ChainDriveNew机械设计英文重大PPT学习教案

1、会计学1ChainDriveNew机械设计英文重大机械设计英文重大Power transmission chains can be categorized as1.Roller chain2.Silent chain 3.Engineering steel chain4.Detachable chain.传动链传动链 起重链起重链 牵引链牵引链 齿形齿形链链 链链滚子链滚子链 第1页/共30页pins that pivot inside the roller bushings.pins are press fitted into the pin link platesroller bushin

2、gs are press fitted into roller link platesfree-turning roller encircles each bushing to provide rolling engagement and contact with sprocket teethThe distance between flexing joints in roller chain is the pitch(链节距), which is the basic designation for different chain sizes.Roller chain第2页/共30页2.Joi

3、nts (2.Joints (联接链节联接链节) )Axial positioning methodsAxial positioning methods：(Spring Pins)(Spring Pins)开口销，开口销，多用于大节距链多用于大节距链(Spring U board)(Spring U board)弹簧卡片弹簧卡片，多用于小节距链多用于小节距链设计时，链节数以取为偶数设计时，链节数以取为偶数(Even)(Even)为宜，这样可避免使用过为宜，这样可避免使用过渡链节渡链节(Offset link bar)(Offset link bar)，因为，因为过渡链节会使链的承载能力下降过渡

4、链节会使链的承载能力下降。过渡链节过渡链节第3页/共30页3.3.滚子链的规格滚子链的规格 标记示例：标记示例： 08A-186 GB1243.183 第4页/共30页Multi-Strands roller chainDouble-pitch roller chainBecause a given length of double-pitch chain contains only half as many pitches, it is lighter and less expensive than standard roller chain.Another choice for high

5、power transmissionChoice for long shaft distance transmission第5页/共30页Center guide chainSide guide chainSilent chain (无声链)第6页/共30页Where the transmission of high power is the primary requirement, engineering steel drive chains offer many useful solutions.Engineering steel chain(工程链)Standard types:1.he

6、avy duty offset sidebar engineering steel roller chain2.heavy duty straight-sidebar roller-type conveyor chain主要用于重型传送装置第7页/共30页Advantages1.detachable links can be separated at any joint without using special tools2.Detachable chain is low in cost and can transmit up to 25 hp at speeds to 350 fpm.De

7、tachable chain（可拆链）Detachable link chains are fabricated with one-piece elements and can be press-formed from flat rolled steel,结构简单、可不用特殊工具安装、拆卸第8页/共30页Chordal action (弦切现象或多边形效应)Characters of chain drive第9页/共30页二、瞬时二、瞬时速度和速度和瞬时瞬时传动比传动比链条铰链链条铰链A A点的前进分速度：点的前进分速度： cos11rv 上下运动分速度：上下运动分速度： sin11rv 因为

8、从动链轮的角速度为：因为从动链轮的角速度为： coscoscos21122rrrv 所以链传动瞬时传动比为：所以链传动瞬时传动比为： coscos1221rri 第10页/共30页当主动链轮匀速转动时，从动链轮的角速度以及链传动的瞬当主动链轮匀速转动时，从动链轮的角速度以及链传动的瞬时传动比都是周期性变化的，因此链传动不宜用于对运动精度有时传动比都是周期性变化的，因此链传动不宜用于对运动精度有较高要求的场合。较高要求的场合。由上述分析可知，链传动中，链条的前进速度和上下抖动速由上述分析可知，链传动中，链条的前进速度和上下抖动速度是周期性变化的，链轮的节距越大，齿数越少，链速的变化就度是周期性变

9、化的，链轮的节距越大，齿数越少，链速的变化就越大。越大。Speed variation character第11页/共30页 d d= = p p/sin(180/sin(180 / /z z) ) Keep Keep p p constantconstant，z z d d Elongation of chain after wearingDesign limitation of sprockets due to chordal actionFor driving sprockets1.1.For the same pitchFor the same pitch， when Z decrea

10、sewhen Z decrease，power loss due to flexing increasepower loss due to flexing increase，joints elements wear fasterjoints elements wear faster；2.2. For the same pitch, when Z decreaseFor the same pitch, when Z decrease，D D decreasesdecreases，larger force must be larger force must be sustained by chai

