A high-speed, wide-format, full-color water-based inkjet printing mechanism for a roll substrate

Abstract

The present invention belongs to the technical field of printing equipment, and specifically relates to a high-speed, wide-format, full-color, water-based inkjet printing mechanism for a roll-to-roll substrate, comprising a frame on which a print roller and a pressure roller are rotatably mounted, a print assembly being provided on the frame above the print roller, and a drying device being provided on the frame. The high-speed, wide-format, full-color, water-based inkjet printing mechanism for a roll-to-roll substrate provided in this embodiment utilizes a print roller to convey the substrate, thereby improving stability. The substrate width can exceed 1 meter, and the substrate conveying speed is fast, exceeding 100 meters per minute. A cooling structure is provided within the print roller, which, in conjunction with the drying device, maintains a constant temperature on the surface of the print roller and on the substrate, stabilizes the elongation of the substrate, and achieves non-deviation registration of four or more colors based on water-based inks.

Description

Technical Field

[0001] The invention belongs to the technical field of printing equipment, and in particular relates to a high-speed, wide-format, full-color water-based inkjet printing mechanism for a roll substrate. Background Art

[0002] There are many printing methods in the printing and packaging industry, including flexographic printing, gravure printing, offset printing, digital printing, etc. Among them, digital printing is an emerging printing method in recent years. It has the characteristics of high efficiency, low cost for small batches, and simple operation, and has therefore become a development trend in recent years.

[0003] Currently, in high-speed inkjet digital printing technology, UV and water-based ink materials are commonly used. However, due to the strong pollution of UV ink and the good environmental protection of water-based ink, water-based ink is recognized by more and more people.

[0004] In the watermark inkjet printing industry, substrate traction and conveying are usually carried out horizontally, usually using a belt structure. This method is feasible for black and white printing, but for color equipment, due to the longer path, the substrate is prone to swinging during the conveying process, and it is difficult to achieve the registration of the four colors (CMYK). Especially for wide-format equipment moving at high speeds, the stability of the substrate movement directly affects the printing effect. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-speed, wide-format, full-color water-based inkjet printing mechanism for a roll substrate, which adopts a roller-type substrate conveying method. The substrate is wrapped on the roller, and the rotation of the roller drives the substrate to move, thereby achieving stability in substrate conveying under the water-based inkjet printing state and ensuring color printing quality.

[0006] In order to achieve the above technical objectives, the technical solution of the present invention is:

[0007] A high-speed, wide-format, full-color water-based inkjet printing mechanism for a roll substrate comprises a frame on which a printing roller is rotatably mounted, a printing assembly is provided on the frame above the printing roller, and a drying device is provided on the frame.

[0008] As an improvement, the printing roller is provided with a cooling structure.

[0009] As an improvement, the printing roller includes a cylinder, the cooling structure includes a cooling channel arranged on the cylinder, the extension direction of the cooling channel is parallel to the axial direction of the cylinder, the cooling channel includes a plurality of groups of spaced-apart medium inlet cooling channels and return medium cooling channels, each group of adjacent medium inlet cooling channels and return medium cooling channels are connected, end covers are provided at both ends of the cylinder, the end covers are provided with inlet and return medium structures, a central shaft is fixedly passed through the centers of the two end covers, the central shaft is provided with inlet and outlet medium channels, the inlet and return medium structures connect the inlet and outlet medium channels and the cooling channel, and the central shaft is provided with an end of the inlet and outlet medium channels connected to a rotary joint.

[0010] As a further improvement, the medium inlet and return structure includes a medium inlet slot and a medium return slot provided on one end cover, one side of the end cover provided with the medium inlet slot and the medium return slot is connected to a pressure plate, and the other end cover is provided with a reversing slot, the medium inlet slot is connected to the medium inlet cooling channel, the medium return slot is connected to the medium return cooling channel, and the reversing slot is connected to a group of the medium inlet cooling channel and the medium return cooling channel;

[0011] The inlet and outlet medium channels include a coaxially arranged inlet medium channel and an outlet medium channel. The inlet medium channel is connected to the inlet medium tank, and the outlet medium channel is connected to the return medium tank via a return medium pipe.

