Section 1: Lithographic Offset Presses Offset printing presses now use an indirect structure, which is printed on an intermediate ----- blanket cylinder to obtain printed graphics. Therefore, lithographic printing presses are often referred to as offset printing presses. Lithographic offset presses, except for round press proofers, are all circular presses, but there are many types. There are manual feeds and automatic feeds; there are single-sided presses and double-sided presses. Printed; Monochromatic, but also multi-color; There are sheets of paper printed, but also a web printing; There are full-open, open, and four open; In addition, some lithographic offset The machine is also equipped with a drying device and a folding device. No matter what kind of lithographic offset printing press, as shown in Figure 9-4, it consists of five parts: feed mechanism, ink supply mechanism, wetting mechanism, and delivery mechanism. (1) Paper feeding mechanism. Consisting of paper storage and paper feeders. (2) Printing organization. Including plate cylinder, blanket cylinder, impression cylinder. Figure 9-5 shows the configuration of each roller in a sheet-fed offset press, and Figure 9-6 shows the configuration of each roller in a web offset press. (3) Ink supply mechanism. It consists of ink fountain, ink adjustment screw, ink output adjustment plate, ink fountain roller, ink transfer roller, ink distribution roller, ink string roller and reel roller. The arrangement is shown in Figure 9-7. (4) Wetting mechanism. Including the bucket, the bucket roller, the water transfer roller, the uniform roller, and the water roller, as shown in Figure 9-8. Section II: Preparation of a lithographic printing process before printing. The lithography's own characteristics determine the complexity of its printing process. Therefore, it must be fully prepared before printing. Prepress preparation mainly includes: paper cutting, school edition, edition, water supply, ink supply, and paper. The first is the preparation of paper. Due to the need of printing size, the printed paper must be cut as required. (Cut paper).
In order to reduce errors that may occur after the printing plate is placed on the machine, the printing plate must be rechecked before printing. The contents mainly include: blue pattern, specifications, printing stone, printing color. (School Edition)
After the proof plate, it can be fixed on the plate cylinder. In order to ensure the quality of the printed matter, it is necessary to grasp the tightness of the upper plate during the operation of the upper plate. If the plate is too loose, overprinting will occur. The printing plate bursts. (Previous edition)
In the prepress preparation process, the selected ink will be loaded into the ink fountain, and the inking device is adjusted so that the ink is uniformly transferred. In the process of applying the ink to the water, we must maintain a balance between water and ink to prevent water and ink from becoming large. Here are some highlights of prepress preparation: 1. Preparation of plates. In order to reduce errors that may occur after the printing plate is placed on the machine, the printing plate must be reviewed before printing. The contents include: plate thickness, printing plate type, color type, color tone, the distance of the printing plate, and whether the plate has irregularities Scars, foreign objects on the back of the plate, etc. Special attention should be paid to the inspection of color and tone. 2 Preparation of ink. The ink used for lithographic printing must have the characteristics of easy printing, that is, it can be smoothly drawn from each ink fountain and passed through the ink roller and printing plate to the rubber roller and printed on the surface of paper or other substrates. Offset printing is indirect printing, and has the presence of fountain solution. When the ink is transferred from the blanket cylinder to the paper surface, the amount of ink must be reduced. Therefore, the offset printing ink should have sufficient adhesion to the paper surface, acid resistance, and insolubility. Water, strong anti-emulsification, bright color, strong gloss, no discoloration after drying, no discoloration, etc. At present, the inks used in offset printing are the following: A. Bright offset printing inks. With high gloss, bright colors, clear dots and good abrasion resistance, it is an advanced resin type offset ink. It is suitable for the printing of coated high-grade paper such as coated paper and glass powdered paper. B, fast fixing offset ink. With good gloss and good fixing characteristics, it can reduce blemishes, shorten the printing cycle and increase the printing speed. Suitable for printing high quality paper and general paper. C, rotary offset ink. Web offset printing inks are used for Web offset printing and are suitable for web presses with printing speeds up to 24,000 rpm.
