A composite printing machine

Abstract

The present invention belongs to the field of printing technology, and specifically relates to a composite printing machine, comprising a reeling unit, a substrate receiving unit, a unit printing mechanism, a digital printing mechanism, a unit varnishing mechanism, and a reeling unit, which are sequentially arranged. The digital printing mechanism comprises a printing frame, a printing roller and a pressure roller are rotatably provided on the printing frame, and a printing assembly is provided on the printing frame above the printing roller. In the composite printing machine provided by the present invention, the printing substrate first passes through the unit printing mechanism for spot color printing, and then passes through the digital printing mechanism for digital printing. The digital printing wraps the printing substrate around the printing roller for inkjet printing. The printing substrate has good conveying stability and high printing precision. The advantages of the digital printing mechanism complement those of the unit printing mechanism, thereby achieving wide-width, high-speed, full-color printing of the printing substrate. The substrate width can exceed 1 meter, and the substrate conveying speed is fast, exceeding 100 meters per minute.

Description

Technical Field

[0001] The invention belongs to the technical field of printing, and in particular relates to a composite printing machine. Background Art

[0002] There are many printing methods in the printing and packaging industry, including flexo, gravure, offset and digital printing. Flexo, gravure and offset are all unit-based printing, which have great advantages in printing large color blocks and background colors, and have the advantages of low cost, high efficiency and no difference. However, there are certain shortcomings in the printing of overprint, gradient colors and dots. Existing digital printing technologies are mostly flat scanning printing and small roll-to-roll printing, and the application effect of industrial printing is not ideal. Among them, small roll-to-roll printing is mainly used in the printing industry, with low speed and narrow format.

[0003] Currently, for the printing of large-format and colorful packaging, unit printing is mainly used. After printing one color layout, it is dried and then printed on other color layouts. If there are several colors, it needs to be printed several times. The process is cumbersome and the equipment is large. In addition, there are problems with fine brushing accuracy and low printing quality for overprinting, gradient color and dot printing. Summary of the Invention

[0004] The object of the present invention is to provide a composite printing machine which combines the advantages of unit printing and digital printing and realizes high-speed full-color printing on packaging substrates with wide formats.

[0005] In order to achieve the above technical objectives, the technical solution of the present invention is:

[0006] A composite printing machine comprises an unwinding unit, a substrate connecting unit, a unit printing mechanism, a digital printing mechanism, a unit varnishing mechanism and a winding unit, which are arranged in sequence. There is more than one unit printing mechanism.

[0007] As an improvement, the printing mechanism and the varnishing mechanism of the unit both include an anilox roller, a plate roller, a bottom roller, a rubber roller and a doctor blade. The plate roller is connected to the plate loading mechanism, the rubber roller is against the bottom roller, and the bottom roller is connected to the traction motor.

[0008] As a further improvement, the digital printing mechanism includes a printing frame, a printing roller is rotatably provided on the printing frame, and a printing component is provided on the printing frame near the printing roller.

[0009] As a further improvement, a drying device is provided on the printing machine frame, and a cooling structure is provided on the printing roller.

[0010] As a further improvement, the printing roller includes a cylinder, one end of which is connected to the medium inlet and outlet end cover, and the other end is connected to the reversing end cover, and a central shaft is passed through the center of the medium inlet and outlet end cover and the reversing end cover;

[0011] 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 cooling channels and return medium cooling channels, the medium inlet and outlet end covers are provided with a medium inlet groove and a return medium groove, the reversing end cover is provided with a reversing groove, the medium inlet groove is connected to the medium inlet cooling channel, the return medium groove is connected to the return medium cooling channel, the reversing groove connects the same group of medium inlet cooling channels and return medium cooling channels, the central axis is provided with a coaxially arranged medium inlet channel and medium outlet channel, the medium inlet groove is connected to the medium inlet channel, and the return medium groove is connected to the medium outlet channel through a return medium pipe.

