Hydraulic drives system for a press
AssigneeMannesmann Rexroth GmbH
InventorStefan Schmidt
Life of this patent
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Abstract
The invention relates to a drive system for a hydraulic press. The drive system is of the type of secondary controlled system maintaining an impressed pressure of substantially constant magnitude in a pressure system. A hydraulic transformer comprises a pair of mechanically coupled hydrostatic machines each having a variably capacity. The first machine is connected to the pressure system and the second machine to the press cylinder. The invention provides a drive system in which biasing the press cylinder, rapid tranverse and pressing stroke, decompressing the fluid and flushing of hot fluid is accomplished in a closed loop free of throttling losses. The hydraulic transformer further allows to recover energy to the pressure system.
Claims12
A hydraulic drive system for a press, comprising a hydrostatic machine operating as a pump when being driven to maintain an impressed pressure of substantially constant magnitude in a fluid system including a hydraulic accumulator, further comprising a hydraulic transformer including a first hydrostatic machine of variable capacity and operating either as the motor or as a pump which first hydrostatic machine is connected to the fluid system, and a second hydrostatic machine of variable capacity and operating as a motor or as a pump which second hydrostatic machine is mechanically connected to said first machine, and a press cylinder including a pair of cylinder chambers which are hydraulically connected to both hydraulic ports of said second hydrostatic machine, characterized in that said fluid system (3,4) is hydraulically connected to both cylinder chambers (17,18) of the press cylinder (16) to subject both cylinder chambers to a biasing pressure corresponding to the pressure prevailing in said fluid system of substantially constant pressure.
Dependencies are inferred from the claim text.