11、n to transmit the same sustained by chain to transmit the same powerpower（2T/D2T/D）Jump teeth occursFor driven sprockets第12页/共30页通常限制链传动的传动比通常限制链传动的传动比i6i6，推荐的传动比，推荐的传动比i i23.523.5。 17min1 ZZ120max212 ZiZZ为磨损均匀，为磨损均匀，Z Z应取与链节数互为质数的奇数。应取与链节数互为质数的奇数。 第13页/共30页Advantages of chain drives over belt drive

12、s are: No slippage between chain and sprocket teeth. Negligible stretch, allowing chains to carry heavy loads. Long operating life expectancy because flexure and friction contact occur between hardened bearing surfaces separated by an oil film. Operates in hostile environments such as high temperatu

13、res,high moisture or oily areas, dusty, dirty, and corrosive atmospheres, etc., especially if high alloy metals and other special materials are used. Long shelf life because metal chain ordinarily doesnt deteriorate with age and is unaffected by sun, reasonable ranges of heat, moisture, and oil. Cer

14、tain types can be replaced without disturbing other components mounted on the same shafts as sprockets.第14页/共30页Drawbacks of chain drives that might affect drive system design are: Noise is usually higher than with belts or gears, but silent chain drives are relatively quiet. Chain drives can elonga

15、te due to wearing of link and sprocket teeth contact surfaces. Chain flexibility is limited to a single plane whereas some belt drives are not. Usually limited to somewhat lower-speed applications compared to belts or gears. Sprockets usually should be replaced because of wear when worn chain is rep

16、laced. V-belt sheaves exhibit very low wear.第15页/共30页Coiler driveDrive for a roller-supported drum with a diameter of approx. 2 m and a length of 9 mRoller conveyorBoard slitter sawsynchronously drivenApplications第16页/共30页Shaft center distanceIn general, the preferred range of center distance for ro

17、ller chain drives that allow adjustable center distances is 30 to 50 chain pitches. Roller chain drives with fixed centers should be limited to about 30 pitches.Minimum center distance must allow clearance between the teeth of the two sprockets.Arc of chain engagement should not be less than 120 deg

18、中心距的合理选择General consideration for arrangement of chain drive design第17页/共30页Very long center distances cause excessive tension and may cause the chain to jump teeth.Long chains may need to be supported by guides or idlers.Idler Sprocket第18页/共30页链传动的链传动的合理布置合理布置（1 1）Vertical planeVertical plane（2 2）S

19、lope angle should be less than 45Slope angle should be less than 45 （3 3）Keep slack side in the bottom sideKeep slack side in the bottom sideGeneral consideration for arrangement of chain drive design第19页/共30页Allowable Power for roller chainAllowable Power for roller chain链传动的承载能力链传动的承载能力 链传动的承载能力是以

20、链的强度和寿命为依据的。链传动的承载能力是以链的强度和寿命为依据的。 1. 1. 极限功率曲线极限功率曲线 0由链板疲劳强度限定由滚子、套筒冲击疲劳强度限定由销轴和套筒胶合限定额定功率额定功率P P0 0/kW/kW小链轮转速小链轮转速n n1 1 /(r/min)/(r/min)第20页/共30页2.A2.A系列套筒滚子链的实用功率曲线图系列套筒滚子链的实用功率曲线图实验条件实验条件：单列：单列, ,水平布置水平布置, ,载荷平稳载荷平稳, Z, Z1 1=19, i=3, =19, i=3, t=100P, tt=100P, th h=15000h, =15000h, P/P 3%P/P

21、3%设计时可根据小链轮的设计时可根据小链轮的转速转速n n1 1从图中查出这种型号从图中查出这种型号的链条允许传递的额定功率的链条允许传递的额定功率P P0 0，额定功率曲线适合于链，额定功率曲线适合于链速速v0.6m/sv0.6m/s的场合。的场合。当链传动实际工作条件当链传动实际工作条件与标准实验条件不符时，应与标准实验条件不符时，应考虑工作情况系数考虑工作情况系数K KA A、链长、链长、小链轮齿数、多排链等因、小链轮齿数、多排链等因素的影响。素的影响。额定功率曲线是在推荐额定功率曲线是在推荐的润滑方式下得到的，当不的润滑方式下得到的，当不能满足推荐的润滑方式时，能满足推荐的润滑方式时，

