The equipment includes: stone sand making machine and belt conveyor. Here is a brief introduction of these two equipments. In fact, the stone sand making machine is our commonly used impact crusher. Its working principle is: the material enters the crusher from the feeding hopper. The material is divided into two parts by a distributor, a part of which enters the high-speed rotating impeller from the middle of the distributor and is rapidly accelerated in the impeller. The acceleration can reach hundreds of times the acceleration of gravity, and then the speed is 60-70 meters per second. It is projected from the three equally-distributed flow paths of the impeller.
The current status of belt conveyor technology The development of foreign belt conveyor technology is very fast, and its performance is mainly in two aspects: on the one hand, the function of the belt conveyor is diversified, and the application scope is expanded, such as high inclination belt conveyor and tubular belt type. Conveyors, space turning belt conveyors and other models; on the other hand, the technology and equipment of the belt conveyors have been greatly developed, especially for large belt conveyors such as long distances, large transport volumes, and high belt speeds. Being the main direction of development, its core technology is to develop and apply dynamic analysis and monitoring technology of belt conveyors to improve the running performance and reliability of belt conveyors.
At present, the belt conveyor used in coal mines has reached the main technical indicators shown in Table 1. The key technologies and equipment have the following characteristics: (1) Large-scale equipment. Its main technical parameters and equipment are being developed towards large-scale development to meet the needs of high-yield and high-efficiency intensive production with an annual output of 300 to 5 million tons. (2) Dynamic analysis technology, mechatronics, computer monitoring and other high technologies are adopted. High-power soft start and automatic tensioning technologies are used to dynamically monitor and monitor conveyors, greatly reducing the dynamic tension of the conveyor belt, and the equipment running performance is good. , high transport efficiency. (3) The use of multi-motor drive and intermediate drive and its power balance, conveyor direction change operation and other technologies have theoretically limited the running length of the conveyor, and ensure the universality, interchangeability and unit of the conveyor system equipment. Drive reliability. (4) New, high-reliability key component technology. Such as CST, including a variety of advanced high-power drive and speed control device, high-life high-speed roller, self-cleaning roller device, high-efficiency tape device, fast self-moving tail and so on.
For example, the FSW1200/(2～3)×400(600) working face conveyor belt conveyor produced by FSW in the United Kingdom adopts the liquid-viscosity differential or frequency conversion speed-regulating device and the transportation capacity reaches over 3000 t/h. In combination with a new type of transshipment machine (such as the S500E produced by U.S. Jiuyi Company), it can automatically and quickly move with the work surface, reduce manual work, and increase production efficiency. 2 Status of Domestic Belt Conveyor Technology There are many varieties and types of belt conveyors manufactured in China. During the "Eighth Five-Year Plan" period, through the implementation of the national one-stop project of "Daily Production of 10,000 Tons of Comprehensive Mining Equipment", the technical level of belt conveyors has been greatly improved, and the key to the use of high-power, long-distance belt conveyors in underground coal mines Technological research and new production Lu development have made great progress. For example, large-angle long-distance belt conveyor complete sets of equipment, high-yield and high-efficiency working surfaces along the groove retractable belt conveyors, etc. have filled the gaps in China, and theoretical research has been conducted on key technologies for reducing belt conveyors and their major components. And product development, developed a variety of soft start and brake devices and PLC as the core of the programmable electronic control device, the drive system uses speed-type fluid coupling and planetary gear reducer. At present, the main technical characteristics of coal belt conveyors in China are shown in Table 2.
The Key Technology Differences of Large Belt Conveyors (1) Dynamic Analysis and Monitoring Technology of Belt Conveyors The key technology of long-distance, high-power belt conveyors is dynamic design and monitoring. It is the core technology that restricts the development of large-scale belt conveyors. . At present, China uses rigid theory to analyze and study belt conveyors and formulate calculation methods and design specifications. In the design, a very high safety system is used for the conveyor belt (generally taking n=10 or so), which is far from the actual situation. In fact, the conveyor belt is a viscoelastic body. The dynamic response of the conveyor belt to the starting and braking force of the drive device is a very complicated process for a long-distance belt conveyor. It cannot be simply explained and calculated by rigid body mechanics. The dynamic design method and application software of the belt conveyor have been developed. Dynamic analysis and dynamic monitoring of the dynamic tension of the conveyor on a large conveyor reduce the safety system of the conveyor belt, greatly prolong the service life, and ensure the reliable operation of the conveyor. As a result, the design of large belt conveyors has reached the highest level (belt safety factor n=5-6), and the cost of the conveyor equipment, especially the cost of the conveyor belt, has been greatly reduced.
Reliable, controlled soft-start technology and power equalization technology Long-distance and large-capacity belt conveyors, due to their large power, long distances, and multi-motor drive, must use soft-start to reduce the conveyor's braking tension, especially when multi-motor drives. In order to reduce the impact on the power grid, the soft starter should have a time-different slow start; it is also necessary to control the starting acceleration of the conveyor from 0.3 to 0.1 m/s2 to solve the problem of belt speed synchronizing between the carrier belt and the drive belt and the phenomenon of the conveyor belt swell. Reduce the impact on the components. Due to manufacturing error and motor characteristic error, the power of each driving point will appear unbalanced. Once a certain motor power is too large, it will cause a burning motor accident. Therefore, the power balance among the motors should be controlled and the balance accuracy must be improved. In China, a large number of variable-speed hydrodynamic couplings have been used to achieve the soft start and power balance of the conveyor, which solves the problems of starting and power balance and synchronization of long-distance belt conveyors. However, there is a certain gap between its adjustment accuracy and reliability compared with foreign countries.
