In the last decade, press hardening has become a fully established technology in both science and industry for the production of ultra-high-strength structural components, especially in the automotive industry. Beside the improvement of car performance such as safety and lightweight design, the production process is also one focus of trends in technology development in the field of press hardening.
This paper presents an overview about alternative approaches for optimized process chains of press hardening, also including pre- and post-processing in addition to the actual forming and quenching process. Investigations on direct contact heating technology show new prospects regarding fast and flexible austenitization of blanks at compact device dimensions. By applying high speed impact cutting (HSIC) for trimming of press hardened parts, an alternative technology is available to substitute the slow and energy-intensive laser trimming in today’s press hardening lines. Combined with stroke-to-stroke control based on measuring of process-relevant parameters, a readjustment of the production line is possible in order to produce each part with individual, optimal process parameters to realize zero defect production of property-graded press hardened components with constant high part quality.
Significant research in the field of press hardening was carried out at Fraunhofer Institute for Machine Tools and Forming Technology IWU, in the hot forming model process chain which enables the running of experiments under conditions similar to industrial scales. All practical tests were prepared by design of experiments and assisted by thermo-mechanical FE simulations.
Additive manufacturing for tooling applications has seen a new boost with emergence of laser beam melting, a technology being capable of layer manufacturing completely dense parts and tool inserts in standard high-alloyed tool steel. Moulding applications have been the first in making use of the advantageous conformal cooling, e. g. in plastic injection moulding and aluminium high pressure die casting. Forming dies as another potential application for layer manufactured tooling have been scarcely addressed so far. The potential of additive manufacturing for added value in tooling applications has now been investigated for sheet metal forming processes. The paper presents results of a research project to apply laser beam melting to manufacture tooling for the hot sheet metal forming process of press hardening. The paper describes the shortcomings of current cooling channels in press hardening tools and the resulting waste of energy and unsatisfactory cooling effect in critical areas with insufficient target temp achievement and heat dissipation. The paper shows how an innovative cooling system has been implemented in the die through laser beam melted die inserts. Cooling of specific die areas has been realized by placing specially designed cooling channels very close to the die cavity, targeting shorter cycle times, improved mechanical properties of press hardened parts manufactured in the die and a reduction of energy consumption for cooling and idle times of forming presses. The paper presents the achieved results
Hot stamping is an important technology for manufacturing high-strength components. This technology offers the possibility to achieve significant weight reductions. In this study, cushion-ram pulsation (CRP), a new technology for hot stamping on servo-screw presses, was investigated and applied for hot stamping. Compared to a conventional process, the tests yielded a significantly higher drawing depth. In this paper, the CRP technology and the first test results with hot stamping were described in comparison to the conventional process
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