A STEP7 and WinCC Automatic Batching Closed-Loop Control System for Calcium Carbide Furnaces

Abstract

This invention relates to the field of automated control technology for calcium carbide furnace production. Specifically, it relates to an automatic batching closed-loop control system for calcium carbide furnaces using STEP7 and WinCC. The system includes a material level detection trigger unit, a weighing bin allocation unit, a discharge and conveying control unit, a batching verification and correction unit, and a reset loop unit. In this invention, the material level detection trigger unit performs delayed confirmation filtering on the material level signal to generate a valid material shortage trigger signal. The weighing bin allocation unit obtains the cumulative number of operations, fault type, and runtime of each empty weighing bin through WinCC, calls a weighting function to calculate the priority allocation weight to determine the target weighing bin, and assigns bins according to slave station address order when weights are equal. Subsequently, the unloading and conveying, weighing deviation verification and correction, and reset loop are completed sequentially, realizing closed-loop automated control of the entire batching process for calcium carbide furnaces. This effectively improves the batching accuracy and equipment operation stability, and reduces manual labor intensity and safety risks.

Description

Technical Field

[0001] This invention relates to the field of automated control technology for calcium carbide furnace production, and more specifically, to an automatic batching closed-loop control system for calcium carbide furnaces using STEP7 and WinCC. Background Technology

[0002] Automation control in calcium carbide furnace production is a crucial technology. Currently, in calcium carbide furnace production, the feeding system largely relies on manual control, lacking precise automated management methods. In actual operation, the adjustment of raw material ratios and feed rates depends entirely on the operator's experience and judgment, lacking scientific parameter support. This leads to significant ratio errors, directly affecting the stability of the calcium carbide furnace and product quality. Key data such as silo levels and equipment operating status cannot be collected and fed back in real time, easily resulting in material shortages, shutdowns, or raw material waste during production. There is a lack of effective linkage control between various stages of the feeding process, making it difficult to detect and handle equipment malfunctions in a timely manner. Production data recording is mostly done manually, leading to omissions and errors, making data traceability difficult and failing to provide a reliable basis for fault tracing and process optimization. Furthermore, operators are exposed to high temperatures and dust for extended periods, resulting in high labor intensity and safety risks. Emergency response is also delayed when facing sudden situations such as raw material agglomeration and blockage or equipment overload. To address these technical issues, we provide a closed-loop automatic batching control system for calcium carbide furnaces based on STEP7 and WinCC. Summary of the Invention

[0003] The purpose of this invention is to provide an automatic batching closed-loop control system for calcium carbide furnaces using STEP7 and WinCC, in order to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, a closed-loop automatic batching control system for calcium carbide furnaces based on STEP7 and WinCC is provided, comprising: The material level detection trigger unit is used to perform delayed confirmation filtering on the output signals of the material level sensors in each raw material silo to generate a valid material shortage trigger signal; The weighing bin allocation unit receives the valid material shortage trigger signal and, based on the material shortage bin number carried therein, executes a bin selection strategy combining load balancing and fixed priority within the Step7 program environment to determine the target weighing bin. The bin selection strategy includes: The Step7 program obtains the cumulative number of operation cycles, the most recent equipment fault type identifier, and the cumulative runtime since the last maintenance for each empty weighing bin in the current production shift through the WinCC historical data archiving interface. The program then calls the preset priority allocation weight generation function to perform weighted normalization processing on the cumulative number of operation cycles, the most recent equipment fault type identifier, and the cumulative runtime since the last maintenance to obtain the priority allocation weight for each empty weighing bin. The program then selects the empty weighing bin with the highest priority allocation weight as the target weighing bin. When there are multiple bins with the same priority allocation weight, the Step7 program assigns bins in a fixed order from low to high according to the preset slave addresses in the hardware configuration. After determining the target weighing bin, the weighing bin allocation unit triggers the unloading and conveying control unit to perform raw material unloading and conveying. After unloading is completed, the batching verification and correction unit performs weighing deviation verification and correction. After the verification is qualified and the material is fed, the reset cycle unit performs equipment status reset and batch data recording and returns to the material level detection trigger unit to enter the next cycle.

[0005] Compared with the prior art, the beneficial effects of the present invention are as follows: Step7 program performs delayed confirmation filtering on the material level signal, effectively filtering out false material shortage signals caused by instantaneous material fluctuations or electromagnetic interference, ensuring accurate and reliable triggering of feeding requests, and preventing equipment malfunctions from the source. The weighing bin allocation unit combines WinCC historical data archiving to obtain the cumulative number of operation cycles, fault type identification, and post-maintenance runtime of empty weighing bins, and calls the priority allocation weight generation function to perform weighted normalization calculation, realizing a bin selection strategy that combines load balancing based on multi-dimensional equipment status with fixed priority, so that the operating load of each weighing bin tends to be balanced, reducing the probability of concentrated equipment wear and failure, and improving the operational stability of the batching system. The unloading conveying and batching verification and correction links use dual timing monitoring and graded deviation correction logic to ensure that the unloading process is controllable and the batching weight accuracy meets the process requirements, avoiding furnace condition fluctuations caused by deviations. At the same time, the WinCC monitoring system automatically archives data of the entire production process, supports batch traceability and report export, greatly reduces the workload of manual recording and inspection, improves operation and maintenance efficiency, and realizes closed-loop automated control from material shortage detection to feeding reset. Attached Figure Description

[0006] Figure 1 This is an overall block diagram of the present invention.

