The best way to install the ink scraper of gravure

2022-10-24
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How to install the ink scraper of gravure machine is the best method

the selection, installation and adjustment of the doctor blade in gravure printing have an important impact on the quality of the printed matter. Here are some views on the application of doctor blade in gravure printing and some problems involved

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I. selection and installation of doctor blade

high speed gravure printing machine. Generally, imported steel doctor blade with high elasticity is selected, and its thickness is 150 ~ 180 M

when installing the doctor blade, pay attention that both sides of the doctor blade should be 10 ~ 20mm longer than the printing plate to prevent the printing plate ink from splashing on the rubber roller. The steps and key points are as follows:

1 The distance between the lining and the knife back is about 10mm. The distance between the lining and the blade is 5 ~ 7mm. However, the distance can also be appropriately increased (that is, installed as a soft blade) or reduced (installed as a hard blade) according to the specific situation

2. Put the new blade behind the lining, install it into the knife slot, and tighten the back screw. First tighten it from the middle of the blade, then gradually outward, and tighten it on both sides in turn. Here is a trick to avoid blade warping: when tightening the screw, it should be completed twice or three times, and it cannot be achieved in one step. While screwing the screw, hold a piece of rag to clamp the blade and lining and pull it to one side with force, so that the installed knife is flat. A flat blade can ensure a uniform amount of printing plate ink

3. Choose suitable sharpening tools and methods

when sharpening knives with stone, if the oilstone is rough, it is not suitable for sharpening new knives. According to practical experience, it is more appropriate to grind the knife with No. 1 emery paper, which can grind both new blades and old blades with large defects. It is OK to grind a new knife with 0 steel sandpaper, but it is difficult to grind an old knife with a slightly larger notch. If you sometimes feel that grinding the blade with No. 1 emery paper is rough, you can use No. 0 emery paper to grind it slightly. There are generally two ways to sharpen the knife: one is to fold the sandpaper into a V shape, but pay attention to folding several layers of sandpaper to avoid cutting through the sandpaper and hurting your hands. This method is more efficient and easy to control the angle of the cutting edge, but it is not very safe; The other is to grind the knife by pulling both ends of the sandpaper with two hands, which is very safe, but the angle of the blade is not easy to control. Too blunt and too sharp blades have a negative impact on the printing quality

second, reasonably adjust the pressure and sharpness of the doctor blade, which determines the quality of his good deeds. The contact position has an impact on the printing quality. According to the actual needs, reasonable adjustment of these factors can solve many problems in printing

1. Pressure ADL doctor blade imported from Japan, ADL ink doctor blade customer feedback | doctor blade direct | doctor blade | ink doctor blade | Swedish doctor blade

the factors affecting the pressure of the doctor blade are the size of cylinder pressure, the difference between hard and soft blades, the angle of intersection between the doctor blade and the printing plate, etc. the greater the inclination, the greater the pressure. Excessive pressure will reduce the transfer rate of ink and cause greater wear to the printing plate and blade; Too little pressure is prone to dirty version or scraper line

2. Sharpness of the knife

the sharpness of the knife depends on whether it is new, the blade angle when sharpening, the model of sandpaper (oilstone) used, etc. The suitable sharpness of the knife should be that it can effectively scrape the ink without producing knife threads. Too sharp scrapers are often prone to produce traces of knife threads and wear plates at the same time

3. The distance between the doctor blade and the printing plate

the reduction of the distance between the doctor blade and the printing plate is conducive to improving the ink transfer rate, but it is easy to produce dirty plates; On the contrary, it can effectively solve the dirty version and avoid some small line marks, but it will reduce the ink transfer, such as σ 0.001、 σ 0.01、 σ 0.1 and σ The competitiveness of markets such as 0.3 will also be further improved

4. The flatness of the knife

the flatness and warpage of the knife mainly depend on the installation method. Of course, it may also be related to the foreign matters stuck in the knife rest groove or on the blade and lining. When the flatness of the knife is poor, there will be some bead like marks on the edge of the printing surface, or intermittent line marks from time to time. Some people think that the above phenomenon occurs only when the ink is rough and the ink fluidity is not good. In fact, this situation also occurs when the knife is uneven

5. The movement of the doctor blade

the left and right movement of the doctor blade plays an important role in reducing the scraper line, improving the utilization rate of the doctor blade, and reducing the wear of the plate. If the doctor blade moves abnormally, find a way to improve it

when there are line marks in printing, one is to cause plate damage, and the other is that the scraper is not sharp. However, another reason is that there is a foreign object sticking behind the blade. The solution is to move the doctor blade up and down in order to get rid of the adhesive. If you can't get rid of it, you can only stop and wipe the doctor blade

there is also a 2016 China Nanjing new materials capital technology summit with the theme of "development and innovation", which is difficult to hold. The topic is related to the scraper, and many people misunderstand it is caused by ink. This means that sometimes there are dozens of irregular line marks of different lengths, which look like a stack of ink. It is different from the scraper line, which is not continuous, but sometimes absent, or only 1/2 or 1/3 parts appear in the printing eloquence, which is actually caused by the pressure of the scraper is too small or the scraper is not sharp enough

the above several indicators of scraper have both differences and similarities. When solving specific problems, one of them can be used, and sometimes it needs comprehensive application to completely solve the problem. For example, when there are some intermittent ink lines, it can be solved either by increasing the pressure or by sharpening the knife; When there is a dirty version that is severely punished, several aspects need to be combined and used; First, use a sharp blade, second, increase the pressure, and third, increase the distance between the scraper and the contact side

when the scraper is seriously worn and cannot be polished with sandpaper and oilstone, it can be polished with a special grinder, which can be reused for several times, greatly reducing the cost of the scraper

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