An automatic waste removing system suitable for online detection of offset printing of flat paper

Abstract

This invention discloses an automatic waste rejection system suitable for online detection in sheet-fed offset printing. The movable bidirectional gripper mechanism includes a bidirectional gripper block and a gripper block motion control component. The bidirectional gripper block has upstream and downstream gripper trajectories along the direction of the gripper bar movement. The motion control component controls its switching between a working gripper position and a clearance position that keeps the gripper bar closed. A negative pressure wheel is rotatably mounted on the frame. A negative pressure air seat is sealed to the negative pressure wheel and has a vacuum port. A covering belt assembly covers the outer periphery of the negative pressure wheel and moves synchronously. During clearance, the upstream trajectory avoids the waste gripper bar, and the downstream trajectory lags behind in gripping. Waste products are fed into the negative pressure wheel via a paper guiding structure and a positive pressure blowing device. After being adsorbed by negative pressure and clamped and conveyed by the covering belt, they fall into the receiving box, achieving automatic waste rejection without stopping the printing press.

Description

Technical Field

[0001] This invention belongs to the field of sheet-fed printing machinery technology, specifically relating to an automatic waste rejection system suitable for online detection in sheet-fed offset printing. Background Technology

[0002] Sheet-fed offset printing presses, as a type of continuous printing equipment, are widely used in many printing and manufacturing fields such as food, packaging, and publishing. With the popularization of machine vision inspection technology, online vision inspection systems have been widely used in sheet-fed offset printing press production lines to perform real-time online detection and alarm for printing defects on the paper surface and inherent flaws in raw materials during high-speed printing operations.

[0003] However, existing sheet-fed offset printing presses and their receiving systems still have the following shortcomings in practical applications: Firstly, the fixed action of the gripper opening mechanism in the finished product receiving area makes it difficult to achieve online selective diversion. Existing sheet-fed offset printing presses typically have a fixed gripper block above the finished product unloading tray. All circulating gripper bars are mechanically triggered to open the grippers when passing this position, releasing all the paper onto the finished product unloading tray. When the online vision inspection system identifies defective or waste products, the lack of a real-time, maneuverable gripper control structure prevents the gripper bars holding the waste products from skipping the finished product unloading station. This results in the waste products being directly mixed into the qualified finished product pile, necessitating subsequent arduous offline manual sorting, severely diminishing the practical application value of online vision inspection.

[0004] Secondly, the transfer and attitude control of waste paper under high-speed dynamic operating conditions is challenging. Sheet-fed offset printing presses operate at high linear speeds. At the moment waste paper is released from the gripper bar, papers of different weights and stiffness are easily affected by high-speed turbulent airflow and inertia, resulting in drifting, rolling, or wrinkling. Conventional flow-guiding structures cannot ensure that the paper, detached from the gripper bar at high speed, is instantly and smoothly bonded and transferred, easily leading to paper jams, collisions, or deviations at the feed inlet, affecting the stability of continuous equipment operation.

[0005] Third, the vacuum energy consumption of the negative pressure conveying mechanism is high and it is prone to causing mechanical abrasions on the paper surface. The existing negative pressure auxiliary adsorption mechanism usually provides negative pressure continuously in the entire circumferential direction, and continues to pump vacuum in the angular range of non-adsorption conditions, resulting in a large amount of ineffective vacuum energy consumption and air circuit load; at the same time, the existing adsorption wheel and drive belt structure lacks a flexible spacing adjustment structure for different width conditions, and the edges of the belt and wheel grooves are prone to forming hard indentations and wear on the paper surface, making it difficult to meet the structural adaptability and protection requirements of the rejection conveying mechanism for high-quality post-printing processing.

[0006] Therefore, how to design a rejection system that can be precisely linked with online detection signals, achieve stable waste transfer, low-energy adsorption, controlled conveying, and independent collection in the continuous production state of high-speed printing presses without stopping, has become a technical problem that urgently needs to be solved in the field of sheet-fed offset printing equipment. Summary of the Invention

[0007] The technical problem this invention aims to solve is: Addressing the issue that existing visual online inspection systems for sheet-fed offset printing presses can only detect but not automatically remove defective products, leading to the mixing of defective products with qualified finished products, this invention provides an automatic defect removal system suitable for online inspection in sheet-fed offset printing. This system allows the gripper bar holding the defective product to bypass the finished product unloading station and release the defective product at a designated position with a delayed opening, solving the problem of fixed opening mechanism movements and inability to selectively divert based on online inspection results in existing systems. It also ensures that the defective paper maintains a controlled posture and smoothly enters the rejection mechanism during high-speed transfer, solving the problems of drifting, rolling, wrinkling, and paper jams caused by airflow disturbances and inertia when the paper leaves the gripper bar at high speeds. Simultaneously, it achieves zoned negative pressure adsorption, adjustable spacing, and indentation-free conveying of the paper surface, solving the problems of high vacuum energy consumption, inability to adapt to different paper widths, and indentation damage to the paper caused by the edges of belts and wheel grooves in existing negative pressure adsorption conveying mechanisms. Thus, it achieves automatic diversion, smooth conveying, and independent collection of defective products in continuous production without stopping the printing press.

