| The three-dimensional precision measurement technology is developed in the late 1960s, because of the continuous improvement of product quality and the processing technology of complex surface. Besides, it also benefits to the development of electronic technology, computer technology and precision machining technology which provide the technical support. This paper is aimed at the requirements of engineering application of the 3D precision measurement, and taking the 2D gantry precision air bearing stage as the research object. By focusing on the static characteristics, dynamic characteristics and motion precision of the air bearing stage, a 3D precision measuring air bearing stage which has the characteristics of high precision, good stiffness, large travel and wide application range is designed. Moreover, the static and dynamic characteristics of the air bearing stage are verified by the thesis. The specific research works include the following aspects:Firstly, the gas film stiffness of the air bearing slider is studied by the static analysis. From studying the main relative factors which affect the gas film stiffness of the air bearing slider, the distribution of influence factors are acquired. It includes the theoretical calculation, simulation analysis and experimental testing three aspects. At the same time, the straightness of air bearing slider is tested under different air supply pressure. By considering the difference of gas film stiffness in serious position of the air bearing slider, the change regularities of the straightness is obtained.Secondly, it can be seen from the simulation analysis of the dynamic characteristics of the 2D gantry air bearing stage that the structure which is the most prone to resonance and produces large amplitude is the beam. According to the natural frequency testing of the beam, the frequency-amplitude curve provides reference for the design of 3D precision measurement air bearing stage. In addition, the positioning and repositioning accuracy of the air bearing slider is studied from kinematics, and the influence of the gas pressure is acquired by adjusting the gas supply pressure.Based on the above researches, the technical and dimension parameters of the 3D air bearing stage are determined by the requirements of the precision measurement and objects. Then the overall design of the air bearing stage is completed. After the servo feed mode is determined, the servo feed system of each moving axis is calculated. Under the premise of ensuring the movement accuracy of the air bearing stage, the range of speed of motion axes is determined.At the end of this article, the static and dynamic characteristics of the 3D precision measurement air bearing stage is researched. From the analysis of the theory of the gantry structure deflection calculation, the static analysis of finite element of the stage is carried out, then the structural deformation and stress distribution can be gained. So the paper put forward a method to improve the structure of the beam. Through the dynamic characteristics, the modal and harmonic response analysis of the air bearing stage are carried out. So the natural frequency distribution, corresponding vibration mode and the dynamic response can be achieved. In practical engineering application, the resonance zone can be avoided by increasing the damping and stiffness of the structure. Then the measurement accuracy and reliability of the 3D measurement can be ensured. |
PDF Full Text Request