Research On System Testing Of Micro-nano CMM

The three coordinate measuring machine(CMM)occupies an important position in the field of measurement.With the development of high-precision machining technology,the size of parts is getting smaller and smaller,but the precision requirements are getting higher and higher.So the research of micro-nano CMM has become the research hotspot in many universities and research institutes at home and abroad.According to the requirements of micro-nano coordinate measuring machine measuring environment,a high-precision constant temperature box system is presented.The structure of the box is separated,air in the box is cooled using several power adjustable semiconductor cooling module and two fans control air circulation speed.The high-precision temperature controlled system is based on PID control algorithm.The experimental results show:the temperature variation is 0.03? at the steady state when no hot resource in the box and the frequency of the inverter is 15Hz.The temperature variation is less than 0.1 ? at the steady state when the CMM working and the frequency of the inverter is 50Hz.The dift of x?y?z-axis laser interferometer is 200nm?200nm?250nm when frequency is set 50Hz,the drift of x?y?z-axis laser interferometer is 40nm?20nm?50nm when frequency is set 15Hz.The results shows when the frequency is more high,the precision of temperature controlled is more high.However,owing to the influence of the wind speed,the drift of the laser interferometer will become largeBy using standard gauge blocks,the repeatability experiment,flatness testing experiment,length measurement experiment and step height measurement experiment can be carried out to identify the precision of the micro-nano CMM.It can be obtained from the experimental results that the standard deviation of the repeatability inx?y,z-axis is about 20nm.The deviation and the standard deviation of the flatness measurement results in these directions can also be obtained which are 20nm and 15nm respectively.The length measurement deviation along the direction of the principle axis is about 40nm,and the standard deviation of this index is less than 30nm.The experimental results show that micro-nano CMM do have the measurement precision of nano scale.