Injection molding machine having function for monitoring screw rotating torques

An injection molding machine having a function for monitoring screw rotating torques, comprising:

• measuring means for measuring screw rotation speeds and screw rotating torques at predetermined time or distance intervals as the screw moves for metering;
• storage means for storing the screw rotation speeds and screw rotating torques measured by the measuring means;
• determining means for determining a maximum screw rotating torque at each screw rotation speed by substituting the screw rotation speeds and screw rotating torques stored in the storage means into a previously-assumed function;
• allowable upper limit setting means for setting an allowable upper limit of screw rotating torque for each screw rotation speed on the basis of the maximum screw rotating torque determined by the determining means;
• and
• limiting means for limiting a driving torque applied to the screw to the allowable upper limit set by the allowable upper limit setting means.

An injection molding machine having a function for monitoring screw rotating torques, comprising:

• measuring means for measuring screw rotation speeds and screw rotating torques at predetermined time or distance intervals as the screw moves for metering;
• storage means for storing the screw rotation speeds and screw rotating torques measured by the measuring means for a predetermined number of molding cycles;
• approximate expression determining means for determining an approximate expression that represents a relationship between a maximum screw rotating torque and a screw rotation speed at the maximum screw rotating torque by substituting the screw rotation speeds and screw rotating torques stored in the storage means to a previously-assumed function;
• allowable upper limit setting means for setting an allowable upper limit of screw rotating torque by substituting the screw rotation speed to the approximate expression determined by the approximate expression determining means;
• and
• screw rotation stopping/changing means for stopping or changing screw rotation when a screw rotating torque exceeding the allowable upper limit is detected during metering after the allowable upper limit is set.

An injection molding machine having a function for monitoring screw rotating torques, comprising:

• measuring means for measuring screw rotation speeds and screw rotating torques at predetermined time or distance intervals as the screw moves for metering;
• storage means for storing the screw rotation speeds and screw rotating torques measured by the measuring means for a predetermined number of molding cycles;
• approximate expression determining means for determining an approximate expression that represents a relationship between a maximum screw rotating torque and a screw rotation speed at the maximum screw rotating torque by substituting the screw rotation speeds and screw rotating torques stored in the storage means to a previously-assumed function;
• allowable upper limit setting means for setting an allowable upper limit of screw rotating torque by substituting the screw rotation speed to the approximate expression determined by the approximate expression determining means;
• and
• limiting means for limiting a driving torque applied to the screw to the allowable upper limit set by the allowable upper limit setting means.