Intelligent PLC control system and method for spinning flame-retardant spun rayon yarn

Abstract

This invention discloses an intelligent PLC control system and method for flame-retardant rayon yarn spinning, relating to the field of cotton yarn spinning technology. It involves real-time acquisition and preprocessing of the fiber quantity waveform, tension signal, and linear velocity of the sliver cross-section; a preset voltage threshold; locking the start and end points of the thick section and integrating the excess portion to obtain the overfeed volume; multiplying this by the tension to obtain an impact risk index; if the index exceeds the safety threshold, the PLC issues a transient elastic yielding command to actively reduce the draft ratio and smoothly restore it; otherwise, it maintains the original speed, achieving pre-emptive yarn protection against over-drafting in the thick section. This invention, by constructing a feedforward quantification mechanism for overfeed volume and impact risk index, shifts the detection of thick sections from tension results to fiber quantity causes, realizing a process shift from reactive shutdown to proactive pre-emptive yarn protection; when the risk exceeds the limit, a transient elastic yielding protection command is triggered, and the speed smoothly restores; when the risk does not exceed the limit, the original speed is maintained, overcoming the blind spot of rigidly adhering to a constant draft ratio warning while reducing the breakage rate.

Description

Technical Field

[0001] This invention relates to the field of cotton yarn spinning technology, specifically to an intelligent PLC control system and method for spinning flame-retardant rayon yarn. Background Technology

[0002] Intelligent PLC control is used for flame-retardant rayon yarn spinning to overcome the spinning difficulties of flame-retardant viscose fibers, such as low strength, brittleness, and static electricity accumulation. This ensures uniform yarn consistency, stable flame-retardant performance, and high-quality continuous production. The principle is to use a PLC as the control core, collecting real-time sensor signals from various spinning equipment, including speed, tension, temperature, and humidity. Based on the preset optimal process curve for flame-retardant fibers, it automatically adjusts roller speed, spindle speed, and winding parameters through PID algorithms and logic programs. It also utilizes frequency converters and servo drives to maintain precise synchronization among multiple units. Simultaneously, it provides immediate shutdown alarms for abnormalities such as yarn breakage and entanglement. Combined with a human-machine interface, it achieves intelligent monitoring of the entire production line, thereby ensuring the consistency and production efficiency of flame-retardant rayon yarn through dynamic balance.

[0003] Existing PLC control relies on tension sensor signals as its core, using PID algorithms to maintain precise synchronization between roller speed and spindle speed, aiming to achieve a constant draft ratio. However, this logic creates a blind spot for warning of over-drafting of thick sections: when local thick sections form in flame-retardant viscose slivers due to uneven distribution of flame retardant, the fiber content in this section surges instantaneously. However, to maintain precise synchronization among multiple units, the PLC not only fails to actively release the speed ratio or reduce pressure, but also forcibly maintains the original draft ratio, causing the draft tension to rise sharply and form a peak. By the time the tension sensor detects the peak and triggers an immediate shutdown alarm for fiber breakage, irreversible breakage has already occurred inside the fiber. This delayed response of stopping after breakage is a typical manifestation of the difficulty of low strength in flame-retardant viscose fibers being amplified by process control, directly leading to a persistently high breakage rate and exposing the lack of early warning capabilities for the arrival of thick sections in the existing system. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an intelligent PLC control system and method for flame-retardant rayon yarn spinning. It solves the problem that existing PLC control systems, by rigidly adhering to a constant draft ratio, cannot actively buffer when thick sections enter the yarn. By the time the tension sensor triggers the breakage alarm, the fiber has already been forcibly broken. This delayed response directly amplifies the defect of low strength in flame-retardant fibers and exposes the system's lack of early warning capabilities for recognizing and flexibly avoiding thick sections.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an intelligent PLC control method for flame-retardant rayon yarn spinning, comprising the following specific steps: Step 1: Real-time acquisition of the fiber quantity waveform signal of the sliver cross-section, the tension signal of the drafting zone, and the current sliver linear speed, and preprocessing of all parameters; Step 2: Presetting a normal sliver voltage threshold, and locking the start and end points of the thick section based on the fiber quantity waveform signal of the sliver cross-section, calculating the length of the thick section, and integrating the waveform portion exceeding this threshold within this time period to obtain the overfeed volume; Step 3: Calculating the impact risk index by combining the overfeed volume with the tension signal of the drafting zone; Step 4: Analyzing whether an impact risk has occurred based on the impact risk index. If an impact is detected, the PLC sends a transient elastic speed-reducing protection command to the servo drive; if no impact is detected, the current draft ratio remains unchanged.

