A corrugated steel pipe is disclosed. The corrugated steel pipe comprises a plurality of unit steel pipes, which are continuous in the axial direction. Each unit steel pipe comprises a first cylindrical pipe obtained by bending a first unit steel plate into a cylindrical shape, both ends of the first unit steel plate abutting each other and forming a first seam on one side of the first cylindrical pipe; and a second cylindrical pipe obtained by bending a second unit steel plate into a cylindrical shape, both ends of the second unit steel plate abutting each other and forming a second seam on one side of the second cylindrical pipe. The second cylindrical pipe is bent into a cylindrical shape and folded on the outer surface of the first cylindrical pipe so that the inner surface of the second unit steel pipe surrounds the first seam. The second seam is positioned not to correspond to the first seam.

A corrugated steel pipe is disclosed. The corrugated steel pipe comprises a plurality of unit steel pipes, which are continuous in the axial direction. Each unit steel pipe comprises a first cylindrical pipe obtained by bending a first unit steel plate into a cylindrical shape, both ends of the first unit steel plate abutting each other and forming a first seam on one side of the first cylindrical pipe; and a second cylindrical pipe obtained by bending a second unit steel plate into a cylindrical shape, both ends of the second unit steel plate abutting each other and forming a second seam on one side of the second cylindrical pipe. The second cylindrical pipe is bent into a cylindrical shape and folded on the outer surface of the first cylindrical pipe so that the inner surface of the second unit steel pipe surrounds the first seam. The second seam is positioned not to correspond to the first seam.

Provided are a pipe which exhibits corrosion resistance against vapor of fuel such as gasoline, diesel oil, bioethanol or a biodiesel fuel, a method for manufacturing the pipe, and a steel sheet for manufacturing the pipe. A method for manufacturing a pipe having a bent portion which has excellent corrosion resistance against fuel vapor includes the steps of; preparing a steel sheet for manufacturing a pipe which is characterized by having a zinc-nickel (ZnNi) alloy layer where a nickel content is 4 to 16 at % on at least one surface of the steel sheet; forming the steel sheet for manufacturing a pipe into a tubular shape such that the ZnNi alloy layer forms an inner surface of the pipe, and applying bending to the pipe such that the elongation of the bent convex portion generated at the time of bending the pipe falls within 20%. A steel sheet for manufacturing a pipe having excellent corrosion resistance against fuel vapor has a ZnNi alloy layer on at least an uppermost surface of a surface thereof which constitutes an inner surface of the pipe, and a nickel content in the ZnNi alloy layer is 4 to 16 at %.

Provided are a pipe which exhibits corrosion resistance against vapor of fuel such as gasoline, diesel oil, bioethanol or a biodiesel fuel, a method for manufacturing the pipe, and a steel sheet for manufacturing the pipe. A method for manufacturing a pipe having a bent portion which has excellent corrosion resistance against fuel vapor includes the steps of; preparing a steel sheet for manufacturing a pipe which is characterized by having a zinc-nickel (ZnNi) alloy layer where a nickel content is 4 to 16 at % on at least one surface of the steel sheet; forming the steel sheet for manufacturing a pipe into a tubular shape such that the ZnNi alloy layer forms an inner surface of the pipe, and applying bending to the pipe such that the elongation of the bent convex portion generated at the time of bending the pipe falls within 20%. A steel sheet for manufacturing a pipe having excellent corrosion resistance against fuel vapor has a ZnNi alloy layer on at least an uppermost surface of a surface thereof which constitutes an inner surface of the pipe, and a nickel content in the ZnNi alloy layer is 4 to 16 at %.

An apparatus for forming the profile of deformable materials including tubular sections. The apparatus (1) includes at least two sets (4, 5) of die elements (6), each set (4,5) including a plurality of die elements (6) respectively arranged to travel along corresponding endless path. The paths each include a forming portion (9,10) in which die elements (6) of each set (4. 5) are opposed to define a forming space (11) therebetween. The forming portion (9, 10) of each path is configured so that one or more dimensions of the forming space (11) reduce along the length of the forming portion (9,10) to simultaneously apply lateral forces to material progressing through the forming portion.

An apparatus for forming the profile of deformable materials including tubular sections. The apparatus (1) includes at least two sets (4, 5) of die elements (6), each set (4,5) including a plurality of die elements (6) respectively arranged to travel along corresponding endless path. The paths each include a forming portion (9,10) in which die elements (6) of each set (4. 5) are opposed to define a forming space (11) therebetween. The forming portion (9, 10) of each path is configured so that one or more dimensions of the forming space (11) reduce along the length of the forming portion (9,10) to simultaneously apply lateral forces to material progressing through the forming portion.

A method for manufacturing a double pipe includes: drawing a plate (1), which has a predetermined shape corresponding to the desired final shape of a curved outer pipe (4), into a curved, substantially U-shape in cross-section to produce a half pipe (2). Then, an inner pipe (3), which has a curved shape similar to the desired final curved shape of the outer pipe, is inserted into and positioned within the interior space of the half pipe. Subsequently, the inner pipe is welded to the half pipe at one longitudinal end thereof. Thereafter, longitudinally-extending edges of the half pipe are curled towards each other until they abut and a substantially circular cross-section is formed that surrounds the exterior of the inner pipe. The abutting longitudinally-extending edges (22) of the half pipe are then welded together to produce the curved outer pipe (4).

A striking mechanism device for a hand-held power tool has at least one hammer tube, in particular made of sheet metal. The hammer tube is provided to guide a hammer and/or a drive piston. The hammer tube is seam-freely longitudinally slit over at least substantially the entire longitudinal extent of the hammer tube.