Drawing Load Research Articles

DEVELOPMENT OF DEEP DRAWING WITHOUT BLANK-HOLDER FOR PRODUCING ELLIPTIC BRASS CUPS THROUGH CONICAL DIES

This paper introduces a new technique for deep drawing of elliptic cups through a conical die without blank holder or draw beads. In this technique an elliptical-cup is produced by pushing a circular blank using a flat-headed elliptic punch through a conical die with an elliptic aperture in a single stroke. A 3D parametric finite element (FE) model was built using the commercial FE-package ANSYS/APDL. Effects of die and punch geometry including, half-cone angle, die fillet radius, die aperture length and punch fillet radius on limiting drawing ratio (LDR), drawing load and thickness strain of the cup have been investigated. A die with half cone angle of 18° has shown the best drawability for the new technique. Finite element model results showed good agreement with experimental results. A die with an aspect ratio of 2 has been used with punches having aspect ratios ranging from 2 to 2.25. Tensile tests were carried out to obtain the stress-strain behavior for the used material. A total of seven punches were used for forming sheet metal of brass (CuZn33) with initial thicknesses of 1.5, 1.9, 2.4 and 3.2 mm at different clearance ratios (c/t). The effects of blank thickness and clearance ratio on limiting drawing ratio, drawing load and thickness strain were experimentally investigated. An elliptic cup with a limiting drawing ratio (LDR) of 2.26 has been successfully achieved.

Spring-seat forming optimisation with genetic algorithm

Forming/drawing is a compression-tension process involving a wide spectrum of phenomenon and flow conditions. The process result depends on the large number of parameters and their interactions. The selection of various parameters is still based on trial and error methods in most industries. In this paper a new approach is presented to optimise the geometric parameters of spring seat – circular geometry component, process parameters such as blank holder pressure and coefficient of friction, etc. The optimisation problem has been formulated with the objective of optimising the draw load. In present work genetic algorithm is used as a tool for the optimisation, to optimise the draw load and process parameters. Optimisation results are validated through finite element analysis simulation software fast form advanced.

Improving the Deformation Uniformity and Minimizing the Inner Surface Roughness in Rectangular Tube Drawing Process

This paper focuses on improving the quality of aluminum rectangular tube in the cold drawing process. The newly developed drawing tools (i.e., the drawing die and the plug) which are considered as one of the most significant factors influencing the final forming quality are proposed. The new-type drawing die is designed with the “convex hull” shape in sizing zone corner and the plug is featured with a “boss club” structure in sizing zone. The equivalent plastic strain, drawn tube’s dimensional accuracy, contact stress distribution, and drawing load have been analyzed for the conditions under which the original tools and the new-type ones have been used, respectively, based on finite element simulations. The simulation results show clearly that the discrepancy of plastic strain in the axial cross section and the tube axial elongation are smaller when the new-type die is employed, which indicates the more uniform metal deformation and steady material flow. Besides that, the fluctuation of wall thickness is also unobvious showing the new-type die is very helpful to improve the tube dimensional accuracy. The newly developed plug can cause higher compressive plastic strain and contact stress, which are crucial to guaranteeing the high surface quality. An experiment on the cold drawing process of the aluminum rectangular tube has been performed. The comparisons of the drawn tube dimensions, e.g., height/width and wall thickness, have been made between simulation results and practical production. Meanwhile, the surface finish has also been measured. The experimental result exhibits that the drawn tube can better fulfill the requirements of the design and usage when the new-type tool is adopted.

인발응력을 고려한 다단 형상인발 공정설계

In this study, a process design method for the multi-pass shape drawing is proposed with consideration of the drawing stress. First, the shape drawing load was calculated to evaluate the shape drawing stress, and the intermediate die shape was determined by using an electric field analysis and the average reduction ratio. In order to evaluate whether material yielding occurs at the die exit, the drawing stress was determined by using the calculated shape drawing load. Finally, FE-analysis and shape drawing experiments were conducted to validate the design of the multi-pass shape drawing process. From the results of the FE-analysis and shape drawing experiments, it was possible to produce a sound shape drawn product with the designed process. The dimensional tolerances of the product were within the allowable tolerances.

