Injection molding control method for an injection molding machine

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.