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1、文档下载亿万文档 免费下载 论文 研究生考试 资格考试 IT计算机 高等教育 教学研究 经管营销 总结/汇报 工作范文 行业资料 考试资料 学术论文当前位置：文档下载 带式输送机外文翻译-煤矿输送带软启动机制的比较 免费下载此文档带式输送机外文翻译-煤矿输送带软启动机制的比较附 录英文文献A Comparison of Soft Start Mechanisms for Mining Belt ConveyorsMichael L. Nave, P.E.CONSOL Inc.1800 Washington RoadPittsburgh, PA15241Belt Conveyors are an
2、 important method for transportation of bulk materials in the mining industry. The control of the application of the starting torque from the belt drive system to the belt fabric affects the performance, life cost, and reliability of the conveyor. This paper examines applications of each starting me
3、thod within the coal mining industry.INTRODUCTIONThe drive pulley via friction between the drive pulley and the belt fabric must transmit the force required to move a belt conveyor. In order to transmit power there must be a difference in the belt tension as it approaches and leaves the drive pulley
4、. These conditions are true for steady state running, starting, and stopping. Traditionally, belt designs are based on static calculations of running forces. Since starting and stopping are not examined in detail, safety factors are applied to static loadings (Harrison, 1987). This paper will primar
5、ily address the starting or acceleration duty of the conveyor. The belt designer must control starting acceleration to prevent excessive tension in the belt fabric and forces in the belt drive system (Surtees, 1986). High acceleration forces can adversely affect the belt fabric, belt splices, drive
6、pulleys, idler pulleys, shafts, bearings, speed reducers, and couplings. Uncontrolled acceleration forces can cause belt conveyor system performance problems with vertical curves, excessive belt take-up movement, loss of drive pulley friction, spillage of materials, and festooning of the belt fabric
7、. The belt designer Is confronted with two problems, The belt drive system must produce a minimum torque powerful enough to start the conveyor, and controlled such that the acceleration forces are within safe limits. Smooth starting of the conveyor can be accomplished by the use of drive torque cont
8、rol equipment, eithermechanical or electrical, or a combination of the two (CEM, 1979).SOFT START MECHANISM EVALUATION CRITERIONWhat is the best belt conveyor drive system? The answer depends on many variables. The best system is one that provides acceptable control for starting, running, and stoppi
9、ng at a reasonable cost and with high reliability (Llewellyn and Sudarshan, 1978).Belt Drive SystemFor the purposes of this paper we will assume that belt conveyors are almost always driven by electrical prime movers (Goodyear Tire and Rubber, 1982). The belt drive system shall consist of multiple c
10、omponents including the electrical prime mover, the electrical motor starter with control system, the motor coupling, the speed reducer, the low speed coupling, the belt drive pulley, and the pulley brake or hold back (Zur, 1986). It is important that the belt designer examine the applicability of e
11、ach system component to the particular application. For the purpose of this paper, we will assume that all drive system components are located in the fresh air, non-permissible, areas of the mine, or in non-hazardous, National Electrical Code, Article 500 explosion-proof, areas of the surface of the
12、 mine.Belt Drive Component AttributesSize.Certain drive components are available and practical in different size ranges. For this discussion, we will assume that belt drive systems range from fractional horsepower to multiples of thousands of horsepower. Small drive systems are often below 50 horsep
13、ower. Medium systems range from 50 to 1000 horsepower. Large systems can be considered above 1000 horsepower. Division of sizes into these groups is entirely arbitrary. Care must be taken to resist the temptation to over motor or under motor a belt flight to enhance standardization. An over motored
14、drive results in poor efficiency and the potential for high torques, while an under motored drive could result in destructive over speeding on regeneration, or overheating with shortened motor life (Lodi, etal., 1978).Torque Control.Belt designers try to limit the starting torque to no more than 150
15、% of the running torque (Cema, 1979; Goodyear, 1982). The limit on the applied starting torque is often the limit of rating of the belt carcass, belt splice, pulley lagging, or shaft deflections. On larger belts and belts withoptimized sized components, torque limits of 110% through 125% are common
16、(Elberton, 1986). In addition to a torque limit, the belt starter may be required to limit torque increments that would stretch belting and cause traveling waves. An ideal starting control system would apply a pretension torque to the belt at rest up to the point of breakaway, or movement of the ent
17、ire belt, then a torque equal to the movement requirements of the belt with load plus a constant torque to accelerate the inertia of the system components from rest to final running speed. This would minimize system transient forces and belt stretch (Shultz, 1992). Different drive systems exhibit va
18、rying ability to control the application of torques to the belt at rest and at different speeds. Also, the conveyor itself exhibits two extremes of loading. An empty belt normally presents the smallest required torque for breakaway and acceleration, while a fully loaded belt presents the highest req
