機械工程英語第二版葉邦彥-漢語翻譯 11-14單元

Unit 11 lathe and turning

車床與車削

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The Lathe and Its Construction車床及其結構

A lathe is a machine tool used primarily for producing surfaces of revolution and flat edges.

車床是主要用於生成旋轉表面和平整邊緣的機床。

Based on their purpose, construction, number of tools that can simultaneously be mounted, and degree of automation, lathes-or, more accurately, lathe-type machine tools can be classified as follows:

根據它們的使用目的、結構、能同時被安裝刀具的數量和自動化的程度，車床—或更確切地說是車床類的機床，可以被分成以下幾類：

(1)Engine lathes

(2)Toolroom lathes

(3)Turret lathes

(4)Vertical turning and boring mills

(5)Automatic lathes

(6)Special-purpose lathes

(1)普通車床

(2)萬能車床

(3)轉塔車床

(4)立式車床

(5)自動車床

(6)特殊車床

In spite of that diversity of lathe-type machine tools, they all have common features with respect to construction and principle of operation. These features can best be illustrated by considering the commonly used representative type, the engine lathe. Following is a description of each of the main elements of an engine lathe, which is shown in Fig.11.1.

雖然車床類的機床多種多樣，但它們在結構和操作原理上具有共同特性。這些特性可以透過普通車床這一最常用的代表性型別來最好地說明。下面是關於圖11.1所示普通車床的主要部分的描述。

Lathe bed. The lathe bed is the main frame, involving a horizontal beam on two vertical supports. It is usually made of grey or nodular cast iron to damp vibrations and is made by casting.

車床床身：車床床身是包含了在兩個垂直支柱上水平橫樑的主骨架。為減振它一般由灰鑄鐵或球墨鑄鐵鑄造而成。

It has guideways to allow the carriage to slide easily lengthwise. The height of the lathe bed should be appropriate to enable the technician to do his or her job easily and comfortably.

它上面有能讓大拖板輕易縱向滑動的導軌。車床床身的高度應適當以讓技師容易而舒適地工作。

Headstock. The headstock is fixed at the left hand side of the lathe bed and includes the spindle whose axis is parallel to the guideways (the slide surface of the bed). The spindle is driven through the gearbox, which is housed within the headstock.

主軸箱：主軸箱固定在車床床身的左側，它包括軸線平行於導軌的主軸。主軸透過裝在主軸箱內的齒輪箱驅動。

The function of the gearbox is to provide a number of different spindle speeds (usually 6 up to 18 speeds). Some modern lathes have headstocks with infinitely variable spindle speeds, which employ frictional ,electrical ,or hydraulic drives.

齒輪箱的功能是給主軸提供若干不同的速度(通常是6到18速)。有些現代車床具有采用摩擦、電力或液壓驅動的無級調速主軸箱。

The spindle is always hollow, i. e., it has a through hole extending lengthwise. Bar stocks can be fed through that hole if continuous production is adopted.

主軸往往是中空的，即縱向有一通孔。如果採取連續生產，棒料能透過此孔進給。

Also, that hole has a tapered surface to allow mounting a plain lathe center. The outer surface of the spindle is threaded to allow mounting of a chuck, a face plate, or the like.

同時，此孔為錐形表面可以安裝普通車床頂尖。主軸外表面是螺紋可以安裝卡盤、花盤或類似的裝置。

Tailstock. The tailstock assembly consists basically of three parts, its lower base, an intermediate part, and the quill. The lower base is a casting that can slide on the lathe bed along the guideways, and it has a clamping device to enable locking the entire tailstock at any desired location, depending upon the length of the workpiece.

尾架：尾架總成基本包括三部分，底座、尾架體和套筒軸。底座是能在車床床身上沿導軌滑動的鑄件，它有一定位裝置能讓整個尾架根據工件長度鎖定在任何需要位置。

The intermediate part is a casting that can be moved transversely to enable alignment of the axis of the tailstock with that of the headstock. The third part, the quill, is a hardened steel tube, which can be moved longitudinally in and out of the intermediate part as required.

尾架體為一能橫向運動的鑄件，它可以調整尾架軸線與主軸箱軸線成一直線。第三部分，套筒軸是一淬硬鋼管，它能根據需要在尾架體中縱向進出移動。

This is achieved through the use of a handwheel and a screw, around which a nut fixed to the quill is engaged. The hole in the open side of the quill is tapered to enable mounting of lathe centers or other tools like twist drills or boring bars. The quill can be locked at any point along its travel path by means of a clamping device.

這透過使用手輪和螺桿來達到，與螺桿齧合的是一固接在套筒軸上的螺母。套筒軸開口端的孔是錐形的，能安裝車床頂尖或諸如麻花鑽和鏜杆之類的工具。套筒軸透過定位裝置能沿著它的移動路徑被鎖定在任何點。

The carriage. The main function of the carriage is mounting of the cutting tools and generating longitudinal and/or cross feeds. It is actually an H-shaped block that slides on the lathe bed between the headstock and tailstock while being guided by the V-shaped guideways of the bed.

大拖板：大拖板的主要功能是安裝刀具和產生縱向和/或橫向進給。它實際上是一由車床床身V形導軌引導的、能在車床床身主軸箱和尾架之間滑動的H形滑塊。

The carriage can be moved either manually or mechanically by means of the apron and either the feed rod or the lead screw.

大拖板能手動或者透過溜板箱和光桿(進給杆)或絲桿(引導螺桿)機動。

When cutting screw threads, power is provided to the gearbox of the apron by the lead screw. In all other turning operations, it is the feed rod that drives the carriage. The lead screw goes through a pair of half nuts, which are fixed to the rear of the apron.

