Defect detection mechanism for silk-screen printing and silk-screen printing process

Abstract

The invention discloses a defect detection mechanism for silk-screen printing and a silk-screen printing process, and relates to printing defect detection.According to the technical scheme, the defect detection mechanism comprises a rack and two guide rails fixedly connected to the top face of the rack, a bearing table is connected to the guide rails in a sliding mode, and a heating part used for heating ink is arranged on a silk-screen printing plate; a temperature information acquisition module, an image acquisition module and a display module are arranged on the rack. The position of the printing ink is judged according to the temperature difference, information collection is not affected even if the color difference between the printing ink and the textile fabric is not obvious, the temperature difference is marked by colors to generate a thermal image, then the image information of the surface of the textile fabric is collected through the camera, image processing is conducted on the thermal image and the image information collected by the camera, and the image processing accuracy is improved. The accuracy of ink distribution judgment is improved through combination of the two methods, so that pattern change flaws caused by ink position deviation on the textile fabric are found out and finally fed back to an operator through a display screen.

Description

Technical Field

[0001] The invention relates to printing defect detection, and more particularly to a defect detection mechanism for screen printing and a screen printing process. Background Art

[0002] As an important printing technology, screen printing has the characteristics of simple equipment, easy operation, strong adaptability and low cost. It is widely used in various fields, such as textile printing, paper printing, plastic printing, wood product printing, metal product printing, glass and ceramic product printing, etc. Its basic principle is to use the principle that the mesh holes of the graphic part of the screen printing plate are transparent to ink, while the mesh holes of the non-graphic part are not transparent to ink. However, in the actual printing process, due to the influence of various factors, such as the viscosity of the ink, the pressure of the scraper, the tension of the screen, etc., various defects often occur, such as uneven printing, missing printing, broken lines, blurring, etc.

[0003] For defect detection in screen printing, traditional detection methods mostly rely on manual visual inspection. This method is not only inefficient, but also easily affected by human factors, making it difficult to ensure the accuracy and consistency of the detection results. Therefore, with the continuous development of image processing technology and machine vision technology, automated and intelligent defect detection mechanisms have gradually been introduced into the field of screen printing. Such defect detection mechanisms usually collect images of printed products, use image processing algorithms to pre-process the images by graying, filtering and noise reduction, brightness balancing, contrast balancing, etc., and then use template matching, feature extraction, deep learning and other technologies to identify and classify defects.

[0004] However, the defect detection mechanism still mainly relies on the image information provided by the camera. For some cases where the color difference is not obvious, such as when the color of textile ink is similar to the color of textile, errors are likely to occur during the image processing process, causing the defect detection mechanism to feedback wrong results during detection, making the defect information received by the operator inconsistent with the actual defect information. Summary of the invention

[0005] In view of the deficiencies in the prior art, an object of the present invention is to provide a defect detection mechanism for screen printing and a screen printing process.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: a defect detection mechanism for screen printing, comprising a frame and two guide rails fixedly connected to the top surface of the frame, a bearing platform slidably connected to the guide rails, the upper part of the frame is divided into a detection area and a processing area along the length direction of the guide rails, a screen printing plate is arranged in the processing area, a heating component for heating ink is arranged on the screen printing plate, and a temperature information acquisition module, an image acquisition module, and a display module are arranged on the frame; The temperature information acquisition module includes a first temperature sensor, the first temperature sensor is located at one end of the detection area close to the processing area, and the first temperature sensor is higher than the bearing platform; The image acquisition module includes a camera, the camera is located in the detection area, the camera is higher than the supporting platform, and the camera is located on a side of the first temperature sensor away from the detection area; The display module includes an interactive component and a connecting line, and the first temperature sensor and the camera are both connected to the interactive component via the connecting line.

[0007] The present invention is further configured as follows: the temperature information acquisition module further includes a second temperature sensor, the second temperature sensor is fixedly connected below the support platform, and the second temperature sensor is communicatively connected to the interactive component.

[0008] The present invention is further configured as follows: a photosensor is fixedly connected to one side of the first temperature sensor, a plurality of lamp beads are fixedly connected to the top edge of the support platform, the lamp beads are linearly arrayed along the length direction of the guide rail, the photosensor is located directly above the moving path of the lamp beads, and the photosensor is electrically connected to the interactive component.