[0012] As a further improvement, the drying device includes a first oven and a second oven, the second oven is arranged close to the printing substrate, the first oven includes a shell, a cavity is provided in the shell, an air inlet and an air outlet are provided on the shell, the edge of the shell on one side close to the printing roller is arc-shaped, and the shell on the side close to the printing roller is provided with an air guide structure.

[0013] As a further improvement, a partition is provided in the cavity of the shell, and the partition divides the cavity into a positive pressure cavity and a negative pressure cavity. The air inlet is connected to the positive pressure cavity, and the air outlet is connected to the negative pressure cavity.

[0014] As a further improvement, the air guide structure includes a plurality of air guide strips arranged on the arc-shaped edge of the shell, the air guide strips are long strips with a V-shaped cross-section, the V-shaped tip of the long strip is arranged away from the printing roller, and an air outlet gap is formed between adjacent air guide strips.

[0015] As a further improvement, a slide rail is provided on the frame, a slideway is provided on the shell, the slide rail and the slideway cooperate with each other, and a cylinder is provided between the frame and the shell.

[0016] As a further improvement, the printing assembly includes a printing bracket, which is vertically slidably mounted on the frame through a vertical screw module, and the printing bracket is provided with printing heads arranged in rows in an arc shape, and a moisturizing bracket is provided on the frame below the printing heads, and the moisturizing bracket is mounted on the frame through a horizontal screw module, and the moisturizing bracket is provided with several moisturizing sealing frames corresponding to the positions of the printing heads, and an ink scraper rod is slidably mounted on the moisturizing bracket, and a scraper blade is provided on the ink scraper rod, and the position of the scraper blade corresponds to the position of the printing heads arranged in rows.

[0017] As a further improvement, the printing bracket is provided with a print head mounting bar, the print heads are mounted on the print head mounting bar, each row of the print heads is mounted on two parallel print head mounting bars, and the positions of the print heads on the two print head mounting bars correspond to each other.

[0018] As a further improvement, the print head is provided with an ink inlet and an ink outlet, the ink inlet is connected to the main ink cartridge, the ink outlet is connected to the return ink cartridge, and the main ink cartridge and the return ink cartridge are respectively connected to a negative pressure device.

[0019] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0020] The present invention provides a high-speed, wide-format, full-color water-based inkjet printing mechanism for a roll substrate. The substrate is conveyed by wrapping the substrate on a printing roller and pressing the substrate against the printing roller through a pressure roller. The substrate and the printing roller rotate together. During the substrate conveying process, there is no left-right swinging or up-and-down jumping of the substrate, so as to achieve stability in the substrate conveying process, which is beneficial to improving the printing effect. During printing, the printing component performs inkjet printing on the substrate wound on the printing roller. When the printed substrate is rotated to the drying device along with the printing roller, the printed substrate is dried to dry the printed ink on the substrate.

[0021] The drying device includes a first oven and a second oven. The first oven is provided with a drying device near the printing roller, and the second oven is provided near the printed substrate to dry the printed substrate to dry the ink thereon. Specifically, the first oven and the second oven can be used separately or in combination. The first oven can be slid to adjust its position, which is convenient to use. Hot air enters the air inlet of the drying device, blows the hot air onto the printed substrate, and then is discharged through the air outlet to dry the printed substrate to dry the ink thereon.

[0022] Since drying and equipment operation will increase the temperature of the printing roller and the printing substrate thereon, the temperature increase will cause the elongation of the printing substrate to change, affecting the printing quality. Therefore, a cooling structure is set on the printing roller to cool the printing roller. In conjunction with the drying device, the temperature of the printing roller and the printing substrate thereon is maintained at a constant level, so that the elongation of the printing substrate and other indicators are stable, thereby ensuring printing accuracy.

