Hydrodynamic Deep Drawing Research Articles

Investigation of the effects of process parameters on hydrodynamic deep drawing of AL-1050 sheet with indentations using genetic algorithm–based optimization

Investigation of the effects of process parameters on hydrodynamic deep drawing of AL-1050 sheet with indentations using genetic algorithm–based optimization

On Improving Sheet Metal Formability in Hydrodynamic Deep Drawing Process through a Solid‐Oil‐Type Mineral Grease Pressure Medium

In this research, the improvement in sheet metal formability obtained through the utilization of a mineral grease in solid‐oil‐type (SMG) pressure medium in the hydrodynamic deep drawing process assisted by radial pressure is investigated by experiments and finite‐element method (FEM) simulations on flat‐bottom cups realized with pure copper and DIN 1.0338 steel. To determine the process parameters ranges, an FEM model is developed in ABAQUS/Explicit and validated against experimental results. Afterward, experiments are carried out using two pressure mediums with different viscosities, i.e., water and SMG. Considering the results relevant for both sheet materials, the SMG medium allows an average reduction of the sheet metal thinning of 15% and 10% on the corner edges while also granting a negligible thickness variation on the cup walls. In contrast, the higher viscosity of the SMG, in comparison to the water medium, also results in an average 16% increase in the forming force when compared to the water pressure medium.

Experimental Investigations of Hydrodynamic Deep Drawing of Galvanized Steel to Form a Hemispherical and Complex Cup

In this work, a blank of galvanized steel blank with 80 mm diameter and 0.7 mm thickness and the hydromechanical deep drawing process to make a hemispherical and complex cup. Hydraulic oil was used to apply different amounts of fluid pressure. The work of this study was done in the following three states: In the first state, the experimental work was done without fluid pressure, so the product has wrinkles. In the second state, flaws like wrinkles were fixed by adding 1N/mm2. At a pressure of 1.7 N/mm2, the third state was done. The results show that a product with a blank holder force (BHF) that is neither too high nor too low may be free of defects. When BHF is low, faults in the cylinder cup look like wrinkles, and when BHF is too high, the cylinder cup breaks. So, the BHF value should change depending on the material, thickness, and nature of the product.

Study on the key process parameters of hydrodynamic deep drawing on the stainless steel single sink with countertop

Stainless steel single sink with countertop (SC) has the characteristics of large depth and asymmetric countertop. Its traditional stamping process is mainly realized by the combination of multi-stage deep drawing and annealing process, which leads to the complex manufacturing process, long production chain and poor consistency of products. Based on finite element analysis software (Dynaform) with nonlinear dynamic display algorithm, numerical simulation analysis and research are carried out on the parameters of hydrodynamic deep drawing. First, the sink and the part of countertop are preformed into a cylinder shell, and then the excess of the cylinder shell is drawn back to the countertop. The research results show that the hydrodynamic deep drawing process can effectively improve the flow uniformity of stainless steel sheet, increase the forming of stainless steel tank, drawing a more uniform wall thickness, thus effectively improve the quality of single tank with countertop by setting up reasonable preform structure, controlling the liquid pressure and its loading paths and blank-holder force.

Investigation on improvement of limit drawing ratio in two-stage hydrodynamic deep drawing of cylindrical cups

Investigation on improvement of limit drawing ratio in two-stage hydrodynamic deep drawing of cylindrical cups

Influence of the key process parameters in hydrodynamic deep drawing utilizing a combined floating and static die cavity

This study focuses on the effects of the key process parameters during a modified hydrodynamic deep drawing utilizing a combined floating and static die cavity (HDDC). A two-stage hydraulic loading path is recommended in the novel process, and each stage of the hydraulic loading path is a linear loading path with an inflection point. The method to evaluate the wrinkle and forming dimension precision of the formed parts is introduced at first. Then, the influence of the key parameters of the two-stage hydraulic loading path as well as the blank holder force on the dimension accuracy and surface quality of the formed parts was studied in detail. The results showed that the influence of the liquid pressure during the second stage is more significant than that in the first stage in hydrodynamic deep drawing utilizing a combined floating and static die cavity. The initial pressure of the second stage and the maximum pressure arriving moment during this stage have a significant impact on the dimensional accuracy of the formed parts, and the smaller initial pressure or the later the maximum pressure of the second stage arrives, the higher the accuracy of the formed part is. Similarly, the influence of the blank holder force in the second stage on the forming accuracy is more significant than that in the first stage.

