Carton Flat Press Die Cutting Technology and Analysis of Related Problems (2)

(b) Die-cutting section

The die-cut part is the core of the die-cutting machine, while the die-cut version and die-cutting master are the most basic components. To ensure high-quality die cutting, die-cut production is critical. Among them, the open point and sticking sponge tape are the most representative techniques for the production level.

1. Open point

The open point is to open a small mouth with a certain width at the edge of the die cutting knife. During the die cutting process, the paper box and the waste are locally connected and will not be scattered during the die cutting process. Originally many operators used their own tools to open the link, so there are many drawbacks, such as: the size of the point is not the same; open cutting point die cutting edge deformation. Many manufacturers now use dedicated openers. Taking the opener used by Sichuan Wuniu as an example, its working principle is to use a variety of thicknesses of abrasive discs to create a continuous point on a die cutter, depending on the thickness of the paper. This evenly opened out evenly, does not hurt the knife. Moderate depth. Typically, the basis weight of 200-250g / m2 paper using 0.3mm thick grinding wheel, 250-350g / m2 paper using a grinding wheel of 0.4mm, 350-450g / m2 paper with 0.5mm thick Grinding discs, 0.8mm thick discs for corrugated board or corrugated board. Regardless of the size of the connecting point, it should be opened in the hidden place of the box so as not to affect the appearance.

2. Stick sponge tape

The high-quality sponge strip has long-lasting elasticity and rapid rebound performance, which can ensure the rapid retreat of cardboard and corrugated cardboard, increase the cutting speed, and avoid the paper being pulled off. The sponge strips are usually placed 1 mm away from the die cutter and 1.5 mm above the die cutter. According to hardness, sponge strips can be divided into 25 °, 30 °. 35°, 55° tape and 60° arched tape. Due to the improvement of die-cutting technology, the method of sticking a sponge from scratch to the end of the past has now been changed. Generally, a 55° sponge strip is attached to a narrow seam; a 60° arched strip is attached to the connecting point and knife line. between.

3. Die-cutting plate making

After the die-cut version is completed, it can be loaded into the die-cut version of the box to make a die cut master. The currently used die-cutting bottom plate has a manual bottom plate. Indentation bottom template. Several kinds of fiber bottom stencils and steel bottom stencils. Hand-made bottom stencils, although the speed is relatively slow, die-cutting accuracy is not high, but because there are many small number of packaging jobs. There are many varieties, and the cost of hand-made bottom template is lower, so there is a certain market demand for hand-made plates. The use of indented strips to make bottom stencils is currently a fast, flexible and convenient method of production. Fiber bottom stencils are bottom stencils that work with laser die cuts and are typically used for small box bottom stencils where long live or indented bars are difficult to make. Steel bottom stencil is currently the most stable and effective bottom stencil in flat die cutting. Die cut products can be comparable to round die cut products, but they are usually matched with sandwich die cuts or resin fiber die cuts. Use, so that the production costs will increase, so it is usually only used in the die-cut cigarette packs such as large quantities of work.

4. Problems in the die-cutting process

(1) Die cutting accuracy is not high

The reason for the lack of accuracy is the problem of die-cutting, and there are also problems with prints. Hand-made die-cutting plates have a large error; die-cutting indentations can cause paper deformation due to the difference between the print indentation and the printing work environment, leading to inaccurate position of die-cutting indentations, and in particular, the deformation of paper after coating and coating is more serious. Die cutting accuracy. Solution: Select advanced plate-making methods to improve the accuracy of the die-cut version; try to ensure that the die-cutting indentations are printed under the same operating environment or ensure the same operating environment (ie, the same temperature, humidity, etc.); Light and film-covered sheets require die-cutting pre-treatment to minimize the effect of paper deformation on die-cutting accuracy.

(2) Die-cut indentation produces burst and dark lines

"Breakout" refers to the fact that the pressure of the die-cut indentation is too large and exceeds the tolerance of the cardboard fiber to cause the cardboard fibers to break or partially break. "Bonding line" refers to an indentation line that should not be present. Generally not suitable for die-cutting and indentation steel wire selection, improper die-cutting pressure adjustment, poor paper quality, inconsistency between the fiber direction of the paper and the direction of the die-cutting plate knife, or the low flexibility of the paper due to the low water content of the paper. of.

Solution: Select the appropriate die-cut version; properly adjust the pressure of the die-cutting machine; place the paper to be die-cut in the workshop for a period of time before die-cutting; increase the humidity of the workshop environment.

There is also a special case where the distance between the indentation lines in many places is very close when the hard box cigarette case is die-cut, if the height of the indentation steel line is configured as normal, the pulling force on the paper during the molding If it is too large, it can also cause a burst. Therefore, efforts should be made to minimize the tension on the paper. There are two methods: one is to reduce the height of the indentation steel wire; the other is to reduce the thickness of the creasing bottom mold strip. The two can not be used at the same time, otherwise it will not achieve a good indentation effect. The preferred method is to reduce the height of the indented steel wire. The reduced height is usually 0.1-0.2 mm. According to the paper thickness to determine the specific reduction in the amount of more than 350g / m2 paper needs to be reduced by 0.2mm, 350g / m2 below the paper is reduced by 0.1mm.

(3) Indentation line movement position. The indentation of the under-stressed steel wire under the action of die-cutting pressure will cause the indentation line to run; insufficient die-cutting pressure will cause the indentation not to be full. This problem can be improved by replacing the die plate and increasing the die cutting pressure. (to be continued)