[0023] The printing assembly can realize the up and down position adjustment of the print nozzle. When printing, the print nozzle position is adjusted downward to make it close to the printing substrate. The print nozzle is arranged in an arc shape, corresponding to the shape of the substrate on the print roller. After printing is completed, the print nozzle position is adjusted upward, and the moisturizing bracket is moved to the position corresponding to the print nozzle through the horizontal screw module. The movement of the scraper on the ink scraper rod is controlled to scrape off the residual ink on the print nozzle, and then the print nozzle is moved downward so that the print nozzle is tightly combined with the moisturizing sealing frame. The print nozzle is in the sealed space inside the moisturizing sealing frame, and the print nozzle will not dry out, which is conducive to subsequent printing.

[0024] Each row of print heads is installed side by side on two print head mounting strips, and a double print head splicing method is adopted. When one print head is blocked or damaged, the other print head installed in parallel can be used for printing. In actual use, the probability of two print heads installed in parallel being damaged at the same time is extremely low, which improves the stability of printing and facilitates the timely disassembly and repair of the faulty print head.

[0025] The ink inlet of the print head is connected to the main ink cartridge, and the ink outlet is connected to the return ink cartridge. The main ink cartridge and the return ink cartridge are respectively connected to the negative pressure device. The double negative pressure method is adopted to control the pressure difference to make the ink circulate normally. At the same time, it also ensures that the ink in the print head does not drip, and ensures that the bubbles and impurities generated during the printing process are taken away in time, ensuring the ink supply and ink stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a diagram of the actual use state of an embodiment of the present invention;

[0027] Figure 2 It is a structural diagram of an embodiment of the present invention;

[0028] Figure 3 It is a schematic diagram of the structure of the printing roller;

[0029] Figure 4 It is a schematic diagram of the end face structure of the inlet and outlet media end cover;

[0030] Figure 5 This is a schematic diagram of the cross-sectional structure of the inlet and outlet media end cover.

[0031] Figure 6 It is a structural diagram of the reversing end cover;

[0032] Figure 7 It is a structural diagram of the commutation slot;

[0033] Figure 8 It is a structural diagram of the medium inlet and outlet ends of the cylinder;

[0034] Figure 9 It is a structural diagram of the reversing end of the cylinder;

[0035] Figure 10 It is a structural diagram of a drying device;

[0036] Figure 11 This is a schematic diagram of the coordination structure between the drying device and the printing roller;

[0037] Figure 12 It is a schematic diagram of the structure of the printing component;

[0038] Figure 13 This is a schematic diagram of the layout of the print head;

[0039] Figure 14 It is a structural diagram of the ink supply system of the print head;

[0040] In the accompanying drawings, 1-frame, 2-printing roller, 215-cylinder, 21-inlet medium cooling channel, 22-return medium cooling channel, 23-center axis, 24-inlet and return medium end cover, 25-reversing end cover, 26-inlet medium slot, 27-return medium slot, 28-pressing plate, 29-reversing slot, 210-inlet medium channel, 211-outlet medium channel, 212-rotating joint, 213-reinforcement sleeve, 214-reinforcement rib, 216-return medium pipe, 3-pressing roller, 4-printing assembly, 41-printing bracket, 42-vertical screw module, 43-printing nozzle, 44-moisturizing bracket, 45-horizontal screw module , 46- moisturizing sealing frame, 47- ink scraping rod, 48- scraping blade, 49- print head mounting strip, 410- main ink cartridge, 411- reflux ink cartridge, 412- main ink barrel, 413- main negative pressure bottle, 414- negative pressure pump, 415- positive pressure pump, 416- reflux pump, 417- reflux negative pressure bottle, 418- control panel, 5- drying device, 51- first oven, 52- air inlet, 53- air outlet, 54- partition, 55- positive pressure chamber, 56- negative pressure chamber, 57- air guide strip, 58- slide rail, 59- slide way, 510- cylinder, 511- second oven, 6- front traction mechanism, 7- rear traction mechanism. DETAILED DESCRIPTION

[0041] The present invention is further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only and are schematic, not actual, representations. They should not be construed as limiting this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted from the drawings.

