Piston rod forgings are widely used in automobiles, compressors, hydraulic lifting devices and other occasions, its working environment is complex, in the execution of reciprocating movement, not only to bear the load and impact load, and reciprocating external work at a certain speed. Its performance is related to the normal operation of the equipment and the personal safety of the staff, how to improve the processing technology of the piston rod to improve the mechanical properties and life of the piston rod as much as possible is particularly important.
Piston rod forgings are axisymmetric forgings with deep blind holes. The traditional processes for producing such forgings include machining, casting and free forging. The mechanical properties of the parts produced by traditional technology are not only difficult to guarantee, but also have many problems such as low material utilization rate. As a net near forming method, hot extrusion overcomes many shortcomings of traditional technology, but there are still some shortcomings in forming deep hole piston rod forgings, such as uneven distribution of punch temperature field and underfilling of forgings.
The hot extrusion process of deep hole piston rod forgings is studied by means of numerical simulation and physical experiment. In this paper, the structural characteristics of deep hole piston rod forgings are analyzed, and the influence of one-step extrusion process on forming quality, die temperature field and forming force of forgings is analyzed by using DEFORM-3D finite element software. In addition, the paper also carried out a physical experiment on the one-step extrusion process, and the simulation results were compared with the physical experiment results, which verified the correctness of the numerical simulation. The influence of different process parameters on forging forming was studied by single factor rotation method. Aiming at the condition of underfilling of FORgings in the process of single extrusion, a two-step forming process was introduced to design two kinds of premade cone bottom shapes, and numerical simulation analysis was carried out on different cone bottom shapes and sizes of premade billets, and reasonable cone bottom shapes and sizes of premade billets were obtained. Aiming at the problem that punch failure is easy to occur during hot extrusion of deep hole piston rod forgings, the causes of die failure are analyzed and the stepwise extrusion criterion is determined. In addition, according to the determined step criteria, taking the forming punch of the piston rod forgings as the research object, DEFORM-2D finite element software was used to determine the reasonable step extrusion times.