[0012] As a further improvement, 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 shell, a cavity being provided in the shell, an air inlet and an air outlet being provided on the shell, an edge of the shell on one side close to the printing roller being arc-shaped, and an air guide structure being provided on a side of the shell close to the printing roller;

[0013] A partition is provided in the cavity of the shell, which 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. The air inlet and the air outlet are connected through a fan.

[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, 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.

[0016] 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.

[0017] 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.

[0018] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0019] The composite printing machine provided by the present invention includes a unit printing mechanism, a digital printing mechanism and a unit varnishing mechanism, so that the advantages of unit printing and digital printing complement each other. First, large color blocks are printed by the unit printing mechanism, and then overprinting, gradient color and dot printing are realized by the digital printing mechanism. Digital printing transports the substrate through the printing roller, has good stability and high printing precision, and is well connected with the unit printing mechanism to realize high-speed, wide-format full-color printing of the roll substrate. The substrate width reaches more than 1 meter and the speed exceeds 100 meters / minute. It also simplifies the process, improves efficiency, reduces costs, has no color difference, a wide color gamut, accurate overprinting, good gradient, and realizes high-quality printing.

[0020] In this application, the number of printing mechanisms of the unit is set according to needs, and can be one or more.

[0021] The unit printing mechanism is an all-in-one traction and printing machine that can perform traction or printing independently, or both functions can be realized simultaneously. The unit printing mechanism in front of the inkjet printing mechanism and the varnishing and coloring group behind the inkjet printing mechanism are both equipped with powered traction, which provides power to the substrate while completing the printing function, so that the substrate of the inkjet printing unit can run stably under constant tension.

[0022] 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 printing substrate to dry the substrate after printing to dry the ink thereon. Specifically, the first oven and the second oven can be used separately or in combination. 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 provided on the printing roller to cool the printing roller. In conjunction with the drying device, the printing roller and the printing substrate thereon are kept at a constant temperature, so that indicators such as the elongation of the printing substrate are stabilized, thereby ensuring printing accuracy.

[0023] The printing component can be adjusted up and down. When not printing, you can use an ink scraper to scrape off the residual ink and dirt on the print nozzle to keep the print spray clean. Then, insert the print nozzle into the moisturizing sealing frame to prevent the print nozzle from being exposed to the air and maintain the printing performance of the print nozzle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural diagram of an embodiment of the present invention;

[0025] Figure 2 It is a structural diagram of the printing mechanism of the unit;

[0026] Figure 3 It is a three-dimensional diagram of a digital printing organization;

[0027] Figure 4 It is a structural diagram of a digital printing mechanism;

[0028] Figure 5 It is a schematic diagram of the structure of the printing roller;

[0029] Figure 6 and Figure 7 It is a structural diagram of the inlet and outlet media end cover;

[0030] Figure 8 It is a structural diagram of the reversing end cover;

[0031] Figure 9 It is a structural diagram of the commutation slot;

[0032] Figure 10 It is a structural diagram of a drying device;

[0033] Figure 11 It is a structural diagram showing the coordination between the drying device and the printing roller;

[0034] Figure 12 It is a schematic diagram of the structure of the printing component;

[0035] Figure 13 It is a structural diagram of the moisturizing bracket;

[0036] Figure 14 It is a structural schematic diagram of the ink supply structure;

[0037] In the accompanying drawings, 1-unwinding unit, 2-substrate connecting unit, 3-unit printing mechanism, 31-anilox roller, 32-plate roller, 33-bottom roller, 34-rubber roller, 35-squeegee, 36-plate loading mechanism, 4-digital printing mechanism, 41-printing frame, 42-printing roller, 421-cylinder, 422-inlet and outlet media end cover, 423-reversing end cover, 424-center shaft, 425-inlet media cooling channel, 426-return media cooling channel, 427-inlet media slot, 428-return media slot, 429-reversing slot, 4210-inlet media channel, 4211-outlet media channel, 4212-rotary joint, 4213-reinforcement sleeve, 4214-reinforcement rib, 4215-return media pipe, 43-pressing roller, 44-printing assembly, 441-spray Printing bracket, 442-vertical screw module, 443-print nozzle, 444-moisturizing bracket, 445-horizontal screw module, 446-moisturizing sealing frame, 447-ink scraper rod, 448-scraper, 449-print nozzle mounting strip, 4410-main ink cartridge, 4411-reflux ink cartridge, 4412-main ink barrel, 4413-main negative pressure bottle, 4414-negative pressure pump, 4415-positive pressure pump, 4416-reflux pump, 4417-reflux negative pressure bottle, 4418-control panel, 45-first oven, 451-shell, 452-air inlet, 453-air outlet, 454-partition, 455-positive pressure chamber, 456-negative pressure chamber, 457-air guide strip, 46-second oven, 5-unit varnishing mechanism, 6-winding unit, 7-correction mechanism. DETAILED DESCRIPTION

