What is the stress condition of spiral steel pipe during the extrusion process

(1) During the extrusion process, the temperature of the lining of the spiral steel pipe continues to increase as the extrusion process proceeds. At the end of the extrusion, the temperature in the area of the inner wall of the lining close to the extrusion die is relatively high, reaching 631°C. The temperature of the middle lining and outer cylinder does not change much.

(2) In the non-working state, the maximum equivalent stress of the spiral steel pipe is 243MPa, which is mainly concentrated on the inner wall of the spiral pipe. In the preheating state, its maximum value is 286MPa, distributed in the middle of the inner wall surface of the lining. Under working conditions, its maximum equivalent stress is 952MPa, which is mainly distributed in the high-temperature area at the upper end of the inner wall. The stress concentration area inside the spiral steel pipe is mainly distributed in the high-temperature area, and its distribution is the same as the temperature distribution. The thermal stress caused by the temperature difference has a greater impact on the internal stress distribution of the spiral steel pipe.

(3) The radial stress on the spiral steel pipe. In the non-working state, the spiral steel pipe is mainly affected by the prestress provided by the external prestress. The spiral steel pipe is in a compressive stress state in the radial direction. The largest value is 113MPa, which is distributed on the outer wall of the spiral steel pipe. In the preheating state, its maximum radial pressure is 124MPa, mainly concentrated on the upper and lower-end faces. In the working state, its maximum radial pressure is 337MPa, which is mainly concentrated in the upper-end area of the spiral steel pipe.