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    Effects of Blanking Speed on the Shear Surface of Mild Steel (St37)
    (Polish Acad Sciences Inst Physics, 2016) Kanca, E.; Eyercioglu, O.; Karahan, I. H.; Gunen, A.; Gov, K.
    Blanking operation is widely used to cut sheet or plates by a shearing process between punch and die. The process of shearing and the conditions of the sheared surface are influenced by the punch, the die, the speed of punching, the clearance between the punch and the die. In this study, effects of high speed blanking on surface quality and corrosion properties of mild steel St37 shear surface have been investigated. The work presented in this paper aims at evaluating the shear surface quality improvements of the St37 resulting from the use of high energy rate forging machine. The appraisal is based on criteria related to surface accuracy and corrosion resistance characterization. For this purpose, St37 mild steels were cut using three different punch speeds hydraulic presses at nearly quasistatic, conventional mechanical presses at low punch velocity (0.2 m/s) and high energy rate forging machine at high punch velocity (10 m/s), for different die clearances (4.5%-6% of sheet thickness). After accelerated corrosion tests, blanks were performed in conjunction with scanning electron microscopy technique to study the cutting process of the blanks at room temperature. In fact, by using high energy rate forging machine, a reduction of more than 25% of the surface roughness (R-a) was realized and better resistance to stress corrosion cracking and pitting corrosion was noticed. It was observed that the corrosion resistance of the high energy rate forging-cut specimen was better than that of the hydraulic-cut and mechanical-cut specimens.
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    Tool life model for Al2O3 particle reinforced MMCs using genetic expression programming
    (Taylor & Francis Ltd, 2011) Kok, M.; Kanca, E.; Eyercioglu, O.
    In the present work, the wear of cutting tools in the machining of 7075Al alloy composites reinforced with 10 and 25 wt-% and 16 mm average size Al2O3 particles was investigated. Machining tests were performed on both as cast and heat treated composites by turning process using a physical vapour deposition coated carbide tool CP500 at different cutting conditions. A new model was developed to predict the tool life by genetic expression programming. The training and validation data sets were obtained from the well established machining test results. The weight fraction of particle P-w, cutting speed V, feedrate f and heat treatment Ht were used as independent input variables, while tool life T was used as a dependent output variable. Different models for tool life were predicted on the basis of the training data set using genetic programming, and the accuracy of the best model was proved with validation data set. The test results showed that the genetic expression programming model has produced correlation coefficient R values of similar to 0.958 for the training data and 0.952 for the validation data. The predicted tool life results were compared with experimental results and found to be in good agreement with the experimentally observed ones.