Method for optimizing the cooling design of hot stamping tools

Steinbeiss, Heinz; So, Hyunwoo; Michelitsch, Thomas; Hoffmann, Hartmut

doi:10.1007/s11740-007-0010-3

Cited by 67 publications

(27 citation statements)

References 3 publications

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“…All experiments described in this work are performed on a 5-axis (three linear and two rotatory) conventional milling center rebuilt as a laser processing machine, named Kondia Aktinos 500 (Kondia, Elgoibar, Spain), whose work piece size capacity is 700 × 360 × 380 mm 3 . In addition, a high power Yb:YAG fiber laser source, Rofin FL010 (ROFIN-SINAR Laser GmbH, Bergkirchen, Germany), is used, with a maximum power output of 1 kW, emitting wavelength of 1070 nm and pulse frequency range up to 5 kHz.…”

Section: Methodsmentioning

confidence: 99%

“…This is due to the fact that nearly all mass-produced parts are manufactured employing processes that include dies and molds, directly affecting not only the efficiency of the process, but also the quality of the product [2]. Moreover, increasing demand in the automotive industry for high strength and lightweight components has led to the promotion and development of hot stamping (also known as Press Hardening) processes [3]. Through this technique, a boron steel blank is heated until austenization at temperatures between 900 • C and 950 • C inside a furnace and then transferred to an internally cooled die set, where it is simultaneously stamped and quenched.…”

Section: Introductionmentioning

confidence: 99%

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Case Study to Illustrate the Potential of Conformal Cooling Channels for Hot Stamping Dies Manufactured Using Hybrid Process of Laser Metal Deposition (LMD) and Milling

Cortina

Arrizubieta

Calleja

et al. 2018

Metals

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Hot stamping dies include cooling channels to treat the formed sheet. The optimum cooling channels of dies and molds should adapt to the shape and surface of the dies, so that a homogeneous temperature distribution and cooling are guaranteed. Nevertheless, cooling ducts are conventionally manufactured by deep drilling, attaining straight channels unable to follow the geometry of the tool. Laser Metal Deposition (LMD) is an additive manufacturing technique capable of fabricating nearly free-form integrated cooling channels and therefore shape the so-called conformal cooling. The present work investigates the design and manufacturing of conformal cooling ducts, which are additively built up on hot work steel and then milled in order to attain the final part. Their mechanical performance and heat transfer capability has been evaluated, both experimentally and by means of thermal simulation. Finally, conformal cooling conduits are evaluated and compared to traditional straight channels. The results show that LMD is a proper technology for the generation of cooling ducts, opening the possibility to produce new geometries on dies and molds and, therefore, new products.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Case Study to Illustrate the Potential of Conformal Cooling Channels for Hot Stamping Dies Manufactured Using Hybrid Process of Laser Metal Deposition (LMD) and Milling

Cortina

Arrizubieta

Calleja

et al. 2018

Metals

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show abstract

“…This excellent performance of the final ANN model with an RMS error of just 7.7% for phase fraction prediction over the test dataset establishes that the final ANN model has indeed robustly learned the functional relationship between the thermal history, deformation amount and deformation temperature and the final resulting phase distribution in the boron steel. Thermal history, deformation amount and deformation temperature are the factors which have the greatest influence on the final phase distribution during tailored hot stamping and hence were used for development of the current ANN model [8,10,12,15,35,36,48,49]. There are other process parameters such as strain rate, austenitization temperature and austenitization time which also have limited influence on the final phase distribution during tailored hot stamping.…”

Section: Model Validation and Performance Analysismentioning

confidence: 99%

Artificial Neural Network (ANN) based microstructural prediction model for 22MnB5 boron steel during tailored hot stamping

Chokshi

Dashwood

Hughes

2017

Computers & Structures

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Abstract:Because of demand for lower emissions and better crashworthiness, the use of hot stamped 22MnB5 boron steel has greatly increased in manufacturing of automobile components. However, for many applications it is required that only certain regions in hot stamped parts are fully hardened whereas other regions need be more ductile. The innovative process of tailored hot stamping does this by controlling the localized microstructures through tailored cooling rates by dividing the tooling into heated and cooled zones. A barrier to optimal application of this technique is the lack of reliable phase distribution prediction model for the process.We present a novel Artificial Neural Network (ANN) based phase distribution prediction model for tailored hot stamping. The model was developed and validated using data generated from extensive thermo-mechanical physical simulation experiments and instrumented nanoindentation based phase quantification method. Advanced statistical techniques were used for preventing overfitting, for making the optimal use of available experimental data and for quantification of prediction uncertainty. The final predictions made by the ANN model during its independent validation have shown good agreement with the experimentally generated data and have a RMS prediction error of just 7.7%, which is a significant improvement over the existing models.

