Bucket elevator is a common material vertical conveying equipment, which is mainly used to transport materials from low to high or from above to below.
Bucket elevators are mainly suitable for conveying bulky, large-capacity and heavy materials, and are widely used in building materials, chemicals, grains, mining and other industries.
The working process of the bucket elevator can be divided into three stages: loading, lifting and unloading. These three processes are closely linked to form a complete working process of the bucket elevator.
Any problem in any process will affect the normal operation of the hoist, which may cause backflow and reduce production, or cause blockage and stop the machine if it is serious.
The following is an in-depth analysis of the loading steps in the working process of the bucket elevator in order to seek an ideal and reliable working state.
Analysis of charging steps in the working process of bucket elevator
The loading process refers to the whole process of loading materials when the empty hopper passes around the bottom wheel and passes through the bottom of the machine base.
How full the hopper is during the loading process directly affects the productivity of the bucket elevator. The type of bucket elevator is different, the working conditions are different, and the filling degree of the hopper is different.
Loading the hopper too shallow obviously reduces the productivity of the hoist. If it is too full, it will easily cause backflow and spillage during the lifting and unloading stages, which is not allowed in the work.
Analysis of two feeding methods of bucket elevator
Common feeding methods for bucket elevators are forward feeding and reverse feeding. What they have in common is that the hopper passes through the stockpile, relying on the movement of the hopper to dig out the material. This loading method is suitable for conveying powdery, granular or very small block materials with good fluidity.
Feed mode 1#: forward feed
When feeding in the forward direction, the material flows into the machine base along the moving direction of the hopper and meets the back of the hopper. At this point the hopper does not fill immediately, but pushes the material forward in the pile. When the hopper turns over the lowest point of the bottom wheel, the material is gradually dug into the hopper as the hopper mouth turns upwards.
The higher the material level in the machine base, the more material the hopper scoops up. And the height of material level is to improve along with the increase of feeding amount, when the charging amount of hopper is balanced with the amount of material fed in, the material level in the machine base remains at a certain level.
If the feed rate increases, firstly the material level on the down side of the hopper inside the machine base will increase, and the cutting depth of the material at the front edge of the hopper will increase.
When the hopper moves to the uplink side and is about to leave the stockpile, there is still a part of the material that has not entered the hopper, and this part of the material will fall into the stockpile of the machine base.
In this way, the following hoppers are repeated continuously, so that the material level on this side is gradually increased, and the filling factor of the hopper is also increased. When the amount of material in the hopper reaches the same amount as the machine, a new balance will be created, and the material level will stabilize at a new height.
When the amount of material supplied makes the material level on the upstream side higher than the horizontal centerline of the bottom wheel, the hopper will pass through the material pile in a straight line motion state, and its filling factor will reach the limit.
If the amount of material in the hopper is still smaller than the amount of material entering the machine at this time, the material level on the upstream side will continue to rise.
In this way, the overfilled material will have a great resistance to the hopper, which will eventually cause the elevator to block and the hopper to stop running.
Therefore, although forward feeding can enable the hopper to obtain a higher filling factor, the hopper will be subject to greater running resistance, so a lower filling factor should be taken during design.
In addition, since the hopper needs to pass through and push materials in the piles on both sides of the bottom wheel, in order to reduce the resistance of this part, the feed hopper is usually installed lower so that the bottom edge is below the horizontal centerline of the bottom wheel. This also reduces the chance of material being trapped between the hopper and the belt.
Feed mode 2#:Reverse feeding
When feeding in the reverse direction, the material flows into the machine base against the moving direction of the hopper, part of it flows to the bottom of the machine base, and part of it can be directly loaded into the hopper. The hopper only touches a little material on the downside of the machine frame, and it starts to fill when it reaches the upside.
When the feed inlet is at a low position, almost all the feed materials flow into the bottom of the machine base* same as the forward feed, the hopper is completely filled by digging, and the filling factor is low. When the feed inlet is at a high position, part of the feed material flows into the bottom of the machine base, and part of it directly falls into the hopper.
In this way, the material level in the machine base can be kept at a low level, so that the hopper can only dig a small amount of material at the bottom, and when it turns to the upward direction, it can be replenished by direct injection of material flow. Therefore, a higher filling factor can be obtained during reverse feeding, and the resistance of digging is not large, which is beneficial for the material to be injected into the hopper.
When feeding in reverse, the bottom edge of the feed port is usually set above the horizontal centerline of the bottom wheel.
During the loading stage of the bucket elevator, the material needs to be transported to the feed inlet of the elevator, and different equipment is used to transport the material according to the properties of different materials.
Whether it is forward feeding or reverse feeding, the material flow into the machine must be well controlled to prevent blockage and ensure the normal operation of the hoist.