Corrugated box gravure preprinting technology innovation II

  Fourth, the pre-printed carton production equipment and process characteristics
The main equipment for preprinting cartons is a large-sized group-type gravure printing press. The auxiliary equipment is a corrugated paper production line controlled by a computer. The pre-printed face paper is placed on the noodle station of the corrugated board line, and after sizing, veneering, flattening, drying, cutting and other processes, the colored cardboard is finally made, and the post-passage is obtained through die-cutting, sticking, and the like. The production process completes the production of the carton.

The important configuration of the gravure printing carton preprinting production line is the computer cross cutting of the corrugated cardboard production line, that is, a crosscutting control function must be installed on the cross cutting knife of the corrugated board production line. Its main control principle is to identify the corrugated cardboard by the photoelectric eyes. The cross-cut logo on the printed pattern transmits the time when the cross-cut mark reaches the photo-electric eye to the control computer, and then the control computer controls the cross-cutting time, thereby accurately cutting the corrugated cardboard at the border of the pattern. At present, cross-cutting machine manufacturers at home and abroad can install this function for the carton factory, and the cross-cutting accuracy can be controlled within 0.5mm. At present, China's current production of corrugated board production lines can be installed according to customer requirements computer cross-cutting device.

The ink used in the preprinted gravure printing machine is mainly based on alcohol-soluble inks or water-based paper-specific gravure inks. When the preprinted tissue paper is flattened and dried in the corrugated paper production line, the used ink must have good high temperature and friction resistance so as to meet the requirements of handling and stacking of the cardboard box manufacturer. Otherwise, the color surface will be pulled. Flower or mop.

The preprinted plate is made of steel chrome-plated electric gravure, and the number of gravure lines can reach more than 300 lines. It can be completely suitable for dot-printing and dot-tone printing of the ground printing and tone transition, but the gravure of paper printing is more intaglio than the general plastic printing. During carving, the deeper carving of the net holes can be used. The glazing roller can use a fixed number of wire rollers and uses a shaftless transmission.

Figure 5: Cartridge gravure pre-printed cell structure and color forming principle

The preprinted intaglio printing material must use coated white paper with good surface smoothness, strong print adaptability, and stable moisture content (6% to 7%). Imported coated cattle card and domestic gray board can meet the high-end color corrugated cardboard paper distribution requirements.

Fifth, the problem of preprinted paper and solutions
Many types of paper, such as coated paper, semi-coated and uncoated paper, Kraft board or test paperboard, can be used for preprinting or postpress printing. Paper with good printability will absorb the proper amount of ink in place and will not negatively affect its dryness. The paper can also exhibit desirable print smoothness, ink permeability, proper optical density, and good rheology (compressibility and elasticity). It should also have sufficient surface tension to prevent fluffing or linting, as well as good dimensional stability to prevent severe deformation in humid air. The surface of the paper should not be separated from the particles to avoid the generation of static electricity, which has negative consequences for the printing process.

Due to the current processing accuracy of the domestic gravure preprinting machine, some common problems are exposed in the production process of the carton factory:

Wrinkles: When the pre-printed paper roll tension is about 50kg, and the uneven moisture and thickness are not uniform, a larger tension change will cause the paper to swing laterally and form a wrinkle on the printed surface. The preheating device of the paper concave machine can help reduce the tension change caused by moisture loss (when the moisture content is too low, install the humidifier); if you add a flattening roller, you can help the paper roll as far as possible The swing is reduced.

Ink pull flower: Gravure printing machine adds air-cushion heating plate heat conduction control system, its process is to set up the air spray channel at the gap between the heating plate and the paper board, which can spray air in an instant to form a gas film to hold the paper board, avoiding The paperboard is heated and pressed to produce scratches, ink and other defects.

Lubai: Mainly because of the dust on the surface of the paper roll and the blockage caused by the ink, the dust and explosion-proof electrostatic ink-absorbing devices installed in the field printing group can respectively blow dust, improve the ink repellent effect, and reduce dot loss.

Spiral winding: Prepress gravure printing presses should use a closed-loop control system to ensure tension taper control.

Figure 6: Corrugated carton gravure printed electronic engraving gravure production

Incomplete edges: The edges of the cross section are not aligned, and the backup roller (receiving rubber roller) can be added to remove air from the paper roll and eliminate static electricity on the surface. Swing sideways. With the installation of Power Load Control (PLC), the computer's corrective device helps alleviate uneven edges and another solution to the problem of missing edges is offline rewind.

Roll overlap: If the roll is improperly overlapped during printing, it will cause downtime and affect the consistency of the printed product. Zero-speed docking can be used to pick up paper without interrupting the printing process.
(to be continued)