An automatic waste rejection system and method for online detection of roll-to-roll offset printing.

Abstract

This invention discloses an automatic waste rejection system and method suitable for online detection in roll-to-roll offset printing. It includes a frame and a first conveyor belt, a second flip conveyor belt, and a third conveyor belt sequentially mounted on the frame along the horizontal conveying direction of the bookmarks. The first conveyor belt is equipped with a lateral alignment device and a visual inspection camera. A reverse waste rejection wheel with suction holes is located above the junction of the first and second conveyor belts. The second flip conveyor belt is connected to a drive mechanism, and a paper skew monitoring device is located above it. The control unit is connected to the camera, pneumatic control circuit, drive mechanism, and monitoring device. This invention, through a built-in tiered channel management program in the control unit, perfectly constructs a dual-channel intelligent tiered rejection mechanism for both occasional single-sheet waste and continuous batch waste within the same electromechanical system. Simultaneously, the linkage of lateral alignment and skew monitoring enables precise tiered rejection and proactive defense resetting of high-speed stacked bookmark flows, effectively avoiding high-speed material stacking and jamming.

Description

Technical Field

[0001] This invention belongs to the field of automated control technology for roll offset printing and post-printing materials, specifically relating to an automatic waste rejection system and method suitable for online detection in roll offset printing. Background Technology

[0002] Web offset printing presses (also known as rotary offset printing presses) are widely used in many printing and manufacturing fields such as books, food packaging, cosmetics packaging, cigarette packaging, and electronic product packaging. With the rapid development of machine vision technology, online image inspection systems have gradually become a core configuration for printing companies to ensure product quality, reduce labor costs, and improve inspection efficiency. Traditional rotary offset printing lines usually adopt a fully continuous operation mode with no unnecessary downtime. The standard process flow is generally as follows: the web of paper is unrolled and fed into the printing press. The paper passes through multiple printing units continuously at high speed and is printed on both sides simultaneously. Then it enters the drying and cooling system, and is then folded and cut at high speed by a folding machine. Finally, it forms a tightly stacked fish-scale pattern of book label material (hereinafter referred to as fish-scale book labels), which is then output to the downstream for automatic stacking and palletizing.

[0003] In actual production, rotary printing lines operate at extremely high speeds, with horizontal conveying frequencies typically exceeding 45,000 sheets per hour for bookmarks. However, existing vision inspection systems, when dealing with such high-speed, continuous, and fish-scale-stacked printed materials, often only achieve "online real-time identification" or "visual marking" (e.g., marking defective bookmarks with waste strips on the side during the preceding folding process). How to perform high-precision "online automatic rejection" of defective products without disrupting continuous production remains a major technical challenge for the industry.

[0004] Existing defective product handling methods or rejection devices have the following main technical shortcomings in practical applications: First, there is a lack of a tiered response and rejection mechanism for both "instantaneous single-sheet defects" and "continuous batch defects." In rotary printing, defects manifest in various forms, including sporadic single-sheet defects caused by localized paper stains or ink splatter, and continuous batch defects caused by roll changes, paper splicing, machine adjustments, or major malfunctions at the offset printing press. Existing rejection devices have overly simplistic structures and control logic. If relying solely on pneumatic adsorption or air jet devices, the physical limits of the pneumatic circuit's response frequency can easily lead to a cascading loss of vacuum in the entire pneumatic bus when batches of defects pass through, resulting in severe missed detections and defect stacking. If relying solely on mechanical baffles or the conveyor belt's overall oscillating switching channels, the large physical inertia and long response cycle of the mechanical structure make it impossible to keep up with the second-level throughput of single-sheet defects. Forced switching can easily disrupt the stacking posture of adjacent qualified sheets, causing severe stacking and jamming at the connection points.

[0005] Secondly, there is a lack of proactive protection and secondary correction capabilities for abnormal postures during high-speed bookplate material flow. Because fish-scale bookplates are thin and stacked, they are highly susceptible to lateral skew, loose pages, or severe misalignment on the conveyor line due to the airflow pulling and minor mechanical vibrations caused by high-speed conveying (up to 45,000 sheets per hour) and rejection processes. Existing systems cannot provide near real-time monitoring and emergency protection against paper misalignment in rejection conflict areas, nor can they perform secondary alignment of qualified bookplates after rejection disturbances. If severely skewed or misaligned bookplates are forced into the subsequent paper receiving machine, palletizer, or inserter, it will directly cause significant jamming, paper accumulation, and mechanical equipment damage, forcing frequent shutdowns of the entire fully automated production line and significantly reducing the practical application value and production efficiency of the front-end image detection.

[0006] Therefore, how to provide an automatic rejection system and method that can adapt to ultra-high-speed rotary offset printing processes, accurately reject single-sheet occasional waste and continuous batch waste in fish-scale stacked book sticker flow through dual channels, and also has online monitoring of conveyor posture for active protection and post-printing secondary correction control functions, so as to effectively avoid material stacking and blockage and ensure the efficient and stable operation of the fully continuous printing line, is a technical problem that technicians in the field of post-printing automation control urgently need to solve. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an automatic waste rejection system and method suitable for online detection in web offset printing. This system and method targets the fish-scale-like stacked bookplate material flow output from ultra-high-speed rotary offset printing processes. Through a control unit linking the pneumatic control circuit of the high-speed differential reverse waste rejection wheel and the downward drive mechanism of the flipping conveyor belt, a high-frequency peeling and adsorption channel for occasional single-sheet waste and a large-capacity physical dropping channel for continuous batches of waste are constructed within the same electromechanical topology, achieving graded response and precise diversion of waste. Simultaneously, the conveying posture of the bookplates is monitored in real time by laterally symmetrically mounted dual photoelectric sensors. A skew-based active downward tilting protection mechanism is introduced, and secondary lateral constraint alignment control is implemented at the output end. This completely solves the problems of airflow disturbance misalignment, material scattering, stacking jamming, and mechanical equipment impact shutdown that easily occur in the mixed rejection conflict area of ​​high-speed stacked bookplates. This significantly improves the precision and reliability of post-printing automated detection and rejection, ensuring the efficient and stable operation of the entire continuous rotary printing line.

