Bureau temperature alloy, 4169 bolt 镦 extrusion forming finite element simulation Zhang Xueyu, party and government. Qi Guangxia School of Materials Science and Engineering, Shenyang Institute of Technology, Shenyang 0016, Liaoning Province, China. Using the relevant finite element analysis, the soft cattle were successfully simulated on the high temperature alloy and 4169 bolts. The flow analysis of the deformed metal and the optimization design of the mold were realized. .

In recent years, with the widespread use of fire, computer, and the numerical method of limiting the effectiveness of the limit element method, it has become a powerful tool for studying the plastic processing theory. The finite element method can be used to simulate the metal deformation process, obtain the mechanical information of the deformed body in the forming of the scale, the mechanical information of the engraving, analyze the gold bending forming mechanism, and predict the forming defects, and propose the modification total for the mold setting process in time. Seven defects. High quality processing and production services. As a traditional plastic processing process, hot forging is also fully capable of realizing effective computer simulations using the finite element method.

1 Basic theory Hot forging is a typical metal hot working process, and the corresponding mathematical theory should be the rigid viscoplastic finite element method. The theoretical basis of the rigid viscoplastic finite element method is the variational principle of the river 31, which is described in all solutions that satisfy the velocity field allowed by the motion. The real solution makes the function take the extreme value. The volume-changing tea piece 6 is introduced, and the functional formula of the functional is the strain rate of the functional change of the functional.

Since the strain hardening effect is not significant during hot working, and has a large sensitivity to the deformation speed, it is necessary to consider strain in the material's Zhejiang force model, and to suppress the metal flow of the ring. Recognize 0, the type can not be jade and viscous flow.

After finite å…€ discretization, the non-linearity of the node velocity component is unknown, and the iteration is repeated for Equation 5 until the velocity error norm is ==1, which is defined as 7 or the node error edge is reached. Predict the specified value as 10.

2 Gang 4 accounted for the specific technology in the application of plastic finite element 2.1 Description of the mold shape The shape of the forging die is mostly smooth transition. In order to facilitate the processing of boundary conditions and release contact, a reasonable mathematical description must be used to process the mold of any shape. Most systems use a combination of several linear arcs and spline curves to describe the mold. If the finite element analysis software itself has limited modeling functions, the geometric modeling of complex objects can be borrowed from the special software, and then passed through the standard formula such as 1; 13, 51. Zhang, 0 0. Data conversion between systems.

2.2 Element Distortion and Grid Re-division The rigid viscoplastic finite element solves the problem of large plastic deformation. When the material flows, it is easy to cause excessive deformation of the corresponding element shape and cause distortion, so that the equal-differential transformation cannot be smoothly performed. In order to ensure the accuracy of the analysis results, the mesh must be subdivided in due course. The mesh re-division technique includes the following criteria: the judgment criterion of the degree of mesh distortion, that is, when to re-divide the mesh; 2 to generate a new grid system with reasonable degree of density in the current contour of the forging; 3 to perform new and old grids The inclusion test of the node determines the old cell where the new mesh node and the new cell center fall; 4 passes the historically related amount from the old grid system to the new grid system 1 into a new calculation file.

2.3 The treatment of frictional boundary conditions The frictional force can be limited by the inverse tangent function to the friction factor and the relative velocity of the upper part of the material can be recorded as 卞, where is the number of nodes on the element contact surface; Shape function; is the tangential relative sliding speed of the contact node along the die face. Thus, the contribution of friction to the element stiffness matrix and the load array is 2.4 generation of the initial velocity field. It is known that to iterate, an initial velocity field must be given. Usually an artificial velocity field is assumed artificially, but the initial velocity field given is often difficult to make, the iteration converges, and the analysis result cannot be obtained. At present, most finite element analysis software uses the direct iterative method to automatically generate the initial velocity field, which is different for forging. 1 household only needs to input the speed of the boundary contact point in the initial state. The system can be automatically transported to generate the initial velocity field, and then 1 in; 031; 0 15 demoulding the processing of the mountain corpse forging process. Steady state forming process. The boundary of the deformed body changes continuously, that is to say, when the corpse has contacted the boundary node of the mold, it will leave the mold as the deformation process progresses. Whether or not the contact node is released from the module depends on the force state of the contact node. If the joint force or stress of the contact node is less than zero pressure on the normal line of the mold, then the node is still in contact with the mold in the next step; otherwise, if the joint force of the contact node is in the normal direction of the mold surface If the component is greater than zero force, it means that the node will leave the mold and become a free boundary node, and then the contact constraint will be released.

3 Application examples Using a finite element analysis software, the finite element simulation of the squeezing process of a certain type of aviation bolt was carried out, and the optimization design of the mold was carried out according to the analysis results.

The axisymmetric blank is used, the material is 169, the mold is also axisymmetric, and the material is die steel. In this example, the shape of the snail is about the condition. And the external load is almost symmetrical. So the bolt should be nine strained. The displacement is cold and axisymmetric, so the actual dimension can be transformed into a simple plane dimension, and the longitudinal section is taken into account. 1 is a geometric model built using the modeling functions provided by the software, and is automatically meshed. Since the metal will have a great friction with the female mold and the jacket during the forming flow, the contact pair is established on the surface, such as the step, that is, the forming result of each step is used as the initial of the finite element simulation of the next step. The condition is solved separately for each step of the forming process, and the processing program is used to observe and analyze the solution. Box 4 is the deformation process in the first step forming process. It can be seen from the plastic flow state of the metal at different stages of forming. In the process of step extrusion, each step has different degrees of filling and filling, which inevitably leads to the accuracy of the forging. High, subsequent processing is cumbersome, material waste rate. At the same time, the stress touches the life of the mold at the corner of the fox lake that is fed by the round ridge at the joint of the bolt head. In view of this, the following two points are proposed to modify the radius of the large mold; 2, the twisting step.

Practice has proved that the finite element simulation results and the experimental results are basically. The simulated metal flow is about the same as the actual situation. The streamline distribution is relatively uniform and smooth. There are no defects such as breaks and breaks, and the metal is not full. This also verifies the feasibility and reliability of the finite element simulation technology in solving the hot forging problem.

4 Conclusion The simulation was successfully carried out, and various mechanical parameters and deformation results of different stages of part forming were obtained, and the mold was optimized according to the simulation results. 1 o'clock. There are also shortcomings in this simulation process because the squeezing process is welcoming multiple. Step-by-step simulation of each step requires a new meshing. This makes it impossible for the wood to be continuous, and the streamline becomes disordered. It is not convenient to investigate the streamline distribution of the entire forming process of the part. And analysis, but this analysis of some important parts is extremely important, and this is yet to be improved and improved by the author in the future.

3,148 such as 4, 2131 world plastic processing latest technology translation set. Beijing Mechanical Industry Press, 2000.

4 Zhao Guoqun. Finite element simulation of metal flow law in axisymmetric forging process. Mold Technology, 1992, 1.

5 Gao Zhenyan. Mesh division and re-division technique for finite element simulation of metal plastic deformation and its application. Journal of Jilin University of Technology, 1993, 232.

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