[0008] This invention provides an automatic waste rejection system suitable for online detection in sheet-fed offset printing, used in conjunction with the gripper bar of a sheet-fed offset printing press, characterized by comprising: frame; A movable bidirectional tooth-opening mechanism is installed on the frame. The movable bidirectional tooth-opening mechanism includes a bidirectional tooth-opening block and a tooth-opening block motion control component. The tooth-opening block motion control component controls the bidirectional tooth-opening block to switch between a working position that opens the paper gripper bar and a clearance position that keeps the paper gripper bar closed. The bidirectional tooth-opening block has an upstream tooth-opening trajectory and a downstream tooth-opening trajectory along the movement direction of the paper gripper bar. When the bidirectional tooth-opening block is in the working position, the upstream tooth-opening trajectory opens the paper gripper bar that passes by. When it is in the clearance position, the upstream tooth-opening trajectory avoids the paper gripper bar that passes by, keeping it closed. The downstream tooth-opening trajectory can continue to control the opening of the paper gripper bar that passes by. A negative pressure wheel is rotatably mounted on the frame; A paper guiding structure is installed on the frame, located below the movement trajectory of the paper gripper bar, with the discharge end of the paper guiding structure facing the feed side of the negative pressure wheel. A positive pressure blowing device is installed on the frame and has an air blowing port facing the position where the paper guide structure is connected to the negative pressure wheel. A negative pressure air seat is disposed on the frame and sealed with the negative pressure wheel, and the negative pressure air seat is provided with a vacuum port; A covered belt assembly is disposed on at least a portion of the outer periphery of the negative pressure wheel and moves synchronously with the negative pressure wheel; A discharge guide structure is provided on the discharge side of the negative pressure wheel; The receiving box is located below the discharge guide structure; A drive unit, mounted on the frame, is connected to the negative pressure wheel via a transmission; and The control unit is electrically connected to the movable bidirectional tooth-opening mechanism and communicatively connected to the online visual inspection system.

[0009] Furthermore, the movable bidirectional tooth-opening mechanism includes a movable bidirectional tooth-opening assembly, which includes a driving member and a bidirectional tooth-opening block body. The bidirectional tooth-opening block body constitutes the bidirectional tooth-opening block. The driving member is disposed on the frame, and the bidirectional tooth-opening block body is connected to the driving member. The bidirectional tooth-opening block body switches between the working position and the avoidance position under the drive of the driving member.

[0010] Furthermore, the driving component is a cylinder, and the piston rod of the cylinder is connected to the bidirectional toothed block body.

[0011] Furthermore, the negative pressure wheel includes multiple sub-wheels arranged at intervals along the axial direction, each sub-wheel having an independent negative pressure cavity inside, and each sub-wheel having an air intake hole communicating with the corresponding negative pressure cavity on its outer peripheral surface.

[0012] Furthermore, each of the aforementioned negative pressure chambers is connected to a negative pressure source via an independent negative pressure control valve.

[0013] Furthermore, a sealing element is provided between the negative pressure air seat and the end face of the negative pressure wheel. The vacuum port is located in the paper entry angle range of the negative pressure wheel. The vacuum port communicates with the negative pressure wheel within the paper entry angle range, but does not communicate with the negative pressure cavity of the negative pressure wheel within the other angle ranges.

[0014] Furthermore, there are multiple negative pressure gas seats, which are arranged at intervals along the axial direction of the negative pressure wheel, and the spacing between adjacent negative pressure gas seats is adjustable.

[0015] Furthermore, the covering belt assembly includes a first covering belt, which is wound around at least a portion of the upper side of the negative pressure wheel, and a clamping gap is formed between the first covering belt and the outer peripheral surface of the negative pressure wheel for paper to pass through.

[0016] Furthermore, the inlet end of the first covering belt is provided with a C-shaped guide structure, which guides the paper into the clamping gap.

[0017] Furthermore, the tension of the first covered belt is adjustable.

[0018] Furthermore, the covered belt assembly includes a second covered belt, and the outer periphery of the negative pressure wheel is provided with a groove, in which the second covered belt is embedded.

[0019] Furthermore, a gap is reserved between the two side walls of the groove and the two side edges of the second covering belt.

[0020] Furthermore, the paper guiding structure is an arc-shaped guide, which extends arc-shapedly from the paper gripper movement trajectory toward the feed side of the negative pressure wheel.

[0021] Furthermore, it also includes a swing guide roller, which is disposed above the feed side of the negative pressure wheel, and a paper feed opening is formed between the swing guide roller and the negative pressure wheel. The angle of the swing guide roller is adjustable to adjust the size of the paper feed opening.

[0022] Furthermore, the discharge guiding structure is an inclined guide groove, with the upper end of the inclined guide groove located on the discharge side of the negative pressure wheel and the lower end facing the receiving box.

[0023] Furthermore, the driving device is a speed-regulating drive motor.