Investigation of consecutive two-stage hydrodynamic deep drawing of aluminum cylindrical cups

In the deep drawing process, achieving a higher drawing ratio has always been considered by researchers. In this study, a new concept of hydrodynamic deep drawing with two consecutive stages without additional operations such as annealing is proposed to increase the limit drawing ratio of the cups. The effective parameters were investigated numerically and experimentally in the forming of Al1200 cylindrical cups. At first, the desired value of punch diameter ratio was determined based on finite element simulation results and was utilized to increase the cup formability. Next, the effects of pressure paths on the cup thickness, separation, and rupture were studied in each forming stage. The cup formability was investigated based on a new proposed framework to obtain the maximum possible limiting drawing ratio, and the desired conditions were determined. Finally, a cup was formed with a high drawing ratio of 3.4 which was a good achievement in comparison with the literature.

A novel hydrodynamic deep drawing utilizing a combined floating and static die cavity

A novel method named hydrodynamic deep drawing process utilizing a combined floating and static die cavity (HDDC) was proposed in this research, in order to depress wrinkling during hydrodynamic deep drawing process to form a conical cup with higher height. A special experimental setup of a combined die cavity, which a static chamber inlaid with an inner floating die cavity, was designed to implement the modified hydrodynamic deep drawing experiments. At first, the feasibility of the modified method was evaluated in detail by numerical analyses and experimental tests. Then, the effects of the liquid counter pressure in die cavity on the forming process were also studied. It was found that the proposed method HDDC was feasible and the suppressing wrinkling effect dramatically came into being by using a floating die cavity during the hydrodynamic deep drawing process for conical cups of higher height. The rigid contact between the crater corner of the floating cavity and the blank contributes to the suppressing wrinkle effect during the hydrodynamic deep drawing process utilizing a combined floating and static die cavity. The hydrodynamic deep drawing process of conical cups utilizing a combined die cavity becomes more robust compared with the conventional hydromechanical deep drawing process.

Effect of Anisotropic Yield Functions on Prediction of Critical Process Window and Deformation Behavior for Hydrodynamic Deep Drawing of Aluminum Alloys

Owing to the reduction of rupture instability and the avoidance of wrinkle defect, the hydrodynamic deep drawing (HDD) process is gradually becoming attractive for fabricating lightweight and complicated products. Meanwhile, since metallic materials present anisotropic deformation behavior, it is necessary to select an appropriate constitutive model for the prediction of plastic deformation behavior of applied material with high precision. In the present research, several anisotropic yield criteria, namely, Hill’48, Yld2000-2d, and BBC2005, were implemented to investigate the effects of yield functions on the prediction accuracy of the critical process window and deformation behavior for the HDD process of 2024 and 5754 aluminum alloys. Material constants in the yield criteria were determined by applying uniaxial and equi-biaxial tension tests and optimizing an error-function using the Levenberg–Marquardt algorithm. Furthermore, the process window diagram was computed utilizing the stress analytical model combined material properties with workpiece geometrical features. Numerical simulation results of predicted material anisotropic parameters, process window, and HDD deformation for aluminum alloys were compared with the experimental data. Through the comparison of diverse yield criteria based on materials’ anisotropic coefficients, critical process window prediction, earing profile, and thickness distribution, it was revealed that the Yld2000-2d and the BBC2005 yield criteria can offer more precise models of material behavior in planar anisotropy properties for the HDD process of 2024 and 5754 aluminum alloys.

