Corrugated carton moisture-proof testing method and corrugated carton moisture-proof testing system

Abstract

The invention relates to the technical field of carton defect analysis, in particular to a corrugated carton moisture-proof testing method and system.The corrugated carton moisture-proof testing method comprises the steps that solutions containing different fluorescent substances are dropwise added to two moisture diffusion points on a paperboard sample synchronously; marking a plurality of paper junction points and determining a fiber water absorption boundary line according to the comparison condition of the fluorescence peaks captured in each sub-region and the neighborhood; judging whether to stop dropwise adding the solution to a wet diffusion point or not by calculating a water absorption performance deviation coefficient of paper surface fibers; and finally, judging whether the water-absorbing moisture-proof performance of the paper surface is qualified or not according to the water-absorbing test value of the paperboard sample. The corrugated carton moisture-proof test system comprises a fluorescence soaking module, an image acquisition module, a fluorescence excitation module, a control module and a test analysis module, and the spatial form difference of water absorption and diffusion of paper surface fibers of a carton is analyzed; the moisture-proof performance of the surface of the carton can be quickly identified and analyzed in the continuous production of the corrugated carton.

Description

Technical Field

[0001] This invention relates to the field of cardboard box defect analysis technology, and in particular to a method and system for testing the moisture resistance of corrugated cardboard boxes. Background Technology

[0002] As a carrier for logistics transportation and product packaging, the moisture-proof performance of corrugated cardboard boxes is crucial to the storage safety and transportation stability of the goods they contain. Especially in humid environments and long-distance transportation, issues such as the uniformity of water absorption by the cardboard fibers can easily lead to damage to the packaging structure. Therefore, accurate testing of the moisture-proof performance of corrugated cardboard boxes is key to packaging quality control. Currently, most moisture-proof testing methods for corrugated cardboard boxes rely on traditional water absorption measurement methods, which struggle to capture the dynamic water absorption and diffusion process of the paper fibers in real time. Traditional testing methods focus only on single quantitative indicators such as total water absorption and penetration rate. In practical applications, the water absorption and diffusion of corrugated cardboard fibers is not uniform. If the diffusion pattern is locally offset or uneven, excessive water absorption may cause a sharp drop in fiber strength, further leading to packaging damage. Traditional methods are insufficient to meet the requirements of high-precision packaging quality control.

[0003] For example, Chinese Patent Publication No. CN119246508A discloses a method and system for monitoring the humidity of a cardboard box. The method includes acquiring color information of the cardboard box surface based on an RGB camera; acquiring temperature distribution information of the cardboard box surface based on an infrared thermal imaging device; acquiring structural change information of the cardboard box surface based on a 3D scanner; inputting the color information, temperature distribution information, and structural change information into a multimodal fusion network for feature-level fusion to obtain a cardboard box humidity feature representation; performing decision fusion based on a temperature change algorithm and the cardboard box humidity feature representation to obtain a cardboard box humidity estimate; determining whether the cardboard box humidity estimate is a preset value; if so, generating a corresponding control action.

[0004] Existing technologies do not consider analyzing the spatial morphological differences in water absorption and diffusion of paper fibers on the carton surface, and cannot quickly identify and analyze the moisture-proof performance of the carton surface during continuous production of corrugated cartons, resulting in a problem of delayed response in defect detection. Summary of the Invention

[0005] To address this, the present invention provides a method and system for testing the moisture resistance of corrugated cardboard boxes, thereby overcoming the problems of existing technologies being unable to analyze the spatial morphological differences in water absorption and diffusion of paper fibers on the cardboard surface, and being unable to quickly identify and analyze the moisture resistance performance of the cardboard box surface during continuous production of corrugated cardboard boxes.

[0006] To achieve the above objectives, the present invention provides a method for testing the moisture resistance of corrugated cardboard boxes, comprising:

[0007] Two moisture diffusion points with a preset spacing were determined on a corrugated cardboard sample, and solutions containing different fluorescent substances were simultaneously added to each moisture diffusion point.

[0008] After a single drop of the solution is added, an image of the region between the wet diffusion points is obtained. Based on the comparison of each sub-region in the region image with the captured fluorescence peaks in the neighboring region, several paper boundary points are marked. Based on the paper boundary points, the fiber water absorption boundary line is determined.

[0009] Obtain the morphological difference information between the fiber water absorption boundary line and the diffusion reference baseline, calculate the water absorption performance deviation coefficient of the paper fiber by weighting each deviation factor in the morphological difference information, and determine whether to stop adding solution to the moisture diffusion point based on the comparison result of the water absorption performance deviation coefficient and the preset threshold.

[0010] In response to the determination result of stopping the addition of solution at the moisture diffusion point, the water absorption test value of the paperboard sample within a preset unit time is calculated, and the water absorption test value is compared with the water absorption calibration value to determine whether the water absorption and moisture-proof performance of the paper surface fibers is qualified.

