英语翻译Core drills .A core drill consists of the chamfer ,body

英语翻译
Core drills .A core drill consists of the chamfer ,body ,neck ,and shank ,as shown in fig.12.2.This type of drill may have either three or four flutes and an equal number of margins ,which ensure superior guidance ,thus resulting in high machining accuracy .It can also be seen in fig.12.2that a core drill has flat end .The chamfer can have three or four cutting edges or lips ,and the lip angle may vary between 90 and 120 .Core drills are employed for enlarging previously made holes and not for originating holes .This type of drills is characterized by greater productivity ,high machining accuracy ,and superior quality of the drilled surfaces .
Gun drills .Gun drills are used for drilling deep holes .all gun drills are straight-fluted ,and each has a single cutting edge .A hole in the body acts as a conduit to transmit coolant under considerable pressure to the tip of the drill .
There are two kinds of gun drills ,namely ,the center-cut gun drill used for drill blind holes and the trepanning drill .The latter has a cylindrical groove at its center ,thus generating a solid core ,which guides the tool as it proceeds during the drilling operation .
Spade drills .Spade drills are used for drilling large holes of 3.5 in.(90mm) or more .Their design results in a marked saving in cost of the tool as well as a tangible reduction in its weight which facilitates its handling.Moreover ,this type of drill is easy to be ground .
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核心训练.一个钻孔机由槽、身体、颈部,如图fig.12.2.这种类型的钻探可能或三个或四个长笛和数量相等的边缘,以确保优越的指导,从而导致加工精度高.它也可以看到fig.12.2that一个钻孔机已经平结束.这个槽能有三个或四个切削刃或嘴唇,唇间的不同角度可以90点,120.为了扩大就业核心训练之前,不是来源于洞孔.这种类型的演练的特点是生产力,加工精度高、优质的钻孔的表面.
枪钻.枪钻用于钻深孔钻是straight-fluted本土人枪,每个人都有一个单一的先锋.一个洞的身体作为冷却水管传送到相当大的压力下的演习.
有两种枪钻,即center-cut枪钻用于钻盲孔、行演练.后者有圆柱状沟在它的中心,从而产生一个坚实的核心,它能引导工具作为它的收益在钻井作业.
铲演习.铲练习是用于钻井大洞.(90mm 3.5)或更多.他们在一个显著节能设计成果的成本的工具,以及一个有形的降低它的重量,便于操控性.而且,这种类型的训练是很容易被磨.