3 fountain solution preparation. Except in special cases, the dampening water used for offset printing is not pure water, but contains a dilute solution of various electrolytes, surfactants, and hydrophilic colloids. In order to distinguish it from the general water phase, we call the aqueous solution used for the wet-printing surface in the offset printing process a fountain solution, or water fountain solution. In order to make the fountain solution ratio and easy to use, the traditional method is to according to the provisions of the formula and the preparation method, a relatively high concentration of the solution is prepared, called fountain solution. When used, dilute the original solution with a fountain solution. Dampening reduction liquids are also often used directly to erase the dirt that is present on the blank part of the printing plate, or to overcome the drawbacks of "burning paste." Due to the gradual commercialization of offset printing raw materials, there are bottles (cans) of dampening stock sold on the domestic and foreign markets. For the convenience of transportation, sales, and use, there is also the sale of each group into tablets or powders. At present, many printing companies in China are still using the zinc-skin-based flat intaglio plate. The hydrophilic part of its blank part is the polar inorganic salt-zinc phosphate layer. It is not wear resistant and has poor chemical stability. And due to a variety of physical and chemical factors, in the printing process, the graphic part may tend to expand, resulting in "burn"; and the blank part of the hydrophilic properties will be reduced, resulting in "dirty version." In order to overcome the drawbacks of “burning†or “dirty printingâ€, one of the main technical measures is to wet the printing plate with fountain solution during the printing process so that the hydrophilicity of the blank portion remains relatively stable. Before the formal printing, the three formal printing needs a calibration process. The contents of the calibration mainly include: printing color, printing specification, tangent, angle line requirements, stains. The film outlet has been removed, the printing lines are registered, and the front and back are overprinted. There are also specific projects requested by the client or the Works Branch.
Before starting the machine, you should first wipe the paper powder on the plate with water, and then use fire water to remove the ink from the plate surface stone. Then, be optimistic about the pull gauge, adjust the double-sheet system and the blowing of the paper feeder. Officially start printing, the first printing and delivery of qualified printed sheets will be sent to the competent person for signing and approval, and then it will be officially mass-printed. In order to promptly discover the quality of printed matter, every 200-300 sheets shall be printed during the printing process. Samples are taken once and the samples taken are routinely inspected. After the printing of each sheet of the vehicle is completed, the personnel concerned must reprint the samples according to the standards to ensure that the color and quality meet the requirements. Section 3: Overview of the development of rotary printing processes for one-step printing At present, rotary printing develops rapidly. The Division also complied with the requirements of the times and set up the Ministry of Rotary Printing. Rotary printing will gradually grow.
Rotary printing, also known as rotary lithography, is the use of webs for continuous lithographic printing. Rotary printing is a kind of printing method developed in modern times. Initially, due to the undeveloped science and technology, the rotary printing press at that time was bulky, complicated in structure, inconvenient in operation, poor ink drying, difficult to control paper tension, and expensive equipment, so the market was small, but with the rapid development of science and technology , The rotary machine has greatly improved in terms of speed quality and economic efficiency, and has greatly surpassed the potential for flat sheet printing. Specifically, the history of the development of rotary printing can be divided into the following stages:
In 1865, W.Bullock pioneered a web rotary press. This can be said to be the start of rotary printing, but it must be cut before it can be printed. In 1869, the London Times technician completed the first rotary press that had been printed and then cut. This was the prototype of the current rotary press. At that time, the double-sided printing speed reached 12,000 sheets/hour. In 1930, the invention of the thermosetting ink was officially used for commercial printing. At the same time, printing in the United States began to enter the newspaper printing system, and entered the stage of rapid development.
Domestic status: Although printing has originated in China, lithographic technology has been completely introduced from foreign countries, especially the introduction of rotary lithography. This is only a matter of recent decades. In general, domestic rotation printing starts from the newspaper industry, and commercial rotary lithography has only been introduced to the country for about ten years, and our company has not introduced the rotation machine infrequently. It can be seen that there is still much potential for rotary printing in China.
Development prospects: The development of today’s era is all reflected in the common progress of the economy and culture, and the demand for it is also increasing. In the face of such a large market, rotary printing has emerged, and it has shown its rapid growth since the early 60’s. Development momentum. For example, in the United States, there were only 228 commercial rotary presses in 133 printing plants in 1961, and in January 1969 there were 729 commercial rotary presses in 286 printing plants. The turnover increased from 200 million U.S. dollars to 27 trillion U.S. dollars. In particular, in recent years, rotary printing has become the fastest growing printing method in Europe, the United States, and Japan. In the United States, after 1980, all lithographic printing machine manufacturers mainly produced rotary lithographic printing machines. It can be seen that rotary printing has an important position in the printing industry with its obvious advantages of high efficiency, high quality, and low cost. We have every reason to believe that in the upcoming new century, there will be even more splendor in rotary printing. Prospects. The structure of the second turn machine:
1. Paper supply unit Since the web press prints on a web, the paper supply system is mainly responsible for supplying paper, controlling the paper speed, tension, and edge position so that it can stably supply the paper to the printing unit. The paper supply system can be divided into two parts, one is the paper feed frame, and we can see in the figure that it is mainly used for the support and stability of the paper roll. The other part is the paper guide roller system, which is mainly used to provide the required tension of the roll paper and the left and right paper gauge positions.
