Sumitomo Metal Industries, Inc.

Kayaba Kogyo Kabushiki Kaisha

Toshiji Takigawa

Akira Sakamoto

Hiroo Ohtani

Yoshiro Matsumoto

Seiichi Watanabe

Ryuji Takahashi

Tatsuro Kunitake

Junichi Kida

A control system for a superhigh pressure generation circuit includes a hydraulic pump having a usual range of delivery pressure. An electrohydraulic servo valve controls the flow rate of pressurized fluid from the pump and supplies it to a primary side of a boost cylinder. A stepped piston slidably received in the boost cylinder strokes in response to the input fluid to generate a fluid pressure elevated in accordance with an effective sectional area ratio of the stepped piston in a secondary side of the boost cylinder. The fluid pressure in the secondary side is caused to coincide accurately with a reference pressure level on the basis of a feedback control.

Control system for superhigh pressure generation circuit

A heavy thick steel casting having high mechanical strength with a tensile strength of 80 kg/mm.sup.2 or more, excellent impact properties with a vE.sub.O value of more than 8 kg-m/cm.sup.2 and improved weldability, and also a method of manufacturing the same. In the method, steel containing boron as an essential component and with a Ceq value corresponding to the maximum thickness of the product is cast. The casting is solidified in air, then heated to a temperature of 930.degree. to 1,050.degree. C. for one hour or more, followed by air cooling. Thereafter, the casting is quenched and tempered to thereby impart the casting with the desired characteristics.

Heavy thick high-strength casting having improved weldability and impact

In a variable crown sleeve roll, the inner peripheral surface of a sleeve is sealingly secured at opposite ends to the opposite ends of the outer peripheral surface of an arbor to define a chamber of a predetermined shape therebetween in the central portion of the sleeve. A pressurized fluid is supplied to said chamber through a passage in the arbor to distend the sleeve so as to control the amount of the crown of the roll. Values of the smallest thickness of the sleeve at the axially central part of the sleeve, the length of the pressure receiving part of the sleeve and the sleeve thickness taper angle for defining said chamber are selected in accordance with predetermined conditions.

Variable crown sleeve roll

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Osaka, Japan

Toshiji Takigawa