有关带式输送机驱动装置设计的一些研究-外文翻译

1、出自:the south african institute of materials handling有关带式输送机驱动装置设计的一些研究j.h. rail理工学硕士，汉森变速器（控股）有限公司董事p. staples理工学硕士，输送机知识与信息科技（控股）有限公司（ckit）董事、总经理摘要：这是是一篇关于探讨运送大量颗粒物质的动力和平板橡胶输送带之间的驱 动装置的综述。它关注的是大批量的物料输送，而不是像喂料或计量输送带，大 倾角式输送机等特殊情况。它主要研究电机联轴器和驱动滚筒之间的减速器，带 速，轴承寿命，使用因数，制动器和逆止器等。1.概述地球原材料的消耗越来越多，那就需要很快地将

2、这些材料从一个地方转移 到使用它的地 方，而且要通过一定的工艺来运输这些物料并且要在最短的时间 内处置废物。许多物料输送的方法是从轮手推车送到自卸卡车或接送的车辆上， 或是依靠一定的空气流在空气导管中进行散料输送。这种输送方式中，在限制成 木的前提下，在可靠的长距离的物料输送中带式输送机发挥了非常重要的作用。每一种物料输送都有其优点和缺点。带式输送机的问题之一是，输送带柔软 易降解，特别是在装货和卸货的时候。如果维持整体尺寸是很重耍的话，那么照 口前的技术來说这在复杂的输送系统屮是很困难。输送系统已变得越来越大，越来越复杂，驱动系统也已经历一个演进过程 而且会继续演进下去。大带要求很大的驱动力

3、。不仅需要更大的独立驱动装置，同时也需要多驱动 装置比如一个带需要4个各1000kw功率的驱动器。完整驱动装置中轴的安装是 另一个变化，它要求更紧凑重量更轻的驱动装置。这往往倾向于在输送带和硬齿 面齿轮旁边配置一个直角驱动器来减小驱动器的尺寸和质量。2.传动比与带速根据待输送物料的数量，规模，输送距离和其特点的不同决定了带的吸收 功率，宽度，拉伸要求和厚度等。大部分的传送带带速范围在26m/s,并且由带允许的弯曲半径决定了托辘 的直径。大型传送带的托辗直径在0.81. 5m之间，托辗速度在50125rpm之 间。假设使用4极电机，这能提供12:130:1之间需要的减速比。大部分的齿轮制造商不会

4、采用过高的传动比，每级传动比不超过5:1,这意 味着将会是23级减速。（除小功率的蜗杆减速器或是扭矩臂和v带驱动器可 能会使用）。有一种误解以为减速器使用6或8极电机可以降低成本，但即使是8极电极 能有更高的速度，且每级减速比超过6:1,这样仍然需要2级传动。大部分变速 器的成本与低速轴的扭矩有关系。因此，只要确定了这一点，除了使用了4极电 机以外使用其他任何电机相比之下都是没有任何经济优势可言的。由于受到规 模和数量的限制，一般对电机制造商来说提供的4极电机的价格最低。因此作为 选择电机的一条原则，为了达到要求的传动轴速度，4极电机是最佳选择了。电动机使用球轴承和滚子轴承的一些制造商喜欢6极

5、甚至8极的转速，能给 屯机提供超过1000千瓦的功率。3.1选择单个或多个驱动器在计算岀驱动皮带所需功率和皮带张力和包角之后就可决定就带是否应装 有一个或多个驱动器。这一决定往往受安装在工厂的数倍于经常使用的小驱动器等设备的影响。 驱动器的大小也可能由最近可用的标准电动机决定。如果一个驱动器离主要动力 源有相当的距离，那么就要用一根长的电缆来连接电机和驱动器。这样一来，在 选择我们使用的电机的数量和尺寸时电缆尺寸和变压器的成本就可能发挥一个 很重要的作用。随着电机的启动，电动机的峰值电流可能是6相满载电流。一个 屯机或一组电机的运行电流与最后一个电机启动时的启动电流z间的联系对驱 动器的选择会

6、有很强的影响。3.2低速轴的连接从减速器到皮带轮轴的传动一种是通过与安装在构架旁边的基础部件上的 驱动装置的“弹性”耦合来实现，一种是通过挂在带轮轴上的驱动装置的轴來实 现。驱动装置可以安装空心轴，通过摩擦锁合原理来驱动或是安装实心轴用一个 刚性联轴器将其与输送机轴连接起来以实现驱动。附件中给出了一些典型的附属 装置草图。（见附录a ）。4.1起动方法、驱动器的大小和保护装置的选择在启动传送带吋，通常涉及到一个需要加速的相当大的质量。为了缩短电 机达到启动电流的时间，需要在减速器和驱动电机之间安装一个“滑动联轴器”。 另外，滑环电动机的使用，实现了通过控制电机的峰值电流以实现快速且柔性启 动。

