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 pressure, etc., 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), and the knife holder is unstable, it will cause the upper knife and the 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 angle of the blade should be small, generally 25-30 °; for thick, solid, hard paper, the angle of the blade 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.