Multiple cavity container with method and apparatus for forming the same
A plastic container for liquid or the like has an open top, with exterior threads to receive a cap, opening into a main cavity defined by the wall of the container. An inward depression is formed in the wall of the container and formed with threads so that the outer wall of the main cavity forms the interior wall of a secondary cavity. A threaded cap mates with the threads formed on the secondary cavity to close the secondary cavity. The container is preferably formed by blow molding a parison or a stretched molded tube formed with an exterior thread. One of the blow mold halves includes an interiorly extending rotatable protuberance, formed with threads, which create threads on the interior of the second cavity. As the molds are retracted, the protuberance is rotated to separate from the formed threads on the wall of the secondary cavity.
This application claims priority of U.S. provisional patent application Ser. No. 60/490,797, filed Jul. 28, 2003, said application being incorporated herein in its entirety by reference.
FIELD OF THE INVENTIONThis invention relates to plastic containers having a plurality of cavities and to methods of forming such containers by blow molding or stretch molding, and to unique molds for use in such molding process.
BACKGROUND OF THE INVENTIONContainers having multiple compartments or cavities for packaging a plurality of different materials, such as liquids, powders, creams, and the like, have been proposed and have a variety of uses. Additionally, one of the compartments may contain articles such as a prize, or the like. Typically, such containers have a primary cavity and a smaller, secondary cavity containing some substance or product which is useful in connection with the liquid or other material stored in the primary cavity.
As an example, U.S. Patent Application Publication No. 2002/0008116 discloses a liquid container with a secondary compartment for retaining a supplement, such as a vitamin, mineral, analgesic, antibiotic, or other medicine, flavor, or other color additive or nutritional substance, which is useful in connection with the liquid contained in the primary container. Often, the secondary cavity of the container will include some additive which is intended to be mixed with the liquid in the primary container when the liquid is poured out of the container. U.S. Pat. No. 5,215,214 discloses a multi-compartment container of that type. U.S. Pat. No. 5,992,677 discloses a container adapted to store a liquid in the primary compartment and an article or prize in the secondary compartment. Certain containers are adapted to store products used for laundering, such as a detergent solution in the primary container and a bleach in the secondary container as disclosed in U.S. Pat. No. 4,618,444. U.S. Pat. No. 3,658,204 discloses a container for a two-component varnish, such as a urethane, wherein the components must be mixed shortly before use. Other uses of a plural cavity container might be to store a relatively large volume of face lotion or body lotion and a relatively expensive cream that is to be used only on a portion of the body, such as the eyes, in the secondary container.
As exemplified by the above-noted patents, these multi-cavity containers are often relatively complex, involving a substantial number of parts which must be assembled, and are accordingly rather expensive. One of the least expensive and most useful methods of forming liquid containers is blow molding, wherein a parison is first extruded and is then disposed in a two-part mold. Gas is injected into the interior of the parison, causing the formation of a central cavity which presses the walls of the parison against the opposed surfaces of the two mold halves to form a finished container. The economy and efficiency of this process has led to its wide scale adoption for the formation of plastic containers for liquids.
SUMMARY OF THE INVENTIONThe present invention is accordingly directed toward a unique multi-cavity container which is adapted to formation by blow molding or its related variant, stretch molding. The invention is further directed toward unique process and apparatus for blow molding and stretch molding capable of forming the multi-cavity containers in a precise and economical manner.
The novel containers of the present invention are characterized by an exterior wall enclosing a main cavity and open at one end to form a spout through which the main cavity may be filled and the contents thereof may be poured out. This open top typically has threads formed about its exterior, to receive a closing cap having mating threads on its interior walls. The container further comprises one or more secondary cavities. Each secondary cavity in the container, comprises a depression formed in the exterior wall of the container such that the exterior wall in the region of the depression forms the interior walls of the respective secondary cavity. Female threads are formed about the periphery of the edge of each secondary cavity and each secondary cavity may be closed by a cap member which has male threads which engage the female threads to close off the cavity.
Any number of the secondary cavities may be formed about the exterior wall of the container. The secondary cavities are typically formed with central axes at right angles to the central axis of the main cavity, so that the cap for the main cavity is oriented at 90 degrees to the caps for the secondary cavities, but this relation is not critical.
The secondary cavity may alternatively be formed with engagement for a snap-on lid rather than a screw cap.
In the process of forming the novel containers of the present invention, by blow molding, or its variant, stretch molding, novel tooling is employed wherein the blow molding forms threads on the pour spout for the main cavity in a normal manner by pressing the surface of the parison against threaded sections formed on the two die halves. Each secondary cavity is formed by a respective male protrusion that extends inwardly, toward the opposing die half, from one of the side walls of a die half. The protrusion forms an indentation in the exterior wall of the parison as it blows out to form the interior wall of the secondary cavity. The protuberance contains formations on its outer surface, which form female threads on the wall of the second cavity where it joins the main surface of the exterior wall of the main cavity, i.e. at the entrance to the second cavity. The engagement of the threaded formation on the protuberance and the female threads thus formed at the wall of the secondary cavity prevent the. protuberance from withdrawing axially from the completed container section. Accordingly, the protuberance is rotated so as to free its threads from the molded threads in the container wall as the mold halves separate to release a molded container.
The formation of female threads in the wall of the secondary cavity by blow molding is an important aspect to the present invention. The interior walls of blow molded bottles are necessarily of indeterminate dimension because of variations in thickness of the wall of the blow molded product. By forming the exterior threads on the exterior wall of the blow molded cavity, which forms an interior wall of the secondary cavity, high quality, precision threading is formed.
