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船舶機電英語（簡體書）
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名人/編輯推薦
《全國船舶工業職業教育教學指導委員會推薦教材?示范性高等職業院校船舶專業英語規劃教材:船舶機電英語》可作為船舶機電專業三年制高職或五年制高職的全日制教材，也可供造船企業、船舶維修及船務公司等相關單位的船員及船機工程技術人員參考使用。
書摘/試閱
Drilling involves producing through or blind holes in a solid metal by a cutting tool, which rotates around its axis, against the workpiece. Drilling operation can be carried out either by hand drill or by drilling machine. Usually, the tool rotates around its spindle while the workpiece is fixed firmly in the latter. Drilling consists of cutting a round hole by means of a rotating drill. The drill can have either one or more cutting edges and corresponding flutes which can be straight or helical. The function of flutes is to provide outlet passages for the chips generated during the drilling operation and also to allow lubricants and coolant to reach cutting edges and the surface being machined. The most common used drills in production are twist drill, core drill, gun drill and spade drill.
The twist drill is a very efficient tool. It is generally formed by forging and twisting grooves in a flat strip of steel or by milling a cylindrical piece of steel, high-speed steel being commonly used. High-speed steel costs more but tools made of it withstand heat much better than those made of ordinary tool steel. The wits drill may be divided into three principal parts:body, shank and point. The flutes are the spiral grooves that are formed on the side of a drill, drills being made with two, three or four flutes. Those having three or four flutes are yes for following smaller drills or for enlarging holes already drilled, and are not suited for drilling into solid struck.
Spiral flutes have four main advantages:
(1) They give the correct rake to the lip of a drill;
(2)They cause the chip to curl so tightly that it occupies the minimum amount of space ;
(3) They form channels through which chips escape from the hole;
(4) They allow the lubricant to flow easily down to the cutting edge.
