【作者】 王娟；

【导师】 裘祖荣；

【作者基本信息】 天津大学 ， 测试计量技术及仪器， 2012， 博士

【摘要】 大型自由锻件是制造大型技术装备关键零部件经常采用的毛坯形态,广泛应用于电力、船舶、石化、冶金、航空、航天等战略性产业,在我国整个制造行业中占有重要地位。由于是在高温状态下成型,对大型锻件的尺寸和形位误差进行在线测量与精度控制是一个长期未能解决的问题。高温锻件尺寸的精确测量与反馈,对于指导生产工艺和提高大型锻件材料的利用率及其制造效率具有重要的理论意义和经济意义。本文在总结分析了国内外大型高温锻件测量方法与测量技术的基础上,提出了基于激光跟踪仪的视觉坐标测量方法,该方法可望大幅度提高大型高温锻件的测量速度和测量精度。论文主要研究内容与创新之处包括:1、将基于激光跟踪仪的视觉坐标测量方法应用于大型高温锻件的在线测量过程。解决了大型高温锻件在线测量过程中环境恶劣、表面高温、视觉盲点、尺寸大等问题。该方法的应用有望大幅度提高大型高温锻件的在线尺寸测量精度。2、提出了测量系统的基本结构,并描述了测量过程。建立了基于激光跟踪仪的视觉坐标测量模型,并利用梯度下降法对系统模型进行了优化。3、计算分析了热传导、热对流、热辐射三种传热方式对测量环境及测量设备的影响,根据测量系统对测量环境的要求,设计了测量系统的关键部件,设计了光笔的结构。4、完成了热辐射对测量部件表面温度的影响实验,防热辐射材料性能实验及非均匀温度场对测量激光束的影响实验。实验结果验证了锻件周围温度场瞬态分析的正确性。计算了温度对空气折射率以及对激光干涉测长的具体影响,与实验结果进行了对比,证实了本测量方案的技术可行性。此外,通过大量的仿真实验,分析了系统中影响测量精度的因素。并在实验室条件下完成了系统测量实验,仿真与实验结果都证实了这一新测量方法满足大型高温锻件的在线测量要求。5、利用设计的系统,采用不同的测头对不同锻件直径进行了测量,提出测头采用球坐标系,利用球面测点的精确位置,通过半径补偿可以有效减小数值计算误差。更多还原

【Abstract】 Large scale hot forgings are the rough casts which are frequently used to make huge technological manufactures, and widely applied in some strategic industries which include electric power, shipbuilding, petroleum and chemicals, metallurgy, aerobatics, aerospace and so on. This kind of technology has an important role in Chinese manufacturing industry. As the large-scale forgings are molded under the high temperature, the online measurement and precision control for the dimension and error on form and position has been an unresolved problem for a long period. The precise measurement and feedback of hot forging dimension has a significantly theoretic and economic value to guide the production techniques, and to enhance the utilization efficiency and its manufacturing productivity of large-scale hot forging materials. After sufficiently summarizing and analyzing the domestic and overseas measurement method and technology about the large hot forging dimension, the vision coordinate measurement technique based on laser tracker is presented in this dissertation, and it is highly possible to improve the measuring speed and precision for the large-scale hot forgings.The key points and innovative works of this dissertation are listed as follows:1. The system combining laser tracker with vision coordinate measurement technique is applied in the on-line measurement process of large-scale hot forgings. This method can be used to conquer the problems generated by the adverse circumstances, high temperature on the surface, blind points of vision measurement and large dimension during the on-line dimension measurement processes of large-scale hot forgings. The on-line measurement accuracy of hot forgings is possible to be greatly increased by applying this method.2. The basic structures of measurement systems are presented and the specific measuring processes are described. The the measurement model based on laser tracker is presented, and the system models are optimized through the gradient decreasing method.3. Influences of heat conduction, heat convection and heat radiation on the measurement environment and the measurement instrument are analyzed and computed. According to the requirements of measurement system for the measured circumstances, the key components of measurement systems and the basic structure of light pen are designed.4. The experiments about the influence of heat radiation on the surface temperature of measuring components, the performance of anti-heat radiation materials and the effect of inhomogeneous temperature field on the laser beam are carried out. The experimental results have verified the validity of transient analysis of temperature field around hot forgings. The impacts of temperature on the air refractive index and the length measure with interferometry are computed, and the computing results are contrasted with the experimental ones. These results have demonstrated the technological feasibility of our measuring schemes. In addition, through a plethora of simulation experiments, the factors of impacting the measuring accuracy are analyzed and established, and the related measuring experiments are performed in the laboratory. The simulation and experimental results have both confirmed that this new measuring method can satisfy the on-line measurement requirements of large-scale hot forgings.5. Based on this newly designed measurement systems, we can adopt different detecting heads to measure different forging diameters, and propose that the detecting heads use the spherical ordinate and utilize the accurate positioning of spherical measuring point , and then we can take us of the radius compensating techniques to effectively reduce the numerically computing errors.更多还原