Manufacturing method of heat-shrinkable sleeve

Abstract

The invention relates to the technical field of sleeve preparation, in particular to a manufacturing method of a heat-shrinkable sleeve, which comprises the following steps: determining whether a to-be-expanded sleeve sample is wrinkled or not in the expansion process based on a wrinkle state evaluation value; extracting the fold characteristics of the fold area of the to-be-expanded casing sample in the expansion process, determining whether the expansion uniformity of the to-be-expanded casing sample reaches the standard or not based on the fold generation characterization parameter, and determining and adjusting the expansion temperature or expansion pressure of the to-be-expanded casing according to the difference value; determining whether the thermal stability of the to-be-expanded casing sample in the expansion process is qualified or not based on the heat distribution value of the wrinkled area, and determining and adjusting the hot air blowing speed of the to-be-expanded casing according to the relative difference; determining whether the expansion stability of the to-be-expanded casing sample reaches the standard or not based on the fold rebound coefficient, and determining and adjusting the expansion time of the to-be-expanded casing according to the ratio; and obtaining the target heat-shrinkable sleeve under the condition of determining that the to-be-expanded sleeve does not have wrinkles in the expansion process. According to the invention, the manufacturing efficiency of the heat-shrinkable sleeve is improved.

Description

Technical Field

[0001] This invention relates to the field of sleeve manufacturing technology, and in particular to a method for manufacturing a heat shrinkable sleeve. Background Technology

[0002] Heat shrink tubing is a polymer material product that shrinks radially upon heating. It is widely used in wire harness insulation, sealing, corrosion protection, and marking in fields such as power, communications, automotive, and aerospace. The expansion process is the core step that determines the final size, performance, and quality of the heat shrink tubing. This process involves heating the cross-linked base tube to an elastic state, applying internal pressure to cause radial expansion, and then cooling and shaping it to achieve heat shrinkability. However, during the expansion process, due to various complex factors such as uneven heating of the material and unbalanced internal stress distribution, the tube wall is prone to buckling instability, forming wrinkles. The presence of these wrinkles directly affects the appearance quality and dimensional uniformity of the product, leading to uneven wall thickness. As stress concentration points, wrinkles significantly degrade the mechanical strength and long-term service life of the tubing. Currently, the control of the expansion process generally relies on the experience and judgment of operators, making it impossible to quantitatively and accurately assess wrinkles and achieve real-time quality monitoring during production. When quality problems are discovered, a large number of defective products have often already been produced, resulting in a waste of raw materials and energy.

[0003] Chinese Patent Application Publication No. CN112391037A discloses a method for preparing easily shrinkable PET tubing material for batteries and capacitors. The easily shrinkable PET tubing material comprises the following components and their mass percentages: PET 30%~60%, PETG 25%~45%, PBT 7%~12%, SEBS 3%~8%, antioxidant 0.1%-3%, and chain extender 0.1%-2%, with the sum of the mass percentages of the above components being 100%. The PET heat-shrink tubing material using the technical solution of this invention possesses excellent mechanical strength and toughness. Most notably, it can shrink very quickly and completely during the shrinking process. Especially when shrunk on imported automatic battery tubing machines, it exhibits very few wrinkles and meets the operating speed requirement of over 200 units per minute, significantly outperforming ordinary PET heat-shrink tubing used in ordinary capacitors and domestically produced battery tubing machines.

[0004] However, the existing technology has the following problems: relying on specific material formulations to make the material itself more wrinkle-resistant cannot solve the problem of wrinkles caused by improper parameter settings or disturbances during the expansion process, resulting in low manufacturing efficiency of heat shrink tubing. Summary of the Invention

[0005] Therefore, the present invention provides a method for manufacturing heat shrink tubing to overcome the problem that the existing technology relies on a specific material formula to make the material itself more wrinkle-resistant, but cannot solve the problem of wrinkles caused by improper parameter settings or disturbances during the expansion process, resulting in low manufacturing efficiency of heat shrink tubing.

