Method of handling a plastic container having a moveable base

A plastic container comprises an upper portion including a finish defining an opening into the container, a lower portion including a base defining a standing surface, a sidewall extending between the upper portion and the lower portion, the sidewall defining a longitudinal axis, and at least one substantially transversely-oriented pressure panel located in the lower portion. The pressure panel is movable between an outwardly-inclined position and an inwardly-inclined position to compensate for a change of pressure inside the container. The standing surface defines a standing plane, and the entire pressure panel is located between the standing plane and the upper portion of the container when the pressure panel is in the outwardly-inclined position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a hot-fill container structure that allows for the removal of vacuum pressure within the container, and more particularly, to a hot-fill container structure having an invertible vacuum panel deeply set into the base of the container. The present invention also relates to methods of making and processing containers having an invertible vacuum panel deeply set into the base of the container.

2. Related Art

So called “hot-fill” containers are known in the art. Plastic containers, such as PET containers, are filled with various liquid contents at an elevated temperature, typically around 185 degrees F. Once the liquid within the container cools, the volume of the contained liquid reduces, creating a vacuum within the container that pulls inwardly on the side and end walls of the container. This in turn leads to deformation of the plastic container if it is not constructed rigidly enough to resist the vacuum forces.

Typically, vacuum pressures have been accommodated by the use of vacuum panels that deflect inwardly under vacuum pressure. Known vacuum panels are typically located in the container sidewall and extend parallel to the longitudinal axis of the container, and flex inwardly under vacuum pressure toward the longitudinal axis.

It is also known in the prior art to have a flexible base region to provide additional vacuum compensation. All such known prior art containers, however, have substantially flat or inwardly recessed base surfaces that deflect further inward to compensate for the vacuum forces. Known flexible base regions have not been able to adequately compensate for the vacuum forces on their own (i.e., vacuum panels in the sidewall and/or or other reinforcing structures are still required).

Therefore, there remains a need in the art for plastic containers that overcome the aforementioned shortcomings of the prior art.

BRIEF SUMMARY OF THE INVENTIONS

The present invention relates to a polymeric or plastic container having an invertible pressure panel located in the container base. The pressure panel is movable from an initial, outwardly-inclined position, to an inverted, inwardly-inclined position, in order to reduce the volume of the container and accommodate for vacuum forces within the container. The entire pressure panel is set deeply into the base of the container, such that no portion of the pressure panel extends beyond the standing ring, regardless of whether the pressure panel is in the initial position or the inverted position. This configuration can allow the container to be supported by the standing ring regardless of whether the pressure panel is in the initial position or the inverted position.

Other plastic containers suitable for containing a liquid are disclosed in U.S. Pat. No. 5,261,544 issued to Weaver, Jr.; and U.S. Pat. No. 5,908,128 issued to Krishnakumar et al.

As disclosed in Weaver, Col. 5, lines 26-29, a polymeric container should be blow-molded with a minimum thickness of at least about 10 mils.

As disclosed in Krishnakumar, Col. 4, lines 17-24, a container of approximately 20 ounces in volume made from ‘bottle grade’ PET (having about 1.5% comonomer and an intrinsic viscosity of about 0.80) may have a side-wall thickness on the order of 0.4 mm, or 15.7 mils, in order to withstand containing a heated liquid.

According to one exemplary embodiment, the present invention relates to a plastic container comprising an upper portion including a finish defining an opening into the container, a lower portion including a base defining a standing surface, a sidewall extending between the upper portion and the lower portion, the sidewall defining a longitudinal axis, and at least one substantially transversely-oriented pressure panel located in the lower portion. The pressure panel can be movable between an outwardly-inclined position and an inwardly-inclined position to compensate for a change of pressure inside the container. The standing surface can define a standing plane, and the entire pressure panel can be located between the standing plane and the upper portion of the container when the pressure panel is in the outwardly-inclined position.

According to another exemplary embodiment, the present invention relates to a method of processing a plastic container, comprising the steps of (a) providing a plastic container having an upper portion including a finish, a sidewall, a lower portion including a base defining a standing surface, and a substantially transversely-oriented pressure panel located in the base; (b) introducing heated liquid contents into the plastic container with the pressure panel located in an outwardly-inclined position entirely between the standing surface and the upper portion; (c) capping the plastic container; and (d) moving the pressure panel to an inwardly-inclined position entirely between 30 the standing surface and the upper portion.

According to yet another exemplary embodiment, the present invention relates to a method of blow molding a plastic container, comprising the steps of (a) enclosing a softened polymer material within a blow mold defining a mold cavity, the blow mold comprising at least first and second side mold portions and a base mold portion; (b) inflating the polymer material within the blow mold to at least partially conform the polymer material to the blow mold cavity; and (c) displacing the base mold portion with respect to the first and second side mold portions to form a transverse pressure panel deeply set within a base portion of the plastic container.