[0008] To achieve the above objectives, the present invention provides an automatic waste rejection system suitable for online detection of roll offset printing, comprising a frame and a first conveyor belt, a second flip conveyor belt and a third conveyor belt sequentially connected and installed on the frame along the horizontal conveying direction of the book cover; The lateral alignment device includes two sets of first edge-aligning vertical belts disposed on both sides of the first conveyor belt and parallel to the horizontal conveying direction, and a first spacing adjustment mechanism mechanically connected to the two sets of first edge-aligning vertical belts. The two sets of first edge-aligning vertical belts run at the same linear speed. The first spacing adjustment mechanism is used to drive the two sets of first edge-aligning vertical belts to move laterally closer or further away to align the book stickers. A visual inspection camera is mounted above the end of the first conveyor belt, with its lens facing the material passage path on the upper surface of the first conveyor belt, for real-time acquisition of side images of the book sticker as it passes by. A reverse rejection wheel is horizontally positioned directly above the junction between the end of the first conveyor belt and the input end of the second reversing conveyor belt. The rotation axis of the reverse rejection wheel is parallel to the roller axis of the first conveyor belt and perpendicular to the horizontal conveying direction. A paper passage gap is reserved between the lowest point of its outer circumference and the upper surface of the first conveyor belt for single sheet paper to pass through. The rotational movement of the reverse rejection wheel causes the movement direction of its lowest outer circumference to be opposite to the material conveying direction on the upper surface of the first conveyor belt. Multiple suction holes are distributed on the outer circumference of the reverse rejection wheel. The pneumatic control circuit includes a negative pressure air source and a high-speed negative pressure solenoid valve. The air inlet of the high-speed negative pressure solenoid valve is connected to the negative pressure air source through a pipeline, and the air outlet is connected to the negative pressure chamber in the reverse waste removal wheel through a rotary joint to control the suction hole to generate or release suction. A drive mechanism is mounted on the frame and connected to the second tilting conveyor belt. The roller axis of the second tilting conveyor belt near the input end of the first conveyor belt is supported on the frame as a fixed rotating shaft. Under normal conditions, the second tilting conveyor belt is on the same horizontal plane as the first conveyor belt and the third conveyor belt. The output end of the second tilting conveyor belt near the third conveyor belt can rotate and swing downward around the fixed rotating shaft under the drive of the drive mechanism to form a continuous waste disposal gap between the output end of the second tilting conveyor belt and the input end of the third conveyor belt. The paper skew monitoring device includes two photoelectric sensors. The two photoelectric sensors are symmetrically mounted on both sides directly above the second flip conveyor belt along a direction perpendicular to the horizontal conveying direction, and the lateral distance between the two photoelectric sensors is greater than the width of the normal book cover. A control unit is mounted on the frame and is electrically connected to the signal control terminal of the visual inspection camera, the high-speed negative pressure solenoid valve, the drive mechanism, and the signal output terminals of the two photoelectric sensors. A single waste output port is located on the frame diagonally below the reverse waste rejection wheel along its rotational throwing direction; And a continuous waste output port is located on the frame directly below the continuous waste discharge opening.

[0009] Furthermore, the first spacing adjustment mechanism includes a bidirectional lead screw that extends laterally through the bottom of the first conveyor belt and a hand crank connected to the bidirectional lead screw. The reverse threaded sections at both ends of the bidirectional lead screw are respectively connected to the mounting bracket threaded pairs of the first flush-edge vertical belts on both sides.

[0010] Furthermore, two second edge-aligning vertical belts running at the same speed are symmetrically arranged on both sides of the third conveyor belt. The distance between the two second edge-aligning vertical belts is adjustable by a second distance adjustment mechanism, which is used to perform secondary lateral alignment of qualified book stickers that have entered the third conveyor belt after the rejection action.

[0011] Furthermore, the visual inspection camera integrates an image processing chip, which has a built-in deep learning recognition algorithm for identifying whether there is a waste label strip on the book sticker based on the side image.

[0012] Furthermore, the control unit is used to control the high-speed negative pressure solenoid valve to open when the single-sheet occasional waste is detected by the visual inspection camera, so that the single-sheet occasional waste is adsorbed and adhered to the outer circumference of the reverse waste rejection wheel by the suction hole, and thrown in the reverse direction to the single-sheet waste output port when the visual inspection camera detects continuous waste. The control unit is also used to control the drive mechanism to drive the second flip conveyor belt to rotate and swing downward around the fixed rotating shaft when the visual inspection camera detects continuous waste, so that the continuous waste falls from the continuous waste throwing gap to the continuous waste output port.