[0009] The present invention is further configured as follows: the screen printing plate is composed of a frame and a plurality of metal wires, the heating component is in contact with the metal wires, the metal wires are made of aluminum-copper alloy, and the diameter of the metal wires is not less than 0.08 mm.

[0010] The present invention is further configured as follows: the frame includes an upper frame and a lower frame, the upper frame is fixedly connected to the heating component, the lower frame is fixedly connected to the metal wire, and the upper frame and the lower frame are detachably connected.

[0011] A screen printing process, using the above-mentioned defect detection mechanism, includes the following steps: S1, preheating, heating the ink on the screen printing plate through the heating component; S2, placing, placing the textile on the loading platform; S3, positioning, obtaining the position information of the textile after placement through a camera, and positioning the textile; S4, printing, the carrier table moves from the detection area to the processing area along the guide rail, and the ink is pressed down by the scraper to form a pattern on the surface of the textile; S5, collecting temperature information, when the carrier moves from the processing area to the detection area, detecting the temperature of the surface of the textile by the first temperature sensor, and recording the temperature difference between each block; S6, collecting image information, when the carrier is completely located in the detection area, obtaining image information of the surface of the textile through a camera; S7, comparing, simulating the ink position information through the position information of the higher temperature area obtained in S5, and combining the simulated information with the image information collected in S6 to ensure the accuracy of determining the ink position information; S8, feedback: comparing the ink position information obtained in S7 with the expected ink position, obtaining the number and position of defects, and feeding back to the operator through the interactive component.

[0012] The present invention is further configured as follows: in said S3, the temperature of each part of the textile is detected by a second temperature sensor, so as to detect whether there is an obvious local temperature difference in the textile before printing.

[0013] The present invention is further configured as follows: in S5, the light beads passing under the light sensor are detected by the light sensor, so as to obtain the position of the first temperature sensor relative to the supporting platform.

[0014] The present invention is further configured as follows: in said S3, based on the position of the lamp beads, the accuracy of the placement of the textile is judged by a camera, so as to reduce the defective products caused by the offset when the textile is printed.

[0015] In summary, the present invention has the following beneficial effects: the position of ink is determined by temperature difference, even if the color difference between ink and textile is not obvious, it does not affect information collection, the temperature difference is marked with color to generate a thermal image, and then the image information of the textile surface is collected by a camera, and the thermal image and the image information collected by the camera are processed, and the accuracy of judging the ink distribution is improved by combining the two, so as to find the pattern change defects on the textile caused by the ink position offset, and finally feedback to the operator through the display screen. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a partial cross-sectional view of the present invention; Figure 3 for Figure 2 The enlarged view of point A in the middle; Figure 4 for Figure 2 The enlarged view of point B in the middle; Figure 5 for Figure 2 Enlarged view of point C in the middle.

[0017] In the figure: 1. rack; 2. guide rail; 3. support platform; 4. heating component; 5. first temperature sensor; 6. camera; 7. interactive component; 8. connecting line; 9. second temperature sensor; 10. photosensor; 11. upper frame; 12. lower frame; 13. lamp beads. DETAILED DESCRIPTION

[0018] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0019] Embodiment 1: A defect detection mechanism for screen printing, such as Figure 1-Figure 3 As shown, it includes a frame 1 and two guide rails 2 fixedly connected to the top surface of the frame 1, and a bearing platform 3 is slidably connected to the guide rails 2. The upper side of the frame 1 is divided into a detection area and a processing area along the length direction of the guide rails 2. A silk screen printing plate is provided in the processing area, and a heating component 4 for heating ink is provided on the silk screen printing plate. A temperature information acquisition module, an image acquisition module, and a display module are provided on the frame 1. The temperature information acquisition module includes a first temperature sensor 5, which is located at one end of the detection area close to the processing area, and the first temperature sensor 5 is higher than the bearing platform 3. The image acquisition module includes a camera 6, which is located in the detection area, and the camera 6 is higher than the bearing platform 3. The camera 6 is located on the side of the first temperature sensor 5 away from the detection area. The display module includes an interactive component 7 and a connecting line 8, and the first temperature sensor 5 and the camera 6 are both connected to the interactive component 7 via the connecting line 8.

