(typogra-phicprinting press)

The characteristics of printed matter: the paper back of printed matter is slightly embossed, the edges of lines or dots are neat, and the printing ink is light in the center, and the embossed edges are under heavy pressure, so there is slight embossing.

printing characteristics: the ink color is relatively strong (the thickness of the ink layer is about 7μm). Can be printed on rough substrates. Tone reproducibility is average.

application scope: trademark, packaging, decoration and printing, newspaper printing, etc. Relief printing machines can usually be divided into three types: flat relief printing machine, circular relief printing machine and circular relief printing machine:

1. Flat relief printing machine

Flat relief printing machine is a unique printing machine in relief printing. At present, the circular disc machine and square box machine used in printing plants belong to this type. This type of printing machine produces great and uniform pressure in the printing process, which is suitable for printing trademarks, book covers, fine color pictures and other printed materials.

1. Rotary flat relief printing machine

When printing, the circular impression cylinder is in contact with the flat printing plate, and the printing speed is faster than that of the flat relief printing machine, which is beneficial to large format printing.

according to the movement form of impression cylinder, the rotary flat relief printing machine can be divided into two types: one rotary and two rotary.

3. Rotary relief printing machine

There are sheet-fed paper and web paper. High printing speed, mainly printing a large number of newspapers, books and periodicals, magazines and so on.

the process of relief printing machine

the printing process using cliche and photosensitive resin plate is: preparation before plate mounting → plate mounting → printing → quality inspection.

Preparation before plate installation

Every product needs to be printed according to the requirements of the construction order. The construction order, also known as the production notice, includes: book title, format, print run, page number, printing and binding methods, paper specifications, quality requirements, completion date, etc.

only after understanding the requirements of the construction order can the preparatory work be carried out.

First, check the printing plate, paper and ink to see if they meet the requirements. Then, check whether the machine has been adjusted, replace the printing lining, and prepare the plate-mounting tools, such as plate frame, plate holder (bottom plate) batten and cork, and measure the dimensions of each part to mount the plate.

plate mounting

The process of mounting the printing on the printing machine according to certain specifications in sequence, and making the printing quality and specifications meet the product requirements through operations such as plate padding is called plate mounting or plate loading. The layout process of the cliche is the most complicated, and the process flow is: layout and pasting → layout → underlaying → middle padding → nailing → whole layout → upping → proofing

1. Layout and pasting

Layout and pasting refer to the reasonable arrangement of the page number order of the printing plate. The printing methods commonly used in general books and periodicals are pirated printing and overprinter printing.

after printing the front side with one printing plate, the reverse side is printed without another printing plate, which is called copy printing. One printing plate can print products on both sides of the paper, and two printed sheets with the same imprint can be obtained by cutting from the middle. When pirated printing is used, it is only necessary to divide the printing plate into appropriate book posts according to the page number order of books and periodicals.

it is called overprint printing that half of the printing plate is printed on the front side of the paper first, and then the other half is printed on the back side of the paper. When overprinter printing is used, the printing plate must be divided into several whole plates according to the page number, and then a whole plate is divided into two groups of printing plates with the same number of blocks: front and back.

in addition, you can also divide the pages according to the binding method. For example, if a book is bound by horse riding, the front and back page numbers of the book should be connected together, while the middle page number version should be separated and printed into separate pages, and then the pages should be put together when binding.

1. Layout

According to the requirements of binding and folding, put the printing plates in the correct position in the order of page numbers.

13. Pad printing plate

The process of adjusting the surface pressure of printing plate is called pad printing plate. There are three methods to pad the plate: under-pad, middle-pad and upper-pad.

when the pressure on more than one third of the layout is too light or too heavy, sticking a piece of paper under the bottom plate or tearing off the paper under the bottom plate is called underlaying.

when the pressure of the layout is less than 1/3 and more than 1 square centimeter, it is called a middle pad to put paper under the cliche or scrape the back of the cliche.

the upper cushion is performed after the lower cushion and the middle cushion. First, adjust the ink color of the printing machine to basically meet the ink color when printing, and print the pad sample. Then check the pressure word by word and line by line on the mat sample, and then paste it on the impression cylinder in an orderly manner with thin paper strips until the ink color is uniform and the pressure meets the requirements.

