Visual hollowing detection equipment and method based on low-temperature-resistant plywood processing

Abstract

The invention discloses visual hollowing detection equipment and method based on low-temperature-resistant plywood processing, and relates to the technical field of visual hollowing detection of plywood. The visual hollowing detection equipment based on low-temperature-resistant plywood processing comprises an annular light diffusion device, the annular light diffusion device is used for arranging a light source with multiple inclination angles and uniformly irradiating softened light to the surface of a plywood body, and a wind heating device is used for maintaining the temperature in a box body at 16-22 DEG C and performing double-section blowing on the plywood body entering the box body, the rotary wiping dew self-drying device is used for stretching out to wipe the surface of the board body under the rotation effect and the wind power effect and then drying the board body after shrinking. According to the visual hollowing detection equipment and method based on low-temperature-resistant plywood processing, the rotary wiping water dew self-drying device, the rough blowing device and the fine blowing device form mechanical wiping and hot air blowing dual drying, the annular light diffusion device provides multi-angle soft illumination, the equipment is adaptive to a special environment for low-temperature-resistant plywood processing, and the precision of a detection result is improved.

Description

Technical Field

[0001] This invention relates to the field of visual hollow detection technology for plywood, and specifically to a visual hollow detection device and method based on low-temperature resistant plywood processing. Background Technology

[0002] The visual hollow detection equipment based on low-temperature resistant plywood processing uses machine vision as its core, integrating image acquisition, algorithm analysis, data processing and other technical modules. It is equipped with a high-definition camera, light source system and dedicated image algorithm to accurately identify surface texture abnormalities, light transmission differences or structural reflection changes caused by hollowness.

[0003] Referring to Chinese Patent Publication No. CN222734083U, a device for detecting hollow spots in sheet metal production includes a base plate. Two sets of placement plates are arranged on the left and right sides of the upper surface of the base plate. Multiple sets of electric push rods are fixedly connected to the lower side of the left surface of each placement plate. A sensing area is formed on the upper side of the left surface of each placement plate near the electric push rods. A motor is fixedly connected to the front surface of the base plate. A detection component is arranged at the center of the upper surface of the base plate. The detection component includes a laser. A reciprocating lead screw is fixedly connected to the output shaft of the motor, and a moving block is threaded onto the outer wall of the reciprocating lead screw. In this invention, by utilizing the interoperability of the components in the detection component through their connections, the detection area of ​​the laser when detecting processed sheets is increased, improving the efficiency of preventing hollow spots in the processed sheets. Furthermore, the laser can be adapted to detect processed sheets of different thicknesses, thus expanding the applicability of the detection component.

[0004] In low-temperature environments, fine water vapor easily condenses on the surface of the board, which, when combined with the coating, forms irregular light and shadow reflection areas. The image algorithms of vision devices have difficulty distinguishing these reflective areas from hollow defects, especially for slight hollows, where the visual difference between surface undulations and coating reflections is minimal, easily leading to misjudgment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a visual hollow detection device and method based on low-temperature resistant plywood processing. It achieves dual drying through mechanical wiping and hot air blowing by using a self-drying device for water dew and coarse blowing and fine blowing. A ring light diffusion device provides multi-angle softened lighting, adapting to the special environment of low-temperature resistant plywood processing and improving the accuracy of detection results.

[0006] Technical Solution: To achieve the above objectives, the present invention is implemented through the following technical solution: A visual hollow detection device based on low-temperature resistant plywood processing, comprising: a box body, wherein a conveying assembly is provided inside the box body, both ends of the conveying assembly pass through the box body and are located outside the box body, a camera is connected to the top wall of the box body, a ring light diffuser is provided outside the camera, the ring light diffuser is used to set a light source with multiple tilt angles and to uniformly irradiate the surface of the board body with softened light, a dehumidifier is connected to the inner wall of the box body, a wind-heating device is fixedly connected to the inner wall of one end of the box body, the wind-heating device is used to maintain the temperature inside the box body at 16-22℃ and to perform two-stage blowing on the board body entering the box body, and a rotating dew self-drying device is provided at the feed port of the box body, the rotating dew self-drying device is used to extend under the action of rotation and wind to wipe the surface of the board body and then retract to dry it.

[0007] Preferably, the ring light diffusion device, the air heating device, and the dew-drying device are all located inside the box, with the air heating device located between the ring light diffusion device and the dew-drying device.

[0008] Preferably, the ring light diffuser includes: a ring rail located below the camera; the inner wall of the ring rail is connected to a sliding sleeve via a fixing plate; the inner wall of the ring rail is connected to one side of the camera via another fixing plate; several positioning plates are equidistantly distributed in a circumferential direction between the two sliding rails; both sides of each positioning plate are fixedly connected to the side of the two sliding rails that are close to each other; several diffuse reflective plates are equidistantly distributed in a circumferential direction at the bottom edge of the sliding rail; a sliding groove is provided on one side of the sliding rail; several rotating connecting parts are slidably connected in a circumferential direction to the sliding groove; and a diffuse light source is connected to the bottom of each rotating connecting part.

[0009] Preferably, the rotating connector includes: a slider, which is slidably connected to a groove, with side plates fixedly connected to the bottom of both ends of the slider, a sleeve fixedly connected to one side of one side plate, a rotating rod rotatably connected to the sleeve, one end of the rotating rod passing through a connecting plate and another side plate in sequence and being threadedly connected to a nut, the bottom of the connecting plate being fixedly connected to a diffuse light source, and a threaded hole being opened at the top of the slider, with the bottom end of the threaded rod passing through the round hole of a positioning plate and being threadedly connected to the threaded hole.

[0010] Preferably, there are several groups of diffuse light sources, each with a different tilt angle. The angles between each group of diffuse light sources and the vertical direction are 25°, 40°, 55°, 70°, and 85°, respectively. Each group of diffuse light sources is equidistant from each other in the circumferential direction, and the number of diffuse light sources in each group is the same and they are distributed at intervals.

