| 摘要 |
Each turn of the wire 1 of an incandescent lamp coil has straight sections and curved sections, each curved section being offset relative to the corresponding section of the adjacent turns by an angle, alpha , lying between 10 DEG and 110 DEG about the axis of the coil. The coil is produced by winding the wire on a mandrel with an elongate cross-section, annealing the wire to partially relieve the stresses caused by winding, and then dissolving the mandrel so that the residual stresses cause the curved sections to open out to a predetermined extent. Wire 1 may be surrounded by a covering coil 3. Coil 3 is initially wound round both wire 1 and a round mandrel (2) the round mandrel subsequently being dissolved. <IMAGE> |