[0007] The meanings of the labels in the diagram are as follows: 1. Material level detection trigger unit; 2. Weighing bin distribution unit; 3. Unloading and conveying control unit; 4. Batching verification and correction unit; 5. Reset and cycle unit. Detailed Implementation

[0008] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0009] This invention provides an automatic batching closed-loop control system for calcium carbide furnaces using STEP7 and WinCC. Please refer to [link / reference]. Figure 1 As shown, it includes: The material level detection trigger unit is used to perform delayed confirmation filtering on the output signals of the material level sensors in each raw material silo to generate a valid material shortage trigger signal; The weighing bin allocation unit receives a valid shortage trigger signal and, based on the shortage bin number carried within it, executes a bin selection strategy combining load balancing and fixed priority within the Step7 program environment to determine the target weighing bin. The bin selection strategy includes: The Step7 program obtains the cumulative number of operation cycles, the most recent equipment fault type identifier, and the cumulative runtime since the last maintenance for each empty weighing bin in the current production shift through the WinCC historical data archiving interface. The program then calls the preset priority allocation weight generation function to perform weighted normalization on the cumulative number of operation cycles, the most recent equipment fault type identifier, and the cumulative runtime since the last maintenance to obtain the priority allocation weight for each empty weighing bin. The program selects the empty weighing bin with the highest priority allocation weight as the target weighing bin. When there are multiple equal priority allocation weights, the Step7 program assigns the bins in the hardware configuration in a fixed order from low to high according to the preset slave addresses of each empty weighing bin. After determining the target weighing bin, the weighing bin distribution unit triggers the unloading and conveying control unit to execute the unloading and conveying of raw materials. After the unloading is completed, the batching verification and correction unit performs weighing deviation verification and correction. After the verification is qualified, the reset cycle unit executes the equipment status reset and batch data recording and returns to the material level detection trigger unit to enter the next cycle.

[0010] Further explanation is needed: after power-on initialization and STEP7 program configuration loading, the system enters continuous operation mode. The material level detection trigger unit, as the starting execution module, immediately initiates the real-time monitoring process of material level signals in all raw material silos. All control logic of this module is implemented based on STEP7 PLC programming, relying on the dedicated timing and digital input resources of the PLC hardware to complete signal processing. The output signal of the material level sensor refers to the digital level signal transmitted from the material level detection device installed inside each raw material silo to the PLC input module. This signal only includes two states: high level and low level. The high level state is a system-preset signal state used to indicate that the material storage in the raw material silo meets the continuous batching requirements. The low level state is a system-preset signal state used to indicate that the material storage in the raw material silo is below the critical storage level and cannot support subsequent batching operations. The raw material silo number is a unique hardware address number assigned by the system to each independent raw material silo. This number is used to accurately distinguish storage units of different material types.

[0011] The material level detection trigger unit calls the system's built-in high-speed timer function block in the STEP7 program. The high-speed timer is a dedicated timing module within the PLC with millisecond-level timing accuracy. This accuracy matches the filtering requirements of instantaneous interference signals in industrial settings. The first time period is a fixed timing duration pre-calibrated by engineers based on the electromagnetic interference characteristics and material drop fluctuation characteristics of the calcium carbide furnace batching site. This duration is the core time threshold for determining the validity of the material shortage signal. The mathematical expression for the timing duration is: In the formula This indicates setting the total duration of the first time period. This indicates the preset timing multiplier parameter in the STEP7 program. This indicates the basic scan cycle duration of the PLC program.

[0012] The material level detection trigger unit continuously monitors the output signals of the material level sensors corresponding to all raw material silos using the cyclic scanning mode of the STEP7 program. When a level transition from a high level to a low level is detected in the output signal of any material level sensor in any raw material silo, the program immediately sends a start command to the high-speed timer corresponding to that raw material silo. After receiving the command, the high-speed timer enters continuous timing operation. At the same time, the material level detection trigger unit starts the continuous sampling mechanism. The continuous sampling mechanism refers to the processing method of sampling the low-level signal output by the current material level sensor according to the PLC program scanning cycle. The sampling time is strictly synchronized with the program scanning cycle.

[0013] During the entire first set time period of the high-speed timer's operation, the level detection trigger unit performs a point-by-point verification operation on the signal status obtained from each sampling. The verification operation determines whether the sampled signal continuously maintains a low level. If all sampling results within the first set time period are in a low level state, the level detection trigger unit determines that the material shortage state of the raw material silo is a true and valid state. This state excludes false signals caused by instantaneous electromagnetic interference or instantaneous material fluctuations. The program generates a valid material shortage trigger signal through data encapsulation instructions. The valid material shortage trigger signal is a standard digital control instruction carrying the corresponding raw material silo number. This instruction is synchronously transmitted to the weighing silo allocation unit through the PLC's internal data bus, serving as the only legal trigger condition for starting the weighing silo selection process. If, during any sampling operation within the first set time period of the high-speed timer's operation, the level sensor output signal is detected to return from a low level state to a high level state, the level detection trigger unit determines that this level jump is a field interference signal. The interference signal refers to an instantaneous false level signal caused by power grid fluctuations, equipment vibration, dust interference, etc., and the program immediately executes... The high-speed timer reset operation clears the current timing value and stops timing, while also clearing all temporary signal status data within the current monitoring cycle. The program does not generate any trigger signal, and the high-speed timer returns to its initial standby state. The material level detection trigger unit continues to perform cyclic monitoring of the output signals from the material level sensors in all raw material bins. All processing logic of the material level detection trigger unit is implemented through function blocks and ladder diagrams in the STEP7 program. Signal sampling and timing operations are entirely executed in real time by the PLC hardware without any additional software delay. The generation of a valid material shortage trigger signal follows the rule of continuous validity of the level. This unit completely eliminates false material shortage signals through delay confirmation filtering, providing a stable and reliable trigger command for the subsequent bin selection operation of the weighing bin allocation unit. This ensures the accuracy and stability of the entire automatic batching closed-loop control system for the calcium carbide furnace during startup. After receiving a valid material shortage trigger signal, the weighing bin allocation unit will immediately start a bin selection strategy combining load balancing and fixed priority based on the material shortage bin number carried by the signal.