[0024] This invention also provides an automatic rejection control method for waste products in online detection of sheet-fed offset printing. The automatic rejection system includes the following steps: detection and tracking, upstream selective avoidance, downstream delayed opening release, guiding and air blowing assistance, zoned negative pressure adsorption and clamping conveying, and negative pressure disconnection unloading. The control unit is linked with the movable bidirectional opening assembly and the online vision detection system to complete the automatic rejection of waste products in the continuous production state of the printing press without stopping. For details of the specific steps, please refer to the specific implementation method.

[0025] The present invention provides an automatic waste rejection system suitable for online detection in sheet-fed offset printing, which has the following advantages compared with the prior art: By setting up a movable bidirectional opening mechanism and electrically connecting the movable bidirectional opening component to the control unit, the bidirectional opening block body is in the working position during normal printing press operation. Its upstream opening trajectory allows the gripper bar holding qualified products to open and discharge normally. When a waste signal is received from the online vision inspection system, the control unit drives the movable bidirectional opening component to switch to the avoidance position. The upstream opening trajectory of the bidirectional opening block body exits the gripper bar movement trajectory, allowing the gripper bar holding waste products to remain closed, passing over the finished product discharge station, and continuing to run to the downstream opening trajectory of the bidirectional opening block to open and release the waste products. This structure breaks the limitation of fixed opening action in traditional equipment, allowing the waste removal process to be seamlessly connected with the continuous operation of the printing press. Waste diversion can be completed without stopping the machine. The maximum linear speed of the waste removal wheel can reach 240m / min, which can adapt to the high-speed operation of sheet-fed offset printing presses.

[0026] By setting a paper guide structure with the discharge end facing the negative pressure wheel below the paper gripper's movement trajectory, and setting a positive pressure blowing device at the junction of the paper guide structure and the negative pressure wheel, the paper guide structure provides arc-shaped support and guidance for the paper at the moment the waste paper is released from the gripper track downstream of the bidirectional gripper block. The positive pressure blowing device blows airflow to the position where the paper is tangent to the negative pressure wheel, helping the waste paper to instantly flatten and adhere to the outer circumference of the negative pressure wheel. Combined with the first covering belt with a C-shaped guide structure at the inlet and the angle-adjustable swing guide roller, the size of the paper inlet opening can be flexibly adjusted to adapt to papers with different basis weights and stiffness, ensuring that the waste paper that is released from the gripper at high speed is smoothly guided into the clamping gap, effectively eliminating the risk of overturning, slippage and paper jam caused by high-speed airflow disturbance.

[0027] By setting multiple independent negative pressure chambers inside the negative pressure wheel and opening vacuum ports on the negative pressure air seats that are only connected within the paper infeed angle range, the negative pressure wheel generates negative pressure adsorption only within the angle range where waste paper needs to be adsorbed, while cutting off the negative pressure in other angle ranges. This avoids the ineffective energy consumption and air circuit load caused by continuous vacuuming around the entire circumference. Through the axially spaced and adjustable negative pressure air seats and seals, the adsorption position can be flexibly adjusted according to the different widths of the processed paper. At the same time, the second covering belt is embedded in the groove on the outer circumference of the negative pressure wheel, and gaps are reserved between the side walls of the groove and the edge of the second covering belt. This allows the belt and the negative pressure adsorption to work together to clamp the paper, ensuring the stability of paper transmission under high-speed operation and preventing the hard edge of the groove from squeezing and scratching the paper surface, thus meeting the protection requirements of high-precision post-printing processing.

[0028] By setting an inclined discharge guide structure extending to the receiving box below the negative pressure wheel that is no longer in the negative pressure zone, the negative pressure disappears when the negative pressure wheel holding the waste paper rotates out of the paper infeed angle range. The waste paper smoothly leaves the negative pressure wheel by its own gravity and centrifugal force and automatically slides down the inclined guide groove into the independent receiving box. The whole process does not interfere with the normal finished product collection process, avoids defective waste products from being mixed into the finished product pile, and ensures the quality stability of the printed products leaving the factory. Attached Figure Description

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments; Figure 1 This is an isometric schematic diagram of the overall structure of the automatic waste rejection system of the present invention; Figure 2 This is a schematic diagram showing the installation position of the movable bidirectional tooth-opening mechanism of the present invention; Figure 3 This is a schematic diagram showing the installation position of the automatic waste rejection system of the present invention on a sheet-fed offset printing press; Figure 4 This is a front view of the automatic waste rejection system of the present invention and a partial enlarged view of the movable bidirectional tooth-opening mechanism; Figure 5 This is a three-dimensional structural diagram of the automatic waste rejection system of the present invention.

