Kawasaki Steel Corporation

Jfe Steel Corporation

Toyota Jidosha Kabushiki Kaisha

The Furukawa Electric Co., Ltd.

Toyota Motor Corporation

Furukawa Aluminum Co., Ltd.

Kawatetsu Wire Products Company Ltd.

Takaaki Hira

Hideo Abe

Yuji Yamasaki

Kazuhiko Higai

Toru Sasaki

Osamu Furukimi

Takaaki Toyooka

Takatoshi Okabe

Yuji Hashimoto

Saiji Matsuoka

Masahiko Morita

Akira Yorifuji

Motoaki Itadani

Yuji Shimoyama

Koichi Hashiguchi

Nobuo Totsuka

Nobuki Tanaka

Kunio Isobe

Taro Kanayama

Motohiro Nabae

Masanori Nishimori

Yoshihiro Matsumoto

Katsuhiro Ochi

Makoto Imanaka

Takeshi Fujita

Akira Yasuda

Kei Sakata

Kaneharu Okuda

Takashi Obara

Hideyuki Nikaido

Yoichi Tobiyama

Yoshikazu Kawabata

Toshiyuki Kato

Yoshikiyo Tamai

Nobuyuki Morito

Yoichiro Bekki

Ikuo Yarita

Fumiya Yanagishima

Takayuki Futatsuka

Yoshihisa Serizawa

Takayuki Naoi

Yasuji Uesugi

Kazuya Miura

Rinsei Ikeda

Naoki Nishiyama

Takaaki Iguchi

Atsushi Ogino

Kunihiko Kataoka

Shusaku Takagi

Toshitake Hanazawa

Nobutaka Kurosawa

Kichizaemon Nakagawa

Toshihiro Hanada

Kouzou Ishikawa

Shigeru Ueki

Kozo Fujiwara

Keiji Kumagai

Takashi Sasaki

Kouichi Tahara

Takanori Tamari

Kazuyoshi Sato

Tadaaki Morishita

Hiroaki Ueno

A method for manufacturing a closed structure part has a closed section using a blank made from a metal plate by pressing the blank using a press forming die and fixing a pair of joint ends of the blank to each other, the method including a pre-forming step of processing the blank into an interim part having a closed section corresponding to the closed structure part, a closing step of, after the pre-forming step is completed, moving the joint ends of the interim part toward each other and urging, against one of the joint ends, a concave flange processing portion formed on one of a pair of press forming surfaces of the press forming die at the edge end adjacent to the other press forming surface, and a press joining step of, after the closing step is completed, further moving the press forming die in a pressing direction, bending the one of the joint ends using a pressing force applied from the flange processing portion so that the joint end overlaps the outer surface of the other join end and a latch flange portion for latching the other joint end is formed and, simultaneously, pressing the blank using the pair of press forming surfaces and press-forming outer portions of the pair of the joint ends of the blank into predetermined shapes.

Closed structure parts, method and press forming apparatus for manufacturing the same

A method for manufacturing includes a polygonal shape closed structure part with a bent shape in the longitudinal direction only by press forming. The method uses two metal plates for manufacturing a curvilineal closed structure part and includes a press forming process of forming straight or bent folding lines in the longitudinal direction of the two metal plates at positions corresponding to a polygonal bent shape with a flange formed at least at one of the ends of the width direction of each plate, a process of forming a closed structure by laying the two metal plates to overlap each other flange to flange and end to end for ends without flanges and by welding the portions laid to overlap each other in the longitudinal direction of the metal plates, and a process of forming a polygonal shape closed structure having a bent shape in the longitudinal direction by holding both ends of the closed structure and by compressing it toward its central axis.

Curvilineal closed structure parts and method for manufacturing the same

The number of sub-parts of a closed structure part and the number of steps for manufacturing the closed structure part can be reduced and, therefore, the closed structure part can be efficiently manufactured. In a hemming press step, a punch is further lowered, and a pair of flange portions is inserted into a slit clearance. Hemming prongs are bent and each of the hemming prongs sandwiches the flange portion. The flange portion, which is one of the two flange portions, is joined to the other flange portion. At the same time, a pair of press forming surfaces of the punch presses a metal plate and performs press-forming on a pair of shoulder portions of a blank into a predetermined shape. The flange portion can be fixed to the other flange portion using the hemming prongs. The pair of shoulder portions of the blank can be press-formed into the predetermined shape.

The steel pipe has a structure composed mainly of ferrite or ferrite plus pearlite or ferrite plus cementite. The steel pipe is characterized by grain size not greater than 3 &mgr;m, preferably not greater than 1 &mgr;m, elongation greater than 20%, tensile strength (TS:MPa) and elongation (E1:%) whose product is greater than 10000, and percent ductile fracture greater than 95%, preferably 100%, measured by Charpy impact test on an actual pipe at &minus;100&deg; C. The structure is characterized by C: 0.005-0.03%, Si: 0.01-3.0%, Mn: 0.01-2.0%, and Al: 0.001-0.10% on a weight basis, and is composed of ferrite or ferrite and a secondary phase, with ferrite grains being not greater than 3 &mgr;m and the secondary phase having an areal ratio not more than 30%. A steel pipe stock having the above-mentioned composition is heated at a temperature of (Ac,&plus;50&deg; C.) to 400&deg; C. and subsequently reduced at a rolling temperature of (Ac,&plus;50&deg; C.) to 400&deg; C. such that the cumulative reduction of diameter is greater than 20%. The reducing is preferably performed such that at least one of rolling passes reduces the diameter by more than 6% per pass. The steel pipe will have high ductility and high strength and will be superior in toughness and stress corrosion cracking resistance, if the content of C, Si, Mn, and other alloying elements is limited low and reducing is performed at the temperature specified above. The resulting steel pipe has good fatigue resistance and is suitable for use as line pipe.

