Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Shaping against forming surface
Reexamination Certificate
1999-05-25
2001-06-12
Heitbrink, Jill L. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Shaping against forming surface
C264S334000, C264S335000, C425S556000, C425S437000, C425S438000, C425S444000, C425SDIG005
Reexamination Certificate
active
06245277
ABSTRACT:
The present invention relates generally to manufacture of plastic containers for containing paint or other materials, and more particularly to a new apparatus and method for injection molding plastic containers that are adapted to be sealed off by removable lids.
FIELD OF THE INVENTION
As is well known, the ordinary one-gallon paint can has been made of steel and is provided with a friction fit lid that also is made of steel. In the paint industry prevention of leakage is important since paint cans frequently encounter rough handling while being transported or stacked for storage or retail display. Consequently a substantially hermetic seal is required between the paint can and its lid. This is achieved by a friction fit air-tight engagement between the lid and container which is such as to permit the lid to be removed manually using a suitable prying tool. In addition, the standard metal paint can lid does not protrude beyond the perimeter of the paint can so that as to prevent accidental disengagement of the lid. The configuration of the interlocking connection between the standard metal paint cans and their metal lids is such that the lids remain tightly in place even when subjected to the action of paint shaking machines or to other severe handling or shock conditions. Further the lids can be re-attached to again provide a fluid tight seal with the container. However standard metal paint cans have certain shortcomings, one of which is the tendency to corrode.
In the past, efforts have been made to provide containers for paint that are made of plastic. For example, U.S. Pat. No. 5,097,977, issued Mar. 24, 1992 to R. Straub illustrates a closure assembly for a container that comprises a snap ring connected to the top of the container and a lid that is removably attached to the ring so as to close off the container. A similar arrangement is disclosed by U.S. Pat. No. 4,619,373, issued Oct. 28, 1986 to H. W. Galer. Other plastic paint can designs and/or apparatus for injection molding same are illustrated by the following U.S. Pat. No. 4,777,004, issued Oct. 11, 1988 to H. W. Galer; U.S. Pat. No. 4,619,373, issued Oct. 28, 1986 to H. W. Galer; U.S. Pat. No. 4,349,119 issued Sep. 14, 1982 to I. Letica; U.S. Pat. No. 4,512,494, issued Apr. 23, 1985 to J. W. Von Holdt; U.S. Pat. No. 4,383,519 issued May 17, 1983 to I. Letica; U.S. Pat. No. 4,293,080, issued Oct. 6, 1981 to I. Letica; and U.S. Pat. No. 3,977,563 issued Aug. 31, 1976 to W. G. Holt.
However, prior plastic paint can/lid designs have suffered from various limitations, such as need for complex and costly injection molds, not capable of being handled by standard filling, labeling and packaging machinery, inadequate strength, unreliable sealing of lid to container, and/or lack of appeal to prospective customers.
A new plastic container/removable lid construction is disclosed and claimed in my copending U.S. application Ser. No. 09/281,367, filed Mar. 30, 1999. The plastic container construction disclosed in my copending application offers numerous advantages. It has a one-piece construction free of any seams or crimps, does not rust internally and requires no internal protective coating, has a higher dynamic compression that metal paint cans, can be manufactured in different colors and surface finishes, weighs less than a metal can of comparable size and volume, can be molded with embossed printing so as to eliminate the need for a subsequent labeling operation, and is adapted to be closed off by a complementary lid that makes an air-tight seal and can be removed and replaced without damage. The container rim and a complementary lid are adapted to interlock in a manner which provides an air-tight friction fit, permits the lid to be easily removed by use of a prying tool, and assures that the lid cannot be accidentally dislodged as a consequence of being subjected to impact, shock or stress in the course of being stacked or transported.
SUMMARY OF THE INVENTION
The primary object or purpose of the invention is to provide a new and improved injection molding apparatus for use in manufacturing plastic containers that embody the construction disclosed and claimed in said copending U.S. application Ser. No. 09/281,367.
A more specific object is to provide an injection mold apparatus for manufacturing one-piece plastic containers having lid-receiving rims that project inwardly of the side walls of the containers.
Another specific object is to provide an injection mold assembly for molding plastic containers that does not require a collapsible core.
A further object is to provide an improved method of injection molding an improved plastic container for use in storing paint or other material.
A further is to provide a novel method and apparatus for manufacturing a plastic container that is adapted to releasably interlock with a lid in a manner that provides positive line contact sealing of the container.
Another object is to provide a novel method and apparatus for injection molding a one-piece, substantially straight-sided plastic container for paint or other liquid or particulate material that is characterized by a rim-to-lid interlock which provides an air-tight friction fit, permits the lid to be easily removed by use of a prying tool, and assures that the lid cannot be accidentally dislodged as a consequence of being subjected to impact, shock or stress due to rough handling in the course of being stacked or transported.
Still other objects and features of the invention are disclosed or rendered obvious by the following detailed description which is to be considered together with the accompanying drawings.
REFERENCES:
patent: 3977563 (1976-08-01), Holt
patent: 4125246 (1978-11-01), Von Holdt
patent: 4286766 (1981-09-01), von Holdt
patent: 4293080 (1981-10-01), Letica
patent: 4349119 (1982-09-01), Letica
patent: 4383819 (1983-05-01), Letica
patent: 4397404 (1983-08-01), Blanchette
patent: 4491238 (1985-01-01), Tobolt
patent: 4512494 (1985-04-01), von Holdt
patent: 4524882 (1985-06-01), Buc
patent: 4619373 (1986-10-01), Galer
patent: 4648834 (1987-03-01), Von Holdt
patent: 4777004 (1988-10-01), Galer
patent: 5097977 (1992-03-01), Straub
patent: 5476187 (1995-12-01), Marisco
patent: 5536161 (1996-07-01), Smith
patent: 5932164 (1999-08-01), Allen
Clementi John
Heitbrink Jill L.
Pandiscio & Pandiscio
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