2. Drying Units In commercial rotary printing, thermosetting inks are generally used. Thermosetting inks generally have high gloss and low viscosity properties. They need to be heated to a certain temperature to be dry, that is, most of the solvents in the ink evaporate when they pass through the drying oven. This allows the ink and the pigment in the ink to evaporate. Through the cooling roller fixed on the paper surface. Most of the current use of hot air drying, fuel for liquefied petroleum gas. At present, our company is using this drying method. 3. Cooling unit paper through the drying box, the temperature is high, the paper surface temperature up to 120-150 °C, the ink is still viscous at high temperatures, so after cooling and curing, so that the surface temperature is reduced to about 30 °C, generally The cooling roller is used to cool the circulating water, and the contact area between the roller and the paper is increased as much as possible to increase the cooling effect. In recent years, cooling cycle oil has also been used to reduce the temperature, because the specific heat of the oil is lower than that of water, and the cooling effect is small. Better. At present, our company's rotary machine uses cooling water to achieve cooling effect. 4. Folding Units The folding system used in commercial rotary printing has a large number of folding methods. Generally, it is determined according to the requirements of customers, and even some multiple folding machines operate simultaneously. According to commercial requirements, most can be more than three fold, including two fold and the third knife-fold and the third parallel fold. At present, our company mainly has 8K, 16K, 24K, 32K folding machines. 5. Printing unit (pictured)
The printing unit is the core of this machine. It is mainly composed of four parts: wet, ink, plate, and eraser. Printing is accompanied by rotation. First, water is supplied and then ink is supplied. After the ink on the plate is inked, it is transferred to the blanket first, instead of being directly transferred to the paper. The rotation between the blanket cylinder and the plate cylinder is During the process, the blanket cylinder is also in contact with the roll, which transfers the text to the paper. In the printing process, the rotation of the machine is carried out at the same time, that is, some of the printing plates accept moisture, and some receive ink. At the same time, some transfer the ink on the blanket to the paper and repeat printing. We know that the transfer of ink can not be separated from the pressure, in the rotary printing, both sides of the rubber roller under pressure at the same time for ink transfer. In the actual operation, the above process is performed on all the rollers at the same time. Therefore, as shown in the figure, the paper passes through the middle and can be printed on both sides at one time, and the graphic and text can be transferred to the paper accurately and quickly. . . . . . . . . Thirty-two rotary printing features: 1 Advantages (a) Printing speed, high productivity, and can be printed on both sides. The speed of rotary printing presses can reach 100,000 sheets/hour in newspapers and 80,000 sheets/hour in commerce. Although most of them are currently 3 to 50,000 sheets/hour, their speed is higher than that of Zhang Pingji (mostly Faster than 15,000 sheets/hour), it can also be double-sided printed and folded. The output is 6-8 times that of a general four-color machine. It is more than 10 folding machines.
In order to reduce errors that may occur after the printing plate is placed on the machine, the printing plate must be rechecked before printing. The contents mainly include: blue pattern, specifications, printing stone, printing color. (School Edition)
After the proof plate, it can be fixed on the plate cylinder. In order to ensure the quality of the printed matter, it is necessary to grasp the tightness of the upper plate during the operation of the upper plate. If the plate is too loose, overprinting will occur. The printing plate bursts. (Previous edition)
In the prepress preparation process, the selected ink will be loaded into the ink fountain, and the inking device is adjusted so that the ink is uniformly transferred. In the process of applying the ink to the water, we must maintain a balance between water and ink to prevent water and ink from becoming large. Here are some highlights of prepress preparation: 1. Preparation of plates. In order to reduce errors that may occur after the printing plate is placed on the machine, the printing plate must be reviewed before printing. The contents include: plate thickness, printing plate type, color type, color tone, the distance of the printing plate, and whether the plate has irregularities Scars, foreign objects on the back of the plate, etc. Special attention should be paid to the inspection of color and tone. 2 Preparation of ink. The ink used for lithographic printing must have the characteristics of easy printing, that is, it can be smoothly drawn from each ink fountain and passed through the ink roller and printing plate to the rubber roller and printed on the surface of paper or other substrates. Offset printing is indirect printing, and has the presence of fountain solution. When the ink is transferred from the blanket cylinder to the paper surface, the amount of ink must be reduced. Therefore, the offset printing ink should have sufficient adhesion to the paper surface, acid resistance, and insolubility. Water, strong anti-emulsification, bright color, strong gloss, no discoloration after drying, no discoloration, etc. At present, the inks used in offset printing are the following: A. Bright offset printing inks. With high gloss, bright colors, clear dots and good abrasion resistance, it is an advanced resin type offset ink. It is suitable for the printing of coated high-grade paper such as coated paper and glass powdered paper. B, fast fixing offset ink. With good gloss and good fixing characteristics, it can reduce blemishes, shorten the printing cycle and increase the printing speed. Suitable for printing high quality paper and general paper. C, rotary offset ink. Web offset printing inks are used for Web offset printing and are suitable for web presses with printing speeds up to 24,000 rpm.