[0013] A second aspect of the present invention provides an automatic rejection method for defective products in online inspection of web offset printing. Using the aforementioned automatic rejection system for defective products in online inspection of web offset printing, the method includes the following steps: S1. Initial alignment and image acquisition: The book stickers are horizontally conveyed along the first conveyor belt, and the book stickers are initially aligned laterally by the two sets of first edge-aligning belts of the lateral alignment device; when the book stickers pass below the end of the first conveyor belt, the visual inspection camera acquires the side image of the book stickers in real time. S2. Intelligent identification and determination of waste type: The control unit determines whether there is a waste marking strip on the currently passing book sticker based on the side image and the built-in deep learning recognition algorithm, and further distinguishes the waste type as single occasional waste or continuous waste when a waste marking strip is present. S3. Graded rejection control execution: If the product is determined to be a single, occasional defective sheet, the control unit controls the high-speed negative pressure solenoid valve to open when the single, occasional defective sheet reaches the paper feed gap. The suction hole is used to adsorb and adhere the single, occasional defective sheet to the outer circumference of the reverse rejection wheel, and then throw it in the reverse direction to the single-sheet defective sheet output port. If the product is determined to be a continuous defective sheet, the control unit controls the drive mechanism to drive the second flip conveyor belt to rotate and swing downward around the fixed rotating shaft, so that the continuous defective sheet falls from the continuous defective sheet drop gap to the continuous defective sheet output port. S4. Conveying posture monitoring and active defense: When the two photoelectric sensors of the paper skew monitoring device are blocked due to spatial interference caused by the book stick's yaw or skew, the control unit determines that the book stick is running skewed and directly triggers the drive mechanism to control the second flip conveyor to rotate and swing downward to throw away the book stick with poor posture. S5. Secondary correction output: Qualified book stickers that have not been rejected enter the third conveyor belt, and are output after secondary lateral alignment by the second edge-aligning vertical belts on both sides of the third conveyor belt.

[0014] Furthermore, in step S3, when a single, occasional defective sheet is determined to be defective, the control unit calculates the delayed trigger time for the single, occasional defective sheet to reach the paper feed gap based on the real-time linear speed of the first conveyor belt and the physical distance from the visual inspection camera to the paper feed gap: In the formula t=L / v, t is the delayed trigger time; L is the physical distance of the conveying path from the object center of the lens of the visual inspection camera to the center of the paper gap; and v is the real-time linear speed of the first conveyor belt.

[0015] Furthermore, in step S3, the reverse waste removal wheel is driven to rotate counterclockwise by an independent speed-regulating motor, so that the rated operating linear speed of its outer circumference is maintained at more than 7 times the rated operating linear speed of the first conveyor belt. Utilizing the relative motion speed difference, tangential friction force, and reverse pulling force generated by the high-speed reverse rotation, in conjunction with the negative pressure released by the suction hole, the target single piece of occasional waste is pulled away and thrown backward and downward without disrupting the fish-scale stacking posture of the adjacent qualified book stickers behind.

[0016] Furthermore, in step S2, the image processing chip integrated in the visual inspection camera directly performs localized high-frequency edge extraction and feature filtering on the input side image data at the hardware level, and performs millisecond-level classification retrieval and pattern comparison on the deep feature model of the marker bar through the built-in deep learning recognition algorithm.

[0017] Furthermore, in step S4, the two photoelectric sensors and the control unit form an "OR" logic trigger relationship, that is, when either photoelectric sensor generates a spatial interference signal, the control unit determines the current book sticker attitude yaw and outputs a swing-over action command.

[0018] The present invention has at least the following beneficial effects: This invention, through a built-in hierarchical channel management program in the control unit, refines the waste removal action into a single-sheet intermittent mode and a large-volume batch mode. Utilizing a reverse-speed waste-removing wheel with a linear velocity difference maintained at more than 7 times, combined with instantaneous high-frequency negative pressure adsorption, it achieves high-speed, undisturbed peeling of three or fewer intermittent single-sheet waste sheets, without disrupting the overall fish-scale stacking and conveying posture of adjacent sheets. When facing a continuous batch of waste sheets of four or more sheets, the system automatically and seamlessly switches to a tilting belt overall swing mode, reconstructing a large, downward-opening drop gap at the junction of the two modes. This completely overcomes the bottlenecks of frequent operation of a single pneumatic valve assembly leading to vacuum avalanche instability when facing continuous batch waste removal, and the inability of the mechanical structure's physical inertia to keep up with the high-frequency removal action. It perfectly solves the industrial problems of frequent mechanical jamming and material stacking under high-speed, highly mixed waste conditions.

[0019] This invention introduces a millisecond-level timestamp delay calculation model (t=L / v) based on the real-time linear speed of the first conveyor belt and the physical distance between the camera and the paper. Combined with a high-speed differential peeling mechanism, extremely strong tangential friction and reverse pulling force are generated at the moment of contact with a single waste sheet. This not only accurately peels off and breaks the forward inertia of the waste sheet, causing it to deflect and fall backward and downward, but also ensures that the removal action is completed independently and thoroughly at high frequency without affecting the normal conveying of adjacent qualified sheets. This greatly improves the success rate of targeted removal of single waste sheets in rotary printing at an extremely high linear speed of 45,000 sheets / hour.

[0020] The system features dual photoelectric sensors symmetrically positioned horizontally above the second flip conveyor belt. Utilizing the interference of materials in the width of the space, it constructs an active skew protection mechanism triggered by an "OR" logic. Under high-speed conveying of up to 45,000 sheets per hour, or the localized reverse airflow and mechanical micro-vibration disturbances caused by frequent rejection, if some qualified bookmarks shift laterally due to loose pages or yaw, thus obstructing any sensor, the control unit can instantly determine that the paper is in a skewed, undesirable operating state without waiting for a camera image signal. It then quickly flips down the second flip conveyor belt to remove the skewed paper in advance, effectively preventing abnormal bookmarks with a significant risk of jamming from forcibly entering the subsequent stages, thus constructing an intelligent protective barrier for fully automated and safe operation of the equipment.

