JigsandFixture解析.ppt

Jigs-and-FixtureJigs-and-Fixture解析解析Definition of a Drill JigDefinition of a Drill JigIntroductionNew Terms and TerminologiesContentsTypical Jigs and FixturesTypical Jigs and Fixtures1 12 23 34 4New Words and Terminologies•Jig : 钻模•Fixture：夹具•Workpiece：工件•Cutting tool：刀具，切削工具，切削刀具•Clamp：vt, 夹住，加紧；n, 夹具•Casting :n,铸造，铸件•Forging: n, 锻造，锻件•Rib：n, 加强肋•Core: n,型芯•Drill: n, 钻头，钻机•Reamer: n, 铰刀New Words and Terminologies•Cutter : n, 铣刀•Bolt: n, 螺栓•Nut ：n, 螺母•Clearance: n, 间隙•Observance :n, 遵守•Encroach :侵犯，侵占•Perpendicular:垂直的•Tap: 攻螺纹•Bushing : n, 套管，衬管 •Hardened-steel：淬火钢•Flange : n,法兰，凸缘•Milling: n, 铣削•planing: n, 刨•Shaping: n,成形•Turning: n,车削，车削加工•Tenon: n,突隼New Words and TerminologiesIntroduction It has already been stated that the workpiece must be located relative to the cutting tool, and be secured in that position. After the workpiece has been marked out, it is still necessary to position it with respect to the machine movements, and to clamp it in that position before machining is started.已经说明了工件必须相对于切削刀具定位并确保到位。

工件划线后，仍有必要将其相对于切削运动定位，并在机加工开始前把它装夹到位工件工件划线划线机械工程英语机械工程英语When several identical workpieces are to be produced the need to mark out each part is eliminated by the use of jigs and fixtures, but if a casting or forging is involved, a trial workpiece is marked out, to ensure that the workpiece can be produced from it, and to ensure that ribs, cores, etc. have not become misplaced.当要加工若干同样的工件时，使用钻模和夹具可以不必在每个工件上划线；但对铸件或锻件而言，还需取一试验工件划线以保证照此加工不会将加强肋、型芯等放错位置钻模钻模夹具夹具铸件铸件锻件锻件加强肋加强肋型芯型芯机械工程英语机械工程英语 Jigs and fixtures are alike in that they both incorporate devices to ensure that the workpiece is correctly located and clamped, but they differ in that jigs incorporate means of tool guiding during the actual cutting operation, and fixtures do not. In practice, the only cutting tools that can be guided while actually cutting are drills, reamers, and similar cutters; and so jigs are associated with drilling operations, and fixtures with all other operations. Fixtures may incorporate means of setting the cutting tools relative to the location system.钻模和夹具的相似点是它们都把保证工件正确定位和夹紧的装置相结合，它们的不同在于钻模在实际切削作业中还能与刀具导向方法相结合，它们的不同在于钻模在实际切削作业中还能与刀具导向方法相结合，而夹具则不能。

实际上，在真实切削中能被导向的切削刀具只有钻头、铰刀和类似的刀具；因此钻模用于钻削作业，而夹具用于其余作业夹具可以与切削刀具相对定位系统装夹的方法结合在一起夹紧夹紧切削操作切削操作钻头钻头铰刀铰刀刀具刀具机械工程英语机械工程英语The advantages of jigs and fixtures can be summarized as follows:1)Marking out and other measuring and setting out methods are eliminated; 2)Unskilled workers may proceed confidently and quickly in knowledge that the workpiece can be positioned correctly, and the tools guided or set;钻模和夹具的优点可归纳如下： 1)可以省去划线和其它测量及放样程序； 2)在知道工件能正确定位、刀具能恰当导向或装夹的情况下，不熟练的工人也能自信而快速地操作；布置，安装布置，安装机械工程英语机械工程英语 3)the assembly of parts is facilitated, since all components will be identical within small limits, and “trying” and filing of work is eliminated; 4)The parts will be interchangeable, and if the product sold over a wide area, the problem of spare parts will be simplified.3)由于所有零件在较小极限范围内是相同的，可以省掉工件的‘试装’和锉削锉削，所以零件装配很方便； 4)零件具有互换性，这样如果产品在较大范围内销售的话，备件问题将简单化。

锉削锉削机械工程英语机械工程英语Bolt holes often have 1.5mm or even 3.0mm clearance for the bolt, and the reader may doubt the necessity of making precision jigs for such work. It must be remembered that the jigs, once made, will be used on many components, and the extra cost of an accurately made jig is spread over a large output. Furthermore, it is surprising how small errors accumulate in a mechanism during its assembly. When a clearance is specified, it is better to ensure its observance, rather than to allow careless marking out and machining to encroach upon it．螺栓孔常给螺栓留出1.5毫米或甚至3.0毫米的间隙，读者可能会怀疑为这样的工作制造精密钻模的必要性。