[0042] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0043] like Figures 1 to 14 As shown together, a high-speed, wide-format, full-color water-based inkjet printing mechanism for a roll substrate includes a frame 1, on which a printing roller 2 is rotatably mounted. During specific use, the printing roller cooperates with a pressure roller 3 to press the printed substrate tightly against the printing roller to improve the use effect. A printing assembly 4 is provided on the frame 1 above the printing roller 2, and a drying device 5 is provided on the frame 1. The printing roller is provided with a cooling structure. During actual use, a front traction mechanism 6 is provided in front of the printing roller 2, and a rear traction mechanism 7 is provided behind the printing roller to provide traction power to the substrate respectively. Specifically, the front traction mechanism and the rear traction mechanism include a pressure roller and an active roller driven by a motor. At the same time, the printing roller is also provided with a power mechanism, such as a motor connected to the motor. During operation, the active rollers of the front and rear traction mechanisms and the printing roller are synchronized. The power setting of the printing roller can reduce the traction force required for the movement of the substrate, reduce the traction force on the substrate, reduce the elongation of the substrate, and avoid over-stretching the substrate or even tearing the substrate.

[0044] During use, the substrate is wrapped around the printing roller 2 for substrate transport. The substrate is pressed against the printing roller by the pressure roller 3. The substrate and the printing roller rotate together. During the substrate transport process, there is no left and right swing or up and down jumping of the substrate, so as to achieve stability of the substrate transport process, which is conducive to improving the printing effect. It is particularly suitable for wide-format printing. The substrate width exceeds 1 meter and the substrate transport speed can reach more than 100 meters per minute, still ensuring stable substrate transport. The substrate transport stability is high, and the printing accuracy and quality are guaranteed. It can realize full-color inkjet printing with water-based ink and achieve non-deflection registration of four colors or multiple colors, which is simply not guaranteed by traditional substrate transport methods.

[0045] In actual use, in order to ensure good tension control of the substrate during the substrate transportation process, a tension controller is added to the forward substrate and the rear substrate receiving part of the printing roller to adjust the substrate tension.

[0046] In this embodiment, the specific structure of the cooling structure of the printing roller is as follows: the printing roller 2 includes a cylinder 215, which is provided with a cooling channel. The extension direction of the cooling channel is parallel to the axial direction of the cylinder. The cooling channel includes a plurality of groups of spaced-apart medium cooling channels 21 and return medium cooling channels 22. Each group of adjacent medium cooling channels and return medium cooling channels is connected. End covers are provided at both ends of the cylinder, and the end covers are provided with a medium inlet and return structure. A central shaft 23 is fixedly passed through the center of the two end covers, and the central shaft is provided with an inlet and outlet medium channel. The inlet and return medium structure connects the inlet and outlet medium channels and the cooling channel.

[0047] Specifically, one end cover is a medium inlet and return end cover 24, and the other end cover is a reversing end cover 25. The medium inlet and return structure includes a medium inlet slot 26 and a medium return slot 27 provided on the medium inlet and return end cover. The medium inlet and return end cover 24 is provided with a pressure plate 28 connected to one side of the medium inlet slot and the medium return slot. The reversing end cover is provided with a reversing slot 29. The medium inlet slot is connected to the medium inlet cooling channel, the medium return slot is connected to the medium return cooling channel, and the reversing slot is connected to a group of medium inlet cooling channels and medium return cooling channels.

