Effect Of Blank Holding Force Research Articles

Investigation on the Effect of Blank Holder Force and Initial Blank Size on the Thinning Problem of the Fuel Tank Part Made from Aluminum Alloy Sheet 5754-O under Deep Drawing Process

Deep drawing process is a common sheet metal forming technique in motor vehicle manufacturing. There are three primary defects that could be occur in deep-drawn parts: tearing, wrinkling, and thinning. When the thinning is difficulty detected by visual inspection. As a result, this study aims to address the thinning issue in a fuel tank part made from an aluminum alloy sheet AA5754-O 1.5 mm thick under cold working deep drawing process, while the manufacturer's desired upper limit for thinning is 20%. Two influential parameters viz. blank holder force and initial size of blank, were investigated and optimized by using Finite Element Analysis (FEA) through PAM-STAMP simulation software with the validated material model was based on Hill’s 1948 anisotropic yield criterion with Swift hardening law. The mechanical parameters in the mentioned model were derived from the results of uniaxial tensile tests. In conclusion, both the hydraulic cushion's blank holder pressure and the initial size of the blank were found to influence the thinning of the part, either individually or in combination. Despite optimizing both parameters, they were unable to consistently achieve the desired limit.

Investigation of the effects of lubrication type, blankholder force and force holding time on the spring-back behaviour for hat-shaped MART steels

ABSTRACT In this study, hat-shaped bending experiments have been conducted on MART1200 and MART1400 Ultra-High-Strength Steels (UHSS). To investigate the influence of different lubrication conditions, on the spring-back, three different lubricant types (Graphite, Teflon film and Teflon film + Graphite) have been used in the experiments. A constant 6.5 tons of bottoming force has been applied at the end of the bending stroke and the force has been held on the samples for 0, 10s and 60s to observe the effect of force holding time on the spring-back. In addition, the effect of blankholder force on the spring-back has also been investigated for MART1400 steel. It has been found that the decrease of blankholder force and the friction between the die and sheet interfaces has considerably reduced the spring-back in the sidewalls and flange regions and also lowered the side wall curl. It has been revealed through finite element analysis that the sheet bottom has suffered a larger deformation in lower friction conditions and blankholder forces and caused in the reduction of spring-back.

A numerical study on warm deep drawing of polypropylene

AbstractWarm deep drawing of polypropylene, a semi‐crystalline thermoplastic polymer, is studied using finite element analysis. In this process, a circular polypropylene blank is preheated to a temperature much below its melting temperature and deep drawn into the shape of a flat‐bottom cylindrical cup using a punch‐die combination, both initially at 25°C. The material model used for the analysis considers the effects of varying temperature and strain rate during the deep drawing process on the depth of draw. The effects of blank holder force, initial blank temperature, blank diameter, and die and punch corner radii on the depth of draw are determined. Thickness, temperature, and strain variations in the drawn cups, punch forces, and failure modes are also determined.

Effect of blank holder force on joining quality of the flat clinch-rivet process

Effect of blank holder force on joining quality of the flat clinch-rivet process

Effect of blank-holder force on springback of ultra-thin copper sheets

After forming by plastic deformation, it’s rare that the part produced retains its shape perfectly after removing the tools, the shape and dimensions that the tools imposed on it. This change in shape is mainly due to springback. This study focuses on the springback of U-shaped channels made of thin sheets of beryllium copper alloy 0.1 mm thick. The intensity of springback depends on several factors of part geometry and process parameters. Among the parameters of the process, we investigated the clamping force, which is an essential factor influencing the final shape of the part. It is shown that the springback is inversly proportional to the clamping force. As a consequence, there is no significant change of the geometry of the final part. Indeed, uneder high clamping force, the internal stresses (already existing in the material) become very important, which makes it possible to attenuate significantly the local moment effect in bending. The result is an uniform distribution of residual stresses in the thickness of the sheet which is studied in this paper.

