Method for controlling material flow rate of bucket chain continuous ship unloader

Abstract

The present invention relates to material transportation, and in particular to a method for controlling the material flow of a chain bucket continuous ship unloader. The method comprises the following steps: S1, installing a front arm belt scale; S2, obtaining a linear function of material flow and torque current; S3, limiting the material flow by controlling the lifting torque of a bucket elevator; S4, regulating the material flow exceeding the expected flow by an output belt conveyor; S5, limiting the material flow at the receiving point of the output belt conveyor. The present invention fully guarantees the operating efficiency and controls the material flow of the chain bucket elevator by caching materials. First, a linear function of material flow and chain bucket lifting torque is obtained, and then the material flow arriving at the arm belt conveyor is preliminarily limited by controlling the lifting speed of the bucket elevator. Finally, the speed of the output belt conveyor is adjusted to achieve the effect of controlling the output material flow of the chain bucket elevator, and the operating process is balanced and stable.

Description

Technical Field

[0001] The invention relates to material transportation, in particular to a method for controlling material flow of a chain bucket type continuous ship unloader. Background Art

[0002] Bucket chain continuous ship unloaders, also known as chain bucket unloaders, are being increasingly adopted by bulk cargo terminals striving for high efficiency due to their high efficiency, energy conservation, and environmental friendliness, as well as their increasingly mature technology. During unloading operations, materials pass through the bucket elevator's excavation and lifting sections, lifting them to the elevated rotary receiving tray and boom conveyor. Finally, they are channeled through the central receiving hopper and the lower output conveyor to the surface conveyor. The chain bucket unloader's power mechanism, with the exception of the rotary receiving tray and boom conveyor, which are driven at a fixed speed, features adjustable speeds.

[0003] Compared to grab ship unloaders, chain bucket ship unloaders lack a large hopper to store and buffer material flow. They are more susceptible to the shape of the material pile in the ship's hold or operator manipulation, resulting in large headstock or intermittent material flow. This leads to frequent overloading and uneven material distribution on the downstream conveyors of the chain bucket ship unloader, impacting the stability of the production process and affecting production efficiency. Summary of the Invention

[0004] The present invention aims to solve the above technical problems, thereby providing a method for controlling material flow of a chain bucket continuous ship unloader with balanced material transportation.

[0005] The present invention solves the technical problem and adopts the following technical solution:

[0006] A method for controlling material flow of a chain bucket continuous ship unloader comprises the following steps:

[0007] S1. Install the front arm belt scale

[0008] The front arm belt scale is located at the feeding end of the arm belt conveyor;

[0009] S2. Obtain the linear function of material flow and torque current

[0010] Record the material flow rate of the front arm belt scale and the torque current of the corresponding bucket elevator's hoisting motor during continuous operation, perform linear analysis, intercept the data with a linear coefficient R² ≥ 0.8, and fit the linear function y = kx + b to obtain the values of k and b. y is the material flow rate, x is the torque current, and the rated time for the material to travel from the hoisting part to the rear arm belt scale is T1;

[0011] S3. Limit material flow by controlling the lifting torque of the bucket elevator

[0012] Calculate the torque current of the bucket elevator's hoist motor corresponding to the expected operating flow rate according to the linear function in step S2, and use it as the upper threshold. If the upper threshold is exceeded, an alarm is triggered and the bucket elevator's feeding speed is reduced.

[0013] S4, adjust the material flow that exceeds the expected flow through the output belt conveyor

[0014] Measure the time T2 from the rear arm belt scale for the material to reach the receiving point of the output belt conveyor. According to the material flow data of the rear arm belt scale, when the material flow exceeding the expected flow reaches the output belt conveyor, adjust the running speed of the output belt conveyor;

[0015] S5. Limit the material flow at the receiving point of the output belt conveyor

[0016] Calculations are based on the theoretical speed value of the output belt conveyor after deceleration. When the material flow of the receiving funnel exceeds the maximum upper limit of the equipment after superposition, the output belt conveyor's operating speed is gradually increased until the output belt conveyor's operating speed reaches the maximum value.

[0017] Compared with the prior art, the present invention adopting the above technical solution has the following beneficial effects:

[0018] To fully guarantee the operation efficiency, the material flow of the chain bucket elevator is controlled by caching the materials. First, a linear function of the material flow and the chain bucket lifting torque is obtained. Then, by controlling the lifting speed of the bucket elevator, the material flow reaching the boom belt conveyor is preliminarily limited. Finally, by adjusting the speed of the output belt conveyor, the output material flow of the chain bucket elevator is controlled, and the operation process is balanced and stable.

[0019] Furthermore, the optimization scheme of the present invention is:

[0020] In step S2, when the bucket elevator operates normally and continuously at the rated speed for more than 30 minutes, the material flow rate value and the torque current of the motor during the period are recorded.

