Domestic corrugated box die-cutting technology is widely used.

Domestic corrugated box die-cutting technology is widely used. There are mainly two processes: flat die-cutting and round die-cutting. Die-cutting includes three methods: flat pressing, round pressing and round pressing round die cutting.

1.1, flat die cutting

Flat die-cutting adopts a flat die and a flat die cutter. The blade cuts through the entire corrugated cardboard at the same time during die-cutting. The die-cutting accuracy is the highest, and the application area is wide. Materials such as adhesive, cardboard, corrugated cardboard, etc. All can be applied.

The flat die-cutting machine is divided into a vertical semi-automatic die-cutting machine and a horizontal automatic die-cutting machine. The vertical die-cutting equipment has a simple structure, convenient maintenance, easy operation and replacement of the die-cutting indentation plate, but the process is more labor-intensive Large, low production efficiency, 20 to 30 times per minute, often used for small batch production and processing.

The overall structure of the horizontal flattening die press is similar to that of a sheet-fed offset press. The whole machine is composed of a cardboard automatic input system, a molding part, a cardboard output part, electrical control, mechanical transmission, etc., and some also have automatic waste removal devices. , Work is safe and reliable, with high degree of automation and high production efficiency.

1.2, round flat die cutting

A cylindrical pressure roller is used instead of the pressure plate. Generally, the pressure-cutting roller is on the top and the die-cutting plate is on the bottom. The die-cutting is processed in a "line contact" mode, so that the pressure on the machine during molding is smaller and the distribution is even Therefore, the load of the machine is relatively stable, and larger-format die-cutting can be carried out. This method is suitable for die-cutting products with different material thicknesses. However, the general circular flattening die-cutting is to stop the rotation or one rotation, two rotations as a working cycle, so the efficiency is low, and the current use is less.

1.3, circular die cutting

The circular die-cutting machine has been in my country for more than 20 years. Its molding roller continuously rotates, so its production efficiency is the highest among all types of molding presses. The product has high die-cutting accuracy, which can be controlled within ±1 mm, and it has equipment The advantages of simple operation, safe and reliable, and long equipment use time. As far as the current die-cutting equipment for the post-press processing of corrugated boxes is concerned, circular die-cutting has become the mainstream.

The moulded plate is made of curved wooden boards and roller knives, which have higher requirements for the strength of the die-cutting knife, and the production of the knife mold is difficult and costly. It is suitable for large batch production and processing. The die-cutting method of round pressing is generally divided into hard cutting and soft cutting. The main difference is that the material of the cutting roller is a hard steel roller and the other is a soft plastic.

The hard cutting method means that the die cutter is in hard contact with the surface of the pressure roller during die cutting, so the die cutter is easier to wear and curl. The soft cutting method is to cover a layer of engineering plastic on the surface of the pressure-cutting drum. When die-cutting, the cutter can have a certain amount of cutting, so that it can not only ensure the expansion of the cutter, but also ensure complete cutting, but the plastic layer needs to be replaced regularly. Otherwise, the die-cutting size will be inaccurate due to the inconsistent line speed.

2. Common die-cutting indentation problems and countermeasures

2.1 The position of the die-cutting indentation line does not match the position of the printed product

(1) There is an error in the production process of the die cutter version. Due to the limitation of technical personnel and operating equipment, manual plate making cannot achieve the ideal die-cutting indentation accuracy. For some products that require high die-cutting accuracy, laser plate making can be used instead.

(2) Cardboard grips have different rules. If the cardboard gripping specification error is large, then it may be that the back positioning (also called secondary positioning) of the die-cutting machine is too small, which can be solved by adjusting the back positioning and increasing the back positioning and flipping distance.

(3) Die-cutting indentation and printing position are not aligned. The solution is to re-calibrate the die-cutting plate according to product requirements, and set the printing and die-cutting indentation positions. In addition, it can also be corrected by adjusting the paper conveying side positioning rule or the front positioning rule, so that the die-cutting indentation line and the printing grid are registered.