[0048] The inlet and outlet media channels include a coaxially arranged inlet media channel 210 and an outlet media channel 211. The inlet media channel is connected to the inlet media tank, and the outlet media channel is connected to the return media tank through a return media pipe 216. Specifically, a blind hole is provided at one end of the central axis, and a sleeve is installed in the blind hole. The inlet media channel is between the sleeve and the central axis, and the outlet media channel is inside the sleeve.

[0049] Specifically, the medium inlet groove extends along the radial direction of the end cover, and the medium inlet groove extends near the circumferential surface of the end cover and turns to extend parallel to the axial direction of the end cover. There are multiple medium inlet grooves, and they are evenly distributed along the circumference of the end cover. The return medium groove is located on the circumferential surface of the end cover and extends along the circumference of the end cover. The groove wall of the return medium groove is lower than the groove wall of the medium inlet groove. Correspondingly, the medium inlet end of the medium inlet cooling channel is also longer than the medium outlet end of the return medium cooling channel, so that when the medium inlet and outlet end cover is connected to the cylinder, the medium inlet groove is connected to the medium inlet cooling channel, and the return medium groove is connected to the medium outlet cooling channel. A through hole connecting the medium inlet groove and the medium inlet channel is provided on the central axis, and a chamfered structure is provided at the bottom of the groove at one end of the medium inlet groove connecting the through hole. The positions of the through hole and the chamfered structure correspond to each other, which is beneficial for the cooling medium to first fill the chamfered structure position of the medium inlet groove close to the central axis when the medium is introduced.

[0050] When this embodiment is used, the central shaft is connected to the rotary joint 212, and the cooling medium flows into the medium inlet groove of the return medium end cover through the medium inlet channel of the central shaft, and then flows into the medium inlet cooling channel of the cylinder, is reversed through the reversing groove of the line change end cover, flows into the return medium cooling channel of the cylinder, then flows into the return medium groove, and finally flows into the medium outlet channel of the central shaft and flows out.

[0051] In this embodiment, in order to ensure the structural strength of the printing roller, reinforcing ribs are provided between the central shaft and the end cover. The reinforcing ribs include a reinforcing sleeve 213 fixedly mounted on the central shaft, and reinforcing ribs 214 are connected around the reinforcing sleeve. The reinforcing ribs are radially radiated with the reinforcing sleeve as the center.

[0052] In the assembly process, the center shaft and the end cover are connected by interference fit and shrinkage to avoid damage to the center shaft caused by welding, which may cause stress deformation. The end cover and the cylinder are connected by external welding, and the end cover and the pressure plate are also connected by external welding to ensure sufficient connection strength. This has little effect on the strength of the end cover, pressure plate and cylinder, and the welds will not come into contact with the cooling medium.

[0053] In this embodiment, the cylinder is a seamless steel tube with no inner or outer jackets. The inlet and return cooling channels are long straight holes provided on the cylinder tube wall, evenly distributed along the circumference of the cylinder. Two adjacent long straight holes form a group, one for the inlet and one for the return. The cooling medium flows in from the inlet end of the cylinder, is reversed through the reversing end cover, and then flows back, avoiding a large temperature difference when flowing in from one side and out from the other. Moreover, the cooling channels of this embodiment are straight holes. Compared with the jacketed rollers commonly used in existing industry, the process and cycle are shortened, which greatly speeds up the cycle speed and makes the temperature control response faster and more accurate. In addition, the long hole method is used instead of the original jacket welding method, which is simple in structure and not easy to rust.

[0054] In this embodiment, a drying device 5 is provided on the frame near the lower part of the printing roller to dry the printed substrate. The drying device includes a first oven 51 and a second oven 511. The second oven is provided near the printed substrate. The first oven includes a shell with a cavity provided therein. The shell is provided with an air inlet 52 and an air outlet 53. The edge of the shell on one side close to the printing roller is arc-shaped, corresponding to the shape of the printing roller. The shell is provided with an air guide structure on the side close to the printing roller.

