Blanking Process Research Articles

Realization of effective laser blanking process by heat zone spread resistance coating and optimization methods

Laser blanking process is widely used for the ability to cut complex profiles on sheet metal without Die. Laser blanking process needs optimization methods to reduce wastage of raw material and cutting time. The work entails optimization of sheet metal nesting allocation to reduce wastage and also optimizes cutting time by reducing ideal travel distance. The laser irradiation induces heat affected zone in the cutting surface leading to poor service life of the components in the cutting edges. The development of AlN heat zone spread resistance coating over steel substrate through a reactive sputtering process is presented. The thin film preparation is carried out in two different combinations of Argon and Nitrogen ratio namely 1:1 and 2:1, respectively. The coating over the steel substrate is exposed to laser to analyze the micro-structural change induced by the laser in the cutting edges. The coating is observed to mitigate the spreading of heat zone. The coatings are further subjected to tafel polarization to analyze the corrosion resistance of the steel substrate. In this paper, an approach has been made to obtain an optimal allocation based on the selection of different dimensions of the AlN coated sheet and also to calculate the utilization and cutting time. The proposed method provides an optimal layout for parts using a software and to obtain minimum travel ideal distance a heuristic algorithm is used. Since the sheet is coated there is also an add-on advantage in minimizing cutting time. Finally, an Optimal Pareto front is developed between wastage and ideal cutting distance, in order to provide choices for the user to select the requirement in both cases.

An analytical approach for the determination of the temperature distribution in the cross section of a sheet metal caused by inductive heating

Abstract Fine blanking is one of the leading technologies in sheet metal separation. Its advantages in comparison to punching are to be found in precision and smooth cut of the cut surface. However, fine blanking faces its process limits at elevated sheet thickness and material strength. Especially the process limits in terms of tensile strength tend to be a handicap in the light of the paradigm shift of the automotive sector: lightweight construction demands for materials with high tensile strength and high stiffness. In order to fulfill the needs of car industry, fine blanking has to qualify itself on behalf of high strength steels. This is imperative to maintain its advantages in terms of productivity and precision over competing technologies. A promising approach to enable fine blanking of high-strength steels is, in analogy to bulk metal forming, to increase process temperatures up to recrystallization temperature. A yield stress decrease will lead to an extension of the number of processible materials and part quality. This effect has not yet been researched for fine blanking. The focus of this paper will be put onto inductive heating and geometrical heating strategies will be discussed. In order to guarantee ideal and reliable temperature conditions in the metal sheet for a subsequent fine blanking process, it is imperative to estimate the heat propagation and profile inside the metal sheet. An approach to determine analytically the temperature profiles in a metal sheet after inductive heating based on energy considerations will be presented.

Investigation of the Mechanical Punch Loads during Fine Blanking of High-Strength Steels with Cemented Carbide

Abstract The increasing ecological demands require emissions reduction of automotive vehicles. This challenges the automotive industry for the increased application of light-weight components made of high-strength steels. The processing of high-strength steels brings many manufacturing processes to its mechanical limitations. In fine blanking, conventional tool materials lack on compressive strength in order to separate high-strength sheet metal. Nowadays, high-speed steels used for tool applications must be substituted with materials having a higher compressive strength, such as cemented carbides. However, with the increased compressive strength the carbides show a significantly lower ductility. During a repeated stripping off process, the low ductility of cemented carbides leads to a premature punch fracture and with this reduced economic feasibility of the process. The stripping off force required for the final punch ejection is generated by the clamping force applied by elastic deformation of the scrap material. Currently, phenomenological models exist allowing only approximate prediction of the clamping force. The precise prediction is not possible, since the clamping force depends on plenty parameters, such as sheet material strength and thickness, as well as punch geometry, ambient temperature, nest positioning, etc. A comprehensive investigation of the influence of these parameters on the punch load is strictly required. In order to enhance the applicability of cemented carbides as an alternative punch material in fine blanking of high-strength steels, a tool for process forces quantification, such as clamping and stripping off forces during one cutting-ejection cycle, must be provided. To achieve this goal, a comprehensive numerical study on the influence of process parameters such as sheet metal strength, sheet thickness and cemented carbide grade on the cutting, clamping and stripping off forces is performed. The developed three-dimensional numerical model of a fine blanking process with an elastic punch is validated by means of the experimentally measured punch force during an industrial fine blanking process of spacer discs. Based on the obtained numerical results, a basic correlation between the clamping force during the cutting step and the stripping off force during the ejection step are analyzed. The identified tendencies are used to create an analytical model of the clamping force and a regression model of the stripping off forces. The developed models allow for improved prediction of the expected process forces during fine blanking of high-strength steels and with this for the selection of the appropriate grade of cemented carbide as a punch material.

