仪器制造技术-螺纹精加工

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-螺纹中径螺纹中径p-螺距 n-线数 S 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细牙螺纹与粗 牙螺纹牙螺纹粗牙：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）中有广泛应用。 r G

3、B 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螺杆与孔用过渡配合，承受轴向载荷孔需精制可起定位

4、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. 52.5dMicrometer（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 the back-and-forth rotation of the wo

5、rkpiece, 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 remarkable innovations in machine design.

6、 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 pitches. Henry Maudslay(1771-1831)亨利 莫兹利He

7、nry 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 that the leadscrew was designed to be inter

8、changeable, 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. The cross slide is graduated, and the saddl

9、e 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 guideway on a swivelling toolholder. The obliqu

10、e 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 hand. Maudslays second great contribution w

11、as 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 flat bed model, illustrated here. This solid

12、, 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 combined prismatic and flat guideways(今天的车床就是这

13、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 accurate thread 5 feet long with a pitch of 50 tp

14、i 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 (平板/标准螺纹/测长机)Sir Joseph Whitworth1803-1887In 18

15、21 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 was to devised a machine capable of measuring to

16、 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 wi

17、th working class poverty and donating large sums of money to educational organizations. He also supplied the funds for engineering scholarships research at technical colleges. Sir Joseph Whitworth died in 1887. 常用的加工螺纹方法常用的加工螺纹方法 攻螺纹、攻螺纹、 滚压螺纹、滚压螺纹、 套螺纹、套螺纹、 铣螺纹、铣螺纹、 车螺纹车螺纹 磨螺纹。磨螺纹。攻螺纹（攻螺纹（tappingta

18、pping） （攻丝）：用丝锥加（攻丝）：用丝锥加工内螺纹；工内螺纹；套螺纹套螺纹(chasing) (chasing) (套丝或套扣套丝或套扣) )：用板牙：用板牙加工外螺纹。加工外螺纹。主要用来加工精度要求低、直径较小的三主要用来加工精度要求低、直径较小的三角螺纹。常用于加工角螺纹。常用于加工M16M16以下的普通螺纹，以下的普通螺纹，最大一般不超过最大一般不超过M50M50。单件和小批生产：由钳工在虎钳上进行，单件和小批生产：由钳工在虎钳上进行，或在车床或钻床上进行；或在车床或钻床上进行；大批量生产：攻螺纹常在攻丝机上进行。大批量生产：攻螺纹常在攻丝机上进行。1.1.攻螺纹和套螺纹攻螺纹

19、和套螺纹车削螺纹车削螺纹(thread turning)(thread turning)可在各类卧式车床或专门可在各类卧式车床或专门的螺纹车床上进行，由于刀具简单，故广泛用于各种的螺纹车床上进行，由于刀具简单，故广泛用于各种精度的未淬硬工件的螺纹加工。精度的未淬硬工件的螺纹加工。2.2.车螺纹车螺纹单齿螺纹车刀：结构简单，适应性广，可单齿螺纹车刀：结构简单，适应性广，可加工各种形状、尺寸及精度的未淬硬工件加工各种形状、尺寸及精度的未淬硬工件的内、外螺纹，但生产率低，适用于单件的内、外螺纹，但生产率低，适用于单件小批生产。小批生产。螺纹梳刀：实际上是多齿成形车刀。一次螺纹梳刀：实际上是多齿成形车

20、刀。一次走刀就能加工出全部螺纹，效率高，适用走刀就能加工出全部螺纹，效率高，适用于大批生产细牙螺纹。一般螺纹梳刀加工于大批生产细牙螺纹。一般螺纹梳刀加工精度不高，不能加工精密螺纹。精度不高，不能加工精密螺纹。螺纹梳刀的类型a)平体 b)棱体 c)圆体 铣螺纹铣螺纹(thread milling)(thread milling)比车螺比车螺纹生产率高，但螺纹精度低，在纹生产率高，但螺纹精度低，在成批大量生产中广泛采用。成批大量生产中广泛采用。 铣螺纹一般在专门的螺纹铣床上铣螺纹一般在专门的螺纹铣床上进行。进行。 3.铣螺纹1 1）盘形铣刀铣螺纹）盘形铣刀铣螺纹 加工时，铣刀轴线对工加工时，铣刀轴

21、线对工件轴线的倾斜角等于螺件轴线的倾斜角等于螺纹升角，工件转一转，纹升角，工件转一转，铣刀走一个工件导程。铣刀走一个工件导程。 适合加工大螺距的长螺适合加工大螺距的长螺纹，如丝杠、螺杆等梯纹，如丝杠、螺杆等梯形外螺纹和蜗杆等。形外螺纹和蜗杆等。 加工精度较低，通常作加工精度较低，通常作为粗加工，铣后用车削为粗加工，铣后用车削进行精加工。进行精加工。2 2）梳形铣刀铣螺纹）梳形铣刀铣螺纹 加工时，工件每转一转，加工时，工件每转一转，铣刀除旋转外，还沿轴向铣刀除旋转外，还沿轴向移动一个导程，工件转移动一个导程，工件转1.251.25转，便能切出全部螺转，便能切出全部螺纹（最后的四分之一转主纹（最后

