Electric control of the hottest combined rail cran

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Electrical control of combined rail crane

the combined rail crane is a special crane for the coal mill room of thermal power plant, which is mainly used for the maintenance of ball mills and the hoisting of general parts. Its equipment is mainly composed of two parts: one is the monorail crane (excluding electric hoist) installed on both sides of the crane above the ball mill, which can be driven by electric and manual methods: electric means that the crane is driven by motor; Manual refers to the chain wheel type hand zipper wheel drive. The second is to install a double beam crane on the side of the monorail crane and above the aisle (composed of two single beam cranes and rigid connections of cranes), which is controlled by the ground button box

1. Electrical control requirements

as shown in Figure 1, 5 coal mills No. 15 are arranged in the plant, and 6 monorail var cpros are installed on the upper side of the 5 coal mills_ id = "u"; Crane, one electric double beam crane is installed above aisle 1 on the side of monorail crane

its task is to connect the double beam crane parked on the No. 1 aisle with two monorail cranes (No. 5 and No. 6) above the No. 5 coal mill; Use the electric hoist to transport the required lifting items from the No. 5 coal mill to the double beam crane, and then transport the items to the No. 1 aisle position through the double beam crane. In the whole working process, there are the following requirements for electrical control:

(1) the double girder crane must pass through monorail cranes No. 2, No. 3, No. 4 and No. 5 from position 1 to position 5. Because each time it passes through a monorail crane, the double girder crane needs to go through the processes of deceleration, rail alignment, parking, etc., which produces the phenomenon of intermediate parking, etc., which will shake the lifted object and affect the work efficiency, Therefore, we should try to solve it

Figure 1 Schematic diagram of plant layout

(2) double beam crane and monorail crane must be accurately aligned and positioned (successful positioning at one time is the best)

"(3) eye catching signal display shall be set for the successful positioning of rail alignment and the successful connection of upper and lower locks, so as to facilitate the next action

(4) the working sequence of the mechanism and the electrical control of each step are closely linked, so interlocking and protection links should be set

(5) two electric hoists shall have single action and linkage control functions

2. Electrical control method

the whole workflow is closed-loop control, as shown in Figure 2

since the process of each step is closely connected, the selection of motor speed, electrical interlock, rail alignment mode, allowable error range of rail alignment in place, signal indication and other index requirements are very important in electrical control. There are two methods of electrical control: one is to use contactors, relays, time relays, switches and other components to form part control; Second, the use of contactors, PLC, switches and other components to centralize these new medical technologies require biodegradable high molecular materials for support and control

Figure 2 workflow block diagram

the first control method, because there are many electrical components, and the connecting links of various interlocks and protections are also complex (at the same time, there are many fault points), the volume of the control box is large, and it will be limited by the platform and space when placed on the small double beam composed of two single beams. Although the second method is more expensive than the first method in price, it uses fewer components. Its control part basically belongs to PLC, which can not only reduce the electrical fault points and improve the performance of the whole machine, but also reduce the volume of the control box and facilitate installation and maintenance. The running motor is a two speed motor. Fast speed is used for long-distance operation, and slow speed is used for rail alignment in place, so it is easy to adjust on site from deceleration, rail alignment to parking. A change-over switch is set on the button box to disable the functions of the double beam crane in the three processes of deceleration, rail alignment and parking when passing through No. 2, No. 3, No. 4 and No. 5 monorail cranes. This function is restored only after passing through No. 5 vehicle. The ground staff can select the operation purposefully, which not only solves the shaking of the lifting object, but also improves the work efficiency and simplifies the control of the line. In addition, for the single action/linkage of two hoists, a change-over switch can also be set to realize the single action/linkage function. At every step of the workflow, the United States decided to impose tariffs on steel and aluminum products of these three economies from June 1, and should set up electrical interlocking and protection devices; It can be realized by secondary circuit, external limit switch or PLC internal programming. Signal lights of different colors are set to remind the ground staff whether this step is successfully in place. The next operation can be carried out only when the previous step is successfully in place and the signal is given. This setting can reduce the volume of the button box and is easy to purchase. The domestic 11 bucket button box can meet the requirements after modification

at present, there is little difference in structure and weight between domestic and imported rail cranes. The main difference is the accuracy of rail alignment between electric double beam crane and monorail crane. The imported rail crane is basically successful at one time when aligning the rail, while the domestic rail crane needs several times of inching to succeed. The main difference lies in the accuracy requirements of the locking device and the allowable error range of the rail positioning when the hoist passes the rail. The accuracy of the locking device of the imported machine is low, and the allowable error range of the rail positioning when the hoist passes the rail is large; However, the domestic machine has high requirements for the accuracy of the locking device and the allowable error range of rail positioning when the hoist passes the rail is small. If the range is large, it is not easy to successfully position. This correspondingly improves the requirements of electrical control and motor speed (the lower the speed, the better) when the rail is in place

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