On the screen before printing plate plane shape selection
Screen quality is Print Quality of the premise, without a good quality screen, can not print high-quality work. Process produced the web version, the selected network, stretching, washing drying glue first version, exposure, development and other working procedure is important, but the screen shape is one of the factors affecting the printing quality. This article discusses the pre-screen flat plate shape choice.
Screen shape that is Network box Flat shape. Do version box content is generally a net increase according to papers put ink zone width in the use of box size, then consider what Moulding materials, with much material. Network box shape of the rectangle, and only in the event the selection of specific substrates of several unusual shape. For example: handkerchief Printing Using square; finished printed umbrella Advertisement Umbrella effect due to use of the triangle or isosceles trapezoid; large color printing capacity to strengthen the network box to prevent inward deformation of the election do-hexagonal; recessed barrel end of the pelvic floor with circle. In fact, a special network version of the shape of the stretching force, tension uniformity, resolution, screen printing, ink under the terms, especially in the production of fine lines, tone color printing using high mesh screen, not only to adapt to specific printer surface, but also has practical common plane. The following mechanical analysis from screen, screen printing experiments, described three aspects of practical application.
One screen plane stress analysis Screen plate is a flexible version, stretching and scraping and India are making wire mesh deformation and requires restitution, the net box bear wire transfer resilience. This resilience can be seen as stretching and scraping and India contribute to tension and friction scraper run and cover the total shear force generated due to movement force is instantaneous, manual scraping by Indian forces to control the net box force can be regarded as similar under static tension. Stretching from the 90 ° view, within the limits of flexibility in the wire, stretching the greater the tension, the more tightly screen, the more uniform tension, the better screen quality. However, tension is not 100% stretching shifted to the Web version, the major loss of tension in the net loss of frame deformation and fatigue on the screen for this contradiction, high-intensity screen, screen frame trapezoidal cross-section came into being, can improve Screen quality. However, if infinitely more Moulding timber will increase the weight of the impact of the actual operation. Frame deformation is proportional to its length, the longer the frame the greater the deformation, the greater the loss of tension, therefore, the net box shape deformation is not the same box does not meet the demand.
Circular screen frame, each action point in both directions by the vertical and horizontal screen on the back edge, back edge of the force point to the center and balance, and thus does not produce inward deformation. Hexagon box intersection nodes Shouli Bu changed relatively short six side by vertical synergies, to minimize distortion. Net frame edge looks so square, rectangular box is the smallest deformation, deformation uniformity of the best post-tension. Rectangular screen frame ratio of short side and long side of the smaller the deformation the greater the tension on the screen uniformity of the greatest impact.
2, screen printing experiments Steps: 1. With a 2cm × 2cm metal square tube bending machine bent the semicircle diameter of 40cm frame two, and then welded together. The same material again produced a hexagonal, square and rectangular screen frame.
2. System network box after a good sanding, glue on the sticky net twice, selecting 300 mesh screen at the same stretching machine stretching, tension about 8kg. Stretch the screen after the level of good standing 3 to 4 days.
3. Empty version were printed in four spot shaving.
4. With 60 lines 1 to 9 into a halftone Yang picture frame on the four networks were content to do the same plates, with each block version of 3mm clear glass in the scrape on the order of printing two most clearly Adjustment. Will be printed on a variety of shapes screen samples for comparison.
Results: a rectangular screen and uniformity of the field slightly worse under the ink, dot deformation, incomplete, there is narrowing of the phenomenon of tone. Other quality of the sample close to the same screen.
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