[0011] Preferably, the air-heating device includes: an air box, the side of which is fixedly connected to the inner wall of the box body, a second air hole and a fourth air hole through the top of the air box, the second air hole being connected to a hot air blower outside the box body through a first pipe, each fourth air hole being connected to the top of the air duct through a second pipe, first air holes being equidistantly opened on the side of the air duct, the bottom of the air duct being fixedly connected to the bottom wall of the box body through a fixing column, each first air hole being connected to a heat dissipation pipe through a solenoid valve, the bottom of the air box being connected to a coarse blowing pipe and a fine blowing pipe, and several third air holes being equidistantly opened on the top of each heat dissipation pipe.

[0012] Preferably, the heat dissipation pipe is a horizontally placed U-shaped pipe, which is adapted to the box body. The heat dissipation pipe is used to evenly distribute hot air to all parts of the box body. Both ends of the heat dissipation pipe are connected to a fan duct. The width of the coarse blowing pipe is 2.5-5 times the width of the fine blowing pipe. The distance between the coarse blowing pipe and the box body inlet is less than the distance between the fine blowing pipe and the box body inlet. The angle between the coarse blowing pipe and the horizontal plane is 18-23°, and the angle between the fine blowing pipe and the horizontal plane is 32-41°.

[0013] Preferably, the self-drying device for wiping away dew includes: a motor, the fixed end of which is fixedly connected to the inner wall of the box, the rotating end of which is rotatably connected to a rotating shaft, and several rotating plates equidistantly connected to the side of the rotating shaft in a circumferential direction. Each rotating plate has an air groove at its bottom and several equidistant air guide holes on one side of each rotating plate. The top wall of each rotating plate is connected to a fan plate by a spring. The fan plate is slidably connected to the inner wall of the air groove. A limit baffle is connected to the interior of the middle of each rotating plate. An air receiving hole is opened at the top of each fan plate. A hot drying pipe is connected to the bottom of each fan plate. A heat-gathering pipe is fixedly connected to the inner wall of each hot drying pipe. Two wiping plates are connected to the middle of the bottom of each fan plate.

[0014] Preferably, the distance between the two wiping plates is less than the width of the wind-driven plate, and the projection of one end of the air receiving hole is trapezoidal, with the length of the top end of the trapezoid being less than the length of the bottom end. When the wind-driven plate moves to the lowest point, the bottom end of the wiping plate contacts the surface of the plate. When the wind-driven plate abuts against the limiting baffle, the bottom end of the wiping plate is located in the heat-collecting tube. A heat-conducting strip is fixedly connected to the inner wall of the rotating plate, and the bottom of the heat-conducting strip is connected to the bottom of the heat-collecting tube.

[0015] A visual hollow detection method based on low-temperature resistant plywood processing is applied to a visual hollow detection device based on low-temperature resistant plywood processing. The plywood is moved into the box by a conveyor assembly and approaches the self-drying device. The rotating end of the motor drives all the rotating plates, hot drying pipes, wiping plates, and pneumatic plates to rotate synchronously. During the rotation of the rotating plates, the air guide holes are directly facing the coarse blowing pipe. The hot air blown out by the coarse blowing pipe and the fine blowing pipe enters the air groove through the air guide holes. The air in the air groove enters the air receiving hole. During the process of the pneumatic plate turning to the lowest point, the pneumatic plate is subjected to air pressure and its own... Under the influence of gravity and centrifugal force, the wiping plate slides down along the direction of the air trough. The spring is stretched, and the bottom end of the wiping plate contacts the surface of the plate. After the air-driven plate moves away from the lowest point, it moves up along the direction of the air trough under the drive of the spring. The air-driven plate abuts against the limiting baffle. The bottom end of the air-driven plate moves into the heat-collecting tube and is dried. The plate continues to move towards the center of the plate. The plate is wiped by the coarse blow pipe and the fine blow pipe in sequence. The plate moves to the middle of the box. The ring light diffusion device evenly illuminates the surface of the plate with softened light from multiple angles. The camera captures images of the plate in real time and identifies hollow areas.

[0016] Beneficial Effects: This invention provides a visual hollow detection device and method based on low-temperature resistant plywood processing. Compared with existing technologies, it has the following beneficial effects: 1. The self-drying device for water dew, combined with coarse and fine blowing, forms a dual drying process of mechanical wiping and hot air blowing. The wiping device drives the wiping plate to adhere and wipe using wind pressure, gravity, and centrifugal force, and is further dried by spring reset and hot drying tubes, ensuring that there is no visible water dew on the board surface. The graded design of coarse and fine blowing, combined with optimized angle and distance, thoroughly removes residual moisture and moisture from the grain gaps, preventing moisture from causing the adhesive layer of the board to become damp and fail, while also eliminating the interference of moisture on image detection. The ring light diffusion device provides multi-angle softened illumination, avoiding the light and shadow interference of the plywood wood grain, allowing the hollow area to form a clear feature difference from the normal area, and accurately identifying hollow defects. The entire process is completed inside the box, reducing the impact of external dust and temperature and humidity changes on the drying effect and detection accuracy, especially suitable for the special environment of low-temperature resistant plywood processing, ensuring stable operation of the equipment and reliable detection results.

[0017] 2. The heat dissipation pipes are compatible with the housing. Hot air from the heat dissipation pipes is evenly blown into all parts of the housing through numerous equidistantly distributed third air vents, maintaining the temperature inside the housing at 16-22℃. Maintaining a constant temperature of 16-22℃ lowers the dew point and prevents condensation. This constant temperature environment also prevents the board material from shrinking and deforming due to sudden temperature changes, protecting its special coatings, such as low-temperature resistant hydrophobic and matte coatings, from damage by high temperatures or strong winds. Visual inspection requires stable temperature and surface conditions; a constant temperature maintains stable parameters for both the board material and the equipment, avoiding inspection deviations caused by temperature fluctuations. 3. Utilizing the combined forces of wind pressure, gravity, and centrifugal force, the wiping plate slides down, automatically adapting to slight unevenness on the board surface to ensure a tight fit and remove moisture. The spring-loaded connection design allows for gentle and adjustable wiping force, preventing scratches or damage to the adhesive layer. Coarse and fine hot air flows through a guide path, powering the wiping plate's movement and simultaneously performing mechanical wiping and hot air drying, significantly improving drying efficiency. Hot air recycling reduces energy waste and lowers operating costs. The spring-driven wiping plate automatically detaches from the board without affecting the production line; after resetting, the wiping plate enters the heat-concentrating tube for drying, ensuring each wipe is dry and preventing secondary contamination from residual moisture. The motor drives all components to move synchronously, precisely matching the board's movement rhythm to meet the needs of continuous industrial operation. The entire process involves low-temperature, gentle treatment without high-temperature baking, protecting the structural stability and adhesive performance of sensitive boards such as low-temperature resistant plywood.

