Abstract
Laser hardening is a surface hardening process which enables high quality results due to the controllability of the energy input. The hardened area is determined by the heat distribution caused by the intensity profile of the laser beam. However, commonly used top-hat laser beams do not provide an ideal temperature profile. Therefore, in this paper the beam profile, and thus the temperature profile, is optimized using freeform optics. The intensity distribution is modified to generate a top-hat temperature profile on the surface. The results of laser hardening with the optimized distribution are thereupon compared with results using a top-hat intensity distribution.
Highlights
Lasers can be used in a lot of different technical applications
Four commonly-used laser intensity distributions exist for laser hardening, two of which can be generated with static optical elements, which are the defocused, round top-hat profile and the rectangular top-hat profile
Shafts with a diameter of 50 mm made of 42CrMo4 (AISI 4140) have been hardened on the lateral this, the inverse heat conduction problem was numerically solved by the Chair for Technology of area using a homogenized top-hat laser spot withUniversity a spot size
Summary
Lasers can be used in a lot of different technical applications. While in measuring technologies the specific characteristic of this type of light is important, in production processes the extremely high energy density makes it a crossover technology which is used for laser-assisted tape laying of thermoplastic prepregs [1] as well as for cutting thick metal sheets, or even surface structuring. Besides other benefits the intensity distribution of these sources can be adjusted by switching individual diode arrays of the stacks on and off Until this technology will be available, optical elements such as mirrors, lenses or fibers have to be used which guide the light from the laser sources to the work piece. Most systems have complex optics which project the laser spot onto the work piece and change the shape or even the power density distribution [8,9,10]. The usage of such optics has been investigated in the following research. An analytical model has been used to illustrate the resulting temperature field in the work piece
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