Improvement of flat flexo printing technology of t

2022-08-16
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Improvement of Corrugated Paperboard Flexo Printing Technology

after more than 30 years of research and improvement and strong market demand, Corrugated Paperboard Flexo printing machine has made considerable progress so far. Problems such as unstable paper feeding, large registration error, difficult machine adjustment, ink scraping and dust have been greatly improved. The degree of improvement can be analyzed by the structure of the following groups of units:

(I) paper feeding part

the traditional paper feeding unit is a push back type, which is often unable to feed due to the bending of the paperboard, and the paper feeding cannot ensure the positioning of the paperboard, resulting in registration errors. After the improvement, vacuum adsorption is used for small-area adsorption plates or rollers. Although the above shortcomings can be improved, deviations will still be caused for large-area paperboard due to insufficient contact area. Aiming at these shortcomings, French Martian company has developed large-area adsorption contact. Krispian Lawrence announced that lechal will face the public users with empty adsorption belt type paper feeding system, which can completely solve these problems and ensure the registration accuracy of leading-edge paper feeding

(II) paper powder removal device

the problem of paper powder has been puzzling the printing quality of corrugated boxes. The initial solution is to remove it by brush and dust suction, but the effect is not obvious. Too much main oil will cause the hydraulic oil to leak from the working cylinder port, which will be firmly attached to the cardboard because the dust has static electricity. Nowadays, models with high printing quality requirements are equipped with high-voltage discharge dust removal devices, which remove static electricity first and then dust to improve the dust removal effect

(III) the spring is easy to be ignored when using the paperboard transmission

the traditional printing machine uses the paper pulling ring to move the paperboard between the printing units. The paper pulling ring needs to adjust its position according to the width of the paperboard, and it must avoid the printing part to avoid scratching the ink. In addition, its periodic transmission action will affect the registration accuracy due to the different bending degree of the paperboard. Therefore, the Swiss boster company has developed a vacuum adsorption transmission system, which transports the paperboard in the form of vacuum adsorption and roller. The paperboard can be adsorbed on the machine and transported stably in the printing unit without periodic jumping between units, which greatly improves the accuracy of printing registration and does not need to adjust the position of the pull ring due to the replacement order

(IV) printing ink supply

system due to the successful introduction of ceramic textured rollers, now flexo printing machines can be equipped with single-chip scrapers, closed groove scrapers and other systems in addition to traditional rubber black guide rollers. In order to adapt to different ink volume and linear density required by different printing, the flexibility of the printing unit is very important. Some manufacturers consider that the printing unit is equipped with rubber ink guide rollers and closed slot scrapers to adapt to full page and even dot overprint. The French Martin company's fast replacement closed slot scraper system can also adapt to full page and dot printing with different scrapers. The Swiss boster company uses the electric replacement of the ceramic roller set device. Two to three sets of embossing rollers are configured in each printing unit, which can be replaced within one minute. It can adapt to a wider range of printing, and can print full page and dot overprint up to 120l/inch

(V) drying unit

in order to adapt to the increasing trend of carton printing color, there are more and more printing units with more than four colors. On this premise, drying device is necessary, which can improve printing quality and production speed. In addition, during line processing, the drying unit can isolate the printing and post-processing (slotted die-cutting) processes, so as to prevent dust from entering the printing unit and vibration from affecting the printing quality. The number and configuration of drying units depend on needs and budgets. Boster's model is designed for multicolor printing and edge glazing, so it is tenacious to configure hot air drying after each printing unit, and the last unit is equipped with UV drying device to coat UV oil

the above is only the improvement of cannon e-system equipment of corrugated paperboard flat sheet printing machine in Germany. There are other equipment that can be equipped to further improve the printing quality, such as independent motors of each unit, ink proximity and abnormal elimination devices, etc. Carton manufacturers should choose the most ideal equipment based on the market demand and investment budget. It can be predicted that the trend of multi-color and high-quality printing of cartons is inevitable

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