[0011] Furthermore, the process of determining the fluorescence peak alignment includes:

[0012] Acquire an image of the region between moisture diffusion points, and divide the region image into several sub-regions of equal area;

[0013] Fluorescence signals were acquired for each sub-region, and the characteristic fluorescence peak wavelengths of each sub-region were extracted.

[0014] Taking each sub-region as the central sub-region, the sub-regions that are adjacent to the central sub-region on the left and right along the direction of the line connecting the moisture diffusion points are determined as the neighborhood. The wavelength difference of the characteristic fluorescence peak wavelength between the central sub-region and each sub-region in the neighborhood is calculated.

[0015] Furthermore, the process of marking the boundary points on the paper includes:

[0016] The wavelength difference is compared with the wavelength difference reference value;

[0017] If the wavelength difference is greater than the wavelength difference reference value, then the center point of the central sub-region is marked as the paper boundary point;

[0018] The wavelength difference reference value is determined based on the wavelength difference of the characteristic fluorescence peaks of different fluorescent substances.

[0019] Furthermore, the process of determining the fiber water absorption boundary line is as follows: the curve formed by connecting each paper boundary point one by one along the direction perpendicular to the line connecting the moisture diffusion points is determined as the fiber water absorption boundary line.

[0020] Furthermore, the first deviation factor within the morphological difference information is obtained, including:

[0021] Determine several first boundary-crossing sub-regions and second boundary-crossing sub-regions enclosed on both sides of the diffusion reference baseline by the fiber water absorption boundary line;

[0022] The accumulated area of ​​several first boundary-crossing sub-regions is recorded as the first boundary-crossing area, and the accumulated area of ​​several second boundary-crossing sub-regions is recorded as the second boundary-crossing area.

[0023] The ratio of the difference between the first boundary area and the second boundary area to the preset difference reference value is determined as the first deviation factor;

[0024] The diffusion reference baseline is a straight line perpendicular to the line connecting the two moisture diffusion points and passing through the midpoint of the line connecting the moisture diffusion points.

[0025] Furthermore, the second deviation factor within the morphological difference information is obtained, including:

[0026] Calculate the vertical distance between each paper interface point and the diffusion reference baseline on the fiber water absorption interface line, and determine the ratio of the maximum vertical distance to the preset vertical distance reference value as the second deviation factor.

[0027] Furthermore, the first deviation factor and the second deviation factor are weighted and summed to obtain the deviation coefficient of the water absorption performance of the paper fibers.

[0028] Furthermore, the process of determining whether to stop adding solution to the moisture diffusion point includes:

[0029] If the water absorption performance deviation coefficient is greater than a preset threshold, then it is determined that the solution should be stopped being added to the moisture diffusion point;

[0030] If the water absorption performance deviation coefficient is less than or equal to a preset threshold, it is determined that the solution should continue to be added to the moisture diffusion point.

[0031] Furthermore, the process of determining whether the water absorption and moisture-proof performance of the paper fibers is qualified based on the comparison between the water absorption test value and the water absorption calibration value includes:

[0032] Obtain the cumulative amount of solution added at two moisture diffusion points within the allowable adding period, and determine the cumulative amount of solution added as the water absorption test value;

[0033] If the water absorption test value is less than the water absorption calibration value, the water absorption and moisture-proof performance of the paper fiber is deemed unqualified; if the water absorption test value is greater than or equal to the water absorption calibration value, the water absorption and moisture-proof performance of the paper fiber is deemed qualified.

[0034] Furthermore, the present invention also provides a moisture-proof testing system for corrugated cardboard boxes, comprising:

[0035] The fluorescent wetting module is used to simultaneously drop solutions containing different fluorescent substances onto each wet diffusion point on a cardboard sample;

[0036] An image acquisition module is used to acquire a regional image of the surface of a cardboard sample and divide the regional image into several sub-regions;

[0037] A fluorescence excitation module, which is connected to the image acquisition module, is used to mark several paper boundary points based on the comparison of fluorescence peaks captured in each sub-region and the neighboring region, and to determine the fiber water absorption boundary line based on the paper boundary points.

[0038] The control module is connected to the fluorescent wetting module and the fluorescent excitation module respectively. It is used to calculate the weighted deviation factors in the morphological difference information to obtain the water absorption performance deviation coefficient of the paper fiber, and to determine whether to stop adding solution to the moisture diffusion point based on the comparison result of the water absorption performance deviation coefficient and the preset threshold.

[0039] The test analysis module, which is connected to the control module, is used to calculate the water absorption test value of the paperboard sample within a preset unit time. Based on the comparison between the water absorption test value and the water absorption calibration value, it is determined whether the water absorption and moisture-proof performance of the paper surface fibers is qualified.

