1. Terms
| Fastening | The process from the screwdriver start to the shut-off controlled by the screwdriver or Fastening electronics |
|---|---|
| Job | List of fastening operations with or without predefined positions that are associated with a workpiece |
| Cycle | Number of the Fastening program on the Fastening control unit to be used for a specific Fastening operation |
| LED Backlight | The display backlight can be red, green, blue, or white. |
2. System Description
The Posco 500 is an electronic control unit for controlling and monitoring the process sequence and
completeness of fastening operations on a workpiece. If the control unit works in conjunction with a
tool stand, it is equipped with an angle and distance sensor and it is thus able to detect the position
of the screw currently being handled.
The description below applies to this control unit, which is referred to as Posco 500 in the following.
In addition to the distance and angle sensor interfaces, the Posco 500 provides further 24 volt digital
input and output signals (that can be freely programmed with the Profi-Programming). These signals
are used to enable and control workstations and the deployed tools are integrated into the process.
Pneumatic screwdrivers can also be enabled and monitored with the "FAS" option in addition to the
electrical tools.
Complete equipment: Posco with a connection to the screwdriver, external operating and display
elements (24 V) and a tool stand with position control.
The Posco 500 thus assumes two different roles, depending on whether it controls an air or electric
screwdriver.
With air screwdrivers, the Posco 500 undertakes the monitoring functions (optionally) known from
the FAS system. In this case, the Posco 500 not only evaluates the OK/NOK for each individual
Fastening, but also the total. This classification is based on the signal sequence at two digital inputs
(dual sensor system) or one digital input (single sensor system). The air screwdriver functions are
available as an option FAS/air for Posco 500 for software versions V.3.00 and higher. The FAS can
be used with and without the tool stand - with and without position control.
With electric screwdrivers, the Posco 500 primarily monitors the sequence of screws and their
completeness including actuating the Fastening program, with and without position control. The OK/
NOK classification of the individuals fastenings is undertaken by the screwdriver control unit (e.g.,
CVCI or ESP-7), which transmits these results via digital I/O signals to the Posco 500.
By utilizing digital 24V signals, the system can be easily linked to existing screwdriver control units. Due to its intuitive menu structure, it can be quickly and smoothly operated after a short learning period.
In teach mode, the unit is programmed with the desired position and process sequences. With the
Posco 500, the complete sequence definition for a workpiece is called a job. The system only
supports random process sequences by using tool stands without a positioning-device.
| Software V.2.xx | Software V.3.xx | |
|---|---|---|
| Number of Possible Jobs | 32 | 63 |
| Number of Positions | 320 | 600 |
The Posco 500 can store up to 63 jobs for software version V.3.00 and higher with a total of 600
sequence element memories for positions, logic positions and text messages available for these
jobs. These sequence elements can be freely allocated to the 63 supported jobs. Thus it is possible
to create, e.g. 60 jobs with 10 positions each or 20 jobs with 30 positions each, etc.
Apart from the Fastening positions, the Posco 500 can also assume additional functions. Additional
input queries can be defined for specific positions in the basic design and external starting signals
and output signals can be processed for clamping.
With the additionally available option of Profi-Programming, logic positions can be combined with
input enquiries, process times and output signals with any position steps. Furthermore, freely
programmable text messages can be built into the sequence.
These tools allow the implementation of complex Fastening processes and they normally make it
unnecessary to use additional control unit hardware such as Memory-Programmable Controls
(MPC).
In order to be able to realize as many applications as possible with the Posco 500, the assignment
of the input/output resources is freely programmable.
The standard unit features 10 digital inputs and 6 digital outputs, which can be doubled with an
optional module to a total of 20 digital inputs and 12 digital outputs.
In the Setup area, the user can assign these inputs/outputs to the various functions.
For example, up to 5 outputs can be assigned for selecting a screwdriver control unit cycle, whereas
users who do not require cycle selection will not waste an output, since they simply forgo specifying
a cycle selection output.
In each case, the Fastening sequence processing in the Posco follows a defined scheme, with the
user being able to utilize various options.
As a rule, the user has to specify the number and positions of a job; this is done in teach mode,
which is automatically called up after a new job has been created.
After specifying the number and positions of the Fastening operations, the user can link various
functions to the individual positions of a job. Thus, the enabling of a screwdriver for a specific
position can be linked to additional queries of digital inputs, which facilitates, e.g., the polling of a
sensor at position 3 if an additional part should be inserted there.
The system deploys absolute distance and angle sensors. In regards to their coordinates, these
sensors are not calibrated to any specific external reference. With respect to this, every tool stand
has its own coordinate system which usually does not correspond to that of another tool stand.
Therefore, the position data for a Fastening job solely apply to the system for which they were
taught. Thus, when transferring job data between two systems or restoring saved job data, the
position data for the jobs must usually be newly taught.
In the following, the extension axis (linear sensor) is called the X-axis and the rotational axis (angle
sensor) is called the Y-axis.
The position resolution of the Posco 500 is finer than 1 mm.
The geometry of the D53 tool stand allows for a maximum extension of 600 mm and a minimum
extension of 340 mm. The effective extension length is thus 260 mm.
This length is typically represented by 900 digits, which results in an X-axis resolution of 0.3 mm.
With the Y-axis, a digital angle sensor with a 13 bit resolution is deployed.
The D53 frame has a maximum tool radius of approx. 600 mm.
At 600mm max. Extension, the resulting circumference is 2 * π * 600 mm = 3768 mm, which
amounts to approx. 10.5 mm per degree.
At the given 13 bit resolution (corresponding to 0.044 degrees/digit) and maximum extension, the
resulting resolution is thus 10.5 mm * 0.044 = 0.46 mm.
amounts to approx. 10.5 mm per degree.
At the given 13 bit resolution (corresponding to 0.044 degrees/digit) and maximum extension, the
resulting resolution is thus 10.5 mm * 0.044 = 0.46 mm.
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