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In general, the precision of a press is described in
terms of its static accuracy and rigidity, which are two
characteristics that are commonly used to describe it.
According to the Japan Institute of Printing's (JIS)
static accuracy index, the accuracy grade under static
state can be divided into four categories: special
grades, grades 1 through 2, grades 3 through 4, and
grades 5 through 6. The accuracy grade under dynamic
state can be divided into four categories: special
grades, grades 1 through 2, grades 3 through 4, and
grades 5 through 6. The rigidity of the press is an
important consideration in addition to the static grade
of the press. One important factor that must not be
overlooked is the power of the press in a democratic
society.
By using a press, material is forced through the die at a
pressure greater than the material's yield point,
resulting in a stronger material. However, it should be
noted that, despite the fact that the nominal pressure
applied does not cause damage to the press, elastic
deformation of various parts, such as bedding elongation
and the lateral deflection of the worktable, has a
significant impact on the stamping process. As a result,
it is preferable to incorporate dynamic characteristics
into the design of the press in order to improve the
static accuracy of the press. The table, crankshaft, and
bed deform as a result of the action of the blanking
force, and the opening of a C-type press causes it to
lose its static accuracy, as illustrated in the figure.
The term "dynamic accuracy" refers to the accuracy that
exists at a given mould.com/zinc-die-casting">zinc die castings point
in time in the future. When operating in dynamic mode,
presses are classified according to the accuracy with
which they operate. With regard to the dynamics of the
press, the rigidity of each component is directly related
to the accuracy of the press; therefore, a press with
high dynamic accuracy is also a press with high rigidity.
Currently, in another country, a press with high rigidity
is being manufactured, and its dynamic accuracy can still
be controlled within the press's static accuracy range,
which is currently within reach. Classes A and A1 are
designated for those with good rigidity, while classes B
and B2 are designated for those with general rigidity.
According to the static accuracy of the press, those with
high rigidity are classified into A1 and A2 classes,
respectively, while those with low rigidity are
classified into A3 and A4 classes.
Because of its rigidity, static accuracy differs from the
other levels of precision. Parts A2 and B1 demonstrate,
for example, that the grade of press used has a different
effect on the parts produced than the grade of press used
in A2. When the processing pressure reaches its maximum
value (the nominal pressure), the rigidity of the
material is measured and used to determine the grade of
the material being processed. In processing, the
resistance to applied pressure varies depending on how
much force has been applied at any given time. In
compression, a class B press with a nominal pressure of
1000kN has rigidity equal to or greater than that of a
class A press with a nominal pressure of 500kN when
compressed with a press pressure of 500kN. As a result,
when a small die is installed on a large press, the
rigidity of the press is unquestionably excellent.
Additional presses with substantial weight and high
rigidity are available, with primary characteristics that
are similar to those of the other presses, such as
nominal pressure, workbench area, and stroke length.
In order for the load to be supported, the press must
deform while bearing the load, as illustrated in Figure
1. Taking the amount of deformation into consideration
when determining the capacity of a press is essential.
Precision blanking, for example, must be performed at a
rate that does not exceed 50% of the total processing
capacity of the press in order to be considered
acceptable. Despite the fact that the general blanking
capacity is greater than 80% of its maximum capacity, the
uniformity of die clearance cannot be guaranteed under
any circumstances at all. As illustrated in Figure 2, the
pressure function with high precision can aid
in casting">die casting aluminum extending the service
life of the die while also improving the quality of the
stamped parts that are produced. Figure 2: Pressure
function with high precisionFigure 2: High precision
pressure function with high accuracy
Section 1 of this document discusses the impact of offset
cutting on machined parts.
Blanking has an impact on the accuracy of the workpiece
based on the accuracy from the lower part of the slider
to the upper part of the die base, as well as other
accuracy factors. Blanking can be used to improve the
accuracy of the workpiece. Blanking can be used to
improve the accuracy of a workpiece by removing excess
material. The following are the most pressing issues that
need to be addressed right away: 1.
One important consideration is the perpendicularity of
the punch and die, which refers to the ability to ensure
that the upper and lower dies are concentrically aligned.
