With a 0.1mm thick gauge, stuff it in at the point of contact. The kraft paper can also be cut into strips of 60-80mm, placed on the contact points, and the length of the anilox rolls is 4 to 6 for long and 3 for short. Adjusting the ink fountain roller to the kraft paper can be pulled under relatively tight conditions. If it is easy to pull it up or it is easy to insert the thick gauge into it, there is a gap between the two, which is abnormal.
The ink fountain roller and metal anilox roller must work under contact. At present, some companies use high-quality anilox roller lines for printing, reaching 180 lines/inch or 250 lines/inch. When printing color blocks and large letters, the amount of ink is not enough, so operators often use ink rollers to increase ink fountains. Roller and anilox roller gap method to increase ink supply. However, as long as there is a gap between the ink fountain roller and the metal anilox roller, the effect of the quantitative supply of ink by the metal anilox roller is lost. Therefore, the use of metal anilox roller must have a "quantitative" concept of ink supply, can not use the gap to adjust the amount of ink, there is a gap in the control of the ink is not good, the actual print is not flat, there will be corduroy-like streak; cable version Color differences will occur. If the ink fountain roller and the metal anilox roller are under normal contact, the ink on the metal anilox roller net wall still cannot be squeezed out, indicating that the viscosity of the ink is too high, the viscosity of the ink should be adjusted, and the ink roller and metal mesh should be enlarged. The pressure between the rollers is of no avail.
2. Control the contact pressure between the metal anilox roller and the plate cylinder The contact pressure between the metal anilox roller and the plate cylinder should be light. It can be seen from Fig. 13 that the anilox roller transfers ink to the printing plate, and the printing plate can be printed after receiving the ink. If the printing plate is out of contact with the printing plate, the printing plate cannot obtain ink and printing cannot be performed. How should the anilox roll be in contact with the printing plate to be optimal and meet the light pressure requirements? Referring to Fig. 13, the plate is mounted on the surface of the plate cylinder. The thickness of the plate is known. For example, the plate thickness is 3.94mm, the lining thickness is 3.05mm, the double-sided tape is 0.11mm, and the hanging polyester is 0.10mm. The total thickness is 7.20 mm. According to the requirement of lighter pressure, it is better that the two rollers are in tangential contact, that is, the distance between the metal anilox roller and the plate cylinder is kept at 7.20mm, but in reality, the anilox roller, the plate, and the roller have a positional error. The tangential state is impossible. After testing the anilox roll misalignment and diameter jump 0.02 ~ 0.04mm, plate roller diameter jump 0.01 ~ 0.02mm, plate thickness error is ± 0.02mm, the maximum error is 0.08mm, plus 0.02mm printing pressure The total amount is 0.1mm. As long as the anilox roller is fully accessible to the printing plate, the ink in the anilox roller can be transferred to the printing plate, and the requirements for ink transfer are achieved. Therefore, with a 6mm feeler gauge and thickness gauge, the distance between the anilox roller and the plate cylinder is 7.10mm, which can meet the pressure requirements.
Now most printing companies in the corrugated box printing process, the printing pressure greatly exceeds 0.1mm. In fact, the pressure is too great, not only affects the service life of the printing plate, but also is very unfavorable to improving the printing quality. As shown in Fig. 14a, the anilox roller is in contact with the plate, and the plate is deformed to meet the light pressure requirement. In FIG. 14b, due to the excessive pressure, the anilox roller contacts the side of the printing plate at the time of printing, and the printing plate is compressed after being deformed. Thus, a hard mouth (wild ink) appears at the front end of the printing pattern and text, and the burr is serious. At present, quality issues in this area can be observed on many prints. When printing the cable version, the pressure is too large to produce a paste, so the contact pressure must be light. Generally, the pressure should be controlled at 0.1mm, and the user still has to be flexible in actual operation depending on the actual situation. If the precision of the machine is poor, the pressure may be appropriately increased; otherwise, the pressure may be reduced.
