Offset "Sanping" is an important work in offset printing, and it is the basic requirement for the operation of offset printing, and it is also one of the keys to achieve ink-water balance. Only by doing a good job of offset printing "Sanping" will the quality of offset printing products have a basic guarantee. Especially the newly introduced used offset presses should do this work. The author here talks about some of the experiences in the work and aims to throw in jade.
The so-called offset printing "Sanping" refers to the offset of the offset printing machine. Ink rollers and flat rollers (print plate, eraser, impression cylinder) are flat, the pressure is balanced and correct, and the ideal printing effect is achieved.
Water roller flat Water roller flat water roller should be straight, the surface should be flat, water roller pressure should be correct and uniform, not too large nor too small. If the water roller is not leveled, the pressure between it and the string, the water roller and the printing plate will be uneven, resulting in the layout water is too large, too small or uneven water coating, affecting the ink and water balance; resulting in water roller and plate The partial pressure between the roller and the water roller is too large or too small, causing it to run unsteadily and accelerating the wear of the printing plate. To do a good job of water leveling, pay attention to the following points:
1. Pay attention to check the parallelism of the water roller, whether the water roller is bent or deformed. If it is a water roller, the rubber core of the water roller must be straight and the surface must be flat.
2. Water roller velvet should be well-jacketed, sew well, and sew firmly. It is necessary to check whether the surface of the water roller velvet is flat and tight or not, and relaxation is not allowed. After the water roller wadding is wrapped, it cannot be installed immediately. It should be scrubbed twice with a dampening solution and then fully wetted before installation.
3. Correctly adjust the pressure of the water roller to make it left and right. The pressure on the right three points is uniform. First adjust the pressure between the water roll and the string water roll, and then adjust the pressure between the water roll and the plate, and then repeatedly measure the left side of the water roll through the paper strip pull test. The pressure of the middle and the right three points makes the pressures of all points basically uniform. Specific approach: Select 2-3 pieces of kraft paper with straight thread and cut 40cra. A paper strip with a width of about 2 cm and a thickness of 0.1-0.1 mm is placed between the water roller and the string of water rollers or the printing plate respectively. After closing the water roller, the paper strip is pulled and the hand wheel and knob are adjusted. To make it reach the tension of the paper tension, the paper can be pulled out without breaking.
4. Keep the fountain roller. String water roller cleaner. When the work is completed or off work, the water roller must be thoroughly cleaned. From the middle, the cleaning must start from the middle. Both ends must be scraped and washed. After the scraping, the counterclockwise hand should be used to flatten it; when it is on the job, the water should be leveled first. Roll, carefully rub both ends and in the middle.
5. Pay attention to checking the bearing of the water roller. This is important, but it is easily overlooked. The bearing gap is small, the error is small, the rotation can be stable, and there will be no beating. If the bearing has worn out beyond the error range, the rotation will not be smooth, affecting the water transfer. At this time the water roller can no longer meet the use requirements, should be replaced in a timely manner, and installation should also be careful not to exceed the error range. If possible, ball bearings or roller bearings should be used as little or as little as possible.
The ink roller flat ink roller flat requires the ink roller to be flat and the surface is smooth. When running, the surface run-out should not be more than 0.05mm. The ink roller pressure must also be correct and uniform, and the surface performance of the ink roller should be good. Ink performance, so as to ensure the uniform transmission of ink. stable. To do a good job of the ink roller work, we must pay attention to the following points:
1. The core of the ink roller should be flat and the surface should be flat. The surface run-out should be kept within 0.05mm, and the maximum should not exceed 0.1mm. Otherwise, the jump amplitude is too large and will directly affect the uniformity of ink transfer.
2. The method of adjusting the pressure of the ink roller is similar to that of the water roller, and it is also necessary to pay attention to measuring and adjusting the left. In the middle, the right three points make the pressure uniform. It is best to use a paper strip pull test to adjust, and then use the steel test method to adjust. The specific operation method is similar to the paper strip pull test method. That is, the steel sheet is inserted and pulled out at a corresponding position, and the strength can be moderate according to experience. Generally, the thickness of the steel sheet is between 0.15-0.2 mm. Finally, the method of pressing the ink bar is also used for testing. Since most of the current prints are mainly printed on high-line screen dots, the general width of the ink bars can be about 3 mm.
3. Bearings should be kept good. If the wear is serious and the clearance has exceeded the error range, it should be replaced in time to ensure smooth transmission and uniform ink transfer.