[0020] Specifically, two guide rails 2 are fixedly connected to the top surface of the frame 1, an operating table is arranged at one end of the frame 1, one end of the guide rail 2 is located in the detection area close to the operating table, and the other end of the guide rail 2 is located in the processing area. In the processing area, from the guide rail 2 upward, there are the screen printing plate and the scraper, the heating component 4 is located on the upper surface of the screen printing plate, the heating component 4 is in the shape of a square frame, the scraper moves horizontally in the frame of the heating component 4, the area framed by the heating component 4 is larger than the area of ​​the top surface of the carrier platform 3, in the detection area, along the direction away from the processing area are the first bracket, the second bracket, and the interactive component 7, the first bracket is used to support the first temperature sensor 5, the first temperature sensor 5 is an infrared temperature sensor, the first temperature sensor 5 is a linear array and the first temperature sensor The direction of the linear array is perpendicular to the length direction of the guide rail 2, the array direction of the infrared temperature sensor is perpendicular to the length direction of the guide rail 2, the first temperature sensor 5 is arranged closer to the processing area, which reduces the distance of the textile from the completion of printing to the detection by the first temperature sensor 5, reduces the time for heat exchange between the outside and the ink and the heat transfer between the ink and the textile, and ensures the detection accuracy of the first temperature sensor 5. The second bracket is used to support the camera 6. The top of the second bracket is slidably connected with a horizontal plate, and the camera 6 is clamped on the horizontal plate. The interactive component 7 includes a shell, a microcomputer, and a display screen. The interactive component 7 is located on one side of the operating table, and the end of the horizontal plate close to the interactive component 7 is integrally formed with a wire hoop for constraining the connecting line 8.

[0021] like Figure 1-Figure 4As shown, the temperature information acquisition module also includes a second temperature sensor 9, which is fixedly connected to the bottom of the supporting platform 3. The second temperature sensor 9 is communicatively connected to the interactive component 7. Specifically, the second temperature sensor 9 is an infrared temperature sensor. A plurality of through holes are arranged on the supporting platform 3. A slider is slidably connected to the guide rail 2. A groove is provided on the top surface of the slider. The second temperature sensors 9 are arranged in a rectangular array on the bottom surface of the groove. The supporting platform 3 is fixedly connected to the top surface of the slider. The second temperature sensor 9 corresponds to the through hole, so that the second temperature sensor 9 can detect the temperature of the textile above the supporting platform 3.

[0022] like Figure 1-Figure 3 As shown, a photosensor 10 is fixedly connected to one side of the first temperature sensor 5, and a plurality of lamp beads 13 are fixedly connected to the edge of the top surface of the supporting platform 3. The lamp beads 13 are linearly arrayed along the length direction of the guide rail 2. The photosensor 10 is located directly above the moving path of the lamp beads 13. The photosensor 10 is electrically connected to the interactive component 7. Specifically, the lamp beads 13 are embedded in the supporting platform 3, and a power supply is fixed on the bottom surface of the groove. The bottom end of the lamp beads 13 is electrically connected to the power supply. The photosensor 10 and the first temperature sensor 5 are installed on the same surface of the first bracket. The position on the supporting platform 3 detected by the first temperature sensor 5 is determined based on the lamp beads 13 passing under the photosensor 10. The photosensor 10 is located at the extension of the array direction of the first temperature sensor 5.

[0023] like Figure 1 , Figure 4 As shown, the screen printing plate is composed of a frame and a plurality of metal wires, the heating component 4 is in contact with the metal wires, the metal wires are made of aluminum-copper alloy, the diameter of the metal wires is not less than 0.08 mm, the frame includes an upper frame 11 and a lower frame 12, the upper frame 11 is fixedly connected to the heating component 4, the lower frame 12 is fixedly connected to the metal wires, the upper frame 11 and the lower frame 12 are detachably connected, specifically, both sides of the lower frame 12 and the upper frame 11 are provided with clamping members, the cross section of the clamping member is C-shaped, and a clamping bolt is provided through the top surface of the clamping member, and the lower frame 1 2 is in contact with the inner wall of the clamping member, the bottom surface of the upper frame 11 is in contact with the top surface of the lower frame 12, the top surface of the upper frame 11 is in contact with the bottom surface of the clamping bolt, the mesh formed by the metal wire is fixed to the lower frame 12, when the upper frame 11 is fixed to the lower frame 12, the heating component 4 is fitted with the mesh, when the mesh needs to be replaced, the lower frame 12 can be pulled out by loosening the clamping bolt, the aluminum-copper alloy has good thermal conductivity, and the thermal conductivity of the metal wire is improved by increasing the diameter of the metal wire, thereby ensuring the heating effect of the heating component 4 on the ink.

