【正文】 The three adjacent locating surfaces of the workpiece art resting against 3, 2 and I pint respectively, which prevent 9 degrees of freedom. The test three degrees of freedom are arrested by three external forces usually provided directly by clamping. Some of such forces may be attained by friction. If more than six points art used, the additional points will be surplus and unnecessary and would therefore be redundant constraints. 這三個相鄰定位工件表面的藝術(shù)靠著 2 和我分別一品脫 ,防止 9 自由度。更高的產(chǎn)量 ,減少崖、易裝配和儲蓄在勞動力成本導(dǎo)致大幅削減成本的零件生產(chǎn)工裝夾具。夾具和 期貨促進統(tǒng)一的質(zhì)量在制造。這樣的位置必須是不變的 ,在這個意義上 ,這個設(shè)備必須夾和安全中 ,工件的位置 ,為特定處理操作。這是一個適合總是確保一些干擾洞和軸之間的耦合。部分的尺寸會允許變化在 和 之間總公差為 。 The actual size of the object may be larger or smaller than the stated size limitation if 實際大小的對象可能大于或小于規(guī)定的大小限制如果 there can be equal variation in both directions. The plus and minus limitations bine to 可以有相等的兩個方向的變化。 Allowance. The intentional difference between the maximum material limits of mating parts. This is a minimum clearance (positive allowance) or maximum interference (negative allowance) between mating parts. 津貼。它包括上限和下限尺寸大小是容許極端大小的一個部分例如 ,限制一個孔弧1500(下限 )和 (上限 )和一個軸我。 Fit. clearance, interference, or transition fit refer to how the object fits an assembly. 配合。它的區(qū)別是最大值和最小值限制為該維度。 As mentioned above, it is principally impossible to produce machine parts with absolute dimensional accuracy. In fact, it is not necessary or useful. It is quite sufficient that the actual dimension of the part is found between two limit dimensions and a permissible deviation is kept with production to ensure correct functioning of engineering products. The required level of accuracy of the given part is then given by the dimensional tolerance which is prescribed in the drawing. The production accuracy is prescribed with regards to the functionality of the product and to the economy of production as well. The principal factor used to set a tolerance for a dimension should be the function of the feature being controlled by the dimension. Unnecessarily tight tolerances lead to high cost of manufacture resulting from more expensive manufacturing methods and higher reject rates. 正如上面提到的 ,主要是不可能產(chǎn)生機器零件與絕對尺寸精度。 2. Shape deviations。不幸的是 ,它是不可能讓事情一個確切的或維度。 Chapter 7 Introduction 引入 Quality and accuracy are major considerations in making machine parts or structures. 質(zhì)量和準(zhǔn)確性是主要的考慮因素在制造機零件或結(jié)構(gòu)。 EDM removes material by discharging an electrical current, normally stored in a capacitor bank, across a small gap between the tool (cathode) and the workpiece (anode) typically in the order of 50 volts/l0 amps. As shown in Fig6. 1, at the beginning of EDM operation, a high voltage is applied across the narrow gap between the electrode and the workpiece. This high voltage induces an electric field in the insulating dielectric that is present in narrow gap between electrode and workpiece. This cause conducting particles suspended in the dielectric to concentrate at the points of strongest electrical field. When the potential difference between the electrode and the workpiece is sufficiently high ,the dielectric breaks down and a transient spark discharges through the dielectric fluid, removing small amount of material from the workpiece surface. The volume of the material removed per spark discharge is typically in the range of 105 to 106 mm3. The gap is only a few thousandths of an inch, which is maintained at a constant value by the servomechanism that actuates and controls the tool feed. 除材料的電火花加工放電電流 ,通常存儲在電容器銀行 ,在一個小差距工具 (陰極 )和工件 (陽極 )通常在訂單 50 伏特 / 10 安培。 Several types of nontraditional machining processes have been developed to meet extra required machining conditions. When these processes are employed properly, they offer many advantages over traditional machining processes. The mon nontraditional machining processes are described in the following section. 幾種類型的非傳統(tǒng)加工過程已經(jīng)被開發(fā)出來 ,以滿足額外的要求加工條件。 Nontraditional machining utilizes other forms of energy。非常脆 弱的材料很難夾巴德傳統(tǒng)加工 。非傳統(tǒng)加工過程被定義為一組進程 ,去除多余 material by various techniques involving mechanical, thermal,electrical or chemical energy or binations of these energies but do not use a sharp cutting tool as it is used in traditional manufacturing processes. [1] 材料的各種技術(shù)涉及機械、熱、電力或化學(xué)能源或組合這些能量但不使用鋒利的刀具 ,因為它是用在傳統(tǒng)的制造過程。它可以實現(xiàn)刀尖的縱向、橫向和斜向進給。它利用橫拖板絲杠于車床軸線成 90 度夾角 的方向上前后移動。這個通孔具有一個內(nèi)錐面，可以安裝普通車床的中心頂尖。其次，車刀的縱向進給與工件的回轉(zhuǎn)運動具有特定的關(guān)系，因此這決定了螺紋的導(dǎo)程。由于切斷刀非常薄而且處于懸臂狀態(tài)，因此這種加工方法不太精確而且加工起來常常比較困難。 Parting. Parting is the operation by which one section of a workpiece is severed from the remainder by means of cutoff tool. Because cutting tools are quite thin and must have considerable overhang, this process is less accurate and more difficult. The tool should be set exactly at the height of axis of rotation, be kept sharp, have proper clearance angles, and be fed into the workpiece at a proper and uniform feed rate. remainder [ri39。rid?] ，拖板 perate [39。鉆頭安裝在尾架上，后者向工件進給。lindrikl] contoured [39。金屬切削意味著通過機械加工去除金屬。230。 除了車削，還有另外幾種加工操作都可以在車床上進行。m230。無論哪種情況，刀尖必須準(zhǔn)確地與回轉(zhuǎn)中心對正。突出 uniform [39。 There are two basic requirements for thread cutting. ? An accurately shaped and properly mounted tool is needed because thread cutting is a formcutting operation. The resulting thread profile is determined by the shape of the tool and its position relative to the workpiece. ? The second by requirement is that the tool must move longitudinally in a specific relationship to the rotation of workpiece, because this determines the lead of the thread. This requirement is met through the use of the lead screw and the split unit, which provide positive motion of carriage relative to the rotation of spindle formcutting operation 成形加工 longitudinally [l?:?d?i39。變速箱的功能是可以產(chǎn)生不同的主軸轉(zhuǎn)速。拖板組件由橫拖板，小刀架，刀架鞍板和溜板箱組成。小刀架只能手動進給，沒有動力傳到小刀架上。課移動部件的橫向調(diào)整有帶有四方頭的橫向絲杠來完成。傳統(tǒng)的加工刀具的磨損 ,也會