Comprehensive protection method for loading and unloading in the main shaft of a mine

Abstract

The invention provides a comprehensive protection method for loading, lifting and unloading of a mine main shaft. A door sensor and a metering scale are arranged in a loading mechanism; a material sensor and a timer are arranged in an unloading mechanism; an in-position sensor is arranged on an ascending container and a descending container; each induction device is connected to a PLC controller through a communication cable; 1) a PCL collects the actual loading capacity of a metering bucket; 2) a theoretical alternating current value y is calculated according to the loading capacity, when 0.5>T≥0 and T>2, y=kx+b, wherein x is the lifting weight, k is the proportional coefficient; b is the correction coefficient; when 0.5≤T≤2, y follows a corresponding table of values ​​of the measured loading capacity T and the corresponding alternating current value y; 3) when the ascending container reaches the unloading position, the material is unloaded, the hoist start signal is true, the container descends after unloading, and the container ascends after loading; 4) the actual unloading residual quantity N is calculated; 5) N is assigned to T0 to calculate the next total loading weight.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine transportation, and in particular relates to a comprehensive protection method for loading, lifting and unloading in a mine main shaft. Technical Background

[0002] The main shaft hoisting system of the mine is composed of an electric control system, a signal system, a braking system, etc., which cooperate with each other to complete the hoisting operation. A complete hoisting cycle consists of fixed-weight loading at the bottom of the shaft, hoisting of the shaft container, unloading of materials at the upper wellhead, and lowering of the shaft container to the fixed-weight loading position.

[0003] The bottom loading system is equipped with a fixed weight container, which loads coal and water into the lifting container. The lifting system adopts a double-hook lifting method. One side lifts the container with a rated amount of material to the upper wellhead unloading position, and the other side lowers the empty container to the bottom loading position. The fixed weight container ensures that the total weight of the material in the container does not exceed the rated amount. Usually, the alternating current of the hoist motor is used as the basis for judging the real-time load of the lifting container. In fact, it reflects the load difference between the lifting container and the lowering container. When the loading and unloading process of the lifting container is abnormal, the loading system based on the alternating current as the logic judgment basis cannot accurately predict the abnormality and control the operation. If it continues to perform the loading operation, it will cause overload lifting, rope breaking, motor overload, and other serious accidents.

[0004] To this end, loading, lifting and unloading must be designed as a complete process flow, breaking the relatively independent situation, eliminating the blind spots in the lifting process, and establishing a safe and reliable lifting machine loading, lifting and unloading protection device. The device needs to realize the online load of the lifting container and the online load of the lowering container, thereby realizing a series of protection and interlocking functions.

[0005] Common problems in the existing technology are: 1) After the unloading system unloads, there is often a problem of residual unloading. In the existing technology, the existence of residual can be judged by the cross current, but the specific residual value cannot be monitored; 2) In the single hook lifting operation mode of the lifting system, due to the abnormal cross current, it cannot reflect the actual lifting load. The existing technology cannot determine whether there is material residue in the lowering container, which may lead to repeated loading accidents. 3) In the existing system, when the residual volume in the lower container is less than 3 tons, when the unloading is abnormal frequently, the differential load cannot reflect the actual load of the lifting container, and the lifting system has a detection blind spot.

[0006] These situations will not only affect the continuity of production, but also bring a certain degree of hidden dangers to the safe production of mines. Therefore, solving the defects of the existing bottom loading system in the three flow processes of loading, lifting and unloading is an urgent technical problem to be solved. Summary of the invention

[0007] In order to overcome the control defects of existing equipment that loading, lifting and unloading are independently operated, the utility model provides a device for comprehensive protection of the above three parts. It can not only effectively solve the interference between the systems, but also improve the detection accuracy of the unloading residual volume in the container to less than 0.5 tons.