[0038] 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.

[0039] 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.

[0040] like Figures 1 to 14As shown together, a composite printing machine includes an unwinding unit 1, a substrate connecting unit 2, a unit printing mechanism 3, a digital printing mechanism 4, a unit varnishing mechanism 5 and a winding unit 6 arranged in sequence. Specifically, there is more than one unit printing mechanism. Since each unit printing mechanism can only print one color, the number of unit printing mechanisms is set according to needs, and multiple units can be set. During use, the unwinding unit realizes the unwinding of the left and right rolls of the roll substrate, the automatic substrate connecting unit completes the substrate connecting and changing rolls without stopping the machine, the unit printing mechanism, the digital printing mechanism and the unit varnishing mechanism complete printing and varnishing, so that the advantages of unit printing and digital printing complement each other. First, the large color blocks are printed by the unit printing mechanism, and then the digital printing mechanism realizes overprinting, gradient color and dot printing. Digital printing transports the substrate through the printing roller, which has good stability and high printing accuracy. In specific use, a correcting mechanism 7 can also be set in front of the unit printing mechanism and behind the unit varnishing mechanism. The front correcting mechanism prevents the substrate path from deviating during operation in front of each printing unit, thereby ensuring the accuracy of printing and overprinting. The rear correcting mechanism ensures the effect and quality of winding before winding. Finally, the winding unit, the unwinding unit, the substrate connecting unit, the winding unit and the front and rear correcting mechanisms can all use the existing structures used in this field.

[0041] In this embodiment, the unit printing mechanism and the unit varnishing mechanism both include an anilox roller 31, a plate roller 32, a bottom roller 33, a rubber roller 34 and a doctor blade 35. The plate roller is connected to the plate-applying mechanism 36, the rubber roller is against the bottom roller, and the bottom roller is connected to the traction motor. The unit printing mechanism is a traction and printing all-in-one machine, which can perform traction or printing separately, or both functions can be realized at the same time. The unit printing mechanism in front of the inkjet printing mechanism and the varnishing color group behind the inkjet printing mechanism are both equipped with power traction, which provides power to the substrate while completing the printing function, so that the substrate of the inkjet printing unit can run stably under constant tension.

[0042] In this embodiment, the digital printing mechanism includes a printing frame 41, on which a printing roller 42 is rotatably provided. The printing roller is usually used in conjunction with a pressure roller 43 to improve the use effect. A printing assembly 44 is provided on the printing frame above the printing roller.

[0043] In this embodiment, during digital printing, the substrate is transported by the printing roller, which has good stability and does not cause the printed substrate to swing left and right or jump up and down, so as to achieve stability in the substrate transportation process, improve printing accuracy, and connect well with the printing mechanism of the unit to achieve high-speed, wide-format, full-color printing of the roll substrate. The substrate width reaches more than 1 meter and the speed exceeds 100 meters / minute. In addition, the process is simplified, the efficiency is improved, the cost is reduced, there is no color difference, the color gamut is wide, the overprint is accurate, the gradient is good, and high-quality printing is achieved.