在切削螺旋時，動力透過絲桿提供給溜板箱上的齒輪箱。在其餘車削作業中，都由光桿驅動大拖板。絲桿穿過一對固定在溜板箱後部的剖分螺母。

When actuating a certain lever, the half nuts are clamped together and engage with the rotating lead screw as a single nut, which is fed, together with the carriage, along the bed. When the lever is disengaged, the half nuts are released and the carriage stops.

當開動特定操作杆時，剖分螺母夾在一起作為單個螺母與旋轉的絲桿齧合，並帶動拖板沿著床身提供進給。當操作杆脫離時，剖分螺母釋放同時大拖板停止運動。

On the other hand, when the feed rod is used, it supplies power to the apron through a worm gear. The latter is keyed to the feed rod and travels with the apron along the feed rod, which has a keyway extending to cover its whole length.

另一方面，當使用光桿時則透過蝸輪給溜板箱提供動力。 蝸輪用鍵連線在光桿上，並與溜板箱一起沿光桿運動，光桿全長範圍開有鍵槽。

A modern lathe usually has a quick-change gearbox located under the headstock and driven from the spindle through a train of gears. It is connected to both the feed rod and the lead screw and enables selecting a variety of feeds easily and rapidly by simply shifting the appropriate levers.

現代車床一般在主軸箱下裝備快速變換齒輪箱，透過一系列齒輪由主軸驅動。它與光桿和絲桿連線，能容易並快速地透過簡單轉換適當的操作杆選擇各種進給。

The quick-change gearbox is employed in plain turning, facing and thread cutting operations. Since that gearbox is linked to the spindle, the distance that the apron (and the cuttingtool) travels for each revolution of the spindle can be controlled and is referred to as the feed.

快速變換齒輪箱可用於普通車削、端面切削和螺旋切削作業中。由於這種齒輪箱與主軸相連，主軸每轉一圈溜板箱(和切削刀具)運動的距離能被控制，這距離就可以被認為是進給。

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Lathe Cutting Tools車床切削刀具

The shape and geometry of the lathe tools depend upon the purpose for which they are employed.

車床刀具的形狀和幾何引數取決於它們的使用目的。

Turning tools can be classified into two main groups, namely, external cutting tools and internal cutting tools. Each of these two groups include the following types of tools:

車削刀具可以分為兩個主要組別，即外部切削刀具和內部切削刀具。這兩組中的每一組都包括以下型別刀具：

Turning tools. Turning tools can be either finishing or rough turning tools. Rough turning tools have small nose radii and are employed when deep cuts are made.

車削刀具：車削刀具可以是精車刀具或粗車刀具。粗車刀具刀尖半徑較小，用於深切削。

On the other hand, finishing tools have larger nose radii and are used for obtaining the final required dimensions with good surface finish by making slight depths of cut. Rough turning tools can be right-hand or left-hand types, depending upon the direction of feed. They can have straight, bent, or offset shanks.

而精車刀具刀尖半徑較大，用於透過微量進刀深度來獲得具有較好表面光潔度的最終所需尺寸。粗車刀具按其進給方向可以是右手型的或是左手型的。它們可以有直的、彎的或偏置的刀杆。

Facing tools. Facing tools are employed in facing operations for machining plane side or end surfaces. There are tools for machining left-hand-side surfaces and tools for right-hand-side surfaces. Those side surfaces are generated through the use of the cross feed, contrary to turning operations, where the usual longitudinal feed is used.

端面刀具：端面刀具用在端面作業中加工平板側面或端部表面，也有加工左右側表面之分。與一般採用縱向進給的車削作業相反，那些側表面透過採用橫向進給產生。

Cutoff tools. Cutoff tools, which are sometimes called parting tools, serve to separate the workpiece into parts and/or machine external annular grooves.

切斷刀具：切斷刀具，有時也稱為分割刀具，用於將工件分割成若干部分和/或加工外部環形槽。

Thread-cutting tools. Thread-cutting tools have either triangular, square, or trapezoidal cutting edges, depending upon the cross section of the desired thread. Also, the plane angles of these tools must always be identical to those of the thread forms.

螺紋切削刀具：螺紋切削刀具根據所需螺紋的橫截面，有三角形的、矩形的或梯形的切削刃。同時，這些刀具的平面角必須始終與螺紋形狀的平面角保持一致。

Thread-cutting tools have straight shanks for external thread cutting and are of the bent-shank type when cutting internal threads.

車外螺紋的螺紋切削刀具為直刀杆，而車內螺紋的螺紋切削刀具則是彎刀杆。

Form tools. Form tools have edges especially manufactured to take a certain form, which is opposite to the desired shape of the machined workpiece.

成形刀具：成形刀具有專門製成特定形狀的刀刃，這種刀刃形狀與被加工工件所需外形正好相反。

An HSS tool is usually made in the form of a single piece, contrary to cemented carbides or ceramic, which are made in the form of tips. The latter are brazed or mechanically fastened to steel shanks．

高速鋼刀具通常以單件形式製造，而硬質合金或陶瓷刀具則以刀尖形式製造。後者用銅焊或機械方法固定於鋼質刀杆上。

Fig.11.2 indicates an arrangement of this latter type, which includes the carbide tip, the chip breaker, the pad, the clamping screw (with a washer and a nut), and the shank.

圖11.2所示為機械式固定佈置方式，它包括了硬質合金刀尖、斷屑槽、襯墊、卡裝螺桿(帶有墊圈和螺母)及刀杆。

As the name suggests, the function of the chip breaker is to break long chips every now and then, thus preventing the formation of very long twisted ribbons that may cause problems during the machining operation.

