提升系统和安全装置毕业论文外文翻译

英语原文Hoisting System And Safety DevicesThomas D.BarkandSenior Member,IEEEMine Safety And Health AdministrationPittsburgh,Pennsylvania 15236Abstract As noted,there are two main operating malfunctions which can occur in a hoist system that can kill men and damage equipment. 1. Overtravel at the shaft extremity.2.Overspeed during the duty cycle .What is required in the case just illustrated is a device that would check hoist speed far enough down the shaft so that if the conveyance were traveling too fast at that point,the hoist would “E”stop soon enough to bring the skip to a stop before it overtraveled its stopping point and did damage.This paper discusses the application of a suspension rope brake to a single rope mine hoist. Technical challenges associated with accelerated rope brake lining wear and suspension rope lubrication are addressed.HOISTING SYSTEMThe hoist together with its associated plant for an underground mine is the single most important and expensive lement of the mine plant.The hoist plant consists of all those components of mine plant that are necessary to elevate ore,coal,stone,or waste and to raise and lower personnel and materiel in the mine.It is with the hoisting system itself-these components of the hoist plant located in the hoist room-that engineering design is mainly needed.These key factors govern hoist selection:1. Production rate,or tonnage to be hoisted per unit of time2. Depth of shaft3. Number of levels to be accessedThere are basically only two hoisting methods,plus some modifications,in use today:drum and friction.The drum hoist stores the rope not extended in the shaft.The friction-sheave hoist passes the rope (or the ropes) over the drive wheel but does not store it.A minor method that has fallen into disuse is reel hoisting,in which a single width of rope is wrapped in many layers.A new method devised in South Africa for very deep shafts is multidrum hoisting using multiple ropes.DESIGN OF HOISTING SYSTEMThe design process for a mine hotsting stytem should be understood by the mining engineer,enen though the design and installation are contracted to an engineer-constructor firm and the equipment bid to a hoist manufacturer.Typically,the mining company developing the mine assigns its own engineering department to monitor the entire process,including both the planning and construction of the surface hoist plant.The design process will now be examined in detail and illustrated by a numerial example.1. Balanced hoisting.All mine hoisting systems are operated in balance to reduce moments,torque,and power demand on the hoist.Generally,two conveyances are suspended from one hoist;sometimes,when more than one level is to be serviced,a counterweight replaces one conveyance.It is designed with a weight equal to the dead load ot the skip or cage plus one half the live load.To further balance the loads,a tail rope can be installed.2. Slippage in friction sheave hoisting.Slippage occurs in a friction-sheave hoist if the ratio of the rope tensions exteeds a theoretical limit.3. Wire rope size.Wire rope has a complex structure.In designing a hoisting system,the two properties of wire rope that are most important are weight per unit length and breaking strength.Note that properties for two qualities of steel are included for round-strand and flattened-strand rope.4. Sheave and drum diameter.To minimize flexing and stressing of the wire rope as it is wound over a sheave or drum,a recommended minimum ratio of drum or sheave diameter to rope diameter should be 80100.Since the cost of wire rope is modest,there may be occasions,espcially in shallow shafts,where it is more coat-effective to select a smaller drum diameter and replace the hoist rope oftener.5. Rope fleet angle.This is the angle subtended by the hoist rope and the centerline from the idler sheave to the drum.To reduce