Pre-print cutting in the common problems and solutions

The structure of the pre-print cutting system consists 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 within ±1 mm so as to ensure the high precision of the preprinted cutting. High-speed color tracking systems have a fast response speed and precise detection range. At present, the detection point diameter is 0.3mm-1mm, and the detection distance is 30mm-100mm. Moreover, the color mark detector can adapt to the environment of the paperboard production workshop, and can be waterproof, dustproof, collision-proof and high-temperature resistant. Now we will do a simple analysis of the problems that are likely to appear in preprinting and cutting.

Printing requirements of the color standard The color of the color target should have obvious color tone difference from the background color. The smaller the detection range of the color scale, the higher the detection accuracy. However, if the color scale is too small, the sensing range of the detector will be too small or unable to sense. Therefore, the fine printing of the color mark must be ensured within the minimum detection range allowed by the detector. If the length and width of the color mark is 20mm*5mm, the cutting range is within 5mm. If it is changed to 10mm*2mm, the cutting accuracy can be increased to ±1mm. In order to prevent the color mark from being printed too shortly, and the left and right lateral movements in the cardboard production are beyond the detection range, resulting in a phenomenon that the color mark tracking system cannot sense, it is necessary to increase the left and right automatic correcting devices.

Preprinted inks must be resistant to high temperatures and abrasion. Because the preprinted pattern is printed, it must be hot-pressed at a high temperature and pressure. Therefore, the ink used must be able to withstand high temperatures and have good abrasion resistance.

Pre-printed and unwrapped and wrinkled paper The base paper is unwinded, tightly and tightly, while the base paper holder is uniformly tensioned, and the paper is not taut. After entering the hot plate, it wrinkles. Adding a tension balance device to the base paper feed can solve the problem.

Image reduction after passing through the hot plate After the preprinted paper with a large moisture content passes through the hot plate, a phenomenon of shrinkage occurs due to moisture evaporation, and the preprinted pattern is also reduced. In order to reduce the moisture content of the raw paper, the raw paper before printing must be preheated.

Preprinted paper slips on a hot plate. Preprinted facestock is usually smooth and the ink is volatilized during heating. Therefore, the ink must be of high temperature and high speed, and the coating oil should not be too thick. Note that when the board first enters the hot plate, the hot plate pressure cannot be adjusted too tightly, and the temperature of the hot plate slowly decreases after the board has completely entered. If necessary, spray water mist on top of the cotton webbing.

Pre-printed paperboards with sloping cuts Pre-printed paperboards are not adjusted to a large pressure at the hotplates, so there will be wobble after the paper is ejected. This will make the paper cut off. The method to eliminate the swing is to add a pressure wheel to the paper exit to increase the longitudinal correction device.

Source: China Packaging News