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1、Who invented it? The archimedes screw, a spiral screw turned inside a cylinder, was once commonly used to lift water from canals. The screw is still used to lift water in the Nile delta in Egypt. 分类：紧固、传动、微调、读数。 在精密仪器或机床中，丝杠即是传动元 件，同时又是长度基准，身兼二职。所 以加工精度要求很高。 d-螺纹大径 d1-螺纹小径 d2-螺纹中径 p-螺距 n-线数 S-导程 -螺纹
2、升角，牙型角 -牙型斜 角旋向 1 、普通螺纹(代号：M GB 192-81) 特点：螺纹的牙型角=2=60。因牙型 角大，所以当量摩擦系数大，自锁性能 好，主要用于联接 细牙螺纹与粗 牙螺纹 粗牙：常用 细牙的缺点：牙小，相同载荷下磨损快，易 脱扣 细牙：自锁性能更好。常用于承受冲击、振 动及变载荷、或空心、薄壁零件上及微调装 置中 2 、矩形螺纹 特点：牙形为正方形， =0，所以效率高， 用于传动,牙根强度弱，加工困难（刀难做）， 常被梯形螺纹代替 3 、梯形螺纹(代号：T 特点： =2=30。比矩形螺纹效率略低。 牙根强度高，易于对中，易于制造，剖分螺母 可消除间隙，在螺旋传动（机床）中
3、有广泛应用。 r GB 192-81) 4、 锯齿形螺纹(代号：S JB 923- 66) 特点：工作边=3，非工作边=30，便于加工。 它综合了矩形螺纹效率高和梯形螺纹牙根强度高的 优点,能承受较大的载荷,但只能用于单向传动 5 、圆柱管螺纹 特点：用于管件联接的三角螺纹，=55 螺纹面间没有间隙，密封性好，适用于压强在 1.6MPa以下的联接 6、 圆锥螺纹 特点：螺纹均布在锥度为1:16的管上,=55或60 螺纹面间没有间隙，不用填料，靠牙变形，密封性 好，适用于高温、高压的联接 螺栓联接/紧固 普通螺栓联接 绞制孔螺栓联接 普通螺栓联接 螺栓和孔壁有间隙 孔的加工精度低 绞制孔螺栓联接
4、 螺杆与孔用过渡配 合，承受轴向载荷 孔需精制 可起定位作用 螺钉联接 特点：被联接件不宜做成通 孔。 不宜经常拆卸。 拧入深度： 铜或青铜：H=d 铸 铁：H=1.251.5d 铝 合 金： H=1. 52.5d Micrometer（测量螺纹） The micrometer is a basic precision measuring tool. It follows Abbe Principle. To a machinist, this tool is indispensable. Above: The continuous-drive lathe of 1568 eliminated
5、 the back-and-forth rotation of the workpiece, produced by pole- and-treadle lathe, but required the services of a helper to turn a drive wheel. German clock-makers screw- cutting lathe c. 1480, showing (below) the tool-holder on cross slide. Above: These sketches by Leonardo da Vinci show several r
6、emarkable innovations in machine design. The lathe at left has a treadle, a crankshaft and a large flywheel. The tailstock spindle can be adjusted by a hand crank. The device at right is a screw-cutting machine (not strictly a lathe), which has a set of change gears for cutting threads of various pi
7、tches. Henry Maudslay(1771-1831) 亨利 莫兹利 Henry Maudslay was no doubt a talented thinker and machinist, The illustration at left shows the lathe he built after setting up business for himself in 1797. It has the familiar prismatic bed, or rather beds, with a leadscrew between them. There is evidence t
8、hat the leadscrew was designed to be interchangeable, not only to allow different pitches of thread to be cut, but also to allow a hand-cut master thread to be used to generate a more robust and accurate replacement leadscrew. The lathe was later fitted with change- gears to allow changes of pitch.
9、The cross slide is graduated, and the saddle has a split nut to engage and disengage it. Like Ramsden before him, Maudslay went to infinite pains to obtain accurate threads for leadscrews. He tried all known methods and finally settled on the inclined knife. The knife was mounted on a prismatic guid
10、eway on a swivelling toolholder. The oblique incision made by the knife in soft metal or wood carried it along the blank cylinder of the work as it was rotated, and by adjusting the inclination of the tool, a groove of any pitch could be cut. Using this groove as a basis, the thread was then cut by
11、hand. Maudslays second great contribution was the appreciation that in the quest for precision, true plane surfaces are almost as important as accurate screw threads. He introduced the use of surface plates and hand scraping. （ 刮削和研磨平板）These techniques were put to use in building his second lathe,a
12、flat bed model, illustrated here. This solid, well designed machine was built in 1800, and was followed by a micrometer in 1805. The first lathe was used to cut the permanently mounted leadscrew of the second, which was equipped with 28 change wheel and a travelling steady. In his third lathe, he co
13、mbined prismatic and flat guideways(今天的车床就是这样的配置), and stepped drive pulleys. He was able to machine a brass screw 7 feet long with an error in length of only 1/16 from the computed length. Still not satisfied, he devised a linkage like that of Thiout to correct this slight error, producing an accur
14、ate thread 5 feet long with a pitch of 50 tpi which was used to calibrate astronomical instruments. Threads like these made possible Maudslays micrometer, nicknamed the Lord Chancellor“, reputedly accurate to 1/10000 of an inch.2.5微米 他的老师是约瑟夫 .布拉马, 他的工厂培养了很多英国机械工 业的骨干,比如约瑟夫 .惠特沃斯Whitworth, Joseph (平
15、板/标 准螺纹/测长机) Sir Joseph Whitworth 1803-1887 In 1821 Whitworth moved to Manchester where he found work as a mechanic. Four years later he moved to London where he trained under Henry Maudslay. After returning to Manchester in 1833 he set up his own machine shop. Probably his most important innovation
16、 was to devised a machine capable of measuring to an accuracy of one hundredth-thousandth of an inch. Since the beginning of the industrial revolution, each workshop used its own sizes for the equipment it made. By 1860 Whitworths specifications for sizes of screw threads was generally accepted throughout Britain. Whitworth was deeply concerned with working class poverty and donating large sums of money to educational organizations. He also su
