New structure and advanced technology of satellite flexo printing machine
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The satellite flexo press, also known as the Central Impression or the central impression cylinder flexo press, is the most important model in the flexo press. According to some data, in Europe and the United States, satellite flexo printing machines account for 70 to 80% of all flexographic printing machines. In China, flexographic printing technology is being used more and more widely, and satellite flexo printing machine will become a major model in the application field of flexographic printing machines in China.
The satellite flexo printing machine has many advantages: its control system is simpler, the investment is lower; the overprinting precision is high, the production efficiency is high; the production line runs stably and reliably, and the adaptability is wide. Satellite flexo presses are mainly used in flexible packaging, cartons, labels and pre-printing of corrugated boxes. In general, the components of a satellite flexo press include: unwinding and input sections, printing sections, drying sections (inter-color drying and final drying), cooling sections, output and winding sections or wiring processing sections, and main drive And control parts, etc.
The technical level of the satellite flexo press can be more accurately expressed by the following performance systems: maximum printing color and printing arrangement, printing material and printing width, printing graphic repeat length range, drying method, printing speed, adapted printing materials, The type of ink, but the focus on the technical level of the flexo press is its control and automation system. Although the flexo press employs a wide variety of control and automation systems. But it can be roughly divided into semi-automatic and fully automatic.
The following is a brief introduction to the new structure and advanced technology of the satellite flexo press:
Sleeve plate cylinder and anilox roller
Plate cylinders and anilox rolls are available in both integral and sleeve types. The overall structure is simple, rigid and adaptable, but the replacement is complicated. The sleeve type is easy to replace, but the structure is complicated, and each component has a pneumatic quick clamping release device. Because the sleeve type plate cylinder has low cost, easy loading and unloading, high flexibility, long service life, convenient storage, high system precision and quick plate changing function, it has been widely used in flexo printing and gravure printing, and will be gradually replaced. Traditional plates.
The sleeve plate cylinder (or sleeve type anilox roller) consists of a mandrel, a gas-supporting roller (empty roller) and a sleeve. When replacing the plate cylinder (or anilox roller), as long as the air pressure switch on the printing unit is turned on, the compressed air is input to the air expansion roller, and is evenly discharged from the small hole of the inflation roller to form an air cushion, so that the inner diameter of the sleeve is enlarged. Expansion, the original plate cylinder (or anilox roller) sleeve used will automatically pop out, replace the new plate cylinder (or anilox roller) sleeve, the new sleeve can easily and conveniently slide on the inflation roller Go to the required location. Close the air pressure switch and the plate cylinder and anilox roller will be fixed. When the compressed air is cut, the sleeve shrinks immediately and is fastened to the inflation roller. The inner diameter of the sleeve is generally smaller than the outer diameter of the air bearing roller to ensure its engagement. Two or more sleeves can also be mounted on the same inflation roll. To replace or remove the sleeve, simply inflate the inflation roll again. The sleeve circumference and diameter of the new satellite flexo plate cylinder (or anilox roller) can be varied while the mandrel size is unchanged.
The biggest advantage of the simple plate cylinder is that it can be reused, and the photosensitive resin plate can be attached to the sleeve at any time. In addition, the sleeve can also be used for laser engraving and plate making, using seamless stitching, printing continuous patterns or the same background pattern. If the allowable printing circumference of the sleeve system varies by 150 mm, the inner diameter of the sleeve with a printing circumference of 350 to 500 mm is the same, and only one inflation roller is required. By changing the wall thickness of the sleeve, the purpose of changing the circumference of the sleeve can be achieved.
Gearless direct drive technology
The rotation of the plate cylinder and the anilox roller of the old-fashioned flexo printing machine drives the plate cylinder gear through the impression roller gear, and the plate cylinder gear drives the gear of the anilox roller to form a synchronous rotation. The repeating length of the printed matter depends on the gears of the plate cylinder and the plate cylinder, and the gear is limited by the pitch and the modulus, and therefore, the repeated circumference of the printed matter is the same as the pitch of the gear. The rotation of the new flexographic printing machine anilox roller is directly driven by the plate cylinder, which solves the problem that the repeating length of the flexographic printing product is limited by the gear pitch.
Each printing unit of the satellite gearless flexo printing machine is driven by 7 motors, 4 of which drive the plate cylinder and the anilox roller to move back and forth, and 1 motor controls the longitudinal registration and rotation of the plate cylinder. The motors control the lateral registration of the plate cylinder and the transverse movement of the plate cylinder, and one motor drives the rotation of the anilox roller. After the plate is loaded, the perimeter of the plate cylinder of the plate cylinder is input, and the plate cylinder and the anilox roller are brought to the pre-printing and pre-registration position by the PLC control, which greatly shortens the printing pressure and the printing registration time, and also saves the time. Raw materials.
At the same time, due to the use of gearless transmission, there is no need to change gears when replacing printed products of different circumferences. The gearless-drive satellite flexo press replaces the flexographic cylinder and anilox roller on one unit in just one minute, greatly reducing the time it takes to change the plate and the anilox roll when replacing the product.
Germany's EROMAC company launched a satellite flexographic printing machine automatic registration system, using a register probe to control the registration of all printing units of the flexo press, instead of 6 sets of registration probes and auxiliary motors for seven-color printing of gravure printing machine. When the printing product is not inaccurate, the register probe directly drives the motor to adjust the longitudinal and lateral overprinting position of the plate cylinder. Unlike the longitudinal registration of the gravure, the plate cylinder is adjusted by the auxiliary motor. The EROMAC automatic registration system is used to adjust the plate cylinder. The adjustment takes a short time and consumes less printing material. The system can be automatically registered according to the registration cross line, or can be registered according to the manual setting, in order to solve the error between the printing pattern and the overprinting cross line generated during the plate making and pasting.
