Blow molding a closed plastic drum including two speed compression molding of an integral handling ring

DETAILED DESCRIPTION It is the object of the present invention to overcome the above problems heretofore presented with one-piece blow-molded closed plastic drums having an integral compression-molded handling ring by providing a drum construction and method of manufacturing same which eliminates stress concentrations heretofore formed in such drums and provides a construction which will resist forces on the outside surface of the handling ring causing breakage of the drum due to impact upon dropping or tipping of a filled drum.
It has been found by this invention that the above object may be accomplished by providing a one-piece blow-molded closed plastic drum which includes a generally cylindrical body portion, a bottom integrally-molded with a lower end of the body portion and a head portion integrally-molded with an upper end of the body portion and defining a top and a transition area around and between the upper end of the body portion and the top.
The drum has a handling ring integrally-molded with the drum which has a leg extending upwardly from the transition area and a grippable member extending generally outwardly from the upper end of the leg and which is parrot beakable.
In accordance with this invention, the transition area preferably has (1) an outside curved surface of a predetermined radius so that an outside surface of the body portion is positioned in a tangential plane in close proximity to a tangential plane along an outer circumferential surface of the handling ring and/or (2) an inside curved surface with at least one radius, preferably defining a double ogee with three predetermined radii, so that no acute angles are formed between the inside surfaces at the transition area.
With this improved configuration of outside curved surface on the transition area of the drum, the outside surface of the drum body portion will absorb forces of impact on the drum when the drum is dropped or tipped on its side, rather than an inordinate portion of such forces being directed to the handling ring causing extreme flexing thereof and breaking of the drum in the transition area