[0021] The system is equipped with edge-aligning vertical belts on both sides of the first and third conveyor belts, which are symmetrically adjusted by bidirectional screws. The vertical belts on both sides of the first conveyor belt form an initial front-end alignment mechanism, which ensures that the center line of the book sticker flow is always absolutely coincident with the geometric center line of the camera imaging, thus laying a unified benchmark for high-frequency and high-quality image acquisition. The vertical belts on both sides of the third conveyor belt form a secondary rear-end reset mechanism, which forcibly eliminates the misalignment of qualified products caused by the high-frequency rejection airflow or belt swing disturbance at the front end. It performs lateral forced secondary physical correction on qualified book stickers, which not only greatly improves the edge stacking regularity of the final output material, but also completely eliminates the stacking jamming caused by the scattered posture of book stickers due to rejection disturbance in subsequent processes. Attached Figure Description

[0022] Figure 1 This is a front side view of the overall structure of an automatic waste rejection system for online detection in roll paper offset printing according to the present invention. Figure 2 This is a top view of an automatic waste rejection system for online detection in roll paper offset printing according to the present invention; Figure 3 This is a schematic diagram of the overall axonometric structure of an automatic waste rejection system for online detection of roll paper offset printing according to the present invention.

[0023] Explanation of reference numerals in the attached drawings: 1. First conveyor belt; 2. Reverse waste rejection wheel; 3. Second overturning conveyor belt; 4. Third conveyor belt; 5. Lateral alignment device; 6. Visual inspection camera; 7. Pneumatic control circuit; 8. Drive mechanism; 9. Paper skew monitoring device; 10. Single sheet waste output port; 11. Continuous waste output port. Detailed Implementation

[0024] Example 1

[0025] like Figures 1 to 3 As shown, the present invention provides an automatic rejection system and method for waste products in online detection of roll offset printing, and its specific implementation is described in detail through the following two mutually supporting embodiments.

[0026] like Figures 1 to 3 As shown, this embodiment first provides the specific hardware physical structure topology of the automatic rejection system required to implement the above method: The system includes a frame and a first conveyor belt 1, a second flip conveyor belt 3 and a third conveyor belt 4 that are sequentially connected and installed on the frame along the horizontal conveying direction of the book covers; The lateral alignment device 5 includes two sets of first edge-aligning vertical belts disposed on both sides of the first conveyor belt 1 and parallel to the horizontal conveying direction, and a first spacing adjustment mechanism mechanically connected to the two sets of first edge-aligning vertical belts. The two sets of first edge-aligning vertical belts run at the same linear speed. The first spacing adjustment mechanism is used to drive the two sets of first edge-aligning vertical belts to move laterally closer or further away to align the book stickers. A visual inspection camera 6 is mounted above the end of the first conveyor belt 1, with its lens facing the material passage path on the upper surface of the first conveyor belt 1, for real-time acquisition of side images of the book sticker as it passes by. The reverse rejection wheel 2 is horizontally positioned directly above the junction between the end of the first conveyor belt 1 and the input end of the second reversing conveyor belt 3. The rotation axis of the reverse rejection wheel 2 is parallel to the roller axis of the first conveyor belt 1 and perpendicular to the horizontal conveying direction. A paper passage gap is reserved between the lowest end of its outer circumference and the upper surface of the first conveyor belt 1 for a single sheet of paper to pass through. The rotational movement of the reverse rejection wheel 2 causes the movement direction of its lowest outer circumference to be opposite to the material conveying direction on the upper surface of the first conveyor belt 1. Multiple suction holes are distributed on the outer circumference of the reverse rejection wheel 2. The pneumatic control circuit 7 includes a negative pressure air source and a high-speed negative pressure solenoid valve. The air inlet of the high-speed negative pressure solenoid valve is connected to the negative pressure air source through a pipeline, and the air outlet is connected to the negative pressure chamber in the reverse waste removal wheel 2 through a rotary joint to control the suction hole to generate or release suction. A drive mechanism 8 is mounted on the frame and connected to the second tilting conveyor belt 3. The roller axis of the second tilting conveyor belt 3 near the input end of the first conveyor belt 1 is supported on the frame as a fixed rotating shaft. Under normal conditions, the second tilting conveyor belt 3 is on the same horizontal plane as the first conveyor belt 1 and the third conveyor belt 4. The output end of the second tilting conveyor belt 3 near the third conveyor belt 4 can rotate and swing downward around the fixed rotating shaft under the drive of the drive mechanism 8, so as to form a continuous waste disposal gap between the output end of the second tilting conveyor belt 3 and the input end of the third conveyor belt 4. The paper skew monitoring device 9 includes two photoelectric sensors. The two photoelectric sensors are symmetrically mounted on both sides directly above the second flip conveyor belt 3 along a direction perpendicular to the horizontal conveying direction, and the lateral distance between the two photoelectric sensors is greater than the width of the normal book cover. A control unit is mounted on the frame and is electrically connected to the signal control terminal of the visual inspection camera 6, the signal control terminal of the high-speed negative pressure solenoid valve, the drive mechanism 8, and the signal output terminals of the two photoelectric sensors. The single waste output port 10 is located on the frame diagonally below the reverse waste rejection wheel 2 along its rotational throwing direction; And a continuous waste output port 11 is provided on the frame directly below the continuous waste discharge opening.

