【正文】 e venting of the mould can be done, if necessary, to increase the permeability of the mould. After venting the patterns are carefully removed from both cope and drag, and a gate or gates are carefully cut to connect the runner channel with the main cavity. Gates should be sited to allow or entry into mould with a minimum of turbulence. Any loose sand is gently blown away and if a core is to be used it the cope upon the drag and it is then ready for use. Liquid metal is poured smoothly into the mould via the feeder. Pouring ceases when liquid metal appears at the top of the risers and the feeder channel is also full. When the metal that has been poured into a sand mould has fully solidified the mould is broken and casting is removed. The casting still has the runner and risers attached to it and there will be sand adhering to portions of the surface. Runners and risers are cut off and returned to the melting furnace. Sand cores are broken and adherent sand is cleaned from the surface by vibration or by sand blasting with dry sand. Any fins or metal flash formed at mould parting lines are removed by grinding and the castings are then ready for inspection. The main Elements of Horizontal Milling Machines Column and base The column and base form the foundation of the plete machine. Both are made from cast iron, designed with thick sections to ensure plete rigidity and freedom form vibration. The base, upon which the column is mounted, is also the cuttingfluid reservoir and contains the pump to circulate the fluid to cutting area. The column contains the spindle, accurately located in precision bearings. The spindle id driven through a gearbox from a veebelt drive from the electric motor housed at the base of column. The gearbox enables a range of spindle speeds to be selected. In the model shown, twelve spindle speeds from 32 to 1400rev/min are available. The front of column carries the guideways upon which the knee is located and guided in a vertical direction. Knee The knee, mounted on the column guideways, provides the vertical movement of the table. Power feed is available, through a gearbox mounted on the side, from a separate builtin motor, providing a range of twelve feed rates from 6 to 250mm/min. Drive is through a leadscrew, whose bottom end is fixed to machine base. Provision is made to raise and lower the knee by hand through a leadscrew and nut operates by a handwheel at the front. The knee has guideways on its top surface giving fullwidth support to the saddle and guiding it in a transverse direction. lock is provided to clamp the knee in any vertical position on the column. Saddle The saddle, mounted on the knee guideways, providers the transverse movement of the table. Power feed is provided through the gearbox on the knee. A range of twelve feeds is available, from 12 to 500mm/min. Alternative hand movement is provided through a leadscrew and nut by a hand heel at the front of the knee. Camping of saddle to the knee is achieved by two clamps on the side of the saddle. The saddle has dovetail gun its upper surface, at right angles to the knee guideways, to provide a guide to the table in a longitudinal direction. Table The table provides the surface upon which all workpieces and workholding equipment are located and clamped. A series of tee slots is provided for this purpose. The dovetail guides on undersurface locate in the guideways on the saddle, giving straightline movement to the table in longitudinal direction at right angles to the saddle movement. Power feed is provided from the knee gearbox, through the saddle, to the table leadscrew. Alternative hand feed is provided by a handwheel at each end of the table. Stops at the front of the table can be set to disengage the longitudinal feed automatically in each direction. Spindle The spindle, accurately mounted in precision bearings, provides the drive for the milling cutters. Cutters can be mounted straight on the spindle nose or in curterholding devices which in turn are mounted in the spindle, held in position by a drawbolt passing the hold spindle. Spindles of milling machines have a standard spindle nose to allow for easy interchange of cutters and cutterholding devices. The bore of the nose is tapered to provide accurate location, the angle of taper being 1. The diameter of the taper depends on the size of the machine and may be 30,40,or 50 IST. Due to their steepness of angle, there tapers – known as nonstick or selfreleasing cannot be relied upon to transmit the drive to the cutter or cutterholding device. Two driving keys are provided to transmit the drive. Overarm and arbor support Due to the length of arbors used, support is required at the outer end to prevent deflection when cutting takes place. Support is provided by an arborsupport bracket, clamped to an overarm which is mounted on top of the column in a dovetail slide. The overarm is adjustable in or out for different lengths of arbor, or can be fully pushed in when arbor support is not required. Two clamping bolts are support is located in the overarm dovetail and is locked by which the arbor runs during splindle rotation. 中文譯文 數(shù)控機床的組成部分 數(shù)控機床的組成部分包括測量系統(tǒng)、控制系統(tǒng)、伺服系統(tǒng)及開環(huán)或閉環(huán)系統(tǒng)，在對數(shù)控零件進行實際程序設計之前，了解各組成部分是重要的。注意，使用這個系統(tǒng)時，每個新的位置在 X 和 Y 鐲上的值都是建立在前一個位置之上的。 具有在兩個或多個坐標做方向上同時運動的能力的機床，歸屬連續(xù)軌跡控制或輪廓控制類機床。把電機注解接在 10 扣 /英寸的絲桿上，每步能產(chǎn)生 英寸的移動。反饋裝置真實地將工作臺加以比較，并對任何誤差進行補償。 數(shù)字控制 先進制造技術中的一個最基本的概念是數(shù)字控制（ NC）。 發(fā)展數(shù)控技術是為了克服人類操作者的局限性，而且它確實完成了這項工作。然而，曲線軌跡成為機床加工的一個問題，在編程時應該采用一系列的水平與豎直的臺階來生成曲線。指令程序寫在穿孔紙帶上（它后來被塑料磁帶所取代），采用帶閱讀機將寫在紙帶或磁帶上的指令給機器翻譯出來。易損壞的紙帶顯然不能承受嚴酷的車間環(huán)境和這種重復使用。而且?guī)ㄟ^閱讀機的次數(shù)還必須與需要加工的零件的個數(shù)相同。當主計算機出現(xiàn)故障時，由其控制的所有機床都將停止工作。同一個程序可能要分別裝入十個相互之間沒有通信聯(lián)系的微機中。為了澄清混亂的概連和術語， 美國機械工程師協(xié)會頒布了 ASA 標準 B5221950，本文的術語即以此為依據(jù)。為了節(jié)省磨刀時間，刀具端后刀面的一部分有時可以 直接鍛造形成，而不需要進行摸削。 角度 7 為側切削刀角，它是側切削刃和刀兵側面之間的夾角。鑄造模型一般由硬木