| 摘要 |
<p>PURPOSE:To make a screwdown speed constant regardless of variations in loading pressure by detecting a loading pressure of a hydraulic cylinder devided into a main pressure oil room and a back pressure oil room and a screwdown direction and supplying oil having a pressure corresponding to a detected value to the back pressure room. CONSTITUTION:Pressure reducing valves 22 and 23 are parallel connected with a pressure oil line 19 having a pressure of PO from a hydraulic pump. Pressure oils of PL and PH obtained by the valves 22 and 23 are inputted into a solenoid selector valve 26 through pressure oil lines 24 and 25. The selector valve 26 is switched by a discrimination circuit 27 to select the oil in the lower pressure side of PL when a loading pressure PL becomes larger because a rolled stock is bitted by working rolls and to select the oil in the higher pressure side of PH when the loading pressure PL becomes smaller. The valve 26 selects the pressure oil of the pressure PH in high pressure side and controls so that a screwdown speed is increased when the screwdown direction of a setup is the opening direction concerning operation of a roll gap for the succeeding rolled stock after the present rolling. On the other hand, the valve 26 selects the pressure oil of the pressure PL of low pressure side and controls so that a screwdown speed is increased when the screwdown direction of the setup is the closing direction.</p> |