Comparative study of Mechanical properties of Glass Carbon Hybrid Composites with fine blanking using analysis software and Experimental method

Abstract In the present advanced material technology applicable in the automobile, naval and aircraft structures, the composite materials reinforced with glass fibre, carbon fibre, etc., play important role due to the excellent properties such as high specific strength, strength to weight ratio, good corrosion resistance in the saline atmosphere. In this study, Glass Fibre Reinforced Plastic (GFRP), Carbon Fibre Reinforced Plastic (CFRP) and glass-carbon Fibre Reinforced plastic (GCFRP) laminated composites were manufactured by hand layup process. Then a hole was produced on each specimen, as per ASTM standards by fine blanking process. The values of the tensile strength and flexural strength of the composite specimen were determined and compared by stress analysis and experimental method. It has been found that strength of Glass-Carbon fibre hybrid composite is between CFRP and GFRP composites.

The influence of relative rolling reduction of sheet metal on the changes of deep drawing forces in multi drawing steps for cylindrical drawpiece without collar made from EN AW-1050A aluminium

The paper presents experimental results of investigations on deep drawing process of cylindrical drawpieces without collar in four drawing steps (single draw and three redraws). The research involved the use of EN AW-1050A aluminium blanks with diameter D = 66 mm. The material was prepared by rolling with different relative rolling reductions (z = 5%; 10%; 15% and 20%, respectively) at rolling mill DUO-100 and blanking process. In investigations of deep drawing, experimental force waveforms as the function of displacement for different relative rolling reductions of sheet metal made from aluminium were obtained.

Features of Manufacturing Spiral Corrugated Blanks From Various Profiles of Corrugations

The leading role in the field of using spiral mechanisms plays the design and manufacture of corrugated spiral working bodies, which are widely used in mixers, heat exchangers, machines for borontation of free abrasives, in the confectionery and pharmaceutical industries, etc. Increasing the requirements to the design and technological parameters, quality, reliability and durability, enhanced technological capabilities require deep analysis of existing structures and technologies of their production and the development of scientific research on theoretical and experimental studies and their successful implementation in production. The paper focuses on the development and implementation of new advanced technological processes of spiral corrugated and ring blanks. The results of theoretical and experimental research were based on the development and analysis of technological schemes for the formation of screw corrugated blanks in order to improve the mixing of bulk materials. The functional and structural and technological features of spiral corrugated blanks manufacture and the designing of the appropriate technological equipment and facilities with the withdrawal of the analytical dependences for determination of treatment regimes. The analytical dependences for determination of power and structural parameters of technological process of bending blanks between two cylindrical gear cross-sectional toothed wheels. Characteristics curves of spiral corrugated blanks on the basis of width and thickness of the lines and the workpiece step of 1 ... 3 mm thickness and with 15 ... 25….30 mm width are given in the paper. The results of the experiment show that labor productivity will increase by 20-30% in manufacturing, 2-3 times in control operations

Design and modelling of CRB cutting equipment for batch processing

Ceramic roller is more reliable than metal roller. However, ceramic materials are difficult to process due to their high hardness and great brittleness. They are easy to crack and easy to damage cutting tools. To batch processing of ceramic roller blanks (CRBs), a special ceramic roller cutting equipment (SCRCE) is designed to deal with CRBs of different diameters and lengths. To avoid clamping damage to CRBs, the SCRCE adopts the new clamping mechanism. The blanks are orientated to double rotating shafts with V-type sleeves to reduce friction. Moreover, the SCRCE adopts a new ring-cut method. The ring-shape cutting is used. The cutting spindle and the blanks are revolving at the same time in cutting processing. The design and modelling of the special cutting equipment is also finished. To analysis the axial displacement of CRBs while cutting, the simulation model with ADAMS is built and the related characteristic is simulated. The test result shows that the new type cutting machine is suitable for ceramic roller blank cutting process.

