1 Introduction There are many types of high-voltage switch product parts and frequent modifications. The tie rod is a key part of the LW8-35SF6 outdoor circuit breaker, which requires high electrical conductivity, thermal conductivity and good mechanical properties to reduce the risk of Low energy consumption and improved product reliability. Aluminum alloy materials not only have good electrical and thermal conductivity and excellent mechanical properties, but also have high specific strength and low density. Therefore, in the manufacturing of high-voltage electrical components, in addition to copper and its alloys, a large amount of aluminum is used alloy. Research shows that functional parts with high comprehensive performance requirements, such as tie rods, joints, conductors, contact seats, etc., are generally made of aluminum alloy extruded rods (tubes) by cutting. 2A50 alloy is one of the commonly used materials. one. 2A50 alloy has good plasticity in the hot state. It can improve the structure and performance through deformation processes such as casting and extrusion. It can also be strengthened by heat treatment and has good processability. Therefore, it has become the first choice material for high-voltage switch parts. The extruded part of the tie rod is shown in Figure 1. Traditionally, it is made by direct cutting of bar stock. The material utilization rate is generally 16%-40%, resulting in serious waste and low efficiency. The new process adopts a composite hot extrusion method of reverse extrusion of the rod part and forward extrusion of the head part, which can greatly improve the dimensional accuracy of the blank, reduce the weight of the blank by more than 72%, and the conductivity, hardness and strength of the product fully meet the design standards. 2. Analysis of hot extrusion process of tie rod. The material of tie rod parts is 2A50 (LD5) alloy, which belongs to the A1-Mg-Si-Cu system. It has good forging performance, is easy to deform in the hot state, and has good corrosion resistance, welding performance and cutting performance. Good, medium strength, good plasticity. During the production process, the surface of the cylindrical blank is coated with aqueous graphite, then induction heated to 490°C, and put into the die of the combined die for extrusion. Preheat the mold to about 250°C before work, and spray lubricant into the mold cavity before each extrusion. After extrusion deformation, solution aging heat treatment can be performed to improve its hardness. The solution temperature is (515±5) ℃ and the time is 3h. The aging temperature is (160±5) ℃ and the time is 5h. Tie rod extrusion can use forward extrusion or reverse extrusion to form the rod. Since the deformation of the tie rod is large and the length-to-diameter ratio of the rod is greater than 7, during forward extrusion, the flow direction of the metal is the same as the movement direction of the punch. There is friction between the blank and the die, so there is not only deformation force in the extrusion force, but also the deformation force in the extrusion force. This friction force is also included. When the temperature of the blank and the die is too high and the lubrication is poor, the extrusion force will be further increased due to relative movement between the blank and the die. Since the rod of this part is long, it is prone to instability and bending during direct ejection. If the structure of the indirect ejection mold is complex, the operation will be more difficult.

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