In addition, long-distance high-power belt conveyors require a tape speed in addition to a coal belt speed. Although the speed-regulating fluid couplings achieve soft start and power balance, they need to be developed for long distances. The stepless hydraulic speed regulator. When stand-alone power >500 kW, controllable CST soft start shows superiority. Since the controlled soft start is the combination of the internal gear ring of the planetary gear reducer and the wet friction clutch (ie, viscous drive). Through the proportional valve and control system to achieve soft start and power balance, the adjustment accuracy of up to 98%. However, it is expensive and urgently needs localization. 3.2 Technical performance gap The main performance and parameters of belt conveyors in China can no longer meet the needs of high-yield and high-efficiency mines, especially the key components and functions of the slot retractable belt conveyor, such as self-moving machine tails and high-efficiency storage belts. There is a big gap with foreign countries such as tensioning devices. (1) Installed power The maximum installed power of the conveyor belt conveyor in the working face of the working face is 4×250 kW, and the foreign product can reach 4×970 kW. The installed power of the domestic belt conveyor is approximately 30% to 40% of the foreign product. The installed power of fixed belt conveyors differs even more. (2) Transportation capacity The maximum capacity of belt conveyors in China is 3,000 t/h, which has reached 5,500 t/h in foreign countries. (3) Maximum belt width China's belt conveyor is 1400 mm, foreign maximum is 1830 mm. (4) Belt speed Due to the limitation of the rotation speed of the roller, the speed of belt conveyors in China is 4m/s, and that of foreign machines is 5m/s or more. (5) The transport length of the working face along the trough is 3000 m in China.
7300m abroad. (6) With the continuous appearance of high-yield and high-efficiency working face from the tail of the shifting machine, it is required that the trailing end of the retractable belt conveyor be rapidly self-moved with the rapid advancement of the working face. Domestic relocation mainly depends on imports, and there are mainly two types: (a) Self-moving tail devices manufactured by the British company LONGWALL, which are moved together with the transponders. (b) Self-relocating tailstock devices produced by Germany DBT. The former has only one propulsion cylinder, while the latter has two propulsion cylinders. The self-proclaimed tail produced by LONGWALL Company is used on a conveyor with a domestic bandwidth of 1.2 m. The disadvantage is that the amount of deviation of the conveyor belt at the tail of the self-advancing machine is too small, the rectifying ability is weak, and the rigidity is poor. The effect of the self-advancing machine produced in Germany is superior to the former in the domestic use. The horizontal and vertical two directions are equipped with a misalignment cylinder and the rectification ability is strong.
Therefore, the former needs to be improved, while the latter needs to be developed. However, the requirements for the self-advancing machine tail are common, and it is necessary to meet the requirements of the non-slippery during the normal operation of the conveyor, and to meet the requirement of rapid self-movement when the conveyor is not stopped. (7) High efficient storage belt and tensioning device China adopts closed storage belt structure and winch red tightness. The tensioning trolley is easy to derail and the conveyor belt is easy to deviate. When the conveyor belt is retracted, the idler trolley is not self-moving and needs to be manually changed. Maintenance trouble. The use of advanced open storage belt devices and high-precision high-torque, large-stroke automatic tensioning equipment abroad, the roller car can automatically telescope in place with the conveyor belt. Conveyor with easy deviation, there will be no derailment. (8) Conveyor models have few varieties, single functions, limited scope of use, and can not fully exert their effectiveness, such as expanding the functions of transporting people, transporting materials, or two-way transportation, so as to use more than one machine; In addition, the geological conditions of coal mines in China are different. Very large, there are often some special requirements in the layout of the transportation system, such as bending, large inclination (>+25°) until vertical lifting, etc. Special type special belt belt conveyors should be developed. 3.3 Differences in reliability and life (1) Tensile strength of conveyor belts The maximum number of fire-retardant conveyor belts produced in China for fabrics is 2500 N/mm and 3150 N/mm in foreign countries. Steel cord core flame-retardant conveyor belt is up to 4000 N/mm and foreign is 7000 N/mm. (2) Conveyor belt joint strength The strength of the conveyor belt joints in China is 50% to 65% of the master belts, and 70% to 75% of the parent belts in foreign countries. (3) Roller life The existing idler technology in China compared with foreign countries, short life, low speed and high resistance, while the new type of oiling idler used in the United States, its running resistance is small, the bearing adopts thin oil lubrication, greatly improves the support Roll life, and can be used as a high-speed roller on the belt conveyor, a wide range of uses, significant economic benefits. China conveyor idler life is 20,000 hours, and foreign idler life is 5 to 90,000 hours. Domestic idler life is only 30% to 40% of foreign products.
Conveyor reducer life China conveyor reducer life of 20,000 h, foreign reducer life of 70,000 h. (5) The belt conveyor has poor reliability when it is operated up and down. 3.4 The gap on the control system (1) The driving mode The speed control fluid coupling and the hardened gear reducer are used in China. There are various transmission modes in foreign countries, such as BOSS system and CST controllable transmission system. High control accuracy. (2) Monitoring Device The foreign conveyor has adopted high-end programmable logic controller PLC, developed advanced program soft-bo and integrated power supply relay control technology and complete automatic monitoring system for data mining, processing, storage, transmission, fault diagnosis and inquiry. China's conveyor only uses a mid-range programmable controller to control the start, normal operation, and shutdown of the conveyor. Although it can be used in conjunction with controllable activation (branch) devices, it can achieve controllable activation, speed synchronization, power balance, etc., but it has no automatic proximity devices, no fault diagnosis and inquiries. (3) Conveyor protection devices In addition to the installation of protection devices to prevent deviations, slippage, tearing, overfilling, and automatic sprinkler dust reduction in foreign conveyor belts, many new types of monitoring devices have been developed in recent years: transmission drums and turning rollers. And roller group temperature monitoring system; smoke alarm and automatic fire extinguishing device; fiber-woven conveyor belt longitudinal tear and joint monitoring system; explosion-proof electronic conveyor belt scale automatic metering system. These new protection systems are basically blank in our country. In China, the existing skid-proof, coal-burning, coal-mesh full-lid protection, anti-runaway, over-temperature watering, and smoke alarm devices have low reliability, sensitivity, and longevity.
