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screen printing machines
I. Types of screen printing machines
Because of the wide application range of screen printing, there are many printing methods according to their uses, printing materials and shapes, and the types of printing machines are also diverse.
the methods of screen printing can be roughly divided into plane printing and curved surface printing. Plane printing includes paper printing, long table printing and cylinder printing. Print mainly targets at advertisements, cards, metal and plastic signs and other single printed materials. Long-stage printing is continuous printing based on substrates such as roll paper and soft vinyl film. Curved surface printing is a method of printing on the outer surface of cylinder and cone, such as metal, plastic, pottery and glass.
according to its degree of automation, plane printing can be divided into: ① manual printing with scraper in hand. (2) Scraping printing of scraper is mechanical transmission, and semi-automatic printing is carried out by hand for feeding and taking out the substrate. (3) Scraping of the scraper and movement of the substrate are all fully automatic printing with mechanical transmission. The classification of screen printing machines is listed in Table 3-1.
the characteristic of manual printing is that even if the shape and size of the substrate change, as long as there are corresponding printing plates and pads and skilled printing technology, it is easy to carry out various kinds of printing. However, compared with machine printing, its printing speed is low, and the amount of ink is easy to change every time it is printed. Therefore, it is rarely used in mass printing. But it is widely used in advertising, clothing, T-shirts and other printing with few quantities and many varieties.
1. classify according to the degree of automation.
manual screen printing machine. Manual screen printing machine is usually a mechanical device composed of screen holder, hinge and workbench.
after the screen frame is fixed on the holder, all kinds of actions in the printing process, such as loading and unloading the workpiece, scraping ink, returning ink, lifting the screen frame, etc., are completely dependent on manual work, and one color is printed at a time.
Because manual screen printing is economical, simple and easy to operate, it still occupies a considerable proportion in some industries, and gradually develops from simple type to more complete function.
a. simple cross-netting frame device. The simplest screen frame clamping device can be fixed on any workbench. After clamping the screen frame, the height can be adjusted according to the substrate.
Most manual screen printing machines are made of this flat platform structure. In particular, some simple screen printing devices can be used for their own use. At present, they are widely used in rural areas and individual manual screen printing workers. As shown in Figure 3-1, 3-2, 3-3 and 3-4. Printing small paper, fabrics, etc., commonly used are these simple and convenient flat platform structures of simple screen printing tables. The screen frame is mostly made of wood, the printing pad can be made of wood and other plates, and the screen is stretched by hand. When printing, the printing plate and printing pad can be mounted with hinges (Figure 3-5).
the screen frame positioning of the above simple screen printing device mostly adopts positioning blocks.
printing device for simple screen printing, as well as screen clamp and simple manual screen printer. The screen clamp is like a hinge, which plays the role of fixing and opening and closing the screen. The handprint device has a two-way fine-tuning table for easy registration. These two devices can adjust the distance between the printing plate and the table at will, and are easy to operate and move, so they are often used for small printing tasks. As long as the operation is skilled, manual printing can also obtain good printing quality.
B. Manual screen printing machine. It is a suction manual screen printing machine, and its feeding, receiving and scraping are all manual operations. However, the printing table is equipped with a perforated plate, which is pumped by a vacuum pump when printing, and the substrate is firmly absorbed by the plate hole, which can save the trouble of manual fixing.
C. precision manual screen printing machine. This domestic screen printing machine is actually a manual version adjustment device with simple structure and complete adjustment functions. The screen holder has four-degree-of-freedom adjustment functions, which can be moved and adjusted along the X-axis, Y-axis and Z-axis, and can be angularly rotated and adjusted around the Z-axis, so as to ensure the necessary positioning of precision screen printing and the adjustment of screen distance.
The adjustment of three axial degrees of freedom is completed by the cylindrical sleeve and the adjusting screw, and the rotation in the z direction is completed by the hinge shaft, and each degree of freedom has its own locking device.
This machine is equipped with a corresponding workbench, which can print a variety of substrates, especially in the circuit board and sign industry.
in the process of screen printing of some substrates, in order to facilitate the positioning, the screen frame holder is only adjusted up and down, and the substrate is fixed on the workbench for slight adjustment in the horizontal direction, that is, only the screen frame holder is required to move in the Z direction (up and down), and the adjustment of the three degrees of freedom of X, Y and Z rotation is performed on the workbench. The most widely used manual screen printing machine with vacuum adsorption device belongs to this type, which is mainly used for printing all kinds of paper and film substrates.
