| 摘要 |
<p>An L-shaped roller chime is provided adjacent each end of a closed head drum. The drum is formed of a thermoplastic material and is blown into shape in an openable mold so that the drum has axially extending dividing seams. Each L-shaped chime has a first leg extending outwardly from the drum and a second leg extending generally perpendicularly to the first leg and in the axial direction of the drum. The depth of the groove formed by the first and second legs and the outer drum surface is uniform, however, the thickness of the first leg varies from a maximum at the dividing seams to a minimum intermediate the seams.</p> |
