Daido Tokushuko Kabushiki Kaisha

Shigeyuki Inagaki

Takao Shimizu

Hirotsugu Horio

Hiroaki Suzuki

Noboru Yamamoto

Ryuzo Yamada

Kazushige Kito

Masaki Tsuchiya

Kazushige Kitou

In diffusion bonding a metal pipe and a metal pipe via a bonded interface formed at the end parts, a portion that is inclined with respect to the radial direction of metal pipes and is provided at least at part of bonded interface In this case, the inclination angle &phgr; of bonded interface and the tip angle 2&thgr; of a pipe expansion tool are preferably in the relationship, 0<&phgr;&lE;&thgr;&plus;60&deg;. In performing pipe expansion of such a metal pipe bonded body the pipe expansion tool is moved from the metal pipe at which the inclined portion of junction face is formed to have a protruding shape, towards the metal pipe at which the inclined portion of junction face is formed to have a recessed shape. Furthermore, the inner diameter at the vicinity of the junction face of the metal pipe junction may be made larger than the inner diameter at positions away from the junction face.

Metal-pipe bonded body, pipe expansion method of metal-pipe bonded body, and method for inspecting metal-pipe bonded body

The present invention provides a metal pipe bonded body formed from a plurality of metal pipes. Each metal-pipe is formed with an elongated, pre-formed portion at each end, and a central portion, each elongated, preformed portion having a constant inside diameter greater than an inside diameter of the central portion of each metal pipe.

Expandable metal-pipe bonded body and manufacturing method thereof

Carbon steel pipes are joined to each other in a non-oxidizing atmosphere by using an insert constituted by a Ni-base alloy or a Fe-base alloy having a melting point which is lower than 1200&deg; C. and a thickness of 80 mm or smaller under conditions that the surface roughness Rmax of the joined surfaces of the carbon steel pipes is 20 &mgr;m or smaller, the joining temperature is not lower than 1250&deg; C. nor higher than 1330&deg; C., duration at the joining temperature is 30 seconds or longer and the pressure is not lower than 2 MPa nor higher than 4 MPa. The expanding operation is performed such that the maximum difference in level of the joined portion is not larger than 25% of the carbon steel pipe and the expansion ratio is 25% or lower.

Method for manufacturing joint of carbon steel pipes suitable for expansion and expanding method

In a method of bonding ferric and austenitic dual stainless steels, an insert material made of a Ni base alloy having a melting point below 1290.degree. C. is put between the bonding cross section faces of mother material steels comprising a dual phase stainless steel. A pressure force in the range of 3 MPa to 5 MPa is applied to a bonding area. The bonding area is heated at a temperature in the range of 1290.degree. C. to a melting point of the mother material steel. The temperature is kept for in the range of 30 second to 180 second.

Bonding method of dual phase stainless steel

In a metal material bonding method, an insertion material, which has a lower melting point than that of metal materials to be bonded, is interposed between bonding end surfaces of the metal materials to be bonded. The metal materials to be bonded is heated and held to a temperature not lower than the melting point of the insertion material and not higher than the melting point of the metal materials to be bonded while applying pressure to bonding surfaces of the metal materials to be bonded. The insertion material is formed to have a size which is smaller than each of the bonding surfaces of the metal materials to be bonded.

Growing community of inventors

Nagoya, Japan

Shigeyuki Inagaki