In gravure printing, the surplus ink on the plate cylinder is scraped off with a scraper, and the ink in the eye of the cylinder is transferred to paper, film and other materials to complete printing. The transfer of ink is achieved by using an imprint cylinder. Because the concave through the rubber imprint cylinder gives the plate cylinder pressure, so the imprint cylinder must be pressure resistant and firm, the usual way is to hang synthetic rubber on the steel pipe iron core. The imprint cylinder, like the drum, is divided into shaft type and shaft separation type. No matter from the accuracy, or from the strength point of view, it is better to take the shaft as a whole. However, a small gravure press such as narrow polyethylene film printing machine mostly uses separate imprint cylinder. The installation of the imprint cylinder has not been as simple as that of the mounting plate cylinder. However, recently, some embossing rollers use the mounting rod technology to make the roller bearing, which can not only shorten the service life of the necessary wrench for the imprint roller. In addition, there is generally only one imprint cylinder, but there are also three or four rotary table type imprint mechanism, so as to shorten the replacement time of imprint cylinder when the width of plate cylinder and material belt changes, especially in the printing press for building materials, this method has great value. Some high capacity printing machines use the device to prevent the original film from loosening when the imprint cylinder is up and down, and the mechanism to keep the film transport length of each unit at a certain value when the imprint cylinder is up and down, so as to reduce the loss of printing materials when the printing cylinder is stopped. In order to improve the printing effect, the embossing rolling should not be too large. For the concave printing used for replacement printing, it is necessary to replace the embossing cylinder. Considering the mechanical strength, the thick wall steel pipe should be used; for the gravure printing machine for packaging printing, due to the change of the width of the printed matter, the embossing drum needs to be replaced frequently and the pressure is light, so the thin steel pipe is often used. The thickness of the rubber on the imprint drum is generally about 10-15mm, and the hardness of rubber varies with different types of substrate materials. When it is used for printing plastic film, the hardness is about hs70. When it is used for printing paper and rough kraft paper, the hardness must reach hs85-hs90. Rubber hardness for printing effect has a larger, in order to ink, solvent resistance requirements, general use of nitrile rubber and other rubber. Generally, the printing pressure is 150-350kg / 1000mm when plastic film is printed. In order to block the white spots, it is necessary to increase the pressure above 800kg / 1000mm. However, the embossing cylinder used for plastic film printing is of light press type and lacks pressure bearing capacity. Therefore, if the pressure is more than 500kg, the roller will not bend. At this time, only the two ends are under strong pressure, and the central part is easy to appear decolorization phenomenon, and the folk color is inaccurate. This so-called bow (deformation caused) overprint is more prominent in wide format printing. The unbalanced state caused by side pressure will also be the cause of poor register, so the inspection level after the installation of the cylinder is. For easy adjustment, one side pressure adjusting handle can be installed. However, when one side 2 and handle are used in printing, it is easy to appear the instability of lateral overprint and film pleating, which is unfavorable to the printing products with good precision.