顧名思義，斷屑槽的功能就是不時地折斷長切屑，以防形成很長的可能會在機加工操作中引起問題的纏繞切屑條。

The carbide tips (or ceramic tips) can have different shapes, depending upon the machining operations for which they are to be employed. The tips can either be solid or with a central through hole, depending on whether brazing or mechanical clamping is employed for mounting the tip on the shank.

硬質合金刀尖(或陶瓷刀尖)根據採用它們的機加工操作，可以有不同的形狀。根據將刀尖裝配在刀杆上是透過用銅焊還是機械卡裝，刀尖可以是實心的或是帶有中心通孔的。

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Lathe Operations車床操作

In the following section, we discuss the various machining operations that can be performed on a conventional engine lathe.

在下面這節中，要討論的是能在傳統普通車床上進行的各種機加工作業。

It must be borne in mind, however, that modern computerized numerically controlled lathes have more capabilities and can do other operations, such as contouring, for example. Following are conventional lathe operations.

然而，必須記住現代計算機數控車床具有更多的功能並且可以進行其它操作，例如仿型。下面是傳統車床的操作。

Cylindrical turning. Cylindrical turning is the simplest and the most common of all lathe operations. A single full turn of the workpiece generates a circle whose center falls on the lathe axis; this motion is then reproduced numerous times as a result of the axial feed motion of the tool.

圓柱面車削：圓柱面車削是所有車床操作中最簡單也是最普通的。工件旋轉一整圈產生一個圓心落在車床主軸上的圓；由於刀具的軸向進給運動這種動作重複許多次。

The resulting machining marks are, therefore, a helix having a very small pitch, which is equal to the feed. Consequently, the machined surface is always cylindrical.

所以，由此產生的機加工痕跡是一條具有很小節距的螺旋線，該節距等於進給。因此機加工表面始終是圓柱形的。

The axial feed is provided by the carriage or the compound rest, either manually or automatically, whereas the depth of cut is controlled by the cross slide.

軸向進給透過大拖板或複式刀架手動或自動提供，然而切削深度則由橫向滑板控制。

In roughing cuts, it is recommended that large depths of cuts (up to 0.25in. or 6mm, depending upon the workpiece material) and smaller feeds would be used. On the other hand, very fine feeds, smaller depths of cut (less than 0.05in, or 0.4mm), and high cutting speeds are preferred for finishing cuts.

粗車中，推薦使用較大切削深度(根據工件材料可達0.25英寸或6毫米)和較小進給。另一方面，精車則最好採用很小的進給、較小的切削深度(小於0.05英寸或0.4毫米)和較高的切削速度。

Facing. The result of a facing operation is a flat surface that is either the whole end surface of the workpiece or an annular intermediate surface like a shoulder. During a facing operation, feed is provided by the cross slide, whereas the depth of cut is controlled by the carriage or compound rest.

端面車削：端面車削操作的結果是將工件整個端部表面或者像軸肩之類的中間環形表面加工平整。在端面車削操作中，進給由橫向滑板提供，而切削深度則透過大拖板或複式刀架控制。

Facing can be carried out either from the periphery inward or from the center of the workpiece outward. It is obvious that the machining marks in both cases take the form of a spiral.

端面車削既可以從外表面向內切削也可以從工件中心往外切削。很明顯在這兩種情況下機加工痕跡都是螺線形式。

Usually, it is preferred to clamp the carriage during a facing operation, since the cutting force tends to push the tool (and, of course, the whole carriage) away from the workpiece. In most facing operations, the workpiece is held in a chuck or on a face plate.

通常在端面車削作業時習慣於採用夾住大拖板，這是因為切削力傾向於將刀具(當然包括整個大拖板)推離工件。在大多數端面車削作業中，工件被支撐在卡盤或花盤上。

Groove cutting. In cut-off and groove-cutting operations, only cross feed of the tool is employed. The cut-off and grooving tools, which were previously discussed, are employed.

開槽：在切斷和開槽操作中，刀具只有橫向進給。要採用前面已經討論過的切斷和開槽刀具。

Boring and internal turning. Boring and internal turning are performed on the internal surfaces by a boring bar or suitable internal cutting tools. If the initial workpiece is solid, a drilling operation must be performed first. The drilling tool is held in the tailstock, and the latter is then fed against the workpiece.

鏜孔和內部車削：鏜孔和內部車削透過鏜杆或合適的內部切削刀具在內表面進行。如果初始工件是實心的，則必須首先進行鑽孔作業。鑽孔刀具安裝在尾架上，然後對著工件進給。

Taper turning. Taper turning is achieved by driving the tool in a direction that is not parallel to the lathe axis but inclined to it with an angle that is equal to the desired angle of the taper. Following are the different methods used in taper-turning practice:

錐面車削：錐面車削透過沿著與車床主軸不平行而傾斜成一個等於錐面所需角度的方向進刀來實現。下面是在實際錐面車削中採用的不同方法：

(1) Rotating the disc of the compound rest with an angle equal to half the apex angle of the cone. Feed is manually provided by cranking the handle of the compound rest. This method is recommended for taper turning of external and internal surfaces when the taper angle is relatively large.

(1) 將複式刀架盤旋轉一個等於圓錐體頂角一半的角度。透過搖動複式刀架操縱柄手動提供進給。當錐角相對較大時切削外錐面和內錐面推薦使用這種方法。

(2) Employing special form tools for external, very short, conical surfaces. The width of the workpiece must be slightly smaller than that of the tool, and the workpiece is usually held in a chuck or clamped on a face plate. In this case, only the cross feed is used during the machining process and the carriage is clamped to the machine bed.

