Wheel stacker reclaimer installation preparation and notes

Bucket wheel stacker and reclaimer, as an efficient continuous loading and unloading machine, is widely used in the yard of ore and coal bulk cargo terminals. This article will mainly introduce the specific procedures and precautions for the preparation work, site installation and safe operation of the bucket wheel stacker and reclaimer before construction on site.

Bucket wheel type stacker reclaimer pre-construction preparation

1. Parts are transported into the infield

Since stackers and reclaimers usually operate in the infield, they are generally shipped in bulk. Usually by ship, during the process from unloading to transshipment into the infield, the tonnage and size of each piece need to meet a number of on-site equipment and road and site requirements, such as the capacity of unloading equipment, the limit load size of the terminal approach bridge, the obstacles on the transshipment road and the requirements of the site. Infield unloading equipment capacity, etc. 

Therefore, in the early stage of the project, it is necessary to conduct on-the-spot investigation of the transshipment route and the final assembly site, and accordingly make a segmentation plan for the oversized and overweight structural parts in the machine. Otherwise, once the component is finalized, it will be very expensive to modify it later. In the Beilun project, the columns and booms were divided into 2 sections due to the size and mass exceeding the limit. At the same time, due to road restrictions, the width of all structural parts is controlled within 10 m, and the excess is removed or divided.

2. Arrangement of infield spare parts

After the loose parts are transported into the infield, they need to be placed reasonably. Usually, the loose parts will be placed on both sides of the track in the final assembly site. The layout should be reasonable, and the hoisting position and channel of the hoisting equipment should be reserved. First of all, ensure that the large parts and the components to be installed can be in a position where they can be lifted once and can be lifted in place, so as to avoid wasting time and manpower in the second displacement. Other small pieces can be stacked and arranged in a centralized manner for easy management. At the same time, the large-scale stacking position and the crane hoisting operation site in the yard should be leveled, and after preliminary compaction, it can withstand the operation of large-scale structural parts and large-tonnage cranes.

3. Final assembly equipment

According to the previous calculation, the mass of the large central column is the largest, about 80 t, and the total assembly height is 36 m. After calculation, it is determined that the 250 t crawler crane is selected as the main lifting equipment for the large pieces. In addition, 6 t and 16 t forklifts, climbing trucks, flatbed trucks and 50 t truck cranes are required as daily equipment, which can be used throughout the entire assembly cycle.

Wheel stacker reclaimer on-site installation solution

Since the installation of the bucket wheel stacker and reclaimer involves many aspects, this article only describes the main points of the installation of the large parts of the main machine, and does not describe the installation of the small parts and the tail car.

First, draw the relative position lines of the three sets of carts on the track, and then hoist the cart components to the track. The wheels of the three sets of carts must be on the same level. After hoisting and positioning, insert wooden wedges into the wheel to prevent sliding and fix with channel steel. At the same time, fix the cart with a hand hoist and adjust the verticality and straightness deviation of the cart to be less than ±1mm.

Hoist the gantry assembly to the traveling mechanism of the cart, connect the gantry and the connecting flange of the cart with product bolts, and install part of the gantry inclined ladder platform. The total mass of the gantry assembly is 77 t, and the height of the lifting point is 17 m, which is second only to the column in quality. Depending on the design form, some projects may have a balance beam structure between the gantry and the cart. During on-site installation, the gantry and the balance beam can be installed together and then hoisted as a whole.

Before installing the slewing platform, arrange the slewing bearing and slewing mechanism on the ground. When arranging slewing bearings, pay attention to adjusting the installation positions of the soft points of the inner and outer rings according to the design drawings. The slewing platform is assembled with the complete lifting assembly on the gantry, and two diagonal bolt connection holes are arbitrarily selected to locate it with the large slewing bearing with guide pins, and then use product bolts to connect the slewing bearing and the flange of the gantry. 

It should be noted that the connecting bolts at the slewing bearing are high-strength bolts, and a torsion test needs to be done in advance to ensure the bolt pre-tightening force for on-site construction. The arrangement of the rotary drive is generally after the assembly of the large parts, the motor and the reduction box can be arranged for inspection first, the gears are first roughly positioned for the meshing gap, and then the upper flange of the drive mechanism is spot welded. Before power-on debugging, weld the upper and lower flanges of the drive mechanism after finely arranging the rotary drive gap.