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“…With higher cooling rates the resulting structure becomes fully martensitic, allowing higher hardness values. Steinbeiss et al [7] showed that the in hot stamping process heat transmission occurs through three factors: heat transfer between the component and the tool, heat conduction through the tool and the transfer of heat between the tool and the cooler. According to Naganathan [8] there are three ways to ensure an efficient heat transfer: use of materials with high thermal conductivity in the dies manufacturing, avoid barriers to the heat driving and improve the cooling system.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Method to Simulate the Hot Stamping Process

Olah¹,

Verran²,

Dutra³

2017

Tecnol. Metal. Mater. Min.

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In this study a new experimental method using low closing pressure and a flat aluminum die was developed in order to investigate the hot stamping process of a 22MnB5 steel grade. Initially, an experimental set up was developed and validated. Next, experiments were carried out to evaluate the behavior of this steel when subjected to quenching, using this experimental set up and different cooling conditions such as water, oil and air. Results were assessed by cooling curves, as well as by mechanical tests and metallographic analyzes. Cooling rates close to 110 o C/s, hardness up to 480HV and ultimate tensile strength up to 1600 MPa were achieved, which are considered acceptable values for this steel in normal conditions of hot stamping. Keywords: Hot stamping; 22MnB5 steel; Quenching; Cooling rate. UM MÉTODO EXPERIMENTAL PARA SIMULAR O PROCESSO DE ESTAMPAGEM A QUENTE ResumoNesta pesquisa foi desenvolvido um novo método experimental, utilizando baixa pressão de fechamento e uma matriz plana de alumínio, com o objetivo de investigar o processo de estampagem a quente do aço 22MnB5. Inicialmente um aparato experimental foi desenvolvido e validado. A seguir foram realizados experimentos com o objetivo de avaliar o comportamento deste aço quando submetido a diferentes meios de têmpera, usando este método e diferentes condições de resfriamento, tais como água, óleo e ar. Os resultados foram avaliados usando curvas de resfriamento, bem como ensaios mecânicos e análises metalográficas. Foram obtidas taxas de resfriamento próximas de 100 0 C/s, durezas acima de 480HV e limite de resistência acima de 1600 MPa, valores que são considerados aceitáveis para este aço em condições normais de estampagem a quente. Palavras-chave: Estampagem a quente; Aço 22MnB5; Têmpera; Taxa de resfriamento. INTRODUCTIONIn recent years the hot stamping process has been widely studied, generating significant technological advancement and allowing its use in the production of several components with excellent performance due to the combination of high mechanical properties with high dimensional accuracies.An important aspect in the hot stamping process is that sheet conformation occurs at elevated temperatures, where the mechanical strength of the material is significantly reduced. Thus, the load required to deform the sheet is very low, opening up the possibility of the use of less robust and cheaper equipment, which results in lower operating costs and investment. The stamping tools would also be less stiff and cheaper. The use of low stress for deformation also requires the evaluation of the thermal behavior because the material is hot formed and simultaneously quenched to room temperature, in order to obtain a component with good dimensional accuracy and high mechanical resistance [1]. The conditions involving contact between the tool and the blank and the closing pressure have a significant influence on the heat extraction coefficient, on the cooling rate and consequently, on the final properties of the component. In hot stamping the co...

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Method for optimizing the cooling design of hot stamping tools

Cited by 67 publications

References 3 publications

Case Study to Illustrate the Potential of Conformal Cooling Channels for Hot Stamping Dies Manufactured Using Hybrid Process of Laser Metal Deposition (LMD) and Milling

Case Study to Illustrate the Potential of Conformal Cooling Channels for Hot Stamping Dies Manufactured Using Hybrid Process of Laser Metal Deposition (LMD) and Milling

Artificial Neural Network (ANN) based microstructural prediction model for 22MnB5 boron steel during tailored hot stamping

An Experimental Method to Simulate the Hot Stamping Process

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