The Study Of Effects Of Secondary Cutting On Surface Damage Of Monocrystalline Silicon

As a kind of infrared optical material with excellent performance and low price,monocrystalline silicon is widely used in thermal imaging system,forward-looking infrared,mobile sensor and other high-tech fields.Because of its advantages in surface roughness,shape precision control and machining efficiency,ultra-precision cutting is applied to ultra-precision machining of single crystal silicon parts.High quality parts usually go through multiple processes.In fact,there are surface and subsurface damage problems in every cutting.If the influence law of secondary cutting on surface damage is found on the basis of previous cutting damage,it is meaningful to guide the cutting process of monocrystalline silicon and reduce surface damage.In this paper,molecular dynamics simulation method is used to study the shape.Firstly,the workpiece surface with damage layer is obtained by cutting on the surface of single crystal silicon with complete lattice,and then the second cutting is carried out on the surface with damage layer,so as to obtain the information of input cutting on the surface with damage layer,and then the second cutting process is analyzed.This article first analyzes the whole process of the second cutting,and compares the cutting for the first time,found in the process of the second cutting force,potential energy changes,stress and temperature changes are for the first time,and in the process of cutting,through the analysis of the causes of different damage layer makes the cutting for the first time by the nature of the material on the surface of the workpiece has changed.During the second cutting,the cutter will cut inside the damage layer,and the damage layer will absorb part of the energy,slowing down the lattice damage of the atoms of the undamaged workpiece below the damage layer.Then the concrete structure inside the damage layer was analyzed,and it was found that the internal structure of the damage layer after the second cutting was similar to the internal structure of the damage layer after the first cutting,which was composed of phase transition and dislocation.However,the surface damage of the workpiece after the second cutting was obviously better than that after the first cutting.In the second cutting,the phase transition of the 10° front cutting tool is less rapid than that of the 0° front cutting tool and the-10° front cutting tool.Finally,in order to study the influence of process parameters on the damaged layer in the second cutting,two key parameters: the thickness of undeformed chip and the influence of tool front Angle on the cutting process were analyzed.Different from previous research conclusions,the damaged layer condition after cutting with 10° and 0° front Angle was better than that with-10° front Angle.