Screen printer work principle introduction —
1. Plane flat screen printing machine works.
1 Plane screen printing machine working cycle program. In the case of a flat halftone screen type monochromatic semi-automatic screen printing machine, one of its work cycles is: feeding → positioning → falling off → down to the ink plate, back to the ink plate → scraping the ink stroke → rising to ink Plate → drop back to ink plate → lift version → ink return stroke → release positioning → receive.
In the continuous cycle operation, as long as the function can be realized, the time occupied by each action should be as short as possible, so as to shorten each working cycle and increase work efficiency.
3 imprinting line. During the printing process, the ink plate and the screen plate are pressed to form a contact line between the screen plate and the substrate, which is called an imprint line. This line is at the edge of the squeegee and countless lines form the print surface. It is difficult to achieve an ideal nip because the print stroke is a dynamic process.
3 screen printing machine works. Taking the commonly used hand-shaped screen plane screen printing machine as an example, the working principle of the screen printing machine can be described as follows: the power is transmitted by the transmission mechanism, so that the ink squeegee presses the ink and the screen printing plate during the movement to make the screen The plate and the substrate form an imprinting line. Since the screen has tensions N1 and N2, a force F2 is generated on the squeegee, and the resilience causes the screen plate not to touch the substrate except for the imprinting line. The ink is Under the effect of the squeegee’s squeezing force F1, the squeegee is leaked from the moving nip to the substrate through the mesh.
During the printing process, the screen printing plate and the squeegee are moved relative to each other, and the squeezing force F1 and the resilience F2 are also moved synchronously. Under the action of the resilience, the screen is returned to contact with the substrate in time to avoid contact. Imprinted dirty. That is, during the printing stroke, the screen is continuously deformed and rebounded.
After the squeegee completes the unidirectional printing, the squeegee is detached from the substrate together with the screen plate. At the same time, the squeegee is returned to the ink to complete a printing cycle. The distance between the upper surface of the substrate and the back surface of the screen plate after ink return is referred to as the same plate distance or net distance, and generally should be 2-5 mm. When hand-printed, the operator’s technique and proficiency influence the formation of the nip directly. In practice, screen printers have accumulated a lot of valuable experience, which can be summed up in six points, that is, to ensure the linearity, uniform speed, equal angle, pressure equalization, neutrality, and verticality of the squeegee. In other words, the squeegee should be straight forward during printing, and cannot be shaken right and left; it cannot be fast before and after it is fast, and it can be slow or fast before and after it is fast; the angle of inclination to the ink plate should be kept constant, and special attention should be paid to overcoming the tilt angle. Gradually increase the common problem; printing pressure should be kept uniform; keep the distance between the squeegee and the inner side of the mesh frame equal; and keep the ink plate and frame vertical.
2. Flat screen surface printing machine works. Flat screen surface screen printing refers to screen printing with a flat screen on a cylindrical or conical surface. Under certain conditions, it is also possible to perform screen printing on curved surfaces such as elliptical surfaces, drum surfaces, and arc surfaces.
Dry-net curved surface screen printing machine is a machine that adopts a flat screen plate to print on the curved surface.
The principle of flat screen printer with a curved surface a-roller bearing b-axis will support c-mosaic bearing. 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 the flat screen curved screen printing machine moves at a uniform speed. The printing material placed on the supporting device rotates due to the friction of the screen plate. The line speed of the curved substrate at the nip line is the same as the speed of the flat screen plate to realize the squeegee printing.
Theoretically, the embossing line should be at the highest busbar of the surface printing substrate to facilitate increasing the off-web angle and ensuring the printing quality. For the convenience of adjustment, the squeegee generally adopts an apex angle of 60°±15°, and it is required to be able to adjust the vertical degree and the up-and-down dimension. Adjustment to vertical is to ensure that the edge line does not produce lateral shift when adjusting up and down, and always aligns with the highest bus A; the squeegee with vertical angle of 60°±15° is used to ensure that the squeegee angle is formed after vertical installation. α. In actual adjustment, in order to ensure that the plane screen printing plate and the surface printing material are detached in time, the imprinting line may be slightly forward. In particular, when the substrate diameter is relatively large, the imprinting line must be located forward. The support device for the curved printing is All kinds of special devices are designed and manufactured by the user according to the product requirements.
Cylindrical containers or conical containers can be printed with two pairs of roller bearings on the curved surface, sleeve-type and cup-type bushing bearings with a length to diameter ratio of less than 1.5, and flexible hollow containers can be supported by inflatable devices. The ellipse is approximately a part of a cylindrical surface that can be supported by a cylindrical mosaic.
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 the screen printing plate used for the surface printing of the cone, it is necessary to first draw the unfolded view of the surface of the cone, and find the center of the sector based on the unfolded view, and then select the appropriate frame to make the screen plate.
On a version of efgh that can completely accommodate the fan-shaped abed, a printing plate conforming to the fan shape is produced. Fix the right-angle bar on the version efgh and install the o-axis as a fan-shaped version. Then, as with the printing of the surface of the cylinder, four rollers are used to support the substrate under the plate, the blade is fixed, and the plate is moved in a fan shape, and the surface of the cone plate can be printed by pressing the blade. During printing, the conical printing is brought into 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 development drawing, the printing material is rotated synchronously on the supporting device. Sports; ink under the pressure of the squeegee, missed to the surface of the substrate to complete the printing.