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. 已經(jīng)說明了工件必須相對于切削刀具定位已經(jīng)說明了工件必須相對于切削刀具定位并確保到位。工件劃線后，仍有必要將其相對并確保到位。工件劃線后，仍有必要將其相對于切削運動定位，并在機加工開始前把它裝夾于切削運動定位，并在機加工開始前把它裝夾到位。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. 當要加工若干同樣的工件時，使用鉆模和當要加工若干同樣的工件時，使用鉆模和夾具可以不必在每個工件上劃線；但對鑄件或夾具可以不必在每個工件上劃線；但對鑄件或鍛件而言，還需取一試驗工件劃線以保證照此鍛件而言，還需取一試驗工件劃線以保證照此加工不會將加強肋、型芯等放錯位置。加工不會將加強肋、型芯等放錯位置。

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. 鉆模和夾具的相似點是它們都把保證工件鉆模和夾具的相似點是它們都把保證工件正確定位和夾緊的裝置相結(jié)合

5、，它們的不同在正確定位和夾緊的裝置相結(jié)合，它們的不同在于鉆模在實際切削作業(yè)中還能與刀具導向方法于鉆模在實際切削作業(yè)中還能與刀具導向方法相結(jié)合，而夾具則不能。相結(jié)合，而夾具則不能。 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. 實際上，在真實切削中能被導向的切削刀具只實際上，在真實切削中能被導向的切削刀具只有鉆頭、鉸刀和類似的刀具；因此鉆模用于鉆有鉆頭、鉸刀和類似的刀具；因此鉆模用于鉆削作業(yè)，而夾具用于其余作業(yè)。夾具可以與切削作業(yè)，而夾具用于其余作業(yè)。夾具可以與切削刀具相對定位系統(tǒng)裝夾的方法結(jié)合在一起。削刀具相對定位系統(tǒng)裝夾的方法結(jié)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; 鉆模和夾具的優(yōu)點可歸納如下：鉆模和夾具的優(yōu)點可歸納如下： (1) 可以省去劃線和其它測量及放樣程序；可以省去劃線和其它測量及放樣程序； (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) 在知道工件能正確定位、刀具能恰當導在知道工件能正確定位、刀具能恰當導向或裝夾的情況下，不熟練的工人也能自信而向或裝夾的情況下，不熟練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) 由于所有零件在較小極限范圍內(nèi)是相同由于所有零件在較小極限范圍內(nèi)是相同的，可以省掉工

9、件的的，可以省掉工件的試裝試裝和銼削，所以零和銼削，所以零件裝配很方便；件裝配很方便； (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) 零件具有互換性，這樣如果產(chǎn)品在較大零件具有互換性，這樣如果產(chǎn)品在較大范圍內(nèi)銷售的話，備件問題將簡單化。范圍內(nèi)銷售的話，備件問題將簡單化。 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. 螺栓孔常給螺栓留出螺栓孔常給螺栓留出1.5毫米或甚至毫米或甚至3.0毫米毫米的間隙，讀者可能會懷疑為這樣的工作制造精的間隙，讀者可能會懷疑為這樣的工作制造精密鉆模的必要性。密鉆模的必要性。 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. 但要記住，這種鉆模一旦造好，可用于許多零但要記住，這種鉆模一旦造好，可用于許多零部件，精確制造鉆模的額外成本可分攤在大量部件，精確制造鉆模的額外成本可分攤在大量產(chǎn)品上。產(chǎn)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，這樣做在裝配機械裝置時其累積誤差之此外，這樣做在裝配機械裝置時其累積誤差之小也是令人驚訝的。在確定一個間隙時，最好小也是令人驚訝的。在確定一個間隙時，最好能保證它的習慣要求，而不是隨便劃線和機加能保證它的習慣要求，而不是隨便劃線和機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：圖工件的定位：圖13.1表示一個在空間完全自表示一個在空間完全自由的物體，在這種情況下它具有六個自由度。由的物體，在這種情況下它具有六個自由度。相對于三根互相垂直的坐標軸相對于三根互相垂直的坐標軸XX、YY和和ZZ來來考慮這些自由度?？紤]這些自由度。 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. 此物體能沿三根坐標軸的任意一根移動；這樣此物體能沿三根坐標軸的任意一根移動；這樣就具有三個平移自由度。它也能圍繞三根坐標就具有三個平移自由度。它也能圍繞三根坐標軸的任意一根回轉(zhuǎn)；這樣它又具有

15、三個旋轉(zhuǎn)自軸的任意一根回轉(zhuǎn)；這樣它又具有三個旋轉(zhuǎn)自由度?？偟淖杂啥葦?shù)目是六個。由度?？偟淖杂啥葦?shù)目是六個。 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. 當工件被定位時，必須盡可能多地消除這些自當工件被定位時，必須盡可能多地消除這些自由度，以保證作業(yè)按要求精度進行。由度，以保證作業(yè)按要求精度進行。 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慮，精除非有必要采用另外定位要素的其它考慮，精度可通過盡可能早地加工合適的定位要素并采度可通過盡可能早地加工合適的定位要素并采用它們進行所有定位來保證。用它們進行所有定位來保證。 If it is necessary, the n