[0006] Furthermore, the method for obtaining the length of the thick section is as follows: the starting point and ending point of the thick section are obtained by analyzing the voltage value of the fiber quantity waveform signal of the sliver cross section and the normal sliver voltage threshold; the duration of the thick section is calculated based on the ending point and the starting point of the thick section; and the length of the thick section is calculated based on the duration of the thick section and the current sliver linear velocity.

[0007] Furthermore, the method for obtaining the starting point and ending point of the thick section is as follows: the voltage value of the fiber quantity waveform signal of the cross-section of the sliver is compared with the normal sliver voltage threshold. If the voltage value is greater than the threshold, it is recorded as the starting point of the thick section; if the voltage value is less than or equal to the threshold, it is recorded as the ending point of the thick section.

[0008] Furthermore, the specific method for obtaining the duration width of the thick section is as follows: ;in, Indicates the duration of the thick section. Indicates the end of the thick section. Indicates the starting point of the thick section.

[0009] Furthermore, the specific method for obtaining the length of the thick section is as follows: ;in, Indicates the length of the thick section. Indicates the duration of the thick section. This indicates the current linear velocity.

[0010] Furthermore, the specific method for obtaining the overfeed volume is as follows: during the time period from the start point to the end point of the coarse section, the voltage value of the fiber quantity waveform signal of the cross-section of the sliver at each moment is calculated with the normal sliver voltage threshold to obtain the excess voltage value at this moment, and then all the excess voltage values ​​at this moment are integrated to obtain the overfeed volume.

[0011] Furthermore, the specific method for obtaining the excess voltage value at this instant is as follows: Since the voltage value of the fiber quantity waveform signal of the sliver cross section is greater than the normal sliver voltage threshold during the time period from the start point to the end point of the thick section, the voltage value of the fiber quantity waveform signal of the sliver cross section at each moment is calculated by the difference between the voltage value and the normal sliver voltage threshold to obtain the excess voltage value at this instant, and the excess voltage value at this instant is greater than zero.

[0012] Furthermore, the specific method for obtaining the overfeed volume is as follows: ;in, Indicates the overfeed volume. Indicates the start of the thick section. Indicates the end of the thick section. This represents the voltage value of the waveform signal indicating the fiber quantity across the sliver cross-section at the current moment. This represents the normal strip voltage threshold at the current moment.

[0013] Furthermore, the impact risk index is obtained in the following way: the impact risk index is calculated by multiplying the overfeed volume with the tension signal value in the drafting zone.

[0014] An intelligent PLC control system for flame-retardant rayon yarn spinning includes the following specific modules: a data acquisition module for real-time acquisition of the fiber quantity waveform signal of the sliver cross-section, the tension signal of the drafting zone, and the current sliver linear speed, all of which are preprocessed; an overfeed volume analysis module for preset normal sliver voltage thresholds, locking the start and end points of the thick section based on the fiber quantity waveform signal of the sliver cross-section, calculating the length of the thick section, and integrating the waveform portion exceeding this threshold within this time period to obtain the overfeed volume; an impact risk calculation module for calculating the impact risk index by combining the overfeed volume with the tension signal of the drafting zone; and an execution module for analyzing whether an impact risk has occurred based on the impact risk index. If an impact is detected, the PLC sends a transient elastic speed-reducing protection command to the servo drive; if no impact is detected, the current draft ratio remains unchanged.

