The anilox roller is the main component of the quantitative ink supply system of the flexographic printing machine. It is known as the "heart" of the flexographic printing machine. The quality of the anilox roller directly affects the quality and effect of the printed matter.
The anilox roller's ink transfer performance refers to its ability to accept and transfer ink and its uniformity. The ink transfer performance of the anilox roller is related to the shape, arrangement angle and capacity of the anilox roller, as well as the number of lines of the anilox roller and the production materials. The effects of these factors on the anilox roller ink transfer performance are discussed below.
1. The shape and arrangement angle of the net hole
The shape of the openings in the top view of the mesh is rhombus and regular hexagon. The opening of the regular hexagon is larger, so the ink inking and ink transfer performance is better than the diamond. The cross-sectional shape of the mesh is generally hemispherical. The mesh wall of this shape is smooth, which is conducive to the transfer of ink. The arrangement angles of the net holes are generally (as shown in Figure 1): 30 °, 45 °, and 60 °.
The 30 ° regular hexagonal mesh hole has good ink release, but the anilox wall on the anilox roller surface causes excessive wear between the ink knife and the anilox roller, and the anilox wall will destroy the uniformity of ink flow. Therefore, it is difficult for the 30 ° regular hexagonal cells to produce a uniform ink film.
The 45 ° diamond-shaped cells work well, but the mesh walls are generally 15-20 μm wide, making the gap between the cells larger and the ink layer transferred not uniform. Moreover, the shape of the communication pipe of the 45 ° diamond-shaped hole has a tendency to be too deep. Too deep will reduce the release of ink, is not conducive to the transfer of ink, and increases the plug of ink at the bottom of the ink hole, thereby increasing the difficulty of cleaning.
For a 60 ° regular hexagonal mesh cell, due to its effective geometry, it can make the most of the space, and the 60 ° arrangement makes the mesh cell array compact, that is, it can be carved more on the surface of the anilox roller of the same area Cells of the same size transmit more ink. Through mathematical calculations, it can be seen that within the same area, the space area occupied by regular hexagonal net holes is 15% more than that of diamond-shaped net holes, which means that regular hexagonal net holes can reduce the depth of the hole by 15% without Affect the original capacity. Therefore, the 60 ° regular hexagon mesh can be carved lighter under the condition of transferring the same amount of ink, which is beneficial to the transfer of ink.
The anilox rollers arranged at 45 ° and 30 ° are generally only used for coating, laminating and some special printing aspects, and have not been used in ordinary flexographic printing. The most widely used in production is the regular hexagonal mesh 60. Anilox rollers arranged.
Second, the capacity of the net hole
The cell volume refers to the amount of ink per unit area that the anilox roller can hold under normal conditions. The unit is BCMin2 (1010μm3 / in2). The capacity of the cell is related to the depth and opening degree. When the cell volume is fixed, the depth of the cell is inversely proportional to the opening. In general, the depth of the cell is 23% to 33% of the opening (that is, the opening of the cell is 100 μm, then its depth is 23-33 μm), which is ideally 28%.
The size of the mesh capacity has a great influence on the dot gain in printing. If the cell volume is large, the amount of ink transferred is large, and the dots are easy to increase; the cell volume is small, and only very little ink is transferred to the substrate during the printing process, which is helpful to prevent the dots from increasing and flying ink. Print quality. Therefore, the smaller the capacity of the cells, the better the ink transfer requirements are. This also confirms that the hexagonal anilox rollers arranged at 60 ° are the best. This arrangement makes it possible to arrange more cells of equal volume per unit area. In the case of transferring the same amount of ink, the cells can be made smaller some.
3. Line number of anilox roller
The line number of the anilox roller refers to the number of grid holes per unit length along the axis of the anilox roller, which determines the uniformity and amount of ink transmission of the anilox roller. The higher the line number of the anilox roller, the closer the ink layer on the anilox roller is to the "continuous" state. In addition, the line number of the anilox roller has a direct relationship with its capacity, so it has a very important influence on the amount of ink transfer. When the line number of the anilox roller increases, the opening area of ​​the ink injection hole decreases and the capacity becomes smaller, so the amount of ink transfer also becomes smaller. It can be seen that the higher the anilox roller line number, the smaller the ink transfer amount.
In addition, the number of lines of the anilox roller determines its own scope of application. In general, when printing large areas of solid patches or images that do not require too much, consider using an anilox roller with a low line count: when halftone or color printing, use an anilox roll with a high line count. In order to ensure that the opening area of ​​the ink hole is smaller than the smallest dot area on the printing plate, thereby reducing the increase of the dot. The number of screen lines of the anilox roller must match the number of printed screen lines. Their ratio is about 5: 1. For individual fine products, this ratio is even higher. However, the number of lines of the anilox roller is not as high as possible. The high number of lines makes it difficult to release ink to the printing plate after the ink hole is inked, resulting in insufficient ink supply and insufficient density on the ground and flowering. Therefore, the choice of anilox rollers can not only pursue the high line number of the anilox roller, but also must consider the printing density. In actual work, the number of lines must be reasonably selected according to different grades of printed matter.
A picture frame is a protective and decorative edging for a picture, such as a painting or photograph. It makes displaying the work safer and easier and both sets the picture apart from its surroundings and aesthetically integrates it with them.
A picture frame is a container that borders the perimeter of a picture, and is used for the protection, display, and visual appreciation of objects and imagery such as photographs, canvas paintings, drawings and prints, posters, mirrors, shadow box memorabilia, and textiles.
Traditionally picture frames have been made of wood, and it remains very popular because wood frames can provide strength, be shaped in a broad range of profiles, and allow a variety of surface treatments. Other materials include metals, e.g. silver, bronze, aluminum, and stiff plastics such as polystyrene.
A frame surface may be of any color or texture. Both genuine gilding and imitation gold remain popular, although many other surfaces are to be found in most framing establishments. Some picture frames have elaborate moldings, which may refer to the subject matter. Intricate decorations are often made of molded, then gilded plaster over a wood base.
Picture frame mouldings come in a wide variety of profiles, generally in some sort of L shape with an upward "lip" and a horizontal rabbet. The rabbet functions as a shelf to hold the frame glazing (if any is to be used), some sort of spacer or mat/matte to keep the object safely behind the inner surface of the glazing, the object itself, and backing boards to protect the object from physical damage and environmental pollutants. The lip extends a proportionate distance up from the edge of the rabbet. It restrains materials in the frame and can be used to help set off or reveal the picture aesthetically.
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