22、应降低额定功率应降低额定功率P P0 0。Pitch selection第21页/共30页人工定期润滑人工定期润滑滴油润滑滴油润滑油浴或飞溅润滑油浴或飞溅润滑压力喷油润压力喷油润滑滑 推荐的润滑方式推荐的润滑方式Recommended Lubrication method第22页/共30页三、链传动主要参数的选择三、链传动主要参数的选择 1 1链的节距和排数链的节距和排数 链条所能传递的功率链条所能传递的功率P P0 0可由下式确定可由下式确定 P Pc c= =K KA AP P(10(1031) 31) PLZcKKKPP 0(10(1030) 30) 式中式中 P P0 0在特定条件下，

23、单排链所能传递的功率在特定条件下，单排链所能传递的功率(kW)(kW)（见图见图102727）；）；P Pc c链传动的计算功率链传动的计算功率(kW)(kW)；K KA A工况系数（表工况系数（表10101212）；）；K KZ Z小链轮齿数系数（表小链轮齿数系数（表101313，当工作在如图，当工作在如图102727所示的曲线顶点左侧时（所示的曲线顶点左侧时（链板疲劳），查表中的链板疲劳），查表中的K KZ Z，当工作在右侧时（滚子套筒冲击疲劳），查表中的，当工作在右侧时（滚子套筒冲击疲劳），查表中的K K Z Z；K KP P多排链系数（表多排链系数（表101414）；）；K KL L链

24、长系数（图链长系数（图10102929），链板疲劳查曲线），链板疲劳查曲线1 1，滚子套筒冲击疲劳查曲线，滚子套筒冲击疲劳查曲线2 2。 根据式（根据式（10103030求出传递的功率，由图求出传递的功率，由图10102727查出合适的链号和链节距。查出合适的链号和链节距。 第23页/共30页例例10-210-2 设计如图设计如图10-3110-31所示的带式运输机传动方所示的带式运输机传动方案中的滚子链传动。已知小链轮转速案中的滚子链传动。已知小链轮转速n n1 1=123r/min=123r/min，传动比，传动比i i=3=3，传递功率，传递功率P P6.85kW6.85kW，两班制工作

25、，两班制工作，中心距可调节，载荷平稳。中心距可调节，载荷平稳。 第24页/共30页解解：1 1选定链轮齿数选定链轮齿数z z1 1、z z2 2初步假设链速初步假设链速v=v=0.60.6 3m/s3m/s，由表，由表10101515查得小链轮齿数查得小链轮齿数z z1 11717，取，取z z1 1=19=19，z z2 2= =iziz1 1=3=319=57 (12019=57 (120合适合适) )。 2 2根据实用功率曲线，选链条型号根据实用功率曲线，选链条型号 （1 1）初定中心距）初定中心距a a0 0=40=40p p，链节数，链节数L LP P为为 92.11814. 321

26、957402571940222222120210 ppppzzapzzpaLp 取取L LP P118118节。由于中心距可调，可不算实际中心距。节。由于中心距可调，可不算实际中心距。 估计，链条链板可能产生疲劳破坏。由表估计，链条链板可能产生疲劳破坏。由表10101313查得查得K KZ Z1.01.0，由表，由表10101414查得查得K KP P=1.0=1.0（初取单排链），由图（初取单排链），由图10102929查得查得K KL L1.051.05，由表，由表10101212查得查得K KA A1.01.0。 第25页/共30页该链条在实验条件下所需传递的功率该链条在实验条件下所需传

27、递的功率 kW52. 60 . 105. 10 . 10 . 185. 60 PLZAPLZcKKKKPKKKPP由由图图10102727，按，按P P0 06.52kW6.52kW，n n1 1=123r/min=123r/min，选取链条，选取链条型号为型号为20A20A，p p=31.75mm=31.75mm，且，且P P0 0与与n n1 1交点在曲线顶点左侧，交点在曲线顶点左侧，确系链板疲劳破坏，估计正确。确系链板疲劳破坏，估计正确。 3 3校核链速校核链速 m/s24. 110006075.311231910006011 pnzv与原假设与原假设v v=0.63m/s=0.63m/s范围符合。