Modeling of Burns When Grinding Hardened 30KhGSA Steel Parts
The multiple dispersion analysis (MDA) models based on a D-optimal plan were developed for predicting the quantitative content of the burns and microhardness of the parts surfaces made of hardened steel 30KhGSA when grinding by abrasive Norton Quantum wheel 5NQ46I6VS3. It showed the best cutting capacity under fuzzy logic conditions with regards to position and dispersion measures for roughness and form accuracy. The models obtained are adequate in the factor space: longitudinal feed sl = 5-15 m/min, cross feed sc = 2-10 mm/double pass, cutting depth t = 0.005-0.02 mm, operational allowance z = 0.1-0.3 mm (cutting speed vw = 35 m/s). The method of quantitative evaluation of the burns with the application of digital technologies can be used to detect a significant effect of the longitudinal feed ( A, A 2) and cross feed ( B, B 2), allowance ( D ) and the first order interactions: AB, BD. MDA models with regards to microhardness are represented only by the longitudinal feed ( A, A 2). It has been established that the sl and sc feeds are the most significant technological factors. In particular, 30KhGSA steel parts should be ground at sl ≥ ≥ 10-12 m/min. The increase in the operational allowance in rough grinding is conducive to the reduction of burns. To improve the removal allowance productivity, grinding should be done at the maximum cutting depth t = 0.015-0.02 mm, which is insignificant in regressions to burns in the factor space. The reduction of microhardness in the areas of the greatest burns indicates that the grinding burns are the result of the surface softening without re-hardening.