| 摘要 |
A mechanical pencil with a chuck made of plastics includes a lead case connected with the chuck, a ring arranged to surround and hold the chuck, and a spring for biasing the chuck toward a position where it is engaged with the ring, all of which are disposed within a tubular housing. The plastic chuck includes a cylindrical tube connected with the lead case and three elastically deformable extensions integral therewith. Each of these extensions has an engaging portion for grasping a lead and a connecting portion whose inner surface axially forms a curve of secondary degree extending from the cylindrical tube and expanding radially toward the engaging portion in its free state, so that the engaging portion aligns with the lead when it is engaged with the ring. Accordingly, a grasping force is uniformly applied around the lead.
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