Offset presses: standardized operation of water and ink paths

8.3 Standardized operation of water and ink circuits
The standardized operation of water and ink roads is closely related to the quality of printing. If the adjustment is not good, it will directly affect the quality of the printing quality. Therefore, its standardized operation has very important significance.
1. Standardized operation of ink fountain and ink fountain roller
(1) Standardized operation of the ink fountain knife blade The accuracy of the ink fountain knife blade will directly affect the adjustment of the ink supply amount. Therefore, the surface of the ink fountain roller should not be damaged, and its surface should be kept clean. When not printing, the ink fountain should be opened. When printing without printing, the gap should not be blocked, and a thin ink film should be formed on the ink fountain roller.
(2) Normalized operation when inking or inking When inking, first check the quality of the ink. If there are impurities such as ink skin in the ink fountain, it should be removed in time. Fewer prints, use small ink cartridges as much as possible, so there is less waste. When the number of prints is large, a large ink tank can be used. The large ink tank has more ink. If the ink is not used up, the remaining ink should be flattened with an ink knife and then covered with paper. Water can also be applied to the fabric on the ink tank, but prolonged contact between water and ink will cause emulsification of the ink. The ink removed from the ink fountain should not be put back in the original ink tank. It is best to put it in a new stack of ink cartridges. It should also be covered with paper afterwards. When inking, remove the top paper and scrape it with an ink knife. The ink on the bottom of the ink tank should also be scraped out, especially for the red ink. The residual ink with ink skin should not be thrown away at will. It should be pressed once with an ink press machine for printing rough products. When the ink knife reaches into the ink tank to get ink, the ink knife should be turned several times repeatedly, so as to ensure that the ink on the ink knife is not easy to fall down on the way. Of course, in order to prevent the ink from falling down in the middle, the ink tank should be made taller than the ink fountain, but pay attention to safety.
The amount of ink in the ink fountain should be determined according to the number of prints, but there should be a slight savings (mainly the ink used for the roll paper and the ink remaining on the ink roller). If the amount of ink used is large, the amount of ink loaded each time should not exceed two-thirds of the ink fountain capacity. When there is a lot of ink in the ink fountain, it is easy to cause difficulty in controlling the amount of ink. Ink should be stirred frequently during printing, otherwise the ink will harden over time. However, when stirring the ink, the two corners of the ink knife are required to be round. If it is sharp, it should be rounded before use. When printing, you should always observe the amount of ink in the ink fountain, especially when the amount of ink is low, so as to prevent local ink shortage (in fact, it is also the role of ink leveling). When not stirring the ink, the ink knife should be placed at the specified position on the machine.
After printing, the ink on the ink fountain blade and ink fountain roller should be cleaned to prevent the ink from peeling, especially to prevent the residual ink and the dust in the air from sticking together, causing damage to the ink fountain blade and ink fountain roller. If the ink fountain blade is badly worn, you can loosen the fastening screws on it and move the blade forward; if the ink fountain roller is badly worn, you need to replace it.
(3) Standardized operation of ink supply adjustment The basic principle of ink supply adjustment is: the gap between the ink fountain blade and the ink fountain roller is as small as possible, and the rotation angle of the ink fountain roller is as large as possible. But the specific situation should be analyzed in detail.
For inks with high viscosity, the gap control can be relaxed, but it is best to make it small and small, and the angle of the ink fountain roller should be as large as possible; for inks with low viscosity, the control of the angle can be relaxed, but it should also be made as much as possible The gap should be as small as possible.
When printing on coated paper, the gap can be smaller and the corners should be larger; when printing on offset paper or register, the gap should be appropriately larger and the corners should be as large as possible. The adjustment method of the ink supplied by the ink press is the same as that of offset paper. When there is a serious shortage of ink, you can quickly press the ink fountain; when the amount of ink is large, you can use the scraper to scrape down or place the coated paper in the ink path to take out the ink.
2. Standardized operation of ink transfer roller
The contact between the ink transfer roller and the ink fountain roller and the ink cross roller should be kept uniform and consistent, so the contact status should be checked regularly, and the pressure line can be detected by the ink pressure line or feeler gauge. In the ink washing path, make the ink transfer roller swing to lead the residual ink on the ink fountain roller to the ink path together. At this time, the angle of the ink fountain roller should be maximized. When the amount of ink is large, the ink transfer roller can be stopped, and the ink transfer can be resumed after the amount of ink decreases.
