Summary

Ein Hersteller von Förderer für Schüttgut nutzt ein RF-Identifikationssystem (RFID), um in einer heissen, staubigen Umgebung die Position eines grossen schienenmontierten Rückgewinnungsförderer zu erkennen. Mittels ein Paar Schreib-/Leseköpfe auf der Maschinenstruktur wird eine Reihenfolge von RFID-Tags abgefragt, die in Abständen von einem Meter auf jeder Laufschiene positioniert sind. Das Steuersystem erkennt jeden einzelnen Tag und bestimmt somit die genaue Position der Maschine.

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Kundennutzen

  • Unterbrechungsfreie Produktion dank sehr zuverlässiger Positionsidentifikation
  • Kein Risiko einer Schiefstellung da Bewegungen der Maschinenstruktur synchronisiert sind
  • Beseitigung von Kollisionsschäden dank einem Schaltabstand bis 45 mm

Alleinstellungsmerkmale

  • Passive Transponder benötigen keine Stromquelle und minimale Wartung
  • ConIdent® Technologie bietet erweiterten Schaltabstand ≤ 45 mm
  • Robuste Transponder mit Nylon oder Ganzmetallgehäuse abgedichtet nach IP67
  • Schreib-/Leseköpfe sind anschliessbar an Industrie-Standard-PROFIBUS DP Steuerungssystemen

Aufgabenstellung

During surface-mining operations, large mobile reclamation machines are used to recover bulk materials. On each machine, a bucket-wheel excavator collects material and deposits it onto a conveyor. As an area is cleared of material, the machine moves along parallel steel travel rails to the next area, allowing continuous operation without interruptions for machine repositioning. The distance between the travel rails is around 100 meters (300 ft) and travel speeds may reach 2 m/sec (4.5 mph). If machine movement along the two rails is not controlled accurately, the two sides of the structure become misaligned, causing the machine to skew. In this event, production is halted while the machine is realigned; in the worst case, costly damage occurs. A sensing system is required that detects the position of each side of the machine structure accurately and reliably along the entire length of the travel rails, allowing coordinated control of the drive systems. Sensors must accommodate up to 10mm lateral movement of the machine structure across either rail and must withstand  the hot, dusty environment of a desert climate. 

Realisierung

Contrinex high-frequency RFID read/write modules and 30mm-diameter RFID transponder tags are ideal for this application. Rated up to IP67, the M30-diameter read/write modules have PBTP sensing faces and V2A stainless-steel housings, making them ideal for the demanding environment. The ConIdent® passive transponders require no internal power source and, with PBTP synthetic housings, have the same IP67 rating. The selected combination provides read/write distances of up to 45mm (nearly 2 in), ideal for the specified operating conditions. Tags are mounted at one-meter intervals along each travel rail, each programmed with a unique identification number. As the machine passes a tag, the read/write module reads its identification number at high speed; this is transmitted via a PROFIBUS DP interface to the customer’s control system. A simple look-up table confirms the location of the tag and thus the position of the machine, allowing movement of both sides of the structure to be synchronized without skewing. Operation is independent of the direction of travel. Contrinex ConIdent® RFID devices allow accurate and highly reliable sensing of machine position and the long sensing distance avoids any risk of collision damage. The customer enjoys extended service life and robustness not available from alternative position-detection systems, together with excellent value for money.