In the case of high printing pressure, imprint roll bending, the central part and the end of the pressure is different, in this case, the use of support roller. However, after using the back-up roll, the rubber of the imprint drum heats up and down under the strong pressure, which causes the rubber to deteriorate and has a short service life. Moreover, if the accumulated heat is too high, it will sometimes break. In order to prevent this phenomenon, sometimes have to take for the imprint drum and support roller water. Generally speaking, the support roller is necessary for gravure press which needs high printing pressure, such as gravure press for publication printing, gravure press for rough paper and kraft paper, and gravure press for building materials. Generally speaking, support roller is not necessary for gravure press for film. In order to prevent the central part from pressing out, some gravure printing machines adopt ring beam imprinting roller mode (the cylinder body and shaft are not integrated structure), which has achieved good results. There are other methods to make the imprint cylinder protrude. The amount of protrusion can be calculated by using the beam theoretical formula or by using the published protrusion scale. Using the formula method, even if there is a complete design drawing, the projection scale is only a general standard due to the load
The influence of time on printing quality
Heavy, iron core quality, bearing and other factors, in many cases, also live. Therefore, the correct protrusion can be obtained according to the actual measurement. The method is to first clip carbon paper in the direction of the circumference of the roll, add the fixed pressure load when using, and measure the width of the central part of the drum and three places 50 mm away from both ends. Then, based on the measured value. Where, C is the cylinder protrusion, i.e. the difference between the diameter of the central part of the drum and the distance of 50 mm from the end; N1 is the width of the central part of the drum, N2 is the width of the cylinder 50 mm away from the end, D1 is the diameter of the upper drum (imprint drum), and D2 is the diameter of the lower drum (plate cylinder). If the calculated result is positive, it means that the protrusion is insufficient and must be added; if the result is negative, it means that the protrusion is too large and should be ground to reduce it. The imprint cylinder of gravure press is not driven by gear engagement, but by contact with the cylinder, so as to realize stepless selection of cylinder diameter. Imprint cylinder up and down mechanism and plate roller with pressure mechanism, generally divided into manual, dynamic two kinds. Manual adjustment is carried out by worm gear screw shaft, and automatic adjustment is made by using motor through button. Besides mechanical method, it is common to use steam, oil cylinder, etc. or to reduce or pressurize milk. This method can keep the set printing pressure stable or preset, which is easy to manage and earlier than the stability of print quality. To observe the printing pressure can be from the pressure width, but this method is not very practical. In the case of using the mechanical roller up and down device, it can be judged by the spring's will to generate deformation; when using air pressure and oil pressure, it can display the size of the pressure. In a gravure press, printing is carried out by the pressure between the plate cylinder and the impression cylinder. The pressure causes the rubber to deform and maintain a wide surface. The width of the imprint varies with the diameter of the two rollers, the rubber hardness of the imprinting drum and the printing pressure. The theory and experience of relief plate and flat plate are not suitable for gravure pressure adjustment. Because all lanthanum is the same. In gravure printing, the printed matter is in close contact with the plate cylinder, and the ink is drawn out from the concave part of the plate. In this process, physical states such as surface tension or capillary phenomenon change with the nature of the ink and the printed matter. For example, paper printing, aluminum foil printing, the conditions are not exactly the same. Different substrate materials require different characteristics of the imprint drum and printing. The surface of rough paper and thick paper, requires a particularly high printing pressure.
In fact, the practical printing pressure is not a line, but the highest pressure per unit area. It is necessary for rubber to have a certain degree of deformation. Generally, to get a good printing pressure, you have to have about 13mm imprint width. In high-speed printing, the rubber deformation caused by printing pressure will lead to a large amount of heat accumulation in the rubber layer. When the gradients are very high, sometimes the rubber will break. The relationship between imprint cylinder and printing conditions. It can be seen that although the diameter of the imprint cylinder is small, it is necessary to consider that the deformation of the imprint cylinder will increase. That is to say, even at the same printing speed, compared with the diameter of 150 mm imprint roller, the diameter of 100 mm imprint roller is 1.5 times of the rotational speed, and from the perspective of rigid arm, it should also be limited. Generally speaking, if the printing width is less than 1100mm, the embossing roller can be used without support, while the press with the width of 1000 needs to use the support roller. After a long period of use (about 300 hours), the two ends of the roller will expand due to the influence of ink solvent, resulting in the same arch state as under overpressure. The surface of the imprint cylinder is synthetic rubber. Due to the effect of solvent, it is necessary to grind it frequently. When grinding, attention must be paid to prevent taper and keep the same circumference of polychromatic printing ground. If there is taper, the film is easy to wrinkle, lateral overprint is not accurate. In addition, if the color group imprint drum circumference is different, there will be longitudinal magnetic printing error. In addition, the use of electrostatic gravure printing, due to the greatly improved ink transfer, can improve the printing quality and greatly reduce the pressure in printing, which is conducive to correct overprint, reduce the extension of paper and film, meet the needs of mechanical rotation at the same speed, increase the printing resistance, reduce mechanical wear, etc. ````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````` ````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````` ````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````` ```````````````````````````````````````````````````````````````````
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
We uphold the integrity of cooperation, good quality, good service business philosophy, won the industry's approval, products sold to all over the world; welcome friends from all walks of life to inquire, visit our factory to investigate guidance and business negotiations.