[0006] To achieve the above objectives, the present invention provides a method for manufacturing a heat shrink tubing, comprising: The material is heated to a preset temperature, extruded and then cross-linked by irradiation to obtain the tube sample to be expanded; The expansion device is used to expand the sleeve sample under preset expansion parameters, and the surface image of the sleeve sample to be expanded is acquired in real time through an image acquisition device. Based on the surface image, a wrinkle status evaluation value is determined to determine whether wrinkles appear in the sleeve sample to be expanded during the expansion process; Extract the wrinkle features of the wrinkled area of ​​the folded area of ​​the folded tube sample during the expansion process, determine the wrinkle generation characterization parameters based on the wrinkle features, determine whether the expansion uniformity of the folded tube sample meets the standard, and determine the expansion temperature or expansion pressure of the folded tube to be expanded based on the difference between the wrinkle generation characterization parameters and the preset wrinkle generation characterization parameters. Infrared images of the folded region are acquired, and the heat distribution value of the folded region is determined based on the infrared images and the folded features to determine whether the thermal stability of the sleeve sample to be expanded is qualified during the expansion process. The hot air blowing speed of the sleeve to be expanded is adjusted according to the relative difference between the heat distribution value of the folded region and the preset heat distribution value of the folded region. The wrinkle rebound coefficient is determined based on the wrinkle characteristics of the completed expansion tube sample and the tube sample during the expansion process, so as to determine whether the expansion stability of the tube sample to be expanded meets the standard, and the expansion time of the tube to be expanded is adjusted according to the ratio of the preset wrinkle rebound coefficient to the wrinkle rebound coefficient. The target heat shrink tubing is obtained after confirming that no wrinkles appear in the tubing to be expanded during the expansion process.

[0007] Furthermore, the appearance of wrinkles in the cannula sample during expansion is determined based on a comparison of the wrinkle state evaluation value with a preset wrinkle state evaluation value, wherein... The wrinkle state evaluation value is determined based on the actual length of the edge contour, the straight-line distance between the two ends of the contour, the number of edges, and the gradient magnitude.

[0008] Furthermore, the non-compliance of the expansion uniformity of the cannula sample is determined based on the comparison results of the wrinkle generation characterization parameter being greater than the preset wrinkle generation characterization parameter, wherein, The wrinkle generation characterization parameters are determined based on the total area of ​​the wrinkled region, the total area of ​​the casing surface, and the wrinkle depth.

[0009] Furthermore, the process of adjusting the expansion temperature of the sleeve to be expanded includes: Calculate the difference between the wrinkle generation characterization parameter and the preset wrinkle generation characterization parameter under the condition that the expansion uniformity of the tube sample is not up to standard. The expansion temperature is increased based on the comparison results where the difference is less than or equal to a preset difference. The increased expansion temperature is determined based on the expansion temperature and the preset expansion temperature adjustment coefficient.

[0010] Furthermore, the process of adjusting the expansion pressure of the sleeve to be expanded includes: Calculate the difference between the wrinkle generation characterization parameter and the preset wrinkle generation characterization parameter under the condition that the expansion uniformity of the tube sample is not up to standard. Based on the comparison results where the difference is greater than a preset difference, the expansion pressure is increased; The increased expansion pressure is determined based on the expansion pressure and the preset expansion pressure adjustment coefficient.

[0011] Furthermore, the failure of the thermal stability of the tube sample to be expanded during the expansion process is determined based on a comparison result showing that the heat distribution value of the wrinkled region is greater than a preset heat distribution value of the wrinkled region. The heat distribution value of the folded region is determined based on the highest temperature, lowest temperature, average temperature of the folded region, and the average depth of the folded region.

[0012] Furthermore, the process of adjusting the hot air purging speed of the sleeve to be expanded includes: Calculate the relative difference between the thermal distribution value of the wrinkled region and the preset thermal distribution value of the wrinkled region of the sample to be expanded under the condition of unqualified thermal stability during the expansion process. Based on the comparison results where the relative difference is less than or equal to the preset relative difference, the hot air blowing speed is increased by the first preset blowing speed adjustment coefficient. Based on the comparison result that the relative difference is greater than the preset relative difference, the hot air blowing speed is increased by the second preset blowing speed adjustment coefficient.

[0013] Furthermore, the failure of the expansion stability of the sample to be expanded is determined based on the comparison result that the wrinkle rebound coefficient is greater than the preset wrinkle rebound coefficient.

[0014] Furthermore, the wrinkle resilience coefficient is the ratio of the absolute value of the difference between the total number of wrinkles in the expanded sleeve sample and the total number of wrinkles in the sleeve sample during the expansion process to the total number of wrinkles in the sleeve sample during the expansion process.