[0015] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: 1. By constructing a feedforward quantification mechanism for overfeed volume and impact risk index, a process shift from stopping the machine after breakage to proactive yarn protection beforehand has been achieved. Specifically, by installing a capacitive sensor array directly in front of the feed inlet of the rear roller, the waveform signal of the fiber quantity of the sliver cross section is collected in advance. Combined with the normal sliver voltage threshold, the start and end points of the thick section are locked and integrated to obtain the overfeed volume. Then, the overfeed volume is multiplied by the tension signal in the drafting zone to generate the impact risk index. Thus, the risk of yarn breakage is proactively assessed before the thick section enters the drafting zone, solving the early warning blind zone of the existing PLC control, which cannot identify the thick section in advance because it adheres to a constant drafting ratio.

[0016] 2. By using transient elastic speed protection commands, the system can flexibly avoid thick sections during the moment, reducing the breakage rate while ensuring yarn evenness. Specifically, when the impact risk index is greater than or equal to the safety threshold, the PLC sends a speed compensation of 1% to 3% to the servo drive and smoothly restores the original set value after the thick section waveform ends. When the impact risk index is less than the safety threshold, the current draft ratio is maintained to avoid excessive intervention in small fluctuations.

[0017] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0018] Figure 1 This is a flowchart of the dynamic posture analysis method of the present invention. Detailed Implementation

[0019] 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.

[0020] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0021] Example 1: like Figure 1 As shown, this embodiment of the invention provides an intelligent PLC control method for spinning flame-retardant rayon yarn, including the following specific steps: Step 1: Since the thick section is essentially an abnormal increase in local fiber quantity, a high-resolution capacitive sensor array is installed directly in front of the feed inlet of the rear roller. The array is configured with a PCap01 type capacitive digital converter chip and parallel plates to form a single channel. Multiple channels are arranged along the direction of sliver travel. The single channel sampling frequency is 10kHz, the output voltage range is 0-10V, and the spacing between adjacent channels is 2mm. The waveform signal of fiber quantity in the cross-section of the sliver is collected in real time. This waveform is a voltage waveform. However, the size of the thick section alone is not enough to judge the risk. When the sliver is slack, the thick section can pass through safely, but when it is taut, it will break at the slightest touch. Therefore, it is still necessary to use the strain gauge tension sensor already installed at the output end of the front roller. Typical models include the SCHMIDTFS series, with a range of 0-200cN and an output of 0-10V analog signal to collect the tension signal in the stretching zone in real time. The current linear speed of the fiber is read through the PLC's internal parameter channel to accurately determine the size of the coarse section. The system collects real-time waveform signals of fiber quantity in the cross-section of the sliver, tension signals in the drafting zone, and the current sliver linear speed. All data is cleaned to remove redundant values, and the timestamps of the waveform signals of fiber quantity in the cross-section of the sliver, tension signals in the drafting zone, and the current sliver linear speed are synchronized.

[0022] Step 2: Preset the normal sliver voltage threshold, which is 115% of the average voltage peak value recorded by the sensor multiple times for a standard weight sliver. This usually corresponds to a voltage of about 2.0 to 3.0V. This provides an objective physical benchmark for determining thick sections. Based on the fiber quantity waveform signal of the sliver cross-section, the start and end points of the thick sections are locked. The length of the thick sections is calculated, and the waveform portion exceeding this threshold within this time period is integrated to obtain the overfeed volume. The overfeed volume range corresponding to the thick sections is 50 to 500 V·ms. Step 3: Calculate the overfeed volume and the tension signal in the drafting zone to obtain the impact risk index. The normal spinning tension is 15 to 40 cN, the overfeed volume is 50 to 500 V·ms, and the impact risk index ranges from 750 to 20000 cN·V·ms. Step 4: Analyze whether an impact risk has occurred based on the impact risk index, i.e., set a safety threshold. Through experimental calibration, take 90% of the minimum critical impact risk index for breakage as the safety threshold, usually set to 2700 cN·V·ms. If an impact is detected, i.e., the impact risk index is greater than or equal to the safety threshold, the PLC sends a transient elastic speed-yielding protection command to the servo drive. That is, if the thick section is forced through the drafting zone under the current sliver tension, it will inevitably generate an abnormal tension peak. Therefore, in order to only cover the few milliseconds of the thick section passing through without affecting the overall production cycle, the drafting ratio is temporarily reduced by 1% to 3% to give the thick section room to pass through, thereby physically flattening it before the abnormal tension peak forms, and smoothly restoring it to the original set value after the thick section waveform ends. If no impact is detected, i.e., the impact risk index is less than the safety threshold, the current drafting ratio is maintained unchanged. That is, the size of the thick section is limited or the sliver is currently relatively loose, and there is sufficient buffer space between the fibers, so the thick section can pass through safely without breaking.

