Deep Drawing Forming Research Articles

A Fuzzy Recognition of early Crack of Metal Deep Drawing Stamping Based on the Fuzzy Clustering

This paper was according to the early crack identification on metal deep drawing, combined with the characteristics of the AE singal of deep drawing forming, determined to analyze it by db4 wavelet basis function for 3 layers, extracted the energy value at every point of the eight AE signal samples from deep drawing forming which crack state was known to constituted characteristic matrix, fuzzy equivalence matrix was obtained by a series of matrix transformation,which was regard as pattern library of crack that used in cluster analysis. Then extracted energy value at every point of AE signal from deep drawing experiments with there states unknown, calculate similarity between samples and the model we established by using euclidean distance formula after normalization processing, deep drawing state was determined by the principle of selecting near, finally compared the recognition result with crack situation deviced by naked eye and microscope, results show that the accuracy of fuzzy identification of early crackn based on fuzzy clustering is up to 90%.

FORMABILITY OF AUSTENITIC STAINLESS STEEL 316 SHEET IN DYNAMIC STRAIN AGING REGIME

Dynamic strain aging region for austenitic stainless steel 316 was investigated from room temperature to 650°C at constant strain rates of 1x10-2, 1x10-3 and 1x10-4 sec-1. Characteristics indicators of serrated plastic flow were observed in the temperature range of 400°C to 600°C at these strain rates. Strain rate sensitivity of the material is found to be negative in this region. Study of fracture surface of tensile test specimen by scanning electron microscope revealed that ductility in this region decreased. The limiting drawing ratio of sheet metal is the indicator of formability in deep drawing. LDR of the sheet metal was estimated by performing the deep drawing of different diameter blanks in finite element simulation software LS-DYNA in DSA temperature region. It was observed that in DSA region, formability of sheet metal decreased. These simulations are validated and compared with experimental results.

Improvement of formability in deep drawing of ultra-high strength steel sheets by coating of die

The formability of deep drawn ultra-high strength steel sheets in dies coated with either titanium nitride (TiN) or Vanadium carbide (VC) at different drawing speeds and ironing ratios was investigated. TiN was deposited via chemical vapour deposition and physical vapour deposition (PVD) while thermal diffusion was used for VC deposition. In non-coated dies, seizure occurred on both surfaces of the die and the side wall of the drawn cup irrespective of the deep drawing conditions. The deep drawability is improved with coating of die. Whereas in coated dies, seizure became significant only during deep drawing extreme conditions of 120mm/s for TiN-coated dies; and this was prevented in VC-coated dies across all drawing conditions. The VC-coated die was suitable for deep drawing of ultra-high strength steel sheets. The delayed fractured observed in the ultra-high strength steel cups occurred for a large amount of ironing ratio and drawing speeds; and this can be prevented by appropriate heat treatment.

Investigation of Material Model for Simulations of Deep Drawing in Dynamic Strain Aging Region

Discontinuous plastic flow in metals referred to as dynamic strain aging. These DSA appears during the plastic deformation of the metallic materials under certain temperatures and strain rates. Present work is aimed to find the best available material model for simulations of deep drawing in DSA region. The limiting drawing ratio and thickness distribution of drawn cup are the indicators of formability in deep drawing. Thickness distribution of the simulated cup at LDR in DSA region was compared with experimental values. It was observed that Barlat material model best simulates the deep drawing process in DSA region.

Experimental and numerical investigation of formability for austenitic stainless steel 316 at elevated temperatures

Sheet metal forming at elevated temperature is not much used in industries but it is going to be a very important process in the future. The present work is aimed to investigate the formability of austenitic stainless steel 316 at elevated temperatures. Limiting drawing ratio and thickness of the drawn cup are the indicators of formability in deep drawing. In the present investigation circular blanks are deep drawn at room temperature, 150°C and 300°C using a 20ton hydraulic press coupled with a furnace. Finite element simulations are carried out using Dynaform with LS-Dyna solver. Simulations and experimental results show an increase in the limiting drawing ration as the temperature increases and a decrease in the thickness of the drawn cup without any fracture. An artificial neural network model is developed for the prediction of the cup thickness at different locations. Based on the input variables, such as distance from the center of the cup, temperature and LDR, a back propagation neural network model to predict the thickness as output was develop. The comparison between these sets of results indicates the reliability of the predictions. It was found that there is a good agreement between the experimental and predicted values.