[0030] In the diagram: 1. Paper guiding structure; 2. Positive pressure blowing device; 3. Swinging guide roller; 4. Negative pressure wheel; 5. Negative pressure air seat; 6. First covering belt; 7. Second covering belt. Detailed Implementation

[0031] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0032] Example 1 Reference Figures 1 to 5 This invention provides an automatic waste rejection system suitable for online detection in sheet-fed offset printing, used in conjunction with the gripper bar of a sheet-fed offset printing press. Its features include: frame; A movable bidirectional tooth-opening mechanism is installed on the frame. The movable bidirectional tooth-opening mechanism includes a bidirectional tooth-opening block and a tooth-opening block motion control component. The tooth-opening block motion control component controls the bidirectional tooth-opening block to switch between a working position that opens the paper gripper bar and a clearance position that keeps the paper gripper bar closed. The bidirectional tooth-opening block has an upstream tooth-opening trajectory and a downstream tooth-opening trajectory along the movement direction of the paper gripper bar. When the bidirectional tooth-opening block is in the working position, the upstream tooth-opening trajectory opens the paper gripper bar that passes by. When it is in the clearance position, the upstream tooth-opening trajectory avoids the paper gripper bar that passes by, keeping it closed. The downstream tooth-opening trajectory can continue to control the opening of the paper gripper bar that passes by. A negative pressure wheel is rotatably mounted on the frame; A paper guiding structure is installed on the frame, located below the movement trajectory of the paper gripper bar, with the discharge end of the paper guiding structure facing the feed side of the negative pressure wheel. A positive pressure blowing device is installed on the frame and has an air blowing port facing the position where the paper guide structure is connected to the negative pressure wheel. A negative pressure air seat is disposed on the frame and sealed with the negative pressure wheel, and the negative pressure air seat is provided with a vacuum port; A covered belt assembly is disposed on at least a portion of the outer periphery of the negative pressure wheel and moves synchronously with the negative pressure wheel; A discharge guide structure is provided on the discharge side of the negative pressure wheel; The receiving box is located below the discharge guide structure; A drive unit, mounted on the frame, is connected to the negative pressure wheel via a transmission; and The control unit is electrically connected to the movable bidirectional tooth-opening mechanism and communicatively connected to the online visual inspection system.

[0033] As one implementation, the movable bidirectional tooth-opening mechanism in this embodiment includes a movable bidirectional tooth-opening assembly. The movable bidirectional tooth-opening assembly includes a driving member and a bidirectional tooth-opening block body. The bidirectional tooth-opening block body constitutes the bidirectional tooth-opening block. The driving member is disposed on the frame. The bidirectional tooth-opening block body is connected to the driving member. The bidirectional tooth-opening block body switches between the working position and the avoidance position under the drive of the driving member.

[0034] In one embodiment, the driving component is a cylinder, and the piston rod of the cylinder is connected to the bidirectional toothed block body.

[0035] In one embodiment, the negative pressure wheel in this embodiment includes multiple sub-wheels arranged at intervals along the axial direction. Each sub-wheel has an independent negative pressure cavity inside, and the outer peripheral surface of each sub-wheel has a suction hole that communicates with the corresponding negative pressure cavity.

[0036] In one implementation, each of the negative pressure cavities in this embodiment is connected to a negative pressure source via an independent negative pressure control valve.

[0037] In one embodiment, a sealing element is provided between the negative pressure air seat and the end face of the negative pressure wheel in this embodiment. The vacuum port is located in the paper entry angle range of the negative pressure wheel. The vacuum port is connected to the negative pressure wheel in the paper entry angle range, and is not connected to the negative pressure cavity of the negative pressure wheel in other angle ranges.

[0038] In one embodiment, the number of negative pressure gas seats in this embodiment is multiple, and the multiple negative pressure gas seats are arranged at intervals along the axial direction of the negative pressure wheel, and the spacing between adjacent negative pressure gas seats is adjustable.

[0039] In one embodiment, the covering belt assembly in this embodiment includes a first covering belt, which is wound around at least a portion of the upper side of the negative pressure wheel, and a clamping gap is formed between the first covering belt and the outer peripheral surface of the negative pressure wheel for paper to pass through.

[0040] In one embodiment, the inlet end of the first covering belt is provided with a C-shaped guide structure, which guides the paper into the clamping gap.

[0041] In one embodiment, the tension of the first covering belt is adjustable.

[0042] In one embodiment, the covered belt assembly in this embodiment includes a second covered belt, and the outer periphery of the negative pressure wheel is provided with a groove, in which the second covered belt is embedded.

[0043] In one embodiment, a gap is reserved between the two side walls of the groove and the two side edges of the second covering belt.

[0044] In one embodiment, the paper guiding structure is an arc-shaped guide that extends arc-shapedly from the paper gripper track towards the feed side of the negative pressure wheel.

[0045] As one implementation, this embodiment also includes a swing guide roller, which is disposed above the feed side of the negative pressure wheel. A paper feed opening is formed between the swing guide roller and the negative pressure wheel. The angle of the swing guide roller is adjustable to adjust the size of the paper feed opening.

[0046] In one embodiment, the discharge guiding structure described in this example is an inclined guide groove, with the upper end of the inclined guide groove located on the discharge side of the negative pressure wheel and the lower end facing the receiving box.

[0047] In one implementation, the driving device described in this embodiment is a speed-regulating drive motor.

[0048] Example 2 like Figures 1 to 5 As shown, this embodiment provides an automatic waste rejection system suitable for online detection of sheet-fed offset printing, including a frame, a movable bidirectional toothing mechanism, a paper guiding structure 1, a positive pressure blowing device 2, a swing guide roller 3, a negative pressure wheel 4, a negative pressure air seat 5, a first covering belt 6, a second covering belt 7, a covering belt assembly, a discharge guiding structure, a receiving box, a drive device, and a control unit.