[0014] Upon receiving a valid material shortage trigger signal, the weighing bin distribution unit immediately initiates the formula matching and equipment status data acquisition process based on the collaborative communication mechanism between the STEP7 program and the WinCC system. This process provides core foundational data for subsequent intelligent bin selection calculations and is a crucial preliminary step for achieving balanced operation of the batching equipment. The STEP7 program calls the WinCC archived data query function block integrated into the system. The WinCC archived data query function block is a standard communication function block in the STEP7 programming environment used to read data stored in the WinCC database. This function block enables real-time data exchange between the PLC program and the host computer monitoring system. According to the interaction, the program uses the shortage bin number carried by the valid shortage trigger signal as the search index to match the system's preset calcium carbide furnace production formula. The production formula is a set of rules for the use of raw materials and weighing bins that are pre-fixed in the system's storage area. The program determines the range of empty weighing bins that can be called in this batching operation through formula matching. An empty weighing bin refers to a standby weighing device that has completed the unloading process of the previous batch and has no material residue inside. After the STEP7 program locks the range of empty weighing bins, it sends a targeted data request command to the WinCC system through the industrial Ethernet communication protocol. The data request command includes the empty weighing bin identifier and the type of status parameter of the device to be read. The cumulative number of operation cycles is a quantitative parameter used to characterize the workload of the weighing silo. This parameter is defined as the total number of times a single empty weighing silo completes the entire batching process (feeding, weighing, unloading) from the start time of the current production shift to the time of data request. The current production shift is a continuous production time unit set by the system. The reset cycle unit is a functional unit that performs data clearing and recording after completing a single batch of batching. Each time the reset cycle unit completes a batch data recording operation, the STEP7 program performs an accumulation calculation on the corresponding weighing silo's operation cycle count. The mathematical expression for the accumulation calculation is: In the formula Indicates the first The cumulative number of operation cycles in the weighing bin after each accumulation. This represents the historical cumulative number of job cycles before accumulation. The program will upload and archive the updated cumulative number of job cycles to the WinCC database in real time. The WinCC database is a dedicated structured storage unit used by the WinCC system to store production data and equipment parameters.

[0015] The most recent equipment fault type identifier is a parameter used to characterize the health status of the weighing silo auxiliary equipment. This parameter is directly generated by the WinCC system. The weighing silo auxiliary equipment includes actuators such as conveyor motors, feeding mechanisms, and unloading valves. The WinCC system configures an independent alarm monitoring channel for each auxiliary equipment. When the equipment generates an alarm, the system automatically matches a predefined type code. The predefined type code is a unique numerical code assigned by the system to different faults such as motor overload, valve jamming, and sensor failure. This code is used to distinguish the fault type. The WinCC system continuously stores the predefined type code corresponding to the most recent alarm of each weighing silo. The STEP7 program can directly read this parameter through a data request. The cumulative runtime since the last maintenance is a quantitative parameter used to characterize the wear and tear of the weighing bin and associated conveying equipment. Planned maintenance refers to periodic inspections performed according to equipment procedures. "Confirmed normal operation" means the equipment passes functional verification and is put into operation after maintenance. The engagement state of the drive motor's main contactor is the electrical basis for determining motor operation; the main contactor engagement corresponds to the motor's running state, and the main contactor disengagement corresponds to the motor's stopped state. The STEP7 program calls the internal timing function block to collect motor operation feedback signals, performing timing accumulation only when the main contactor is engaged. The mathematical expression for the cumulative runtime since the last maintenance is: In the formula Indicates the first Cumulative runtime after the latest refresh This indicates the cumulative running time before the update. This indicates the basic scan cycle duration of the STEP7 program, which archives the timing data to the WinCC database in real time. After receiving a data request from the STEP7 program, the WinCC system retrieves parameters from the database, including the cumulative number of operation cycles, the most recent equipment fault type identifier, and the cumulative runtime since the last maintenance, corresponding to all empty weighing bins. All parameters are then transmitted back to the weighing bin allocation unit via the communication link. After collecting the three core parameters, the weighing bin allocation unit initiates a weighted scoring bin selection calculation process based on multi-dimensional equipment status data.

[0016] After receiving all the core status parameters of the empty weighing bins, the weighing bin allocation unit immediately initiates the calculation process of the priority allocation weight generation function. This function is the core algorithm for realizing multi-dimensional equipment status quantification and scoring. All calculation logic is solidified in the function blocks of the STEP7 program. The data source for the calculation is the real-time equipment parameters returned by the WinCC system, and the calculation benchmark is the fixed configuration parameters predefined within the program. The STEP7 program permanently stores the weight configuration table in a dedicated global data block. The global data block is an independent storage unit in the STEP7 system used to store non-volatile configuration parameters. The weight configuration table is a weight definition table customized for the equipment status evaluation parameters. This table is the cumulative number of operation cycles most recently... The equipment fault type identifier, cumulative runtime since the last maintenance, and three other core parameters each define a unique corresponding preset weight coefficient. The preset weight coefficient is a dimensionless real number representing the priority of a single parameter's influence on the weighing bin selection decision. The coefficient values ​​are pre-calibrated based on the equipment balance requirements of the calcium carbide furnace batching process. After the priority allocation weight generation function starts its calculation, it first reads the cumulative number of operation cycles corresponding to a single empty weighing bin from the original dataset returned by WinCC. It then performs a multiplication operation with the preset weight coefficient matched in the weight configuration table. The result is defined as the first sub-weight value. The first sub-weight value is used to quantify the impact of equipment operating load on allocation priority. The mathematical expression for the first sub-weight value is: In the formula Indicates the first The first sub-weight corresponding to each empty weighing bin. The hardware number indicating the empty weighing chamber. Indicates the first The cumulative number of operation cycles for each empty weighing bin. This represents the preset weight coefficients defined in the weight configuration table for the cumulative number of job cycles.

