Study On High Speed Cutting Hardened Steel With The Coated Insert (CN35)

Dr. Carl. J. Salomon came out with high speed machining concept on his famous cutting test and its physics explicate in 1931. It shows the beautiful foreground for people that reduces the cutting time and advances productivity greatly. From 1970's on, industrial developed countries have developed research of the high speed machining technology, and brought into industrial use in 1980's in part. Most research literatures made mention of high speed machining about its high cutting speed and that it brings along the technical and economic benefits. This dissertation is with a view to reveal the high speed machining mechanism, and to research into where its physical nature is. Aiming at the different operating conditions in industrial use, how to achieve the optimal technical and economic effect.This research subject based upon the experimentation, the effects are observed and analyzed that the changes of cutting conditions in the high speed cutting courses on the chip deformation, cutting forces, cutting temperatures, cutting tools wear and dilapidation, workpiece machined surface profiles and so on. It is the metal cutting mechanism that is researched while high speed cutting process.That was discovered from researching the chip deformation, under the conditions of high speed cutting, the high strain rate and cutting thermal make the material deformation more active and complex, the new phenomena of cutting deformation appear. There are two kinds of chip shapes, banded and serrated. The local shearing deformation is the key of conducing the serrated chip coming into being. The cutting speed affects both sides on the chip forming. There are a lots SEM pictures in this dissertation, that show, the serrated chip is the typical form of chip deformation under the condition of high speed cutting. With the cutting condition varying, the chip form will be changed. The high cutting thermal from deforming and rubbing is the main factor to affect on material deforming.With the mathematical statistics to handle the cutting forces and temperatures test data, the empiric formulae are up built. The rules are revealed which both forces and temperatures following cutting conditions varying under the condition of high speed cutting from both assay curves and formulae. In the cutting course, the cutting forces'and cutting temperatures'varying trends are different with the different cutting conditions and factors, are complex.By means of SEM pictures and energy spectroscopy reports, the cutting tool's wear down and dilapidation are analyzed. Mechanical brunt makes tools dilapidation at low speed. Thermal brunt makes tools wear down at high speed. The tools'disable modes are abrasive wear, thermal fatigue and oxidation wear.The upheavals and furrows and dimples and side flows can be found from the SEM pictures and surface contour curves, which are affected on tool sharpening and wearing states and feed pathways, which are relevant to cutting conditions. The analysis to work piece superficial contour shows, it is not decrease that temperature in work piece superficies.