| 摘要 |
<p>A retractable needle unit (10) for use on the roller (12) of a punching apparatus is provided. The unit (10) has a support wheel (16) coaxially mountable on the shaft (14) of the roller (12). A plurality of needles (26) are mounted on the support wheel (16), each of which being pivotable in the radial plane of the support wheel (16) between an operative position where it partially projects beyond the outer circumference of the support wheel (16) and a retracted position where it lies within the outer circumference. The unit (10) also includes a guiding wheel (34) rotatably mountable on the shaft (14) besides the support wheel (16), and being provided with a plurality of needle guides to engage the punching needles (26). Therefore, rotating the guiding wheel (34) pivots the needles (26) between the retracted and operative positions. The guiding wheel (34) is lockable with respect to the support wheel (16).</p> |
