Simulation And Experimental Study On Mechanism And Drilling Force Of Tooth For BTA Deep Hole Drilling

BTA deep-hole drilling is a widely used deep-hole processing technology due to its high efficiency,good quality and stable processing performance.BTA deep-hole drilling adopts self-oriented processing principle.The tooth of BTA drills arranges asymmetrically.The mechanical load on tooth and guide pads and its distribution have an important influence on tool wear and stability during the drilling.This thesis focuses on BTA drilling process.The chip formation characteristic and deformation laws as well as BTA drills tooth drilling force and its distribution laws are studied by the method of Simulation and experiment.The chip formation mechanism and deformation laws during metal cutting process are described.The principle of the BTA drilling system and the working principle of staggered teeth BTA drills are discussed.The generation of drilling force is analyzed and the mechanical model of staggered teeth BTA drills is established.According to the characteristics of BTA drilling,the simulation program drilling equal diameter cylindrical workpiece and the annular element workpiece are determined.The geometric models of BTA drilling are established.The Johnson-Cook model is selected as the workpiece material constitutive model and separation criteria.The contact type for the tools and workpiece is determined.The finite element simulation models of three typical BTA drills are established with FEM simulation software ABAQUS.The drilling process simulation is implemented.The chip formation characteristics and deformation laws of each cutting tooth of BTA drills are analyzed.The results show that the cutter tooth cutting conditions gradually deteriorate,the chip deformation increased,and the extrusion deformation is growing worse with the decrease of cutting speed and the radius of curvature of the workpiece.The three-components of drilling force of tooth of three typical BTA drills are obtained.Effect of different structures drills on three-component proportional relationship of drilling force is revealed.Three-component of unit tooth drilling force distribution laws along the radius with different cutting parameters and drills structures are obtained and studied.The experimental platforms of BTA drilling and drilling force testing system are established.Experiment research is conducted on three typical BTA drills.Time-domain waveform of three-component of whole tooth drilling force and unit tooth drilling force are obtained.Unit tooth drilling force distribution laws along the radius are studied.As the results show,unit tooth drilling force presents the non-uniform distribution law which is increasing while the radius increases.The simulation and experimental results are basically consistent.The correctness of the simulation analysis is verified.The results of the research provide theoretical evidence for designing and optimizing the BTA drills.