Analyze the satellite flexo press (below)
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Let's take a look at the structure of several different ways in which the components are usually seen.
Unwinding part
The unwinding part is the same as our common coil type unwinding structure, which can be divided into single station, upper and lower duplex, and double duplex. Among them, each manufacturer has a big difference in function and shape according to its own design, material selection, manufacturing process, etc., but the principle and the final purpose are the same.
Single stations are mainly used for large diameter materials such as cardboard and base paper. Usually the diameter is above 1270mm. The upper and lower duplex positions are a very simple structure that is mounted directly on the side of the wall. This can reduce the floor space, reduce the size of the whole machine, and also facilitate installation and commissioning, suitable for places where the work space is relatively tight. Part of the upper and lower double-station structure can also realize non-stop refueling. The flip-over duplex position can be divided into a cantilever-type flip-up double-station and a disc-turning double-station. The cantilever-type flip-up double-station is a structure that is commonly used in gravure printing machines. This structure is relatively thin, and most of them are based on the Japanese Fuji model. This structure is suitable for unwinding of plastic films at speeds below 200 m/min. Since the turning mechanism is adopted in the form of a worm gear or a gear pair transmission, the gap and the rigidity of the cantilever are very likely to cause up and down shaking during the turning process, which may affect the tension change, thereby affecting the printing quality. Therefore, a disc-type flip double station is usually used on a high-speed printing press with a speed of 300 m/min. The disc structure is very compact, with either a timing belt drive or a gear drive. The flipping process is very smooth and does not affect printing.
There are four types of braking methods for unwinding: mechanical braking, magnetic powder braking, pneumatic braking, and motor braking. Mechanical braking is a very transmission structure that is often seen on cascading flexographic presses. Magnetic powder braking uses the electromagnetic principle to brake the coil. Pneumatic brakes are mainly used for large-diameter paper brakes. It is much more economical to use pneumatic brakes than large-diameter brakes. Motor brake is a popular brake method in recent years. It is mainly used after the motor brake, it can realize a lot of automation functions, for example, the pre-drive function can be automatically exchanged.
Between the unwinding and printing sections, an in-row correction system is usually added as needed. In order to correct the edge irregularities before the raw materials enter the printing.
Second printing part
The biggest feature of the satellite flexo press is that it has a large diameter central printing roller. The diameter of the roller is usually between 1250 and 2700mm, and the double-wall structure is beneficial to the temperature control of the central printing roller. The surface of the central printing roller has a nickel-plated protective layer, and the thickness of the nickel layer is about 0.3 mm. The central printing roller is mounted on the roller bearing to control the eccentricity error of the central printing roller within ±0.008 to 0.012 mm. All printing is done on top of this roller. Therefore, this roller becomes the core of the whole machine. Its internal structure, materials, machining process, heat treatment mode, dynamic and static balance control, and temperature control during use determine the quality of the final print. In order to allow the substrate to be printed under the surface of the roller, it is first necessary to ensure the smoothness of the surface of the roller and the jitter error as small as possible during the rotation. Therefore, the roll surface runout error of an excellent satellite flexo press must be within the rated error range. At the same time, in order to reduce the thermal energy difference in the printing process, the external environment temperature difference between day and night, the physical deformation of thermal expansion and contraction affects the roller, and it is usually necessary to use a constant temperature circulation system to control the temperature of the roller. Keep the roller at a constant temperature and extend the life of the device.
The printing unit of the satellite flexo press is surrounded by a large star, surrounded by a large star like a small satellite. Therefore, devices of this type are all satellite-type. Satellite flexo presses, like other flexo presses, use an anilox roller to deliver ink.
1. Center embossing roller
2. Plate roller
3. Ceramic anilox roll
4. Closed double scraper cartridge
5. Ink bucket
6. Ink pump
Due to the updating and development of technology, closed double-squeegee inking systems and ceramic anilox rolls are commonly used in satellite flexo printing presses. 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. Therefore, 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 ink is sprayed onto the surface of the anilox roller through the ink port to be 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.
The plate of the flexo press is attached to the plate cylinder by double-sided tape for the best plate effect. Usually each manufacturer's equipment is equipped with a special plate machine. There are multiple magnification devices (optical magnifier or magnifying glass) on the plater to enlarge the details. The plate is then accurately attached to the plate cylinder in accordance with the specified requirements. Figure 8 below is an outline drawing of an applicator. At present, the plate-type roller of the sleeve type structure is popular in Europe and America, but due to insufficient supply in this aspect in China, the promotion of this technology needs to be improved.