Due to the relationship between the load limit of the transfer time and the large shape of the column, the column is generally shipped in sections. After arriving at the site, it needs to be assembled first. Depending on the process, the assembly can be bolted or welded. When assembling, it is necessary to control the level and verticality, and re-test after assembling. After the assembly is completed, hoist the column assembly, wear the column and the pin shaft hole of the rotary platform at one end, place the tire frame and sleeper support at the bottom of the other end, and set up the tire frame platform, and adjust the column to be in a horizontal state. 

The mass of the column assembly is 80 t, and the height of the lifting point is 36 m, which is the largest mass. Before hoisting, ensure that it is within the hoisting capacity of the crawler crane. After the hoisting is in place, pull the windproof wire rope, and tighten the hand hoist under the wire rope. Since the high tire frame under the column is temporarily assembled on site, pay attention that the height cannot be too high, it needs to be just right or slightly lower, otherwise it will affect the installation of the middle and front tie rods. In order to ensure the stability, the high tire frames are connected and fixed with each other and the door seat frame with process braces. The belt conveyor drive can then be installed.

Hanging column:

Before hoisting the boom, assemble the front and rear sections of the boom on the ground to ensure that the centerline deviation is ≤ 3 mm. Then hoist the boom assembly as a whole, first assemble the hinge point connected to the column, and then slowly place the other end on the arranged tire frame. In order to facilitate the installation of the rear boom rod, the high tire frame on the boom head can be appropriately increased, so that the boom head is in an upturned state (about 2°). If conditions permit, the jib can be hoisted by double-machine hoisting, which is convenient to adjust the inclination of the girder at any time during hoisting. It can also be combined with the calculated center of gravity position and adjust the position of the lifting lug and the length of the suspending rope, so as to control the slope of the girder and use a single machine for hoisting.

Hoisting boom:

The pull rod in this project is a figure-eight pull rod, the upper part is a single hinge point, and the lower part is a double hinge point, which are respectively connected to the boom, and the left and right pull rods are connected as a whole by a connecting beam in the middle. It can be assembled into components on the ground on site, and then the whole lifting beam can be used for overall lifting. The installation of this form of tie rod is much more difficult than that of the left and right parallel form, so it is necessary to strictly control the opening size when assembling on the ground, otherwise it will be difficult to assemble the lower hinge point. 

The front tie rod and the middle tie rod are not rigid due to the thin plate, so they can be adjusted slightly if there is any error during installation. However, the thickness of the rear tie rod must be matched with the opening size and slope of the counterweight frame connection when assembling on the ground, otherwise the installation will be very difficult. The tie-rod installation can also be carried out by means of double-machine hoisting, and at the same time, the chain hoist is used to cooperate with the installation, and then the intermediate connecting beam is hoisted. However, this method will increase the workload of high-altitude, and how to choose should be determined according to the situation on site.

Before installing the bucket wheel body assembly, first assemble the hopper, bucket wheel shaft and bearing seat on the bucket wheel body on the ground, then hoist the bucket wheel body assembly as a whole, place it on the boom and bucket wheel support and connect with product bolts , and then install the internal chute, bracket and other components of the bucket wheel body. Finally, install the arc baffle plate, adjust the gap to the drawing size, and ensure that the bucket wheel body can rotate flexibly.

The counterweight beam is hoisted together by two cranes. After the pin shaft is threaded with the column, the crane at the column end slowly loosens the hook and removes the hoisting wire rope, and the other end keeps the hoisting hook. Then hoist the rear tie rod assembly (the rear tie rod needs to be assembled into components on the ground first), first assemble the hinge point to connect with the column, and then slightly lift the counterweight beam to connect the rear tie rod and the counterweight beam hinge point.

The above is the general assembly process of each large piece. It should be noted that the basis of the large piece installation process is the calculation and use of the center of gravity. From the hoisting of a single large piece to the installation process of the whole machine, the change of the center of gravity should be strictly calculated and controlled. The stability of the installation structure, the core essence of large-scale installation lies in this. After the installation of large parts, the installation of various small parts can be carried out, and then the electrical wiring and wiring can be carried out, and finally enter the debugging stage.

Wheel stacker on-site work safety precautions

When the bucket wheel stacker and reclaimer is installed on site, most of the structural parts are of large quality and dimensions, requiring hundreds of tons of cranes for high-altitude hoisting operations, which are relatively dangerous. Therefore, the craftsmen must first design and install the corresponding craft platform according to the conditions of each construction operation in the early stage to ensure that the work is carried out during construction. During the displacement and lifting of large components, the displacement area needs to be cleared, and irrelevant personnel are not allowed to stay. All construction workers must strictly follow the instructions of the commanding staff to carry out operations.