Preprint cutting solution

The structure of the pre-print cutting system is composed of a high-speed color tracking system and a high-precision computer cutting system. The cutting accuracy of the computerized cross cutting system must be guaranteed to be within 1mm, so as to ensure the high precision of the preprinted cutting paper. High-speed color tracking systems require fast response times and precise detection ranges. At present, the diameter of the detection point is (0.3mm~1mm), and the detection distance is (30mm~100mm). Moreover, the color mark detector can adapt to the environment of cardboard production workshop, and it can be waterproof, dustproof, collision-proof and high-temperature resistant.

First, printing of pre-printed color marks requires printing of color marks

The difference between the color of the color scale and the background color is distinct. The smaller the detection range of the color scale is, the more accurate the detection accuracy will be. However, if the color scale is too small, the sensing range of the color scale detector will become smaller. Therefore, the color standard printing requires that the color scale be fine, and at the same time, the minimum detection range of the detector should be ensured. If the length and width of the color scale is (20mm╳5mm), the range of the alignment is within 5mm. If the color scale can be printed smaller, such as 10mm╳2mm, the cutting accuracy can be increased to &1mm. In order to prevent the color mark from being printed too shortly, the left and right lateral movements in the cardboard production are beyond the detection range of the detector, resulting in a phenomenon that the color mark tracking system cannot sense, and it is necessary to add left and right automatic correcting devices on the color mark tracking system.

Second, the pre-print cutting preparation and process requirements

Because of the pre-printed pattern, it must be dried after the hot plate is hot and high pressure. In this process, in order to avoid damage to the printed pattern by the hot plate, special requirements must be made on the ink, that is, the ink used must be able to withstand high temperatures and have good wear resistance. In the printing process, the paper roll is in the form of front-end and back-end, and it is difficult for the paper roll to maintain the original roll paper strength before the paper is delivered, but the paper roll must also be neat and compact.

Third, the common problems in production

n The pre-printed face paper is not rewound due to uneven rolling, causing the cardboard face paper to wrinkle. The base paper is loose during the unwinding process, and the tension of the original paper holder is uniform. This results in no tension on the base paper. After the hot plate, the tissue will wrinkle. This problem can be solved if a tension equalizing device is added to the paper feed position.

n Pre-printed images appear to shrink after passing through the hot plate. The moisture content of the paper roll is heavy before printing. After printing, the water content will increase. After entering the hot plate, the water will evaporate. A shrinking phenomenon occurs, so the printed image will also become smaller. In order to reduce the moisture content of the base paper, the pre-printed base paper must be preheated.

n Preprinted cardboard often slips in the hot plate. Preprinted surface of paper is usually more smooth than the surface, and the ink will volatilize during preheating, so that the board will pass through the preheated plate. It is easy to bond with the hot plate surface, causing great resistance. Therefore, the ink must be of a high-temperature, high-speed type. In order to increase the coefficient of friction of the surface of the tissue, the coating oil must not be too thick. When the board first enters the hot plate, the pressure of the hot plate should not be adjusted too tightly, and the temperature of the hot plate should be lowered slowly when the board is completely in. If necessary, add a water spray device to the top of the cotton belt.

n The phenomenon of dip pits in the cut-off preprinted paperboard The pressure of the preprinted paperboard at the hot plate is not adjusted so much, so the phenomenon of swinging to the left or right appears after the paper is ejected, so that when the paper is cut at the cutter Deviations will occur. To eliminate this swing, you can add a pressure wheel or increase the longitudinal correction device at the paper exit.

Author / Deng Junbo

Source: Global corrugated box industry