Development trend of belt conveyor technology in coal mines 4.1 Equipment enlargement and transportation capacity enhancement In order to meet the needs of high production and efficient intensive production, the conveyor capacity of belt conveyors should be increased. Long distance, high belt speed, large capacity, and high power are inevitable trends for future development, and are also the development direction of high-yield and high-efficiency mine transportation technologies. In the next 10 years, the transportation volume should be increased to 3000-4000 t/h, the speed should be increased to 4-6 m/s, and the conveying length should reach 3000 m for the retractable belt conveyor. For steel cord core belt conveyors that need to be extended to more than 5000m, single-frame drive power requirements are 1000 to 1500 kW, conveyor belt tensile strength is up to 6000 N/mm (steel wire cores) and 2500 N/mm (steel cord cores) . Especially with the development of the telescoping conveyor technology for down-hole coal mining, with the emergence of high-yield and high-efficiency working face and the continuous development of coal technology, the existing scalable belt conveyors are difficult to adapt to high yields regardless of their main parameters or operating performance. With the requirements of high-efficiency working face, coal mines urgently need long-distance, large-capacity, high-power slot-retractable belt conveyors with larger main parameters, more advanced technologies, and more reliable performance to improve the design of belt conveyor technology in China. Level, to fill the gaps in the domestic, close to and catch up with the technological level of the international advanced industrial countries. It contains seven key technologies: (1) dynamic analysis and monitoring technology of belt conveyors; (2) soft start and power balance technology; (3) intermediate drive technology; (4) automatic tensioning technology; (5) new high-speed high-speed idler technology; (6) rapid Self-moving tail technology; (7) High-efficiency storage technology. Improve the performance of components and reliability The high and low equipment operating rates mainly depend on the performance and reliability of the components.
In addition to further improving and improving the performance and reliability of existing components, new technologies and components such as high-performance controlled soft-start technology, dynamic analysis and monitoring technology, high-efficiency tape storage devices, and rapid self-development have also been continuously researched and researched. Transfer tails, high-speed idlers, etc., to further enhance the performance of the belt conveyor. 4.3 to expand the function, a multi-purpose machine to expand the transport of people, transport materials or two-way transport and other functions, so that a multi-purpose machine to make it play the greatest economic benefits. Develop special belt conveyors such as curved belt conveyors, large angle or vertical lift conveyors. (2) Reliable controllable soft-start technology and power equalization technology Long-distance and large-capacity belt conveyors must be soft-started to reduce the braking tension of conveyors due to their large power, long distances, and multi-motor drive, especially when multi-motor drives. . In order to reduce the impact on the power grid, the soft starter should have a time-different slow start; it is also necessary to control the starting acceleration of the conveyor from 0.3 to 0.1 m/s2 to solve the problem of belt speed synchronizing between the carrier belt and the drive belt and the phenomenon of the conveyor belt swell. Reduce the impact on the components. Due to manufacturing error and motor characteristic error, the power of each driving point will appear unbalanced. Once a certain motor power is too large, it will cause a burning motor accident. Therefore, the power balance among the motors should be controlled and the balance accuracy must be improved. In China, a large number of variable-speed hydrodynamic couplings have been used to achieve the soft start and power balance of the conveyor, which solves the problems of starting and power balance and synchronization of long-distance belt conveyors. However, there is a certain gap between its adjustment accuracy and reliability compared with foreign countries. In addition, long-distance high-power belt conveyors require a tape speed in addition to a coal belt speed. Although the speed-regulating fluid couplings achieve soft start and power balance, they need to be developed for long distances. The stepless hydraulic speed regulator. When stand-alone power >500 kW, controllable CST soft start shows superiority. Since the controlled soft start is the combination of the internal gear ring of the planetary gear reducer and the wet friction clutch (ie, viscous drive). Through the proportional valve and control system to achieve soft start and power balance, the adjustment accuracy of up to 98%. However, it is expensive and urgently needs localization.
Technical performance gap The main performance and parameters of belt conveyors in China can no longer meet the needs of high-yield and high-efficiency mines, especially the key components and their functions such as self-aligning conveyor belts and high-efficiency storage belts. Tensioning devices have a big gap with foreign countries. (1) Installed power The maximum installed power of the conveyor belt conveyor in the working face of the working face is 4×250 kW, and the foreign product can reach 4×970 kW. The installed power of the domestic belt conveyor is approximately 30% to 40% of the foreign product. The installed power of fixed belt conveyors differs even more. (2) Transportation capacity The maximum capacity of belt conveyors in China is 3,000 t/h, which has reached 5,500 t/h in foreign countries. (3) Maximum belt width China's belt conveyor is 1400 mm, foreign maximum is 1830 mm. (4) Belt speed Due to the limitation of the rotation speed of the roller, the speed of belt conveyors in China is 4m/s, and that of foreign machines is 5m/s or more. (5) The transport length of the working face along the trough is 3000 m in China and 7300 m in foreign countries. (6) With the continuous appearance of high-yield and high-efficiency working face from the tail of the shifting machine, it is required that the trailing end of the retractable belt conveyor be rapidly self-moved with the rapid advancement of the working face. Domestic relocation mainly depends on imports, and there are mainly two types: (a) Self-moving tail devices manufactured by the British company LONGWALL, which are moved together with the transponders. (b) Self-relocating tailstock devices produced by Germany DBT. The former has only one propulsion cylinder, while the latter has two propulsion cylinders. The self-proclaimed tail produced by LONGWALL Company is used on a conveyor with a domestic bandwidth of 1.2 m. The disadvantage is that the amount of deviation of the conveyor belt at the tail of the self-advancing machine is too small, the rectifying ability is weak, and the rigidity is poor. The effect of the self-advancing machine produced in Germany is superior to the former in the domestic use. The horizontal and vertical two directions are equipped with a misalignment cylinder and the rectification ability is strong.