3 fountain solution preparation. Except in special cases, the dampening water used for offset printing is not pure water, but contains a dilute solution of various electrolytes, surfactants, and hydrophilic colloids. In order to distinguish it from the general water phase, we call the aqueous solution used for the wet-printing surface in the offset printing process a fountain solution, or water fountain solution. In order to make the fountain solution ratio and easy to use, the traditional method is to according to the provisions of the formula and the preparation method, a relatively high concentration of the solution is prepared, called fountain solution. When used, dilute the original solution with a fountain solution. Dampening reduction liquids are also often used directly to erase the dirt that is present on the blank part of the printing plate, or to overcome the drawbacks of "burning paste." Due to the gradual commercialization of offset printing raw materials, there are bottles (cans) of dampening stock sold on the domestic and foreign markets. For the convenience of transportation, sales, and use, there is also the sale of each group into tablets or powders. At present, many printing companies in China are still using the zinc-skin-based flat intaglio plate. The hydrophilic part of its blank part is the polar inorganic salt-zinc phosphate layer. It is not wear resistant and has poor chemical stability. And due to a variety of physical and chemical factors, in the printing process, the graphic part may tend to expand, resulting in "burn"; and the blank part of the hydrophilic properties will be reduced, resulting in "dirty version." In order to overcome the drawbacks of “burning†or “dirty printingâ€, one of the main technical measures is to wet the printing plate with fountain solution during the printing process so that the hydrophilicity of the blank portion remains relatively stable. Before the formal printing, the three formal printing needs a calibration process. The contents of the calibration mainly include: printing color, printing specification, tangent, angle line requirements, stains. The film outlet has been removed, the printing lines are registered, and the front and back are overprinted. There are also specific projects requested by the client or the Works Branch.
Before starting the machine, you should first wipe the paper powder on the plate with water, and then use fire water to remove the ink from the plate surface stone. Then, be optimistic about the pull gauge, adjust the double-sheet system and the blowing of the paper feeder. Officially start printing, the first printing and delivery of qualified printed sheets will be sent to the competent person for signing and approval, and then it will be officially mass-printed. In order to promptly discover the quality of printed matter, every 200-300 sheets shall be printed during the printing process. Samples are taken once and the samples taken are routinely inspected. After the printing of each sheet of the vehicle is completed, the personnel concerned must reprint the samples according to the standards to ensure that the color and quality meet the requirements. Section 3: Overview of the development of rotary printing processes for one-step printing At present, rotary printing develops rapidly. The Division also complied with the requirements of the times and set up the Ministry of Rotary Printing. Rotary printing will gradually grow.
Rotary printing, also known as rotary lithography, is the use of webs for continuous lithographic printing. Rotary printing is a kind of printing method developed in modern times. Initially, due to the undeveloped science and technology, the rotary printing press at that time was bulky, complicated in structure, inconvenient in operation, poor ink drying, difficult to control paper tension, and expensive equipment, so the market was small, but with the rapid development of science and technology , The rotary machine has greatly improved in terms of speed quality and economic efficiency, and has greatly surpassed the potential for flat sheet printing. Specifically, the history of the development of rotary printing can be divided into the following stages:
In 1865, W.Bullock pioneered a web rotary press. This can be said to be the start of rotary printing, but it must be cut before it can be printed. In 1869, the London Times technician completed the first rotary press that had been printed and then cut. This was the prototype of the current rotary press. At that time, the double-sided printing speed reached 12,000 sheets/hour. In 1930, the invention of the thermosetting ink was officially used for commercial printing. At the same time, printing in the United States began to enter the newspaper printing system, and entered the stage of rapid development.