19、uired torque. A mining drive system must be capable of scaling the applied torque from a 2/1 ratio for a horizontal simple belt arrangement, to a 10/1 range for an inclined or complex belt profile.Thermal Rating.During starting and running, each drive system may dissipate waste heat. The waste heat
20、may be liberated in the electrical motor, the electrical controls, the couplings, the speed reducer, or the belt braking system. The thermal load of each start Is dependent on the amount of belt load and the duration of the start. The designer must fulfill the application requirements for repeated s
21、tarts after running the conveyor at full load. Typical mining belt starting duties vary from 3 to 10 starts per hour equally spaced, or 2 to 4 starts in succession. Repeated starting may require the debating or over sizing of system components. There is a direct relationship between thermal rating f
22、or repeated starts and costs.Variable Speed.Some belt drive systems are suitable for controlling the starting torque and speed, but only run at constant speed. Some belt applications would require a drive system capable of running for extended periods at less than full speed. This is useful when the
23、 drive load must be shared with other drives, the belt is used as a process feeder for rate control of the conveyed material, the belt speed is optimized for the haulage rate, the belt is used at slower speeds to transport men or materials, or the belt is run a slow inspection or inching speed for m
24、aintenance purposes (Hager, 1991). The variable speed belt drive will require a control system based on some algorithm toregulate operating speed.Regeneration or Overhauling Load.Some belt profiles present the potential for overhauling loads where the belt system supplies energy to the drive system.
25、 Not all drive systems have the ability to accept regenerated energy from the load. Some drives can accept energy from the load and return it to the power line for use by other loads. Other drives accept energy from the load and dissipate it into designated dynamic or mechanical braking elements. So
26、me belt profiles switch from motoring to regeneration during operation. Can the drive system accept regenerated energy of a certain magnitude for the application? Does the drive system have to control or modulate the amount of retarding force during overhauling? Does the overhauling occur when runni
27、ng and starting?Maintenance and Supporting Systems.Each drive system will require periodic preventative maintenance. Replaceable items would include motor brushes, bearings, brake pads, dissipation resistors, oils, and cooling water. If the drive system is conservatively engineered and operated, the
28、 lower stress on consumables will result in lower maintenance costs. Some drives require supporting systems such as circulating oil for lubrication, cooling air or water, environmental dust filtering, or computer instrumentation. The maintenance of the supporting systems can affect the reliability o
29、f the drive system.Cost.The drive designer will examine the cost of each drive system. The total cost is the sum of the first capital cost to acquire the drive, the cost to install and commission the drive, the cost to operate the drive, and the cost to maintain the drive. The cost for power to oper
30、ate the drive may vary widely with different locations. The designer strives to meet all system performance requirements at lowest total cost. Often more than one drive system may satisfy all system performance criterions at competitive costs.Complexity.The preferred drive arrangement is the simples
31、t, such as a single motor driving through a single head pulley. However, mechanical, economic, and functional requirements often necessitate the use of complex drives. The belt designer must balance the need for sophistication against the problems that accompany complex systems. Complex systems requ
32、ire additional design engineering for successful deployment. An often-overlooked cost in a complex system is the costof training onsite personnel, or the cost of downtime as a result of insufficient training.Multiple Drives.A simple belt is often driven by one drive pulley. Multiple, independent pul
33、leys drive some more complex belts. These pulleys may be near each other, or at different belt locations. Multiple drives allow the belt designer to increase the driven horsepower, while maintaining or reducing belt fabric tensions. Multiple drives require a drive starting and running system that al
34、lows for coordination between drives. Multiple drives of different sizes or different belt wrap angles may require a load proportion scheme (load sharing). Load sharing requires one of the drives to operate at a lower torque rating during starting, or also during running conditions. Will the multipl
35、e drive belt system operate with one or more prime movers out of service? Multiple drives at different locations will require a distributed control system (Gallina, 1991; Sur, 1987).Conveyor Jam.It is possible for a running belt conveyor to encounter a mechanical jam of the belt fabric. The drive sy
36、stem will continue to impart torque to the fabric up to the slip of the fabric on the drive pulley. Different drives vary in the application of breakdown torque to the stalled machine. It is important for the drive designer to examine the rotating inertia in the drive system. The prime mover motor r
37、otor and all other rotating parts may contribute significant kinetic energy to the stalled belt. The drive response to the stall and the application of the torque limit may vary.Control System.Each drive system will require a base case permissive control system for starting and running supervision.