Some Studies on Forming Optimization with Genetic Algorithm

Forming is a compression-tension process involving wide spectrum of operations and flow conditions. The result of the process depends on the large number of parameters and their interdependence. The selection of various parameters is still based on trial and error methods. In this paper the authors presents a new approach to optimize the geometry parameters of circular components, process parameters such as blank holder pressure and coefficient of friction etc. The optimization problem has been formulated with the objective of optimizing the maximum forming load required in Forming. Genetic algorithm is used for the optimization purpose to minimize the drawing load and to optimize the process parameters. A finite element analysis simulation software Fast Form Advanced is used for the validations of the results after optimization.

Modeling Analysis of the Wire-Drawing Operation Using the Weighted-Residual Finite Element Method

Numerical analysis of a wire drawing operation to compute the stress distribution along the blank cross-section is presented. The governing equation describing the wire drawing equation is weakened using the Bubnov-Galerkin finite element method to obtain the finite element model. The blank is descritized into a mesh of C0 quadratic isoparametric and C0 cubic finite elements. Stiffness matrices for all elements are obtained using the finite element model which were subsequently assembled by enforcing continuity of the nodal stress. Boundary conditions are applied and the resulting condensed system of equation solved for unknown nodal stresses using Gauss Seidel method. The relative performance of the C0 quadratic and C0 cubic elements are assessed. Parametric analysis is carried out to show the influence of drawing parameters on the stresses generated and drawing load. The analysis was carried out using a Visual Basic.Net program developed by the authors.The results are presented in both graphical and tabular forms.

Experimental Study of Drawing Load Curves in Forming Conical Parts by Hydroforming and Conventional Deep Drawing Processes

Since conical parts have wide applications in the industry and forming these parts is one of the most complex and difficult fields in sheet metal forming processes, the study on different methods in forming these parts can be useful. Hydroforming and conventional multistage deep drawing are two deep drawing processes which have been used to form conical parts. Hydroforming deep drawing is one of the special deep drawing processes which have been introduced in order to overcome some inherent problems in the conventional deep drawing with rigid tools. In the present work, an experimental program has been carried out to compare the drawing load variation and maximum drawing load in forming pure copper conical-cylindrical cups with the thickness of 2.5 mm by hydroforming and conventional multistage deep drawing processes. The results of the study demonstrate that drawing load variation is more uniform in the forming of conical parts by hydroforming deep drawing process. The maximum drawing load for drawing copper blank occurs at a higher amount in hydroforming process.

Numerical Analysis of Cold Tube Drawing Operation using Finite Element Method

In this paper the effect of semi die angle on drawing load in cold tube drawing has been investigated numerically using the finite element method. The equation governing the stress distribution was derived and solved using Galerkin finite element method. An isoparametric formulation for the governing equation was utilized along with C0 cubic isoparametric element. Numerical experimentation showed that the results obtained using the present method is very close to the analytical solution and more accurate than finite difference solution. Having established the accuracy of the present solution method, parametric studies were carried out to show the effect of semi die angle on the drawing load for different tube drawing processes. The analysis was carried out using a Visual Basic.Net program developed by the authors. The results are presented in both graphical and tabular forms.

A parametric study on residual stresses and loads in drawing process with idle rolls

A comprehensive study of drawing process with flat idle rolls of round wires is presented through 3D mechanical finite element simulations. An elastic–plastic model is used for the wire material and contact behavior is simulated by a sliding–sticking friction model. The results of numerical simulations are compared with measurements on wires produced with a laboratory equipment. The comparison of drawing load and some geometrical characteristics of experimental samples with numerical model predictions allowed to establish a good correspondence of model with experimental findings, thus validating the numerical model. Residual stress of flat roll drawn wires, pressure distribution on the forming rolls and drawing load are studied. The effects of main process parameters such as initial workpiece diameter, forming rolls diameter and percentage of deformation are investigated. The results present a helpful insight into the process parameters effect in wire drawing with flat idle rolls thus furnishing the basic guidelines for process design and optimization.

