In the diploma thesis, we treated the problem of uncontrolled changes of dimensions and shape of the workpiece during CNC mill cutting, which were not caused by incorrect settings or machine errors, but by the behavior of the material itself. For this reason, the workpiece did not meet the prescribed dimensional requirements, since the structural element (linear electric actuator housing) must be constructed within very narrow tolerance limits. Although the workpieces had been annealed before machining, uncontrolled deformation was still occurring. The cause of the uncontrolled changes in shape and dimensions was ascribed to residual internal stresses that might remain in the workpiece after pre-machining steps (rolling, cutting). The purpose of the diploma thesis was to obtain information on the stress state present in the flat profile before and after stress relief annealing and how annealing affects the hardness and microstructural changes of the material. The residual stress state of the workpiece has been investigated by the hole drilling method and for comparison with the X-ray diffraction method. We found that stress relief annealing was not successful since the residual stresses were still relatively high and could cause the distortion of the workpiece during mill cutting.
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