An intelligent winding method for bend winding

Abstract

The present application relates to the technical field of winding air pipe, and particularly relates to an intelligent winding method for a curved winding pipe, which comprises the following steps: forming a polyester filament skeleton by spirally and crossly winding polyester filaments on the surface of a core mold, and winding the polyester filament skeleton by adhering and overlapping a felt strip; obtaining a radial pressure average based on the radial pressure borne by the core mold when the polyester filaments are wound, determining a skeleton state index based on the radial pressure average and a winding angle of the polyester filaments to determine the performance state of the polyester filament skeleton; obtaining inherent sound emission characteristics of the current batch of air guide pipes based on the geometric parameters of the air guide pipes, determining an original sound pressure level under a main resonance frequency, obtaining a felt porosity and an air flow resistance rate of the felt to determine a felt sound absorption coefficient; obtaining an actual sound absorption coefficient of the current batch of finished winding pipes to determine an actual coefficient deviation, and adjusting a threshold interval of the skeleton state index based on the actual coefficient deviation. The present application adaptively adjusts winding parameters of winding pipe production based on corresponding noise reduction requirements and material noise reduction performance.

Description

Technical Field

[0001] This invention relates to the field of winding hollow tube technology, and more particularly to an intelligent winding method for bending and winding tubes. Background Technology

[0002] With the continuous improvement of automotive NVH performance requirements, the curved winding tube, which is made of PET felt strips and polyester filament skeleton composite molding, has been widely used in automotive air filter intake systems. While achieving flexible bending adaptation of the pipeline, it relies on the porous felt structure to attenuate intake noise, solving the problems of large resonance noise and difficult control of intake noise in traditional rigid plastic bend tubes.

[0003] Currently, there are still significant technical shortcomings in the winding process for this type of composite curved spiral pipe: Traditional winding equipment is mostly designed for straight pipe structures and cannot adapt to the varying curvature and diameter characteristics of curved pipes. In the curved section, uneven bonding, wrinkling and displacement of PET felt strips are prone to occur, as well as positioning deviation of polyester filament skeleton, resulting in disordered pipe pore structure, which directly affects the stability of sound transmission loss and noise reduction effect.

[0004] The winding process relies on manual or semi-automatic adjustment. The tension of the felt strip winding, the amount of glue applied, and the tension of the skeleton cannot be controlled in a coordinated manner. This can easily lead to excessive tension that tears the felt, or insufficient tension that loosens the pipes. Glue leakage or accumulation can cause debonding and hardening. Long-term use can easily lead to structural failure and a decrease in noise reduction performance.

[0005] Lacking online sensing and closed-loop adjustment mechanisms, it is impossible to detect the wrapping fit, glue coating uniformity, and skeleton support status in real time. The wrapping trajectory, feeding speed, and coating parameters are all preset fixed values ​​and cannot be dynamically corrected according to the changes in the curvature of the bend, resulting in low yield and poor batch consistency.

[0006] The winding path planning of the bent pipe is rough, the movement of the winding head is prone to interference with the pipe fitting, the production efficiency is low, and it is difficult to adapt to the multi-specification, small-batch, and flexible production needs of the automotive industry, which restricts the large-scale application of noise-reducing bent winding pipes.

[0007] Therefore, existing bending and winding pipe forming methods cannot simultaneously meet the requirements of structural forming accuracy, noise reduction performance stability, and intelligent production. Developing an intelligent winding method that can adapt to the bending shape and adjust process parameters in real time has become an urgent technical problem to be solved in the manufacturing field of this type of intake noise reduction pipe.

[0008] Chinese Patent Publication No. CN106738822A discloses a composite fiber automotive exhaust pipe and its manufacturing process. The process involves using an electrically heated mandrel. After impregnation with resin, carbon fiber bundles are directly wound onto the mandrel under tension control. During the initial winding stage, the mandrel is heated at a constant temperature between 100-120°C until the thickness of the wound carbon fiber layer reaches 1 / 6 to 1 / 5 of the preset winding thickness. Then, after impregnation with resin, glass fiber bundles are directly wound onto the carbon fiber layer under tension control, while the mandrel is gradually heated at a rate of 5-10°C per 0.1mm winding thickness. After reaching 4 / 5 to 5 / 6 of the preset winding thickness, the carbon fiber bundles are impregnated again and directly wound onto the glass fiber layer under tension control until the preset winding thickness is reached, at which point winding stops. The mandrel is then heated at a constant temperature between 140-160°C until the carbon / glass composite fiber exhaust pipe is cured and formed. However, the manufacturing process of this composite fiber automotive exhaust pipe has the following problems: It is impossible to adaptively adjust the winding parameters of the winding tube production in real time based on the noise reduction requirements corresponding to the tracheal shape and the noise reduction performance of the winding material. Summary of the Invention

[0009] Therefore, the present invention provides an intelligent winding method for curved winding tubes to overcome the problem in the prior art that it is impossible to adaptively adjust the winding parameters of winding tube production in real time based on the noise reduction requirements corresponding to the tube shape and the noise reduction performance of the winding material.

[0010] To achieve the above objectives, the present invention provides an intelligent winding method for bending and winding tubes, comprising: Polyester filaments are spirally and crosswise wrapped around the surface of the core mold to form a polyester filament skeleton, and felt strips are attached and overlapped to wrap the polyester filament skeleton. The radial pressure average value is obtained based on the radial pressure borne by the mandrel during polyester filament winding. The skeleton state index is determined based on the radial pressure average value and the winding angle of the polyester filament to determine the performance state of the polyester filament skeleton. Based on the geometric parameters of the air intake tube, the inherent sound emission characteristics of the current batch of air intake tubes are obtained, the original sound pressure level at the main resonant frequency is determined, and the felt porosity and airflow resistance of the felt are obtained to determine the felt sound absorption coefficient. The overlap correction coefficient is determined based on the design overlap width of the felt strip, and the corrected felt sound absorption coefficient is determined in combination with the main resonant frequency. The expected residual noise is determined based on the corrected felt sound absorption coefficient and the original sound pressure level, and the sound absorption capacity of the wound tube with the current winding parameters for the exhaust pipe with the current sound characteristics is predicted. In response to the sound absorption capacity, the pressure fluctuation coefficient and circumferential non-uniformity of the polyester filament winding process are obtained to determine the fluctuation range of the felt sound absorption coefficient. Based on the fluctuation range, the uncertainty range of the felt sound absorption coefficient is determined to combine with the original sound pressure level to determine the worst-case residual noise assessment of the compliance risk level of the winding tube. Based on the compliance risk level, combined with the circumferential non-uniformity and the pressure fluctuation coefficient, the detection cycle is adjusted to determine whether to adjust the design overlap width of the felt strip winding process and to determine the adjustment direction of the design winding angle according to the skeleton state index. Obtain the actual sound absorption coefficient of the current batch of finished spiral tubes to determine the actual coefficient deviation, and adjust the threshold range of the skeleton state index based on the actual coefficient deviation.

[0011] Furthermore, the process of determining the performance state of the polyester filament skeleton includes: When the skeleton state index is greater than or equal to the first index threshold and less than or equal to the second index threshold, the skeleton is determined to be in the first performance state, and the skeleton performance and stability are determined based on the circumferential non-uniformity and the pressure fluctuation coefficient. When the skeleton state index is less than the first index threshold, the skeleton is judged to be in the second performance state, with insufficient radial support potential. When the skeleton state index is greater than the second index threshold, the skeleton is judged to be in the third performance state, indicating that the radial support potential is too large.

