Patent ID: 8651846
Filing Date: 2014-02-18
Classification: B29C

Abstract:
1. An abnormality detection apparatus of an injection molding machine, comprising: a drive unit that drivingly controls a servomotor to drive a moving part; a physical quantity detection unit that detects a load applied to the servomotor or a speed, current or position error of the servomotor, as a physical quantity; a storage unit that stores the detected physical quantity as a reference physical quantity in association with an elapsed time during which the moving part operates or an operating position of the moving part; a physical quantity deviation calculation unit that successively compares the stored reference physical quantity and a current physical quantity with each other in association with the elapsed time during which the moving part operates or the operating position of the moving part, thereby determining a deviation of the physical quantity; an absolute value calculation unit that calculates an absolute value of the determined deviation of the physical quantity; an average calculation unit that calculates an average of the calculated absolute values of deviations of the physical quantities; and a threshold calculation unit that calculates a threshold corresponding to the elapsed time during which the moving part operates or the operating position of the moving part, based on the calculated absolute value of the deviation of the physical quantity, such that the threshold increases as the calculated absolute value of the deviation of the physical quantity increases, wherein abnormality is detected if the threshold calculated by the threshold calculation unit is exceeded by the deviation of the physical quantity determined by the physical quantity deviation calculation unit.