[0015] Furthermore, the process of adjusting the expansion time of the cannula to be expanded includes: Calculate the ratio of the preset wrinkle springback coefficient to the wrinkle springback coefficient under the condition that the expansion stability of the cannula sample does not meet the standard. Based on the comparison results where the ratio is less than or equal to a preset ratio, the expansion time is increased by a first preset expansion time adjustment coefficient. Based on the comparison results where the ratio is greater than a preset ratio, the expansion time is increased by a second preset expansion time adjustment coefficient.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention determines whether wrinkles appear in the expansion process of the heat shrink tubing sample by using the wrinkle state evaluation value. When wrinkles exist, it determines whether the expansion uniformity of the heat shrink tubing sample meets the standard based on the wrinkle generation characterization parameter. If it does not meet the standard, it adjusts the expansion temperature or expansion pressure of the next batch of heat shrink tubing. It determines whether the thermal stability of the heat shrink tubing sample meets the standard during the expansion process based on the heat distribution value of the wrinkle area. If it does not meet the standard, it adjusts the hot air purging speed of the heat shrink tubing. It determines whether the expansion stability of the heat shrink tubing sample meets the standard based on the wrinkle rebound coefficient. If it does not meet the standard, it adjusts the expansion time of the heat shrink tubing. This allows the process parameters to be matched with the material properties in real time, improving the accuracy of the heat shrink tubing expansion process. The wrinkle generation characterization parameter quantifies the uniformity of the expansion process, thereby improving the manufacturing efficiency of heat shrink tubing.

[0017] Furthermore, this invention determines whether wrinkles appear in the expansion process of the tubing sample by using a wrinkle state evaluation value, which improves the accuracy of detecting minute wrinkles and reduces the missed detection rate. It quantifies the coverage of wrinkles based on wrinkle generation characterization parameters, avoids uneven shrinkage caused by local dense wrinkles and prevents sealing failure caused by deep wrinkles, reduces the deviation of the circumferential shrinkage rate of the heat shrink tubing, and thus improves the manufacturing efficiency of the heat shrink tubing.

[0018] Furthermore, this invention determines the thermal stability of the sleeve sample during the expansion process by using the heat distribution value of the folded area. If the thermal stability is unqualified, the hot air purging speed is dynamically increased. The temperature distribution coefficient reflects the temperature uniformity of the folded area, avoiding molecular chain breakage caused by local overheating. The morphology coefficient, combined with the spatial distribution and severity of the folds, prevents local high temperatures caused by poor heat dissipation in deep folds, thereby avoiding molecular chain degradation caused by local overheating or insufficient cross-linking caused by underheating. Precise hot air purging control can suppress thermal stress concentration caused by uneven temperature during the expansion process and reduce the surface roughness value of the sleeve.

[0019] Furthermore, this invention judges the expansion stability by comparing the percentage difference in the number of folds between the completed expansion sleeve and the sleeve during expansion. If the stability does not meet the standard, the expansion time is dynamically extended. The expansion stability is evaluated based on the fold rebound coefficient, which improves the control precision, ensures the consistency of the heat shrink sleeve size, and precisely extends the expansion time to promote the full relaxation of the molecular chain, reduce the internal stress caused by rebound, reduce the inner diameter deviation after the sleeve shrinks, and improve the fit with the protected part. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the manufacturing method of the heat shrink tubing according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating how to determine whether wrinkles appear in the expansion sample of the cannula during the expansion process, as described in this embodiment of the invention. Figure 3 This is a flowchart illustrating how to determine whether the expansion uniformity of a cannula sample meets the standard, as described in an embodiment of the present invention. Figure 4 This is a flowchart for determining whether the thermal stability of the sleeve sample to be expanded is qualified during the expansion process, as described in an embodiment of the present invention. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] It should be noted that the data in this embodiment are all derived from a comprehensive analysis and evaluation of historical test data and corresponding historical test results from the three months prior to this test. Those skilled in the art will understand that the determination of the above-mentioned parameters for any single item in this invention can be achieved by selecting the value with the highest percentage based on the data distribution as the preset standard parameter, using weighted summation to obtain the value as the preset standard parameter, substituting each historical data point into a specific formula and using the value obtained from that formula as the preset standard parameter, or other selection methods, as long as the invention can clearly define different specific situations in the single-item judgment process through the obtained values.

[0024] See also Figure 1 As shown, it is a flowchart of the manufacturing method of heat shrink tubing according to an embodiment of the present invention.