[0012] Furthermore, the circumferential non-uniformity is determined based on the circumferential pressure distribution of the mandrel during polyester filament winding, and the pressure fluctuation coefficient is determined based on the radial standard deviation and radial pressure mean of the radial pressure borne by the mandrel per unit time. If the circumferential non-uniformity is less than the uniformity threshold and the pressure fluctuation coefficient is less than the fluctuation threshold, it is judged that the skeleton performance meets the standard and is uniform and stable. The radial clamping force and the winding angle are well matched. The circumferential pressure distribution of the skeleton is uniform, the instantaneous pressure is stable, and there are no abnormal fluctuations. Then the felt strip winding process can be carried out.

[0013] Furthermore, the geometric parameters of the air intake tube include the cavity length, cavity diameter, and tube wall thickness of the air intake tube in the current batch, and the main resonant frequency is determined based on the geometric parameters of the air intake tube in the current batch. The sound absorption coefficient of the felt is determined based on the main resonant frequency. The overlap correction coefficient of the felt is determined based on the designed overlap width of the felt strip. The corrected sound absorption coefficient of the felt is then determined based on the overlap correction coefficient.

[0014] Furthermore, the expected residual noise is determined based on the corrected sound absorption coefficient of the felt; If the expected residual noise is less than or equal to the difference between the target residual noise and the safety margin, then the winding tube with the current winding parameters is predicted to have sufficient sound absorption capacity for the exhaust pipe with the current sound characteristics, and the winding tube meets the standard. If the expected residual noise is greater than the difference between the target residual noise and the safety margin, but less than the target residual noise, then the winding tube with the current winding parameters is predicted to have a critical sound absorption capacity for the exhaust pipe with the current sound characteristics, and the winding tube is at risk of failing to meet the standard. If the expected residual noise is greater than the target residual noise, then the winding tube with the predicted current winding parameters is insufficient for the sound absorption capacity of the exhaust pipe with the current sound characteristics, and the winding tube does not meet the standard.

[0015] Furthermore, based on the pressure fluctuation coefficient and circumferential non-uniformity determined by the polyester filament winding process, the uncertainty range of the effect of the process fluctuation of the winding process on the felt sound absorption coefficient of the finished winding tube is determined. The worst-case residual noise is determined based on the lower limit of the uncertainty range of the sound absorption coefficient of the felt. If the worst-case residual noise is less than or equal to the target residual noise, the compliance risk of the wound tube is judged to be at a low risk level. If the worst-case residual noise is greater than the target residual noise, then the risk of non-compliance with standards for the wound tube is judged to be at a medium-risk level.

[0016] Furthermore, the compliance risk is at a medium risk level, and the detection cycle is adjusted based on the circumferential non-uniformity and the pressure fluctuation coefficient; When the pressure fluctuation coefficient is greater than the fluctuation threshold, it is determined that the tension in the winding process is unstable. The detection cycle of tension control is reduced according to the ratio of the pressure fluctuation coefficient to the fluctuation threshold. When the circumferential non-uniformity is greater than the uniformity threshold, it is determined that the circumferential pressure in the winding process is uneven. Based on the ratio of the circumferential non-uniformity to the uniformity threshold, the detection cycle of the coaxiality between the mandrel and the rotation axis is reduced.

[0017] Furthermore, when the skeleton performance meets the standard, adjust the design overlap width of the felt strip winding process, and after adjusting the overlap width, determine the corresponding overlap correction coefficient. If the adjusted felt sound absorption coefficient corresponding to the adjusted overlap correction coefficient is less than or equal to the target residual noise, it is determined that the adjusted overlap width can meet the exhaust pipe sound absorption capacity requirements of the wound tube for the current sound characteristics, and the design overlap width is determined to be the adjusted overlap width. If the adjusted overlap correction coefficient reaches the upper limit of the designed overlap width, and the corresponding corrected felt sound absorption coefficient is greater than the target residual noise, then it is determined that the adjusted overlap width does not meet the exhaust pipe sound absorption capacity requirements of the wound tube for the current sound characteristics, and the adjustment direction of the designed winding angle is determined according to the skeleton state index.

[0018] Furthermore, when the skeleton state index is less than the first index threshold, it is determined that the radial support potential is insufficient, and the design winding angle is increased. When the skeleton state index is greater than the second index threshold, it is determined that the radial support potential is too large, and the design winding angle is reduced.

[0019] Furthermore, the process of adjusting the threshold range of the skeleton state index includes: The average sound absorption coefficient of the current batch of finished spiral wound tubes is obtained as the actual sound absorption coefficient, and the actual coefficient deviation between the actual sound absorption coefficient and the expected sound absorption coefficient of the felt is determined. If the actual coefficient deviation is higher than the allowable deviation range, it is determined that the actual sound absorption effect of the finished product exceeds expectations, and the threshold range of the first index threshold and the second index threshold is increased according to the actual coefficient deviation. If the actual coefficient deviation is lower than the allowable deviation range, it is determined that the actual sound absorption effect of the finished product is lower than expected, and the threshold range of the first index threshold and the second index threshold is adjusted down according to the actual coefficient deviation.

[0020] Compared with existing technologies, the advantages of this invention are as follows: It achieves intelligent and precise production of wound tubes through a closed-loop control of the entire process, from polyester filament skeleton forming, felt strip winding, acoustic performance prediction, process fluctuation risk assessment to threshold adaptive adjustment; it establishes a pre-prediction model of acoustic performance based on the skeleton state index and felt sound absorption coefficient, enabling prediction of the finished product's noise reduction capability during the winding stage; it introduces a quantitative assessment and graded adjustment strategy for process fluctuations, optimizing the detection cycle, overlap width, and winding angle for medium-risk conditions, effectively suppressing the impact of uncertainty on acoustic performance; and it dynamically corrects the judgment threshold of the skeleton state index through feedback from the actual sound absorption coefficient, enabling the system to have self-learning and self-optimization capabilities. This invention improves the batch consistency, process robustness, and production adaptability of the acoustic performance of wound tubes.

[0021] Furthermore, as the core supporting skeleton of the spiral wound tube's felt layer, polyester filament must ensure the radial stiffness and bending flexibility of the spiral wound tube to provide stable support for subsequent PET felt winding. This invention uses multi-dimensional real-time sensing of radial pressure, circumferential uniformity, and tension stability during the polyester filament winding process to predictively adjust the winding parameters of the polyester filament in advance, adaptively changing the performance of the skeleton formed by the polyester filament, ensuring that the bent tube has radial support force and bending flexibility after forming. Based on the average radial pressure and winding angle, a skeleton state index is constructed to accurately quantify the balance between the skeleton's radial support force and bending flexibility. When the skeleton state index exceeds the threshold range or the circumferential non-uniformity and pressure fluctuation coefficient exceed the standard, the skeleton performance abnormality can be determined in real time and adjustment can be triggered to ensure that the bent tube has excellent radial compressive strength and bending flexibility after forming, effectively avoiding tube collapse due to an overly soft skeleton or installation difficulties due to an overly hard skeleton, significantly improving the product consistency and service reliability of the spiral wound tube.