Analysis of the effects of tool and process parameters in hydrodynamic deep drawing assisted by radial pressure

Among the various techniques of sheet hydroforming, hydrodynamic deep drawing assisted by radial pressure (HDDRP) has showed good results to shape parts with uniform thickness distribution and high drawing ratio. In this paper, improving formability of the parts in HDDRP is taken into consideration and the effects of some geometrical parameters such as the die profile radius and the gap between the die and the blank holder, and some process parameters such as pressure path and friction coefficient are investigated on thickness distribution of cylindrical cups and punch force. The pressure path has a great effect on the formability. The results showed that increasing the maximum pressure reduces part thinning in the critical regions. Increasing the pressure above a certain value does not have a significant effect on the part forming, but it increases the punch force. The most appropriate pressure path for forming the part studied in this paper is 27 MPa. Furthermore, thinning of the part and maximum punch force decreases by decreasing the friction between the sheet and blank holder. Moreover, increasing the friction coefficient between the punch and sheet to a certain value (0.2) improves forming condition that results in decreasing thinning of the part. Increasing the friction coefficient more than this value does not have a significant effect on forming the part. Friction between the punch and the sheet does not affect the maximum punch force. The results also illustrated that by increasing the gap between the blank holder and the die to 1.2 mm which is more than the thickness of the sheet, thickness reduction of the part and maximum punch force decreases. Increasing the gap above this value does not have a significant effect on ease of sheet flow and improving part formability.

A Comprehensive Thinning Analysis for Hydrodynamic Deep Drawing Assisted by Radial Pressure

Aiming to achieve a perfect concept of thinning in hydrodynamic deep drawing assisted by radial pressure (HDDRP), the formability of pure copper thick sheet was investigated. Many process parameters affect the quality of the product during HDDRP. The purpose of the present study is to understand simultaneously the effect of process parameters including maximum fluid pressure, punch velocity, friction coefficient between punch and blank, friction coefficient between die and blank, punch nose radius, die entrance radius, the gap between die and blank holder and prebulging pressure on the sheet thinning. The process was initially simulated via explicit finite element (FE) code ABAQUS. To verify the simulation results, the copper sheet was formed by experiment. After experimental validation, the FE model was used for performing a set of experiments designed by Taguchi L27 orthogonal array. Signal-to-noise ratio and the ANOVA techniques were used to calculate the importance and contribution of each parameter. Results reveal that a higher corner radius of the punch and a higher die entrance radius lead to an increase in thickness reduction at the critical region of the final cup. Moreover, optimization results represent an improvement of 11% in thinning compared to conventional results.

Optimization of pressure paths in hydrodynamic deep drawing assisted by radial pressure with inward flowing liquid using a hybrid method

Hydroforming is a convenient method for applying fluid to produce parts with high strength-to-weight ratio. Hydrodynamic deep drawing assisted by radial pressure with inward flowing liquid process is considered as a type of hydroforming. In this method, radial and chamber pressures are two most important parameters. The values of these parameters at any moment play important roles on the quality of final part. In this study, based on a hybrid method, the chamber and radial pressure paths in hydrodynamic deep drawing assisted by radial pressure with inward flowing liquid process are optimized. In this method, an adaptive simulation that is integrated with the fuzzy control system with the artificial bee colony (ABC) algorithm is used to determine the optimized radial and chamber pressure paths. The achievement of a conical part with minimum thinning and without wrinkling has been defined as the optimization goal. The validity of radial and chamber pressure paths obtained from optimization algorithm is verified through an experiment. Results showed that utilization of the optimized loading path yields a part with lower maximum thinning and without wrinkling.

Investigation of a Modified Hydrodynamic Deep Drawing Assisted by Radial Pressure with Inward Flowing Liquid Process

Hydrodynamic Deep Drawing (HDDRP), the combination of hydroforming and conventional deep drawing, accommodates the advantages of the two processes. A technique, called HDDRP with inward flowing liquid, has been introduced based on the idea of insertion of radial pressure around the blank rim. The radial pressure created on the blank edge, can increase the drawing ratio. Thus, increasing the radial pressure to an amount greater than the cavity pressure, and independent control of these pressures is the basic idea of this research for forming cylindrical parts. To perform the experiments, two independent pumps were used to provide the two pressures independently. The pressure supply system and the die set were designed in a way that provides simultaneous control of the pressures throughout the process. Then, the effects of radial pressure paths on thickness distribution of cylindrical St13 cups were investigated. In addition, a comparison between HDDRP and HDDRP with inward flowing liquid processes has been performed experimentally. Results indicated that using a higher radial pressure than the cavity pressure and controlling their values at any moment of the process enhances the thickness distribution of the formed part in all regions.

