| The screen is an important component parts on the shale shaker and is one consumables of drilling, it is always in direct contact and interact with the drilling fluid in the working process of the shale shaker, and its actual modal trajectory, static or dynamic characteristics ultimately determines the cuttings sieving particle size, velocity, cutting removal rate and the amount of liquid handling. As technology advances, the screen manufacturing technology has been gradually improved, richer design, installation method is more convenient and reliable, but the research for the new screen and the new method of installation for screen is incomplete or even missing in recent years. Therefore, in addition to continue to study for the structure and the mechanism of the shale shaker, also the need for the dynamic characteristics of the different types of screens installed in different ways under the more in-depth research, it is benefit for improving the life of the screen and provideing the basis for design and improvement of the installation device of screen.This article researchs the screen from the following five aspects.1. Summarized the development history and status of the research related to the screen, the weaving ways of the screens which are widely used in the market and the existing standard at home and abroad by refering to the literature. Analysed different types of screen structural features, applications and installation methods.2. The free vibration equation of ordinary flexible screen is deduced, and got the calculation formula of the natural frequencies of each suppot. Elastic support multi-span continuous unidirectional rectangular plate model which is simplified by the using the bolt tightening method of the flat-screen installation model has been proposed, derived the transfer function of the entire screen by using the transfer matrix method, and got the free vibration frequency equation of screen according to the boundary conditions. Numerical solution for free vibration characteristic equation has been conducted on a version of flat-screen to obtain the natural frequency with different magnitude of bolt preload and different numbers and stiffness of rubber support bar. Date analysis shows that these three parameters are positively correlated with the natural frequency of the screen, and have effects on each other. The modal simulation analysis is carried out on the two different types of frame screen, and obtained the top ten natural frequencies and mode shapes of screen.3. The dynamic equations of the two-motor linear and three-motor oval shale shaker are established, and solved its steady-state solution; the development stages of the rigid-flexible coupling multi-body dynamic are summarized, briefly introduced the RecurDyn which is a dynamics simulation software, and compared to two kinds of typical modeling method for flexible body, obtained the modeling process of each method.4. In order to study the forced vibration response of the screen under the effect of vibration force from the motor, a multi-body simulation model of three-motor shale shaker is established and validated in RecurDyn, based on the finite element multi-flexible-body dynamics (MFBD) technology, on the basis of rigid model to establish the rigid-flexible coupling multi-body dynamic simulation model which is between shale shaker and screen, After the simulation analysis, through compared and anlysed the vibration parameters,the dynamic stress of measured points and the stress nephogram of screen which is under the different models, places of screen, bolt preload, degree of compaction, square tube arrangement methods, vibration trajectories, support conditions and vibration force, the performance characteristics of screen is obtained under each installation method, summarized the advantages and disadvantages of different installation method from the kinetic point of view. This kind of simulation method can provide reference databases for structural design, installation method and the evaluation of fatigue damage of the screen. In addition, the vibration accelerations of the dual-motor linear shaker screen box and the flat screen which is installed by using the bolts tightened are tested,not only validated the simulation model again but also studied the effect of bolt on the throwing index of screen by analyzed data.5. Proposed a new method to install the screen, and the device is initially designed, modal analysis for the spindle that it proved this device can be installed on screen box to work together with the shaker. Carried on the forced vibration simulation analysis for the screen which is installed using the new device. the results show that this kind of installation method can guarantee the life of the screen at the same time has a high throw an ideal index. |
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