针对复杂曲面薄壁零件高效、精密在机测厚难题，提出一种面形自适应的超声在机测厚新方法，创新设计多功能高度集成的超声在机测厚装置，进一步建立超声在机扫描测厚运动控制基本模型。通过基于静力平衡的测量位姿解算和基于首次回波能量衰减的姿态偏角自动辨识，确定出传感器动态调整中的最佳测量姿态。对于具有固定时延的超声回波信号，利用所构造的步长控制函数，设计回波声时变步长自适应计算算法，可有效提高算法收敛速率和减小稳态误差。以弧形和S形薄壁件为典型对象，利用所研发的超声在机测厚系统，开展面形自适应超声在机测厚综合试验研究。试验表明，对在机测量的厚度数据实施姿态偏角误差补偿，其结果与三坐标测量机标定值相比较，测量精度可稳定在0.02 mm以内，满足了复杂薄壁零件在机测厚需求。
Precise and efficient thickness on-machine measurement is a challenging problem for complex thin-walled parts. A shape adaptive thickness on-machine measurement method using ultrasonic is developed. A multi-function integrated ultrasonic thickness on-machine measuring device is innovatively designed, and a basic measurement motion control model is further established. The best measuring posture of ultrasonic sensor in dynamic adjustment can be determined, through the position and pose calculation based on static force equilibrium and the posture angle error automatic identification based on first echo energy attenuation. For echo signals with fixed time delays, a variable step size adaptive algorithm for ultrasonic time of flight(TOF) calculation is designed using a novel step control function, which can improve the convergence rate and reduce the steady-state error effectively. Taking the arc-and S-thin-walled parts as typical objects, the experimental study is conducted using the proposed method. It shows that the ultrasonic thickness on-machine measurement accuracy with posture angle error compensation can be controlled within 0.02 mm by comparing with coordinate measuring machine(CMM) calibration, which could meet the requirements of thickness on-machine measurement of complexed thin-wall parts.
[1] 贾振元,王永青,王福吉,等. 高性能复杂曲面零件测量-再设计-数字加工一体化加工方法[J]. 机械工程学报,2013,49(19):126-132. JIA Zhenyuan,WANG Yongqing,WANG Fuji,et al. Research on measure-redesign-machining integration manufacturing method for complicated surface parts with high performance[J]. Journal of Mechanical Engineering,2013,49(19):126-132.
[2] 刘少伟,李迎光,郝小忠,等. 基于特征的蒙皮镜像铣加工残区刀轨优化方法[J]. 航空学报,2016,37(7):2295-2302. LIU Shaowei,LI Yingguang,HAO Xiaozhong,et al. Feature-based uncut region tool path optimization method for skin parts machined by mirror milling system[J]. Acta Aeronautica et Astronautica,2016,37(7):2295-2302.
[3] 陈天瑞,项延训,陈虎,等. 基于相位-频率测量的材料残余应力超声表征方法[J]. 机械工程学报,2016,52(22):9-14. CHEN Tianrui,XIANG Yanxun,CHEN Hu,et al. Ultrasonic characterization of residual stress in materials based on phase-frequency relationship[J]. Journal of Mechanical Engineering,2016,52(22):9-14.
[4] VERTESY G,TOMAS I,UCHIMOIO T,et al. Nondestructive investigation of wall thinning in layered ferromagnetic material by magnetic adaptive testing[J]. NDT & E International,2012,47(4):51-55.
[5] TRAN D H,DERIBLE S,FRANKLIN H,et al. Ultrasonic measurements of particle retention by a porous medium[J]. Ultrasonics,2012,52(1):62-68.
[6] CONG S,GANG T. Ultrasonic thickness measurement for aluminum alloy irregular surface parts based on spectral analysis[J]. Transactions of Nonferrous Metals Society of China,2012,22:323-328.
[7] DIXON S,EDWARDS C,PALMER S B. High accuracy non-contact ultrasonic thickness gauging of aluminum sheet using electromagnetic acoustic transducers[J]. Ultrasonics,2001,39(6):445-453.
[8] JIANG G X,KATO H,YOSHIDA Y J,KOMAI T. Optimization of ultrasonic measurement of remelted zone thickness using backscattered waves[J]. NDT & E International,2002,35(4):221-225.
[9] CHRLESWORTH J P,TEMPLE J A G. Engineering applications of ultrasonic time-of-flight diffraction[M]. Hertfordshire:Research Studies Press LTD,2001.
[10] Fei D,Hsu D K,Warchol M. Simultaneous velocity,thickness and profile imaging by ultrasonic scan[J]. Journal of nondestructive evaluation,2001,20(3):95-112.
[11] DARIUSZ B,KRZYSZTOF C,ZBIGNIEW O. Review and comparison of variable step-size LMS algorithms[J]. International Journal of Acoustics and Vibration,2016,21(1):24-39.
[12] TILO P,MANFRED B,BASTIAN E,et al. High precision ultrasonic on-machine measurement[J]. Measurement,2006,39:407-414.
[13] 唐玉恒,黄云,邹莱. 钛合金管材壁厚自动超声检测装置研制[J]. 机械科学与技术,2017,36(8):1-5. TANG Yuheng,HUANG Yun,ZHOU Lai. Development of automatic ultrasonic measuring device for wall thickness of titanium alloy tube[J]. Mechanical Science and Technology for Aerospace Engineering,2017,36(8):1-5.
[14] 徐明,向兵飞,李响,等. 蒙皮镜像铣切系统及先进制造工艺的应用[J]. 制造技术与机床,2014(11):40-43. XU Ming,XIANG Bingfei,LI Xiang,et al. Application of mirror milling system and advanced machining technology for aircraft skin[J]. Manufacturing Technology & Machine Tool,2014(11):40-43.
[15] LIU H B,WANG Y Q,JIA Z Y,et al. Integration strategy of on-machine measurement(OMM) and numerical control(NC) machining for the large thin-walled parts with surface correlative constraint[J]. International Journal of Advanced Manufacturing Technology,2015,80(9-12):1721-1731.
