1. IntroductionBlanking and, more g

1. Introduction
Blanking and, more generally, shearing operations are the most
common operations in the process chains for sheet metal parts.
Looking at a typical punch force vs. penetration curve in blanking
(Fig. 1), two main phases can be distinguished. In the first phase
(from A to B in Fig. 1), the punch penetrates the material causing
the sheet metal to deform, first elastically and then plastically,
until the pressure at the cutting edges starts the shearing. Initially,
the punch force increases steadily due to both the deformation and
strain hardening of the material and, then, at the onset of shearing,
it decreases due to the progressive reduction in the cross-section
despite the strain hardening. In this phase, the press and die set
store up elastic energy. In the second phase (from B to C in Fig. 1),
the shear strength of the material in the shearing zone is exceeded
and a fracture starts causing the sudden release of the energy that
dissipates through the high frequency oscillations shown in the tail
end of the curve in Fig. 1. This break through shock generates
uncontrolled high reverse loads, mechanical vibrations and loud
noise that may cause serious problems such as fatigue cracks in the
ram, drive linkage, crown, housings and, in the bed of the press,
premature wear in punches and dies and great discomfort for press
operators. To withstand the harmful effects caused by break
through shocks, mechanical and hydraulic presses can be oversized
(an over tonnage of 50% is usual for continuous blanking and
punching of high strength materials) or equipped with cushions or
hydraulic shock dampers that absorb part of the shock energy.
However, if, on the one hand, over sizing the press may not be
practical from an economical point of view, on the other hand, the
required additional load capacity, fluid elasticity and limitations in
the working stroke represent the main drawbacks of cushions and
hydraulic dampers.
The break through shock in blanking operations has been
considered by a number of researchers, most notably for modelling
the ductile fracture that causes the sheet metal separation and the
associated energy release [1–3] or for correlating the stiffness of
the system components (press, stripper and die set) and their
vibrations during the break through [4–6]. However, few
contributions in the scientific literature have dealt with new
possible solutions to effectively reduce the reverse load, vibrations
and noise. Murakawa [7] developed a ‘‘hydraulic inertia damper’’
that proved to be effective in lowering the punch force reduction
rate, thereby causing a reduction in vibration and noise. Osakada
[8] demonstrated that the noise level accompanying the break
through shock can be significantly reduced if an accurate control of
the punch motion – such as that allows by servo controlled presses
– is combined with a ‘‘continuous two-step blanking’’, where the
punch is stopped just before the fracture starts.
In this paper, the application of magneto-rheological (MR)
dampers to reduce the shock response of press systems during
blanking operations is considered. In recent years, many research
projects have demonstrated that MR dampers can be profitably
utilized to control the vibrations of civil structures, vehicle
suspensions and biomedical systems as well (e.g. see Refs. [9–
11]). The principal aim of the investigation described in the paper
was to evaluate, through full-scale experiments, the feasibility and
practicability of implementing MR dampers and to understand the
potential benefits when they are used in a semi-active manner in
comparison with conventional dampers. In the first part of the
paper, the design and construction of the MR dampers utilized in
the experiments are presented together with the testing that was
carried out to evaluate their damping force characteristic. The
second part focuses on the experiments, which aimed at evaluating
the press system response to the break through shocks generated

ผลลัพธ์ (อังกฤษ) 2:

1. Introduction
Blanking and, more generally, shearing Operations are the Most
common in the Operations Process for Sheet Metal Parts chains.
Looking at a Typical Punch Penetration Force vs. Curve in blanking
(Fig. 1), Two Main phases Can be distinguished. In the First Phase
(from A to B in Fig. 1), the Punch penetrates the Material causing
the Sheet Metal to Deform, First elastically and then plastically,
until the pressure at the Cutting edges starts the shearing. Initially,
the Punch Force increases steadily Due to both the deformation and
strain hardening of the Material and, then, at the onset of shearing,
it decreases Due to the progressive Reduction in the cross-section
Despite the strain hardening. In this Phase, the Press and Die SET
up Elastic Energy Store. In the Second Phase (from B to C in Fig. 1),
the shear strength of the Material in the shearing Zone is exceeded
and a fracture starts causing the Sudden release of the Energy that
dissipates Through the High frequency oscillations shown in the Tail
End. of the curve in Fig. 1. This generates Shock Break Through
Reverse High uncontrolled loads, vibrations and Mechanical Loud
Noise May Cause Serious Problems such as that fatigue cracks in the
RAM, linkage Drive, Crown, and Housings, in the Bed of the Press,
premature Wear in and punches. Great Dies and Press discomfort for
operators. To Withstand the harmful effects caused by Break
Through shocks, Mechanical and Hydraulic presses Can be Oversized
(an over Tonnage of 50% is usual for continuous blanking and
punching of High strength Materials) or Equipped with cushions or
Hydraulic Shock dampers that absorb Part of the. Shock Energy.
However, if, on the one Hand, over sizing the Press May not be
practical from an economical Point of View, on the Other Hand, the
required additional Load capacity, Fluid elasticity and limitations in
the working stroke represent the Main drawbacks. of cushions and
Hydraulic dampers.
The Shock Break Through in blanking Operations has been
considered by a Number of researchers, modeling Most notably for
the ductile fracture that causes the Sheet Metal Separation and the
associated Energy release [1-3] or for correlating the stiffness. of
the System components (Press, stripper and Die SET) and their
vibrations during the Break Through [4-6]. However, few
contributions in the Scientific literature have dealt with New
Solutions to effectively possible Reduce the Reverse Load, vibrations
and Noise. Murakawa [7] developed a '' Hydraulic damper inertia ''
that proved to be effective in lowering the Punch Force Reduction
rate, thereby causing a vibration and Noise Reduction in. Osakada
[8] demonstrated that the Noise level accompanying the Break
Through Shock Can be significantly reduced if an Accurate Control of
the Punch Motion - such as that Allows by Servo controlled presses
- is combined with a '' continuous Two-Step blanking '',. where the
Punch is stopped just before the fracture starts.
In this Paper, the magneto-rheological Application of (MR)
dampers to Reduce the Shock response of Press Systems during
Operations blanking is considered. In recent years, many Research
Projects have demonstrated that MR dampers Can be profitably
utilized to Control the vibrations of Civil Structures, Vehicle
suspensions and Biomedical Systems as well (eg See Refs. [9-
11]). The Principal of the Investigation AIM described in the Paper
was to evaluate, Through full-scale experiments, the feasibility and
practicability of implementing and MR dampers to Understand the
Benefits potential when they are used in a semi-active Manner in
comparison with conventional dampers. In the First Part of the
Paper, the Design and Construction of the MR dampers utilized in
the experiments that are Presented Together with the Testing was
carried out to evaluate their damping characteristic Force. The
Second Part focuses on the experiments, which aimed at evaluating
the response to the Break Through Press System Generated shocks.

