【正文】 ometry: , , machines, and machines. The frinding process forms chips, but the geometry of the barasive grain is uncontrollable. The amount and rate of material removed by the various machining processes may be large, as in heavy truning operations, or extremely small, as in lapping or superfinishing operations where only the high spots of a surface are removed. A machine tool performs three major functions: rigidly supports the workpiece or its holder and the cutting tool。 together they are driven by a driver p。 namely, rough boring and finish boring. The objective of the roughboring operation is to remove the excess metal rapidly and efficiently, and the objective of the finishboring operation is to obtain the desired size, surface finish, and location of the hole. The size of the hole is obtained by using the trialcut procedure. The diameter of the hole can be measured with inside calipers and outside micrometer calipers. Basic Measuring Insteruments, or inside micrometer calipers can be used to measure the diameter directly. Cored holes and drilled holes are sometimes eccentric wwith respect to the rotation of the lathe. When the boring tool enters the work, the boring bar will take a deeper cut on one side of the hole than on the other, and will deflect more when taking this deeper cut,with the result that the bored hole will not be concentric with the rotation of the work. This effect is corrected by taking several cuts through the hole using a shallow depth of cut. Each succeeding shallow cut causes the resulting hole to be more concentric than it was with the previous cut. Before the final, finish cut is taken, the hole should be concentric with the rotation of the work in order to make certain that the finished hole will be accurately located. Shoulders, grooves, contours, tapers, and threads are bored inside of holes. Internal grooves are cut using a tool that is similar to an external grooving tool. The procedure for boring internal shoulders is very similar to the procedure for turning shoulders are faced with the boring tool positioned with the nose leading, and using the cross slide to feed the tool. Internal contours can be machined using a tracing attachment on a lathe. The tracing attachment is mounted on the cross slide and the stylus follows the outline of the master profile plate. This causes the cutting tool to move in a path corresponding to the profile of the master profile plate. Thus, the profile on the master profile plate is reproduced inside the bore. The master profile plate is accurately mounted on a special slide which can be precisely adjusted in two dirctions, in two directionsm, in order to align the cutting tool in the correct relationship to the work. This lathe has a camlick type of spindle nose which permits it to take a cut when rotating in either direction. Normal turning cuts are taken with the spindle rotating counterclockwise. Thie boring cut is taken with the spindle revolving in a clockwise direction, or “backwards”. This permits the boring cut to be taken on the “back side” of the bore which is easier to see from the operator’sposition in front of the lathe. This should not be done on lathes having a threaded spindle nose because the cutting force will tend to unscrew the chuck. 中文翻譯 振動的定義和術語 振動 所有的物質 固體，液體和氣體 都能夠振動，例如，在噴氣發(fā)動機尾部導管中產生的氣體振動會發(fā)出令人討厭的噪聲，而且有時還會使金屬產生疲勞裂縫。一臺常見的機器中有許多運動零件，每個 零件都是潛在的振動源或沖擊激振源。 一個物體或一種材料在振動時，它相對于靜平衡位置的位置變化或位移是周期性的。 瞬態(tài)振動 是逐漸衰減的，而且通常與不規(guī)則的擾動有關，例如，滾動載荷通過橋梁，汽車通過坑洞，也就是在確定的期間內不重復的力。由于需要能量才能產生振動，因此，振動消耗了能量，降低了機器和機構的效率。也就是說，這種振動不是周期性變化的，是不定期地進行重復的。在任何一個周期內所完成的運動，被子稱為一個循環(huán)。 自由振動和強迫振動 。 強迫振動是在外力的 激勵（或者外部的振蕩性干擾）下產生的。也就是說，強迫振動的頻率是一個與系統(tǒng)固有頻率沒有關系的任意量。在這種臨界條件下，機械系統(tǒng)中出現(xiàn)具有危險性的在振幅和高應力。阻尼是振動系統(tǒng)中能量被消耗的現(xiàn)象，它可以防止過量的響應。例如，在結構中，材料內部的磨擦和由空氣可液體阻力等造成的外部磨擦被稱為“粘性”阻尼，在這里假定阻力與運動部件之間的速度成正比。 基本的加工工序和機床 基本的加工工序 機床是從早期的埃及人的腳踏動力車床和約翰切屑是廢棄的產品，與其工件相比相當短但是比未切屑的部分有相對的增加。如果以類似的方式加工一根空心管的內部，則這道工序就叫鏜削。 常常需要的是平坦的或平的表面。大一些的工作很容易保持刀具固定不動，而像龍門刨削那樣在其下面拉動工件，在每次往復時進給刀具。不管是鉆頭轉動還是工件旋轉，切削刃與工件之間的相 對運動是一個重要因數(shù)。 基本的機床 機床用于以切屑的形式從韌性材料上去除金屬來加工特殊幾何形狀和精密尺寸的部件。例如：鏜削是內部的車削；鉸削、錐體車削和平底锪孔則修改鉆孔，與鉆削有關；滾齒與切齒是基本銑削作業(yè)；弓鋸削和拉削是刨削和珩磨的一種形式；而研磨、超精加工、拋光和磨光則是磨削和研磨切屑作業(yè)的各種變化形式。 機床完成 3 種主要功能 ： ； 與切削刀具之間的相對運動； ，通常每種情況有4～ 32 種選擇。它們都影響切削力、功率和對金屬切削的速率。 切削 在普通車床上完成的基本車削工序，那些在外表面上用單刃刀具完成的工序叫車削。精加工工序用以獲得工件最終的大小、形狀和表面光潔度。與尾架鄰近的工件端部總是由尾架頂尖支承，而挨著主軸箱的一端則由主軸箱頂尖支承或裝在卡盤內。 通過將工件支承在兩個頂尖之間可以獲得非常精密的結果。在工件由于任何原因被從車床上拆下后，頂尖孔可以精確地將工件裝回車床或另一臺車床，或都裝在一臺外圓磨床上。幾乎被獨自用在大量生產工件上的補償或浮動爪式卡盤是上述的一個例外。 鏜削 鏜削工序一般分兩步完成，即粗鏜 和精鏜。測量儀表或內千分卡尺可用于直接測量直徑。因為每個淺切口使形成的孔比使用先前切口形成的孔更加同心。鏜削內槽的步驟非常類似于肩部的步驟。這使刀具對應于標準剖面樣板的輪廓線的路徑進行移動。正常的車削世削是在主軸逆時針轉動時進行的；鏜削切削是在主軸順時針方向或“向后”轉動時進行的