Carton manufacturing process materials

Editor's note: With the development of the packaging industry, corrugated cartons have become more widely used as a means of packaging. In order to adapt to the development needs of the carton industry and promote the improvement of carton manufacturing process, technology and quality, this publication started a technical seminar on “manufacturing process and quality control of corrugated carton boxes” from this issue, and invited the associate professor Luo Guanglin of the School of Printing and Packaging of Xi’an University of Technology to write an article. , introduced in phases: the classification and structure of corrugated boxes, the production process and equipment of corrugated board, the printing of cartons, the manufacturing process and equipment of cartons, and the quality control of cartons, etc., for reference by readers.

Corrugated cardboard is widely used as a packaging material because it has the following advantages compared to traditional packaging materials:

1. Empty corrugated cartons made of corrugated cardboard are usually delivered in a folded or spread form, which makes the use of vehicles and warehouses more efficient.

2. Corrugated cardboard packaging box compared with the same volume of wooden boxes, the quality of raw materials for the same volume of wooden box 1/4 to 1/5; same as the internal size of the ordinary wooden box and plywood box, its appearance The size is much smaller; and its cost is only 2/3 to 2/5 of the same volume wooden box.

3. The corrugated cardboard box has shock-absorbing properties to avoid collision and impact of the packaged goods.

4. The production of paper and cardboard for corrugated cardboard boxes can use various types of pulp. Therefore, it is suitable for China's national conditions and can be replaced by grass.

5. Compared with the use of a large number of nails, metal wires, and metal strappings in the manufacture of wooden boxes, the metal used in the corrugated cardboard box manufacturing process requires only 5% of the former.

6. The production of corrugated cardboard boxes can be carried out on highly mechanized and automated, high-efficiency equipment, which can greatly increase production efficiency.

7. The use of corrugated cardboard boxes enables automated packaging of products, which reduces the amount of packaging work, reduces the cost of the product packaging process, and doubles the production area required by the workshop.
8. Corrugated cardboard boxes can have a good appearance, quality is very good color printing, and can play a role in the promotion of goods.
Especially in the current situation where the world's wood resources are generally insufficient, the application of corrugated boxes is of special significance.

First, the type and characteristics of corrugated cardboard

Corrugated paperboard is first processed into corrugated corrugated paper, and then the surface layer is bonded with adhesive from both sides, so that the cardboard middle layer is hollow structure, so that corrugated board has a higher strength. Its stiffness, hardness, pressure resistance, tear resistance, elongation and elasticity are all higher than those of ordinary cardboard. The cartons made from it are firmer and are more conducive to the packaged product.

(a) The shape of the corrugated

Corrugated shapes are directly related to the compressive strength of corrugated board, so it is necessary to study the corrugated shape. Corrugated curve is composed of two arcs and their connected lines. According to the radius of the wave arc radius, it is generally divided into three types: U-shaped, V-shaped, and UV-type, as shown in Figure 1-1. The peak radius of the U-shaped peak is larger and has a circular arc shape; the radius of the V-shaped peak is small and sharp; the UV type boundary is almost between the two. Figure 1-2 shows the stress-strain curve of U-type corrugated board and V-type corrugated board in plane compression test.

1.U type

This type of jaw stretch is good, so it is flexible, high energy absorption. Within the elastic limit, when the pressure is relieved, it can still be restored. However, due to the instability of the arc's stress point, the compressive strength is not high. Due to the large contact surface between the crest and the tissue paper, compared with the V-type, when the corrugated paper is manufactured, the amount of adhesive used is large, but the wear of the corrugating roller is relatively small, and the crest of the corrugated paper is crushed. The U-shape has better performance than the V-shape.

2.V type

The angle of the V-type corrugated file is generally around 90°, and the contact surface between the dome and the face paper is small, and it is easier to peel off. Due to the combined action of the two oblique lines, the compressive strength is greater. However, if the applied pressure exceeds the pressure limit it is subjected to, the scorpion type is quickly destroyed and the pressure cannot be restored after it is eliminated. V-type corrugated base paper and adhesive use less, but corrugated roller wear faster, and in the pressure collapse, corrugated paper peaks are more likely to collapse.

3.UV type

Taking the advantages of the above two types of waveforms, U-type and V-type UV-type corrugations are produced. Tests have shown that the UV type corrugated file has a high compressive strength, so the UV type is widely used. (to be continued)