A Research Of Measuring Method Of Large Plane's Flatness Based On Liquid Surface

The modern manufacture has a rising requirement of machining accuracy, measurement accuracy is a key that can affect machining accuracy. Flatness is one of the important evaluation indexes of morphology error, in some condition, it has the absolute influence on the workpiece's precision.At present, measurement with high accuracy for small work piece has been perfect, and the main method is light interference method. There are many measuring methods of large plane's flatness, they are level method, since the collimator instrument method, the light axis method, the liquid surface method, error separation with several testheads, table bridge method, and Stride instrument and so on, but not each of them can achieve a high precision. Therefore, this paper proposes a new method of measuring large plane's flatness based on liquid surface。Be different from liquid-surface based on the principle of communicating vessels,this paper take the error separation technique, which uses a high viscosity fluid as a absolute reference, calibrate the system error firstly, and then separate it from the measured value.By this means, after some experiments and simulation analysis, the main factors affecting the measurement precision were found, that were temperature and positioning accuracy, this paper puts forward some corresponding improvement methods to reduce the influence of the two aspects, so as to achieve the purpose of high precision.