Experiment Research On High Speed Machining Compacted Graphite Cast Iron With Hard Brittle Tools

Compacted graphite cast iron as a representative of the new engineering materials,RuT450 grade above the compacted graphite cast iron has good tensile strength,thermal fatigue strength,elastic modulus,thermal conductivity,wear resistance,processing and other characteristics,has become a manufacturing industry In the important structural materials.At present in the automotive engine cylinder,cylinder head and other complex components on the application of more and more widely,has been a good economic benefits.Due to the cutting characteristics of the compacted graphite cast iron itself,it is difficult for any tool material to process it,and it is one of the difficult materials.The contradiction between the growing market demand for vermicular cast iron and the relatively backward cutting process is particularly evident.At present,one of the important ways to solve the problem of difficult machining of materials is to use high-performance cutting tools and high-speed cutting technology.In this paper,high-speed turning experiments were carried out on CKA6150 CNC lathes using four kinds of hard and brittle tools.The effects of different cutting speed and back knife on the tool wear and surface quality were discussed.The wear morphology of the tool and the wear mechanism of the tool are studied.The morphological characteristics of the chip are also observed and studied.Experiments show that the cutting speed vc has a significant impact on the tool wear,the greater the cutting speed vc,the wear of the four tools also increases,the tool life with the cutting speed increases.Under the same conditions,the life of the cermet tool is the shortest.In the cutting process,the main wear mechanism of-the four tools is diffusion wear,chemical wear abrasive wear,adhesive wear.Tool wear and the amount of apron knife ap changes,and tool life and cutting speed vc curve similar to the curve.With the increase of cutting speed,the cutting heat generation in unit time is accelerated,and the thermal softening effect of workpiece materials starts to highlight.Therefore,with the increase of cutting speed,the surface roughness of workpiece has been reduced.With the cutting depth a,becomes larger,the machined surface roughness Ra.follow larger.The cutting parameters on the machined surface roughness Ra,the smallest is the cutting depth ap,the maximum cutting speed is vc.The cutting depth an has great influence on the macro morphology of the chip,the cutting depth is small,easy to produce fine machining chips,part of roll shaped cuttings;in depth increases,the sawtooth chips gradually weakened upward bending deformation,the equivalent chip thickness will gradually increase.The spacing between the sawtooth will continue to increase.In summary,the research of this paper has a certain reference value to solve the problem that the tool wears too fast during the machining process and finds the cutting parameters suitable for the difficult materials.