但要记住，这种钻模一旦造好，可用于许多零部件，精确制造钻模的额外成本可分摊在大量产品上此外，这样做在装配机械装置时其累积误差之小也是令人惊讶的在确定一个间隙时，最好能保证它的习惯要求，而不是随便划线和机加工使其超出正常的界限螺栓螺栓间隙间隙遵守遵守侵犯，侵占侵犯，侵占机械工程英语机械工程英语 1) The location of workpiece. Fig.13.1 represents a body that is completely free in space. In this condition it has six degrees of freedom. Consider these freedoms with respect to the three mutually perpendicular axes XX, YY, and ZZ. The body can move along any of these axes; it therefore has three freedoms of translation. It can also rotate about any of the three axes; it therefore has three freedoms of rotation. The total number of freedoms is six. 自由度自由度垂直的垂直的axis机械工程英语机械工程英语When work is located, as many of these freedoms as possible must be eliminated, to ensure that the operation is performed with the required accuracy. Accuracy is ensured by machining suitable location features as early as possible, and using them for all location, unless other considerations mean that other location features must be used. If it is necessary, the new location features must be machined as a result of location from the former location features.机械工程英语机械工程英语1) 工工件件的的定定位位：：图13.1表示一个在空间完全自由的物体，在这种情况下它具有六个自由度。

相对于三根互相垂直的坐标轴XX、YY和ZZ来考虑这些自由度此物体能沿三根坐标轴的任意一根移动；这样就具有三个平移自由度它也能围绕三根坐标轴的任意一根回转；这样它又具有三个旋转自由度总的自由度数目是六个当工件被定位时，必须尽可能多地消除这些自由度，以保证作业按要求精度进行除非有必要采用另外定位要素的其它考虑，精度可通过尽可能早地加工合适的定位要素并采用它们进行所有定位来保证如果必要的话，新的定位要素必须作为先前的定位要素的定位结果来加工机械工程英语机械工程英语2) The clamping of the workpiece. The clamping system must be such that the workpiece is held against the cutting forces, and the clamping forces must not be so great as to cause the workpiece to become distorted or damaged. The workpiece must be supported beneath the point of clamping, to ensure that the forces are taken by the main frame of the jig or fixture, and on to the machine table and bed. When jigs and fixtures are designed, the clamping system is designed to ensure that the correct clamping force is applied, and that the clamps can be operated quickly but with safety.切削力切削力装夹力装夹力机械工程英语机械工程英语2) 工工件件的的装装夹夹：：装夹系统必须使工件对着切削力夹持，而且装夹力又不能大得引起工件变形或损坏。

工件必须在装夹点下被支撑，以保证这些力由钻模或夹具的主框架来承受并传递给机床工作台和床身在设计钻模和夹具时，要同时设计装夹系统来保证提供恰当的装夹力，并使装夹操作快速而安全Definition of a Drill JigA drill jig is a device for ensuring that a hole to be drilled, tapped, or reamed in a workpiece will be machined in the proper place. Basically it consists of a clamping device to hold the part in position under hardened-steel bushings through which the drill passes during the drilling operation. The drill is guided by the bushings. If the workpiece is of simple construction, the jig may be clamped on the workpiece. In most cases, however, the workpiece is held by the jig, and the jig is arranged so that the workpiece can be quickly inserted and as quickly removed after the machining operation is performed.钻钻攻螺纹攻螺纹铰铰淬火钢淬火钢套管，衬管套管，衬管Definition of a Drill Jig钻模是一种确保在工件正确位置进行钻孔、攻丝或铰孔加工的装置。

它基本上由在淬硬钢衬套下将零件夹持到位的夹持装置组成，钻孔作业中钻头穿过这些衬套，通过它们来导向如果工件结构比较简单，钻模可夹持在工件上然而大多数情况下，工件由钻模来夹持，并且把钻模设计成能将工件迅速装入而在加工后同样能很快取出机械工程英语机械工程英语 Jigs make it possible to drill, ream, and tap holes at much greater speeds and with greater accuracy than when the holes are produced by conventional hand methods. Another advantage is that skilled workers are not required when jigs are used. Responsibility for the accuracy of hole location is taken from the operator and given to the jig.相对于用常规的手工方法加工孔，钻模使得钻孔、铰孔和攻丝速度快很多而且精度更高成为可能。

