Calculation of Isothermal Flow Stress by Combination of FEM and Simple Compression Test

Kada, Osamu; Miki, Tsuneharu; Toda, Masahiro; Osakada, Kozo

doi:10.1016/s0007-8506(07)62814-5

Cited by 12 publications

(5 citation statements)

References 3 publications

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“…Deformation analysis was coupled with thermal analysis to perform axisymmetric analysis. The flow stress obtained in the compression test was corrected for the effects of the friction force and temperature changes by using the method proposed by Kada et al [3]. The resultant isothermal flow stress shown in Fig.…”

Section: Analysis Methodsmentioning

confidence: 99%

“…Finite element method (FEM) analysis of hot forging is often conducted by coupling deformation analysis with thermal analysis to consider the temperature change of the workpiece and the tool. Many hot forging studies are reported on the temperature dependence of flow stress of the workpiece [2,3,4] and the heat transfer coefficient between the workpiece and the tool [5,6]. In cold forging, the temperature difference between the workpiece and the tool is smaller than that in hot forging and the deformation analysis is rarely coupled with the thermal analysis.…”

Section: Introductionmentioning

confidence: 99%

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Heat Transfer Coefficient of Zinc Phosphate Coating with Metal Soap during Cold Backward Extrusion

Kada

Wang

2022

DDF

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In cold forging, the temperature difference between the workpiece and the tool is small and thus deformation analysis is rarely coupled with thermal analysis. However, the friction coefficient of zinc phosphate coating with metal soap has a large temperature dependence. Consideration of the effects of workpiece and tool temperature change on the friction coefficient is thus expected to improve the analytical accuracy of cold forging. Thermally coupled cold forging analysis requires thermal conductivity, specific heat, heat transfer coefficient between the workpiece and the tool, in addition to the temperature dependence of flow stress and friction coefficient. The heat transfer coefficient between workpieces coated with zinc phosphate with metal soap and tools is investigated in this paper. Cold backward extrusion was performed with a 50% reduction of area, and the temperature history in the punch was measured with a thermocouple. The forging speed was 1, 3, and 10 spm. FEM analysis was performed to simulate the experiment by considering the temperature dependence of flow stress and friction coefficient. The heat transfer coefficient was estimated at 20 kW/(m2•°C) by comparing the experimental result and calibration curves.

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Section: Analysis Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Heat Transfer Coefficient of Zinc Phosphate Coating with Metal Soap during Cold Backward Extrusion

Kada

Wang

2022

DDF

Self Cite

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“…Others developed correction terms to account for the inhomogeneous distribution of strain during compression tests with sticking friction using data from laboratory tests for inverse calibration …”

Section: State Of the Artmentioning

confidence: 99%

The Precise Prediction of Rolling Forces in Heavy Plate Rolling Based on Inverse Modeling Techniques

Lohmar

Bambach�

Kiefer

et al. 2014

steel research int.

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The industry scale production of heavy steel plates is performed in plate mills using reversing mill stands and roll schedules with 30 or more passes. Ideal pass scheduling is dependent on a precise prediction of the roll force in each pass. To obtain these forces process models based on the slab theory together with semi-empirical material models are most frequently used. The material parameters necessary to calibrate the models for a specific steel grade are conventionally generated on a lab scale via time-consuming and expensive compression tests. This paper will introduce a concept that allows obtaining the material model parameters directly from the rolling process on an industrial scale by an inverse modeling technique. In this context, the parameters of the material model are adjusted according to the current offset between measured and calculated roll forces. The adjustment is enabled by a non-linear optimization that aims for a minimum deviation between measured and calculated roll forces for each pass. Several results gathered in an optimization run with industrial data of about 2650 produced plates are presented. The concurrence between measurement and prediction using the optimal parameters is in detail shown for three different schedules. In summary, inverse modeling seems to allow utilizing data of past rolling processes to determine material model parameters with high accuracy.

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“…Hot forging of cast magnesium alloys has mass production advantages over hot forging of extruded magnesium alloys, but less research on hot forging of cast magnesium materials has been performed. Kada et al [15] reported a new method of predicting isothermal deformation resistance of magnesium alloys during hot forging, which includes effects of friction, heat of deformation, and heat transportation in hot forging. The ring-compression test is a popular method that can estimate friction between tools and materials as well as deformation resistance during forging.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Friction Properties of Magnesium Alloy during Hot Forging by Ring Compression Test

Hirawatari

Watari

Nishida

et al. 2017

MSF

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This paper deals with friction properties and deformation resistance during hot forming of Mg-Al-Ca-Mn series magnesium alloys. Friction coefficients between dies and magnesium alloys were obtained by ring compression tests that used graphite, PTFE, and an oil lubricant in a hot-forging process. Hot forging was performed under various conditions to clarify the effects of types of lubricants and slide motion of the press machines on friction properties. Two types of slide motion, a constant velocity motion and a pulse motion were selected in the ring-compression test. It was found that graphite with an oil lubricant effectively eliminated die sticking in hot forming of magnesium alloys. The isothermal deformation resistances were derived using friction coefficients obtained by ring-compression tests as well as finite-element simulations. The predicted stress strain curves with temperature were examined with the stress-strain relationship obtained in experiments using a servo press and demonstrated the effectiveness of the proposed method.

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Calculation of Isothermal Flow Stress by Combination of FEM and Simple Compression Test

Cited by 12 publications

References 3 publications

Heat Transfer Coefficient of Zinc Phosphate Coating with Metal Soap during Cold Backward Extrusion

Heat Transfer Coefficient of Zinc Phosphate Coating with Metal Soap during Cold Backward Extrusion

The Precise Prediction of Rolling Forces in Heavy Plate Rolling Based on Inverse Modeling Techniques

Evaluation of Friction Properties of Magnesium Alloy during Hot Forging by Ring Compression Test

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