Crack Position Recognition of Metal Deep Drawing Parts Based on BP Neural Network

Crack position of metal drawing parts molding was analyzed by the BP neural network. First analysis of the drawing parts forming process may crack in different position. The BP neural network location identification was introduced in the basic process. 11 characteristic parameters from the drawing parts may crack position were gathered by acoustic emission signal acquisition system of deep drawing process. Then the BP neural network was designed rational, and carried out appropriate conduct to train and test. Establishing deep drawing parts of the relations between the different positions crack acoustic emission characteristic parameters and the corresponding position. Crack location was identified, in order to achieve the purpose of positioning the work piece forming process. The better method of acoustic emission location issues are resolved, metal deep drawing forming of crack location identification for basis. Provide the basis for metal drawing parts forming crack location identification.

In-Process Visualisation for Deformation Monitoring and Analysis of Sheet Metal Forming Processes

In this paper, a visualisation system will be discussed that can be used to capture the deformation profile of the sheet blank during sheet metal forming processes, such as deep drawing and shape forming. The visualisation system utilizes a 2D laser displacement sensor for deformation profile acquisition. The sensor is embedded in the die and the laser propagates through the die to detect the profile change of the specimen concealed in the die during operation. The captured profile data will be collected, manipulated and transferred to a monitor for display via a controller. This visualisation of the deformation profile will provide engineers and researchers with an intuitive means of analysing and diagnosing the deformation process during sheet metal forming.

Research on Finite Element Simulation and Test of Two-Pass Deep Drawing Forming for Conical Parts

This paper is focus on two-Pass Deep Drawing Forming of conical axisymmetric parts, study on the finite element simulation and test of multi-Pass deep drawing part. It carry on the finite element analysis and calculation using the ANSYS/LS-DYNA software platform, analyzing the simulation results such as stress , strain distribution and formability by post-processing LSPOST software. It was done multi-Pass deep drawing test using a set of combined type mould. Based on the multi-Pass forming test by using a set of combined type mould, comparison of simulation and test data can be obtained through the forming limit diagram. The result of simulation and test is basically the same and both reflect the formability.

Temperature and Processability of Magnesium Alloy AZ31 on Rectangular Cup Deep Drawing

The magnesium alloys, that have high specific strength, are often applied to the industrial products. However, the magnesium alloys exhibit low ductility at the room temperature on account of its hexagonal close-packed structure. It is difficult to give large deformation to the magnesium alloys at room temperature. Therefore, the plastic forming of a magnesium alloy sheet needs the process at warm temperature. In the present work, the procedure of thermal-mechanical coupled analyses are employed. The numerical simulations of warm deep drawings have been performed in order to evaluate the dependence of the temperature on the plastic forming of a magnesium alloy AZ31 sheet. The mechanical properties of the magnesium alloy AZ31 shall be described as the functions depending on temperature. The shapes of punches and die holes are rectangle whose aspect ratios are 1.5 or 2.0. The corners of punches and dies are heated locally at 473K. The influence of local heating on the formability have been investigated. The relation between the blank size and the formability has been also estimated. As the results of numerical simulations, it was shown that the formability of deep drawing was improved by local heating to the punch and the die. When the blanks of various sizes were tried, the distributions of the plastic strain rate around the die corner were changed. Therefore, the deviation of the plastic flow and the temperature distribution arose in a sheet. Consequently, it is necessary to optimize the blank sizes according to the shape of die holes in addition to the forming temperature.

EBSD Study of Microstructural Development during Superplastic-Like Forming

Superplastic-like forming takes advantages of both deep drawing and bulge forming. The use of non-superplastic grade materials enables it to be more compatible with existing forming process with less material and time cost. Here, a non-isothermal heating system was adopted to selectively heat up selected localized areas to form the workpiece more efficiently. Electron backscattered diffraction (EBSD) was then used to investigate the wide range of grains in the formed samples resulting from elevated-temperature and large-strain deformation. The crystallographic textures of the material before and after deformation were observed for comparison. Very little recrystallization was found in the midst of the deformed grains. Considerable amount of elongated grains with high angle boundaries were produced during deformation. Many subgrain boundaries have developed within the big grains due to dynamic recovery.