3. Standardized operation of ink roller
The size of the cross-motion of the cross-ink roller should be determined according to the requirements of ink viscosity and print quality. Generally, the cross-motion of the screen mesh is set to the maximum. Analyzed in principle, the crosstalk of the dark tone should be larger, and the crosstalk of the highlight can be smaller. Therefore, the string momentum should be the largest when it is live. If you print several colors at the same time with the same color group, you should make the series momentum zero.
When the position of the ink inking roller is different, the amount of ink inking is also different. Therefore, the place with the largest crosstalk should correspond to the dark tone on the printed product, and the place with small or zero crosstalk should correspond to the rear trailing edge or gap of the cylinder. The exact position of the crosstalk should be determined according to the specific situation. .
The surface of the ink fountain roller should have good lipophilicity and water repellency, so it should prevent the acid and alkali solutions from falling on it, causing surface corrosion.
4. Standardized operation of ink leveling roller
The function of the ink leveling roller is to equalize the ink, and it also has the function of buffering and absorbing the vibration. Therefore, the elasticity of the surface of the ink roller should be checked regularly. If the elasticity fails, it should be replaced. The roller surface is aging.
The rotation of the ink roller is driven by friction, so it must be in reliable contact with the ink roller. The position of the ink leveling roller is determined by the ink roller frame on the wall plate. If the position is not suitable, it will cause the ink roller to vibrate, resulting in poor ink leveling. In fact, the ink leveling roller is always in the dynamic balance position (self-aligning).
5. Standardized operation of heavy roller
The function of the heavy roller is to maintain reliable contact of the ink leveling roller. Another important role of the heavy roller is to collect stolen goods. Most of the impurities in the ink path are hydrophilic and easily adsorbed on the surface of the heavy roller, so the heavy roller should be cleaned frequently to keep its surface clean and prevent the impurities from returning to the ink path. The top heavy roller can also be used to shoot ink. When a small amount of ink needs to be added, you can enter it from this position.
6. Standardized operation of the inking roller
The pressure adjustment of the inking roller is the most critical, and it should be adjusted accurately. Usually, it can be detected by the inking line or the plug. Generally, adjust the pressure between the ink roller and the ink roller first, and then adjust the pressure between the ink roller and the printing plate. However, since the pressure between the inking roller and the inking roller will not change too much in a short time, it is usually just to adjust the pressure between the inking roller and the printing plate. When the inking roller and the printing plate are in contact, the ink layer between them is the thickest, so a little carelessness will cause serious deformation of the dot, so it is necessary to accurately control its pressure. At present, offset presses generally use four inking rollers, the amount of ink on each roller is different, usually the pressure of the first two rollers is slightly larger, the pressure of the latter two rollers is smaller, especially the last one The root pressure can be controlled at about half of the first two poles (can be judged by the width of the ink line).
7. Standardized operation for cleaning the ink path
The installation of the wiper is a very important part of cleaning the ink path. The quality of the ink tank installation directly affects the quality and efficiency of cleaning the ink circuit. The pressure between the squeegee and the squeegee roller should not be too large. If it is too large, the rubber pad at the front of the squeegee will bend, causing ink and cleaning agent to stay between the rubber pad and the squeegee roller. If the pressure is too low, the ink cannot be scraped evenly. The position of the wiper should not be too low or too high. Generally, the rubber pad above it and the ink roller are in a tangent position. However, it should be noted that the contact condition between the ink fountain and the ink fountain roller should be uniform. If the rubber pad is worn, the entire wiper can be moved forward; if the wear is severe, it should be replaced. Whether the ink scraper is installed properly can be observed by the effect of ink scraping. If the ink layer flows down evenly, the installation is appropriate, otherwise it should be readjusted. The wiper of the domestic machine needs to be readjusted every time it is installed, and after the wiper of the Heidelberg machine is calibrated once, it can be adjusted for a long period of time and is easy to use. When the ink scraper scrapes ink, you can put some ancient cloth inside, so that the mixed liquid flowing down from the ink path can be stained on the ancient cloth, which is convenient for the cleaning of the ink scraper itself. The installation of the wiper must be reliable, that is, both sides must be placed in the plug on the wall board, otherwise it may cause accidents.
The use of cleaning fluid is another important part of the ink circuit. The cleaning fluid is generally dominated by gasoline, but now there are special cleaning fluids. When cleaning the ink path, firstly pour the cleaning liquid onto the top single ink roller in the ink path (injecting the left and right evenly). In order to clean the ink fountain roller at the same time, the angle of the ink fountain roller should be maximized, and the ink transfer roller should be in working condition. When it is found that the ink in the ink path has been cleaned, the wiper should be opened. If the ink is not cleaned, you should continue to add cleaning fluid. If there is a dry grinding state between the wiper and the squeegee roller, an abnormal sound will be made. At this time, the wiper should be opened urgently or the cleaning fluid should be injected into the ink path immediately. Be careful not to put the cleaning liquid on the wall plates on both sides, otherwise the lubricated parts of the wall plates will be affected.
