A scraper conveyor chain jump protection system and protection method

Abstract

The present invention discloses a chain jump protection system and method for a scraper conveyor. The system includes a sprocket vertical fine-tuning mechanism, a stress sensor, a weighing sensor, and a laser ranging sensor. The sensor is also connected to a signal conditioning box to convert various sensor signals into signals that can be recognized by an industrial computer. Then, based on the data signal input by the industrial computer and the tension and overhang threshold of the scraper conveyor chain, the host computer identifies the meshing state of the scraper chain and the sprocket to realize chain jump monitoring. The system also includes a vertical tensioning hydraulic cylinder and a constant velocity universal transmission shaft structure, which can change the amount of oil entering the hydraulic cylinder in real time to control the vertical displacement of the sprocket. The method converts the digital signal into a current signal that can be recognized by the servo valve through the signal conditioning system, realizes the coordinated control of the horizontal and vertical tensioning hydraulic cylinders, and simultaneously ensures the real-time control of the scraper chain tension and the protection of the scraper conveyor chain from jumping, thereby better ensuring the reliable and stable operation of the scraper conveyor.

Description

Technical Field

[0001] The present application relates to the field of scraper conveyor monitoring and safety assurance technology, and specifically to a scraper conveyor chain jump protection system and protection method. Background Art

[0002] As a continuous transportation equipment for mining that uses scraper chains to transport coal, scraper conveyors undertake the important tasks of transporting coal, providing a push fulcrum for hydraulic supports, and providing a walking track for coal mining machines. Their reliability directly affects the safe and efficient production of modern coal mines.

[0003] The chain is the most prone to failure in scraper conveyors, with chain failures (such as chain breakage, chain jumping, and chain drop) accounting for approximately 21.1% of all scraper conveyor failures. Once a scraper conveyor chain fails, such as chain jumping, the required repair time is long, seriously restricting the production efficiency of large-scale coal mines in my country. At present, the chain tension and hydraulic cylinder tensioning force of scraper conveyors are mainly obtained indirectly through cylinder pressure, chain overhang, and load torque at home and abroad. During the operation of the scraper conveyor, only the total tension of all the scraper conveyor chains can be obtained through cylinder pressure and power, making it difficult to effectively monitor the tension of each chain. The scraper conveyor chain transports coal through stepless closed-loop movement, and traditional wired measurement methods make it difficult to achieve real-time direct monitoring of chain tension. The invention patent, entitled "A Scraper Conveyor Chain Tension Monitoring Device and Method," with publication number CN105928653A, discloses a scraper conveyor chain tension monitoring device and method. Through wireless transmission, the device converts chain tension monitoring into real-time sprocket stress detection. Based on the collected stress data, the device determines whether the chain tension exceeds the limit, whether a chain break has occurred, and the specific chain where the break occurred. This monitoring method is flexible and reliable, but its scope of application is limited. It can only be used to detect chain breaks in scraper conveyors and cannot quickly and accurately identify chain skipping.

[0004] The above problems need to be solved urgently. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention aims to provide a chain jump protection system for a scraper conveyor to solve the problems raised in the above background technology.

[0006] According to one aspect of the present application, a scraper conveyor chain jumping protection system includes a sprocket vertical fine-tuning mechanism, a scraper conveyor middle groove, a weighing sensor, a horizontal tensioning hydraulic cylinder, a vertical tensioning hydraulic cylinder, a laser ranging sensor, and an external host computer, an industrial computer and a signal conditioning box. The right side of the sprocket vertical fine-tuning mechanism is fixedly connected to the motor of the scraper conveyor. The motor is fixed, and the sprocket of the scraper conveyor is rotatably arranged on the sprocket base through the sprocket shaft, and the sprocket base is movably arranged. The left side of the sprocket vertical fine-tuning mechanism is connected to the sprocket shaft, a stress sensor is installed on the side surface of the sprocket teeth, a laser ranging sensor is installed on one side of the sprocket vertical fine-tuning mechanism, a weighing sensor is installed in the middle groove of the scraper conveyor, the sprocket vertical fine-tuning mechanism is fixedly connected to the vertical protruding end of the vertical tensioning hydraulic cylinder, the bottom of the vertical tensioning hydraulic cylinder is connected to the ground through a slide rail, and the vertical tensioning hydraulic cylinder can be synchronized with the sprocket base. The scraper conveyor moves laterally in steps, and the horizontal tensioning hydraulic cylinder is horizontally installed on the ground. The protruding end of the horizontal tensioning hydraulic cylinder is fixedly connected to the sprocket base. The stress sensor is used to measure the stress data of the sprocket teeth under different chain tensions during the operation of the scraper conveyor. The weighing sensor is used to measure the weight of the fallen coal in each operation cycle of the scraper conveyor. The laser ranging sensor is used to measure the vertical distance from the sprocket chain meshing point to the middle groove of the scraper conveyor. The stress sensor, weighing sensor and laser ranging sensor are all electrically connected to the signal conditioning box, the signal conditioning box is electrically connected to the industrial control computer, the industrial control computer is electrically connected to the host computer, and the signal conditioning box can condition the output signals of the stress sensor, weighing sensor and laser ranging sensor into voltage signals that can be recognized by the industrial control computer. The industrial control computer transmits the data collected by the stress sensor, weighing sensor and laser ranging sensor to the host computer through the TCP / IP protocol.

