Research On The Characteristic Of Uniform Deformation Of Radial Expansion- Closed Control Extrusion

Traditional backward extrusion forming with center hole cylindrical parts adopts anti-extrusion and machining hole. The forming process requires the squeeze pressure and present the deformation of different position of the cylinder body is not uniform, at the bottom of the worst performance problems. To solve these problems, we developed radial expansion-closed control extrusion technology. In this paper, with the numerical simulation and experimental verification, a study on the deformation uniformity of the radial expansion-closed control of the center with a hole in the extrusion process is carried out.By introducing the radial expansion-closed control extrusion. The DEFORM simulation software was used to compare the metal flow, the effect of deformation and the distribution of grain size at the bottom of the die, and the percentage distribution of dynamic recrystallization in the bottom of the cylinder. The results show that through radial expansion-closed control extrusion, greatly improving the deformation at the bottom of the cylinder body, forming the bottom member average etc. effects increased 2 times, grains are refined obviously.Through secondary development, 7A04 high-strength aluminum alloy material information is added into deform; establish good 7A04 aluminum alloy critical strain and microstructure evolution model is embedded into the software subroutine using FORTRAN language, lay the foundation for the simulation of the microstructure evolution of the alloy during the deformation process.Based on the simulation of radial expansion and receiving control in the process of extrusion expansion, according to the gradient effect of cylinder parts and so on, damage value and uniform distribution of grain and dynamic recrystallization distribution of forming cylindrical workpiece deformation uniformity were evaluated, the effect of process parameters is found.Finally according to the research results, 20 Inch aluminum alloy wheel rim was successfully developed on the 12.5MN hydraulic press. Obtained mechanical properties at room temperature using INSTRON-3382 static testing machine, found that the comprehensive mechanical performance is enhanced greatly; use 200HRS-150 digital Rockwell hardness tester hardness test on each part of the rim, the results show that the hardness gradient difference is small, which shows that the uniformity of the rim is obviously increased. It has played a very good role in the promotion of this technology in the future.