Fabrication, microstructure, and properties of a biodegradable Mg-Zn-Ca clip.

An Mg-Zn-Ca alloy biodegradable clip was fabricated by combining hot extrusion and blanking processing. Microstructure evolution was investigated by optical microscopy and electron backscattering diffraction and the occlusion properties of Mg-Zn-Ca alloy clip were evaluated in vitro and in vivo. It was found that the as-extruded Mg-Zn-Ca alloy exhibited a typical fiber microstructure. After blanking, the basal texture intensity increased because of the work hardening effect. Subsequent annealing treatment of the blanking clip can significantly weaken the texture while improving the ductility of the Mg-Zn-Ca alloy. It was found that Mg-Zn-Ca clips can maintain closure performance for 2 weeks in in vitro immersion tests while in vivo tests indicated that the Mg-3Zn-0.2Ca alloy clips fabricated by this preparation processing successfully occluded the blood vessels. These results suggest that the developed Mg-3Zn-0.2Ca alloy clip is a suitable candidate for biodegradable soft tissue fixation devices such as surgical clips. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1741-1749, 2019.

Development of methodology of experimental studies of control in crystallization of castings by optimizing the thermophysical properties of the elements of the gating system

The fundamental purpose of the proposed research is to identify and analyze important technological parameters by obtaining the characteristics of the studied thermal properties of hot tops, providing a stable mode of applying hydrodynamic pressure before the crystallization of the casting due to the heating of hot top part of the interrelated elements of the «gating system–casting» on the basis of means of providing computational experiments from the point of view of managing the production process of blanks of wearing parts.

Optimum clearance determination in blanking coarse-grained non-oriented electrical steel sheets: experiment and simulation

Blanking process plays a critical role in the deterioration of magnetic properties of coarse-grained non-oriented electrical steel of motors. With the decrease of grain number in the thickness direction, the deformation behavior in blanking process becomes different and complex. In this paper, the high-grade non-oriented electrical steel is selected for blanking tests within the relative blanking clearance range. The results show that there exists an optimum clearance which leads to the high-quality sheared edge for the application. Nevertheless, the exact value of optimum clearance cannot be provided by experiments. Therefore, a novel Voronoi-based FE model is established to analyze the blanking deformation behaviors of individual grains. The flow stresses of surface and internal grains are identified through the widely applied surface layer theory. The proposed FE model is an appropriate prediction tool for simulating the blanking process of non-oriented electrical steel sheets. Meanwhile, through the new proposed model, an exact optimum clearance determination method is established. The proposed methodology predicts that the optimum clearance for the investigated sheet is 13.8%t, which is further verified by the experimental data.

Numerical quantification of damage accumulation resulting from blanking in multi-phase steel

The high potentials of utilizing high strength steels in the automotive industry have been proved. However, there are still some unsolved challenges. Forming of a component that has been produced by blanking is one of these. Blanking is commonly used in sheet metal forming as the initial cutting process. Yet, it introduces damage into the blanked edges that in subsequent forming steps may lead to crack formation. This problem arises in particular in modern multi-phase steels and can currently not be avoided thoroughly due to a lack of understanding of the relevant influences. In the present work, the effects of the blanking process on an HCT980XD sheet were therefore numerically investigated. To achieve this, the Edge-Fracture-Tensile-Test method was simulated. By using this method, a conventional uniaxial tensile specimen is manufactured with one milled side and one blanked side. This allows to highlight the effect of blanking in a subsequent tensile test. In order to investigate the damage process, the coupled Modified-Bai-Wierzbicki model was applied to simulate first the blanking process and then the tensile test. The results revealed that during the blanking process, the failure initiated from the surface elements near the punch and propagated through the thickness. Meanwhile, another crack initiated from the opposite side of the sheet. The elements of these cracks experienced near pure-shear condition at both damage initiation and fracture moments. At the end of this step, the remaining damage, which is considered as the predamage of the next step, was higher in the middle of thickness. During the subsequent uniaxial tension, the crack in the specimen initiated at a shear cut edge and crossed the width. The possible detailed resolution of loading paths and crack formation shows that the damage mechanics simulation provides researchers with a powerful tool for assessing limit states in forming processes.