[0040] The beneficial effects of the technical solution presented in this application include: firstly, solutions containing different fluorescent substances are simultaneously added to two moisture diffusion points on a cardboard sample; by acquiring regional images between the moisture diffusion points after a single solution addition, several paper surface boundary points are marked and fiber water absorption boundary lines are determined based on the comparison of fluorescence peaks captured in each sub-region and its neighboring region; by acquiring morphological difference information between the fiber water absorption boundary line and the diffusion reference baseline, the water absorption performance deviation coefficient of the paper surface fibers is calculated to determine whether to stop adding solution to the moisture diffusion points; in response to the determination result of stopping the addition of solution to the moisture diffusion points, the water absorption and moisture-proof performance of the paper surface fibers is determined based on the comparison of the water absorption test value and the water absorption calibration value of the cardboard sample within a preset unit time. Furthermore, by analyzing the spatial morphological differences of water absorption and diffusion of paper surface fibers in the carton, rapid identification and analysis of the moisture-proof performance of the carton surface is achieved in the continuous production of corrugated cartons.

[0041] Furthermore, the present invention adds solutions containing different fluorescent substances at two wet diffusion points. Since the characteristic fluorescence peak wavelengths of these two fluorescent substances have a fixed and quantifiable difference, this inherent difference becomes the basis for defining the two solutions. Thus, it provides a fast and intuitive visualization method for analyzing the spatial morphological differences in water absorption and diffusion of paper fibers in cardboard boxes.

[0042] Furthermore, in actual testing, differences in paper fiber density and material uniformity can lead to asymmetrical solution diffusion. The fiber water absorption boundary line will deviate from the baseline and form several enclosed boundary areas on both sides. The enclosed areas on both sides of the baseline are classified as the first boundary sub-region and the second boundary sub-region, and their areas are added together to obtain the first boundary area and the second boundary area, which can accurately quantify the actual diffusion deviation scale on both sides.

[0043] Furthermore, by calculating the vertical distance between each paper interface point on the fiber water absorption interface line and the baseline, the present invention can capture the local deviation of each point and select the maximum value to reflect the degree of deviation of the solution diffusion from the baseline caused by factors such as the difference in the microstructure of the paper fibers.

[0044] Furthermore, the water absorption test value of this invention is essentially the average water absorption rate of the paper fibers during the effective testing phase. This indicator can intuitively reflect the water absorption capacity of the paper fibers. If the water absorption test value is less than the water absorption calibration value, it indicates that the moisture-proof performance of the paper fibers is insufficient before reaching the moisture-proof limit, and it is judged as unqualified. Thus, it realizes the rapid identification and analysis of the moisture-proof performance of the carton surface in the continuous production of corrugated cartons. Attached Figure Description

[0045] Figure 1 This is a flowchart illustrating the steps of the moisture-proof testing method for corrugated cardboard boxes according to an embodiment of the present invention.

[0046] Figure 2 This is a flowchart illustrating the steps involved in determining the fluorescence peak alignment in an embodiment of the present invention.

[0047] Figure 3 This is a flowchart illustrating the steps for obtaining the first deviation factor in an embodiment of the present invention.

[0048] Figure 4 This is a flowchart illustrating the logic of determining whether the water absorption and moisture-proof performance of paper fibers is qualified according to an embodiment of the present invention.

[0049] Figure 5 This is a system block diagram of the corrugated cardboard box moisture-proof testing system according to an embodiment of the present invention; Detailed Implementation

[0050] 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.

[0051] 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.

[0052] It should be noted that in the description of this invention, the terms "upper," "lower," "inner," "outer," etc., which indicate the direction or positional relationship, are based on the direction or positional relationship shown in the accompanying drawings. This is only for the convenience of description and does not 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.

[0053] It should be understood that although the present invention may use terms such as "first," "second," etc., to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of the present invention, first information may also be referred to as second information, and similarly, second information may also be referred to as first information.

[0054] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation" and "connection" 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.

[0055] Please see Figure 1 The diagram shows the steps of a moisture-proof testing method for corrugated cardboard boxes according to an embodiment of the present invention. The moisture-proof testing method for corrugated cardboard boxes of the present invention includes:

[0056] Step S100: Determine two moisture diffusion points with a preset spacing on the cardboard sample of the corrugated box, and simultaneously add solutions containing different fluorescent substances to each moisture diffusion point.

[0057] In this invention, the two fluorescent substances with non-overlapping characteristic fluorescence peaks are sodium fluorescein and rhodamine B. It is known that the characteristic fluorescence peak wavelength of sodium fluorescein is 510-520 nm, and the characteristic fluorescence peak wavelength of rhodamine B is 570-580 nm. Optionally, sodium fluorescein and rhodamine B can be prepared into solutions with a concentration of 0.08 mol / L, and then simultaneously and continuously added to the two wet diffusion points using a micropipette. The volume of solution added each time is 12 μL. Micropipettes are widely used in micro-infusion scenarios of solutions and reagents, and will not be elaborated here.

[0058] To avoid excessive local solution accumulation due to too small a distance between the two moisture diffusion points, which would affect the actual absorption performance test of the surface fibers, and to avoid excessive test time due to too large a distance between the two moisture diffusion points, the preset distance between the two moisture diffusion points can optionally be 24 mm.