Further objectives and advantages, as well as the structure and function of preferred embodiments will become apparent from a consideration of the description, drawings, and examples.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention are discussed in detail below. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. While specific exemplary embodiments are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without departing from the spirit and scope of the invention. All references cited herein are incorporated by reference as if each had been individually incorporated.

As discussed above, to accommodate vacuum forces during cooling of the liquid contents within a hot-fill container, plastic containers have typically included a series of vacuum panels located around the sidewall and/or in the base portion. The vacuum panels deform inwardly, and the base deforms upwardly, under the influence of the vacuum forces. This configuration attempts to prevent unwanted distortion elsewhere in the container. However, the container is still subjected to internal vacuum forces. The sidewalls and base merely provide a suitably resistant structure against that force. Additionally, the vacuum panels in the sidewall can undesirably detract from the appearance and feel of the container, and limit the design possibilities for the container.

Typically at a bottling plant, the containers are filled with a hot liquid and then capped before being subjected to a cold water spray, resulting in the formation of a vacuum within the container. The container structure needs to be able to cope with this vacuum force. U.S. patent application Ser. No. 10/529,198, filed on Dec. 15, 2005, the entire content of which is incorporated herein by reference, discloses hot-fill containers that provide for the substantial removal or substantial negation of the vacuum pressure within the containers. The disclosed containers include a transversely-oriented pressure panel located in the container base. The pressure panel is movable between an initial, outwardly inclined position, and an inverted, inwardly inclined position, in order to reduce the volume of the container and accommodate for vacuum forces within the container. The present invention relates to additional embodiments of this concept in which the pressure panel is set deeply into the base of the container, such that no portion of the pressure panel extends beyond the standing ring, regardless of whether the pressure panel is in the initial position or in the inverted position. This configuration can allow the container to be supported by the standing ring regardless of whether the pressure panel is in the initial position or the inverted position.

Referring toFIGS.1-4, an exemplary embodiment of a plastic container10according to the present invention is shown. The container10can include an upper portion12including a finish14that defines an opening into the interior of the container10. As shown, the finish14can include threads16or other structures adapted to secure a closure (not shown) onto the container10. The container10can also include a lower portion18having a base20, and a sidewall22extending between the upper portion12and the lower portion18. The base20can define a standing surface21that is substantially flat and adapted to support the container10in a substantially upright position (e.g., with longitudinal axis A substantially perpendicular to the surface on which container10is resting).

In the exemplary embodiment shown, the sidewall22is substantially tubular and has a substantially circular transverse cross-sectional shape. Alternative cross-sectional shapes can include, for example, an oval transverse cross-section; a substantially square transverse cross-section; other substantially polygonal transverse cross-sectional shapes such as triangular, pentagonal, etc.; or combinations of curved and arced shapes with linear shapes. As will be understood by one of ordinary skill in the art, when the container10has a substantially polygonal transverse cross-sectional shape, the corners of the polygon are typically rounded or chamfered. Although the container10is shown as having reinforcing ribs or rings23in the sidewall22to resist paneling, dents and other unwanted deformation of the sidewall, particularly under vacuum force, other embodiments are possible where the sidewall22is substantially devoid of such features (e.g., the sidewall22can be smooth like that of a conventional glass container).

As best seen inFIG.4, a portion of the base20can include a plurality of reinforcing ribs24, however other embodiments with or without the reinforcing ribs24are possible.

The lower portion18of the container10, and particularly the base20, can include a substantially transversely-oriented pressure panel26. The pressure panel26can be moved between an outwardly-inclined position (shown inFIGS.1and2) and an inwardly-inclined position (shown inFIG.3) in order to reduce the internal volume of the container10and compensate for any vacuum forces created within the container, for example, during the filling process. For example, the pressure panel26may substantially remove the internal vacuum that develops within the container10during a hot-fill process once the container10has been hot-filled, capped, and cooled.

As best seen in the sectional views ofFIGS.2and3, the pressure panel26can be deeply set into the container10in order to facilitate standing of the container10on its standing surface21regardless of whether the pressure panel26is located in the outwardly-inclined position (FIG.2) or the inwardly-inclined position (FIG.3). In other words, the entire pressure panel26structure can be located between the plane P of the standing surface21and the upper portion12of the container10when the pressure panel26is in the outwardly-inclined position (FIG.2) and also when the pressure panel26is in the inwardly-inclined position (FIG.3).