Closed double scraper chamber inking system
Although the two-roller type is used in the flexo press, the positive scraper type and the reverse scraper type structure can realize the quantitative ink supply, but since these are all open type ink supply, ink is stored by the ink tank, and the ink roller is used. Part of the ink is used for printing, and the excess part is returned to the ink tank. This open structure allows the ink to be directly exposed to the atmosphere in a large area. If a solvent-based ink is used, the solvent evaporates into the air, which causes changes in ink characteristics and environment. Pollution; if water-based ink is used, bubbles are easily generated, which affects the printing quality.
Most of the satellite wide-format flexo printing machines adopt a fully enclosed double-squeegee inking system. The inking system consists of a blade holder, two scrapers, a side sealing plate made of wear-resistant soft material and an anilox roller to form a closed ink chamber. The flexo ink is sprayed onto the surface of the anilox roller through the ink port and stored in the ink chamber, and the ink is scraped by the reverse scraper to seal the positive scraper. According to the principle of fluid mechanics, the ink or cleaning agent is in a flowing state in the ink fountain, so that even a small amount of ink can be recycled, and a small amount of cleaning agent can be used for rapid cleaning. Because of the good sealing, it has great benefits for health and environmental protection. The closed double-blade chamber inking system consists of ceramic anilox roller, two scrapers, sealing strips, ink storage container, ink pump, ink hose and other components. In a fully enclosed system, the scraper, seal, gasket, and pressure plate are mounted on a cavity bracket, mechanically (or pneumatically, hydraulically) pushed toward the ceramic anilox roller, and a certain pressure is applied, and then The ink feed pipe and the return pipe are respectively connected to the ink pump and the ink storage container. The system has the following characteristics: the reverse scraper structure is adopted in the quantitative ink supply system, which is suitable for high-speed operation, avoids the problem of solvent evaporation and environmental pollution in the solvent-based ink, and solves the foam problem accompanying the use of the aqueous ink. The system can also be quickly docked with an automated cleaning system for quick cleaning to reduce ink change times and downtime.
Non-stop fast change device
The pressure roller device and the tape break device operate pneumatically, using a gas-electric tension measurement and adjustment device to ensure constant tension. The automatic paper-feeding mechanism works normally even at the maximum roll diameter, thus ensuring tension control at the highest printing speed. In order to ensure that the printing material enters the edge of the printed part, the position is always correct. For opaque materials such as paper, a correcting device composed of a photoelectric scanning head or an ultrasonic sensor is also used. When printing paper or paper jams, temperature and humidity adjustments are sometimes performed. When printing plastic film or aluminum foil. A corona treatment device is also provided to increase the ink repellency of the film surface.
Temperature-controlled impression cylinder and high-power drying/cooling system
The impression cylinder of the satellite flexo press has a double wall structure. Conducive to the temperature control of the impression cylinder. The surface of the impression cylinder has a nickel-plated protective layer. The thickness of the nickel layer is about 0.3 mm. The impression cylinder is mounted on the roller bearing to control the eccentricity error of the impression cylinder within 0.008-0.012 mm. The impression cylinder is subjected to dynamic balancing and static balance. The impression cylinder is equipped with a water circulation system. In order to keep the temperature of the outer surface of the impression cylinder constant, the impression cylinder is prevented from being thermally expanded. Some flexo presses also have over-temperature protection. When the temperature exceeds a certain maximum value, the power of the entire press will be automatically cut off.
The inter-color drying device and the bridge drying device between the printing color groups use double-circuit circulating air to reduce the demand for fresh air, thereby reducing the consumption of heating energy.
Modular intelligent control management system
There are three types of control systems for satellite flexo presses: a rapid regulation system based on manual adjustment, an electronic information system based on automatic adjustment, and a digital control system based on fully automatic adjustment. The digital control system drives the printing unit with 7 stepper motors, manages and monitors the printing area with PC/PLC technology, achieves automatic registration in the axial and circumferential directions, and rotates the anilox roller at low speed during shutdown, and passes through the modem for the whole The press provides troubleshooting.
Modern satellite flexo presses mainly have the following control and management functions:
■ Modular automatic operating system, which can pre-select menu, centralized operation unwinding/rewinding unit, printing unit, drying unit, and optional camera observation module to view the entire printing process on the display screen.
■Intelligent transmission system and positioning system ensure accurate movement and lateral registration of plate cylinders and anilox rollers of various color groups.
■ Electronic synchronous adjustment and computer controlled fast-forward system, through stepper motor speed measurement, to ensure highly accurate setting of printing pressure, printing length, plate and substrate thickness. Ensure that the equipment does not generate waste when registering in the stop state, and achieve coordination between the printing unit and the anilox roller.
■ Robotic roll change system for automatic replacement of plate cylinders and anilox roll systems.
■Ink supply and cleaning system for quantitatively supplying ink to printing parts and automatically cleaning the anilox roller, cavity type squeegee system, ink pump and ink tube. The cleaning sequence is controlled by computer, which greatly reduces labor intensity and significantly improves efficiency. , reducing the downtime of replacement.
■ Remote control system. Remotely adjust and control printing pressure, tension control, lateral and vertical automatic registration.