[0025] The method for manufacturing heat shrink tubing according to an embodiment of the present invention includes: Step S1: The material is heated to a preset temperature, extruded and cross-linked by irradiation to obtain the tube sample to be expanded; Step S2: Expand the sleeve sample to be expanded using an expansion device under preset expansion parameters, and acquire the surface image of the sleeve sample to be expanded in real time through an image acquisition device. Step S3: Determine the wrinkle status evaluation value based on the surface image to determine whether wrinkles appear in the expansion sample of the sleeve to be expanded during the expansion process; Step S4: Extract the wrinkle features of the wrinkled area of ​​the folded area of ​​the folded tube sample during the expansion process, determine the wrinkle generation characterization parameters based on the wrinkle features, determine whether the expansion uniformity of the folded tube sample meets the standard, and determine the expansion temperature or expansion pressure of the folded tube to be expanded based on the difference between the wrinkle generation characterization parameters and the preset wrinkle generation characterization parameters. Step S5: Obtain an infrared image of the wrinkled area, determine the heat distribution value of the wrinkled area based on the infrared image and the wrinkled features, in order to determine whether the thermal stability of the sleeve sample to be expanded is qualified during the expansion process, and determine the hot air blowing speed of the sleeve to be expanded according to the relative difference between the heat distribution value of the wrinkled area and the preset heat distribution value of the wrinkled area. Step S6: Determine the wrinkle rebound coefficient based on the wrinkle characteristics of the completed expansion sleeve sample and the sleeve sample during the expansion process, so as to determine whether the expansion stability of the sleeve sample to be expanded meets the standard, and determine the expansion time of the sleeve to be expanded according to the ratio of the preset wrinkle rebound coefficient to the wrinkle rebound coefficient. Step S7: Obtain the target heat shrink tubing after confirming that no wrinkles appear in the tubing to be expanded during the expansion process.

[0026] Specifically, this invention determines whether wrinkles appear in the expansion process of the heat shrink tubing sample by using a wrinkle state evaluation value. If wrinkles are present, the expansion uniformity of the sample is determined based on the wrinkle generation characterization parameters. If it does not meet the standard, the expansion temperature or pressure of the next batch of tubing is adjusted. The thermal stability of the sample during expansion is determined based on the heat distribution value of the wrinkled area. If it does not meet the standard, the hot air purging speed of the tubing is adjusted. The expansion stability of the sample is determined based on the wrinkle rebound coefficient. If it does not meet the standard, the expansion time is adjusted. This allows the process parameters to match the material properties in real time, improving the accuracy of the heat shrink tubing expansion process. The wrinkle generation characterization parameters quantify the uniformity of the expansion process, thereby improving the manufacturing efficiency of heat shrink tubing.

[0027] In this embodiment of the invention, the material is a polyolefin, the preset temperature is 180-220℃, preferably 200℃, the irradiation crosslinking is carried out by an electron accelerator, the irradiation dose is 10-30kGy, preferably 20kGy, the material is not specifically limited, and is selected according to the actual application scenario.

[0028] Specifically, in this embodiment of the invention, an expansion device is used to expand the sheath sample to be expanded under preset expansion parameters, and an image acquisition device is used to acquire surface images of the sheath sample to be expanded in real time during the expansion process. In this embodiment of the invention, the preset expansion parameters include an expansion temperature of 100-130℃, preferably 115℃, an expansion pressure of 0.1-0.3MPa, preferably 0.2MPa, an expansion time of 40-60s, preferably 50s, a hot air blowing speed of 5-15m / s, preferably 10m / s, and the image acquisition device is an industrial camera.

[0029] See also Figure 2 As shown, it is a flowchart of an embodiment of the present invention for determining whether wrinkles appear in the expansion process of the sleeve sample to be expanded.

[0030] Specifically, in this embodiment of the invention, under the condition that a surface image of the sample to be expanded is obtained, the wrinkle state evaluation value determined by the surface image is compared with the preset wrinkle state evaluation value to determine whether wrinkles appear in the sample to be expanded during the expansion process. When the wrinkle state evaluation value is less than or equal to the preset wrinkle state evaluation value, it is determined that no wrinkles appeared in the expansion process of the sleeve sample. When the wrinkle state evaluation value is greater than the preset wrinkle state evaluation value, it is determined that wrinkles have appeared in the tube sample to be expanded during the expansion process.