[0018] 4. The trapezoidal structure of the air intake, wider at the bottom and narrower at the top, acts like a funnel to gather hot air, increasing its speed and creating a stable positive pressure on the lower surface of the fan plate, precisely converting it into downward thrust. When the fan plate falls upward under the spring tension, the inner slope of the trapezoidal hole creates a damping effect, allowing the airflow to exit slowly and preventing the fan plate from colliding with the limit baffle, thus reducing noise and protecting the components. Attached Figure Description

[0019] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments of the present application and, together with the specification, further serve to explain the principles of the present application and enable those skilled in the art to implement and use the present application.

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of the present invention.

[0022] Figure 2 This is a separate diagram of the box body, the conveying components, and the internal structure of the box body.

[0023] Figure 3 This is a schematic diagram of the structure of the ring light diffusion device, the air heating device, and the water-drying device.

[0024] Figure 4 This diagram shows the separation of the ambient light diffusion device, the air-heating device, the water-drying device, and the dehumidifier.

[0025] Figure 5 This is a schematic diagram of the ring light diffuser.

[0026] Figure 6 This is a partial diagram of a ring light diffuser structure.

[0027] Figure 7 This is a schematic diagram of the rotating connector.

[0028] Figure 8 This is a schematic diagram of the air-heated device.

[0029] Figure 9 This is an exploded view of a wind-heated device.

[0030] Figure 10 This is a structural diagram of the air box, coarse air blower, fine air blower, and heat dissipation pipe.

[0031] Figure 11 This is a schematic diagram of the self-drying device for transferring water droplets.

[0032] Figure 12 This is a diagram showing the separation of the self-drying device for wiping away dew.

[0033] Figure 13 for Figure 12 A cross-sectional view of the entire assembly, including the central baffle, pneumatic plate spring, hot drying tube, guide plate, and limiting baffle.

[0034] The reference numerals in the diagram are as follows: 11. Box body; 12. Conveying assembly; 13. Control console; 14. Workbench; 15. Camera; 2. Ring light diffuser; 21. Ring rail; 22. Sliding sleeve; 23. Positioning plate; 24. Fixing plate; 25. Diffuse reflector; 26. Slide groove; 27. Diffuse light source; 28. Rotating connector; 281. Slider; 282. Side plate; 283. Rotating rod; 284. Sleeve; 285. Nut; 286. Connecting plate; 287. Threaded hole; 288. Threaded rod; 3. Heating device; 31. Air box. 32. First pipe; 33. Hot air blower; 34. Coarse blowing pipe; 35. Fine blowing pipe; 36. Second pipe; 37. Air duct; 38. Heat dissipation pipe; 39. First air hole; 4. Rotary wiping water dew self-drying device; 41. Motor; 42. Rotating shaft; 43. Rotating plate; 44. Wiping plate; 45. Pneumatic plate; 46. Spring; 47. Hot drying pipe; 48. Heat collection plate; 49. Limiting baffle; 5. Dehumidifier; 61. Fixed column; 62. Second air hole; 63. Third air hole; 64. Fourth air hole; 71. Air guide hole; 72. Air receiving hole.

[0035] As shown in the figure, specific structures and devices are labeled in the figure to clearly illustrate the structure of the embodiments of the present invention. However, this is only for illustrative purposes and is not intended to limit the present invention to the specific structure, device and environment. Those skilled in the art can adjust or modify these devices and environments according to specific needs, and such adjustments or modifications are still included in the scope of the appended claims. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] like Figure 1 - Figure 13 As shown, the present invention provides a visual hollow detection device and method based on low-temperature resistant plywood processing, comprising: a box body 11, a conveying assembly 12 disposed inside the box body 11, the two ends of the conveying assembly 12 passing through the box body 11 and located outside the box body 11, a camera 15 connected to the top wall of the box body 11, a ring light diffuser 2 disposed outside the camera 15, the ring light diffuser 2 being used to set up a light source with multiple tilt angles and to uniformly irradiate the surface of the board with softened light, a dehumidifier 5 being connected to the inner wall of the box body 11, a wind-heating device 3 being fixedly connected to the inner wall of one end of the box body 11, the wind-heating device 3 being used to maintain the temperature inside the box body 11 at 16-22℃ and to perform two-stage blowing on the board entering the box body 11, and a rotating dew self-drying device being disposed at the feed inlet of the box body 11, the rotating dew self-drying device being used to extend under the action of rotation and wind to wipe the surface of the board and then retract to dry it.

[0038] In low-temperature environments, the temperature difference between the inside and outside of the box 11 can easily cause condensation on the surface of the board. This condensation may also remain due to electrostatic adsorption, forming a reflective area that interferes with visual inspection. Maintaining a constant temperature of 16-22℃ can reduce the dew point at the source and prevent condensation. Dual-stage purging can precisely remove surface condensation and electrostatic residue, eliminating the impact of condensation on inspection accuracy. When the production line speed is ≥10m / min, single purging is insufficient for rapid and thorough water removal. Dual-stage purging, with its strong airflow for coarse removal and gentle airflow for fine removal, adapts to the high-speed pace, ensuring the board dries quickly. A constant temperature environment of 16-22℃ prevents the board from shrinking and deforming due to sudden temperature changes, protecting its special coatings, such as low-temperature resistant hydrophobic and matte coatings, from damage by high temperatures or strong winds. Visual inspection requires stable temperature and surface conditions. Constant temperature maintains stable board and equipment parameters, avoiding inspection deviations caused by temperature fluctuations. Dual-stage purging combined with ion air can simultaneously remove dust from the board surface, reducing misjudgments caused by impurities and condensation, and improving defect identification accuracy.

