A non-stop roller changing device and method for flexographic printing press

Abstract

This invention discloses a non-stop roller changing device and method for a flexographic printing press, belonging to the field of flexographic printing technology. The structure includes a frame and several color groups mounted on the frame. Each color group includes a rotatably mounted roller changing assembly, an impression mechanism, and a drying mechanism. The roller changing assembly is equipped with at least two sets of printing plate rollers, and one set of printing plate rollers can be selectively driven to engage with the impression mechanism. The frame also includes a detection unit and a phase fine-tuning unit for detecting the printed pattern effect and fine-tuning the printing registration accuracy. This invention enables non-stop roller changing in a flexographic printing press, improving production efficiency and ensuring print quality.

Description

Technical Field

[0001] This invention relates to the field of flexographic printing technology, specifically to a non-stop roller changing device and roller changing method for a flexographic printing press. Background Technology

[0002] Flexographic printing presses are one of the most commonly used printing presses. They consist of an anilox roller, a plate roller, and an impression roller, all mounted on a frame. The anilox roller precisely supplies ink to the plate roller, controlling the ink layer thickness and uniformity. The plate roller carries the printed image and transfers the ink to the substrate to form the desired pattern. The impression roller provides stable printing pressure, ensuring a tight fit between the substrate and the plate roller for clear transfer. During printing, the paper passes through the plate roller and impression roller to be printed. The plate roller is usually replaced as needed during the printing process.

[0003] Chinese invention patent publication number "CN210011451U" discloses a flexographic printing machine with an easy-to-disassemble printing spindle. Its printing roller is detachably connected to the printing shaft by a shaft head, a hollow bushing, and a threaded connection, an elastic locking protrusion, and a locking block. The entire printing unit can be raised and lowered vertically under the drive of the drive device, so that the operator can disassemble and replace the printing shaft. This improved roller replacement structure reduces some of the manual operation intensity.

[0004] However, the printing press must be stopped when changing rollers, resulting in low continuity of printing production and limiting production efficiency. Roller changes are fine after printing is completed, but if roller changes are made in the middle of printing, the wet ink adheres to the paper for a long time without being dried. This can cause the edges of text or patterns to become blurry, smudged, or blurred, resulting in poor printing quality. The paper is also prone to absorbing water and swelling, and localized elongation, which affects the tension of subsequent paper and leads to poor color registration. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a non-stop roller changing device and method for flexographic printing presses, enabling rapid plate changing without stopping the printing process and ensuring good printing quality.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A non-stop roller changing device for a flexographic printing press includes a frame and several color groups arranged along the direction of travel of the substrate on the frame. The device is characterized in that: each color group includes a roller changing assembly rotatably mounted on the frame, an impression mechanism, and a drying mechanism for drying the printed substrate; the roller changing assembly is detachably equipped with a first printing plate roller and a second printing plate roller; the impression mechanism is correspondingly equipped with a first impression roller and a second impression roller; the roller changing assembly can selectively drive the first printing plate roller to contact the first impression roller, or drive the second printing plate roller to contact the second impression roller; the frame is also equipped with several detection units and a phase fine-tuning unit; the detection units are located downstream of the last color group and are used to detect the printing pattern effect; the phase fine-tuning unit is used to fine-tune the printing color registration accuracy; the roller changing assembly also includes an inking assembly for supplying ink to the printing process.

[0007] By employing the above technical solution, the roller changing assembly, rotatably mounted on the frame, eliminates the need to stop the printing press during roller changes, maintaining continuous printing production and significantly improving efficiency. The drying mechanism promptly dries the printed substrate, drastically reducing the adhesion time of wet ink on the paper surface. This avoids issues such as blurred edges, smudging, and ink smudging in text or patterns, improving the overall printing display. Simultaneously, it prevents paper from absorbing water and swelling, ensuring stable paper tension and guaranteeing high-quality color registration. The coordinated design of the detection unit and phase fine-tuning unit allows for real-time monitoring and correction of the printed image, resulting in high printing accuracy and quality.