BRIEF DESCRIPTION OF THE DRAWINGSOther objects, advantages and applications of the present invention will be made apparent by the following descriptions of preferred embodiments of the invention. The description makes reference to the accompanying drawings in which:
Referring to the drawings, a typical multi-cavity container formed in accordance with the present invention is illustrated in
The container, generally indicated at 10, has an open top 12 surrounded by an annular spout 14. Threads 16 are formed about the outer periphery of the spout 14. The top 12 opens into a primary container volume 18 enclosed by front and rear side walls 20 and 22, and a bottom wall 24 as well as side walls 26 connecting the front, rear and bottom walls.
The annular spout 14 may be closed off with a pouring spout 28, shown in exploded relation, which has threads on its interior cap (not shown) which mate with the threads 16 to close off the top 12. The front wall 20 of the container is formed with a central, cylindrical, inwardly directed depression 30 which forms the wall of a secondary cavity. Threads 32 are formed on the wall of the depression 30, bounding the front surface 20 of the container. This opening may be closed off with a cap 34 having a reduced diameter section 36 with threads 38 formed about its surface. The threads 38 engage with the threads 32 to retain the cap 34 at the opening of the secondary cavity formed by the depression 30. A shoulder 40 formed on the cap 34 at the margin of the reduced diameter section 32 bears against the outer surface of the wall 20 surrounding the recess 30 to seal the contents in the container.
The method of forming the container 10 by blow molding is generally illustrated in
As shown in
After the parison cools, the molding machine draws the die halves 52 and 54 away from one another. During this process it is necessary to rotate the protrusion 56 about its central axis so as to unscrew the threads 58 formed on the outer surface of the protrusion from the molded threads 60 formed by the protrusion threads in the parison 50. As illustrated in
The cap 116 has an outer contour which is figurative, in this case representing a human face 130, with a nose and the like. Cap 130 may be formed by the blow molding process illustrated in
The main cavity 154 is preferably closed off by a pump top 164 which has threads (not shown), which engage with the threads 151.
The container 150 and its top 164 might contain face lotion or body lotion, or the like, in the main cavity 154, with a more expensive body care product, such as an eye care product, in the smaller, secondary cavity 156.
Another embodiment of the invention is illustrated in
The cap for the container 180 is generally indicated at 184 and constitutes a toroidal body, having threads 186 formed on its interior wall by a blow molding process of the type disclosed in
The cap for closing off the secondary cavity 202, generally indicated at 210, is itself a blow molded container. The cap 210 is disc-shaped, with a hollow interior. Threads 212 are formed about its outer perimeter and a spout 214 formed with exterior threads 260 allows access to the interior of the cap 210 and may be closed off with a threaded cap 218. This forms a three cavity container, shown in
Another embodiment of the invention, constituting a squeeze container, generally indicated at 230, is shown in side-perspective view in
The bottle 230, which is preferably formed by the method illustrated in
The rear of the container is formed with a series of corrugated louvers 250 which take the form of concentric rings. The center section 252, in the middle of the louvers 250, may be depressed by means of spots 254, to decrease the volume of the container 230 and force contents out of the spout 234.
Claims
1. A multi-cavity container having an outer wall and bottom and an open top, communicating with a main cavity defined by the wall and bottom;
- a secondary cavity formed by a depression in the outer wall extending inwardly toward the center of the main cavity;
- screw threads formed about the perimeter of the depression adjacent the outer wall of the container, and
- caps adapted to close off the main cavity and the secondary cavity.
2. The container of claim 1 wherein the depression in the side wall of the container forming the secondary cavity is cylindrical.
3. The container of claim 1 which is formed by a blow molding process which also forms threads about the perimeter of the depression forming the secondary cavity.
4. The container of claim 3 formed by a pair of mold halves including one mold half which has an inwardly extending protrusion rotatably supported within the wall of the mold half, thread producing formations on the sides of the protrusion within the die half, and means for rotating the protrusion relative to the mold half as it is withdrawn from the finished product, so as to release threads formed on the interior of the depression forming the secondary cavity from the thread-producing formations on the exterior of the protrusion.
5. The container of claim 1 including a plurality of depressions in the outer wall forming second and subsequent secondary cavities
6. The method of forming a blow molded, multi-cavity container, having a side wall defining a main cavity, an inwardly directed depression in the side wall defining an interior wall of a secondary cavity, and threads formed about the perimeter of said depression adjacent to the container side wall, comprising:
- disposing a parison between two halves of an open mold, one half having a cylindrical member rotatably supported in the mold wall and extending into the mold cavity and containing projections on its outer surface capable of forming threads;
- closing the mold and introducing gas to the interior of the parison to expand the parison against the mold to form a container having a central cavity and a depression formed by the cylindrical member;
- and rotating the cylindrical member as the mold halves are opened to release the cylindrical member from threads formed on the interior of the depression on the side wall of the resulting container.
7. A blow molding tooling for forming a container having a main cavity enclosed by an outer wall and at least one threaded secondary cavity formed by a depression in the outer wall and extending inwardly toward the center of the main cavity, said tooling including one mold half which has an inwardly extending protrusion rotatably supported within the wall of the mold half to form said depression, and thread-producing formations on an exterior surface of the protrusion within the mold half, said tooling further comprising means for rotating the protrusion relative to the mold half as the mold half is withdrawn from the finished product, so as to release threads formed on the interior of the depression forming the secondary cavity from the thread-producing formations on the exterior of the protrusion.
Type: Application
Filed: Jul 26, 2004
Publication Date: Mar 31, 2005
Inventor: Erik Lipson (Philadelphia, PA)
Application Number: 10/898,805