ผลลัพธ์ (อังกฤษ) 3:

1. Introduction
Blanking, generally and more, operations shearing are the most
common operations in the process chains. For sheet metal parts.
Looking at a typical punch force vs. Penetration curve in blanking
(Fig. 1), two main phases can. Be distinguished. In the first phase
(from A to B in Fig. 1), the punch penetrates the material causing
the sheet metal. To, deformFirst elastically and, then plastically
until the pressure at the cutting edges starts the shearing. Initially
the, punch. Force increases steadily due to both the deformation and
strain hardening of the, material and then at the, onset of shearing
it,, Decreases due to the progressive reduction in the cross-section
despite the strain hardening. In this phase the press, and. Die set
.Store up elastic energy. In the second phase (from B to C in Fig. 1),
the shear strength of the material in the shearing. Zone is exceeded
and a fracture starts causing the sudden release of the energy that
dissipates through the high frequency. Oscillations shown in the tail
end of the curve in Fig. 1. This break through shock generates
uncontrolled high reverse. Loads.Mechanical vibrations and loud
noise that may cause serious problems such as fatigue cracks in the
ram drive linkage,,, ,, crown housings and in the bed of, the press
premature wear in punches and dies and great discomfort for press
operators.? To withstand the harmful effects caused by break
through shocks mechanical and, hydraulic presses can be oversized
.(an over tonnage of 50% is usual for continuous blanking and
punching of high strength materials) or equipped with cushions. Or
hydraulic shock dampers that absorb part of the shock energy.
However if on the one hand,,, sizing over the press may. Not be
practical from an economical point, of view on the other, hand the
required additional load capacity fluid elasticity,, And limitations in
.The working stroke represent the main drawbacks of cushions and
hydraulic dampers.
The break through shock in blanking. Operations has been
considered by a number of researchers most notably, for modelling
the ductile fracture that causes the. Sheet metal separation and the
associated energy release [1 - 3] or for correlating the stiffness of
the system components. , (pressStripper and die set) and their
vibrations during the break through [4 - 6]. However few
contributions, in the scientific. Literature have dealt with new
possible solutions to effectively reduce the, reverse load vibrations
and noise. Murakawa. [] developed 7 a '' hydraulic inertia damper ''
that proved to be effective in lowering the punch force, reduction
rateThereby causing a reduction in vibration and noise. Osakada
[] demonstrated 8 that the noise level accompanying the break
through. Shock can be significantly reduced if an accurate control of
the punch motion - such as that allows by servo controlled. Presses
- is combined with a '' continuous two-step blanking '', where the
punch is stopped just before the fracture starts.
In. This, paperThe application of magneto-rheological (MR)
dampers to reduce the shock response of press systems during
blanking operations. Is considered. In, recent years many research
projects have demonstrated that MR dampers can be profitably
utilized to control. The vibrations of, civil structures vehicle
suspensions and biomedical systems as well (e.g. See Refs. [9 -
11]).The principal aim of the investigation described in the paper
was to evaluate through full-scale experiments the feasibility,,, And
practicability of implementing MR dampers and to understand the
potential benefits when they are used in a semi-active. Manner in
comparison with conventional dampers. In the first part of the
paper the design, and construction of the MR dampers. Utilized in
.The experiments are presented together with the testing that was
carried out to evaluate their damping force, characteristic. The
second part focuses on, the experiments which aimed at evaluating
the press system response to the break through shocks. Generated.