[0007] Preferably, the sprocket vertical fine-tuning mechanism includes a connector, a stress sensor, a sprocket shaft and a constant velocity universal joint transmission shaft structure. The protruding end of the vertical tensioning hydraulic cylinder is fixedly connected to the constant velocity universal joint transmission shaft structure through a connector. The constant velocity universal joint transmission shaft structure is fixedly connected to the sprocket shaft, and the constant velocity universal joint transmission shaft structure is fixedly connected to the output shaft of the motor of the scraper conveyor.

[0008] Preferably, the constant velocity universal transmission shaft structure includes an intermediate shaft, a universal adjustment member, a steering shaft, a connecting plate, a connecting shaft and a gear box. The universal adjustment member is fixedly connected to the protruding end of the vertical tensioning hydraulic cylinder through the connector, the universal adjustment member is fixedly connected to the sprocket shaft through the intermediate shaft, the universal adjustment member is connected to a ball joint at one end of the steering shaft, the other end of the steering shaft is connected to the gear box through a gear meshing transmission, the gear box is fixedly connected to the connecting plate through the connecting shaft, and the connecting plate is fixedly connected to the output shaft of the motor.

[0009] Preferably, a digital signal conversion module and a control signal conversion module are provided in the industrial computer, and an analog input conditioning module and an analog output conditioning module are provided in the signal conditioning box. The analog input conditioning module transmits the output signals of the weighing sensor and the laser ranging sensor to the industrial computer through the digital signal conversion module. The industrial computer sends a control signal through the control signal conversion module and the analog output conditioning module to drive the servo valve, thereby controlling the oil output to the vertical tensioning hydraulic cylinder and the horizontal tensioning hydraulic cylinder to achieve chain tensioning force adjustment. The industrial computer can transmit the data collected by the weighing sensor and the laser ranging sensor to the host computer through the TCP / IP protocol for calculation and storage. The data collected by the stress sensor is transmitted to the host computer by the DH5960 data collector through Gigabit Ethernet.

[0010] Preferably, the laser ranging sensor is a ZYT-405 area ranging detection control sensor, and the horizontal tensioning hydraulic cylinder and the vertical tensioning hydraulic cylinder are both servo valve controlled hydraulic cylinders.

[0011] A protection method for a chain skipping protection system of a scraper conveyor, comprising the following steps:

[0012] During a single working cycle of a scraper conveyor, a correlation model between the chain tension of the scraper conveyor and the stress at the installation location of the stress sensor is established using dynamic principles. The installed stress sensor is calibrated using an external standard tension sensor, and the chain tension of the scraper conveyor is obtained from the output of the stress sensor. Using the derived dynamic model, the tension of the horizontal tensioning hydraulic cylinder is calculated based on the obtained chain tension and data measured by the load cell. This is used to control the extension and retraction of the horizontal tensioning hydraulic cylinder, thereby controlling the extension and retraction of the scraper conveyor chain and tightening the chain horizontally.

[0013] A laser distance measuring sensor is used to measure the vertical distance from the lower meshing point of the sprocket and the chain to the bottom plate of the middle trough of the scraper conveyor; by judging the fault of the scraper conveyor, it is determined whether the chain has a chain jumping fault; based on the determination of the chain jumping fault, the tensioning force of the vertical tensioning hydraulic cylinder is obtained by combining the data measured by the laser distance measuring sensor, the stress sensor and the weighing sensor, and the extension of the vertical tensioning hydraulic cylinder is controlled to control the sprocket to move upward to tighten the chain to prevent the chain jumping accident.

[0014] Preferably, the correlation model between the chain tension and the stress at the installation position of the stress sensor is achieved by installing a stress sensor on the side of the sprocket teeth to measure the tension of the scraper conveyor chain and the stress changes at the corresponding position on the side of the sprocket teeth in real time, thereby realizing the measurement of the chain tension.

[0015] Preferably, the derivation process of the kinetic model includes:

[0016] The moment balance equation of the sprocket is:

[0017]

[0018] In formula (1), θ m and θ s are the angular displacements of the drive unit and sprocket respectively; J m B is the equivalent moment of inertia of the tail sprocket drive device; m is the damping coefficient; M m and M s are the output torque of the motor and the load torque of the sprocket respectively; Z s is the transmission ratio of the gear reducer; R0 is the pitch radius of the sprocket, μ is the friction coefficient of the middle groove surface, G is the random coal falling weight, and L is the center distance of the head and tail sprockets;

[0019] Combined with the linear mass density λ of the chain and the boundary condition y′(La / 2)=0, the catenary sag equation of the tail EF section is established as:

[0020]

[0021] Where a is the length of the catenary in the horizontal direction; T F The chain tension at point F is measured by the stress sensor (1.2);

[0022] Combining equations (1) and (2) and decomposing them in the horizontal and vertical directions, the tensioning forces of the horizontal and vertical tensioning hydraulic cylinders are obtained as follows:

[0023] F h (T F , G, h E , h B )=(μGL / R0-T F / cosα) / cosβ+T F Formula (3)

[0024] F v (T F , G, h E , h B )=(μGL / R0-T F / sinα) / sinβ formula (4)

[0025] The meshing angles α and β can be obtained through chain configuration analysis:

[0026]

[0027] Where S1 and S2 are the lengths of the loaded and unloaded side chains, respectively, hB and h E are the chain verticals on the loaded and unloaded sides respectively.