According to the exemplary embodiment shown inFIGS.1-4, the lower portion18of the container10includes a concave outer wall portion30that extends from the lower end of the sidewall22to the standing surface21. The standing surface may be a ring or annular portion as shown inFIG.1, or may be discontinuous as shown inFIG.5. The pressure panel26is deeply set into the lower portion18of the container10via an inner wall32that extends from the standing surface21to the pressure panel26. The inner wall may therefore comprise an instep or hollow recessed portion between the pressure panel26and the standing surface21. In the exemplary embodiment shown, the inner wall32is parallel or nearly parallel to the longitudinal axis A of the container10, and provides the recessed portion with a concave annular ring shape; however, other configurations and/or inclinations of the inner wall32are possible that are not concave annular ring structures, and may have different angles as shown inFIGS.18-19with reference to the inner wall1120. In addition, one of ordinary skill in the art will know that other configurations besides the inner wall32may be implemented to set the pressure panel26deeply into the lower portion18. An annular, recessed channel34can be provided in the inner wall32adjacent the standing surface21to provide a further recessed concave ring structure in the inner wall32. In the exemplary embodiment shown, the annular recessed channel has a substantially square or annular cross-section, however, other shapes are possible for the channel to be inwardly stepped. Channel34can act as a rib member and reinforce the foot portion or standing surface21and/or facilitate stacking of multiple containers on top of one another, depending on the shape and size of the finish14and/or closure.

In the exemplary embodiment ofFIGS.1-4, the standing surface21, inner wall32, and outer wall30are substantially continuous about the circumference of the container10(seeFIG.4). However, as shown in the alternative embodiment of FIGS.5and6, andFIGS.27A-27E, the container10′ can have a standing surface21, inner wall32′, and outer wall30′ that are discontinuous.

The pressure panel or inner annular wall240has an inner periphery244and an outer periphery242, and is set, with respect to the longitudinal axis and the opening into the container, at an outward or downward angle prior to filling with a heated liquid. The outer annular wall includes support or foot portions230and the inner wall portions32′ extend from the standing surfaces21′ to the inner annular wall or pressure panel240. Radial webs or straps246are uniformly spaced apart and separate each support230. The web surface is closer to the finish than the footed contact surface, or expressed another way, the webs246are longitudinally displaced above the footed contact surface21′. In addition, each support230has a larger arcuate extent than that of each radial web246. The inner annular wall240extends within the concave outer annular wall30′. The outer periphery242of the inner annular wall or pressure panel240merges with the inner wall32′ of each of the supports230, and radially or circumferentially with the plurality of spaced-apart, horizontally disposed, radial webs or straps246located adjacent the outer periphery232of the standing surface of the base. Each of the webs246extends between the supports230and connects to the container sidewall22in the lower portion18at an elevation above the horizontal plane “P” extending through the standing surface21to form radius202such that web surface246is visible from a side of the container. Preferably the inner annular wall240and the central dimple or push up248merge via an annular hinge250at the foot of the push-up, comprising radius251.

In order to facilitate movement (e.g., folding) of the pressure panel26between the outwardly-inclined position ofFIG.2and the inwardly-inclined position ofFIG.3, pressure panel26can include a decoupling or hinge structure36that is located between the inner wall32and the pressure panel26. In the exemplary embodiment shown, the hinge structure36comprises a substantially flat, non-ribbed region, that is susceptible to folding, however, other configurations of the hinge structure, such as a crease, are possible.

Referring now particularly toFIG.4, the pressure panel26can comprise an initiator portion40and a control portion42. Both the initiator portion40and control portion42can comprise part of the pressure panel26that folds when the pressure panel26is moved from its initial position inFIG.2to its inverted position inFIG.3. The initiator portion40can be adapted to move or fold before the rest of the pressure panel26(e.g., before the control portion42). In the exemplary embodiment shown, the control portion42is at a steeper angle to the standing plane P than the initiator portion40, thereby resisting expansion of the pressure panel from the inverted state (FIG.3) to the initial state (FIG.2), for example, if the container10were accidentally dropped.

In order to maximize the amount of vacuum compensation from the pressure panel26, it is preferable for at least the control portion42to have a steep angle of inclination with respect to the standing plane P. As shown inFIG.2, the control portion42can be at a first angle alpha, with respect to the standing plane P. According to one exemplary embodiment, the first angle alpha, can be at least 10 degrees, and preferably is between about 30 degrees and about 45 degrees. According to this embodiment, the initiator portion1can be at a second angle beta, with respect to standing plane P, that is at least 10 degrees less than the first angle alpha.

When the pressure panel is inverted from the outward state (FIG.2) to the inward state (FIG.3), it can undergo an angular change that is approximately equal to its angle of inclination. For example, if the control portion42is initially set at an angle alpha, of about 10 degrees, it will provide an angular change of approximately 20 degrees. At such a low angle of inclination, however, it can be difficult to provide an adequate amount of vacuum compensation in a hot-filled container. Therefore it is preferable to provide the initiator portion40and control portion42with steeper angles. For example, with the control portion set at an angle alpha, of about 35 degrees, the pressure panel26will undergo an angular change of about 70 degrees upon inversion. According to this exemplary embodiment, the initiator portion40can be set at an angle beta, of about 20 degrees.

Referring toFIGS.22-23, a base portion of a container according to an alternative embodiment is shown, wherein the control portion of the pressure panel comprises a substantially continuous conical area extending around the base. According to this embodiment, the initiator portion140and the control portion142are set at a common angle, such that they form a substantially uniform pressure panel126. However, initiator portion140may still be configured to provide the least amount of resistance to inversion of pressure panel126, such that it still provides an initial area of folding or inversion. For example, the initiator portion140may have a smaller material thickness than the control portion142. According to the embodiment shown inFIGS.22-23, initiator portion140causes the pressure panel126to begin inversion at its region of widest diameter, near the hinge structure136.