[0031] In this embodiment of the invention, the preset wrinkle state evaluation value ranges from [0.05, 0.15], preferably 0.1, but the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0032] In this embodiment of the invention, the process of obtaining the wrinkle state evaluation value is as follows: the surface image is grayscaled and denoised to obtain a grayscale image; the inter-class variance of the grayscale image is calculated using the OTSU threshold segmentation algorithm, and the grayscale value with the largest variance is selected as the threshold. Regions with pixel values ​​greater than or equal to the threshold are marked as sleeve regions, and regions with pixel values ​​less than the threshold are marked as background regions; the Canny algorithm is used to extract the contours of the sleeve region edges with a continuous length greater than or equal to 10 pixels, and the ratio of the sum of the ratios of the actual length of several edge contours to the straight-line distance between the two endpoints of the contours to the number of edges is recorded as the edge irregularity; the gradient magnitude of each pixel in the sleeve region is calculated using the Sobel operator; the ratio of the standard deviation to the mean of the gradient magnitude of the sleeve region is recorded as the grayscale gradient variation coefficient; the wrinkle state evaluation value is the product of the wrinkle state evaluation value and a weight of 0.5 plus the product of the grayscale gradient variation coefficient and a weight of 0.5.

[0033] Specifically, in this embodiment of the invention, the area where wrinkles appear in the expansion sample of the cannula to be expanded is marked as a wrinkled area, and the wrinkle features of the wrinkled area are extracted. The wrinkle features include the width, depth, number and area of ​​the wrinkles.

[0034] See also Figure 3 As shown, it is a flowchart of an embodiment of the present invention for determining whether the expansion uniformity of the sleeve sample meets the standard.

[0035] Specifically, in this embodiment of the invention, the wrinkle features of the wrinkled area of ​​the folded region of the folded tube sample to be expanded are extracted, and the expansion uniformity of the folded tube sample is determined based on the comparison result between the wrinkle generation characterization parameter determined by the wrinkle features and the preset wrinkle generation characterization parameter. When the wrinkle generation characterization parameter is less than or equal to the preset wrinkle generation characterization parameter, it is determined that the expansion uniformity of the sleeve sample to be expanded meets the standard. When the wrinkle generation characterization parameter is greater than the preset wrinkle generation characterization parameter, it is determined that the expansion uniformity of the tube sample to be expanded does not meet the standard.

[0036] In this embodiment of the invention, the preset range of the wrinkle generation characterization parameter is [0.1, 0.2], preferably 0.15, but the above value is not limited to this, and those skilled in the art can also adjust the value according to actual needs.

[0037] In this embodiment of the invention, the process of obtaining the wrinkle generation characterization parameter is as follows: the ratio of the total area of ​​the wrinkle region to the total area of ​​the sleeve surface is obtained through image segmentation, which is denoted as the wrinkle distribution density; the ratio of the standard deviation of the wrinkle depth of all extracted wrinkles to the average wrinkle depth is denoted as the wrinkle distribution depth; the product of the wrinkle distribution density and a weight of 0.6 is added to the product of the wrinkle distribution depth and a weight of 0.4, which is denoted as the wrinkle generation characterization parameter.

[0038] Specifically, in this embodiment of the invention, when it is determined that the expansion uniformity of the sleeve sample to be expanded is not up to standard, the expansion temperature or expansion pressure of the sleeve to be expanded is determined by comparing the difference between the wrinkle generation characterization parameter and the preset wrinkle generation characterization parameter with the preset difference. When the difference is less than or equal to the preset difference, it is determined that the expansion temperature will be increased to the corresponding value by a preset expansion temperature adjustment coefficient of 1.1. When the difference is greater than the preset difference, it is determined that the expansion pressure will be increased to the corresponding value by a preset expansion pressure adjustment coefficient of 1.2. Wherein, the difference is the difference between the wrinkle generation characterization parameter and the preset wrinkle generation characterization parameter.

[0039] In this embodiment of the invention, the preset difference value range is [0.05, 0.09], preferably 0.07, but the above value is not limited to this, and those skilled in the art can also adjust the value according to actual needs.

[0040] In this embodiment of the invention, the increased expansion temperature is the product of the expansion temperature and the preset expansion temperature adjustment coefficient, with the preset expansion temperature adjustment coefficient being 1.1. The increased expansion pressure is the product of the expansion pressure and the preset expansion pressure adjustment coefficient, with the preset expansion pressure adjustment coefficient being 1.2. To ensure that the adjusted expansion temperature and expansion pressure adjustment coefficients meet the actual needs, the adjustment range should not be too large, so corresponding adjustment coefficients are set to control the adjustment range.