rope abrasion in the sheave groove,the fleet angle is restricted to 11.5°.The principal effect of such a limit is to restrict the width of the drum.6. Skip size vs.hoisting velocity.To achieve a desired production rate in a shaft,the design engineer seeks a balance between skip size and hoisting velocity.The ultimate limit on skip size is rope strength,and on hoisting velocity it is energy consumption.As a compromise it is generally advantageous to hoist the large skip load possible at the lowest possible rope velocity.7. Hoisting cycle.The relationship of time to distance in hoisting is referred to as the hoisting cycle.Calculation of time and distance elements is accomplished with the following formulas:a. Acceleration time b. Acceleration distance c. Constant-velocity distance d. Constant-velocity time e. Cycle time 8. Duty cycle.The relationship between hoist motor torque requirements and hoisting cycle times is called the duty cycle.The sloping section of the drum hoist reflects the unbalanced load of the hoist rope.Integrating the area under the curve provides the energy consumption for the hoisting-duty cycles.Safety Devices-like all mechanical devices with large heavy moving parts,such as gears,drums,conveyances and motors,a mine hoist must bu protected from traveling too far in any given direction and traveling too fast.Protective devices are incorporated into a mine hoist for two reasons.The first is to protect life and limb of persons riding the cage and working in the vicinity of the shaft.The second is to protect the hoist headframe and,most important,the shaft.As noted,there are two main operating malfunctions which can occur in a hoist system that can kill men and damage equipment.These are:1. Overtravel at the shaft extremity.2. Overspeed during the duty cycle.Overtravel is defined as travel of a conveyance past the planned or programmed stopping point.This stopping point can be the dump bin in the headframe or a shaft loading pocket or cage landing. Overspeed is defined as speed in excess of that required or programmed for any particular point in the travel in the shaft.It can easily be seen why this is important by considering the case when the skip is traveling at full speed while entering the dump scrolls. Given:Travel distance in dump scrolls 20ft(6.1m) Full hoist speed 30fps(9.14m/s) Emergency-stop retard rate 7.5(2.3m/) This means that the skip would overshoot the dump bin by some 60 ft.In all likelihood it would be pulled though the top of the headframe and thus damage structural work at the shaft collar.What is required in the case just illustrated is a device that would check hoist speed far enough down the shaft so that if the conveyance were traveling too fast at that point,the hoist would “E”stop soon enough to bring the skip to a stop before it overtraveled its stopping point and did damage.There are a mumber of such devices available around the world that,when geared and driven from the hoist drum(or wheel),will provide accurate and sensitive protection of the hoist and conveyance from damage due to overtravel and overspeed.The best known and most widely used is the “Lilly Controller”,manufactured by the Logan Actuator Co.,Inc.,Chicago.INTRODUCTIONMine elevators and personnel hoists provide a lifeline for miners at more than 360 mines nationwide l. The hoisting system transports mine personnel through an isolated corridor during routine operations or life threatening emergencies. The potential risk of injury is great if the hoisting system fails. Therefore, a safe, reliable hoisting system is essential to the well being of the miners. In mining history there have been two well documented investigations of mine hoisting systems crashing in the upward direction 2, 3. These accidents occurred on counterweighted hoisting systems when the mechanical brake failed while the cage was empty. This