How to adjust the upper knife and lower knife of the paper cutter?

When the paper cutter cuts the paper, due to various factors, the phenomenon of upper knife and lower knife (also known as convex knife and concave knife phenomenon) often occurs, which causes difficulties in printing registration. Here is an analysis and summary of the causes of the knife-up and knife-down phenomenon.

1. The pressure is not enough
There are two situations:

(1) The spring force of the mechanical pressure spring is not enough. At this time, the pressure must be increased. If it is not possible to increase to the maximum position, the spring needs to be replaced. Note: If one of the multiple springs is broken, you need to replace multiple springs at the same time, otherwise there will be uneven pressure, insufficient and other phenomena, resulting in the phenomenon of upper knife and lower knife.

(2) Insufficient hydraulic pressure. That is, the hydraulic oil in the oil circuit or the oil pump is not enough, resulting in insufficient pressure. At this time, it is necessary to find out the cause and take the medicine.

2. The gap between the tool holder and the slider is too large
When the wear or improper adjustment causes the gap between the knife holder and the slider to be too large (generally 0.1mm), resulting in unstable knife holder, it will cause the phenomenon of upper knife and lower knife. At this time, the gap between the tool holder and the slider needs to be readjusted.

3. Blunt knife
When cutting, you must master the cutting amount, change the tool frequently, and use a fast knife. If the knife is too blunt, it will not only affect the quality of paper cutting, but also affect the accuracy and life of the machine, and in serious cases, mechanical accidents may occur.

4. The angle of the blade is not adjusted correctly
The angle of the blade should be determined according to the paper being cut. For thin, loose and soft paper, the blade angle should be small, generally 25-30 °; for thick, solid, hard paper, the blade angle should be large, generally 30-35 °. Otherwise, the phenomenon of upper knife and lower knife is likely to occur, and the blade passivation is accelerated.

5. Blade reason
Normally, the blade is parallel to the plane of the platform. When the blade is too high or too low, the phenomenon of upper knife and lower knife is also easy to occur. At this time, the blade needs to be adjusted to be parallel to the plane of the platform.

6. The plane of the feeder (commonly known as the backer) is not perpendicular to the plane of the platform
The plane of the feeder (commonly known as the backer) is not perpendicular to the plane of the platform, and the phenomenon of upper and lower knife occurs. You need to readjust the angle of the two planes with a square ruler to make it 90 °.

7. The movement direction of the knife holder is not perpendicular to the plane of the paper feeding platform
If the gap between the knife holder and the slider is just right, you need to adjust the platform plane to be perpendicular to the movement direction of the knife holder. Generally, it is only necessary to adjust the height of the supporting rod supported by the back of the platform and the ground.

8. Paper reason
When the paper leaves the factory for a short time and is relatively soft, there is more air trapped in the paper and it is not true, and the phenomenon of upper knife and lower knife is also easy to occur during cutting.

9. Reason for operation
There are two situations: ① Do not press the catty during operation, and cut the paper directly after positioning, resulting in the phenomenon of upper knife and lower knife. When cutting, it should be compacted first, and then cut again; ② When the paper stack is pushed forward with insufficient force or excessive force, the paper is bounced back, causing the upper knife and lower knife to appear skewed. When cutting paper, you should regulate the operation.