Hot extrusion

Extrusion is the application of an external force to a metal blank placed in a container (squeezing cylinder) to flow out of a specific die hole to obtain a desired cross-sectional shape and size – mainly for stainless steel, nickel-based superalloys and hard The bar, tube and profile of the molten alloy are different from the traditional steel materials and non-ferrous materials. The production of the waste pipe is carried out by the rolling perforation process. The production of the 690 alloy seamless pipe is mainly by hot extrusion molding. Figure 1-4 is the alloy 690. Simplified drawing of the hot extrusion process of the waste pipe. The production of seamless tubes by hot extrusion requires that the tube blanks be hollow blanks, and the hot-extruded hollow tubes are obtained by firstly drilling and then inductively heating and expanding the holes. After the reaming of the hollow shell temperature, the temperature is raised to the set preheating temperature of the billet, and the glass gasket capable of lubricating is placed on the extrusion mold, and the glass powder is used for the hollow shell blank. The inner and outer surfaces are lubricated. The preheated glass powder lubricated tube blank is transported to the loading table near the extrusion barrel, then rolled into the trough between the extrusion barrel and the plunger, and the extrusion gasket is transported into the trough and close to the trough After the blank, the extrusion rod moves slowly and is close to the pressing pad, the extruded mandrel is extended, and the blank, the pressing gasket and the extruded core rod are connected together. The extrusion rod moves forward under a low extrusion pressure, and the blank is sent into the extrusion cylinder, and the trough automatically descends. As the pressing force increases, the extrusion rod gradually moves forward, and the pre-extrusion is performed first. The gap between the tube blank and the extrusion barrel, and then the blank is extruded from the gap between the extrusion die and the extruded mandrel. During this process, the glass gasket gradually softens after contact with the hot billet, and a glass lubricating film is formed on the surface of the billet. The squeeze bar continues to move forward under a large squeezing force until a short remainder of material remains, completing a hot extrusion.