(1) During the extrusion process, the temperature of the inner lining of the spiral steel pipe increases continuously with the extrusion process. At the end of the extrusion, the temperature of the inner wall of the inner lining near the extrusion die is higher, reaching 631 °C. The temperature of the lining and the 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 preheated state, its maximum value is 286MPa, which is distributed in the middle of the inner wall surface of the lining. In the working state, its maximum equivalent stress is 952MPa, which is mainly distributed in the upper high-temperature area of the inner wall. The stress concentration area inside the spiral steel pipe is mainly distributed in the high-temperature area, and its distribution and temperature distribution are the same. The thermal stress generated by the temperature difference has a great influence 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 state of compressive stress in the radial direction, and the maximum 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, mainly concentrated in the upper part of the spiral steel pipe.