Therefore, the former needs to be improved, while the latter needs to be developed. However, the requirements for the self-advancing machine tail are common, and it is necessary to meet the requirements of the non-slippery during the normal operation of the conveyor, and to meet the requirement of rapid self-movement when the conveyor is not stopped. (7) High efficient storage belt and tensioning device China adopts closed storage belt structure and winch red tightness. The tensioning trolley is easy to derail and the conveyor belt is easy to deviate. When the conveyor belt is retracted, the idler trolley is not self-moving and needs to be manually changed. Maintenance trouble. The use of advanced open storage belt devices and high-precision high-torque, large-stroke automatic tensioning equipment abroad, the roller car can automatically telescope in place with the conveyor belt. Conveyor with easy deviation, there will be no derailment. (8) Conveyor models have few varieties, single functions, limited scope of use, and can not fully exert their effectiveness, such as expanding the functions of transporting people, transporting materials, or two-way transportation, so as to use more than one machine; In addition, the geological conditions of coal mines in China are different. Very large, there are often some special requirements in the layout of the transportation system, such as bending, large inclination (>+25°) until vertical lifting, etc. Special type special belt belt conveyors should be developed. 3.3 Differences in reliability and life (1) Tensile strength of conveyor belts The maximum number of fire-retardant conveyor belts produced in China for fabrics is 2500 N/mm and 3150 N/mm in foreign countries. Steel cord core flame-retardant conveyor belt is up to 4000 N/mm and foreign is 7000 N/mm. (2) Conveyor belt joint strength The strength of the conveyor belt joints in China is 50% to 65% of the master belts, and 70% to 75% of the parent belts in foreign countries. (3) Roller life The existing idler technology in China compared with foreign countries, short life, low speed and high resistance, while the new type of oiling idler used in the United States, its running resistance is small, the bearing adopts thin oil lubrication, greatly improves the support Roll life, and can be used as a high-speed roller on the belt conveyor, a wide range of uses, significant economic benefits. China conveyor idler life is 20,000 hours, and foreign idler life is 5 to 90,000 hours. Domestic idler life is only 30% to 40% of foreign products. (4) The life of the conveyor reducer The life of the conveyor reducer in our country is 20,000 hours, and the life of the foreign reducer is 70,000 hours. (5) The belt conveyor has poor reliability when it is operated up and down. 3.4 The gap on the control system (1) The driving mode The speed control fluid coupling and the hardened gear reducer are used in China. There are various transmission modes in foreign countries, such as BOSS system and CST controllable transmission system. High control accuracy.
Monitoring equipment Foreign conveyors have adopted high-end programmable logic controllers PLC, developed advanced software Po and integrated power relay control technology and data mining, processing, storage, transmission, fault diagnosis and inquiries complete automatic monitoring system. China's conveyor only uses a mid-range programmable controller to control the start, normal operation, and shutdown of the conveyor. Although it can be used in conjunction with controllable activation (branch) devices, it can achieve controllable activation, speed synchronization, power balance, etc., but it has no automatic proximity devices, no fault diagnosis and inquiries. (3) Conveyor protection devices In addition to the installation of protection devices to prevent deviations, slippage, tearing, overfilling, and automatic sprinkler dust reduction in foreign conveyor belts, many new types of monitoring devices have been developed in recent years: transmission drums and turning rollers. And roller group temperature monitoring system; smoke alarm and automatic fire extinguishing device; fiber-woven conveyor belt longitudinal tear and joint monitoring system; explosion-proof electronic conveyor belt scale automatic metering system. These new protection systems are basically blank in our country. In China, the existing skid-proof, coal-burning, coal-mesh full-lid protection, anti-runaway, over-temperature watering, and smoke alarm devices have low reliability, sensitivity, and longevity.
Development trend of belt conveyor technology in coal mines 4.1 Equipment enlargement and transportation capacity enhancement In order to meet the needs of high production and efficient intensive production, the conveyor capacity of belt conveyors should be increased. Long distance, high belt speed, large capacity, and high power are inevitable trends for future development, and are also the development direction of high-yield and high-efficiency mine transportation technologies. In the next 10 years, the transportation volume should be increased to 3000-4000 t/h, the speed should be increased to 4-6 m/s, and the conveying length should reach 3000 m for the retractable belt conveyor. For steel cord core belt conveyors that need to be extended to more than 5000m, single-frame drive power requirements are 1000 to 1500 kW, conveyor belt tensile strength is up to 6000 N/mm (steel wire cores) and 2500 N/mm (steel cord cores) . Especially with the development of the telescoping conveyor technology for down-hole coal mining, with the emergence of high-yield and high-efficiency working face and the continuous development of coal technology, the existing scalable belt conveyors are difficult to adapt to high yields regardless of their main parameters or operating performance. With the requirements of high-efficiency working face, coal mines urgently need long-distance, large-capacity, high-power slot-retractable belt conveyors with larger main parameters, more advanced technologies, and more reliable performance to improve the design of belt conveyor technology in China. Level, to fill the gaps in the domestic, close to and catch up with the technological level of the international advanced industrial countries. It contains seven key technologies: (1) dynamic analysis and monitoring technology of belt conveyors; (2) soft start and power balance technology; (3) intermediate drive technology; (4) automatic tensioning technology; (5) new high-speed high-speed idler technology; (6) rapid Self-moving tail technology; (7) High-efficiency storage technology. Improve the performance of components and reliability The high and low equipment operating rates mainly depend on the performance and reliability of the components.
In addition to further improving and improving the performance and reliability of existing components, new technologies and components such as high-performance controlled soft-start technology, dynamic analysis and monitoring technology, high-efficiency tape storage devices, and rapid self-development have also been continuously researched and researched. Transfer tails, high-speed idlers, etc., to further enhance the performance of the belt conveyor. 4.3 to expand the function, a multi-purpose machine to expand the transport of people, transport materials or two-way transport and other functions, so that a multi-purpose machine to make it play the greatest economic benefits. Develop special types such as curved belt conveyors, large dips or vertical lifts.
