Patent ID: 7713049
Filing Date: 2010-05-11
Classification: B29C

Abstract:
1. An injection molding machine comprising: a screw equipped with a check ring; a torque detecting means for detecting torque acting on the screw during forward movement of the screw; a check ring closure state determining means for determining whether the check ring is closed or not on the basis of the torque detected by said torque detecting means; and a screw reverse rotation control means for controlling reverse rotation of the screw on the basis of the determination by said check ring closure state determining means, wherein the check ring closure state determining means is configured to compare the torque during forward movement of the screw with a first reference value, to determine that the check ring is not closed when the torque is greater than the first reference value, and to determine that the check ring is closed when the torque is less than or equal to the first reference value.