[0041] Specifically, this invention determines whether wrinkles appear in the expansion process of the tubing sample by using a wrinkle state evaluation value, which improves the accuracy of detecting minute wrinkles and reduces the missed detection rate. It quantifies the coverage of wrinkles based on wrinkle generation characterization parameters, avoids uneven shrinkage caused by local dense wrinkles and prevents sealing failure caused by deep wrinkles, reduces the deviation of the circumferential shrinkage rate of the heat shrink tubing, and thus improves the manufacturing efficiency of the heat shrink tubing.

[0042] See also Figure 4 As shown, it is a flowchart of an embodiment of the present invention for determining whether the thermal stability of the sleeve sample to be expanded is qualified during the expansion process.

[0043] Specifically, in this embodiment of the invention, under the condition that an infrared image of the wrinkled area of ​​the sleeve sample to be expanded is obtained during the expansion process, the thermal stability of the sleeve sample to be expanded during the expansion process is determined based on the comparison result between the thermal distribution value of the wrinkled area determined by the infrared image and the wrinkled features and the preset thermal distribution value of the wrinkled area. When the heat distribution value of the wrinkled area is less than or equal to the preset heat distribution value of the wrinkled area, the thermal stability of the sleeve sample to be expanded is determined to be qualified during the expansion process. When the heat distribution value of the folded area is greater than the preset heat distribution value of the folded area, it is determined that the thermal stability of the sleeve sample to be expanded is unqualified during the expansion process.

[0044] In this embodiment of the invention, the preset range of heat distribution value in the wrinkled area is [0.2, 0.3], preferably 0.25, but the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0045] In this embodiment of the invention, the process of obtaining the heat distribution value of the folded region is as follows: the infrared image is calibrated for temperature, the pixel values ​​are converted into actual temperature values, and the highest temperature, lowest temperature, and average temperature of the folded region are extracted; the ratio of the difference between the highest and lowest temperatures to the average temperature is recorded as the fold temperature distribution coefficient; the ratio of the average depth of the folded region to the maximum fold depth threshold is multiplied by a weight of 0.6 and added to the product of the fold distribution density and a weight of 0.4, and recorded as the fold morphology coefficient, wherein the maximum fold depth threshold is set to 0.3 mm; the product of the fold temperature distribution coefficient and a weight of 0.7 and the product of the fold morphology coefficient and a weight of 0.3 is recorded as the heat distribution value of the folded region.

[0046] Specifically, in this embodiment of the invention, when it is determined that the thermal stability of the sleeve sample to be expanded is unqualified during the expansion process, the hot air purging speed of the sleeve to be expanded is adjusted based on the comparison result of the relative difference between the heat distribution value of the wrinkled area and the preset heat distribution value of the wrinkled area and the preset relative difference. When the relative difference is less than or equal to the preset relative difference, it is determined that the hot air blowing speed will be increased to the corresponding value by the first preset blowing speed adjustment coefficient of 1.15. When the relative difference is greater than the preset relative difference, it is determined that the hot air blowing speed will be increased to the corresponding value by the second preset blowing speed adjustment coefficient of 1.25. The relative difference is the relative difference between the heat distribution value of the folded region and the preset heat distribution value of the folded region.

[0047] In this embodiment of the invention, the preset relative difference range is [0.4, 0.5], preferably 0.45, but the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0048] In this embodiment of the invention, the increased hot air purging speed is the product of the hot air purging speed and the preset purging speed adjustment coefficient. The preset purging speed adjustment coefficient includes a first preset purging speed adjustment coefficient with a value of 1.15 and a second preset purging speed adjustment coefficient with a value of 1.25. In order to ensure that the adjusted hot air purging speed meets the actual needs, the adjustment range should not be too large, so an adjustment coefficient is set to control the adjustment range.

[0049] Specifically, this invention determines the thermal stability of the sleeve sample during the expansion process by measuring the thermal distribution value of the folded area. If the thermal stability is unqualified, the hot air purging speed is dynamically increased. The temperature distribution coefficient reflects the temperature uniformity of the folded area, avoiding molecular chain breakage caused by local overheating. The morphology coefficient, combined with the spatial distribution and severity of the folds, prevents local high temperatures caused by poor heat dissipation in deep folds, thereby avoiding molecular chain degradation caused by local overheating or insufficient cross-linking caused by underheating. Precise hot air purging control can suppress thermal stress concentration caused by uneven temperature during the expansion process and reduce the surface roughness value of the sleeve.