[0017] After the function completes the calculation of the first sub-weight, it continues to read the second sub-weight. The function identifies the most recent equipment failure type for each empty weighing bin and simultaneously calls the fault level mapping table pre-stored in the STEP7 program data block. This table represents the correspondence between predefined type codes and standardized numerical values. The function uses an index lookup operation to convert the failure type identifier into a dimensionless failure impact coefficient. This coefficient is a standardized value characterizing the degree of interference the failure causes to the batching operation. The function then multiplies the failure impact coefficient with the corresponding preset weight coefficient in the weight configuration table. The result is defined as the second sub-weight, which quantifies the impact of equipment failure status on priority allocation. The mathematical expression for the second sub-weight is as follows: In the formula Indicates the first The second sub-weight corresponding to each empty weighing bin. Indicates the first The failure impact coefficient corresponding to an empty weighing bin. This indicates the preset weight coefficients defined in the weight configuration table for the most recent device fault type identifier. The function continues reading the... The function calculates the cumulative runtime of each empty weighing bin since the last maintenance, and simultaneously calls the system's preset baseline runtime. The baseline runtime is a standard continuous runtime threshold defined according to the equipment operation and maintenance procedures. The function divides the cumulative runtime by the baseline runtime to obtain the runtime ratio, which is a standardized ratio representing the degree of equipment wear and tear. The function then multiplies the runtime ratio by the corresponding preset weight coefficient in the weight configuration table. The result is defined as the third sub-weight, which quantifies the impact of equipment wear and tear on priority allocation. The mathematical expression for the third sub-weight is as follows: In the formula Indicates the first The third sub-weight corresponding to each empty weighing bin. Indicates the first The cumulative runtime of each empty weighing bin since the last maintenance. This indicates the system's preset baseline running time. This indicates the preset weight coefficients defined in the weight configuration table based on the cumulative runtime since the last maintenance.

[0018] After the weight generation function performs independent operations on the three types of sub-weights, it performs a numerical summation operation, accumulating the first, second, and third sub-weights to obtain the result. The initial priority allocation weight for each empty weighing bin is a unique quantitative score representing the wear degree under the comprehensive equipment load, fault condition, and overall condition. The mathematical expression for the initial priority allocation weight is: In the formula Indicates the first The initial priority allocation weight of each empty weighing bin is determined. Following the above calculation logic, the weighing bin allocation unit calculates the initial priority allocation weight for all empty weighing bins. Then, it performs an ascending sorting operation on all the initial priority allocation weights, locking the empty weighing bin with the smallest weight as the optimal execution device for this batching operation. After completing the bin selection operation, it immediately sends a target weighing bin locking command and a quantitative batching start command to the quantitative feeding control unit.

[0019] After completing the initial priority allocation weight calculation for all empty weighing bins, the STEP7 program of the weighing bin allocation unit immediately calls the built-in dynamic adjustment module to initiate a dynamic weight correction process based on production progress. This process integrates real-time production status into the bin selection decision, enabling the weighing bin allocation strategy to adapt to different production cycle requirements. The dynamic adjustment module is a dedicated calculation function block embedded within the STEP7 program. This module maintains real-time data interaction with the WinCC monitoring system via industrial Ethernet and can dynamically adjust the priority allocation weight according to the production progress, balancing the needs of equipment utilization and production efficiency. The dynamic adjustment module first initiates a data read command through the WinCC archived data query interface to retrieve the core output data of the current production shift from the WinCC real-time database. The current production shift refers to the continuous batching production time unit set by the system. The planned total output refers to the total output index of the calcium carbide furnace batching for this shift that the production scheduler has pre-entered into the WinCC system. This index is a fixed value and is stored in the WinCC recipe variable area. The actual cumulative output refers to the total output of qualified batches that the system has completed from the start time of the current shift to the data read time. This data is accumulated in real time by the reset cycle unit after each feeding operation is completed and synchronously archived to the WinCC database.

[0020] The dynamic adjustment module performs a production completion progress ratio calculation based on the above two sets of production data. The production completion progress ratio refers to the ratio of actual output to planned output, used to characterize the current production pace. The mathematical expression for the calculation is: In the formula Indicates the percentage of production completion. This represents the actual cumulative output up to the current moment. This indicates the planned total output for the current production shift.

[0021] After calculating the progress ratio, the dynamic adjustment module calls the pre-stored weight correction coefficient table in the STEP7 program data block. This table is a pre-calibrated two-dimensional parameter mapping table that divides the production completion progress ratio into multiple continuous intervals. Each interval corresponds to a unique dynamic adjustment factor. The dynamic adjustment factor is a dimensionless real number used to scale the initial priority allocation weights, and its value adapts to different operating conditions such as expedited production, regular production, and slow production as the production progress changes. The dynamic adjustment module performs an interval matching query between the calculated production completion progress ratio and the weight correction coefficient table to lock the dynamic adjustment factor value corresponding to the current progress ratio. The module then performs a multiplication operation between the initial priority allocation weight of each empty weighing bin and the corresponding dynamic adjustment factor to obtain the final priority allocation weight factor that incorporates production progress factors. The final priority allocation weight is the unique bin selection evaluation index that comprehensively considers equipment status and production rhythm. The mathematical expression for the calculation is: In the formula Indicates the first The final priority allocation weight for each empty weighing bin This represents the initial priority allocation weight for the i-th empty weighing bin. This indicates the dynamic adjustment factor obtained from the query. After the STEP7 program completes the calculation of the final priority allocation weight for all empty weighing bins, it sorts all the final weights in descending order and selects the empty weighing bin with the highest value as the candidate target weighing bin. When two or more empty weighing bins have the same final priority allocation weight, the STEP7 program will automatically activate the standby selection routine and execute the fixed sorting assignment logic based on the hardware slave address.

