We can often find a line (usually black) with a width of about 2 mm on a large-format cigarette package print sample, which is used for web rectification during the process of web gravure. Since the accuracy of cigarette pack registration is very strict, the paper edge positioning generally cannot meet the requirements. Whether it is gravure trimming or post-process web hot stamping or round die cutting, this thread is indispensable. The lateral positioning of the web is very important.
The distance between the correction line and the effective graphic is at least 3 mm, that is, there is no graphic information within 3 mm. In addition, at least 2mm of blank space should be reserved on the outside of the correction wire, and the layout should be kept clean, that is, the gold and silver cardboard should not be able to have aluminum and defects. Relative to the horizontal positioning of the scanning triangle MARK, the correction line will increase the width of the paper of 7mm by the cigarette printing enterprise, and the size of the conventional GDX2 cigarette packet box is 3, and the horizontal direction of the cigarette case is 3, and the horizontal displacement of the box is 2 If the width of the paper is 730 ~ 735mm, the paper width should be increased by about 1%. If the cigarette printing enterprise has a large business volume and the paper used is a roll of gold and silver cardboard, the paper usage will increase greatly in one year, and the added cost is also very considerable.
However, the author recently found that this correction line is not indispensable, because the correction device that comes with the gravure printing device actually has many optional functions. We can analyze it according to the content of the layout and make a reasonable choice.
Here is a brief introduction to the corrector. Gravure printing equipment generally uses imported corrector. Common brands include FIFE in the United States, E+L and BST in Germany. In the case of the commonly used FIFE CDP-01, there are a variety of scanning positioning correction methods to choose from.
Option 1 : Scan the edge of the patch. Generally, the color blocks with darker colors are selected, and the color blocks are required to be at least 2 mm wide in the paper feeding direction, and the regions are evenly arranged without interruption.
Option 2 : Scan line positioning. This line is the correction line mentioned above, the line width is 1 ~ 2.5mm, can not be too wide, need to give the electric eye halo (usually about 4mm diameter) on the hair detector to leave a certain room. This method is called lateral correction line scanning positioning.
Option 3 : Scan the printed color block for broken edges. That is to say, the scanned color patches are discontinuous and intermittent, but it is still required that the color blocks are evenly neatly arranged in the direction of the paper feed at least 2 mm wide, and no discontinuity occurs.
Option 4 : Scan the printed dashed line. However, the dotted line is not available for all cigarette packets. If so, this method can be used, but note that the line width should be 1 to 2.5 mm.
In addition, the FIFE CDP-01 corrector has some other corrective positioning functions, such as paper-scanning edge, center positioning, etc., which are generally used in the field of flexible packaging and gravure printing, and will not be described here.
It can be seen that it is not only the lines that can correct the positioning, but it should be noted that when the color block is broken or broken, the correction function is turned off in the broken area, so the proportion of the broken area should be as small as possible. When the running speed of the equipment reaches 150m/min or even higher, the broken area will not affect the deviation of the web, and the precision of less than 1mm can be achieved.
Since the gravure cigarette packets are generally repeated by a plurality of units (repeated cigarette boxes or regularly changing color blocks) and there are many solid color blocks, the above-mentioned color block broken edge or broken line scanning positioning function can fully meet the requirements. Take a brand cigarette case as an example, because the domestic conventional GDX2 cigarette case is generally horizontally inserted typesetting, and the middle is a single knife, in order to ensure the integrity of the cigarette package, a line color block with a width of about 3 mm should be designed on one side of the large layout. (Figure 1), and is a multi-cell repetition, this line color block can be used for color block edge scanning and positioning correction.
The strip box may not have this regular broken line, but according to the above idea, some color blocks may be added in the waste side area of ​​the large layout of the strip box to create a break point color block parallel to the paper edge for the rectification scan.
Of course, some cigarette packs do not have solid color blocks, so it is a different matter. In short, the peers need to analyze the specific conditions of the web when they are doing gravure printing. In addition, different brands of correctors, their functions are not the same, but as long as we diligently think about, combined with the layout elements of cigarette packets, we will be able to find the most economical typesetting and avoid waste.
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