[0044] In actual use, the print roller is connected to an auxiliary traction motor. The traction motor and the auxiliary traction motor operate synchronously, and the rubber roller presses the substrate tightly against the bottom roller and the print roller. The rotation of the bottom roller and the print roller provides traction force on the substrate, pulling the printed substrate forward. The print roller provides auxiliary traction force, reducing the traction force required by the bottom roller and achieving smooth transportation of the printed substrate. The printing mechanism of this embodiment is an integrated traction and printing machine. Compared with existing dedicated traction mechanisms, it simplifies the equipment structure, reduces costs, and saves equipment space. In addition, the enlargement of the bottom roller increases both strength and peripheral space.

[0045] In this embodiment, a drying device is provided on the printing machine frame to dry the substrate after printing to dry the ink thereon. Since the 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 provided on the printing roller to cool the printing roller. In conjunction with the drying device, the printing roller and the printing substrate thereon are kept at a constant temperature, so that the elongation of the printing substrate and other indicators are stabilized, thereby ensuring printing accuracy.

[0046] In this embodiment, the printing roller 42 includes a cylinder 421, one end of which is connected to a medium inlet and outlet end cover 422, and the other end is connected to a reversing end cover 423. A central shaft 424 is provided through the centers of the medium inlet and outlet end cover and the reversing end cover.

[0047] The cooling structure includes a cooling channel arranged in the cylinder, and the extension direction of the cooling channel is parallel to the axial direction of the cylinder. Specifically, the cylinder is a seamless steel pipe, and the cooling channel is a through hole arranged in the tube wall of the cylinder. The cooling channel includes several groups of spaced-apart medium cooling channels 425 and return medium cooling channels 426. The medium inlet and outlet end covers are provided with medium inlet grooves 427 and return medium grooves 428, and the reversing end covers are provided with reversing grooves 429. The medium inlet grooves are connected to the medium inlet cooling channels, and the return medium grooves are connected to the return medium cooling channels. The reversing grooves connect the same group of medium inlet cooling channels and return medium cooling channels. The central axis is provided with coaxially arranged medium inlet channels 4210 and medium outlet channels 4211. The medium inlet grooves are connected to the medium inlet channels, and the return medium grooves are connected to the medium outlet channels through the return medium pipe 4215. A through hole connecting the medium inlet groove and the medium inlet channel is provided on the central axis. The bottom of the groove where the medium inlet groove is connected to one end of the through hole is provided with a chamfered structure, and the positions of the through hole and the chamfered structure correspond to each other. In actual use, the central axis is connected to the rotary joint 4212, the medium inlet of the rotary joint is connected to the medium inlet channel, and the medium outlet is connected to the medium outlet channel.

[0048] Specifically, the medium inlet groove extends along the radial direction of the medium inlet and outlet end cover, and the medium inlet groove extends close to the circumferential surface of the end cover and turns to extend parallel to the axial direction of the medium inlet and outlet end cover. There are multiple medium inlet grooves, and they are evenly distributed along the circumference of the medium inlet and outlet end cover. The return medium groove is located on the circumferential surface of the medium inlet and outlet end cover and extends along the circumference of the medium inlet and outlet end cover. The groove wall of the return medium groove is lower than the groove wall of the inlet medium groove. Accordingly, 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 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.

[0049] In this embodiment, reinforcing ribs are provided between the central shaft and the end cover. The reinforcing ribs include a reinforcing sleeve 4213 fixedly mounted on the central shaft. Reinforcing ribs 4214 are connected around the reinforcing sleeve. The reinforcing ribs are radially radiated with the reinforcing sleeve as the center to enhance the structural strength of the entire drum.

[0050] In this embodiment, the center shaft and the end cover are connected by interference fit and shrinkage to avoid damage to the center shaft caused by welding, etc., 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. The strength of the end cover, pressure plate and cylinder is less affected, and the weld will not contact the cooling medium.

[0051] In actual use of this embodiment, the roller is an integrated seamless steel pipe without inner and outer jackets. Evenly distributed long holes are processed on the pipe wall as cooling medium channels. Every two adjacent holes form a group, which are the inlet medium and the return medium respectively. The cooling medium flows from the inlet medium side to the reversing side and then flows back, avoiding the temperature difference between the two sides when flowing in from one side and out from the other side.

