Kawasaki Steel Corporation

Jfe Steel Corporation

Kao Corporation

Kazuhito Kenmochi

Hiroyasu Yokoyama

Tomohiro Inoue

Yukinori Iizuka

Ikuo Yarita

Takatoshi Okabe

Shigeto Sakashita

Akihiko Fukuhara

Hideo Abe

Akira Kishida

Tomio Komatu

Yuji Sugimoto

Hiroyuki Nagamori

Osamu Sonobe

Toru Sasaki

Hiroyuki Shirosawa

Hiroyuki Matsuda

Takeshi Yoshimoto

Muneyoshi Murakami

Makoto Kobayashi

Kei Sakata

Fumiya Yanagishima

Kenichi Iwazaki

Masanori Kitahama

Koichi Ito

Yasuo Nishida

Hirotaka Kano

Yuichiro Watanabe

Yasuhiro Yamada

Junichi Tateno

Daijiro Yuasa

Tetsuro Sawaki

Yoshikazu Seino

Nobuyuki Matsuo

Tatsuo Koide

Osamu Shiotani

Eisuke Kawazumi

Takashi Akazawa

Kazusito Okada

Hisao Imai

Toshihiro Fukaya

Yoshifumi Fujioka

Tomohiro Kaneko

Nobuaki Gamo

Motoaki Egi

A method for manufacturing an electric resistance steel pipe having a good toughness at a welded portion is provided, the method being capable of stably manufacturing an electric resistance welded steel pipe having a desirable toughness at a welded portion although a steel strip serving as a base material has a dimensional variation. Groove shapes and are applied to edges and of an open pipe, an edge shape monitor continuously captures images of the edges and immediately before electric resistance welding, and the captured images are input to an arithmetic processing unit for image processing.

Method and equipment for manufacturing electric resistance welded steel pipe

A method of manufacturing an electric resistance welding pipe is provided in which a lateral edge shape is made to be an appropriate shape immediately before electric resistance welding is performed, whereby penetrators are securely removed during the electric resistance welding and, consequently, an electric resistance welding pipe having excellent characterization of welded seam can be obtained. A fin shape in finpass forming is printed to lateral edges of a strip, whereby the lateral edges of the strip are shaped with predetermined tapering.

Method of manufacturing electric resistance welding pipe having excellent characterization of welded seam

A method of efficiently manufacturing electric resistance welding pipes having excellent characterization of welded seams is provided, by which each lateral edge of a rounded strip immediately before electric resistance welding is securely shaped with desired tapering flexibly in response to change in strip thickness, so that welding quality may be kept to be excellent. A method of manufacturing electric resistance welding pipes, in which a strip is subjected to forming, then edges thereof are formed to substantially face each other, and then the edges are subjected to electric resistance welding to form a pipe, wherein an edge and an edge opposed thereto at one of an upper-surface side and a lower-surface side of the strip are shaped with tapering before the forming by means of cutting or shaving, or finpass forming.

Method of manufacturing electric resistance welding pipes having excellent characterization of welded seams

According to the present invention, penetrators can be adequately determined as flaws. In particular, a welded zone of a pipe is subjected to ultrasonic flaw detection at least in a pipe axial direction, and the quality of the pipe is evaluated using observed values in units of a predetermined area in a pipe thickness direction and the pipe axial direction. The length of one side of the predetermined area is an ultrasound beam width or more and a pipe thickness or less. The quality of the pipe can be evaluated while shifting the predetermined area in the pipe axial direction by using an average value of the observed values within the predetermined area. The length of one side of the predetermined area can be made an ultrasound beam width or more and a pipe thickness or less.

Quality control method and manufacturing method for pipe

The present invention has a structure capable of detecting the scattered-type penetrator having oxides each with the size of several &#x3bc;m sparsely and widely dispersed. Specifically, the structure includes a wave transmission unitfor transmitting an ultrasonic wave to the welded surface of the welded portionin a pipe axial direction of the pipesuch that the beam width of a transmission beamis brought into a range from 0.5 mm to 2.5 mm, and a wave reception unitfor receiving at least a portion of the reflection wave (reception beam) at the welded surface. The wave transmission unitand the wave reception unitinclude transmission/reception units formed of different groups of transducer elements on at least one or more array probesarranged in the circumferential direction of the pipe.

Ultrasonic flaw detection apparatus and ultrasonic flaw detection method for pipe

In an electric resistance welded steel pipe with excellent weld toughness for a line pipe, the area fraction of minute defects each having a maximum length of less than 50 &#x3bc;m in a projection plane of an electric resistance welded seam is in the range of 0.000006 to 0.026, and the absorbed energy at &#x2212;40&#xb0; C. measured by a method for an impact test of metallic materials is 315 J or more.

