【正文】 這種銑刀的側(cè)面呈盤狀，有間隙，可以防止粘連。錯齒銑刀是較薄的圓柱形銑刀，刀上有相互交錯的刀齒，相鄰刀齒具有相反的螺旋角。側(cè)刃銑刀的刀齒既可以是直線的，也可以是螺旋形的，這種銑刀一般較窄小，具有盤形的形狀。它們可以用來銑削平面，這種銑削稱做平面銑削。平面銑刀通常用螺栓固定在刀軸 的末端上。這種類型的銑刀僅需磨削齒的前刀面就可以變得鋒利，只要切削刃的外形保持不變。如果工件表面堅(jiān)硬，像鑄件，就會使刀齒迅速地變鈍。因?yàn)樵阢姷督Y(jié)束切削時，處于切線方向的被切材料發(fā)生屈服，所以與逆銑相比，順銑的被加工表面沒有什么切痕。此外，銑削表面的平整度主要取決于切削刃的鋒利程度。應(yīng)注意，在逆銑時，銑刀旋轉(zhuǎn)方向與工件進(jìn)給方 向相反，而在順銑時銑刀旋轉(zhuǎn)與工件進(jìn)給方向相同。，被加工平面是刀具位于周邊和端面的齒綜合作用形成的。 銑削操作類型：銑削操作可以分成兩大種類，每一類又有多種類型。由于銑削切削金屬速度很快，并且能產(chǎn)生良好的表面光潔度，故特別適合大規(guī)模生產(chǎn)加工。在大多數(shù)情況下，使用多齒刀具，金屬切削量大，只需一次銑削就可以獲得所期望的表面。一些老式的或價廉的車床為了能夠得到所有的進(jìn)給量和加工出所有螺紋，必須更換主軸和變速齒輪箱之間的齒輪系中的一個或兩個齒輪。 現(xiàn)代車床有一個變速齒輪箱，齒輪箱的輸入端由車床主軸通過合適的齒輪傳動來驅(qū)動。光杠通過摩擦離合器驅(qū)動拖板移動，離合器可能會 產(chǎn)生打滑現(xiàn)象。光杠上有一個幾乎貫穿于整個光杠的鍵槽，光杠通過兩個轉(zhuǎn)向相反并用鍵連接的錐齒輪傳遞動力。溜板箱裝在大拖板前面，通過溜板箱內(nèi)的機(jī)械裝置可以手動和動力驅(qū)動大拖板以及動力驅(qū)動橫拖板。大拖板上有橫向?qū)к?，使橫向拖板可以安裝在上面，并通過絲杠使其運(yùn)動，絲杠由一個小手柄和刻度盤控制。通常在活動套筒的外表面刻有幾英寸長的刻度，以控制尾座的前后移動。尾座安裝在底座上，可以沿鍵槽在底座上橫向移動，使尾座與主軸箱中的主軸對中并為切削圓錐體提供方便。主軸由電動機(jī)經(jīng) V 帶或無聲鏈裝置提供動力。 主軸的內(nèi)端從主軸箱中凸出，其上可以安裝多種卡盤、花盤和擋塊。目前發(fā)展的趨勢是通過電氣的或機(jī)械的裝置進(jìn)行無級變速。它提供動力，使工件在 各種速度下旋轉(zhuǎn)。同樣地，在操作中應(yīng)該小心，以避免損傷導(dǎo)軌。它通常是由經(jīng)過充分正火或時效處理的灰鑄鐵或者球墨鑄鐵制 成，它是一個堅(jiān)固的剛性框架，所有其他主要部件都安裝在床身上。這種車床可以控制工具的機(jī)械進(jìn)給。這就是在生產(chǎn)中普遍使用各種車床比其他種類的機(jī)床都要多的原因。 MILLING A shop that is equipped with a milling machine and an engine lathe can machine almost any type of product of suitable size. The basic machines that are designed primarily to do turning， facing and boring are called lathes. Very little turning is done on other types of machine tools， and none can do it with equal facility. Because lathe can do boring， facing， drilling， and reaming in addition to turning， their versatility permits several operations to be performed with a single setup of the workpiece. This accounts for the fact that lathes of various types are more widely used in manufacturing than any other machine tool. Lathes in various forms have existed for more than two thousand years. Modern lathes date from about 1797， when Henry Maudsley developed one with a leads crew. It provided controlled， mechanical feed of the tool. This ingenious Englishman also developed a change gear system that could connect the motions of the spindle and leadscrew and thus enable threads to be cut. Lathe Construction. The essential ponents of a lathe are depicted in the block diagram of picture. These are the bed， headstock assembly， tailstock assembly，carriage assembly， quickchange gearbox， and the leadscrew and feed rod. The bed is the back bone of a lathe. It usually is made of wellnormalized or aged gray or nodular cast iron and provides a heavy， rigid frame on which all the other basic ponents are mounted. Two sets of parallel， longitudinal ways， inner and outer， are contained on the bed， usually on the upper side. Some makers use an inverted Vshape for all four ways， whereas others utilize one inverted V and one flat way in one or both sets. Because several other ponents are mounted and/or move on the ways they must be made with precision to assure accuracy of alignment. Similarly， proper precaution should betaken in operating a lathe to assure that the ways are not damaged. Any inaccuracy in them usually means that the accuracy of the entire lathe is destroyed. The ways on most modern lathes are surface hardened to offer greater resistance to wear and abrasion. The headstock is mounted in a fixed position on the inner ways at one end of the lathe bed. It provides a powered means of rotating the work at various speeds. It consists， essentially， of a hollow spindle， mounted in accurate bearings， and a set of transmission gears——similar to a truck transmission——through which the spindle can be rotated at a number of speeds. Most lathes provide from eight to eighteen speeds， usually in a geometric ratio， and on modern lathes all the speeds can be obtained merely by moving from two to four levers. An increasing trend is to provide a continuously variable speed range through electrical or mechanical drives. Because the accuracy of a lathe is greatly dependent on the spindle， it is of heavy construction and mounted in heavy bearings， usually preloaded tapered roller or ball types. A long itudinal hole extends throu