Önder Ayer

Effect of die inlet geometry on extrusion of clover sections through curved dies: Upper bound analysis and experimental verification

The effect of die inlet and transition geometry on the extrusion loads and material flow for extrusion of clover sections were investigated and presented both theoretically and experimentally. For this purpose, four different die geometries including straight tapered and cosine transition profile and each of them having round and clover inlet geometries were chosen. In the experimental study, commercially pure lead was used because of its hot forming characteristic at room temperature. A newly kinematical admissible velocity field to analyze different profiles of extrusion dies of clover section from round bars was proposed by upper bound analysis. It is clear that the extrusion loads obtained from the theoretical analysis for various die inlet-die transition geometry combinations are in good agreement with the experimental results. Axis deviations of the parts which define the dimensional quality of the products were also investigated.

FE Analyzing of Layout Types for Multi-hole Extrusion Dies

Extrusion method is an important bulk-forming process to transform materials into semi-finished products in the form of bar, strip, and solid section as well as tubes and hollow sections. One of the basic considerations of die design is to determine the number of die openings based on the shape and size of the profile. In this study, variation of the extrusion load and temperature is investigated for different number and layout of die openings by finite element analysis. Three types of layouts, radial layout of a multi-hole die, flat layout of a multi-hole die and orientation of a shape around its center of gravity, were simulated with four openings in the dies. Moreover, the most commonly used type of them was also simulated for different number of openings in the die to compare the effect of the openings number on the extrusion.

A numerical study for prediction of forming load and experimental verification of bimetallic disc upsetting

Original scientific paper Forming of disc samples composed from aluminium and copper in performed study was examined with upsetting procedure. An approach for prediction deformation load of upsetting processes is developed. This study combines the finite element method model, neural network model and upper bound method to simulate and predict the deformation load in upsetting of bimetallic materials. The Finite Element Method (FEM) results were obtained from DEFORM-3D software and they were compared and validated with experiments by taking forming load into consideration. Also, Artificial Neural Network (ANN) model was used to analyze and predict the forming load for different process parameters. The Upper Bound (UB) model was also proposed to estimate the forming load and the results were compared with experiments. It was understood that calculated results were in concordance with experimental results in upsetting of bimetallic hollow discs. Thus, proposed ANN, FEM and UB models provide a valuable insight into the parameters affecting forming load and can be named as useful tools to predict the forming load without the need of any experiments.

SIMULATION OF HELICAL GEAR FORMING OF AZ31 MAGNESIUM MATERIAL

The simulation of helical gear forming is investigated in this study. AZ31 type magnesium material was selected for workpiece material because of its high specific strength. The finite element method was used to simulate the closed die upsetting method for magnesium material of helical gear upsetting. Three dimensional finite element analyses were carried out to obtain the forming load, effective stress, effective strain and temperature change with DEFORM-3D software.