[0008] The above technical solution can be further configured as follows: the roller changing assembly further includes a roller changing turntable, a drive mechanism for driving the roller changing turntable to rotate, and an anilox roller. The roller changing turntable is rotatably mounted on the frame, and the anilox roller and the roller changing turntable can rotate coaxially. The anilox roller and the printing plate roller are both rotatably mounted on the roller changing turntable by means of bearings. The drive mechanism is driven by the roller changing turntable, and when the drive mechanism rotates, it can drive the roller changing turntable to rotate. A first servo motor is provided at the end of the anilox roller, and a second servo motor is provided at the end of the first printing plate roller and the second printing plate roller, respectively. The first servo motor is fixedly mounted on the frame, and its output shaft is driven by the anilox roller. The two second servo motors are fixedly mounted on the roller changing turntable, and their output shafts are driven by the first printing plate roller and the second printing plate roller, respectively.

[0009] By adopting the above technical solution, the cooperative structure of the roller changing turntable and the drive mechanism allows the switching operation of the printing plate roller to be realized through the rotation of the roller changing turntable. This simplifies the mechanical structure of the roller changing action and ensures the stability and reliability of the roller changing process. It is important to note that in this structure, the printing plate roller and the anilox roller remain in contact at all times; that is, the printing plate roller is in an inked state before and after the roller changing. The coaxial rotation design of the anilox roller and the roller changing turntable ensures that the relative positional relationship between the anilox roller and the printing plate roller remains stable during the roller changing process, and the continuity and uniformity of ink supply are not affected. The distributed configuration of the first and second servo motors allows the driving of the anilox roller and the printing plate roller to be independent, improving the flexibility of speed adjustment and enhancing adaptability to different printing conditions. The bearing support structure reduces the rotational resistance of the anilox roller and the printing plate roller, improves transmission efficiency, and reduces the energy consumption of the equipment.

[0010] The above technical solution can be further configured as follows: the driving mechanism includes a driving gear and a driving servo motor, the driving servo motor is fixedly mounted on the frame, the output shaft of the driving servo motor is connected to the driving gear, the roller changing turntable is provided with an external gear ring, and the driving gear and the external gear ring are driven by gear meshing.

[0011] By adopting the above technical solution, the use of gear meshing transmission ensures precise and reliable power transmission between the drive servo motor and the roller changing turntable, guarantees the angular positioning accuracy of the roller changing turntable, and improves the accuracy of the printing plate roller switching position. The mating structure of the external gear ring and the drive gear has high transmission efficiency, low energy loss, and does not interfere with the first servo motor.

[0012] The above technical solution can be further configured as follows: the first impression roller and the second impression roller are rotatably mounted on the frame via bearings; the impression mechanism is also provided with a third servo motor for driving the first impression roller and the second impression roller to rotate, and the third servo motor is fixedly mounted on the frame; the drying mechanism includes a first drying unit corresponding to the first impression roller and a second drying unit corresponding to the second impression roller; the first drying unit is fixedly mounted downstream of the first impression roller on the frame, and the second drying unit is fixedly mounted downstream of the second impression roller on the frame; the first printing plate roller and the second printing plate roller are symmetrically distributed on both sides of the anilox roller on the roller changing turntable, and both are in contact with the anilox roller.

[0013] Using the above technical solution, each of the two sets of printing plate rollers corresponds to an independent impression and drying station, ensuring the continuity of printing and drying operations during roller changing. The first and second drying units are respectively located downstream of the corresponding impression rollers, optimizing the matching between the drying and printing positions and precisely controlling the timing and effect of ink drying. It should be noted that the first and second drying units only start when their respective printing stations are in operation; otherwise, drying stops. That is, the first drying unit only dries the printed substrate when the first printing plate roller and the first impression roller are in contact for printing. When the first printing plate roller and the second impression roller separate, the first drying unit immediately stops drying. Similarly, the second drying unit only operates when the second printing plate roller and the second impression roller are in contact, and does not operate at other times, preventing over-drying and reducing energy consumption. The symmetrical distribution of the two sets of printing plate rollers on both sides of the anilox roller minimizes the rotation angle of the roller changing turntable, shortens roller changing time, and improves roller changing efficiency. Only one set of printing rollers participates in printing at any given time, which avoids printing interference caused by two sets of printing rollers contacting the substrate at the same time, thus ensuring the stability of printing quality.