If the ink path has not been cleaned after repeated use of the cleaning solution, the ink rollers (inking roller, ink leveling roller, heavy roller and ink roller) in the ink path should be removed and cleaned one by one. If there are impurities such as paper wool in the ink path, it can be cleaned by patting ink. First shoot the ink on the heavy roller at the top of the ink path, the ink enters the ink path from here, the impurities in the ink path stick together, and enter the wiper along with the cleaning fluid.
When changing the ink, the ink in the ink path should be cleaned once, and then the ink to be used should be patted into the ink path, and the cleaning fluid should be added to wash again. Generally, after these two cleanings, new ink can be used. However, if it is a particularly demanding product, the ink roller should be removed and cleaned one by one.
8. Standardized operation of water bucket and water bucket roller
(1) Standardized operation of water supply tanks At present, most printing presses use direct water supply from water tanks. The flow of water is achieved by the pressure difference. Appropriate pressure difference can keep the water supply uniform. Therefore, it is necessary to create the existence of pressure difference. When filling water, do not fill the water tank to avoid the formation of negative pressure and the water cannot flow down. In addition, it should be noted that the water injection hole on the water tank should have a good seal. If the seal is not suitable, the flow of water will be unstable. After the water in the water tank is used up, the residual liquid in it should be cleaned, and then a new fountain solution should be installed. In addition to the direct water supply from the water tank, there are currently some machines that use electric water to add water, that is, the water in the water tank is sent to the water bucket through the water pump. This method can circulate water, but in order to prevent dirt from re-entering the water bucket, The population is equipped with filters, and the filters should be cleaned regularly. There is another way of water supply is alcohol wetting. The fountain solution is sent to each color group through a water tank. Pay attention to the mixing ratio of alcohol and water. Generally, this ratio is 25%. High, otherwise the alcohol will evaporate seriously.
(2) Standardized operation of water bucket and water bucket roller The water in the water bucket can be added by the water tank or directly by hand, but the labor intensity of the latter is greater, and the water in the water bucket should not be too much, otherwise at high speed It may overflow, and the water in the water bucket should not be too small, otherwise the buffering capacity is too weak. The pH value of the fountain solution is generally controlled at about 4-6, and the residual liquid in the water bucket should be cleaned every day after work to prevent the water bucket from corroding. Pay attention to the installation position of the water bucket and the layout of the upper and lower water pipes. If the installation is not suitable or the water pipe is not smooth, it should be adjusted in time.
The amount of water supply is achieved by changing the rotation speed of the water bucket roller. The rotation of the water bucket roller is driven by the water roller motor. The improper installation of the water roller motor of some machines or other reasons often cause the water bucket roller to not rotate or the speed is uneven. At this time, the cause should be investigated in detail. Some machines on domestic single-dual-color machines cannot be locked during operation. If this situation is found, it should be adjusted in time. In addition to automatic watering, some machines use manual watering to pour water directly into the water bucket, but you should always observe the amount of water in the water bucket when printing.
When the printing plate is dirty, it is necessary to adopt emergency watering method. Generally, plastic bottles with nozzles are used to add water to the water transfer roller or the water outer roller. It is not advisable to directly add water to the water roller. It can also adopt the method of water filling as a whole (that is, increase the rotation angle or rotation speed of the water bucket roller, and then return to the original state after the victory is removed). Some equipment is equipped with an emergency watering device. You can also use a sponge to control the amount of water in the local water supply (wet the sponge and squeeze it by hand).
When the water volume exceeds the normal demand, the water supply volume can be reduced by reducing the rotation speed or rotation angle of the water bucket roller. If the local water is large, you can install a scraper or blow nozzle to reduce the amount of water. You can also use a piece of paper to stick to the bucket roller and the other end to the bucket to absorb the excess water on the bucket roller through the paper sheet. In this way, the number of prints is small. When the number of prints is large, the paper is easy to enter the water path with the water bucket roller due to the reduced internal stress of the temperature, and finally lead to the ink path or the printed product.