D. multicolor overprint manual screen printing machine. This machine is mostly used for continuous multi-color screen overprinting. The machine can install four screen frames at a time, and the four tables rotate around a fixed axis. After rotating to the required angle, they are positioned by a positioning pin with accurate indexing to ensure the accuracy of multi-color overprinting. One or four working tables can be provided as required. This machine is suitable for printing knitwear with good ink absorption, such as T-shirts and handkerchiefs.
e. characteristics of manual printing press. Manual printing is slower than mechanical printing, and the amount of ink pressed out varies greatly each time. Due to too much or too little ink, printed matter is prone to the shortcomings of unclear words or lines. Manual printing takes a long time to master different printing technologies of various printing materials. However, in order to adapt to the diversification of printing materials, both manual printing machines and automatic printing machines are now used in screen printing.
the biggest advantage of manual printing is that no matter what changes are made in the type, shape and weight of materials, as long as there are suitable printing plates, printing tables with different sizes, skilled technology and suitable workplaces, all kinds of printing needs can be met. The operation and use of all automatic printing machines originated from manual printing, which contains all the essentials of printing technology. In this sense, it is very important to master hand printing skillfully. To learn screen printing, we must first master the preparation of ink, the addition and subtraction of pressure, the choice of materials and hardness, the choice of angle, the adjustment of the gap between the layout and the substrate, and the overprinter rules of multi-color printing. Learning screen printing should start with learning manual printing.
In manual printing, paper feeding, paper receiving, plate lifting and dropping, plate use and printing drying are all done by hand. All the working procedures can be completed by one person, but in most cases, it takes 1 ~ 2 people to complete paper feeding, paper receiving and drying, and it is common for 2 ~ 3 people to form a working group.
As mentioned above, manual printing has many advantages, so many developed countries still keep it. However, in the printing of large quantities of industrial products with high precision and consistent quality requirements, automation is often used.
② semi-automatic screen printing machine. On the basis of manual screen printing machine, the basic actions of printing, such as the reciprocating motion of ink feeding and ink returning, the lifting of printing device, the lifting of screen frame, the adsorption and registration of printed parts, blank sheet control, etc., are automatically completed by a certain mechanism according to fixed procedures, and only the upper and lower workpieces are manually carried out. This is what we usually call semi-automatic screen printing machine. Its transmission mode is generally motor-driven, mechanical transmission, pneumatic or hydraulic, mechanical-pneumatic or mechanical-rolling, etc.
The main functions of semi-automatic screen printing machine are: double motor design, two groups of motors respectively control the ascending and descending and the automation of scraper stroke; Screen spacing, ink knife angle and pressure and stop time can be adjusted; Printing platen with strong air extraction and three-way fine adjustment; With automatic net stripping device; The printing speed is 4 ~ 8 prints/hour: the maximum thickness of the substrate is 12 mm. In the automation series, semi-automatic screen printing machine is the most widely used one.
③ automatic screen printing machine. Automatic screen printing machine is a screen printing machine with automatic paper feeding, automatic printing, automatic drying and automatic paper receiving. This type of machine has advanced structure, precise parts, perfect adjustment and control system, and the printing speed can reach more than 5 prints/hour, which is suitable for large-scale continuous screen printing and can ensure the stability of printing quality.
during operation, the substrate is sent to the printing host by the feeder through the conveyor belt, and the roller on the printing host grits and bites, and printing is completed with the rotation of the roller and the movement of the screen. When the drum rotates until the paper is closed, the printed matter gradually enters the conveying belt, and the paper clips on the dryer take the printed matter one by one and walk into the drying stage, and the dried printed matter is automatically difficult to be absorbed on the paper table one by one. The printing speed of automatic screen printing machine is 85 ~ 33 prints/hour.
④ screen printing linkage machine. In fact, the screen printing linkage machine is a fully automatic screen printing production line, which is composed of an automatic feeding mechanism, one or more groups of automatic screen printing devices and drying devices in series. It can also be equipped with a series of devices such as bronzing, indentation, die cutting and edge stripping according to the needs of products. It is the most efficient and functional screen printing production equipment for printing monochrome and multicolor screen prints at present. Each link of the whole unit has a detection and control device, and each group of institutions can be controlled independently, or the whole unit can be programmed by a microcomputer.
2. Classification by screen and printing table. Screen printing machines can be classified into two types according to the form of screen and printing table.
① flat screen machine. Flat screen machine refers to a screen printing machine with a flat screen. The printing mode of dry screen can only be reciprocating intermittent, or screen plate is fixed and scraper is reciprocating, or scraper is fixed and screen plate is reciprocating. In this way, ink supply and scraping can not be carried out continuously, which increases the time of lifting and reciprocating movement in vain and limits the printing speed. The maximum printing speed of flat screen machine is about 3O printing/hour.
Flat screen screen printing machine is the most widely used variety at present. Many manufacturers engaged in the manufacture of screen printing machines have started to produce various specifications of flat screen screen printing machines according to industries and uses. For example, printed circuit boards and electronic components screen printing machines for electronic industry, screen printing machines for porcelain decal printing, screen printing machines for industrial three-dimensional articles, curved screen printing machines, printing and dyeing screen printing machines, etc.