Additional structures may be added to the pressure panel126in order to add further control over the inversion process. For example, the pressure panel126may be divided into fluted regions, as shown inFIGS.6and7. As shown, the fluted regions145can be outwardly convex, resulting in inward creases127between each outward flute and evenly distributed around the container's longitudinal axis to create alternating regions of greater and lesser angular inclination. Referring toFIGS.24-26in particular, panel portions145that are convex outwardly, and evenly distributed around the central axis create regions of greater angular set219and regions of lesser angular set218. The angular set in the midline218of each of the plurality of flutes145has lesser angular set gamma than the angular set delta in the plurality of creases219created between each fluted panel portion145. This may provide for greater control over the inversion of the panel. Such geometry provides increased resistance to reversion of the panel, and a more even distribution of forces when in the inverted position. This type of geometry can provide increased resistance against the panel returning from the inward position (FIG.10) to the outward position (FIG.9), for example, if the container were dropped. The fluted configuration can also provide more even distribution of forces on the pressure panel126. According to an alternative embodiment, the flutes can be inwardly concave. Inwardly directed flutes offer less resistance to initial inverting forces, coupled with increased resistance to reverting back to the original, outward position. In this way, they behave in much the same manner as ribs to prevent the panel being forced back out of the outwardly inclined position, but allow for hinge movement from the first outwardly inclined position to the inwardly inclined position. Such inwardly or outwardly directed flutes or projections function as ribs to increase the force required to invert the panel. Further details regarding the pressure panel and fluting are disclosed in co-pending U.S. patent application Ser. No. 10/529,198, filed on Dec. 15, 2005, the entire content of which is incorporated herein by reference.

FIGS.13to15show another exemplary embodiment of a container that can be used as described herein. The container includes an upper portion1102, shoulder1104, body1106and base1108. The upper portion1102includes an opening into the container which may be closed and sealed, such as via a screw cap using thread1112.

The container body1106in the present example includes ribs1114in a first region thereof and panels1116in second portions thereof. Panels1116in this example act as vacuum panels as discussed below and also facilitate gripping of the container by a consumer, but in other examples may be configured to serve only as grip panels and not pressure panels. In another example, vacuum panels may be placed in the container body separately from the grips or without the grips.

The container base1108includes standing ring or bearing surface1118on which the container rests when in an upright position. Adjacent the standing ring1118is a recess or instep forming a first wall1120which joins pressure panel or second wall1124via a hinge structure1122. An inwardly projecting push-up or section1126is provided in the center of the base1108. The panel or second wall1124may include creases1128as shown which aid control over the configuration of the panel or second wall1124as it moves between outwardly and inwardly inclined positions.

The container ofFIGS.13to15is particularly adapted to hot-fill applications but may be used in other applications where there are changes in pressure inside the container.

According to one hot-filling method using the container ofFIGS.13-15, the container is provided to a filling station with the second wall1124configured as shown inFIGS.14and15. The container is then filled with hot or heated liquid and sealed, for example, using a screw cap. As the container cools, contents of the container (particularly the headspace), contract. This causes the pressure in the container to drop. Cooling may be accelerated, for example, by spraying the outside of the container with water for example in a cooling tunnel or station.

To prevent unwanted deformation of the container caused by the reduction in internal pressure, one or both pressure panels1116,1124are configured to move inwards to reduce the container volume and increase the internal pressure of the container. In one example, at least the panels1116provided in the container sidewall are adapted to move inwards through action of the vacuum force generated inside the container during cooling, and in another example the panel1124is adapted to move inward through action of the vacuum force generated inside the container during cooling. In a third example, both move inward, and in a further example, the container sidewalls are subjected to vacuum force prior to the base.

In the present example, panel1124is also configured to move to adjust the container volume. More particularly, panel1124is configured to invert about hinge structure1122from being outwardly inclined as shown inFIGS.14and15to being inwardly inclined (not shown).

Inversion of the panel1124may be initiated by engagement of a pusher or other external mechanical force against the base1108, preferably the centrally located push-up1126of the base1108. Additionally or alternatively, the panel1124may include an initiator portion that is configured to initiate or cause the rest of the panel to move between the outwardly and inwardly inclined positions. The initiator portion may reduce or obviate the need for a pusher, providing for movement of the panel1124due to the forces generated by the pressure differential between the inside and outside of the container. To this end, the initiator portion may have a lower angle of inclination than other portions of the panel1124relative to the standing plane formed by the standing ring1118.

According to preferred embodiments, opposing vacuum panels1116are subjected to vacuum force prior to repositioning of the base. More preferably, the vacuum panels1116move inwards prior to movement of the second wall30or panel1124to the inwardly inclined position. Other methods of using containers as described herein can also be used with the container ofFIGS.13-15.

