Patent ID: 7806675

Claim:
An injection molding machine comprising: an axial driving means for driving a screw or a plunger in an axial direction, a position detecting means for detecting an axial position of the screw or the plunger, and a resin pressure detecting means for detecting resin pressure, the injection molding machine being configured for carrying out suck back control, wherein the injection molding machine further includes: a resin pressure gradient detecting means for detecting a gradient of resin pressure related to a change of the axial position of the screw or the plunger in the suck back control based on a position detection value from the position detecting means and a pressure detection value from the resin pressure detecting means; and a pressure reduction completion determining means for determining a completion of reduction of the resin pressure by comparing an absolute value of the gradient of the resin pressure detected by the resin pressure gradient detecting means with a value set in advance.