Research Of Designing And Controlling Shaped Piston CNC Lathes

Shaped piston, named convex variable oval piston, means that it owns a special shapeof work side. However, this kind of piston has superior performance in the engine, it’sdifficult to manufacture. It’s urgently needed a kind of processing equipment withefficient to proving production efficiency in the time of low marine large diameter pistonproduction nowadays. The convex variable oval piston lathe, which can decide the qualityand accuracy of processing piston directly, is the key part in producing piston.This paperdesigns a new type of numeric control lathe of piston based on convex variable oval pistonmachining. The main contents of this paper include the following aspects:1）For home and abroad the research status of convex variable oval piston lather athome and abroad, this paper proposes the main content and the goal of research.2）According to the characteristic of piston skirt side, mathematic formulas aredescribed to skirt type line and some complex type lines of modeling motion areresearched. The cubic spline fitting interpolation of skirt type line be realized inMATLAB and researching the interpolation processing principle of it, using polarcoordinate interpolation algorithm to cross-sectional interpolation and the equal lengthstraight-line method to the shaft cross-section interpolation.3）By researching the existing piston lathe, there is designed the overall structure ofconvex variable oval piston CNC lather to the processing principle of shaped piston, usingPro/E to establishing the physic model and selecting the key parts of piston lather. Themodel of spindle system is built in ADAMS which can analyze rigid-flexible couplingand verify the reasonableness of design.4）As the key parts of piston lather, servo turret is drove by permanent magnet linearmotor. The motion model of linear motor is built by using ADAMS, analyzing the motorof high-frequency micro-feed motion, which is the base of achieving high precisionmotion control. The dynamics model of servo turret is established and the controller of itis designed. According to the requirements of piston cross-section to the servo cuttingknife, optional complex PID algorithm of feedback+speed/acceleration feed-forward tocontrol the turret position in real time.5) Using the module of ACRView can comprehensively set the PID parameter andvelocity/accelerate feed forward parameter of linear motor position control system, whichin the motor linkage experimental platform based on Parker controller,the followingexplore is the linkage control between linear motor and servo motor. Above all is based on the processing of large-diameter convex variable oval piston.There are some theoretical significance and application value to the piston processing ofengine in ship, same to other non-circular cross-section parts.