Numerical and Experimental Investigation of Influence of Weld Line Orientation on Formability in Deep Drawing of Tailor-Welded Blanks

Application of tailor welded blanks (TWBs) in automobile industry and aircraft manufacturing have been increased during past few years. Efficient material distribution and decreasing weight of the final part are some of the most important advantages of TWBs. Since tailor welded blanks are produced with at least two dissimilar and uniform or non-uniform thickness materials, they show different behavior than uniform materials during deep drawing process. In this research, the effect of weld line orientation on formability in deep drawing of tailor-welded blanks is examined using finite element simulation and experiments. The thinning behavior of the circular TWBs during a deep drawing in a square die is studied for different weld line orientations between two mild-steel blanks with different thicknesses. The numerical and experimental results indicate that the orientation of the weld line direction of the blank sheet has significant influence on the deformation behaviour. It is seen that thinning behavior is similar for two sections of TWB for the same weld line orientation. In addition, the most thinning occurs at 45 degree rotation of weld line, thus appropriate weld line orientation or the tailor blank sheets direction orientation can improve the formability of the tailor-welded blank in a deep-drawing of square cup.

Research of Numerical Simulation Method in Two Pass Deep Drawing Forming of Sheet Metal

Numerical simulation is of great importance in sheet metal multistage deep drawing forming, optimizing mould design and improving mould research and development capability. Now researchers have proposed the numerical simulation general steps of multistage deep drawing, but there are still many problems to be resolved. This paper, comprehensively considering the two important factors of influencing the accuracy of the numerical simulation, introduces the numerical simulation simplified steps of two pass stamping forming. Results show that this new method is effective and successful in simulating two pass deep drawing forming, and the simulation results are more reasonable.

Análisis de la deformabilidad del acero inoxidable AISI 304 DDQ en condiciones multiaxiales de embutición. Evaluación de la influencia de la acritud inicial

The deep drawing formability of a material is established as a function of standard indexes, as strength coefficient and anisotropy coefficient. But these indexes are determined in different conditions to those that take place in the forming process. The simulative assays do not separate the actions due to the different variables that work in the process, as for example, the rolling direction. In the present work a test that uses a wedge shape die is considered in order to obtain the strength and anisotropy coefficients as a function of rolling direction. This way, the assays are carried out under a tensile-biaxial compression stress state similar to that one taking place in the flange zone in deep drawing. The experimented material is a deep drawing quality stainless steel AISI 304. The influence of initial strengthened states, rolling and uniaxial tensile on the steel behaviour are also studied. The results permits the authors establish the validity of the assay from the point of view of the strains produced in the sheet. The initial strain has a higher effect on the material than that one obtained from the tensile-biaxial of the state than the tensile-biaxial compression causes. The anisotropy coefficient changes with the strain for the sheet rolling direction.

Advantages of the Meso/Macro Approach for the Simulation of Fibre Composite Reinforcements

This paper presents a new discrete modelling for the dry woven composite reinforcements forming in LCM (Liquid Composite Moulding) processes. Two existing approaches to model woven composite reinforcements at the macroscopic and mesoscopic scale are reminded and our modelling at the mesoscopic scale which can be applied to large fabric pieces is presented. The mechanical behaviour of each compound in such a model is simpler than for continuous models and difficult aspects such as yarn's direction updating are naturally built in as in the mesoscopic approach. The compensation lies in the large amount of components with complex contacts between them. Interests of this approach such as the prediction of the apparition of wrinkles and “unweaving” phenomena are also detailed and illustrated by the simulation of a picture frame test and of a deep drawing forming.

English

In the present study the effect of mechanical Properties like strain hardening coefficient (n) and yield strength (σys) on the deep drawing formability is observed. In which three levels of n and σys have been considered. All the simulations were performed in the PAM STAMP 2G a FEM code and specialized sheet metal forming soft. Hill’s 1948 isotropic hardening yield criterion was used as the plasticity model. Hollomon’s power law was used as the strain hardening law. All three levels of mechanical properties were taken from experimental work of Singh and Gupta (2010) on IF steel. The data like dome height, and thickness distribution variations is taken. The results showed that dome height for the all the simulation is same and thickness distribution has got little variation with respect to mechanical properties.