7、功率10kw以下的小带直接在线器启动采用直接耦合是很正常的，但对于100 千瓦以下的带来说采用“滑动联轴器”是最常见的，而且可能是最简单和成本效 益最大的。采用较大的驱动器来获得需要的功率会持续的增加成本，在这种情况 下滑环电机就可能引起了人们的注意，因为它能预防用电高峰期，特别是在最高 电力需求需要支出大量电费的时候。市场上有很多种与d. 0. l.启动机配套使用的滑动联轴器，但对于较大的输 送带来说多数使用液体耦合器，无论是连续牵引或是延迟填补牵引或是可控填补 填补牵引（杓子式）。流力耦合器总是会做少量的“滑动”以帮助多个驱动器共 担负载，并且提供了精确调整过的耦合“填补”。一般来说，每个

8、耦合器都略有 各自不同的特点，如果止确调整分担载荷，在满载条件下将有可能比轻载条件下 不适当的分担载荷更好。电机的特点也各不相同，这有助于多个驱动器分担负荷。 驱动系统通常都是每带最多4个电机，但只用很少的会用更多的电机。4. 2电动机起动（d. 0. l.与液力偶合器多个驱动器启动的一般做法是先启动次级驱动器电机35秒钟后在启动另 一个主级电机，持续510秒钟后启动下一个主级电机。然而，在实践中观察到启动开始后和理想状态有一个时间延迟。一个非常常 见的现象是观察到次级驱动电机由于保守耦合的选择，启动电流有所下降，但很 快又开始上升，由于延迟填补耦合增加了它的滑动力矩，而带依然平稳。如果主 级

9、驱动器是在耦合扭矩大幅度增加之前的正确时间启动的，带就会在过低电流状 态下带速増加。联轴器的相对滑移影响到它的扭矩和电机电流，而且很快带就可 以启动了，峰值电流很快也将下降。在杓子式液力偶合器中所有电机都很快成功的启动然后所有联轴器开始缓 慢填补。滑环电动机也采用类似的的方式启动。这两种方法无疑对皮带，皮带轮 是有利的方式。采用杓子式液力偶合器或滑环电机有可能使较小型电机的使用更安全和开 关装置维修成本的节省。4. 3其他驱动器方法如果要求输送率变化的，那么直流驱动器可以当作鼠笼电动机來实现变频控 制。另一种方法是用水文静态驱动器，但大功率驱动器的运行和维护费用上很可 能会高于釆用sc电机液力

10、偶合驱动器和或滑环电动机。4.4带保护带保护是为了防止超载和失控。其做法通常是通过皮带下方的托辘驱动的 离心开关来实现的。然而，这并不是现在使用的非常灵敏和最尖端的方法。一种恰当的方法是在驱动变速箱低速轴上安装一个脉冲发牛器，皮带驱动的 托辗上装上类似的脉冲发生器。监测器能不断的检测脉冲频率，如果输送带跑偏 的话它就会给出警报或直接使带停下来。通过使用监测器来控制滑环电动机的启 动能将带的跑偏滑动控制在最低限度内。监测器可控制转子电阻继而控制起动转 矩。5.带式输送机制动5. 1正向制动一般说来，摩擦会降低皮带正常前进的速度并增加负载使其在相对较短的 时间内停止。停车时间的长短主要取决于卸料结

11、束条件。如果一个带给另一个带 送料是，平稳的条件，转载仓的大小和带的布局可能会需要一个制动带的其他方 法而不是靠正常的摩擦。一般来说向下卸料或是向上输送的带都需要制动。如果一个输送带输送部分 比输送机其它部分长很多的话，输送斜槽就可会超载甚至可能是遭到破坏，但这 种情况很少出现。先初步根据输送带的布局（见附录b ）在变速箱高速轴上装制动器，可以 看到，当又载荷的情况下停止的时候载荷的惯性往往会依靠重力拉紧和释放驱动 器和前部带轮z间带的张紧力，英至带还可能会松弛。反转时驱动器因制动器作 用而不动，但负载会在重力的作用下使带加速。而当驱动器和头部滚筒张紧时， 就会使因负载而加速的带由于长距离输送

