In the printing process, the ink scraper blade is an important part of determining the quality of printed matter, involving the printing ink color saturation and printing can be used normally. Under normal circumstances, the three factors affect the quality of printed materials, respectively, the location of the ink scraper, ink scraper distance and the length of the ink scraper by the pressure.
First, the ink scraper installation location
When installing a squeegee, it is often supported by a sub-blade. Vice blade generally made of hard steel, the choice of China's blade lining thickness generally 120mm ~ 150mm. Scraper blade is often clamped in its center, the general knife from the hard steel sheet about 8mm, hard steel from the squeegee blade is about 7mm or so, the specific size through the use of the effect to determine, fasten the blade commonly used 8 # nut to fast , The squeegee blade should be larger than the plate version of the roll. Before installation, whether it is a new blade or the old blade, the blade edge should be grinding, requiring no gap, no burr, edge angle should be inclined 25 °. We often use the method is to first add a few drops of oil to the oil and coarse grinding, and then with 1000 # water-resistant cloth and then add a few drops of oil and then fine grinding, add a few drops of oil is the purpose of lubrication, reduce friction, so After grinding the doctor blade effect is generally good. Scraper blade installed too prominent, scraper easily deformed, was wavy, in high-speed printing, some places clean, and some are scraping clean, there are traces, will affect the printing quality, and will be lost. Scraper installation is too short, and the lack of flexibility should be, to increase the pressure to clean the surface without a page of ink, and easy to hurt the plate, shorten its life. So the installation is appropriate is very critical, which depends on the size of the plate, the length of the actual adjustment to do. The position of the squeegee is the distance from the blade edge of the doctor blade to the point of contact of the plate roll to the embossing roll.
Second, the length of ink scraper distance
Often scraper blades are equipped with adjustment nuts, which are adjusted up and down and forward and backward. Most gravure machines are such structures. If the adjustment is not so that the printed matter is not glossy, there are dry version, blocking version, no color, virtual edge, poor hardness and other phenomena, and ink evaporation rate is adjusted according to the speed of the press, so scraping knife The distance is adjusted according to the speed of the press. Under normal circumstances, the plate diameter around R15, machine speed of about 60m / min when the squeegee and embossed roller distance of 6cm. Printing speed, the distance is better, the printing speed is slow, the squeegee knife and the embossing roller distance is very good; speed fast scraping, knife too close, the distance may be high speed under the blade under the blade Splash out and cause waste, which must be noted.
Third, the ink squeegee blade pressure
In the gravure printing press generally have to give some pressure on the squeegee, because after the pressure of the squeegee knife through the ink layer, so that the squeegee and the plate roller contact, scraping the excess ink. The size of the pressure can be adjusted according to the depth of the plate and the level of the picture. Of course, too much pressure is easy to screen the ink is too clean and the printing is not up, too light pressure will produce printing tail and other failures. To solve its approach is appropriate to the edge of the blade that is linked with the printing plate interface can be resolved, the hair can be provided with a special version of the fan. The pressure is too large will change the contact angle becomes smaller, it is difficult to scratch the ink caused by the blade under the blade accumulation and produce knife line. So the scraper left and right swing, the purpose is to reduce friction, reduce the friction plate, while avoiding the accumulation of ink under the ink knife, so no knife line. Under normal circumstances, good working conditions in the scraping system, the contact angle of about 60 ° is more appropriate.
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