allowed the counterweight to fall to the bottom of the shaft, causing the car to overspeed and crash into the overhead structure. The accidents were initially believed to be isolated incidents. However, research covering a 5-year period, showed there were over eighteen documented cases of ascending elevators striking the overhead structure 4.Rules and regulations applying to elevator safety have come under review in response to these accidents. The Canadian Elevator Safety Code and the Pennsylvania Bureau of Deep Mine Safety have recently revised their regulations and policies to require supplemental ascending car overspeed protection. As a result of this initiative, a new generation of braking systems has been developed and applied to mine elevators and hoists.Several supplemental emergency braking systems can be applied to mine hoisting systems. Some of the proven systems are counterweight safeties, electrical dynamicbraking, and a pneumatic rope brake system. The application of these braking systems to multiple rope hoisting systems is discussed in other literature 5, 6. The purpose of this paper is to discuss the application of these systems to single rope mine hoists. The electrical dynamic braking system is inherently unaffected by the number of suspension ropes and has been successfully applied to a single rope mine hoist 7. However, the application of the rope brake on a single rope hoist has presented technical challenges. This paper will discuss the control, design, and testing of the world's first application of a suspension rope brake to a single rope mine hoist. Problems with accelerated rope brake lining wear and excessive suspension rope lubrication will be addressed. The dynamic performance will be compared to rope brake installations on multiple rope hoisting systems.CASE STUDY: SINGLE ROPE MINE HOISTThe first installation of a Bode rope brake' on a single rope mine hoist was evaluated January 30-31, 1992. The pneumatic rope brake was installed on a ground mounted hoist which operates with a cage in balance with a counterweight in a vertical shaft. The drum is designed to wind an "under" and "over" 1-lj2 inch flattened strand hoist rope in a single layer. The drum is helically grooved to wind 20.4 live turns, 6 dead and 6 cutting turns, plus 4 turns between ropes. The drive is arranged for SCR controlled single D.C. motor drive through a double reduction reducer. The controls are either semi-automatic or manual by operation from the control panel. This hoist was commissioned by the federal and state regulatory agencies on April 12-13, 1984.Hoist Mechanical and Electrical Specifications Hoist Distance : 571 Ft. - Personnel/MaterialsD.C. Motor : 300 Horsepower, 500 Volts DC,Drum : 110 Diameter x 58" FaceHoist Ropes : Two - 1-1/2 Flattened Strand 6 x 30 Fiber Core, Galvanized,Preformed, Lang Lay,Breaking Strength 235,000 lb.490 Amperes, 400 rpmPersonnel Load : 7,875 lb.Material Load : 10,750 lb.Weight of Cage : 13,000 lb.Weight ofCounterweight : 17,250 lb.Weight of Rope : 4,700 lb. - 3.95 lb./feetSpeed of Hoist : 600 fpmSpeed of Motor : 467 rpm 600 fpmSpeed of Drum : 20.55 rpm 600 fpmWR2 of Hoist ：1，098，340lb.-ft2Drum Brakes : Four - Disc Brake Units, Spring Applied Pressure Released, Two Discs, Two Units Per Disc Lilly One - Model "C' Lilly ControllerController : Man SafetySafety Catches : Instantaneous Type, Activated by Slack or Broken RopeRope Brake DesignThe rope brake grips the suspension ropes and stops the hoist when an overspeed of 15% is detected or the cage moves away from the landing when it is not under control of the hoist motor. The pneumatic design is identical to the model 580 described in the literature 6. When the rope brake is activated, a set of magnetic valves direct pressurized air from the compressor tank into the rope brake cylinder. The air pushes the piston inside the rope