Metal extrusion has many important characteristics such as good variety diversity and large production flexibility. It is the industrial production of metal pipe, rod, wire and profile and various new materials and new products such as composite materials, powder materials, and high-performance difficult-to-process materials. Important method. With the rapid development of economic construction and high-tech, metal extrusion technology has developed rapidly. In the past ten years, my country has achieved world-renowned achievements in metal extrusion production, high-end product development, localization of heavy and super-heavy extrusion equipment and production line construction, and is currently actively developing new metal extrusion processes.
1. Isothermal extrusion technology.
In order to overcome the changes in product structure caused by temperature changes in the extrusion process and increase the extrusion speed, the isothermal extrusion process has been paid more and more attention. The methods to achieve isothermal extrusion include billet ladder heating/cooling, tool and mold temperature control, parameter optimization method, thermal model-based speed control, and temperature-speed online detection closed-loop control. Among them, the temperature-speed online detection closed-loop control has the best effect, but its implementation is more difficult, which is the ideal development direction of the isothermal extrusion process. The temperature-speed closed-loop control method is to measure the temperature change of the product at the exit of the die hole online during the extrusion process, feedback the measurement results, and adjust the extrusion speed accordingly in real time to achieve the purpose of isothermal extrusion. In addition to the effect of maintaining a certain temperature of the product hole at the die hole, temperature-speed closed-loop control is often notable compared to ordinary constant-speed extrusion in many cases because the speed of the initial and middle stages of extrusion is greatly increased Shorten the extrusion time, thereby improving production efficiency. However, due to the characteristics of the speed response frequency of the extruder and the non-linear shape of the extruder speed output, it is often difficult to obtain the ideal control effect. Therefore, the development of isothermal extrusion technology with joint control of multiple methods has attracted attention. By using a special structure of the extrusion die to control the flow of metal, various layered composite materials can be formed, some of which are difficult to even form using existing plastic processing methods, such as using two or more Materials to form the same coating layer (that is, a coating layer made of different materials welded together in the circumferential direction), simultaneous coating of more than two layers, multilayer composite tubes or hollow profiles, special layered composite materials, etc.
2. Multi-blank extrusion.
The multi-blank extrusion method is different from the case where only one billet is used in traditional extrusion, but a plurality of extrusion barrel holes are opened on a cylinder body according to needs, and blanks of the same size and material are loaded into each cylinder hole, Then squeeze simultaneously. In the additional bending extrusion method, the bending deformation device not only guides the movement direction of the profile, but also applies bending deformation to the profile after the extrusion die hole to obtain the desired arc profile. Therefore, the additional bending extrusion method is actually a combined extrusion-bending method.
3. Core extrusion.
In order to meet the needs of some special applications, such as slender special steel, high temperature alloy pipes, copper clad steel wire, etc., the core extrusion method is a simple and feasible method. If the core rod is replaced with a core material covering the wire, the resulting product is the covered wire. The biggest feature of core extrusion is that it can be realized on an ordinary extruder with an independent perforation system. It is developed on the basis of combining the characteristics of fixed needle extrusion and follower needle extrusion. In this method, the core rod or core material enters the die hole from the rear of the extruder through the hollow needle support and the hollow needle, and is driven out of the die synchronously with the extruded product by the friction force exerted by the extruded metal on the surface of the core rod hole.