A real-time monitoring system and method for coal flow of scraper conveyor

Abstract

The present invention provides a real-time monitoring system and method for the coal flow of a scraper conveyor, which belongs to the technical field of coal flow monitoring. It solves the problem that the existing method does not organically combine the coal cutting amount and the coal sweeping amount in the coal flow monitoring of the scraper conveyor, resulting in uneven coal flow distribution on the scraper conveyor. It includes a coal flow monitoring device for real-time collection of coal flow data generated by left / right rocker arm coal cutting or coal sweeping during the coal mining process. The two coal flow monitoring devices are respectively connected to a coal flow solver, and the coal flow solver communicates with the coal mining machine control system and the scraper conveyor control system respectively. The coal flow solver is used to receive data collected by the coal flow monitoring device on the left / right rocker arm, and solve the collected data into actual coal flow, and send the left / right rocker arm coal flow and total coal flow data to the coal mining machine control system and the scraper conveyor control system. The present invention is applied to coal flow monitoring and regulation of scraper conveyors on fully mechanized mining working faces.

Description

Technical Field

[0001] The invention provides a scraper conveyor coal flow real-time monitoring system and method, belonging to the technical field of coal flow monitoring. Background Art

[0002] A scraper conveyor in a fully mechanized coal mining face uses an open chute as a carrier for coal, gangue, or other materials. A scraper is attached to a chain to form a scraper chain, which serves as the traction element. When the head drive is activated, the sprocket on the head shaft rotates, causing the scraper chain to circulate, moving the material along the chute and unloading it at the head. The scraper chain then loops around the sprocket in a stepless closed loop, completing material transportation. The scraper conveyor is responsible for continuously and efficiently transporting coal cut by the shearer in the face to the transfer machine, which then transfers it to the chute belt conveyor via the transfer machine and crusher. However, in actual operation, the distribution of coal flow on the scraper conveyor is often uneven, with variations in coal flow exhibiting spatiotemporal characteristics. This is due to a combination of factors, including the shearer's cutting method, the coal seam's geological conditions, and the scraper conveyor's operating parameters.

[0003] Uneven coal flow distribution on a scraper conveyor can lead to uneven loads during operation, affecting its operating efficiency. Uneven loads can cause increased wear on the scraper chain, leading to increased energy consumption and increased equipment failure rates. Uneven coal flow distribution can also pose a threat to safe production. For example, when excessive coal accumulates on a scraper conveyor, it can cause equipment overload, jamming, or even damage, leading to safety accidents. Uneven coal flow distribution also increases the difficulty and cost of equipment maintenance. Due to increased equipment wear and increased failure rates caused by uneven loads, more frequent equipment maintenance and overhauls are required, increasing maintenance costs and downtime. In summary, the coal flow conditions of the scraper conveyor on the fully mechanized mining face have a significant impact on the equipment's operating efficiency, safe production, and equipment maintenance.

[0004] At present, there are some technical solutions that use sensors or image processing to monitor the coal flow of scraper conveyors. However, the existing technical solutions ignore the separate monitoring of the coal cutting and sweeping amounts of the coal mining machine inputting the coal flow of the scraper conveyor, and cannot fundamentally solve the problem of uneven coal flow distribution on the scraper conveyor. Summary of the Invention

[0005] In order to solve the problem that the existing method does not organically combine the coal cutting amount and the coal sweeping amount in the scraper conveyor coal flow monitoring, resulting in uneven coal flow distribution on the scraper conveyor, the present invention proposes a real-time monitoring system and method for the scraper conveyor coal flow.

[0006] The technical solution adopted by the present invention is: a real-time monitoring system for coal flow of a scraper conveyor, including a coal flow monitoring device installed on the left / right rocker arm of the coal mining machine for real-time collection of coal flow data generated by the left / right rocker arm cutting or sweeping coal during the coal mining process. The two coal flow monitoring devices are respectively connected to the coal flow solver, and the coal flow solver communicates with the coal mining machine control system and the scraper conveyor control system respectively. The coal flow solver is used to receive the data collected by the coal flow monitoring device on the left / right rocker arm, and solve the collected data into actual coal flow, and send the left / right rocker arm coal flow and total coal flow data to the coal mining machine control system and the scraper conveyor control system respectively.