[0055] Specifically, a partition 54 is provided in the cavity of the shell, and the partition is connected to the air guide structure. The partition divides the cavity into two parts. When in use, the air inlet and the air outlet are connected through a fan. The part of the cavity connected to the air inlet is a positive pressure cavity 55, and the part connected to the air outlet is a negative pressure cavity 56. In actual use, hot air enters the positive pressure cavity from the air inlet and is blown toward the substrate through the air guide structure. Under the action of pressure difference, it enters the negative pressure cavity and flows out from the air outlet. It is recycled through the fan, saving energy. The pressure difference acts on the island wind, so that the hot air flows along the surface of the substrate, which is different from the traditional direct blowing method of drying, and improves the drying efficiency.

[0056] In this embodiment, the structure of the second oven is not specifically limited, and the existing oven structure on the market can be used. The first oven and the second oven can be used separately or in combination, and can be determined according to factors such as the use environment, the drying ability of the ink and the printing speed.

[0057] In this embodiment, the air guide structure includes a plurality of air guide strips 57 arranged on the arc-shaped edge of the shell. The air guide strips are long strips with a V-shaped cross-section. The V-shaped tip of the long strip is arranged away from the printing roller. An air outlet gap is formed between adjacent air guide strips, so that the hot air is blown evenly and vertically toward the substrate. The air guide strips also play a role in strengthening the strength of the shell structure.

[0058] In this embodiment, a slide rail 58 is provided on the frame, and a slideway 59 is provided on the shell. The slide rail and the slideway cooperate with each other, and a cylinder 510 is provided between the frame and the shell, which is convenient for adjusting the distance between the shell and the substrate on the printing roller, ensuring the drying effect while avoiding excessive drying due to being too close to the substrate, and facilitating the maintenance of the substrate and the printing roller. When in working state, the shell is adjusted to be close to the printing roller, and when in non-working state, the shell is kept away from the printing roller.

[0059] In actual use, the direction of hot air flowing from the positive pressure chamber to the negative pressure chamber is opposite to the rotation direction of the printing roller, which increases the relative speed between the hot air and the substrate and improves the drying effect.

[0060] In this embodiment, the printing assembly 4 includes a printing bracket 41, which is vertically slidably mounted on the frame 1 through a vertical screw module 42. The printing bracket is provided with printing nozzles 43 arranged in an arc shape in rows, corresponding to the shape of the substrate on the printing roller. A moisturizing bracket 44 is provided on the frame below the printing nozzles. The moisturizing bracket is installed on the frame through a horizontal screw module 45. The moisturizing bracket is provided with a number of moisturizing sealing frames 46 corresponding to the positions of the printing nozzles. The top of the moisturizing sealing frame is open, and the other surfaces are closed. A scraper rod 47 is slidably provided on the moisturizing bracket. Specifically, a belt and a motor can be set on the moisturizing bracket, and the scraper rod is installed on the belt. The motor drives the belt to move, and the belt drives the scraper rod to move. There is a scraper 48, the position of the scraper corresponds to the position of the print nozzles arranged in a row, and the bottom of the moisturizing bracket is closed to form an ink storage pool, which can store the scraped ink. When printing, the position of the print nozzle is adjusted downward by the vertical screw module to make it close to the printing substrate for printing. After printing is completed, the position of the print nozzle is adjusted upward, and the moisturizing bracket is moved to the position corresponding to the print nozzle through the horizontal screw module. The position of the print nozzle is adjusted, and the movement of the scraper rod is controlled to drive the scraper to move and scrape off the residual ink and dirt on the print nozzle. Then the scraper rod returns to its position and the print nozzle is moved downward so that the print nozzle is tightly combined with the moisturizing sealing frame. The print nozzle is in the sealed space inside the moisturizing sealing frame, and the print nozzle will not dry out, which is conducive to subsequent printing.