Effect of Blank Holder Force and Edge Radius on Joining Strength in Flat-Clinching Process

A lightweight structure has been often mentioned in the automotive industry due to the increasing cost of energy as well as environmental legislation. Multi-material design is applied to reduce the weight of a car body. To join dissimilar sheet materials, it is quite difficult to achieve by welding processes. A flat-clinching process is one of the mechanical joining processes, which have join-ability of dissimilar sheet materials by plastic deformation. The purpose of this paper was to study the clinch-ability to join AA1100-to-AA1100 aluminum, AISI1010-to-AISI1010 steel, and AISI1010 steel-to-AA1100 aluminum sheets. Furthermore, the effect of both blank holder force (BHF) and edge radius (BHR) in the flat-clinching process on a joining strength was investigated. A shear strength test was conducted to examine the joining strength. The results show that the flat-clinching process can be successfully applied to join the similar sheet materials with the formation of interlocking. However, to achieve the joint of the dissimilar sheet materials, the AISI1010 steel sheet must be on the punch side. Also, both the BHF and the BHR significantly influent on the joining strength.

Manufacturing and Performance Analysis of Q390A High-Strength Steel V-Shaped Stiffeners via Warm Drawing Process

Herein, warm drawing technology assisted by an electric current heating system is proposed to minimize the formation of wrinkles and cracks on the surface of Q390A high-strength steel V-shaped stiffeners during cold forming. V-shaped stiffeners with excellent properties were obtained by elevating the forming temperature and improving the material plasticity. The influence of temperature and tensile rate on the mechanical properties of the Q390A high-strength steel at 400-800°C was investigated. The effects of blankholder force and friction coefficient on the formed parts were simulated and analyzed by the finite element simulation software DYNAFORM. The law of heating and cooling for the formed parts during the forming process was studied through the electric current heating experiments. The forming temperature was controlled from 530 to 720 °C as the current density was maintained in the range from 7.3 to 8.5 A/mm2. Surface oxidation, cracks, sheet warping degree, sectional thickness distribution, mechanical properties, and microstructure of the V-shaped stiffeners formed at 400 to 700 °C were analyzed. The results show that the V-shaped stiffeners formed at 600 °C possess excellent overall properties.

Formability of Laser Welding Plates of Dissimilar Materials

Hydraulic deformation is a procedure utilized for forming sheet by applying the pressure driven pressurized fluid on the sheet. This procedure is described by its capacity to give homogenous strain distribution along the blank with high mechanical properties. The analysis of the sample deformation process has performed by using circular welded plate by laser technique of dissimilar steel plate (SS304-St1008) with thickness 1mm using profile radius for lower die 2 mm under the effect of blank holder force 10 kN. The metal thickness checked and the SEM test investigated for the formability product of laser welded plate. Discoveries show that by and large better mechanical characteristics, for example, formability, tensile and yield strength of welded joints can be achieved by using laser welding and the blank deformation becomes uniform with the hydraulic force. It is useful to avoid thinning of the blank with suitable friction coefficient between the die and the blank. Based on the experimental results of dissimilar metal, it found, that the joint weld strength parts, was lesser than the base strength, so the fracture is occur on the base metal. The SEM investigation indicated that the joining process between the SS304 and St1008 was occurred by heating due to laser on the other hand the depth of the interface between the joint materials had the range of 3-5 µm. The EDS examination indicated that the interface zone of the jointed contained Cr, Ni, C and Fe, the left side is SS304 passing through the region zone and ending with St1008, the ratio of Fe increased and the other elements decreased.