[0007] Furthermore, the coal flow monitoring device can scan the coal flow of the scraper conveyor by adopting radar recognition, laser ranging, image recognition or other technologies to obtain the cross-sectional profile height information of the coal flow.

[0008] Furthermore, the coal flow solver calculates the actual coal flow cross-sectional area by comparing the contour lines of the scraper conveyor when loaded and when unloaded, thereby obtaining the actual coal flow rate.

[0009] Furthermore, the calculation formula of coal flow is as follows:

[0010] Q = A × V × Δt;

[0011] In the above formula: Q is the coal flow rate, A is the actual coal flow cross-sectional area, Δt is the measurement time interval, and V is the average flow velocity within the measurement time interval.

[0012] A method for real-time monitoring of coal flow in a scraper conveyor comprises the following steps:

[0013] S1: Install two coal flow monitoring devices in the scraper conveyor coal flow real-time monitoring system at appropriate positions on the left / right rocker arms of the shearer, start the system, and collect coal flow data generated by the shearer when cutting or sweeping coal;

[0014] S2: Monitoring and Adjusting the Coal Cutting and Sweeping Volumes of the Coal Miner: The coal flow solver receives coal flow data collected by the coal flow monitoring device, calculates the coal flow rates of the left and right rocker arms, and sends this data to the shearer control system. The shearer control system adjusts the shearer's coal sweeping speed or force, as well as the traction speed, based on the real-time coal flow data. This ensures synchronized control of coal cutting and sweeping operations, preventing excessive cutting and untimely sweeping, or excessive cutting and idling of the sweeping device.

[0015] S3: Control of the total coal flow of the scraper conveyor: Through the adjustment of the coal cutting amount and the coal sweeping amount by the coal mining machine control system, the total coal flow of the scraper conveyor is controlled within a relatively stable and uniform trend and range. When local overload or no load is detected, the chain speed of the scraper conveyor is automatically adjusted to achieve load balancing adjustment of the scraper conveyor.

[0016] Furthermore, in step S2, it is determined whether the left / right rocker arm upper coal flow monitoring device collects the coal cutting amount data or the coal sweeping amount data according to the actual running direction of the coal shearer;

[0017] When the shearer is mining in the left direction, the coal flow monitoring device on the left rocker arm collects data on the amount of coal cut. In this case, the left rocker arm is the coal cutting arm, and the coal flow monitoring device on the right rocker arm collects data on the amount of coal swept. In this case, the right rocker arm is the coal sweeping arm.

[0018] When the coal mining machine moves to the right to mine coal, the coal flow monitoring device on the right rocker arm collects data on the amount of coal cut, and the coal flow monitoring device on the left rocker arm collects data on the amount of coal swept.

[0019] Furthermore, the coal cutting amount is controlled according to the real-time monitoring data of the coal sweeping amount, so that the total amount of coal sweeping and coal cutting is kept relatively balanced, so that the coal flow load of the scraper conveyor is relatively balanced.

[0020] Furthermore, the traction speed of the coal shearer is dynamically adjusted according to the real-time monitoring data of the coal cutting amount to ensure the coal cutting efficiency and coal quantity uniformity.

[0021] Furthermore, in step S3, when the sum of the coal cutting amount and the coal sweeping amount exceeds the carrying capacity of the scraper conveyor or is lower than the production demand, the system sends an alarm signal; and when the coal flow increases, the chain speed of the scraper conveyor is increased; when the coal flow decreases, the chain speed of the scraper conveyor is reduced.

[0022] Furthermore, the chain speed of the scraper conveyor adopts an adaptive correction algorithm, and the chain speed dynamic compensation formula is:

[0023] Vcorrected=Vbase+ΔK* ( Qactual / Qdesign-1 ) 2 +β*(Imotor / Irated);

[0024] Where: V correcte Represents the corrected chain speed; V base Represents the design chain speed, and the adjustment range is generally 0.8-1.5m / s; Q actual is the actual coal transport volume, i.e. the sum of the coal cutting volume and coal sweeping volume; Q designis the designed transport capacity of the scraper conveyor; ΔK is the coal flow deviation coefficient, ranging from 0.2 to 0.8. A higher value is used when the gangue content is greater than 30%; β is the motor load supplement factor, with a default value of 0.15, which can be adaptively adjusted according to voltage fluctuations; I motor is the real-time motor current, and the average value of the motors before and after the drive unit is taken during calculation; I rated is the rated current of the motor. When calculating, the average current of the motors before and after the drive unit is taken.