[0021] In step S2, the torque current of the motor when the material enters the lower end of the lifting part of the bucket elevator corresponds to the material flow rate when the material reaches the front arm belt scale after a fixed conveying time.

[0022] In step S3, the torque current of the motor of the lifting part of the bucket elevator is continuously detected. When the torque current exceeds the upper threshold for 9 seconds in 3 consecutive seconds or 30 seconds, a warning signal is issued to reduce the feeding speed; if the torque current exceeds the upper threshold for 12 seconds in 7 consecutive seconds or 30 seconds, the lifting speed of the lifting part is reduced to 80% of the rated value. After each deceleration of the bucket elevator, the torque current of the motor must be kept below the upper threshold for at least 5 seconds. If the torque current still exceeds the upper threshold for more than 3 seconds during the deceleration period, the lifting speed of the lifting part is continuously reduced by 20%.

[0023] In step S4, the adjustment frequency is 1 Hz, and the output material flow is limited to not exceed 5% of the expected value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural schematic diagram of a chain bucket continuous ship unloader according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the operation of the output belt conveyor.

[0026] In the figure: bucket elevator 1; excavation part 1-1; lifting part 1-2; rotary feed tray 2; front arm belt scale 3; arm belt conveyor 4; rear arm belt scale 5; receiving funnel 6; output belt conveyor 7; cart 8. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the accompanying drawings and examples.

[0028] See also Figure 1 、 Figure 2 The chain bucket continuous ship unloader is mainly composed of a bucket elevator 1, a rotary feeder 2, a front arm belt scale 3, an arm belt conveyor 4, a rear arm belt scale 5, a material receiving funnel 6, an output belt conveyor 7 and a trolley 8. The bucket elevator 1 is mainly composed of an excavating part 1-1 and a lifting part 1-2, and the lifting part 1-2 is driven by a motor.

[0029] The above-mentioned method for controlling the material flow of the chain bucket continuous ship unloader is carried out in the following steps:

[0030] S1. Install the front arm belt scale 3

[0031] The front arm frame belt scale 3 is located at the feeding end of the arm frame belt conveyor 4. The front arm frame belt scale 3 is set at one end close to the rotary receiving tray 2 and away from the receiving funnel 6 of the corresponding output belt conveyor 7;

[0032] S2. Obtain the linear function of material flow and torque current

[0033] When the chain bucket continuous ship unloader is operating on materials with a flat surface and relatively uniform density, and the hoisting section 1-2 operates normally and continuously at the rated speed for more than 30 minutes, the material flow rate value of the front arm belt scale 3 and the torque current of the motor of the hoisting section 1-2 of the bucket elevator 1 are recorded during this period. A linear analysis is performed, and data with a linear coefficient R² ≥ 0.8 are intercepted. The linear function y = kx + b is fitted to obtain the values of k and b, where y is the material flow rate value and x is the torque current;

[0034] The torque current of the motor when the material enters the lowest end of the hoist 1-2 corresponds to the material flow rate when the material reaches the front arm belt scale 3 after a fixed conveying time. If the chain bucket of the hoist 1-2 lifts the material from the lowest end to the highest end at the rated speed, and the total time it takes for the material to reach the rear arm belt scale 5 via the rated speed rotary feed tray 2 and the arm belt conveyor 4 is the rated time T1, then the material flow rate corresponding to the latest torque current of the motor of the hoist 1-2 is the flow rate value displayed by the front arm belt scale 3 after T1 time.

[0035] S3. Limit material flow by controlling the lifting torque of the bucket elevator

[0036] The torque current of the motor of the hoisting part 1-2 of the bucket elevator 1 corresponding to the expected operating flow is calculated according to the linear function in step S2 as the upper threshold value. The motor torque current of the hoisting part 1-2 is continuously detected. When it exceeds the upper threshold value for 3 consecutive seconds or 9 seconds cumulatively within 30 seconds, an early warning signal is issued to the operator to remind the operator to operate the relevant rotary mechanism to reduce the feeding speed of the bucket elevator 1. If it exceeds the upper threshold value for 7 consecutive seconds or 12 seconds cumulatively within 30 seconds, the lifting speed of the hoisting part 1-2 is reduced to 80% of the rated value. After each deceleration of the hoisting part 1-2, it is necessary to keep the motor torque current below the upper threshold value for at least 5 seconds. If the torque current still exceeds the upper threshold value for more than 3 seconds during the deceleration period, the chain bucket lifting speed is continuously reduced by 20%. Among them, 30 seconds is the rated time T1, and 7 seconds is the time it takes for the output belt conveyor 7 to transport the material from the receiving point to the ground belt conveyor;

[0037] S4, adjust the material flow that exceeds the expected flow through the output belt conveyor

[0038] The time it takes for the material to reach the receiving point of the output conveyor 7 from the rear arm belt scale 5 is measured as T2. Based on the material flow data of the rear arm belt scale 5, when the material flow exceeding the expected flow reaches the output conveyor 7, the operating speed of the output conveyor 7 is adjusted at a frequency of 1 Hz to limit the output material flow to no more than 5% of the expected value.

