Patent ID: 11858190
Assignee: FANUC CORPORATION
Field: Other special machines (Mechanical engineering)
Classification: CPC B | IPC B

Claim 0:
1. An abnormality detection device for an injection molding machine, the abnormality detection device comprising:
a servo CPU;
a driving unit which drives and controls a servo motor based on an instruction from the servo CPU so as to drive a movable part;
a physical quantity detection unit which detects any one of a load applied on the servo motor, a speed of the servo motor, a current flowing in the servo motor, and a position deviation of the servo motor, as a physical quantity; and
first and second storage units which store a physical quantity in such a manner as to associate the physical quantity with the time that has elapsed during the operation of the movable part or the position of the movable part in the operation of the movable part, as a reference physical quantity, wherein
the reference physical quantities which are stored in the first and second storage units, respectively, are sequentially compared with a physical quantity which is currently detected in such a manner that the reference and currently detected physical quantities are associated with the time that has elapsed during the operation of the movable part or the position of the movable part in the operation of the movable part, and thus, first and second physical quantity deviations are found so that an abnormality can be detected in the case where any physical quantity deviation exceeds a threshold value,
the first storage unit is directly readable/writable by the servo CPU,
the second storage unit is not directly readable/writable by the servo CPU, and
the servo CPU outputs an instruction to stop or decelerate the movable part in the case where either a first physical quantity deviation which is a deviation between a reference physical quantity read from the first storage unit and a current physical quantity or a second physical quantity deviation which is a deviation between a reference physical quantity read from the second storage unit and a current physical quantity exceeds a threshold value.