[0025] The beneficial effects of the present invention compared to the prior art are:

[0026] (1) Avoid uneven load problems during the operation of scraper conveyors and improve coal mining production efficiency;

[0027] (2) Uneven load reduction may lead to increased wear of the scraper chain, increased energy consumption, and increased equipment failure rate;

[0028] (3) Improved the safety production rate of coal mining process in fully mechanized mining face;

[0029] (4) Reduce the occurrence of increased equipment maintenance difficulty and cost due to uneven distribution of coal flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings:

[0031] Figure 1 It is a structural block diagram of the system of the present invention;

[0032] Figure 2 This is a working principle diagram of the coal flow monitoring device and the coal flow solver;

[0033] Figure 3 Schematic diagram of system installation and operation;

[0034] In the figure: 1 is a coal mining machine, 2 is a scraper conveyor, 3 is a left rocker arm coal flow monitoring device, and 4 is a right rocker arm coal flow monitoring device. DETAILED DESCRIPTION

[0035] like Figures 1 to 3As shown, the present invention provides a real-time monitoring system for coal flow of a scraper conveyor, which is mainly composed of a left rocker arm coal flow monitoring device 3, a right rocker arm coal flow monitoring device 4, a coal flow solver and corresponding interface modules. The left rocker arm coal flow monitoring device 3 and the right rocker arm coal flow monitoring device 4 are used to collect in real time the coal flow data generated by the left / right rocker arm of the coal mining machine 1 during the coal mining process; the coal flow solver is used to receive the collected data of the left rocker arm coal flow monitoring device 3 and the right rocker arm coal flow monitoring device 4, accurately solve the collected data into actual coal flow, and send the left / right rocker arm coal flow, total coal flow and other data to the coal mining machine control system and the scraper conveyor control system respectively. In this embodiment, the interface form of the interface module is not specifically limited.

[0036] The left rocker arm coal flow monitoring device 3 and the right rocker arm coal flow monitoring device 4 can use radar recognition, laser ranging, image recognition or other technologies to scan the coal flow of the scraper conveyor 2 to obtain the cross-sectional profile height information of the coal flow. Figure 2 As shown, by comparing the contour lines of the scraper conveyor 2 when it is unloaded, the actual coal flow cross-sectional area can be calculated, and then the actual coal flow rate can be obtained.

[0037] There is no single mathematical model for calculating the actual coal flow rate; it depends on the specific measurement method and application scenario. However, based on the above information about the actual coal flow cross-sectional area, an approximate mathematical model can be constructed to calculate the coal flow rate. The following is a possible mathematical model:

[0038] Within the measurement time interval Δt, the coal flow rate Q can be calculated by multiplying the actual coal flow cross-sectional area A by the average flow velocity V within the period, that is: Q = A × V × Δt.

[0039] In addition, in order to achieve real-time and accurate monitoring of the coal flow of the scraper conveyor 2 and dynamically adjust the coal cutting amount according to the coal sweeping amount during the coal mining process, thereby effectively controlling the total coal flow of the scraper conveyor 2, the present invention also proposes a real-time monitoring method for the coal flow of the scraper conveyor, comprising the following steps:

[0040] S1: Installation and configuration of the coal flow monitoring system for scraper conveyor 2. The specific implementation method is as follows:

[0041] (1) Installation location: Install a coal flow monitoring device on each of the left and right rocker arms of the coal mining machine 1, such as Figure 3 The installation position in the figure is adjustable so as to accurately capture the change in the amount of coal produced by the coal shearer 1 when cutting or sweeping coal.

[0042] (2) Monitoring Principle: The coal flow monitoring device can use radar sensors, laser ranging sensors, or image recognition technology to monitor the coal flow in real time. These technologies can accurately measure the size, density, and volume of coal blocks produced by the coal mining machine 1 during the cutting process, thereby calculating the coal flow.