The current status of belt conveyor technology The development of foreign belt conveyor technology is very fast, and its performance is mainly in two aspects: on the one hand, the function of the belt conveyor is diversified, and the application scope is expanded, such as high inclination belt conveyor and tubular belt type. Conveyors, space turning belt conveyors and other models; on the other hand, the technology and equipment of the belt conveyors have been greatly developed, especially for large belt conveyors such as long distances, large transport volumes, and high belt speeds. Being the main direction of development, its core technology is to develop and apply dynamic analysis and monitoring technology of belt conveyors to improve the running performance and reliability of belt conveyors.
At present, the belt conveyor used in coal mines has reached the main technical indicators shown in Table 1. The key technologies and equipment have the following characteristics: (1) Large-scale equipment. Its main technical parameters and equipment are being developed towards large-scale development to meet the needs of high-yield and high-efficiency intensive production with an annual output of 300 to 5 million tons. (2) Dynamic analysis technology, mechatronics, computer monitoring and other high technologies are adopted. High-power soft start and automatic tensioning technologies are used to dynamically monitor and monitor conveyors, greatly reducing the dynamic tension of the conveyor belt, and the equipment running performance is good. , high transport efficiency. (3) The use of multi-motor drive and intermediate drive and its power balance, conveyor direction change operation and other technologies have theoretically limited the running length of the conveyor, and ensure the universality, interchangeability and unit of the conveyor system equipment. Drive reliability. (4) New, high-reliability key component technology. Such as CST, including a variety of advanced high-power drive and speed control device, high-life high-speed roller, self-cleaning roller device, high-efficiency tape device, fast self-moving tail and so on.
For example, the FSW1200/(2～3)×400(600) working face conveyor belt conveyor produced by FSW in the United Kingdom adopts the liquid-viscosity differential or frequency conversion speed-regulating device and the transportation capacity reaches over 3000 t/h. In combination with a new type of transshipment machine (such as the S500E produced by U.S. Jiuyi Company), it can automatically and quickly move with the work surface, reduce manual work, and increase production efficiency. 2 Status of Domestic Belt Conveyor Technology There are many varieties and types of belt conveyors manufactured in China. During the "Eighth Five-Year Plan" period, through the implementation of the national one-stop project of "Daily Production of 10,000 Tons of Comprehensive Mining Equipment", the technical level of belt conveyors has been greatly improved, and the key to the use of high-power, long-distance belt conveyors in underground coal mines Technological research and new production Lu development have made great progress. For example, large-angle long-distance belt conveyor complete sets of equipment, high-yield and high-efficiency working surfaces along the groove retractable belt conveyors, etc. have filled the gaps in China, and theoretical research has been conducted on key technologies for reducing belt conveyors and their major components. And product development, developed a variety of soft start and brake devices and PLC as the core of the programmable electronic control device, the drive system uses speed-type fluid coupling and planetary gear reducer. At present, the main technical characteristics of coal belt conveyors in China are shown in Table 2.
The Key Technology Differences of Large Belt Conveyors (1) Dynamic Analysis and Monitoring Technology of Belt Conveyors The key technology of long-distance, high-power belt conveyors is dynamic design and monitoring. It is the core technology that restricts the development of large-scale belt conveyors. . At present, China uses rigid theory to analyze and study belt conveyors and formulate calculation methods and design specifications. In the design, a very high safety system is used for the conveyor belt (generally taking n=10 or so), which is far from the actual situation. In fact, the conveyor belt is a viscoelastic body. The dynamic response of the conveyor belt to the starting and braking force of the drive device is a very complicated process for a long-distance belt conveyor. It cannot be simply explained and calculated by rigid body mechanics. The dynamic design method and application software of the belt conveyor have been developed. Dynamic analysis and dynamic monitoring of the dynamic tension of the conveyor on a large conveyor reduce the safety system of the conveyor belt, greatly prolong the service life, and ensure the reliable operation of the conveyor. As a result, the design of large belt conveyors has reached the highest level (belt safety factor n=5-6), and the cost of the conveyor equipment, especially the cost of the conveyor belt, has been greatly reduced.
Reliable, controlled soft-start technology and power equalization technology Long-distance and large-capacity belt conveyors, due to their large power, long distances, and multi-motor drive, must use soft-start to reduce the conveyor's braking tension, especially when multi-motor drives. In order to reduce the impact on the power grid, the soft starter should have a time-different slow start; it is also necessary to control the starting acceleration of the conveyor from 0.3 to 0.1 m/s2 to solve the problem of belt speed synchronizing between the carrier belt and the drive belt and the phenomenon of the conveyor belt swell. Reduce the impact on the components. Due to manufacturing error and motor characteristic error, the power of each driving point will appear unbalanced. Once a certain motor power is too large, it will cause a burning motor accident. Therefore, the power balance among the motors should be controlled and the balance accuracy must be improved. In China, a large number of variable-speed hydrodynamic couplings have been used to achieve the soft start and power balance of the conveyor, which solves the problems of starting and power balance and synchronization of long-distance belt conveyors. However, there is a certain gap between its adjustment accuracy and reliability compared with foreign countries.