(2) 對很短的外錐面採用特殊的成型刀具。工件的寬度必須略小於刀具的寬度，並且工件通常由卡盤支撐或夾緊在花盤上。在這種情況下，機加工作業時只有橫向進給而大拖板則夾緊在床身上。

(3) Offsetting the tailstock center. This method is employed for external taper turning of long workpieces that are required to have small taper angles (less than 8°). The workpiece is mounted between the two centers; then the tailstock center is shifted a distance S in the direction normal to the lathe axis.

(3)偏移尾架頂尖。對需要較小錐角(小於8°) 的較長工件外錐面車削採用這種方法。工件安裝於兩頂尖之間；然後將尾架頂尖朝垂直於車床主軸方向移動一距離S。

(4) Using the taper-turning attachment. This method is used for turning very long workpieces, when the length is larger than the whole stroke of the compound rest. The procedure followed in such cases involves complete disengagement of the cross slide from the carriage, which is then guided by the taper-turning attachment.

(4) 採用錐面車削附加裝置。這種方法用於車削很長的工件，其長度大於複式刀架的整個行程。在這種場合下要遵循的步驟是將橫向滑板完全脫離大拖板，然後透過錐面車削附加裝置進行引導。

During this process, the automatic axial feed can be used as usual. This method is recommended for very long workpieces with a small cone angle, i.e., 8°through 10°.

在此作業中，能照常使用自動軸向進給。對具有較小錐角(即8°到10°)的很長工件推薦採用這種方法。

Thread cutting. When performing thread cutting, the axial feed must be kept at a constant rate, which is dependent upon the rotational speed (rpm) of the workpiece. The relationship between both is determined primarily by the desired pitch of the thread to be cut.

螺紋切削：在螺紋切削作業時，軸向進給必須保持恆定速率，這取決於工件的轉速(rpm)。兩者之間的關係基本上由被切削螺紋所需的節距決定。

As previously mentioned, the axial feed is automatically generated when cutting a thread by means of the lead screw, which drives the carriage. When the lead screw rotates a single revolution, the carriage travels a distance equal to the pitch of the lead screw.

如前所述，當依靠驅動大拖板的絲桿切削螺紋時軸向進給是自動產生的。絲桿旋轉一圈，大拖板就行進等於絲桿節距的一段距離。

Consequently, if the rotational speed of the lead screw is equal to that of the spindle (i.e., that of the workpiece), the pitch of the resulting cut thread is exactly equal to that of the lead screw.

因此如果絲桿的旋轉速度等於心軸的轉速(即工件的轉速)，生成切削螺紋的節距就正好等於絲桿的節距。

The pitch of the resulting thread being cut therefore always depends upon the ratio of the rotational speeds of the lead screw and the spindle: Pitch of the lead screw/ Desired pitch of workpiece=rpm of the workpiece/rpm of lead screw=spindle-to-carriage gearing ratio.

所以被切削生成螺紋的節距總是取決於絲桿和心軸的轉速比：絲桿的節距/工件所需節距=工件轉速/絲桿轉速=心軸到大拖板的傳動比。

This equation is useful in determining the kinematic linkage between the lathe spindle and the lead screw and enables proper selection of the gear train between them.

這公式在決定車床心軸和絲桿之間的運動學關係時很有用，並且提供了正確挑選它們之間輪系的方法。

In thread cutting operations, the workpiece can either be held in the chuck or mounted between the two lathe centers for relatively long workpieces. The form of the tool used must exactly coincide with the profile of the thread to be cut, i.e., triangular tools must be used for triangular threads, and so on.

在螺紋切削作業中，工件既能支撐於卡盤中，對相對較長的工件也能安裝在兩個車床頂尖之間。使用的刀具外形必須正好與要切削螺紋的輪廓一致，即三角形刀具必須用於三角形螺紋等等。

Knurling. Knurling is mainly a forming operation in which no chips are produced. It involves pressing two hardened rolls with rough filelike surfaces against the rotating workpiece to cause plastic deformation of the workpiece metal.

滾花：滾花主要是一種不產生切屑的成型操作。它使用兩個帶有粗銼式表面的淬火滾輪壓在旋轉的工件上使工件金屬產生塑性變形。

Knurling is carried out to produce rough, cylindrical (or conical) surfaces, which are usually used as handles. Sometimes, surfaces are knurled just for the sake of decoration; there are different types of patterns of knurls from which to choose.

滾花用於生成粗糙的圓柱(或圓錐)面，通常用來作手柄。有時表面滾花只為裝飾之故；有不同的滾花圖案型別可供選擇。

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Cutting Speeds and Feed切削速度和進給

The cutting speed, which is usually given in surface feet per minute (SFM), is the number of feet traveled in the circumferential direction by a given point on the surface (being cut) of the workpiece in 1 minute.

切削速度，通常用每分鐘表面英尺給出，就是一分鐘內工件(被切削)表面給定點在圓周方向上行進的英尺數。

The relationship between the surface speed and rpm can be given by the following equation: SFM=πDN

Where

D=the diameter of the workpiece in feet

N=the rpm

表面速度與轉速之間的關係可以用下式給出：

SFM=πDN

式中

D=用英尺表示的工件直徑

N=轉速

The surface cutting speed is dependant primarily upon the material being machined as well as the material of the cutting tool and can be obtained from handbooks, information provided by cutting tool manufacturers, and the like.

表面切削速度主要由被切削材料和切削刀具材料決定，可以從手冊、切削刀具生產商提供的資料及類似的東西上查取。

Generally, the SFM is taken as 100 when machining cold-rolled or mild steel, as 50 when machining tougher metals, and as 200 when machining softer materials. For aluminum, the SFM is usually taken as 400 or above. There are also other variables that affect the optimal value of the surface cutting speed.