[0023] Example 2 differs from Example 1 in that: The method for obtaining the length of the thick section is as follows: By analyzing the voltage value of the fiber quantity waveform signal of the sliver cross-section and the normal sliver voltage threshold, the start and end points of the thick section are obtained. Based on the end and start points of the thick section, the duration of the thick section is calculated. Based on the duration of the thick section and the current sliver linear velocity, the length of the thick section is calculated. The length of the thick section is the basis for subsequent speed reduction window positioning. Only by knowing how many millimeters the thick section extends in space can the system accurately control the duration of the speed reduction command, so as not to miss the thick section or over-interfere with the normal sliver segment.

[0024] The starting and ending points of the thick section are obtained as follows: The voltage value of the fiber quantity waveform signal of the sliver cross section is compared with the normal sliver voltage threshold. This threshold is the physical boundary between the normal sliver and the thick section. That is, if the voltage exceeds this threshold, it means that the fiber quantity has exceeded the normal range. This is the most direct way to determine the boundary of the thick section. If the voltage value is greater than this threshold, it is recorded as the start of the thick section; if the voltage value is less than or equal to this threshold, it is recorded as the end of the thick section.

[0025] The specific method for obtaining the duration width of the thick section is as follows: ; in, Indicates the duration of the thick section. Indicates the end of the thick section. The starting point of the thick section is indicated by the time width, which is the span of the thick section on the time axis. It needs to be calculated from the starting point and the ending point in order to convert the time quantity into a spatial quantity in combination with the linear velocity.

[0026] The specific method for obtaining the length of the thick section is as follows: ; in, Indicates the length of the thick section. Indicates the duration of the thick section. This indicates the current linear velocity.

[0027] The specific method for obtaining the overfeed volume is as follows: During the time period from the start to the end of the coarse section, the voltage value of the fiber quantity waveform signal of the sliver cross-section at each moment is calculated with the normal sliver voltage threshold to obtain the excess voltage value at this moment. Then, all the excess voltage values ​​at this moment are integrated to obtain the overfeed volume. The overfeed volume is the total scale of excess fibers in the entire coarse section. It is not judged by the voltage at a single point, but by accumulating all the excess fiber quantity at every moment from the beginning to the end of the coarse section, and using a total amount to measure the degree of damage of this coarse section.

[0028] The specific method for obtaining the excess voltage value at this instant is as follows: Since the voltage value of the fiber quantity waveform signal of the sliver cross section is greater than the normal sliver voltage threshold during the time period from the start point to the end point of the thick section, the voltage value of the fiber quantity waveform signal of the sliver cross section at each moment is calculated by the difference between the voltage value and the normal sliver voltage threshold to obtain the excess voltage value at this moment, and the excess voltage value at this moment is greater than zero.

[0029] The specific method for obtaining the overfeed volume is as follows: ; in, Indicates the overfeed volume. Indicates the start of the thick section. Indicates the end of the thick section. This represents the voltage value of the waveform signal indicating the fiber quantity across the sliver cross-section at the current moment. This represents the normal fiber voltage threshold at the current moment. Mathematically, this definite integral adds up all the excess voltages at any instant within the coarse segment along the time axis. The physical meaning of the resulting area value is the total amount of excess fiber that will be over-fed into the drafting zone.