12、之间的摩擦力而减缓下来。在这种根据 负载突然停止的时候驱动器会受到剧烈冲击。在这种情况下，制动不仅是不必要 的，而且是极不可取的。安装在卸料带的制动器将再次释放驱动器和头部滚筒z间的张紧力，但这往 往会释放正在运行（或停止）的带轮的张力，并使得带有滑动。这对皮带和带轮 有害，而且也是很危险的。制动带正确的方法像是这样的：在带尾部滚筒或反转 时的其它滚筒上采取行动。另一个制动器有时会用到的方法有时用一个移动堆垛机来制动皮带，以减少 带的刮伤；带固定的时候堆垛机应能够移动。但在尾部滚筒上仍然要装一个制动 器，在驱动器或输送机头部安装一个钳制器。附件:from : the south african

13、 institute of materials handlingbelt conveyor drives - a consideration ofsome design aspectsj.h. rail pr.eng., bsc eng., msaime hansen transmissions(pty) ltdp. staples pr.eng bsc, msaimemanaging director conveyor knowledge and informationtechnology (pty)ltd (ckit)summary:this is a short review of pa

14、rt of the link between the electric power grid and flat rubber covered belts used for transporting large volumes of granular material. it is concerned with high volume material conveying and not with special cases such as feed or metering conveyors, steep inclined conveyors etc. it considers mainly

15、the speed reducer between motor coupling and drive pulley, ratings, bearing life, service factors, stopping and anti-runback devices1 generalthe ever increasing rate of consumption of earth's raw materials has brought with it a need for faster movement of these material from the point of extract

16、ion to the point of process or usage and transporting these materials through the process plant and disposing of the waste in the shortest possible time. many methods of material handling are employed from wheel barrows to dump trucks or shuttle cars, to pneumatic ducts carrying pulverised particles

17、 in an air stream. in this line of movement, belt conveyors play a very important part in the reliable canying of material over long distances at a competitive costeach method of material conveying has its advantages and disadvantages. one of the problems with belt conveyors is that soft friable mat

18、erial can be degraded, particularly in loading and unloading. if the maintenance of lump size is important, this can present difficulties on a complicated conveyor system.conveyor systems have become larger and more complex and drive systems have also been going through a process of evolution and wi

19、ll continue to do so.bigger belts require more power and has brought the need for larger individual drives as well as multiple drives such as 4 drives of 1000 kw each on one belt. shaft mounting of the complete drive unit is another change which has brought with it the requirement for more compact a

20、nd lighter drive units. this tends to favor a right angle drive configuration with the motor next to the belt and hardened gears to reduce the dimensions and mass of the drive.2. drive ratio and belt speedsdepending on the quantity, size, distance and characteristics of the material to be conveyed,

21、the absorbed power, width, tensile requirements and top cover thickness of the belt will be decidedlarge volume conveyor belts run in the range of 2 to 6 metre/second and the allowable bend radius of the belt determines pulley diameters which for large belts is of the order of 0,8 to 1,5 m giving pu

22、lley speeds between 50 and 125 rpm<assuming that 4 pole motors are used, this gives a reduction ratio required between 12:1 and 30:1.most modern gear manufacturers do not use a higher ratio per stage than 5:1, which means that speed reducers will be either 2 or 3 stage reduction. (except for smal

23、l powers where worm reducers, or torque arms and v belt drives may be used).there is a misconception that one can reduce the cost of the gear-speed reducer by using a 6 or 8 pole motor, but even an 8 pole motor on the higher speeds would require a reduction above 6: land a 2 stage unit would still b

24、e required. the bulk of the cost of a gearbox is related to the low speed shaft torque and therefore having determined this, there is generally no economic advantage at all in using anything but a 4 pole motor. the motor manufacturers, because of size and volume, generally supply 4 pole motors at th

25、e lowest price, and as a rule therefore, a 4 pole motor is the best choice with a gearbox of the appropriate ratio to arrive at the desired conveyor shaft speed.where ball and roller bearings are used in the electric motors some manufacturers prefer 6 pole or even 8 pole speeds for motors over 1000

26、kw.3.1. choice of single or multiple drivehaving calculated the power required to drive the belt and having considered the belt tension and angle of contact, a decision can be taken on whether the belt should be fitted with single or multiple drive.this decision is often influenced by other equipmen

27、t installed in a plant and multiples of other smaller drives are often used. drive size may also be determined by the nearest standard motor available. where a drive point is situated some considerable distance from the main power source, a long cable may be involved to supply electric power to the

28、drive. in this case, the cable size and cost of transformers may play an important part in the selection of number and size of motors used. with direct on line starting, the peak current the motor will draw is likely to be of the order of 6 x full load current and the combination of running cuitent