[0024] Embodiment 2: A screen printing process using the above-mentioned defect detection mechanism comprises the following steps: S1, preheating, heating the ink on the screen printing plate by heating component 4; S2, placing, placing the textile on the carrying platform 3; S3, positioning, obtaining the position information of the textile after placement through the camera 6, and positioning the textile; S4, printing, the carrier 3 moves from the detection area to the processing area along the guide rail 2, and the ink is pressed down by the scraper to form a pattern on the surface of the textile; S5, collecting temperature information, when the carrier 3 moves from the processing area to the detection area, the temperature of the surface of the textile is detected by the first temperature sensor 5, and the temperature difference between each block is recorded; S6, collecting image information, when the carrier platform 3 is completely located in the detection area, obtaining image information of the surface of the textile through the camera 6; S7, comparing, simulating the ink position information through the position information of the higher temperature area obtained in S5, and combining the simulated information with the image information collected in S6 to ensure the accuracy of determining the ink position information; S8, feedback: compare the ink position information obtained in S7 with the expected ink position, obtain the number and position of defects, and feed back to the operator through the interactive component 7.

[0025] Specifically, the heating component 4 is started first to heat the metal wire and the ink. In the subsequent links, the heating component 4 is kept heated to ensure that the ink can carry enough heat when leaving the screen printing plate. On the one hand, the possibility of ink blocking the screen is reduced, and on the other hand, it is convenient to detect the position of the ink on the textile by temperature change through the first temperature sensor 5. When the textile arrives on the carrier 3, the relative position of the textile with respect to the carrier 3 is obtained by the camera 6, and then the textile is sent to the processing area through the carrier 3. The silk screen scraper squeezes the heated ink from the screen, and the falling ink forms a pattern on the textile. The carrier 3 drives the textile with the pattern to move outward and passes under the first temperature sensor 5. The temperature of the location where the fabric is covered with ink is higher than that of other locations, because the location of the ink is determined by the temperature difference. Even if the color difference between the ink and the textile is not obvious, it does not affect the collection of information. When the carrier 3 is completely located in the detection area, it means that the first temperature sensor 5 has completed the detection of the entire textile on the carrier 3, and generates a thermal image by color marking the temperature difference. At this time, the camera 6 is used to collect image information of the textile surface, and the thermal image and the image information collected by the camera 6 are processed. The combination of the two can improve the accuracy of judging the ink distribution, so as to find the pattern change defects on the textile caused by the ink position offset, and finally feedback to the operator through the display screen.

[0026] In S3, the temperature of each part of the textile is detected by the second temperature sensor 9 to detect whether there is an obvious local temperature difference in the textile before printing. Specifically, the second temperature sensor 9 detects the temperature of the textile placed on the carrier 3 through the through hole. The temperature of the textile is measured before S4 to avoid obvious temperature differences between various blocks of the textile before contacting the ink due to external factors, resulting in a difference between the hot zone detected by the subsequent first temperature sensor 5 and the actual position of the ink.

[0027] In S5, the light-sensitive sensor 10 detects the lamp bead 13 passing under the light-sensitive sensor 10 to obtain the position of the first temperature sensor 5 relative to the supporting platform 3. In S3, based on the position of the lamp bead 13, the accuracy of the placement of the textile is judged by the camera 6 to reduce the defective products caused by the offset when the textile is printed. Specifically, the position of the lamp bead 13 is detected by the light-sensitive sensor 10, and the position of the textile detected by the first temperature sensor 5 is determined based on the position of the lamp bead 13 to ensure that the output thermal image and the textile can accurately correspond. At the same time, when placing the textile, the camera 6 determines whether the placement of the textile is accurate through the relative position of the lamp bead 13 and the textile, thereby ensuring that the printed pattern falls accurately at the desired position when printing.