[0008] The technical solution adopted by the utility model to solve its technical problems is:

[0009] A comprehensive protection method for loading, lifting and unloading in a mine main shaft comprises a loading mechanism, a lifting mechanism and an unloading mechanism arranged in the mine shaft, wherein an ascending container and a descending container are installed on the lifting mechanism; the loading mechanism is arranged at the bottom of the shaft, near the loading position of the container; the unloading mechanism is arranged at the wellhead, near the unloading position of the container; a door sensor for judging whether the door is open or closed is arranged on the gate of the weighing hopper of the loading mechanism; a weighing scale is arranged at the bottom of the weighing hopper; a material sensor for detecting whether the ascending container has unloaded material is arranged in the unloading system, and the material sensor is equipped with a timer; loading / unloading position sensors are arranged on the ascending container and the descending container; the gate sensor, the weighing scale, the material sensor are equipped with a timer; the loading / unloading position sensors are arranged on the ascending container and the descending container; the door ... material sensor, the material sensor, the material sensor are equipped with a timer; the loading / unloading position sensors are arranged on the ascending container and the descending container; the door sensor, the weighing scale, the material sensor are equipped with a timer; the material sensor, the material sensor, the material sensor are equipped with a timer; the loading / unloading position sensors are arranged on the ascending container and the descending container; the door sensor, the weighing scale, the material sensor are equipped with a timer; the material sensor, the material sensor, the material sensor are equipped with a timer; the material sensor, the material sensor, the material sensor, the material sensor The sensor, timer, hoist current signal, loading / unloading position sensor are connected to the PLC controller through the communication cable, and the PLC controller is connected to the host computer through Ethernet; the host computer is a control mechanism for overall coordination of the loading mechanism, the lifting mechanism, and the unloading mechanism; the host computer is provided with a unit for calculating the load weight T according to the continuous data provided by the measuring scale; the host computer is provided with a unit for converting the theoretical alternating current value according to the load volume T; the host computer is provided with a unit for converting the residual volume T0 in the downlink container according to the comparison between the theoretical alternating current value and the actual alternating current value; the host computer is designed to control the corresponding sound and light alarm unit action according to abnormal conditions after calculating according to the PLC logic;

[0010] Specifically, the protection method follows the following rules:

[0011] 1) When the descending container falls to the loading position at the bottom of the well, the weighing bucket of the loading mechanism is weighed by a weighing scale, and the weight is T1. The weight after the weighing bucket fills the container is recorded as T2. The current loading amount of the container T = T0 + (T1-T2), where T0 is the original stock amount of the descending container before loading. The current loading amount T is collected and processed by the PLC, and then uploaded to the host computer for display;

[0012] 2) The upper computer converts the theoretical exchange current value of the two containers of the hoist at the exchange moment through the load T of the upper container. When 0.5>T≥0 and T>2, the theoretical exchange current value y follows the formula 1: y=kx+b, where y is the theoretical exchange current, x is the lifting weight, k is the proportional coefficient, and b is the correction coefficient;

[0013] When 0.5≤T ≤2, follow the weight classification and current classification comparison table, which is a corresponding table of the load T actually measured through the test and the corresponding cross current value y;

[0014] 3) When the upward container is lifted to the wellhead unloading position, the material sensor determines whether the container has been unloaded, and records the unloading duration through the timer. The duration is written into the historical data. The hoist start signal is true, the container after unloading goes down, and the container after loading goes up;

[0015] 4) Substituting the difference ∆y between the theoretical value of the cross current y and the actual cross current value y' into Formula 2, the actual unloading residual capacity N can be calculated. Formula 2: N = (∆y – b) / k, where k and b are the same as k and b in Formula 1;

[0016] 5) Assign N to T0 to calculate the next total loading weight.

[0017] The invention has the following beneficial effects:

[0018] In the above device, the host computer is equipped with a unit that calculates the load weight T based on the continuous data provided by the weighing scale; the host computer is equipped with a unit that converts the theoretical exchange current value based on the load T; the host computer is equipped with a unit that converts the residual volume T0 in the downstream container based on the comparison between the theoretical exchange current value and the actual exchange current value; the host computer is designed to control the corresponding sound and light alarm unit according to abnormal conditions after calculation based on PLC logic. This solution monitors the specific residual volume in the unloaded container, and the residual volume judgment accuracy is controlled below 0.5 tons. Compared with the original control system, the detection blind area is smaller and it can maintain normal operation even in the single hook lifting state;

[0019] This method realizes the overall control of the mine main shaft hoisting system, can monitor the specific residual volume in the unemptied container, and the residual volume judgment accuracy is controlled below 0.5 tons, with a small detection blind area; it also maintains normal operation in the single hook lifting state, realizes the overall control of the mine main shaft hoisting system, and avoids disturbances between systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the overall structure of the comprehensive protection device.