17、ew location features must be machined as a result of location from the former location features. 如果必要的話，新的定位要素必須作為先前的如果必要的話，新的定位要素必須作為先前的定位要素的定位結(jié)果來加工。定位要素的定位結(jié)果來加工。 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. 工件的裝夾：裝夾系統(tǒng)必須使工件對著切工件的裝夾：裝夾系統(tǒng)必須使工件對著切削力夾持，而且裝夾力又不能大得引起工件變削力夾持，而且裝夾力又不能大得引起工件變形或損壞。形或損壞。 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. 工件必須在裝夾點下被支撐，以保證這些力由工件必須在裝夾點下被支撐，以保證這些力由鉆?；驃A具的主框架來承受并傳遞給機器臺和鉆?；驃A具的主框架來承受并傳遞給機器臺和床身。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. 在設計鉆模和夾具時，要同時設計裝夾系統(tǒng)來在設計鉆模和夾具時，要同時設計裝夾系統(tǒng)來保證提供恰當?shù)难b夾力，并使裝夾操作快速而保證提供恰當?shù)难b夾力，并使裝夾操作快速而安全。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. 鉆模是一種確保在工件正確位置進行鉆孔、鉆模是一種確保在工件正確位置進行鉆孔、攻絲或鉸孔加工的裝置。攻絲或鉸孔

21、加工的裝置。 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. 它基本上由在淬硬鋼襯套下將零件夾持到位的它基本上由在淬硬鋼襯套下將零件夾持到位的夾持裝置組成，鉆孔作業(yè)中鉆頭穿過這些襯套。夾持裝置組成，鉆孔作業(yè)中鉆頭穿過這些襯套。通過它們來導向。通過

22、它們來導向。 If the workpiece is of simple construction, the jig may be clamped on the workpiece. 如果工件結(jié)構(gòu)比較簡單，鉆?？蓨A持在工件上。如果工件結(jié)構(gòu)比較簡單，鉆?？蓨A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. 然而大多數(shù)情況下，工件由鉆模來夾持，并且然而大多數(shù)情況下，工件由鉆模來夾持，并且把鉆模設計成能將工件迅速裝入而在加工后同把鉆模設計成能將工件迅速裝入而在加工后同樣能很快取出。樣能很快取出。 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. 相對于用常規(guī)的手工方法

24、加工孔，鉆模使相對于用常規(guī)的手工方法加工孔，鉆模使得鉆孔、鉸孔和攻絲速度快很多而且精度更高得鉆孔、鉸孔和攻絲速度快很多而且精度更高成為可能。成為可能。 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. 另一個優(yōu)點是采用鉆模時不需要熟練工人。保另一個優(yōu)點是采用鉆模時不需要熟練工人。保證孔定位精度的

25、責任從操作者身上轉(zhuǎn)移到了鉆證孔定位精度的責任從操作者身上轉(zhuǎn)移到了鉆模上。模上。 The term jig should be used only for devices employed while drilling, reaming, or tapping holes. 鉆模這個術語只用在服務于鉆孔、鉸孔或鉆模這個術語只用在服務于鉆孔、鉸孔或攻絲的裝置上。攻絲的裝置上。 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鉆床上，它能在鉆床工作它不固定在使用它的鉆床上，它能在鉆床工作臺上到處移動以使每個襯套都直接位于鉆頭下。臺上到處移動以使每個襯套都直接位于鉆頭下。鉆模有形地限制和控制鉆削刀具的路徑。鉆模有形地限制和控制鉆削刀具的路徑。 If the operation includes machining operations like milling, plani

27、ng, shaping, turning, etc., the term fixture should be used. 如果作業(yè)還包括其它象銑削、刨削、成型、如果作業(yè)還包括其它象銑削、刨削、成型、車削等機加工，則應采用夾具這一術語。車削等機加工，則應采用夾具這一術語。 A fixture holds the work during machining operations but does not contain special arrangements for guiding the cutting tool, as drill jigs do. 夾具在機加工作業(yè)時夾持工件，但它不象鉆模夾

28、具在機加工作業(yè)時夾持工件，但它不象鉆模那樣包含引導切削刀具的特殊布置。那樣包含引導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. 典型的鉆模：圖典型的鉆模：圖13.2所示為一個能在某工件所示為一個能在某工件的法蘭上鉆四個孔的鉆模，該工件除了這四個的法蘭上鉆四個孔的鉆模，該工件除了這四個孔外已全部完成。

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. 此工件有一精確機加工的大孔，因此通過一圓此工件有一精確機加工的大孔，因此通過一圓柱體采用該孔和工件端面定位。柱體采用該孔和工件端面定位。 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. 由于直至鉆這些小孔時，工件都對稱于大孔軸由于直至鉆這些小孔時，工件都對稱于大孔軸線，所以沒必要控制圍繞大孔軸線回轉(zhuǎn)的位置。線，所以沒必要控制圍繞大孔軸線回轉(zhuǎn)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. 四個控制鉆頭的襯套裝在鉆板里，連同手擰螺四個控制鉆頭的襯套裝在鉆板里，連同手擰螺母一起用于靠著夾具基座夾持工件。母一起用于靠著夾具基座夾持工件。