【正文】 以根據(jù)下列工藝 方法進行，如圖 8所示，在彎曲模具中產生的零件也可以通過等同回彈角度彎曲模上挖凹?；驈椥跃彌_式彎曲模而被過度彎曲來減少或消除回彈。 圖 8 減少或消除回彈的方法 從應用角度來說，有許多類型的壓力機，諸如：閉式雙點偏心軸單動機械壓力機，沖壓成形機，液壓成形壓力機，液壓機，彎板機，三動式壓力機，沖?；剞D壓力機，雙點壓力機，雙邊齒輪驅動壓力機，雙點單動壓力機，臺式壓力機，切邊壓力機，閉式單動（曲柄）壓力機，肘桿式壓力機，單點單動壓力機，開式雙柱可傾壓力機，開式壓力機，四點式壓力機，四曲柄壓力機，飛輪式螺旋壓力機， 摩擦傳動螺旋壓力機，閉式雙點單動雙曲柄壓力機，搖臂式壓力機螺旋式壓力機和上傳動板料沖壓自動壓力機等。 雙動式壓力機是用于鈑金零件的拉深加工。此種類型的壓力機有一個外滑塊（壓邊圈），并且有一個切斷的內滑塊（沖頭夾緊器）。在加工工作循環(huán)期間，壓邊圈首先與零件接觸，然后施加壓力使沖頭夾緊器進行適當零件拉深（見圖 9）。 圖 9 典型通用壓力機 三動式壓力機具有和雙動式壓力機相同的內、外滑塊。另外，三動式壓力機床身還有另一個滑塊，它可向上運動，從而在一個沖壓循環(huán)中實現(xiàn)反向拉伸。三動式壓力機應用不是很廣泛。 肘桿式壓 力機是用于壓印加工。這裝置的設計是在沖壓行程的末端以很高壓力。此種壓力機利用一個曲柄（曲柄帶動違節(jié)運動，連節(jié)是由兩個在上死點到下死點之間進行擺動的連桿組成，連桿擺動時間很短）．在臨近沖程底部時慢速移動的滑塊具有功率很大的短距離位移。液壓機主要是用于成形加工工序中，相比大多散機械式壓力機，它有一個比較長的工作周期。液壓機的優(yōu)點足工作壓力、沖程和滑塊的速度均是可調的（見圖 10）。 圖 10 典型液壓機 液壓機屬于壓力限定型的成形機械，液壓機的主要用途體現(xiàn)在沿滑塊路徑外力是必須保持恒定或處于精確攤制鋒成形技術領 域中?；钊c液壓缸的驅動機構是用線性方式實現(xiàn)的，并且直接．連接到滑塊。液壓機框架結構的形式是非常類似于機械式力機。液壓驅動裝置易于安裝在機械框架結構中。因此幾種液壓機驅動很容易就被制成復雜成形與切斷加工（拉深、擠壓、切斷、模鍛等）的單一機械，并且所要求的運動可以容易地定位，彎扳機除了它的長床身之外基本是與開式壓力機棚同的，床身長度可為 6～ 20 英尺 (～ 6 米 )或更長，它基本上是用在尺寸大的鈑金零件上的各種類型的彎曲加工成形，它也可以使用不同整套的刀具分別進行淺沖孔、切口與成形（見圖 11）。這就可以使零件僅 通過把復雜的零件分成幾個簡單的加工工序實現(xiàn)由復雜設計到精確制造的過程，且沒有使用昂貴的沖制刀具。此種類型加工工序用于小批量生產或試樣零件。 圖 11 典型彎板機 使用帶有簡單央具的彎扳機可以容易地對鈑金進行彎曲。彎板機使用一個用在機械或液壓饑上的長模具，適用于小批量生產。模具簡單，適于各種類型的成形加工，而且，加工工序很容易實現(xiàn)自動化。彎板機的模具材料可以是硬木（用于低強度材料與小批量生產），也可以是硬質合金材料。大多數(shù)應用中，一般是使用碳鋼或灰鑄鐵材料模具。 附件 2：外文原文 Stampng Die Design The wide variety of sheet metal parts for both the automobile and electronic industries is produced by numerous forming processes that fall into the generic category of sheetmetal forming. Sheetmetal forming ( also called stamping or pressing )is often carried out in large facilities hundreds of yards long. It is hard to imagine the scope and cost of these facilities without visiting an automobile factory, standing next to the gigantic machines, feeling the floor vibrate, and watching heavy duty robotic manipulators move the parts from one machine to another. Certainly, a videotape or television special cannot convey the scale of today39。s automobile stamping lines. Another factor that one sees standing next to such lines is the number of different sheetforming operations that automobile panels go through. Blanks are created by simple shearing, but from then on a wide variety of bending, drawing, stretching, cropping , and trimming takes place, each requiring a special, custommade die. Despite this wide variety of subprocesses, in each case the desired shapes are achieved by the modes of deformation known as drawing, stretching, and bending. The three modes can be illustrated by considering the deformation of small sheet elements subjected to various states of stress in the plane of the sheet. Figure 1 considers a simple forming process in which a cylindrical cup is produced from a circular blank. Figure 1 Sheet forming a simple cup Drawing is observed in the blank flange as it is being drawn horizontally through the die by the downward action of the punch. A sheet element in the flange is made to elongate in the radial direction and contract in the circumferential direction, the sheet thickness remaining approximately constant Modes of sheet forming are shown in Figure 2. Figure2 Modes of sheet forming Stretching is the term usually used to describe the deformation in which an element of sheet material is made to elongate in two perpendicular directions in the sheet plane. A special form of stretching, which is encountered in most forming operations, is plane strain stretching. In this case, a sheet element is made to stretch in one direction only, with no change in dimensio