Method for extrusion of block e.g. chrome-plated steel block, of central mandrel for manufacturing seamless pipe, involves introducing block into extruding device, pressing block over mandrel, and fixing mandrel against die during pressing

摘要

The method involves providing a block made from iron base alloy i.e. chrome-plated steel, or nickel base alloy. The block is introduced into an extruding device with a central mandrel. The block is pressed over the mandrel by a die. The mandrel is fixed against the die during pressing the block. The mandrel is provided with a mandrel tip that is releasably connected with a mandrel body, where the mandrel comprises a coating (4) e.g. scale coating such as ceramic coating and/or coating with coated metal alloy and/or cemented carbide. The portion of the block is lubricated by a lubricant based on glass and/or phosphate and/or graphite.