| 摘要 |
PROBLEM TO BE SOLVED: To heat up an armature shaft highly accurately in a short time by arranging heaters around specified number of armature shaft insertion holes, dividing the insertion holes and the heaters into zones, inserting an armature shaft into the insertion hole of a preheating die provided with a temperature sensor for each zone and then heating the armature shaft. SOLUTION: A preheating die 1 is provided with forty nine heaters 3 while surrounding thirty six armature shift insertion holes 2 and insertion holes 2. Number of the insertion holes 2 is determined by dividing the time required for heating an armature shaft 23 up to a specified temperature by a molding cycle time required for resin coating in next process. In order to suppress fluctuation in the heat distribution of the preheating die 1, the heaters 3 are divided into five zones, i.e., four zones of forty outer heaters and one zone of nine central heaters, and each zone is provided with one thermocouple temperature sensor 4. Output from the temperature sensor 4 is fed back to a temperature regulator and the preheating die 1 is controlled to sustain a specified temperature.
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