In order to realize the efficient and rapid erection and flexible unfolding of super large active array meter wave radar with an area of more than 100 square meters, this study takes a meter wave radar antenna array unfolding and retracting system as the research object, makes a detailed structural design of the unfolding and retracting system, and establishes a three-dimensional model of the unfolding and retracting system on this basis to to Simulate the stiffness and strength of it. The changes of stiffness and strength of the array under different wind loads and wind angles are compared and analyzed. The results show that the unfolding and retracting system has high reliability under the condition of rapid erection and mobility, and has a good application and popularization prospect in the automatic unfolding and retracting system of super large radar array.
As the rapid development of equipment for aerospace, national defense, biological engineering and precision machinery, traditional milling is gradually difficult to satisfy the growing demand for accuracy and machining surface quality. It is an effective method to introduce ultrasonic vibration into milling processing. Ultrasonic vibration assisted milling(UVAM) has been widely studied recent years for its extensive adaptability on materials, good cutting effect, high efficiency, long cutting life, et al. And it is an emerging trend to obtain biomimetic surface texture and certain surface performance by UVAM. In this paper, the characteristics of squamous surface and ultrasonic vibration assisted milling surface are analyzed and discussed. Ultrasonic vibration assisted milling surface is formed by tool tip path and influenced by vibration frequency and amplitude, cutting tool diameter, feed speed, spindle speed, spindle rotation accuracy, etc. The squamous surface feature is extracted based on image processing and compared with ultrasonic vibration assisted milling surfaces. The results show that the feature curves of squamous surface can be regarded as the same type of function curve with tool tip trajectories. The spindle precision only plays a role in surface features distribution uniformity during UVAM. Squamous surface shall be obtained by UVAM with certain vibration and machining parameters. It is concluded that UVAM is suitable for machining squamous surface, which is helpful to guide practical UVAM for machining biomimetic surface.
A lifting electrical push rod mechanism which is suitable for the upper load pitch lifting has been designed based on a particular mobile radar in this paper. Through the theoretical modeling analysis of the lifting force of the electric actuator and the stability of the screw during the whole Lifting process, this article aims to investigate the influence of the compound load on the force and stability of the push rod during the lifting process of the screw, and to verify the accuracy of the calculation results by combination with the actual measurement results. The research results show that: in the lifting process of the upper load from the lifting angle 0 to 90°, the self-weight moment of the upper load is the main influencing factor of the force on the electric push rod, and in the lifting process, the maximum force on the electric push rod appears in the middle state of the lifting process, the lifting angle with the most dangerous screw stability coefficient and the position of the maximum force on the screw do not overlap. In the lifting process, the measured results and the theoretical calculation values are in good agreement, which proves the accuracy of the calculation model and method.
The formation mechanism of surface texture for feed-direction ultrasonic vibration−assisted milling (UVAM) was investigated in this study by establishing a kinematic model and a pressing model of UVAM. The kinematic model showed that the cutter tip, which was supposed to be totally sharp, produced closed scratches by crossed trajectories. The variation trends of the interval for closed textures were of sine function. A comparative experiment was carried out by UVAM and conventional milling. A dividing line close to the X coordinate divides the surface feature into two parts. The pressing model showed that the tool minor cutting edge left clear traces with certain width because of the tool minor cutting edge angle. Scratches by tool minor cutting edge were intermittent and regularly varied when feed-direction vibration was introduced. All the surface feature changes are in the radial direction and the trajectory intersections shall always be the scratch grooves or ridges. The ratio between ultrasonic vibration frequency and spindle speed, tool radius, and the located cutter rotation angle affected the changing rule of scratches by tool minor cutting edge. The analytical models and the experimental results proved to each other reasonable.
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