[0059] In this invention, the cardboard sample is always kept in a horizontal and fixed state.

[0060] Step S200: Obtain an image of the area between the wet diffusion points after a single drop of the solution; mark several paper boundary points based on the comparison of each sub-region with the captured fluorescence peaks in the neighboring region within the image; and determine the fiber water absorption boundary line based on the paper boundary points.

[0061] In this invention, the interval between single drops of solution is the time from the first drop to the physical contact between the diffusion fronts of the two solutions on the paper fibers.

[0062] Step S300: Obtain the morphological difference information between the fiber water absorption boundary line and the diffusion reference baseline; calculate the water absorption performance deviation coefficient of the paper fiber by weighting each deviation factor in the morphological difference information; and determine whether to stop adding solution to the moisture diffusion point based on the comparison result of the water absorption performance deviation coefficient and the preset threshold.

[0063] Step S400: In response to the determination result of stopping the dripping of solution at the moisture diffusion point, calculate the water absorption test value of the paperboard sample within a preset unit time, and determine whether the water absorption and moisture-proof performance of the paper surface fibers is qualified based on the comparison between the water absorption test value and the water absorption calibration value.

[0064] Specifically, please refer to Figure 2 The diagram shown illustrates the steps for determining the fluorescence peak alignment in an embodiment of the present invention. The process for determining the fluorescence peak alignment includes:

[0065] Step S201: Obtain an image of the area between moisture diffusion points, and divide the image into several sub-regions of equal area;

[0066] Step S202: Collect fluorescence signals for each sub-region and extract the characteristic fluorescence peak wavelengths of each sub-region;

[0067] Step S203: Taking each sub-region as the central sub-region, the sub-regions that are adjacent to the central sub-region on the left and right along the direction of the line connecting the moisture diffusion points are determined as the neighborhood, and the wavelength difference of the characteristic fluorescence peak wavelength between the central sub-region and each sub-region in the neighborhood is calculated.

[0068] In this invention, the region image can be divided into several 2mm × 2mm square sub-regions.

[0069] It is understandable that when two solutions containing different fluorescent substances are simultaneously added from two moist diffusion points, the main diffusion trend is towards each other along the line connecting the two moisture diffusion points, and the boundary region between the two solutions also mainly extends along this direction. By selecting adjacent sub-regions for fluorescence peak comparison, it is possible to capture the location nodes where the same solution infiltrates into different solutions.

[0070] It is understandable that two solutions containing different fluorescent substances diffuse synchronously from two moist diffusion points. During the diffusion process, the areas wetted by different solutions will exhibit corresponding fluorescence peaks. Dividing the regional image into several equal-area sub-regions is to transform the continuous fluorescence signal distribution into discrete units that can be accurately acquired and analyzed, ensuring the targeted nature of subsequent fluorescence signal extraction. Fluorescence signals are acquired for each sub-region, and the wavelength of the characteristic fluorescence peak is extracted. Since the wavelength of the characteristic fluorescence peak is a unique identifier of the fluorescent substance, the characteristic fluorescence peak wavelengths of different fluorescent substances have fixed differences. By extracting the wavelength, it can be determined which solution wetted each sub-region.

[0071] Specifically, the process of marking the boundary points on the paper includes:

[0072] The wavelength difference is compared with the wavelength difference reference value;

[0073] If the wavelength difference is greater than the wavelength difference reference value, then the center point of the central sub-region is marked as the paper boundary point;

[0074] If the wavelength difference is less than or equal to the wavelength difference reference value, then the central sub-region is not marked;

[0075] The wavelength difference reference value is determined based on the wavelength difference of the characteristic fluorescence peaks of different fluorescent substances.

[0076] In this invention, when the two fluorescent substances selected are sodium fluorescein and rhodamine B, the wavelength difference reference value can optionally be set to 40 nm.

[0077] It is understandable that, since the solutions added at the two wet diffusion points contain different fluorescent substances, there is a fixed and quantifiable difference in the characteristic fluorescence peak wavelengths of these two fluorescent substances. This inherent difference is the basis for defining the two solutions. After extracting the characteristic fluorescence peak wavelengths of each sub-region and calculating the wavelength difference between the central sub-region and the neighboring sub-region, the calculated wavelength difference is compared with the wavelength difference reference value. If the wavelength difference is less than or equal to the wavelength difference reference value, it indicates that the fluorescent substances in the central sub-region and the neighboring sub-region are of the same type, that is, they are wetted by the same solution and belong to the same diffusion region. If the wavelength difference is greater than the wavelength difference reference value, it indicates that the fluorescent substances in the central sub-region and the neighboring sub-region are of different types and are wetted by two different solutions. The center point of the central sub-region is exactly at the boundary between the diffusion of the two solutions.

[0078] Specifically, the process of determining the fiber water absorption boundary line is as follows: the curve formed by connecting each paper boundary point one by one along the direction perpendicular to the line connecting the moisture diffusion points is determined as the fiber water absorption boundary line.