Investigation of Forming Cylindrical Parts in a Modified Hydrodynamic Deep Drawing Assisted by Radial Pressure With Inward Flowing Liquid

Among the sheet hydroforming processes, hydrodynamic deep drawing (HDD) process has been used to form complex shapes and can produce parts with high drawing ratio. Studies showed that radial pressure created on the edge of the sheet can decrease the drawing force and increase drawing ratio. Thus, increasing of radial pressure to an amount greater than chamber pressure, and independent control of these pressures, is the basic idea in this study. In this research, the effect of radial and chamber pressures on formability of St13 and pure copper sheets in the process of hydrodynamic deep drawing assisted by radial pressure (HDDRP) with inward flowing liquid is investigated. Giving that a significant portion of the maximum thinning of the formed part occurs in the beginning of the process, the pressure supply system used in the experimental tests was designed in a way, which provides simultaneous control of the radial and chamber pressures throughout the process. Thickness distribution, forming force, and tensile stresses are the parameters that were evaluated in this study. Results indicated that using a higher radial pressure than the chamber pressure and controlling their values in the initial stages of the process enhances the thickness distribution of the formed part in all regions. A comparison between the thickness distribution and maximum forming force of the formed parts by the HDDRP and HDDRP with inward flowing liquid methods showed that by applying the later method, parts with more uniform thickness distribution and less maximum thinning and forming force can be achieved.

Simulation and Experimental Studies on Hydrodynamic Deep Drawing of 2198 Aluminum Lithium Alloy

The process of hydrodynamic deep drawing of Al2198 was investigated by finite element (FE) simulation and experimental works. The effects of die cavity pressure, blank holder gap and pre-bulging pressure on the forming process and the thickness distribution were evaluated. The results indicate that the pressure inside the liquid chamber and the blank holder gap or blank holder force are the main factors affecting hydrodynamic deep drawing process. In addition, appropriate pre-bulging pressure is beneficial to form good quality parts with a relatively uniform wall thickness.

Optimization of Hydroforming Process for Deep Drawing of AA7075 Using Finite Element Simulation and Response Surface Methodology

Aluminum 7075 is a functional aerospace alloy that has high strength and low formability during room temperature deep drawing. Therefore, to avoid warm forming process and relative difficulties, careful control in the process design is needed to enhance quality of drawn part and improve die life. In the present work, an attempt was made to experimentally and numerically study the effect of hydrodynamic deep drawing process such as die geometry and fluid pressure on thinning ratio and punch force. Statistical analysis based on response surface methodology was carried out to correlate empirical relationship between die corner radius, punch corner radius and die fluid pressure as process factors and maximum thinning ratio and punch force as responses. Sensitivity analysis was also performed to find out the factor having greatest impact on aforementioned responses. Further, optimization was carried out by using desirability approach to find out optimal parameter setting to attain minimum thinning and forming force simultaneously. Results indicated that punch and die corner radius followed by fluid had significant effect on the process quality characteristics. Moreover, setting of 9.3 mm punch corner radius, 2 mm die corner radius and 26 MPa fluid pressure resulted in 71% desirability incorporating 31% thinning and 175 MPa punch force. The obtained optimal results were then verified through both FE simulation and confirmatory experiment.

