Hydraulic control device for the press cylinder pressure control method and a press cylinder

摘要

PROBLEM TO BE SOLVED: To keep holding pressure of a press cylinder while preventing over-shoot.SOLUTION: After pressure P2 in an extrusion side pressure chamber 3b reaches holding pressure, a secondary pressure detection sensor 10 detects that the pressure P2 in the extrusion side pressure chamber 3b reaches lower limit pressure lower than the holding pressure. Then, a hydraulic pump 5 is driven until pressure P1 of a primary pressure detection sensor 9 reaches lower limit pressure. Thereafter, the hydraulic pump 5 is driven until the hydraulic pressure P1 of the primary pressure detection sensor 9 reaches the holding pressure again.