Conductive Heating during Press Hardening by Hot Metal Gas Forming for Curved Complex Part Geometries

Abstract

Climate targets set by the EU, including the reduction of CO2, are leading to the increased use of lightweight materials for mass production such as press hardening steels. Besides sheet metal forming for high-strength components, tubular or profile forming (Hot Metal Gas Forming—HMGF) allows for designs that are more complex in combination with a lower weight. This paper particularly examines the application of conductive heating of the component for the combined press hardening process. The previous Finite-Element-Method (FEM)-supported design of an industry-oriented, curved component geometry allows the development of forming tools and process peripherals with a high degree of reliability. This work comprises a description regarding the functionality of the tools and the heating strategy for the curved component as well as the measurement technology used to investigate the heat distribution in the component during the conduction process. Subsequently, forming tests are carried out, material characterization is performed by hardness measurements in relevant areas of the component, and the FEM simulation is validated by comparing the resulting sheet thickness distribution to the experimental one.

Latest Hydroforming Technology of Metallic Tubes and Sheets

“…The contributions are generally divided into three basic groups according to the workpiece geometry and forming methods. The first group is tube hydroforming (THF) [1][2][3][4][5][6][7][8][9], in which a hydraulic media and dies are used to deform a tube workpiece. The second group is tube forming [10][11][12][13][14], in which only dies are used to deform a tube workpiece.…”

“…Hwang et al [5] proposed a new hydro-flanging process combining hydro-piercing and hydro-flanging to investigate the effects of punch shape and loading path in the hydro-flanging processes of aluminum alloy tubes. Bach et al [6] used the functionality of the tools and the heating strategy for a curved component as well as a measurement technology to investigate the heat distribution in a component during hot metal gas forming (HMGF). Yoshimura et al [7] proposed a local one-sided rubber bulging method of metal tubes to evaluate various strain paths at an aimed portion and measured the forming limit strains of metal tubes at the place of the occurrence of necking under biaxial deformation.…”

“…Besides sheet metal forming for high-strength components, tubular or profile forming (hot metal gas forming-HMGF) allows for designs that are more complex in combination with a lower weight. Bach et al [6] used the functionality of the tools and the heating strategy for the curved component as well as the measurement technology to investigate the heat distribution in the component during hot metal gas forming. This paper particularly examined the application of conductive heating of the component for the combined press hardening process.…”

Integration of Hot Tube Gas Forming and Die Quenching of Ultra-High Strength Steel Hollow Parts Using Low Pressure Sealed-Air

“…Neugebauer and Schieck [19] developed a gas forming process with a maximum pressure of 80 MPa and a maximum temperature of 1000 • C for tube press hardening with integrated heat treatments to form high-strength products. Bach et al [20] heightened a pre-bent steel tube with the combination of gas forming and conductive heating. Winter et al [21] investigated the influence of local cooling rates on the mechanical properties of the quenching and partitioning-steels in gas forming with the forming pressure of 70 MPa.…”

Upset bulging as a preforming operation for hot metal gas forming of 22MnB5 tubes

“…This process can be coupled with a simultaneous heat treatment, how it is done in a press hardening (or hot stamping) [12]. The process of tube gas forming coupled with a quenching of a hardenable steel or alloy is known as hot metal gas forming (HMGF) [13]. A tube or a hollow profile made of high hardenability steel, such as 22MnB5 [14], deforms in a fully austenitized state by means of internal gas pressure in order to fill the die cavity [15].…”