29、of a motor or group of motors with the starting current of the last motor to start will have a strong influence on the drive choice.32 method of low speed shaft connectionsdrive from the reducer to the belt pulley shaft is either by ”flexible” coupling from a drive pack mounted on a foundation next

30、to the structure or by shaft mounted drive unit hanging on the pulley shaft. when shaft mounted, the drive unit can be either hollow shaft, driving through a friction locking element or solid shaft attached by a rigid coupling to the conveyor shaft. some typical attachments are shown in the sketches

31、. (see appendix a).41 choice of starting method, drive size and protectionduring start up of conveyor belts, a considerable mass is usually involved which requires acceleration, and to reduce the length of time that the motor draws starting current, a "slip couplingn is fitted between the drive

32、 motor and speed reduce匸 alternatively,slip ring motors are used to achieve a quick but gentle start up with control of the peak current. on small belts below lokw direct on line starting directly coupled is quite normal and on belts, say below 100 kw d.o.l. starting with "slip" couplings

33、is most common, and probably the simplest and most cost effective. on larger drives with power at its present continuously increasing cost, slip ring motors may be attractive, due to the prevention of the peak, pailicularly where maximum demand plays a part in the electricity tariff.there is a multi

34、tude of slip couplings on the market for use with d.o.l. start motors, but for larger belts the majority in use are liquid type couplings, either straight traction or traction with delayed fill or controllable fill (scoop type). a fluid coupling will always "slip” a small amount and will help m

35、ultiple drives to share load, provided the coupling "fill” has been carefully adjusted. as a rule, each coupling has a slightly different characteristic and if adjusted to share load correctly under full load conditions will more than likely not share properly under light load conditions. motor

36、 characteristics also vary a little and can also contribute to poor load sharing on multiple drives. drive systems commonly go up to 4 motors per belt, but rarely more.4.2. motor starting: (d.o.l. with fluid coupling)on multiple drives accepted practice is to start the motor on the secondary drive f

37、irst and say 3-5 seconds later one of the primary drive motors and then the next primary motor say 5-10 seconds later.in practice, however, the observed starting procedures and delay times vary a great deal. a very common sight is to see the secondary drive motor running and due to conservative coup

38、ling selection, the starting current drops somewhat, but starts rising quickly again due to the delayed fill coupling increasing its slip torque, while the belt remains stationary. if a primary drive is started at the correct time before the coupling torque has increased too far, the belt is brought

39、 into motion much quicker with a lower overall cuirent. the relative slip of the coupling affects it's torque and so the motor current, and the sooner the belt can be moved, the sooner the current peaks will drop.in the case of scoop controlled fluid couplings all motors are started in quick suc

40、cession and then all couplings filled slowly. a similar procedure is followed with slip ring motors and these two methods are undoubtedly the kindest to the belt, pulley and lagging etc.the choice of scoop type fluid couplings or slip ring motors is likely to lead to the use of smaller motors with s

41、afety and possible savings on switch gear maintenance.4.3. other drive methodswhere a variable conveying rate is required, d.c. drives can be used as well as squirrel cage motors with frequency control. another method is by hydro-static drive; again ideal for variable speed, but overall running and

42、maintenance costs on big powers are likely to be higher than a fluid coupling drive, with s.c. motor or slip ring moto匚4.4. belt protectionbelt protection against overload and stalling is commonly done by a centrifugal switch driven by a roller on the underside of the belt. this, however, is not ver

43、y sensitive and more sophisticated methods are now used.one method consists of fitting a pulse generator to the drive gearbox low speed shaft and similar pulse generator to a roller driven by the belt. a monitoring unit compares the pulse frequencies continuously and if they go outside set limits, a

44、n alarm is given or the belt stopped. on start up, belt slip can be kept to a minimum by using the monitoring unit to control the start up on slipring motors. the monitoring unit can control the rotor resistance and so the starting torque. alternatively, the "fill” of a variable fill fluid coup

45、ling can be controlled by the comparitor.5 stopping a belt conveyor5丄 forward stoppingas a general rule, friction will reduce the normal forward speed of the belt and load and bring it to rest in a relatively short time. the allowable time for stopping depends mainly on the discharge end conditions.

46、 where one belt feeds onto another, tripping conditions, transfer bunker size and belt layout may indicate a need for a belt to be slowed down by other methods than normal friction.on a downhill section of a conveyor discharging onto a level or uphill belt is generally the place where braking is required. if one belt runs on longer than the rest of a system of conveyors, bunkers or transfer chutes can be overloaded and may even be a hazard,