[0043] (3) Data transmission: The coal flow monitoring device should transmit real-time data to the shearer control system and the scraper conveyor control system via wired or wireless means. Ensure the stability and real-time nature of data transmission so that timely adjustments can be made.

[0044] S2: Monitoring and adjusting the coal cutting and sweeping amount of the shearer 1. The specific implementation steps are as follows:

[0045] S2.1: The coal flow solver calculates the left and right rocker arm coal flow rates using a built-in mathematical model and sends this data to the shearer control system. If shearer 1 is mining in the left direction, the left rocker arm coal flow monitoring device 3 collects data on the amount of coal cut (hence, the left rocker arm is the cutting arm), while the right rocker arm coal flow monitoring device 4 collects data on the amount of coal swept (hence, the right rocker arm is the sweeping arm). If shearer 1 is mining in the right direction, the right rocker arm coal flow monitoring device 4 collects data on the amount of coal cut, while the left rocker arm coal flow monitoring device 3 collects data on the amount of coal swept.

[0046] S2.2: Coal sweeping volume monitoring: According to the actual working conditions of the coal shearer 1, determine whether the left rocker arm coal flow monitoring device 3 and the right rocker arm coal flow monitoring device 4 collect data on the coal cutting volume or the coal sweeping volume. These data will serve as the basis for adjusting the coal sweeping volume.

[0047] S2.3: Coal sweeping amount adjustment: The coal cutting amount is controlled according to the real-time monitoring data of the coal sweeping amount. The coal shearer control system can dynamically adjust the coal cutting speed or force of the coal cutting arm of the coal shearer 1 to ensure that the total amount of coal sweeping and coal cutting remains relatively balanced, so that the coal flow load of the scraper conveyor 2 is relatively balanced.

[0048] S2.4: Speed ​​adjustment of shearer 1: Adjust the traction speed of shearer 1 according to the real-time monitoring data of the coal cutting amount to ensure the coal cutting efficiency and coal quantity uniformity, and avoid the occurrence of poor coal sweeping effect.

[0049] S3: Control of the total coal flow of scraper conveyor 2. The specific implementation steps are as follows:

[0050] S3.1: Total Coal Flow Control: By coordinating the coal cutting and sweeping rates with the shearer control system, the total coal flow of Scraper Conveyor 2 can be controlled to maintain a relatively stable and uniform trend and range. Based on real-time coal flow data, combined with Scraper Conveyor 2's conveying capacity and production needs, the shearer control system automatically adjusts the coal cutting speed of shearer 1 and the coal sweeping speed of the coal sweeping arm to maintain the total coal flow of Scraper Conveyor 2 within the set range.

[0051] S3.2: Alarm and protection: When the sum of the coal cutting volume and the coal sweeping volume exceeds the carrying capacity of the scraper conveyor 2 or is lower than the production demand, the system will issue an alarm signal; and when the coal flow increases, the chain speed of the scraper conveyor 2 will be increased; when the coal flow decreases, the chain speed of the scraper conveyor 2 will be reduced.

[0052] The chain speed of scraper conveyor 2 adopts an adaptive correction algorithm, and the chain speed dynamic compensation formula is:

[0053] Vcorrected=Vbase+ΔK* ( Qactual / Qdesign-1 ) 2 +β*(Imotor / Irated);

[0054] Where: V correcte Represents the corrected chain speed; V base Represents the design chain speed, and the adjustment range is generally 0.8-1.5m / s; Q actual is the actual coal transport volume, i.e. the sum of the coal cutting volume and coal sweeping volume; Q design is the designed transport capacity of the scraper conveyor; ΔK is the coal flow deviation coefficient, ranging from 0.2 to 0.8. A higher value is used when the gangue content is greater than 30%; β is the motor load supplement factor, with a default value of 0.15, which can be adaptively adjusted according to voltage fluctuations; I motor is the real-time motor current, and the average value of the motors before and after the drive unit is taken during calculation; I rated is the rated current of the motor. When calculating, the average current of the motors before and after the drive unit is taken.

[0055] By implementing the above method, real-time and accurate monitoring of the coal flow of the scraper conveyor 2 can be achieved, and the coal cutting amount can be dynamically adjusted in combination with the coal sweeping amount of the coal mining machine 1, thereby effectively controlling the total coal flow of the scraper conveyor 2 and improving production efficiency and safety.

