Papers by Keyword: Drawing Process

Abstract: A detailed analysis of the effect of variable stresses on the intensity of retained austenite transformation into martensite was carried out in the work. Tests were done for three bending stress (σ_max) levels, lower than the value of the yield stress (R_0.2) the material tested. Preliminary tests conducted for one bending stress value have shown that a certain amount of untransformed retained austenite remains in the material in spite of applying as many as 40 000 fatigue cycles. It is therefore necessary to determine whether and, if so, in what extent the magnitude of applied bending stress will increase or decrease that amount of retained austenite. It should be established whether, for different bending stress levels, the curves describing the variation in the volumetric fraction of retained austenite of the tested wire structure, will approximate asymptotically the same value, or the values will, after all, be different.The results of these studies have a practical dimension, since, e.g. a screw made of the TRIP steel, subjected to variable stresses in service, may undergo additional hardening to a varying extent, which will influence its mechanical properties, life and operation safety.The knowledge acquired from the studies will constitute a novelty in this scope of applications, and will be useful from the point of view of both the manufacturer and the user.

Abstract: Numerical simulations of drawing and redrawing process of forming cylindrical elements from thin sheets are complicated issues due to the problem with describing finite elements in the complex calculation model. This type of simulation require the creation of the rheological model including the forming limit curve, the true-stress-strain curve and anisotropy defined in various directions. In addition, it is necessary to design optimal geometry of the forming tools. FEM calculations have been performed for 3XXX series aluminum tape in cold-hardening state. The initial data, boundary conditions have been defined, as well as technological data concerning the sheets have been specified experimentally. Numerical analysis of thin aluminum sheet drawing and redrawing process has been analyzed for 3 various sheet thicknesses, i.e.: 0,250 mm , 0,240 mm , 0,230 mm. Currently, the industry uses mainly sheets of 0.250mm thickness. A few manufacturers of beverage cans use sheets of thickness0.240mm while the sheet of thickness 0.230mmis the innovation which manufacturers try to introduce into the industry to minimize the quantity of material. For the selected thickness the clearance between the punch and the die has been calculated as well as the optimum hold-down force. The influence of sheet thickness on the distribution of thinning along generating line has been examined. In order to determine the thinnest possible sheet for obtaining the optimal thickness of the final product, the thinning of drawpiece has been analyzed. Moreover the value of deformations has been compared to FLC curve as well as the intensity of the stresses generated in the bottom and on side walls of the cup has been examined.

Abstract: The discussed subject matter concerns the influence of two kinds of Al-Zr alloy production technologies on the properties of the wires dedicated for electrical purposes. The paper presents research and the analysis of the research into the influence of the production technology and the processing technology on the ingot wires made from the heat resistant Al-Zr alloys as well as on the characteristics of the properties of the examined materials with the focus on the electrical and mechanical properties and their microstructure analysis. The materials subject to the mechanical and physicochemical research were materials manufactured in industrial and laboratory conditions in the form of the wire rod and cast bars as well as wires of various diameters drawn from them. The research concerned six Al-Zr alloys with the zirconium content from 0.05 to 0.32% of the mass.

Abstract: For the numerical analysis of TRIP steel wire drawing process, the Drawing 2d programme based of finite element method, has been used. The process was run following two variants, with small and large partial drafts for two drawing speeds: 1.11; 0.23 m/s. The investigations carried out allowed a relationship between temperature of drawing wires and the amount of retained austenite for wire surface and for wire axis.

