Research On Aspecial CNC Milling Machine For External Arc Segment Of Flywheels

Flywheel is a common part of the engine, its circular arc notch which embedsmagnets needs to be processed. Conventional milling circular arc segment uses turretinstalled with special fixture, through the worm gears driving machining parts to turn,precision and efficiency is very low, difficult to meet the needs of high-volumeproduction. To solve this problem, a special milling machine for flywheels was designedbased on double-spindle double-station four-turntable in this paper, being high efficientin milling theexternal arc segment.The general situation of the development of numerical control technology and thedevelopment status of arc milling machinewere introduced in this paper, the backgroundand significance of the selected subjectwere expounded, and then the research workwasdeveloped around the following aspects:Firstly, movement principle and mechanical structure of the milling machine wereintroduced. The new structure of milling machine based on double-spindledouble-station four-turntable, uses longitudinal feed of sliding table and circular feed ofworkpiece turntable to form cutting trajectory in polar coordinates, and uses the rotarymotion of station turntable to constitute double stations: processing and handling，eachstation can mill two workpieces simultaneously. As a result, the processing efficiencydoubled.Secondly, the dynamic characteristic of double spindle system was analyzed.Because of the symmetrical layout of double-spindle structure, the cutting forceproduced by the two cutters, which has effect on the spindle box together and mutualinterference on each other, is easy to cause vibration and affect the machining accuracyand surface quality. To analyze vibration weaknesses of spindle box, and improve itsstructure and vibration resistance, its finite element model was established on ANSYSWorkbench14.0, modal and harmonic response was analyzed.Thirdly, the control system of milling machine and a new linear interpolationalgorithm in polar coordinatewere described.Milling machine basing ARM9asmicroprocessor, photoelectric encoder as feedback, the speed of three-phaseasynchronous motor was realized by inverter control, the positive and negative rotationof DC motor was realized by L298N drive, and the position control of ac servo motorwas implemented by the PID strategy.Feed and retract of milling cutter were completed though the collaboration of radial and circumferential movement of flywheel. Its controlprogram adopted a new linear interpolation algorithm in polar coordinate.Finally, the processing experimental data was analyzed. To explore the processingperformance of milling machine and verify its vibration resistance, the three-factor andfour-level orthogonal experimentsweredesigned after assembling and debugging theexperimental prototype, the milling speed v, each tooth feeding f, milling depthapwere selected and prepared, the best cutting parameters were obtained.