Plate shears - This has nothing
to do with chocolate
The
plate shears or guillotine shears belong to the field of cutting manufacturing
technology. As the name shears or scissors suggests, only the cutting of
material is defined as a machining process.
Structure
and functionality of plate shears
With
the classic plate or guillotine shears, the cut is a straight cut. The
structure and the mode of operation are usually carried out in a vertical
construction. The main components of a guillotine shear are the plate table,
guillotine shear frame, lower cutting beam with lower knife, upper cutting beam
with upper knife, stops, hold-down device (blank- or downholder) and the drive.
The drive is usually carried out by means of one or more hydraulic cylinders
which move the upper cutting beam and the upper knife vertically up and down.
The hydraulic cylinders can attack the upper cutting beam directly or the
movement of the upper beam takes place via a toggle lever. The upper cutter beam
is guided together with the knife in the frame of the guillotine shears.
The cut takes place at the moment when the upper
knife passes the lower knife. The knives do not touch, but must be set to a
defined gap. When cutting steel, the gap, also known as the cutting gap, must
be approx. 10% of the material thickness to be cut with guillotine shears. The
cutting gap varies from material to material. The quality of the cut can also
be influenced by the cutting gap. The narrower the gap, the higher the cutting
force required. The setting values given by the manufacturers are only
recommendations and usually have to be optimized by the operators. The cutting
gap becomes smaller and smaller as the material thickness of the material to be
cut decreases. It can also go to zero, but it must be prevented that the knives
overlap. Then knives breakouts cannot be avoided. From the paper scissors is
known the effect that the cutting edges of the knives slide against each other
during the cut.
The material to be cut is in a horizontal position
between the upper and lower knife during the cut. Since the knives exert a
torque on the material to be cut during the cut, a movement (rotation) must be
absorbed. On the one hand, the material is supported on the shear table, on the
other hand, a hold-down device prevents the material from being lifted off
during the cut. The hold-down clamps the material positively during the cut.
The bottom knife of a guillotine shears is arranged
horizontally. The upper knife is arranged at an angle. This incline is normally
between 1 ° and 3 °. The more obliquely the knife of the guillotine shears is
arranged, the lower the cutting force. But the stroke of the upper cutter beam
to be carried out raises with the increase in the cutting angle. The risk of
permanent deformation of the material to be cut after the cut also increases
with the size of the cutting angle.
Another parameter for a right-angled cut is that
the two knives do not move past one another in parallel, but rather that the
upper knife is engaged by a clearance angle. A useful clearance angle is
approx. 1.5 ° (for metals). The thicker the material to be cut, the more important
it is to choose the right clearance angle for an rectangular cutting edge.
Wide range
of plate shears and guillotine shears
In the metal sector, the guillotine shears for
larger material thicknesses are equipped with hydraulic drives, as already
described. Manually operated guillotine shears are also known from the paper
and film sector. Pneumatic or electric drives are also conceivable with a
somewhat higher expenditure of force.
For the processing of large and small workpieces,
the plate and guillotine shears are available in different sizes and
performance levels. One variant is the width, which can range from a knife
length of 100 mm to widths over 10 m. The material thickness of the material to
be cut ranges from a few micrometers to a thickness of over 200 mm. With short
knife lengths and large material thicknesses, the guillotine shears mutate into
billet shears or profile shears.
The variety of guillotine shears naturally also
extends to the material. The most famous guillotine shears are those for
metals, cardboard or plastics.
Other types of scissors, which in the broadest
sense also work like plate shears, are:
-
Swinging shears (circular movement of the upper cutter beam)
-
Knee lever shears
-
Crop shears
-
Rotary shears (cutting beams upper and lower move on eccentrics)
-
Flying shears (shear is mounted on a sliding carriage)
Rotating and flying shears are used in
cut-to-length lines for the cutting process.
The knives
- the hard core of a pair of blades
Hardened and ground cutting edges are the
characteristics of a knife. The material is a tool steel to achieve the
necessary hardness. A good knife can be sharpened several times before it is
completely worn out. The grinding can be done on normal surface grinding
machines.
With us you
will find a large selection of used plate shears
tramao offers you a large selection of used plate
or guillotine shears. The plate shears in the metal category can be found in
the metal cutting machines area.
You will find the right service companies for
repairs and spare parts procurement on tramao.de.
You will also find a wide range of machine
accessories on tramao. Not to be forgotten is our range of tools, including
knives.
If you decide to buy used guillotine shears, you
will find a large selection of well-known manufacturers such as Baykal, Durma,
Safan, Haco, Digep, Fermat, Fasti or Matra on tramao.