The forward and backward movement of the printing unit is accomplished by mechanical screwing of the screw. Depending on the model configuration, it can be divided into manual, semi-automatic, and fully automatic modes. When the device is in the coarse adjustment process, it can be fully automatic and semi-automatic to complete the forward and backward. Manual fine-tuning is used when making fine adjustments to the print. After the adjustment is completed, the printing unit is fixed in position using a hydraulic locking mechanism. When emergency stop is caused for a special reason, a protection device inside the printing unit can quickly move the printing unit as a whole back a certain distance to allow the printing plate to leave the surface of the center imprinting roller. So as not to hurt each other, damage the parts.
The satellite flexo press has been able to achieve reverse printing functions under the market demand and through engineering innovation. However, due to the influence of the structure, it can only be 3+3 or 4+4. Moreover, when printing certain products, such as casing coating film printing, an 8-color 1000 wide-format satellite flexo printing machine can achieve 8+8 color of the casing film below 500mm through a special mechanism. Reverse printing.
Three dry parts
Satellite type flexographic printing machine for separation between color separation and bridge drying. The inter-color drying is mainly to pre-dry the surface of the ink that has been printed well for each color, so as not to affect the printing of the next color. Once all printing has been completed, it is thoroughly dried by the final bridge dryer.
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. Usually, the inside of the channel is equipped with a temperature detecting rod. When the set temperature is reached, the air valve is opened and closed by a cylinder to ensure the constant temperature in the drying channel.
At present, there are many ways to supply thermal energy, and electric heating, oil heating, steam heating, and gas heating can be used. Depending on the product, UV printing and drying can also be used in conjunction with the printed part.
Four cooling parts
The cooling of the satellite flexo press mainly refers to the cooling and winding traction cooling of the central printing cylinder. The cooling of the central printing roller is mainly to maintain a constant temperature, so as not to affect the printing accuracy and quality. The function of winding traction cooling is mainly to cool the printed product after passing through the temperature carried by the drying oven. In order to avoid the natural cooling of the winding, it will affect the next compounding process.
Five winding part
The structure of the winding part is the same as that of the unwinding described above, and can usually be divided into a single station, a double station, a double station, and the like. But in terms of control methods, there are differences. In the early practice, the magnetic powder clutch was driven by the main motor, the tension change was detected by the tension sensor, and the tension of the magnetic powder clutch was adjusted by the tension controller to control the winding tension. The current mainstream is coiled by the variable frequency motor. The tension is detected by a floating swing arm. The displacement signal is detected by the angle potentiometer, converted into an electrical signal, transmitted to the controller, and then fed back to the inverter to control the motor. speed. In this way, more functions can be realized through PLC programming, such as: automatic taper tension, non-stop refueling, and the like. At present, such control methods are very mature in both gravure printing machines and flexographic printing machines.
Before the winding, in order to ensure the quality of the products, the satellite flexo printing machine is equipped with an online still picture monitoring system and a traveling correction system before winding. The former can detect printing problems such as print quality, overprinting error, ink chromatic aberration, etc. through the display. The latter can eliminate the deviation of the substrate when passing through the bridge drying device after printing, so that the winding is more neat.
Six connection processing
The satellite flexographic printing press has a general processing capability, but with the addition of components. It can realize the functions of connection die cutting and breaking. According to the actual product demand, it is also possible to install gravure and other units. But the speed advantage will be lost. The more static application is after the carton is pre-printed, and the cross-cut is performed by photoelectric tracking.
Seven main drive
The main drive of the satellite flexo press can be divided into two types: mechanical gear transmission and electronic shaft gearless transmission. In the mechanical gear transmission type flexo printing machine, the rotation of the plate cylinder and the anilox roller drives the plate cylinder gear through the central printing roller gear, and the plate cylinder gear drives the gear of the anilox roller to form a synchronous rotation. The repeat length of the print depends on the gears of the plate cylinder and the plate cylinder, and the gears are affected by the pitch and modulus, so the repeating circumference of the print is the same as the pitch of the gears. The rotation of the anilox roller of the flexo printing machine with the electronic shaft without gear transmission is directly driven by the plate cylinder, which solves the problem that the repeated length of the flexographic printing product is limited by the gear pitch.
Each printing unit of the satellite flexo printing machine electronic shaft without gear transmission 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 of the plate cylinder. Rotating, one motor controls the lateral registration of the plate cylinder and the horizontal 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, since the electronic shaft is gearless, it is not necessary to replace the gear 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.
The mechanical gear transmission has a simple structure, good rigidity and low cost, and is suitable for initial contact with flexographic customers. The electronic shaft gearless drive must be used in conjunction with a sleeve plate cylinder. The structure is complex and the maintenance and use costs are high. However, with the popularity of manufacturing technology, electronic shaft gearless transmission will be an industry trend, which will eventually replace mechanical transmission.
Eight control section
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.
The manual adjustment-based rapid control system is simple to operate, and the training and maintenance of the operator is simple, and the entry threshold is low. The automatic adjustment control system is powerful, complex in structure, multi-functional, highly automated and user-friendly, and requires high-quality engineering and technical personnel to maintain and use.