Effect of pre-forming and pressure path on deformation behavior in multi-pass hydrodynamic deep drawing process

Hydrodynamic deep drawing (HDD) is an effective method for the fabrication of the sheet metal parts with deep cavity and complex surface configuration. Despite the remarkable progress that has been made on the development of one-stroke HDD process, a number of fundamental challenges are still unsolved in the multi-stage HDD technology due to the unique process allocation and continuous deformation behavior. In this study, the effect of pre-forming parameters and loading locus of cavity pressure on the sequential deformation of aluminum alloy is explored to determine the suitable working conditions to form a conical part with deep cavity using multi-pass HDD process. Based on the equal allowance function method, the material deformation amount for the multi-pass process is allocated and optimized. In addition, the defect patterns including wrinkling and tearing during the multi-step process are discussed. The effect of pre-forming depth and loading loci of cavity pressure on the dimensional accuracy and thickness variation of the workpiece is analyzed, the appropriate pre-forming depth and loading loci of cavity pressure are achieved by using numerical models implementing diverse yield criteria. The results mirror that yld2000-2d and BBC2005 yield functions predict the pre-forming depth more accurately with respect to Von Mises isotropic formulation and Hill’48 yield criterion. However, the prediction accuracy of the pre-forming stage is superior to that of the final forming period using yld2000-2d yield formula due to the error accumulation and the effect of prestrain on the sequential process. Moreover, the reasonable loading path of cavity pressure for the intermediate cylindrical part is characterized by three feature points, whereas the suitable pressure locus for the final conical part is featured with four unique points and three distinct segments containing low-pressure stage, pressure-raising stage and full pressure period. By using the suitable working conditions, the well-formed conical part with homogenous thickness distribution, desirable surface finish, and high dimensional precision is fabricated, which highlights that the proposed multi-step HDD technology is valid for the integration and precision forming of the workpiece with complex feature and high drawing ratio.

Investigation of Wrinkling in Hydrodynamic Deep Drawing Assisted by Radial Pressure with Inward Flowing Liquid

The formation of wrinkling in deep drawing processes generally occurs in the two area of flange and cup wall. In this paper, a geometric method based on FEM simulation has been developed to investigate the wrinkling in the wall area of conical cups. Wrinkling wave variation was considered as the criterion of wrinkle defect. The forming process in this study is hydrodynamic deep drawing assisted by radial pressure with inward flowing liquid. The effects of radial pressure and cavity pressure on wrinkle phenomenon have been investigated. To verify the results of the simulation, experiments were performed on the steel sheets. Good agreement between the simulation and experimental results shows the reliability of this method in the wrinkling study. Results showed that radial pressure and cavity pressure have significant impacts on creation or prevention of wrinkling in the side wall.

Process window calculation and pressure locus optimization in hydroforming of conical box with double concave cavities

With the enhancement in the functional integration of components and concentration on lightweight materials, complex sheet metal parts are widely used in automobile and aviation industrial clusters. Consequently, the sheet hydroforming process has become an attractive fabricating technology for forming lightweight materials and complicated products. In this research, the hydrodynamic deep drawing (HDD) process of a composite conical box with double concave cavities was investigated through theoretical analysis, numerical simulation, and process experimentation. Furthermore, the process window diagram (PWD) was calculated using the stress analytical model combining material properties with workpiece geometrical features. The influence of cavity pressure loading locus on the forming quality of the fabricated part and the deformation behavior of aluminum alloy was explored. The forming results indicated that the initial pressure, full pressure, and loading locus are the fundamental parameters directly related to the forming quality and dimensional accuracy. For the conical part with composite features, the reasonable initial pressure value is crucial for the thickness homogeneity of the double concave characteristics, whereas the magnitude of the full pressure is vital for improving the quality of the conical feature. In addition, the optimal loading locus of the cavity pressure is characterized by two turning points, which are related to the punch corner radius, die shoulder radius, blank thickness, and angle of the conical feature.

Investigation of step pressure path influence on cylindrical cup formation through hydrodynamic deep drawing

In recent years, hydroforming process has been applied in different industries such as aerospace, automotive industry and military industry due to its advantages, like high dimensional accuracy, capability of forming complicated-shaped parts and high drawing ratio. Hydrodynamic deep drawing with radial pressure is one of the hydroforming processes. In this paper, forming of cylindrical cups in hydrodynamic deep drawing with radial pressure is investigated and the effect of pressure path on the cup thickness distribution and punch force was studied. In this study, two pressure paths (liner pressure with maximum pressure and step pressure) were used and their thickness distributions were compared. The results of this study have shown that by choosing the step pressure path, the quality of the formed cup increases and more uniform thickness distribution will be obtained.