Experimental and numerical study of DC04 sheet metal behaviour—plastic anisotropy identification and application to deep drawing

This paper deals with the identification and modelling of the deformation behaviour of DC04 sheet metal. An application of the identified behaviour model in the framework of finite element (FE) simulation of deep drawing is performed. Uniaxial tensile tests in three directions are performed to reveal the in-plane plastic anisotropy of the DC04 sheet. The Hill48 quadratic criterion is introduced to represent the initial plastic anisotropy, while the work hardening is represented by power and exponential type laws. Parameters of the established behaviour model are identified using two methods based on Hill48 criterion. FE simulations of uniaxial tensile tests are carried out to validate the identified parameters and thus retain the identification method giving best fitting of performed tests. The identified plastic behaviour model, including initial plastic anisotropy and hardening, is then introduced in FE simulation of deep drawing of waterproof case for a truck, in which the effect of blank-holder force on the drawpiece quality is analysed in order to determine the optimum thickness. Then, the effect of combination between plastic anisotropy and friction anisotropy on the sheet thickness distribution is investigated. The performed analysis shows that the plastic and friction anisotropies have an effect on the DC04 sheet metal deformation.

A Comparative Study on Formability of the Third-Generation Automotive Medium-Mn Steel and 22MnB5 Steel

Third-generation advanced automotive medium-Mn steel, which can replace 22MnB5 steel, was newly developed to improve the lightweight and crashworthiness of automobile. Studies on the formability and simulation method of medium-Mn steel have just been initiated. In this study, finite element simulation models of square-cup deep drawing were established based on various material property experiments and validated by experiments. The effects of blank holder force (BHF), fillet radii of tools (die and punch) on the maximum drawing depth (MDD), thickness distribution of the formed products, and the microstructure before and after forming were investigated and compared with those on 22MnB5 steel. Results show that the MDD of the two steels decreased with increased BHF but increased with the fillet radius of punch; however, the fillet radius of die showed no significant effect on the MDD for both steels. Compared with hot-formed 22MnB5 steel, the martensitic transformation of the hot-formed medium-Mn steel is rarely influenced by the process parameters; thus, it holds the complete, fine-grained, and uniform martensitic microstructure. Moreover, the medium-Mn has better formability, lower initial blank temperature, and smaller impact of BHF and fillet radius of tools on the hot-formed product. Thus, a theoretical basis for the replacement of 22MnB5 steel by medium-Mn steel in hot forming process is provided.

Experimental and finite element investigation on wrinkling behaviour in deep drawing process of Al3105/Polypropylene/Steel304 sandwich sheets

The three-layer aluminum 3105 – polypropylene – 304 steel components are fabricated using the deep drawing process. Then, finite element (FE) simulation of this process was carried out in ABAQUS software and the results of numerical and experimental studies regarding the effects of blank holder force on wrinkling of blank’s flange and punch force were compared to each other. The results indicate a reduction in wrinkling of the deep drawn cups with increase in BHF. In addition, FE simulation could predict the tearing place in the samples well.

Research on Stamping Process Design and Forming Law of Floor Beam

Aiming at the problems of cracking and wrinkling in the forming process of floor beam, the design of the drawing die is finished, and the finite element analysis software DYNAFORM is used to analyze the drawing process of the floor beam, and the effects of blank holder force and drawbead on the formed part are analyzed. With the maximum thinning rate and maximum thickening rate as the evaluation index, the optimized process parameters are that blank holder force is F = 270kN and drawbead is set to segmented drawbead. The results have important reference value for the forming application of floor beam.

Study on the effects of forming parameters on the plastic flow of axisymmetrical curved parts in stamping process

Due to the axisymmetrical parts easy to occur fracture or wrinkle in stamping process, by using the professional press finite element software and the control variable method the simple finite element simulation analysis on the barrel member is performed. In order to explore the effect of blank holder force, coefficient of friction and other factors on the barrel shape of flow parts in the stamping process and the influence on the forming quality of stamping parts are determined.

