外文翻譯----有關(guān)帶式輸送機的驅(qū)動裝置設(shè)計的一些研究-wenkub
2023-05-19 11:29:50 本頁面
【正文】 而 當(dāng)驅(qū)動器和 頭部滾筒張緊時 ，就會使因負載而加速的帶由于長距離輸送之間的摩擦力而減緩下來 。這 對 皮帶和 帶 輪有害 ， 而且也 是 很 危險的。 附件 ： FROM : The South African Institute of Materials Handling BELT CONVEYOR DRIVES A CONSIDERATION OF SOME DESIGN ASPECTS . Rall ., BSc Eng., MSAIME Hansen Transmissions (Pty) ltd P. Staples BSc, MSAIME Managing Director Conveyor Knowledge and Information Technology (Pty)Ltd (CKIT) Summary: This is a short review of part 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 the speed reducer between motor coupling and drive pulley, ratings, bearing life, service factors, stopping and antirunback devices 1. General The ever increasing rate of consumption of earth39。 again ideal for variable speed, but overall running and maintenance costs on big powers are likely to be higher than a fluid coupling drive, with . motor or slip ring motor. . Belt Protection Belt protection against overload and stalling is monly done by a centrifugal switch driven by a roller on the underside of the belt. This, however, is not very 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 pares the pulse frequencies continuously and if they go outside set limits, an 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 coupling can be controlled by the paritor. 5. Stopping a Belt Conveyor . Forward stopping As 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. 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, but this is generally a very rare condition. Considering a conveyor layout as per sketch (see appendix B) fitted with a brake on the gearbox high speed shaft, it can be seen that when stopped under load the inertia of the load would tend to pick up the gravity tensioner and release the tension in the belt between drive and head pulley and may even go slack by the time the load es to rest. The load assisted by the gravity take up would then accelerate the belt in the return direction while the drives are stationery with brakes on. When the belt between drive and head pulley bees tight it has to retard the load in a fraction of the distance in which it had been accelerated. Under this sudden stopping of the load the drive is subjected to heavy shock. In this
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