[0052] Traditional jacketed systems feature spiral media separators welded around the jacket's circumference. The cooling channel length is the product of the circumferential diameter and the number of spiral turns, making it excessively long. The present invention, which circulates through a straight hole, significantly reduces the cycle time to several tenths of the original at the same flow rate, significantly accelerating the circulation speed and enabling faster and more precise temperature control. Furthermore, the long hole structure employed in this embodiment eliminates the need for welding, resulting in a simpler structure and greater resistance to rust.

[0053] When the present invention is in use, the cooling medium flows from the medium inlet channel of the central axis through the medium inlet groove of the end cover into the medium inlet cooling channel, then flows into the return medium cooling channel through the reversing end cover, and finally flows into the medium outlet channel through the return medium pipe, completing the cooling process.

[0054] In this embodiment, the drying device includes a first oven 45 and a second oven 46. The second oven 46 is located near the printing substrate. The first oven 45 includes a housing 451, which has a cavity therein and is provided with an air inlet 452 and an air outlet 453. The housing has an arc-shaped edge on one side near the printing roller, and an air guide structure is provided on the side of the housing near the printing roller.

[0055] A partition 454 is provided in the cavity of the shell, which divides the cavity into a positive pressure cavity 455 and a negative pressure cavity 456. The air inlet is connected to the positive pressure cavity, and the air outlet is connected to the negative pressure cavity. The air inlet and the air outlet are connected through a fan.

[0056] Specifically, 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, which can be determined according to factors such as the use environment, the drying ability of the ink and the printing speed.

[0057] When the first oven is actually used, hot air enters the positive pressure chamber from the air inlet and is blown toward the substrate through the air guide structure. Under the action of pressure difference, the hot air enters the negative pressure chamber and flows out from the air outlet. It is recycled by the fan, saving energy. The pressure difference guides the air so that the hot air flows along the surface of the substrate. This is different from the traditional direct blowing method of drying, which improves the drying efficiency.

[0058] In this embodiment, the air guide structure includes a plurality of air guide strips 457 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 serve to strengthen the strength of the shell structure.

[0059] In practice, the housing is slidably mounted on the printer frame via slide rails and a pneumatic cylinder. This facilitates adjustment of the distance between the housing and the substrate on the print roller, ensuring effective drying while preventing overdrying due to proximity. It also facilitates maintenance of the substrate and print roller. When operating, the housing is adjusted close to the print roller; when not operating, it is moved away from the roller. In actual use, the direction of hot air flowing from the positive-pressure chamber to the negative-pressure chamber is opposite to the direction of rotation of the print roller, increasing the relative velocity between the hot air and the substrate and improving drying efficiency.

[0060] In this embodiment, the printing assembly 44 includes a printing bracket 441, which is vertically slidably mounted on the frame through a vertical screw module 442. The printing bracket is provided with printing nozzles 443 arranged in an arc shape in rows. A moisturizing bracket 444 is provided on the frame below the printing nozzles. The moisturizing bracket is mounted on the frame through a horizontal screw module 445. The moisturizing bracket is provided with several moisturizing sealing frames 446 corresponding to the positions of the printing nozzles. The top of the moisturizing sealing frame is open and the other surfaces are closed, which can hold a certain amount of ink. An ink scraper rod 447 is slidably provided on the moisturizing bracket, and a scraper blade 448 is provided on the ink scraper rod. The position of the scraper blade corresponds to the position of the printing nozzles arranged in a row. The printing assembly can be adjusted up and down. When not printing, the ink scraper blade can be used to scrape off residual ink and dirt on the printing nozzle to keep the printing spray clean. Afterwards, the printing nozzle is inserted into the moisturizing sealing frame to prevent the printing nozzle from being exposed to the air and maintain the printing performance of the printing nozzle. Specifically, the moisturizing bracket can be configured as a pool-like structure to store scraped residual ink and dirt to avoid contamination of other components.