Burr formation and shear strain field evolution studies during sheet metal blanking

Sheet metal blanking is an industrial process widely used in automotive, electronics, aerospace and several other industrial applications. Burrs are the hard and sharp-raised edges formed at the cut edge of the blank during blanking process. Presence of a burr reduces the quality, accuracy and usability of the blank. So, it has to be removed by further processing like machining or deburring, which further increases the cost of production. Choosing proper process and geometric parameters can reduce the extent of burr. In this paper, finite element simulations of the blanking process for AA6082-T6 were carried out using the ABAQUS-CAE software package with various process and geometric parameters. Design of experiments (DoE) methodology was applied to understand the effects of the process and geometric parameters on the burr formation during blanking of metal sheets. This effort will not only help to optimize the blanking process, but also to increase the product quality and reduce the cost of production. Typical pattern of shear strain field evolved at various punch penetrations of sheet metal blanking is being studied.

Effects of fabric structure on the formability characteristics of thermoplastic composites under various process conditions

Thermoplastic composites are broadly utilized for structural and automotive applications due to their higher specific strength and modulus, higher strain to failure, recyclability, and unlimited shelf life. This study investigates the effects of fabric structure on the forming behaviour of glass fabric reinforced polypropylene composites during the sheet forming of a doubly curved shape. Stamp forming, a novel thermoforming technique, is mostly used for hemispherical forming of thermoplastic composites. The study also investigates the influence of process parameters such as die temperature, blank temperature, and blank holder force on sheet formability. Forming ratio, thickness distribution, material draw-in, and punch force were used for the evaluation of the formability of composites. Conventional and novel plain weave glass fabric reinforced polypropylene composite laminates were fabricated using the film stacking technique. Thermo-stamp forming experiments were conducted on the basis of the Taguchi’s L9 orthogonal array. Experimental results revealed better forming characteristics by the novel glass fabric reinforced composite than for the conventional glass fabric reinforced composite. Production of defect-free components under high die temperature, low blank holder force, and medium blank temperature process condition was observed.

Advanced induction heating system for hot stamping

The development of a rapid uniform heating process for blanks is needed to perform hot stamping processes. To solve the problem of inhomogeneous temperature distribution in conventional induction heating systems, a heating block has been added to an induction system and investigated to determine if it can achieve rapid and uniform blank heating. To characterize the effects of incorporating the heating block, the temperature distributions of various coil geometry have been experimentally analyzed. The results show that the proposed induction heating system makes it possible to achieve rapid and uniform blank heating, which is used to conduct stable hot stamping. The mechanical properties of a hot stamped part confirm that the proposed heating method is a feasible alternative method for hot stamping products, and that it yields excellent results. This system for the reduction of heating time requires less installation space compared to a conventional electric furnace and achieves uniform heating, which results in improved product quality and reduced manufacturing costs.

Numerical analysis of the deep drawing process including the history of stress and strain

This paper discusses the results of a numerical study of circular cup drawing of steel sheets using finite element method. The drawing process is considered as a geometrical and physical nonlinear problem with unknown boundary conditions in the contact area of the system, such as the tool and the workpiece. The updated Lagrangian description is used to charac- terize these nonlinear phenomena on a typical incremental step time. Numerical results are obtained using an explicit method in Ansys/Ls-Dyna program. The constitutive Cowper- -Symonds material model with linear hardening strain to predict material plasticity is used. The results of implementation of stresses and strains from a blanking operation flat disc of a sheet of metal for deep-drawing process are presented. After the blanking process simula- tion, an implicit springback analysis is performed. Then a numerical analysis of cup forming from this flat disc plate was carried out. The analysis results are compared with one another through reading of the sheet thickness in several characteristic points and the overall height of the product.

