Corrugated flat sheet flexo technology

After more than 30 years of research and improvement and strong market demand, corrugated flat sheet presses have made considerable progress. Problems such as unstable paper feeding, large registration errors, difficulties in tuning, ink scraping and dust, etc. have been greatly improved. The degree of improvement can be analyzed by the structure of the following groups of units:
(1) Feeding section The traditional paper feeding unit is a push-back type, which often cannot be fed due to the paperboard bending, and the paper feed cannot guarantee the positioning of the paper board and thus cause the registration error. After improving the vacuum adsorption for a small area of ​​the adsorption plate or roller, the above disadvantages can be improved, but the large area of ​​the cardboard may still cause deviations due to insufficient contact area. French company Martin developed a large-area suction contact vacuum suction belt feeding system for these shortcomings, which can completely solve these problems and ensure the registration accuracy of the leading edge feed.
(2) The problem of paper powder removing device paper powder has always troubled the printing quality of corrugated boxes. The initial solution was to remove them by brushing and vacuuming, but the effect was not obvious, mainly because the dust was electrostatically attached to the cardboard. . Nowadays, the higher printing quality requirements are all equipped with high-voltage discharge dust removal devices, which first remove the static electricity and then vacuum to improve the dust removal effect.
(3) Cardboard transport Conventional printing machines run cardboard in the printing unit to pull the paper ring. Pull the paper ring to adjust the position according to the width of the paper board, and must avoid the printing part to avoid scratching ink. In addition, the staged transfer action will affect the accuracy of registration due to the different degree of paperboard bending. BOBST developed the vacuum adsorption transfer system to transport the paperboard by means of vacuum adsorption and roller. The paperboard can be sucked into the machine and transferred to the printing unit stably. There is no periodic beating between the units, which greatly improves the Print registration accuracy, and no need to adjust the position of the draw ring for changing orders.
(D) Printing ink supply system Due to the successful launch of ceramic anilox roll, flexo printing presses can now be used with single-blade squeegee, closed-slot squeegee and other systems in addition to traditional rubber guide rollers. In order to adapt to different printing needs different ink amount and network line density, the flexibility of printing unit is very important. Some manufacturers consider the printing unit to be equipped with a rubber ink roller and a closed groove scraper to accommodate full plates and overprints. The French company Martin's rapid replacement of closed slotted blade systems, with different scrapers can also adapt to full version and dot printing. Swiss Bobst company is an electric replacement ceramic net roller unit. It can be replaced in one minute by arranging two to three sets of anilox roller in each printing unit. It can adapt to a wider range of printing, printing full version and up to 120L/inch network overprint.
(5) Drying units In order to adapt to the increasing trend of carton printing, more and more four-color or more printing units are now available. Under this premise, drying units are necessary, one can improve the printing quality, and the second can increase production. speed. In addition, during the connection process, the drying unit can isolate the printing and post-processing (grooving die cutting) process, so as not to affect the printing quality when the dust enters the printing unit and the vibration. The quantity and configuration of the drying unit depend on the need and budget. . Bobst's models are designed for multi-color printing and side-by-side lighting, so hot air drying is applied after each printing unit, and the last unit is equipped with a UV drying unit to coat UV oil.
The above is only a basic improvement of the corrugated sheetfed printing press. There are other devices that can be used to further improve the printing quality, such as independent motors for each unit, proximity and exclusion devices for ink. Carton manufacturers should choose the best equipment for their investment budget based on the market demand. It can be foreseen that the trend of multi-color and high-quality printing of cartons is unavoidable.