Brief Discussion on Offset Die Cutting of Gravure Printing Machine
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The gravure printing machine is a high-efficiency, high-quality printing machine that is widely used in the production of packaging printed matter. Due to its long plate making cycle and long service life, it is particularly suitable for printing long-line, large-volume products.
The gravure printing machine is suitable for plastic film packaging and printing, and is also suitable for the production of paper printing. Among them, after the film-type printed matter is printed into a roll, the post-sequence composite bag is formed, and the cutting process is reasonable and mature, and will not be discussed here. This article only discusses the methods that should be used in the post-processing process of paper-based gravure products.
There are quite a large number of gravure products in the packaging carton category, especially the cigarette case. Now take the cigarette case production as an example, compare the traditional production process with the offline die-cutting process to analyze its advantages and disadvantages, and put forward opinions and opinions. The industry has discussed together.
The gravure printing machine adopts the production method of feeding and unloading without stopping the machine. After color-by-color printing, it is taken into a roll and taken off. After being taken offline, the roll-shaped printed matter is cut and cut by a single printing length by a calibrating cross-cutting machine. The single printed matter collected by the cut and cut is subjected to spine, indentation, die cutting, scrapping, collection, inspection and packaging; if the printed matter needs hot stamping or laser marking to be hot, it is necessary to increase the process, and the above process defects are many processes, accounting for The area is large, the number of machines used is large, and there are many people. Sometimes the offline printing of the roll printing material is interrupted in the cross-cutting process, and the precision of the sheet is exceeded. A large number of inspection personnel and a large working space are required. Because the breakage is for the next process, each print should be left at least 15mm in length, which directly causes the loss of paper and increases the production cost. If you need hot stamping and indentation, die cutting requires at least On the machine twice, the material will be deformed in the workshop turnover due to changes in air temperature and humidity, resulting in an increase in scrap rate. The above situation is relatively clear in the industry. Since all the factories use the same technology above, everyone is on the same starting line in the competition, there is no competitive pressure brought by new methods and high efficiency.
The traditional process flow will inevitably change with the development of industrial technology. The first is to change the traditional gravure winding method to the machine break, because the structure of the broken structure is low, and the offline cross-cutting machine is omitted. Process. Since the printing tension and the breaking tension are on the same tension section when the machine is broken, the breaking accuracy is more accurate than the lower thread breaking, so it is widely used in many gravure printing line production lines. Hot stamping and spine, indentation, and die-cutting processes have to be carried out in a conventional manner, and significant technological advances have taken place using this method. In order to solve the existing problems, a small number of imported machinery manufacturers have adopted the process of indentation, die cutting and collection. Although the technology has been realized now, there are many drawbacks. The analysis is as follows:
Since the gravure printing machine works under high speed without stopping the machine, the traditional paper receiving method is a method of quickly lapping the tape, and the joint is about several tens of centimeters in length as a double-layer printing material, and the gravure printing group is a rubber roller because of the embossing roller. A slight vibration can still pass, but when it enters the indentation and die-cutting station, it will cause great impact damage to the indentation-to-roller and the die-cutting roller, which will reduce its life and pass the scrap rejection after high speed. Finished product collection, irregular joints will cause collection failure of the paper stacking station. Once the stacking machine fails, it will cause the gravure printing line to stop. Therefore, when connecting the gravure printing machine, the non-stop unwinding mechanism must be designed. In order to ensure a good working condition for the butt joint method, the gravure winder winding mechanism is bulky and costly. Because the docking paper is carried out at zero speed, it is necessary to design the paper storage rack, joint strength and tension. The control is difficult, the joint success rate is not very high, and the system is expensive.
In addition, there is a technically cumbersome problem. The gravure printing machine suddenly stops after printing and in the gravure printing. If the process is in the process of printing, the gravure printing group must be depressurized for pressure. The printing is applied once, and the material at the die cutting station is kept free of paper between the stations, and the clutch must be used to separate the gravure from the post-processing section. It is also necessary to make the gravure station run the plate and then press it to the second stage before putting it into production, and keep the memory in the original phase when the pressure is pressed. After the re-input, the printing and die-cutting positions are misplaced, the mechanism is complicated, and the operation is difficult. And the high cost, but also due to the complexity of the system affects the positional accuracy, we believe that the above method is not desirable, in fact, there is no successful use of the example. Maybe you think that this view is arbitrary, can you solve it with a shaftless drive? Yes! If each of the printing units and each of the post-processing units are driven by an AC servo shaftless transmission, there is no problem as set forth above. We don't talk about how expensive the system is, and we have to consider the reliability of the entire electrical system, because the system printing manufacturer can not be equipped with maintenance personnel. Even so, we have to analyze the value is not worth doing, because the printing process needs to be consistent in speed, temperature, ink viscosity and non-stop production conditions to ensure consistent ink color, high quality prints and high quality. The yield rate, when working in each color group, requires the operator to monitor the working status of each color group to ensure that the failure cannot be stopped and the machine is shut down. The post-processing process is to perform bronzing (including cold bronzing) on the printed screen, such as spine, indentation, die-cutting, and allowing the above operations to be stopped. The shutdown does not cause a decrease in quality and an increase in waste, according to The basic requirements for printing operations and post-processing operations are different. It is contradictory to connect two different process-based operations. When the post-processing process is hot stamping, it is impossible to design a non-stop system for the film roll to be used, and the film roll must be shut down. Once the product collection and waste rejection occur, it is necessary to stop the machine and troubleshoot. For example, the continuous production will inevitably affect the printing quality and the yield rate. Once the multi-color group press is shut down and restarted from pressure, waste is conceivable.
Through the above analysis, the reel printed on the gravure printing machine is not necessary to be broken, but the reel is taken offline and the machine is connected. It is a wise choice to connect the subsequent processes that need to be processed. Firstly, after the roll print is unrolled, the position is pre-positioned by tension and position control, so that the reprinting and repositioning of the bronzing (including cold blanching) can be realized to perform the positioning of the laser mark, and then the spine, indentation, waste rejection, and finished product collection work can be performed. The whole process is continuous and in one go. Therefore, this revolutionary change completed in the post-order process can reduce the number of machines in the printing enterprise, save printing materials, reduce personnel, reduce plant area, improve yield, and reduce energy consumption. In short, there are many advantages and prospects. people. At the same time, fierce competition in the market forces you to make such a choice.
The reason for the above implementation is very clear, and the possibility is unquestionable. It is equivalent to the fact that there is a calibrating cross-cutting machine for breaking the work. Now, the function of the calibrating cross-cutting machine has been expanded, and other stations have been added. Integrated work.