JPS57134202A - Hydraulic circuit - Google Patents

Abstract

PURPOSE:To reduce the time for exchanging of rolls considerably by keeping the remaining quantity discharged by a pump for giving rolling force of hydraulically loaded rolling mills or the like accumulated via a sequence valve on a branch circuit. CONSTITUTION:The oil pressure supplied with a pump 11 controls the rolling forces of work rolls 3 via a valve 54, a pipeline 73, a servo valve 8, a cylinder 4, and a reinforcing rolls 2. On the other hand, a sequence valve 5 is so designed that the excess oil pressure is supplied to a pipeline 77 when the required max. pressure is attained in the pipeline 73, and the pressure is accumulated by this in an accumulator 52. In the stage of exchanging the work rolls, the valve 8 is set at center valve position upon stopping of rolling, and pipelines 82, 83 are interrupted by a selector valve 63, then pipelines 81, 91 are conducted by a selector valve 60 so that valves 57, 58 are opened by the oil pressure and the oil pressure in a cylinder oil chamber 6 is released. The oil pressure in the accumulator 52 is supplied through pipelines 78, 83 into an oil chamber 7, whereby the time T1 is reduced considerably. The accumulator 52 restores high pressure in the time T2 because an accumulator 9 is high in pressure and the volume of the chamber 7 is small. This high pressure is similarly utilized for raising of the roll 2, whereby the time T3 is reduced considerably.