[0022] After the STEP7 program completes the calculation and ranking comparison of the final priority allocation weights for all empty weighing bins, if it determines that two or more empty weighing bins simultaneously possess the highest final priority allocation weight, the program will immediately exit the regular bin selection branch and activate the built-in backup selection routine. The backup selection routine is a deterministic fallback logic preset in the STEP7 program to resolve conflicts in weight equivalence. It can quickly complete the selection of the target weighing bin without manual intervention, ensuring the continuous execution of the batching process. After the standby selection routine starts, the program calls the hardware configuration access function block integrated into the STEP7 system to read the hardware configuration information in the PLC system storage area. This hardware configuration information is distributed device configuration data completed by the STEP7 programming software before the system is powered on. This data completely records fixed parameters such as the slave address, communication port, and device mapping relationship corresponding to all weighing bins. The slave address is a unique communication number assigned by the PLC to the distributed I / O module associated with each weighing bin. The address value is an integer and is fixed during the hardware configuration stage, with no duplication or change. The standby selection routine extracts the slave addresses corresponding to all empty weighing bins with equal highest priority allocation weights and performs ascending sorting on the extracted slave address values. Ascending sorting refers to sorting the slave addresses... The weighing bins are arranged in ascending order of numerical value. After sorting, the program constructs a temporary assignment queue in the internal temporary storage area. The temporary assignment queue is an ordered list of candidate weighing bins generated by sorting the slave addresses. The order of elements in the queue strictly corresponds to the numerical value of the slave address. The STEP7 program starts from the first element of the temporary assignment queue, that is, the empty weighing bin with the smallest slave address value, and performs the final check of equipment status and ready signals in sequence. The equipment status check includes three core judgment conditions: the fully closed feedback signal of the weighing bin unloading door, the stable and valid signal of the weighing sensor, and the fault-free alarm signal of the drive motor. The ready signal refers to the standard permission signal that the weighing bin has completed the reset of the previous cycle and is ready to receive the batching task. All signals are collected in real time through the PLC digital input channel. The program performs a full check on the first candidate weighing bin. If all check items meet the preset qualification conditions, the program immediately marks the weighing bin as the target weighing bin for this batching operation. If the first candidate weighing bin fails the check, the program selects the next candidate weighing bin in the order of the temporary assignment queue and repeats the check process until the first empty weighing bin that passes all check items is selected and finally determined as the target weighing bin. After the target weighing bin is finally locked, the weighing bin allocation unit sends the target bin locking command and batching execution command to the unloading and conveying control unit through the PLC internal data bus. After receiving the command, the unloading and conveying control unit immediately starts the raw material unloading and conveying mechanism to directionally convey the material in the material shortage bin to the target weighing bin.

[0023] After the unloading and conveying control unit completes the conveying of raw materials from the raw material silo to the target weighing silo, it immediately controls the unloading gate of the weighing silo to close. The feedback signal that the unloading gate is closed is transmitted to the STEP7 program through the digital input channel. After receiving the signal, the batching verification and correction unit starts the entire process of weighing verification and deviation correction. This unit is the core execution module that ensures that the batching accuracy of the calcium carbide furnace meets the production process requirements. All control logic is implemented based on the analog quantity acquisition and logic judgment function block of the STEP7 program. The batching verification and correction unit acquires the continuous weight signal output by the weighing sensor on the target weighing silo through the analog quantity reading function block built into the STEP7 program. The program performs moving average filtering on the weight signal acquired in multiple cycles to filter out the instantaneous numerical fluctuations caused by the vibration of the equipment and the impact of the material. The stable value obtained after filtering is the real-time stable weight value. The real-time stable weight value is the quantified data that represents the actual total weight of the material in the target weighing silo. The STEP7 program reads the formula parameters corresponding to the current batch of ingredients through the WinCC communication interface. These formula parameters are stored in the WinCC system's formula variable area. These parameters include the target weight values ​​of the raw materials for the current batch. The target weight value is a standard ingredient weight value preset in the production process. The program calculates the difference between the real-time stable weight value and the target weight value and takes the absolute value to obtain the absolute deviation value. The mathematical expression for the absolute deviation value is as follows: In the formula This indicates the absolute deviation value of the current batch of ingredients. This indicates the real-time stable weight value collected by the load cell. This indicates the target weight value set in the WinCC recipe.

[0024] The STEP7 program calls the pre-stored deviation threshold parameters in the data block. The first allowable deviation is the upper limit of qualified batching deviation that meets the requirements of the calcium carbide furnace production process. The second allowable deviation is the upper limit of correctable deviation that is greater than the first allowable deviation. Both types of thresholds are fixed values ​​calibrated according to the characteristics of raw materials and the requirements of batching accuracy. The program performs a three-level logical judgment on the absolute deviation value and two types of deviation thresholds. The first level judgment is when the absolute deviation value is less than or equal to the first allowable deviation. At this point, the program determines that the batching and weighing verification is qualified and directly sends a feeding permission signal to the reset loop unit via the PLC's internal data bus. Upon receiving the signal, the reset loop unit prepares to execute subsequent feeding and reset operations. The second level judgment is when the absolute deviation value is greater than the first allowable deviation and less than or equal to the second allowable deviation. At this point, the program determines that a micro-correction operation is required for this batching. The program further calculates the sign of the original difference between the real-time stable weight value and the target weight value. If the original difference is negative (i.e., the real-time stable weight value is less than the target weight value), the STEP7 program outputs a jog control command to drive the fine feeding mechanism to perform a micro-feeding action. If the original difference is positive (i.e., the real-time stable weight value is greater than the target weight value), the STEP7 program outputs a jog control command to drive the fine discharging mechanism to perform a micro-discharging action. Jogging refers to the short-term start and stop of the actuator to convey or discharge a small amount of material, enabling precise fine-tuning of the weight. After each jog operation, the program waits for the weighing result. Once the value stabilizes and the real-time stable weight value is re-acquired, the absolute deviation value is recalculated, and the threshold judgment process is repeated until the corrected absolute deviation value falls within the first allowable deviation range. Then, the program sends a feeding permission signal to the reset loop unit. The third-level judgment is that the absolute deviation value is greater than the second allowable deviation. At this time, the program determines that there is an out-of-tolerance fault in this batching. The STEP7 program immediately triggers the hardware alarm output command, drives the on-site audible and visual alarm device to issue an alarm, and pushes the batching out-of-tolerance fault pop-up window to the monitoring system through the WinCC communication interface. The program locks all unloading, replenishing, and discharging related actuators, prohibits any equipment from operating, and does not send a feeding permission signal to the reset loop unit throughout the process, waiting for the on-site operator to complete the fault investigation and manual system reset. When the batching verification and correction unit completes the qualified judgment or deviation correction and successfully sends the feeding permission signal, the discharge valve of the target weighing bin receives the execution command and opens. The qualified proportioned raw materials in the weighing bin are put into the calcium carbide furnace to complete the feeding operation. After the feeding is completed, the reset loop unit immediately starts the closed-loop finishing process of equipment status reset and batch production data recording.