[0028] Preferably, the coal falling weight G is regarded as a fixed value and is measured by the weighing sensor, and the chain tension T F The vertical distance h is measured by the stress sensor. B and h E All are measured by the laser ranging sensor.

[0029] Preferably, the specific steps of fault identification of the scraper conveyor are:

[0030] (a) First, the vertical distance from the lower meshing point of the sprocket and chain to the bottom plate of the middle trough of the scraper conveyor and the safety thresholds of the chain tension value are set as X and Y based on historical data under normal operation of the scraper conveyor;

[0031] (b) Then, determine whether the vertical distance from the lower meshing point of the scraper conveyor sprocket and chain to the bottom plate of the middle trough of the scraper conveyor and the chain tension value T are greater than the set safety thresholds X and Y respectively. The specific determination method is as follows:

[0032] (b1) If all the answers are negative, the industrial computer outputs a tension-not-exceeded signal;

[0033] (b2) if the vertical distance from the lower meshing point of the sprocket and the chain to the bottom plate of the middle trough of the scraper conveyor is lower than the safety threshold value X and the ratio of the chain tension value T to the tension threshold value Y suddenly changes, the industrial computer outputs a scraper conveyor chain break determination signal;

[0034] (b3) if the vertical distance from the lower meshing point of the sprocket and the chain to the bottom plate of the middle trough of the scraper conveyor does not exceed the safety threshold value X but the chain tension value T exceeds the set safety threshold value Y, the industrial computer outputs a scraper conveyor chain jam determination signal;

[0035] (b4) If both are yes, the industrial computer outputs a scraper conveyor chain jumping determination signal;

[0036] (c) Finally, once the host computer receives the scraper conveyor chain jumping determination signal, it controls the vertical tensioning hydraulic cylinder to move, thereby driving the sprocket to move upward to tighten the chain to prevent the chain jumping accident from occurring.

[0037] Compared with the prior art, the advantages of the present invention are:

[0038] (1) Compared with the traditional scraper conveyor chain tension single lateral adjustment mode, the present invention designs a sprocket vertical fine-tuning mechanism, and uses a constant velocity universal joint transmission shaft structure and a vertical tensioning hydraulic cylinder to realize vertical fine-tuning of the sprocket to tension the chain. In addition, since the universal adjustment device of the constant velocity universal joint transmission shaft structure is connected to the steering shaft through a precision ball joint, slight misalignment is likely to occur when the mechanical parts are matched, making it easier to achieve engagement between the sprocket and the chain.

[0039] (2) The present invention converts the monitoring of the scraper conveyor chain tension into real-time detection of the sprocket stress, judges the scraper conveyor chain failure based on the online monitoring of the chain tension and overhang, and uses the horizontal and vertical tensioning hydraulic cylinders to control its operating status.

[0040] (3) The present invention not only designs a chain jumping protection method for a scraper conveyor, but also designs a chain tensioning force adjustment method based on time-varying load during normal operation of the scraper conveyor, which is beneficial to improving the reliability and safety of the scraper conveyor operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a structural schematic diagram of a scraper conveyor chain jump protection system according to an embodiment of the present application.

[0042] Figure 2 It is a structural schematic diagram of a sprocket vertical fine-tuning mechanism of a scraper conveyor chain jump protection system according to an embodiment of the present application.

[0043] Figure 3 This is a control principle diagram of a scraper conveyor chain skipping protection system according to an embodiment of the present application.

[0044] Figure 4 This is a dynamic principle diagram of a scraper conveyor chain skipping protection system according to an embodiment of the present application.

[0045] Figure numerals: 1. Sprocket vertical fine-tuning mechanism; 1.1. Connector; 1.2. Stress sensor; 1.3. Sprocket shaft; 1.4. Intermediate shaft; 1.5. Universal adjustment member; 1.6. Steering shaft; 1.7. Connecting plate; 1.8. Connecting shaft; 1.9. Gearbox; 2. Scraper conveyor middle trough; 3. Weighing sensor; 4. Horizontal tensioning hydraulic cylinder; 5. Vertical tensioning hydraulic cylinder; 6. Laser ranging sensor; 7. Host computer; 8. Industrial computer; 9. Signal conditioning box. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0047] In order to make the content of this application easier to understand, the following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. It should be noted that the words "front", "back", "left", "right", "up" and "down" used in the following description are based on the attached drawings. Figure 2 The terms "inward" and "outward" refer to directions toward and away from, respectively, the geometric center of a particular component.

[0048] It should be noted that tension refers to the pulling or traction within an object or system, and its direction is usually along the axis or stretching direction of the object; tension refers to the force applied to the surface of an object, usually to keep the object tightly connected or fixed;

[0049] Chains are usually subject to tension when in use. When the chain bears a load or is in motion, the chain will be subjected to pulling or traction inside, which is the tension of the chain; the tension is applied by the tensioning device connected to the chain; in order to ensure that the chain connection is tight, a certain tension needs to be applied to adjust the tightness of the chain to achieve the optimal state; when the tension of the chain is too small, the chain is prone to jumping or loosening. Therefore, when using the chain, it is necessary to maintain an appropriate balance between tension and tension to ensure the normal operation of the chain.