[0050] Specifically, in this embodiment of the invention, the expansion stability of the sleeve sample to be expanded is determined by comparing the wrinkle rebound coefficient determined by the final wrinkle of the expanded sleeve sample with the wrinkle during the expansion process with the preset wrinkle rebound coefficient. When the wrinkle rebound coefficient is less than or equal to the preset wrinkle rebound coefficient, the expansion stability of the tube sample to be expanded is determined to meet the standard. When the wrinkle rebound coefficient is greater than the preset wrinkle rebound coefficient, it is determined that the expansion stability of the sleeve sample to be expanded does not meet the standard.

[0051] In this embodiment of the invention, the preset wrinkle resilience coefficient range is [0.13, 0.23], preferably 0.17, but the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0052] In this embodiment of the invention, the process of obtaining the wrinkle resilience coefficient is the ratio of the absolute value of the difference between the number of all wrinkle contours of the expanded sleeve sample and the number of wrinkles in the sleeve sample during the expansion process to the number of wrinkles in the sleeve sample during the expansion process.

[0053] Specifically, in this embodiment of the invention, when it is determined that the expansion stability of the sample to be expanded is not up to standard, the expansion time of the sample to be expanded is adjusted based on the comparison result of the ratio of the preset wrinkle rebound coefficient to the preset ratio. When the ratio is less than or equal to the preset ratio, it is determined that the expansion time of the sleeve to be expanded will be increased to the corresponding value by using the first preset expansion time adjustment coefficient of 1.05. When the ratio is greater than the preset ratio, it is determined that the expansion time of the sleeve to be expanded will be increased to the corresponding value by the second preset expansion time adjustment coefficient of 1.35. The ratio is the ratio of the preset wrinkle resilience coefficient to the wrinkle resilience coefficient.

[0054] In this embodiment of the invention, the preset ratio range is [0.6, 0.7], preferably 0.65, but the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0055] In this embodiment of the invention, the increased expansion time is the product of the expansion time and the preset expansion time adjustment coefficient. The preset expansion time adjustment coefficient includes a first preset expansion time adjustment coefficient with a value of 1.05 and a second preset expansion time adjustment coefficient with a value of 1.35. In order to ensure that the adjusted expansion time meets the actual needs, the adjustment range should not be too large, so an adjustment coefficient is set to control the adjustment range.

[0056] Specifically, this invention judges the expansion stability by comparing the percentage difference in the number of folds between the completed expansion sleeve and the sleeve during expansion. If the stability does not meet the standard, the expansion time is dynamically extended. The expansion stability is evaluated based on the fold rebound coefficient, which improves the control precision, ensures the consistency of the heat shrink sleeve size, and precisely extends the expansion time to promote the full relaxation of the molecular chain, reduce the internal stress caused by rebound, reduce the deviation of the inner diameter after the sleeve shrinks, and improve the fit with the protected part.

[0057] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing a heat shrink tubing, characterized in that, include: The material is heated to a preset temperature, extruded and then cross-linked by irradiation to obtain the tube sample to be expanded; The expansion device is used to expand the sleeve sample under preset expansion parameters, and the surface image of the sleeve sample to be expanded is acquired in real time through an image acquisition device. Based on the surface image, a wrinkle status evaluation value is determined to determine whether wrinkles appear in the sleeve sample to be expanded during the expansion process; Extract the wrinkle features of the wrinkled area of ​​the folded area of ​​the folded tube sample during the expansion process, determine the wrinkle generation characterization parameters based on the wrinkle features, determine whether the expansion uniformity of the folded tube sample meets the standard, and determine the expansion temperature or expansion pressure of the folded tube to be expanded based on the difference between the wrinkle generation characterization parameters and the preset wrinkle generation characterization parameters. Infrared images of the folded region are acquired, and the heat distribution value of the folded region is determined based on the infrared images and the folded features to determine whether the thermal stability of the sleeve sample to be expanded is qualified during the expansion process. The hot air blowing speed of the sleeve to be expanded is adjusted according to the relative difference between the heat distribution value of the folded region and the preset heat distribution value of the folded region. The wrinkle rebound coefficient is determined based on the wrinkle characteristics of the completed expansion tube sample and the tube sample during the expansion process, so as to determine whether the expansion stability of the tube sample to be expanded meets the standard, and the expansion time of the tube to be expanded is adjusted according to the ratio of the preset wrinkle rebound coefficient to the wrinkle rebound coefficient. The target heat shrink tubing is obtained after confirming that no wrinkles appear in the tubing to be expanded during the expansion process.

