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

Claim 3:
4. 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; and
a control unit configured to control a hydraulic circuit of the hydraulic cylinder, 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 higher than the abnormality determination threshold value,
the hydraulic circuit includes 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,
the control unit is configured to compare a difference in a hydraulic pressure between a hydraulic pressure value of hydraulic oil at an upstream opening of the first pressure control valve and a hydraulic pressure valve of hydraulic oil at a downstream opening of the first pressure control valve 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 difference in the hydraulic pressure has fallen below the predictor determination threshold value and is above 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 the first pressure control valve, and
when the control unit determines that the difference in the hydraulic pressure has fallen below the abnormality determination threshold value, the control unit is configured to determine that the abnormality occurs in the hydraulic circuit.