[0022] Furthermore, this invention establishes a quantitative correlation model between the geometric parameters of the air intake tube and the original noise, and integrates the sound absorption coefficient prediction of multiple factors such as felt porosity, airflow resistance, and overlap structure to achieve batch-level pre-evaluation of the noise reduction capability of the wound tube. Based on the comparison between the expected residual noise and the target value, the sound absorption effect is divided into three levels: sufficient, critical, and insufficient. This allows for the prediction of the noise reduction risk under the current batch matching of felt and air intake tube before or during the winding process, avoiding the lag in verifying the noise reduction effect that traditional methods require waiting until the finished product is made. The prediction method provides a quantitative decision-making basis for process adjustments such as overlap width and winding parameters, effectively reducing the defect rate and improving the acoustic controllability of wound tube design and production.

[0023] Furthermore, the structural geometric parameters of the pipeline are similar to those of musical instruments, resulting in different noise levels and frequencies. While the sound-absorbing capacity of the felt strips constituting the wound tube is fixed, the sound-absorbing degree of the finished wound tube is affected by the winding parameters. Therefore, based on the batch characteristics of the air intake tube, the predicted noise level range, the predicted sound-absorbing capacity of the finished product based on the current winding parameters and batch characteristics of the felt strips, and the fluctuation range of the sound-absorbing capacity determined by the device fluctuation correction based on the polyester filament winding, the risk that the sound absorption and noise reduction capacity of the finished product may not meet the required range is determined. This invention introduces a pressure fluctuation coefficient and a circumferential non-circular... The method uniformly measures the fluctuations in the winding process and assesses the uncertainty range of the felt sound absorption coefficient and the residual noise in the worst case, classifying the compliance risk into low-risk and medium-risk levels. For the medium-risk level, it further distinguishes different working conditions such as process fluctuation as the main factor, and whether the skeleton performance meets the standard or is abnormal, and formulates graded adjustment strategies such as reducing the detection cycle, adjusting the overlap width, or adjusting the winding angle. This achieves closed-loop control from risk identification to parameter correction, avoids blind adjustment, and ensures that the sound absorption and noise reduction capabilities of the finished product can still be effectively controlled under process fluctuation conditions, significantly improving the robustness and batch consistency of the acoustic performance of the wound tube.

[0024] Furthermore, this invention establishes a threshold closed-loop feedback mechanism based on actual sound absorption effect by collecting the actual sound absorption coefficient of the finished wound tube and comparing the deviation with the expected sound absorption coefficient. When the actual sound absorption effect is better than expected, the threshold range of the skeleton state index is appropriately widened to avoid efficiency loss caused by over-adjustment. When the actual sound absorption effect is lower than expected, the threshold range is tightened accordingly to improve the skeleton performance screening standard. Through adaptive adjustment, the judgment criterion of the skeleton state index can be continuously optimized according to the actual acoustic performance of the batch, solving the limitation that a fixed threshold is difficult to adapt to different felt batches and air tube models, and realizing intelligent iteration of the winding process and precise control of acoustic performance. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating an intelligent winding method for a bent winding tube according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of the winding tube in an embodiment of the present invention; Figure 3 This is a flowchart illustrating the process of determining the performance state of the polyester filament skeleton in an embodiment of the present invention. Figure 4 This is a comparison diagram of the transmission loss test of the wound tube in the embodiment of the present invention; In the diagram: 1 - Winding tube. Detailed Implementation

[0026] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0027] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0028] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0029] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] Please see Figures 1-4 As shown, Figure 1 This is a flowchart illustrating an intelligent winding method for a bent winding tube according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of the winding tube in an embodiment of the present invention; Figure 3 This is a flowchart illustrating the process of determining the performance state of the polyester filament skeleton in an embodiment of the present invention. Figure 4 This is a comparison diagram of the transmission loss test of the wound tube in an embodiment of the present invention.

[0031] This invention provides an intelligent winding method for bent and wound tubes, comprising: Step S1: Polyester filaments are spirally and cross-wound onto the surface of the core mold to form a polyester filament skeleton, and felt strips are attached and overlapped to wrap the polyester filament skeleton. Step S2: Obtain the average radial pressure based on the radial pressure borne by the mandrel during polyester filament winding, and determine the skeleton state index based on the average radial pressure and the winding angle of the polyester filament to determine the performance state of the polyester filament skeleton. Step S3: Based on the geometric parameters of the air intake tube, obtain the inherent sound emission characteristics of the current batch of air intake tubes, determine the original sound pressure level at the main resonant frequency, and obtain the felt porosity and airflow resistance of the felt to determine the felt sound absorption coefficient. Step S4: Determine the overlap correction coefficient based on the design overlap width of the felt strip, determine the corrected felt sound absorption coefficient in combination with the main resonant frequency, determine the expected residual noise based on the corrected felt sound absorption coefficient and the original sound pressure level, and predict the sound absorption capacity of the wound tube with the current winding parameters for the exhaust pipe with the current sound characteristics. Step S5: In response to the sound absorption capacity, obtain the pressure fluctuation coefficient and circumferential non-uniformity of the polyester filament winding process to determine the fluctuation range of the felt sound absorption coefficient, and determine the uncertainty range of the felt sound absorption coefficient based on the fluctuation range to determine the worst-case residual noise assessment of the winding tube in combination with the original sound pressure level. Step S6: Based on the compliance risk level, combined with the circumferential non-uniformity and the pressure fluctuation coefficient, adjust the detection cycle, determine whether to adjust the design overlap width of the felt strip winding process, and determine the adjustment direction of the design winding angle according to the skeleton state index. Step S7: Obtain the actual sound absorption coefficient of the current batch of finished wound tubes, determine the actual coefficient deviation, and adjust the threshold range of the skeleton state index based on the actual coefficient deviation.

[0032] Specifically, this invention achieves intelligent and precise production of wound tubes through a closed-loop control of the entire process, from polyester filament skeleton forming, felt strip winding, acoustic performance prediction, process fluctuation risk assessment to threshold adaptive adjustment; it establishes a pre-prediction model of acoustic performance based on skeleton state index and felt sound absorption coefficient, which can predict the noise reduction capability of the finished product during the winding stage; it introduces a quantitative assessment and graded adjustment strategy for process fluctuations, optimizing the detection cycle, overlap width, and winding angle for medium-risk conditions, effectively suppressing the impact of uncertainty on acoustic performance; and it dynamically corrects the judgment threshold of skeleton state index through feedback from actual sound absorption coefficient, enabling the system to have self-learning and self-optimization capabilities. This invention improves the batch consistency, process robustness, and production adaptability of the acoustic performance of wound tubes.

[0033] In this embodiment, the material of the PET spiral tube is PET felt strip, the skeleton is polyester filament, and the auxiliary material is glue; the PET felt strip is supported by polyester filament and wound by the equipment, and then bonded with glue to form an air intake pipe.

[0034] PET spiral wound tubing is used in automotive air filter intake pipes to reduce noise at the air inlet of the automotive air filter intake pipe.

[0035] like Figure 4 As shown in the figure, the PET spiral wound tube in this embodiment has undergone performance testing, and the loss transmission of the non-woven spiral wound tube is significantly better than that of the braided tube.

