Parametric Design And Drilling Experiment Research Of Three-blade Shovel Taper Countersink Drill

As an important part of finish machining,the hole machining process in machining can not meet the demand of automation and intelligence in manufacturing industry.With the rapid development of aerospace,vehicles,submarines and other high-end manufacturing fields,people put forward higher requirements for the quality and efficiency of hole machining.In recent years,a shovel tooth taper countersink has been widely used in hole machining processes such as countersinking,taper hole machining,hole chamfering and deburring,etc.Tool parameters and cutting parameters have become the main factors affecting its machining quality.In this paper,the parametric modeling system of shovel tooth taper countersink is developed by studying the shape characteristics and cutting mechanism of taper countersink,combining the mathematical modeling formula and NX/Open secondary development kit.The countersink model generated by the parametric modeling system is simulated by finite element method in DEFORM-3D platform,and the optimal tool parameters are obtained.Finally,combined with the corresponding drilling experiments,the tool geometry parameters and cutting parameters of the spade drill are verified and optimized.The main research contents of this paper are as follows:(1)Through the research and analysis of the cutting mechanism and application characteristics of shovel tooth taper countersink,the structure and shape of countersink are mathematically analyzed.By analyzing the grinding situation of the shovel tooth taper countersink in the machining process,the cross-section movable frame for grinding wheel is created.Then,by analyzing the surface forming principle of shovel tooth taper countersink,the cutting edge curve equation and the end surface curve equation of countersink are obtained.Finally,the mathematical models of the rake face,the rake face and the chip flute of shovel tooth taper countersink are built.(2)The external data access technology and its practice flow in NX secondary development are introduced in detail.Firstly,through the key technology of creating standard parts library,the connection with open data interconnection technology is established based on Access database management system,and then NX/Open API function is called to complete the secondary development of shovel tooth taper countersink.The tool model can be updated by changing the size parameters in the database.Finally,the three-dimensional model of the tool can be automatically loaded by clicking the tool model,which significantly improves the design efficiency of the tool.(3)The finite element simulation system based on DEFORM-3D software is established.Using orthogonal experiment method,the drilling simulation experiment of shovel tooth taper countersink generated in parametric modeling system is carried out.By sorting out and analyzing 9 sets of simulation data obtained by orthogonal experiment,and considering the machining conditions and machining efficiency comprehensively,the following conclusions are obtained:when the geometric parameters of shovel tooth taper countersink are respectively 20 front angle,4 back angle,50%base circle and 2 spiral angle,the axial force and torque in countersinking process are the smallest.(4)The drilling test platform of shovel tooth taper countersink is set up.Taking drilling 45 steel as an example,the accuracy of finite element simulation model is verified by analyzing the axial force and surface roughness of drilling.The effects of feed rate per tooth and cutting speed on axial force and surface roughness are studied by single factor experiment method.Combined with machining efficiency,it is concluded that the optimal cutting parameters are cutting speed45m/min and feed rate per tooth 0.1mm/r under the working condition of machining chamfer depth1 mm.