Influence of the inaccuracy of thermal contact conductance coefficient on the weighted-mean temperature calculated for a forged blank

Polozine, Alexandre; Schaeffer, Lírio

doi:10.1016/j.jmatprotec.2007.05.020

Cited by 8 publications

(3 citation statements)

References 9 publications

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“…In order to ensure specific cooling rates during quenching numerically, it is necessary to characterise the thermal conditions of this process part. Since the major part of the heat transfer takes place shortly after the initial contact between the tool and the sheet metal [4], the heat transfer coefficient (HTC) is of particular importance to avoid prediction errors during process simulations [5]. Subsequently, a practical method for characterising the heat transfer coefficient (HTC) is presented.…”

Section: Introductionmentioning

confidence: 99%

Practical process characterisation for hot-stamping regarding the heat transfer coefficient using a numerical and experimental coupled method

Behrens¹,

Brunotte²,

Wester³

et al. 2020

METAL 2020 Conference Proeedings

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Due to the efficient combination of a forming step with a consecutive heat treatment, hot-stamping has become an established technology for the production of high strength steel parts in the automotive industry. In the beginning, sheets are heated above austenitisation temperature and held in order to obtain a fully austenised microstructure, then formed and instantly quenched in the forming tool. To achieve the desired increase in tensile strength for the widely used manganese boron steel 22MnB5, cooling rates of at least 27 K/s are necessary. This requirement sets a high demand on the numerical process simulation in order to being able to predict the occurrence of component or process errors with a high degree of certainty. To achieve this, the exact knowledge of the local heat transfer coefficient is necessary, which dominantly determines the temperature distribution within the work piece and the die. Since there is none standardised test method for the determination of heat transfer coefficients exists, a practical test method is presented in this study. In addition to the use of a divisible temperature-measuring stamp, the method is based on a close coupling of practical experiment and iterative numerical simulation. With the method and tools shown in the scope of this paper, the heat transfer coefficient could be successfully determined as a function of contact pressure and tool start temperature, taking the process route of hot-stamping into account. Results are compared with literature knowledgeorder to demonstrate the performance of the determination method.

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Section: Introductionmentioning

confidence: 99%

Practical process characterisation for hot-stamping regarding the heat transfer coefficient using a numerical and experimental coupled method

Behrens¹,

Brunotte²,

Wester³

et al. 2020

METAL 2020 Conference Proeedings

View full text Add to dashboard Cite

show abstract

“…У роботі [14] показано, що при застосовуванні бойків опуклої форми досягається значне накопичення пластичних деформацій високого рівня осьової зони заготовки. Бойок опуклої форми також запропонований у роботі [15]. У запропонованих роботах не досліджено впливу профілювання заготовки на розподіл деформацій у процесі осадження.…”

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Study New Method of Masive Ingots Upsetting of Workpieces With Conical Faces

Марков¹,

Khvashchynskyi²,

Musorin³

et al. 2022

TST

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Quantity of massive parts produced from an ingot is increasing today. It is caused by increasing in the capacity of a massive equipment. However, the quality of produced forging parts does not corresponds to customer`s requirements. Poor quality of the produced forging parts is caused by low quality of forging ingots.Defects of ultrasonic test after forging of the massive forging parts equal to 10%. The defects after ultrasonic test are caused by upsetting operation of the ingots with no equal internal structure. As a result, this structure is processed unevenly and insufficiently. Increasing of the ingot internal defects occurs during upsetting operation of billets by flat deformation tools.The purpose of this work is establishing the rational geometry of billets with conical faces which guarantee the uniform distribution of the deformations, and significant hydrostatic stresses.Analysis of the strain and stress states allows find that in the billet at the upsetting operation occurs the state with non-uniform compress stresses. Raising the degree of the compressive stresses in the internal and external parts can be obtained after upsetting of the shot billets (H/D<3.0). Raising the deformation degree from till 0.45 provides to letdown factor of the stress state η from –1,0 to 0. The upsetting till 0.7 raises this factor to +1.5. It was established that decreasing diameter of the conical faces leads to reduction the factor η. This factor has a more significant influence for welding of the internal cavities in the–1.5...–0.6 at upsetting operation with the comparative diameter of the conical faces of the 0.5.Upsetting of the toll billets leads to the reduction degree of logarithmicstrains and reduction equability of the local-ization. Obtained geometrical parameters of the billets with conical faces are able to be introduced in producing of the massive forged parts.

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“…Нині розроблено безліч варіантів кування, що відрізняються послідовністю операцій, ступенем деформації, застосуванням різного виду інструменту й різних режимів термічної обробки [12][13][14][15][16].…”

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Скінчено-Елементне Дослідження Напружено-Деформованого Стану Процесу Профілювання Циліндричних Заготовок

Марков

Musorin

Khvashchynskyi

et al. 2021

TST

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Аналіз наукових публікацій дозволив виявити, що проблема підвищення якості великих кованок відповідального призначення нині не вирішена повністю. Наявні технологічні процеси кування великих заготовок полягають у деформуванні злитків плоскими або комбінованими бойками. Такі способи деформування не завжди гарантують проробку литої структури заготовки. Моделювання дало змогу встановити, що профілювання випуклими радіусними бойками призводить до зміни розподілу деформацій та напружень у тілі заготовки. У результаті підвищується рівномірність розподілу деформацій, а також увігнуті грані підвищують рівень стискаючих напружень у центральних та периферійних шарах заготовки.

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Influence of the inaccuracy of thermal contact conductance coefficient on the weighted-mean temperature calculated for a forged blank

Cited by 8 publications

References 9 publications

Practical process characterisation for hot-stamping regarding the heat transfer coefficient using a numerical and experimental coupled method

Practical process characterisation for hot-stamping regarding the heat transfer coefficient using a numerical and experimental coupled method

Study New Method of Masive Ingots Upsetting of Workpieces With Conical Faces

Скінчено-Елементне Дослідження Напружено-Деформованого Стану Процесу Профілювання Циліндричних Заготовок

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