[0049] The frame is a sheet metal frame structure, directly mounted on the maintenance window above the finished product feeding tray of the sheet offset printing machine. The movable bidirectional toothing mechanism, paper guide structure 1, negative pressure wheel 4, negative pressure air seat 5, covered belt assembly, discharge guide structure and drive device are all mounted on the frame.

[0050] I. Removable bidirectional dental opener like Figure 2 and Figure 4 As shown, the movable bidirectional opening mechanism is located at the normal opening position above the finished product feeding tray of the sheet-fed offset printing press. In the bidirectional opening block of the movable bidirectional opening mechanism, the opening vertex located on the upstream opening trajectory line is located at the normal opening point above the finished product feeding tray, and the opening vertex located on the downstream opening trajectory line is located at the center point downstream of the paper gripper bar's movement direction, where it intersects with the waste rejection station.

[0051] The movable bidirectional tooth-opening assembly includes a drive component and a bidirectional tooth-opening block body. In this embodiment, the drive component is a cylinder, the cylinder body of which is mounted on the frame, and the piston rod of the cylinder is connected to the bidirectional tooth-opening block body. Driven by the cylinder, the bidirectional tooth-opening block body has two positions: a working position and a clearance position. When the bidirectional tooth-opening block body is in the working position, it extends into the movement trajectory of the gripper bar. When the gripper bar passes by, it is triggered to open teeth by the upstream tooth-opening trajectory line of the bidirectional tooth-opening block body. When the bidirectional tooth-opening block body is in the clearance position, its upstream tooth-opening trajectory line exits the movement trajectory of the gripper bar. When the gripper bar passes over the finished product discharge tray, it is not triggered and remains closed. It continues to run carrying waste products until it reaches the downstream tooth-opening trajectory line of the bidirectional tooth-opening block body, where it is triggered to open teeth.

[0052] II. Paper guiding structure like Figure 1 and Figure 4 As shown, the paper guiding structure 1 is an arc-shaped guide made of sheet metal bending. It is located below the paper gripper movement trajectory, specifically below the downstream opening trajectory line of the bidirectional opening block body. The paper guiding structure 1 extends arc-shaped from below the paper gripper movement trajectory towards the feed side of the negative pressure wheel 4, with its discharge end facing the feed side of the negative pressure wheel 4. It guides the waste paper released from the downstream opening trajectory line of the bidirectional opening block body into the negative pressure wheel 4 via an arc-shaped path.

[0053] III. Positive pressure air blowing device like Figure 1 and Figure 4 As shown, the positive pressure blowing device 2 includes a blowing nozzle and an air supply line. The blowing nozzle is mounted on the frame, and its blowing port faces the tangential position where the paper guide structure 1 and the negative pressure wheel 4 meet. The air supply line is connected to a compressed air source, and the blowing nozzle blows a positive airflow towards the tangential position to help the waste paper adhere to the outer peripheral surface of the negative pressure wheel 4.

[0054] IV. Negative Pressure Wheel like Figure 1 and Figure 5 As shown, the negative pressure roller 4 is rotatably mounted on the frame, located at the discharge end of the paper guiding structure 1. The negative pressure roller 4 includes multiple sub-rollers arranged axially at intervals, each sub-roller coaxially mounted on the same rotating shaft. Each sub-roller has an independent negative pressure chamber inside, and multiple suction holes are provided on the outer circumferential surface of each sub-roller. The suction holes are evenly distributed along the circumference of the sub-roller and communicate with the corresponding negative pressure chamber. Grooves are formed between adjacent sub-rollers.

[0055] Each negative pressure chamber is connected to a negative pressure source via an independent negative pressure control valve. In this embodiment, the negative pressure control valve is a high-speed negative pressure solenoid valve, which can independently control the negative pressure on / off of each negative pressure chamber, thereby achieving regional negative pressure generation. The negative pressure wheel 4 runs clockwise (from...). Figure 4 (View from a perspective) The maximum linear speed can reach 240m / min, and the rotation speed can be adjusted independently.

[0056] V. Negative Pressure Air Seat like Figure 1 and Figure 5 As shown, the negative pressure air seat 5 is mounted on the frame and seals against the end face of the negative pressure wheel 4. A sealing element is provided between the negative pressure air seat 5 and the end face of the negative pressure wheel 4. In this embodiment, the sealing element is a wear-resistant, low-friction sealing sheet. A vacuum port is provided on the negative pressure air seat 5, and the vacuum port is connected to a negative pressure source through a pipeline. The vacuum port is located in the paper entry angle range of the negative pressure wheel 4, that is, within the angle range where waste paper enters the negative pressure wheel 4 and needs to be adsorbed. When the negative pressure wheel 4 rotates, the negative pressure cavity of the wheel passes through the angle range where the vacuum port is located and connects with the vacuum port to generate negative pressure. In other angle ranges, the negative pressure cavity is not connected with the vacuum port, and no negative pressure is generated.