It will be noted that the instep or first wall1120is configured so as to elevate the panel1124and other portions of the base1108above the standing ring1118when the panel1124is outwardly inclined. Such a configuration provides improved container stability during the filling operations. However, the instep or first wall1120may be recessed to a lesser extent such that a portion of the base extends below the standing ring1118when the panel1124is outwardly inclined. As will be appreciated, this will mean that different portions of the container base1108act as the standing ring depending on whether the panel or second wall1124is inwardly or outwardly inclined.

The container shown inFIGS.13to15may also be used in pasteurisation processes. According to an example such process, the container is filled with the panel1116,1124in the inward position and then sealed. The container and its contents are then heated, causing an increase in internal pressure. As a result of this the panels1116,1124move to an outward position. After the heating stage of the pasteurisation process is completed and the container is cooled, the panels1116,1124preferably revert to the inwardly inclined position.

According to preferred embodiments, different stages of the filling and/or pasteurisation processes may be performed at different stations within a filling or processing facility. To this end, the container may be conveyed in between stages or during a particular stage depending on system requirements and preferences.

As stated above, the containers according to the present invention may be manufactured with the base panel extending above or below the standing ring, providing for various degrees of container stability during the filling operations.

The process of positioning the moveable portion of a base of the container into a first filling position or to a second position after filling a hot product into the container and after creating a vacuum by cooling, may be further controlled by stabilizing the container in a holding device, or the containers may also be stabilized by supporting the neck of the container (FIG.28), as discussed below.

The processing of a container, can be accomplished as part of a conveyor system. In one such system, as seen inFIG.29, containers C can be conveyed singularly to a combining system that combines container holding devices and containers. The combining system ofFIG.29includes a container in-feed518aand a container holding device in-feed520. As will be more fully described below, this system may be one way to stabilize containers with projected bottom portions that are unable to be supported by their bottom surfaces alone. Container in-feed518aincludes a feed scroll assembly524, which feeds and spaces the containers at the appropriate spacing for merging containers C into a feed-in wheel522a. Wheel522acomprises a generally star-shaped wheel, which feeds the containers to a main turret system530and includes a stationary or fixed plate523athat supports the respective containers while containers C are fed to turret system530, where the containers are matched up with a container holding device H and then deactivated to have a projecting bottom portion.

Similarly, container holding devices H are fed in and spaced by a second feed scroll526, which feeds in and spaces container holding devices H to match the spacing on a second feed-in wheel528, which also comprises a generally star-shaped wheel. Feed-in wheel528similarly includes a fixed plate528afor supporting container holding devices H while they are fed into turret system530. Container holding devices H are fed into main turret system530where containers C are placed in container holding devices H, with holding devices H providing a stable bottom surface for processing the containers. In the illustrated embodiment, main turret system530rotates in a clock-wise direction to align the respective containers over the container holding devices fed in by star wheel528. However, it should be understood that the direction of rotation may be changed. Wheels522aand528are driven by a motor529(FIG.30), which is drivingly coupled, for example, by a belt or chain or the like, to gears or sheaves mounted on the respective shafts of wheels522aand528.

Container holding devices H comprise disc-shaped members with a first recess with an upwardly facing opening for receiving the lower end of a container and a second recess with downwardly facing opening, which extends upwardly from the downwardly facing side of the disc-shaped member through to the first recess to form a transverse passage through the disc-shaped member. The second recess is smaller in diameter than the first so as to form a shelf in the disc-shaped member on which at least the perimeter of the container can rest. As noted above, when a container is deactivated, its vacuum panels will be extended or projecting from the bottom surface.

The extended or projecting portion is accommodated by the second recess. In addition, the containers can then be activated through the transverse passage formed by the second recess, as will be appreciated more fully in reference toFIGS.34-35described herein.

In order to provide extra volume and accommodation of pressure changes needed when the containers are filled with a hot product, such as a hot liquid or a partly solid product, the inverted projection of the blow-molded containers should be pushed back out of the container (deactivated). For example, a mechanical operation employing a rod that enters the neck of the blow-molded container and pushes against the inverted projection of the blow-molded container causing the inverted projection to move out and project from the bottom of the base, as shown inFIGS.34-35. Alternatively, other methods of deploying the inverted projection disposed inside a blow-molded container, such as injecting pressurized air into the blow-molded container, may be used to force the inverted projection outside of the container. Thus, in this embodiment, the blow-molded projection is initially inverted inside the container and then, a repositioning operation pushes the inverted projection so that it projects out of the container.

