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***同特性。這些特性可以通過普通車床這壹最常用的代表性類型來最好地說明。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梁的主骨架。為減振它壹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。主軸通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幹不同的速度(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，即縱向有壹通孔。如果采取連續生產，棒料能通過此孔進給。
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，它有壹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.
尾架體為壹能橫向運動的鑄件，它可以調整尾架軸線與主軸箱軸線成壹直線。第三部分，套筒軸是壹淬硬鋼管，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.
這通過使用手輪和螺桿來達到，與螺桿嚙合的是壹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鉆和鏜桿之類的工具。套筒軸通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。它實際上是壹由車床床身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.
大拖板能手動或者通過溜板箱和光桿(進給桿)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，動力通過絲桿提供給溜板箱上的齒輪箱。在其余車削作業中，都由光桿驅動大拖板。絲桿穿過壹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.
當開動特定操作桿時，剖分螺母夾在壹起作為單個螺母與旋轉的絲桿嚙合，並帶動拖板沿著床身提供進給。當操作桿脫離時，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.
另壹方面，當使用光桿時則通過蝸輪給溜板箱提供動力。 蝸輪用鍵連接在光桿上，並與溜板箱壹起沿光桿運動，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.
現代車床壹般在主軸箱下裝備快速變換齒輪箱，通過壹系列齒輪由主軸驅動。它與光桿和絲桿連接，能容易並快速地通過簡單轉換適當的操作桿選擇各種進給。
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，主軸每轉壹圈溜板箱(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。