| 摘要 |
1,168,385. Extruding. MANNESMANN A.G. 10 April, 1968 [12 April, 1967], No. 17167/68. Heading B3P. In an extrusion process the workpiece is coated with a material having a softening interval such as glass and the pressing tool is lubricated with a material having a fixed melting point. The glass is formed by applying a glass forming powder containing silica gel, boron oxide and sodium chloride to a heated workpiece. The sodium chloride reacts with any oxide formed on the workpiece and in the case of steel workpieces ferric chloride is formed which is volatile. A plate of annealed sodium carbonate is positioned between the workpiece and the tool to lubricate the tool. A sodium-rich glass forms on the workpiece after forging and it can be removed by hydraulic descaling. |
