Development Of The Special Caliber Dimming Sytem And Its Experimental Study

A special caliber dimming system with the maximum masking aperture ofФ300mm and the minimum ofФ50mm was developed in this paper. The experimental test indicated that the dimming system has a good smoothness of operation, meeting for the design requirements. It provided a good design guideline and theoretical foundation for the similar system in related fields.In this paper, the integrated design of the dimming system was implemented, it mainly includes the design of iris blade, wire race ball bearing and drive system, in addition, the simulation analysis and the experimental tests were also studied.Firstly, as one of the key components the iris blade was designed. In order to avoid the influence of process error and installation error, prevent the iris blades slipped from the groove in the flexible ring during the swing motion, correction computation for both the movable pin and fixed pin was carried out, the correction results show that the relative error is less than 5%.Secondly, By using of K.L.Johnson's contact mechanics theories, the relationship between friction and preload force, preload distance was deduced, and finally calculated the value of friction between rolling element and wire race. Furthermore, according to Hertz's contact theories, the analysis of contact parameters was developed, the contact size, contact deformation and maximum contact stress was calculated, the specific contact parameter was obtained. It laid the theoretical foundation for the design of wire race ball bearing.Thirdly, the analysis and simulation of deformation of the key mirror cylinder was carried out, the simulation results show that the maximum displacement is 0.7μm, after mesh densification the maximum relative error is about 2.6%. Furthermore, the modal analysis of the iris blade was also studied, it shows that the first 5 natural frequencies are obviously different, there're no intensive or reaped roots. By the point of structural dynamics, the design of the structure of the iris blade is reasonable.Finally, the experiment of the dimming system was investigated. For the worm drive system, in order to achieve a high-accuracy of mesh, a running-in experiment was carried out, through the experiment, a better running smoothness and less vibration is not only achieved, but also indicated that the worm drive system meets the operating requirements. Furthermore, the friction moment was measured by means of counterbalance force, contrasting to theoretical value, the maximum error is 12.41% while the minimum is about 4.02%.For the investigation of the special caliber dimming system, a detailed discuss or deduce had been given from the theories to experiment research, it provided a good design example for the research of the large caliber dimming system,...