[0030] The specific methods for obtaining the shock risk index are as follows: The impact risk index is calculated by multiplying the overfeed volume and the tension signal in the drafting zone. Using a product instead of a single indicator is to fundamentally avoid misjudgments caused by looking only at the size of the thick section or the tension level. In other words, it avoids situations where the overfeed volume is very large but the sliver is slack, allowing the thick section to pass safely. In such cases, using the overfeed volume alone would cause unnecessary disturbances. Similarly, if the tension is very high but the thick section is extremely small, the sliver may be tight but will not break. In such cases, using the tension alone would also lead to excessive intervention.

[0031] Example 3: An intelligent PLC control system for flame-retardant rayon yarn spinning includes the following specific modules: Data acquisition module: used to acquire real-time waveform signals of fiber quantity in the cross-section of the sliver, tension signals in the drafting zone, and the current linear speed of the sliver, and to preprocess all of them; Overfeed volume analysis module: presets the normal sliver voltage threshold, and locks the start and end points of the thick section based on the fiber quantity waveform signal of the sliver cross section, calculates the length of the thick section, and integrates the waveform portion exceeding this threshold within this time period to obtain the overfeed volume; Impact risk calculation module: used to calculate the impact risk index by combining the overfeed volume with the tension signal in the drafting zone; Execution module: Used to analyze whether an impact risk has occurred based on the impact risk index. If an impact is detected, the PLC sends a transient elastic speed reduction protection command to the servo drive; if no impact is detected, the current draw ratio is maintained.

[0032] The preferred embodiments disclosed in this invention are merely illustrative examples of feasible implementation methods and are not intended to exhaustively cover all technical details of the invention, nor do they constitute a limitation on the scope of protection of this invention. In practical applications, those skilled in the art can make appropriate adjustments, combinations, or substitutions to the methods or systems described in these embodiments based on specific production conditions, equipment configurations, and process requirements, without departing from the core concept of this invention. For example, the acquisition method, data processing algorithm, control threshold, or specific implementation form of the execution unit can all be reasonably modified according to the actual situation.

[0033] Furthermore, the technical concepts disclosed in this invention have universal extensibility and adaptability. They are not only applicable to the specific scenarios described in the embodiments, but can also be applied in similar technical fields or related industrial processes through analogy, transplantation, or improvement. Any technical solution formed by making logically equivalent substitutions, reasonable adjustments to the order of steps, or recombination of module functions based on the principles, ideas, or framework disclosed in this specification should be considered to fall within the spirit and scope of this invention.

[0034] It should be further clarified that the specific descriptions and drawings in the patent documents are for the purpose of assisting in understanding the present invention only, and their details should not be interpreted as limitations on the claims. The true scope of protection of the present invention should be determined by the content of the claims recorded in the authorized text, and should cover all equivalent technical solutions that comply with the provisions of patent law under these claims. Any implementation method that has the same or similar function and achieves similar effects through reasonable changes in technical means under the guidance of the concept of the present invention falls within the scope of protection sought by the present invention.

[0035] Therefore, the descriptions in this specification are merely illustrative. Any adjustments to implementation methods, equivalent substitutions of technical features, or further applications based on the concept of this invention, as long as they do not depart from the overall technical approach described in this invention, should be included within the scope of protection of this invention. We encourage those skilled in the art to innovate and optimize based on their understanding of the core of this invention and in conjunction with specific practices, so as to jointly promote the progress and development of related technologies.

Claims

1. An intelligent PLC control method for spinning flame-retardant rayon yarn, characterized in that: The specific steps include the following: Step 1: Real-time acquisition of fiber quantity waveform signal of sliver cross section, tension signal of drafting zone and current sliver linear speed, and preprocessing of all data; Step 2: Preset the normal sliver voltage threshold, and lock the start and end points of the thick section according to the fiber quantity waveform signal of the sliver cross section, calculate the length of the thick section, and integrate the waveform portion exceeding this threshold within this time period to obtain the overfeed volume; Step 3: Calculate the impact risk index by combining the overfeed volume with the tension signal in the draw zone; Step 4: Analyze whether an impact risk has occurred based on the impact risk index. If an impact is detected, the PLC sends a transient elastic speed reduction protection command to the servo drive; if no impact is detected, the current draw ratio remains unchanged.

