Experimental Study Of Gas Hydrostatic Bearing Vibration Pneumatic Hammer Mechanism Analysis

The aerostatic bearing is of its substantially low friction loss and heat generation, which significantly decreased the effect of the friction and hot deformation on the precision error. As a result, the bearing, achieving the nanometer lever of motion precision, widely applied to Precision/Ultra-Precision Motion Stages as a means of mainstream bearing. Nevertheless, vibrations induced by gas flowing in the aerostatic bearing can still not be ignored, and especially the pneumatic hammer, directly bringing on aerostatic bearing losing function and not working, has become one of the major facts, which limits further improvement of the capacity load,stiffness and precision. This article is just developed around the advanced problem, aiming to further investigate the pneumatic hammer of the essence and how to restrain it by the combinational methods of simulation and experiment. The content and achievement of this article are as follows.(1)A3D aerostatic and gas film mechanical physical model is built by applying the gas lubrication theory. The simulation results indicate that the accuracy of the proposed model not only has much been improved, but also has obtained the microcosmic characteristic and more exactly distributing rule of3D flow field, comparing to that of the existing2D model, in order to supply flow field parameters for establishing pneumatic hammer model.(2)A mathematic model of the pneumatic hammer has been established by combining systemic dynamics and kinematics. The intrinsic relationship between the parameters of aerostatic bearing and pneumatic hammer has been studied by using simulation. The laws of the influence of the parameters on the pneumatic hammer are revealed.(3)It is studied an interior disturbance that is the vortex by simulation, and obtains the relationship of the effect on the gas supply pressure, gas film, recess shapes and its structure parameters. It is clarified that the vortex, as the interior disturbance, brings forth fluid-structure coupling, causing gas bearings support to produce sympathetic vibration, and places a premium on the pneumatic hammer.(4)The laws between the parameters of aerostatic bearing and pneumatic hammer are validated by the self-designed experimental platform. It is clear that the pressure fluctuation of gas film brings on the sympathetic vibration, and then the pneumatic hammer occurs. Moreover, it is greatly explored the pneumatic hammer mechanism, and a method how to avoid the pneumatic hammer is proposed.In general, the pneumatic hammer mechanism of aerostatic bearing is revealed, and the laws of the influence of process and structure parameters of aerostatic bearing on the vortex and pneumatic hammer are clarified, and an effectual method to suppress the vortex and control the pneumatic hammer is proposed. Therefore, the research results are validated to provide a significant theoretical basis for the design and manufacturing of the precision/ultra-precision aerostatic bearing.