Provided is a clad welded pipe or tube that has improved pipe or tube mechanical properties by reducing the width of a weld without its function as a clad pipe or tube being impaired. A clad welded pipe or tube comprises: a first layer made of base metal; and a second layer placed on one surface of the first layer, and made of first cladding metal that is a material different from the base metal, wherein a pipe or tube circumferential length L1 of weld metal at a pipe or tube inner surface and a pipe or tube circumferential length L2 of the weld metal at a pipe or tube outer surface in a weld are each 0.0010 mm or more and 1.0 mm or less, and the base metal is not exposed at a first cladding metal-side surface of the clad welded pipe or tube in the weld.

Provided are a press forming method capable of improving material yield while avoiding the risk of dimensional error increase at product forming sections in blank material when carrying out press forming, and a plate material expansion device used in this method. An end side of plate material for press forming is restricted by blank holding rollers, and pressure is applied to a middle location in the part that is restricted by a pressure roller. In this state, the plate material is transported in a rotating direction of the rollers being driven to continuously bend and extend the section receiving pressure. This bent and extended section is flattened with a flattening roller to obtain blank material wherein an end part is expanded.

Tubular structures, systems, and methods are generally directed to support structures having structural properties similar to thick-walled structures while being formed using materials having thickness amendable to rolling and welding and, thus, useful for rapid and cost-effective fabrication.

A method for manufacturing a hot-rolled steel sheet having a large thickness and a large width, a larger sheet width and a lower temperature can stably be cut at a cutting load equal to that of a conventional steel sheet having a usual sheet thickness, a usual sheet width and a usual temperature. In a rough rolling step, the steel sheet is formed so that the shortest length L (mm) from a concave portion bottom to a convex portion top of the fishtail shape satisfies Equation (1) mentioned below, and an intermediate portion between the concave portion bottom and the convex portion top, defined as a desired cutting location, is cut:
(2X+30)L300(1),
in which X is a maximum deviation (mm) of the cutting location of a crop cutting machine and 0X90.

A press forming method is capable of improving material yield while avoiding the risk of dimensional error increase at product forming sections in blank material when carrying out press forming, and a plate material expansion device is used in this method. An end side of plate material for press forming is restricted by blank holding rollers, and pressure is applied to a middle location in the part that is restricted by a pressure roller. In this state, the plate material is transported in a rotating direction of the rollers being driven to continuously bend and extend the section receiving pressure. This bent and extended section is flattened with a flattening roller to obtain blank material wherein an end part is expanded.

Provided is a clad welded pipe or tube that has improved pipe or tube mechanical properties by reducing the width of a weld without its function as a clad pipe or tube being impaired. A clad welded pipe or tube comprises: a first layer made of base metal; and a second layer placed on one surface of the first layer, and made of first cladding metal that is a material different from the base metal, wherein a pipe or tube circumferential length L1 of weld metal at a pipe or tube inner surface and a pipe or tube circumferential length L2 of the weld metal at a pipe or tube outer surface in a weld are each 0.0010 mm or more and 1.0 mm or less, and the base metal is not exposed at a first cladding metal-side surface of the clad welded pipe or tube in the weld.

A cross edge rolling process for increasing a thickness of a strip in longitudinal edge strips on both longitudinal sides of the strip. According to the invention, this is achieved in that firstly a step extending in the longitudinal direction of the strip is produced by means of a roll profiling process, wherein the strip is supported during the cross edge rolling process on said step against a compression force acting transversely to the strip, so that the strip is not compressed outside the longitudinal edge strip. After the edging process for increasing the thickness of the longitudinal edge strips, the strip is bent by means of a roll profiling process to form a C-profile rail.

A method for manufacturing a hot-rolled steel sheet having a large thickness and a large width, a larger sheet width and a lower temperature can stably be cut at a cutting load equal to that of a conventional steel sheet having a usual sheet thickness, a usual sheet width and a usual temperature. In a rough rolling step, the steel sheet is formed so that the shortest length L (mm) from a concave portion bottom to a convex portion top of the fishtail shape satisfies Equation (1) mentioned below, and an intermediate portion between the concave portion bottom and the convex portion top, defined as a desired cutting location, is cut:

(2X+30)L300(1),

in which X is a maximum deviation (mm) of the cutting location of a crop cutting machine and 0X90.

According to one aspect, a tubular structure may include a base and a wrap. The base may have a first surface and second surface opposite one another, the first surface defining an elongate cavity, and the base having a tubular shape defining a longitudinal axis extending along the elongate cavity. The wrap may be supported on the second surface of the base, the wrap including a plurality of layers, and each layer having a first longitudinal edge and a second longitudinal edge coupled to one another along a respective spiral seam associated with the given layer and extending about the longitudinal axis of the base.

A cross edge rolling process for increasing a thickness of a strip in longitudinal edge strips on both longitudinal sides of the strip. According to the invention, this is achieved in that firstly a step extending in the longitudinal direction of the strip is produced by means of a roll profiling process, wherein the strip is supported during the cross edge rolling process on said step against a compression force acting transversely to the strip, so that the strip is not compressed outside the longitudinal edge strip. After the edging process for increasing the thickness of the longitudinal edge strips, the strip is bent by means of a roll profiling process to form a C-profile rail.