[0036] Understandably, the process for manufacturing the curved spiral tube to reduce noise at the air intake of an automotive air filter is not to directly wind it onto the existing air intake tube. Instead, it is first wound into an independent tubular structure on a mandrel mold, demolded, and then installed onto the air filter. Process flow: PET felt strip pretreatment: PET felt rolls with high porosity and high airflow resistivity are selected to meet the requirements of air intake sound absorption and noise reduction. They are cut into continuous felt strips with a design width of 15~30mm and a thickness of 0.8~2.0mm. Static electricity on the felt surface is removed using an electrostatic eliminator to prevent dust adsorption and overlap misalignment during winding. The strips are then dried at a low temperature of 60℃ for 30 minutes to remove moisture, preventing bubbling and poor adhesion during subsequent adhesive application. A corresponding mandrel is customized according to the design diameter of the air vent pipe of the car air filter. The main shaft drives the mandrel to rotate at a constant speed, and the winding head moves axially along the preset trajectory to simultaneously feed polyester filaments. The polyester filaments are covered on the surface of the mandrel in a spiral cross-winding manner, with a winding angle of 45°~60° and a winding density evenly distributed according to the design requirements to form a continuous flexible mesh support skeleton, ensuring that the bent tube has radial support force and bending flexibility after forming. The winding equipment conveys the pre-treated PET felt strips to the winding head, and the felt strips are wrapped with the polyester filament skeleton. The felt strips are wound in a spiral overlap, with the overlap width controlled at 3~5mm to ensure the sealing of the wrapping, while retaining the porous structure inside the felt to provide a channel for air intake noise absorption. The coating mechanism combines roller coating and dot spraying to simultaneously apply adhesive to the contact layer between the felt strip and the skeleton, as well as at the overlap of the felt. After coating, the pressing roller immediately presses the adhesive to eliminate air bubbles and ensure that the PET felt, polyester filament skeleton, and overlap layer are firmly bonded. The depth of adhesive penetration is strictly controlled to bond only the surface fibers and not to block the internal pores of the PET felt, thus avoiding the loss of air intake, sound absorption, and noise reduction capabilities. The segmented curing process is adopted. After the molded tube is wound and formed, it is sent into a constant temperature oven and pre-cured at a low temperature of 40~50℃ for 20~30 minutes to allow the adhesive to initially solidify and prevent the felt from shifting and the adhesive from flowing. High-temperature final curing: Heat to 70~80℃ and cure for 30~40 minutes to ensure complete cross-linking and curing of the adhesive, reaching peak bonding strength; During the curing process, the core mold continuously fixes the curvature of the bent tube to prevent product springback deformation. After curing, the tube is allowed to cool naturally to room temperature to ensure that the shape of the bent tube is stable and the adhesive layer is free from aging and cracking. After cooling, the tube is demolded and corrected to complete the winding of the automotive air filter vent pipe.

[0037] The radial pressure P(t) borne by the mandrel is determined by measuring the force of the polyester filament skeleton pressing vertically on the surface of the mandrel during the polyester filament winding process using an embedded pressure sensor in the mandrel. This reflects the clamping force of the polyester filament skeleton on the mandrel under the combined effects of winding tension and winding angle. The circumferential pressure distribution P of the mandrel during polyester filament winding is obtained by a pressure sensor distributed circumferentially in the mandrel. This reflects the circumferential uniformity of the polyester filament skeleton, and 3-6 pressure sensors are evenly distributed on the same axial section of the mandrel. The dynamic pressure fluctuation Pd(t) is determined by measuring the impact force when the polyester filament comes into instantaneous contact with the mandrel through PVDF piezoelectric films arranged alternately with pressure sensors on the surface of the mandrel. The tension stability is reflected by the instantaneous impact when the filaments come into contact.

[0038] Obtain the mean and standard deviation of several radial pressures within one second, as well as the maximum and minimum values ​​of radial pressure within one second, and the mean and standard deviation of dynamic pulse amplitudes of several dynamic pulses of dynamic pressure fluctuation within one second. The circumferential non-uniformity is determined based on the circumferential pressure distribution. The circumferential non-uniformity is the difference between the maximum and minimum values ​​of several circumferential pressures within the same axial section / the average radial pressure, reflecting the circumferential uniformity of the polyester filament skeleton. The pressure fluctuation coefficient is determined based on the radial standard deviation and the radial pressure mean, and the pressure fluctuation coefficient = radial standard deviation / radial pressure mean, which reflects the instantaneous pressure stability. Pulse stability is determined based on the mean dynamic pulse amplitude and the standard deviation of the dynamic pulse amplitude. The pulse stability = standard deviation of dynamic pulse amplitude / mean dynamic pulse amplitude, which reflects the stability of the filament tension.

[0039] The skeleton state index is determined based on the mean radial pressure and the winding angle of the polyester filament, wherein the skeleton state index = [mean radial pressure / (1 / tangent of winding angle)] / target calibration coefficient; It is understandable that the winding angle is the angle between the filament bundle and the mandrel axis, the mean radial pressure is used to represent the radial support potential of the skeleton, and (1 / tangent of the winding angle) is used to represent the bending flexibility potential of the skeleton.

[0040] In practice, the target calibration coefficient is an offline experimental calibration value, used to make the skeleton state index one under ideal conditions; Several sets of samples prepared under different winding parameters, i.e. different winding tensions and winding angles, are taken. The mean radial pressure and winding angle of each set of samples are recorded online. After demolding, the radial stiffness and bending flexibility of the samples are measured. The combination of mean radial pressure and winding angle that makes the radial stiffness and bending flexibility simultaneously meet the design requirements is determined. The product of the mean radial pressure and the tangent of the winding angle of this combination is calculated as the target calibration coefficient.

[0041] When the skeleton state index is greater than or equal to the first index threshold and less than or equal to the second index threshold, the skeleton is determined to be in the first performance state, and the skeleton performance and stability are determined based on the circumferential non-uniformity and the pressure fluctuation coefficient. Specifically, if the circumferential non-uniformity is less than the uniformity threshold and the pressure fluctuation coefficient is less than the fluctuation threshold, the skeleton performance is judged to be up to standard, uniform and stable, the radial clamping force and winding angle are well matched, the circumferential pressure distribution of the skeleton is uniform, the instantaneous pressure is stable, and there are no abnormal fluctuations, then the felt strip winding process can be carried out.

[0042] When the skeleton state index is less than the first index threshold, the skeleton is judged to be in the second performance state, with insufficient radial support potential. When the skeleton state index is greater than the second index threshold, the skeleton is judged to be in the third performance state, indicating that the radial support potential is too large. Wherein, the first index threshold is 0.9, the second index threshold is 1.1, the uniformity threshold is 15%, and the fluctuation threshold is 10%.

[0043] Understandably, the ideal value of the skeleton state index is 1, representing a design balance between radial support force and bending flexibility. A deviation range of ±10%, i.e., 0.9~1.1, is a commonly used engineering tolerance in industrial control. Experiments show that when the skeleton state index deviates from 1 by more than 10%, the radial stiffness or bending flexibility of the bent tube after demolding exhibits measurable performance degradation, but the performance remains acceptable when the deviation is within 10%. Simultaneously, with a symmetrical design, the impact of excessive radial support (>1.1) and insufficient support (<0.9) on product failure is roughly equivalent, hence the threshold is set to a symmetrical value. Furthermore, based on the measurement noise tolerance, the sensor signal has an inherent fluctuation of ±3%~5%, and a 10% threshold can avoid frequent false triggering adjustments.

