How to ensure the position of the sun even 8 times

Once, the Tongliang County color printing factory in Chongqing printed a 32-page book with a front ring lining and a front page. The front ring lining had no content, and the front page had a single-color screen pattern, printed on the same paper. Due to the limitation of time and quality, the front ring lining and the front page can only be printed on folio paper, but the front page film only has 32 sets. If you use manual copying of 8 sheets, it is easy to have inconsistencies in the depth of the dots and so on. When the version of the sun even 8 times, to get a split version. How can we ensure that even the position of the sun is accurate without affecting the quality?

1. Check the film sheet

The title page is a 32-mesh screen with a size of 210mm x 145mm. The screens are surrounded by dots. The page film has 4 gauge lines and 4 corner lines.

2. Design even drying program

Since the left side of the front ring lining and the front page is blank, the right side is a 32-page front page. With the open version, it can be dried in 8 sets. Even the drying area can use only 2 left and right guide lines. The positions of the ruled lines and the four corner lines have been occupied by the pattern, and there is no space or overlap between adjacent patterns, that is, a seamless connection. Since the 32-day open book has only 4mm openings, considering the binding error, the widths of the repairable parts of the dots in the adjacent parts of the two patterns must not exceed 2mm, and the positional deviation degree of each pattern is also required. Therefore, even the drying of the cover method, accuracy and pattern position accuracy requirements are high.

3. Even drying operation

(1) Since only the left and right 2 gauges are available, first connect the left and right gauges together and copy 8 copies.

(2) On the standard coordinate paper, the eight copies of the copied standard film are pasted on a transparent film base, which requires accurate dimensions and correct positions so that the relative reference position of the continuous exposure is determined.

(3) Put the assembled gauge plate on the PS plate according to the requirements of printing machine pass and side rule, cover the PS plate with black paper or red film, only reveal the rule line, and pay attention to as few as possible Dew point, to prevent excessive exposure of the printing plate photosensitive film, resulting in waste version. After printing, show the gauge line and dry the plate for use.

(4) Use golden yellow polyester adhesive (because its thickness is much smaller than black paper, board paper, easy to paste, and shading meets requirements, does not affect the quality of the dot) stick to the upper and lower blank parts of the film, paste the film surface. In this way, the coverage can be made more accurate without affecting the quality of the outlets, and it is also convenient for covering in the next step, and it is possible to prevent the outlets from being restored due to improper covering. After the paste is done, use a sharp knife to gently scribe along the edge of the pattern with a ruler, tear off the sticker that covers the pattern, leaving a sticker that covers the blank.

(5) Match the gauge line of the film processed in Step 4 with the ruled line in Step 3, and fix the film in the direction of the foot and foot, and firmly attach the film to the PS plate. After checking and confirming that the gauges are completely coincident, cover the pattern to be exposed with black paper or red film and place other than the blank portion corresponding to the front ring lining (note that the black paper or red film is as far away from the edge of the pattern as possible, otherwise If the previous step is not affixed to the adhesive, then the cover must be close to the edge of the pattern, but it is easy to make the edge of the pattern appear to have a loss width greater than 2mm, becoming a waste version). Check and confirm the cover. The first exposure can be performed immediately after it is tightly closed. Because the film edge of the film has been pasted, the degree of vacuum in the plate press should be adjusted slightly.

(6) Repeat step 5 until a pair of exposures has been exposed (note the same exposure time) and develop. After development, it is necessary to check: 1 Whether each benchmark line is complete or not, if it is incomplete, it is necessary to observe the degree of deviation carefully, and the deviation is too large. The illustrated version has been scrapped and needs re-lighting. 2 whether there is loss of pattern, especially the loss of adjacent parts. If the loss exceeds 2mm, the version is also scrapped.

As long as each step operation method is accurate, even printing plates basically meet the printing requirements.

Source: Printing Technology