[0027] In a preferred embodiment, the first spacing adjustment mechanism includes a bidirectional lead screw extending laterally beneath the first conveyor belt 1 and a hand crank connected to the bidirectional lead screw. The reverse threaded sections at both ends of the bidirectional lead screw are respectively connected to the threaded joints of the mounting brackets of the first flush-edge vertical belts on both sides. Specifically, when switching and adjusting for book sticker products of different widths is required, the hand crank is manually rotated, which drives the bidirectional lead screw to rotate synchronously. Since the bidirectional lead screw has reverse threaded sections at both ends with opposite thread directions, it can drive the mounting brackets of the first flush-edge vertical belts on both sides to produce synchronous displacements of equal magnitude and opposite directions on the horizontal platform, causing both sides to synchronously move inward or outward. This mechanical symmetrical linkage adjustment method is not only simple to operate and highly efficient, but also ensures that the transverse geometric center line of the first conveyor belt 1 always remains absolutely aligned with the conveying center line of the book sticker material flow. This fundamentally avoids the problems of overall lateral deviation, loose pages, or skew caused by individual manual adjustment on both sides, laying a reliable and unified physical alignment benchmark for the subsequent accurate side imaging of the visual inspection camera 6.

[0028] In a preferred embodiment, the third conveyor belt 4 in this embodiment is symmetrically provided with two second edge-aligning vertical belts running at the same speed on both sides of its transverse direction. The distance between the two second edge-aligning vertical belts is adjustable by a second distance adjustment mechanism to perform secondary lateral alignment of qualified book stickers entering the third conveyor belt 4 after the rejection action. Furthermore, in a high-speed rotary offset printing environment with a speed of up to 45,000 sheets per hour, the material flow runs in a tight, fish-scale-like stacked state. When the book sticker flow passes through the junction of the first conveyor belt 1 and the second reversing conveyor belt 3, due to the frequent adsorption and pulling of the high-speed reverse airflow from the reverse rejection wheel 2, or the frequent downward swinging disturbance of the second reversing conveyor belt 3, even qualified book stickers that have not been rejected are easily misaligned laterally due to the interference of instantaneous airflow and minor mechanical vibrations, causing their original neat stacking posture or lateral edge alignment to be affected. The second edge-aligning vertical belt, controlled by the second spacing adjustment mechanism, is symmetrically arranged on the third conveyor belt 4 at the final output end. This belt can perform secondary lateral physical constraints and forced correction clamping on qualified book stickers after passing through the conflict area, eliminating the lateral posture defects caused by the rejection action. This ensures that the book stickers finally output to the subsequent stacking, inserting, or bundling processes have extremely high edge stacking regularity, effectively avoiding mechanical stacking jamming failures caused by the scattered posture of the book stickers in the subsequent processes.

[0029] In a preferred embodiment, the reverse rejection wheel 2 in this example is driven by an independent speed-regulating motor. This motor drives the reverse rejection wheel 2 to rotate, maintaining its rated linear speed on its outer circumference at more than seven times the rated linear speed of the first conveyor belt 1. During operation, the book sticker output from the rotary offset printing press has an extremely high linear speed, and the book sticker possesses significant forward inertia in the horizontal conveying direction. By equipping the reverse rejection wheel 2 with the independent speed-regulating motor to rotate counterclockwise at high speed, a strong reverse linear speed is generated on its lowermost outer circumference, opposite to the forward conveying direction of the book sticker. When its rated linear speed is maintained at more than seven times the rated linear speed of the first conveyor belt 1, at the extremely brief instant of contact between the outer circumference of the reverse rejection wheel 2 and the target single waste book sticker, the huge relative speed difference generates extremely high-frequency tangential friction and reverse pulling forces. Combined with the negative pressure released instantaneously by the suction hole, this instantly breaks and overcomes the forward inertia of the single waste book sticker, causing it to deflect backward and downward. This ultra-high linear speed differential stripping mechanism can, without affecting the normal forward conveying of adjacent qualified sheets or disrupting the overall fish-scale stacking posture, extremely quickly and thoroughly extract and throw the target single sheet of occasional waste from the high-speed material flow, significantly improving the success rate of targeted removal of single sheets of waste under high-speed conditions.

[0030] In a preferred embodiment, the visual inspection camera 6 in this example integrates an image processing chip. This chip incorporates a deep learning recognition algorithm to identify whether defective marking strips exist on the book stickers based on the side image. Specifically, during the preceding folding process, if a book sticker is found to have surface printing defects such as inkjet printing or overprinting, a defect marking strip of a specific shape or color is applied to the side of the sticker. When the stacked book stickers pass through the end of the first conveyor belt 1, the visual inspection camera 6 acquires side images of the book stickers in real time. The image processing chip integrated within the camera directly performs localized high-frequency edge extraction and feature filtering on the image data at the hardware level. Through the built-in deep learning recognition algorithm, millisecond-level classification retrieval and pattern comparison are performed on the deep feature model of the marking strips. This embodiment directly integrates the algorithm and image chip into the edge-side camera, eliminating the communication latency and system overhead of uploading massive amounts of high-frequency images to a remote host computer for processing. This significantly shortens the data transmission cycle and core inference latency, achieving zero-miss detection and high-precision near real-time online edge recognition of defective marking strips.