[0044] Circumferential non-uniformity reflects the pressure difference of the skeleton in the circumferential direction. 15% is a commonly used limit for the concentricity acceptance of rotating machinery. When the uniformity threshold is < 15%, the impact of eccentricity on product performance can be ignored. When it exceeds 15%, after demolding, the bent tube will be locally too hard at the point of maximum pressure and locally too soft at the point of minimum pressure, which may lead to cracking or collapse during bending. Pressure sensors themselves have an individual difference of ±5%. The 15% threshold is higher than the sensor error to avoid misjudgment.

[0045] The pressure fluctuation coefficient reflects the relative fluctuation range of instantaneous pressure. The typical accuracy of the industrial polyester filament tension control system is ±5%, corresponding to a pressure fluctuation coefficient of about 5% to 8%. The 10% threshold leaves a safety margin of 2% to 5%. Exceeding 10% indicates that there is a significant abnormality in the tension controller or filament supply system. Experiments show that when the pressure fluctuation coefficient exceeds 10%, uneven felt compression causes the sound absorption coefficient to fluctuate by more than ±0.05, which is enough to affect the product compliance rate.

[0046] Specifically, polyester filament, as the core supporting skeleton of the spiral wound tube's felt layer, must ensure the radial stiffness and bending flexibility of the spiral wound tube, providing stable support for subsequent PET felt winding. This invention uses multi-dimensional real-time sensing of radial pressure, circumferential uniformity, and tension stability during the polyester filament winding process to predictively adjust the winding parameters of the polyester filament in advance, adaptively changing the performance of the skeleton formed by the polyester filament, ensuring that the bent tube has both radial support force and bending flexibility after forming. Furthermore, a skeleton state index is constructed based on the average radial pressure and winding angle to accurately quantify the balance between the skeleton's radial support force and bending flexibility. When the skeleton state index exceeds the threshold range or the circumferential non-uniformity and pressure fluctuation coefficient exceed the standard, the skeleton performance abnormality can be determined in real time and adjustment can be triggered, ensuring that the bent tube has excellent radial compressive strength and bending flexibility after forming, effectively avoiding tube collapse due to an overly soft skeleton or installation difficulties due to an overly rigid skeleton, significantly improving the product consistency and service reliability of the spiral wound tube.

[0047] When the skeleton performance is substandard, the adjustment strategy for the winding parameters is determined by combining the batch characteristics of the felt strip, porosity, airflow resistance rate, and batch characteristics of the air intake tube, cavity length, tube thickness, cavity diameter, and device fluctuations determined by the winding of polyester filaments, to predict whether the sound absorption and noise reduction capability of the finished product under the current winding parameters can meet the required range.

[0048] Understandably, the geometric parameters of the airway determine its inherent sound characteristics. Tubes of different lengths and diameters, like musical instruments of different sizes, will produce noise of different frequencies and intensities.

[0049] The geometric parameters of the air intake tube include the cavity length L, cavity diameter D, and tube wall thickness t of the air intake tube in the current batch. The main resonant frequency is determined based on the geometric parameters of the air intake tube in the current batch. Specifically, for an air inlet with one open end and a closed end connected to an air filter, its acoustic characteristics are approximately those of a quarter-wavelength tube, with a resonant frequency fn = (2n-1)·c / 4L, (n = 1, 2, 3, ...), where n is the harmonic order; In practice, the main resonant frequency f1 = 85 / L, where the speed of sound c is 340 m / s, and the fundamental frequency of the quarter-wavelength tube f = c / (4L) = 340 / (4L) = 85 / L, where L is in meters and f is in Hz.

[0050] The original sound pressure level at the main resonant frequency is estimated based on the empirical formula for the main resonant frequency and the original sound pressure level: Original sound pressure level = K0 - K1log 10 (L), where K0 and K1 are calibration coefficients. The typical value of K0 ranges from 100 to 120, and the typical value of K1 ranges from 20 to 40. In this embodiment, K0 is 110 and K1 is 30.

[0051] Understandably, the original sound pressure level formula is based on acoustic theory and experimental data. The sound pressure level is proportional to the logarithm of the distance and the size of the sound source, which is a basic characteristic of the spherical diffusion of sound waves. The logarithm of 1 / L² attenuation is represented by the log(L) term. The calibration coefficients K0 and K1 are obtained by fitting the sound pressure level of different lengths of air ducts at the 1 / 4 wavelength resonant frequency. K0≈110dB, which is the typical value for a 0.5m tube length, and K1≈30dB / decathlon, which is the average slope of the sound pressure level as a function of length.

[0052] Based on felt porosity The sound absorption coefficient of the felt is determined by the airflow resistance ratio σ. The original thickness of the felt strip is h0 (in meters), the air density ρ0 is 1.2 kg / m³, and the sound velocity c0 is 340 m / s. The airflow resistance ratio σ and the porosity of the felt are obtained through experimental testing or by consulting relevant resources.

[0053] Specifically, X = (σ·h0) / (ρ0·c0), and the unit of airflow drag coefficient σ is kg / (m). 3 ·s), X and felt porosity It is a dimensionless parameter; Felt sound absorption coefficient = maximum sound absorption coefficient In the formula, γ is the felt material constant, and the maximum sound absorption coefficient in practice is taken as 0.95; The material constant of felt is dimensionless, and can be controlled by X and the porosity of felt. Experiments were conducted to determine the sound absorption coefficient of felt. The experimental calibration showed a typical value of 0.5~2.0. In practice, the sound absorption coefficient of the felt varies with the noise frequency. For a given main resonant frequency f1, a frequency-corrected sound absorption coefficient of the felt is introduced. The sound absorption coefficient of the felt at the resonant frequency f1 is equal to the sound absorption coefficient of the felt · (1 - e^(-f1 / f1))^(-f1 / f1 ... -δ·f1 / fr In the formula, fr is the reference frequency, which is taken as 1000 Hz in practice, and δ is the frequency sensitivity coefficient. The experimental calibration is performed by obtaining different resonant frequencies and the corresponding sound absorption coefficients of felt. The typical value of δ ranges from 0.5 to 1.5.

[0054] It is understandable that the formula for the sound absorption coefficient of felt is based on a simplification of the sound absorption characteristics of porous materials. When sound waves propagate in porous materials, the energy decays exponentially; the sound absorption coefficient = 1 - the reflection coefficient, and the reflection coefficient decreases in a negative power of e with the increase of the dimensionless parameter X. Therefore, the sound absorption coefficient takes the form of 1 - e^{-...}; the physical meaning of X is the dimensionless resistance of the material to sound waves, which is the core determining factor of sound absorption capacity; the porosity φ determines the proportion of material that effectively participates in sound absorption, serving as an exponential multiplier correction; by experimentally measuring the sound absorption coefficient under different X and φ, the γ value is inferred, with a typical range of 0.5~2.0 reflecting the influence of different fiber materials and binder formulations.