[0025] After the batching verification and correction unit completes the deviation sign determination, it initiates corresponding precise correction control processes for negative and positive deviations respectively. Negative deviations correspond to replenishment conditions where the real-time stable weight value is less than the target weight value, while positive deviations correspond to discharge conditions where the real-time stable weight value is greater than the target weight value. Both types of correction processes achieve time-series precise control based on raw material physical parameters and equipment performance parameters. The entire process is executed in a closed loop by the STEP7 program. When the program determines that a negative deviation requires a replenishment operation, it calls the pre-stored raw material physical parameters and equipment performance parameters in the data block. The preset bulk density is the raw material mass per unit volume calibrated by the raw material's physical characteristics. This value is a fixed constant and adapts to various raw material types used in calcium carbide furnace batching. The preset volumetric conveying efficiency of the fine feeding mechanism is the raw material volume that the fine feeding mechanism can convey per unit operating time. This value is a fixed performance parameter calibrated at the equipment factory. Based on the current absolute deviation value, preset bulk density, and preset volumetric conveying efficiency, the STEP7 program calculates the estimated replenishment operating time. The mathematical expression for the estimated replenishment operating time is: In the formula This indicates the estimated feeding operation time of the precision feeding mechanism. This represents the current uncorrected absolute deviation value. This indicates the preset bulk density of the raw material. This indicates the preset volumetric conveying efficiency of the precision feeding mechanism. The program sends operating instructions to the precision feeding mechanism through the digital output channel, controlling it to run continuously for the estimated replenishment time before automatically stopping. After stopping, the program initiates a weighing stabilization waiting mechanism. This mechanism continuously samples the weight signal to determine the range of numerical fluctuation. When the fluctuation range is below a set threshold, the weight is considered to have reached a stable state. The program reads the new real-time stable weight value and recalculates the absolute deviation value. The program compares the newly calculated absolute deviation value with the first allowable deviation. If it does not fall within the acceptable range, the replenishment time calculation and mechanism operation control process are repeated based on the new absolute deviation value. Simultaneously, the program internally sets a preset value for the number of correction repetitions. This preset value is a fixed safety threshold to prevent infinite loops. The number of repetitions in the entire replenishment correction process does not exceed this preset value. When the program determines that the deviation is positive, it needs to perform a discharge operation. During material handling, the jogging discharge process of the fine discharge mechanism and the replenishment process have the same calculation logic. Only the controlled object is replaced by the fine discharge mechanism. The program calls the preset volumetric conveying efficiency parameter corresponding to the fine discharge mechanism, calculates the estimated discharge running time, and controls the mechanism to perform jogging discharge actions. After each discharge, the program waits for the weight to stabilize and re-verifies the deviation. The repeated correction rules are consistent with the replenishment process. If the number of repeated corrections for replenishment or discharge reaches the preset value and the absolute deviation value still does not fall within the first allowable deviation range, the STEP7 program determines that the automatic correction has failed, immediately triggers a fault alarm signal, and locks all actuators. If the correction process makes the absolute deviation value meet the qualification requirements within the preset number of times, the batching verification correction unit immediately sends a feeding permission signal to the reset cycle unit. After receiving the signal, the reset cycle unit starts the feeding execution of the target weighing bin and the equipment reset operation.

[0026] After the batching calibration and correction unit sends the feeding permission signal, the discharge valve of the target weighing hopper receives the execution command and opens. All qualified raw materials in the hopper are fed into the calcium carbide furnace. The digital feedback signal of the discharge valve closing is transmitted to the STEP7 program. The reset cycle unit immediately starts the full-process reset operation of this batching cycle. This unit is the core closing module to ensure the continuous closed-loop operation of the automatic batching system of the calcium carbide furnace. All reset logic is implemented by relying on the reset operation command, timer reset function block and data block clearing command of the STEP7 program, without additional calculation delay. The reset cycle unit is implemented through STE The P7 program executes a first-type reset operation, clearing all intermediate state flags related to the target weighing bin in this batching cycle. These intermediate state flags are Boolean variables used in the program to mark the execution status of each stage of the batching process, including the weighing bin lock flag, unloading completion flag, weighing stability flag, deviation correction completion flag, and feeding ready flag. These variables are only used for logical jumps within a single loop and must be cleared after the loop ends to avoid interfering with the next round of the process. The program uses a reset instruction to forcibly set the binary values ​​of all relevant flags to an invalid state. The logical expression for flag reset is as follows: In the formula This indicates any intermediate state flag corresponding to this batching cycle; 0 represents no valid state after the flag is reset.

[0027] The reset loop unit synchronously executes the second type of reset operation, resetting the high-speed timer and trigger latch related to the current cycle in the material level detection trigger unit. The high-speed timer is a millisecond-level timing module within the material level detection trigger unit used for delay confirmation of the material shortage signal. The trigger latch is a temporary storage unit used to lock a valid material shortage trigger signal. The program calls the system's built-in timer reset function block, clearing the current timing value and timing enable bit of the high-speed timer to zero, simultaneously releasing the signal lock state of the trigger latch, and clearing the trigger record for this material shortage. The mathematical expression for high-speed timer reset is: , In the formula This indicates the current cumulative count of the high-speed timer. This indicates the enable bit for the high-speed timer. The reset loop unit continues to execute the third type of reset operation, clearing the intermediate variable data block generated in the weighing bin allocation unit for calculating the priority allocation weights for this cycle. The intermediate variable data block is a dedicated storage area in the STEP7 program that stores temporary data for weight calculations. The stored content includes temporary calculation data such as the cumulative number of operation cycles, fault impact coefficient, running time ratio, three types of sub-weights, preliminary priority allocation weights, dynamic adjustment factors, and final priority allocation weights. The program uses a batch clearing instruction for data blocks to set all byte, word, and double-word type temporary variable values ​​within the data block to 0, releasing the calculation storage resources. The logical expression for clearing the data block is: In the formula This indicates the data block number of the intermediate variable used in the priority allocation weight calculation. This represents any temporary operation variable within the data block. After resetting all equipment status and program data, the reset loop unit packages and writes key batch data such as raw material type, weighing bin number, actual weighing value, and batching time of this batching cycle into the WinCC database through the WinCC archiving interface, completing the permanent archiving of production data. Subsequently, the reset loop unit sends a cycle reset completion confirmation signal to the material level detection trigger unit. Upon receiving the signal, the material level detection trigger unit immediately resumes uninterrupted monitoring of the output signals of all raw material bin material level sensors, and the system officially enters the next round of automatic batching closed-loop cycle.

