Corrugated cardboard is made of face paper, lining paper, core paper and corrugated paper processed into corrugated corrugation by bonding. According to the needs of commodity packaging, corrugated cardboard can be processed into single-faced corrugated cardboard, three-layer corrugated cardboard, five-layer, seven-layer, eleven-layer corrugated cardboard, etc.
The functions of corrugated cardboard bonded with different corrugated shapes are also different. Even if the same quality of face paper and lining paper are used, the performance of the corrugated cardboard formed is also different due to the difference in flute shape. There are four types of corrugated flutes commonly used internationally, namely A-type flute, C-type flute, B-type flute and E-type flute. Their technical indicators and requirements are shown in Table 1. Corrugated cardboard made of A-type flute has good cushioning and has a certain elasticity, while C-type flute is inferior to A-type flute. However, its stiffness and impact resistance are better than A-type flute; B-type flute has a large arrangement density, and the surface of the corrugated cardboard made is flat, with high bearing pressure, which is suitable for printing; E-type flute is thin and dense, which shows its rigidity.
The difference between containers and non-containers lies mainly in the outer diameter, which is closely related to the type of corrugated paper. The following table lists the relationship between the inner diameter specification, manufacturing specification, and outer diameter specification of the carton in detail:
Measuring method of manufacturing size of corrugated paper boxes
The manufacturing size of the carton is the blanking size when making the box. The manufacturing size is measured based on the creasing line on the unfolded box blank. The creasing roller on the slitting machine presses a groove at the creasing line position, and the creasing line is the center line of this groove. The distance between the two creasing lines is the manufacturing size. The conversion of the manufacturing size to the inner and outer diameter size can be quickly completed through Table 2, but they also have their own measurement methods.
Corrugated paper boxes are divided into single-piece and double-piece in the manufacturing process
Single-piece is a one-page forming box, which is generally used for cartons with a smaller circumference; double-piece is also called a two-page box. Some cartons have a circumference that is too large, so they have to use two pieces of box blanks to piece together a carton, but sometimes the carton factory will use two pieces to piece together a carton of not too large size in order to use the leftovers cut off during the production process, and sometimes even four pieces are used. Compared with the one-page box, the two-page box has an additional joint, so there are some slight differences in the area calculation of the two.
Joints and backthread
The manufacturing size of the carton joint is determined according to the number of corrugated layers and the production process level. The single corrugated board is 35 ~ 40mm, the double corrugated board is 45 ~ 50mm, and the triple corrugated board is 50mm.
When calculating the unfolded area of the carton, the loss of backthread in the manufacturing process must be taken into account. The size of the backthread is determined according to the number of cardboard layers, generally 20 ~ 40mm.
In order to facilitate calculations in actual work, the rule of adding "8" plus "4" is uniformly adopted, that is, the sum of the joints and backthread in the horizontal direction is set to 8cm, and the sum of the backthread in the longitudinal direction is set to 4cm.
