Intelligent system of improving contouring accuracy on CNC machine tools

• Main Authors: Ren-Bin Xiao, 蕭人賓
• Other Authors: Pi-Cheng Tung
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/33212484213508626254

碩士 === 國立中央大學 === 機械工程研究所 === 92 === Abstract As the development in industry, time and quality are more and more important. Therefore, automatic manufacturing machines are tending to high speed and high precision. In order to eliminate tracking error, appropriate compensation value of friction is necessary for manufacture of high precision when processing a circular profile or a curved surface on the CNC machine tools. Friction includes static friction, Coulomb friction and viscous friction. Static friction is nonlinear function, and it is one of the most significant sources of nonlinear disturbance for manufacturing. The transient response that is produced by static friction will deteriorate manufacturing precision because it makes the velocity profile non-smooth at zero crossing. The nonlinear component of friction such as static friction (stiction) should be overcome so that the tracking error will be eliminated. When the X-Y tables are tracking a circular profile, quadrant glitches appear at ninety degrees intervals, i.e. the motion of one axis has a zero velocity crossing and reverses direction. The quadrant glitches due to friction brought about transient phenomenon. For solving the transient phenomenon, we will make the system to reach steady state quickly by anticipatively compensating a value when the motion of one axis has a zero velocity crossing and reverses direction. But the appropriate compensated value is difficult to get through trial and error. An algorithm is developed to find the compensated value automatically. Finally, theoretical study, simulation, and experiment are performed to verify the proposed algorithm.