9. Standardized operation of the wood transfer roller
The key to the adjustment of the water transfer roller is to prove that the pressure on both sides is consistent and should not be too large, otherwise the water on the outside of the water will be squeezed out, but it should not be too small otherwise the water will not pass. The water rubber fleece of the water transfer roller should be kept clean, and the water should be filled before the start, and then the ink, so as to ensure good water repellency of the waterway. [next]
10. Standardized spreading of water roller
The standardized operation of rate mercury is similar to that of ink rollers. The difference is that the surface should be hydrophilic and repel ink. If there is oily substance on the surface, it should be removed in time.
11. Standardized operation of the water stick
The adjustment of the water roller is the same as that of the ink roller. The general machine is equipped with two water rollers, one of which is mainly responsible for water supply, and the other is mainly responsible for water leveling. To print high-quality prints, the amount of water must be even, so both water rollers should be used. For some coarse grain products, only one water roller can be used. At present, a wetting roller is generally used for alcohol wetting. For two landing rollers, attention should be paid to the pressure coordination relationship between them. The pressure between the upper landing roller and the stringing roller should not be too large, otherwise it will be difficult for the lower landing roller to fill the water.
12. Standardized operation of water glue line
The water rubber fleece should match the diameter of the water rubber roller. The number of water rubber fleece used in different models is often different. If the diameter of the water gel fleece is too large, it is difficult to tightly surround the water gel fleece. As a result, the wrapped roller is not round. If the diameter is too small, it is difficult to fit the water rubber roller.
It is difficult to install the domestic water gel fleece. You should first scrub the water rubber roller with talc powder to make it smooth, so that the water gel fleece will be easy to put in, otherwise it will be difficult to put it on. It can also be wrapped with thin paper on the water rubber roller, and then covered with water rubber fleece. Although this is very easy to wrap, but when the water wave line is wet, the paper tension is reduced, between the water rubber and the water rubber roller Under the action of friction, causing uneven pressure on the water roller. Another method is to bundle two or three thin polyester wheels on the oil head at the end of the water rubber roller (the same length as the water rubber roller), and then put the water rubber fleece from the end of the bundle, and then put the film on This method is more practical and convenient. For example, the glue thread uses the fluff on it to absorb water. If the fluff is reversed, it will not play the role of water. The water glue grade will wear off after a period of time. If this phenomenon occurs, it should be replaced in time. After the water gel fleece cover is set, it should be immersed in water, and then use a brush or a plastic knife to scrape off the fluff that is not firmly adhered on it. Wash and scrub with water every day after work. The common practice is to soak it in gasoline to dissolve the oily substance on it, and then scrape it with a scraper. The water on it should be re-installed during installation, so as not to store too much water on it, which will cause difficulties in printing. Due to the series movement of the water roller, if the water glue line is not installed firmly, the water glue roller will come out from one end. If this happens, you should stop in time and fasten the water glue. Both sides of the domestic hydrogel are locked with rope (first sew the rope at both ends of the hydrogel, and then force the two ropes together), Heidelberg's hydrogel is easy to install, and the hydrogel is placed on the hydrogel On the roller, soak in the pool, warm water for 5 minutes, cool water for 15 minutes. However, it should be noted that when installing the water rubber fleece, it is necessary to pull hard on both sides, so that the amount of water rubber fleece in the middle can be minimized, and the water rubber fleece that grows at both ends should be cut off, otherwise it will affect the operation of the bearing.
13. Standardized operation of water and ink roller landing gear
When printing, the water and ink rollers are closed, that is, against the plate cylinder. When not printing, the water and ink rollers need to be left. This process is achieved by the landing gear of the water and ink rollers. The landing gear of the water roller is manual or electric. At present, there are many manual ones. When printing, first put down the landing gear of the water roller by hand, and then press the ink. If you forget the hydration roller, it will paste. The landing gear of the ink roller is mainly automatic, that is, the ink is automatically applied when the pressure is closed, but when the pressure is not closed, it can also be manually operated to make it clutch. The landing gear of the ink roller can also be locked, so that it can be disengaged from the clutch pressure mechanism, so that the set of ink paths stops inking.
The landing gear of the water and ink roller also controls the distance between the ink roller and the water roller and the printing plate. Some machines are equipped with adjustment stoppers for water and ink rollers, which can be used to control the maximum and minimum distances between water, ink rollers and printing plates.
14. Standardized operation of printing plate
(1) The cylinder body of the printing plate should be kept horizontal and available for inspection only, but this method cannot be adopted after the equipment is installed. The usual practice is to check the level of the plate cylinder based on the rubber cylinder, which can be detected by pressing a fuse, pulling a paper strip, or pressing an ink bar.
(2) The surface of the plate cylinder body should be kept clean to ensure the uniformity of the contact pressure. Therefore, every time the plate is installed, impurities such as ink on the surface of the cylinder body should be cleaned.
