礦物加工外文翻譯-wenkub
2022-12-17 03:29:03 本頁面
【正文】 en length .A lower throwing index and material delivery velocity near the discharge end causes the material to stay longer on the screen and encourages more plete peration of the mesh. Two methods are currently used to improve screening efficiency [7– 8].The first is to add material to the screen from multiple feed ports. This is troublesome in practical use especially in terms of controlling the distribution of differently granulated materials .Hence it is rarely used in practical production. The second way is to adopt new screening equipment like, for example, a constant thickness screen. The motion of the new screen surface causes material to maintain the same, or an increased, thickness .It achieves a rather more ideal motion. The main problem with the constant thickness screen is that it covers a bigger area and that the structure is plicated and hard to maintain .A simple structure with good screening efficiency is still a necessity. We have designed a new vibration screen with a variable elliptical trace that is based upon an ideal screen motion for use in raw coal classification. The size of the vibrating screen is m m,the feed granularity is 0 to 50 mm and the classification granularity is vibrating screens bine the basic advantages of both circular and linear vibrating screens [9– 10].The long axis of the ellipse determines material delivery and the short axis influences material loosening, to be exact. 3 Dynamics model analysis of vibrating screen with variable elliptical trace We made the exciting force deviate from the center of gravity,to change the motion pattern of the new vibrating stiffness matrix of the vibration isolation 4 spring was not zero under these circumstances and the vibrating system had multiple degrees of transverse wagging was neglected to simplify the motion was considered to be a linear vibration of a rigid beam in the longitudinally symmetrical each point the vibration is a bination of the translation of the center of gravity and the screen pitching about the center of studies neglected the influence of elastic forces in the horizontal and vertical direction on the swing of the vibrating screen [3,11].An accurate dynamic model consisting of three differential equations that include coupling of degrees of freedom in the vertical,horizontal and swing directions is proposed. The mathematical model of the vibrating screen is shown in center of gravity, is taken as the origin of a rectangular coordinate system at static equilibrium, in accordance with rigid motion on the plane [12].Simultaneous differential equations in generalized coordinates using center of gravity coordinates,(x,y),and the swing declination angle, θ ,may be written as 5 where M is the mass of the vibrating screen’s the moment of inertia of M relative to the center of gravity,O。screening process with constant bed thickness。 dynamic model。x and y the displacements in the x and y0directionas。fx,f yond father damping coefficients in the x,y and directions。 and,βthe included angle between the l and x directions. The damping force is rather small and can be neglected. Then Eq. (1) can be simplified to Eq.(2). 4 Motion and screening effect analysis of a vibrating screen with variable elliptical trace Analysis of the motion parameters Multiple degreeoffreedom vibration theory was used to find a stable solution for the
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