Thermomechanical simulations of blanking process operated over a wide range of punch velocities

A numerical model based on the finite element method has been developed to simulate the blanking process. Thanks to this model we analyse the influence of punch velocities during blanking on the quality of the sheared edge and the characteristic parameters governing the process (maximum punch force and displacement, temperature increase). In this model, inertia, viscous and thermal effects are properly considered by means of a unified thermomechanical framework. A full remeshing approach is adopted to overcome the high distortion of elements due to large deformations, prior to fracture. The material strain-rate sensitivity is introduced by means of an extension of elasto-viscoplastic constitutive equations for the large strain regime. The inertial effects are considered thanks to an implicit time integration scheme. Crack propagation during the process is tracked using the element deletion method driven by an uncoupled damage criterion. Finally, the coupled thermomechanical problem is solved by an isothermal staggered scheme. Experimental and numerical results are compared for the entire range of punch velocities under consideration. Good agreement between both results has been found.

Finite Element Analysis of Blanking Operation of Magnesium Alloy (AZ31) Sheet Using Ductile Fracture Criteria and Its Experimental Verification at Various Temperatures

This study focuses on modeling and analyzing sheet blanking process of Magnesium alloy sheet (AZ31) using finite element method at various temperatures. The computational analysis is then compared with the results obtained through the experimental setup. In the finite element model fracture initiation and the shape of the blanked edge are influenced by the value of critical damage criteria (C). The value of critical criteria is determined and compared using the ductile fracture criteria proposed by various researchers by varying various process parameters and temperature. The effect of temperature and process parameters on the geometry of the blanked edge including burr, fracture zone, shear surface and rollover has been investigated. Moreover, numerical predictions were compared with the experimental results.

Finite element simulation of effect of material thickness and die clearance on fine blanking process

Bu calismada, sac metal kesme yontemlerinden biri olan hassas kesme islemine kalip boslugunun ve malzeme kalinliginin etkisi sonlu elemanlar yontemi(SEY) kullanilarak arastirilmistir. Analizler, 0,01, 0,025, 0,05 ve 0,1 mm kalip bosluklarinda, 1 ve 2 mm kalinliginda malzeme kullanilarak gerceklestirilmistir. Belirlenen parametrelerin kavislenme genisligi ve yuksekligine, kirilma bolgesi yuksekligi ve acisina, zimba kuvvetine, kesme bolgesindeki gerilme ve birim sekil degisimine etkisi arastirilmistir. Analiz sonucundan, kalip boslugunun artmasi ile kavislenme degerinin ve kirilma bolgesi yuksekligi ile acisinin arttigi, gerilme dagiliminin ise azaldigi belirlenmistir. Ayrica malzeme kalinliginin ise kavislenme degerini etkileyen onemli bir faktor oldugu gorulmustur.

Modelling of the blanking process of high-carbon steel using Lemaitre damage model

This paper presents a methodology to model a blanking process using a continuum mechanical damage model. A variant of the Lemaitre model, in which the quasi-unilateral conditions are taken into consideration to modify the damage behavior under compressive stress states, is selected as material model. S45C high-carbon steel is analyzed experimentally. To characterize the damage behavior of the material, notched round bar tensile tests with three different notch radii (6 mm, 10 mm, and 20 mm) using image analysis are performed. Using digital image processing, the strain at the deformation zone can be computed for the load–strain curves. Those curves are used as an objective function to determine the parameters of the Lemaitre damage model. The experimental results are compared with the results of the FE analysis of the tensile test. The identified model parameters are used in numerical investigations of axisymmetric blanking. The effect of the model's extension to quasi-unilateral damage evolution is discussed. The crack progress in high-carbon steel sheet during blanking and the final sheared part morphology are predicted and compared with the experimental results. Sheared surface and burr height obtained by the analysis coincide with the results of the blanking experiment.

Numerical Simulation of Cold Rolled Steel Sheet Metal during Blanking Process

Numerical Simulation of Cold Rolled Steel Sheet Metal during Blanking Process