Key technologies for successful gravure printing
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Gravure printing is currently the most widely used printing technology in China's flexible packaging industry. In all flexible packaging printing equipment in the country, gravure printing equipment accounts for more than 94%. Gravure printing technology is widely used in PVDC, PET, PE, NY, CPP, OPP, BOPP and other films and composite films. The printed packaging products cover the food industry, beverage industry, pharmaceutical industry, etc. . According to the survey, more than 95% of flexible packaging manufacturers use gravure printing equipment for printing. As the cost of domestic high-speed gravure presses continues to decline, the market share of gravure printing will continue to increase.
However, domestic gravure packaging equipment manufacturing industry still has a considerable gap compared with developed countries (especially Europe). Therefore, we should accelerate the development and promotion of several key technologies for gravure printing, including electronic shaft transmission technology and printing. Cars and sleeve-type impression cylinders, as well as green water-based inks and equipment, wire processing technology and equipment.
First, electronic shaft transmission technology
The electronic shaft driven gravure printing machine is a new type of high speed gravure printing machine that replaces the traditional mechanical gear with high precision virtual electronic long shaft and electronic gear. The machine receives and discharges the parts (for variable frequency control), the receiving and pulling parts are discharged, and each printing unit is driven by a servo motor alone, which is adjusted by high-precision motion control to achieve synchronous operation.
Electronic Shaft Drive Gravure Press Each print unit is a standard unit that can be arbitrarily increased or decreased and interchanged. The utility model not only has a compact structure, but also eliminates the execution mechanism of the color version between the color groups, improves the stability of the whole machine, and is convenient for operation and maintenance. For easy and quick change of the plate roll, each printing unit is equipped with an interchangeable upper plate.
The tension system is a high precision closed loop servo system. The system is perfectly integrated with the electronic spindle and registration system to ensure the superior performance of the equipment, as well as significantly reduce downtime and scrap rate, thus bringing benefits to the printing enterprise.
From conception to application, shaftless transmission technology has experienced many years of development in China. So far, we have not only seen the shaftless transmission technology in the field of offset printing, but also the corresponding equipments, such as Manroland, KBA, Goss, and Beiren, in the gravure field, although it lags behind Well-known foreign manufacturers, domestic manufacturers have successfully applied the shaftless transmission technology to the equipment, which has effectively accelerated the development of gravure printing in China and improved the quality of gravure printing products.
The double-discharge and paper-receiving gravure printing machine manufactured by Zhongshan Songde Co., Ltd., which represents the technical strength of domestic gravure printing equipment, is currently the largest electronic shaft gravure printing machine in China. It has undergone many technical transformations and has many remarkable features. advantage. For example: using the latest electronic shaft drive technology; suitable for paper and film printing; using squeegee eccentric clamping mechanism, double stroke cylinder control; multiple sets of electrostatic ink transfer device, can be installed on any color group, suitable for fine paper Printing requirements; flexible printing combination, can be used in single or dual machine, to achieve any combination of no more than 12 colors.
Others such as Xi'an Huayang's SDP650 electronic shaft drive high-speed paper gravure printing machine, this equipment has significant innovation in control, registration, paper-taking, etc., filling the domestic roll paper gravure printing machine in the field of electronic shaft transmission Blank, the main technical indicators have reached the advanced level of the current international similar products; can replace imported equipment, creating favorable conditions for domestic roll paper gravure printing machine to enter the international market.
For example, at the Shanghai International All-India Exhibition in 2006, more than 170 packaging and printing customers from the domestic and international flexible packaging industry witnessed and experienced the high-end printing equipment produced by the company in the current domestic flexible packaging manufacturing industry in front of the Huayang booth. -1050 shaftless high speed gravure press. This machine is a high-end model developed by Xi'an Huayang Company to meet the market demand and integrates many international leading and domestic first-class new technologies and new devices in Japan and Europe.
Although the history of electronic shaft gravure printing machines is not long in the current market, its superior technical advantages make it have unlimited application prospects. With the deepening of users' understanding of this new technology and the intensification of market competition, electronics The shaft gravure press will be the undisputed best choice for flexible packaging processors to cope with the short-run market.
Second, printing trolley
The gravure car has become the standardized structure of the international high-speed gravure printing machine. European manufacturers all use the gravure trolley structure, but Asian manufacturers are only a small amount of adoption, the gap is large.
A gravure trolley, sometimes referred to as a printing trolley, refers to a mobile cart that can mount and transport gravure ink supply devices and plate cylinders. Generally, the gravure cart is composed of a combination of an ink tank, an ink pump, an ink feed and recovery line, an ink tank, a plate cylinder, and the like, and sometimes a doctor blade assembly. In actual use, the plate cylinder can be carried on the trolley, or the plate cylinder can be placed on the printing unit wall panel. Therefore, the gravure trolley can mount the entire ink supply system, plate cylinder or doctor blade assembly on a small cart. The difference between various gravure cars is mainly reflected in the way they are installed and replaced.
