圓振動篩設(shè)計的外文翻譯-文庫吧
2025-04-17 14:41 本頁面
【正文】 tion is producedby eccentrics。 by unbalanced weight。 by cams or bumpers. They can also be subdivided as inclined and horizontal. Sizes Vibrating screens are made in standard sizes of from 12 in. to 10 ft wide and from 2 1/2 ft to 28 ft long. Common practice dictates that the length of the screen should be times the width for dry screening. For wet screening, wider and shorter screen is best. Screens for scalping ahead of primary crushers, operate at a slope of from 12 degrees to 18 degrees and have openings as large as 11in. square. The eccentric throw for openings from 5 to 11 in. is usually 1/2 in.。 for openings from 3 to 5 in. about 3/8 in.。 and for smaller openings 1/4 in. The screening surface consists of a heavy cast desk, perforated steel with or without skid bars welded between the holes, rod deck, etc. The mechanical shaking screen prises a rectangular frame, with perforated steel or wire cloth screening medium. It is usually inclined and suspended on loose rods or cables. These screens now are used mainly for special tasks of coarse screening, having given way to vibrating screens. ElectricallyHeated Screens Electrically heated screen cloth decks have afforded better screening and less dust. Modern or updated screening operations, now handling clays, limestone, potash, salts, phosphates and various hydroscopic materials, report minimum dust loss when equipped with heated screens. The controlling factor in this improvement is the electricallyheated screen doth deck. Any vibratory screen with fine opening (less than 1/2 in.) can be equipped with low voltagehigh amperage resistance heating. The principle of electric heating is based on the fact that small diameter wire of screen cloth (especially stainless steel) serves as a conductor, but offers resistance to a highamperage current. This resistance causes heating of the wire when powerful transformer and specially designed bus bars connected to screen doth decks push up to 6,000 amps current into a circuit. The current is safe and shockproof because voltage is low, ranging from approximately 1 1/2 to 16 volts. Workers can do their jobs around electricallyheated screens without special precautions. Heated screens are effective in preventing moisture content of material from causing buildup and blinding. The screen wire is kept at 100 degrees to 130 degrees F depending on character and tonnage of the material processed. This temperature is not high enough to weaken the wire cloth or screen structure, nor does it suffice to drive off moisture held in material. The warm wire stays dry, breaking the surface tension that otherwise would bind damp material to cold, damp metal. This differential or 遼寧科技大學本科生畢業(yè)設(shè)計 第 3 頁
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