| 摘要 |
<p>In the manufacture of poly-V belt pulleys from a flat disc-shaped blank which is formed into a cup-shaped can, after which external annular grooves are formed in the cylindrical portion of the can, the internal surface of this portion is provided with a limited number of ribs, e.g. four, forming a driving key co-operating with the mandrel on which the pulley is formed.</p> |