The main motion of the flat screen screen printing machine is reciprocating, and the printing speed is low, while the main motion of the circular screen printing machine is continuous rotation, which can greatly improve the printing speed. Therefore, the circular screen printing machine is suitable for high-speed mass production and is a model with great development prospects.
a. flat screen printing machine with flat screen platform to open books. This kind of screen printing machine is a common model in plane screen printing machine. One side of its flat screen printing plate is fixed on the machine by hinges, and the screen printing plate can swing around the fixed edge, so it is also called hinge flat screen printing machine. When printing, the screen printing plate is put down and parallel to the printing table, and then the scraper moves horizontally on the printing plate to press and print; After printing, lift the screen printing plate and take out the printed piece.
there are two types of screen printing machines, manual and semi-automatic. Manual type has simple structure, convenient maintenance, low price and wide adaptability; However, the printing accuracy is not high, the technical level of the operator is required to be high, and the printing efficiency is low, so it is suitable for small batches of flat prints. Semi-automatic type can be completed by machinery except for printing the upper and lower parts, also known as semi-automatic book-opening flat screen platform plane screen printing machine or fan-shaped combined dry screen platform hand screen printing machine, as shown in Figure 3-14a. This semi-automatic screen printing machine has the advantages of high printing speed, easy adjustment of the pressure on the plate and printing stroke, good stability and better printing quality than the manual screen printing machine. The printing platform of this kind of printing machine is generally made of stainless steel and equipped with vacuum adsorption device. Its floor space is small and its operation performance is excellent. A typical model of this screen printing machine is the flat screen printing machine produced by Shanghai Bida Printing Industry Co., Ltd.. This kind of screen printing machine overcomes the shortcoming that the plate can not be lifted when ink is returned to the ordinary small screen printing machine. Under the condition of not adding extra power, the scraper can be lifted when ink is returned, which effectively prolongs the service life of screen printing plate and improves the printing quality. At the same time, the machine can also replace the scraper without removing the printing plate, which makes the operation more convenient, avoids the trouble of plate alignment after replacing the scraper and improves the accuracy of multi-color printing.
B. Flat screen printing machine with flat screen printing plate and horizontal lifting. This kind of screen printing machine is a kind of plane screen printing machine. In the printing process, the screen printing plate moves up and down in a horizontal state.
during printing, the printing plate is fixed, the printing table moves up and down in a horizontal state, and the scraper moves horizontally.
this model has the advantages of smooth operation and accurate overprinter, and is mostly used in printed circuit boards, electronic components and multi-color overprinter.
C. Horizontal movable flat screen printing machine with flat screen platform. This kind of screen printing machine, when printing, the printing plate is fixed, the printing table moves horizontally and the scraper moves horizontally, which is also called sliding table screen printing machine.
In this screen printing machine, the printing pieces are taken and placed when the printing platform slides out, so it is convenient to locate, take and place the printing pieces. It has the advantages of smooth printing and accurate overprinter, and can be used for printed circuit boards, electronic components and other flat monochrome and overprinter prints.
D. horizontal sliding screen printing machine with inclined printing table. It is a screen printing machine in which the printing table can rise (fall) horizontally in the oblique upper (lower) direction.
e. fan-shaped screen printing machine with printing table. The printing table of this machine takes the inner end as the fulcrum, which can be opened and closed up and down in a fan shape, but the space is narrow, which makes it inconvenient to exchange substrates.
F. rotary screen printing machine with printing table. There are several suction cups on the rotary printing table of this screen printing machine, which can print continuously while rotating. The feature of this model is that it can control the accuracy of printing position. Because this machine can supply and take out materials synchronously during printing, the printing efficiency is high.
g. drum screen printing machine. Drum flat screen screen printing machine is mainly a special machine invented to adapt to high-speed printing of sheet-fed substrates. The feeding, receiving, drying, conveying and palletizing of this machine are all automatic. Many countries in the world, such as Figure 3-17 printing table rotary screen printing machine, have developed roller flat screen screen printing machine, which is mainly for large-scale paper advertising printing. The principle and structure of this screen printing machine are characterized by the cylindrical printing table. The planographic printing plate and the cylinder printing table are properly meshed through racks and gears. The scraper is fixed in the center above the drum, the printing plate moves horizontally left and right, and the drum rotates at the same time. The substrate is sent to the preparation position before printing, and then rotates with the roller. There are many vacuum holes on the circumferential surface of the roller to absorb the substrate for rotary printing, but the thickness of the substrate is limited. Small rollers can only print thin substrates. The solution for printing thick substrates is to increase the diameter of the drum, but if the diameter is too large, the weight of the drum will increase and the inertia of the drum will increase. It is still difficult to control the substrate accurately and ensure the accuracy. Even if the above method can solve the accuracy problem, its speed will slow down. In order to solve the speed problem, we developed the.