一般而言，SFM當機加工冷軋或低碳鋼時取100，機加工較堅韌的金屬時取50，而機加工較軟材料時取200。對鋁而言，SFM通常可取400以上。也還存在其它一些變數影響表面切削速度的最佳值。

These include the tool geometry, the type of lubricant or coolant, the feed, and the depth of cut. As soon as the cutting speed is decided upon, the rotational speed (rpm) of the spindle can be obtained as follows:

N=SFM/(πD)

其中包括刀具形狀、潤滑劑或冷卻液的型別、進給和切削深度。切削速度一旦確定，心軸轉速(rpm)就能按下式得到：

N=SFM/(πD)

The selection of a suitable feed depends upon many factors, such as the required surface finish, the depth of cut, and the geometry of the tool used. Finer feeds produce better surface finish, whereas higher feeds reduce the machining time during which the tool is in direct contact with the workpiece.

合適進給的選擇取決於許多因素，例如所需表面光潔度、切削深度和所用刀具的幾何形狀。進給越小生成的光潔度越好，而在刀具與工件直接接觸時進給越大則可以減少機加工時間。

Therefore, it is generally recommended to use high feeds for roughing operations and finer feeds for finishing operations. Again, recommended values for feeds, which can be taken as guidelines, are found in handbooks and in information booklets provided by cutting tool manufacturers.

所以對粗車一般推薦使用較大進給，而精車則用較小進給。再者，作為指導方針的進給推薦值可以從手冊和切削刀具生產商提供的資料小冊子上找到。

Unit 12 Drilling and Drills

鑽削和鑽頭

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Drilling and Drills鑽削和鑽頭

Drilling involves producing through or blind holes in a workpiece by forcing a tool, which rotates around its axis, against the workpiece.

鑽削就是透過迫使繞自身軸線旋轉的切削刀具進入工件而在其上生成通孔或盲孔。

Consequently, the range of cutting from that axis of rotation is equal to the radius of the required hole. In practice, two symmetrical cutting edges that rotate about the same axis are employed.

因此，從旋轉軸線開始的切削範圍等於所需孔的半徑。實際上，使用的是兩條圍繞相同軸線旋轉的對稱切削刃。

Drilling operations can be carried out by using either hand drills or drilling machines. The latter differ in size and construction. Nevertheless, the tool always rotates around its axis while the workpiece is kept firmly fixed. This is contrary to drilling on a lathe.

鑽削作業既能採用手鑽也能採用鑽床來實現。鑽床在尺寸和結構上雖有差別，然而始終都是切削刀具圍繞自身軸線旋轉、工件穩固定位的形式。這正好與在車床上鑽孔相反。

Cutting Tool for Drilling Operation

In drilling operations, a cylindrical rotary-end cutting tool, called a drill, is employed. The drill can have either one or more cutting edges and corresponding flutes, which can be straight or helical.

用於鑽削作業的切削刀具

在鑽削作業中，要用到被稱為鑽頭的圓柱形迴轉端切削刀具。鑽頭可以有一條或多條直的或是螺旋狀的切削刃以及相應的出屑槽。

The function of the flutes is to provide outlet passages for the chips generated during the drilling operation and also to allow lubricants and coolants to reach the cutting edges and the surface being machined. Following is a survey of the commonly used drills.

出屑槽的功能是給鑽削作業中產生的切屑提供排出通道，並允許潤滑劑和冷卻液到達切削刃和正在被加工的表面。下面是常用鑽頭的概述。

Twist drill. The twist drill is the most common type of drill. It has two cutting edges and two helical flutes that continue over the length of the drill body, as shown in Fig.12.1. The drill also consists of a neck and a shank that can be either straight or tapered.

麻花鑽：麻花鑽是最常用的鑽頭型別。它有兩條切削刃和兩條沿鑽頭體全長連續的螺旋狀出屑槽，如圖12.1所示。麻花鑽還包括鑽頸和鑽柄，鑽柄可以是直的也可以是錐形的。

In the latter case, the shank is fitted by the wedge action into the tapered socket of the spindle and has a tang, which goes into a slot in the spindle socket, thus acting as a solid means for transmitting rotation.

錐形鑽柄透過楔入動作安裝在主軸的錐形軸孔中，鑽柄上還有柄舌插入主軸軸孔中的插槽，從而作為傳遞轉動的可靠方法。

On the other hand, straight-shank drills are held in a drill chuck that is, in turn, fitted into the spindle socket in the same way as tapered shank drills.

另一方面，直柄鑽頭用鑽頭卡盤夾住，接下來鑽頭卡盤則象錐形鑽柄鑽頭一樣安裝在主軸軸孔內。

As can be seen in Fig.12.1, the two cutting edges are referred to as the lips, and are connected together by a wedge, which is a chisel-like edge. The twist drill also has two margins, which enable proper guidance and locating of the drill while it is in operation.

如圖12.1所示，兩條切削刃就是鑽唇，透過鑿子狀邊緣的楔形體連在一起。麻花鑽還有兩條導向邊，用於作業中鑽頭的正確導向和定位。

The tool point angle (TPA) is formed by the two lips and is chosen based on the properties of the material to be cut. The usual TPA for commercial drills is 118°, which is appropriate for drilling low-carbon steels and cast irons.

兩條鑽唇形成鑽頂角，並根據被鑽削材料的效能來選取其大小。商品化鑽頭的鑽頂角一般為118°，這適用於鑽削低碳鋼和鑄鐵。

For harder and tougher metals, such as hardened steel, brass and bronze, larger TPAs (130°or 140°) give better performance. The helix angle of the flutes of the commonly used twist drills ranges between 24°and 30°. When drilling copper or soft plastics, higher values for the helix angle are recommended (between 35°and 45°).