Comparison of some Final Part Geometrical Characteristics of Cylindrical Cups Manufactured by Deep-Drawing and Two-Point Incremental Sheet Forming

Asymmetric incremental sheet forming (AISF) is a new sheet metal forming process in which sheet metal parts are produced by CNC-controlled movements of a simple ball-headed forming tool. Despite its flexibility and successful application in many cases, AISF has not yet been established in an industrial context due to some still existing process limits such as severe thinning, which strongly depends on the inclination of the part surface, as well as a limited geometric accuracy due to springback. Furthermore, there is little knowledge available about the properties of parts produced by AISF, especially in comparison to deep-drawn parts. The aim of the present paper is to compare cylindrical cups manufactured by deep-drawing and AISF regarding the resulting strain and thickness distribution. For AISF, different forming strategies were applied. Comparisons of the wall thickness and surface strain distributions show similar results for the cup produced by deep-drawing and the best cup produced by AISF, but the surface strains and the sheet thinning in the parts formed by AISF were larger than in the deep-drawn part.

Finite element study and sensitive analysis of the deep-drawing formability of commercially pure titanium

This paper describes a 3D finite element model used for optimizing the deep-drawing formability of a commercially pure titanium cap designed for the cosmetic industry. The results obtained from a specific tooling and various tensile tests highlight a strong anisotropic behavior of the material (earing profile on the parts and Lankford coefficients very sensitive to the loading direction). The mechanical behavior taking this anisotropy into account is described according to an elastic-plastic model based on the quadratic Hill’s criterion. A special attention is paid to studying the sensitivity of the FEM predictions with respect to the numerical parameters. The type and number of elements in the thickness of the blank and the friction coefficient have a significant influence on the numerical results. The comparison with the experiments taking the springback into account shows that the FE model is suitable for describing the behavior of titanium during a forming process such as deep-drawing. A Forming Limit Diagram is finally given to predict the feasibility and optimize the forming operation.

Strength and Formability of Friction Stir Welded Aluminum Alloy with Cold Rolled Steel

Friction-stir-welding (FSW) was conducted between an aluminum alloy 6061-T6 plate and a cold-rolled steel SPCC plate. Tensile and fatigue strengths of the FSWed material were investigated and its formability was estimated through bending and deep-drawing tests. Furthermore, we investigated effect of aging treatment (18ks, 453K) after FSW. The result showed that the condition of FSW was suitable and no brittle compound and defects were formed at the interface between the 6061 alloy and SPCC steel. However, hardness decreased in the region where the rotating tool passed so that the tensile strength of the FSWed material was slightly lower than that of uniform 6061 alloy. The tensile strength of the FSWed material was recovered by aging treatment and it reached to the same level to the 6061 alloy. The FSWed material and its aged material possessed good bending and deep-drawing formability. However, the fatigue strength was decreased even after aging treatment because an insufficient joining region was inevitably formed by FSW at the opposite side where the rotating tool traveled.

Research on the Effect of Entry Angle and Pressure-Pad Force on Deep-Draw Thermo-Rheological Forming of a TC1 Ti-Alloy Sheet

Numerical simulation can be successfully applied to evaluate product manufacturability and predict, while material wrinkling and splitting are associated with entry angle and pressure-pad force during sheet metal stamping process. In this paper, the influence of entry angle and pressure-pad force on deep-drawing thermal forming of TC1 titanium alloy was analyzed by using explicit dynamic finite element software STAMPACK, two kinds of main invalidation, including wrinkling and splitting, and obtained that the entry angle is an important factor for deep-draw thermal forming. By analyzing the forming operation and optimizing the entry angle and the pressure-pad force of the die, the best range of the entry angle and the suitable pressure-pad force without wrinkling were obtained and splitting phenomena were controlled effectively. The researched results of numerical simulation provided some parameters for die design.

The Experimental Research on the Formability of Stamping of Magnesium Alloy AZ31B Sheets

In this paper, the basic formability of stamping of magnesium-alloy AZ31B sheet has been studied through experiments. The stamping formability of magnesium-alloy AZ31B sheet, such as the conical cup value, bending formability, deep drawing formability, formability of hole expanding, forming limit has been studied by simulating processing experiments. The formability of stamping supplies the basic reference data for the stamping processing. It is also found that the formability of stamping of magnesium-alloy AZ31B sheets is poor at room temperature and is excellent at intermediate and high temperatures.