[0050] like Figures 1 and 2As shown, a chain skipping protection system for a scraper conveyor includes a sprocket vertical fine-tuning mechanism 1, a scraper conveyor middle groove 2, a weighing sensor 3, a horizontal tensioning hydraulic cylinder 4, a vertical tensioning hydraulic cylinder 5, a laser ranging sensor 6, and an external host computer 7, an industrial computer 8 and a signal conditioning box 9. The right side of the sprocket vertical fine-tuning mechanism 1 is fixedly connected to the motor of the scraper conveyor. The motor is fixed. The sprocket of the scraper conveyor is rotated on the sprocket base through the sprocket shaft 1.3, and the sprocket base is movable. The left side of the sprocket vertical fine-tuning mechanism 1 The side is connected to the sprocket shaft 1.3, a stress sensor 1.2 is installed on the side of the sprocket teeth, a laser distance sensor 6 is installed on one side of the sprocket vertical fine-tuning mechanism 1, a weighing sensor 3 is installed in the middle groove 2 of the scraper conveyor, the sprocket vertical fine-tuning mechanism 1 is fixedly connected to the vertical extension end of the vertical tensioning hydraulic cylinder 5, the bottom of the vertical tensioning hydraulic cylinder 5 is connected to the ground through a slide rail, the vertical tensioning hydraulic cylinder 5 can move laterally synchronously with the sprocket base, the horizontal tensioning hydraulic cylinder 4 is horizontally installed on the ground, and the extension of the horizontal tensioning hydraulic cylinder 4 The end is fixedly connected to the sprocket base, the stress sensor 1.2 is used to measure the stress data of the sprocket teeth under different chain tensions during the operation of the scraper conveyor, the weighing sensor 3 is used to measure the weight of the coal dropped in each operation cycle of the scraper conveyor, and the laser distance sensor 6 is used to measure the vertical distance from the sprocket chain meshing point to the middle groove 2 of the scraper conveyor. The stress sensor 1.2, the weighing sensor 3 and the laser distance sensor 6 are all electrically connected to the signal conditioning box 9, the signal conditioning box 9 is electrically connected to the industrial computer 8, and the industrial computer 8 is electrically connected to the host computer 7. The stress sensor 1.2, the weighing sensor 3 and the laser ranging sensor 6 are connected, and the signal conditioning box 9 can condition the output signals of the stress sensor 1.2, the weighing sensor 3 and the laser ranging sensor 6 into voltage signals recognizable by the industrial computer 8. The industrial computer 8 transmits the data collected by the stress sensor 1.2, the weighing sensor 3 and the laser ranging sensor 6 to the host computer 7 through the TCP / IP protocol. Specifically, the laser ranging sensor 6 uses the ZYT-405 area distance detection control sensor, and the horizontal tensioning hydraulic cylinder 4 and the vertical tensioning hydraulic cylinder 5 both use servo valve controlled hydraulic cylinders.

[0051] In one embodiment, combined Figure 2The sprocket vertical fine-tuning mechanism 1 includes a connector, a stress sensor 1.2, a sprocket shaft 1.3 and a constant velocity universal joint structure. The protruding end of the vertical tensioning hydraulic cylinder 5 is fixedly connected to the constant velocity universal joint structure through a connector. The constant velocity universal joint structure is fixedly connected to the sprocket shaft 1.3. The constant velocity universal joint structure is fixedly connected to the output shaft of the scraper conveyor motor. Among them, the constant velocity universal joint structure includes an intermediate shaft 1.4, a universal adjustment member 1.5, a steering shaft 1.6, a connecting plate 1.7, a connecting shaft 1.8 and a gear box 1.9. The universal adjustment member 1.5 is fixedly connected to the protruding end of the vertical tensioning hydraulic cylinder 5 through a connector. The universal adjustment member 1.5 is fixedly connected to the sprocket shaft 1.3 through the intermediate shaft 1.4. The universal adjustment member 1.5 is connected to one end of the steering shaft 1.6 by a ball joint. The other end of the steering shaft 1.6 is meshed with the gear box 1.9 through a gear. The gear box 1.9 is fixedly connected to the connecting plate 1.7 through the connecting shaft 1.8. The connecting plate 1.7 is fixedly connected to the output shaft of the motor. In a specific implementation, the motor can drive the gear box 1.9 through the connecting plate 1.7 and the connecting shaft 1.8, thereby driving the steering shaft 1.6 to rotate, and then driving the sprocket shaft 1.3 to rotate through the universal adjustment member 1.5 and the intermediate shaft 1.4, thereby driving the sprocket to rotate.

