The Research On The Cutting Mechanism Of Free-cutting Steel

With the great development of the machinery industry, the improvement of the levelof automatism, machinability requirements of the material will follow the continuousimprovement. Therefore, the development of free-cutting steel is very valuable.Through the changes of the chemical elements added, we get two different kinds offree-cutting steel (Calcium materials for1#, do not contain calcium materials for2#).we studied their cutting mechanism and machinability through a series of experiments.First of all, through the tool rapid disengage test, we got the chips root and analyzedthe cutting deformation mechanism of free-cutting steel. Also we collected theprocessing chip, observed its shape, and analyzed the breaker mechanism. The resultsshow that, the chip morphologies of two kinds of material are basically identical. Chipcompress ratio of materials1is increased then decreased with the increase of cuttingspeed because of the role of built-up edge. Cutting speed has a little influence on thedeformation of material2.Secondly, through cutting tests of two kinds of free-cutting steel material, wemeasured the tool life of these two free-cutting steels with different chemicalcomposition at different cutting speed, and we got the relationships of each materialbetween tool life and cutting speed. The results show that, the influence of cutting speedon tool life of these two kinds of free-cutting steel is very obvious, however, when at200,300m/min, both nearly have the same tool life.When measuring tool flank wear, we took the wear photos, then made EDS analysisof the blunt tools, so we can find different materials tool wear patterns and wearmechanisms at different cutting speed. The results show that, the tool wear patterns ofthe two materials are basically the same, there are obvious crater wear at differentcutting speed.Finally, in order to find the influence of cutting speed of each material on cuttingforce and surface quality, we used three-dimensional dynamometer to measure thecutting forces at different cutting speed, and used profilograph to measure the surfaceroughness values. The results show that, the cutting force of cutting two materials showa downward trend with the increase of cutting speed. Relatively, material1is easier toget a better surface roughness.