[0021] In the figure: unloading mechanism 1, lifting mechanism 2, loading mechanism 3, upward container 4, downward container 5, timer 11, material sensor 12, arrival sensor 13, elevator 21, upper guide wheel 22, lower guide wheel 23, main lifting wire rope 24, balance wire rope 25, weighing bucket 31, warehouse door sensor 32, weighing scale 33. DETAILED DESCRIPTION

[0022] The following is combined with Figure 1 The technical solution of the present invention is further described as follows:

[0023] The present invention adopts a comprehensive protection device for loading, lifting and unloading in the main shaft of a mine, including a loading mechanism 3, an unloading mechanism 1 and a lifting mechanism 2 arranged in the mine, the lifting mechanism 2 includes a hoist 21, an upper guide wheel 22, a lower guide wheel 23, a main lifting wire rope 24 and a balance wire rope 25, the hoist 21 is a container lifting drive device, adopts an independent electric control system, the main lifting wire rope 24 is equipped with an upward container 4 and a downward container 5, the loading mechanism 3 is arranged at the bottom of the shaft, located near the loading position of the container; the unloading mechanism 1 is arranged at the wellhead, located near the unloading position of the container.

[0024] The structure provided by the present invention for providing protection for the loading, lifting and unloading operation of the above-mentioned equipment is:

[0025] The door of the weighing hopper 31 of the loading mechanism 3 is provided with a door sensor 32 for judging whether the door is open or closed; a weighing scale 33 is provided at the bottom of the weighing hopper 31; the unloading system adopts a curved track automatic unloading structure, and is equipped with a material sensor 12 for detecting whether the upward container has unloaded material, and the material sensor 12 is equipped with a timer 11; the upward container 4 and the downward container 5 are provided with a loading / unloading position sensor 13. The door sensor 32, the weighing scale 33, the material sensor 12, the timer 11, the hoist current signal, and the loading / unloading position sensor 13 are connected to the PLC controller through a communication cable, and the PLC controller is connected to the host computer through Ethernet, and the host computer is a control mechanism for overall coordination of the loading mechanism 3, the lifting mechanism 2, and the unloading mechanism 1.

[0026] This protection device realizes unified monitoring of the loading, lifting and unloading parts. The operation of each part is related, and problems can be discovered and handled in time, avoiding the problem of the original system being unrelated and causing disturbances.

[0027] The host computer of the present invention is provided with a unit for calculating the load weight T according to the continuous data provided by the measuring scale 33; the host computer is provided with a unit for converting the theoretical alternating current value according to the load amount T; the host computer is provided with a unit for converting the residual amount T0 in the downstream container according to the comparison between the theoretical alternating current value and the actual alternating current value; the host computer is designed to control the action of the corresponding sound and light alarm unit according to abnormal conditions after calculation according to the PLC logic.

[0028] The in-position sensor 13 of the present invention includes a transmitter and a receiver, one of which is installed on the descending container and the ascending container, and the other is installed in the loading mechanism 3 and the unloading mechanism 1. When the descending container is lowered into position, the transmitter and the receiver are connected, and it is determined that the descending container is in position, and a signal is transmitted to the PLC.

[0029] The load weight of the protective device loader provided by the present invention, the opening and closing signal of the loading bin door, the start signal of the lifting, the stop signal, the collision signal between the upper container and the lower container, the container arrival signal, the hoist current signal, the unloading signal and the coal unloading signal are all connected to the acquisition module of the PLC. The processing program is set in the PLC to realize the collection and calculation of data, which is uploaded to the upper computer for processing. The operation of each part is related, and problems are dealt with in time when they are found, so as to avoid the problem that the original system is unrelated to each other and generates disturbances.

[0030] In the present invention, the host computer reads parameters such as unloading time, lifting weight, alternating current, operating status, lifting current, in-place status and unloading residual quantity in the PLC, and has the authority to modify the PLC parameters.

[0031] This device monitors each step and promptly detects operational abnormalities, then classifies and alarms according to the abnormal situation and shuts down the system for processing, thus avoiding operational accidents and ensuring the safety of the system and operators.