[0039] The ring light diffusion device 2, the air heating device 3, and the dew-drying device are all located inside the box 11, with the air heating device 3 located between the ring light diffusion device 2 and the dew-drying device.

[0040] The ring light diffuser 2 includes: a ring rail 21 located below the camera 15; the inner wall of the ring rail 21 is connected to the sliding sleeve 22 via a fixing plate 24; the inner wall of the ring rail 21 is connected to one side of the camera 15 via another fixing plate 24; several positioning plates 23 are arranged equidistantly in the circumferential direction between the two sliding rails; both sides of each positioning plate 23 are fixedly connected to the side of the two sliding rails that are close to each other; several diffuse reflective plates 25 are equidistantly distributed in the circumferential direction at the bottom edge of the sliding rail; a sliding groove 26 is provided on one side of the sliding rail; several rotating connecting parts 28 are slidably connected to the sliding groove 26; and a diffuse light source 27 is connected to the bottom of each rotating connecting part 28.

[0041] The rotating connector 28 includes: a slider 281, which is slidably connected to the slide groove 26. Side plates 282 are fixedly connected to the bottom of both ends of the slider 281. A sleeve 284 is fixedly connected to one side of one side plate 282. A rotating rod 283 is rotatably connected to the sleeve 284. One end of the rotating rod 283 passes through the connecting plate 286 and the other side plate 282 in sequence and is threadedly connected to the nut 285. The bottom of the connecting plate 286 is fixedly connected to the diffuse light source 27. A threaded hole 287 is opened at the top of the slider 281. The bottom end of the threaded rod 288 passes through the round hole of a positioning piece 23 and is threadedly connected to the threaded hole 287.

[0042] There are several groups of diffuse light sources 27, and the tilt angle of each group of diffuse light sources 27 is different. The angles between each group of diffuse light sources 27 and the vertical direction are 25°, 40°, 55°, 70° and 85°, respectively. Each group of diffuse light sources 27 is equidistantly distributed in the circumferential direction. The number of diffuse light sources 27 in each group is the same and they are distributed at intervals.

[0043] Each group of light sources is distributed at a gradient angle of 25°-85°, comprehensively covering the surface of the board from low to high angles. Combined with equidistant and spaced circular arrangement, the alternating distribution of different angle groups avoids excessively strong or weak local illumination. Whether it's the center, edge, or corner of the board, it can be uniformly illuminated, completely eliminating shadows and blind spots, reducing missed detections caused by uneven lighting. In low-temperature environments, the direction of moisture and coating reflections on the board surface is random. Multiple groups of diffused light at different angles neutralize these reflections from various directions, effectively preventing overexposure in reflective areas and making the grayscale difference between defects and the background clearer, significantly reducing the probability of algorithm misjudgment. Minor defects such as hollow areas and scratches have very small surface undulations, making them difficult to highlight with a single angle of light. However, the gradient angle of 25°~85° can characterize the defect from different dimensions. Low-angle light highlights the side shadows of the defect, medium-angle light restores the true grayscale of the defect, and high-angle light supplements details. After superposition, the outline and layering of the defect are more obvious, allowing the algorithm to extract features more easily, making it less likely to miss even tiny defects. Whether the material is matte, reflective, or has a hydrophobic coating, the brightness of different angle groups can be adjusted to suit the material without changing the light source. Even when the material is slightly tilted or shifted in position on the production line, the full-angle coverage of the illumination field ensures stable imaging and prevents detection deviations due to changes in the material's orientation.

[0044] The air-heating device 3 includes: an air box 31, the side of which is fixedly connected to the inner wall of the box body 11; a second air hole 62 and a fourth air hole 64 are opened through the top of the air box 31; the second air hole 62 is connected to the hot air blower 33 outside the box body 11 through a first pipe 32; each fourth air hole 64 is connected to the top of the air duct 37 through a second pipe 36; first air holes 39 are opened at equal intervals on the side of the air duct 37; the bottom of the air duct 37 is fixedly connected to the bottom wall of the box body 11 through a fixing post 61; each first air hole 39 is connected to a heat dissipation pipe 38 through a solenoid valve; a coarse blowing pipe 34 and a fine blowing pipe 35 are connected to the bottom of the air box 31; and several third air holes 63 are opened through the top of each heat dissipation pipe 38 at equal intervals.

[0045] The heat dissipation pipe 38 is a horizontally placed U-shaped pipe. The heat dissipation pipe 38 is adapted to the box body 11. The heat dissipation pipe 38 is used to evenly distribute hot air to all parts of the box body 11. Both ends of the heat dissipation pipe 38 are connected to a fan duct 37. The width of the coarse blowing pipe 34 is 2.5-5 times the width of the fine blowing pipe 35. The distance between the coarse blowing pipe 34 and the feed inlet of the box body 11 is less than the distance between the fine blowing pipe 35 and the feed inlet of the box body 11. The angle between the coarse blowing pipe 34 and the horizontal plane is 18-23°, and the angle between the fine blowing pipe 35 and the horizontal plane is 32-41°.

[0046] The coarse blow pipe 34 is 2.5-5 times wider than the fine blow pipe 35 and is closer to the inlet. When the board just enters, the hot air from the coarse blow pipe 34 can quickly peel off most of the liquid water film and droplets on the surface with a wider coverage area and stronger airflow, achieving rapid dehydration over a large area. The fine blow pipe 35 is farther from the inlet. After the coarse blow, any remaining fine water droplets and water film will converge under gravity, and then be thoroughly removed by precise airflow. It can also work with ion air to eliminate static electricity, preventing water vapor from adsorbing due to static electricity, ultimately ensuring that the board surface is dry and clean when it enters the testing area. The small angle of 18-23° for the coarse blow allows the airflow to be closer to the board surface, forming strong shearing force, suitable for peeling off stubborn water films. The larger angle of 32-41° for the fine blow concentrates the airflow energy on the surface, efficiently removing residue while avoiding strong airflow that could cause board vibration or scratches to the coating. The distance between the coarse blowing, fine blowing and the detection area increases sequentially, allowing time for the water to flow and drip, avoiding secondary pollution caused by the water droplets being blown back to the dried area by the later blowing, and at the same time not interfering with the stable airflow field of the detection area.

