Seif Guide Mechanism Research And Drilling Process Parameter Optimization Of Staggered Teeth BTA Deep Hole Drilling

There are some problems that complex of processing and chip breaking difficult in the deep hole processing,which restricted the development of deep hole machining technology.BTA deep hole drilling is used for machining holes of nuclear power tube sheet,with achieving high productivity,and the high machining stability,especially good quality of drilled hole.If the processing parameters selected is not reasonable,it will leaded to chip abnormally breaking,and processing quality declining.This article is a deep hole processing project of nuclear power steam generator tube sheet as the background.Through building theoretical model and experimenting of the staggered teeth BTA deep hole drilling process.The change rules of drilling force,chip breaking and processing quality with drilling process parameters is reseached,The reasonable drilling process parameters of nuclear power tube sheet deep holes is obtianed by optimized.The working principles and characteristics of the deep hole drilling system is summarized.The BTA deep hole drilling principle is expounded.The staggered teeth BTA drill force of the drilling process is analysed.The cutting force model is established,which get the staggered teeth BTA drill drilling force and mechanical characteristics of the guide pads.The main factors of affecting the drilling force is analysed.The chip fracture form of the staggered teeth BTA drilling is analyzed.Fracturing model of chip is established,researching on size of chip breaker and drilling feeding have effect on chip fracturing.By researching self-guiding working mechanism of the BTA deep hole drilling,revealing the BTA drilled final hole wall rely on burnishing and friction of the guide pads and hole wall,together working plastic deformation with elastic recovery.Drilled hole wall lower roughness,higher hardness,better resistant corrosion and wear properties.Set up the BTA deep hole drilling experiment platform and drilling force testing system,Through the experimental research change rule of cutting force and chip deformation and fracture under different drilling process parameters.The results show that the cutting speed seems to have a limited influence on the deformation and fracture of chips.As the increase of feed,increasing of the drilling force and deformation coefficient of chips,decreasing of the length and fracture coefficient of chips.The experience formula of the chips fracturing coefficient for the staggered teeth BTA drilling is obtained by the method of linear regression,to forecast of the chip fracture under different drilling parameters.By means of experiment studys hole size precision and surface quality of staggered teeth BTA deep drilled changing with the drilling process parameters,Under the different conditions burnishing deformation of guide pads on the hole wall,hole diameter,surface roughness,micro-hardness is obtained.With the increase of feed,the burnishing deformation increases,the hole diameter decrease after the first increase,the surface roughness increases,the surface micro-hardness increases.With the increase of cutting speed,the burnishing deformation increases,the hole diameter increases after the first decreases,and the surface roughness is reduced,the surface of the micro hardness increases.Via drilling experiment for test piece of nuclear power tube sheet to obtain the wear form and law of staggered teeth BTA tool.The optimum drilling parameters for drilling nuclear power tube sheet use ?17.75 mm staggered teeth BTA drill is get by optimized,drilling speed v= 92.4 m/min(n=1657 r/min),feeding f = 0.114 mm/r.The results for providing guidance of deep hole drilling process parameters selection of the nuclear power tube sheet and optimization design of staggered teeth BTA drill.