Part1Unit13JigsandFixtures

1、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 start

2、ed. 已经说明了工件必须相对于切削刀具定位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于切削运动定位，并在机加工开始前把它装夹到位。到位。 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

3、 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。加工不会将加强肋、型芯等放错位置。

4、 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. 钻模和夹具的相似点是它们都把保证工件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

5、，它们的不同在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。相结合，而夹具则不能。 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 operation

6、s. Fixtures may incorporate means of setting the cutting tools relative to the location system. 实际上，在真实切削中能被导向的切削刀具只实际上，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。削刀具相对定位系统装夹的方法结合在一起。 The advantages of jigs and fixtures can be

7、summarised as follows: (1) Marking out and other measuring and setting out methods are eliminated; 钻模和夹具的优点可归纳如下：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；可以省去划线和其它测量及放样程序； (2) Unskilled workers may proceed confidently and quickly in knowledge that the workpiece can be positioned correctly, and the tools

8、guided or set; (2) 在知道工件能正确定位、刀具能恰当导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向或装夹的情况下，不熟练的工人也能自信而快速地操作；快速地操作； (3) the assembly of parts is facilitated, since all components will be identical within small limits, and “trying” and filing of work is eliminated; (3) 由于所有零件在较小极限范围内是相同由于所有零件在较小极限范围内是相同的，可以省掉工

9、件的的，可以省掉工件的试装试装和锉削，所以零和锉削，所以零件装配很方便；件装配很方便； (4) The parts will be interchangeable, and if the product is sold over a wide area, the problem of spare parts will be simplified. (4) 零件具有互换性，这样如果产品在较大零件具有互换性，这样如果产品在较大范围内销售的话，备件问题将简单化。范围内销售的话，备件问题将简单化。 Bolt holes often have 1.5mm or even 3.0mm clearance

10、for the bolt, and the reader may doubt the necessity of making precision jigs for such work. 螺栓孔常给螺栓留出螺栓孔常给螺栓留出1.5毫米或甚至毫米或甚至3.0毫米毫米的间隙，读者可能会怀疑为这样的工作制造精的间隙，读者可能会怀疑为这样的工作制造精密钻模的必要性。密钻模的必要性。 It must be remembered that the jigs, once made, will be used on many components, and the extra cost of an accura

11、tely made jig is spread over a large output. 但要记住，这种钻模一旦造好，可用于许多零但要记住，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部件，精确制造钻模的额外成本可分摊在大量产品上。产品上。 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, ra

12、ther than to allow careless marking out and machining to encroach upon it. 此外，这样做在装配机械装置时其累积误差之此外，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。工使其超出正常的界限。 1. The location of workpiece. Fig.13.1 represents a body that is completely free i

13、n 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. 工件的定位：图工件的定位：图13.1表示一个在空间完全自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。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相对于三根互相垂直的坐标轴XX、YY和和ZZ来来考虑这些自由度。考虑这些自由度。 The body can mov

14、e 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. 此物体能沿三根坐标轴的任意一根移动；这样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

15、三个旋转自轴的任意一根回转；这样它又具有三个旋转自由度。总的自由度数目是六个。由度。总的自由度数目是六个。 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. 当工件被定位时，必须尽可能多地消除这些自当工件被定位时，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。由度，以保证作业按要求精度进行。 Accuracy is ensured by

16、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. 除非有必要采用另外定位要素的其它考虑，精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。用它们进行所有定位来保证。 If it is necessary, the n

17、ew location features must be machined as a result of location from the former location features. 如果必要的话，新的定位要素必须作为先前的如果必要的话，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。定位要素的定位结果来加工。 2. The clamping of the workpiece. The clamping system must be such that the workpiece is held against the cutting forces, and the clampi

18、ng forces must not be so great as to cause the workpiece to become distorted or damaged. 工件的装夹：装夹系统必须使工件对着切工件的装夹：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削力夹持，而且装夹力又不能大得引起工件变形或损坏。形或损坏。 The workpiece must be supported beneath the point of clamping, to ensure that the forces are taken by the main frame of the

19、jig or fixture, and on to the machine table and bed. 工件必须在装夹点下被支撑，以保证这些力由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器台和钻模或夹具的主框架来承受并传递给机器台和床身。床身。 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 q

20、uickly but with safety. 在设计钻模和夹具时，要同时设计装夹系统来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保证提供恰当的装夹力，并使装夹操作快速而安全。安全。 A 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. 钻模是一种确保在工件正确位置进行钻孔、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。攻丝或铰孔

21、加工的装置。 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. 它基本上由在淬硬钢衬套下将零件夹持到位的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。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。通过

22、它们来导向。 If the workpiece is of simple construction, the jig may be clamped on the workpiece. 如果工件结构比较简单，钻模可夹持在工件上。如果工件结构比较简单，钻模可夹持在工件上。 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 mach

23、ining operation is performed. 然而大多数情况下，工件由钻模来夹持，并且然而大多数情况下，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。样能很快取出。 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. 相对于用常规的手工方法

24、加工孔，钻模使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得钻孔、铰孔和攻丝速度快很多而且精度更高成为可能。成为可能。 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. 另一个优点是采用钻模时不需要熟练工人。保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

25、责任从操作者身上转移到了钻证孔定位精度的责任从操作者身上转移到了钻模上。模上。 The term jig should be used only for devices employed while drilling, reaming, or tapping holes. 钻模这个术语只用在服务于钻孔、铰孔或钻模这个术语只用在服务于钻孔、铰孔或攻丝的装置上。攻丝的装置上。 It is not fastened to the machine on which it is used and may be moved around on the table of the drilling machi

26、ne to bring each bushing directly under the drill. Jigs physically limit and control the path of the cutting tool. 它不固定在使用它的钻床上，它能在钻床工作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。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。钻模有形地限制和控制钻削刀具的路径。 If the operation includes machining operations like milling, plani

27、ng, shaping, turning, etc., the term fixture should be used. 如果作业还包括其它象铣削、刨削、成型、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。车削等机加工，则应采用夹具这一术语。 A fixture holds the work during machining operations but does not contain special arrangements for guiding the cutting tool, as drill jigs do. 夹具在机加工作业时夹持工件，但它不象钻模夹

28、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。那样包含引导切削刀具的特殊布置。 Typical 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. 典型的钻模：图典型的钻模：图13.2所示为一个能在某工件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。

29、孔外已全部完成。 The workpiece has an accurately machined bore, and is located from the bore and the end face, from a cylindrical post. 此工件有一精确机加工的大孔，因此通过一圆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。柱体采用该孔和工件端面定位。 There is no need to control the rotational position about the axis of the bore, because up to the time

30、when the holes are drilled, it is symmetrical about that axis. 由于直至钻这些小孔时，工件都对称于大孔轴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。线，所以没必要控制围绕大孔轴线回转的位置。 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. 四个控制钻头的衬套装在钻板里，连同手拧螺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。母一起用于靠着夹具基座夹持工件。