2. The intelligent PLC control method for flame-retardant rayon yarn spinning according to claim 1, characterized in that: The method for obtaining the length of the thick section is as follows: The starting and ending points of the thick section are obtained by analyzing the voltage value of the fiber quantity waveform signal of the sliver cross section and the normal sliver voltage threshold. The duration of the thick section is calculated based on the end point and the starting point of the thick section. The length of the thick section is calculated based on the duration of the thick section and the current sliver linear velocity.

3. The intelligent PLC control method for flame-retardant rayon yarn spinning according to claim 2, characterized in that: The method for obtaining the start and end points of the thick section is as follows: The voltage value of the fiber quantity waveform signal of the sliver cross section is compared with the normal sliver voltage threshold. If the voltage value is greater than the threshold, it is recorded as the start of the thick section; if the voltage value is less than or equal to the threshold, it is recorded as the end of the thick section.

4. The intelligent PLC control method for flame-retardant rayon yarn spinning according to claim 3, characterized in that: The specific method for obtaining the duration of the thick section is as follows: ； in, Indicates the duration of the thick section. Indicates the end of the thick section. Indicates the starting point of the thick section.

5. The intelligent PLC control method for flame-retardant rayon yarn spinning according to claim 4, characterized in that: The specific method for obtaining the length of the thick section is as follows: ； in, Indicates the length of the thick section. Indicates the duration of the thick section. This indicates the current linear velocity.

6. The intelligent PLC control method for flame-retardant rayon yarn spinning according to claim 5, characterized in that: The specific method for obtaining the overfeed volume is as follows: During the time period from the start to the end of the coarse section, the voltage value of the fiber quantity waveform signal of the sliver cross-section at each moment is calculated with the normal sliver voltage threshold to obtain the excess voltage value at this moment. Then, all the excess voltage values ​​at this moment are integrated to obtain the overfeed volume.

7. The intelligent PLC control method for flame-retardant rayon yarn spinning according to claim 6, characterized in that: The specific method for obtaining the excess voltage value at this instant is as follows: Since the voltage value of the fiber quantity waveform signal of the sliver cross section is greater than the normal sliver voltage threshold during the time period from the start point to the end point of the thick section, the voltage value of the fiber quantity waveform signal of the sliver cross section at each moment is calculated by the difference between the voltage value and the normal sliver voltage threshold to obtain the excess voltage value at this moment, and the excess voltage value at this moment is greater than zero.

8. The intelligent PLC control method for flame-retardant rayon yarn spinning according to claim 7, characterized in that: The specific method for obtaining the overfeed volume is as follows: ； in, Indicates the overfeed volume. Indicates the start of the thick section. Indicates the end of the thick section. This represents the voltage value of the waveform signal indicating the fiber quantity across the sliver cross-section at the current moment. This represents the normal strip voltage threshold at the current moment.

9. The intelligent PLC control method for flame-retardant rayon yarn spinning according to claim 8, characterized in that: The specific method for obtaining the shock risk index is as follows: The impact risk index is obtained by multiplying the overfeed volume with the tension signal value in the stretching zone.

10. An intelligent PLC control system for spinning flame-retardant rayon yarn, used to implement the intelligent PLC control method for spinning flame-retardant rayon yarn as described in any one of claims 1-9, characterized in that, The intelligent PLC control system for flame-retardant rayon yarn spinning includes: Data acquisition module: used to acquire real-time waveform signals of fiber quantity in the cross-section of the sliver, tension signals in the drafting zone, and the current linear speed of the sliver, and to preprocess all of them; Overfeed volume analysis module: presets the normal sliver voltage threshold, and locks the start and end points of the thick section based on the fiber quantity waveform signal of the sliver cross section, calculates the length of the thick section, and integrates the waveform portion exceeding this threshold within this time period to obtain the overfeed volume; Impact risk calculation module: used to calculate the impact risk index by combining the overfeed volume with the tension signal in the drafting zone; Execution module: Used to analyze whether an impact risk has occurred based on the impact risk index. If an impact is detected, the PLC sends a transient elastic speed reduction protection command to the servo drive; if no impact is detected, the current draw ratio is maintained.

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