[0014] The above technical solution can be further configured as follows: the color group also includes a cooling guide mechanism, the cooling guide mechanism includes a first cooling guide roller, a second cooling guide roller and a fourth servo motor that drives the two to rotate; the first cooling guide roller is installed downstream of the first drying unit on the frame, the second cooling guide roller is installed downstream of the second drying unit on the frame, the first cooling guide roller and the second cooling guide roller are rotatably installed on the frame by setting bearings, and the fourth servo motor is fixedly installed on the frame.

[0015] By employing the above technical solution, the downstream configuration of the cooling guide mechanism allows for a rapid reduction in the temperature of the substrate after drying, eliminating deformation and stress caused by high temperatures and restoring the paper's flatness and dimensional stability. The first and second cooling guide rollers correspond to the two sets of drying units, both filled with flowing coolant. Regardless of which set of printing rollers is currently used, the substrate receives timely cooling rather than being in contact with other components in a hot state, ensuring consistent and reliable cooling performance. The bearing support structure of the cooling guide rollers exhibits low rotational resistance, does not affect paper tension, and has low drive energy consumption.

[0016] The above technical solution can be further configured as follows: the inking assembly includes an ink cartridge, an upper ink doctor blade, and a lower ink doctor blade; the upper and lower ink doctor blades are respectively obliquely and detachably installed at the upper and lower ends of the ink cartridge for scraping off excess ink from the surface of the anilox roller; the ink cartridge includes an ink cavity for storing ink and supplying ink to the anilox roller, and an ink outlet for ink to flow out; the ink cavity is generally shaped as larger at the top and smaller at the bottom; the blades of the upper and lower ink doctor blades face the opening direction of the ink outlet.

[0017] The above technical solution employs a dual-scraper configuration with upper and lower ink scrapers. When one scrapes ink, the other acts as a seal, maintaining the scraping effect while preventing ink leakage and improving the precision of ink supply control. The obliquely detachable scraper facilitates disassembly, maintenance, and replacement. The ink chamber's shape, wider at the top and narrower at the bottom, ensures that even as the ink chamber rotates with the changing roller turntable, the ink naturally converges at the lower end under gravity and flows out of the ink outlet, guaranteeing smooth ink flow and improving the continuity and stability of ink supply. The scraped-off blades face the ink outlet opening, allowing excess ink to flow directly back to the outlet, improving ink recycling and reducing ink waste.

[0018] The above technical solution can be further configured as follows: the phase fine-tuning unit is mounted on the frame and includes a phase adjustment groove, a phase fine-tuning roller disposed in the phase adjustment groove, and a phase adjustment mechanism for driving the phase fine-tuning roller to move in the phase adjustment groove; the phase adjustment mechanism includes a phase roller mounting seat slidably mounted in the phase adjustment groove, a worm gear assembly fixedly mounted on the frame, and a worm drive motor fixedly mounted on the frame. The worm gear assembly includes a worm seat fixedly mounted on the frame, a worm rotatably mounted on the worm seat, and a worm wheel rotatably mounted on the frame and cooperating with the worm. The phase roller mounting seat has a rack facing the worm wheel, and the rack matches the tooth profile of the worm wheel. The output shaft of the worm drive motor is connected to the worm drive, and the worm drive motor can drive the phase roller mounting seat to move in the phase adjustment groove when it is working.

[0019] By employing the above technical solution, the sliding fit structure between the phase adjustment groove and the phase fine-tuning roller precisely defines the position adjustment trajectory of the phase fine-tuning roller, ensuring the accuracy of the adjustment direction and the controllability of the adjustment amount. The worm gear transmission mechanism has a large transmission ratio and high adjustment accuracy, improving the resolution of phase fine-tuning and enhancing the fine-tuning effect of color registration accuracy. The self-locking characteristic of the worm gear ensures that the phase fine-tuning roller maintains a stable position after adjustment, preventing positional shift due to external forces during printing and improving the stability of color registration accuracy. The fixed installation configuration of the worm drive motor reduces the impact of motor vibration on phase adjustment accuracy and improves the smoothness of the adjustment process.

[0020] The above technical solution can be further configured as follows: the frame includes two support plates arranged opposite each other, a plurality of connecting beams are arranged between the two support plates, the two ends of each connecting beam are fixedly connected to the two support plates respectively, and a plurality of foot plates are provided at the bottom of each support plate, the foot plates are arranged perpendicular to the support plates, and the foot plates are welded and fixed to the bottom of the support plates.