22、的四分之一转主要是修光螺纹）。要是修光螺纹）。 生产率高，螺距精度可达生产率高，螺距精度可达9 98 8级，表面粗糙度级，表面粗糙度R Ra a值值为为3.23.20.63m0.63m。 适合成批加工一般精度并适合成批加工一般精度并且长度短而螺距不大的三且长度短而螺距不大的三角形内、外螺纹和圆锥螺角形内、外螺纹和圆锥螺纹。纹。3）旋风铣刀铣螺纹利用装在特殊旋转刀盘上的多利用装在特殊旋转刀盘上的多把硬质合金刀头（一般为把硬质合金刀头（一般为1 14 4把）或梳刀，从工件上高速铣把）或梳刀，从工件上高速铣出螺纹的方法出螺纹的方法旋风铣生产效率高，一般比盘旋风铣生产效率高，一般比盘形铣刀铣螺纹高形铣

23、刀铣螺纹高2 28 8倍。倍。加工长度大、不淬硬的外螺纹，加工长度大、不淬硬的外螺纹，如丝杠、螺旋送料杆、大模数如丝杠、螺旋送料杆、大模数蜗杆、注塑机螺杆等长工件；蜗杆、注塑机螺杆等长工件；也可加工大直径（也可加工大直径（32mm32mm以上）以上）的内螺纹，如滚珠丝杠螺母、的内螺纹，如滚珠丝杠螺母、梯形丝杠螺母、环形槽等；尤梯形丝杠螺母、环形槽等；尤其适合加工无退刀槽、有长键其适合加工无退刀槽、有长键槽和平面的螺纹件。槽和平面的螺纹件。 1 1）搓板滚压）搓板滚压 两块搓板都带有螺纹齿形，其截面形状两块搓板都带有螺纹齿形，其截面形状与待搓螺纹牙型相符，上搓板为动板，与待搓螺纹牙型相符，上搓板

24、为动板，下搓板固定不动为静板，动板作平行于下搓板固定不动为静板，动板作平行于静板的往复直线运动。静板的往复直线运动。 工件在两板之间被挤压和滚动，当动板工件在两板之间被挤压和滚动，当动板移动时，坯料表面便挤压出螺纹。移动时，坯料表面便挤压出螺纹。2 2）. .滚轮滚压：滚轮滚压：滚丝机滚丝机 工件放在两个带有螺纹齿形的滚轮之间的支工件放在两个带有螺纹齿形的滚轮之间的支承板上，两滚轮等速转动，其中一轮轴心固承板上，两滚轮等速转动，其中一轮轴心固定，一轮作径向进给运动，工件在滚轮摩擦定，一轮作径向进给运动，工件在滚轮摩擦力带动下旋转，表面受径向挤压而形成螺纹。力带动下旋转，表面受径向挤压而形成螺纹

25、。 滚螺纹的生产率低于搓螺纹，但精度高滚螺纹的生产率低于搓螺纹，但精度高于搓螺纹。这是因为滚丝轮热处理后可于搓螺纹。这是因为滚丝轮热处理后可在螺纹磨床上精磨，而搓丝板热处理后在螺纹磨床上精磨，而搓丝板热处理后精加工困难。精加工困难。 搓螺纹可加工直径为搓螺纹可加工直径为3 324mm24mm、螺纹长度、螺纹长度小于小于120mm120mm的螺钉、双头螺栓、木螺钉、的螺钉、双头螺栓、木螺钉、自攻螺钉等；自攻螺钉等； 滚压螺纹适用于直径滚压螺纹适用于直径3 380mm80mm、螺纹长度、螺纹长度小于小于120mm120mm的双头螺栓、螺钉、锥形螺纹、的双头螺栓、螺钉、锥形螺纹、蜗杆、丝锥等的加工。

26、蜗杆、丝锥等的加工。 滚压螺纹与切削螺纹相比，主要优点是滚压螺纹与切削螺纹相比，主要优点是提高了螺纹的强度。提高了螺纹的强度。 切削加工的螺纹纤维组织是被割断的，切削加工的螺纹纤维组织是被割断的，而滚压螺纹的纤维组织是连续的，从而而滚压螺纹的纤维组织是连续的，从而提高了其剪切强度；提高了其剪切强度； 螺纹滚压后，由于表面变形强化及表面螺纹滚压后，由于表面变形强化及表面粗糙度值降低，还可提高螺纹的疲劳强粗糙度值降低，还可提高螺纹的疲劳强度。度。 滚压螺纹比切削螺纹的生产率高。滚压螺纹比切削螺纹的生产率高。 Ball Screw带反馈丝杠驱动提示：丝杠传动分三种，开环/半闭环/闭环，三坐标怎么传动，工作台和测量机有何本质的区别螺纹磨床精密车削中刀具的安装螺距误差1