[0079] It is understandable that the paper interface point is the discrete boundary point of the wetting area of ​​the two solutions; the direction perpendicular to the line connecting the moisture diffusion points is selected as the basis for the connection order because this direction matches the direction of the diffusion front of the two solutions and fits the actual diffusion boundary shape of the solution in the paper fibers; by connecting all the paper interface points one by one to form a continuous curve, the water absorption and diffusion boundary of the two solutions in the paper fibers can be intuitively presented.

[0080] Specifically, please refer to Figure 3 The diagram illustrates the steps for obtaining the first deviation factor in an embodiment of the present invention. Obtaining the first deviation factor within the morphological difference information includes:

[0081] Step S301: Determine several first boundary crossing sub-regions and second boundary crossing sub-regions enclosed by the fiber water absorption boundary line on both sides of the diffusion reference baseline.

[0082] Step S302: The accumulated value of the area surface of several first boundary-crossing sub-regions is recorded as the first boundary-crossing area, and the accumulated value of the area surface of several second boundary-crossing sub-regions is recorded as the second boundary-crossing area;

[0083] Step S303: The ratio of the difference between the first boundary area and the second boundary area to the preset difference reference value is determined as the first deviation factor;

[0084] The diffusion reference baseline is a straight line perpendicular to the line connecting the two moisture diffusion points and passing through the midpoint of the line connecting the moisture diffusion points.

[0085] In this invention, the preset difference reference value can be determined by the area of ​​the first boundary area and the second boundary area. Optionally, the preset difference reference value = the sum of the areas of the first boundary area and the second boundary area × the difference reference value coefficient. The preset difference reference value coefficient can be set to 0.08 to ensure that the feature of a large difference between the areas of the first boundary area and the second boundary area can be amplified and incorporated into the calculation of the water absorption performance deviation coefficient.

[0086] For example, using the diffusion reference baseline as the boundary, the closed area formed by the intersection of the fiber water absorption boundary line and the diffusion reference baseline is divided into two categories: the closed area on one side of the baseline is the first boundary crossing sub-region, and the closed area on the other side is the second boundary crossing sub-region; if there are multiple intersection points between the fiber water absorption boundary line and the baseline, then independent closed boundary crossing regions are divided in the order of the intersection points, and all boundary crossing regions do not overlap with each other;

[0087] Summing up the areas of all sub-regions identified as first boundary violations yields the first boundary violation area. Similarly, summing up the areas of all sub-regions identified as second boundary violations yields the second boundary violation area. Since each sub-region is a 2mm x 2mm square, the area of ​​each first or second boundary violation sub-region is 4mm². 2 .

[0088] Understandably, the diffusion reference baseline is the midline of the boundary under ideal, uniform diffusion conditions after two solutions are simultaneously added from the wet diffusion point. At this point, the diffusion ranges of the solutions on both sides are completely symmetrical. However, in actual testing, differences in paper fiber density and material uniformity can lead to asymmetrical solution diffusion. The fiber water absorption boundary line will deviate from the baseline and form several enclosed boundary areas on both sides. The enclosed areas on both sides of the baseline are classified as the first boundary sub-region and the second boundary sub-region, respectively. The sum of their areas yields the first boundary area and the second boundary area, which can accurately quantify the actual degree of diffusion deviation on both sides. The ratio of the two boundary areas is used as the first deviation factor. The closer the ratio is to 1, the more balanced the degree of diffusion deviation on both sides, and the better the symmetry and uniformity of paper fiber water absorption diffusion. The greater the deviation of the ratio from 1, the more significant the difference in diffusion on both sides, and the worse the uniformity.

[0089] Specifically, the second deviation factor within the morphological difference information is obtained, including:

[0090] Calculate the vertical distance between each paper interface point and the diffusion reference baseline on the fiber water absorption interface line, and determine the ratio of the maximum vertical distance to the preset vertical distance reference value as the second deviation factor.

[0091] In this invention, the vertical distance between each paper intersection point and the diffusion reference baseline can be calculated using the coordinate ranging function. The coordinate ranging function is a commonly used calculation and calibration function in image processors, and will not be described in detail here.

[0092] In this invention, the preset vertical distance reference value is determined based on the preset distance between two moisture diffusion points, and the vertical distance reference value T is... c0 =δ×T0, where δ is the factor for the vertical distance reference value, and the value range of δ is [0.075, 0.12]. T0 is the preset distance between the two moisture diffusion points. Optionally, under the condition that T0=24mm, the value of δ can be 0.1.

[0093] Under ideal conditions, the fiber water absorption boundary line should coincide with the diffusion reference baseline, and the vertical distance between each paper boundary point and the baseline should be close to 0. However, in actual tests, factors such as differences in the microstructure of the paper fibers can cause local bulges or depressions in the solution diffusion, causing the fiber water absorption boundary line to deviate from the baseline. By calculating the vertical distance between each paper boundary point on the fiber water absorption boundary line and the baseline, the local deviation at each point can be captured. Selecting the maximum value reflects the limit of the boundary line's deviation relative to the baseline. The larger the value of the second deviation factor, the more significant the overall deviation of the fiber water absorption boundary line, and the worse the uniformity of the paper fiber water absorption diffusion.