對於更硬更韌的金屬，諸如淬火鋼、黃銅和青銅，更大的鑽頂角(130°或140°)才能有更好的效果。麻花鑽常用的出屑槽螺旋角範圍為24°到 30°。鑽削紫銅或軟塑膠時，推薦採用更大的螺旋角(35°到45°)。

Twist drills are usually made of high-speed steel, although carbide-tipped drills are also available. The sizes of twist drills used in industrial practice range from 0.01 up to 3.25 in. (i. e., 0.25 up to 80 mm).

雖然也有硬質合金刀尖的鑽頭，麻花鑽一般用高速鋼製成。工業實際中使用的麻花鑽尺寸範圍為0.01到3.25英寸(即0.25到80毫米)。

Core drills. A core drill consists of the chamfer, body, neck, and shank, as shown in Fig.12.2. This type of drill may have either three or four flutes and equal number of margins, which ensure superior guidance, thus resulting in high machining accuracy.

空心鑽：空心鑽包括斜面、鑽頭體、鑽頸和鑽柄，如圖12.2所示。這類鑽頭可以有三條或四條出屑槽及相同數量的保證良好導向的導向邊，這樣使得加工有高精度。

It can also be seen in Fig.12.2 that a core drill has flat end. The chamfer can have three or four cutting edges or lips, and the lip angle may vary between 90°and 120°.

在圖12.2中同樣能看到，空心鑽具有平坦的端部。斜面可以有三或四條切削刃或鑽唇，並且鑽唇角可以在90°到120°之間變化。

Core drills are employed for enlarging previously made holes and not for originating holes. This type of drill is characterized by greater productivity, high machining accuracy, and superior quality of the drilled surfaces.

空心鑽用於擴大已有的孔而不是打孔。這類鑽頭具有較大生產率、高加工精度和優良鑽削表面質量的特性。

Gun drills. Gun drills are used for drilling deep holes. All gun drills are straight-fluted, and each has a single cutting edge. A hole in the body acts as a conduit to transmit coolant under considerable pressure to the tip of the drill.

深孔鑽：深孔鑽用於鑽深孔。所有深孔鑽都是直出屑槽的，並且均為單切削刃。鑽頭體中有個孔作為導管在相當大的壓力下將冷卻液傳送到鑽頭頂端。

There are two kinds of gun drills, namely, the center-cut gun drill used for drilling blind holes and the trepanning drill. The latter has a cylindrical groove at its center, thus generating a solid core, which guides the tool as it proceeds during the drilling operation.

深孔鑽有兩種型別，即用於鑽盲孔的中心切削深孔鑽和套孔鑽。後者在其中心有一圓柱形溝槽，這樣能生成整體芯在鑽孔作業過程中引導鑽頭。

Spade drills. Spade drills are used for drilling large holes of 3.5 in.(90mm) or more. Their design results in a marked saving in cost of the tool as well as a tangible reduction in its weight, which facilitates its handling. Moreover, this type of drill is easy to grind.

扁平鑽：扁平鑽用於鑽削3.5英寸(90毫米)或更大的大孔。其設計使得鑽頭成本明顯節省、重量切實減輕，重量輕又使操作更方便。此外這種鑽頭容易磨利。

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Milling and Milling Cutter銑削和銑刀

Milling is a machining process that is carried out by means of a multiedge rotating tool known as a milling cutter.

銑削是採用被稱為銑刀的多刃旋轉刀具完成的機加工作業。

In this process, metal removal is achieved through combining the rotary motion of the milling cutter and linear motions of the workpiece simultaneously. Milling operations are employed in producing flat, contoured and helical surfaces as well as for thread- and gear-cutting operation.

在此工藝中，金屬去除是透過銑刀的旋轉運動和工件的直線運動的組合實現的。銑削作業既可用於生成平面、輪廓面和螺旋麵，也可用於切削螺紋和齒輪。

Each of the cutting edges of a milling cutter acts as an individual single-point cutter when it engages with the workpiece metal. Therefore, each of those cutting edges has appropriate rake and relief angles.

在銑刀切削工件金屬時，銑刀的每條切削刃都象一單獨的單刃刀具一樣作用。所以每條切削刃都適當的前後角。

Since only a few of the cutting edges are engaged with the workpiece at a time, heavy cuts can be taken without adversely affecting the tool life. In fact, the permissible cutting speeds and feeds for milling are three to four times higher than those for turning or drilling.

由於同一時間只有部分切削刃切削工件，因此可以在對刀具壽命沒有不利影響的情況下承擔重型切削。事實上，銑削允許的切削速度和進給比車削或鑽削高三到四倍。

Moreover, the quality of the surfaces machined by milling is generally superior to the quality of surfaces machined by turning, shaping, or drilling.

此外，由銑削加工的表面質量通常優於車削、刨削或鑽削加工的表面質量。

A wide variety of milling cutters is available in industry. This, together with the fact that a milling machine is a very versatile machine tool, makes the milling machine the backbone of a machining workshop.

工業上可採用的銑刀型別眾多。連同銑床是極通用機床的事實，使得銑床成為機加工車間的支柱。

As far as the direction of cutter rotation and workpiece feed are concerned, milling is performed by either of the following two methods.

至於涉及到銑刀轉動的方向和工件的進給，銑削可以透過下列兩種方法之一進行。

Up milling (conventional milling). In up milling the workpiece is fed against the direction of cutter rotation, as shown in Fig.12.3a. As we can see in that figure, the depth of cut (and consequently the load) gradually increases on the successively engaged cutting edges.