[0061] In this embodiment, a print head mounting bar 49 is provided on the printing bracket, and the print heads are mounted on the print head mounting bar. Each row of print heads is mounted on two parallel print head mounting bars. The positions of the print heads on the two print head mounting bars correspond to each other. The print heads are double-spliced so that when one print head is blocked or damaged, the other parallel print head can be used for printing. In actual use, the probability of two parallel print heads being damaged at the same time is extremely low, which greatly improves the stability of printing and facilitates the timely disassembly and repair of the faulty print head.

[0062] In this embodiment, the printing assembly adopts a double negative pressure circulation ink supply, and the specific structure is as follows: Figure 14As shown, the print head is provided with a nozzle, an ink inlet and an ink outlet, the ink inlet is connected to the main ink cartridge 410 through an ink inlet tube, a filter is provided on the ink inlet tube, the ink outlet is connected to the reflux ink cartridge 411 through an ink return tube, the main ink cartridge and the reflux ink cartridge are respectively connected to a negative pressure device, specifically, the ink inlet of the main ink cartridge is connected to the main ink barrel 412 through a connecting pipe, the connecting pipe is provided with an ink supply pump, a filter and a degassing device, the air vent of the main ink cartridge is connected to an inlet of a three-way valve, an outlet of the three-way valve is connected to a main negative pressure bottle 413, the main negative pressure bottle is connected to a negative pressure pump 414 through a valve, and the other outlet of the three-way valve is connected to a positive pressure pump 415; the ink outlet of the reflux ink cartridge 411 is connected to a reflux pump 416, the reflux pump is connected to the main ink barrel 412, and the air vent of the reflux ink cartridge is connected to the reflux The negative pressure bottle 417 and the reflux negative pressure bottle are connected to the negative pressure pump 414 through a valve, and the state of the pump and the valve is controlled by the control board 418 to control the air pressure of the negative pressure system. The main negative pressure bottle generates negative pressure for the main ink cartridge, and the reflux negative pressure bottle generates negative pressure for the reflux ink cartridge. The main ink cartridge adopts a low negative pressure, and the reflux ink cartridge adopts a high negative pressure to generate a negative pressure difference to ensure that the ink returns from the main ink cartridge through the print nozzle to the reflux ink cartridge, and the ink in the reflux ink cartridge returns to the main ink barrel, and the main ink barrel returns to the main ink cartridge through the ink supply pump. The double negative pressure method is adopted to control the pressure difference to make the ink circulate normally, while also ensuring that the ink in the print nozzle does not drip, and that the bubbles and impurities generated during the printing process are taken away in time, thereby ensuring the stability of the ink supply and ink.

[0063] In specific use of this embodiment, the printing substrate is wound around the print roller and transported. When printing is required, the printing assembly descends to a suitable position for printing. The printed substrate rotates with the print roller to the drying device position. The drying device sprays hot air to dry the printing substrate, so that the ink on the substrate is dry and can enter the subsequent process. During the substrate transportation and drying process, the print roller and the substrate will heat up. In this embodiment, a cooling structure is set in the print roller to cool the print roller and the substrate, so that the working temperature of the print roller and the substrate is constant, thereby preventing temperature changes from affecting the expansion and contraction rate of the substrate and affecting the printing quality.

[0064] The high-speed, wide-format, full-color water-based inkjet printing mechanism for a roll substrate provided in this embodiment adopts a printing roller to transport the substrate, thereby improving the stability of substrate transportation. The substrate width can exceed 1 meter, and the substrate transportation speed is fast, exceeding 100 meters per minute. A cooling structure is provided inside the printing roller, which is used in conjunction with a drying device to maintain a constant temperature on the surface of the printing roller and the substrate, and a stable elongation of the substrate, thereby achieving non-deviation registration of four or more colors based on water-based ink.