[0047] The self-drying device for wiping away dew includes: a motor 41, the fixed end of which is fixedly connected to the inner wall of the box 11; a rotating shaft 42 is rotatably connected to the rotating end of the motor 41; several rotating plates 43 are equidistantly connected to the side of the rotating shaft 42 in a circumferential direction; each rotating plate 43 has an air groove at its bottom; several equidistant air guide holes 71 are opened on one side of each rotating plate 43; the top wall of each rotating plate 43 is connected to a wind-driven plate 45 by a spring 46; the wind-driven plate 45 is slidably connected to the inner wall of the air groove; a limit baffle 49 is connected to the interior of the middle of each rotating plate 43; an air receiving hole 72 is opened at the top of each wind-driven plate 45; a heat-drying pipe 47 is connected to the bottom of each wind-driven plate 45; a heat-gathering pipe is fixedly connected to the inner wall of each heat-drying pipe 47; and two wiping plates 44 are connected to the middle of the bottom of each wind-driven plate 45.

[0048] The distance between the two wiping plates 44 is less than the width of the wind-driven plate 45. The projection of one end of the air receiving hole 72 is trapezoidal, and the length of the top of the trapezoid is less than the length of the bottom of the trapezoid. When the wind-driven plate 45 moves to the lowest point, the bottom of the wiping plate 44 contacts the plate surface. When the wind-driven plate 45 abuts against the limiting baffle 49, the bottom of the wiping plate 44 is located in the heat-collecting tube. A heat-conducting strip is fixedly connected to the inner wall of the rotating plate 43, and the bottom of the heat-conducting strip is connected to the bottom of the heat-collecting tube.

[0049] The trapezoidal structure of the air intake vent 72, with a larger bottom and a smaller top, can gather hot air like a funnel, increasing airflow speed and creating stable positive pressure on the lower surface of the fan plate 45, precisely converting it into downward thrust. Simultaneously, the trapezoidal slope ensures more even force distribution, preventing the fan plate 45 from tilting or jamming during descent. It is highly responsive and adaptable to various wind conditions, even weak hot air. The efficient trapezoidal windward surface quickly captures airflow and converts it into downward pressure, allowing the fan plate 45 to start rapidly. It can automatically adjust the force when facing fluctuating airflow speeds, preventing overshoot or loss of control, thus enhancing its adaptability. The descent is smooth, with low noise and protection against foreign objects. When the hot air weakens or disappears, as the fan plate 45 falls upward under the tension of the spring 46, the inner slope of the trapezoidal vent creates a damping effect, allowing the airflow to exit slowly and preventing the fan plate 45 from colliding with the limiting baffle 49, reducing noise and protecting components. At the same time, its shape, which is wider on the outside and narrower on the inside, makes it less likely for dust and small particles to get stuck, making it easy to clean and ensuring long-term stable operation.

[0050] A visual hollow detection method based on low-temperature resistant plywood processing is applied to a visual hollow detection device based on low-temperature resistant plywood processing. The plywood is moved into the box 11 by the conveying assembly 12. The plywood is close to the self-drying device 4. The rotating end of the motor 41 drives all the rotating plates 43, the hot drying tube 47, the wiping plate 44, and the pneumatic plate 45 to rotate synchronously. During the rotation of the rotating plate 43, the air guide hole 71 is directly facing the coarse blowing pipe 34. The hot air blown out by the coarse blowing pipe 34 and the fine blowing pipe 35 enters the air groove through the air guide hole 71. The air in the air groove enters the air receiving hole 72. During the process of the pneumatic plate 45 turning to the lowest point, the pneumatic plate 45 is subjected to air pressure. Under the action of its own gravity and centrifugal force, the wiping plate 44 slides down along the direction of the air groove, the spring 46 is stretched, and the bottom end of the wiping plate 44 contacts the surface of the plate. After the wind-driven plate 45 moves away from the lowest point, the wind-driven plate 45 moves up along the direction of the air groove under the action of the spring 46. The wind-driven plate 45 abuts against the limiting baffle 49. The bottom end of the wind-driven plate 45 moves into the heat-collecting tube and is dried. The plate continues to move towards the center of the plate. The plate is wiped by the coarse blowing pipe 34 and the fine blowing pipe 35 in sequence. The plate moves to the middle of the box 11. The ring light diffuser 2 illuminates the plate surface evenly with softened light from multiple angles. The camera 15 captures images of the plate in real time and identifies hollow areas.

[0051] During use, based on the thickness, number of layers, and surface material of the plywood, combined with the resolution requirements for hollow area detection (e.g., identifying hollow areas ≥2mm²), determine the number of ring light sources, typically 2-5 sets. Increase the number if the board is thicker or has strong surface reflectivity to ensure complete light coverage. For multi-layered or thick boards, multiple sets of light sources need to be stacked to offset the effect of the board's thickness on light penetration. For reflective surfaces, use multi-directional light sources to reduce glare and avoid missing hollow areas. Push the slider 281, which houses the diffuse light source 27, along the preset slide groove 26 to the target position preset in the first step. The position must match the number of ring light sources to ensure that the diffuse and ring light illumination ranges overlap, forming complementary lighting. The slide groove 26 uses a high-precision linear guide structure to ensure that the slider 281's sliding accuracy is ≤0.1mm, avoiding uneven illumination caused by light source position deviation. Pass the bottom end of the threaded rod 288 through the round hole of the positioning piece 23, align it with the threaded hole 287 on the slider 281, and insert it. Turn the threaded rod 288 clockwise until the positioning piece 23 and the slider 281 are tightly engaged, fixing them as a whole and locking the position of the diffuse light source 27. The threaded connection has a self-locking function, which, together with the clamping action of the positioning piece 23, can resist vibration in low-temperature processing environments, ensuring long-term stability of the light source position. At the same time, the threaded rod 288 is easy to disassemble, facilitating subsequent adjustment or maintenance. Locate the nut 285 at the connection between the connecting plate 286 and the light source bracket. Rotate and unscrew the nut 285 to release the fixing constraint of the connecting plate 286. The nut 285 adopts an anti-loosening structure, which can maintain its locking performance in low-temperature environments (-20℃~0℃), preventing the threads from loosening due to temperature changes. Manually rotate the connecting plate 286 while simultaneously rotating the diffuse light source 27. According to the preset tilt angle, which can be read from the angle scale markings on the equipment with an accuracy of ≤1°, adjust the diffuse light source 27 to the target angle. Once the diffused light source 27 reaches the predetermined angle, the unscrewed nut 285 is put back into the connecting shaft, rotated clockwise and tightened until the connecting plate 286 fits tightly against the light source bracket, locking the light source angle.