[0055] Meanwhile, the sound absorption coefficient of porous materials increases with increasing frequency in the low-frequency range, exhibiting a cutoff frequency below which the sound absorption capacity decreases significantly. This pattern of insufficient low-frequency absorption and near-saturation in high-frequency absorption can be described using the form 1 - e^{-f / f_ref}. When f1 is much greater than fr, the correction coefficient approaches 1; when f1 is much less than fr, the correction coefficient approaches 0. 1000Hz is the most sensitive frequency for A-weighted sound absorption and is also a reference frequency for evaluating the performance of common sound-absorbing materials. By testing the sound absorption coefficient of the same material at different frequencies, δ is obtained through fitting, with typical values ​​of 0.5~1.5 reflecting the material's sensitivity to different frequencies.

[0056] The overlap width w of the felt strip affects the sealing performance and effective sound absorption area of ​​the finished spiral wound tube. If the overlap is too narrow, there is a risk of air leakage and the sound absorption capacity will decrease. If the overlap is too wide, the effective thickness will increase, but there is a risk of excessive compression. In implementation, the overlap width w is determined based on the design overlap width of the felt strip, which is the overlap correction coefficient for the sound absorption coefficient of the felt. Specifically, if the designed overlap width of the current batch of spiral wound tubes is within the overlap width range, the overlap correction factor is 0.70 + 0.10·(w-3); if the designed overlap width of the current batch of spiral wound tubes is lower than the overlap width range, the overlap correction factor is 0.7; if the designed overlap width of the current batch of spiral wound tubes is higher than the overlap width range, the overlap correction factor is 0.9. The overlap width range is [3, 5], and the corrected felt sound absorption coefficient is the product of the felt sound absorption coefficient at the resonant frequency f1 and the overlap correction coefficient.

[0057] Understandably, the overlap width of the felt strips affects two opposing effects: too narrow an overlap leads to air leakage and reduced sound absorption, while too wide an overlap results in excessive compression, reduced porosity, and also reduced sound absorption. 3-5 mm is the optimal range determined by experiments. Within the 3-5 mm range, the correction coefficient increases linearly from 0.70 to 0.90, with the lowest value at w=3 mm, just meeting the sealing requirements, and the highest value at w=5 mm, approaching the optimal range. When w<3 mm, the risk of air leakage dominates, and a worst-case value of 0.7 is fixed. When w>5 mm, excessive compression dominates, and a value of 0.9 is fixed and not increased further, as compression has already begun to degrade performance.

[0058] The expected residual noise is determined based on the corrected sound absorption coefficient of the felt. Expected residual noise = original sound pressure level - 10·log 10 (1 - Corrected sound absorption coefficient of felt); If the expected residual noise is less than or equal to the difference between the target residual noise and the safety margin, then the winding tube with the current winding parameters is predicted to have sufficient sound absorption capacity for the exhaust pipe with the current sound characteristics, and the winding tube meets the standard. If the expected residual noise is greater than the difference between the target residual noise and the safety margin, but less than the target residual noise, then the winding tube with the current winding parameters is predicted to have a critical sound absorption capacity for the exhaust pipe with the current sound characteristics, and the winding tube is at risk of failing to meet the standard. If the expected residual noise is greater than the target residual noise, then the winding tube with the current winding parameters is not good enough for the sound absorption capacity of the exhaust pipe with the current sound characteristics, and the winding tube is not up to standard. The target residual noise is related to the exhaust pipe noise requirements of different vehicle models. In practice, the target residual noise can be selected in the range of 75~90 dB, and the typical range of safety margin is 2~3 dB.

[0059] It is understandable that the expected residual noise formula is the fundamental relationship between sound absorption and sound pressure level attenuation in acoustics: sound pressure level attenuation = 10·log 10 (The ratio of the square of the reflected sound pressure to the incident sound pressure), (1 - the corrected felt absorption coefficient) is the ratio of the reflected sound energy to the incident sound energy. Sound energy is proportional to the square of the sound pressure, so the ratio of the effective value of the reflected sound pressure to the square of the effective value of the incident sound pressure is (1 - the corrected felt absorption coefficient). Since the sound pressure level attenuation is negative, it is usually written as subtraction.

[0060] Specifically, this invention establishes a quantitative correlation model between the geometric parameters of the air intake tube and the original noise, and integrates the sound absorption coefficient prediction of multiple factors such as felt porosity, airflow resistance rate, and overlap structure to achieve batch-level pre-evaluation of the noise reduction capability of the wound tube. Based on the comparison between the expected residual noise and the target value, the sound absorption effect is divided into three levels: sufficient, critical, and insufficient. This allows for the prediction of the noise reduction risk under the current batch matching of felt and air intake tube before or during the winding process, avoiding the lag of traditional methods that require waiting until the finished product is made to verify the noise reduction effect. The prediction method provides a quantitative decision-making basis for process adjustments such as overlap width and winding parameters, effectively reducing the defect rate and improving the acoustic controllability of wound tube design and production.

[0061] There is a risk of non-compliance with standards for wound tubes. The process fluctuation of the winding process is determined based on the winding conditions of polyester filaments, and the compliance risk level of the wound tubes is assessed based on the process fluctuation. Specifically, the impact of process fluctuations in the winding process on the sound absorption capacity of the finished wound tube is determined based on the pressure fluctuation coefficient and the circumferential non-uniformity determined by the polyester filament winding process. The fluctuation range of the corrected felt sound absorption coefficient = corrected felt sound absorption coefficient · (first sensitivity coefficient · pressure fluctuation coefficient + second sensitivity coefficient · circumferential non-uniformity), where the first sensitivity coefficient and the second sensitivity coefficient are experimentally calibrated by testing the influence of pressure fluctuation coefficient and circumferential non-uniformity on the felt sound absorption coefficient, respectively. The typical value of the first sensitivity coefficient is 0.5, and the typical value of the second sensitivity coefficient is 0.3.

[0062] It is understandable that process fluctuations fall into two categories: tension fluctuations and circumferential unevenness. The effects of these two on the sound absorption coefficient are independent, hence they are linearly superimposed. The first and second sensitivity coefficients were calibrated experimentally. Under the same material batch, the pressure fluctuation coefficient and circumferential unevenness were changed separately, and the changes in the sensitivity coefficients were measured. The fitting yielded a first sensitivity coefficient ≈ 0.5 and a second sensitivity coefficient ≈ 0.3. The first sensitivity coefficient > the second sensitivity coefficient indicates that tension fluctuations have a greater impact on sound absorption than circumferential unevenness. Simultaneously, the fluctuation amplitude is proportional to the current sound absorption coefficient value, because the higher the sound absorption coefficient, the greater the absolute fluctuation amplitude caused by the same process fluctuation.

[0063] The uncertainty range of the felt sound absorption coefficient is determined based on the fluctuation range of the felt sound absorption coefficient. The lower limit of the uncertainty range is max(0, corrected felt sound absorption coefficient - fluctuation range of felt sound absorption coefficient), and the upper limit of the uncertainty range is min(1, corrected felt sound absorption coefficient + fluctuation range of felt sound absorption coefficient). The worst-case residual noise is determined based on the uncertainty range of the felt absorption coefficient. Worst-case residual noise = original sound pressure level - 10·log10 (1 - lower limit of the uncertainty interval); If the worst-case residual noise is less than or equal to the target residual noise, then the compliance risk of the wound tube is judged to be at a low risk level. If the worst-case residual noise is greater than the target residual noise, then the risk of non-compliance with standards for the wound tube is judged to be at a medium-risk level.