Experimental Investigation on Warm Deep Drawing of Stainless Steel AISI 304

Deep drawing is one of the most widely used metal forming process to produce sheet metal parts especially in automobile industries. Warm working is the plastic deformation of metal at temperatures below the temperature range for recrystallization and above the room temperature. In this investigation, 1.0mm thick circular specimen of stainless steel AISI 304 were warm deep drawn and the influence of temperature on the deformation behaviour of material and the drawing loads which is required to draw the component was studied. The results show that the warm working has positive effects like reduced drawing load, negligible amount of increase in thinning and thickening of a drawn component when compared to the conventional drawing and also there is no necking or cracking occurs due to the temperature influence.

Influence of lubricants in deep drawing of thick steel sheets

The main objective of this was to evaluate the influence of lubrication in deep drawing of EPA sheet with thickness of 3.5 mm and to understand the occurrence of defects as cracks, and bottlenecks. The factorial Design of Experiments was applied to examine the probability of fracture as a function of the following process variables: outer diameter of the blank, radius of the tools, lubricants and performance of the blankholder. Experimental results showed that deep drawing load is significantly reduced with the five different lubricants and that lubrication is more effective when a smaller tool radius is used.

An Experimental and Analytical Study on the Limit Drawing Ratio of Stainless Steel 304 Foils for Microsheet Forming

A series of micro-deep drawing experiments were conducted on stainless steel 304 foils with four thicknesses that were heat treated at four different temperatures. Due to heat treatments, a variety of different grain sizes and T/D ratios (the number of grains throughout thickness) were obtained. In this study, the limit drawing rations (LDR) of these foils were obtained; it has also been found that the factors that influence LRD of the foils include, but are not limited to, thickness, grain size, and T/D ratios. Tensile tests were conducted to obtain their mechanical properties that were used for two macroempirical equations to predict the maximum drawing load and LDR. It has been verified that the two equations can be applied to foils that are not thinner than 150 µm for reasonable predictions. However, the size effects are more noticeable and significant for the foils that are less than or equal to 100 µm so that the macroscale empirical equations cannot be applied to them.

Increasing the drawing height of conical square cups using anti-lock braking system (ABS)

This paper deals with increasing the drawing height of metal conical square cups with anti-lock braking system (ABS). A novel technique enabling higher drawing height than that achieved in the conventional deep drawing process is introduced, and the principle of the process is explained in this paper. Results of experiments conducted using aluminum alloyed Al-1050 blanks of thickness of 1 mm to draw conical square cups are reported here. Measured drawing load, drawing height and thickness distributions were compared with those obtained from the conventional method. The experimental results showed that higher drawing height of the cup can be achieved by the use of ABS.

이형인발공정 하중예측에 관한 연구

The prediction of drawing load is very important in the drawing process. However, it is not easy to calculate the drawing load for the shape drawing process through a theoretical model because of a complex arbitrary final cross section shape. The purpose of this study is to predict drawing load in shape drawing process. The cross section of product is divided with small angle as much as similar with fan-shape. The drawing load of each section was calculated by theoretical model of round to round drawing process. And the shape drawing load was determined by summation of drawing load of each section. The effectiveness of the proposed method was verified through the FE analysis and shape drawing experiment. It had a good agreement between proposed method, FE analysis and experiment within about 3% errors.

Analysis and design of profiled dies for polymer wire die drawing process

A coupled thermomechanical finite element model has been developed to study the detailed temperature, strain and strain rate distributions in conical and profiled die designs and their effect on important processing parameters such as draw load and speed. The performance of conical and profile die designs has also been compared experimentally under identical drawing conditions for the specific case of die drawing of polyoxymethylene wire. Both the analytical and experimental results demonstrate the ability of the profile die designs to significantly increase the processing speed whilst retaining the high degree of orientation and enhanced properties of the die drawn product.