(3) The liner under the printing plate should be flat and should be slightly compressible, so it is not suitable to use coated paper as the liner. Offset paper, textured paper, special pad paper, etc. can be used. In fact, as long as the surface is flat and slightly compressible, for example, the polyester wheel base can be used as the printing plate liner. Because there is relative sliding between the printing plate pad and the printing plate and the cylinder body. As a result, the surface of the pad will be worn and the uniformity of its surface will be destroyed. In addition, due to the effect of printing pressure, the compressibility of the printing plate liner is getting smaller and smaller, so the liner should be replaced after a period of use. The fewer the number of pads, the better. The thickness of the pad should be measured with a sub-meter, subject to the data in the technical specification. It is worth noting that when the surface of the pad is uneven, it cannot be replaced, but can only be replaced.
(4) The graphics and text on the surface of the printing plate must be complete, uniform and consistent, so as to ensure uniform inking of the entire layout, and the surface of the printing plate should be free of dirt. If there is a victory, it should be removed with a decontamination agent in time. If a large area is dirty, it can be scrubbed with developer. To meet the above conditions, there should be strict requirements for printing, exposure time, vacuum and developing roller concentration should be standardized.
The decontamination of the printing plate should be carried out before the machine, at this time, it is convenient to win, and it is convenient to take other measures. However, some latent dirt on the printing plate will only be exposed when printing, so you should always check the proofs after starting up. If the surface layer of the printing plate is destroyed, it will affect the hydrophilicity of its surface, resulting in surface upper limbs. Such as long time parking, the surface of the printing plate is exposed to strong light, and the regenerated version. If it gets dirty, it can be scrubbed with moisturizing powder, but at this time the graphic parts are also affected. If the scrubbing still does not work, the plate needs to be replaced.
(5) The graphic on the surface of the printing plate should be centered, but due to the irregularity of the printing plate, it can only be close to the center. Based on one side, the mouth of the printing plate should be consistent on the left and right, and it should be noted that the size of the mouth of the different models is different. Generally, the instruction manual of the machine should prevail. If the image is printed on the inside of the mouth, it may not be printed. Or its surface is dirty.
(6) When installing the printing plate, the plate clips should first be displayed on the left and right sides, and the plate clips on the edge of the mouth should be in a specific position, and the two sides should be consistent. It can be judged by the ruler or other characteristic symbols on the plate gap The clip at the tip should be placed back to the lowest end. Secondly, the trailing edge of the printing plate should be bent at an angle of 120 Â° to facilitate insertion into the plate clamp. Prepare the pad of the printing plate again. After the above three tasks are completed, the following operations can be performed. First, press the grip edge of the printing plate into the plate clip, make the plate edge and the clip solid, and then lock the plate clip. The plate clamping mechanism of different models is different. For screwing the plate clamping, the middle should be tightened first, and then both sides should be tightened. For the quick plate clamping mechanism, attention should be paid to the adjustment of plate thickness. After installing the edge of the printing plate, place the plate gasket between the plate and the cylinder. Note that the liner should be flat and the grip should be placed well. Then press it together (the ink roller should be locked first) or put it down The water roller is installed so that the printing plate can be tightly enclosed on the drum, and it is also convenient for the installation of the printing plate. When you want to turn to the trailing part of the printing plate (the hand rest plate is used when turning), stop the machine (some machines will automatically stop), insert the phase application part of the printing plate into the plate clip, and the operation is the same as the mouth . After the upper and lower sides of the printing plate are installed, the printing plate and the roller body can be fixedly connected together by the support screw on the upper side of the plate clamp. It is best to tighten the axial item plate screws at both ends of the plate clamp (especially It is the mouth).
(7) The adjustment of the printing plate should be carried out according to the specific situation. In general, there are the following situations: local (printing direction) drawing, axial drawing, circumferential and axial drawing at the same time.
â‘ Circumferential pull-up: When the circumferential overprint of the printing plate is inaccurate, it can be adjusted by the supporting screw on it. If you pull the printing plate towards the edge of the gripper, first open the drag screw on the plate clamp of the dragging part, and then turn the gripper screw on the gripper edge, the printing plate moves forward (note that the printing plate cannot be pushed back ), Of course, the amount of pull on both sides can be different, and vice versa.
â‘¡Axial pull plate: when the axial overprint of the printing plate is inaccurate, it can also be adjusted by adjusting the top plate screw on it. Pay attention to that the top plate screw on the other end should not contact with the roller, and should also loosen the corresponding plate clamp Support screw.