(4) In addition, the working environment of die-cutting indentation is different from that of printing, which will cause deformation or stretching of cardboard fibers, and inaccurate position of die-cutting indentation. The solution is to try to ensure that the die-cutting indentation and printing are carried out in the same working environment or to ensure the identity of the working environment (that is, the same temperature, humidity, etc.).

2.2 Die cutting accuracy is not high

There are many factors that affect the accuracy of die-cutting, mainly as follows:

(1) The main drive chain is worn and elongated, which will directly affect the positioning accuracy before die cutting. At this time, only the chain can be replaced.

(2) The intermittent mechanism is worn out, causing the tooth row to shake during the stopping or starting process, which affects the accuracy of die cutting. In this case, it generally only affects the positioning accuracy. At this time, the intermittent mechanism should be overhauled.

(3) The positioning distance of the front and rear positioning swing frame is too small. Because the length of the chain itself has a certain error, if the positioning distance is too small, the chain error cannot be eliminated during the front and rear positioning, which will affect the accuracy of die cutting. At this time, the adjustment screw of the front positioning swing frame or the cam position of the rear positioning swing frame should be adjusted so that the front and rear positioning frames can move the teeth row by 2 to 3 mm.

(4) The positioning of the upper or lower die-cutting plate is incorrect. Long-term use of the machine will cause wear of the positioning block on the die-cutting plate frame or die-cutting bottom plate, which will cause the matching clearance to be too large and reduce the accuracy of die-cutting. The positioning block should be replaced at this time.

(5) Wear of the side positioning plate is an important factor causing inaccurate side positioning. Since the amount of positioning toggle is insufficient to compensate for the amount of wear, it will cause the side positioning accuracy to deteriorate. At this time, the side positioning plate should be replaced.

(6) The pressure of the gripper is too small or uneven. If the elasticity of the movable teeth of the grippers becomes smaller due to long-term use, the paper will slip or fall off during the transfer process, which will directly affect the accuracy of die cutting; uneven pressure between the grippers may cause the paper to die Skew in the process. The movable teeth should be replaced at this time. In addition, the fixed teeth should also be consistent in level, otherwise there may be paper collisions or wrinkles after the paper is gripped, which will affect the accuracy of die cutting.

(7) The cardboard is deformed or stretched during operation, causing inaccurate "overprint", which affects the accuracy of die-cutting. Appropriate paper should be selected to reduce the impact of material defects on die-cutting accuracy.

(8) The accuracy of the operator is insufficient due to operating errors, or the die-cutting accuracy is not up to the required due to the low accuracy of the die-cutting version. At this time, professional training should be given to operators, production management requirements should be improved, or die-cutting plates should be re-made.

2.3 Burst line at the indentation (burst color)

Burst line refers to the paper cracking at the indentation when the product is die-cut or the finished product is folded. This is a frequent problem in die cutting, especially in dry weather. Specific analysis should be based on specific conditions:

(1) The paper is brittle and has low water content, especially the high-temperature polished paper, which is easy to explode during die cutting. At this time, adjust the humidity of the paper before die-cutting, and use a water-passing machine to pass water on the back of the paper to increase its moisture content, make the grade a little more flexible, and then go to the die-cutting machine. After die-cutting, if the line bursts when pasting the box, wipe water at the crease to relieve the line burst.

(2) The surface of the printed matter has a large area of deep color such as blue or black, and it is easy to explode after die cutting. No or less ink additives are added to the dark ink during printing to strengthen the adhesion of the ink on the paper and reduce color bursting and line bursting.

(3) When the thickness of the paper (board) is too large, it is easy to produce burst lines. At this time, the height of the die-cut steel wire should be selected reasonably

(4) After the steel plate is under the paper, the explosive line should be thinned.

(5) When the pressure of the die-cutting machine is too high, the line will explode. At this time, the pressure should be reduced to make the waste edges just separate.

(6) The indentation die or bottom paper is too thick, the indentation is narrow, and the line is explosive. An indentation die of appropriate thickness should be selected, and the indentation width should be moderate.

(7) The paper powder dropped from the incision accumulates in the explosive line in the groove. The operator should promptly remove clean paper, foreign matter, etc.