Roland R4000 Manual page 16

System description
2.3.7 Weld seam positioning and positioning accuracy
A good positioning accuracy can only be achieved if:
• the response time for the controller is short enough
• the driver rotates the tube with a constant rotation speed / surface velocity and with no
slippage
• the drive stops reproducibly
• the weld seam detection is reliable
• for friction rollers the diameter tolerances should be close
• the SND40 is correctly adjusted
Accuracies better than +/- 8° require additionally:
• rotation of the tube with chuck and servo drive
• check for feasibility in the application laboratory
• an optimum setting of the SDN40
2.3.8 Reliability of detection
Due to steady progress in the welding technology and in the production processes of tubes, the
detection of weld seams is a constantly increasing challenge. Therefore some tubes can be
encountered, where the weld seams are not reliably detectable.
Reliable weld seam detection can be affected by a variety of factors, such as grooves, deviations
from concentricity, material defects, or hard spots in the tube wall from roll forming.
In the most unfavourable case this can result in false weld seam positioning. Such tubes cannot be
processed further and must be sorted out..
Therefore, for such tubes the SND40 supplies the signal "reduced detection capability" to the PLC
interface. This signal instructs the PLC to initiate the removal of the tube. The decision therefore is
done automatically by the SND40.
High detection reliability means:
no incorrectly positioned tubes (ideal case), but
•
depending on tube class, a relatively large number of rejected tubes.
•
Low detection reliability means:
relative large number of incorrectly positioned tubes
•
few or no rejected tubes
•
The detection reliability can be adjusted in the SND40 with the parameter "detection grade".
The reliability of detection increases with high dB values.
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ROLAND ELECTRONIC GmbH · Otto-Maurer-Str. 17 · DE 75210 Keltern · Phone +49 (0)7236-9392-0 · Fax +49 (0)7236-9392-33
Weld Seam Detection System R4000 SND40
for Tubes, Cans and Drums
Important:
the "blue discoloration" at the seam is for checking of the position roughly suitable!
Measurement errors of 10 ° or more may occur.
Manual
B0059001 / Rev. 2.3