Receptacles – Table dish
Reexamination Certificate
1998-12-09
2001-12-18
Castellano, Stephen (Department: 3727)
Receptacles
Table dish
C220S636000, C220S626000
Reexamination Certificate
active
06330956
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to bowls having an upper bowl portion formed of one plastic material and a lower base portion formed of a second plastic material. This invention particularly relates to such bowls having a side wall or floor formed with bleed passages for the escape of gas generated as the base portion is molded to the bowl portion so as to define an annular boundary between the two different materials.
2. Description of Prior Developments
When molding a plastic bowl using a two-step molding process, it is difficult and costly to mold the bottom portion of the bowl with a diameter larger than the top portion so as to form a truncated-cone shaped profile. That is, when such a bowl is molded from different plastic or rubber materials on the upper and lower portions, an inwardly directed circumferential ledge is generally formed along the external annular boundary line between the two materials.
When building a mold which forms this annular circumferential boundary ledge, it was found that the walls of the upper portion of the bowl had to be virtually perfectly cylindrical rather than conical in order to extract the bowl from the mold. Otherwise, an expensive and complicated split mold was required.
Rather than using an expensive split mold, a two-part, two-material plastic bowl can be molded in the shape of an inverted truncated cone having an outwardly directed ledge defining the external boundary line between the two plastic materials. While this configuration simplifies the mold design, it creates a problem relating to the removal of gas from the mold during molding of the lower portion of the bowl to the upper pre-formed portion.
Accordingly, a need exists for a method and apparatus for molding a plastic pet bowl in the shape of an inverted truncated cone using a simple mold.
A further need exists for such a method and apparatus which effectively and inexpensively bleeds off excess gas during molding.
SUMMARY OF THE INVENTION
The present invention has been developed to fulfill the needs noted above and therefore has as an object the provision of a method and apparatus for efficiently and economically molding a pet bowl using one plastic material for its base and second plastic material for its top.
Another object of the invention is to provide a method and apparatus for molding a non-skid base on a plastic bowl having outwardly and upwardly diverging walls.
Still another object of the invention is the provision of a method and apparatus for molding a non-skid base on a plastic bowl so that molding gasses can be easily and economically vented.
Yet another object of the invention is the provision of a pet bowl having a plastic upper portion and a plastic or rubber non-skid base which has plastic or rubber extensions or runners decoratively arranged on the upper portions for venting gas during molding of the base to the upper portion.
These and other objects are met by the present invention which is directed to a method and apparatus for molding a non-skid base to a plastic bowl. The bowl can be formed with an upwardly and outwardly flaring sidewall in a profile similar to an inverted truncated cone. A circumferential ridge separates the base from the bowl along a molding boundary line. The bowl may be formed with bleed holes and/or bleed channels to allow molding gas to escape the mold cavity during molding of the base to the bowl.
In one embodiment of the invention, gas bleed holes can be formed in the floor of the bowl. This approach eliminates the need for forming an annular step, ledge or other discontinuity in the side wall of the bowl. In this case, the bowl and base can have rounded profiles which taper into one another along an external annular molding boundary line.
Molding of the base to the bowl can be carried out in the same mold in which the bowl is originally molded or in a separate mold. If separate molds are used, the bowl is removed from its original mold and placed in a second mold for receiving a base. The two molds can be included in one machine wherein the molding of the bowl is followed by the molding of the base in two separate steps.
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Castellano Stephen
J.W. Pet Company
Rosenman & Colin LLP
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