Ishikawajima-harima Heavy Industries Co., Ltd.

Ishikawajima Inspection & Instrumentation Co., Ltd

Kiyofumi Ishikawa

Norio Morishige

Shuji Furuya

Kenji Hirano

Akihiro Sato

Yasuhiro Aoki

Hiroto Yamaoka

Hiroyuki Miyazawa

A recess formed in close contact with a thin-walled portionof a workpiece to store molten metal at a surfaced portion, a jigmanufactured from a material with a higher heat-resisting temperature than that of the molten metal and a satisfactorily large heat capacity, a step (A) wherein the jig is installed on the workpiece, a preheating step (B) in which the workpiece and the jig are preheated to a predetermined temperature under the condition that jigis installed, a build up welding step (C) for build up welding the thin-walled portion of the workpiece and forming weld beads at surfaced portion, and a jig-removing step (D) for removing the jig after weld beads solidify completely.

Method of build up welding to thin-walled portion

The corrosion resistance inherent in stainless steel is further improved by a cladding layer provided on the surface thereof. The cladding layer is formed of a coating material which is applied onto the surface of the stainless steel and, then, burnt to be fused by laser beams. The coating material contains a larger amount of Cr than that of the stainless steel. The thus fused material and a fused portion of the stainless steel are mixed with each other to form the cladding layer of remarkable corrosion resistance due to a larger amount of Cr contained therein. The formation of the cladding layer on the inner surface of a small diameter pipe is enabled by a coating film shaping device which has a jig for shaping the applied material into a film of a uniform thickness and by a laser irradiation torch which has an arrangement for emitting the laser means radially outward from the inside of the pipe.

Corrosion resistant stainless steel

A laser irradiating torch device is used to apply corrosion resistant coating or other coatings to an inner surface of small diameter piping. The torch device consists basically of a torch body disposed in the rearward end of the torch device; a revolving torch head disposed in the forward end of the torch device which revolves around the central axis of the torch device; and a driving device to rotate the torch head disposed in the rearward end. A laser beam generated outside the torch device is transmitted to the torch head in an optical fiber disposed, longitudinally through the central axis, and the focal point of the laser beam can be adjusted with a lens system whose location can be adjusted in the axial direction. The transmitted laser beam is reflected radially out of the torch device with a reflection mirror, and the lens system is adjusted so that the laser beam is focused near the inner surface of the piping. When the torch device is inserted in the piping, a centering device aligns the torch body and the torch head centrally within the piping so that the revolving axis of the torch device coincides with the central axis of the piping. When the torch head is rotated and the laser beam turned on, the inner wall surfaces of the piping is heated uniformly to produce a coating of excellent consistency, thus producing a coating having superior corrosion resistant properties.

Laser irradiating torch

Growing community of inventors

Hiratsuka, Japan

Kiyofumi Ishikawa