â‘¢ Simultaneous axial and circumferential pull version: when both circumferential and axial directions need to be adjusted at the same time, you can adjust as described in â‘ and â‘¡. During the drawing process, it should be noted that the reference edge cannot be selected incorrectly. The reference edge is selected based on the graphics on the printed sheet. The essence of the pull plate is to change the relative position of the printing plate, so the axial and circumferential pull plates can sometimes play the same role.
(8) Adjustment of the printing plate cylinder When the rule line on the printing plate is parallel difference, the registration requirements can be achieved through the change of the position of the printing plate cylinder. The axial movement of the plate cylinder is achieved by the plate-drawing mechanism pulling the plate cylinder shaft, and the circumferential movement of the plate cylinder is achieved by the plate-drawing mechanism pulling the gear on the cylinder. In order to make the position of the plate cylinder change smoothly, the plate cylinder should be pulled while the machine is running. The plate pulling mechanism is manual or electric, but the plate pulling amount is relatively small, the axial plate pulling amount is generally 5mm, and the circumferential plate pulling amount is generally 3mm. If the rule line of the printing plate exceeds this adjustment range, other measures can be adopted. If the axial difference is large, it can be adjusted by the lateral movement of the gauge. If the circumferential difference is large, it can be achieved by borrowing the roller. Pay attention to when borrowing the roller: After borrowing, the roller should be locked. It is best to use the turning method (domestic machine) to borrow the roller. The plate cylinder of the imported machine is directly equipped with a plate drive mechanism. In addition, large reprint errors can be eliminated by re-fixing the printing plate.
(9) Calibration of the version clip mechanism The calibration of the version clip mechanism is very beneficial for reducing the time for finding rules. Prepare a set of printing plates with standard gauge lines, install them as described above, and set the axial and circumferential plate pulling mechanism of the cylinder to the zero position, and the previous position to the zero position. When there is an error in the rule line, the requirements can be met through the adjustment of the printing plate. When the accuracy of the overprint meets the requirements, write down the reading on the scale, so that if you use this reading to determine the position of the printing plate when installing the plate later, you can quickly correct the rules. If the printing is irregular, this method should not be adopted. When this happens, a marking line can be made on the drum. When you are sure that the rule line is completely accurate, extend the rule on the plate to the surface of the plate cylinder. In this way, each time the plate is installed, the rule line on the printing plate and the marking line on the cylinder coincide, so that the printing plate can be corrected as quickly as possible. This method is the most practical.
(10) Protection of the printing plate When holding the printing plate, it should prevent the formation of horseshoe marks or other types of disassembly marks to avoid scratches on the surface of the printing plate. The printing plates that are not used for a short time should be protected by the cavity and placed in a dark place. The plates should be separated by paper. Prevent acidic or alkaline substances from staying on the surface of the printing plate, causing corrosion of the surface of the printing plate. The printing plate should not be placed in a high temperature environment, otherwise the hydrophilic layer on the surface will be oxidized. The cloth for scrubbing the printing plate should be kept clean, and there should be no other hard impurities such as sand. Before wiping the glue, the ink on the printing plate should be cleaned first, otherwise the ink may consolidate on the surface of the printing plate. The printing plate should not be clamped too tightly, otherwise the surface of the printing plate will be broken, but it should not be too loose, otherwise the printing plate will slide relatively within the clamping plate. To make the plate clamp reliable, the entire plate clamp should be in working condition. This is very important. Otherwise, the plate will be partially stressed, causing tearing. The lining of the plate cylinder and rubber cylinder should be carried out according to standard data, so as to ensure that the plate and water, ink roller and blanket are in a pure rolling state. In addition, the printing pressure should be as low as possible, which can reduce the friction of the printing plate surface. There is a paper feed failure during printing, it is not appropriate to stop the host, and the water roller should be kept in contact with the surface of the printing plate, so that a water film can always be guaranteed on the surface of the printing plate. If the machine is stopped, the water roller should be away from the printing plate, otherwise the first few sheets of paper will form a water bar or transfer the dirt on the water roller to the printing plate.
l5. Standardized operation of rubber roller
(1) The rubber roller body should always be kept level and can be detected by a spirit level, but generally the level of the rubber roller is calibrated based on the impression cylinder, and can also be detected by the method of pressing a fuse, pulling a paper strip, or pressing an ink bar.
(2) The surface of the rubber roller body must be kept clean to maintain the uniformity of the contact pressure, so every time before installing the rubber cloth, the ink and other impurities on the surface should be scrubbed clean.
