| 摘要 |
PURPOSE:To perform highly accurate injection control by transferring from injection speed control to injection pressure control without being influenced by the inertia force of the rotor of a motor by a method wherein the speed control of an injection plunger or injection screw is performed by detecting the injection pressure. CONSTITUTION:The reaction developed by the advancement of a screw 1 for injection is detected in the amount of the deformation of the rear wall 4a of a housing with a strain gage 21 set at the rear end part of a shaft 11, which is journaled to the rear wall, in an electrically operated injection unit to inject molten resin by rotating the screw 1 by means of a servo-motor 19 as a driving source. The detected value is regarded as the injection force and compared with the set value at a comparator 25. When the detected value is larger than the set value, a signal switch 27 is changed over to an injection pressure signal DELTAV4 side, resulting in transferring from speed control to pressure control. In addition, the difference signal DELTAV4 between the pressure signal V5 corresponding to said detected value and the expected set pressure signal V4 is employed as the basic speed instruction signal of the servo-motor 19. |
