Altan T. Metal Forming Handbook
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– provision of all important data to the operator during production, to
allow on-going assessment of machine status,
– support for the operator in troubleshooting and repair work in case
of machine failure,
– clearly arranged indication of maintenance intervals and instruc-
tions on the execution of necessary work,
– production log to inform the operator on the type and time of previ-
ous faults and maintenance work – operators must be able to enter
and access their own comments,
– a software system which is sufficiently open-ended to allow other
applications such as job management, quality assurance, operational
data acquisition or remote diagnostics.
Compliance with all these requirements imposes stringent demands on
the control and in particular on the software system. While these
requirements exceed the capability of a programmable logic controller
(PLC), industrial PCs possess practically all the components necessary
for compliance with these specifications. The industrial PC is not only
highly efficient, but also benefits from an open-ended software system,
offering graphic user interfaces and object-oriented programming
through the use of powerful programming tools.
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Fig. 4.6.34 Demands made on modern operating and visualization systems
Production
operating, monitoring
signalling
tool data management
Operating parameters
Acquisition of
operational data
Maintenance/repairs
maintenance
execution
log
production data, machine
data, statistics
line operating
and
information system
input and editing of
process parameters
Failure diagnostics
error message
failure diagnostics
Job preparation
job sheet,
job management
remote diagnostics
documentation
quality assurance
measurement-control
documentation
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
The widespread popularity of MS Windows as a graphic user interface
has provided a platform for many software suppliers to offer efficient
software solutions – also in the field of process visualization, which pro-
vides users with an ergonomically configured representation of produc-
tion sequences. Through integration in MS windows, communication
is possible with other Windows applications via the “dynamic data
exchange (DDE)” interface. Drivers for the relevant PLC systems are
required for communication between the process visualization system
and the “programmable logic controller (PLC)”.
Line operating and information system
The line operating and information system (ABI-Plus) is a modular,
open-ended and flexible software system designed to address present
and future press automation requirements. ABI-Plus helps reduce
machine and production line standstill periods, and so contributes
towards improved productivity as well as greater flexibility.
Process visualization
For ABI-Plus, a standard commercially available process visualization
system was selected as the core of the overall system. The operator is
able to monitor and control the process either interactively or auto-
matically through the control system. The man-machine interface pro-
vides an optical representation of the machine status with the aid of
dynamic graphics and real images (Fig.4.6.35).
Intervention in the process is possible using the softkeys. The user is
guided through the various operating modes such as set-up, automatic
continuous operation or die change on a step-by-step basis. The process
parameters are entered using an alphanumeric keypad and feasibility
tested by the program.
If a machine error occurs, the relevant error message with date and
time is superimposed on the screen mask currently being used. The
operator is able to access the troubleshooting module in order to local-
ize the fault and remedy it if necessary. The need of a machine mainte-
nance interval is also indicated to the operator by means of a flashing
maintenance symbol.
Tool data management
Another module of the ABI-Plus is a comprehensive tool data manage-
ment system which allows all die-specific data and machine settings to
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Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
be entered, edited, stored and transferred to the PLC(Fig. 4.6.36). For all
of these activities, the operator is offered support in the form of sym-
bols and graphic images, as well as being able to delete, rename and
copy tool data records at will. The number of tool data records which
can be stored depends on the storage capacity of the industrial PC.
Failure diagnostics module
If a machine failure is signalled, the operator is able to access the failure
diagnostics module by pressing a softkey and have the possible error
causes and the relevant repair process with the necessary work stages
displayed on screen (Fig.4.6.37).For each work stage, an instruction
text with a real image and, where necessary, also circuit diagrams,
hydraulic plans or technical drawings are displayed. The relevant sec-
tion of the illustration is highlighted by an icon.
For each error message, the operator is able to enter the date, the
name of the processing staff member and a commentary for the records.
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Fig. 4.6.35 Machine status display
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
Maintenance module
The maintenance signal is provided in the form of a flashing maintenance
symbol to indicate to the operator that maintenance is due. A table with
color-coded bars, which can also be accessed during production, indicates
all the maintenance intervals (Fig.4.6.38).The operator accesses the
maintenance module using a softkey. The individual work steps of the
maintenance activities are indicated by an instruction text with a real
image assigned to it (Fig. 4.6.39).In addition, every work stage can be fur-
ther illustrated by accessing a circuit diagram, hydraulic plan or technical
drawing. Here too, it is possible to store production log information such
as date, name of the operator and commentary.