In addition, long-distance high-power belt conveyors require a tape speed in addition to a coal belt speed. Although the speed-regulating fluid couplings achieve soft start and power balance, they need to be developed for long distances. The stepless hydraulic speed regulator. When stand-alone power >500 kW, controllable CST soft start shows superiority. Since the controlled soft start is the combination of the internal gear ring of the planetary gear reducer and the wet friction clutch (ie, viscous drive). Through the proportional valve and control system to achieve soft start and power balance, the adjustment accuracy of up to 98%. However, it is expensive and urgently needs localization. 3.2 Technical performance gap The main performance and parameters of belt conveyors in China can no longer meet the needs of high-yield and high-efficiency mines, especially the key components and functions of the slot retractable belt conveyor, such as self-moving machine tails and high-efficiency storage belts. There is a big gap with foreign countries such as tensioning devices. (1) Installed power The maximum installed power of the conveyor belt conveyor in the working face of the working face is 4×250 kW, and the foreign product can reach 4×970 kW. The installed power of the domestic belt conveyor is approximately 30% to 40% of the foreign product. The installed power of fixed belt conveyors differs even more. (2) Transportation capacity The maximum capacity of belt conveyors in China is 3,000 t/h, which has reached 5,500 t/h in foreign countries. (3) Maximum belt width China's belt conveyor is 1400 mm, foreign maximum is 1830 mm. (4) Belt speed Due to the limitation of the rotation speed of the roller, the speed of belt conveyors in China is 4m/s, and that of foreign machines is 5m/s or more. (5) The transport length of the working face along the trough is 3000 m in China.
7300m abroad. (6) With the continuous appearance of high-yield and high-efficiency working face from the tail of the shifting machine, it is required that the trailing end of the retractable belt conveyor be rapidly self-moved with the rapid advancement of the working face. Domestic relocation mainly depends on imports, and there are mainly two types: (a) Self-moving tail devices manufactured by the British company LONGWALL, which are moved together with the transponders. (b) Self-relocating tailstock devices produced by Germany DBT. The former has only one propulsion cylinder, while the latter has two propulsion cylinders. The self-proclaimed tail produced by LONGWALL Company is used on a conveyor with a domestic bandwidth of 1.2 m. The disadvantage is that the amount of deviation of the conveyor belt at the tail of the self-advancing machine is too small, the rectifying ability is weak, and the rigidity is poor. The effect of the self-advancing machine produced in Germany is superior to the former in the domestic use. The horizontal and vertical two directions are equipped with a misalignment cylinder and the rectification ability is strong.
Therefore, the former needs to be improved, while the latter needs to be developed. However, the requirements for the self-advancing machine tail are common, and it is necessary to meet the requirements of the non-slippery during the normal operation of the conveyor, and to meet the requirement of rapid self-movement when the conveyor is not stopped. (7) High efficient storage belt and tensioning device China adopts closed storage belt structure and winch red tightness. The tensioning trolley is easy to derail and the conveyor belt is easy to deviate. When the conveyor belt is retracted, the idler trolley is not self-moving and needs to be manually changed. Maintenance trouble. The use of advanced open storage belt devices and high-precision high-torque, large-stroke automatic tensioning equipment abroad, the roller car can automatically telescope in place with the conveyor belt. Conveyor with easy deviation, there will be no derailment. (8) Conveyor models have few varieties, single functions, limited scope of use, and can not fully exert their effectiveness, such as expanding the functions of transporting people, transporting materials, or two-way transportation, so as to use more than one machine; In addition, the geological conditions of coal mines in China are different. Very large, there are often some special requirements in the layout of the transportation system, such as bending, large inclination (>+25°) until vertical lifting, etc. Special type special belt belt conveyors should be developed. 3.3 Differences in reliability and life (1) Tensile strength of conveyor belts The maximum number of fire-retardant conveyor belts produced in China for fabrics is 2500 N/mm and 3150 N/mm in foreign countries. Steel cord core flame-retardant conveyor belt is up to 4000 N/mm and foreign is 7000 N/mm. (2) Conveyor belt joint strength The strength of the conveyor belt joints in China is 50% to 65% of the master belts, and 70% to 75% of the parent belts in foreign countries. (3) Roller life The existing idler technology in China compared with foreign countries, short life, low speed and high resistance, while the new type of oiling idler used in the United States, its running resistance is small, the bearing adopts thin oil lubrication, greatly improves the support Roll life, and can be used as a high-speed roller on the belt conveyor, a wide range of uses, significant economic benefits. China conveyor idler life is 20,000 hours, and foreign idler life is 5 to 90,000 hours. Domestic idler life is only 30% to 40% of foreign products.
Conveyor reducer life China conveyor reducer life of 20,000 h, foreign reducer life of 70,000 h. (5) The belt conveyor has poor reliability when it is operated up and down. 3.4 The gap on the control system (1) The driving mode The speed control fluid coupling and the hardened gear reducer are used in China. There are various transmission modes in foreign countries, such as BOSS system and CST controllable transmission system. High control accuracy. (2) Monitoring Device The foreign conveyor has adopted high-end programmable logic controller PLC, developed advanced program soft-bo and integrated power supply relay control technology and complete automatic monitoring system for data mining, processing, storage, transmission, fault diagnosis and inquiry. China's conveyor only uses a mid-range programmable controller to control the start, normal operation, and shutdown of the conveyor. Although it can be used in conjunction with controllable activation (branch) devices, it can achieve controllable activation, speed synchronization, power balance, etc., but it has no automatic proximity devices, no fault diagnosis and inquiries. (3) Conveyor protection devices In addition to the installation of protection devices to prevent deviations, slippage, tearing, overfilling, and automatic sprinkler dust reduction in foreign conveyor belts, many new types of monitoring devices have been developed in recent years: transmission drums and turning rollers. And roller group temperature monitoring system; smoke alarm and automatic fire extinguishing device; fiber-woven conveyor belt longitudinal tear and joint monitoring system; explosion-proof electronic conveyor belt scale automatic metering system. These new protection systems are basically blank in our country. In China, the existing skid-proof, coal-burning, coal-mesh full-lid protection, anti-runaway, over-temperature watering, and smoke alarm devices have low reliability, sensitivity, and longevity.