[0057] There are multiple negative pressure air seats 5, each corresponding to a separate rotary disc 4, and these multiple negative pressure air seats 5 are arranged at intervals along the axial direction of the negative pressure rotary disc 4. The spacing between adjacent negative pressure air seats 5 is adjustable to accommodate paper of different widths. In this embodiment, the negative pressure air seats 5 are installed on the frame through oblong holes and fasteners. After loosening the fasteners, the position of the negative pressure air seats 5 can be adjusted axially, and then tightened again.

[0058] VI. Covered belt assembly The covered belt assembly includes a first covered belt 6 and a second covered belt 7.

[0059] like Figure 1 , Figure 4 and Figure 5 As shown, the first covering belt 6, also known as the upper covering belt, is wound around at least a portion of the upper side of the negative pressure wheel 4. The belt path is fan-shaped and presses downwards, covering the upper circumference of the negative pressure wheel 4. The first covering belt 6 is wound around multiple guide rollers and tension rollers, and is driven to move synchronously by the rotation of the negative pressure wheel 4 through friction. A clamping gap is formed between the first covering belt 6 and the outer circumferential surface of the negative pressure wheel 4 to allow the paper to pass through. The belt applies a clamping force, pressing the waste paper entering the clamping gap onto the outer circumferential surface of the negative pressure wheel 4, ensuring that the paper is completely controlled when it first enters the wheel.

[0060] The inlet end of the first wrapping belt 6 is equipped with a C-shaped guide structure. The C-shaped guide structure is a C-shaped guide sheet metal structure that guides the paper into the clamping gap. It works in conjunction with the positive pressure blowing device 2 to enhance the stability of the paper-adhering wheel as it enters the belt. The tension of the first wrapping belt 6 can be adjusted by the tension roller to accommodate papers of different weights and stiffnesses, preventing wrinkles and slippage.

[0061] like Figure 1 and Figure 5As shown, the second covering belt 7, also known as the embedded covering belt, is embedded in the groove on the outer periphery of the negative pressure wheel 4, specifically in the groove between adjacent dividing wheels. The second covering belt 7 is entirely enclosed in the groove and is driven by the main drive of the negative pressure wheel 4, rotating synchronously with it without relative slippage. The outer surface of the second covering belt 7 is in direct contact with the surface of the waste paper, working in conjunction with the suction force of the negative pressure cavity to clamp the paper, ensuring the stability of paper conveying under high tension and high speed.

[0062] A gap is reserved between the two side walls of the groove and the two side edges of the second covering belt 7, so that the edges of the second covering belt 7 do not contact the side walls of the groove, thus preventing indentation damage to the paper edges and adapting to high-precision post-printing processing requirements. The tension of the second covering belt 7 can be manually adjusted via the side adjusting bolts, making maintenance convenient and adaptable to paper of different widths and weights.

[0063] VII. Oscillating Guide Roller like Figure 1 and Figure 4 As shown, the oscillating guide roller 3 is positioned above the feed side of the negative pressure wheel 4, at the entrance of the first covering belt 6. The oscillating guide roller 3 features an adjustable overall oscillation angle, with both ends mounted to the frame via oscillation brackets. The angle of the oscillation brackets can be fixed using adjusting screws. A paper feed opening is formed between the oscillating guide roller 3 and the lower negative pressure wheel 4. By adjusting the oscillation angle of the oscillating guide roller 3, the size of the paper feed opening can be flexibly adjusted to accommodate papers of different thicknesses and stiffnesses according to process requirements.

[0064] 8. Discharge guiding structure and receiving box like Figure 4 As shown, the discharge guiding structure is an inclined guide groove, located on the discharge side of the negative pressure wheel 4. The upper end of the inclined guide groove is below the end of the negative pressure action area of ​​the negative pressure wheel 4, and the lower end faces the receiving box. The receiving box is located below the discharge guiding structure and is an independent waste collection box. When the negative pressure wheel 4, which adsorbs waste paper, rotates out of the negative pressure action area, the negative pressure chamber is disconnected from the vacuum port, the negative pressure disappears, and the waste paper detaches from the negative pressure wheel 4 under its own gravity and centrifugal force, sliding down the inclined guide groove into the receiving box.

[0065] IX. Drive Unit and Control Unit like Figure 1 and Figure 5 As shown, the drive unit is a speed-regulating drive motor, mounted on the frame, and connected to the rotating shaft of the negative pressure wheel 4 via a synchronous belt transmission mechanism. The speed of the speed-regulating drive motor is adjustable, thereby independently adjusting the linear velocity of the negative pressure wheel 4.

[0066] The control unit is installed in the frame or electrical cabinet, electrically connected to the cylinder solenoid valve of the movable bidirectional gripper assembly, and communicatively connected to the online vision inspection system of the sheet-fed offset printing press. The control unit receives the waste signal from the online vision inspection system, records the position information of the gripper bar where the waste is located, and tracks the movement of the gripper bar. When the gripper bar moves to the movable bidirectional gripper assembly, the control cylinder drives the bidirectional gripper block body to switch to the avoidance position.

