外文翻译--皮带传送系统及其牵引系统

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1、 本科毕业设计 外文文献 及 译文 文献、资料题目： Belt conveying systems and driving system 文献、资料来源： 期刊 文献、资料发表（出版）日期： 2012.3.2 院 （部）： 机电 工程学院 专 业： 机械电子 班 级： 姓 名： 学 号： 指导教师： 翻译日期： 2012.4.25 山东建筑大学毕业设计外文文献及译文 - 1 - 外文 文献 ： Belt conveying systems and driving system Among the methods of material conveying employed， belt conv

2、eyors play a very important part in the reliable carrying of material over long distances at competitive cost。 Conveyor systems have become larger and more complex and drive systems have also been going through a process of evolution and will continue to do so。 Nowadays， bigger belts require more po

3、wer and have brought the need for larger individual drives as well as multiple drives such as 3 drives of 750 kW for one belt(this is the case for the conveyor drives in Chengzhuang Mine)。 The ability to control drive acceleration torque is critical to belt conveyors performance。 An efficient drive

4、system should be able to provide smooth， soft starts while maintaining belt tensions within the specified safe limits。 For load sharing on multiple drives， torque and speed control are also important considerations in the drive systems design。 Due to the advances in conveyor drive control technology

5、， at present many more reliable。 Cost-effective and performance-driven conveyor drive systems covering a wide range of power are available for customers choices。 1 Analysis on conveyor drive technologies 1 1 Direct drives Full-voltage starters。 With a full-voltage starter design， the conveyor head s

6、haft is direct-coupled to the motor through the gear drive。 Direct full-voltage starters are adequate for relatively low-power, simple-profile conveyors。 With direct full-voltage starters， no control is provided for various conveyor loads and depending on the ratio between full- and no-load power re

7、quirements， empty starting times can be three or four times faster than full load。 The maintenance-free starting system is simple， low-cost and very reliable。 However, they cannot control starting torque and maximum stall torque； therefore， they are limited to the low-power, simple-profile conveyor

8、belt drives Reduced-voltage starters。 As conveyor power requirements increase， controlling the applied motor torque during the acceleration period becomes increasingly important。 Because motor torque 1second a function of voltage， motor voltage must be controlled。 This can be achieved through reduce

9、d-voltage starters by employing a silicon controlled rectifier(SCR)。 A common starting method with SCR reduced-voltage starters is to apply low voltage initially to take up 山东建筑大学毕业设计外文文献及译文 - 2 - conveyor belt slack， and then to apply a timed linear ramp up to full voltage and belt speed。However, t

10、his starting method will not produce constant conveyor belt acceleration。 When acceleration is complete， the SCRs, which control the applied voltage to the electric motor， are locked in full conduction, providing full-line voltage to the motor。 Motors with higher torque and pullup torque， can provid

11、e better starting torque when combined 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 resist

12、ance in series with the motors 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 torqu

13、e。 On multiple-drive 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 design。However, the control systems for these can be highly complex， because they are based on computer control of the resistance s

14、witching。 Today， the majority of control systems are custom designed to meet a conveyor systems particular specifications。 Wound rotor motors are appropriate for systems requiring more than 400 kW 。 DC motor DC motors， available from a fraction of thousands of kW ， are designed to deliver constant t

15、orque 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 motors rotating armature is connected externally。 The most common technology for controlling DC drives is

16、a SCR device， which allows for continual variable-speed operation 。 The DC drive system is mechanically simple, but can include complex custom-designed electronics to monitor and control the complete system。 This system option is expensive in comparison to other soft-start systems。 but it is a relia

17、ble, cost-effective drive in applications in which torque,load sharing and variable speed are primary considerations。 DC motors generally are used with higher-power conveyors， including complex profile conveyors with multiple-drive systems， booster tripper systems needing belt tension control and conveyors requiring a wide variable-speed range。 1 2 Hydrokinetic coupling