[0032] The protection method embodied by the above-mentioned mine main shaft loading and unloading comprehensive protection device is:

[0033] 1) When the descending container falls to the loading position at the bottom of the well, the weighing bucket 31 of the loading mechanism 3 is weighed by a weighing scale 33, and the weight is T1. The weight of the weighing bucket 31 after filling the container is recorded as T2. The current loading amount of the container T = T0 + (T1-T2), where T0 is the original stock amount of the descending container before loading. The current loading amount T is collected, processed and calculated by the PLC, and then uploaded to the host computer for display.

[0034] 2) When the start signal of elevator 21 is true, the container after unloading moves downward, and the container after loading moves upward.

[0035] 4) PLC calculates the theoretical current value of the upstream container and the downstream container at the time of the collision through the loading capacity T of the upstream container.

[0036] When 0.5>T≥0 and T>2, the theoretical alternating current value y follows Formula 1: y=kx+b, where y is the theoretical alternating current; x is the lifting weight, x=T; k is the proportional coefficient; and b is the current correction coefficient.

[0037] When 0.5≤T ≤2, y follows the weight classification and current classification comparison table, which is a correspondence table between the residual quantity actually measured through the test and the theoretical confrontation current value y.

[0038] 3) When the upward container is lifted to the wellhead unloading position, the material sensor 12 determines whether the container has been unloaded, and records the unloading duration through a timer, which is written into the historical data.

[0039] 4) Substituting the difference ∆y between the theoretical value of the alternating current y and the actual alternating current value y' into Formula 2, the actual unloading residual volume N of the downstream container can be calculated. Formula 2 is: N=(∆y –b) / k, where k and b are the same as k and b in Formula 1.

[0040] 5) The remaining quantity N of the downstream container is assigned to the variable T0 when the container is loaded, which is used to calculate the total weight of the next load.

[0041] The current correction coefficient and weight correction coefficient are the ratios of the signal collected by the PLC and the signal given by the external system. The adjustment of this coefficient should be based on the data displayed by the external system. The adjustment of this coefficient directly affects all the calculation data of current and weight. The current zero point cut-off parameter is the zero point error value of the current signal.

[0042] In the above method, when 0.5≤T ≤2, when conducting the comparison table data test, the standard alternating current measured when the residual amount in the downstream container is 0.5 tons, 1 ton, 1.5 tons, and 2 tons is taken respectively, and the comparison table is used as the benchmark reference for the alternating current.

[0043] To prevent the system from false alarms or no alarms when the tonnage is reduced. The present invention divides the lower limit of the cross current alarm into three levels when 0.5≤T ≤2, and the level value is set according to the measured theoretical cross current. The measured cross current value of the next level is used as the cross current alarm level value of the previous level. When the load weight is in a certain level, if its actual cross current is less than the alarm level value of the previous level, the system triggers an alarm. For example: when the load capacity is 0.5≤T ≤1.0, the actual cross current value is less than the current level value of 0.5 tons, the system calculates the coal storage and triggers an alarm. The list is as follows:

[0044] Weight classification value 2 tons 1.5 tons 1.0 ton 0.5 ton Measured current value A0 A1 A2 A3 Alarm current value A0 A1 A2 A3

[0045] When the lifting system is in normal use, the double hooks are alternately loaded and lifted, that is, when one hook is lifted, the other hook is lowered. In special cases, one hook is not loaded, that is, it is lifted when the load is 0, and this is a single hook lifting. In the traditional lifting protection system, it is impossible to protect and measure when a single hook is lifted. When the load is 0, this system meets the calculation formula in formula 1, so it can effectively protect the lifting and unloading system.

[0046] The protections mainly include: alarm for long container unloading time, alarm for short container unloading time, alarm for coal not unloaded, alarm for not fully unloaded, alarm for south hook not in place, alarm for north hook not in place. The following is a detailed description:

[0047] 1) Extraction of loading weight: When the upward container is lifted to the unloading position, the system detects the state signal of the quantitative bucket door of the loader being in place, and extracts the weighed weight T1. After loading is completed, the system detects the state signal of the door being in place, and extracts the weighed weight T2 for the second time. The difference between the two weighings is T1-T2, which is the actual loading weight T. The present invention allows the metering bucket 31 to be loaded multiple times. When multiple loadings are performed, the system automatically accumulates the value of each loading and uses the accumulated result as the actual loading weight T of the container. The present invention can record the remaining capacity of the downward container, that is, the stock capacity T0 of the container before loading. Therefore, the actual loading capacity obtained by the system should be T= T0+(T1- T2)+(T N -T N+1 ).

