Flat screen curved screen printing refers to screen printing with a flat screen on a cylindrical or conical curved surface. Under certain conditions, screen printing can also be performed on curved surfaces such as elliptical surfaces, drum-shaped surfaces, and curved surfaces. The dry screen curved screen printing machine is a machine that uses a flat screen to print the above curved surface. The working principle of the flat and curved screen printing machine: a-roller support b-shaft meeting support c-inlaid support. During printing, the flat screen printing plate and the substrate move, while the squeegee is stationary.
The flat screen printing plate is clamped on the screen frame and moved by the flat screen curved screen printing machine to translate at a constant speed. Due to the friction of the screen plate, the substrate placed on the support device rotates accordingly. The linear speed of the curved surface substrate at the embossing line is the same as the moving speed of the flat screen printing plate to realize squeegee printing. Theoretically, the embossing line should be at the highest bus bar of the curved substrate, so as to increase the off-screen angle and ensure the printing quality. For the convenience of adjustment, the squeegee generally adopts the apex angle of 60°±15°, and it is required to be able to adjust the vertical degree and the upper and lower dimensions. The adjustment to vertical is to ensure that the cutting edge line does not shift laterally when adjusting up and down, and it is always aligned with the highest bus bar A; the squeegee with an apex angle of 60°±15° is used to ensure that the squeegee inclination is formed after vertical installation. a. In the actual adjustment, in order to ensure the timely separation of the flat screen printing plate and the curved substrate, the embossing line can be moved forward a little, especially when the diameter of the substrate is large, the embossing line must be offset forward, and the supporting device for curved surface printing is Various forms of special devices are designed and manufactured by users according to product requirements.
Two pairs of roller supports can be used for the curved surface printing of cylindrical containers or conical containers, bushing supports for lids and cups with a ratio of length to diameter less than 1.5, and flexible hollow containers can be supported by inflatable devices. The elliptical surface is approximately a part of the cylindrical surface and can be supported by a cylindrical inlay method. The principle of printing on the surface of the cone is basically the same as the principle of printing on the surface of the cylinder, the difference is the graphic shape of the screen printing plate and the movement form of the screen printing plate. When making a screen printing plate for printing on the surface of a cone, it is necessary to draw an expanded view of the surface of the cone, and find the center of the fan shape according to the expanded view, and then select an appropriate screen frame to make the screen printing plate. On the plate efgh that can fully accommodate the fan-shaped abed, a printing plate that conforms to the fan-shaped abed is produced. Fix the right-angle rod on the plate efgh, and install it with o as the axis to make the plate that can be rotated in a fan shape. Then, just like the surface printing of the cylinder, four rollers are used to support the substrate under the plate, the scraper is fixed, and the plate frame is moved in a fan shape, and the surface of the conical plate can be printed by pressing the scraper.
During printing, the conical bearing is in line contact with the screen printing plate under a certain squeegee pressure; when the screen printing plate moves horizontally around the axis of the fan-shaped expansion diagram, the substrate rotates synchronously on the support device. Movement; the ink is squeezed by the scraper, and the ink is leaked to the surface of the substrate to complete the printing. 3. The process of the printing machine: (1) The working cycle program of the flat screen printing machine. Taking the flat screen platform type monochrome semi-automatic hand screen printing machine as an example, one of its working cycles is: feeding the parts → positioning → setting off → lowering to the ink plate, rising back to the ink plate → scraping stroke → rising to the ink plate Plate → lower back to ink plate → lift plate → ink return stroke → release positioning → pick up. In the continuous cycle action, as long as the function can be realized, the time occupied by each action should be as short as possible to shorten the period of each work cycle and improve the work efficiency. (2) Embossing line. During the printing process, the ink and the screen printing plate are squeezed to the ink plate, so that the screen printing plate and the substrate form a contact line, which is called the embossing line. This line is at the edge of the squeegee, and countless embossed lines form the printing surface. Achieving an ideal nip line is difficult because the printing stroke is a dynamic process.
