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Montagemetoder för axel och rotor

At ABB LV Motors in Västerås the shaft is assembled into the rotor with a shrink fit. After athorough investigation of the assembly method, several factors that make the insertion of theshaft more difficult has been discovered. Some affect the assembly directly while others onlyhave an indirect influence. The investigation has shown that the radial play between the shaftsouter radius and the rotors inner radius might be too small which could lead to anunsuccessful assembly. For the larger rotors, the condition is the opposite, and the rotor mightmove compared to the shaft direct after the assembly when the rotor still is warm. The factthat the shaft is inserted into the rotor horizontally makes the linearization of the rotor centerand the shaft center very important. To minimize the scrap rate of the rotors and shafts it isessential to take measures of these factors.Theoretical calculations and experimental analysis have shown that the interference for sizes112 and 132 could be loosened without risking a breakdown of the joint. To eliminate theproblem of rotors that moves compared to the shaft after the assembly the interference couldbe tightened for sizes 200-250. The introduction of lubricant in the process has reduced theamount of discarded rotors and shafts considerably. To ensure that lubricant doesn?t have anynegative effects of the joint, experimental tests has been done without finding anydisadvantages. However, the expectation is that after the shafts tolerances have been adjusted,the use of lubricants would be unnecessary. A cost saving calculation indicates that theintroduction of new shaft tolerances would reduce the cost of discarded shafts and rotors by300 000 SEK annually.

Författare

Gustav Borg

Lärosäte och institution

KTH/Maskinkonstruktion (Inst.)

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