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Working principle of flat screen curved screen printing machine

Flat screen surface screen printing refers to screen printing with flat screen on cylindrical or conical surfaces. Under certain conditions, it can also screen the oval, drum, arc and other surfaces. Dry screen curved surface screen printing machine is a machine that uses flat screen to print the above curved surface. Working principle of flat surface screen printing machine: a - roller support b - shaft support c - inlaid support. During printing, the flat screen plate and the substrate move while the ink scraper is stationary. The flat screen printing plate is clamped on the screen frame, and the flat screen curved screen printing machine moves at a constant speed. Because of the friction of the screen plate, the substrate placed on the supporting device rotates accordingly. The linear speed of the curved substrate at the embossing line is consistent with the moving speed of the plane screen printing plate to achieve ink scraping printing. In theory, the embossing line should be located at the highest bus of the curved substrate to increase the off screen angle and ensure the printing quality. For the convenience of adjustment, the doctor blade generally adopts a top angle of 60 °± 15 °, and it is required to adjust the verticality and upper and lower dimensions. The adjustment to vertical is to ensure that the cutting edge line will not produce lateral displacement when adjusting up and down, and it is always aligned with the highest bus A; The ink scraper with a top angle of 60 °± 15 ° is used to ensure the obliquity of the ink scraper after vertical installation α。 In the actual adjustment, in order to ensure that the flat screen printing plate and the curved substrate are separated in time, the embossing line can be slightly forward. Especially when the diameter of the substrate is large, the embossing line must be slightly forward. The supporting device for curved surface printing is a special device of various forms, which is designed and manufactured by the user according to the product requirements. Two pairs of roller supports can be used for curved surface printing of cylindrical or conical containers. Shaft sleeve supports can be used for covers and cups with the ratio of length to diameter less than 1.5. Flexible hollow containers can be supported by inflation devices. The elliptical surface is approximately a part of the cylindrical surface, which can be supported by the cylinder inlay method. The principle of printing on the surface of a cone is basically the same as that of printing on the surface of a cylinder. The difference is the graphic shape of the screen plate and the motion form of the screen plate. When making the screen printing plate for the cone surface printing, first draw the development diagram of the cone surface, find out the center of the sector according to the development diagram, and then select the appropriate screen frame to make the screen printing plate. On a plate that can completely contain a sector, a printing plate corresponding to the sector is made. Fix the right angle bar on the plate, and install the shaft into a plate that can be sector rotated. Then, just like the surface printing of the cylinder, four rollers are used to support the substrate under the plate, and the scraper is fixed. Move the plate frame according to the sector shape, and the scraper can be pressurized to print the surface of the conical plate. When printing, the conical bearing printing is in linear contact with the screen printing plate under a certain scraper pressure; When the screen printing plate is horizontally fan-shaped moved around the axis of the fan-shaped development diagram, the substrate rotates synchronously on the support device; The printing ink is squeezed by the scraper, and it skips to the surface of the substrate to complete the printing.

2022

Printing mode of printing machine

(1) Flat press Flat press printing machine: both the plate support and the imprint are flat (2) Circular press Round platen press (platform press): a flat bed cylinder press in which the plate support is flat and the impression is cylindrical. (3) Stop rotary printing machine Stop cyclinder press: the printing plate moves reciprocally. When it moves forward, the printing cylinder rotates for one circle. When it returns, the printing cylinder stops rotating to complete a printing process. (4) One rotary printing machine One turn printing press: a printing machine that completes a printing process by rotating the impression cylinder once every time the single evolution printing press plate table reciprocates. (5) Two rotary printing machine Two rotary printing press: a printing machine that completes a printing process when the two revolution printing press plate table moves back and forth once (6) Reciprocating printing machine Reciprocating printing press: A printing machine that can reverse printing press the printing cylinder to and fro once to complete a printing process. (7) Circular press Rotary printing press: The rotary printing press is a printing machine with cylinder shaped plate support and transfer body, which rotates completely when the printing process is completed. 4. Classification by printing ink type (1) Monochrome printing machine Monochrome printing press: A single color printing press used to print one ink color on one side of the paper during printing. (2) Two-color printing machine Two color printing press: a printing press that prints two ink colors on one side of the paper during the printing process. (3) Multicolor printing machine Multi color printing press: a printing press that prints more than two ink colors on one side of the paper during printing. (4) Double sided monochrome printing machine Double sided monochrome printing press: a printing press that prints on both sides of the paper during the printing process. (5) Two-sided multicolor printing machine Double sided multi-color printing press: a two-sided printing press in which at least two ink colors are printed on one side of the paper during the printing process.

