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US 5,611,259 AGranted
Hydraulic circuit for driving a ram of hydraulic press
AssigneeNisshinbo Industries, Inc.
InventorTakeshi Nagata
Life of this patent
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AssigneeNisshinbo Industries, Inc.
InventorTakeshi Nagata
Estimating the term…
The hydraulic circuit directional control valve 20 is provided in a line connected with a lower chamber 13 of the hydraulic cylinder 1 and the B-port of the servo valve 3. A check valve 22 permitting oil flowing into the P-port of the servo valve 3 from the lower chamber 13 is provided in the line in parallel with the hydraulic circuit directional control valve 20 and connected with the lower chamber 13 and the P-port of the servo valve 3. When making the ram 15 move downward with high speed, the hydraulic differential circuit is constituted by changing the hydraulic circuit directional control valve 20 such that the delivery oil exhausted from the lower chamber 13 returns to the P-port of the servo valve 3. The hydraulic oil supplied from the hydraulic pump 1 flows into the upper chamber 12 through the servo valve 3. The delivery oil exhausted from the lower chamber 13 returns to the suction side of the P-port of the servo valve 3 through the check valve 22, assisting the flow rate of the hydraulic pump 2.
A hydraulic circuit for driving a ram of hydraulic press comprising:
Dependencies are inferred from the claim text.