[0094] Specifically, the first deviation factor and the second deviation factor are weighted and summed to obtain the deviation coefficient K of the water absorption performance of the paper fibers.

[0095] In this invention, the weights of the first deviation factor and the second deviation factor can be adjusted by technicians according to the actual calculated feature emphasis. The water absorption performance deviation coefficient K = α × F1 + β × F2, where F1 is the first deviation factor, F2 is the second deviation factor, α is the weight of the first deviation factor, β is the weight of the second deviation factor, and α + β = 1. Optionally, in practice, the weights of the first deviation factor and the second deviation factor can both be set to 0.5.

[0096] Specifically, the process of determining whether to stop adding solution to the moisture diffusion point includes:

[0097] If the water absorption performance deviation coefficient is greater than a preset threshold, then it is determined that the solution should be stopped being added to the moisture diffusion point;

[0098] If the water absorption performance deviation coefficient is less than or equal to a preset threshold, it is determined that the solution should continue to be added to the moisture diffusion point.

[0099] In this invention, the purpose of setting a preset threshold is as follows: the face paper and corrugated paper of corrugated cardboard have a layered structure. The pore structure of the face paper fibers is the main carrier for moisture storage and diffusion. In the initial stage of dripping, the solution mainly diffuses within the pores of the face paper fibers. At this time, the fiber's water absorption capacity is not saturated, and the diffusion is dominated by the uniformity of the fiber's microstructure. The water absorption performance deviation coefficient is in a stable low range. When the capillary pores of the face paper fibers are completely filled by the solution, the water absorption capacity reaches its limit. The solution that continues to be dripped cannot diffuse effectively within the face paper and can only break through the interface between the face paper and the corrugated paper, penetrating into the corrugated paper layer with greater differences in water absorption characteristics. The corrugated paper's corrugated structure causes the solution diffusion path to be disordered, which is directly manifested as a sharp increase in the water absorption performance deviation coefficient. The preset threshold is a quantitative critical value for capturing abrupt changes. Optionally, under the condition that the calculated value of the first deviation factor is greater than 1.2 and the calculated value of the second deviation factor is greater than 1.2, it can be determined that the fiber's water absorption capacity is unevenly diffused due to local saturation. Based on this, the preset threshold value can be set to 1.2.

[0100] Understandably, the water absorption performance deviation coefficient is a weighted composite parameter that integrates diffusion symmetry and uniformity with the degree of local extreme deviation. Its value directly corresponds to the diffusion uniformity of the solution in the paper fibers. In the actual test scenario on the cardboard surface, as the amount of solution added increases, the local water absorption performance of the paper fibers will first reach its saturation limit. At this point, the solution will penetrate into the corrugated paper layer inside the face paper. However, the material structure and water absorption characteristics of the corrugated paper and the face paper are different, which will further aggravate the unevenness of solution diffusion, reflected in a significantly larger water absorption performance deviation coefficient. In the test case, when the water absorption deviation coefficient is greater than the preset threshold, it indicates that the paperboard sample has reached its moisture-proof limit in some areas. Continuing to add solution will cause the diffusion pattern to deviate significantly from the true moisture-proof characteristics of the paper fibers due to the uneven water absorption of the corrugated paper, rendering the test data meaningless. Therefore, in this case, it is necessary to stop adding solution. When the water absorption deviation coefficient is less than or equal to the preset threshold, it indicates that the solution is still mainly diffused within the paper fibers, and the diffusion uniformity meets the deviation requirements. Continuing to add solution can effectively collect the true water absorption and moisture-proof data of the paper fibers, thereby achieving precise control of the test process.

[0101] Specifically, please refer to Figure 4 As shown, this is a flowchart illustrating the logic of determining whether the water absorption and moisture-proof performance of paper fibers is qualified according to an embodiment of the present invention. The process of determining whether the water absorption and moisture-proof performance of paper fibers is qualified based on the comparison between the water absorption test value and the water absorption calibration value includes:

[0102] Obtain the cumulative amount of solution added at two moisture diffusion points within the allowable adding period, and determine the cumulative amount of solution added as the water absorption test value;

[0103] If the water absorption test value is less than the water absorption calibration value, the water absorption and moisture-proof performance of the paper fiber is deemed unqualified; if the water absorption test value is greater than or equal to the water absorption calibration value, the water absorption and moisture-proof performance of the paper fiber is deemed qualified.

[0104] In the implementation of this invention, the water absorption calibration value can be determined according to the moisture content parameter calibrated in the design of the carton. The moisture content parameter calibrated in the design of the carton refers to the maximum moisture content that the carton can reach during its normal service life. Exceeding this maximum moisture content will lead to a decrease in the strength of the carton or even deformation.