Referring toFIG.30, main turret system530includes a central shaft530a, which supports a container carrier wheel532, a plurality of radially spaced container actuator assemblies534and, further, a plurality of radially spaced container holder actuator assemblies536(FIG.31). Actuator assemblies534deactivate the containers (extend the inverted projection outside the bottom surface of the container), while actuator assemblies536support the container holding devices and containers. Shaft530ais also driven by motor529, which is coupled to a gear or sheave mounted to shaft530aby a belt or chain or the like. In addition, main turret system530includes a fixed plate532afor supporting the containers as they are fed into container carrier wheel532. However, fixed plate532aterminates adjacent the feed-in point of the container holding devices so that the containers can be placed or dropped into the container holding devices under the force of gravity, for example. Container holding devices H are then supported on a rotating plate532b, which rotates and conveys container holding devices H to discharge wheel522b, which thereafter feeds the container holding devices and containers to a conveyor518b, which conveys the container holding devices and containers to a filling system. Rotating plate532bincludes openings or is perforated so that the extendable rods of the actuator assemblies536, which rotate with the rotating plate, may extend through the rotating plate to raise the container holding devices and containers and feed the container holding devices and containers to a fixed plate or platform523bfor feeding to discharge wheel522b.

As best seen inFIG.31, each actuator assembly534,536is positioned to align with a respective container C and container holding device H. Each actuator assembly534includes an extendable rod538for deactivating containers C, as will be described below. Each actuator assembly536also includes an extendable rod540and a pusher member542, which supports a container holding device, while a container C is dropped into the container holding device H and, further supports the container holding device H while the container is deactivated by extendable rod538. To deactivate a container, actuator assembly534is actuated to extend its extendable rod538so that it extends into the container C and applies a downward force onto the invertible projection (512) of the container to thereby move the projection to an extended position to increase the volume of container C for the hot-filling and post-cooling process that follows. After rod538has fully extended the invertible projection of a container, rod538is retracted so that the container holding device and container may be conveyed for further processing.

Again as best seen inFIG.31, while rod538is retracted, extendable rod540of actuator536is further extended to raise the container holding device and container to an elevation for placement on fixed plate or platform523bof discharge wheel522b. Wheel522bfeeds the container holding device and container to an adjacent conveyor518b, which conveys the container holding device and container to filling portion516of the container processing system. Discharge wheel522bis similar driven by motor529, which is coupled to a gear or sheave mounted on its respective shaft.

Referring again toFIGS.30and31, main turret assembly530includes an upper cam assembly550and a lower cam assembly552. Cam assemblies550and552comprise annular cam plates that encircle shaft530aand actuator assemblies534and536. The cam plates provide cam surfaces to actuate the actuator assemblies, as will be more fully described below. Upper cam assembly550includes upper cam plate554and a lower cam plate556, which define there between a cam surface or groove558for guiding the respective extendable rods538of actuator assemblies534. Similarly, lower cam assembly552includes a lower cam plate560and an upper cam plate562which define there between a cam surface or groove564for guiding extendable rods540of actuator assemblies536. Mounted to extendable rod538may be a guide member or cam follower, which engages cam groove or surface558of upper cam assembly550. As noted previously, actuator assemblies534are mounted in a radial arrangement on main turret system530and, further, are rotatably mounted such that actuator assemblies534rotate with shaft530aand container holder wheel532. In addition, actuator assemblies534may rotate in a manner to be synchronized with the in-feed of containers C. As each of the respective actuator assemblies534is rotated about main turret system530with a respective container, the cam follower is guided by groove558of cam assembly550, thereby raising and lowering extendable member538to deactivate the containers, as previously noted, after the containers are loaded into the container holding devices.

If the container holding devices are not used, the containers according to one embodiment of the invention may be supported at the neck of each container during the filling and capping operations to provide maximum control of the container processes. This may be achieved by rails R, which support the neck of the container, and a traditional cleat and chain drive, or any other known like-conveying modes for moving the containers along the rails R of the production line. The extendable projection512may be positioned outside the container C by an actuator as described above.

The process of repositioning the projection outside of the container preferably should occur right before the filling of the hot product into the container. According to one embodiment of the invention, the neck of a container would be sufficiently supported by rails so that the repositioning operation could force or pop the inverted base outside of the container without causing the container to fall off the rail conveyor system. In some instances, it may not be necessary to invert the projection prior to leaving the blow-molding operation and these containers are moved directly to a filling station. The container with an extended projection, still supported by its neck, may be moved by a traditional neck rail drive to the filling and capping operations, as schematically shown inFIG.28.

Referring toFIGS.32and33, one system for singularly activating containers C includes a feed-in scroll assembly584, which feeds and, further, spaces the respective container holding devices and their containers at a spacing appropriate for feeding into a feed-in wheel586. Feed-in wheel586is of similar construction to wheel522band includes a generally star-shaped wheel that feeds-in the container holders and containers to turret assembly588. Turret assembly588is of similar construction to turret assembly530and includes a container holder wheel590for guiding and moving container holding devices H and containers C in a circular path and, further, a plurality of actuator assemblies5104and5106for removing the containers from the container holders and for activating the respective containers, as will be more fully described below. After the respective containers have been activated and the respective containers removed from the container holding devices, the holders are discharged by a discharge wheel592to conveyor594and the containers are discharged by a discharge wheel596to a conveyor598for further processing. Wheels586,592, and596may be driven by a common motor, which is drivingly coupled to gears or sheaves mounted to the respective shafts of wheels586,592, and596.