38、Most belt drive systems today use some form of computer control. The computer control systems all depend on field sensors for measurement and reporting of drive parameters. The belt drive designer must determine the minimum required number and location of the field devices for adequate control. The
39、drive control system will require power switchgear and control switchgear with provisions for lockout for conveyor maintenance and service. Lockout applies to sources of electrical, hydraulic, pneumatic, and gravity energy.SOFT START METHODS OVERVIEWThe system approach will group the electrical prim
40、e mover with control, the high and low speed couplings, the speed reducer, and the drive pulley for examination. The belt conveyor will require a force to initiate movement, termed breakaway torque. In movement, the conveyor willrequire torque to support existing motion and torque to support acceler
41、ation to running speed within the time and thermal limits imposed by the system. The resultant acceleration is proportional to the applied force divided by the mass in the system according to Newtons second law, where the mass is the system equivalent weight, or external inertia, divided by the forc
42、e of gravity. More commonly, the belt designer will calculate the Wk, or the weight of the system times the square of the radius of gyration. It is important that the designer add the drive system external inertia to the belt system inertia in order to view total system inertia. System inertias are
43、modeled at the rotating speed of the electrical prime mover, or at the linear speed of the belt fabric. All system external inertias must be referred to a common base (Harper, 1960).下一页Word文档免费下载：带式输送机外文翻译-煤矿输送带软启动机制的比较（下载1-7页，共10页）我要评论TOP相关主题 软启动 输送带 输送机 软启动器 螺旋输送机 皮带输送机 刮板输送机 带式输送机相关内容外文翻译- 带式输送机及
44、其牵引系统带式输送机及其牵引系统 在运送大量的物料时,带式输送机在长距离的运输中起到.统需耍更大的功率,比如 3 驱动系统需耍给输送带 750KW(成庄煤矿输送 机驱动.对煤矿带式输送机常用软启动装置的比较分析对煤矿带式输送机常用软启动装置的比较分析 段慧新疆煤炭设计研究院有限责任公司 【摘要】井下带式输送机目前正朝着高速度、大运量、大功率、 长距离的方向发展.外文翻译- 带式输送机及其牵引系统中文原文: 带式输送机及其牵引系统 在运送大量的物料时,带式输送机在长距离的.统需耍更大的功率,比如 3 驱动系统需耍给输送带 750KW(成庄煤矿输送 机驱动.外文翻译-带式输送机技术的最新发展外文翻
45、译-带式输送机技术的最新发展外文翻译-.图 7- Wyodak 煤矿 隧道式如通过没有水平曲线线路.这样的输送机输送带与托辊之间的重力和摩擦力保证原.外文翻译-带式输送机技术的最新发展带式输送机文献综述 8页 10财富值 外文翻译带式.图 7- Wyodak 煤矿 隧道式如通过没有水平曲线线路.这样的输送机输送带与托辊之间的重力和摩擦力保证.带式输送机英文翻译外文翻译-带式输送机技术. 51页 20财富值 带式输送机外文翻译 12页 .常用软启动器以减少在启动时的皮带张力, 此外,他们还减少能源消耗9。一般.外文翻译带式输送机及其牵引系统更大的功率,比如 3 驱动系 统需耍给输送带 750KW
46、(成庄煤矿输送机驱动系统的.的弯曲部分的输送装置中最常用的软启动装置,其结构相对比较简单,成本又低对 .带式输送机技术的最新发展外文文献翻译带式输送机技术的最新发展外文文献翻译 隐藏 .图 7- Wyodak 煤矿 隧道式如通过没有水平曲线线路.这样的输送机输送带与托辊之间的重力和摩擦力保证原.带式输送机软启动装置的选型设计煤矿机电 带式输送机软启动装置的选型设计齐海涛 (.分析和比较 , 针对 不同场合提出了软启动驱动装置.的启动力矩 , 以减小动 张力 , 改善输送带及整机.他们刚刚阅读过：七种常用的WEB服务器远 离 毒 品计算机国家二级access2010年9月笔试试卷经典英文歌曲赏析
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