[0021] The above technical solution, employing a frame structure composed of double support plates and connecting beams, provides high overall rigidity and strong resistance to deformation. This ensures the relative positional stability of each component during printing and improves the long-term maintenance of printing accuracy. The fixed connection between the connecting beams and the support plates at both ends ensures a clear force transmission path, uniform structural stress, and enhanced load-bearing capacity and reliability of the frame. The bottom support structure, with its foot plates perpendicular to the support plates and welded in place, increases the contact area between the frame and the ground, enhancing support stability and reducing vibration transmission during equipment operation. The welded fixed connection offers high strength, low risk of loosening, extended equipment maintenance cycles, and reduced operating costs.

[0022] A roller changing method based on a non-stop roller changing device for a flexographic printing press includes the following steps: S1: When the current printing plate roller is printing, perform plate changing operation on the idle printing plate rollers on each color group roller changing assembly; S2: After all idle printing plate rollers have been replaced, wait for the new printing plate to be fully inked; S3: The roller changing assembly drives the currently working printing plate roller to disengage from the corresponding printing mechanism, and at the same time drives the printing plate roller that has completed the plate change to rotate to the position where it is attached to its corresponding printing mechanism. S4: Each color group performs the roller changing operation of S3 in sequence; S5: Take a still photo of the printed pattern after roller change through the detection unit to check the color registration effect. If the color registration is not accurate, make fine-tuning of the color registration through the phase fine-tuning unit.

[0023] Using the above technical solution, step S1 employs a parallel operation mode where idle printing plate rollers are used for plate changing during the current printing process. The plate changing time overlaps with the printing time, eliminating the impact of plate changing on production continuity, extending the effective operating time of the equipment, and significantly improving production efficiency. Step S2 waits for the new printing plate to be fully inked, ensuring uniform ink distribution on the surface of the printing plate roller after the roller change, guaranteeing the quality of the first printed product after the roller change, and reducing the scrap rate. Step S3 synchronizes the actions of the roller changing assembly in disengaging the old printing plate roller and engaging the new printing plate roller, completing the roller changing process in one go, shortening the roller changing time, and improving the stability and reliability of the roller changing action. Step S4 uses a coordinated control method for sequential roller changing of each color group, avoiding the situation where multiple color groups change rollers simultaneously, causing the previous printing task to start a new round of printing before it is completed, resulting in printing overlap and improving the consistency of printing quality. Step S5 employs a closed-loop control system for detection and fine-tuning, automatically detecting and correcting color misregistration after roller changing, ensuring the stability of printing quality, and reducing the need for manual intervention. It should be added that in step S3, the rotation speed of each component needs to be controlled by a servo motor, especially the rotation speed of the roller changing turntable, so that when the new printing plate roller is attached to the printing mechanism, the unprinted area of ​​the paper just moves to the new printing station, so that there is no waste in the printing process.

[0024] The beneficial effects of this invention are as follows: By incorporating a rotatable roller-changing turntable with two sets of printing plate rollers in each color group, printing plate roller replacement can be completed without stopping the printing press: while the current printing plate roller is in operation, the operator can simultaneously replace the idle printing plate roller. After the replacement is completed, the roller-changing turntable drives the old plate roller to disengage and the new plate roller to attach simultaneously, making the roller replacement process rapid. Rollers are replaced sequentially for each color group, effectively avoiding printing overlap and ensuring the quality of multi-color registration. The detection unit and phase fine-tuning unit form a closed-loop control, which can automatically detect registration deviations after roller replacement and precisely fine-tune them through a worm gear mechanism. The dual-scalpel inking assembly ensures continuous and stable ink supply during roller replacement. Printing continues when the blank area of ​​the substrate before roller replacement reaches the printing area of ​​the printing plate roller after roller replacement, resulting in no blank waste and a low scrap rate. The overall solution completely eliminates the production capacity loss caused by downtime during roller replacement, improves production efficiency, and ensures high consistency of printing quality and a low scrap rate before and after roller replacement.

