INNOVATIVE HIGH-PERFORMANCE PROCESS FOR DRY MANUFACTURING OF SHEET METAL ARMATURES AND THEIR INTEGRATED ON-LINE CLEANLINESS EXAMINATION

S. Behrning1, H. Bley(1), S. Joergens(2)

(1)Saarland University, Institute for Production Engineering/CAM, Saarbruecken, Germany; (2)Moeller GmbH, Bonn, Germany

At present armatures and cores in electromagnetic contactor systems consist of soft-iron, soft-magnetic castings or stampings fixed with rivet joints. To guarantee the reliability of the magnet system characteristics for the complete lifespan of the product, it is necessary to integrate a remanence air gap into the magnet system.
State-of-the-art technology for integrating the remanence air gap is either to grind the center pole of the magnet core or to fix a copper foil into the yoke of the armature or magnet core. Both methods lead to high production costs and tolerance problems. To avoid these main problems of the manufacturing process, an innovative high-performance process for realizing the remanence air gap was developed in which a nonmagnetic material (e.g. a polyurethane foil) is bonded automatically to the surface of the armature.
Because of the high demands on the lifespan of the contactors (up to 10 million mechanical switching operations or 15 to 20 years of operation) and the critical function of the foil, special attention has to be paid to bonding. Prior to bonding, surface cleanliness has to be guaranteed implying the detection and removal of all kinds of residues (solid particles, fluids and/or pastes). To accomplish these tasks, a cleanliness examination system is being developed consisting of an image processing system and an analytical measurement method. The image processor detects whether or not residues are on the surface and provides the subsequent measurement method (modified Fourier Transform Infrared Spectroscopy) with a priori information concerning the character of the residue and its location. Out of the analysis of the identified region an objective index, the cleanliness index, is generated describing the extent of contamination. The analysis results support the decision whether or not the foil may be bonded to the surface of the armature.
These methods will be described for dry manufactured armatures being used in magnet systems for Moeller contactors DIL M 185/ DIL M 820 for nominal currents between 185-820A.

Keywords: laminated drives, remanence air gap, magnetic steel sheets, dry manufacturing process, cleanliness examination, image processing, FT-IR-spectroscopy