A STUDY ON NON-MANDREL DRAWING PROCESS OF A RECTANGULAR TUBE FROM CIRCULAR CROSS-SECTION

Non-mandrel drawing process is available for producing aluminum tube with rectangular cross-section. The corresponding dynamics and finite element models were developed based on FEM software during the investigation. The influence curve of different semi-die angle on drawing load was achieved, and a proper value a2 = 11° was found. When tube blank instability occurred during drawing, the stress along the section profile increased substantially. Thus the drawing die sizing section got optimized with β = 178° to prevent blank instability. Then the touch-stress distribution of three key points was evaluated for selecting proper lubricant. Finally, the tube drawing experiments were performed to verify the effectiveness of the appropriate die.

Deforming Mechanisms of Two-Pass Drawing Process of an Aluminum Tube from Circular to Rectangle Section

The aluminum tube with rectangle section can be produced by two-pass drawing process including non-plug and with-plug drawing. It is an effective method to study the deforming mechanisms by simulation, based on which the section varying of two-pass drawing got schemed and the relevant dies with reasonable dimensions got designed. The dynamics model and elasto-plastic FE model of the non-plug and with-plug drawing were established based on FEM software, then the simulation was performed. The sizing section of drawing die got optimized with angle β=178°, which eliminated instability. The influence of different semi-die angle 2 a on drawing load was researched, and a proper value of 2 a and 1 a was found. The touch boundary and touch-stress distribution of transitional drawing were achieved. Furthermore the residual stress and spring-back strain distribution after final drawing were achieved, which contributes to modifying the dimensions of rectangle sizing section.

851 歩行時における膝十字靱帯損傷膝の不安定性評価(G02-3 バイオエンジニアリング(3),21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

This study demonstrates the knee instability of crusiate ligament deficient knee in walking using knee brace with motion analysis system. Young-male subjects with intact knee crusiate ligament and young-female subject with anterior cruciate ligament(ACL) deficient knee participated. Knee flection, anterior-posterior tibial displacement and internal-external rotation of tibia were measured when subjects walked at their natural speed. The results showed that 1) anterior tibial displacement and external rotation angle of tibia were increased in anterior cruciate ligament deficient knee than in intact knee, 2) medial tibial displacement of ACL injured knee were significantly increased relative to the intack knee. Our results indicated that consideration of drawing direction as well as drawing load of tibia would be necessary to fix the cruciate ligament deficient knee using functional knee brace with dwawing system.

Analysis and Design of Profiled Dies for the Polymer Wire Die-Drawing Process

In the standard polymer die-drawing process, using conventional conical dies, the strain and strain rate are maximum at the die exit where the stress state in the material, now oriented, is predominantly tensile in nature. This leads to fracture of the material at the die exit at high drawing speeds. In this paper, the plastic flow of the polymer in profiled dies, where the strain and strain rate are controlled along the die-length, is analysed theoretically and it is shown that the design of profiled dies can be chosen to reduce the strain rate at the die exit. A coupled thermo-mechanical finite-element model has been developed to study the detailed temperature, strain and strain rate distributions in conical and profiled die-designs and their effect on important processing parameters such as draw load and speed. The performance of conical and profile die designs has also been compared experimentally under identical drawing conditions for the specific case of die drawing of polyoxymethylene wire. Both the analytical and experimental results demonstrate the ability of the profile die designs to significantly increase the processing speed while retaining the high degree of orientation and enhanced properties of the die-drawn product.

Identification of the bulk behavior of coatings by nano-indentation test and FE-analysis and its application to forming analysis of the coated steel sheet

Abstract In this study, nano-indentation tests, FE simulation and artificial neural network (ANN) technique were used to characterize the power law of the elasto-plastic stress–strain behavior of the coating layers of coated sheets. In addition, based on Oudin's work, two types of FE model were applied on the behavior of the coatings in FE simulations; one was a single-behavior model, which had only one stress–strain behavior and the other was a layer-behavior model, which consisted of separate coating layers and substrates. FE simulations of the cup drawing process were carried out for the two FE models, respectively. The results show that the layer-behavior model that considered the behavior of the coatings was most accurate at predicting of drawing loads.