Finite Element Analysis and Life Prediction of Pre-stressed Composed Dies in Cold Extrusion Process

Improving and stabilizing the life of the die has always been the key to increasing the output of cold precision forging products and reducing the production cost of forgings. The stress state in pre-stressed composed dies during cold extrusion process is investigated in this paper, it shows that the combined die can greatly reduce the tangential tensile stress of the inner wall of the die and reduce the strain energy density of the die, thereby improving the strength of the die and extending the life of the die. By increasing the number of pre-stressed rings, the amount of interference can be changed, which indirectly changes the pre-stress applied to the die. The relationship between the die fatigue life and the number of pre-stressed rings indicates that the design of the pre-stressed composed structure above the inflection point is an excess design, and the optimal design should be near the inflection point.

Study on Plasticity Shaped Technics of Speed-Down Gears of New Type Tractor

Extrusion for tractor speed-down gears with big modulus have big distortion resistance , dentiform cavity filled difficulty and the service life of die low etc technology difficult problem , a method dividing the material flow in dentiform cavity of concave model was put forward ,and combining with floating die technology ,working-out extrusion new technics , the experiment results show that this shaped technics is beneficial for improving the corner filled capability and decreasing the shaped load 50% significantly, increasing the service life of die，the finished forging parts needs only a bit turning or grinding on excircle , can get qualified parts and would not harm the fibrous tissue of the teeth, have driven cold precision forging of spur gear with big modulus into practice.

Study on Cold Precision Forging of Non Straight Wall Cavity Piston

Brake piston is a huge demand non straight wall cavity part for the typical automotive industry; the traditional processing method is machine processing, or preforming by cold extrusion, and then machining. In this paper, the combined cold precision forging method of cold extrusion and spinning was proposed, which might improve the overall performance of parts and reduce costs. The rigid plastic finite element model of cold extrusion and spinning was established to simulate the forming process. The results showed that the combined cold precision forging method was available to manufacture non-straight wall cavity piston.

Study on the Large Module Spur Gear Cold Forming Process by Means of Numerical Simulation

The cold forging process of large module spur gear with four modules and 59mm breadth is performed by means of numerical simulation method. Two processes to forming such spur gears were compared by the simulation method, one is with the closed-die performing and extrusion in the finish-forging, the other is with divided-flow method in the finish-forging. Especially, the divided-flow method is analyzed in detail. The necessary reference and basis to realize practical cold precision forging process of spur gear with large modulus is provided eventually.

Research on Warm-Cold Precision Forging Process and Numerical Simulation for Spherical Housing

The warm-cold forming process is researched for complex-DOJ-type spherical housing by means of numerical simulation. Each step of the process is simulated, especially for the reverse extrusion process. Focusing on analysis of the material flow, temperature distribution as well as the load curve, a reasonable process for DOJ-type spherical housing is obtained. The reasonable forming process for DOJ-typed spherical housing offers favorable basis for forming and mold design.