Electric resistance welded steel pipe with excellent weld toughness for line pipe

Manufacturing equipment of electric resistance welding pipes having excellent characterization of welded seams, includes an apparatus that supplies a strip, an apparatus that reforms a shape, an apparatus that performs roll forming, an induction heater, and a contacting apparatus of strip edges by pressing, and having a finpass forming apparatus incorporating a fin having at least two stages of tapering in a middle portion of the roll forming, wherein tapering of the strip immediately before electric resistance welding is conducted such that an angle from a surface of a strip edge toward a vertical direction is in a range of 25 degrees to 50 degrees, and length of a perpendicular angle from a starting position to an end position of the tapering at one side is 20% to 45% of strip thickness, and by shaping the tapering with a fin, having at least two stages of tapering, incorporated in a finpass forming end stand.

Manufacturing equipment for electric resistance welding pipes having excellent characterization for welded seam

An ultrasonic flaw detection is performed to a welded portionof a pipe body, a defect detection threshold value is determined based on the signal intensity difference between the total area of the defects existing in the region of an ultrasonic beam on a welded surface and an artificial defect, and a quality control of the pipe body is performed based on the defect detection threshold value. An equivalent defect diameter is determined from the defect density on the welded surface of the welded portion of the pipe body in a pipe axis direction and the area of the ultrasonic beam on the welded surface based on the total area of the defects existing in the region of the ultrasonic beam, and the defect detection threshold value is determined based on the equivalent defect diameter and the signal intensity difference of the artificial defect.

Calibration of an ultrasonic flaw detector and quality control and production methods for a tubular body

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

It is possible, in a rolling method of a strip shifting one-side-tapered work rolls in the axial direction and causing the upper and the lower work rolls to cross each other, to appropriately set a quantity of shift and a crossing angle and to improve an edge drop satisfactorily, by utilizing the relationship of the three factors including the quantity of shift and the crossing angle for determining quantities of operation necessary to correcting an edge drop of the strip and the quantity of correction of edge drop corresponding to these quantities of operation in the form of the relationship between the roll gap between the upper and the lower work rolls and the quantity of correction of edge drop, by providing an effective roll gap reference position apart from the strip edge by a prescribed distance.

Rolling method and rolling mill of strip for reducing edge drop

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

An apparatus for pre-processing a stainless steel to be cold-rolled comprising: annealing and pickling means having a mechanical descaling device and a pickling device; rolling means consisting of rolls arranged to be two or more stages; and means capable of applying liquid lubricant at a thin thickness to a work roll of the rolling means.

Apparatus for pre-processing stainless steel strip intended to be

A multi-roll cluster rolling apparatus has a pair of work rolls, and a plurality of first intermediate rolls, a plurality of second intermediate rolls and a plurality of backup rolls arranged successively in the mentioned order behind each the work roll. A roll crown presented by unidirectinally tapering one end of a roll is imparted to at least a pair of rolls, e.g., the work rolls, selected from a roll group consisting of the work rolls, first intermediate rolls and the second intermediate rolls. A roll crown approximated by at least one-pitch portion of a waveform is imparted to at least one other pair of rolls, e.g., pairs of the first intermediate rolls. A roll crown approximated by at least two-pitch portion of a waveform is imparted to at least one of the remainder pairs of rolls, e.g., selected pairs of the second intermediate rolls. The rolls of each pair having the same roll crown arranged arranged in opposite axial directions and are axially shiftably mounted on a mill housing.

Multi-roll cluster rolling apparatus

A method of pre-processing a stainless steel strip to be cold-processed comprising the steps of: annealing and pickling the stainless steel strip after completing hot rolling; applying liquid lubricant with a thickness of 1 .mu.m or less to the surfaces of rolls before the rolls come into contact with the stainless steel strip; and rolling the stainless steel strip at a reduction ratio exceeding 5%. An apparatus for pre-processing a stainless steel to be cold-rolled comprising: annealing and picking means having a mechanical descaling device and a pickling device; rolling means consisting of rolls arranged in two or more stages; and means capable of applying liquid lubricant in a thin layer to a work roll of the rolling means.

Method for pre-processing stainless steel strip intended to be

A process of producing cold rolled stainless steel strip, according to the invention, includes preliminary treatment for hot rolled stainless steel strip, in which preliminary treatment, hot rolled stainless steel strip is, at first, treated through annealing and picking process and is subsequently subject cold rolling without introducing rolling mill lubricant at a reduction of more than 5%. The process of preliminary treatment for preparation of cold rolling is useful for producing high surface brightness cold rolled stainless steel strip, which can achieve both of satisfactory quality and high efficiency.

Method and apparatus for preliminary treatment of stainless steel for

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Chiba, Japan

Kazuhito Kenmochi