As previously noted, turret assembly588is of similar construction to turret assembly530and includes container holder wheel590, upper and lower cam assemblies5100and5102, respectively, a plurality of actuator assemblies5104for griping the containers, and a plurality of actuator assemblies5106for activating the containers. In addition, turret system588includes a support plate5107, which supports the container holders and containers as they are moved by turret system588. As best seen inFIG.33, container holder wheel590, actuator assemblies5104, actuator assemblies5106, and plate5107are commonly mounted to shaft588aso that they rotate in unison. Shaft588ais similarly driven by the common motor, which is drivingly coupled to a gear or sheave mounted on shaft588a.

Looking atFIGS.34-36, actuator assemblies5104and5106are similarly controlled by upper and lower cam assemblies5100and5102, to remove the containers C from the container holding devices H and activate the respective containers so that the containers generally assume their normal geometrically stable configuration wherein the containers can be supported from their bottom surfaces and be conveyed on a conventional conveyor. Referring toFIG.34, each actuator assembly5104includes actuator assembly534and a container gripper5108that is mounted to the extendable rod538of actuator assembly534. As would be understood, grippers5108are, therefore, extended or retracted with the extension or retraction of extendable rods538, which is controlled by upper cam assembly5100.

Similar to upper cam assembly550, upper cam assembly5100includes an upper plate5110and a lower plate5112, which define therebetween a cam surface or recess5114, which guides guide members572of actuator assemblies5104to thereby extend and retract extendable rods538and in turn to extend and retract container grippers5108. As the containers are conveyed through turret assembly588, a respective gripper5108is lowered onto a respective container by its respective extendable rod538. Once the gripper is positioned on the respective container, actuator assemblies5106are then actuated to extend their respective extendable rods5116, which extend through plate5107and holders H, to apply a compressive force onto the invertible projections of the containers to move the projections to their recessed or retracted positions to thereby activate the containers. As would be understood, the upward force generated by extendable rod5116is counteracted by the downward force of a gripper5108on container C. After the activation of each container is complete, the container then can be removed from the holder by its respective gripper5108.

Referring toFIGS.34-35, each actuator assembly5106is of similar construction to actuator assemblies534and536and includes a housing5120, which supports extendable rod5116. Similar to the extendable rods of actuator assemblies534and536, extendable rod5116includes mounted thereto a guide5122, which engages the cam surface or recess5124of lower cam assembly5102. In this manner, guide member5122extends and retracts extendable rod5116as it follows cam surface5124through turret assembly588. As noted previously, when extendable rod5116is extended, it passes through the base of container holding device H to extend and contact the lower surface of container C and, further, to apply a force sufficient to compress or move the invertible projection its retracted position so that container C can again resume its geometrically stable configuration for normal handling or processing.

The physics of manipulating the activation panel P or extendable rod5116is a calculated science recognizing 1) Headspace in a container; 2) Product density in a hot-filled container; 3) Thermal differences from the fill temperature through the cooler temperature through the ambient storage temperature and finally the refrigerated temperature; and 4) Water vapor transmission. By recognizing all of these factors, the size and travel of the activation panel P or extendable rod5116is calculated so as to achieve predictable and repeatable results. With the vacuum removed from the hot-filled container, the container can be light-weighted because the need to add weight to resist a vacuum or to build vacuum panels is no longer necessary. Weight reduction of a container can be anticipated to be approximately 10%.

FIGS.16and17show a container according to another embodiment. Many of the features of this embodiment are the same or substantially the same as those of the embodiment ofFIGS.13to15and like references have been used to aid clarity. Only features that differ from the embodiment ofFIGS.13to15will be described.

As shown inFIGS.16and17, the container of this embodiment includes first and second panels1116on two opposing faces of the sidewall thereof, at least one of which is a vacuum panel.

FIGS.18and19show another embodiment of a container that is substantially identical to the container ofFIGS.16and17and again only points of difference will be described.

Notably, in the embodiment ofFIGS.18and19, the first wall or instep1120is inclined at a lesser angle than in the embodiment ofFIGS.16and17. As will be appreciated, other angles of inclination may also be used.

The operation or preferred use of the containers ofFIGS.16and17, andFIGS.18and19, is substantially identical to that described in relation to the embodiment ofFIGS.13to15.

Referring toFIGS.11A-11E, an exemplary method of processing a plastic container according to the present invention is shown. Prior to processing, the container10may be formed (e.g., blow molded) with the pressure panel26in the inwardly-inclined position. According to this embodiment, a force can be applied to the pressure panel26in order to move the pressure panel26into the outwardly-inclined position. For example, as shown inFIGS.11A and11B, a first mechanical pusher50can be introduced through the opening in the container finish14and forced downwardly on the pressure panel26in order to move it to the outwardly-inclined position (shown inFIG.11C). One of ordinary skill in the art will know that other types of mechanical or other forces can alternatively be used to move the pressure panel26into the outwardly-inclined position. Alternatively, the container10can be initially formed with the pressure panel26located in the outwardly-inclined position.

