What kinds of screen printing machines are there?

(1) plane screen printing machine. Using flat screen to print on a flat substrate, generally, the scraper moves horizontally against the printing plate, and the substrate is changed through the ups and downs of the printing plate.

(2) Curved screen printing machine. Plane screen printing is used on a circular substrate. Generally, the scraper is fixed, the printing plate moves horizontally, and the substrate rotates with the printing plate at the same linear speed.

(3) Rotary screen printing machine. Screen printing plates are printed by roller, and wedge-shaped ink scraping plates or rollers are installed in the roller, and the linear speed of printing plate rotation and substrate movement is the same.

(4) Electrostatic screen printing machine. Stainless steel screen printing with good conductivity is used, and black and pink are driven by static electricity between positive and negative electrode plates to pass through the through holes of the printing plate and attach to the surface of the printed piece, which is pressureless printing. The shape of the machine varies from substrate to substrate, but it generally includes substrate input part, printing part, ink fixing and drying part and substrate collection part. The printing part consists of a screen printing plate, an electrode plate and a high voltage generator.

(5) Electrostatic screen printing: Electrostatic screen printing is a method of transferring ink from screen printing layout to printing surface by electrostatic attraction. This is a non-contact printing method, which uses a conductive wire mesh as a printing plate and connects it to the positive pole of a high-voltage power supply. The negative electrode is a metal plate parallel to the printed board; The substrate is between two layers. When printing, the toner on the printing plate is positively charged when it passes through the mesh, attracted by negative charge, dispersed on the printing surface, and then fixed by heating and other methods to form an imprint. This method is mainly used for printing on high-temperature substrates (such as steel plates).

Four generations

(1) manual screen printing machine. Generally, it is composed of hinge bracket, printing platform and screen version, and all actions are manual operation. There is a multi-station manual machine whose platen and screen frame are connected in series on a fixed central axis, and the platen (or screen frame) can rotate around the central axis to facilitate multi-color overprinting. This machine is called rotary multi-color manual screen printing machine.

(2) Semi-automatic screen printing machine. All kinds of actions in the printing process are automatic, and the rest are manual screen printing machines. It is generally called 1/4 full-automatic leveling, homogenizing and screen frame screen printing machine, and 1/2 full-automatic leveling, homogenizing, screen frame and substrate adsorption screen printing machine. In addition, the substrate can also be automatically sent to the 3/4 automatic screen printing machine.

(3) Automatic screen printing machine. Automatic printing lifting, conveying, drying and receiving stacking mechanisms are respectively added in front of and behind the 3/4 automatic screen printing machine, and the printing speed is obviously higher than that of the semi-automatic machine, which can reach more than 1500 sheets/hour.

(4) Screen printing linkage machine. It is composed of several groups of printing and drying devices and devices such as bronzing, indentation, laminating and die cutting in series. The substrate is continuously fed on the reel, with automatic unwinding, automatic winding and positioning control mechanisms, which can ensure stable speed, accurate overprinter and consistent tension. The whole machine can be controlled by computer. It is a screen printing machine with high printing efficiency and full functions.

main feature

(1) Screen printing machine is a representative printing equipment in stencil printing machine. Its printing plate is a crisscross screen woven from silk and other materials, with clear latitude and longitude. A variety of screen printing machines, such as plane, curved surface, molding, printing and dyeing, printed circuit, new rotary wheel and so on, have been produced. Among them, the new rotary screen printing machine has higher speed and productivity. It is characterized in that the screen is installed on the drum and the ink is poured into the drum. When the machine works, the drum rotates and the rubber scraper quickly prints the drawing on the printed matter.

(2) besides silk, the screen can also be made of nylon wire, copper wire, steel wire or stainless steel wire. The principle of stencil printing applied in screen printing machine originated from ancient stencil printing. There are many forms of stencil printing, such as copying stencil, stencil printing and screen printing.

(3) At first, screen printing was a manual operation. At that time, there was only one frame, one screen and one template. It was not until 1950s that screen printing realized mechanization and automation. Drum screen printing machine has a large amount of ink when printing, which is suitable for printing printed matter with thick ink layer. It can be printed on all kinds of paper, glass, wood, metal, ceramics, plastic or cloth, and can use all kinds of ink, including conductive metal ink.

principle of operation

(1) The working cycle program of flat screen flat screen printing machine takes the flat screen platform monochrome semi-automatic manual screen printing machine as an example, and its working cycle is: feeding → positioning → lowering → ink lowering plate, ink raising plate → scraping stroke → ink raising plate → ink lowering plate → lifting plate → return trip → moving positioning → receiving. (2) In the continuous loop action, as long as the function can be realized, the time occupied by each action should be as short as possible, so as to shorten the same period of each work cycle and improve work efficiency.

(3) embossing line. In the printing process, ink and silk-screen printing plate are pressed against the ink plate, so that the silk-screen printing plate and the substrate form a contact line, which is called nip. This line is on the edge of the doctor blade, and countless indentation lines form the printing surface. Because the printing stroke is a dynamic process, it is difficult to achieve an ideal nip.

(4) The working principle of screen printing machine. 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 scraper squeezes the ink and the screen printing plate in motion, and the screen printing plate and the substrate form an indentation line; Due to the tension of screen N 1 and N2, a force F2 is generated on the screen, so that the screen does not contact the substrate except the nip, and the ink is squeezed in the screen.

(5) In the printing process, the screen printing plate moves relative to the squeegee, and the extrusion force F 1 and the resilience F2 also move synchronously. Under the action of resilience, the screen returns to be out of contact with the substrate in time to avoid friction marks. That is to say, the screen constantly deforms and rebounds during the printing process.

(6) After the unidirectional printing is completed, the ink scraping plate and the screen printing plate are separated from the substrate together, and at the same time, the ink flows back, that is, a printing cycle is completed. The distance between the top of the substrate and the back of the screen printing plate after ink return is called the same plate spacing or screen spacing, which should generally be 2 ~ 5 mm When printing by hand, the proficiency of the operator directly affects the formation of the nip. Screen printing workers have accumulated a lot of valuable experience in practice, which can be summarized as six points, that is, to ensure the straightness, uniformity, equiangular, pressure uniformity, centering and vertical edge of the scraper in motion. That is to say, when printing, the scraper should go straight, and can't shake from side to side; Can't be slow before, fast before, slow after, and can't be slow and fast; The inclination angle of the ink board should be kept constant, and special attention should be paid to overcoming the common problem of gradually increasing inclination angle; Printing pressure should be uniform; Keep the distance between the scraper and the inner sides of the screen frame equal; Keep the ink board perpendicular to the border.