The gravure car has many advantages:
1 Improve the effective utilization of the machine. The use of a small cart allows for the preparation of cleaning, plate rolling and inks outside the machine, significantly reducing the downtime of product replacement, thus extending the effective production time of the machine. For short-run printing, the use of gravure cars is an indispensable condition.
2 Reduce labor intensity and improve operating environment. The operator does not have to bend over for a long time in a narrow environment. Since the trolley can be moved to a special, more spacious, light-ventilated, exhaust-ventilated place for cleaning and preparation, the concentration of volatile solvent in the operating environment can be lowered to a lower level, and the printing workshop environment can be improved.
3 Make better use of human resources. Operators and support personnel can be arranged according to the operation skills, and the auxiliary personnel are engaged in special cleaning and replacement preparation work.
4 easy to recycle and reuse. Convenient for centralized cleaning and recycling of waste liquid. This is even more important for large printers with multiple gravure presses.
Third, the sleeve type impression cylinder
The sleeve-type embossing roller is a new type of embossing cylinder that began to appear in the 1980s and has been used in gravure printing machines for various applications in Europe and the United States, including publishing, packaging and special-purpose gravure presses.
The sleeve type impression cylinder is an impression cylinder that uses a combination of a thin-walled sleeve and a mandrel. It consists of two basic parts: a special tapered mandrel and a lightweight fiberglass sleeve that covers the surface of the rubber. When a new impression cylinder needs to be replaced, high pressure gas is applied to the mandrel, and the old sleeve can be easily removed by pressure expansion. When the new sleeve is selected, it is slipped over the mandrel to release the air pressure, and the sleeve and rubber layer can be fixed in the desired position to start printing.
Compared to conventional monolithic impression cylinders, sleeve-type impression cylinders have many features:
1 Replacement operation is simple and quick. There is no need to break the strip when replacing, and the mandrel does not need to be removed from the press.
2 For an embossed position, only one mandrel is required (and the integral type requires multiple mandrels).
3 replace the outer layer of the roller, the mandrel remains stationary, and it is not necessary to spend time on the “re-encapsulation”.
The gravure printing machine of the 4-sleeve impression cylinder has a high manufacturing cost and an additional air compression system, which is why it develops slowly in China.
At present, the sleeve type impression cylinders in Europe and the United States are used for printing, packaging printing and special-purpose gravure printing machines.
Fourth, the use of green gravure materials and equipment
Actively developing environmentally-friendly and non-polluting “green” packaging and printing is the trend of the times. Therefore, vigorously developing gravure ink application is a necessary way to increase the market share of gravure printing.
Water-based ink not only meets environmental protection requirements, but also significantly reduces the emission of organic volatiles into the atmosphere, thereby reducing atmospheric pollution and improving the printing environment. It is called “green packaging” ink and is suitable for food, beverage, pharmaceutical and other products. Packaging and Printing. At the same time, it is easy to print, economical and safe, and its application range is expanding. It can be seen that in gravure printing, with the increasing environmental protection requirements and the low solvent cost, water-based inks will have broad development prospects.
Of course, water-based inks also have disadvantages. Compared with oil-based inks, solvents are slower to dry because of the slow drying time of the solvent itself. Extending the drying time is equivalent to slowing down the printing speed. In addition, when using water-based inks, it is necessary to improve the original equipment or introduce new corresponding models.
At the end of 2006, China's first self-developed digital control full-computer green environmentally-friendly water-based ink plastic gravure printing machine production line was put into use in Shanggao Industrial Park. The high-speed production line was successfully developed by Jiangxi Siwei Printing Co., Ltd. and domestic famous gravure printing machine manufacturer and gravure manufacturer. The highest printing speed can reach 180 m/min and the annual production capacity is about 5000. Ten thousand yuan.
Fifth, connection processing technology
Whether in the east or the Midwest, user demand for high-end packaging is on the rise. This will inevitably lead to the development of post-press processing technology and special post-press processing technology. Special post-press processing and extremely high-quality work are generally short-lived, requiring frequent replacement of jobs. For the crazy pursuit of high efficiency in modern society, it will inevitably lead to the development of in-line production technology. Across the entire workflow, equipment suppliers tend to offer a full range of finishing solutions.
Post-printing and post-processing is a combination of several single-printing methods such as transfer transfer, cold-hot, die-cutting unit, etc. It imposes high quality requirements on the operator, requiring it not only to know the machine structure and register device, but also to know the machine structure and register device. To understand the four printing processes and post-press processing principles, master the operation of the equipment and adjust the hue and viscosity of the ink. In general, it is necessary to pass the multi-layer training of the captain with rich experience in work, so that all aspects of skills are qualified, in order to ensure product quality.