Mechanical Thermal Deformation Measurement System And Its Error Analysis

With the increasing demand of high precision in the manufacturing industry of mechanical equipment,the thermal effect becomes the key factor to improve the precision. The research on the basic theory of mechanical thermal deformation can greatly reduce the influence of temperature, and it is of great value in scientific research and engineering application. In this research, it is important to measure the thermal deformation. Supported by the major program of the National Natural Science Foundation of China "shape function of surface structure and properties of the coupling effects modeling and mechanism of (project number:51490660/51490661), This paper takes the barrel and plunger of common types of oil pump as the research object, provided by an oil company, and does a systematic study on the measurement system and data processing of thermal deformation research.The main research contents of this paper are as follows:(1)According to the requirements of accuracy, anti-disturbance in the experiment, the acquisition system of mechanical thermal deformation is designed. The hardware structure and software structure of the system are introduced in the paper. The structure and principle of the measurement subsystem for the thermal error are described in detail. Among them, the selection of the high temperature shift sensor TWJH and the acquisition card,PCI-1716/1716L,the system circuit’s establish and the calibration of the sensor are included. The contrast experiment was designed to eliminate the systematic errors in the test preliminarily.In this experiment, taking quartz as the experimental material, the new method of error analysis is proposed and adopted to improve the measurement accuracy of the sensor through the calibration experiment and error processing of the inductance sensor.(2)Taking Basic Visual as the development platform, the host computer program of the system is compiled. Calling Advantech Advantech ActiveDAQ Pro AI control by Visual basic, thermal error measurement subroutine is compiled by the digital acquisition module; by the characteristic of that Visual Basic can call matlab, the voltage values received from the capture card are transformed to thermal deformation and the elimination of gross error is achieved; besides. the function compiles of upper machine software are introduced, including the high-speed real-time data acquisition of thermal deformation, regular set operation, graphical display of data, the realization of data preservation by Visual Basic calling Excel. After this, the standardization, error handling and debugging of Visual Basic software are described.(3)According to the data collected in the experiment, several methods for data processing are proposed, including threshold method based on Fourier transform and frequency selection method. The two methods are compared with the traditional methods, and the advantages and disadvantages of these methods are shown through the experimental data processing. The results shows that, the real-time variation of the thermal deformation of the object to be measured can be obtained by the two methods for the measured data processing.