Patent attributes
A load determining device for an electrically-operated injection molding machine in which a load exerted on a movable part is detected based on the motor current or by an observer, with removing the influence of motor temperature. Upon start of continuous molding, a maximum load detected during retreat motion of an ejector or movable part is stored as a reference value Lr0. In every molding cycle, a maximum detected load Lra during the retraction of the ejector is determined. In the next molding cycle, load La detected during advance of the ejector is corrected based on the reference value Lr0 and the maximum detected load Lra to eliminate the influence of motor temperature rise, thereby determining the load Lfx(n) during the advance of the ejector. When there occurs a change in temperature of the ejector driving motor, the load detected based on the motor current or by the observer varies even if the actual ejector load is constant. By eliminating the influence of temperature change, the load can accurately be detected.
