Structure Design Of Spiral Bevel Gear Milling Cutter And Simulation Analysis Of Milling Process

Spiral bevel gear is the basis component of mechanical transmission which is widely used in various types of high high speed machinery and some low speed transmission which requirement high stability. The widely used cutter to cut spiral bevel gear is Gleason facing cutter home and abroad. But the structure of the Gleason facing cutter is complex and with high cost. Installation and adjustment of Gleason facing cutter is more complicated. If the cutter tooth is weared, requires special grinding machine to grind the weared tooth. The facing cutter which is designed based on the theory of involution gear cutting on the tracing line has the advantages of simple manufacture, simple installation, simple adjustment and the grind of the tooth is simple. The cost of cutter is also redused. Because of the milling process have the features of multiple intermittent cutting edge and the cutting thickness is different. The milling force is complicated. Therefore combine the method of theoretical modeling and software analysis to make physical simulation on the milling process. At present, the physical simulation of the cutting process which use the method of relevant finite element software, especially on the condition of the relative motion of the workpiece and the tool is more complicated, the literatures about cutting force, cutting heat and cutter wear are rare. Especially the literatures of simulation analysis about relevant physical parameters during cutting process by the method of finite element software are almost none.Based on the theory of involution gear cutting on the tracing line, this thesis aims to design oblique spur spiral bevel gear milling cutter which is meeting the requirements based on the theory of involution gear cutting on the tracing line,and cut straight-skew spiral bevel gear with spherical involute. Because the milling process have the features of intermittent edge cutting and variable thickness processing and so on,the cutting mechanism is more complicated. Therefore the auther focuses on the relevant parameters of the milling process applying the method of theoretical modeling and software analysis to make geometry simulation and physical simulation on milling process with the purpose of choosing tool geometric parameters and cutting parameters reasonabely to exert the best cutting performance,which have significance theoretical guidance and verify. The main work of this thesis are as follows:(1) Take the theory of involution gear cutting on the tracing line as theoretical foundation, combine the metal cutting principle and the tool design theory, define the cutter diameter and the main geometric dimensions of the cutter edge. Because of the restrictions of tracing line size to cut a complete tooth and alveolar size of the small gear, the diameter of the cutter is larger and the thickness is smaller. To increase the structure stiffness of the cutter, take the ladder structure as the rake face shape of the cutter tooth. Taking the manufacture, clamping, grinding of the milling cutter, use the tipped of mechanical clamping style. Establish a solid model of the milling cutter. Convert the model to two-dimensional engineering drawings by the software AutoCAD to manufacture the milling cutter.(2) Select milling parameters reasonablyand calculate milling force preliminarily,establish finite element model of cutter tooth by large general finite element software ANSYS and exert boundary conditions on the cutter tooth, then add calculated milling force as load to the cutter tooth and do static analysis on it. Obtain the stress distribution graph and displacement of straight line graph of the milling cutter to master the sensitive parts of the cutter tooth. Compare the maximum stress calculated with the flexural ultimate strength to guide the selection of the cutter parameters.(3) Create three-dimensions solid model of machine,tool system,rough and fixture system in CNC machining simulation software VERICUT.Select appropriate control system and edit G-Code according to the motion equation. Then generate control file.Make real-time process simulation on L-gear of straight-skew spiral bevel gear and R-gear of straight-skew spiral bevel gear. Observe the process of cutting movement intuitively and make sure whether there exists collision,over-cutting,less-cutting and so on in the milling process.With the purpose of verifing the correctness of the cutting motion equation and the rationality of the cutter geometry.(4) Because of the milling process have the features of multiple intermittent cutting edge and the cutting thickness is different. The movement relationship of cutter and gear blank is complex. Therefore, analyze force situation of cutter tooth deeply. Use the large commercial finite element software DEFROM3D as a computing platform, make theory analysis on the key technologies such as knife-chip separation guideline, knife-chip contact relationship, friction relationship, thermal coupling theory and so on in the simulation process. Set relative parameters. Establish thermal coupling finite element model of cutter and workpiece. Make three-dimensional numerical simulation on the milling cutter under the condition of two groups milling widths according to the movement relationship of three axes linkage which is required in actual processing. Obtain the physical quantities such as stress, strain, cutting force, cutting heat, tool wear and so on. Analyze the physical quantities deeply. Compare the two groups simulation results. The simulation results provide basis for milling parameters selection form the view of how to reduce the plastic deformation, fatigue failure and prolong tool life.