Abstract: It was discovered that a rolling mandrel holding a hollow which is rolled in a multistrand mill should be advanced in a particular manner that relates to the stretching the hollow undergoes in the first and second stand, as well as to the speed of the unrolled hollow. A velocity profile has been developed accordingly.

Abstract: A mechanical pipe expander for a step-by-step expanding of steel pipes formed with a spiral welded seam. The expander includes an expander head that performs the expanding made up of circumferentially arranged segments over which the pipe assumes a circumjacent position and after which the segments move radially outward to forcibly engage the inside of the pipe. In order to avoid the segments contacting the inside welded seams of the pipe, the segments are formed with one or more complementary spiral slots and if the pipe has cross welded seams with one or more corresponding cross spiral slots.

Abstract: A hold down device is disclosed suitable for an edge planing machine for working sheet metal. The hold down device has a plurality of hold down elements arranged in the direction of movement of the sheet metal and in a laterally overlapping relation. A plurality of piston cylinder units are provided and a single hydraulic cylinder is associated with and connected to each element for pressing it down against the sheet metal to be worked. The lateral surfaces of the elements facing the plate edge are in alignment with each other. The piston rod of the hydraulic drives are connected to the middle of each element for swivel action. The individual elements may either have an essentially rhomboidal or Z-shaped plan view. A further improvement adds spring forces and guidance to the hold down action.