4. The problem of cleaning the ink roller is also very important. When the work is completed or after work, it is necessary to thoroughly clean the ink and ink marks on all the ink rollers. In addition to scraping the clean ink, it is necessary to spray gasoline on the ink roller near the ink fountain to clean the waste ink on the ink roller. At the same time, the washed ink roller should be wiped dry with a clean, soft, lint-free cloth.
Roller flat drum requires plate, eraser. The embossing cylinder is straight and can not be tapered. The center distance of the three cylinders is in line with the standard. The diameter of the cylinder is equal to the diameter of the indexing circle of the driving gear, and the liner must be flat. The pressure of the blanket must be uniform, and the pressure should be uniform. The process remains relatively constant. Among the three rollers, the rubber roller is most affected by the elastic deformation of the blanket, so it is often the key to making the roller level work. Handling a little carelessness can cause a lot of problems, such as uneven pressure, dot distortion, roller sliding, etc., resulting in accelerated wear of the printing plate. To do a good job of roller flatness, the following points should be noted:
1. Guarantee the quality of blankets and pads. In addition to the corresponding chemical or physical properties, its thickness must be strictly measured. The thickness of the blanket should be uniform and the flatness error should be within 0.04mm. When dry mouth cards are used to measure the fistula, the two points of the tip should be consistent, and the points should not exceed the allowable error range. The liner should have a certain degree of hardness, smoothness and flatness. Liner paper is best to use Manila paper. If other papers are used, papers with small thickness tolerances, uniform interweaving of fibers, no holes, no lumps, certain tensile strength, and no crushed paper should be used. Wool and felt liner materials should have certain mechanical strength and tensile strength, and be flexible. The texture is dense and uniform.
2. When checking the flatness of the blanket cylinder, the method of painting a full version and drawing a map is usually used. By using a uniform ink layer on the printing plate, the surface of the blanket is uneven and similar to the shape of the map when the blanket is not in full contact with the plate. According to this, the surface flatness is checked and described by a pencil. Different thicknesses of paper fill the depressions of the blanket to make it flat. However, the following points should be noted:
(1) The size of the pad area must not exceed the original size of the low dimple pattern, and it cannot have a hard mouth. It is best to tear it by hand.
(2) Note that the amount of shimming should be gradually thickened and cannot be over-stretched at one time.
(3) When multi-layer shimming, the shimming area should be covered from small to large in order, and cannot be overwritten by the same size of paper.
3. Roller leveling work should be done regularly, with an average of about 3 months.
4. Center distance to the drum. After the pressure is corrected, the pressure of the roller can be checked by the pressure bar method or the paper strip pull test method.
The so-called offset printing "Sanping" refers to the offset of the offset printing machine. Ink rollers and flat rollers (print plate, eraser, impression cylinder) are flat, the pressure is balanced and correct, and the ideal printing effect is achieved.
Water roller flat Water roller flat water roller should be straight, the surface should be flat, water roller pressure should be correct and uniform, not too large nor too small. If the water roller is not leveled, the pressure between it and the string, the water roller and the printing plate will be uneven, resulting in the layout water is too large, too small or uneven water coating, affecting the ink and water balance; resulting in water roller and plate The partial pressure between the roller and the water roller is too large or too small, causing it to run unsteadily and accelerating the wear of the printing plate. To do a good job of water leveling, pay attention to the following points:
1. Pay attention to check the parallelism of the water roller, whether the water roller is bent or deformed. If it is a water roller, the rubber core of the water roller must be straight and the surface must be flat.
2. Water roller velvet should be well-jacketed, sew well, and sew firmly. It is necessary to check whether the surface of the water roller velvet is flat and tight or not, and relaxation is not allowed. After the water roller wadding is wrapped, it cannot be installed immediately. It should be scrubbed twice with a dampening solution and then fully wetted before installation.
3. Correctly adjust the pressure of the water roller to make it left and right. The pressure on the right three points is uniform. First adjust the pressure between the water roll and the string water roll, and then adjust the pressure between the water roll and the plate, and then repeatedly measure the left side of the water roll through the paper strip pull test. The pressure of the middle and the right three points makes the pressures of all points basically uniform. Specific approach: Select 2-3 pieces of kraft paper with straight thread and cut 40cra. A paper strip with a width of about 2 cm and a thickness of 0.1-0.1 mm is placed between the water roller and the string of water rollers or the printing plate respectively. After closing the water roller, the paper strip is pulled and the hand wheel and knob are adjusted. To make it reach the tension of the paper tension, the paper can be pulled out without breaking.
4. Keep the fountain roller. String water roller cleaner. When the work is completed or off work, the water roller must be thoroughly cleaned. From the middle, the cleaning must start from the middle. Both ends must be scraped and washed. After the scraping, the counterclockwise hand should be used to flatten it; when it is on the job, the water should be leveled first. Roll, carefully rub both ends and in the middle.