[0028] After the reset loop unit completes all hardware and software reset operations, including clearing the equipment status flag, resetting the high-speed timer, and clearing the intermediate variable data block, it simultaneously starts the batch data archiving and loop restart connection process. This process achieves seamless integration between permanent retention of production data and continuous closed-loop operation of the system. All operations rely on the communication function block of the STEP7 program and the WinCC database storage rules for execution. The reset loop unit performs unified packaging processing on the key data of this batching cycle through the STEP7 program. The key data includes core production traceability parameters such as raw material warehouse number, target weighing warehouse slave address, formula target weight, actual stable weighing value, deviation correction times, total batching time, and feeding completion timestamp. The program encapsulates the above discrete parameters into continuously transmitted data frames according to a preset fixed data structure, completing the standardized packaging of key data. The WinCC archiving interface is a dedicated data communication channel between the STEP7 system and the WinCC monitoring system. Based on the industrial Ethernet protocol, it enables real-time interaction between the PLC and the host computer database. The archived variable is a pre-configured dedicated storage variable for batch data in the WinCC database. This variable has timestamp and batch index functions. The reset loop unit writes the packaged batch data frame to the corresponding archived variable through the WinCC archiving interface. The WinCC database automatically assigns an independent batch code to the data group, generating a queryable and exportable formal batch record. The batch record is permanently stored in the WinCC historical archive library, meeting the needs of quality traceability and equipment operation and maintenance analysis in the production of calcium carbide furnace batching. After completing batch data recording, the reset loop unit scans the system instruction register through the STEP7 program. The instruction register stores various control instructions such as new material shortage trigger signals, manual batching instructions, and system pause instructions issued by the host computer. The program checks whether there is a new valid instruction identifier in the register. The valid instruction identifier is a Boolean status signal that indicates the start of a new batching task. If no new valid instruction is detected in the instruction register, the reset loop unit sends a loop completion reset confirmation signal to the material level detection trigger unit through the PLC internal data bus. The loop completion reset confirmation signal is a standard permission signal that indicates that the entire batching closed-loop process has been completed. After receiving the confirmation signal, the material level detection trigger unit immediately releases the signal monitoring lock state of the current cycle and resumes uninterrupted cyclic scanning and monitoring of the output signals of all raw material silo material level sensors. The monitoring logic returns to the initial operating state of the system and continuously detects the transition state of the material level signal from high level to low level. The system officially enters the next round of automatic batching closed-loop cycle, waiting for a new valid material shortage trigger signal to start the subsequent batching operation.

[0029] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A closed loop control system for automatic batching of calcium carbide furnaces using STEP7 and WinCC, characterized in that, The application relates to a material level detection trigger unit (1) for performing delay confirmation filtering processing on material level sensor output signals of each raw material bin to generate effective material shortage trigger signals. The weighing bin distribution unit (2) is used for receiving the effective material shortage trigger signals and executing a load balancing and fixed priority combined bin selection strategy in a Step7 program environment to determine a target weighing bin according to a material shortage bin number carried in the effective material shortage trigger signals, and the bin selection strategy comprises the following steps: The Step7 program calls a preset priority distribution weight value generation function to perform weighted and normalized processing on the cumulative operation cycle number, the last equipment failure type identification and the cumulative running time after the last maintenance of each empty weighing bin to obtain a priority distribution weight value of each empty weighing bin, and the empty weighing bin with the highest priority distribution weight value is selected as the target weighing bin; when there are multiple empty weighing bins with equal priority distribution weight values, the Step7 program assigns the empty weighing bins in a fixed order from low to high according to the slave station addresses of the empty weighing bins in the hardware configuration. The weighing bin distribution unit (2) triggers the unloading and conveying control unit (3) to execute raw material unloading and conveying after the target weighing bin is determined, and the batching verification and correction unit (4) performs weighing deviation verification and correction after the unloading is completed; after the batching is qualified, the reset and cycle unit (5) executes equipment state resetting and batch data recording and returns to the material level detection trigger unit (1) to enter the next cycle. The material level detection trigger unit (1) starts a high-speed timer in the Step7 program by calling the high-speed timer in the material level detection trigger unit (1) when the material level sensor output signal of any raw material bin jumps from a high level state representing a normal material level to a low level state representing a material shortage, and continuously samples a low level signal corresponding to the low level state in a set first time period during the running of the high-speed timer.

2. The automatic batching closed-loop control system of calcium carbide furnace according to claim 1, characterized in that: If the low level signal sampled at each time in the first time period remains in the low level state, the material level detection trigger unit (1) confirms that the material shortage state is valid, generates and outputs the effective material shortage trigger signal containing the raw material bin number. If the low level signal sampled at any time in the first time period is in the high level state, the material level detection trigger unit (1) determines that it is an interference signal, immediately resets the high-speed timer and does not generate any trigger signal. After receiving the effective material shortage trigger signal, the Step7 program determines the empty weighing bin range according to a formula associated with the material shortage bin number through the integrated WinCC archiving data query function of the Step7 program, and sends a data request to the WinCC system. ​ 3. The automatic batching closed-loop control system of calcium carbide furnace according to claim 2, characterized in that: ​ The cumulative job cycle number is obtained by counting the number of times that each empty weighing bin successfully completes a complete batching process from feeding, weighing to unloading from the start of the current production shift to the time of data request, which is updated and archived to the WinCC database in real time by the Step7 program each time the reset cycle unit (5) completes batch data recording; The last device failure type identifier is obtained by the predefined type code corresponding to the last alarm recorded in the WinCC system for each weighing bin accessory device, which is used to distinguish the failure type; The cumulative running time since the last maintenance is obtained by counting the total time length of the main contactor of the driving motor of each weighing bin and its associated conveying device from the last planned maintenance completion and confirmation of normal operation, which is obtained by the Step7 program through corresponding motor running feedback signals.