[0065] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A high-speed, wide-format, full-color water-based inkjet printing mechanism for a roll substrate, characterized in that: The machine comprises a frame, a printing roller is rotatably mounted on the frame, a printing assembly is provided on the frame above the printing roller, a drying device is provided on the frame, and a cooling structure is provided on the printing roller; The printing roller includes a cylinder, the cooling structure includes a cooling channel provided on the cylinder, the extension direction of the cooling channel is parallel to the axial direction of the cylinder, the cooling channel includes a plurality of groups of medium inlet cooling channels and medium return cooling channels arranged at intervals, each group of adjacent medium inlet cooling channels and medium return cooling channels are connected, end covers are provided at both ends of the cylinder, the end covers are provided with a medium inlet and return structure, a central shaft is fixedly passed through the centers of the two end covers, the central shaft is provided with a medium inlet and outlet channel, the medium inlet and return structure connects the medium inlet and outlet channel and the cooling channel, and one end of the central shaft provided with the medium inlet and outlet channel is connected to a rotary joint; The drying device includes a first oven and a second oven, the second oven being arranged near the printing substrate, the first oven including a housing, a cavity being arranged in the housing, an air inlet and an air outlet being arranged on the housing, an edge of the housing on one side close to the printing roller being arc-shaped, and an air guide structure being arranged on the side of the housing close to the printing roller; The medium inlet and return structure includes a medium inlet slot and a medium return slot provided on one end cover, one side of the end cover provided with the medium inlet slot and the medium return slot is connected to a pressure plate, and the other end cover is provided with a reversing slot, the medium inlet slot is connected to the medium inlet cooling channel, the medium return slot is connected to the medium return cooling channel, and the reversing slot is connected to a group of the medium inlet cooling channel and the medium return cooling channel; The inlet and outlet medium channels include a coaxially arranged inlet medium channel and an outlet medium channel, the inlet medium channel is connected to the inlet medium tank, and the outlet medium channel is connected to the return medium tank via a return medium pipe; A partition is provided in the cavity of the shell, and the partition divides the cavity into a positive pressure cavity and a negative pressure cavity. The air inlet is connected to the positive pressure cavity, and the air outlet is connected to the negative pressure cavity.

2. The high-speed, wide-format, full-color water-based inkjet printing mechanism for a roll substrate according to claim 1, characterized in that: The air guide structure includes a plurality of air guide strips arranged on the arc-shaped edge of the shell. The air guide strips are long strips with a V-shaped cross section. The V-shaped tip of the long strip is arranged away from the printing roller, and an air outlet gap is formed between adjacent air guide strips.

3. The high-speed, wide-format, full-color water-based inkjet printing mechanism for a roll substrate according to claim 1, characterized in that: The printing assembly includes a printing bracket, which is vertically slidably mounted on the frame through a vertical screw module. The printing bracket is provided with printing nozzles arranged in rows in an arc shape. A moisturizing bracket is provided on the frame below the printing nozzles. The moisturizing bracket is mounted on the frame through a horizontal screw module. The moisturizing bracket is provided with a number of moisturizing sealing frames corresponding to the positions of the printing nozzles. An ink scraper rod is slidably mounted on the moisturizing bracket. A scraper blade is provided on the ink scraper rod. The position of the scraper blade corresponds to the position of the printing nozzles arranged in rows.

4. The high-speed, wide-format, full-color water-based inkjet printing mechanism for a web substrate according to claim 3, characterized in that: The printing bracket is provided with a print head mounting bar, the print heads are mounted on the print head mounting bar, each row of the print heads is mounted on two parallel print head mounting bars, and the positions of the print heads on the two print head mounting bars correspond to each other.

5. The high-speed, wide-format, full-color water-based inkjet printing mechanism for a roll substrate according to claim 3, characterized in that: The printing nozzle is provided with an ink inlet and an ink outlet, the ink inlet is connected to the main ink cartridge, the ink outlet is connected to the return ink cartridge, and the main ink cartridge and the return ink cartridge are respectively connected to a negative pressure device.

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