Abstract: The gas separator is provided with a substrate portion having a predetermined concave-convex shape, an underlying coating layer formed on the substrate portion, a first coating layer for coating the substrate portion and the underlying coating layer, and a second coating layer formed thereon. The second coating layer is formed from a carbon material, and is sufficiently conductive. Moreover, the second coating layer protects the underlying layer. The first coating layer is formed from a noble metal. Therefore, the first coating layer coated with the second coating layer exhibits extremely high corrosion resistance. The underlying coating layer and the substrate portion are coated with the first and second coating layers, so that the progress in corrosion can be sufficiently prevented. Thus, excellent overall corrosion resistance of the separator can be realized.

Abstract: A method and apparatus of manufacturing an endless metallic belt adjusts a circumferential length of the belt by subjecting the endless metallic belt to a shot peening treatment. For example, by measuring the circumferential length prior to the shot peening treatment and determining the condition of the shot peening treatment on the basis of the measured length, and/or by measuring the circumferential length during the shot peening treatment and terminating the shot peening treatment on the basis of the measured length.

Abstract: An endless metallic belt has at its outer peripheral surface a layer provided with a compressive residual stress by shot peening, and also has at its inner peripheral surface a layer provided with a compressive residual stress by shot peening. In a method for manufacturing the endless metallic belt, both outer and inner peripheral surfaces of the endless metallic belt are subjected to shot peening, wherein the inner peripheral surface is shot peened prior to the outer peripheral surface. The method produces an endless metallic belt having its fatigue strength improved without suffering any significant deformation.

Abstract: A method and apparatus of manufacturing an endless metallic belt adjusts a circumferential length of the belt by subjecting the endless metallic belt to a shot peening treatment. For example, by measuring the circumferential length prior to the shot peening treatment and determining the condition of the shot peening treatment on the basis of the measured length, and/or by measuring the circumferential length during the shot peening treatment and terminating the shot peening treatment on the basis of the measured length.

Abstract: An endless metallic belt has at its outer peripheral surface a layer provided with a compressive residual stress by shot peening, and also has at its inner peripheral surface a layer provided with a compressive residual stress by shot peening. In a method for manufacturing the endless metallic belt, both outer and inner peripheral surfaces of the endless metallic belt are subjected to shot peening, wherein the inner peripheral surface is shot peened prior to the outer peripheral surface. The method produces an endless metallic belt having its fatigue strength improved without suffering any significant deformation.

Abstract: The gas separator is provided with a substrate portion having a predetermined concave-convex shape, an underlying coating layer formed on the substrate portion, a first coating layer for coating the substrate portion and the underlying coating layer, and a second coating layer formed thereon. The second coating layer is formed from a carbon material, and is sufficiently conductive. Moreover, the second coating layer protects the underlying layer. The first coating layer is formed from a noble metal. Therefore, the first coating layer coated with the second coating layer exhibits extremely high corrosion resistance. The underlying coating layer and the substrate portion are coated with the first and second coating layers, so that the progress in corrosion can be sufficiently prevented. Thus, excellent overall corrosion resistance of the separator can be realized.

Abstract: A press-formed article has a quenched area and a required strength distribution. The quenched area has a hardness distribution exhibiting a hardness transition which corresponds to the required strength distribution. The press-formed article may include one end portion, the other end portion, and a central area disposed between the one end portion and the other end portion. The quenched area is extended from the one end portion and to the other end portion. The hardness distribution of the quenched area exhibits a condition that hardness is the highest in the central area in such a manner that hardness is gradually decreased from the central area to the one end portion and to the other end portion.

Abstract: A multistage gear-rolling apparatus of the present invention comprises a roller squeezing apparatus including a roughing roller die and a finishing roller die disposed coaxially and connected in series in an axial direction of said roughing roller die. The roughing roller die is used for carrying out a hot rough-rolling step. The finishing roller die is used for a warm finish-rolling step. Thus, immediately after the hot rough-rolling step, the warm finish-rolling step can be carried out without a reset of workpiece.

Abstract: According to the present invention, in a heating step, an outer circumferential portion of a workpiece having a disk shape is heated to high temperatures. In a hot rough-rolling step, the outer circumferential portion of the heated workpiece is formed by use of a roller die to generate a rolled-gear having teeth. In a warm finish-rolling step, the teeth of the rolled-gear are finish-rolled by use of the finishing roller die. The starting temperature T.sub.1 of the hot rough-rolling step is set in the range of from 850.degree. through 1100.degree. C., the terminating temperature of the hot rough-rolling step T.sub.2 is set in the range of from 500.degree. through 700.degree. C. The starting temperature T.sub.3 of the warm finish-rolling step is set in the range of from 400.degree. through 700.degree. C., and the terminating temperature of the warm finish-rolling step T.sub.4 is set in the range of from 200.degree. through 650.degree. C.

Abstract: A method for producing cast iron gears includes the steps of heating a blank composed of cast iron and having a teeth forming part to such a temperature that at least the teeth forming part is at least austenitized, and hot rolling the teeth forming part of the blank by pressing projecting teeth of a rolling machine against the teeth forming part which is in a hot state and within an austenitized range, while cooling the blank, thereby generating a teeth part in the teeth forming part of the blank. Hot rolling with a low plastic deformation resistance prevents lowering of strength due to the exposure of graphite particles of cast iron and occurrence of quenching cracks and rolling cracks, and improves gear accuracy.

Abstract: In a method and apparatus for manufacturing a corrugated tube, a tube is clamped by a pair of spaced apart chucks. A local portion of the tube is softened. The chucks are moved in the same direction such that the trailing or rearward chuck moves farther than the leading or forward chuck, thereby imparting an axially compressive force on the tube. Accordingly, a bulge is formed at the softened portion of the tube. The heating and compression cycle may be performed several times to obtain a corrugated tube having a plurality of bulges or waves formed therein.

Abstract: A brightening chemical polishing solution for a hardened steel article (e.g., a carburized and quenched gear) comprises hydrofluoric acid having a molar concentration of from 0.2 to 2 mol/l, hydrogen peroxide having a molar concentration of from 0.4 to 4 mol/l, and water, a molar ratio of the hydrofluoric acid to the hydrogen peroxide being from 1:1.5 to 1:2.8. The steel article is quench hardened and is chemically polished in the solution. A shot-peening is additionally performed, prior to the polishing.

Abstract: A production process for producing a hollow steel tube of a high strength includes the steps of a tube preparation step of producing a seamless steel tube of a heavy thickness containing flaws of less than 0.25 mm in depth in an inner periphery thereof, a tube inner periphery correction step of correcting at least the flaws having a width of 0.001 mm or less so as to have a depth of 0.15 mm or less, and a hardening step of hardening the seamless steel tube across a whole thickness thereof to a hardness of from 450 to 670 in Vickers hardness (Hv). The production process enables not only to produce a hollow steel tube of a high strength at a less production cost but also to adapt it to exhibit such a high torsional fatigue fracture resistance and a high impact strength that it is applicable to axles for large size automobiles producing high outputs.