Study On Processing Method For Cold Extrusion In Internal Thread Of Knuckle Axis

The study of this paper is combined with the exploitation and the manufacture of internal thread of C195 knuckle axis of automobile. The crisis problem of processing is internal threads forming. Although cutting is the conventional method used for internal maching, it is not only inefficient but also cuts off the metal wools and reduces the internal thread quality. Extrusion processing of internal threads is a advanced processing technology with little chip or even chipless. It makes the metal wools continuous, and increases the draw-resistance intensity and fatigue-resistance of the internal threads. Cold extrusion processing of internal threads is studied deeply through combined with the finite element method simulation and experiments in the paper.At first, techniques characteristic of cold extrusion processing of internal threads is analyzed, and the deformed discipline of metal material are studied, that is extrusion forming of internal thread is a process of partial forming, material flowing in the diameter direction, on the other hand, material flowing in the axial direction, as well as the axial strain being the biggest strain, make it very difficult to form than other forming method. Then, according to techniques characteristic of cold extrusion processing, the results are concluded that the structure of extrusion tap, diameter of prefabricate hole, extrusion speed and the selection of lubricating oil is the main influencing factions of cold extrusion processing of internal threads. Then, the structure and the parameter of extrusion tap is determine, and formula of diameter of prefabricate hole is deducted through theory calculation when the internal thread is machined by cold extrusion processing.In this paper, the processing discipline of cold extrusion processing of internal threads is analyzed by DEF0RM-3D (a finite element method simulation software), and the variational discipline of extrusion torque is simulated when diameter of prefabricate hole and extrusion speed is vary. Finally, the best values of the diameter of prefabricate hole and extrusion speed is determined through optimize simulation results,In the end, forming experiments study of cold extrusion is processed, experiments results shows that internal thread of C195 knuckle axis can be formed by cold extrusion method, and the extrusion torque is varied when diameter of prefabricate hole and extrusion speed is a series of different value.Theory of cold extrusion processing of internal threads, FEM simulation andmould CAD/CAM/CAE are integrated through the research, which helps to increased productivity, shorten developing periods and prolonged life-span of extrusion taps, the research of the paper provide the better theory and practice experience for cold extrusion of internal thread.