[0052] The air from the hot air blower 33 enters the air box 31 through the first pipe 32. A portion of the air in the air box 31 blows through the coarse blow pipe 34 and the fine blow pipe 35 to activate the conveyor assembly 12. The remaining air in the air box 31 enters several equidistantly distributed heat dissipation pipes 38 through the second air hole 62, the air duct 37, the first air hole 39, and the solenoid valve. The heat dissipation pipes 38 are U-shaped and adapted to the box body 11. The hot air from the heat dissipation pipes 38 is evenly blown into various parts of the box body 11 through numerous equidistantly distributed third air holes 63, raising the temperature inside the box body 11. The temperature inside the box body 11 is measured in real time by a temperature sensor to maintain the temperature between 16-22℃. When the temperature approaches the target value of 19-20℃, the PLC sequentially opens the solenoid valves one group at a time. The hot air flows through the second air hole 62, the air duct 37, the first air hole 39, and the solenoid valve, then is distributed to the equidistantly distributed heat dissipation pipes 38 and evenly blown into the detection area. When the temperature stabilizes within the 16-22℃ range, the sensor continuously feeds back data. When the temperature rises to the upper limit of 21-22℃, the solenoid valve closes to reduce hot air output, and the temperature inside the housing 11 slowly decreases. When the temperature drops to the lower limit of 16-17℃, the solenoid valve opens to supply air, maintaining a temperature control accuracy of ±1℃ through closed-loop airflow circulation. Maintaining a constant temperature of 16-22℃ can reduce the dew point at the source and prevent water vapor condensation.

[0053] After the plate enters the box 11 through the feed inlet along with the conveyor assembly 12, when the plate to be processed moves to the working area of ​​the self-drying device 4, the rotating end of the motor 41 will drive all related components such as the rotating plate 43, the hot drying tube 47, the wiping plate 44, and the pneumatic plate 45 to rotate synchronously. During the rotation of the rotating plate 43, the air guide hole 71 on the rotating plate 43 will rotate with the rotating plate 43 to a position directly facing the coarse blowing tube 34. At this time, the coarse blowing tube 34 and the fine blowing tube 35 blow out hot air simultaneously. This hot air accurately enters the preset air groove through the air guide hole 71. Then, the hot air collected in the air groove will further flow into the air receiving hole 72 on the pneumatic plate 45, completing the hot air delivery and guidance, preparing for subsequent air pressure drive and drying. The pneumatic plate 45 rotates along with the rotating plate 43 and gradually moves towards the lowest point. The pneumatic plate 45 is subjected to three forces: the wind pressure generated by the hot air introduced through the air vents 72, the weight of the pneumatic plate 45 and the wiping plate 44 themselves, and the centrifugal force generated during rotation. Under the combined action of these three forces, the wiping plate 44 slides downwards along the guide direction of the air duct, and the spring 46 connecting the wiping plate 44 is gradually stretched. Finally, the bottom end of the wiping plate 44 comes into close contact with the moving plate surface, wiping away any water droplets on the plate surface during synchronous rotation. As the pneumatic plate 45 rotates and gradually moves away from the lowest point, the combined force that previously caused the wiping plate 44 to slide down gradually weakens, and the stretched spring 46 begins to release its elastic potential energy, generating a reverse restoring force. Driven by elastic force, the wiping plate 44 and the pneumatic plate 45 move upward along the air trough until the pneumatic plate 45 abuts against the limiting baffle 49 on the device. At this point, the bottom end of the wiping plate 44 separates from the plate surface, ending the wiping of that area of ​​the plate. After the pneumatic plate 45 resets, its bottom end moves into the heat-gathering area of ​​the hot drying tube 47. The heat-conducting strip transfers the heat absorbed in the air trough to the heat-gathering plate 48, raising the temperature of the area where the heat-gathering plate 48 is located. This heats the wiping plate 44, which may still have residual moisture after wiping, preventing it from carrying moisture that could affect subsequent wiping. At the same time, the plate does not stop moving but continues to move smoothly towards its center, preparing for possible secondary cleaning or the next process. The motor 41 continues to run, driving all components to rotate continuously. The air guide hole 71 of the rotating plate 43 will repeatedly align with the coarse blowing pipe 34 to continuously introduce hot air. The fan plate 45 will also cycle through the actions of turning to the lowest point, wiping with the wiping plate 44, moving away from the lowest point, and resetting to dry. As the plate moves towards the center, it will continuously pass through the wiping area of ​​the wiping plate 44 and the area that may be covered by hot air, ultimately achieving thorough removal and drying of water droplets on the plate surface.