[0064] The adjustment strategy for the winding parameters of the felt strip is determined based on the compliance risk level and the performance status of the skeleton. The compliance risk is at a medium risk level. Based on the circumferential non-uniformity and the pressure fluctuation coefficient, the process fluctuation of the winding device is determined, and it is determined whether to adjust the design overlap width of the felt strip winding process. When the pressure fluctuation coefficient is greater than the fluctuation threshold, it is determined that the tension in the winding process is unstable. The detection cycle of tension control is reduced according to the ratio of the pressure fluctuation coefficient to the fluctuation threshold. When the circumferential non-uniformity is greater than the uniformity threshold, it is determined that the circumferential pressure in the winding process is uneven, and the detection cycle of the coaxiality between the mandrel and the rotation axis is reduced according to the ratio of the circumferential non-uniformity to the uniformity threshold. When the skeleton performance meets the standard, adjust the design overlap width of the felt strip winding process. In practice, the adjustable range of the design overlap width is 3~5 mm. Increase the design overlap width in standard units. The upper limit of the design overlap width is less than or equal to the upper limit of the adjustable range. After adjusting the overlap width, determine the corresponding overlap correction coefficient. The corresponding overlap correction coefficient after adjustment is 0.70 + 0.10 * (adjusted overlap width - 3). If the adjusted felt sound absorption coefficient corresponding to the adjusted overlap correction coefficient is less than or equal to the target residual noise, it is determined that the adjusted overlap width can meet the exhaust pipe sound absorption capacity requirements of the wound tube for the current sound characteristics, and the design overlap width is determined to be the adjusted overlap width. If the adjusted overlap correction coefficient reaches the upper limit of the design overlap width, and the corresponding corrected felt sound absorption coefficient is greater than the target residual noise, then it is determined that the adjusted overlap width does not meet the exhaust pipe sound absorption capacity requirements of the wound tube for the current sound characteristics, and the adjustment direction of the design winding angle is determined according to the skeleton state index. Specifically, when the skeleton state index is less than the first index threshold, it is determined that the radial support potential is insufficient, the felt is over-compressed, and the design winding angle is increased. When the skeleton state index is greater than the second index threshold, it is determined that the radial support potential is too large, the felt pores are squeezed, and the design winding angle is reduced.

[0065] In practice, the adjustment range of the winding angle is ±2°, where the standard unit is 1mm.

[0066] Specifically, the structural geometry of the pipeline is similar to that of musical instruments, resulting in different noise levels and frequencies. While the sound-absorbing capacity of the felt strips that make up the wound tube is fixed, the sound-absorbing degree of the finished wound tube is affected by the winding parameters. Therefore, based on the batch characteristics of the air intake tube, the predicted noise level range, the predicted sound-absorbing capacity of the finished product based on the current winding parameters and batch characteristics of the felt strips, and the fluctuation range of the sound-absorbing capacity determined by the device fluctuation correction based on the polyester filament winding, the risk that the sound absorption and noise reduction capacity of the finished product may not meet the required range is determined. This invention introduces a pressure fluctuation coefficient and a circumferential non-circular... The method uniformly measures the fluctuations in the winding process and assesses the uncertainty range of the felt sound absorption coefficient and the residual noise in the worst case, classifying the compliance risk into low-risk and medium-risk levels. For the medium-risk level, it further distinguishes different working conditions such as process fluctuation as the main factor, and whether the skeleton performance meets the standard or is abnormal, and formulates graded adjustment strategies such as reducing the detection cycle, adjusting the overlap width, or adjusting the winding angle. This achieves closed-loop control from risk identification to parameter correction, avoids blind adjustment, and ensures that the sound absorption and noise reduction capabilities of the finished product can still be effectively controlled under process fluctuation conditions, significantly improving the robustness and batch consistency of the acoustic performance of the wound tube.

[0067] The average sound absorption coefficient of the current batch of finished spiral wound tubes is obtained as the actual sound absorption coefficient. The actual coefficient deviation between the actual sound absorption coefficient and the expected sound absorption coefficient of the felt is determined. Actual coefficient deviation = actual sound absorption coefficient of finished spiral wound tube - expected sound absorption coefficient of felt. If the actual coefficient deviation is higher than the allowable deviation range, it is determined that the actual sound absorption effect of the finished product exceeds expectations, and the threshold range of the first index threshold and the second index threshold is increased according to the actual coefficient deviation. If the actual coefficient deviation is lower than the allowable deviation range, it is determined that the actual sound absorption effect of the finished product is lower than expected, and the threshold range of the first index threshold and the second index threshold is adjusted down according to the actual coefficient deviation. In practice, the threshold adjustment amount of the threshold range = adjustment coefficient × actual coefficient deviation. The adjustment coefficient is 0.5, that is, for every 0.05 deviation, the threshold range is adjusted by 0.025. The adjustment coefficient determines the response strength to the deviation. If it is greater than 0.5, the adjustment change is too large, which causes a sudden change in the judgment standard of adjacent batches, resulting in process instability. If it is less than 0.5, more batches are needed to correct the deviation, resulting in a delayed response.

[0068] The allowable deviation range is (-0.05, 0.05). Since the sound absorption coefficient measurement itself has repeatability error, an excessively small allowable range will lead to frequent threshold adjustments and system oscillations. Moreover, the minimum sound pressure level change that the human ear can distinguish under steady-state noise conditions is about 0.5 dB. The allowable deviation range defines the unadjustable zone between the actual sound absorption coefficient and the expected sound absorption coefficient.

[0069] Specifically, this invention establishes a threshold closed-loop feedback mechanism based on actual sound absorption effect by collecting the actual sound absorption coefficient of the finished wound tube and comparing it with the expected sound absorption coefficient. When the actual sound absorption effect is better than expected, the threshold range of the skeleton state index is appropriately widened to avoid efficiency loss caused by over-adjustment. When the actual sound absorption effect is lower than expected, the threshold range is tightened accordingly to improve the skeleton performance screening standard. Through adaptive adjustment, the judgment criterion of the skeleton state index can be continuously optimized according to the actual acoustic performance of the batch, which solves the limitation that a fixed threshold is difficult to adapt to different felt batches and air tube models, and realizes intelligent iteration of the winding process and precise control of acoustic performance.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An intelligent winding method for bending and winding tubes, characterized in that, include: Polyester filaments are spirally and crosswise wrapped around the surface of the core mold to form a polyester filament skeleton, and felt strips are attached and overlapped to wrap the polyester filament skeleton. The radial pressure average value is obtained based on the radial pressure borne by the mandrel during polyester filament winding. The skeleton state index is determined based on the radial pressure average value and the winding angle of the polyester filament to determine the performance state of the polyester filament skeleton. Based on the geometric parameters of the air intake tube, the inherent sound emission characteristics of the current batch of air intake tubes are obtained, the original sound pressure level at the main resonant frequency is determined, and the felt porosity and airflow resistance of the felt are obtained to determine the felt sound absorption coefficient. The overlap correction coefficient is determined based on the design overlap width of the felt strip, and the corrected felt sound absorption coefficient is determined in combination with the main resonant frequency. The expected residual noise is determined based on the corrected felt sound absorption coefficient and the original sound pressure level, and the sound absorption capacity of the wound tube with the current winding parameters for the exhaust pipe with the current sound characteristics is predicted. In response to the sound absorption capacity, the pressure fluctuation coefficient and circumferential non-uniformity of the polyester filament winding process are obtained to determine the fluctuation range of the felt sound absorption coefficient. Based on the fluctuation range, the uncertainty range of the felt sound absorption coefficient is determined to combine with the original sound pressure level to determine the worst-case residual noise assessment of the compliance risk level of the winding tube. Based on the compliance risk level, combined with the circumferential non-uniformity and the pressure fluctuation coefficient, the detection cycle is adjusted to determine whether to adjust the design overlap width of the felt strip winding process and to determine the adjustment direction of the design winding angle according to the skeleton state index. Obtain the actual sound absorption coefficient of the current batch of finished spiral tubes to determine the actual coefficient deviation, and adjust the threshold range of the skeleton state index based on the actual coefficient deviation.