Development trend of belt conveyor technology in coal mines 4.1 Equipment enlargement and transportation capacity enhancement In order to meet the needs of high production and efficient intensive production, the conveyor capacity of belt conveyors should be increased. Long distance, high belt speed, large capacity, and high power are inevitable trends for future development, and are also the development direction of high-yield and high-efficiency mine transportation technologies. In the next 10 years, the transportation volume should be increased to 3000-4000 t/h, the speed should be increased to 4-6 m/s, and the conveying length should reach 3000 m for the retractable belt conveyor. For steel cord core belt conveyors that need to be extended to more than 5000m, single-frame drive power requirements are 1000 to 1500 kW, conveyor belt tensile strength is up to 6000 N/mm (steel wire cores) and 2500 N/mm (steel cord cores) . Especially with the development of the telescoping conveyor technology for down-hole coal mining, with the emergence of high-yield and high-efficiency working face and the continuous development of coal technology, the existing scalable belt conveyors are difficult to adapt to high yields regardless of their main parameters or operating performance. With the requirements of high-efficiency working face, coal mines urgently need long-distance, large-capacity, high-power slot-retractable belt conveyors with larger main parameters, more advanced technologies, and more reliable performance to improve the design of belt conveyor technology in China. Level, to fill the gaps in the domestic, close to and catch up with the technological level of the international advanced industrial countries. It contains seven key technologies: (1) dynamic analysis and monitoring technology of belt conveyors; (2) soft start and power balance technology; (3) intermediate drive technology; (4) automatic tensioning technology; (5) new high-speed high-speed idler technology; (6) rapid Self-moving tail technology; (7) High-efficiency storage technology. Improve the performance of components and reliability The high and low equipment operating rates mainly depend on the performance and reliability of the components.
In addition to further improving and improving the performance and reliability of existing components, new technologies and components such as high-performance controlled soft-start technology, dynamic analysis and monitoring technology, high-efficiency tape storage devices, and rapid self-development have also been continuously researched and researched. Transfer tails, high-speed idlers, etc., to further enhance the performance of the belt conveyor. 4.3 to expand the function, a multi-purpose machine to expand the transport of people, transport materials or two-way transport and other functions, so that a multi-purpose machine to make it play the greatest economic benefits. Develop special belt conveyors such as curved belt conveyors, large angle or vertical lift conveyors. (2) Reliable controllable soft-start technology and power equalization technology Long-distance and large-capacity belt conveyors must be soft-started to reduce the braking tension of conveyors due to their large power, long distances, and multi-motor drive, especially when multi-motor drives. . In order to reduce the impact on the power grid, the soft starter should have a time-different slow start; it is also necessary to control the starting acceleration of the conveyor from 0.3 to 0.1 m/s2 to solve the problem of belt speed synchronizing between the carrier belt and the drive belt and the phenomenon of the conveyor belt swell. Reduce the impact on the components. Due to manufacturing error and motor characteristic error, the power of each driving point will appear unbalanced. Once a certain motor power is too large, it will cause a burning motor accident. Therefore, the power balance among the motors should be controlled and the balance accuracy must be improved. In China, a large number of variable-speed hydrodynamic couplings have been used to achieve the soft start and power balance of the conveyor, which solves the problems of starting and power balance and synchronization of long-distance belt conveyors. However, there is a certain gap between its adjustment accuracy and reliability compared with foreign countries. In addition, long-distance high-power belt conveyors require a tape speed in addition to a coal belt speed. Although the speed-regulating fluid couplings achieve soft start and power balance, they need to be developed for long distances. The stepless hydraulic speed regulator. When stand-alone power >500 kW, controllable CST soft start shows superiority. Since the controlled soft start is the combination of the internal gear ring of the planetary gear reducer and the wet friction clutch (ie, viscous drive). Through the proportional valve and control system to achieve soft start and power balance, the adjustment accuracy of up to 98%. However, it is expensive and urgently needs localization.
Technical performance gap The main performance and parameters of belt conveyors in China can no longer meet the needs of high-yield and high-efficiency mines, especially the key components and their functions such as self-aligning conveyor belts and high-efficiency storage belts. Tensioning devices have a big gap with foreign countries. (1) Installed power The maximum installed power of the conveyor belt conveyor in the working face of the working face is 4×250 kW, and the foreign product can reach 4×970 kW. The installed power of the domestic belt conveyor is approximately 30% to 40% of the foreign product. The installed power of fixed belt conveyors differs even more. (2) Transportation capacity The maximum capacity of belt conveyors in China is 3,000 t/h, which has reached 5,500 t/h in foreign countries. (3) Maximum belt width China's belt conveyor is 1400 mm, foreign maximum is 1830 mm. (4) Belt speed Due to the limitation of the rotation speed of the roller, the speed of belt conveyors in China is 4m/s, and that of foreign machines is 5m/s or more. (5) The transport length of the working face along the trough is 3000 m in China and 7300 m in foreign countries. (6) With the continuous appearance of high-yield and high-efficiency working face from the tail of the shifting machine, it is required that the trailing end of the retractable belt conveyor be rapidly self-moved with the rapid advancement of the working face. Domestic relocation mainly depends on imports, and there are mainly two types: (a) Self-moving tail devices manufactured by the British company LONGWALL, which are moved together with the transponders. (b) Self-relocating tailstock devices produced by Germany DBT. The former has only one propulsion cylinder, while the latter has two propulsion cylinders. The self-proclaimed tail produced by LONGWALL Company is used on a conveyor with a domestic bandwidth of 1.2 m. The disadvantage is that the amount of deviation of the conveyor belt at the tail of the self-advancing machine is too small, the rectifying ability is weak, and the rigidity is poor. The effect of the self-advancing machine produced in Germany is superior to the former in the domestic use. The horizontal and vertical two directions are equipped with a misalignment cylinder and the rectification ability is strong.