逆銑(傳統銑削)：在逆銑中，工件逆著銑刀轉動的方向進給，如圖12.3a所示。就像在此圖中能看到的那樣，切削深度(及作為結果的載荷)隨著切削刃持續進入切削而逐漸增加。

Therefore, the machining process involves no impact loading, thus ensuring smoother operation of the machine tool and longer tool life. The quality of the machined surface obtained by up milling is not very high. Nevertheless, up milling is commonly used in industry, especially for rough cuts.

所以，這種工藝沒有衝擊載荷，從而保證了機床的較平穩執行和較長壽命。透過逆銑所得機加工表面質量不是很高。然而逆銑仍經常被用在工業上，尤其是粗切削時。

Down milling (climb milling). As can be seen in Fig.12.3b, in down milling the cutter rotation coincides with the direction of feed at the contact point between the tool and the workpiece. It can also be seen that the maximum depth of cut is achieved directly as the cutter engages with the workpiece.

順銑(同向銑削)：如同在圖12.3b中看到的那樣，在順銑時刀具與工件之間接觸點上銑刀旋轉與進給方向一致。還可以看到當刀具進入工件切削時直接達到最大切削深度。

This results in a kind of impact, or sudden loading. Therefore, this method cannot be used unless the milling machine is equipped with a backlash eliminator on the feed screw. The advantages of this method include higher quality of the machined surface and easier clamping of workpieces, since the cutting forces act downward.

這會導致一種衝擊，或突然載入。因此，這種方法只有當銑床在進給螺栓上配備間隙消除器時才採用。這種方法的優點包括機加工表面質量較高和工件由於切削力向下作用而較容易夾緊。

Types of Milling Cutters

There is a wide variety of milling cutter shapes. Each of them is designed to perform effectively a specific milling operation.

銑刀的型別

銑刀的形狀型別很多。其中每種都是為有效進行特定的銑削作業而設計的。

Generally, a milling cutter can be described as a multiedge cutting tool having the shape of a solid of revolution, with the cutting teeth arranged either on the periphery or on an end face or on both. Following is a quick survey of the commonly used types of milling cutters.

通常，銑刀可以被描述為具有旋轉實體形狀並將切削齒安裝在周邊或一到兩個端面上的多刃切削刀具。下面是常用銑刀型別的快速綜覽。

Plain milling cutter. A plain milling cutter is a disk-shaped cutting tool that may have either straight or helical teeth, as shown in Fig.12.4a. This type is always mounted on horizontal milling machines and is used for machining flat surfaces.

平面銑刀：平面銑刀是一種盤狀切削刀具，它可以具有直齒或螺旋齒，如圖12.4a所示。這類銑刀總是安裝在臥式銑床上，用於機加工平面。

Face milling cutter. A face milling cutter is also used for machining flat surfaces. It is bolted at the end of a short arbor, which is in turn mounted on a vertical milling machine. Fig.12.4b indicates a milling cutter of this type.

端面銑刀：端面銑刀也可用於機加工平面。它用螺栓固定在短刀杆的端部，而短刀杆則依次安裝於立式銑床上。圖12.4b顯示了這類銑刀。

Plain metal slitting saw cutter. Fig.12.4c indicates a plain metal slitting saw cutter. we can see that it actually involves a very thin plain milling cutter.

平面金屬開槽鋸刃銑刀：圖12.4c顯示了一種平面金屬開槽鋸刃銑刀。可以看到它其實是一種很薄的平面銑刀。

Side milling cutter. A side milling cutter is used for cutting slots, grooves, and splines. As shown in Fig.12.4d, it is quite similar to the plain milling cutter, the difference being that this type has teeth on the sides. As is the case with the plain cutter, the cutting teeth can be straight or helical.

側銑刀：側銑刀用於切削狹槽、凹槽和花鍵槽。正如圖12.4d所示，它與平面銑刀十分相似，差別在於此類銑刀齒在側面。象平面銑刀的情況一樣，切削齒既可以是直的也可以是螺旋的。

Angle milling cutter. An angle milling cutter is employed in cutting dovetail grooves, ratchet wheels, and the like. Fig.12.4e indicates a milling cutter of this type.

傾斜銑刀：傾斜銑刀用於切削燕尾槽、棘輪之類的。圖12.4e顯示了這類銑刀。

T-slot cutter. As shown in Fig.12.4f, a T-slot cutter involves a plain milling cutter with an integral shaft normal to it. As the name suggests, this type is used for milling T-slots.

T型槽銑刀：如圖12.4f所示，T型槽銑刀包括了一個平面銑刀和一根垂直於它的整體軸。正像其名字所表明的，這類銑刀用於銑削T型槽。

End mill cutter. End mill cutters find common applications in cutting slots, grooves, flutes, splines, pocketing work, and the like. Fig.12.4g indicates an end mill cutter. The latter is always mounted on a vertical milling machine and can have two or four flutes, which may be either straight or helical.

端面銑刀：端面銑刀在切削狹槽、凹槽、長凹槽、花鍵槽、凹狀工件之類時均能發現其普遍應用。圖12.4g為端面銑刀。它總是安裝在立式銑床上，並具有兩到四條既可是直的也可是螺旋的長凹槽。

Form milling cutter. The teeth of a form milling cutter have a certain shape, which is identical to the section of the metal to be removed during the milling operation. Examples of this type include gear cutters, gear hobs, convex and concave cutters, and the like. From milling cutters are mounted on horizontal milling machines.

成形銑刀：成形銑刀的齒具有特定的形狀，這個形狀與銑削時要切削的那部分金屬的形狀一致。這類銑刀的例子包括齒輪銑刀、齒輪滾刀、凸形和凹形銑刀等等。成形銑刀安裝在臥式銑床上。

Materials of Milling Cutters

The commonly used milling cutters are made of high-speed steel, which is generally adequate for most jobs.

