When the paper cutter cutting the paper,
due to various factors, the phenomenon of upper knife and lower knife (also
known as convex knife and concave knife) often appears, which brings
difficulties to the printing registration. So the printing company have
make the analyzes and summarizes the causes of the phenomenon of upper knife
and lower knife.
1. The pressure of the kilo is not enough
there are two cases:
(1) the elasticity of mechanical pressure spring is not enough. At
this time, the pressure must be increased. If it cannot be increased to the
maximum position, the spring needs to be replaced. Note: if one of the springs
is broken, it is necessary to replace multiple springs at the same time,
otherwise uneven and insufficient pressure will occur, resulting in the
phenomenon of loading and unloading.
(2) insufficient hydraulic pressure. That is, the hydraulic oil in
the oil circuit or oil pump is not enough, which leads to insufficient
pressure. At this time, it is necessary to find out the cause and suit the
remedy to the case.
2. The clearance between the tool holder and the slider is too
large
when the gap between the tool holder and the slider is too large
(generally 0.1mm) due to wear or improper adjustment, and the tool holder is
unstable, it will cause the phenomenon of loading and unloading. At this time,
it is necessary to readjust the gap between the tool holder and the slider.
3. The knife
is blunt
when cutting, it is necessary to master the cutting amount, change
the tool frequently and use the fast tool. If the knife is too blunt, it will
not only affect the quality of paper cutting, but also affect the accuracy and
service life of the machine, and even cause mechanical accidents.
4. The blade angle is not adjusted correctly
the angle of the blade should be determined according to the paper
to be cut. For thin, loose and soft paper, the blade angle should be small,
generally 25-30 degrees; for thick, solid and hard paper, the blade angle
should be large, generally 30-35 degrees. Otherwise, the phenomenon of loading
and unloading is easy to occur, and the blade passivation is accelerated.
5. Blade reason
normally, the blade is parallel to the platform plane. When the
blade is too high or too low, it is easy to get on and off. At this time,
adjust the blade to make it parallel to the platform plane.
6. The paper feeder plane (commonly known as the backer) is not
perpendicular to the platform plane
the plane of the paper feeder (commonly known as the backer) is not
perpendicular to the plane of the platform, resulting in the phenomenon of
upper knife and lower knife. It is necessary to readjust the angle of the two
planes to 90 ° with a square.
7. The movement direction of cutter base is not perpendicular to
the plane of paper feeding platform
if the clearance between the tool holder and the slider is just
right, adjust the platform plane to make it perpendicular to the motion
direction of the tool holder. Generally, it is only necessary to adjust the
height of the support rod behind the platform and supported on the ground.
8. Paper reasons
when the paper leaves the factory to printing company for a
short time and is soft, there is a lot of air trapped in the paper and it is
not solid, and it is easy to put the knife on and off when cutting.
9. Operation reason
there are two cases: � when the operation does not press the kilo, the paper is directly
cut after positioning, resulting in the phenomenon of upper and lower knife.
When cutting, you should first compact the kilo, and then cut; � when
pushing the paper pile forward, the force is insufficient or too strong, and
the paper is bounced back, resulting in skewness and knife up and knife down.
The paper cutting should be standardized operation.
