【作者】 张敏；

【导师】 黎向锋；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2011， 硕士

【摘要】 螺纹连接作为机械结构中最常用的连接方法之一,其性能要求越来越高;因此,螺纹构件的抗疲劳设计与制造已经成为现代机械加工技术中最为重要的课题之一。内螺纹冷挤压成形因具有较高精度和疲劳寿命及其表面完整性好的特点,成为当今螺纹抗疲劳加工的一个发展趋势。基于多传感器信息融合技术,开展内螺纹冷挤压成形质量预测研究将为内螺纹质量的检测提供一种新途径。本文完成的主要工作和取得的成果如下:1.基于LabVIEW设计开发了内螺纹冷挤压在线测试系统,通过电阻应变片、热电偶、加速度传感器、声级计以及数据采集卡,实现了内螺纹冷挤压成形过程中挤压扭矩、温度、丝锥振动及机床声音等多传感器信号的采集与存储。2.基于Matlab对获得的多传感器信号进行了预处理和特征提取,对挤压扭矩和温度进行了时域分析,以最大扭矩和最大温度作为其特征值;对丝锥振动和机床声音信号进行了时域、频域和时频域分析,研究了信号均方根值、功率谱以及小波能量等特征量的变化规律。3.基于内螺纹冷挤压试验研究了机床转速、工件底孔直径、润滑液以及挤压次数等工艺参数对内螺纹冷挤压成形的影响,初步优化了工艺参数;并在此基础上,研究了丝锥磨损状态对内螺纹成形过程信号及其成形质量的影响规律。4.基于VC++6.0和Matlab混合编程,设计开发了内螺纹冷挤压加工工件质量预测系统;该系统通过主成分分析对内螺纹冷挤压成形过程中的特征向量进行选择,采用BP神经网络实现了内螺纹成形质量的模式识别。更多还原

【Abstract】 As one of the connection methods for machine structures, the performance requirement of threaded connection becomes higher and higher. Fatigue design and manufacture of threaded connection has been one of the important research projects for modern machining techniques. Because of the high precision, high quality surface and long fatigue life, the cold extrusion of internal threads has become the development tendency in the field of threads anti-fatigue manufacture. Forecasting on the cold extrusion forming quality of internal threads provides a new solution for their detection based on the technology of multi sensor information fusion.The main work and the results as follows:1. The on-line test system on the cold extrusion processing of an internal thread is developed based on the software of LabVIEW. The foil gauges, a thermocouple, an acceleration transducer, a sound level meter and a piece of DAQ card are used to gather the signals during the cold forming processing of internal threads, such as the torque, temperature, tap vibration and lathe sound.2. Pretreatment and feature extraction of sensor signals are done based on the software of Matlab. Signals of both torque and temperature produced from the cold extrusion forming are analyzed in time-domain, maximum torque and max temperature are assumed their feature vector. Signals of both tap vibration and lathe sound are analyzed in time-domain, frequency-domain and time-frequency-domain, and the change law of signals is researched, which contains their RMS, power spectrum and wavelet energy.3. Influences of technological parameters on the cold extrusion processing are studied, such as the rotate speed of lathe, the bottom hole diameter of a piecework, kinds of lubricant and the times of extrusion forming. Also, the relation between forming processing signals and the tap wear state is researched based on the optimized technological parameters.4. Quality forecasting system on the cold extrusion forming of internal threads is developed based on hybrid programming of VC++ and Matlab. Principal component analysis is used to extract the feature vectors, and a neural network is used to realize the pattern recognition for internal threads forming quality.更多还原