Finite Element Method on Die Deformation and Elastic Spring-Back Analysis for Product of Helical Gear

The elastic stress analysis of the die for helical gear forging has been calculated by using the nodal force at the final stage obtained from the rigid-plastic finite element analysis. In order to obtain more precise gear products. the elastic analysis of the die after release of punch and the elastic spring-back analysis of product after ejection have been performed and the final dimension of the computational product has been in good agreement with that of the experimental product

Study on Precision Cold Forging of helical Gearar

In metal forming, there are problems with recurrent geometric characteristics without explicitly prescibed boundary conditions. In such problems, so-called recurrent boundary conditions must be introduced. In this paper, as a practical application of the proposed method, the precision cold forging of a helical gear has been simulated by a three-dimensional rigid-plastic finite element method and compared with the experiment. The application of recurrent boundary conditions to helical gear forging analysis is proved to be effective and valid. the elastic stress analysis of the die for helical gear forging has been calculated by using the nodal force at the final stage obtained from the rigid-plastic finite element analysis. In order to obtain more precise gear products, the elastic analysis of the die after release of punch and the elastic spring-back analysis of product after ejection have been performed, and the final dimension of the computational product has been in good agreement with that of the experimental product

트로코이달 헬리컬 기어의 비정상 상태 유한요소해석

In metal forming, there ar problems with recurrent geometric characteristics and without explicitly prescribed boundary conditions. In such problems, so-called recurrent boundary conditions must be introduced. The present study deals with nonsteady-state three-dimensional finite element analysis for extrusion of a trocoidal helical gear through a curved die. The boundary-directed remeshing scheme based on the modular remeshing technique is developed to reduce the errors arising in fitting old and new mesh systems. The computed extrusion pressure in reaching the near steady-state loading stage is compared with the results of the experiment and the steady-state analysis. The three-dimensional deformed pattern involving warping at the extruded end due to torsional deformation mode is demonstrated

Finite Element Analysis of Axisymmetric Cold Forging by Curved Dies

The paper is concerned with the analysis of spike forging and backward extrusion as nonsteady processes by the rigid-plastic finite element method. These process include die boundaries of curved shape and this should be taken into account in the finite element formulation. The spike forging process is characterized by large free surface, rigid part and curved contact surface. The developed program for initial velocity field generation is included in the present FEM program. The workhardening effect, rigid body treatment and interface friction along curved die surface are introduced in the formulation. In backward extrusion deformation is very severe around the punch corner and the remeshing technique is employed in the FEM program to combat this problem.The experiments are carried out for spike forging and backward extrusion with commercially pure aluminum(Al 1100) billets. Computational results in deformation and load are in excellent agreement with the experimental observation. The present analysis permits the prediction of stresses, strains and strain rates. The effects of fiction factors on interface pressure and spike height are discussed in spike forging. It is thus shown that the present formulation enables the effective design of axisymmetric cold forging processes

반복 경계 조건을 가진 형상의 3차원 성형에 대한 강소성 유한요소해석

학위논문(박사) - 한국과학기술원 : 정밀공학과, 1995.2, [ ix, 146 p. ]An effective and accurate method of analysis of forging processes is essential to the design of optimized dies as well as to the production of net-shape products. CAD/CAM/CAE involving FEM has been extensively applied to various metal forming areas with the fast development of computers, in order to make effective approaches to the die design and the die manufacturing for more accurate products of high quality. Up to date many useful schemes for analysis of three-dimensional metal forming have been developed and applied to practical problems. However, in the case of problems with recurrent shapes and without explicitly prescribed boundary conditions which mainly arise from recurrent loading condition or recurrence of shape, no effective method has been thus far proposed for analysis of metal forming problems. In the present work, so-called recurrent boundary condition is systematically formulated in the three-dimensional rigid-plastic finite element method so as to treat readily and efficiently the problems in which the geometric shape for consideration is not symmetric in the ordinary sense and is only recurrent. In order to show the validity and effectiveness of the introduced method, computations have been carried out for some metal forming examples having recurrent geometry. Analysis of torsion, one of important mechanical tests, has been carried out mainly concerning the comparison with the conventional methods in computational time and accuracy. Helical extrusion of a clover section has been analyzed with a full region as well as with a minimum region using recurrent boundary conditions as a region of analysis. Comparisons of deformed configuration and effective strain of a section have been made between two cases. The computational results have shown that there is no appreciable difference at all between two cases and thus computation can be effectively carried out using recurrent boundary conditions and it can be extended to other processes with twiste...한국과학기술원 : 정밀공학과

Finite element analysis of axisymmetric forging by curved dies

학위논문(석사) - 한국과학기술원 : 생산공학과, 1987.2, [ v, 58 p. ]한국과학기술원 : 생산공학과