帶式輸送機張緊裝置的設計畢業設計-資料下載頁

【導讀】裝置是保證輸送機正常啟動、運行、制動、和停車的不可缺少的重要部件之一，直接影響帶式輸送機的安全可靠性和穩定性。置,很難達到最佳的張緊效果。本設計利用電動絞車技術對膠帶張緊力進行實時。帶和設備的使用壽命，節約了輸送機的運行成本。該張緊裝置結構簡單、維護方。便，并且能夠實現長距離帶式輸送機的張緊要求。行了簡要的論述。

　　

【正文】 oltage starters are adequate for relatively lowpower, simple Profile conveyors. With direct fullvoltage starters. no control is provided for various conveyor loads and. depending on the ratio between full and noload power requirements, empty starting times can be three or four times faster than full load. The maintenancefree starting system is simple, lowcost and very reliable. However, they cannot control starting torque and maximum stall torque。 therefore. they are limited to the lowpower, simpleprofile conveyor belt drives. Reducedvoltage starters. As conveyor power requirements increase,controlling the applied motor torque during the acceleration period bees increasingly important. Because motor torque is a function of voltage, motor voltage must be controlled. This can be achieved through reducedvoltage starters by employing a silicon controlled rectifier (SCR). A mon starting method with SCR 2 reducedvoltage starters is to apply low voltage initially to take up conveyor belt slack. and then to apply a timed linear ramp up to full voltage and belt speed. However, this starting method will not produce constant conveyor belt acceleration. When acceleration is plete. the SCRs, which control the applied voltage to the electric motor. are locked in full conduction, providing fullline voltage to the motor. Motors with higher torque and pull vp torque, can provide better starting torque when bined with the SCR starters, which are available in sizes up to 750 KW. Wound rotor induction motors. Wound rotor induction motors are connected directly to the drive system reducer and are a modified configuration of a standard AC induction motor. By inserting resistance in series with the motor39。s rotor windings. the modified motor control System controls motor torque. For conveyor starting, resistance is placed in series with the rotor for low initial torque. As the conveyor accelerates,the resistance is reduced slowly to maintain a constant acceleration torque. On multipledrive systems. an external slip resistor may be left in series with the rotor windings to aid in load sharing .the motor systems have a relatively simple a ,the control systems for these can be highly plex, because they are based on puter control of the resistance switching. Today, the majority of control systems are custom designed to meet a conveyor system39。s particular specifications. Wound rotor motors are appropriate for systems requiring more than 400KW. DC motor. DC motors. available from a fraction of thousands of KW， are designed to deliver constant torque below base speed and constant KW above base speed to the maximum allowable revolutions per minute (r/min). with the majority of conveyor drives, a .DC shunt wound motor is used. Wherein the motor39。s rotating armature is connected externally. The most mon technology for controlling DC drives is a SCR device. which allows for continual variablespeed operation. The DC drive system is mechanically simple, but can include plex customdesigned electronics to monitor and control the plete system. this system option is expensive in parison to other softstart systems. but it is a reliable, costeffective drive in applications in which torque,load sharing and variable speed are primary considerations. DC motors generally are used with higherpower conveyors, including plex profile conveyors with multipledrive systems, booster tripper systems needing belt tension control and conveyors requiring a wide variablespeed range. 3 1. 2 Hydrokiic coupling Hydrokiic couplings, monly referred to as fluid couplings. are posed of three basic elements。 the driven impeller, which acts as acentrifugal pump。 the driving hydraulic turbine known as the runner and a casing that encloses the two power ponents. Hydraulic fluid is pumped from the driven impeller to the driving runner, producing torque at the driven shaft. Because circulating hydraulic fluid produces the torque and speed, no mechanical connection is required between the driving and driver power produced by this coupling is based on the circulated fluid39。s amount and density and the torque in proportion to input speed. Because the pumping action within the fluid coupling depends on centrifugal forces. the output speed is less than the input speed. Referred to as slip. this normally is between 1% and 3%. Basic hydrokiic couplings are available in configurations from fractional to several thousand KW. Fixedfill fluid couplings. Fixedfill fluid couplings are the most monly used softstart devices for conveyors with simpler belt profiles and limited convex/concave sections. They are relatively simple,lowcost,reliable,maintenance free devices that provide excellent soft starting results to the majority of belt conveyors in use today. Variablefill drain couplings. Drainablefluid couplings work on the same principle as fixedfill couplings. The coupling39。s impellers are mounted on the AC motor and the runners on the driven reducer highspeed shaft. Housing mounted to the drive base encloses the working circuit. The coupling39。s rotating casing contains bleedoff orifices that continually allow fluid to exit the working circuit into a separate hydraulic reservoir. Oil from the reservoir is pumped through a heat exchanger to a solenoidoperated hydraulic valve that controls the filling of the fluid coupling. To control the starting torque of a singledrive conveyor system, the AC motor current must be monitored to provide feedback to the solenoid control valve. Variable fill drain couplings are used in medium to highkw conveyor systems and are available in sizes up to thousands of drives can be mechanically plex and depending on the control parameters. the system can be electronically intricate. The drive system cost is medium to high,dep