Study On The Effect Of The Moving Trajectory Of The Biglide Parallel Kinematic Platform On Helical Drill

Drilling in the material processing is an important part.Most of the mechanical parts need hole processing.In recent years,some new materials continue to emerge,the commonly used conical twist drill has been unable to meet the processing requirements because of the long straight edge of the blade.As a new type of twist drill,the involute spiral twist drill has the advantages of good centering,small drilling force and high drilling accuracy.According to its grinding principle,Northeastern University independently developed a kind of biglide parallel CNC grinding machine.In order to improve the grinding technology of involute helical drill and promote the application of biglide parallel machine tool in actual production,it is necessary to explore the influence of moving trajectory of machine tool on helical drill.The research route of this thesis is as follows:(1)Combining with the motion characteristics of biglide parallel machine tool,the kinematic trajectory of moving machine platform is analyzed in the premise of satisfying grinding condition;(2)Mathematical modeling of the involute helix drill tip:Based on the movement law of the biglide parallel machine tool,the cutting edge of the drill tip,the flank of the drill core and the external flank of the drill tip are established by the coordinate transformation vector method.The relationship between the five structural parameters of the drill tip(the semi.point angle,the chisel edge angle,the lip clearance angle,the heel clearance angle and the rake angle)with the grinding parameters are established;(3)The effect of the involute screw point on the moving platform is simulated by MATLAB.According to the mathematical model,the change curve of the structure parameters of the drill bit with the motion parameters of the machine bed is made.The three-dimensional simulation graphics of the external flank face and the core part,especially the transverse edge,of the drill tip under different moving platform trajectories are compared and analyzed;(4)Finite element analysis of the involute helix drilling process:The solid model of the involute drill tip is established by UG and the finite element analysis software DEFORM-3D is used to simulate the drilling process.The axial force,torque and temperature in the process of drilling are analyzed and compared with which of common cone twist drill.(5)Grinding experiment:The GUI of the drill tip structure parameters was developed to solve the interface,and the grinding parameters were compared with the results of the GUI to verify the rationality of the mathematical model.The results show that the involute helical drill tip is not only different in shape but also different in drilling performance because of the different trajectories of the moving platform used in the parallel machine tool,but it is still superior to ordinary twist drill.In the same kinematic curve,the Z-direction velocity of the kinematic trajectory is faster,and the drilling performance of the drill tip is better.