RFID tool head monitoring system for electrode cap grinders

As a specialist manufacturer of welding system accessories, AEG SVS Schweisstechnik in Mülheim mainly produces electrode caps, electrode cap grinders and related cutting heads. To ensure that the correct Tool head was selected for the corresponding welding helmet geometry, the company approached Andres Bäker and two classmates to develop this reliable identification solution as an Engineering course study project.

The yellow read/write head reads the tag in the cutter head during rotation

Challenge cutter head identification

AEG SVS Schweisstechnik produces the electrode cap grinders, electrode caps and approximately 200 different cutting heads required for this repair process. If a dresser is equipped with the wrong cutting head, this can lead to major failures in the production process.

Since it was difficult to distinguish the cutter heads during visual inspection, AEG Schweisstechnik began looking for a way to automatically identify the cutter heads in 2010. The goal was also to create a test application in order to determine the optimal settings for cutting parameters, including speed, number of cutting strokes and pressure. The company approached the Mönchengladbach Institute for technical consultation on these issues. At that time, Andres Bäker, who was about to complete the final stage of his studies in engineering, was eager to use it as a course project and accepted the challenge together with two other classmates.

These would-be engineers used RFID systems to develop solutions for detecting cutter heads during installation. The read/write head with a diameter of 18 mm is installed diagonally above the cutter head. It does not hinder the cutting process but is close enough to the tag to ensure recognition even at high speeds. Engineers integrated the tag directly into the cutter head. The mini tag is only 1 mm high and 7.5 mm in diameter. The 128-byte storage capacity is fully adequate for basic identification tasks. It is necessary to write an 8-digit identification number to the tag. With the identification number, the tag can be uniquely identified.

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The code body can be protected in the cutter head

The read/write head is connected to the I/O module of the RFID system. Users program the BL20 gateway through software, which then controls the entire application. In addition to identification tasks, engineers also developed solutions for detecting the speed and direction of rotation of the cutter head. For this purpose, they installed two inductive sensors in the chip collection system that detect two recesses in the cutter head. Based on the switching pulses of the rotating disk, appropriate control logic determines the speed and direction of rotation of the cutter head. If the wrong cutter head is installed, the yellow LED will light up and the device will be prevented from starting.

The test equipment can display all parameters through the CoDeSys user interface: speed, pressure and number of cutting strokes. These parameters can be set separately by the controller to test the optimal configuration for cutting different electrode caps. “The results of this engineering learning project cannot be described in one word as satisfactory for us. Because we can integrate the RFID solution directly into our products with almost no additional requirements”, AEG SVS Schweisstechnik explains product manager Jürgen Rosendahl.