4. The automatic batching closed-loop control system of calcium carbide furnace according to claim 3, characterized in that: The weight configuration table is pre-stored in a specific data block of the Step7 program, which defines the corresponding preset weight coefficients for the cumulative job cycle number, the last device failure type identifier and the cumulative running time since the last maintenance respectively; When the priority allocation weight generation function is executed, the cumulative job cycle number of each empty weighing bin is first read from the original data obtained by WinCC, and the cumulative job cycle number is multiplied by the corresponding preset weight coefficient to obtain the first sub-weight value; The last device failure type identifier is read, and the predefined failure level mapping table is queried according to the last device failure type identifier to convert different failure type identifiers into dimensionless failure influence coefficients, and then the failure influence coefficients are multiplied by the corresponding preset weight coefficients to obtain the second sub-weight value; The cumulative running time since the last maintenance is read, and the cumulative running time since the last maintenance is divided by the preset reference running time to obtain a running time ratio, and then the running time ratio is multiplied by the corresponding preset weight coefficient to obtain the third sub-weight value; Finally, the priority allocation weight generation function adds the first sub-weight value, the second sub-weight value and the third sub-weight value to obtain the preliminary priority allocation weight value of each empty weighing bin.

5. The automatic batching closed-loop control system of calcium carbide furnace according to claim 4, characterized in that: After obtaining the preliminary priority allocation weight value of each empty weighing bin, the Step7 program calls the dynamic adjustment module to read the planned total production and the actual cumulative production up to the current time from WinCC, calculates the production completion progress ratio, and queries the preset weight correction coefficient table according to the production completion progress ratio to obtain a dynamic adjustment factor, and finally the priority allocation weight value of each empty weighing bin is equal to the preliminary priority allocation weight value multiplied by the dynamic adjustment factor.

6. The automatic batching closed loop control system for calcium carbide furnace according to claim 5, characterized in that: When the priority allocation weight generation function calculates and two or more empty weighing bins have the same highest priority allocation weight, the Step7 program will activate the standby selection routine. The standby selection routine accesses the hardware configuration information of the Step7 project, reads the slave address corresponding to the empty weighing bin with the same highest priority allocation weight, and sorts the slave address values ​​in ascending order to generate a temporary assignment queue. Step 7 starts with the empty weighing bin corresponding to the first address of the temporary assignment queue, i.e. the slave station address with the smallest value. It then sequentially checks the equipment status and readiness signals of each empty weighing bin as a candidate for the target weighing bin, and finally determines the first empty weighing bin that passes the check as the target weighing bin.

7. The automatic batching closed loop control system for calcium carbide furnace according to claim 1, characterized in that: After the unloading and conveying control unit (3) completes the unloading of raw materials and closes the unloading door of the weighing bin, the batching verification and correction unit (4) reads the real-time stable weight value of the weighing sensor on the target weighing bin through the Step7 program, compares the real-time stable weight value with the target weight value of the batch of raw materials set by the WinCC formula, and calculates the absolute deviation value. If the absolute deviation value is less than or equal to the preset first allowable deviation, the verification is deemed qualified, and a feeding allow signal is directly sent to the reset loop unit (5); If the absolute deviation value is greater than the preset first allowable deviation but less than or equal to the preset second allowable deviation, where the second allowable deviation is greater than the first allowable deviation, then it is determined that correction is required. At this time, the Step7 program will control the fine feeding mechanism to perform jogging feeding or control the fine discharging mechanism to perform jogging discharging according to the sign of the deviation. After each jogging operation, the stable weight value will be reread and compared until the absolute deviation between the corrected stable weight value and the target weight value falls within the first allowable deviation range, and then a feeding permission signal will be sent. If the absolute deviation value is greater than the preset second allowable deviation, it is determined to be a batching failure, an alarm signal is sent and the system is locked, and no feeding allow signal is sent to the reset cycle unit (5).

8. The automatic batching closed loop control system for calcium carbide furnace according to claim 7, characterized in that: When the deviation is negative, i.e. the real-time stable weight value is less than the target weight value, it is determined to replenish the material. Step7 program calculates the estimated replenishment operation time based on the absolute deviation value, the preset bulk density of the raw material and the preset volumetric conveying efficiency of the fine feeding mechanism. Step 7: The program controls the fine feeding mechanism to run for the estimated feeding time. After the operation stops, it waits for the weight to stabilize and reads the new real-time stable weight value. The absolute deviation value is recalculated. If the requirements are still not met, the calculation and control process is repeated according to the new absolute deviation value until the requirements are met. The number of repetitions does not exceed the preset value. When the deviation is positive, the process of controlling the fine material feeding mechanism to perform inching material feeding is the same as the feeding process, but the controlled object is the fine material feeding mechanism.

9. The automatic batching closed loop control system for calcium carbide furnace according to claim 8, characterized in that: After the batching verification and correction unit (4) sends the feeding permission signal and the discharge valve of the target weighing bin is opened and the raw material is fed into the calcium carbide furnace, the reset cycle unit (5) is started. The reset cycle unit (5) clears all intermediate status flags involved in the target weighing bin in this batching cycle through the Step7 program. At the same time, the high-speed timer and trigger latch related to this cycle in the material level detection trigger unit (1) are reset, and the intermediate variable data block generated by the weighing bin allocation unit (2) for calculating the priority allocation weight for this cycle is cleared to zero.

10. The automatic batching closed-loop control system of calcium carbide furnace according to claim 9, characterized in that: While completing the equipment status reset, the reset cycle unit (5) packages the key data of this batching cycle through the Step7 program and writes it into the archive variable of the WinCC database through the WinCC archive interface to form a batch record. After completing the data recording, the reset cycle unit (5) checks whether a new instruction has been received. If not, it sends a cycle completion reset confirmation signal to the material level detection trigger unit (1). After receiving the cycle completion reset confirmation signal, the material level detection trigger unit (1) immediately resumes the monitoring state of the output signals of the material level sensors of all raw material silos and enters the next cycle.

Images