[0056] The present invention will be further described below with reference to specific embodiments.

[0057] Example 1

[0058] Install a video AI coal flow monitoring device on the left / right rocker arm of coal mining machine 1. The installation position is referenced Figure 3The position is adjustable to accurately capture changes in coal volume during shearer 1's cutting or sweeping. Two video AI coal flow monitoring devices collect left and right rocker arm coal flow monitoring data and transmit it to the coal flow solver via 100M Ethernet twisted pair cables. The coal flow solver accurately converts the collected data into actual coal flow and transmits data such as left / right rocker arm coal flow and total coal flow to the shearer control system and scraper conveyor control system via 100M Ethernet twisted pair cables.

[0059] The video AI coal flow monitoring device uses video recognition technology to scan the coal flow of scraper conveyor 2 and extract image information of the coal flow surface. Technologies that may be involved include image enhancement, filtering, edge detection, etc. to improve image quality and clarity. Then, image processing technology is used to identify and extract the contour information of the coal flow surface. When scraper conveyor 2 is in an unloaded state, the same video recognition technology is used to extract the contour line of scraper conveyor 2, which will serve as the baseline for the subsequent calculation of the actual coal flow cross-sectional area. The contour of the coal flow surface is compared with the unloaded contour, and the difference between the two is calculated to determine the actual coal flow cross-sectional contour. The actual coal flow cross-sectional area is calculated using mathematical models such as integration and differential method. Finally, the coal flow is calculated using the possible approximate mathematical model Q = A × V × Δt constructed above.

[0060] Based on the actual operating conditions of shearer 1, the left rocker arm coal flow monitoring device 3 is configured to monitor the amount of coal (coal cut) when shearer 1 is cutting to the left, while the right rocker arm coal flow monitoring device 4 is configured to monitor the amount of coal when shearer 1 is cutting to the right. Based on real-time monitoring data on the amount of coal swept, the shearer control system dynamically adjusts the cutting speed or force of shearer 1's cutting arm to control the amount of coal cut. For example, as the amount of coal swept increases, the cutting speed of the cutting arm should also be increased to maintain a stable coal flow rate for scraper conveyor 2. While adjusting the amount of coal cut based on real-time monitoring data on the amount of coal swept, the traction speed of shearer 1 is further adjusted to avoid poor coal sweeping results.

[0061] When the total amount of coal cut and swept exceeds the carrying capacity of the scraper conveyor 2 or is lower than the production demand, the system sends an alarm signal and suspends the coal mining operation or adjusts the operating speed of the scraper conveyor 2.

[0062] Example 2

[0063] Install a radar signal coal flow monitoring device on the left / right rocker arm of coal mining machine 1. The installation position is referenced to Figure 3The position is adjustable to accurately capture changes in coal volume caused by shearer 1 cutting or sweeping coal. Two radar coal flow monitoring devices collect coal flow monitoring data from the left and right rocker arms, respectively. This data is then transmitted to the coal flow solver via a wireless Wi-Fi network. The coal flow solver accurately converts the collected data into actual coal flow and transmits data such as left / right rocker arm coal flow and total coal flow to the shearer control system and scraper conveyor control system via a 100M Ethernet twisted pair cable.

