Quantitative evaluation method for fitting degree of transparent paper of cigarette soft box

Abstract

The invention relates to a quantitative evaluation method for the fitting degree of transparent paper of a cigarette soft box, and belongs to the technical field of cigarette manufacturing. The method comprises the following steps: acquiring a contour line of the transparent paper surface by means of a line laser and a camera; a 3D point cloud on the surface of the transparent paper is reconstructed by calculating the height value of the contour line; extracting 3D point cloud data of the wrinkled region; based on the point cloud information, obtaining the bottom area, the height and the volume of each wrinkle region; and carrying out quantitative evaluation on the fit degree of the transparent paper according to the transparent paper fit degree evaluation function by integrating the characteristic parameters of all the wrinkle regions. The method can effectively evaluate the wrinkle degree of the transparent paper on the surface of the cigarette case, and the technical achievement can be applied to cigarette quality inspection or production sampling inspection.

Description

Technical Field

[0001] The present invention belongs to the technical field of cigarette manufacturing, and in particular relates to a quantitative evaluation method for the degree of adhesion of transparent paper of a soft cigarette box. Background Art

[0002] Affected by the packaging process, the transparent packaging of cigarette soft boxes will produce a certain proportion of paper wrinkles during the packaging process, resulting in poor adhesion between the transparent paper and the soft box label paper, which has a significant impact on the sealing performance of the cigarette soft box and consumer sensory perception. The degree of adhesion of the transparent paper of the cigarette soft box is one of the important indicators for evaluating the quality of cigarettes packed in soft boxes. With the continuous iteration and upgrading of new products in the tobacco industry, the industry has also put forward higher requirements for the aesthetics and applicability of cigarette packaging.

[0003] At present, in the actual production process, due to the influence of materials, equipment differences, process conditions and other factors, a series of appearance quality defects such as loose or too tight transparent paper wrapping, wrinkling and unevenness usually occur, especially transparent paper wrinkle defects account for the largest proportion. In the process of product factory inspection, various industrial enterprises mainly inspect the quality of cigarette packaging by manual visual inspection, which is relatively subjective, and the inspectors must touch the samples to be tested, which can easily cause certain deformation of the soft box samples, affecting the judgment of transparent paper wrinkles. There are shortcomings such as time-consuming and labor-intensive, relatively low detection accuracy, and large errors. Summary of the invention

[0004] The present disclosure proposes a quantitative evaluation method for the degree of adhesion of transparent paper of a soft cigarette box to solve the above technical problems.

[0005] A quantitative evaluation method for the fit of transparent paper of a soft cigarette box includes: a quantitative evaluation method for the fit of transparent paper of a soft cigarette box, characterized in that the method includes: collecting contour lines of the transparent paper surface by means of a line laser and a camera; reconstructing a 3D point cloud of the transparent paper surface by calculating the height value of the contour line; extracting 3D point cloud data of wrinkle areas; obtaining the bottom area, height and volume of each wrinkle area based on the point cloud information; and comprehensively evaluating the fit of the transparent paper according to a transparent paper fit evaluation function based on the characteristic parameters of all wrinkle areas.

[0006] In some embodiments, calculating the height value of the contour line includes: according to the formula: , calculate the height value of the contour line ,in, , Indicates the deviation of the light strip projected by the laser line onto the folds of the transparent paper. Indicates the offset distance of the upper edge of the light bar from the center line in the image. Indicates the focal length of the lens, represents the distance between the camera and the line laser, Indicates the height value from the probe when the light bar is not offset. Indicates the height of the light bar from the probe after it is not offset.

[0007] In some embodiments, reconstructing the 3D point cloud of the transparent paper surface includes: splicing contour lines in three-dimensional space according to the order of height values ​​of the contour lines to form the 3D point cloud of the transparent paper surface.

[0008] In some embodiments, the extracting of 3D point cloud data of the wrinkle area includes: scanning the 3D point cloud of the upper surface of the transparent paper of the cigarette box line by line along the XY direction, wherein the measured area of ​​the 3D point cloud of the upper surface is S c ; Use the mean filter convolution kernel to smooth the area and get the area of ​​the reference surface as S ， , then the area Z of the wrinkle point cloud is S c – S ， .

[0009] In some embodiments, the step of comprehensively evaluating the characteristic parameters of all wrinkle regions and quantitatively evaluating the degree of adhesion of the transparent paper according to a transparent paper adhesion evaluation function includes: according to the formula: , calculate the deformation coefficient of the i-th wrinkle ,in, represents the volume of the i-th wrinkle, represents the bottom area of ​​the i-th fold, Represents the height of the i-th wrinkle; according to the formula: , calculate the fit evaluation coefficient , where n is the total number of folds, Represents the design area of ​​the measuring surface of the cigarette box.