2022

Interpretation of Printing and Glazing Process

The traditional film covering process has gone through many years, and we are no longer unfamiliar with its process. Compared with the glazing process, there are similarities and differences between the two. The so-called printing glazing is to use the field printing plate or the graphic printing plate to print one or two times of varnish on the surface of the copy that has completed the graphic printing, so as to obtain a bright and transparent film on the surface of the print. Common glazing methods include oily glazing, water-based glazing and UV glazing. Printing glazing can enhance the light resistance of the ink, increase the ability of the ink layer to prevent heat and moisture, and play a role in protecting the impression, beautifying the product, and replacing the covering film. Printing glazing is cheap and simple compared with film covering. It can be both full plate glazing and partial glazing. WeChat pictures_ 20180919105220.jpg environment protection First of all, from a purely environmental perspective, water and UV are in line with the trend. Because there are two layers of pollution, white pollution and plastic pollution. The cover after water-based glazing and UV glazing can be directly recycled without any further treatment. In addition, from the perspective of the market application environment, in addition to food, drug and cosmetic packaging, foreign live parts, even those electronic products that do not directly contact the human body, are increasingly required to use the non polluting printing method of glazing because the corporate culture advocates environmental protection and takes pride in it. With the economic exchange and cooperation of various countries, a considerable number of printing and packaging enterprises in the coastal and inland areas have external single business, while western countries have high requirements for environmental protection, and pollution-free water-based glazing and UV glazing have developed quite mature. Especially in food packaging, drug packaging and other fields, Europe has set strict standards, and the survival space of film covering and oily glazing that do not meet the standards has been very small. The traditional film covering process will not completely fade out of the market because it can increase the thickness and toughness of the paper and its good waterproof property. However, in the face of the enhancement of global environmental awareness, products are required to be recycled or biodegraded, and the film covering process must strive to improve the pollution of products, working environment and the external environment to have a greater living space. Cost and efficiency According to the actual application, the cost of lamination is higher than the cost of glazing. In the industry, the quotation of glazing generally does not exceed half of the film covering, so the traditional film covering has no advantage in cost. The speed of traditional laminating machine is 30 m/min~75 m/min, while the current online glazing equipment can fully match the speed of the printing machine, and the stability of the glazing quality has been greatly improved. Without considering the specific requirements of customers, the glazing process is more economical in terms of efficiency. It is worth noting that the multiple use of transfer film technology in recent two years has broken through the boundaries of traditional film covering, and has shown initial advantages in the application of related color boxes and cigarette packs. Characteristics of varnish There are many kinds of varnish, but the commonly used varnish can be roughly divided into three categories: oily varnish, water-based varnish and UV varnish. According to the practical application trend of varnish and the improvement of environmental protection requirements, the use of oily varnish will be reduced day by day, while the application space of water-based varnish and UV varnish is very broad. This section mainly introduces water-based varnish and UV varnish. water base varnish The water-based varnish is mainly composed of water-soluble resin and water dispersible resin. The water-based varnish is non-toxic and tasteless, which eliminates the harm to human body and the pollution to the environment. It has the characteristics of fast drying speed, good film transparency, stable performance, wide equipment adaptability, good abrasion resistance and flatness of the polished surface, wide post press processing adaptability, good heat sealing performance, safe and reliable use, convenient storage and transportation, and is increasingly popular in food, medicine Tobacco carton packaging printing enterprises attach importance to.

2022

Maintenance of printing machine

The printing press is one of the equipment with the highest utilization rate among all the equipment in the printing factory. To ensure the normal operation of the printing machine, daily maintenance is essential and necessary. Let's talk about the daily maintenance of the machine from the following aspects.

2022

Development History of Printing Press

The invention and development of the printing press plays an important role in the spread of human civilization and culture. In 1439, Gutenberg, Germany, manufactured a wooden relief printing machine. Although the vertical spiral type trigger printing machine has a simple structure, it has been used for 300 years; In 1812, Konich of Germany made the first round flat relief printing machine; In 1847, Hoy of the United States invented the rotary printing press; In 1900, it was made into a six color rotary printing press; In 1904, American Rupert invented offset printing press.

2022

Application of Heidelberg Online Glazing System

Nowadays, the surface treatment of printed matter is not only limited to hot stamping, gluing, embossing and other processes, but also chooses glazing process to improve the brightness and feel of printed matter. Glazing has been regarded as a very potential surface finishing process by printing enterprises. Major printing machinery and equipment manufacturers have also invested a lot of manpower and material resources to develop a variety of glazing equipment. Because online glazing is much more economical and better in quality than single glazing after printing, online glazing technology has been widely used and developed. Next, the author introduces and analyzes the online glazing system of Heidelberg Speed Blaster CD102-7+LY+UV+CP2000.

2022

Overview of glazing process

The glazing process can improve the surface glossiness, give special effects to the printed matter, and enable the printed matter to have functions such as moisture-proof and protection of printed pictures and texts through the leveling and matting of the glazing coating on the entire printed matter surface or local images and texts. In addition, glazing does not affect the recycling of paper, which is conducive to environmental protection. It is one of the most widely used surface finishing technologies. The glazing methods can be divided into stand-alone glazing and online glazing. Single machine glazing uses a dedicated glazing machine or calender to complete the operation. On line glazing can be carried out by using the wetting or ink feeding device of the printing unit, or by using an independent glazing unit on the printing machine. Printing and glazing can be completed at one time, with fast speed and high efficiency. There are two types of glazing devices: roller type and scraper type. Polish coating mainly includes solvent, water-based, UV varnish. Due to the poor efficacy of solvent varnish, and is not conducive to environmental protection, the scope of application is greatly limited. With water as the solvent, water-based varnish is non-toxic and tasteless, green and environmentally friendly. It has the characteristics of fast drying speed, good film transparency, stable performance, good polish surface flatness, wide post press processing adaptability, good heat sealing performance, safe and reliable use, and is increasingly valued by food, medicine, tobacco carton packaging. UV glazing can achieve instant drying without solvent volatilization, and is mainly used for glazing of high-grade paper boxes. Now, local UV glazing has become the new favorite of packaging and printing enterprises. There are various processes to achieve local UV glazing, including screen printing, flexographic printing, gravure printing and VU glazing. Mixed ink technology, reverse glazing and online UV glazing have also developed into new technologies for local UV glazing. The hybrid ink combines the advantages of UV ink and traditional ink in UV curing and oxidative polymerization drying, and improves the synergistic effect between the ink surface and UV varnish. Reverse glazing adopts traditional glazing method for local glazing, and finally uses local glazing printing to achieve high contrast effect of local images and texts, with a certain sense of hierarchy.

2022

2021 Beijing Printing International Exhibition

2022

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