In the manufacture of subassemblies of prototype servomotors rotors of automotive steering systems, non-magnetized permanent magnets must be affixed to the rotor cores by means of suitable mounting tools. We want to speed up the bonding process and improve the positioning accuracy of non-magnetized magnets on the core of the servomotor rotor, thus reducing the ejection of prototype rotors.
We performed an input check of magnets and rotor cores, thus reducing the possibility of errors due to the poor quality of the delivered parts. The load on the bonded joints was calculated and the force of the spring holding the magnet to the core during the bonding process was measured. Then, considering all the important dimensional and geometric tolerances of the rotor, we designed a new mounting tool. The tool was used to make ten sets of rotors, where the accuracy of magnet positions on the core was compared with ten sets made with the old tool. We also measured the time taken to produce a subassembly with both tools and found that the manufacturing time when using the new tool was shorter by an average of 18.2 seconds. The new tool improved the accuracy of the position of permanent magnets on the cylindrical surface of the rotor core by an average of 22% compared to the one achieved when using the old tool. With regard to the accuracy of the outer diameters of the rotors, a 100% proportion of the corresponding subassemblies was obtained with both tools according to the required tolerances. The retaining system of the new tool successfully eliminated any core lifting during the bonding process.
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