Domestic status: Although printing has originated in China, lithographic technology has been completely introduced from foreign countries, especially the introduction of rotary lithography. This is only a matter of recent decades. In general, domestic rotation printing starts from the newspaper industry, and commercial rotary lithography has only been introduced to the country for about ten years, and our company has not introduced the rotation machine infrequently. It can be seen that there is still much potential for rotary printing in China.
Development prospects: The development of today’s era is all reflected in the common progress of the economy and culture, and the demand for it is also increasing. In the face of such a large market, rotary printing has emerged, and it has shown its rapid growth since the early 60’s. Development momentum. For example, in the United States, there were only 228 commercial rotary presses in 133 printing plants in 1961, and in January 1969 there were 729 commercial rotary presses in 286 printing plants. The turnover increased from 200 million U.S. dollars to 27 trillion U.S. dollars. In particular, in recent years, rotary printing has become the fastest growing printing method in Europe, the United States, and Japan. In the United States, after 1980, all lithographic printing machine manufacturers mainly produced rotary lithographic printing machines. It can be seen that rotary printing has an important position in the printing industry with its obvious advantages of high efficiency, high quality, and low cost. We have every reason to believe that in the upcoming new century, there will be even more splendor in rotary printing. Prospects. The structure of the second turn machine:
1. Paper supply unit Since the web press prints on a web, the paper supply system is mainly responsible for supplying paper, controlling the paper speed, tension, and edge position so that it can stably supply the paper to the printing unit. The paper supply system can be divided into two parts, one is the paper feed frame, and we can see in the figure that it is mainly used for the support and stability of the paper roll. The other part is the paper guide roller system, which is mainly used to provide the required tension of the roll paper and the left and right paper gauge positions.
2. Drying Units In commercial rotary printing, thermosetting inks are generally used. Thermosetting inks generally have high gloss and low viscosity properties. They need to be heated to a certain temperature to be dry, that is, most of the solvents in the ink evaporate when they pass through the drying oven. This allows the ink and the pigment in the ink to evaporate. Through the cooling roller fixed on the paper surface. Most of the current use of hot air drying, fuel for liquefied petroleum gas. At present, our company is using this drying method. 3. Cooling unit paper through the drying box, the temperature is high, the paper surface temperature up to 120-150 °C, the ink is still viscous at high temperatures, so after cooling and curing, so that the surface temperature is reduced to about 30 °C, generally The cooling roller is used to cool the circulating water, and the contact area between the roller and the paper is increased as much as possible to increase the cooling effect. In recent years, cooling cycle oil has also been used to reduce the temperature, because the specific heat of the oil is lower than that of water, and the cooling effect is small. Better. At present, our company's rotary machine uses cooling water to achieve cooling effect. 4. Folding Units The folding system used in commercial rotary printing has a large number of folding methods. Generally, it is determined according to the requirements of customers, and even some multiple folding machines operate simultaneously. According to commercial requirements, most can be more than three fold, including two fold and the third knife-fold and the third parallel fold. At present, our company mainly has 8K, 16K, 24K, 32K folding machines. 5. Printing unit (pictured)
The printing unit is the core of this machine. It is mainly composed of four parts: wet, ink, plate, and eraser. Printing is accompanied by rotation. First, water is supplied and then ink is supplied. After the ink on the plate is inked, it is transferred to the blanket first, instead of being directly transferred to the paper. The rotation between the blanket cylinder and the plate cylinder is During the process, the blanket cylinder is also in contact with the roll, which transfers the text to the paper. In the printing process, the rotation of the machine is carried out at the same time, that is, some of the printing plates accept moisture, and some receive ink. At the same time, some transfer the ink on the blanket to the paper and repeat printing. We know that the transfer of ink can not be separated from the pressure, in the rotary printing, both sides of the rubber roller under pressure at the same time for ink transfer. In the actual operation, the above process is performed on all the rollers at the same time. Therefore, as shown in the figure, the paper passes through the middle and can be printed on both sides at one time, and the graphic and text can be transferred to the paper accurately and quickly. . . . . . . . . Thirty-two rotary printing features: 1 Advantages (a) Printing speed, high productivity, and can be printed on both sides. The speed of rotary printing presses can reach 100,000 sheets/hour in newspapers and 80,000 sheets/hour in commerce. Although most of them are currently 3 to 50,000 sheets/hour, their speed is higher than that of Zhang Pingji (mostly Faster than 15,000 sheets/hour), it can also be double-sided printed and folded. The output is 6-8 times that of a general four-color machine. It is more than 10 folding machines.
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