[0105] For example, the maximum allowable moisture content W of the carton is obtained from the carton design specifications. max The dry mass M of the surface paper in the area between the moisture diffusion point and the moisture diffusion point p For example: the area between moisture diffusion points is 100 cm². 2 The paper weight is 150g / m². 2 Then M p =1.5g; The calculated total water absorption of the paper fibers when they reach the designed maximum moisture content is M. abs =M p ×W max This value represents the maximum mass of water that the facial tissue can absorb without becoming ineffective; the density of bound water is 1 g / cm³. 3 Mass can be converted into volume, i.e., V. abs =M abs ×1mL=M abs ×1000μL, since the amount of solution diffusing from the moisture diffusion point to the area between moisture diffusion points is only half of the actual amount diffused, the water absorption calibration value can be set to 2V. abs .

[0106] It is understood that the allowable dripping period in this invention is an effective test time interval determined by comparing the water absorption performance deviation coefficient with a preset threshold. During this time interval, the solution mainly diffuses within the paper fibers and does not cause data distortion due to penetration into the corrugated paper layer. Therefore, the cumulative amount of solution dripped during this period is a key parameter reflecting the true water absorption capacity of the paper fibers. The water absorption test value is essentially the average water absorption rate of the paper fibers during the effective test phase. This indicator can intuitively reflect the water absorption capacity of the paper fibers. If the water absorption test value is less than the water absorption calibration value, it indicates that the moisture-proof performance of the paper fibers is insufficient before reaching the moisture-proof limit, and it is judged as unqualified. If the water absorption test value is greater than or equal to the water absorption calibration value, it indicates that the paper fibers have good water retention capacity and the moisture-proof performance meets the standard.

[0107] Specifically, please refer to Figure 5 The diagram shown is a system block diagram of the corrugated cardboard box moisture-proof testing system according to an embodiment of the present invention. The corrugated cardboard box moisture-proof testing system of the present invention includes:

[0108] The fluorescent wetting module is used to simultaneously drop solutions containing different fluorescent substances onto each wet diffusion point on a cardboard sample;

[0109] In this invention, the fluorescent wetting module can be a micropipette, which is widely used for aspirating and dispensing liquid volumes of 0.1 μL to 10 mL, and will not be described in detail here.

[0110] An image acquisition module is used to acquire a regional image of the surface of a cardboard sample and divide the regional image into several sub-regions;

[0111] This invention does not limit the image acquisition module, which can be an industrial CCD camera.

[0112] A fluorescence excitation module, which is connected to the image acquisition module, is used to mark several paper boundary points based on the comparison of fluorescence peaks captured in each sub-region and the neighboring region, and to determine the fiber water absorption boundary line based on the paper boundary points.

[0113] This invention does not limit the fluorescence excitation module, which can irradiate fluorescent materials with different excitation wavelengths emitted by an LED excitation light source.

[0114] The control module is connected to the fluorescent wetting module and the fluorescent excitation module respectively. It is used to calculate the weighted deviation factors in the morphological difference information to obtain the water absorption performance deviation coefficient of the paper fiber, and to determine whether to stop adding solution to the moisture diffusion point based on the comparison result of the water absorption performance deviation coefficient and the preset threshold.

[0115] This invention does not limit the control module, which can be a PLC controller or an industrial-grade microcontroller, and will not be elaborated here.

[0116] The test analysis module, which is connected to the control module, is used to calculate the water absorption test value of the paperboard sample within a preset unit time. Based on the comparison between the water absorption test value and the water absorption calibration value, it is determined whether the water absorption and moisture-proof performance of the paper surface fibers is qualified.

[0117] This invention does not limit the test and analysis module, which can be a microprocessor, a processor used in a computer, etc.

[0118] 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.

[0119] 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. A method for testing the moisture resistance of corrugated cardboard boxes, characterized in that, include: Two moisture diffusion points with a preset spacing were determined on a corrugated cardboard sample, and solutions containing different fluorescent substances were simultaneously added to each moisture diffusion point. After a single drop of the solution is added, an image of the region between the wet diffusion points is obtained. Based on the comparison of each sub-region in the region image with the captured fluorescence peaks in the neighboring region, several paper boundary points are marked. Based on the paper boundary points, the fiber water absorption boundary line is determined. Obtain the morphological difference information between the fiber water absorption boundary line and the diffusion reference baseline, calculate the water absorption performance deviation coefficient of the paper fiber by weighting each deviation factor in the morphological difference information, and determine whether to stop adding solution to the moisture diffusion point based on the comparison result of the water absorption performance deviation coefficient and the preset threshold. In response to the determination result of stopping the addition of solution at the moisture diffusion point, the water absorption test value of the paperboard sample within a preset unit time is calculated, and the water absorption test value is compared with the water absorption calibration value to determine whether the water absorption and moisture-proof performance of the paper surface fibers is qualified.