[0054] The sheet enters the working range of the coarse blowing pipe 34. The coarse blowing pipe 34 is wider, capable of covering most or all of the sheet's width in one go. Its closer proximity to the feed inlet allows hot air to quickly reach the sheet surface, reducing moisture diffusion. The coarse blowing pipe 34 blows high-pressure, high-flow-rate hot air onto the sheet surface at an angle of 18-23°. This angle design balances impact force and airflow guidance, ensuring sufficient airflow perpendicular to the sheet surface to quickly peel off large water droplets and large water films, while also guiding the peeled water droplets to the sheet edges through the angle, preventing backflow. The wide design allows the coarse blowing pipe 34 to achieve full-width sheet coverage without frequent adjustments. Combined with the high-pressure airflow, this reduces processing pressure in the subsequent fine blowing stage, preventing large amounts of water droplets from entering the fine blowing area and causing incomplete drying. After coarse blowing, the sheet enters the working area of ​​the fine blowing pipe 35. At this point, there are no large patches of condensation on the surface of the board, but a thin layer of moisture, tiny water droplets, or dampness adhering to the plywood texture and edge crevices remain. These require meticulous cleaning using the fine air blower 35. The board enters the effective range of the fine air blower 35. The fine air blower 35 is narrower, resulting in a more concentrated airflow. Combined with a relatively large tilt angle of 32-41°, the hot air can precisely target the areas of residual moisture on the board surface. The fine air blower 35 uses low-pressure, low-flow-rate hot air. The larger angle design allows the hot air to easily penetrate the tiny textures and edge crevices of the plywood, thoroughly blowing away any residual moisture and tiny water droplets that were not removed by the initial cleaning. Simultaneously, the narrow, concentrated airflow prevents moisture diffusion caused by high pressure, ensuring that every area is precisely dried without any blind spots. Because the fine air blower 35 is farther away from the feed inlet, the board has already had a certain amount of natural air drying time during the movement. Combined with the precise blowing of the fine air blower 35, the drying uniformity can be further improved, ensuring that the moisture on the board surface is completely removed, and the plywood surface texture or adhesive layer will not be damaged due to excessive airflow.

[0055] When the board reaches the preset detection position in the middle of the box 11, the photoelectric sensor sends a trigger signal, and the ring light diffuser 2 immediately starts illumination. This device emits light from multiple angles onto the board surface through multiple light sources arranged in a ring. The light is softened by diffuse reflection before illuminating the board surface, avoiding direct, strong light. The softened light evenly covers the board surface, preventing localized reflections due to wood grain or slight unevenness, and avoiding underexposure due to shadows. The multi-angle illumination design allows for a clear grayscale difference or contour contrast between the hollow area and the normal area, providing clear image features for subsequent identification. Simultaneously with the illumination activation, the camera 15 captures images of the board surface in real time at a preset frame rate. Because the board is in continuous motion, the camera 15 uses a dynamic capture mode, with each frame covering a fixed area of ​​the board surface, and adjacent frames having a 10%–20% overlap rate to avoid detection blind spots caused by board movement. During the shooting process, camera 15 transmits the captured high-definition images to the image processing system in real time, with a transmission delay controlled within 100ms to ensure uninterrupted continuous operation of the production line. Simultaneously, the images are temporarily stored for subsequent defect tracing and verification. After receiving the images, the image processing system performs noise reduction, grayscale correction, and contrast enhancement to eliminate interference factors such as wood grain texture and slight dust, highlighting the characteristic differences of hollow areas. Through edge detection and contour recognition, it extracts feature parameters such as the size, shape, and grayscale value differences of abnormal protrusions or depressions in the image. The extracted feature parameters are compared with preset thresholds. If the threshold conditions are met, it is determined to be a hollow defect; simultaneously, the location coordinates, size, and quantity of the defect are recorded. If no hollow defect is detected, the system outputs a pass signal, and the board continues to move along the conveyor mechanism to the next process. If a hollow defect is detected, the system immediately triggers an alarm and marks the defect location. It can then link with the subsequent sorting mechanism to divert the defective boards or pause the production line for manual verification.

[0056] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details have been described in detail in the above preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits have not been described in detail.

[0057] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A visual hollow detection device based on low-temperature resistant plywood processing, characterized in that, include: The box (11) is equipped with a conveying assembly (12) inside the box (11). The two ends of the conveying assembly (12) pass through the box (11) and are located outside the box (11). A camera (15) is connected to the top wall of the box (11). A ring light diffuser (2) is provided on the outside of the camera (15). The ring light diffuser (2) is used to set up a light source with multiple tilt angles and to evenly irradiate the softened light onto the surface of the board. A dehumidifier (5) is connected to the inner wall of the box (11). A wind-heating device (3) is fixedly connected to the inner wall of one end of the box (11). The wind-heating device (3) is used to maintain the temperature inside the box (11) at 16-22℃ and to perform double-stage blowing on the board entering the box (11). A rotating dew self-drying device is provided at the feed port of the box (11). The rotating dew self-drying device is used to extend under the action of rotation and wind to wipe the surface of the board and then shrink back to dry it.

2. The visual hollow detection device based on low-temperature resistant plywood processing according to claim 1, characterized in that: The ring light diffuser (2), the air heat device (3), and the dew-drying device are all located inside the box (11), with the air heat device (3) located between the ring light diffuser (2) and the dew-drying device.

3. The visual hollow detection device based on low-temperature resistant plywood processing according to claim 1, characterized in that, The ring light diffuser (2) includes: a ring rail (21), which is located below the camera (15). The inner wall of the ring rail (21) is connected to the sliding sleeve (22) through a fixing plate (24). The inner wall of the ring rail (21) is connected to one side of the camera (15) through another fixing plate (24). Several positioning plates (23) are arranged between the two sliding rails at equal intervals in the circumferential direction. Both sides of each positioning plate (23) are fixedly connected to the side of the two sliding rails that are close to each other. Several diffuse reflective plates (25) are arranged at equal intervals in the circumferential direction at the bottom edge of the sliding rail. A sliding groove (26) is opened on one side of the sliding rail. Several rotating connecting parts (28) are slidably connected to the sliding groove (26) at equal intervals in the circumferential direction. A diffuse light source (27) is connected to the bottom of each rotating connecting part (28).