A New Damage Constitutive Model for Thermal Deformation of AA6111 Sheet

Hot tensile tests were conducted using a Gleeble 1500, at the temperature range of 623 K to 823 K (350 °C to 550 °C) and strain rate range of 0.1 to 10 s−1. Flow stress is significantly affected by temperature and strain rate. As strain increases; the flow stress first rapidly increases, subsequently maintains a steady state, and finally drops sharply because of damage evolution. The features and mechanism of the damage were studied utilizing a scanning electron microscope. Micro-void nucleation, growth, and coalescence result in the failure of the hot-formed specimen. A damage equation based on continuum damage mechanics and damage mechanism in hot metal forming was proposed. A unified viscoplastic damage model coupled with strain, strain rate, temperature, dislocation, hardening, damage, damage rate, and so on was developed and calibrated for AA6111 using Genetic Algorism Tool in three steps. This model can be used to describe viscoplastic flow behavior and damage evolution at various temperatures and strain rates. The model was implemented into the finite element (FE) model in ABAQUS platform via the variable user material subroutine. Thus, the FE model could be employed to study the damage distribution and the effects of blank holder force (BHF) and forming velocity on hot cylindrical deep drawing. It is revealed that lower BHF and higher velocity are beneficial for drawability. A good agreement between simulated and experimental results has been achieved.

Effect of Blank Holding Force on the Gas Tightness of Paperboard Trays Manufactured by the Press Forming Process

Although several authors have studied 3D forming using the press forming process, the gas tightness of polymer-coated paperboard trays has not been widely researched. In this paper, the effect of blank holding force on the surface quality and tightness of press-formed paperboard trays was researched. The press-formed trays were heat-sealed with a multilayer polymer lid. The tightness of the trays was analyzed by following the oxygen content of the packages over the course of 14 d and by using a penetrant coloring solution to locate possible leaks. The results indicate that the blank holding force had a great effect on the quality and tightness of the trays, especially in the case of a rectangular geometry. The geometry of the formed trays played a significant role in process parameter selection, and more demanding geometries emphasize the importance of parameter optimization. However, with the correctly selected parameters, the use of modified atmospheric packaging (MAP) in polymer coated paperboard trays was shown to be possible. The oxygen content of both analyzed geometries was found to be less than 1% 14 d after sealing. It was also demonstrated that the gas tightness of a seal cannot be confirmed using a penetrant solution test exclusively.

Effect of Forming Parameters on Springback of Advanced High Strength Steel DP800

Springback is one of the main quality defects in the sheet forming. In this paper, numerical simulation is used to analyze the effects of blank holder force, friction coefficient, blank thickness, die corner radius and stroke on springback. The effect of blank holder force and blank thickness on springback is obvious. Springback decreases as the BHF and blank thickness increase. Increasing friction coefficient between tools and blank shows a good suppression effect on springback. Larger die corners increase the curvature of side wall and worsen the springback, but the springback of flange is reduced. The greater the stroke is, the larger the final springback will be.

Effect of Blank Holder Force on Strains and Thickness Distribution in Deep Drawing Process

Effect of Blank Holder Force on Strains and Thickness Distribution in Deep Drawing Process

Multi-Objective Optimization and Research of Hot Stamping Process Parameters

The hot stamping and quenching process of U-shaped parts is simulated by ANSYS/ LS-DYNA software. The influence law of forming process and temperature field in quenching process of U-shaped parts is obtained through the simulation of forming and quenching process under different blank holder force, punch velocity and mould initial temperature. The results show that plate temperature changes with the punch velocity and mould initial temperature changes, while the effect of blank holder force on plate temperature can be neglected.

Influence of the Blankholder Force on the Accuracy of the Rectangular Drawn Parts Made from Steel Sheets

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.

Prediction of Failure Modes during Deep Drawing of Metal Sheets with Nickel Coating

To optimize the process parameters, it is necessary to exactly predict failure modes during deep drawing of coated metal sheets, where two main failure forms are fracture and wrinkling. In this paper, finite element simulations based on continuous damage mechanics were used to study the failure behavior during a cylindrical deep drawing of metal sheets with nickel coating. It is shown that taking the effect of blank holder force into account, these two failure modes can be predicted. The simulation results are well consistent with that obtained from experiments.