3. To control the pressure between the plate cylinder and the impression cylinder Theoretically speaking, the contact pressure between the plate cylinder and the impression cylinder should be light, but in fact this is not easy to do in the printing of corrugated boxes, but The concept of "lightness" must be established in the minds of operators and efforts must be made to achieve light pressure. Referring again to FIG. 13, the distance between the plate cylinder and the impression cylinder is the total thickness of the plate plus the thickness of the corrugated cardboard. The total thickness of the plate can be controlled as described above, but the thickness of the corrugated cardboard is difficult to control, so the corrugated box is The printing quality is closely related to the thickness error and flatness of the corrugated board itself. Corrugated paper is the worst among printing substrates. Not only does the thickness of one sheet of cardboard vary greatly, but the thickness and the level of corrugation of the same sheet of paper also have a large error. When printing, it is necessary to meet the thickness requirements of all corrugated boards to achieve good results. Quality is hard to control.
How to control the gap between the plate cylinder and the impression cylinder?
Clearance = total plate thickness + corrugated board thickness - 0.5-0.1
0.5 in the formula is the measured amount of corrugated board thickness error, 0.1 is the aforementioned error amount of the drum and the plate, which is 0.6 (0.5 + 0.1) mm is based on the quality of corrugated cardboard and other errors to control India The reasonable amount of compression. The feeler and gauge are used to control the gap between the plate cylinder and the impression cylinder. Within this control range, it is already possible to ensure that the inked portion of the corrugated paper is completely printed out. However, due to the thickness error of corrugated paper, when printing thick corrugated cardboard, the large amount of compression of the printing plate will be detrimental to improving the printing quality. Therefore, to ensure the printing quality, the quality of the corrugated cardboard should be improved as much as possible to reduce the thickness error. If you do not control the operation, there will be a serious hard-to-mouth pressure, overprinted on the ground, ink ink part of the line is light, non-inking edges appear hard and ink is dark. Excessive pressure on the printed cable version will cause the network to enlarge the paste, and three or four percent of the network have hollow dots.
The above is a three-point pressure control problem. The pressure control is reasonable and the printing quality is good.
In addition, if the phenomenon of partial printing cannot be seen during the printing test of the school, it is better not to adopt a method of increasing the pressure, because although this can temporarily solve the problem of partial printing, it will cause most of the imprints to be deformed. , not worth the candle. The correct approach should be to use the pad version of the method to solve, that is, according to the actual situation in the hanging film behind the paper. Corrugated carton printing generally sticks the plate to the hanging plate film, so the platen is very convenient, especially much more convenient than the narrow-width unit type flexographic printing machine.
In addition, pay attention to the cleaning of the plate cylinder and the impression cylinder. The surface of the cylinder is glued with a single-sided adhesive, paper, ink, etc., all of which affect the printing pressure and affect the quality of the printed product.
The ink fountain roller and metal anilox roller must work under contact. At present, some companies use high-quality anilox roller lines for printing, reaching 180 lines/inch or 250 lines/inch. When printing color blocks and large letters, the amount of ink is not enough, so operators often use ink rollers to increase ink fountains. Roller and anilox roller gap method to increase ink supply. However, as long as there is a gap between the ink fountain roller and the metal anilox roller, the effect of the quantitative supply of ink by the metal anilox roller is lost. Therefore, the use of metal anilox roller must have a "quantitative" concept of ink supply, can not use the gap to adjust the amount of ink, there is a gap in the control of the ink is not good, the actual print is not flat, there will be corduroy-like streak; cable version Color differences will occur. If the ink fountain roller and the metal anilox roller are under normal contact, the ink on the metal anilox roller net wall still cannot be squeezed out, indicating that the viscosity of the ink is too high, the viscosity of the ink should be adjusted, and the ink roller and metal mesh should be enlarged. The pressure between the rollers is of no avail.
2. Control the contact pressure between the metal anilox roller and the plate cylinder The contact pressure between the metal anilox roller and the plate cylinder should be light. It can be seen from Fig. 13 that the anilox roller transfers ink to the printing plate, and the printing plate can be printed after receiving the ink. If the printing plate is out of contact with the printing plate, the printing plate cannot obtain ink and printing cannot be performed. How should the anilox roll be in contact with the printing plate to be optimal and meet the light pressure requirements? Referring to Fig. 13, the plate is mounted on the surface of the plate cylinder. The thickness of the plate is known. For example, the plate thickness is 3.94mm, the lining thickness is 3.05mm, the double-sided tape is 0.11mm, and the hanging polyester is 0.10mm. The total thickness is 7.20 mm. According to the requirement of lighter pressure, it is better that the two rollers are in tangential contact, that is, the distance between the metal anilox roller and the plate cylinder is kept at 7.20mm, but in reality, the anilox roller, the plate, and the roller have a positional error. The tangential state is impossible. After testing the anilox roll misalignment and diameter jump 0.02 ~ 0.04mm, plate roller diameter jump 0.01 ~ 0.02mm, plate thickness error is ± 0.02mm, the maximum error is 0.08mm, plus 0.02mm printing pressure The total amount is 0.1mm. As long as the anilox roller is fully accessible to the printing plate, the ink in the anilox roller can be transferred to the printing plate, and the requirements for ink transfer are achieved. Therefore, with a 6mm feeler gauge and thickness gauge, the distance between the anilox roller and the plate cylinder is 7.10mm, which can meet the pressure requirements.