4. The visual hollow detection device based on low-temperature resistant plywood processing according to claim 3, characterized in that, The rotating connector (28) includes: a slider (281), which is slidably connected to the slide groove (26). Side plates (282) are fixedly connected to the bottom of both ends of the slider (281). A sleeve (284) is fixedly connected to one side of a side plate (282). A rotating rod (283) is rotatably connected to the sleeve (284). One end of the rotating rod (283) passes through the connecting plate (286) and the other side plate (282) in sequence and is threadedly connected to the nut (285). The bottom of the connecting plate (286) is fixedly connected to the diffuse light source (27). A threaded hole (287) is opened at the top of the slider (281). The bottom end of the threaded rod (288) passes through the round hole of a positioning piece (23) and is threadedly connected to the threaded hole (287).

5. The visual hollow detection device based on low-temperature resistant plywood processing according to claim 3, characterized in that: The diffuse light source (27) consists of several groups, each with a different tilt angle. The angles between each group of diffuse light sources (27) and the vertical direction are 25°, 40°, 55°, 70°, and 85°, respectively. Each group of diffuse light sources (27) is equidistantly distributed in the circumferential direction, and the number of diffuse light sources (27) in each group is the same and they are distributed at intervals.

6. The visual hollow detection device based on low-temperature resistant plywood processing according to claim 1, characterized in that, The air-heating device (3) includes: an air box (31), the side of the air box (31) is fixedly connected to the inner wall of the box body (11), the top of the air box (31) is provided with a second air hole (62) and a fourth air hole (64), the second air hole (62) is connected to a hot air blower (33) outside the box body (11) through a first pipe (32), each fourth air hole (64) is connected to the top of the air duct (37) through a second pipe (36), the side of the air duct (37) is provided with first air holes (39) at equal intervals, the bottom of the air duct (37) is fixedly connected to the bottom wall of the box body (11) through a fixed column (61), each first air hole (39) is connected to a heat dissipation pipe (38) through a solenoid valve, the bottom of the air box (31) is connected to a coarse blowing pipe (34) and a fine blowing pipe (35), and the top of each heat dissipation pipe (38) is provided with several third air holes (63) at equal intervals.

7. The visual hollow detection device based on low-temperature resistant plywood processing according to claim 6, characterized in that, The heat dissipation pipe (38) is a horizontally placed U-shaped pipe. The heat dissipation pipe (38) is adapted to the box body (11). The heat dissipation pipe (38) is used to evenly distribute hot air to all parts of the box body (11). The two ends of the heat dissipation pipe (38) are connected to a fan duct (37). The width of the coarse blowing pipe (34) is 2.5-5 times the width of the fine blowing pipe (35). The distance between the coarse blowing pipe (34) and the feed inlet of the box body (11) is less than the distance between the fine blowing pipe (35) and the feed inlet of the box body (11). The angle between the coarse blowing pipe (34) and the horizontal plane is 18-23°, and the angle between the fine blowing pipe (35) and the horizontal plane is 32-41°.

8. The visual hollow detection device based on low-temperature resistant plywood processing according to claim 6, characterized in that, The self-drying device for wiping away dew includes: a motor (41), the fixed end of the motor (41) is fixedly connected to the inner wall of the box (11), the rotating end of the motor (41) is rotatably connected to a rotating shaft (42), and several rotating plates (43) are equidistantly connected on the side of the rotating shaft (42) in the circumferential direction. Each rotating plate (43) has an air groove at its bottom and several equidistant air guide holes (71) on one side of each rotating plate (43). The top wall of each rotating plate (43) is permeated with air grooves. The spring (46) is connected to the wind plate (45), the wind plate (45) is slidably connected to the inner wall of the air groove, the inner part of the middle of each rotating plate (43) is connected to a limit baffle (49), the top of each wind plate (45) is provided with a wind receiving hole (72), the bottom of each wind plate (45) is connected to a heat drying pipe (47), the inner wall of each heat drying pipe (47) is fixedly connected to a heat gathering pipe, and the middle of the bottom of each wind plate (45) is connected to two wiping plates (44).

9. A visual hollow detection device based on low-temperature resistant plywood processing according to claim 8, characterized in that: The distance between the two wipers (44) is less than the width of the wind-driven plate (45). The projection of one end of the air intake hole (72) is a trapezoid. The length of the top of the trapezoid is less than the length of the bottom of the trapezoid. When the wind-driven plate (45) moves to the lowest point, the bottom of the wiper (44) contacts the surface of the plate. When the wind-driven plate (45) abuts against the limiting baffle (49), the bottom of the wiper (44) is located in the heat-collecting tube. A heat-conducting strip is fixedly connected to the inner wall of the rotating plate (43). The bottom of the heat-conducting strip is connected to the bottom of the heat-collecting tube.

10. A visual hollow detection method based on low-temperature resistant plywood processing, applied to the visual hollow detection equipment based on low-temperature resistant plywood processing as described in any one of claims 1-9, characterized in that: The plate is moved into the box (11) by the conveyor assembly (12). The plate is close to the self-drying device (4). The rotating end of the motor (41) drives all the rotating plates (43), the hot drying tube (47), the wiping plate (44), and the wind-driven plate (45) to rotate synchronously. During the rotation of the rotating plate (43), the air guide hole (71) is directly facing the coarse blowing pipe (34). The hot air blown out by the coarse blowing pipe (34) and the fine blowing pipe (35) enters the air groove through the air guide hole (71). The air in the air groove enters the air receiving hole (72). During the process of the wind-driven plate (45) turning to the lowest point, the wind-driven plate (45) is subjected to wind pressure, its own weight, and centrifugal force. The wiping plate (44) As the plate slides down the wind channel, the spring (46) stretches, and the bottom end of the wiping plate (44) contacts the surface of the plate. After the wind-driven plate (45) moves away from the lowest point, the wind-driven plate (45) moves up the wind channel under the elastic drive. The wind-driven plate (45) abuts against the limiting baffle (49). The bottom end of the wind-driven plate (45) moves into the heat-collecting tube and is dried. The plate continues to move towards the center of the plate. The plate is wiped by the coarse blowing pipe (34) and the fine blowing pipe (35) in sequence. The plate moves to the middle of the box (11). The ring light diffuser (2) evenly illuminates the plate surface with softened light from multiple angles. The camera (15) takes real-time pictures to obtain the plate image and identify the hollow area.

Images