[0031] In a preferred embodiment, the high-speed negative pressure solenoid valve in the pneumatic control circuit 7 is normally closed. This normally closed configuration allows the system to remain in a de-energized, silent state during normal product delivery (i.e., most normal production conditions). In this state, the negative pressure air source and the negative pressure chamber inside the reverse rejecting wheel 2 are physically isolated, and the external suction holes do not generate suction. This minimizes energy waste during long-term system operation and prevents unnecessary leakage and loss of vacuum from the negative pressure air source. Simultaneously, this structure significantly reduces physical fatigue wear of the valve core, extending the service life of pneumatic components. Furthermore, when a sudden power outage, signal failure, or bus communication malfunction occurs on the production line, the normally closed high-speed negative pressure solenoid valve automatically locks in the closed state due to power loss, preventing the reverse rejecting wheel 2 from accidentally sucking up normal qualified product labels during system malfunctions. This provides passive fault protection for the entire rotary production line.

[0032] Example 2 This embodiment details the specific control method and steps for performing fully automatic hierarchical elimination control using the physical topology system described in Embodiment 1 above. The method includes the following core steps: S1. Initial Alignment and Image Acquisition: The continuous fish-scale pattern of book stickers enters the first conveyor belt 1. First, the fish-scale book stickers are mechanically constrained and physically aligned at high speed by two sets of first edge-aligning belts of the lateral alignment device 5. When the book stickers pass through the paper path at the end of the first conveyor belt 1, the visual inspection camera 6 mounted directly above it begins to take high-frequency, high-precision pictures and collect side images of each book sticker in real time.

[0033] S2. Intelligent identification and determination of waste type: Image data acquired in real time by the visual inspection camera 6 is input to the image processing chip integrated into the camera, where it performs localized high-frequency edge extraction and feature filtering at the hardware level. Subsequently, the built-in deep learning recognition algorithm performs millisecond-level classification retrieval and pattern comparison on the deep feature model of the waste label strips affixed in the previous process, thereby allowing the control unit to determine in near real-time whether a waste label strip exists on the currently passing book sticker. If it does, the hierarchical channel management program built into the control unit will automatically classify and determine the waste scale type based on the consecutive number of waste label strips (in this embodiment, 3 consecutive strips are used as the threshold), thereby intelligently selecting to activate either the "single waste rejection mode" or the "continuous waste rejection mode" within the same system.

[0034] S3, Implementation of graded rejection control: Based on the determination result of step S2, the system performs the following different physical space diversion and clearing actions in a hierarchical manner: (1) Single-sheet waste rejection mode: If the number of consecutive waste labels identified and determined by the control unit is 3 or less (i.e., determined to be a single-sheet occasional waste or short consecutive waste), the system will input a signal to the first-level response. The control unit immediately calculates the millisecond-level delay trigger time for the target single-sheet waste to move to the center of the paper gap based on the real-time running linear speed (v) of the first conveyor belt 1 and the physical distance (L) of the conveying path from the object center of the lens of the vision inspection camera 6 to the center of the paper gap: t=L / v. After the delay trigger time t is processed, the control unit sends an instantaneous high-frequency electrical signal to the high-speed negative pressure solenoid valve of the pneumatic control circuit 7 to briefly turn it on. The negative pressure air source is instantly connected to the negative pressure chamber in the reverse waste rejection wheel 2, and the strong instantaneous local negative pressure generated by the peripheral suction hole is used to grab the tail end of the single-sheet waste in the very short instant it passes. At this time, because the reverse scrap wheel 2 is driven by the independent speed-regulating motor to maintain high-speed counterclockwise rotation, and the rated operating linear speed of its outer circumference is maintained at more than 7 times the rated operating linear speed of the first conveyor belt 1, the tangential friction and reverse pulling force generated by the huge relative motion speed difference can instantly break the forward inertia of the single waste book sticker, causing it to deflect backward and downward, smoothly and thoroughly pulling it away and throwing it backward and downward into the single waste output port 10; during this period, the qualified book sticker continues to move forward horizontally, completely unaffected by the peeling action.

[0035] (2) Continuous waste rejection mode: If the number of consecutive waste label strips identified and determined by the control unit is greater than 3 (i.e., it is determined to be a large-volume continuous batch of waste), the system automatically and seamlessly switches to the second-level large-volume diversion response. At this time, in order to protect the vacuum of the pneumatic system from leakage and instability, for the first 3 wastes in the continuous waste flow, the system still uses the reverse waste rejection wheel 2 to quickly extract and throw them into the single waste output port 10 through the first response path mentioned above; while for the subsequent large-volume continuous wastes starting from the 4th waste, the control unit runs to the position of the second flip conveyor belt 3 after a pulse delay L2, and sends a continuous waste rejection signal to the drive mechanism 8 (cylinder assembly). The drive mechanism 8 (cylinder) responds quickly and controls the second flip conveyor belt 3 to rotate and swing clockwise downward around the fixed shaft at its input end, so that its output end swings down instantly, thereby reconstructing and tearing a continuous waste throwing gap between the output end of the second flip conveyor belt 3 and the input end of the third conveyor belt 4. Under the combined force of the conveyor belt's forward movement and their own gravity, the batch of continuously defective products smoothly slides into the continuously defective product output port 11 directly below the gap. Only after the visual inspection camera 6 determines that the last continuously defective product has passed and the set reset delay has elapsed, does the drive mechanism 8 (cylinder) reverse its action, controlling the second flip conveyor belt 3 to return to its initial horizontal coplanar position, allowing subsequent qualified product labels to be seamlessly connected and output.