(3) The liner under the blanket should be kept flat. The liner under the blanket varies according to the accuracy of the machine. There are three types of soft, medium and hard. Note that the choice of liner should be based on technical requirements, can not be arranged at will, this point should be strictly paid attention to. Regardless of the type of liner used, the surface should be flat and have a large coefficient of friction. Therefore, it is not appropriate to use coated paper as the liner. It is best to use offset paper or other paper with a rough surface but a flat surface.
(4) The selection of rubber blankets should also be carried out according to the accuracy requirements of the machine. There are two types of blankets: ordinary blankets (also called elastic blankets) and air cushion blankets. Soft padding, air cushion blanket + medium and hard padding. The lining of the rubber roller shall be subject to the technical specification.
(5) The surface of the blanket should be kept clean so as to ensure uniform contact pressure, and it is conducive to stable print quality. During the printing process, the blanket should be scrubbed frequently (not suitable for scrubbing with non-volatile oils). Should be scrubbed.
(6) Installation of the rubber blanket First, cut the blanket into a short shape, and make its longitudinal direction the circumferential direction of the roller, and then put the blanket into the plywood, be sure to put it firmly. When tightening the splint, start from the middle and then tighten the two sides, but in the process of tightening, it should be gradually approached. After the blanket and the splint are installed, the operation on the roller should be performed. There are two spring runners on the drum. First use the splint to open the spring clip, and then press down the splint. At this time, the two spring clips are pulled back, so the splint enters the wedge groove above the drum (you should hear one The crisp voice, if you can't hear it, you should check it carefully, otherwise the consequences will be unbearable). After the splint is put in place, turn the worm gear mechanism, and when the angle is appropriate, put backing paper and click the car. Afterwards, the rear plate clamp is changed into the groove of the old man, the worm gear mechanism is rotated, and the blanket is tensioned. Generally speaking, the tension on the surface of the blanket should be greater than the frictional force generated by the contact surface during printing, so as to ensure that the blanket is tightly enclosed on the cylinder during printing, otherwise the blanket will be doubled and loose.
(7) The surface of the blanket will become uneven due to various reasons. If it is not padded, the print quality will be affected. For the slight indentation, you can use the rubber restoration fluid; for the heavy indentation, you need to use the method of cushioning. When padding the blanket, you should first draw the position of the padding (commonly known as drawing a map). This position must be accurate. The usual practice is to use the pen tip to draw from under the blanket (visually at the indentation). The paper in the padding rubber market should not be too thick, usually the thickness should be 0.03-0.05mm, if the thickness is not enough, two or three layers can be cushioned, but the number of layers should be the least, and the glue used should be as little as possible. It is best to pour the glue and gently scrape it with a small blade to make the glue as thin as possible. It is not advisable to pad paper under the liner, because the liner will slip relative to the blanket. For some products, the method of moving the blanket can be adopted, such as moving the blanket under pressure to a part that is not obvious or without graphics.
(8) Maintenance of blankets The newly installed blankets should be re-clamped after printing 10,000 sheets. If not used for a long time, the blanket market should be released. When not printing, the blanket should be covered to prevent sunlight exposure, and the surface of the blanket should be protected from acid, alkali, oil and other substances. The printing pressure should not be too large, otherwise the surface of the blanket will be worn. After using the blanket for a period of time, it should be removed and placed in a dark place to gradually restore its elasticity. If the rubber market is no longer flexible and compressible, you should stop using the rubber market. When printing, it should prevent the paper into dozens or other debris from entering the middle of the roller. The pad under the blanket should be replaced after a period of use. When printing rough work, use a poor blanket; when printing fine work, use a high-quality blanket. Unless the overhaul is generally not suitable for changing the position of the rubber roller (otherwise there will be an accident).
16. Standardized operation of printing pressure
The printing pressure includes water, the pressure between the ink roller and the printing plate, the pressure between the printing plate and the blanket, and the pressure between the blanket and the impression cylinder. The printing pressure is closely related to the printing quality, so the printing pressure of each part should be strictly controlled. From the perspective of ink transfer, the ink layer between water, the ink roller and the printing plate is the thickest, followed by the printing plate and the blanket, and the thinnest between the blanket and the impression cylinder. Judging from the roughness of the contact surface, the roughness of the contact surface between the printing plate and the water, ink roller and blanket is small, and the roughness between the blanket and the paper is large. The greater the roughness, the thinner the ink layer. The lower the sensitivity to pressure. It can be seen from the above analysis that the pressure between the printing plate and the water, ink roller and blanket should be strictly controlled. The pressure between the blanket and the paper can be slightly larger to make the dots neat and strong.
