Abstract: A method and apparatus for manufacturing a plug-type chamber to accommodate at least two floating plugs for use in the cascade drawing of tubes is disclosed. A starting tube is first fixed in position by a clamping and denting device. A necking-down ring is subsequently moved with the help of a necking-down cylinder along a freely projecting end section of the starting tube. A punch is then pushed with the help of a cylinder into the end section of the tube. When the punch has reached its end position, the necking-down ring is pulled over the end section of the tube, and the outside diameter is reduced to its original size. The punch is subsequently removed, and two indentations are made on the periphery of the end section of the starting tube with the help of the clamping and denting device.

Abstract: A method for forming a protective layer on a copper surface is set forth. The surface of degreased strips or sheets of copper are roughened by mechanical treatment in a controlled manner. The roughened surfaces of the strips or sheets are then chemically treated to bring about a green patination. After the chemical treatment, the strips or sheets are stored in a climate-controlled space.

Abstract: A method for producing a uniform and adherent brown covering layer (brown patina) on surfaces of semifinished products made of copper, particularly on rolled tapes or sheets used in building construction. The surface of the copper semifinished product is first roughened by means of a mechanical treatment. The copper semifinished product is then heat treated at a temperature lying within the temperature range of 150.degree. to 650.degree. C. for the duration of 0.1 to 30 minutes. The copper semifinished product can be advantageously subjected to a chemical postoxidation treatment immediately following the heat treatment.

Abstract: Molds for continuous casting machines are made by providing a plurality of different tubular blanks of copper or copper based alloys; selecting a particular blank and feeding same to a first working station in which the blank is provided with a thrust mount such as a rim against which a mandrel to be inserted can abut during subsequent working; a particular mandrel is selected from among a plurality of stored mandrels and forced into the rimmed tubular blank; by means of a die, the tubular blank is forced onto the mandrel in all around, tight, surface to surface contact while preferably a normal orientation of the die is maintained in relation to the mandrel passing through; thereafter the mandrel is recovered from the blank and either returned to the station of mandrel insertion or to the mandrel store.