[0048] Container not loaded with coal prompt: When the upper container is lifted to the position, the lower container falls to the loading position, but the in-position sensor 13 has not detected the loading bin door sensor 32 bin door opening signal, indicating that the lower container is not loaded this time. When the upper container turns to descend, the unloaded coal alarm is triggered. During the alarm period, the theoretical alternating current value conversion and the residual quantity N calculation are not performed to prevent the system from triggering other false alarms.

[0049] 2) Unloading time extraction: When the signal of material sensor 12 is "true", the timing starts, and when the signal of material sensor 12 is "false", the timing ends, and the recorded duration is the unloading time. After the start signal of hoist 21 is true or the material signal disappears for 5 seconds, the timer 11 performs a reset operation. The unloading time is written into the historical record, and the system generates a report of each unloading time.

[0050] Unloading time long (short) alarm: Unloading time is linearly related to loading weight. Unloading time can be calculated by multiplying loading weight by a certain coefficient. The system can set alarm limits by modifying this coefficient. When unloading is completed, the system will compare the actual unloading time with the alarm limit. If the actual unloading time is greater than the limit, the unloading time long alarm will be output. If the actual unloading time is less than the limit, the unloading time short alarm will be output.

[0051] 3) Unloaded coal alarm: When the loading volume is greater than the setting value of the first sub-gear, the south (north) hook is in place and the corresponding material sensor 12 does not detect a material signal within 2 seconds, it is considered that the south (north) hook has not unloaded coal, triggering the unloaded coal alarm.

[0052] 4) Calculate the theoretical alternating current value y using the actual load weight according to the formula y=kx+b.

[0053] Not fully unloaded alarm: When the upstream container and the downstream container are in a confrontation state, the confrontation current y' is extracted and saved. Multiply y by a certain error coefficient and then compare it with the actual confrontation current y'. When y' is less than the theoretical current value multiplied by the error coefficient, the system will trigger a not fully unloaded alarm. The alarm distinguishes between the upstream container and the downstream container. At this time, the system will make a difference between y' and y, and use the difference ∆y to reversely calculate the weight of the remaining coal in the downstream container at the time of the handover. This remaining coal weight value is assigned to T0 and included in the actual loading amount T of the container. When the prompt that the container is not loaded with coal appears, this remaining coal weight value is assigned to T as its actual loading weight when it is ascending.

[0054] 5) Container not in place alarm: When the material sensor 12 detects the material signal and the system still does not detect the corresponding unloading in place signal within 6 seconds, the system considers that the in place signal is missing and triggers the not in place alarm.

[0055] The above monitoring logic is effective only in the coal lifting state and is set to invalid in the maintenance state.

[0056] The invention discloses a long coal unloading time, a short coal unloading time, and an alarm for coal not unloading, which are serious fault alarms, trip the safety circuit, and can be directly reset. The alarm for coal not unloading completely belongs to a minor fault alarm, which does not trip the safety circuit, and the bucket that needs to be alarmed can be reset only when it is lifted into place.

[0057] The bucket not in place alarm is a fault alarm, which does not participate in logic control and does not require reset operation. However, the technicians should handle this fault in time, because when the in place signal is lost, the system will misjudge and the system will not be able to play a protective role.

[0058] When the communication between the host computer and PLC is interrupted, the host computer system will automatically output a communication interruption voice alarm, and the red alarm light will flash on the screen until the communication is restored. At this time, all monitoring data of the host computer are data before the communication is interrupted, not real-time data. Although the logic protection is still running, the host computer cannot display the current status of the system normally and cannot issue other voice alarms. Therefore, technicians need to handle and restore system communication as soon as possible.

[0059] When the current sensor or weight sensor fails, the system will issue a corresponding voice alarm until the fault disappears. When this fault occurs, the system cannot be protected and technicians are required to restore the system in time.

[0060] The host computer monitoring system of the present invention:

[0061] The voice alarms involved in the control include: long unloading time, short unloading time, incomplete unloading, and coal not unloaded.

[0062] The voice alarms that are not involved in the control include: communication interruption, weighing scale failure, current sensor failure, and container not in place. This prompt tone is only a voice prompt, and the system affects the operation of the lifting system itself.

[0063] Voice warnings include: no coal loaded, maintenance, and coal lifting. This voice is only for prompting.

