Zlatko Kampuš

Welding of tailored blanks of different materials

Abstract This paper treats welding of tailored blanks made of different materials. In general, fusion welding and welding with pressure, practically without fusion, are described. Fusion welding may be carried out with or without the addition of filler material. In Section 3 , general characteristics of tailored blanks are described. In Section 4 , MIG welding and laser welding of austenitic stainless steel with ferrite non-stainless steel are described. After welding, hardness of the welded joints was measured. The welded joints were subjected to deep drawing. At the end, conclusions are stated. Investigations have shown that tailored blanks of high-alloy stainless steel cannot be laser or TIG welded to those of low-alloyed ferrite steel without the addition of filler material. A suitable process and filler material should be selected. The purpose of the filler material is to compensate for the differences in chemical and physical properties of both materials.

Deep drawing of tailored blanks without a blankholder

Abstract This paper describes experiments involving the deep drawing of tailored blanks without a blankholder. Four materials with very different forming properties were tested. A rough comparison is given between the production of MIG-welded blanks and laser-welded blanks. The properties of cups produced in this manner are described, and an FEM analysis of this procedure is presented.

Injection moulding simulation results as an input to the injection moulding process

Abstract In the presented research work the authors tried to develop the software which will suit all the needs of the injection moulding when optimising the part-mould-technology system. The simulation results consist of geometrical and technological data. Geometrical data are useful for both: the part as well as the mould designers, because technological data help the moulders to understand the process parameters. On the basis of the simulation results, the part designers can optimise the geometry of the part and the mould designers can optimise the running and the cooling system of the mould. In this way the optimal input values for the technology optimisation can be defined. The paper provides evidence that the program with its open structure suits the needs of the laboratory environment as well as of the real production.

Modeling of forming efficiency using genetic programming

This paper proposes new approach for modeling of various processes in metal-forming industry. As an example, we demonstrate the use of genetic programming (GP) for modeling of forming efficiency. The forming efficiency is a basis for determination of yield stress which is the fundamental characteristic of metallic materials. Several different genetically evolved models for forming efficiency on the basis of experimental data for learning were discovered. The obtained models (equations) differ in size, shape, complexity and precision of solutions. In one run out of many runs of our GP system the well-known equation of Siebel was obtained. This fact leads us to opinion that GP is a very powerful evolutionary optimization method appropriate not only for modeling of forming efficiency but also for modeling of many other processes in metal-forming industry.

Improving workability in ironing

Abstract The paper describes the possibilities of improving workability in ironing by using a superimposed force on the cup edge. Equations for stresses and forces in ironing with superimposed force were derived on the basis of the elementary theory of plasticity. The increase in workability is shown in the workability diagram. The finite element method (FEM) served as the basis for simulating the production of cups with non-uniform wall thickness. Two theoretical models were verified by experiments.

Experimental and numerical (FEM) analysis of deep drawing of relatively thick sheet metal

Abstract The paper deals with an analysis of deep drawing without blankholder with special emphasis on workpiece geometry. The process was simulated by the FEM using a rigid-plastic model. Because of a relatively small forming speed (a hydraulic press is normally used) and small deformations, temperature was not considered in the model. In the analysis axi-symmetric quadratic elements were used. The model was also verified experimentally.

Analysis of the factors influencing the geometrical shape of workpieces produced by ironing

Abstract The paper consists of an analysis of the subsequent ironing of cups that had been produced by deep-drawing without a blankholder. On the basis of the theory of elasto-plasticity, a computer-aided model of ironing has been built, which considers the main influences on the outer and inner diameter of the workpieces, these influences including the stiffness of the tool. the forming and material properties of the workpiece material, the magnitude of the strain, the magnitude of the superposed force, the influence of heating and others. A comparison is made between the theoretical and experimental deviations of the cross sections of the heated workpiece on the punch, after removing it from the punch and allowing it to cool.

Analysis of factors influencing accuracy in the drawing of round rods

Abstract The analysis of factors influencing the dimensional and shape accuracy of products made by forming is above all based on the results of experiments, but also, more recently, on the predictions of the finite-element method (FEM). This paper gives an analysis of factors influencing the accuracy of drawn rods using two models. The first model, made with the elasto-plasticity equations, is simple and suitable for integration into expert systems; while the second model, made using FEM, is used to verify the accuracy of the first model.

Ironing with Superimposed Force

The paper presents equations for the calculation of stresses in ironing with superimposed force which were derived on the basis of the elementary theory of plasticity. The process of ironing with superimposed force was simulated using the finite element method (FEM). Simulation showed that cups can be made either with internal or external wall thickening. Experiments were conducted to verify the predictions obtained by the model using the elementary theory of plasticity and the finite element method.

The Influence of Injection-Molding Parameters on the Dimensional Accuracy

The most influential injection-molding factors were chosen and the Taguchi method of experiment planning was used to determine the number of the experiments needed. The test specimens in the form of a standardized tensile specimen were injection-molded under six different conditions. The analysis of variance was used to determine the parameters influencing the dimensions of a green part. Under the same conditions the test specimens were then subjected to debinding and sintering, and the influences of injection on the mass, mechanical properties and dimensions were analyzed once again.