1. Fixing printing plates

There are many types of relief printing machines, and the forms and thicknesses of printing plates are different, so the methods of fixing printing plates are different. For example, a flat lead plate is fixed to the bottom plate with small nails on a circular flat relief printing machine. LP111 sheet-fed rotary machine fastens the printing plate on the printing plate cylinder with screws, while the photosensitive resin plate is usually directly stuck on the printing plate cylinder with double-sided adhesive paper or on the film substrate wrapped outside the cylinder (the film can be taken off the machine and put on the plate, reducing the downtime when putting on the plate).

⒌ imposition

according to the requirements of the construction order, the operation of fixing the printing plate in the correct position is called imposition. Through the whole page, the size is correct, and the words, lines and page numbers are overprinted accurately. There are three methods for the whole page: drawing sample, punching sample and red sample. The whole plate work of plane cliche is carried out after the printing plate is basically fixed after the lower pad and the middle pad, and the printing plate position is knocked straight or moved with the punching plate. The curved cliche can loosen the screw that fixes the printing plate and move the printing plate. The photosensitive resin plate is glued with double-sided adhesive paper, and the printing plate can be gently lifted and then pasted again.

when installing plates, printing marks should also be installed. There are two kinds of printing marks, one is the side gauge mark, which is installed at the edge of the side gauge paper to check whether the overprint is accurate and whether there are upside down or white pages. The other is the binding folding label (also called the post code), which is installed at the outermost binding mouth of each post. The purpose is to check whether there are more posts or fewer posts when binding books and periodicals.

printing

after the imposition, you should make good preparations before printing.

The preparation work includes: piling up the paper to be printed, checking the proofs and printing samples, checking the quality of words, and preventing the problems such as bad words, broken pens and missing marks. Check whether the specifications and dimensions meet the specified requirements, and check the fastening of the printing plate to prevent the printing plate from loosening.

in the process of starting printing, it is necessary to check the quality of printed matter by sampling at any time, such as no dirt, out-of-print, out-of-print, out-of-print, etc. If problems are found, handle them in time. In printing, we should always pay attention to the operation of the machine. If we find abnormal sound, we should stop the machine for maintenance.

the photosensitive resin plate has certain elasticity and good ink transmission, and the printing pressure and ink roller pressure should be less than that of the lead plate, otherwise the printing image and text will be deformed easily, and the appropriate pressure should be that the imprint is solid but not empty. The concentration of the ink used should be higher than that of the cliche, but the amount of ink can be less than that of the cliche. When removing ink stains from the layout, wipe it with a cloth dipped in kerosene or gasoline. It is not advisable to use a hard brush.

letterpress printing

The ink supply device of the printing machine first distributes the ink evenly, and then transfers the ink to the printing plate through the ink roller.

The graphic part on the relief is much higher than the non-graphic part, so the ink can only be transferred to the graphic part of the printing plate, while the non-graphic part has no ink.

the paper feeding mechanism conveys the paper to the printing part, and under the action of printing pressure, the ink in the graphic part of the printing plate is transferred to the substrate, thus completing the printing of the printed matter at one time.

