Blanking of head plate

　　In order to ensure that there is a margin in the height direction after the head is formed, the blank is blanked at 1850mm when blanking, and the appearance and size of the head plate are confirmed after blanking. If there are defects such as scratches, bumps, etc., strictly follow the relevant standards Perform repair welding and non-destructive inspection.

　　Mold selection and requirements

　　The caliber of the thermoformed head usually shrinks after cooling, and the straight section thickens. Therefore, when choosing a mold, it is usually larger than the theoretical inner diameter of the head. The size of the upper tire is generally the same as the inner diameter of the head, and the inner diameter of the lower tire is appropriately enlarged. Based on experience, the upper tire is 1450mm and the lower tire is 1500mm. In addition, in order to reduce the pollution of the stainless steel inner surface of the head and bumps during the pressing process, the upper and lower mold surfaces should be cleaned and polished before the head is formed, and the contact edge of the mold and the head plate should be painted. High temperature resistant lubricating oil, to ensure that the contact surface is clean and smooth.

　　Head pressure type

　　The heating temperature, holding time and shelling temperature of the head should be strictly controlled during the pressing process. Put the head plate and test plate into a gas heating furnace for heating at the same time. The heating temperature is 1080±20℃, and the heat preservation is 0.5h. When the furnace is out of the furnace, the measured temperature is 1070℃ with an infrared thermometer. Use a forklift to quickly transfer the head plate to the hydraulic press On the mold, adjust the center of the head plate to align with the center of the mold to complete the molding at one time. The temperature measurement before molding is 1050℃, and the temperature measurement for shelling (final pressure) is 980℃, avoiding the dual phase of the coating material. In the high temperature embrittlement zone (<950℃) of stainless steel, the temperature nodes are well controlled.

　　Head spray

　　After the hot-pressing of the head is completed, it will be quickly cooled together with the test plate. The slow cooling will cause the precipitation of brittle phases, which will result in the decrease of the toughness and corrosion resistance of the steel. Therefore, multiple nozzles are used to spray uniformly on the inner and outer surfaces of the head to speed up the cooling rate, so that the coated dual-phase steel is equivalent to solid solution, and the base carbon steel is equivalent to normalizing.