brake cylinder and forces a movable brake pad toward a stationary brake pad. The suspension rope is clamped between the two brake pads. The rope brake is released by energizing the magnetic valves, which vent the pressurized rope brake cylinder to the atmosphere through a blowout silencer. The brake pads are forced open by six coil springs.The force exerted on the suspension rope equals the air pressure multiplied by the surface area of the piston. The rope brake model number 580 designates the inner diameter of the brake cylinder in millimeters. This translates into 409.36 in2 of surface area. The working air pressure varies from 90 to 120 1bf/in2. The corresponding range of force applied to the suspension rope is 36,842 to 49,123 lb. The static force experienced by the suspension rope on the cage sheave, under fully loaded conditions is 26,OOO lb. Therefore, the ropes experience up to 89% greater force during application of the rope brake under emergency conditions, than normally encountered during full load operation. Rope Brake Installation The rope brake was installed in a control room constructed in the hoist. headframe directly below the cage suspension rope sheave as shown in Fig. 1. The control room contains the complete rope brake system, including the rope brake, control logic, and air compressor. The rope brake safety relay contacts were wired into the hoist control below through conduit. Heaters were installed in the rope brake control room to regulate the temperature during cold weather operation. Fig. 1: Rope Brake InstallationRope Brake ModificationsThe mechanical design of the rope brake was modified for this application to a single hoist rope in addition to the modifications previously presented 6. The rope pulse tachometer wheel was increased to approximately 5 inches in diameter which is more than double the original diameter. Consequently, the number of screws on the wheel was increased to maintain the original sensitivity of the speed and position sensing logic. The pulse tachometer wheel diameter was increased to provide a smoother operation on the relatively rough surface of the hoist rope, compared to a typical elevator rope.Rope Brake Tests and ResultsThe integrity of the existing hoist safety system was, verified prior to performing any rope brake tests. The hoist emergency stopping, safety catches, overspeed and overtravel protection were dynamically tested. This procedure was essential to assure the safe completion of the rope brake test agenda.A series of tests were then conducted to evaluate the performance of the rope brake under extreme loading conditions and multiple control system faults. The compound braking effect on the deceleration rate was also evaluated. Compound braking occurs when the rope brake and the hoist brake operate simultaneously.Average Hoist Deceleration Rates: The rope brake and the compound braking deceleration rates are shown in Table I. The four test conditions represent the extreme hoist loading conditions for all possible directions of travel. The braking systems were activated at the rated speed of 600 ft/min. The average deceleration rates include the inherent mechanical time delay of approximately 300 msec before braking effort is realized. During this time period, the overhauling load begins to accelerate if it is traveling in the downward direction.TABLE IAverage Brake Deceleration RatesThe deceleration rates of each braking system can not be added algebraically to yield the compound deceleration rate because of the mechanical time delay and the non-linear characteristics of the rope brake deceleration. For example, the machine brake will stop the empty ca e traveling down at an average deceleration rate of 7.3 ft/s5 . Table I shows the rope brake only deceleration under this condition is 4.0 ft/s2. However, the compound braking deceleration rate is 8.7 