Common letterpress printing methods: movable type printing (including clay type and lead type) and flexographic printing. Only the flexible version is still widely used.

flexographic printing principle

Ink in Mo Dou, under the action of the anilox roller in flexographic printing parts, the holes of the anilox roller and the surface of the anilox roller are covered with printing ink.

the ink on the surface of the anilox roller is scraped off by the doctor blade, so that the ink only exists in the net holes of the anilox roller.

the ink in the mesh hole is transferred to the flexographic printing plate under the action of pressure.

finally, under the action of printing pressure, the ink on the printing plate is transferred to the substrate. (Lithographic PrintingPress)

Introduction of lithographic printing machine

Lithographic printing machine is different from other printing methods in that it is equipped with a water moistening device. In addition to lithographic printing machines, offset printing machines and proofing machines, they are all rotary printing machines with circular pressing.

sheet-fed and web-fed printing machines, the printing plates are all metal sheets (zinc plates, aluminum plates, etc.). Offset presses are mostly used for color printing.

Sheet-fed offset press

According to the structural design of different models and the number of colors printed at a time, the drum arrangement of the printing part can be divided into single-unit monochrome, single-unit two-color and multi-unit multi-color. Usually, the single-machine monochromator is of three-drum type, as shown in Figure 1. The two colors of the single machine set are five rollers, that is, the impression cylinder is used by two colors, as shown in Figure 2. One set of three-drum offset presses with one color, two colors, four colors, five colors and six colors, as shown in Figure 3. In addition, there is a double-sided monochrome offset press, which is composed of four rollers. There is no impression cylinder, and the paper is pressed by two blanket rollers. As shown in Figure 4, it is also called a double-sided offset press. Three-drum machines and multi-color offset presses can also be printed on both sides by adding a paper turnover mechanism, and the paper feeding and receiving parts adopt a paper pile type. Sheet-fed offset press is mainly used to print exquisite color pictures, book covers, posters, trademarks, packaging and decoration products, and double-sided adhesive press is mainly used to print the text of books and magazines.

Web offset press

Continuous double-sided printing is carried out with web, and the paper receiving part is equipped with cutting and folding devices, and some of them are also equipped with automatic paper receiving, paper tension control, ink color automatic control, registration automatic control, glazing device and drying box. Web offset press has the following types according to its use and structure: ① Four-roller type (B-B type). The arrangement of rollers is similar to that of single-sheet paper machine, and there are two types of rollers: horizontal feeding and horizontal feeding.

lithographic printing machine

The horizontal paper feeding type is a unit with one color printed on both sides, and several horizontally arranged units are set for printing several colors, as shown in Figure 5. Vertical paper feeding is to set up several vertically arranged units for printing several colors, as shown in Figure 6. ② Satellite type. There is a * * * impression cylinder in the unit, surrounded by four pairs of printing plate cylinders and blanket cylinders, which can be used for single-sided 4-color printing, and can print ordinary quality color printed matter. As shown in fig. 7. ③ Satellite +B-B type. On the basis of the satellite type, a group of B-B vertical paper feeding units is added, as shown in Figure 8. It can be used for multi-color printing on one side and monochrome printing on the other side, mainly used for color newspapers and publications. In addition, according to the requirements of different printed materials, it can form various types, and meet the requirements of printing single-sided or double-sided, single-color or multi-color on each side by changing the serial paper feeding mode. Web offset press is mainly used for large and medium-sized printing houses to print large quantities of newspapers, books and periodicals and color printed matter with short cycle.

Other categories

The number of colors in a printing process includes monochrome, double color, four color, five color and six color, and there are single-sided and double-sided printing.

main structure

its main structure consists of five parts: paper feeding, water moistening, ink feeding, printing and paper receiving. The new machine is equipped with computer-controlled ink color and registration device. Since 198s, devices for controlling water quantity have appeared again.

according to the structural design of different models and the number of colors printed at a time, the arrangement of rollers in the printing part of sheet-fed offset press can be divided into single-machine monochrome, single-machine double-color and multi-machine multi-color. Usually, single-machine monochromator is of three-drum type. The two colors of the single machine set are five-drum type, that is, the impression cylinder is used by two colors. Three-drum offset press with one unit and one color, with two colors, four colors, five colors and six colors.

