Toppan Printing

When the fixed axis swings and swings to the vertical position, they are in contact with each other to carry out imprinting. The printing is completed during the movement, the structure is relatively complicated, and the printing quality is not high. The platen swinging type is that the platen is fixed in the vertical position, and the yaw plate oscillates around its fixed axis. When the platen swings to the vertical position, the platen contacts the platen for imprinting. When the embossed plate is tilted, the printed sheet is taken out. And put the paper to be printed, at the same time, the layout is inking (Figure 5-9). This type of printer is generally only suitable for printed text, simple illustrations, forms, parts and other printed matter. The parallel stamping type is that the printing plate is fixed in a vertical position. When the platen is first arc-rolled to a vertical position, the platen is parallel to the platen, and then it is pressed in parallel to the printing plate to complete the printing. When the platen is returned, it is perpendicular, leaving the plate, and tilting and tilting. At this time, the printed sheet is taken out and then put into the paper to be printed, and the printing plate is inked. The printing press has uniform printing pressure, strong printing, good ink color, large flip angle of the printing plate, which is conducive to continuous paper, and is suitable for printing fine color pictures and quotations.

Figure 5-9 Schematic diagram of flat-press gravure printing machine

Marks, covers, etc.

Flat-press printing presses have a small print format, generally no more than four open prints and often eight open prints.

2. Flat press type letterpress printing machine

The working principle of the round-press flat printing press is that the printing plate is fixed on a flat plate table and horizontally moves back and forth, and the embossing part is a cylinder, and rotates at a predetermined position, and its linear velocity is equal to the translation speed of the platen. During printing, the impression cylinder gripper bites the paper and rotates, and the printing pressure is achieved by the pressure of the impression cylinder in contact with the platen. The platen moves back once and completes a work cycle.

In the imprinting process, since the surface is in contact with the flat surface, the flat pressure printing machine can easily obtain a large printing pressure per unit area, and the total pressure is not too large, which is advantageous for large-format printing.

According to the form of movement of the impression cylinder, a round-press flat letterpress printing machine serves several purposes:

(1) Two-rotary letterpress printing machine

The impression cylinder rotates continuously for two weeks in the same direction, and the platen moves back and forth once to complete a working cycle, so it is called two revolutions. When the impression cylinder rotates for the first week, the impression cylinder descends and contacts the platen for printing; when the impression cylinder rotates for the second round, the impression cylinder rises off the plate, and the platen moves back at this time (Figure 5-10a). ).

Figure 5-10 Schematic diagram of the motion of a letterpress flat press

The second rotary letterpress printing machine (Figure 5-11), the machine rotation is relatively stable, overprinting is also more accurate, suitable for printing higher demanding books and science and technology books.

Figure 5-11 Outline of two-rotation letterpress printing machine

(2) A rotary letterpress printing machine

Each revolution of the impression cylinder, the platen moves back and forth once to complete a working cycle. In this way, a large-diameter impression cylinder must be used. A part of the surface of the cylinder is imprinted with a larger diameter and a smaller diameter for the plate. The stage does not come into contact with the plate during the return stroke (Figure 5-1Ob). When the printing paper is the same size, the diameter of the imprinting cylinder is much larger than that of other types of printing machines, which not only increases the weight of the machine, but also limits the printing speed further.

A rotary letterpress printing machine (Figure 5-12) is suitable for printing open-faced art pictures, books and illustrations as well as trademarks and other printed materials.

Figure 5-12 Schematic diagram of a rotary letterpress printing machine

(3) stop rotary letterpress printing machine

When the impression cylinder rotates, it is printed when it comes into contact with the plate surface. Then the impression cylinder stops rotating, the platen stage makes a return stroke, and the plate passes under the notch of the impression cylinder, and the platen does not come into contact with the impression cylinder (Figure 5-10c). This type of printing press is a variable-speed movement in a round-press type printing press, the speed of the machine is limited, the rigidity of the imprinting mechanism is also poor, the printing pressure is not as good as a rotary, two-rotation printing press, so it is generally suitable for printing lead type, movable type , 25 lines / cm below the wire copper plate and the general overprint print, printing size is generally not more than half.

According to the different positions of the transfer table and the delivery table, the stop rotary rotary printing press can be divided into two types, platform type and high table type.

A platen printer (see FIG. 5-13a) feeds paper from the lower or upper side of the impression cylinder, and the delivery table provided at the other end of the feed table receives the paper.

Figure 5-13 Stop Rotary Letterpress Printing Machine

The high desk printer (Fig. 5-13b) has basically the same structure as that of the platform type. It feeds the paper from the upper side of the impression cylinder, and the delivery table collects the paper under the paper feed table.

(4) Reverse Rotary Printing Machine

The platen rotates counterclockwise during the working stroke. When the platen is returned to the stroke, the platen rotates clockwise and rises off the plate (Figure 5-10d).

3. Round press type letterpress printing machine

Both the plate device and the imprinting mechanism are in the form of a cylinder. The plate is mounted on the plate cylinder. The printing pressure is applied by the impression cylinder. The paper is pressed by the pressure between the two rollers to complete the printing. This machine is called a rotary machine. The habit of letterpress printing is called the letterpress rotary press.

Since this type of printing machine adopts a continuous rotation mode of two rollers, the two cylinders are used for line contact to imprint, which is not only simple in structure, but also relatively smooth in movement. In the printing process, it also avoids the flat-press type printing machine. It can increase the printing speed by turning on and off the inertia impact generated by the back and forth motion of the platen. It is also possible to design the printing device as a unit type, which is easy to perform double-sided and multi-color printing. Therefore, it is widely used in printing newspapers and books.

Rotary presses are divided into sheet-fed rotary presses and web-fed rotary presses depending on the type of feed.

(1) Sheet-fed rotary printing press

The printing press is automated from the paper feeding, printing, and delivery to the whole process. Its paper feeding mechanism is relatively complicated, and the paper receiving mechanism is relatively simple. Generally, the ink feeding device of swing-type ink transfer roller is used to feed the paper. There is a certain separation distance and interval time between each piece of paper, most of which are printed on one side, and the drum rotation together completes a print sheet. The paper is subjected to printing pressure and the printing speed is relatively long for the imprinting time, so the print is relatively clear, the ink is saturated, and the color is Deep, high printing quality, suitable for printing hardcover books, classics, reference books and other high-demanding prints, illustrations and other printed matter, domestic machine maximum speed of 6,000 rev / h, the normal printing capacity of 4500 ~ 5000 rev / h Figure 5-14 shows a sheet-fed letterpress rotary press.

Figure 5-14 Outline drawing of a sheet-fed letterpress rotary press