[0039] S5. Limit the material flow at the receiving point of the output belt conveyor

[0040] Calculations are based on the theoretical speed value of the output conveyor 7 after the speed reduction. When the material flow from the receiving hopper 6 exceeds the maximum upper limit of the equipment after the superposition, the output conveyor 7 is gradually increased until the output conveyor 7 reaches the maximum speed. If the material flow from the receiving hopper 6 of the output conveyor 7 is frequently too large, the drive motor of the boom conveyor 4 can also be converted to a variable frequency motor. By reducing the operating speed of the boom conveyor 4, the ability of the chain bucket continuous ship unloader's auxiliary conveyor to buffer materials can be further increased.

[0041] Under the premise of ensuring operating efficiency, the present invention controls the material flow of the chain bucket conveyor by caching materials. First, a linear function of the material flow and the chain bucket lifting torque is obtained. Then, by controlling the chain bucket lifting speed, the material flow arriving at the boom belt conveyor is preliminarily limited. Finally, by adjusting the speed of the output belt conveyor, the effect of controlling the output material flow of the chain bucket conveyor is achieved.

[0042] The above description is only a preferred embodiment of the present invention and does not limit the scope of the present invention. Any equivalent structural changes made using the contents of the present invention description and drawings are included in the scope of the present invention.

Claims

1. A method for controlling material flow of a chain bucket continuous ship unloader, comprising the following steps: S1. Install the front arm belt scale. The front arm belt scale is located at the feeding end of the arm belt conveyor; S2. Obtain the linear function of material flow and torque current, Record the material flow rate of the front arm belt scale and the torque current of the corresponding bucket elevator's hoisting motor during continuous operation, perform linear analysis, intercept the data with a linear coefficient R² ≥ 0.8, and fit the linear function y = kx + b to obtain the values of k and b. y is the material flow rate, x is the torque current, and the rated time for the material to travel from the hoisting part to the rear arm belt scale is T1; S3, limit the material flow by controlling the lifting torque of the bucket elevator, Calculate the torque current of the bucket elevator's hoist motor corresponding to the expected operating flow rate according to the linear function in step S2, and use it as the upper threshold. If the upper threshold is exceeded, an alarm is triggered and the bucket elevator's feeding speed is reduced. S4, adjust the material flow that exceeds the expected flow through the output belt conveyor, Measure the time T2 from the rear arm belt scale for the material to reach the receiving point of the output belt conveyor. According to the material flow data of the rear arm belt scale, when the material flow exceeding the expected flow reaches the output belt conveyor, adjust the running speed of the output belt conveyor; S5, limit the material flow at the receiving point of the output belt conveyor, Calculation is based on the theoretical speed value of the output belt conveyor after deceleration. When the material flow of the receiving hopper exceeds the maximum upper limit of the equipment after superposition, the output belt conveyor speed is gradually increased until the output belt conveyor speed reaches the maximum value. In step S3, the torque current of the motor of the lifting part of the bucket elevator is continuously detected. When the torque current exceeds the upper threshold for 9 seconds in 3 consecutive seconds or 30 seconds, an early warning signal is issued to reduce the feeding speed; if the torque current exceeds the upper threshold for 12 seconds in 7 consecutive seconds or 30 seconds, the lifting speed of the lifting part is reduced to 80% of the rated value. After each deceleration of the bucket elevator, the torque current of the motor must be kept below the upper threshold for at least 5 seconds. If the torque current still exceeds the upper threshold for more than 3 seconds during the deceleration period, the lifting speed of the lifting part is continuously reduced by 20%.

2. The method for controlling material flow of a chain bucket continuous ship unloader according to claim 1, characterized in that: In step S2, when the bucket elevator operates normally and continuously at the rated speed for more than 30 minutes, the material flow rate value and the torque current of the motor during the period are recorded.

3. The method for controlling material flow of a chain bucket continuous ship unloader according to claim 1, characterized in that: In step S2, the torque current of the motor when the material enters the lower end of the lifting part of the bucket elevator corresponds to the material flow rate when the material reaches the front arm belt scale after a fixed conveying time.

4. The method for controlling material flow of a chain bucket continuous ship unloader according to claim 1, characterized in that: In step S4, the adjustment frequency is 1 Hz, and the output material flow is limited to not exceed 5% of the expected value.

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