[0064] The present invention classifies different abnormalities, and the upper computer triggers corresponding alarms according to the classification. There is also a corresponding reset action design after the alarm according to the situation. Specifically, the alarms of long coal unloading time, short coal unloading time, and no coal unloading belong to serious fault alarms, which will trip the safety circuit and can be directly reset. The alarm of not completely unloading belongs to minor fault alarm, which will not trip the safety circuit, and the container that needs to be alarmed can be reset only when it is lifted into place. When the key switch is in emergency reset, all faults can be reset at any time.

[0065] The container not in place alarm is a fault alarm, which does not participate in the logic control and does not require a reset operation. However, the technicians should handle this fault in time, because when the in place signal is lost, the system will misjudge and the system will not be able to play a protective role.

[0066] When the communication between the host computer and PLC is interrupted, the host computer system will automatically output a communication interruption voice alarm, and the red alarm light will flash on the screen until the communication is restored. At this time, all monitoring data of the host computer are data before the communication is interrupted, not real-time data. Although the logic protection is still running, the host computer cannot display the current status of the system normally and cannot issue other voice alarms. Therefore, technicians need to handle and restore system communication as soon as possible.

[0067] When the current sensor or weight sensor fails, the system will issue a corresponding voice alarm until the fault disappears. When this fault occurs, the system cannot be protected and technicians are required to restore the system in time.

Claims

1. A comprehensive protection method for loading, lifting and unloading in a mine main shaft, wherein the protection device used comprises a loading mechanism, a lifting mechanism and an unloading mechanism arranged in the mine shaft, wherein an upward container and a downward container are installed on the lifting mechanism; the loading mechanism is arranged at the bottom of the shaft, near the loading position of the container; the unloading mechanism is arranged at the wellhead, near the unloading position of the container, The weighing hopper door of the loading mechanism is provided with a door sensor for judging whether the door is open or closed; a weighing scale is provided at the bottom of the weighing hopper; the unloading system is provided with a material sensor for detecting whether the upper container has unloaded material, and the material sensor is equipped with a timer; the upper container and the lower container are provided with loading / unloading position sensors; the door sensor, weighing scale, material sensor, timer, hoist current signal, loading / unloading position sensor are connected to the PLC controller through a communication cable, and the PLC controller is connected to the host computer through Ethernet, and the host computer is a control mechanism for overall coordination of the loading mechanism, the lifting mechanism, and the unloading mechanism; the host computer is provided with a unit for calculating the load weight T according to the continuous data provided by the weighing scale; the host computer is provided with a unit for converting the theoretical exchange current value according to the load amount T; the host computer is provided with a unit for converting the residual amount T0 in the lower container according to the comparison between the theoretical exchange current value and the actual exchange current value; the host computer is designed to control the corresponding sound and light alarm unit action according to abnormal conditions after calculating according to the PLC logic; Specifically, the protection method follows the following rules: 1) When the descending container falls to the loading position at the bottom of the well, the weighing bucket of the loading mechanism is weighed with a weighing scale, and the weight is T1. The weight after the weighing bucket fills the container is recorded as T2. The current loading amount of the container is T = T0 + (T1- T2), where T0 is the original stock volume of the downstream container before loading. The current loading volume T is collected and processed by the PLC and then uploaded to the host computer for display; 2) The upper computer converts the theoretical exchange current value of the two containers of the hoist at the exchange moment through the load T of the upper container. When 0.5>T≥0 and T>2, the theoretical exchange current value y follows the formula 1: y=kx+b, where y is the theoretical exchange current, x is the lifting weight, k is the proportional coefficient, and b is the correction coefficient; When 0.5≤T ≤2, follow the weight classification and current classification comparison table, which is a corresponding table of the load T actually measured through the test and the corresponding cross current value y; 3) When the upward container is lifted to the wellhead unloading position, the material sensor determines whether the container has been unloaded, and records the unloading duration through the timer. The duration is written into the historical data. The hoist start signal is true, the container after unloading goes down, and the container after loading goes up; 4) Substituting the difference ∆y between the theoretical value of the cross current y and the actual cross current value y' into Formula 2, the actual unloading residual capacity N can be calculated. Formula 2: N = (∆y – b) / k, where k and b are the same as k and b in Formula 1; 5) Assign N to T0 to calculate the next total loading weight.

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