銑刀的材料

普通使用的銑刀用高速鋼製造，這對一般大多數工作已足夠。

Milling cutters tipped with sintered carbides or cast nonferrous alloys as cutting teeth are usually employed for mass production, where heavier cuts and/or high cutting speeds are required.

對大規模生產而言，因為其需要重型切削和/或高切削速度，銑刀頂端常裝有燒結碳化物或有色金屬碳合金作為切削齒。

Unit 13 Jigs and fixtures

夾具與固定裝置

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Introduction 導言

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.

已經說明了工件必須相對於切削刀具定位並確保到位。工件劃線後，仍有必要將其相對於切削運動定位，並在機加工開始前把它裝夾到位。

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 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，使用鑽模和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加工不會將加強肋、型芯等放錯位置。

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.

鑽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合，它們的不同在於鑽模在實際切削作業中還能與刀具導向方法相結合，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 operations. 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有鑽頭、鉸刀和類似的刀具；因此鑽模用於鑽削作業，而夾具用於其餘作業。夾具可以與切削刀具相對定位系統裝夾的方法結合在一起。

The advantages of jigs and fixtures can be summarised 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;

鑽模和夾具的優點可歸納如下：

1)可以省去劃線和其它測量及放樣程式；

2)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;

4)The parts will be interchangeable, and if the product sold over a wide area, the problem of spare parts will be simplified.

3)由於所有零件在較小極限範圍內是相同的，可以省掉工件的‘試裝’和銼削，所以零件裝配很方便；

4)零件具有互換性，這樣如果產品在較大範圍內銷售的話，備件問題將簡單化。

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.

螺栓孔常給螺栓留出1.5毫米或甚至3.0毫米的間隙，讀者可能會懷疑為這樣的工作制造精密鑽模的必要性。但要記住，這種鑽模一旦造好，可用於許多零部件，精確製造鑽模的額外成本可分攤在大量產品上。

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, rather 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 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.

1) 工件的定位：圖13.1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。相對於三根互相垂直的座標軸XX、YY和ZZ來考慮這些自由度。

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. 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.

此物體能沿三根座標軸的任意一根移動；這樣就具有三個平移自由度。它也能圍繞三根座標軸的任意一根迴轉；這樣它又具有三個旋轉自由度。總的自由度數目是六個。當工件被定位時，必須儘可能多地消除這些自由度，以保證作業按要求精度進行。

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.

除非有必要採用另外定位要素的其它考慮，精度可透過儘可能早地加工合適的定位要素並採用它們進行所有定位來保證。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 clamping forces must not be so great as to cause the workpiece to become distorted or damaged.

2) 工件的裝夾：裝夾系統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 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.

工件必須在裝夾點下被支撐，以保證這些力由鑽模或夾具的主框架來承受並傳遞給機器臺和床身。在設計鑽模和夾具時，要同時設計裝夾系統來保證提供恰當的裝夾力，並使裝夾操作快速而安全。

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Definition of a Drill Jig鑽模的定義

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.

鑽模是一種確保在工件正確位置進行鑽孔、攻絲或鉸孔加工的裝置。

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夾持裝置組成，鑽孔作業中鑽頭穿過這些襯套，透過它們來導向。

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.

如果工件結構比較簡單，鑽模可夾持在工件上。然而大多數情況下，工件由鑽模來夾持，並且把鑽模設計成能將工件迅速裝入而在加工後同樣能很快取出。

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. 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.

相對於用常規的手工方法加工孔，鑽模使得鑽孔、鉸孔和攻絲速度快很多而且精度更高成為可能。另一個優點是採用鑽模時不需要熟練工人。保證孔定位精度的責任從操作者身上轉移到了鑽模上。

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.

鑽模這個術語只用在服務於鑽孔、鉸孔或攻絲的裝置上。它不固定在使用它的鑽床上，它能在鑽床工作臺上到處移動以使每個襯套都直接位於鑽頭下。鑽模有形地限制和控制鑽削刀具的路徑。

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.

如果作業還包括其它象銑削、刨削、成型、車削等機加工，則應採用夾具這一術語。夾具在機加工作業時夾持工件，但它不象鑽模那樣包含引導切削刀具的特殊佈置。

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Typical Jigs and Fixtures典型的鑽模和夾具

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.

典型的鑽模：圖13.2所示為一個能在某工件的法蘭上鑽四個孔的鑽模，該工件除了這四個孔外已全部完成。

The workpiece has an accurately machined bore, and is located from the bore and the end face, from a cylindrical post. 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.

此工件有一精確機加工的大孔，因此透過一圓柱體採用該孔和工件端面定位。由於直至鑽這些小孔時，工件都對稱於大孔軸線，所以沒必要控制圍繞大孔軸線迴轉的位置。

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.

四個控制鑽頭的襯套裝在鑽板裡，連同手擰螺母一起用於靠著夾具基座夾持工件。

Typical 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.

典型的銑削夾具：圖13.3所示為一用於在圖示其它工序都完成的工件上銑槽的簡單銑削夾具。此工件採用其基座上四孔中的兩孔和基座的底面定位。

The workpiece is clamped in position, and cutter is located against the setting block, which provides setting or cutter position and depth of cut.

工件被夾持到位，銑刀靠著提供安裝或銑刀位置及切削深度的安裝臺定位。

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).

夾具必須相對於銑床工作臺定位，這可透過把夾具底部的兩個凸榫插入工作臺上的槽中來實現。夾具用T型螺栓固定於銑床工作臺，同時與工作臺上的槽接合(圖13.3)。