[0052] In the above design, compared with the traditional scraper conveyor chain tension single lateral adjustment mode, the present invention designs a sprocket vertical fine-tuning mechanism 1, and uses a constant velocity universal joint transmission shaft structure and a vertical tensioning hydraulic cylinder 5 to realize vertical fine-tuning of the sprocket to tension the chain. Moreover, since the universal adjustment device of the constant velocity universal joint transmission shaft structure is connected to the steering shaft 1.6 through a precision ball joint, slight misalignment is likely to occur when the mechanical parts cooperate, making it easier to achieve engagement between the sprocket and the chain.

[0053] In one embodiment, referring to Figure 3, the industrial computer 8 is provided with a digital signal conversion module and a control signal conversion module, and the signal conditioning box 9 is provided with an analog input conditioning module and an analog output conditioning module. Specifically, the digital signal conversion module uses the AD board PCI-1716, and the control signal conversion module uses the DA board PCI-6208. The signal conditioning box 9 is provided with an analog input conditioning module and an analog output conditioning module. The analog input conditioning module converts the 4-20mA current signal output by the weighing sensor 3 and the laser ranging sensor 6 into a -10V-10V voltage signal that can be adopted by the AD board PCI-1716. Then the AD board PCI-1716 transmits the signal to the industrial computer 8, and then the industrial computer 8 transmits the signal to the host computer 7. The host computer 7 is based on the catenary theory and dynamic The digital signal calculated by the controller model obtained from the mechanical principle is transmitted to the industrial computer 8, and then the digital signal of the industrial computer 8 is converted into a -10V~10V voltage signal through the DA board PCI-6208, and then converted into a -40mA~40mA current signal through the analog output conditioning module to drive the servo valve. This servo valve can control the oil of the vertical tensioning hydraulic cylinder 5 and the horizontal tensioning hydraulic cylinder 4, and then control the oil output to the vertical tensioning hydraulic cylinder 5 and the horizontal tensioning hydraulic cylinder 4 to achieve the adjustment of the chain tension force. The industrial computer 8 can transmit the data collected by the weighing sensor 3 and the laser ranging sensor 6 to the host computer 7 through the TCP / IP protocol. The data collected by the stress sensor 1.2 is transmitted to the host computer 7 by the DH5960 data collector via Gigabit Ethernet.

[0054] like Figure 4 The figure shows the dynamic principle diagram of the scraper chain tensioning device of a scraper conveyor chain skipping protection system. The sprocket drives the chain through meshing force. The torque balance equation of the sprocket is:

[0055]

[0056] In formula (1), θ m and θ s are the angular displacements of the drive unit and sprocket respectively; J m B is the equivalent moment of inertia of the tail sprocket drive device; m is the damping coefficient; M m and M s are the output torque of the motor and the load torque of the sprocket respectively; Z s is the transmission ratio of the gear reducer; R0 is the pitch circle radius of the sprocket, μ is the friction coefficient of the middle groove surface, G is the random coal falling weight measured by the weighing sensor 3, and L is the center distance of the head and tail sprockets.

[0057] Assuming that the chain mass is uniform, the unloaded side chain is supported by the middle trough bottom plate, and the unloaded side chain at the tail is in a suspended state, the catenary equation is used to derive the engagement angle of the chain at point E. Figure 3 , combined with the chain's linear mass density λ and the boundary condition y'(La / 2) = 0, the catenary sag equation of the tail side EF segment can be established as:

[0058]

[0059] Where a is the length of the catenary in the horizontal direction; T F The chain tension at point F is measured by the strain sensor 1.2. The catenary chain refers to the chain connecting the scrapers in the scraper conveyor.

[0060] Combining equations (1) and (2) and decomposing them in the horizontal and vertical directions, the tensioning forces of the horizontal and vertical tensioning hydraulic cylinders are obtained as follows:

[0061] F h (T F , G, h E , h B )=(μGL / R0-T F / cosα) / cosβ+T F Formula (3)

[0062] F v (T F , G, h E , h B )=(μGL / R0-T F / sinα) / sinβ formula (4)

[0063] The meshing angles α and β can be obtained through chain configuration analysis:

[0064]

[0065] Where S1 and S2 are the lengths of the loaded and unloaded side chains, respectively, h B and h E The vertical amounts of the chain on the loaded and unloaded sides are measured by the laser distance measuring sensor 6.

[0066] The control working principle of the present invention is:

[0067] (1) Correlation between chain tension and sprocket stress

[0068] Scraper conveyors transport coal by rotating sprockets, which drive the chain. Chain tension is directly correlated with the deformation of the sprocket's side surfaces. For example, the tension between individual chains, sudden changes in tension caused by chain skipping, and chain tension imbalance can all be measured in real time through stress values ​​at corresponding sprocket locations. By correlating scraper conveyor chain tension with stress changes at key locations on the sprocket teeth, chain tension can be measured.

[0069] (2) Setting thresholds for fault detection

[0070] During the operation of the scraper conveyor, a working cycle of a certain length is taken. In each cycle, the scraper chain tension and overhang have certain rated values. If the rated values ​​are exceeded within a certain range, a chain jump failure will occur under extreme overload conditions. By setting the tension and overhang thresholds, chain jump faults can be detected.

