Patent ID: 7032423

Claim:
A hydraulic circuit for linearly driving a machine-tool slider in both directions, comprising a hydraulic cylinder ( 5 ) whose piston rod ( 4 ) is connected to a slider that travels until a first predetermined position for each pass of one or more passes of working operation of a workpiece to be bent, the hydraulic cylinder having two chambers ( 6 , 7 ) in one of which there is the piston rod ( 4 ), both chambers, in order to be in high and low pressure alternatively, communicating with respective ducts ( 10 , 11 ) of pressurized fluid fed from a reservoir by a pump ( 15 ), ducts ( 10 , 11 ) on which a three-position four-way valve ( 18 ), a check valve ( 12 - 13 ), and in a bypass ( 190 ) between the check valve and the fourway valve, a first throttling valve ( 19 ) operate, the throttling valve ( 19 ), that is operated to generate an increased pressure in a chamber ( 6 , 7 ), which is at the moment in a low pressure, in order to slow down said slider in a first work motion when a programmable interval is approached from said first predetermined position for each working pass, characterized in that the hydraulic circuit comprises a second throttling valve ( 19 ′), which is mounted in a bypass ( 190 ′) symmetrically opposite to said first throttling valve ( 19 ) and operated to generate an increased pressure in said other chamber, which is at the moment in a low pressure, in order to slow down said slider in a second work motion when a programmable interval is approached from a second predetermined position for each working pass.