International Deep Drawing Research Group (IDDRG) annual conference was held in Lorient, France from 6 to 10 June 2022. The conference was co-organised by Université de Bretagne Sud and ArcelorMittal ...France and was chaired by Prof Sandrine Thuillier. This was a fantastic opportunity to gather the IDDRG community after the pandemics, though some colleagues were still not able to travel due to COVID-19.List of Conference topics, Patronage, Committees, Acknowledgements, Sponsors, Editor are available in the pdf
Abstract In this study, appropriate conditions for forming complex shapes with multiple steps, such as automotive side door inner in a two-stage deep drawing process are investigated, and the ...effectiveness of the process is verified in a test. In this forming process, the inner area of the part is formed in the first stage and the outer area is formed in the second stage. And in the second stage, a forming pad is used to reduce strain in the inner area that is formed in the first stage. The results of the forming test showed that it is necessary to control the blank holding force (BHF) and the pad force (PF) in the second stage to avoid blank ruptures in all areas. Therefore, the concept of the BHF and PF for blank rupture risk at each site was studied using the finite element method (FEM). An appropriate range of BHF and PF was estimated from the results of FEM and the validity of the estimated values was confirmed in an actual test. In addition, it was confirmed that a two-stage deep drawing process using the above appropriate values can form a more severe shape than a one-stage deep drawing process.
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•A novel deep drawing process at cryogenic temperatures is developed to overcome the low drawability of Al-Cu-Mn alloy sheets at room temperature.•A special deep drawing system is ...designed for investigating the cryogenic deep drawability of the Al-Cu-Mn alloy sheet.•The superior deep drawability of the Al-Cu-Mn alloy sheet can be obtained as the temperature decreases to −160 °C. The LDR value at RT is 1.80, while the −160 °C is increased to 2.08, which has increased by 15.6%. The average cup height at −160 °C is 50.2% higher than that at RT.•The deformation mechanism for the enhanced formability and strength is illuminated by the microstructure observations on fracture morphologies and dislocation evolutions at cryogenic temperatures.
To overcome the low drawability of aluminum alloy sheets at room temperature (RT), a novel deep drawing process at cryogenic temperatures is proposed. Uniaxial tensile tests were carried out at RT, −130 °C, −150 °C, −160 °C and −196 °C, respectively, and the desired temperature of cryogenic deep drawing was obtained. Based on a newly-designed cryogenic deep drawing system, deep drawing experiments of an Al-Cu-Mn alloy sheet were conducted at different cryogenic temperatures. The material flow, drawing ratio, drawing load, thickness distribution and Vickers microhardness of the drawn cups at both RT and cryogenic temperatures were discussed in detail. It was found that the deep drawability was significantly enhanced as the temperature decreased to −160 °C. The limiting drawing ratio at RT was 1.80, while that at −160 °C increased by 15.6% to 2.08. Similarly, the average cup height (89.5 mm) at −160 °C was found to be 50.2% higher than that at RT (59.6 mm). The cryogenically drawn cups exhibited slight localized thinning, uniform thickness distribution, and a large drawing height and drawing load. In addition, the enhancement of the deep drawability was illuminated via microstructural observations of the fracture morphology and dislocation evolution at cryogenic temperatures.
Among the sheet metal forming processes, hydrodynamics deep drawing and hydromechanical deep drawing process are two main types of the deep drawing process that can fabricate complicated parts. In ...the hydroforming process, the blank is formed to the desired shape by applying a considerably high hydraulic pressure. In this article, the selection of the process parameters will be investigated during the manufacturing of a pure copper sharp conical part by finite element analysis and experimental tests. Two finite element models are developed for hydrodynamics deep drawing and hydromechanical deep drawing processes. After verification of the FE model by experimental results, the effect of process parameters includes the applied pressure, friction coefficient, die radius and blank holder force on thinning of the blank are investigated. The thinning ratio of blank is calculated in different zones of the conical part under different working conditions determined according to the Taguchi design of experiment methods. Signal to noise ratio analysis has been carried out and the influence of process parameters on the thinning ratio is determined at different zones of the conical part. The results show that the friction coefficient has an important role in the thinning of the conical nose while at the lateral surface of the cone, the die radius is the most effective parameter on the thinning ratio. The results show that by implementing statistical tools (Taguchi method and signal to noise ratio analysis), it is possible to select the proper process parameters conditions and fabricate defect-free parts. In addition, a non-linear regression equation is developed for prediction of thinning ratio in the hydrodynamics deep drawing and hydromechanical deep drawing processes.
To meet the increasing demand of multifunctional applications of microcomponents, metal composites have been gradually noted in micromanufacturing. In this paper, the formability of aluminium ...(Al)-copper (Cu) composite foils in micro deep drawing (MDD) was studied, and the mechanism involved was discussed. A two-layered Al-Cu composite with the thickness of 235 µm was selected and first rolled to 50 µm, and then annealed at 200, 300, 400 and 500 °C for 5 min prior to the MDD experiments. The results show that Al-Cu composite foil possesses the best combination of strength and ductility after annealing at 400 °C. With the increase in annealing temperature, the grains of both Al and Cu layers are refined, and in the meantime, the thickness of intermetallic layer also increases. The results from MDD tests indicate that the existence of intermetallic layer has a greater influence on the formability of the composite foil compared to the finer distribution of grains. On the basis of the obtained results, the optimised heat treatment method with the annealing temperature of 300 °C for 1 h was proposed, which was then proved to significantly improve the performance of the Al-Cu composite foil in MDD.
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This article details the ESAFORM Benchmark 2021. The deep drawing cup of a 1 mm thick, AA 6016-T4 sheet with a strong cube texture was simulated by 11 teams relying on phenomenological or crystal ...plasticity approaches, using commercial or self-developed Finite Element (FE) codes, with solid, continuum or classical shell elements and different contact models. The material characterization (tensile tests, biaxial tensile tests, monotonic and reverse shear tests, EBSD measurements) and the cup forming steps were performed with care (redundancy of measurements). The Benchmark organizers identified some constitutive laws but each team could perform its own identification. The methodology to reach material data is systematically described as well as the final data set. The ability of the constitutive law and of the FE model to predict Lankford and yield stress in different directions is verified. Then, the simulation results such as the earing (number and average height and amplitude), the punch force evolution and thickness in the cup wall are evaluated and analysed. The CPU time, the manpower for each step as well as the required tests versus the final prediction accuracy of more than 20 FE simulations are commented. The article aims to guide students and engineers in their choice of a constitutive law (yield locus, hardening law or plasticity approach) and data set used in the identification, without neglecting the other FE features, such as software, explicit or implicit strategy, element type and contact model.
In this paper, the effect of sheet deformation on the change of the surface roughness parameters and friction coefficient value is considered. For this purpose, deep drawing quality (DDQ) steel ...samples were straightened using a uniaxial tensile test to different true strain values. The correlation between the surface roughness parameters and frictional conditions of the tested sheets was investigated in the strip drawing test. It was found that the friction coefficient determined for all pre-strained samples decreases with increasing nominal pressure of rolls under both dry and lubricated conditions. An increase in the plastic deformation of sheets under the uniaxial tensile stress state causes a nearly linear increase in the value of basic amplitude parameters of surface roughness.
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•The effect of sheet deformation on the change in surface roughness is considered.•The strip drawing test is used to study the frictional resistance of steel sheets.•The friction coefficient decreases with increasing nominal pressure.•The plastic deformation of the sheets causes an increase of the profile height.