[0071] (3) Industrial computer 8 controls the movement of the hydraulic cylinder

[0072] In each working cycle, the weight of the falling coal G can be regarded as a constant and measured by the weighing sensor 3. The chain tension T F and vertical h E 、h B The stress sensor 1.2 and the laser ranging sensor 6 can be used to measure respectively. After the output signals of various sensors are conditioned into voltage signals recognizable by the industrial control computer 8, all data are transmitted to the host computer 7 through the TCP / IP protocol. The host computer 7 converts the received data instructions into corresponding digital signals in combination with the above-mentioned horizontal and vertical tensioning hydraulic cylinder tensioning force model, and then converts them into current signals by the signal conditioning box 9 to drive the servo valve, and then controls the oil output to the horizontal and vertical tensioning hydraulic cylinder 5 to realize the control of the hydraulic cylinder movement.

[0073] A protection method for a chain skipping protection system of a scraper conveyor, comprising the following steps:

[0074] First, the tension of the scraper conveyor chain is adjusted to obtain the tensioning force of the horizontal tensioning hydraulic cylinder 4, thereby controlling the extension and contraction of the horizontal tensioning hydraulic cylinder to control the extension and contraction of the scraper conveyor chain; then, the tensioning force of the vertical tensioning hydraulic cylinder 5 is obtained by vertically fine-tuning the sprocket, thereby controlling the upward movement of the sprocket to tighten the chain to prevent chain jumping accidents. During the vertical fine-tuning of the sprocket, the scraper conveyor fault is judged to determine whether the chain has jumped.

[0075] Specifically, the specific steps of adjusting the chain tension of the scraper conveyor are as follows: First, within one working cycle of the scraper conveyor, a correlation model between the chain tension of the scraper conveyor and the stress at the installation position of the stress sensor 1.2 is established by the dynamic principle (such as Figure 4 and as shown in the above description); then, the installed stress sensor 1.2 is calibrated by an external standard tension sensor, and the chain tension of the scraper conveyor is obtained through the output of the stress sensor 1.2; finally, using the derived dynamic model (as shown in the above derived formula), the tensioning force of the horizontal tensioning hydraulic cylinder 4 is obtained according to the obtained chain tension and the data measured by the weighing sensor 3, thereby controlling the extension and retraction of the horizontal tensioning hydraulic cylinder 4 to control the extension and retraction of the scraper conveyor chain.

[0076] Specifically, the specific steps for vertical fine-tuning of the sprocket are: first, on the basis of adjusting the chain tension of the scraper conveyor, use the laser ranging sensor 6 to measure the vertical distance from the lower meshing point of the sprocket and the chain to the bottom plate of the middle groove 2 of the scraper conveyor; then, determine whether the chain has a chain jumping failure by judging the fault of the scraper conveyor; finally, on the basis of determining the chain jumping failure, combine the data measured by the laser ranging sensor 6, the stress sensor 1.2 and the weighing sensor 3 to obtain the tensioning force of the vertical tensioning hydraulic cylinder 5, and control the sprocket to move upward to tighten the chain to prevent chain jumping accidents.

[0077] Specifically, the specific steps for scraper conveyor fault diagnosis are:

[0078] (a) First, the vertical distance from the lower meshing point of the sprocket and chain to the bottom plate of the scraper conveyor's middle trough 2 and the safety thresholds of the chain tension value are set as X and Y based on historical data under normal operation of the scraper conveyor;

[0079] (b) Then, determine whether the vertical distance from the lower meshing point of the scraper conveyor sprocket and chain to the bottom plate of the scraper conveyor middle trough 2 and the chain tension value T are greater than the set safety thresholds X and Y respectively. The specific determination method is as follows:

[0080] (b1) If all the answers are negative, the industrial computer 8 outputs a tension-not-exceeding-limit signal;

[0081] (b2) If the vertical distance from the lower meshing point between the sprocket and the chain to the bottom plate of the middle trough 2 of the scraper conveyor is lower than the safety threshold value X and the ratio of the chain tension value T to the tension threshold value Y suddenly changes, the industrial computer 8 outputs a scraper conveyor chain break determination signal;

[0082] (b3) If the vertical distance from the lower meshing point of the sprocket and the chain to the bottom plate of the scraper conveyor middle trough 2 does not exceed the safety threshold value X but the chain tension value T exceeds the set safety threshold value Y, the industrial computer 8 outputs a scraper conveyor chain jam determination signal;

[0083] (b4) If both are yes, the industrial computer 8 outputs a scraper conveyor chain jumping determination signal;

[0084] (c) Finally, once the host computer 7 receives the scraper conveyor chain jumping judgment signal, it controls the vertical tensioning hydraulic cylinder 5 to operate, thereby driving the sprocket to move upward to tighten the chain to prevent the chain jumping accident from occurring.

[0085] The present invention converts the monitoring of the scraper conveyor chain tension into real-time detection of the sprocket stress, judges the scraper conveyor chain fault based on the online monitoring of the chain tension and overhang, and uses the horizontal and vertical tensioning hydraulic cylinders 5 to control its operating state.

[0086] The above embodiments are intended only to illustrate the technical solutions of the embodiments of the present application and are not intended to limit them. Although the embodiments of the present application have been described in detail with reference to the aforementioned embodiments, it should be understood by those skilled in the art that, without departing from the spirit and scope defined by the claims of the present application, they may still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents.