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 A magnified schematic diagram of the non-stop roller changing device for a flexographic printing press; Figure 3 This is a schematic diagram of the color group structure according to an embodiment of the present invention; Figure 4 This is an embodiment of the present invention. Figure 3 A schematic diagram of the cross-section along the AA direction; Figure 5 This is a schematic diagram of the inking assembly structure according to an embodiment of the present invention; Figure 6 This is a cross-sectional schematic diagram of the inking assembly according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the phase fine-tuning unit structure according to an embodiment of the present invention; Labeling notes: Frame 1, Support plate 11, Connecting beam 12, Foot plate 13, Color group 2, Roll changing assembly 21, Roll changing turntable 211, External gear ring 2111, Drive mechanism 212, Drive gear 2121, Drive servo motor 2122, Anilox roller 213, First servo motor 214, Second servo motor 215, First printing plate roller 216, Second printing plate roller 217, Imprinting mechanism 22, First impression roller 221, Second impression roller 222, Third servo motor 223, Drying mechanism 23, First drying unit 231, Second drying unit 2 32. Cooling guide mechanism 24. First cooling guide roller 241. Second cooling guide roller 242. Fourth servo motor 243. Inking assembly 25. Ink cartridge 251. Ink chamber 2511. Ink outlet 2512. Upper ink doctor blade 252. Lower ink doctor blade 253. Detection unit 3. Phase fine-tuning unit 4. Phase adjustment groove 41. Phase fine-tuning roller 42. Phase adjustment mechanism 43. Phase roller mounting base 431. Rack 4311. Worm gear assembly 432. Worm seat 4321. Worm 4322. Worm wheel 4323. Worm drive motor 433. Detailed Implementation

[0027] like Figure 1-7 As shown, the non-stop roller changing device for a flexographic printing press according to the present invention includes at least the following technical solutions: The system includes a frame 1 and several color groups 2 mounted on the frame 1. The frame 1 includes two opposing support plates 11, with several connecting beams 12 between the two support plates 11. The two ends of each connecting beam 12 are fixedly connected to the two support plates 11 respectively. Each support plate 11 has several foot plates 13 at its bottom, which are perpendicular to the support plate 11 and welded to the bottom of the support plate 11.

[0028] like Figure 1-4As shown, color group 2 includes a roller changing assembly 21 rotatably mounted on frame 1, an impression mechanism 22, and a drying mechanism 23 for drying the printed substrate. The roller changing assembly 21 is equipped with a first printing plate roller 216 and a second printing plate roller 217. The roller changing assembly 21 can selectively drive one set of printing plate rollers to engage with the impression mechanism 22. The roller changing assembly 21 also includes a roller changing turntable 211, a drive mechanism 212 for driving the roller changing turntable 211 to rotate, and an anilox roller 213. The roller changing turntable 211 is rotatably mounted on frame 1, and the anilox roller 213 can rotate coaxially with the roller changing turntable 211. The anilox roller 213, the first printing plate roller 216, and the second printing plate roller 217 are all rotatably mounted on the roller changing turntable 211 via bearings. The drive mechanism 212 is connected to the roller changing turntable 211 for transmission; when the drive mechanism 212 rotates, it drives the roller changing turntable 211 to rotate. A first servo motor 214 and a second servo motor 215 are respectively installed at both ends of the anilox roller 213 and the printing plate roller. The first servo motor 214 is fixedly mounted on the frame 1, and the second servo motor 215 is fixedly mounted on the roller changing turntable 211. The output shafts of both are connected to the anilox roller 213 and the printing plate roller respectively for transmission. Figure 2As shown, a second servo motor 215 is provided at the end of the first printing plate roller 216, and a second servo motor 215 is also provided at the end of the second printing plate roller 217. The drive mechanism 212 includes a drive gear 2121 and a drive servo motor 2122. The drive servo motor 2122 is fixedly mounted on the frame 1. The output shaft of the drive servo motor 2122 is connected to the drive gear 2121 for transmission. An external gear ring 2111 is provided on the roller changing turntable 211. The drive gear 2121 and the external gear ring 2111 are driven by gear meshing. Its working principle is as follows: when the drive servo motor 2122 is working, it drives the drive gear 2121 to rotate. The drive gear 2121 drives the roller changing turntable 211 to rotate around its central axis through meshing with the external gear ring 2111, thereby realizing the switching between different printing plate rollers and the printing mechanism 22. The printing mechanism 22 includes a first printing roller 221, a second printing roller 222, and a third servo motor 223 that drives both to rotate. The first printing roller 221 and the second printing roller 222 are rotatably mounted on the frame 1 via bearings, and the third servo motor 223 is fixedly mounted on the frame 1. The drying mechanism 23 includes a first drying unit 231 corresponding to the first printing roller 221 and a second drying unit 232 corresponding to the second printing roller 222. The first drying unit 231 is fixedly mounted downstream of the first printing roller 221 on the frame 1, and the second drying unit 232 is fixedly mounted downstream of the second printing roller 222 on the frame 1. The first printing plate roller 216 and the second printing plate roller 217 are symmetrically distributed on both sides of the anilox roller 213 on the roller changing turntable 211 and are both in contact with the anilox roller 213. The color group 2 also includes a cooling guide mechanism 24, which includes a first cooling guide roller 241, a second cooling guide roller 242, and a fourth servo motor 243 that drives both to rotate. The first cooling guide roller 241 is installed on the frame 1 downstream of the first drying unit 231, and the second cooling guide roller 242 is installed on the frame 1 downstream of the second drying unit 232. Both the first cooling guide roller 241 and the second cooling guide roller 242 are rotatably installed on the frame 1 by means of bearings. The fourth servo motor 243 is fixedly installed on the frame 1.

