英语翻译Types of milling machinesThere are several types of mill

英语翻译
Types of milling machines
There are several types of milling employed in industry.They are generally classified based on their construction and design features.They vary from the common general-purpose types to duplicators and machining centers that involve a tool magazine and are capable of carrying out many machining operations with a single workpiece setup.Following is a survey of the milling machine types commonly used in industry.
Plain horizontal milling machine.The construction of the plain horizontal milling machine is very similar to that of the universal milling machine shown in figure 9-43,except that the machine table cannot be swiveled.Plain milling machines usually have column and knee-type construction and also have three table motions,i.e.,longitudinal,transverse,and vertical.As clear in figure 9-43,the milling cutter is mounted on a short arbor,which is,in turn,rigidly supported by the overram of the milling machine.
Universal milling machine.The construction of a universal milling machine is similar to that of the plain milling machine,except that it is more accurate and has sturdier frame,and its table can be swiveled with an angle up to 50°.Universal milling machines are usually equipped with an index or dividing head,which allows cutting of gears and cams,as is discussed later.Figure 9-43 indicates a machine tool of this type.
Vertical milling machine.As the name vertical milling machine suggests,the axis of the spindle that holds the milling cutter is vertical.Table movements are generally similar to those of the plain horizontal milling machines; however,an additional rotary motion is sometimes provided for the table to enable machining helical and circular grooves.The cutters used with vertical milling machines are almost always of the end mill type.Figure 9-44 illustrates the construction and design features of a vertical milling machine.

不同类型的铣床
工业中应用的铣床有几种类型,可根据其结构和设计特点进行大致分类,从普通的多用途铣床到复制机及加工中心,包括多刀刀座,并能用简单的加工设备完成许多加工操作,以下是在工业中普遍应用的铣床类型：水平铣,它与万能铣削的结构非常相似,唯一不同是万能铣削的机床不能在枢轴上转动,如图9-43所示.平铣通常是圆柱形曲片结构,也有三桌式结构,如纵向、横向、纵向的.按图9-43所示,将铣刀安装在一个短的支架上,就这样依次安装,将平铣坚固的支撑起来.
万能铣削,其机器构造与平铣很相似,两者的差异的是万能铣削更精确,结构更坚固,它的桌面能旋转50度.万能铣削通常配备有量度或分度头器,用来削齿轮和凸轮,这在以后还会谈到,图9-43就是这种类型的一种机械工具.
垂直铣床,正如其名字一样,支撑铣刀的轴在坐标轴中是垂直的.其工作台运动与那些水平铣大致相同,然而有时会多一个旋转运动,使桌面能够加工螺旋状和环形的槽,垂直铣床用的切割工具几乎都是立断刀类型的.如图9-44,可以说明垂直铣床的构造及设计特点.