Direct contact heating for hot forming die quenching

Rasera, Joshua Nicholas; Daun, Kyle J.; Shi, Cangji; D’Souza, Mary

doi:10.1016/j.applthermaleng.2015.12.142

Cited by 23 publications

(6 citation statements)

References 10 publications

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“…Correspondingly, an increase of the workpiece temperature occurs. The measured temperature curve is characterized by an initial fast rise that decreases more and more when it approximates the temperature of the contact plates, which is in good agreement with [16]. After reaching the target temperature of 475°C, the test is completed, the specimen is removed from the tool and quenched in water, and the contact plate temperature is re-adjusted for next test of the test series.…”

Section: Experimental Setup and Process Descriptionsupporting

confidence: 74%

“…Direct contact heating is a relatively new approach (suggested in [14]) with high potential to overcome these limitations. In this technology, the contact plates (typically made of metal or ceramics) that are heated by a heat source (e. g. induction coils [14], gas burners [15], cartridge heaters [16]) serve as energy storage and transfer the heat to the workpiece via thermal conduction. Compared to furnace heating, contact heating excels due to extremely high heating rates, which significantly reduces heating time [17].…”

Section: Introductionmentioning

confidence: 99%

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Influence of surface pressure and tool materials on contact heating of aluminum

Trân

2023

Materials Research Proceedings

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Abstract. The implementation of lightweight design concepts can significantly benefit from using highly efficient heating technologies such as contact heating in thermo-mechanical processing of sheet metal components. The investigation of the influence of surface pressure and tool material on the heating time and the heating rate during contact heating is the subject of this publication. A specially manufactured contact heating tool with comprehensive temperature and force measurement was used for studying the effects of different contact plate materials (CuZn39Pb3 and CuCr1Zr), surface pressures (3 MPa - 15 MPa) and variable plate thicknesses (1.0 mm - 5.2 mm) during heating of the aluminum alloy EN AW-7075 up to the solution heat treatment temperature of 475 °C. It was observed that heating time is lower for thinner workpieces. Furthermore, heating times decrease and heating rates increase significantly with increasing surface pressure for a pressure range of 3 MPa - 9 MPa. A further increase in surface pressure is not recommended, because the benefit in terms of further reduction of the heating time is marginal and the strength of the contact plate materials at elevated temperatures is limited. Contact heating using copper plates is significantly faster compared to brass plates and the conventionally used steel plates. Brass plates, however, benefit more from an increase in surface pressure. Both investigated materials allow faster heating than conventional steel plates due to their higher thermal conductivity. Depending on the specific process parameters the heating process can be accelerated to less than one second. Thus, contact heating can be realized within the press cycle.

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Section: Experimental Setup and Process Descriptionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Influence of surface pressure and tool materials on contact heating of aluminum

Trân

2023

Materials Research Proceedings

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“…However, the reverse transformation is complicated due to the inhomogeneously distributed carbon and alloying elements, which can be equilibrated at the interface for interstitial alloying elements [10], or negligible-partition local equilibrium [11]. In particular, more and more alternative heating technologies are being used in the hot stamping process, such as induction heating [12], conduction heating [13] and direct contact heating [14], in order to improve production efficiency by shortening the process cycle time. Li et al studied the effects of thermal conditions on austenite formation in a 22MnB5 manganese-boron steel with an initial microstructure composed of a mixture of approximately 78% proeutectoid ferrite and 22% pearlite [15].…”

Section: Introductionmentioning

confidence: 99%

Microstructure Characterization of Reversed Transformation in Cryogenically Rolled 22MnB5

et al. 2020

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Hot stamping is a well-known process to produce structural automotive parts with an excellent strength-to-weight ratio. However, this process is more expensive due to the lower energy efficiency and operating cost of the traditional roller-hearth furnace. Additionally, lower ductility and toughness are commonly recognized as the main disadvantages of the current hot stamped ultra-high-strength parts. Refinement of austenite grains could be a profitable way to improve the strength of hot stamped parts. In this work, the evolution of reversed transformation in asymmetrically cryogenically rolled samples was studied in order to control the austenite. Thermomechanical simulation and heat treatment in the salt bath were used to investigate the reversed transformation process, and the typical microstructures were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Compared with symmetric prerolling, ferrite recrystallization could be remarkably inhibited by asymmetric rolling at the liquid nitrogen temperature (LNT) during the reheating process. Additionally, the nucleation of the austenite inner grains can also be promoted and the dynamics of the reversed transformation accelerated by asymmetric prerolling. Such phenomena might be very useful to refine the parent austenite grains before press hardening and enhance the new hot stamping strategy by partial fast reheating.

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“…Austenitizing the steel to be hardened is a must in the manufacturing process, which turns the austenitizing furnace into a key piece of equipment. Despite that several heating alternatives have been studied, such as resistance heating [4], induction heating [5,6], or direct contact heating [7], radiant heating is the leading industrial solution for mass production. The amount of published works related to dedicated furnaces for press hardening is, though, scarce and mostly focused on roller hearth furnaces [8].…”

Section: Introductionmentioning

confidence: 99%

Failure-Analysis Based Redesign of Furnace Conveyor System Components: A Case Study

González-Ciordia

Fernández

Artola

et al. 2019

Metals

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Any manufacturing equipment designed from scratch requires a detailed follow-up of the performance for the first units placed in service during the production ramp-up, so that lessons learned are immediately implemented in next deliveries and running equipment is accordingly updated. Component failure analysis is one of the most valuable sources of improvement among these lessons. In this context, a failure-assessment based design revision of the conveying system of a newly developed press hardening furnace is presented. The proposed method starts with a forensic metallurgical analysis of the failed components, followed by an investigation of the working conditions to ensure they match the forensic observations. The results of this approach evidenced an initially unforeseen thermo-mechanical damage produced by a combination of thermal distortions, material ageing, and mechanical fatigue. Once the cause–effect relationship for the failure is backed up by evidence, an improved design is proposed. As a conclusion, a new standard design for the furnace entrance set of rollers in hot stamping lines was established for roller hearth furnaces. The solution can be extended to similar applications, ensuring the same issues will not arise thanks to the lessons learned.

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Direct contact heating for hot forming die quenching

Cited by 23 publications

References 10 publications

Influence of surface pressure and tool materials on contact heating of aluminum

Influence of surface pressure and tool materials on contact heating of aluminum

Microstructure Characterization of Reversed Transformation in Cryogenically Rolled 22MnB5

Failure-Analysis Based Redesign of Furnace Conveyor System Components: A Case Study

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