Injection molding control method for an injection molding machine

• US 5,906,777 A
• Filed: 11/22/1995
• Issued: 05/25/1999
• Est. Priority Date: 03/24/1994
• Status: Expired due to Fees

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Uchiyama, Tatsuhiro, Hosoya, Yuichi, Kamiguchi, Masao
• Primary Examiner(s): HEITBRINK, TIMOTHY W
• Application Number:
  US08/553,420
• Time in Patent Office: 1,280 Days
• Field of Search: 425/149, 425/150, 425/152, 264/328.7, 264/40.7, 264/40.1
• US Class Current: 264/40.1
• CPC Class Codes: B29C 45/70 Means for plasticising or homogenising the moulding material or forcing it into the mould, combined with mould opening, closing or clamping devices
• CPC Class Codes: B29C 45/762 the sequence of operations of an injection cycle
• CPC Class Codes: B29C 45/7653 mould clamping forces
• CPC Class Codes: B29C 45/80 of relative position of mould parts

Abstract

Clamping and injection operations are executed partially in parallel by adjusting a clamping speed and an injection start timing T so that sum ΣP of resin pressure acting on the parting plane of a mold cavity will not exceed mold clamping force F outputted at that time. An injection operation is started during the period in which the mold clamping force F is relatively low between mold touch and mold clamping completion, so that gas breathing from the mold cavity can be done easily without providing gas vent in the mold, thereby preventing resin filling failure or burning. Also, the clamping and injection operations are executed partially in parallel, so that time required for clamping and injection processes is shortened by time T'"'"' as a whole. Therefore, speeding of molding cycle can be attained.

Claims

1. An injection molding control method for an injection molding machine, wherein injection of resin into a cavity is started prior to completing a mold clamping operation and the mold clamping operation and injection operation are executed with injection start timing and mold clamping speed set so that the sum of a resin pressure acting on the parting plane of a mold cavity increases with increasing mold clamping force during the period ranging from mold touch to mold clamping completion in a mold closing process.

2. The injection molding control method according to claim 1, wherein the beginning of injection of the resin into the cavity is determined on the basis of the time elapsed from initial mold touch.

3. The injection molding control method according to claim 1, wherein the beginning of injection of the resin into the cavity is determined on the basis of a position of a movable platen.

4. The injection molding control method according to claim 1, wherein the beginning of injection of the resin into the cavity is determined on the basis of mold positions on a tie bar.

5. An injection molding control method for an injection molding machine, wherein injection of resin into a cavity is started prior to completing a mold clamping operation and the mold clamping operation and injection operation are executed with injection start timing and either injection pressure or injection speed of the resin is set so that the sum of a resin pressure acting on the parting plane of a mold cavity increases with increasing mold clamping force during the period ranging from mold touch to mold clamping completion in a mold closing process.

6. The injection molding control method according to claim 5, wherein the beginning of injection of the resin into the cavity is determined on the basis of the time elapsed from initial mold touch.

7. The injection molding control method according to claim 5, wherein the beginning of injection of the resin into the cavity is determined on the basis of a position of a movable platen.

8. The injection molding control method according to claim 5, wherein the beginning of injection of the resin into the cavity is determined on the basis of mold positions on a tie bar.

9. An injection molding control method for an injection molding machine, wherein injection of resin into a cavity is started prior to completing a mold clamping operation and the mold clamping operation and injection operation are executed with injection start timing, clamping speed and either injection pressure or injection speed of the resin is set so that the sum of a resin pressure acting on the parting plane of a mold cavity increases with increasing mold clamping force during the period ranging from mold touch to mold clamping completion in a mold closing process.

10. The injection molding control method according to claim 9, wherein the beginning of injection of the resin into the cavity is determined on the basis of the time elapsed from initial mold touch.

11. The injection molding control method according to claim 9, wherein the beginning of injection of the resin into the cavity is determined on the basis of a position of a movable platen.

12. The injection molding control method according to claim 9, wherein the beginning of injection of the resin into the cavity is determined on the basis of mold positions on a tie bar.

13. An injection molding control method for an injection molding machine, comprising the steps of:

starting an injection operation prior to completing a mold clamping operation;

displaying a two-axis orthogonal coordinate having a first axis for plotting elapsed time from a mold touch and a second axis for plotting mold clamping force, on a screen of a display device connected to the injection molding machine;

displaying on the coordinates a mold clamping force curve indicating transition of mold clamping force with respect to an elapsed time from a mold touch position where a movable side mold and a stationary side mold start to abut against each other to a mold clamping completion position where a clamping toggle system is locked up, on the basis of related data designated previously by manual input;

displaying on said coordinates a mold opening force curve indicating a mold opening force, which is a resin pressure acting on the parting plane of a mold cavity, corresponding to an elapsed time from a mold touch position to a clamping completion position, calculated based on relating data detected by actually operating a injection molding machine according to preset injection conditions;

judging whether said mold opening force curve shown on said coordinates is lying all the way below said mold clamping force curve throughout the entire section between said mold touch position and said mold clamping completion position;

changing the previous injection molding conditions by taking at least one of the following means (a) through (d) if it is judged that said mold opening force curve is even partially lying above said mold clamping force curve on said coordinate;

operating injection molding machine according to the changed injection molding conditions again;

setting said changed injection molding conditions to a control device if it is confirmed that said mold opening force curve is lying below said mold clamping force curve throughout the entire section between said mold touch position and said mold clamping completion position on said coordinate; and

again changing said injection molding conditions and repeating the same operation as described above if the mold opening force curve is not lying in the fashion described above,

said means comprising;

(a) adjusting injection start timing with respect to molds touch;

(b) adjusting mold clamping speed;

(c) adjusting time required from the injection start to resin filling completion; and

(d) increasing resin injection pressure in the initial injection stage with increasing clamping force between the movable side mold and the stationary side mold.

14. An injection molding control method for an injection molding machine having first and second mold portions which come together and separate at a parting plane of a mold cavity, comprising the steps of:

starting resin injection while the first and second mold portions are being clamped together in a clamping operation, after the first and second mold portions make initial contact with one another;

setting at least one parameter selected from the group consisting of the time at which resin injection is started, the speed at which the first and second mold portions are clamped together, the pressure at which the resin is injected into the mold and the speed at which the resin is injected into the mold, the at least one parameter being set so that a resin pressure acting on the parting plane of the mold cavity increases with increasing clamping force between the first and second mold portions.