In addition, there is a double-sided monochrome offset press, which consists of four rollers. Without impression cylinder, two blanket rollers press against each other, and the paper passes through the double-sided printing, which is also called a double-sided (B-B) offset press. Three-drum machines and multi-color offset presses can also be printed on both sides by adding a paper turnover mechanism, and the paper feeding and receiving parts adopt a paper pile type. Sheet-fed offset press is mainly used to print exquisite color pictures, book covers, posters, trademarks, packaging and decoration products, and double-sided adhesive press is mainly used to print the text of books and magazines.

main features

the graphic part and blank part on the printing plate surface of lithographic printing machine are almost on the same plane. Based on the principle that water and oil repel each other, it makes the graphic part water-repellent and oil-hydrophilic, and the blank part oil-repellent and hydrophilic without touching the ink. Under the pressure, the ink in the inked part is transferred to the surface of the printed matter, thus completing the printing process.

After the indirect printing method was adopted, lithographic printing machines developed rapidly, and there were many kinds, such as micro offset press for office use, large, multi-color and high-speed offset rotary press for books, newspapers and magazines, and lithographic printing machines for flat paper or web paper, single-sided printing or double-sided printing. Monochrome offset press and web offset press are representative. Computer control devices have been widely used in lithographic printing machines, and the technology is becoming more and more advanced. Plate-making equipment has also developed to use electronic color separator, and pre-coating is widely used. (Intaglio Printing Press)

Introduction of intaglio printing press

When the intaglio printing press is printing, the printing plate cylinder is inked on the whole page, and the ink in the blank part of the page is scraped off with a scraper, leaving the ink in the graphic part, then the ink passes through the paper, and is impressed on the back of the paper by impression cylinder, so that the ink in the concave part is directly transferred to the paper, and finally the printed matter is piled up or rewound through the paper receiving part.

printing mode

Gravure printing machine uses rotary direct printing mode, the printing plate is directly made on the printing plate cylinder, and the ink is fed by dipping or inkjet, and there is no ink equalizing mechanism. Because of the thick ink layer, the use of volatile quick-drying ink requires a drying device.

it can be mainly divided into:

1. The models are divided into sheet-fed gravure press and web gravure press according to the different paper used

2. It can be divided into monochrome, four-color, five-color, six-color and so on according to the number of colors printed once by the unit, and it can also be divided into single-sided printing and double-sided printing.

Main structure of gravure printing machine:

The main structure of gravure printing machine consists of five parts: paper feeding, ink feeding, printing, drying and paper receiving.

1. In the paper feeding part, the sheet-fed gravure press is a pile-type continuous sheet feeding machine, and the web-fed gravure press is a continuous sheet feeding machine.

2. In the printing part, the arrangement of the plate cylinder and the impression cylinder is vertical, horizontal and inclined, and the plate cylinder is arranged below. Generally, each unit has a printing plate cylinder and a impression cylinder. In order to increase the printing pressure, some are equipped with two impression cylinder.

3. There are direct ink feeding devices that partially immerse the printing plate cylinder in the ink tank and indirect ink feeding devices that transfer the ink to the printing plate cylinder by the ink outlet roller immersed in the ink tank, and some high-speed machines also adopt inkjet mode.

4. The drying part is hot air heated by electricity or steam, and some use infrared rays or far infrared lamp to dry printed matter.

5. In the delivery part, single sheets of paper are piled up into paper piles, and the paper roll is made by cutting and folding paper tapes or rewinding them into paper rolls. The structure of the printing part of the web multi-color gravure press has two types: unit type and satellite type. The former is to set up units according to the required color number, and each unit has a printing plate cylinder and 1 ~ 2 impression cylinder, and the paper delivery part adopts rewinding mode. Satellite four-color gravure printing machine, the printing part has a large impression cylinder and four sets of printing plate cylinders. There is also a combination of gravure printing and lithography or relief printing and die cutting to meet the different requirements of printed matter.

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