Abstract: Magnesium-calcium alloys with increased bio-compatibility are applied in medicine for sake of high compatibility and solubility in human body. Production of surgical threads to integration of tissue may be one of the applications of those types of alloys. A new manufacturing process of thin wires made of biocompatible Mg alloys, including drawing in heated dies, was developed in Authors previous works. Conducting drawing process in conditions, in which recrystallization occurs, is the basis of the process. This allows for multi-pass drawing without intermediate annealing. Control of recrystallization after every pass using experimental method is complex so numerical simulation seems to be a rational method to design the process parameters. The purpose of the paper is developing a mathematical model of recrystallization for MgCa08 alloy, its implementation into the finite element (FE) code that simulates wire drawing and experimental verification of the numerical calculations. The first part of work was focused on the development of mathematical model of wire drawing process of Mg alloys in heated die. Proposed model takes into account thermal phenomena in the wire and in the die, plastic flow of the material, stress-strain state and recrystallization. The fracture criterion was implemented into FE code to eliminate the possibility of damage. The second part of the work was focused on experiments including upsetting and tensile tests for calibration of recrystallization and fracture models. Recrystallization model was calibrated on the basis of flow curves only what is a limitation. Therefore, experimental wire drawing on drawing bench developed by the Authors was the final stage of the work performed to validate the model. Recrystallization during wire drawing was studied. The developed computer program enables prediction of the recrystallization kinetics during wire drawing in heated die for MgCa08 alloy. The model of static and dynamic recrystallization of this alloy and complex model of the drawing process were proposed in this work, as well.

Abstract: the engine oil pan, materials for ST16, tensile depth of the parts is bigger, the design of the mould is very important to the success or failure of the drawing process to appear. The drawing process design, the engine oil pan drawing die general assembly drawing and work process analysis, finite element simulation, the engine oil pan tensile drawing process and die to improve oil pan.

Abstract: In addition to the high cost and long period, the traditional design of the drawing process depends too much on empirical formulas and data. To solve this problem, the paper proposes an ideal design process of the drawing process, which improves the traditional design process bases on CAE and applies FEM software Dynaform. The paper takes a drawing cylinder as an example, which needed 4-stage drawing process, could be improved into 3-stage by the simulation analysis of CAE, as a result , which can reduce the cost and improve the production efficiency.

Abstract: In the case of sheet metal forming process one of the most important phenomena that affect the dimensional and shape accuracy of the formed parts is the part springback after the tools removing. The springback phenomenon depends, on the one hand by the material mechanical parameters (especially Youngs modulus, anisotropy coefficient, yield stress) and on the other hand by the process parameters and tools geometry. Therefore in order to control the springback for a given material, the influence of the process parameters or tools geometry must be know. The aim of the present paper is to investigate the effect of blankholder force (as process parameter) on the springback parameters in the case of rectangular parts made from steel sheets. The investigations were made both experimentally and by finite element simulation. The springback parameters of the obtained parts were determined by using the ATOS system and ATOS software that allows the virtual reconstruction of the part shape in order to measure the springback parameters. Both experimental and simulation tests shown that the use of a high value of blankholder force leads to the increase of the drawn part accuracy.

Abstract: The specific properties of TRIP steel can be obtained by the occurring the effect of additional plasticity during transformation of metastable retained austenite into martensite caused by plastic deformation process. Research carried out for highly alloyed austenitic steels with TRIP effect proved the influence of strain intensity, chemical composition and deformation temperature on efficiency marteniste transformation. In the work research concerned with the influence change of drawing speed on retained austenite amount in drawn wires structure was shown. In available literature there are no publications concerned with the influence of wire drawing process parameters on the structure evolution the medium carbon TRIP steel wires. Research shown in the work was realized with the assumption that the strain intensity is determined by scheme of single and total reductions, and the value of strain rate is a result of used in wire drawing process drawing speed.

Abstract: Tension-tension fatigue tests were performed to examine the influence of post drawing heat treatment on the fatigue properties of drawn specific steel tube (STB340) for small-sized single pass boiler. The untreated, as-drawn and post drawing heat treated series were prepared for fatigue tests. The hardness, grain size and residual stress were measured for each series. As a result, the change of grain size and residual stress was small after post heat treatment. The drawn series was softened by post heat treatment but the hardness was still higher than untreated samples. The fatigue strength of the as-drawn and the post drawing heat treated series was higher than that of untreated series. In addition, the difference of endurance limit was small between as-drawn and post drawing heat treated series.