5. Pay attention to checking the bearing of the water roller. This is important, but it is easily overlooked. The bearing gap is small, the error is small, the rotation can be stable, and there will be no beating. If the bearing has worn out beyond the error range, the rotation will not be smooth, affecting the water transfer. At this time the water roller can no longer meet the use requirements, should be replaced in a timely manner, and installation should also be careful not to exceed the error range. If possible, ball bearings or roller bearings should be used as little or as little as possible.
The ink roller flat ink roller flat requires the ink roller to be flat and the surface is smooth. When running, the surface run-out should not be more than 0.05mm. The ink roller pressure must also be correct and uniform, and the surface performance of the ink roller should be good. Ink performance, so as to ensure the uniform transmission of ink. stable. To do a good job of the ink roller work, we must pay attention to the following points:
1. The core of the ink roller should be flat and the surface should be flat. The surface run-out should be kept within 0.05mm, and the maximum should not exceed 0.1mm. Otherwise, the jump amplitude is too large and will directly affect the uniformity of ink transfer.
2. The method of adjusting the pressure of the ink roller is similar to that of the water roller, and it is also necessary to pay attention to measuring and adjusting the left. In the middle, the right three points make the pressure uniform. It is best to use a paper strip pull test to adjust, and then use the steel test method to adjust. The specific operation method is similar to the paper strip pull test method. That is, the steel sheet is inserted and pulled out at a corresponding position, and the strength can be moderate according to experience. Generally, the thickness of the steel sheet is between 0.15-0.2 mm. Finally, the method of pressing the ink bar is also used for testing. Since most of the current prints are mainly printed on high-line screen dots, the general width of the ink bars can be about 3 mm.
3. Bearings should be kept good. If the wear is serious and the clearance has exceeded the error range, it should be replaced in time to ensure smooth transmission and uniform ink transfer.
4. The problem of cleaning the ink roller is also very important. When the work is completed or after work, it is necessary to thoroughly clean the ink and ink marks on all the ink rollers. In addition to scraping the clean ink, it is necessary to spray gasoline on the ink roller near the ink fountain to clean the waste ink on the ink roller. At the same time, the washed ink roller should be wiped dry with a clean, soft, lint-free cloth.
Roller flat drum requires plate, eraser. The embossing cylinder is straight and can not be tapered. The center distance of the three cylinders is in line with the standard. The diameter of the cylinder is equal to the diameter of the indexing circle of the driving gear, and the liner must be flat. The pressure of the blanket must be uniform, and the pressure should be uniform. The process remains relatively constant. Among the three rollers, the rubber roller is most affected by the elastic deformation of the blanket, so it is often the key to making the roller level work. Handling a little carelessness can cause a lot of problems, such as uneven pressure, dot distortion, roller sliding, etc., resulting in accelerated wear of the printing plate. To do a good job of roller flatness, the following points should be noted:
1. Guarantee the quality of blankets and pads. In addition to the corresponding chemical or physical properties, its thickness must be strictly measured. The thickness of the blanket should be uniform and the flatness error should be within 0.04mm. When dry mouth cards are used to measure the fistula, the two points of the tip should be consistent, and the points should not exceed the allowable error range. The liner should have a certain degree of hardness, smoothness and flatness. Liner paper is best to use Manila paper. If other papers are used, papers with small thickness tolerances, uniform interweaving of fibers, no holes, no lumps, certain tensile strength, and no crushed paper should be used. Wool and felt liner materials should have certain mechanical strength and tensile strength, and be flexible. The texture is dense and uniform.
2. When checking the flatness of the blanket cylinder, the method of painting a full version and drawing a map is usually used. By using a uniform ink layer on the printing plate, the surface of the blanket is uneven and similar to the shape of the map when the blanket is not in full contact with the plate. According to this, the surface flatness is checked and described by a pencil. Different thicknesses of paper fill the depressions of the blanket to make it flat. However, the following points should be noted:
(1) The size of the pad area must not exceed the original size of the low dimple pattern, and it cannot have a hard mouth. It is best to tear it by hand.
(2) Note that the amount of shimming should be gradually thickened and cannot be over-stretched at one time.
(3) When multi-layer shimming, the shimming area should be covered from small to large in order, and cannot be overwritten by the same size of paper.
3. Roller leveling work should be done regularly, with an average of about 3 months.
4. Center distance to the drum. After the pressure is corrected, the pressure of the roller can be checked by the pressure bar method or the paper strip pull test method.
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