Jfe Steel Corporation

Kawasaki Steel Corporation

Osamu Sonobe

Koji Suzuki

Rinsei Ikeda

Toyohisa Shinmiya

Jun Takano

Masaki Yoshikawa

Takuya Nagahama

Kazunari Takahashi

Masateru Ueta

Hiroshi Chikatsune

Yuji Hashimoto

Takamasa Kawai

Hirotaka Kano

Kazuhito Kenmochi

Akio Sato

Yoshikazu Kawabata

Shunsuke Toyoda

Ikuo Yarita

Masaki Urabe

Kinya Nakagawa

Akinobu Ishiwatari

Jiro Hiramoto

Akihiko Fukuhara

Yoshikazu Seino

Nobuaki Gamo

Eisuke Kawazumi

Takashi Akazawa

Kazusito Okada

Masaki Ueta

A threaded joint in which the outer peripheral face of the pin nose has a single tapered shape, the seal face of the box has an outwardly convex curved shape, and a seal point xdefined by equation (1) is greater than or equal to 0.2 inches, 

Threaded joint for steel pipes

A springback amount evaluation method evaluates an amount of springback after die release of a press forming product by a computer and includes: setting a plurality of section planes intersecting a shape of the press forming product at predetermined intervals; obtaining a sectional shape of the press forming product for each of the set section planes; and obtaining an orientation of each of the sectional shapes in each section plane as a direction of the each of the sectional shapes, wherein for each of a shape to be a reference of the press forming product and a shape after the die release, the above-described three steps are performed, and the amount of springback is evaluated by comparing, for all of the section planes, the obtained directions of the sectional shapes for the shape to be the reference and for the shape after the die release.

Springback amount evaluation method

A method for manufacturing a press formed part, the method including specifying stretch flange limit strain in a metal sheet by using strain gradient in a radial direction and strain gradient in a sheet thickness direction. The strain gradient in the radial direction being directed from an end portion of the metal sheet at a time a press load is applied. The strain gradient in the sheet thickness direction being a direction of the metal sheet that intersects a loading direction. Additionally, the stretch flange limit strain satisfies the formula &#x3f5;=A[a&#xb7;&#x394;&#x3f5;/&#x394;r+b&#xb7;&#x394;&#x3f5;/&#x394;t]+c, where &#x3f5;represents the stretch flange limit strain in a tangential direction of the sheet edge, &#x394;&#x3f5;/&#x394;r represents the strain gradient in the radial direction, &#x394;&#x3f5;/&#x394;t represents the strain gradient in the sheet thickness direction, A, a, and b represent influence coefficients, and c represents the limit strain at a time the strain gradient is zero.

Method for specifying stretch flange limit strain and method for determining feasibility of press forming

A threaded joint for steel pipes that includes a pin and a box. The pin has an externally threaded portion, a nose, and a shoulder portion. The box has an internally threaded portion, a sealing surface, and a shoulder portion. The outer circumferential surface of the nose of the pin has an outward convex curved shape, and the sealing surface of the box has a tapered shape. Additionally, the cross-sectional area of the pin at a seal point is 35% or more of the cross-sectional area of an original pipe portion corresponding to an unprocessed portion of the pin, the seal point being a portion on the pin that first comes into contact with the sealing surface of the box when the pin and the box are joined.

Threaded joint for pipes

A threaded joint for a pipe is disclosed in which scalability, compression resistance, and galling resistance are enhanced. The threaded joint includes a pin nose outer peripheral surface that forms an outward convex curve in an axial cross-sectional view; the convex curve is such that a composite R curve, in which a plurality of outward convex arcs having different radiuses of curvature are connected in sequence to a generating line of a cylindrical portion next to a male member, is curved such that the radiuses of curvature increase with distance from the male member and tangents on connection points of the arcs are aligned with those of corresponding arcs connected thereto; and the inner peripheral surface of a box component facing the pin nose is a tapered surface that interferes with the pin nose outer peripheral surface when connected to a pin component.

Threaded joint for pipe

Provided is a threaded joint for steel pipes having high sealability even under a bending load. In the threaded joint, when a pinand a boxare threadedly connected with each other, the outer peripheral face of a noseof the pin and the inner peripheral face of a nose of the box are in metal-to-metal contact with each other at a contact portion and the contact portion serves as a seal portion. A threaded portion, at which the externally threaded portionand the internally threaded portionare threadedly connected with each other, has a negative load flank angle &#x3b1;, shoulder portionsandhave a negative torque shoulder angle &#x3b2;, and the ratio L/dof a length L of the nose and a pipe outside diameter dis equal to or higher than 0.08.

A method enhances fatigue strength of ear portions which are high fatigue risk parts in a torsion beam almost without bringing about disadvantages in terms of productivity and cost. A torsion beam is formed with a portion of the tubular body into an approximately U-shape in cross section by crushing the portion of the tubular body in the radial direction and, thereafter, due to bending with a bottom line set as a belly side of bending, a bending strain of 2 to 6% in the tube longitudinal direction on a tensile side is imparted to the ear portions.

Torsion beam manufacturing method and torsion beam

The present invention provides a composite roll for cold rolling capable of rolling a cold-rolled steel strip having little edge drop, a cold-rolled stainless steel strip or a bright finish steel strip having excellent surface brightness or a silicon steel strip excellent in magnetic properties without causing breakage of roll, which is a roll in which a sleeve is fitted at a surrounding of a shaft portion with the shaft portion as a central axis and its fabrication method, in which the sleeve is constituted by previously integrating a plurality of pieces of mold members divided by a face intersecting with the central axis of the roll. Further, this is a fit roll in which a sleeve member of an outermost layer is made of WC&mdash;Co series hard alloys having Young's modulus of 35000 kgf/mm or more and Co content of 12-50 weight % and is provided with a wall thickness of 3% or more of roll radius and a ratio L/D of a length L of a barrel of the sleeve to a diameter D of the roll falls in a range of 2-10. Further, when there are one layer or more of intermediate layers between the outermost layer of the sleeve and the shaft core, the intermediate layers are arranged such that Young's modulus of the layer on the outer side is larger than Young's modulus of the layer on the inner side.

Compound roll for thin cold rolled steel strip and method of manufacturing same

A method of producing a stainless steel produces steel sheets having excellent surface brightness. The method includes performing a cold rolling operation using a work roll having a Young's modulus between 25,000 to 70,000 kg/mm.sup.2 in one or more stands of a tandem mill having a plurality of stands. Preferably the work roll is composed of a tungsten carbide based hard metal alloy. The diameter of a work roll at a final stand of the tandem mill is equal to or smaller than a diameter of a work roll in the previous stand. It is preferable that the work roll is dimensioned to have a diameter between 150 mm to 400 mm. In addition, it is preferable that a cold rolling operation is achieved at a reduction between 25% to 60% reduction in the final stand of the tandem mill.

Method of producing a stainless steel sheet having excellent surface

Growing community of inventors

Chiba, Japan

Osamu Sonobe