2. The intelligent winding method for bent and wound tubes according to claim 1, characterized in that, The process of determining the performance state of the polyester filament skeleton includes: When the skeleton state index is greater than or equal to the first index threshold and less than or equal to the second index threshold, the skeleton is determined to be in the first performance state, and the skeleton performance and stability are determined based on the circumferential non-uniformity and the pressure fluctuation coefficient. When the skeleton state index is less than the first index threshold, the skeleton is judged to be in the second performance state, with insufficient radial support potential. When the skeleton state index is greater than the second index threshold, the skeleton is judged to be in the third performance state, indicating that the radial support potential is too large.

3. The intelligent winding method for bent and wound tubes according to claim 2, characterized in that, The circumferential non-uniformity is determined based on the circumferential pressure distribution of the mandrel during polyester filament winding, and the pressure fluctuation coefficient is determined based on the radial standard deviation and radial pressure mean of the radial pressure borne by the mandrel per unit time. If the circumferential non-uniformity is less than the uniformity threshold and the pressure fluctuation coefficient is less than the fluctuation threshold, it is judged that the skeleton performance meets the standard and is uniform and stable. The radial clamping force and the winding angle are well matched. The circumferential pressure distribution of the skeleton is uniform, the instantaneous pressure is stable, and there are no abnormal fluctuations. Then the felt strip winding process can be carried out.

4. The intelligent winding method for bent and wound tubes according to claim 3, characterized in that, The geometric parameters of the air intake tube include the cavity length, cavity diameter, and tube wall thickness of the air intake tube in the current batch. The main resonant frequency is determined based on the geometric parameters of the air intake tube in the current batch. The sound absorption coefficient of the felt is determined based on the main resonant frequency. The overlap correction coefficient of the felt is determined based on the designed overlap width of the felt strip. The corrected sound absorption coefficient of the felt is then determined based on the overlap correction coefficient.

5. The intelligent winding method for bent and wound tubes according to claim 4, characterized in that, The expected residual noise is determined based on the corrected felt absorption coefficient. If the expected residual noise is less than or equal to the difference between the target residual noise and the safety margin, then the winding tube with the current winding parameters is predicted to have sufficient sound absorption capacity for the exhaust pipe with the current sound characteristics, and the winding tube meets the standard. If the expected residual noise is greater than the difference between the target residual noise and the safety margin, but less than the target residual noise, then the winding tube with the current winding parameters is predicted to have a critical sound absorption capacity for the exhaust pipe with the current sound characteristics, and the winding tube is at risk of failing to meet the standard. If the expected residual noise is greater than the target residual noise, then the winding tube with the predicted current winding parameters is insufficient for the sound absorption capacity of the exhaust pipe with the current sound characteristics, and the winding tube does not meet the standard.

6. The intelligent winding method for bent and wound tubes according to claim 5, characterized in that, The uncertainty range of the sound absorption coefficient of the felt in the finished winding tube is determined based on the pressure fluctuation coefficient and the circumferential non-uniformity determined by the polyester filament winding process. The worst-case residual noise is determined based on the lower limit of the uncertainty range of the sound absorption coefficient of the felt. If the worst-case residual noise is less than or equal to the target residual noise, the compliance risk of the wound tube is judged to be at a low risk level. If the worst-case residual noise is greater than the target residual noise, then the risk of non-compliance with standards for the wound tube is judged to be at a medium-risk level.

7. The intelligent winding method for bent and wound tubes according to claim 6, characterized in that, The risk of failing to meet the standard is at a medium risk level, and the detection cycle is adjusted based on the circumferential non-uniformity and the pressure fluctuation coefficient. When the pressure fluctuation coefficient is greater than the fluctuation threshold, it is determined that the tension in the winding process is unstable. The detection cycle of tension control is reduced according to the ratio of the pressure fluctuation coefficient to the fluctuation threshold. When the circumferential non-uniformity is greater than the uniformity threshold, it is determined that the circumferential pressure in the winding process is uneven. Based on the ratio of the circumferential non-uniformity to the uniformity threshold, the detection cycle of the coaxiality between the mandrel and the rotation axis is reduced.

8. The intelligent winding method for bent and wound tubes according to claim 7, characterized in that, When the skeleton performance meets the standard, adjust the design overlap width of the felt strip winding process, and after adjusting the overlap width, determine the corresponding overlap correction coefficient. If the adjusted felt sound absorption coefficient corresponding to the adjusted overlap correction coefficient is less than or equal to the target residual noise, it is determined that the adjusted overlap width can meet the exhaust pipe sound absorption capacity requirements of the wound tube for the current sound characteristics, and the design overlap width is determined to be the adjusted overlap width. If the adjusted overlap correction coefficient reaches the upper limit of the designed overlap width, and the corresponding corrected felt sound absorption coefficient is greater than the target residual noise, then it is determined that the adjusted overlap width does not meet the exhaust pipe sound absorption capacity requirements of the wound tube for the current sound characteristics, and the adjustment direction of the designed winding angle is determined according to the skeleton state index.

9. The intelligent winding method for bent and wound tubes according to claim 8, characterized in that, When the skeleton state index is less than the first index threshold, it is determined that the radial support potential is insufficient, and the design winding angle is increased. When the skeleton state index is greater than the second index threshold, it is determined that the radial support potential is too large, and the design winding angle is reduced.

10. The intelligent winding method for bent and wound tubes according to claim 9, characterized in that, The process of adjusting the threshold range of the skeleton state index includes: The average sound absorption coefficient of the current batch of finished spiral wound tubes is obtained as the actual sound absorption coefficient, and the actual coefficient deviation between the actual sound absorption coefficient and the expected sound absorption coefficient of the felt is determined. If the actual coefficient deviation is higher than the allowable deviation range, it is determined that the actual sound absorption effect of the finished product exceeds expectations, and the threshold range of the first index threshold and the second index threshold is increased according to the actual coefficient deviation. If the actual coefficient deviation is lower than the allowable deviation range, it is determined that the actual sound absorption effect of the finished product is lower than expected, and the threshold range of the first index threshold and the second index threshold is adjusted down according to the actual coefficient deviation.

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