Therefore, the former needs to be improved, while the latter needs to be developed. However, the requirements for the self-advancing machine tail are common, and it is necessary to meet the requirements of the non-slippery during the normal operation of the conveyor, and to meet the requirement of rapid self-movement when the conveyor is not stopped. (7) High efficient storage belt and tensioning device China adopts closed storage belt structure and winch red tightness. The tensioning trolley is easy to derail and the conveyor belt is easy to deviate. When the conveyor belt is retracted, the idler trolley is not self-moving and needs to be manually changed. Maintenance trouble. The use of advanced open storage belt devices and high-precision high-torque, large-stroke automatic tensioning equipment abroad, the roller car can automatically telescope in place with the conveyor belt. Conveyor with easy deviation, there will be no derailment. (8) Conveyor models have few varieties, single functions, limited scope of use, and can not fully exert their effectiveness, such as expanding the functions of transporting people, transporting materials, or two-way transportation, so as to use more than one machine; In addition, the geological conditions of coal mines in China are different. Very large, there are often some special requirements in the layout of the transportation system, such as bending, large inclination (>+25°) until vertical lifting, etc. Special type special belt belt conveyors should be developed. 3.3 Differences in reliability and life (1) Tensile strength of conveyor belts The maximum number of fire-retardant conveyor belts produced in China for fabrics is 2500 N/mm and 3150 N/mm in foreign countries. Steel cord core flame-retardant conveyor belt is up to 4000 N/mm and foreign is 7000 N/mm. (2) Conveyor belt joint strength The strength of the conveyor belt joints in China is 50% to 65% of the master belts, and 70% to 75% of the parent belts in foreign countries. (3) Roller life The existing idler technology in China compared with foreign countries, short life, low speed and high resistance, while the new type of oiling idler used in the United States, its running resistance is small, the bearing adopts thin oil lubrication, greatly improves the support Roll life, and can be used as a high-speed roller on the belt conveyor, a wide range of uses, significant economic benefits. China conveyor idler life is 20,000 hours, and foreign idler life is 5 to 90,000 hours. Domestic idler life is only 30% to 40% of foreign products. (4) The life of the conveyor reducer The life of the conveyor reducer in our country is 20,000 hours, and the life of the foreign reducer is 70,000 hours. (5) The belt conveyor has poor reliability when it is operated up and down. 3.4 The gap on the control system (1) The driving mode The speed control fluid coupling and the hardened gear reducer are used in China. There are various transmission modes in foreign countries, such as BOSS system and CST controllable transmission system. High control accuracy.
Monitoring equipment Foreign conveyors have adopted high-end programmable logic controllers PLC, developed advanced software Po and integrated power relay control technology and data mining, processing, storage, transmission, fault diagnosis and inquiries complete automatic monitoring system. China's conveyor only uses a mid-range programmable controller to control the start, normal operation, and shutdown of the conveyor. Although it can be used in conjunction with controllable activation (branch) devices, it can achieve controllable activation, speed synchronization, power balance, etc., but it has no automatic proximity devices, no fault diagnosis and inquiries. (3) Conveyor protection devices In addition to the installation of protection devices to prevent deviations, slippage, tearing, overfilling, and automatic sprinkler dust reduction in foreign conveyor belts, many new types of monitoring devices have been developed in recent years: transmission drums and turning rollers. And roller group temperature monitoring system; smoke alarm and automatic fire extinguishing device; fiber-woven conveyor belt longitudinal tear and joint monitoring system; explosion-proof electronic conveyor belt scale automatic metering system. These new protection systems are basically blank in our country. In China, the existing skid-proof, coal-burning, coal-mesh full-lid protection, anti-runaway, over-temperature watering, and smoke alarm devices have low reliability, sensitivity, and longevity.
Development trend of belt conveyor technology in coal mines 4.1 Equipment enlargement and transportation capacity enhancement In order to meet the needs of high production and efficient intensive production, the conveyor capacity of belt conveyors should be increased. Long distance, high belt speed, large capacity, and high power are inevitable trends for future development, and are also the development direction of high-yield and high-efficiency mine transportation technologies. In the next 10 years, the transportation volume should be increased to 3000-4000 t/h, the speed should be increased to 4-6 m/s, and the conveying length should reach 3000 m for the retractable belt conveyor. For steel cord core belt conveyors that need to be extended to more than 5000m, single-frame drive power requirements are 1000 to 1500 kW, conveyor belt tensile strength is up to 6000 N/mm (steel wire cores) and 2500 N/mm (steel cord cores) . Especially with the development of the telescoping conveyor technology for down-hole coal mining, with the emergence of high-yield and high-efficiency working face and the continuous development of coal technology, the existing scalable belt conveyors are difficult to adapt to high yields regardless of their main parameters or operating performance. With the requirements of high-efficiency working face, coal mines urgently need long-distance, large-capacity, high-power slot-retractable belt conveyors with larger main parameters, more advanced technologies, and more reliable performance to improve the design of belt conveyor technology in China. Level, to fill the gaps in the domestic, close to and catch up with the technological level of the international advanced industrial countries. It contains seven key technologies: (1) dynamic analysis and monitoring technology of belt conveyors; (2) soft start and power balance technology; (3) intermediate drive technology; (4) automatic tensioning technology; (5) new high-speed high-speed idler technology; (6) rapid Self-moving tail technology; (7) High-efficiency storage technology. Improve the performance of components and reliability The high and low equipment operating rates mainly depend on the performance and reliability of the components.
In addition to further improving and improving the performance and reliability of existing components, new technologies and components such as high-performance controlled soft-start technology, dynamic analysis and monitoring technology, high-efficiency tape storage devices, and rapid self-development have also been continuously researched and researched. Transfer tails, high-speed idlers, etc., to further enhance the performance of the belt conveyor. 4.3 to expand the function, a multi-purpose machine to expand the transport of people, transport materials or two-way transport and other functions, so that a multi-purpose machine to make it play the greatest economic benefits. Develop special types such as curved belt conveyors, large dips or vertical lifts.
Developing the double guide - pillars & 4 - post guider , wide work center with connection bar structure driven by slide block on the response guide point can be suitable speedup and high precision as well as pressing of eccentric mold.
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