[0036] S4. Transport attitude monitoring and active defense (skew correction mechanism): During the process of the bookplate passing through the second flip conveyor belt 3, it is prone to page breakage and skewing due to the high-speed reverse pulling of the reverse rejection wheel 2 or belt slippage disturbance. The two photoelectric sensors of the paper skewing monitoring device 9 are symmetrically arranged on both sides directly above the second flip conveyor belt 3, and they form an "OR" logic trigger relationship with the control unit. When either photoelectric sensor is blocked due to spatial interference caused by the lateral angle deviation of the paper or severe skewing, the control unit does not need to wait for the camera signal. It directly determines that the current bookplate's conveying posture is abnormal (with a major risk of subsequent jamming), and then directly triggers the drive mechanism 8 (cylinder) connected to it to act, controlling the second flip conveyor belt 3 to quickly flip down, throwing the bookplate with poor posture into the continuous waste output port 11 in advance, thus constructing an active defense barrier from the hardware layer mechanism linkage.

[0037] S5, Secondary Correction Output: Unrejected bookplates with acceptable posture smoothly enter the third conveyor belt 4. At the final output end, the second edge-aligning vertical belts (the spacing of which is controlled by the second spacing adjustment mechanism) symmetrically arranged on both sides of the third conveyor belt 4 perform secondary lateral physical constraints, clamping, and forced alignment of the fish-scale bookplates after passing through the rejection disturbance area. This completely eliminates the lateral posture misalignment caused by the rejection action, ensuring that the fish-scale bookplates finally efficiently conveyed to the downstream finished bookplate stacking machine have extremely high edge stacking regularity, preventing major paper accumulation failures in the later stages.

[0038] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An automatic rejecting system for waste products in online detection of roll-to-roll offset printing, characterized in that, It includes a frame and a first conveyor belt (1), a second flip conveyor belt (3) and a third conveyor belt (4) that are sequentially connected and installed on the frame along the horizontal conveying direction of the book stickers; The lateral alignment device (5) includes two sets of first edge-aligning vertical belts disposed on the lateral sides of the first conveyor belt (1) and parallel to the horizontal conveying direction, and a first spacing adjustment mechanism mechanically connected to the two sets of first edge-aligning vertical belts. The two sets of first edge-aligning vertical belts run at the same linear speed. The first spacing adjustment mechanism is used to drive the two sets of first edge-aligning vertical belts to move laterally closer or further away in order to align the book stickers. A visual inspection camera (6) is mounted above the end of the first conveyor belt (1), with its lens facing the material passage path on the upper surface of the first conveyor belt (1), for real-time acquisition of side images of the book sticker as it passes by. The reverse waste rejection wheel (2) is horizontally positioned directly above the connection between the end of the first conveyor belt (1) and the input end of the second reversing conveyor belt (3). The rotation axis of the reverse waste rejection wheel (2) is parallel to the roller axis of the first conveyor belt (1) and perpendicular to the horizontal conveying direction. A paper passage gap for single book stickers is reserved between the lowest end of its outer circumference and the upper surface of the first conveyor belt (1). The rotational movement of the reverse waste rejection wheel (2) causes the movement direction of its lowest outer circumference to be opposite to the material conveying direction of the upper surface of the first conveyor belt (1). Multiple suction holes are distributed on the outer circumference of the reverse waste rejection wheel (2). The pneumatic control circuit (7) includes a negative pressure air source and a high-speed negative pressure solenoid valve. The air inlet of the high-speed negative pressure solenoid valve is connected to the negative pressure air source through a pipeline, and the air outlet is connected to the negative pressure chamber inside the reverse waste removal wheel (2) through a rotary joint to control the suction hole to generate or release suction. A drive mechanism (8) is mounted on the frame and connected to the second flip conveyor belt (3). The roller axis of the second flip conveyor belt (3) near the input end of the first conveyor belt (1) is supported on the frame as a fixed rotating shaft. Under normal conditions, the second flip conveyor belt (3) is on the same horizontal plane as the first conveyor belt (1) and the third conveyor belt (4). The output end of the second flip conveyor belt (3) near the third conveyor belt (4) can rotate and swing downward around the fixed rotating shaft under the drive of the drive mechanism (8) to form a continuous waste disposal gap between the output end of the second flip conveyor belt (3) and the input end of the third conveyor belt (4). The paper skew monitoring device (9) includes two photoelectric sensors. The two photoelectric sensors are symmetrically mounted on both sides directly above the second flip conveyor belt (3) in a direction perpendicular to the horizontal conveying direction, and the lateral distance between the two photoelectric sensors is greater than the width of the normal book cover. The control unit is installed on the frame and is electrically connected to the signal control terminal of the visual inspection camera (6), the high-speed negative pressure solenoid valve, the drive mechanism (8), and the signal output terminals of the two photoelectric sensors. A single waste output port (10) is located on the frame below the reverse waste rejection wheel (2) along its rotational throwing direction; And a continuous waste output port (11) is located on the frame directly below the continuous waste discharge opening.

2. The automatic rejecting system for online inspection of roll-to-roll offset printing as described in claim 1, characterized in that: The first spacing adjustment mechanism includes a bidirectional lead screw that runs horizontally through the bottom of the first conveyor belt (1) and a hand crank connected to the bidirectional lead screw. The reverse threaded sections at both ends of the bidirectional lead screw are respectively connected to the mounting bracket threaded pairs of the first flush-edge vertical belts on both sides.

