Study On The Chamfer Parameter Of PCBN Cutting Tool In Interrupted Cutting

The PCBN cutting tool,with many advantages such as good wear resistance,thermal and chemical stability,low friction factor and so on,has been widely used in hard machining and dry cutting of ferreous materials.However,in the interrupted cutting,the chamfer parameter selection is mainly based on the situation of chamfer parameter in continuous cutting,which easily results in the damage of the tool in practical processing.Therefore,it is necessary to make a deep study on chamfer angle under the conditions of interrupted cutting.There were abundant researches on cutting hardened steel with PCBN tool both at home and abroad in the past years,and many valuable experimental results and conclusions had been obtained.However,the research on PCBN tool cutting ductile iron and vermicular cast iron,which are widely used in manufacturing,was rather limited.So the influence of the chamfer angle on cutting force,tool life,surface roughness and tool wear in interrupted cutting was studied in this paper.First,through disposing and analyzing the experimental data by using the BN250 PCBN tool to turn hardened steel,the results of the research are as follows:among the four tool chamfer angle(γ₀₁=-15°,-20°,-25°,-28°) adopted in the experiment,the effective radial impact force is the smallest atγ₀₁=-25°,b_γ1=0.4mm and the tool life is the longest at these values;the wear reason is chemical and mechanical wear;the form of the chip is serrated chip, and the chip deformation becomes more and more obvious when the chamfer angle grows up. Second,by using the BN700 tool to process nodular cast iron,the influence of the chamfer angle on cutting force and surface roughness was further investigated in this article, meanwhile three different cutting parameters were adopted to study the wear mechanism and tool life when the BN700 tool is used to cut nodular cast iron.The results show that:among the three angles of chamfer(γ₀₁=-15°,-20°,-25°),the longest tool life is achieved atγ₀₁ =-25°,b_γ1=0.4mm;the changing range of the surface roughness Ra of workpieces processed by three tools is between 0.6～3.0um,and Ra change is the smallest atγ₀₁=-25°;the main wear reason is chemical wear.At last,the economical cutting parameters are obtained by turning these two materials,the conclusions are as follows:when the hardened steel is turned: V=135～175m/min,f=0.05～0.15mm/rev,a_p=0.05～0.1mm/rev,the result is much more better,and V=110～135m/min,f=0.05～0.1mm/rev,a_p=0.05～0.1mm/rev used to turn the ductile iron could get satisfactory outcome.