[0029] Reference Figure 3-6The roller changing assembly 21 is also equipped with an inking assembly 25 for supplying ink to the printing process. The inking assembly 25 includes an ink cartridge 251, an upper ink doctor blade 252, and a lower ink doctor blade 253. The upper ink doctor blade 252 and the lower ink doctor blade 253 are respectively obliquely and detachably installed at the upper and lower ends of the ink cartridge 251 to scrape off excess ink from the surface of the anilox roller 213. The ink cartridge 251 includes an ink chamber 2511 for storing ink and supplying ink to the anilox roller 213, and an ink outlet 2512 for ink to flow out. The ink chamber 2511 has an overall shape that is larger at the top and smaller at the bottom. The blades of the upper ink doctor blade 252 and the lower ink doctor blade 253 face the opening direction of the ink outlet 2512. Its working principle is as follows: the ink is stored in the ink chamber 2511 and flows to the surface of the anilox roller 213 through the ink outlet 2512. When the anilox roller 213 rotates, it drives the ink to transfer. The upper ink doctor blade 252 and the lower ink doctor blade 253 scrape off the excess ink on the surface of the anilox roller 213, so that a uniform ink layer is formed on the surface of the anilox roller 213.

[0030] Reference Figure 1 , Figure 2 , Figure 7 The frame 1 is also equipped with a detection unit 3 and a phase fine-tuning unit 4. The detection unit 3 is located downstream of the last color group 2 and is used to detect the printing pattern effect. The phase fine-tuning unit 4 is used to fine-tune the printing color registration accuracy. The phase fine-tuning unit 4 is mounted on the frame 1 and includes a phase adjustment groove 41, a phase fine-tuning roller 42 disposed in the phase adjustment groove 41, and a phase adjustment mechanism 43 that drives the phase fine-tuning roller 42 to move in the phase adjustment groove 41. The phase adjustment mechanism 43 includes a phase roller mounting seat 431 slidably mounted in the phase adjustment groove 41, a worm gear assembly 432 fixedly mounted on the frame 1, and a worm drive motor 433 fixedly mounted on the frame 1. The worm gear assembly 432 includes a worm seat 4321 fixedly mounted on the frame 1, a worm 4322 rotatably mounted on the worm seat 4321, and a worm wheel 4323 rotatably mounted on the frame 1 and cooperating with the worm 4322. The phase roller mounting seat 431 is provided with a rack 4311 on the side facing the worm wheel 4323. The rack 4311 matches the tooth profile of the worm wheel 4323. The output shaft of the worm drive motor 433 is connected to the worm 4322 for transmission. When the worm drive motor 433 is working, it can drive the phase roller mounting seat 431 to move in the phase adjustment groove 41. Its working principle is as follows: the worm drive motor 433 drives the worm 4322 to rotate, the worm 4322 drives the worm wheel 4323 to rotate, and the worm wheel 4323 drives the phase roller mounting seat 431 and the phase fine-tuning roller 42 to move in the phase adjustment groove 41 through meshing with the rack 4311, thereby adjusting the tension of the substrate and realizing the fine adjustment of the color registration accuracy.

