Improve flexo printing technology to improve carton structural strength (paper feeding)

Corrugated carton packaging During cargo handling, handling and storage, it is absolutely necessary that the structural strength of the carton is sufficient to protect the goods from being damaged in the process of circulation.
The shape of the carton and the strength of the cardboard will affect the structural strength of the carton. Generally, the higher the carton strength requirement, the relatively higher the relative cost of the cardboard. However, the carton manufacturer often neglects the cost burden of the cardboard strength destruction during the processing.
Corrugated board strength Each corrugated board manufacturer invests in expensive manufacturing equipment and a large amount of manpower in the manufacturing process. It is precisely controlling every link and wants to manufacture the same or higher quality corrugated board at a lower cost than the industry. .
Enhance the rigidity, compressive strength and impact strength of corrugated paperboard and the core paper type, type of corrugation, corrugation height, bonding strength and corrugation strength under the general requirement that vertical compression strength (ECT) is greater than burst strength (BS). All are closely related.
Printing and Cutting Processes Destroy Intensity In the process of printing and cutting the corrugated box manufacturing process, how to minimize the damage of the cardboard or not to damage it will undoubtedly help improve the strength of the carton and reduce the cost.
In the process of printing and cutting, there are several parts where the cardboard is easily damaged when it passes through:
1. Feed roll
2. Print plate
3. Print and cut various parts of the Pull collar
4. Rotary die cutter Die This article only discusses the effect of the paper on the carton strength of the Flexo printing machine.
General Flexo printing machine paper feeding method 1. Kickboard type (kickboard push and upper feed roller clamping combination)
The speed of the kickboard and the speed of the feed roller cannot be maintained at the same speed, the length of the paper cannot be extended, and it must be completely transported by the feed roller. The strength of the paperboard is greatly destructive and has gradually been eliminated.
2. Leading edge paper feeding (suction suction wheel and upper and lower paper feed roller clamp combination)
The speed of the transfer wheel and the speed of the feed roller can be maintained at the same speed, and the length of the feed paper can be extended to assist the feed roller to transfer the paper. The destructiveness of the cardboard strength can be controlled and reduced. Now mainstream equipment is widely used.
3. Leading edge paper (suction conveyor wheel extends directly to the printing unit)
No upper and lower feed rollers hold the paper directly to the printing unit. The strength of the paperboard is minimally damaged, and new types of equipment have not yet been commonly used.
In order to ensure the accuracy of the paper feeding speed through the printing press, the paper feeding wheel is still an indispensable device in the existing equipment. It has enough clamping force and reduces the damage to the paper board strength. Wheels should consider factors:
1. Outside diameter A feed roller actual radius B, C, D feed extrusion depth is different, the feed roller pressure point changes the transmission radius of the transmission point changes, resulting in a difference with the surface speed of the lower feed roller.
When the outer diameter is too small, the same drag force must be tighter.
2. Hardness The surface hardness of most new feed rollers is between 30 and 35 degrees.
Long-term use will gradually become hard due to factors such as time, exposure to heat and light, and abrasion. It must be checked regularly to avoid damage to corrugated cardboard. When the hardness exceeds 40 degrees, it should be replaced.
The relationship between the surface hardness and clamping tightness of the paper feed roller on the C board (set pressure 40PSI does not reach the strength of the damaged board)
3. Friction in contact with cardboard The extrusion depth of the gripping board is generally 1.2mm to 2.0mm to prevent the board from slipping when it passes through the feed roller.
The higher the coefficient of friction of the material of the feed roller, the greater the same degree of clamping can have a greater drag force.
The shape of the surface of the lower paper feed roller (smooth surface, cross pattern, horizontal grain, etc.) has a significant difference in drag force.
Improper guttering on the surface of the feed roller can affect the supporting force or the deformation space.
The maximum pressure reference value (feed roller pressure point pressure) that various corrugated cardboard can withstand is shown in Table 1.

Table 1

The above is a general paperboard reference value. The five-layer paperboard (eg, B/C) is subject to pressure at a lower value (40 psi).
4. Causes of increase in clamping pressure caused by rigid operation during flexing at high speeds 1. The thickness change caused by the pressure of the carton lid cannot be reliably transmitted.
2. It is not possible to extend the paper feed to the printing unit due to lack of friction. It is necessary to hold the grip tighter and increase the drag force.
3. The cardboard stack has too much weight to increase and must be gripped tighter to increase drag.
4. When the cardboard is strongly dropped on the paper feed deck during stacking, the grip must be tighter to increase the drag force.
5. The position of the rear backstop is large under the cardboard, and it is necessary to hold the stacker more tightly to increase the drag force.
Concluding Remarks In the face of fierce competition in the corrugated box industry, more and more factories pay attention to the upgrading of production technology, relying on their own bit by bit to accumulate, and often rely on others' experience and technology as a shortcut, but now many problems lie in the equipment. Bad, it is tricky to improve. Choosing equipment that is truly suitable for your production needs is a topic that cannot be ignored in the face of competition. (Long Sound Industrial Co., Ltd. You Lichuan)