[0067] 10. Work Process The working process of this invention is as follows: During normal operation of a sheet-fed offset printing press, the online vision inspection system monitors the printing quality in real time. When a defective product is detected, the online vision inspection system sends a defect signal to the control unit. The control unit records the position of the gripper bar containing the defective product and tracks its movement.

[0068] When the gripper holding waste paper reaches the movable bidirectional opening assembly above the finished product discharge tray, the control unit controls the cylinder to drive the bidirectional opening block body to switch to the avoidance position. The bidirectional opening block body, located on the upstream opening trajectory line, exits the gripper's movement trajectory. The gripper remains closed without being triggered to open, continuing to run along the circulation line carrying waste paper. When the gripper holding qualified paper passes the movable bidirectional opening assembly, the bidirectional opening block body is in the working position, opening normally along the upstream opening trajectory line, and the qualified paper falls into the finished product discharge tray.

[0069] As the paper gripper carrying the waste paper continues to move until the bidirectional gripper block body is located at the downstream gripper trajectory line, the bidirectional gripper block body triggers the gripper to open, releasing the waste paper. The leading edge of the waste paper enters the paper guide structure 1 first and slides along the arc-shaped guide surface towards the feed side of the negative pressure wheel 4. At the same time, the positive pressure blowing device 2 blows airflow towards the position where the paper is tangent to the negative pressure wheel 4, assisting the waste paper to adhere to the outer circumference of the negative pressure wheel 4. The paper feed opening between the oscillating guide roller 3 and the negative pressure wheel 4 guides and limits the paper, and the C-shaped guide structure guides the paper into the clamping gap between the first covering belt 6 and the negative pressure wheel 4.

[0070] Driven by the drive device, the negative pressure wheel 4 rotates clockwise. Within the paper infeed angle range, the negative pressure chamber generates negative pressure through the vacuum port, and the suction hole adsorbs waste paper. The first covering belt 6 presses the paper from above, and the second covering belt 7 cooperates with the negative pressure adsorption to clamp the paper in the groove, so that the waste paper is transported with the negative pressure wheel 4 under the combined action of negative pressure adsorption and belt clamping.

[0071] When the waste paper rotates out of the paper inlet / outlet angle range with the negative pressure wheel 4, the negative pressure chamber is disconnected from the vacuum port, the negative pressure disappears, and the waste paper is released from the negative pressure wheel 4 under its own gravity and centrifugal force, and slides down the inclined guide groove into the receiving box, thus completing the waste rejection.

[0072] During the above process, each negative pressure chamber generates negative pressure only within the paper infeed angle range, and there is no negative pressure in other angle ranges, thus avoiding ineffective energy consumption; a gap is reserved between the second covering belt 7 and the side wall of the groove to avoid damaging the paper edge; the entire rejection process is automatically completed in the continuous production state of the printing press without stopping, without affecting the normal product receiving process.

[0073] Example 3 This embodiment provides an automatic rejection control method for waste products in online detection of sheet-fed offset printing. The method employs the automatic rejection system described in Embodiments 1 and 2, and includes the following steps: Step S1, Detection and Tracking: When the sheet-fed offset printing press is running normally, the online vision inspection system detects the printing quality in real time. When a defective product is detected, the online vision inspection system sends the defect signal to the control unit. The control unit records the position of the gripper bar where the defective product is located and tracks its movement.

[0074] Step S2, upstream selective avoidance: When the gripper holding waste products moves to the movable bidirectional opening component above the finished product discharge tray, the control unit controls the cylinder to drive the bidirectional opening block body to switch to the avoidance position. The upstream opening trajectory line of the bidirectional opening block body exits the gripper's movement trajectory, and the waste product gripper is not triggered to open and remains closed, carrying the waste product past the finished product discharge station; while when the gripper holding qualified products passes the movable bidirectional opening component, the bidirectional opening block body is in the working position and opens normally by the upstream opening trajectory line, and the qualified products fall into the finished product discharge tray.

[0075] Step S3, Downstream Delayed Tooth Release: When the paper gripper bar holding the waste continues to run to the downstream tooth opening trajectory line of the bidirectional tooth opening block body, the bidirectional tooth opening block body triggers the paper gripper bar to open, and the waste paper is released.

[0076] Step S4, Guiding and Air Blowing Assistance: The front end of the released waste paper enters the paper guiding structure and slides along the arc-shaped guide surface towards the feeding side of the negative pressure wheel. At the same time, the positive pressure blowing device blows airflow to the position where the paper is tangent to the negative pressure wheel, assisting the waste paper to adhere to the outer circumference of the negative pressure wheel. The paper feeding opening between the swing guide roller and the negative pressure wheel guides and limits the paper, and the C-shaped guide structure guides the paper into the clamping gap between the first covering belt and the negative pressure wheel.

[0077] Step S5, Negative Pressure Adsorption and Clamping Conveying: The negative pressure wheel rotates under the drive of the drive device. Within the paper infeed angle range, the corresponding negative pressure chamber generates negative pressure through the vacuum port and adsorbs waste paper through the suction hole. The first covering belt presses the paper from above, and the second covering belt clamps the paper in the groove with the negative pressure adsorption. The waste paper is conveyed with the negative pressure wheel under the combined action of negative pressure adsorption and clamping by the covering belt. Each negative pressure chamber generates negative pressure only within the paper infeed angle range, and there is no negative pressure in other angle ranges.