[0028] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A defect detection mechanism for screen printing, comprising a frame (1) and two guide rails (2) fixedly connected to the top surface of the frame (1), a bearing platform (3) being slidably connected to the guide rails (2), the upper part of the frame (1) being divided into a detection area and a processing area along the length direction of the guide rails (2), a screen printing plate being arranged in the processing area, characterized in that: The screen printing plate is provided with a heating component (4) for heating ink, and the frame (1) is provided with a temperature information acquisition module, an image acquisition module, and a display module; The temperature information acquisition module comprises a first temperature sensor (5), the first temperature sensor (5) being located at one end of the detection area close to the processing area, and the first temperature sensor (5) being higher than the supporting platform (3); The image acquisition module comprises a camera (6), the camera (6) is located in the detection area, the camera (6) is higher than the support platform (3), and the camera (6) is located on a side of the first temperature sensor (5) away from the detection area; The display module comprises an interactive component (7) and a connecting line (8), and the first temperature sensor (5) and the camera (6) are both connected to the interactive component (7) via the connecting line (8).

2. The defect detection mechanism for screen printing according to claim 1, characterized in that: The temperature information acquisition module further comprises a second temperature sensor (9), the second temperature sensor (9) being fixedly connected below the support platform (3), and the second temperature sensor (9) being communicatively connected to the interaction component (7).

3. The defect detection mechanism for screen printing according to claim 1, characterized in that: A photosensitive sensor (10) is fixedly connected to one side of the first temperature sensor (5); a plurality of lamp beads (13) are fixedly connected to the edge of the top surface of the support platform (3); the lamp beads (13) are arranged in a linear array along the length direction of the guide rail (2); the photosensitive sensor (10) is located directly above the moving path of the lamp beads (13); and the photosensitive sensor (10) is electrically connected to the interactive component (7).

4. The defect detection mechanism for screen printing according to claim 1, characterized in that: The screen printing plate is composed of a frame and a plurality of metal wires. The heating component (4) is in contact with the metal wires. The metal wires are made of an aluminum-copper alloy. The diameter of the metal wires is not less than 0.08 mm.

5. The defect detection mechanism for screen printing according to claim 4, characterized in that: The frame comprises an upper frame (11) and a lower frame (12); the upper frame (11) is fixedly connected to the heating component (4); the lower frame (12) is fixedly connected to the metal wire; and the upper frame (11) and the lower frame (12) are detachably connected.

6. A screen printing process using a defect detection mechanism as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1, preheating, heating the ink on the screen printing plate by a heating component (4); S2, placing, placing the textile on the supporting platform (3); S3, positioning, obtaining the position information of the textile after placement through the camera (6), and positioning the textile; S4, printing, the carrier platform (3) moves from the detection area to the processing area along the guide rail (2), and the ink is pressed down by a scraper to form a pattern on the surface of the textile; S5, collecting temperature information, when the carrier (3) moves from the processing area to the detection area, detecting the temperature of the surface of the textile by means of the first temperature sensor (5), and recording the temperature difference between the various blocks; S6, collecting image information, when the support platform (3) is completely located in the detection area, obtaining image information of the surface of the textile through the camera (6); S7, comparing, simulating the ink position information through the position information of the higher temperature area obtained in S5, and combining the simulated information with the image information collected in S6 to ensure the accuracy of determining the ink position information; S8, feedback: comparing the ink position information obtained in S7 with the expected ink position, obtaining the number and position of defects, and feeding back to the operator through the interactive component (7).

7. The screen printing process according to claim 6, characterized in that: In S3, the temperature of each part of the textile is detected by a second temperature sensor (9) to detect whether there is an obvious local temperature difference in the textile before printing.

8. The screen printing process according to claim 6, characterized in that: In S5, the light bead (13) passing under the light sensor (10) is detected by the light sensor (10), thereby obtaining the position of the first temperature sensor (5) relative to the supporting platform (3).

9. The screen printing process according to claim 6, characterized in that: In S3, based on the position of the lamp beads (13), the accuracy of textile placement is judged by the camera (6), thereby reducing defective products caused by deviation during textile printing.

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