Manufacturing of shaped holes in multi-layer plates by laser drilling

Providing the technology to achieve an efficiency of 65 % in natural gas-fired combined cycle power plants is the aim of the Collaborative Research Center 561 "Thermally highly loaded, porous and cooled multilayer systems for combined-cycle power plants" at RWTH Aachen University, Germany. For these purposes, the fluid temperatures in the gas turbine cycle have to be raised considerably. This requires a more effective cooling of the thermo-mechanically highly-loaded parts, which is achieved by a newly developed effusion cooling. Within this paper drilling of cooling holes at an acute angle and generating the fan shape at the hole outlet by pulsed laser radiation is discussed as a new manufacturing technique. The drilling techniques used are percussion drilling for the through holes and five-axis trepanning for the fan shapes. The influence of the process gases argon and oxygen with different gas pressures on the drilling are investigated. By using superposed laser radiation a significant decrease of drilling time and of standard deviation of the drilling time is achieved resulting in a reduced over all machining time.

Subjects

Aspect ratio

Laser drilling

Process monitoring

Shaped holes

Superposed laser radiation

DDC Class

530: Physik

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Manufacturing of shaped holes in multi-layer plates by laser drilling