Study On Forming Technology Of Deep Hole Piston Rod Forging

The piston rod is widely used in automobiles, compressors, hydraulic lifting devices,etc. Its working environment is so complex, when executing reciprocating motion, it hasto withstand the load and impact load at the same time, and has to work at a certain speedreciprocatedly as well. The performance of piston rod is related to the normal operation ofthe equipment and the personal safety of staff, so how to improve the processingtechnology of the piston rod, improve the mechanical properties and life of the piston rodas much as possible is particularly important.Piston rod forgings is a kind of forgings with deep blind hole in axial direction,traditional processes for producing such forgings are machining, casting, free forging andetc, which not only cannot guarantee the mechanical properties of products, but also existmany problems like low material utilization. Hot extrusion as a net nearly forming method,overcomes many disadvantages existing in the traditional process, but still exists manyproblems such as uneven temperature distribution of punch, under-fill, etc. In this articlecombining the method of numerical simulation and physical experiment, the hot extrusionforming process of deep hole piston rod forgings are studied.Firstly, analyzing structure characteristics of the deep hole piston rod forging, usingthe finite element software Deform-3d, the influence of one step extrusion formingprocess on forgings’ forming quality and die life was researched in this paper. In addition,physical experiments about one step extrusion forming technology were also conducted,simulation results and experiments results were compared with each other, the validity ofthe numerical simulation was verified.Then, using the single factor alternate method, the influence of different factors ofone step extrusion forming process on the forming of piston rod were studied. Beside, thetwo-step forming process was introduced, two kinds of pre blockings with cone bottomwere designed against the disadvantages of one step extrusion forming process, and theshape and size of the cone bottom were also analyzed by numerical simulation, the reasonable pre blocking shape and size was determinedAt last, against the problem of uneven temperature distribution of punch, theprinciples for step-by-step extrusion were determined by analyzing the reasons of diefailure. In addition, according to above principles, regarding the punch of piston rodforging as the research object, adopting the finite element software Deform-2d, reasonableextrusion steps were determined.