At the conclusion of the blanking period, the load is
reduced to a percentage of its initial value equal to
zero percent.(2) A buffer that has the ability to be
stretchedIt is necessary to apply deformation energy
generated by the press to the punch in order for it to be
forced into the die. A large number of dies are being
thrown away as a result of the hammering buffer. In order
to achieve maximum accuracy, it is critical to minimize
or avoid any deformation during high-precision blanking.
It is necessary for the press to maintain a high level of
static precision in order for it to continue operating
properly. In particular, the C-frame press is susceptible
to a significant inclination of the center line of the
upper and lower dies as a result of opening deformation,
with the parallelism of the upper and lower dies
deviating as a result. This is illustrated in Figure 3,
where the inclined shear section has inconsistencies that
result in burrs and a significant decrease in the service
life of the die. Given that the blanking force in a high-
speed automatic punch is periodic and repeated, if the
rigidity of each part is less than twice that of an
ordinary press, each part will exhibit abnormal
deflection die
casting products and deformation, as well as
excessive noise and vibration, and the machine will be
unable to operate continuously as a result of this. The
small press must be made of special grade steel plate in
order to perform such operations because a press with a
pressure greater than A1 is required.
In order to maintain workpiece accuracy over an extended
period of time when the plate thickness is less than
0.5mm, it is necessary to use an A1 precision press. When
blanking sheet metal ranging in thickness from 0.8 to
1.2mm on blanking presses, it is possible to reduce the
influence of the rigidity of the press on the parts by
using a large die clearance and good perpendicularity,
which reduces the influence of the rigidity of the press
on the parts. It is possible to reduce the influence of
the rigidity of the press on parts when using the B1
press, but only to a limited extent. If, however, the die
clearance is large and the perpendicularity is good,
there will be no problem when using the B1 press.
Depending on how large the die clearance and how good the
perpendicularity are, it may be possible to reduce the
effect that a press' rigidity has on the parts by a small
amount. The B2 press can be used successfully when the
material thickness is between 1.6 and 2.4mm or greater
and the production batch is small. When the die is
deflected, it has only a minor impact on the accuracy or
appearance of the workpiece, and this is because the die
is deflected. In the course of processing medium and
thick plates with a thickness greater than 3mm, the
blanking pressure acts on the sliding block, causing the
plate to advance. Consequently, the press's rigidity has
emerged as a very important factor to take into
consideration. The fact that, when using the C-shaped
press, the pressure cannot be maintained below 60% of the
nominal pressure will not only result in a reduction in
the quality of the parts, but it will also have a
significant impact on the length of time that the press
will last.
A second factor to consider is how the parts bend in
relation to one another.
Because of this, the static accuracy of the press has
little effect on the parts that are bending formed, but
the rigidity of the press has a significant impact on the
parts that are bending formed, as depicted in the diagram
below. When correcting the bending, it is preferable to
use this method in order to keep the springback error
within a reasonable range and to avoid causing the upper
and lower dies to become out of alignment with one
another. As a result of this variation in the thickness
of the sheet sandwiched between the punch and the die,
along with variations in tensile strength and other
precision die
casting supplier mechanical properties, the press
can produce bending forces that are several times greater
than the required minimum pressure, causing the workpiece
to deform elastically and compromising its accuracy.
Among those working in the bending and forming
industries, the A2 level press is the most frequently
encountered machine. For example, when there are
stringent requirements for the accuracy of parts,
particularly the amount of rebound, the bending of
phosphor bronze and other thin plates with a small
allowable error in plate thickness can only be
accomplished with an A1 level press, which provides the
accuracy required for the bending operation. Similarly,
when there are stringent requirements for the accuracy of
parts, particularly the amount of rebound, the bending of
phosphor bronze and other thin plates with a small
allowable error in plate thickness can only be
accomplished withBecause of this, the difference in
material thickness between parts is more important in
terms of reliability than the press specifications used
to manufacture the parts. In cases where there is no
issue with the accuracy of grade 2 precision materials
during the bending forming process, the use of a grade B2
press can produce better results if the grade 2 precision
materials are not subjected to any issues. Sheet metal
that has been mixed with thick and hard materials may
become overloaded and break as a result of the
overloading. Even though the press exhibits good rigidity
and does not deform in this situation, the die may be
damaged or deformed as a result of the deformation.
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