[0010] In some embodiments, the line laser and the camera are both fixed on a motorized slide.

[0011] Advantages of the present invention: A dedicated acquisition system for the three-dimensional morphology of transparent paper is constructed with the aid of a camera and a line laser to obtain the contour line of the transparent paper surface. The 3D point cloud of the transparent paper surface is reconstructed by calculating the height value of the contour line; the 3D point cloud data of the wrinkle area is extracted by the reference plane subtraction method, and the bottom area, height and volume of each wrinkle area are obtained according to the point cloud information. The transparent paper fit evaluation function is constructed by integrating the characteristic parameters of all wrinkle areas, and the transparent paper fit of the cigarette soft box is quantitatively evaluated. The present invention can be applied to the quality inspection of finished cigarettes or production sampling.

[0012] Other features and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0014] Figure 1 It is a transparent paper three-dimensional shape measurement system.

[0015] Figure 2 Schematic diagram for calculating contour height values.

[0016] Figure 3 Schematic diagram of the laser outline of transparent paper.

[0017] Figure 4 This is a schematic diagram of the transparent paper 3D point cloud.

[0018] Figure 5 This is a diagram of a cigarette box.

[0019] Figure 6 Schematic diagram of fold combination parameters. DETAILED DESCRIPTION

[0020] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure unless otherwise specifically stated.

[0021] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0022] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0023] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0024] The method comprises: using a cigarette transparent paper three-dimensional shape measurement system to obtain the contour line of the transparent paper surface through a line laser and a camera, and reconstructing a 3D point cloud of the transparent paper surface by calculating the height value of the contour line; using a wrinkle characteristic parameter measurement algorithm to extract 3D point cloud data of the wrinkle area through a reference plane subtraction method, and obtaining the bottom area, height, and volume of each wrinkle area according to the point cloud information; and constructing a transparent paper adhesion evaluation function by comprehensively combining the characteristic parameters of all wrinkle areas, and quantitatively evaluating the transparent paper adhesion of the cigarette soft box.

[0025] like Figure 1As shown in the figure, the three-dimensional shape measurement system of cigarette transparent paper: the shape scanning device includes a line laser, a camera, an electric slide, a cigarette and a stage. The line laser is vertically downward, and the camera is located 100mm to one side of the line laser, with an angle of 60°. The line laser and the camera are fixed on the same electric slide. The electric slide drives the line laser and the camera to scan the transparent paper on the surface of the cigarette box. When the laser line is irradiated on the surface of the transparent paper to form a light strip, the camera collects each frame of the light strip image.

[0026] The three-dimensional reconstruction algorithm of transparent paper morphology includes line laser contour extraction algorithm, height calculation algorithm and three-dimensional reconstruction algorithm. For each frame of laser line image, the line laser contour extraction algorithm extracts the transparent paper laser contour line according to the highest point extraction criterion, such as Figure 3 As shown in the figure, the specific requirement of the highest point extraction criterion is that the laser will be projected when it is irradiated on the transparent paper, and light strips will be generated on the surface of the transparent paper and the surface of the cigarette box respectively; each frame of the light strip image collected by the camera is scanned by column, and only the pixel point corresponding to the highest point of the Y axis of the light strip is extracted from each column. Figure 2 As shown, the calculation method of the Z-axis height h of the transparent paper is: , θ is the deviation angle of the light strip projected by the laser line onto the folds of the transparent paper, bias is the offset distance of the upper edge of the light strip from the center line in the image, f is the focal length of the lens, h is the height of the fold at the measurement point, L is the distance between the camera and the laser, Indicates the height value from the probe when the light bar is not offset. Indicates the height of the light bar from the probe after it is not offset.

[0027] The 3D reconstruction algorithm calculates the laser line height value in each frame of the light strip image, and then stitches the contour lines of all the transparent paper laser contour lines scanned on the cigarette box in sequence in 3D space to form a 3D point cloud on the upper surface of the transparent paper of the cigarette box, such as Figure 4 shown.

[0028] The wrinkle feature parameter measurement algorithm includes a wrinkle extraction algorithm and a wrinkle feature parameter measurement algorithm. The specific steps of the wrinkle extraction algorithm are to scan the three-dimensional point cloud of the upper surface of the transparent paper of the cigarette box line by line along the XY direction. The measured area of ​​the three-dimensional point cloud of the upper surface is S c , use the mean filter convolution kernel of size 10×10 to smooth the area and get the reference surface S', then the area Z of the wrinkle point cloud is S c - S'.

[0029] The specific steps of the wrinkle characteristic parameter measurement algorithm are to extract the point cloud Z of the i-th wrinkle i Afterwards, Figure 6 As shown, the bottom area S of the wrinkle area is obtained i , height h i , and volume V i.

