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application background
Steel company Hüttenwerke Krupp Mannesmann GmbH (HKM) in Duisburg, Germany, is steaming hot all year round. The company is Europe’s leading steel manufacturer and supplies its partners such as Thyssen Krupp Steel AG with the preliminary products for steel processing, so-called ingots or billets (round steel bars). To make these products, molten metal must be transported, mixed, and processed. The raw materials needed for steel production are transported in molten iron tanks through huge warehouses and production halls. Depending on the size of the molten iron bucket, 90 to 425 tons of molten iron must be moved during processing, a job that only giant cranes can do.
In total, HKM has around 50 giant cranes in use, 10 of which are used to transport liquid materials above the production hall. Under the unfavorable conditions of iron and iron ash in steel forming, if a certain link goes wrong, it will cause a lot of time loss at light, and the crane will be damaged and cause huge losses.
Calibration using RFID
Due to the high temperature, steel producer HKM finally decided to use a high temperature solution from Turck. Utilize BL ident RFIDThe system, as well as special sensors operating over an extended temperature range of up to 100 °C, can transport and track the ladle with precision down to 1 cm, thus avoiding huge losses due to errors during transport or when filling raw materials. Wilhelm Leurs, technician in the crane maintenance department at HKM, said: “There is an adage ‘install and forget’, and Turck’s products are just that: easy to install, perfectly integrated with the existing S7 controller, and so far there have been no operational failures.
Turck’s BL ident RFID solution supports an important control function on the BS6L crane. The crane transports the empty molten iron buckets to the charging area, where they are cleaned and heated as needed so that they can be filled with liquid raw materials again. The operator sits in a small cockpit about 16 meters above the ground and controls the machine with the aid of a monitor. There are no longer locators on the ground, and the crane’s movement and position are visualized on a monitor. The monitor helps the crane operator position the crane when lifting and lowering the load, which requires a high degree of precision from the system.
Rotary position sensor loosens easily
In order to move the crane in a controlled manner over a distance of approximately 400 meters between the lifting and loading positions, HKM installed a rotary position sensor on the turntable, which records the crane movement data and sends it to the main control unit. There is a problem with this approach: the travel sensor can only detect the position of the crane using the actual rotation of the huge turntable. The steel wheels of the crane run on the rails, so a certain amount of looseness cannot be ruled out. This will result in inaccuracies that the travel sensor cannot compensate for.
A few centimeters of looseness can cause serious errors in the lifting and lowering areas, preventing the crane operator from lifting or lowering the iron bucket with precision. This is where the BL ident RFID system comes into play. A Q80 read-write head is installed near the crane turntable to record the signal of the transponder installed at a specific point on the track, so whether there is looseness or not, the position coordinate accuracy of the travel sensor in the main control unit can reach centimeter level. Using the known label position, the control unit can calibrate the signal of the rotary position sensor, effectively preventing possible loosening from being affected. These labels are specially designed to be used in high temperature environments up to 210 °C.
HKM opted for a control system that is less expensive to install and maintain, which continuously detects the signals from the travel sensors and can update these signals in the control unit when needed. The BL ident system not only prevents serious accidents, but also enables efficient supply chain management. “In the spirit of comprehensive monitoring of the material, it was important for us to know exactly where the crane lowered the load, so we could pinpoint the location of the different numbered iron buckets,” says Leurs.
The system is so reliable that HKM intends to equip all the giant cranes used to transport raw materials and final products with Turck’s BL ident system, which means there will be 30 of them in the company’s steel production hall in Duisburg, Germany Giant cranes deliver materials faithfully and reliably. Leurs concludes: “We may not be using the full potential of the BL ident system, but for our control purposes this solution is unmatched.”
Replacing a Locator with a Sensor
In addition to RFID solutions, Turck’s inductive sensors are also proven for use in harsh steel production environments. The crane lifts and transports the ladle using large hooks weighing several tons, each with two special sensors with IP68 protection. These sensors record whether the lifting ring on the ladle is accurately and safely seated in the single piece hook. Here, from the cockpit, which is 18 meters above the ground, it is also difficult for the operator to judge whether the ladle is in the correct position on the hook. Two sensors placed at a 90° angle solve this problem, ensuring that the hoist ring reliably straddles the entire surface of the blade hook.
A crucial and very reliable control tool for Leurs is the S100 heat-resistant, shock-resistant and vibration-resistant sensor of the BI15-K series. Leurs adds: “The Turck sensor has never had a problem, so we intend to have it on all cranes that transport liquid raw materials.” In the harsh environment of steel production, slag and fine metal dust can enter the machine , which obstructs or distorts the sensor reading, while Turck’s special sensor measures switching distances up to 15 mm, which is an important reason why it is suitable for use in this environment.
Summarize
In addition to the perfect application of RFID in logistics, production and processing, warehouse storage management, etc., it can also be widely used in object positioning.
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