礦物加工外文翻譯-文庫吧
2024-11-16 03:29 本頁面
【正文】 increase .Thus ,the screening efficiency declines dramatically .The material granularity simultaneously bees uniform and the energy imparted from the vibrations to the material suffers little loss .Hence ,the amplitude and velocity of the material particles increase .This causes the material bed depth at the feed end to be thick while at the discharge end it is Thin .This kind of motion leads to an asymmetrical peration along the screen surface,which influences the screening efficiency and processing capability [6].Common screening characteristics are shown in . 3 Ideal motion for screen surface and implementing scheme The ideal motion for screen surface is described below, according to the principle of screening process with constant bed thickness .The feed end of the screen has a bigger throwing index and a higher material delivery velocity ,which makes bulk material quickly perate and causes rapid delaminating. Earlier lamination of material increases the probability of finegrained material passing through the mesh .The screen has an appropriate throwing index and a little higher material delivery velocity in its middle part .This is of benefit for stabilizing finegrained materials and for perating uniformly along the screen 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 t
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