hiroshi
• Application Number:
  US11/240,372
• Publication Number:
  US 20060022363A1
• Time in Patent Office: Days
• US Class Current: 264/40.100
• CPC Class Codes: B29C 2945/76006 Pressure
• CPC Class Codes: B29C 2945/76113 linear movement
• CPC Class Codes: B29C 2945/76187 screw
• CPC Class Codes: B29C 2945/76404 injection-holding
• CPC Class Codes: B29C 2945/76498 Pressure
• CPC Class Codes: B29C 2945/76602 derivative, change thereof
• CPC Class Codes: B29C 2945/76665 screw
• CPC Class Codes: B29C 2945/76859 Injection
• CPC Class Codes: B29C 2945/76933 The operating conditions are corrected immediately, during the same phase or cycle
• CPC Class Codes: B29C 2945/76943 compare with thresholds
• CPC Class Codes: B29C 2945/76986 Interpolating
• CPC Class Codes: B29C 45/77 of velocity or pressure of moulding material

Abstract

An injection pressure of an injection molding machine is controlled by a movement of a screw. The injection pressure is detected when the screw is moved forward and rearward in an injection process. A rising injection pressure ΔP is predicted in a case where the screw is stopped at a previously set deceleration of the screw from the time of detection of the injection pressure. The predicted rising injection pressure ΔP and a previously set pressure P are compared, and the screw is decelerated at a previously set deceleration based on the comparison result.

Claims

1. A control method of an injection machine to control an injection pressure by a movement of a screw, comprising:

detecting the injection pressure generated when said screw moves forward in an injection process;

predicting a rising injection pressure Δ

P when decelerating the screw at a previously set deceleration of the screw from a time of detection of the injection pressure;

comparing the predicted rising injection pressure Δ

P and a previously set pressure P with each other; and

decelerating said screw at a previously set deceleration based on a result of the comparison.

2. The control method as claimed in claim 1, wherein the prediction of said rising injection pressure Δ

P is performed based on an arithmetic expression represented by Δ

P=dP·

(V0/k), where dP is an injection pressure change in a unit time, V0 is a forward moving velocity of the screw and k is a coefficient.

3. The control method as claimed in claim 2, wherein a coefficient k, which is a constant part of said arithmetic expression, is calculated back as an ideal coefficient kmodel by plugging various kinds of performance result values obtained by at least one shot into said arithmetic expression so as to perform molding by reflecting said ideal coefficient kmodel in subsequent molding.

4. The control method as claimed in claim 3, wherein:

a pressure, which is a sum of a rising pressure after prediction and a predicted delay pressure, is used as said rising injection pressure Δ

P in the back calculation of said coefficient k;

said rising pressure after prediction is given as a value (Pmax−

Pfb1), which is calculated by subtracting an injection pressure Pfb1 at a time when a value of a sum of said rising pressure after prediction and said predicted delay pressure is determined as not coincide with a maximum injection pressure from the maximum injection pressure Pmax obtained in the molding of said one shot; and

said predicted delay pressure is given as a value (Pfb1+Δ

P−

Pref), which is calculated by adding to the injection pressure Pfb1 at a time when said discrepancy is determined the rising injection pressure Δ

P at that time, and subtracting said setting pressure Pref from the added value.

5. The control method as claimed in claim 2, wherein a value of said coefficient k at a time when actual molding is performed and an operator determines that a molded component is a nondefective good is used as the ideal coefficient kmodel.

6. The control method as claimed in claim 2, wherein said coefficient k is 2·

dV, where dV is said previously set deceleration.

7. The control method as claimed in claim 6, wherein said previously set deceleration is corrected by using said coefficient k obtained from a performance value obtained by molding of at least one shot.

8. The control method as claimed in claim 6, wherein a time of starting deceleration is corrected by using said coefficient k obtained from a performance value obtained by molding of at least one shot.

9. The control method as claimed in claim 6, wherein:

a pressure, which is a sum of a rising pressure after prediction and a predicted delay pressure, is used as said rising injection pressure Δ

P in the back calculation of said coefficient k;

said rising pressure after prediction is given as a value (Pmax−

Pfb1), which is calculated by subtracting an injection pressure Pfb1 at a time when a value of a sum of said rising pressure after prediction and said predicted delay pressure is determined as not coincide with a maximum injection pressure from the maximum injection pressure Pmax obtained in the molding of said one shot; and

said predicted delay pressure is given as a value (Pfb1+Δ

P−

Pref), which is calculated by adding the rising injection pressure Δ

P at a time when said discrepancy is determined, to the injection pressure Pfb1 at that time, and subtracting said setting pressure Pref from the added value.

10. The control method as claimed in claim 6, wherein said coefficient k is obtained by using a pressure detected when determined as exceeding said previously set pressure P.

11. The control method as claimed in claim 2, wherein an average value of a plurality of back calculation values of the coefficient k obtained by performing a plurality of shots of test molding is used as said coefficient kmodel.

12. The control method as claimed in claim 2, wherein said plurality of shots of test molding are performed while reflecting a back calculation value of said coefficient k obtained by a preceding shot.

13. The control method as claimed in claim 2, wherein a moving average value of a plurality of back calculation values of the coefficient k corresponding to a plurality of shots equal to said plurality of shots is calculated as said coefficient kmodel even in actual molding.

14. The control method as claimed in claim 1, wherein the prediction of said rising injection pressure Δ

P and said determination are repeated at an arbitrary time interval.

15. The control method as claimed in claim 1, wherein said previously set deceleration is corrected by using a performance value obtained by molding of at least one shot.

16. The control method as claimed in claim 1, wherein a time of starting deceleration is corrected by using a performance value obtained by molding of at least one shot.

17. The control method as claimed in claim 1, wherein a difference between a maximum injection pressure detected by molding of at least one shoe and said previously set pressure P is obtained, and said previously set pressure P is corrected by using the obtained difference.