Method for making chime structure for blow molded hollow member

In the method of producing a chime projecting radially outwardly on a blow-molded hollow member of thermoplastic material by forming the chime directly from the still hot hollow member by actuation of axially movable slide means toward an axially aligned fixed mold surface of a divided blow mold after the two mold halves have been brought together and after a plastic parison gripped between the mold halves has been inflated to a given shape to form the hollow member with a radially outwardly projecting annular channel-shaped part having one side wall thereof lying against the fixed mold surface, its other side wall lying against the slide means and the bottom outer wall lying against a radially outwardly disposed axial surface of the mold, by moving the slide means axially of the hollow member toward the fixed mold surface, the improvement characterized in that:

• (a) the slide means, which are defined by multi-part first and second slides telescoped on one another, are moved axially in supporting relationship with the other side wall of the channel-shaped part through different stroke lengths and at different stroke speeds;
• and
• (b) with the first radially inwardly most disposed slide being moved farther and faster than the second radially outwardly most disposed slide to produce a rolling movement of the material of the channel-shaped part with the radially inwardly most disposed material thereof moving farthest and being welded to the material of the channel-shaped part lying on the fixed mold surface.