机械英语Unit2MachineParts

1、Unit 2 Machine PartsFastenersVocabularylfastenerl联接件 lnaill钉子lscrewl螺钉lnutl螺帽lboltl螺栓llocknutl锁紧螺帽lwasherl垫圈lretaining ringl挡圈lrivetl铆钉ladhesivel粘合剂lrivnutl 铆钉llock washerl锁紧垫圈llocknutl锁紧螺帽lmetal stitchingl金属钉合lcreep in the boltl螺栓内部蠕动lloss of resiliencel弹性丧失lthermal expansionl热膨胀lwearl磨损laxial load

2、l轴向载荷lvibration forcel振动力lslotted nutl开槽螺帽lcotter pinl开口销ldiameterl直径lclearancel间隙lself-locking nutl自锁螺帽lthreadl螺纹lpitch diameterl中径lclampl夹钳lfrictional forcel摩擦力lnonmetallic-insert typel非金属嵌入型lelastic locking mediuml弹性锁紧介质lbolt loadingl螺栓载荷lseall密封lmoisturel湿气lself-tapping screwl自攻丝螺钉ldrive screwl传

3、动螺杆lcastingl铸件llead holel导孔lcutting threadl切削螺纹lforming threadl成形螺纹lholding powerl保持力lself-piercing screwl自开孔螺丝lmachine screwl机用螺钉lsetscrewsl止动螺钉lcap screwsl铆螺钉lshaftl轴长lshankl杆ldeformationl变形lthread-type fastenerl螺纹型联接件laluminuml铝lbucking barl铆钉顶棒lhydraulic pressurel液压lpneumatic pressurel气动压力lrivet

4、ing machinel铆接机limproperly formedl成形不当lstressl应力lsolid rivetl实心铆钉ltubular / hollow rivetl管形/空心铆钉lsemitubular rivetl半管形铆钉lswaged rivetl挤压铆钉lsplit rivetl开口铆钉lblind rivetl埋头铆钉lMonel metall蒙乃尔合金lbrassl铜lcorrosionl腐蚀lanodic coatingl阳极化镀层lbrazier headl扁头lstreamlined piecesl流线型工件Classification:FastenersTra

5、ditional: nuts, bolts, washers New:rivnuts, retaining ringsFastenersTemporary:nuts, bolts etc.Permanent:rivets, adhesives etc.The commonest means of joining materials:l Types: nuts, bolts, screwsl Advantage: attain maximum effectiveness at the lowest possible costl an ordinary nut loosens: vibration

6、 frictionl nut + lock washerl 1. supplies an independent locking feature preventing the nut from looseningl 2. is useful only when the bolt might loosen because of a relative change between the length of the bolt and the parts assembled by itThe factors cause the relative change between the length:l

7、1. creep in the boltsl2. loss of resiliencel3. difference in thermal expansion between the bolt and the bolted membersl4. wearSlotted nut + cotter pinldiameter:l pin the hole in the boltl pin the slot in the nutlvibration:l can make the nut back off until the clearances are reduced and the cotter pi

8、n jams the assemblySelf-locking nutltop threads of the bolt are manufactured at a reduced pitch diameterlpitch diameter is smaller and smallerlit can produce greater frictional forces than an ordinary nutNonmetallic-insert type (locknut)l The elastic locking medium in this nut is independent of bolt

9、 loading.l advantage: it can seal the bolt threads against external moisture or leakage of internal pressure or liquidsl disadvantage: high / elevated temperature can affect the functionHow to join such things? l1. sheet metal + plastic / woodl2. one side of work is blindl3. the application of nuts

10、to bolts becomes practically impossiblel lself-tapping screw & drive screw Self-tapping & drive screwlBoth of them need lead holes.lself tapping screw:lspecially designed threads (cutting / forming) suitable to the applications.lall kinds of standard head forms are available (slotted / with

11、a recess)ldrive screw:lholding power is greater than a nailldriven with a hammerlcan be backed out with a screw driverSelf-piercing screwlAttaching wood panels to light structural parts without having to drill lead holes.lhammer - inlscrew driver - turn downMachine screws / Cap screwslFor fastening

12、metallic elements.lmachine screws: lare usually threaded the full length of the shaft / applied with a screwdriverlcap screws:lare threaded for only part of the shanklsquare / hexagonal / knurled headsSetscrews lare threaded for the length of the shaft and may be either headed or headlessl l usually

13、 fluted or providedl with a slot or hexagonal l socket for drivinglsetscrews are used to secure machine tools / some machine element in a precise settingRivets - permanent fastenersldepending on deformation of their structure for their holding powerlAdvantages:l1. stronger than the threaded-type fas

14、tenerl2. more economical on a first-cost basislCan be driven either hot / cold depending upon mechanical properties of the rivet material.Riveting methods:lhammer + bucking bar:lbucking bar - heading rivetslhammer - hammered the other endlsqueeze:lmechanical / hydraulic / pneumatic pressurel the riv

15、ets l(between the jaws of a compression tool)lriveting machines:lproduction runs are largerDifferent rivetslsolid rivets (with chamfered shanks)l require great strengthltubular rivets l are used in the fastening of leather braceslhollow rivetslsemitubular rivetslswaged rivetslsplit rivets - making of suitcaseslblind rivetsDifferent materialslaluminum alloys: l saving in weight / resistant to corrosionl anodic