Molding process for coating a motor stator

Details Molding process for coating a motor stator Molding process for coating a motor stator

1989-02-08

1990-08-21

Lowe, James

Plastic and nonmetallic article shaping or treating: processes

Mechanical shaping or molding to form or reform shaped article

To produce composite, plural part or multilayered article

264338, 425812, B29C 3910

Patent

active

049504380

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION

1. Technical Field
The present invention relates to a molding process for coating the stator windings of a motor by molding, which process is widely employed in the motor manufacturing field.
2. Background Art
Conventionally, portions of stator coils projecting from a motor stator are coated with a resin, and in such a conventional resin-coating process, stator coils in one side of a stator core are first resin-coated by placing one side of the stator core in a mold for resin-coating, and stator coils in the other side of the stator core are then resin-coated in the same manner. In another conventional resin-coating process, a stator inclined in one direction at an inclination (approximately 15.degree. ) is rotated while a resin is dripped on the upper portions of stator coils, to impregnate the upper portions of the stator coils with the resin, the stator is inverted, and the resin is then dripped similarly on the upper portions of the stator coils to impregnate the upper portions of the stator coils with the resin, while the stator is rotated.
For a motor which must be cooled internally, such as a spindle motor, coating the coils with a synthetic resin is advantageous, particularly with respect to coil protection. Nevertheless, the foregoing conventional resin-coating processes for coating stator coils with a synthetic resin can coat the stator coils only on one side of the stator core in one resin-coating cycle, and thus the resin-coating cycle must be repeated twice to coat all of the stator coils with the synthetic resin, which is inefficient.
A spindle motor particularly requiring a liquid-resistant (water-resistant) coating for the coils has a comparatively long stator core, and therefore, the simultaneously coating of the coils on opposite sides of the stator core which need not necessarily be coated causes problems such as an unsatisfactory impregnation of the coils with the synthetic resin, an incomplete venting, and difficulty in removing the stator core from the mold due to a contraction of the synthetic resin during cooling.
The present invention provides a means capable of solving the foregoing problems and capable of fundamentally eliminating the defects of the conventional means.


DISCLOSURE OF THE INVENTION

According to the present invention, an integral stator, comprising a stator core 1 and coils 2 partly projecting from the stator core 1, is placed in an upright position, a mold core consisting of a top mold 3, a middle mold 4, a first bottom mold 5, and a second bottom mold 6 is combined with the stator as shown by way of example in FIG. 1, and then a heated synthetic resin solution is poured through sprues 0 formed in the top mold 3 into a cavity formed between the built-up mold and the stator. After the resin has filled the bottom portion of the cavity around the lower ends of the coils and has started flowing through drain holes 9 formed in a lower ring 8, the drain holes are stopped with plugs 81. Consequently, the resin fills the remaining portions of the cavity including an annular runner W tapered upward. After the cavity has completely been filled with the resin, the resin is left to cool and solidify. Gas remaining around the lower ends of the coils in the bottom portion of the cavity flows along the outer side of the lower ends of the coils and is discharged through the drain holes 9 together with the resin solution. The gas contained in the resin solution filling a portion of the cavity inside the stator and the gas contained in the resin solution filling a portion of the cavity around the upper ends of the coils flow upward and escape from the sprues 0 formed in the top mold of the mold. The surface of the mold is coated with an elastic coating film 7 to absorb strain induced by the solidification of the synthetic resin solution, and thus prevents any difficulty in separating the mold from the stator.
Furthermore, since the annular runner W is tapered upward, the flow speed of the resin within the annular runner W diminishes as the resin flows downward within

REFERENCES:
patent: 3058156 (1962-10-01), O'Connor
patent: 3075250 (1963-01-01), Strohn et al.
patent: 4714576 (1987-12-01), Cotton et al.

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