Claims

1. A chain skipping protection system for a scraper conveyor, comprising a sprocket vertical fine-tuning mechanism (1), a scraper conveyor middle trough (2), a weighing sensor (3), a horizontal tensioning hydraulic cylinder (4), a vertical tensioning hydraulic cylinder (5), a laser distance sensor (6), and an external host computer (7), an industrial computer (8), and a signal conditioning box (9), characterized in that: The right side of the sprocket vertical fine-tuning mechanism (1) is fixedly connected to the motor of the scraper conveyor, the motor is fixedly arranged, the sprocket of the scraper conveyor is rotatably arranged on the sprocket base via the sprocket shaft (1.3), and the sprocket base is movable. The left side of the sprocket vertical fine-tuning mechanism (1) is connected to the sprocket shaft (1.3), a stress sensor (1.2) is installed on the side surface of the sprocket teeth, and a laser distance sensor (6) is installed on one side of the sprocket vertical fine-tuning mechanism (1). A weighing sensor (3) is installed in the middle groove (2) of the scraper conveyor. The sprocket vertical fine-tuning mechanism (1) is fixedly connected to the vertical extension end of the vertical tensioning hydraulic cylinder (5). The bottom of the vertical tensioning hydraulic cylinder (5) is connected to the ground through a slide rail. The vertical tensioning hydraulic cylinder (5) can move horizontally synchronously with the sprocket base. The horizontal tensioning hydraulic cylinder (4) is horizontally installed on the ground. The extension end of the horizontal tensioning hydraulic cylinder (4) is fixedly connected to the sprocket base. The stress sensor (1.2 ) is used to measure the stress data of the sprocket teeth under different chain tensions during the operation of the scraper conveyor, the weighing sensor (3) is used to measure the weight of the coal dropped in each operation cycle of the scraper conveyor, the laser distance sensor (6) is used to measure the vertical distance from the sprocket chain meshing point to the middle groove (2) of the scraper conveyor, the stress sensor (1.2), the weighing sensor (3) and the laser distance sensor (6) are all electrically connected to the signal conditioning box (9), and the signal conditioning box (9) is connected to the industrial control The industrial computer (8) is electrically connected to the host computer (7), and the signal conditioning box (9) is capable of conditioning the output signals of the stress sensor (1.2), the weighing sensor (3) and the laser ranging sensor (6) into voltage signals identifiable by the industrial computer (8). The industrial computer (8) transmits the data collected by the stress sensor (1.2), the weighing sensor (3) and the laser ranging sensor (6) to the host computer (7) through the TCP / IP protocol. The sprocket vertical fine-tuning mechanism (1) comprises a connector (1.1), a stress sensor (1.2), a sprocket shaft (1.3) and a constant velocity universal joint transmission shaft structure; the protruding end of the vertical tensioning hydraulic cylinder (5) is fixedly connected to the constant velocity universal joint transmission shaft structure via the connector (1.1); the constant velocity universal joint transmission shaft structure is fixedly connected to the sprocket shaft (1.3); and the constant velocity universal joint transmission shaft structure is fixedly connected to the output shaft of the motor of the scraper conveyor.

2. A chain skipping protection system for a scraper conveyor according to claim 1, characterized in that: The constant velocity universal transmission shaft structure comprises an intermediate shaft (1.4), a universal adjustment member (1.5), a steering shaft (1.6), a connecting disc (1.7), a connecting shaft (1.8) and a gear box (1.9); the universal adjustment member (1.5) is fixedly connected to the protruding end of the vertical tensioning hydraulic cylinder (5) via the connector (1.1); the universal adjustment member (1.5) is fixedly connected to the sprocket shaft (1.3) via the intermediate shaft (1.4); the universal adjustment member (1.5) is connected to one end of the steering shaft (1.6) via a ball joint; the other end of the steering shaft (1.6) is meshed and transmission-connected with a gear box (1.9) via a gear; the gear box (1.9) is fixedly connected to the connecting disc (1.7) via the connecting shaft (1.8); and the connecting disc (1.7) is fixedly connected to the output shaft of the motor.

3. The chain skipping protection system for a scraper conveyor according to claim 1, characterized in that: The industrial computer (8) is provided with a digital signal conversion module and a control signal conversion module, and the signal conditioning box (9) is provided with an analog input conditioning module and an analog output conditioning module. The analog input conditioning module transmits the output signals of the weighing sensor (3) and the laser ranging sensor (6) to the industrial computer (8) through the digital signal conversion module. The industrial computer (8) sends a control signal to drive a servo valve through the control signal conversion module and the analog output conditioning module, thereby controlling the oil output to the vertical tensioning hydraulic cylinder (5) and the horizontal tensioning hydraulic cylinder (4) to achieve the adjustment of the chain tensioning force.

4. A chain-jumping protection system for a scraper conveyor according to claim 3, characterized in that: The laser distance measuring sensor (6) is a ZYT-405 type area distance measuring detection control sensor, and the horizontal tensioning hydraulic cylinder (4) and the vertical tensioning hydraulic cylinder (5) are both servo valve controlled hydraulic cylinders.