[0031] The working principle of this embodiment is as follows: During the printing process, the first printing plate roller 216 is in contact with the first impression roller 221, and the substrate passes between them to complete the printing. After printing, the substrate is dried by the first drying unit 231, then cooled and guided by the first cooling guide roller 241, and then passes around the second impression roller 222 and the second cooling guide roller 242 in sequence before entering the next color group. When a printing plate needs to be changed, the second printing plate roller 217 is removed and a new printing plate is installed in advance while the first printing plate roller 216 is working. Then, the second printing plate roller 217 is reinstalled. After the second printing plate roller 217 is fully inked by the anilox roller, the servo motor 2122 is driven to work, which drives the roller changing turntable 211 to rotate, so that the first printing plate roller 216 is disengaged from the first impression roller 221. At the same time, the second printing plate roller 217 is attached to the second impression roller 222, and the printing work continues to be performed by the second printing plate roller 217. This achieves non-stop roller changing for single color groups. Then, each subsequent color group 2 is changed in sequence according to the printing order to avoid printing overlap caused by simultaneous roller changing for multiple color groups. After the roller change is completed, the detection unit 3 takes a picture of the printed pattern and compares it with the standard pattern. If a color registration deviation is found, the worm drive motor 433 is started to drive the worm 4322 to rotate on the worm seat 4321. The worm 4322 then drives the worm wheel 432 to rotate. The worm wheel 432 meshes with the rack 4311 to drive the phase roller mounting seat 431 to slide up and down in the phase adjustment groove 41, so that the position of the phase fine-tuning roller 42 is finely adjusted up and down. The color registration of the substrate wrapped on the phase fine-tuning roller 42 is finely adjusted until the color registration accuracy meets the requirements. The fine-tuning principle is as follows: when the substrate is registered too early in color group 2, the phase fine-tuning roller 42 moves slightly upward, so that the tension of the substrate is slightly reduced. At this time, the tension of the substrate in color group 2 is lower than that of the substrate that has not entered color group 2. The travel speed of the substrate is slightly reduced due to the external tension of color group 2, and the color registration position of the substrate is gradually corrected until the internal and external tensions are consistent when the color registration is accurate. Conversely, if the registration of the substrate in color group 2 is too lagging, the phase adjustment roller 42 will move downward slightly, causing the tension of the substrate to increase slightly. At this time, the tension of the substrate in color group 2 is higher than that of the substrate that has not entered color group 2. The travel speed of the substrate is slightly increased due to the tension in color group 2, correcting the registration position until the registration is accurate and the tension inside and outside are consistent.

[0032] The above embodiments are merely one preferred embodiment of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included within the protection scope of the present invention.

Claims

1. A soft printing machine non-stop roll changing device, comprising a frame, a plurality of color groups arranged along the direction of the substrate travel arranged on the frame, characterized in that: The color set includes a roller changing assembly rotatably mounted on a frame, an impression mechanism, and a drying mechanism for drying the printed substrate. The roller changing assembly is detachably equipped with a first printing plate roller and a second printing plate roller. The impression mechanism is correspondingly equipped with a first impression roller and a second impression roller. The roller changing assembly can selectively drive the first printing plate roller to engage with the first impression roller, or drive the second printing plate roller to engage with the second impression roller. The roller changing assembly also includes a roller changing turntable, a drive mechanism for driving the roller changing turntable to rotate, and an anilox roller. The roller changing turntable is rotatably mounted on the frame, and the anilox roller and the roller changing turntable can rotate coaxially. Both the anilox roller and the printing plate roller are rotatably mounted on the roller changing turntable via bearings. The drive mechanism is connected to the roller changing turntable via a transmission connection, and when the drive mechanism rotates, it drives the roller changing turntable to rotate. A first servo motor is provided at the end of the anilox roller, and second servo motors are respectively provided at the ends of the first and second printing plate rollers. The first servo motor is fixed... The machine is fixedly mounted on the frame, with its output shaft connected to the anilox roller drive. Two second servo motors are fixedly mounted on the roller changing turntable, with their output shafts respectively connected to the first and second printing plate rollers. The first and second printing plate rollers are symmetrically distributed on both sides of the anilox roller on the roller changing turntable, and both are in contact with the anilox roller. The frame is also equipped with several detection units and a phase fine-tuning unit. The detection units are located downstream of the last color group and are used to detect the printing pattern effect. The phase fine-tuning unit is used to fine-tune the printing color registration accuracy. The roller changing assembly is also equipped with an inking assembly for supplying ink to the printing work. The inking assembly includes an ink box, an upper ink doctor blade, and a lower ink doctor blade. The upper and lower ink doctor blades are respectively obliquely and detachably mounted on the upper and lower ends of the ink box and are used to scrape off excess ink from the surface of the anilox roller. The ink box includes an ink cavity for storing ink and supplying ink to the anilox roller, and an ink outlet for ink to flow out. The ink cavity is generally shaped with a larger top and a smaller bottom. The blades of the upper and lower ink doctor blades face the opening direction of the ink outlet.

