Design And Study Of Drilling Fluid Balanced Elliptical Vibrating Screen

The drilling fluid vibrating screen is introduced into the oil extraction industry by mining equipment.In oil drilling operations,vibrating screen is mainly used to remove cuttings and other harmful solid particles in drilling fluid.On the one hand,the machine is required stronger treatment capacity could recycle as much as possible expensive drilling fluid for reusing.On the other hand,it is required to remove the small solid particles in the drilling fluid as much as possible.The working conditions of drilling fluid vibrating screen are severe,and it is subjected to strong high frequency alternating load.So the structure of the sieve box is prone to fatigue and breakage,which will bring great passive influence on the production.As a result of its special vibrating screen mode,the balanced elliptical vibrating screen has the advantages of high screening efficiency and is especially suitable for filtering the fine particles such as drilling mud,so it is favored by the oil drilling industry.However,the current market of mature drilling fluid vibrating screen products are mainly linear vibrating screens,and the existing balanced elliptical screens are generally smaller than linear screens.In this paper,a drilling fluid balance elliptical vibrating screen is designed based on the principal mechanical dynamic theory.(1)The working principle of the balanced elliptical vibrating screen and the reasons for reaching the balanced elliptical are analyzed in detail,which is led by coincidence of force center and centroid.The uniqueness theory of force center is analyzed,which is the key to reach balanced motion.The screen box model is modeled by using CAD 3D modeling software Solidworks.(2)The finite element analysis software Workbench is used to analyze the dynamic characteristics of the screen box of the drilling fluid balanced elliptical vibrating screen.First,modal analysis is carried out to extract the first 8 order modal frequencies and vibration modes.The analysis results present that the working frequencies of the vibrating screen is far away from its natural frequency.And the first 6 orders are rigid body mode whose frequencies are far lower than the working frequency.The second 2 orders are the elastic body mode,and the frequencies are far higher than the working frequency.So the resonance would not be occurred during normal work process of vibrating screen.(3)Dynamic response analysis of vibrating screen is carried out.The static analysis is used to analyze the stress value of the vibrating screen only withstanding gravity and only undertaking most elastic force respectively.The results show that the overall stress of the vibrating screen is very low in two loaded conditions,but the stress of the spring support plate and side wall of side plate are higher.The maximum stress values of the two conditions are much less than the allowable stress.The dynamic characteristics of the screen box are studied by the harmonic response analysis module via the software.The stress,deformation and the vibration trajectory of the screen box under steady operation withstanding inertia force and steady exciting force are obtained.The analysis results indicate that the most of the stress value of the vibrating screen is less than the allowable stress in steady working.And it is vibrating translationally.The elliptical track is well formed.But the stress of the vibrating screen is more than slightly the allowable stress on the motor mounting plate and at the connection point between the rear baffle and the side plate.(4)The above problems are solved by structure improvement then improved model get reanalyzed.The results indicate that the stress environment of the box is obviously improved under the condition that the mass is nearly unchanged.