[0078] Step S6, Disconnecting negative pressure and unloading: When the waste paper rotates out of the paper inlet / outlet angle range with the negative pressure wheel, the corresponding negative pressure chamber is disconnected from the vacuum port and the negative pressure disappears. The waste paper is released from the negative pressure wheel under its own gravity and centrifugal force and slides down into the receiving box along the discharge guide structure. The entire waste rejection process is automatically completed in the continuous production state of the printing press without stopping.

[0079] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. An automatic waste rejection system suitable for online detection in sheet-fed offset printing, used in conjunction with the gripper bar of a sheet-fed offset printing press, characterized in that, include: frame; A movable bidirectional tooth-opening mechanism is installed on the frame. The movable bidirectional tooth-opening mechanism includes a bidirectional tooth-opening block and a tooth-opening block motion control component. The tooth-opening block motion control component controls the bidirectional tooth-opening block to switch between a working position that opens the paper gripper bar and a clearance position that keeps the paper gripper bar closed. The bidirectional tooth-opening block has an upstream tooth-opening trajectory and a downstream tooth-opening trajectory along the movement direction of the paper gripper bar. When the bidirectional tooth-opening block is in the working position, the upstream tooth-opening trajectory opens the paper gripper bar that passes by. When it is in the clearance position, the upstream tooth-opening trajectory avoids the paper gripper bar that passes by, keeping it closed. The downstream tooth-opening trajectory can continue to control the opening of the paper gripper bar that passes by. A negative pressure wheel is rotatably mounted on the frame; A paper guiding structure is installed on the frame, located below the movement trajectory of the paper gripper bar, with the discharge end of the paper guiding structure facing the feed side of the negative pressure wheel. A positive pressure blowing device is installed on the frame and has an air blowing port facing the position where the paper guide structure is connected to the negative pressure wheel. A negative pressure air seat is disposed on the frame and sealed with the negative pressure wheel, and the negative pressure air seat is provided with a vacuum port; A covered belt assembly is disposed on at least a portion of the outer periphery of the negative pressure wheel and moves synchronously with the negative pressure wheel; A discharge guide structure is provided on the discharge side of the negative pressure wheel; The receiving box is located below the discharge guide structure; The drive unit is mounted on the frame and is connected to the negative pressure wheel via a transmission. as well as The control unit is electrically connected to the movable bidirectional tooth-opening mechanism and communicatively connected to the online visual inspection system.

2. The automatic waste rejection system according to claim 1, characterized in that, The movable bidirectional tooth-opening mechanism includes a movable bidirectional tooth-opening assembly, which includes a drive component and a bidirectional tooth-opening block body. The bidirectional tooth-opening block body constitutes the bidirectional tooth-opening block. The drive component is disposed on the frame, and the bidirectional tooth-opening block body is connected to the drive component. The bidirectional tooth-opening block body switches between the working position and the avoidance position under the drive of the drive component.

3. The automatic waste rejection system according to claim 2, characterized in that, The driving component is a cylinder, and the piston rod of the cylinder is connected to the body of the bidirectional toothed block.

4. The automatic waste rejection system according to claim 1, characterized in that, The negative pressure wheel includes multiple sub-wheels arranged at intervals along the axial direction. Each sub-wheel has an independent negative pressure cavity inside, and each sub-wheel has an air suction hole on its outer peripheral surface that communicates with the corresponding negative pressure cavity.

5. The automatic waste rejection system according to claim 4, characterized in that, Each of the aforementioned negative pressure chambers is connected to a negative pressure source via an independent negative pressure control valve.

6. The automatic waste rejection system according to claim 1, characterized in that, A sealing element is provided between the negative pressure air seat and the end face of the negative pressure wheel. The vacuum port is located in the paper entry angle range of the negative pressure wheel. The vacuum port is connected to the negative pressure wheel within the paper entry angle range, and is not connected to the negative pressure cavity of the negative pressure wheel within the other angle ranges.

7. The automatic waste rejection system according to claim 1, characterized in that, The number of negative pressure gas seats is multiple, and the multiple negative pressure gas seats are arranged at intervals along the axial direction of the negative pressure wheel, and the spacing between adjacent negative pressure gas seats is adjustable.

8. The automatic waste rejection system according to claim 1, characterized in that, The covering belt assembly includes a first covering belt, which is wound around at least a portion of the upper side of the negative pressure wheel, and a clamping gap is formed between the first covering belt and the outer peripheral surface of the negative pressure wheel for paper to pass through.

9. The automatic waste rejection system according to claim 8, characterized in that, The inlet end of the first covering belt is provided with a C-shaped guide structure, which guides the paper into the clamping gap.

10. The automatic waste rejection system according to claim 1, characterized in that, The covered belt assembly includes a second covered belt, and the outer periphery of the negative pressure wheel is provided with a groove, in which the second covered belt is embedded.

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