[0064] The radar signal coal flow monitoring device uses radar recognition technology, specifically laser radar, which measures the distance to a target object by emitting a laser beam and receiving the reflected signal. The laser radar is installed in an appropriate location to continuously scan the coal flow on scraper conveyor 2. During the scanning process, the laser radar records the distance and angle information of each scanning point, thereby constructing a cross-sectional profile of the coal flow. A similar scan is also performed when scraper conveyor 2 is unloaded to obtain the unloaded contour line of scraper conveyor 2. By comparing the coal flow cross-sectional profile with the unloaded contour line, the actual cross-sectional profile of the coal flow can be calculated, and the actual cross-sectional area of ​​the coal flow can be calculated using mathematical models such as integration and differential element methods.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A real-time monitoring method for coal flow in a scraper conveyor, characterized by: The following steps are involved: S1: Install two coal flow monitoring devices in the scraper conveyor coal flow real-time monitoring system at appropriate positions on the left / right rocker arms of the shearer, start the system, and collect coal flow data on the scraper conveyor when the shearer is cutting or sweeping coal; The scraper conveyor coal flow real-time monitoring system includes a coal flow monitoring device installed on the left / right rocker arm of the coal mining machine for real-time collection of coal flow data generated by the left / right rocker arm cutting or sweeping coal on the scraper conveyor during the coal mining process. The two coal flow monitoring devices are respectively connected to a coal flow solver, and the coal flow solver communicates with the coal mining machine control system and the scraper conveyor control system respectively. The coal flow solver is used to receive data collected by the coal flow monitoring device on the left / right rocker arm, and solve the collected data into actual coal flow, and send the left / right rocker arm coal flow and total coal flow data to the coal mining machine control system and the scraper conveyor control system respectively; S2: Monitoring and adjusting the shearer's coal cutting and sweeping volume: The coal flow solver receives coal flow data collected by the coal flow monitoring device, calculates the left / right rocker arm coal flow, and sends the left / right rocker arm coal flow data to the shearer control system. The shearer control system adjusts the shearer's sweeping speed or force and traction speed based on the monitored real-time coal flow data. S3: Control of the total coal flow of the scraper conveyor: Through the adjustment and coordination of the coal cutting amount and the coal sweeping amount by the coal mining machine control system, the total coal flow of the scraper conveyor is controlled within a relatively stable and uniform trend and range.

2. A method for real-time monitoring of coal flow in a scraper conveyor according to claim 1, characterized in that: The coal flow monitoring device scans the coal flow surface of the scraper conveyor by adopting radar recognition, laser ranging or image recognition technology to obtain the cross-sectional profile height information of the coal flow.

3. A method for real-time monitoring of coal flow in a scraper conveyor according to claim 2, characterized in that: The coal flow solver calculates the actual coal flow cross-sectional area by comparing the contour lines of the scraper conveyor when loaded and when unloaded, thereby obtaining the actual coal flow rate.

4. A method for real-time monitoring of coal flow in a scraper conveyor according to claim 3, characterized in that: The calculation formula of coal flow is as follows: Q = A × V × Δt; In the above formula: Q is the coal flow rate, A is the actual coal flow cross-sectional area, Δt is the measurement time interval, and V is the average flow velocity within the measurement time interval.

5. The method for real-time monitoring of coal flow in a scraper conveyor according to claim 1, characterized in that: In step S2, it is determined whether the left / right rocker arm upper coal flow monitoring device collects coal cutting amount data or coal sweeping amount data according to the actual running direction of the coal shearer; When the shearer is mining in the left direction, the coal flow monitoring device on the left rocker arm collects data on the amount of coal cut. In this case, the left rocker arm is the coal cutting arm, and the coal flow monitoring device on the right rocker arm collects data on the amount of coal swept. In this case, the right rocker arm is the coal sweeping arm. When the coal mining machine moves to the right to mine coal, the coal flow monitoring device on the right rocker arm collects data on the amount of coal cut, and the coal flow monitoring device on the left rocker arm collects data on the amount of coal swept.

6. A method for real-time monitoring of coal flow in a scraper conveyor according to claim 5, characterized in that: Based on the real-time monitoring data of the coal cutting volume, the shearer control system dynamically adjusts the coal sweeping speed or strength of the shearer sweeping arm to keep the coal sweeping volume and coal cutting volume balanced.

7. A method for real-time monitoring of coal flow in a scraper conveyor according to claim 6, characterized in that: While adjusting the coal sweeping volume according to the real-time monitoring data of the coal cutting volume, the coal shearer control system maintains a uniform coal sweeping volume by adjusting the traction speed of the coal shearer.

8. The method for real-time monitoring of coal flow in a scraper conveyor according to claim 5, characterized in that: In step S3, when the coal sweeping amount exceeds the carrying capacity of the scraper conveyor or is lower than the production demand, the system sends an alarm signal.

9. A method for real-time monitoring of coal flow in a scraper conveyor according to claim 6, characterized in that: The shearer control system dynamically adjusts the sweeping speed or force of the shearer sweeping arm by correspondingly slowing down the sweeping speed of the sweeping arm when the amount of coal cut increases to keep the coal flow of the scraper conveyor stable.

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