Research On Hard Cutting Performances Of Chamfered PCBN Tool

The valve seat by powder metallurgy process is widely used because of its good abrasion resistance and high temperature resistance, but the cutting performance with carbide tool of this valve seat with high hardness is not good, the tool life is very short because of its internal microporous structure, so cutting valve seat with carbide tool leads to low benefit. In recent years, with the using of polycrystalline cubic boron nitride (PCBN) tool, hard cutting valve seat has been a promising advanced manufacturing technology for increasing productivity, reducing production costs dramatically and improving the machining quality.In this paper the PCBN tools were used for hard cutting powder metallurgy valve seat to investigate the effects of cutting parameters on machining performance, and this research has great theoretical value and practical significance. The main work and achievements are as follows:First in the cutting force measurement test, it is shown that the cutting forces Fx, Fy and Fz are all in an increasing trend with the increasing of the chamfer angle. With the increase of the chamfer width, cutting forces Fx, Fy, Fz appear to increasing at first and then decreasing and increasing again at last, in which the Fy changes obviously.Then by measuring the valve seat machined surface roughness, it is found that with PCBN tool chamfer angle increases, the valve seat machined surface roughness increases; and with the increasing of the chamfer width, the surface roughness increases at first and then decreases, finally trends to increasing again; and for PCBN tools with different chamfer width, the effect of feed on the surface roughness is not consistent.Finally, based on the PCBN tool wear test, it is shown that the PCBN tool’s failure modes are normal wear and breakage; the main wear forms include micro chipping, flank wear and rake face wear, the main wear mechanisms are abrasive wear, adhesion wear, diffusion wear and oxidation wear; the failure of main forms include collapse edge, peeling and chopping and so on.