Apparatus for making multi-groove pulleys

Apparatus for making a V-grooved pulley having at least three grooves from a single cup-shaped sheet metal blank having a cup bottom wall and a cylindrical side wall. A cup-shaped blank first is formed by usual press operations. Then the cup bottom wall preferably is supplied with a hub of desired configuration having an axial bore with which the ultimately formed pulley grooves are concentric and about which the pulley to be formed is dynamically balanced. Two pulley grooves then initially are spun adjacent the cup bottom wall in the cup cylindrical flange or side wall to form an intermediate spun product in special first stage spinning dies. A third pulley groove then is spun in second stage spinning dies in the cylindrical cup side wall between the open end of the cup and the two initially spun grooves. The cylindrical side wall portion of the intermediate spun product in which the third groove finally is formed adjacent the open end of the cup, supports the cup during operation of the first stage dies, while the two grooves initially are formed in the cup, thereby assisting in maintaining concentricity and in providing dynamic balance during groove spinning.