另一个优点是采用钻模时不需要熟练工人保证孔定位精度的责任从操作者身上转移到了钻模上机械工程英语机械工程英语 The term jig should be used only for devices employed while drilling, reaming, or tapping holes. It is not fastened to the machine on which it is used and may be moved around on the table of the drilling machine to bring each bushing directly under the drill. Jigs physically limit and control the path of the cutting tool.钻模这个术语只用在服务于钻孔、铰孔或攻丝的装置上它不固定在使用它的钻床上，它能在钻床工作台上到处移动以使每个衬套都直接位于钻头下钻模有形地限制和控制钻削刀具的路径机械工程英语机械工程英语 If the operation includes machining operations like milling, planing, shaping, turning, etc., the term fixture should be used. A fixture holds the work during machining operations but does not contain special arrangements for guiding the cutting tool ,as drill jigs do.如果作业还包括其它象铣削、刨削、成型、车削等机加工，则应采用夹具这一术语。

夹具在机加工作业时夹持工件，但它不象钻模那样包含引导切削刀具的特殊布置Typical Jigs and FixturesTypical drill jig. Figure 13.2 illustrates a drilling jig for drilling four holes in the flange of a workpiece that has been completed except for the four holes. The workpiece has an accurately machined bore, and is located from the bore and the end face, from a cylindrical post. There is no need to control the rotational position about the axis of the bore, because up to the time when the holes are drilled, it is symmetrical about that axis. The four bushes used to control the drill are held in the drill plate, which, with the hand nut, is used to clamp the workpiece against the base of the fixture.Typical Jigs and Fixtures典典型型的的钻钻模模：：图13.2所示为一个能在某工件的法兰上钻四个孔的钻模，该工件除了这四个孔外已全部完成。

此工件有一精确机加工的大孔，因此通过一圆柱体采用该孔和工件端面定位由于直至钻这些小孔时，工件都对称于大孔轴线，所以没必要控制围绕大孔轴线回转的位置四个控制钻头的衬套装在钻板里，连同手拧螺母一起用于靠着夹具基座夹持工件Typical Jigs and FixturesTypical milling fixture. Figure 13.3 illustrates a simple milling fixture for milling the slot in the otherwise completed workpiece shown. The workpiece is located from two of the four holes in its base, and from the underside of the base. The workpiece is clamped in position, and cutter is located against the setting block, which provides setting or cutter position and depth of cut. The fixture must be positioned relative to the machine table, this is done by engaging the two tenons at the bottom of the fixture in the slot in the machine table. The fixture is secured to the machine table with T-bolts, also engaging in the slots in the table (Fig.13.3).突隼突隼Typical Jigs and Fixtures典型的铣削夹具：图13.3所示为一用于在图示其它工序都完成的工件上铣槽的简单铣削夹具。

此工件采用其基座上四孔中的两孔和基座的底面定位工件被夹持到位，铣刀靠着提供安装或铣刀位置及切削深度的安装台定位夹具必须相对于铣床工作台定位，这可通过把夹具底部的两个凸榫插入工作台上的槽中来实现夹具用T型螺栓固定于铣床工作台，同时与工作台上的槽接合(图13.3)划线找正装夹划线找正装夹事先按图纸要求在工作表面上划出位置线、加工线和找正线；装夹工件时，先按照找正线找正工件的位置，然后夹紧工件划线找正不需要专门的设备，通用性好，但效率低，精度并不高，通常划线找正精度只能达到0.1~0.5mm此方法用于单件小批生产中铸件的粗加工工序在支座零件上镗孔，可先在划线台上划出十字中心线，再划出找正线和加工线然后将工件安装在四爪卡盘上，按找正线找正后夹紧Fig 13.1 The six degrees of freedomFig 10.2 Drilling JigFig 13.3 Milling fixture工件的装夹直接找正装夹直接找正装夹将工件装在机床上，然后按工件的某个（某些）表面，用划针或者百分表等量具进行找正，以获得工件在机床上的正确位置直接找正效率低，精度取决为操作的技术水平，可以达到很高的精度，适用于单件小批生产或者定位精度特别高的场合划线找正划线找正事先按图纸的要求在工件表面划出位置线、加工线、和找正线；装夹时，先按照找正线找正工件的位置，然后夹紧工件。

划线找正不需要专门设备，通用性好，但效率低，精度不高，通常用于单件小批量生产中铸件的粗加工工序夹具找正夹具找正钻套固定钻套固定钻套可换钻套可换钻套快速钻套快速钻套结束结束 。