Steel pipe having high ductility and high strength and process for production thereof

A steel pipe containing fine ferrite crystal grains, which has excellent toughness and ductility and good ductility-strength balance as well as superior collision impact resistance, and a method for producing the same are provided. A steel pipe containing super-fine crystal grains can be produced by heating a base steel pipe having ferrite grains with an average crystal diameter of di (&mgr;m), in which C, Si, Mn and Al are limited within proper ranges, and if necessary, Cu, Ni, Cr and Mo, or Nb, Ti, V, B, etc. are further added, at not higher than the Ac,transformation point, and applying reducing at an average rolling temperature of &thgr;m (&deg;C.) and a total reduction ration Tred (%) within s temperature range of from 400 to Ac,transformation point, with di, &thgr;m and Tred being in a relation satisfying a prescribed equation.

Ultrafine-grain steel pipe and process for manufacturing the same

Thin steel sheet having excellent rectangular drawability and production

A high strength steel sheet for automobiles which exhibits excellent press-formability strength against impact resistance at a high strain rate is hot rolled under specific conditions, or is cold rolled from hot rolled sheet which is prepared under conventional conditions, with the cold rolled steel being annealed under specific conditions. The steel sheet comprises 0.010-0.10 wt % of C, not greater than 1.50 wt % of Si, 0.50-3.00 wt % of Mn, not greater than 0.010 wt % of S and 0.01-0.1 wt % of Al, and one kind or two kinds selected from 0.05-0.15 wt % of P and 0.5-1.5 wt % of Cr, and the balance being Fe and inevitable impurities and having a structure mainly composed of 2-30 vol % of martensite phase and a ferrite phase containing a solution C not greater than 0.0010 wt %.

Steel sheet for automobiles having excellent impact resistance and

A method including preparing an aluminum scrap containing a total of about 0.3 to 2.0 wt % of Fe and Si; melting and then adjusting the material composition so as to attain an Mg content of about 3 to 10 wt % or a composition further containing at least one of the elements Cu, Mn, Cr, Zr and Ti, each in the amount of 0.02 to 0.5 wt %; subjecting the material to casting, hot rolling, cold rolling and continuous annealing to obtain an aluminum alloy sheet having a tensile strength of about 31 kgf/mm.sup.2 or more; and applying a lubricant surface coating to impart a coefficient of friction of not more than about 0.11.

Method of producing an aluminum alloy sheet excelling in formability

In a hot-dip zinc-coated steel sheet exhibiting excellent press die sliding characteristics and obtained by performing a molten galvanization and then skin pass rolling on a surface of the steel sheet, a galvanized layer has a three-dimensional average surface roughness ranging from 0.7 .mu.m to 1.4 .mu.m, and a skewness (S) of the amplitude probability distribution of the surface roughness, which is defined by the following equation (1), ranging from 0.1 to -0.3:

Galvannealed steel sheets exhibiting excellent press die sliding property

Aluminum alloy sheet with improved formability and method of production

A process and an equipment for micro-pattern forming on the surface of a rolling roll, and a metallic thin sheet and preparation thereof by transferring a micro-pattern on the surface by use of the roll are provided. Such a rolling roll can be attained by a method wherein resin film mixed with optical absorbing agent is formed on the surface, a Q switch YAG laser having an output of 5 to 100W is applied to make a marking on this resin film, a part of the coated film is removed in strict accordance with the pattern, then an etching process is applied to the roll surface. The metallic thin sheet skin pass rolled by this roll is used as a car panel and is superior in pressworkability and sharpness of reflections.

Process and equipment for micro-pattern forming on roll surface, metal

A slab is successively fed between periodically moving press tools to reduce the slab in a widthwise direction. In this method, the leading and tail end portions of a given length in the slab are reduced at a reduced width wider than that of remaining steady portion.

Method of reducing slab in widthwise direction

A steel cord comprising at least 10 metal filaments and having an elongation of 0.015-0.045% under a load of 0.5 kgf, an elongation of 0.025-0.060% under a load 1 kgf, and an elongation of 0.060-0.114% under a load of 4 kgf, assuming that the elongation under a load of 0.05 kgf is 0%, has a soft twist construction and is suitable to be used in the carcass of a radial tire for truck and bus.

Steel cord for radial tire

A continuous annealing apparatus for metal strips comprises cylindrical rolls each arranged at a location immediately before the metal strip passes about a hearth roll in a high temperature heat-treatment region of the apparatus. An axis of the cylindrical roll is finely tilted relative to the hearth roll within 0.15 degree in directions compensating for shifted distances of the metal strip on the hearth roll in response to every 50 mm shift of the strip, thereby preventing meandering and buckling of the metal strip caused by the hearth rolls.

Continuous annealing apparatus

In the operation of a continuous-process annealing furnace for a steel strip of a continuous length which is guided through the high-temperature zones of the furnace by the upper and lower hearth rolls in an alternate up and down vertical movement, each of the hearth rolls having an end-tapered or crowned configuration to correct the meandering of the running strip, each of the hearth rolls is coupled with one or a plural number of straightly cylindrical auxiliary rolls in contact with the strip at a position close to the hearth roll. By virtue of the installation of the auxiliary rolls, the phenomenon of wrinkling or buckling in the steel strip can be effectively prevented without causing meandering and the effect is more remarkable when specific relationships are held among the values of the diameters of the hearth roll and auxiliary roll and the position of the auxiliary roll relative to the hearth roll.

Method for continuous annealing of a metal strip

Growing community of inventors

Chiba, Japan

Takaaki Hira