Flat pressing die cutting technology of the hottes

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Carton flat pressing die cutting technology and analysis of related problems (II)

(II) die cutting part

the die cutting part is the core of the die cutting machine, and the die cutting plate and die cutting base plate are the most basic components. To ensure high-quality die-cutting, die-cutting plate production is very critical. Among them, the process of opening connection points and sticking sponge strips is the most representative of the manufacturing level

1. connection opening point

connection opening point is to open a small opening with a certain width at the edge of the die-cutting blade, so that the carton and the waste are locally connected during the die-cutting process, and will not be scattered during the die-cutting process. It used to be that operators used their own tools to open the connection points. This has many disadvantages, such as: the connection points are different in size; Die cutting edge deformation occurs at the opening point. Now many manufacturers have used special disconnect points. Taking the connecting point opener used by Sichuan Wuniu company as an example, its working principle is to make connecting points on the die-cutting knife by using the grinding wheel of various thicknesses according to the different thickness of the paper. In this way, the size of the connecting points is uniform, without hurting the knife, and the depth is moderate. Generally, 0.3mm thick grinding wheel is used for paper with a ration of 200-250g/m2, 0.4mm thick grinding wheel is used for paper with a ration of 250-350g/m2, 0.5mm thick grinding wheel is used for paper with a ration of 350-450g/m2, and 0.8mm thick grinding wheel is used for paperboard

or corrugated paperboard. No matter the size of the connecting point, it should be opened in the concealed place of the packing box to avoid affecting the appearance

2. sticking sponge adhesive strips

high quality sponge adhesive strips have the properties of long-lasting elasticity and rapid rebound, which can ensure the rapid withdrawal of paperboard and corrugated board, improve the die-cutting speed, and avoid the paper from being broken and fuzzed. The sponge rubber strip is usually pasted 1mm away from the die-cutting knife and 1.5mm higher than the die-cutting knife. According to hardness, sponge adhesive strips can be divided into 25 °, 30 °. 35 °, 55 ° and 60 ° arch adhesive strips. Due to the improvement of die-cutting technology, the former method of sponge sticking from head to tail has been changed. Generally, 55 ° sponge adhesive strips are stuck at the narrow seams; The 60 ° arch shaped adhesive strip is pasted between the connecting point and the knife line

3. making of die-cutting base plate

after the die-cutting base plate is made, it can be loaded into the die-cutting frame to make the die-cutting base plate. At present, the applied die-cutting base plates mainly include manual base plate, indentation strip base plate, fiber base plate and steel base plate. Although the speed of hand-made bottom template is relatively slow and the die-cutting precision is not high, there is still a certain market demand for hand-made bottom template because there are many packaging live parts with a small number and a large variety, and the cost of hand-made bottom template is low. At present, it is a fast, flexible and convenient method to make bottom template with indentation strip. The fiber bottom template is used together with the laser die-cutting template. It is generally used for the bottom template of small packaging boxes where it is difficult to make long version or indentation strips. At present, the steel bottom template is the most stable and effective bottom template in the flat pressing and flat die cutting. The products produced by die cutting can be comparable to the products produced by circular pressing and circular die cutting, but they are usually used together with sandwich die cutting or resin fiber die

cutting, which will increase the production cost. Therefore, they are usually used only when die cutting such large quantities of live parts as cigarette packs

4. problems in the process of die cutting

(1) the die cutting accuracy is not high

the reasons for the low accuracy are the problems of the die cutting version body and the printing materials. Handmade die-cutting plate has large error; The different working environment between die-cutting indentation and printing will cause paper deformation, resulting in inaccurate position of die-cutting indentation, especially the deformation of paper after glazing and coating, which will affect the die-cutting accuracy. Solution: select advanced plate making method to improve the precision of die-cutting plate; Try to ensure that the die cutting indentation and printing are carried out under the same operating environment or the same operating environment (i.e. the same temperature, humidity, etc.); On the glazing and lamination of the printing sheet to carry out die-cutting pretreatment, to minimize the impact of paper deformation on die-cutting accuracy

(2) die cutting indentation produces burst lines and dark lines

"burst lines" refers to that the pressure of die cutting indentation exceeds the bearing limit of paperboard fiber, resulting in the fracture or partial fracture of paperboard fiber The "blank line" refers to the unnecessary indentation line. It is generally caused by improper selection of die-cutting plate and indentation steel wire, improper adjustment of die-cutting pressure, poor paper quality, inconsistency between the fiber direction of the paper and the cutting direction of the die-cutting plate, or the low water content of the paper, resulting in the decline of paper flexibility

solution: select the appropriate die cutting plate; Properly adjust the pressure of the die-cutting machine; Before die cutting, the paper to be die cut shall be placed for a period of time between the successful holding of the 109th Shanghai Industrial Expo, 2017 world robot conference, 2017 world Intelligent Manufacturing Conference and other important activities; Increase the humidity of the workshop environment

there is another special case, that is, when die cutting the small box of the hard box cigarette pack, because the distance between the indentation lines at many positions is very close, if one hand grabs the production capacity and configures the height of the indentation steel line according to the normal situation, the excessive tension on the paper during die pressing will also cause wire burst. Therefore, try to minimize the tension on the paper. There are two methods: one is to reduce the height of indentation steel wire; the other is to reduce the thickness of indentation bottom mold strip. The two cannot be used at the same time, otherwise it will not have a good indentation effect. The better method is to reduce the height of the indentation steel wire, which is usually 0.1-0.2mm. The specific reduction shall be determined according to the paper thickness. The paper with a ration of more than 350g/m2 shall be reduced by 0.2mm, and the paper with a ration of less than 350g/m2 shall be reduced by 0.1mm

(3) indentation line displacement. The torsion of the steel wire with insufficient indentation under the action of die cutting pressure will lead to indentation line displacement; Insufficient die cutting pressure will lead to insufficient indentation. The problem can be improved by changing the die-cutting plate and increasing the die-cutting pressure. (to be continued)

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