ft/s2, not 11.3 ft/s2.The acceted maximum value for emergency deceleration is 16.1 ft/s (0.5g). Limiting emergency decelerations to rates less then 0.5g will minimize the possibility of injuring the passengers on the hoist. As shown in Table I, the compound braking effort did not exceed 16.1 ft/s2 (0.5g) for any possible condition.The hoist speed and armature voltage signal demonstrate the initial acceleration .that typically occurs when the armature current is interrupted before the rope brake develops sufficient braking effort to decelerate the falling counterweight. The speed deceleration profile shows the applied rope braking force is inversely related to the speed of the hoist. This observation is consistent with previously reported findings on multiple rope elevators 6.The pressure in the rope brake cylinder increased logarithmically with a time constant of 550 milliseconds. The pneumatic time constant is affected by the innerdiameter and total length of the air supply line. Since this hoist is not friction driven, the suspension rope can be protected by applying lubrication without causing rope slippage on the hoist drum. The lubrication presents a technical challenge not previously encountered when the rope brake was installed on friction driven elevators. The rope lubricant may have increased the stopping distances, which resulted in additional heat generation as the rope pulled through the set rope brake. 中文翻译 提升系统和安全装置Thomas D.BarkandSenior Member,IEEEMine Safety And Health AdministrationPittsburgh,Pennsylvania 15236摘要 根据记载，两个主要的可能发生在提升系统中导致人员伤亡和设备损坏的运行故障：1.在井筒末端过卷，2.工作循环中超速。在上述的情况下，就需要一种装置能在离井口相当远时就检测提升速度，如果容器在那一点运行太快则提升机将尽早进行紧急制动，以使得箕斗在过卷和引起破坏前就停下来。这篇论文就是研究单绳索牵引的矿井提升系统悬挂绳索制动刹车的应用。使绳索和绳索的刹车装置有机结合以及悬绳的润滑是技术上的一大挑战。提升装置的组成提升机和它的联接装置是地下矿山生产中最重要、最昂贵的部分。提升设备是所有的矿山都具有的部件，用于煤矿中提升必要的矿石、煤块、石料或提升和下放人员及物料。根据安装位置来分类，提升设备的组成如下：1. 地面设施a. 提升房 （1）提升滚筒或导向轮 （2）提升电气设备和机械设备 （3）提升钢丝绳b. 井架 （1）天轮 （2） 储藏柜 （3） 箕斗卸载装置2. 井筒中的设施a. 箕斗 （整装运输）b. 罐笼、升降机 （人员、物料）c. 导向轴 （为箕斗和罐笼导向）3. 地下设施a. 倾倒和储存仓b. 压碎机 （为提升需要而减小提升物尺寸）c. 装载容器d. 人员和物料支持设备提升系统在提升机房中提升设备的组成部分，即提升系统本身是工程设计主要所需要的。3个关键的因素决定了提升机的选择：1. 生产率或单位时间内的提升吨位2. 矿井深度3. 提升途径的数量有两种基本的提升方法，加上一些改进方法，一直沿用至今：滚筒提升和摩擦提升。滚筒提升贮存绳索在矿井中不伸展，摩擦提升使单根绳索（或多根）绕过主动轮而不去贮存绳索。一种次要的已基本不再使用的方法是卷筒提升，该提升中一根一定宽度的绳索被缠裹了许多层。一种新型的用于深井提升的多绳滚筒提升方法在南非被发明。提升系统的设计煤矿提升系统的设计方法应该被采矿工程师，甚至签订了设计和安装合同的工程公司和参与设备投标的提升设备制造公司会指派自己的工程部门去监察整个加工程序，包括采煤装置的设计和制造，现代提升系统的设计方法，会通过许多例子详细而生动地解释。1. 平衡提升。所有的煤矿提升系统都要求平衡地运行，以减小提升机的冲击、扭矩和动力要求。一般，两个提升容器悬挂在一个提升机上，有时，当一个提升容器需要维修时，用一个同等重量的平衡锤代替一个提升容器。平衡锤被设计成和箕斗或罐笼的固有负载量加上一半的活负载一样的重量，为了进一步平衡负载，我们又安装了尾绳。2. 摩擦盘提升中的滑动。如果钢丝绳张紧率超过理论极限时，摩擦提升装置将发生滑移。3. 钢丝绳尺寸。钢丝绳结构复杂，设计一个提升系统时，钢丝绳的单位长度重量和断裂强度这两项参数最重要。要注意钢材质量的这两项参数，包括圆股钢丝绳和三角股钢丝绳。4. 导向轮和滚筒直径。当钢丝绳缠绕越过一个导向轮或滚筒时，能使钢丝绳的挠矩和压力最小化，推荐的滚筒或导向轮直径与钢丝绳直径的最小比率是80100。自从钢丝绳的费用变大，更高效率的小直径滚筒代替传统的提升钢丝绳才变成可能，尤其在浅井提升中。5. 绳偏角。 即提升钢丝绳和导向轮与滚筒中心线之间的夹角。为了减少在导向轮运转中绳索的磨损，绳索偏角被限制在11.5°。这样一个限制最主要的结果是去限制滚筒的宽度。6. 箕斗尺寸和提升速度。为了在矿井中实现一个理想的生产率，设计者在箕斗尺寸和提升速度之间寻求一个平衡。最终限制箕斗尺寸的因素是钢丝绳强度和提升速度上的动力消耗。折衷的方案一般是尽可能大的箕斗在尽可能低的提升速度下运行最有利于提升。7. 提升系统。时间和距离的关系作为提升循环时间被考虑。计算时间和距离由以下几个公式可以完成：a. 加速时间 b. 加速距离 c. 匀速运行距离 d. 匀速时间 e. 周期时间 8. 工作循环。 提升动力矩的需求和提升循环时间之间的关系被称为工作循环。滚筒提升的倾斜部分反映了提升钢丝绳的失衡负载。对曲线以下的部分积分得到提供提升工作循环的能量损耗。安全设施 安全设施可能所有的大重量运动的机械设备，诸如齿轮、滚筒、提升容器和电动机，煤矿提升必须被保护避免发生在特定方向上过卷和过速。保护装置和矿山提升融为一体有两个原因。一是去保护人身安全，二是保护提升井架和最重要的部件、井筒。根据记载，两个主要的可能发生在提升系统中导致人员伤亡和设备损坏的运行故障：1. 在井筒末端过卷2. 工作循环中超速 过卷被定义为提升容器的运行超过预先计划或程序规定的停止点。这些停止点可能是井架上倾倒处或井筒中装载处或者罐笼着陆处。超速被定义为在矿井提升运行中的许多特殊点，其运行速度超过所需要或程序所规定的速度。当看到箕斗全速进入倾倒卷轴时，很容易知道为什么要考虑这些场景的重要性。如下：在倾倒曲轴的运行距离 20英尺（6.1米）全速提升速度 30英尺/秒（9.14米/秒）紧急停车延迟率 7.5英尺/(2.3米/)这意味着箕斗可能超过倾倒处60英尺，有可能它被推着通过井架顶端，从而破坏井口工作构件。在上述的情况下，就需要一种装置能在离井口相当远时就检测提升速度，如果容器在那一点运行太快则提升机将尽早进行紧急制动，以使得箕斗在过卷和引起破坏前就停下来。世界上有许多这种可以利用的设备，滚筒上的齿轮和驱动轴将提供精确的、灵敏的保护来避免因为过卷和过速造成提升设备和提升容器的损坏。众所周知，运用最广泛的是“Lilly Controller”，由芝加哥洛根有限责任公司制造。矿井提升机和提升人员为全国360多个煤矿的矿工提供了重要的安全线1。在例行的操作或生命受到威胁的紧急事件期间，煤矿提升系统通过一个隔离走廊输送矿工。如果提升系统失败，伤害的潜在风险就会变大。因此，一个安全的、可靠的矿井提升系