2. The flexographic printing press on-the-fly roller changing apparatus of claim 1, wherein: The driving mechanism includes a driving gear and a driving servo motor. The driving servo motor is fixedly mounted on the frame. The output shaft of the driving servo motor is connected to the driving gear. An external gear ring is provided on the roller changing turntable. The driving gear and the external gear ring are driven by gear meshing.

3. The flexographic printing press on-the-fly roller changing apparatus of claim 1, wherein: The first and second impression rollers are rotatably mounted on the frame via bearings. The impression mechanism is also equipped with a third servo motor that drives the first and second impression rollers to rotate. The third servo motor is fixedly mounted on the frame. The drying mechanism includes a first drying unit corresponding to the first impression roller and a second drying unit corresponding to the second impression roller. The first drying unit is fixedly mounted downstream of the first impression roller on the frame, and the second drying unit is fixedly mounted downstream of the second impression roller on the frame.

4. The flexographic printing press on-the-fly roller changing apparatus of claim 3, wherein: The color group also includes a cooling guide mechanism, which includes a first cooling guide roller, a second cooling guide roller, and a fourth servo motor that drives both to rotate. The first cooling guide roller is installed downstream of the first drying unit on the frame, and the second cooling guide roller is installed downstream of the second drying unit on the frame. Both the first and second cooling guide rollers are rotatably mounted on the frame by bearings. The fourth servo motor is fixedly mounted on the frame.

5. The flexographic printing press on-the-fly roller changing apparatus of claim 1, wherein: The phase fine-tuning unit is mounted on a frame and includes a phase adjustment groove, a phase fine-tuning roller disposed in the phase adjustment groove, and a phase adjustment mechanism for driving the phase fine-tuning roller to move in the phase adjustment groove. The phase adjustment mechanism includes a phase roller mounting seat slidably mounted in the phase adjustment groove, a worm gear assembly fixedly mounted on the frame, and a worm drive motor fixedly mounted on the frame. The worm gear assembly includes a worm seat fixedly mounted on the frame, a worm rotatably mounted on the worm seat, and a worm wheel rotatably mounted on the frame and cooperating with the worm. The phase roller mounting seat has a rack facing the worm wheel, and the rack matches the tooth profile of the worm wheel. The output shaft of the worm drive motor is connected to the worm drive, and the worm drive motor can drive the phase roller mounting seat to move in the phase adjustment groove when it is working.

6. The flexographic printing press on-the-fly roller changing apparatus of claim 1, wherein: The frame includes two opposing support plates, with several connecting beams between the two support plates. Each connecting beam is fixedly connected to the two support plates at both ends. Each support plate has several foot plates at its bottom, which are perpendicular to the support plates and welded to the bottom of the support plates.

7. A method of changing a printing roll based on the roll changing device of any one of claims 1 to 6, characterized in that: Includes the following steps: S1: When the current printing plate roller is printing, the idle printing plate rollers on each color group's roller changing assembly are changed. S2: After all idle printing plate rollers have changed plates, wait for the new printing plate to be fully inked. S3: The roller changing assembly disengages the currently working printing plate roller from its corresponding impression mechanism, and simultaneously rotates the changed printing plate roller to its corresponding impression mechanism position. S4: Each color group performs the roller changing operation in sequence (S3). S5: A still photograph of the printed image after roller changing is taken by the detection unit to check the color registration effect. If the color registration is not accurate, fine-tuning is performed by the phase fine-tuning unit.

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