Now most printing companies in the corrugated box printing process, the printing pressure greatly exceeds 0.1mm. In fact, the pressure is too great, not only affects the service life of the printing plate, but also is very unfavorable to improving the printing quality. As shown in Fig. 14a, the anilox roller is in contact with the plate, and the plate is deformed to meet the light pressure requirement. In FIG. 14b, due to the excessive pressure, the anilox roller contacts the side of the printing plate at the time of printing, and the printing plate is compressed after being deformed. Thus, a hard mouth (wild ink) appears at the front end of the printing pattern and text, and the burr is serious. At present, quality issues in this area can be observed on many prints. When printing the cable version, the pressure is too large to produce a paste, so the contact pressure must be light. Generally, the pressure should be controlled at 0.1mm, and the user still has to be flexible in actual operation depending on the actual situation. If the precision of the machine is poor, the pressure may be appropriately increased; otherwise, the pressure may be reduced.
3. To control the pressure between the plate cylinder and the impression cylinder Theoretically speaking, the contact pressure between the plate cylinder and the impression cylinder should be light, but in fact this is not easy to do in the printing of corrugated boxes, but The concept of "lightness" must be established in the minds of operators and efforts must be made to achieve light pressure. Referring again to FIG. 13, the distance between the plate cylinder and the impression cylinder is the total thickness of the plate plus the thickness of the corrugated cardboard. The total thickness of the plate can be controlled as described above, but the thickness of the corrugated cardboard is difficult to control, so the corrugated box is The printing quality is closely related to the thickness error and flatness of the corrugated board itself. Corrugated paper is the worst among printing substrates. Not only does the thickness of one sheet of cardboard vary greatly, but the thickness and the level of corrugation of the same sheet of paper also have a large error. When printing, it is necessary to meet the thickness requirements of all corrugated boards to achieve good results. Quality is hard to control.
How to control the gap between the plate cylinder and the impression cylinder?
Clearance = total plate thickness + corrugated board thickness - 0.5-0.1
0.5 in the formula is the measured amount of corrugated board thickness error, 0.1 is the aforementioned error amount of the drum and the plate, which is 0.6 (0.5 + 0.1) mm is based on the quality of corrugated cardboard and other errors to control India The reasonable amount of compression. The feeler and gauge are used to control the gap between the plate cylinder and the impression cylinder. Within this control range, it is already possible to ensure that the inked portion of the corrugated paper is completely printed out. However, due to the thickness error of corrugated paper, when printing thick corrugated cardboard, the large amount of compression of the printing plate will be detrimental to improving the printing quality. Therefore, to ensure the printing quality, the quality of the corrugated cardboard should be improved as much as possible to reduce the thickness error. If you do not control the operation, there will be a serious hard-to-mouth pressure, overprinted on the ground, ink ink part of the line is light, non-inking edges appear hard and ink is dark. Excessive pressure on the printed cable version will cause the network to enlarge the paste, and three or four percent of the network have hollow dots.
The above is a three-point pressure control problem. The pressure control is reasonable and the printing quality is good.
In addition, if the phenomenon of partial printing cannot be seen during the printing test of the school, it is better not to adopt a method of increasing the pressure, because although this can temporarily solve the problem of partial printing, it will cause most of the imprints to be deformed. , not worth the candle. The correct approach should be to use the pad version of the method to solve, that is, according to the actual situation in the hanging film behind the paper. Corrugated carton printing generally sticks the plate to the hanging plate film, so the platen is very convenient, especially much more convenient than the narrow-width unit type flexographic printing machine.
In addition, pay attention to the cleaning of the plate cylinder and the impression cylinder. The surface of the cylinder is glued with a single-sided adhesive, paper, ink, etc., all of which affect the printing pressure and affect the quality of the printed product.
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