Electrical equipment
As a rule, the electrical equipment of the press is broken down as fol-
lows:
–operating and information system with swivel-mounted pendant
control unit
–supply, distribution and electrical control in the switch cabinet
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Sheet metal forming and blanking
Fig. 4.6.36 Tool data display
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
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Fig. 4.6.37 Failure diagnostics module
Fig. 4.6.38 Overview of the maintenance module
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
–decentral I/O module at the press, at the feed unit, at the hydraulic
and lubrication systems and in the pendant control unit
–sensors and actuators at the press, at the feed unit and at the
hydraulic and lubrication systems
–main press drive system
Depending on the configuration of the press line, a range of periph-
eral devices and units such as coil lines with straightening machines
(cf. Sect.4.3) and recoilers or coil lubrication devices are additionally
used. These are equipped with their own control systems, sensors and
actuators.
Structure of the operating unit
The operating unit comprises an industrial PC for line operation and
monitoring, tool and machine data management, as well as informa-
tion system functions for the elimination of failures as well as backup
during maintenance and repairs (Fig.4.6.40).Basic and safety functions
are supported by keys, switches and lamps.
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Sheet metal forming and blanking
Fig. 4.6.39 Maintenance instructions
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
Structure of the electrical control system
Some of the special functions not described in the Section “Press con-
trol systems” will be illustrated here using the example of a high-speed
blanking line control system (cf. Sect.3.5). Figure 4.6.41provides an
overview of the system structure.
The sensors and actuators integrated in the press line are connected
via the I/O system of the central PLC unit. The wiring of the power sup-
ply to the switch cabinet is added to this.
Depending on the scope of the press line in question, the transition
from central to decentral I/O modules allows the wiring input to be
substantially reduced: Retrofitting, modifications, installation and
troubleshooting are considerably simplified. In addition, there is a
marked improvement in electromagnetic compatibility (EMC).
Communication between the PLC and the I/O units at the press line
runs via the serial field bus with transmission speeds of up to 12 Mega-
bits/s. The transmission medium is a shielded twisted-pair copper cable.
For applications in environments subject to marked electromagnetic
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Fig. 4.6.40
Control unit
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
Main drive
system
Press
L2-DP
L2-DP L2-DP L2-DP
L2-DP
Feed system Pendant control
unit
crank position
M
T
encoder slide height
slide adjustment
feed length setting
feed height setting
monitoring
lubrication flow
lubrication manifold
pump actuation
monitoring
pumps
system pressures
filter and oil level
triggering of hydraulic
valves
die change
oil temperature
monitoring
coil end
GG
press clutch
encoder feed length
encoder infeed height
activation
feed rollers
infeed centering
device
Contact control
mode preselection
emergency STOP
cut-in control
protective door safeguard
protective doors
recoiling
coil clamping
stroke adjustment
stroke adjustment
PLC CPU
tool safeguard
operating elements
operating elements
Control system
stroke adjustment
emergency STOP
emergency STOP
emergency STOP
operating elements
Link
coil line
electr. feed
system
clutch ON
reference point
mode preselection
direct voltage
motor
monitoring
_
industrial PC
press safety control PST 3
setpoint input, analog
control system
electronic
cam controller
penetration depth
control
feed length control
Lubrication
Hydraulic system
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Sheet metal forming and blanking
Fig. 4.6.41 Structural breakdown of the control system in a high-speed blanking line
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
interference, or where both increased transmission ranges and speeds
are involved at the same time, fiber optic cables can be used.
Data communication to peripheral equipment such as coil lines, coil
stock thickness gauges or coil lubrication systems is performed via the
I/O interface of the PLC. Between the industrial PC and the PLC, data
communication is implemented via an active serial interface with
20 mA. For data communication with a higher-level computer system,
an additional serial interface is available in the industrial PC.
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Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
4Sheet metal forming and blanking
4.7Fine blanking
In practice, fine blanking is also known by the terms precision blanking or
fine stamping. The production process involves shear blanking for the
manufacture of parts with a smooth cut surface. Like standard shear
blanking, according to DIN 8580 fine blanking falls under the main cate-
gory of material separation or parting processes, and is defined according
to DIN 8588 under the sub-category dividing (cf.Fig.2.1.2). Compared to
standard shear blanking, also known as normal blanking (cf. Fig.4.5.1),
however, different process parameters apply, resulting in a higher work-
piece quality.
The basic concept of fine blanking is that, in contrast to standard
blanking, the material is separated after being clamped on all sides
only as a result of material flow, i.e. without a fractured surface (cf.
Fig. 2.1.30).
4.7.1Fine blanking process
Advantages of fine blanking
Apart from the quality-related advantages of fine blanking, cost-effec-
tiveness is also a decisive factor in favor of the application of this
process. Specific blank-related advantages compared to normal shear
blanking include:
–smooth blanked surfaces free from fracture and tearing which are
able to fulfil functions without the need for reworking,
–extended field of application for shear blanking,
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998