2. The method for testing the moisture resistance of corrugated cardboard boxes according to claim 1, characterized in that, The process of determining the fluorescence peak alignment includes: Acquire an image of the region between moisture diffusion points, and divide the region image into several sub-regions of equal area; Fluorescence signals were acquired for each sub-region, and the characteristic fluorescence peak wavelengths of each sub-region were extracted. Taking each sub-region as the central sub-region, the sub-regions that are adjacent to the central sub-region on the left and right along the direction of the line connecting the moisture diffusion points are determined as the neighborhood. The wavelength difference of the characteristic fluorescence peak wavelength between the central sub-region and each sub-region in the neighborhood is calculated.

3. The method for testing the moisture resistance of corrugated cardboard boxes according to claim 2, characterized in that, The process of marking the boundary points on the paper includes: The wavelength difference is compared with the wavelength difference reference value; If the wavelength difference is greater than the wavelength difference reference value, then the center point of the central sub-region is marked as the paper boundary point; The wavelength difference reference value is determined based on the wavelength difference of the characteristic fluorescence peaks of different fluorescent substances.

4. The method for testing the moisture resistance of corrugated cardboard boxes according to claim 3, characterized in that, The process of determining the fiber water absorption boundary line is as follows: connect each paper boundary point one by one along the direction perpendicular to the line connecting the moisture diffusion points to determine the curve formed by the fiber water absorption boundary line.

5. The method for testing the moisture resistance of corrugated cardboard boxes according to claim 1, characterized in that, The first deviation factor within the morphological difference information is obtained, including: Determine several first boundary-crossing sub-regions and second boundary-crossing sub-regions enclosed on both sides of the diffusion reference baseline by the fiber water absorption boundary line; The accumulated area of ​​several first boundary-crossing sub-regions is recorded as the first boundary-crossing area, and the accumulated area of ​​several second boundary-crossing sub-regions is recorded as the second boundary-crossing area. The ratio of the difference between the first boundary area and the second boundary area to the preset difference reference value is determined as the first deviation factor; The diffusion reference baseline is a straight line perpendicular to the line connecting the two moisture diffusion points and passing through the midpoint of the line connecting the moisture diffusion points.

6. The method for testing the moisture resistance of corrugated cardboard boxes according to claim 1, characterized in that, The second deviation factor within the morphological difference information is obtained, including: Calculate the vertical distance between each paper interface point and the diffusion reference baseline on the fiber water absorption interface line, and determine the ratio of the maximum vertical distance to the preset vertical distance reference value as the second deviation factor.

7. The method for testing the moisture resistance of corrugated cardboard boxes according to claim 5 or 6, characterized in that, The first deviation factor and the second deviation factor are weighted and summed to obtain the deviation coefficient of water absorption performance of paper fibers.

8. The method for testing the moisture resistance of corrugated cardboard boxes according to claim 6, characterized in that, The process of determining whether to stop adding solution to the moisture diffusion point includes: If the water absorption performance deviation coefficient is greater than a preset threshold, then it is determined that the solution should be stopped being added to the moisture diffusion point; If the water absorption performance deviation coefficient is less than or equal to a preset threshold, it is determined that the solution should continue to be added to the moisture diffusion point.

9. The method for testing the moisture resistance of corrugated cardboard boxes according to claim 7, characterized in that, The process of determining whether the water absorption and moisture-proof performance of the paper fibers is qualified based on the comparison between the water absorption test value and the water absorption calibration value includes: Obtain the cumulative amount of solution added at two moisture diffusion points within the allowable adding period, and determine the cumulative amount of solution added as the water absorption test value; If the water absorption test value is less than the water absorption calibration value, the water absorption and moisture-proof performance of the paper fiber is deemed unqualified; if the water absorption test value is greater than or equal to the water absorption calibration value, the water absorption and moisture-proof performance of the paper fiber is deemed qualified.

10. A corrugated cardboard box moisture-proof testing system, used to perform the corrugated cardboard box moisture-proof testing method according to any one of claims 1-9, characterized in that, include: The fluorescent wetting module is used to simultaneously drop solutions containing different fluorescent substances onto each wet diffusion point on a cardboard sample; An image acquisition module is used to acquire a regional image of the surface of a cardboard sample and divide the regional image into several sub-regions; A fluorescence excitation module, which is connected to the image acquisition module, is used to mark several paper boundary points based on the comparison of fluorescence peaks captured in each sub-region and the neighboring region, and to determine the fiber water absorption boundary line based on the paper boundary points. The control module is connected to the fluorescent wetting module and the fluorescent excitation module respectively. It is used to calculate the weighted deviation factors in the morphological difference information to obtain the water absorption performance deviation coefficient of the paper fiber, and to determine whether to stop adding solution to the moisture diffusion point based on the comparison result of the water absorption performance deviation coefficient and the preset threshold. The test analysis module, which is connected to the control module, is used to calculate the water absorption test value of the paperboard sample within a preset unit time. Based on the comparison between the water absorption test value and the water absorption calibration value, it is determined whether the water absorption and moisture-proof performance of the paper surface fibers is qualified.

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