A pre-stretching roller of an unwinding apparatus, associable to a wrapping machine, includes a main body elongated and manufactured by an extrusion process of a metal alloy. The main body includes a first tubular element having a cylindrical shape and defining an external cylindrical wall for interacting with a film, a second tubular element internal to the first tubular element and having a first end provided with a first seat suitable for coupling with a driving shaft of a driving unit and an opposite second end provided with a second seat suitable for coupling with a supporting pin for fixing the pre-stretching roller to the unwinding apparatus, and a plurality of longitudinal vanes which connect the first tubular element to the second tubular element. The second tubular element has a plurality of longitudinal ribs, each connected to a respective longitudinal vane.

Method for manufacturing a tube of metal in which sensors are attached to tubes, which register and signal a damage of the tube. It is detrimental that protection of the sensors at these tubes against environmental influences is complex. In contrast, it is an object of the present disclosure to provide a method for manufacturing a tube, in which the signal line can be protectively mounted. To solve this object, a method for manufacturing a tube of metal is suggested with an outer tube and an inner tube, wherein a groove is drawn in an inner surface of the outer tube or in an outer surface of the inner tube and subsequently the inner tube and the outer tube are drawn together through a drawing die, wherein the inner dimension of the outer tube is reduced such that after the drawing the outer tube is force-fitted onto the inner tube.

An article of furniture may include a component such as a frame, leg, or support. The component may be constructed from a strip of material and the strip of material may include a strip length, a strip width, and a strip thickness. The component may include a longitudinal welding joint that may be disposed between a first strip end or a first strip side and a second strip end or second strip side. A profile may be embossed into a surface of the strip of material and the component may be manufactured in a continuous inline roll forming process.

A device for forming a tubular hollow body has a forming die, a mandrel and a forming drive with a die drive. Die profile projections arranged on the outer side of a hollow body wall and mandrel profile intermediate spaces arranged on the inner side of the hollow body wall as well as die profile intermediate spaces arranged on outer side of the hollow body wall and mandrel profile projections arranged on the inner side of the hollow body wall lie opposite to each other on the hollow body wall in the radial direction. A method for forming a tubular hollow body involves moving the forming die along the hollow body axis, and by exceeding of the flow limit of the material of the hollow body wall, material of the hollow body wall flows into the mandrel profile intermediate spaces, forming an inner profile of the hollow body wall.