Cutting Force Action And Structural Optimization Of Arc-free PDC Cutters In Vacuum Anhydrous Environment

The high vacuum anhydrous and complicated temperature environment of the moon watch will cause a lot of heat between the drill bit and the moon rock during the drilling sampling process,and the heat cannot be diffused in time,which in turn aggravates the wear of the tool,resulting in the cutting performance and use of the drill bit.Life expectancy is reduced.At present,most PDC bits use standard cylindrical sharp teeth.Due to the stress concentration and cutting force fluctuation behavior at the cutting tip,the cutting teeth are prone to blunt and broken teeth.The wear of the cutting teeth is mainly concentrated in the cutting edge area,which makes the cutting teeth lose their cutting efficiency,and ultimately leads to a sharp increase in the energy used for rock cutting.According to literature research,the shape of PDC cutting tooth edge has become an important research object for rock cutting,and it is essential to reduce the wear of cutting teeth and improve the life of cutting teeth.This paper mainly considers the influence of arc-shaped cutting teeth on rock breaking,and studies the changing law of cutting force and temperature during rock cutting,tool wear morphology and rock breaking mechanism.The main research contents are as follows:(1)The friction coefficient under vacuum conditions and the temperature on the cutting teeth are much higher than the ambient air conditions.Under atmospheric conditions,the contact area of the cutting teeth mainly undergoes smooth wear.This wear mode usually occurs when drilling in homogeneous layers.Yes,the formation is highly abrasive,and the polished surface is very smooth,without causing it to break in a macro sense.Under vacuum conditions,most of the heat generated by the plastic deformation of the chips and the friction between the cutting teeth and the chips and rocks is transferred to the cutting teeth,which causes the temperature of the cutting teeth to rise.In the absence of drilling fluid,the heat generated in the vacuum cannot be timely Diffusion,aggravating the wear of cutting teeth.(2)By simulating the rock cutting process,the variation rules of temperature,cutting force and rock breaking during different arc tooth cutting processes are obtained: sharp teeth: the peak temperature of the cutting tooth is the highest,and the force is mainly concentrated in the contact area of the rake face,mainly It is manifested by the cutting action,which produces large lump cuttings;the arc radius is 0.2mm-0.5mm cutting teeth: the peak temperature on the tooth is small,which significantly reduces the stress concentration on the tooth and has good cutting performance,resulting in small lump Rock cuttings;circular arc radius 0.8mm-1.5mm cutting teeth: The cutting teeth enter the stage of severe wear and tear,the cutting performance is significantly reduced,the rock breaking method changes,and powdery cuttings are produced.(3)The radius of the cutting edge can prevent rapid and unpredictable wear.The stress distribution of sharp teeth during the cutting process is relatively concentrated and the fluctuation is large,which is prone to chipping.The arc-shaped teeth of a reasonable radius can improve the mechanical strength of the cutting teeth and make the local concentration The cutting stress is dispersed and the fluctuation phenomenon is significantly reduced.In particular,the results obtained from the simulation have confirmed that there is an optimal cutting edge radius(0.2mm-0.5mm),thereby reducing the cutting tooth breakage and wear phenomenon,and increasing the life of the cutting tooth.