2. The method for manufacturing heat shrink tubing according to claim 1, characterized in that, The wrinkles that appear on the cannula sample during expansion are determined based on a comparison of the wrinkle state evaluation value with a preset wrinkle state evaluation value. The wrinkle state evaluation value is determined based on the actual length of the edge contour, the straight-line distance between the two ends of the contour, the number of edges, and the gradient magnitude.

3. The method for manufacturing heat shrink tubing according to claim 2, characterized in that, The failure of the expansion uniformity of the cannula sample to be expanded was determined based on the comparison results of the wrinkle generation characterization parameter being greater than the preset wrinkle generation characterization parameter. The wrinkle generation characterization parameters are determined based on the total area of ​​the wrinkled region, the total area of ​​the casing surface, and the wrinkle depth.

4. The method for manufacturing a heat shrink tubing according to claim 3, characterized in that, The process of adjusting the expansion temperature of the sleeve to be expanded includes: Calculate the difference between the wrinkle generation characterization parameter and the preset wrinkle generation characterization parameter under the condition that the expansion uniformity of the tube sample is not up to standard. The expansion temperature is increased based on the comparison results where the difference is less than or equal to a preset difference. The increased expansion temperature is determined based on the expansion temperature and the preset expansion temperature adjustment coefficient.

5. The method for manufacturing a heat shrink tubing according to claim 4, characterized in that, The process of adjusting the expansion pressure of the sleeve to be expanded includes: Calculate the difference between the wrinkle generation characterization parameter and the preset wrinkle generation characterization parameter under the condition that the expansion uniformity of the tube sample is not up to standard. Based on the comparison results where the difference is greater than a preset difference, the expansion pressure is increased; The increased expansion pressure is determined based on the expansion pressure and the preset expansion pressure adjustment coefficient.

6. The method for manufacturing a heat shrink tubing according to claim 5, characterized in that, The failure of the thermal stability of the tube sample to be expanded during the expansion process was determined based on a comparison result showing that the thermal distribution value of the wrinkled region was greater than the preset thermal distribution value of the wrinkled region. The heat distribution value of the folded region is determined based on the highest temperature, lowest temperature, average temperature of the folded region, and the average depth of the folded region.

7. The method for manufacturing a heat shrink tubing according to claim 6, characterized in that, The process of adjusting the hot air blowing speed of the sleeve to be expanded includes: Calculate the relative difference between the thermal distribution value of the wrinkled region and the preset thermal distribution value of the wrinkled region of the sample to be expanded under the condition of unqualified thermal stability during the expansion process. Based on the comparison results where the relative difference is less than or equal to the preset relative difference, the hot air blowing speed is increased by the first preset blowing speed adjustment coefficient. Based on the comparison result that the relative difference is greater than the preset relative difference, the hot air blowing speed is increased by the second preset blowing speed adjustment coefficient.

8. The method for manufacturing a heat shrink tubing according to claim 7, characterized in that, The failure of the expansion stability of the sample to be expanded was determined based on the comparison result that the wrinkle rebound coefficient was greater than the preset wrinkle rebound coefficient.

9. The method for manufacturing a heat shrink tubing according to claim 8, characterized in that, The wrinkle resilience coefficient is the ratio of the absolute value of the difference between the total number of wrinkles in the expanded casing sample and the total number of wrinkles in the casing sample during the expansion process to the total number of wrinkles in the casing sample during the expansion process.

10. The method for manufacturing a heat shrink tubing according to claim 9, characterized in that, The process of adjusting the expansion time of the sleeve to be expanded includes: Calculate the ratio of the preset wrinkle springback coefficient to the wrinkle springback coefficient under the condition that the expansion stability of the cannula sample does not meet the standard. Based on the comparison results where the ratio is less than or equal to a preset ratio, the expansion time is increased by a first preset expansion time adjustment coefficient. Based on the comparison results where the ratio is greater than a preset ratio, the expansion time is increased by a second preset expansion time adjustment coefficient.

Images