A novel design of extrusion container for large steel tube extrusion process

Abstract

Extrusion container is the most important tooling in steel hot extrusion processing. Traditional designs such as the multilayered cylinder are difficult to execute for large extrusion containers. A novel design is proposed in this article, a salient feature of which is that the container employs steel wire winding technology. The primary difficulty of applying wire winding to the design of extrusion container is that the container should be heated to 350 °C while the temperature of steel wire cannot exceed 75 °C due to accelerated creep and stress relaxation at high temperature. In addition, the prestress generated by steel wire should fulfill the requirements necessary for the container. The proposed design should meet both goals. The functional requirements including preheating, protection of steel wire from high temperature, and stress distribution are discussed, and solutions are proposed. A new method to generate prestress called thermally induced prestress is introduced and detailed. To verify the design, a proof-of-concept prototype model was fabricated and tested. Results showed that the container using the proposed design could meet the expected prestressing goals, and the temperature of the wire would not exceed the limit and can offer an alternative to conventional design methods of extrusion containers.