[0061] In this embodiment, a print head mounting bar 449 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 dual negative pressure circulation ink supply structure, and the printing nozzle is provided with an ink inlet and an ink outlet, the ink inlet is connected to the main ink cartridge 4410, and the ink outlet is connected to the return ink cartridge 4411, and the main ink cartridge and the return ink cartridge are respectively connected to the negative pressure device. Specifically, the ink inlet of the main ink cartridge is connected to the main ink barrel 4412 through a connecting pipe, and an ink supply pump, a filter and a degassing device are provided on the connecting pipe. The air vent of the main ink cartridge is connected to an inlet of the three-way valve, and an outlet of the three-way valve is connected to the main negative pressure bottle 4413, and the main negative pressure bottle is connected to the negative pressure pump 4414 through a valve, and the other outlet of the three-way valve is connected to the positive pressure pump 4415; the ink outlet of the return ink cartridge 4411 is connected to the return pump 4416, and the return pump is connected to the main ink barrel 4412, and the air vent of the return ink cartridge is connected to the return The flow negative pressure bottle 4417 and the reflux negative pressure bottle are connected to the negative pressure pump 4414 through a valve. The status of the pump and the valve are controlled by the control board 4418 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. The main ink barrel returns to the main ink cartridge through the ink supply pump, and adopts a double negative pressure method to control the pressure difference to make the ink circulate normally. At the same time, it also ensures that the ink in the print nozzle does not drip, and ensures that the bubbles and impurities generated during the printing process are taken away in time to ensure the stability of ink supply and ink.

[0063] In specific use of this embodiment, the printing substrate first passes through the unit printing mechanism for spot color printing, and then passes through the digital printing mechanism for digital printing. Both the unit printing mechanism and the digital printing structure are provided with a drying structure, which is dried after each printing step before entering the next step. The digital printing of this embodiment wraps the printing substrate around the printing roller for inkjet printing, and the printing roller maintains a constant temperature. The printing substrate has good conveying stability and high printing accuracy. It cooperates with the unit printing mechanism, and the advantages complement each other to achieve wide-width, high-speed, full-color printing of the printing substrate. The substrate width can exceed 1 meter, and the substrate conveying speed is fast, exceeding 100 meters / minute.

[0064] 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 composite printing press, characterized in that: It includes an unwinding unit, a substrate receiving unit, a unit printing mechanism, a digital printing mechanism, a unit varnishing mechanism and a winding unit, which are arranged in sequence. There is at least one unit printing mechanism; The printing mechanism and varnishing mechanism of the unit both include an anilox roller, a plate roller, a bottom roller, a rubber roller and a doctor blade. The plate roller is connected to the plate loading mechanism, the rubber roller abuts against the bottom roller, and the bottom roller is transmission-connected to the traction motor. The digital printing mechanism includes a printing frame, a printing roller is rotatably provided on the printing frame, and a printing assembly is provided on the printing frame near the printing roller; The printing machine frame is provided with a drying device, and the printing roller is provided with a cooling structure; The printing roller includes a cylinder, one end of which is connected to the medium inlet and outlet end cover, and the other end is connected to the reversing end cover, and a central shaft is passed through the center of the medium inlet and outlet end cover and the reversing end cover; The cooling structure includes a cooling channel provided on the cylinder, wherein 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, the inlet and outlet medium end covers are provided with inlet medium grooves and return medium grooves, the reversing end covers are provided with reversing grooves, the inlet medium grooves are connected to the inlet medium cooling channels, the return medium grooves are connected to the return medium cooling channels, the reversing grooves are connected to the same group of inlet medium cooling channels and return medium cooling channels, the central axis is provided with a coaxially arranged inlet medium channel and outlet medium channel, the inlet medium grooves are connected to the inlet medium channels, and the return medium grooves are connected to the outlet medium channels via a return medium pipe; 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; A partition is provided in the cavity of the shell, which 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. The air inlet and the air outlet are connected through a fan.

2. The composite printing machine 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 composite printing machine 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 composite printing machine 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 composite printing machine 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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