3. The automatic rejecting system for online inspection of roll-to-roll offset printing as described in claim 1, characterized in that: The third conveyor belt (4) has two second edge-aligning vertical belts running at the same speed on its transverse sides. The distance between the two second edge-aligning vertical belts is adjustable by a second distance adjustment mechanism, which is used to perform secondary lateral alignment of qualified book stickers that have entered the third conveyor belt (4) after the rejection action.

4. The automatic rejecting system for online inspection of roll-to-roll offset printing as described in claim 1, characterized in that: The visual inspection camera (6) integrates an image processing chip, which has a built-in deep learning recognition algorithm for identifying whether there is a waste label strip on the book sticker based on the side image.

5. The automatic rejecting system for online inspection of roll-to-roll offset printing as described in claim 1, characterized in that: The control unit is used to control the high-speed negative pressure solenoid valve to open when the single-sheet occasional waste is detected by the visual inspection camera (6) and the single-sheet occasional waste reaches the paper feed gap. The suction hole is used to adsorb and stick the single-sheet occasional waste to the outer circumference of the reverse waste rejection wheel (2) and throw it in the opposite direction to the single-sheet waste output port (10). The control unit is also used to control the drive mechanism (8) to drive the second flip conveyor belt (3) to rotate and swing downward around the fixed rotating shaft when the visual inspection camera (6) detects continuous waste, so that the continuous waste falls from the continuous waste drop gap to the continuous waste output port (11).

6. A method for automatic rejection of defective products in online detection of roll-to-roll offset printing, characterized in that, The automatic rejecting system for online inspection of roll-to-roll offset printing, as described in any one of claims 1 to 5, comprises the following steps: S1. Initial alignment and image acquisition: The book stickers are horizontally conveyed along the first conveyor belt (1), and the book stickers are initially aligned laterally by the two sets of first edge-aligning belts of the lateral alignment device (5); when the book stickers pass below the end of the first conveyor belt (1), the visual inspection camera (6) acquires the side image of the book stickers in real time. S2. Intelligent identification and determination of waste type: The control unit determines whether there is a waste marking strip on the currently passing book sticker based on the side image and the built-in deep learning recognition algorithm, and further distinguishes the waste type as single occasional waste or continuous waste when a waste marking strip is present. S3. Graded rejection control execution: If it is determined to be a single-sheet occasional waste, the control unit controls the high-speed negative pressure solenoid valve of the pneumatic control circuit (7) to open when the single-sheet occasional waste reaches the paper feed gap, and uses the suction hole to adsorb and stick the single-sheet occasional waste to the outer circumference of the reverse rejection wheel (2), and throw it in the opposite direction to the single-sheet waste output port (10); if it is determined to be a continuous waste, the control unit controls the drive mechanism (8) to drive the second flip conveyor belt (3) to rotate and swing downward around the fixed rotating shaft, so that the continuous waste falls from the continuous waste drop gap to the continuous waste output port (11). S4. Conveying posture monitoring and active defense: When the book sticker passes through the second flip conveyor belt (3), when the two photoelectric sensors of the paper skew monitoring device (9) are blocked due to spatial interference caused by the book sticker's yaw or skew, the control unit determines that the book sticker is running skewed and directly triggers the drive mechanism (8) to control the second flip conveyor belt (3) to rotate and swing downwards to throw away the book sticker with poor posture. S5. Secondary correction output: The qualified book stickers that have not been rejected enter the third conveyor belt (4) and are output after secondary lateral alignment by the second edge-aligning vertical belts on both sides of the third conveyor belt (4).

7. The automatic rejection method for defective products in online detection of roll-to-roll offset printing according to claim 6, characterized in that: In step S3, when a single-sheet occasional defective item is determined, the control unit calculates the delayed trigger time for the single-sheet occasional defective item to reach the paper feed gap based on the real-time running linear speed of the first conveyor belt (1) and the physical distance from the visual inspection camera (6) to the paper feed gap: t=L / v In the formula, t is the delayed trigger time; L is the physical distance of the conveying path from the object center of the lens of the visual inspection camera (6) to the center of the paper gap; v is the real-time running linear speed of the first conveyor belt (1).

8. The automatic rejection method for defective products in online detection of roll-to-roll offset printing according to claim 6, characterized in that: In step S3, the reverse waste removal wheel (2) is driven to rotate counterclockwise by an independent speed-regulating motor, so that the rated operating linear speed of its outer circumference is kept more than 7 times the rated operating linear speed of the first conveyor belt (1). By utilizing the relative motion speed difference, tangential friction force and reverse pulling force generated by the high-speed reverse rotation, and in conjunction with the negative pressure released by the suction hole, the target single waste sheet is pulled away and thrown to the rear and lower without damaging the fish-scale stacking posture of the adjacent qualified book stickers.

9. The automatic rejection method for defective products in online detection of roll-to-roll offset printing according to claim 6, characterized in that: In step S2, the image processing chip integrated in the visual inspection camera (6) directly performs localized high-frequency edge extraction and feature filtering on the input side image data at the hardware level, and performs millisecond-level classification retrieval and pattern comparison on the deep feature model of the marker bar through the built-in deep learning recognition algorithm.

10. The automatic rejection method for defective products in online detection of roll-to-roll offset printing according to claim 6, characterized in that: In step S4, the two photoelectric sensors and the control unit form an "OR" logic trigger relationship. That is, when either photoelectric sensor generates a spatial interference signal, the control unit determines the current book sticker attitude yaw and outputs a swing-over action command.

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