A tubular structure is disclosed. The tubular structure has a first sheet metal having a machine direction. The first sheet metal is convolutely wound about a longitudinal axis and has a tail portion. The tail portion of the first sheet metal is disposed upon and bonded to an immediately subjacent convolution of the first sheet metal.

An elongate tubular structure is disclosed. The elongate tubular structure has a first and second tubular structure wherein a first end of the first tubular structure is matingly and fasteningly engaged to a first end of the second tubular structure. The first and second tubular structures each have a first sheet metal having a machine direction being convolutely wound about a first longitudinal axis. The first sheet metal has a tail portion that is disposed upon and bonded to an immediately subjacent convolution of the first sheet metal to form the respective first and second tubular structures.

A method of progressive processing includes feeding a strip-shaped sheet to a press machine; pressing the strip-shaped sheet with the press machine; and joining the strip-shaped sheet with a new strip-shaped sheet by applying a tape over an end of the strip-shaped sheet located in a direction opposite a direction in which the strip-shaped sheet is fed and an end of the new strip-shaped sheet located in a direction in which the new strip-shaped sheet is fed.

A stitcher (1) for connecting an end portion of an outgoing metal strip to a starting portion of an incoming metal strip for a continuously operated strip processing system comprises a first punching tool (20), which is designed to connect metal strips having a first thickness range and/or strength range to one another, and a second punching tool (30), which is designed to connect metal strips having a second thickness range and/or strength range to one another. Both thickness ranges and/or strength ranges are different from one another.

To solve the problems of conventional wire billet butt-welding such as high labor intensity, potential safety hazards, and low production efficiency, the disclosure provides a wire billet butt-welding apparatus and a wire billet butt-welding method. The wire billet butt-welding method comprises: S1: preparing a stock, S2: rotating a butt-welding stock receiver to a stock receiving position, and feeding a first coil of wire billet to a stock receiving rod of the butt-welding stock receiver; S3: welding the first coil of wire billet and the second coil of wire billet on a rotary plate at the butt-welding position end-to-head; S4: rotating the butt-welding stock receiver and the second coil of wire billet to the stock receiving position; S5: rotating the stock receiving rod to rotate to tighten the wire billet between the first coil of wire billet and the second coil of wire billet; and S6: repeating steps S3 to S5 to complete butt-welding operations on the 3.sup.rd to n.sup.th coils of wire billet sequentially. The solution implements semi-automated butt-welding operation; with provision of the rotary plate and the butt-welding stock receiver, enables automatic loading, automatic flipping, and automatic discharging, which reduces the manual workload, lowers the safety hazards, and improves the production efficiency.

A method of joining strip-shaped sheets includes a support step of placing a support member in contact with a reverse feed direction end of a strip-shaped sheet fed to a pressing machine and a feed direction end of a new strip-shaped sheet, and a joining step of joining the new strip-shaped sheet to the strip-shaped sheet by attaching a tape on the reverse feed direction end of the strip-shaped sheet and the feed direction end of the new strip-shaped sheet, wherein in the joining step, the tape is attached from a side opposite the support member with the support member placed in contact with the reverse feed direction end of the strip-shaped sheet and the feed direction end of the new strip-shaped sheet. The problem of the variation in welding quality encountered when welding thin and wide strip-shaped sheets together is resolved and the strip-shaped sheet is fed smoothly.

A wire billet butt-welding apparatus and a wire billet butt-welding method, the method including: S1: preparing a stock, S2: rotating a butt-welding stock receiver to a stock receiving position, and feeding a first coil of wire billet to a stock receiving rod of the butt-welding stock receiver; S3: welding the first coil of wire billet and the second coil of wire billet on a rotary plate at the butt-welding position end-to-head; S4: rotating the butt-welding stock receiver and the second coil of wire billet to the stock receiving position; S5: rotating the stock receiving rod to rotate to tighten the wire billet between the first coil of wire billet and the second coil of wire billet; and S6: repeating steps S3 to S5 to complete butt-welding operations on the 3.sup.rd to n.sup.th coils of wire billet sequentially.

A first recessing-and-projecting line is formed in a trailing end of a preceding first belt material and a second recessing-and-projecting line is formed in a leading end of a newly fed out second belt material, and the first recessing-and-projecting line and the second recessing-and-projecting line are fitted to each other, thereby joining the first belt material and the second belt material. Note that the first recessing-and-projecting line and the second recessing-and-projecting line pass through a holding section that holds an element in the first belt material or the second belt material.

A method of joining strip-shaped sheets includes a support step of placing a support member in contact with a reverse feed direction end of a strip-shaped sheet fed to a pressing machine and a feed direction end of a new strip-shaped sheet, and a joining step of joining the new strip-shaped sheet to the strip-shaped sheet by attaching a tape on the reverse feed direction end of the strip-shaped sheet and the feed direction end of the new strip-shaped sheet, wherein in the joining step, the tape is attached from a side opposite the support member with the support member placed in contact with the reverse feed direction end of the strip-shaped sheet and the feed direction end of the new strip-shaped sheet. The problem of the variation in welding quality encountered when welding thin and wide strip-shaped sheets together is resolved and the strip-shaped sheet is fed smoothly.

A trailing end of a leading metal strip is joined to a leading end of a trailing metal strip by first overlapping the leading end of the trailing strip with the trailing end of the leading strip and then clinching the ends together at the overlap by pressing at least one punch of a joining tool into one of the strips at the overlap sufficiently to complementarily deform both of the strips. The thickness of the leading and trailing ends is measured and a depth of engagement of the punch into the strips is controlled in accordance with the measured thickness.