[0030] According to the formula , calculate the deformation coefficient of each fold, represents the deformation coefficient of the i-th wrinkle, and the evaluation function is , T represents the evaluation coefficient, n represents the total number of wrinkles, and S represents the design area of ​​the measuring surface of the cigarette box, which is a theoretical value.

[0031] like Figure 5 As shown, the present invention can evaluate the wrinkle degree of transparent paper, and the technical achievements of the present invention can be applied to cigarette quality inspection or production sampling inspection.

[0032] In some embodiments, after extracting the 3D point cloud data of the wrinkle area, the area enclosed by the bottom contour lines of all wrinkles can be counted, and the surface area of ​​the standard cigarette box formed by the reference surface can be calculated. Based on the area enclosed by the bottom contour lines of all wrinkles and the surface area of ​​the standard cigarette box formed by the reference surface, the wrinkle amount is obtained, the maximum height and maximum length of the wrinkles are determined, and the wrinkle protrusion of each wrinkle is calculated; the total wrinkle protrusion is calculated; the squareness of the soft package is determined; based on the wrinkle amount, the total wrinkle protrusion, and the squareness of the soft package, the soft package molding quality evaluation value is determined. This embodiment can evaluate the molding quality of the soft box from multiple dimensions.

[0033] Please note that according to the formula: , calculate the right angle of the jth vertex ,in, represents the angle of the jth vertex; according to the formula , calculate the squareness D of the soft box, where N represents the number of vertex angles of the soft box. The soft box has 6 faces, namely the front, back, upper end, lower end, left side, and right side. Each face has 4 vertex angles, for a total of 24 vertex angles. Indicates the detection angle of one of the 24 angles. According to the formula: , calculate the squareness D of the soft box, where N represents the number of vertex angles of the soft box. In this embodiment, N is 24.

[0034] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A quantitative evaluation method for the degree of adhesion of transparent paper of a cigarette soft box, characterized in that: The method comprises: The contour lines of the transparent paper surface are collected with the help of line laser and camera; Reconstruct the 3D point cloud of the transparent paper surface by calculating the height value of the contour line; Extract 3D point cloud data of wrinkle area; Based on the point cloud information, the bottom area, height and volume of each wrinkle area are obtained; The characteristic parameters of all wrinkle areas are comprehensively considered, and the degree of adhesion of transparent paper is quantitatively evaluated according to the evaluation function of the degree of adhesion of transparent paper.

2. The quantitative evaluation method for the degree of adhesion of transparent paper of a cigarette soft box according to claim 1, characterized in that: The step of calculating the height value of the contour line comprises: According to the formula: , calculate the height value of the contour line ,in, , Indicates the deviation of the light strip projected by the laser line onto the folds of the transparent paper. Indicates the offset distance of the upper edge of the light bar from the center line in the image. Indicates the focal length of the lens, represents the distance between the camera and the line laser, Indicates the height value from the probe when the light bar is not offset. Indicates the height of the light bar from the probe after it is not offset.

3. The quantitative evaluation method for the degree of adhesion of transparent paper of a cigarette soft box according to any one of claims 1 or 2, characterized in that: The 3D point cloud of the reconstructed transparent paper surface comprises: The contour lines are spliced ​​in three-dimensional space according to the order of their height values ​​to form a 3D point cloud of the transparent paper surface.

4. The quantitative evaluation method for the degree of adhesion of transparent paper of a cigarette soft box according to claim 1, characterized in that: The step of extracting 3D point cloud data of the wrinkle area includes: The three-dimensional point cloud of the upper surface of the transparent paper of the cigarette box is scanned line by line along the XY direction, where the measured area of ​​the three-dimensional point cloud of the upper surface is S c ; The area is smoothed using the mean filter convolution kernel, and the area of ​​the reference surface is S ， , then the area Z of the wrinkle point cloud is S c – S ， .

5. The quantitative evaluation method for the degree of adhesion of transparent paper of a cigarette soft box according to claim 1, characterized in that: The method of comprehensively evaluating the characteristic parameters of all wrinkle regions and quantitatively evaluating the degree of adhesion of the transparent paper according to the transparent paper adhesion evaluation function includes: According to the formula: , calculate the deformation coefficient of the i-th wrinkle ,in, represents the volume of the i-th wrinkle, represents the bottom area of ​​the i-th fold, represents the height of the i-th fold; According to the formula: , calculate the fit evaluation coefficient , where n is the total number of folds, Represents the design area of ​​the measuring surface of the cigarette box.

6. The quantitative evaluation method for the degree of adhesion of transparent paper of a cigarette soft box according to claim 1, characterized in that: The line laser and the camera are both fixed on an electric slide.

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