Papers by Keyword: Preform Design

Abstract: Hand-tool is one of the important products which are widely used in manufacturing industry as well as in human life. The torx is one kind of hand-tools which is considered as a case study in this research. There are two trial preforms designed to analyze their influence on forgings formability. Firstly, DEFORM-3D software was used to simulate and analyze forming processes of different preform shapes for observing the formability of each trial preform and defects during the forming processes. Die stress analysis was also conducted to investigate the die stress of the forming stages in different forming processes. Secondly, according to the formability and the die stress, the most suitable forming processes and preform were selected for actual experiments. Finally, to verify the simulation results accuracy, the feature matching and hardness test were performed. The result of this research show that appropriate forming processes and preform applied improve the quality of product compared to original product.

Abstract: For the forging with complex shape, the preform design is a difficult problem in the process and die design. It has an enormous influence on the quality of the forging. In this paper, combining with the FEM, the Ant Colony Algorithm was used for the preform optimization design. The general Ant Colony Algorithm was improved to fit for the multivariate continuous function optimization. The preform die shape was represented by B-spline and the coordinates of the control point of the B-spline were taken as the optimization design variables. The optimization program was developed. Finally, aimed to decrease the material cost of the forging, the preform optimization of a typical H-section forging was obtained using the self-developed program. The optimization results show that the improved Ant Colony Algorithm is suitable for the preform optimization design of forging.

Abstract: This paper deals with problems in the coining process for manufacturing surgical slit knife using two-dimensional (2D) and three-dimensional (3D) finite element (FE) simulations. The FE simulations are performed to investigate the material flow, and especially stress distribution on the coining dies. The main objective of this paper is to study the feasibility of a coining process for manufacturing a given geometry of surgical slit knife without forming defects and die failure. Very high stress distribution on the coining dies is found by 2D simulations of the coining process that exceeds the strength limit of the die material. The optimum preform and preforming die geometry are determined by FE simulations in order to reduce the die stress. 3D simulations of the preforming and coining processes are conducted with the optimal design to show that the geometry of the product can be achieved without defects by the coining process.

Abstract: In this paper, the finite element method is used to investigate the effect of preform shapes on the strain hardening distribution in the wall of the extruded cup of backward extrusion. A series of simulations on the backward extrusion with three different preform shapes (flat, concave and convex) and without preform using the FEM program DEFORM 2D was carried out, respectively. The influence of preform shapes on the effective strain distribution in the extruded wall was examined. A hardness vs. effective strain curve for an annealed AL6061 Aluminum was first obtained using a simple forging test in conjunction with FE simulations, then the curve was used to convert the effective strain distribution into the hardness distribution in the extruded wall. The results of FEM calculations reveal that the concave shape preform has the best effect on the hardness strengthening at the extruded wall of backward extrusion.

Abstract: In order to decrease the cost of the material and energy during the forging process, multiple preform die shape optimization design was carried out in this paper. Based on the FEM, a sensitivity analysis method was used to perform the optimization procedure. The shape of the forging and deforming force of the final forging was used to express the cost of material and energy respectively. Using the weighted sum method, the total objective function was gotton. The coordinates of the control point of the B-spline used to represent the preform die shape was determined as the optimization design variable. The sensitivity equations of the total objective function with respect to the design variables was developed. The multiple objective perform design optimization software was developed by FORTRAN language. And then, the preform die shape of an H-shaped forging process is optimized. The total objective function, sub-objective function, the shape of the preform die and the final forging during the optimization were given. After the optimiztion, a near net shape forging was obtained. At the same time, the deforming force decreased. The optimization results are very satisfactory.

Abstract: The difficulty in forging of bevel gear with an outside diameter larger than 75mm is due to the high forming load requirement. In this paper, a new intuitive method for the punch and preform design of the bevel gear warm orbital forging is proposed to lower the forging load and improve the die filling. The geometry of the forged bevel gear are divided into characteristic features and mapped to the main dimensions of the preform design. The exact dimensions of the preform are determined utilizing constraints of the volume constancy and the section centroid balance. The surface of punch tip is designed using the section profile described by a Bezier curve with five control points which are related to the preform and the forged part geometry simultaneously. The forming process was analyzed via the FEM simulation. The die stress was also calculated to prevent die failure and improve tool life. A PXW-200 orbital forging press was adopted for the experimental tests of the proposed designs. The unfilled area at the teeth faces were examined via the laser scanner. The experimental results of the maximum unfilled distances were varied from 0.3 mm to 0.8mm depending on the different punch tip profile design. The predicted tooth profiles were in good agreement with the experimental measurements.

Abstract: Preform design in tube hydroforming implies the design of an intermediate shape between initial tube and the final product enabling to be fabricated without defects and excessive loss of material. A carefully selected preform can contribute significantly to reduce production cost and improve formability, since thinned sections may not be able to endure internal pressure during expansion whereas excessive thickening may lead to wrinkles. Generally, preform design in hydroforming was mainly carried out through the trial-and-error approach. Even though a series of numerical simulations for several predetermined preformed shapes were conducted, optimum configuration could not be obtained and could not be suggested the general procedure for preform design as well. In this work, a simple numerical approach to the preform design for formability enhancement was introduced based on the deformation history during forward hydroforming simulation. The proposed approach was implemented to a hydroforming process of an automobile subframe component in order to be satisfied the required specification after hydroforming, and the conceptual application has been proved to be successful on its effectiveness and feasibility. Therefore, it is shown that preform design approach proposed in this study will provide one of feasible methods to satisfy the increasing practical demands for improvement of the formability in hydroforming processes.