Patent ID: 11872620
Assignee: AMADA CO., LTD.
Field: Machine tools (Mechanical engineering)
Classification: CPC B | IPC B

Claim 0:
1. A press brake, comprising:
a hydraulic cylinder configured to move an upper table and a lower table relative to each other in a vertical direction;
a control unit configured to control a hydraulic circuit of the hydraulic cylinder; and
a position detector configured to detect position information in a moving direction of either one of the upper table and the lower table, the one moving relative to the other in a vertical direction, wherein
the control unit has an abnormality determination threshold value for detecting an abnormality that has actually occurred and a predictor determination threshold value that is a value lower than the abnormality determination threshold value,
the control unit is configured to compare a speed of self-weight movement per unit time calculated based on the position information from the position detector with the predictor determination threshold value and the abnormality determination threshold value while the one of the upper table and the lower table, the one moving relative to the other in a vertical direction, stops operation,
when the control unit determines that the speed of self-weight movement exceeds the predictor determination threshold value and is below the abnormality determination threshold value, the control unit is configured to determines a predictor of an occurrence of an abnormality in the hydraulic circuit including a first pressure control valve configured to control a back pressure of hydraulic oil on a back pressure side port side of the hydraulic cylinder, and
when the control unit determines that the speed of self-weight movement exceeds the abnormality determination threshold value, the control unit is configured to determine that the abnormality occurs in the hydraulic circuit.