The size of the printing pressure can be detected with a feeler gauge, a fuse, a paper strip, an ink line, or a full version of the ground (70%). The more accurate method is the ink line. First, press the ink line between the inking roller and the printing plate well (push the landing gear of the ink roller repeatedly) and then lock the landing gear of the inking roller. At this time, the pressure line is running, and the ink line is transferred from the printing plate to the surface of the blanket and the impression cylinder. The size of the printing pressure can be estimated by the width of the ink line. In general, the ink line should be controlled between 4-5mm. A more accurate method is to use a signal test strip. If the printing pressure does not meet the requirements, you can adjust the printing pressure by changing the center distance and changing the thickness of the pad.
The printing pressure is equal to the product of the contact material's resistance to deformation and the amount of deformation. In these two parameters, reducing one while increasing the other can achieve the same printing pressure, which provides a theoretical basis for the selection of printing pressure. For printed art paper, the deformation of the contact surface is smaller; for printed offset paper, the deformation of the contact surface is larger. When printing on the ground, medium and soft pads can be used, and the amount of deformation is a little larger, so that the ground can be worn flat. When printing meshes, medium and hard liners should be used, and the amount of deformation is a little smaller, so as to ensure that the mesh points are clear and strong.
17. Standardized operation of clutch pressure mechanism
At present, the sequential clutch pressure mechanism is used on the offset printing machine, firstly the pressure between the printing plate and the rubber, and then the pressure between the rubber and the impression cylinder. Sometimes the closing process can be completed within a week, sometimes it cannot be completed, but at most it does not exceed two weeks, so when the car is turned on for two weeks, the machine can be reliably closed. The depressurization process is the opposite of the above, but the time is the same.
The clutch pressure mechanism is an inertial mechanism. The higher the speed, the greater the inertia, so it is not suitable to carry out clutch pressure at high speed. The speed should be increased after the closing is completed. If the pressure between the rollers is high and low, the working condition of the clutch pressure mechanism should be checked. For the control mechanism using an electromagnet as the clutch pressure, the copper core will be worn out after a long time, and the clutch pressure mechanism will fail. The working condition of the electromagnet should be checked frequently. When the machine is stuffy, the clutch pressure mechanism should be pushed to force the machine to release pressure, so that the machine can be unloaded first.
18. Standardized operation of pressure regulating mechanism
When there is a slight change in the printing pressure, it can be calibrated by the pressure regulating mechanism (it can also be calibrated by the pad).åˆ¤æ–è°ƒåŽ‹é‡çš„å¤§å°æ—¶ï¼Œå¯ç”¨åŽ‹ä¿é™©ä¸çš„æ–¹æ³•æ¥æµ‹é‡ã€‚åŽ‹ä¿é™©ä¸çš„åŸºå‡†æ˜¯æ»šç’çš„è‚©é“ï¼Œå› æ¤è‚©é“ä¸€å®šè¦ä¿æŒæ¸…æ´ï¼Œå¦åˆ™ä¼šå½±å“æµ‹è¯•ç»“æžœã€‚åŽ‹ä¿é™©ä¸æ—¶ï¼Œä¿é™©ä¸çš„æ’å…¥æ–¹å‘åº”å’Œæ»šç’çš„æ—‹è½¬æ–¹å‘ä¸€è‡´ï¼Œè¿™æ ·æ»šç’å›žè½¬æ—¶å¯å°†ä¿é™©ä¸å¸¦äººåŽ‹å°æŽ¥è§¦é¢ï¼Œè€Œä¸”ä¸¤è¾¹åº”åŒæ—¶åŽ‹äººï¼ˆåŒä¸€ä½ç½®ï¼‰ï¼Œå¦åˆ™ç»“æžœä¹Ÿå¯èƒ½æœ‰åå·®ã€‚å¦‚æžœä¸¤ç«¯ä¿é™©ä¸çš„åŽšåº¦å·®å¤§äºŽ0ï¼Ž02mmï¼Œåˆ™åº”é‡æ–°æ ¡å‡†åŽ‹åŠ›ã€‚å¦åˆ™ç”±äºŽä¸¤è¾¹åå¿ƒä½ç½®ä¸åŒå¿ƒï¼Œæœ‰å¯èƒ½é€ æˆè½´æ‰¿æˆ–é½¿è½®è¿è½¬ä¸ç¨³ã€‚å¸¦æœ‰é”ç´§è£…ç½®çš„è°ƒåŽ‹æœºæž„åœ¨è°ƒåŽ‹å®ŒæˆåŽï¼ŒåŠ¡å¿…å°†å…¶é‡æ–°é”ç´§ã€‚

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