Abstract: A core unit is moved into position within the mold halves of an injection mold and a casting is molded therein. The outer wall zones of the casting are cooled sufficiently to enable the casting to maintain its shape. At the beginning of the shrinking of the casting and while the inner wall zones of the casting are still in the plastic state but before any stresses are set up in the casting the divided mold is opened. The core and the casting thereon are removed from the mold to a cooling station where the casting is rapidly cooled and the core is then removed from the cooled casting. A corrugation can be formed in a tubular casting by positioning a ferromagnetic insert member upon the core and establishing a magnetic field to maintain the insert member in position during the casting process. The core can be provided with permanent magnets or electromagnets to hold the insert member in position.

Abstract: .Iadd.Apparatus to produce widenings at tube ends with precise dimension of the inner surfaces of the widened zone which includes a holding device for the tube to be worked, a variable form core arranged axially in front of the center of the holding device, a device for axially displacement of the core, a cylinder axially movable over the tube for exterior calibration and adaptation of the tube end to the core, and a device to bring the core to a shape in which it can be drawn from the formed tube end. .Iaddend.