5. A protection method for a scraper conveyor chain skipping protection system according to any one of claims 1 to 4, characterized in that: The specific steps include: During a working cycle of a scraper conveyor, a correlation model between the chain tension of the scraper conveyor and the stress at the installation position of the stress sensor (1.2) is established by using the principle of dynamics; the installed stress sensor (1.2) is calibrated by using an external standard tension sensor, and the chain tension of the scraper conveyor is obtained by the output of the stress sensor (1.2); the derived dynamic model is used to obtain the tension of the horizontal tensioning hydraulic cylinder (4) based on the obtained chain tension and the data measured by the weighing sensor (3), thereby controlling the extension and contraction of the horizontal tensioning hydraulic cylinder (4) to control the extension and contraction of the scraper conveyor chain to tighten the chain in the horizontal direction; A laser distance sensor (6) is used to measure the vertical distance from the lower meshing point between the sprocket and the chain to the bottom plate of the middle trough (2) of the scraper conveyor; by judging the fault of the scraper conveyor, it is determined whether the chain has a chain jump fault; based on the determination of the chain jump fault, the tensioning force of the vertical tensioning hydraulic cylinder (5) is obtained by combining the data measured by the laser distance sensor (6), the stress sensor (1.2) and the weighing sensor (3), and the extension of the vertical tensioning hydraulic cylinder (5) is controlled to control the sprocket to move upward to tighten the chain and prevent the chain jump accident from occurring.

6. The protection method of a scraper conveyor chain skipping protection system according to claim 5, characterized in that: The correlation model between the chain tension and the stress at the installation position of the stress sensor (1.2) is to measure the tension of the scraper conveyor chain and the stress change at the corresponding position of the sprocket tooth side in real time by installing the stress sensor (1.2) arranged on the sprocket tooth side, thereby realizing the measurement of the chain tension.

7. The protection method of a scraper conveyor chain skipping protection system according to claim 5, characterized in that: The derivation process of the kinetic model includes: The moment balance equation of the sprocket is: In formula (1), θ m and θ s are the angular displacements of the drive unit and sprocket respectively; J m B is the equivalent moment of inertia of the tail sprocket drive device; m is the damping coefficient; M m and M s are the output torque of the motor and the load torque of the sprocket respectively; Z s is the transmission ratio of the gear reducer; R0 is the pitch radius of the sprocket, μ is the friction coefficient of the middle groove surface, G is the random coal falling weight, and L is the center distance of the head and tail sprockets; Combined with the linear mass density λ of the chain and the boundary condition y'(La / 2) = 0, the catenary sag equation of the tail EF section is established as: In formula (2), a is the length of the catenary in the horizontal direction; T F The chain tension at point F is measured by the stress sensor (1.2); Combining equations (1) and (2) and decomposing them in the horizontal and vertical directions, the tensioning forces of the horizontal and vertical tensioning hydraulic cylinders are obtained as follows: F h (T F ,G,h E ,h B ) = (μGL / R0 - T F / cosα) / cosβ + T F Formula (3) F v (T F ,G,h E ,h B )=(uGL / R0-T F / sina) / sinβ formula (4) The meshing angles α and β can be obtained through chain configuration analysis: In formula (5), S1 and S2 are the lengths of the loaded and unloaded side chains, respectively, and h B and h E are the chain verticals on the loaded and unloaded sides respectively.

8. The protection method of a scraper conveyor chain skipping protection system according to claim 7, characterized in that: The coal falling weight G is regarded as a fixed value and is measured by the weighing sensor (3). The chain tension T F The vertical distance h is measured by the stress sensor (1.2). B and h E All are measured by the laser distance measuring sensor (6).

9. The protection method of a scraper conveyor chain skipping protection system according to claim 5, characterized in that: The specific steps of fault diagnosis of the scraper conveyor are as follows: (a) First, according to historical data of the normal operation of the scraper conveyor, the vertical distance from the lower meshing point of the sprocket and the chain to the bottom plate of the middle trough (2) of the scraper conveyor and the safety threshold value of the chain tension value are set as X and Y; (b) Then, the vertical distance from the lower meshing point of the scraper conveyor sprocket and the chain to the bottom plate of the scraper conveyor middle trough (2) and the chain tension value T are judged to be greater than the set safety thresholds X and Y respectively. The specific judgment method is as follows: (b1) If all the answers are negative, the industrial computer (8) outputs a tension-not-exceeding-limit signal; (b2) if the vertical distance from the lower meshing point of the sprocket and the chain to the bottom plate of the middle trough (2) of the scraper conveyor is lower than the safety threshold value X and the ratio of the chain tension value T to the tension threshold value Y changes suddenly, the industrial control computer (8) outputs a scraper conveyor chain break determination signal; (b3) if the vertical distance from the lower meshing point of the sprocket and the chain to the bottom plate of the middle trough (2) of the scraper conveyor does not exceed the safety threshold value X but the chain tension value T exceeds the set safety threshold value Y, the industrial control computer (8) outputs a scraper conveyor chain jam determination signal; (b4) If both are yes, the industrial computer (8) outputs a scraper conveyor chain jumping determination signal; (c) Finally, once the host computer (7) receives the scraper conveyor chain jumping judgment signal, it controls the vertical tensioning hydraulic cylinder (5) to operate, thereby driving the sprocket to move upward to tighten the chain to prevent the chain jumping accident from occurring.

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