| 摘要 |
A refillable ballpoint pen structure in which the refill can be extended or retracted by relative rotation of the parts of the pen structure through 360 DEG . A driving casing tube is fixed in the upper end of a body tube and an external casing tube is fitted over the driving casing tube for relative rotation but not axial movement. A driving axial tube is rotatable within the driving casing tube and is axially slidable and non-rotatably engaged with the interior of the external casing tube. The driving casing tube has a sinuously curved groove therearound, in which an inwardly projecting projection on the driving casing tube is engaged for causing longitudinal movement of the driving axial tube upon relative rotational movement between the driving axial tube and the driving casing tube. A spring is fitted between the driving axial tube and the driving casing tube and a cap is fitted over the external casing tube and in which the external casing tube is relatively axially slidable and non-rotatable. With a ballpoint pen refill having a ballpoint thereon held fixed in relation to the driving axial tube, relative rotation of the cap and body tube causes relative rotation of the driving axial tube and driving casing tube for causing the projection to move relatively along the groove and the ballpoint to be extended out of and retracted into the body tube by relative rotation of 360 DEG between the cap and the body tube.
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