Referring toFIG.11C, the container10can be filled with liquid contents when the pressure panel26is located in the outwardly-inclined position. Particularly, the container10can be “hot-filled” with the liquid contents at an elevated temperature, for example, 185 degrees C. As shown inFIG.11C, the liquid contents can be introduced into the container10via a filling nozzle52inserted through the opening in the container finish10, although one of ordinary skill in the art will know that any number of known filling devices and techniques can be implemented. According to an alternative embodiment, the first mechanical pusher50and the filling nozzle52can be the same instrument.

Referring toFIG.11D, once the container10has been filled to the desired level, the filling nozzle52can be removed, and a cap54can be applied to the container finish14. Any number of capping techniques and devices known in the art can be used to apply the cap54to the container finish14. Next the container10can be cooled, for example, by spraying the container10with cool water, or alternatively, by leaving the container10in ambient conditions for a sufficient amount of time. As the container10and its contents cool, the contents tend to contract. This volumetric change inside the sealed container10can create a vacuum force within the container10.

In order to alleviate all or a portion of the vacuum forces within the container10, the pressure panel26can be moved from the outwardly-inclined position ofFIG.11Dto the inwardly-inclined position ofFIG.11E. For example, following filling, capping, and cooling of the container10, an external force can be applied to the pressure panel26, for example, by a second mechanical pusher56, as shown inFIG.11D. Alternatively, the pressure panel26can be moved by the creation of relative movement of the container10relative to a punch or similar apparatus, in order to force the pressure panel26into the inwardly-inclined position. Alternatively, the pressure panel26can invert to the inwardly-inclined position under the internal vacuum forces within the sealed container10. For example, all or a portion of the pressure panel26(e.g., the initiator portion) can be made flexible enough to cause the pressure panel26to invert under the internal vacuum forces.

The inversion of the pressure panel26from the outwardly-inclined position to the inwardly-inclined position reduces the internal volume of the container10, and thereby increases the pressure inside the sealed container10. This can alleviate any vacuum created within the container10due to the hot-fill process. This can also remedy any deformation of the container10that was caused as a result of the internal vacuum.

As shown inFIGS.11A-E, the entire pressure panel26is above the plane P of the standing surface21(seeFIG.11C) of the container10. As a result of this configuration, the containers10according to the present invention can be stored, transported, and capped/filled, etc., all while standing on the standing surface21. This can eliminate the need for any adapters or other devices to stabilize the container10in the upright position. This can also make the containers10of the present invention more readily adapted for use with conventional, existing container transports, capping and filling stations, and storage facilities.

Referring toFIGS.12A-C, an exemplary method of blow molding a plastic container according to the present invention is shown. Referring toFIG.12A, the method includes enclosing a softened polymer material (such as PET, PEN, PP, blends thereof, and other suitable materials known in the art) within a blow mold. In the exemplary embodiment shown, the polymer material comprises a plastic container preform60. However, according to an alternative embodiment, the polymer material can comprise a tube of extruded polymer material, for example, as used in the known process of “extrusion blow molding.”

The blow mold can comprise two or more side mold portions62,64, and a base mold portion66. The side mold portions62,64can move from an open position (not shown) in which the side mold portions are separated from one another, to a closed position, shown inFIGS.12A-C. In the closed position, shown, the side mold portions62,64define a mold cavity68having an open bottom. The mold cavity68corresponds to the shape of a plastic container to be molded therein. The base mold portion66is located in the open bottom region of the mold cavity68and is movable with respect to the side mold portions62,64in the vertical direction (as viewed inFIGS.12A-C) between the retracted position shown inFIGS.12A and12B, and the extended position shown inFIG.12C. Mechanical, pneumatic, hydraulic, or other means known in the art can be implemented to move the base mold portion66between the retracted and extended positions.

A stretch rod70can be inserted into the neck portion of the softened preform60, and can be used to stretch or elongate the preform60. Air or another medium can be expelled from the stretch rod70or other device to at least partially inflate the preform60into conformity with the mold cavity68in what is commonly known in the art of stretch blow molding as a “pre-blow” step. Preferably, the preform60is inflated into substantially complete conformity with the mold cavity68while the base mold portion66is in the retracted position, as shown inFIG.12B. In order to stretch blow mold the container from the partially inflated volume, it is commonly known in the art of stretch blow molding to increase the pressure during the final blowing step in order to force the plastic material into complete conformity with the mold cavity68. This can eliminate the need for the polymer material to expand deeply into tight corners, narrow spaces, etc., that are associated with the deeply-set pressure panel of the present invention. This can avoid resultant thin or weak spots in the formed container.

While the polymer material is still in a softened state, the base mold portion66can be displaced upwardly into the mold cavity68to form a transverse pressure panel deeply set within the base portion of the plastic container (see, for example, the base20and pressure panel26ofFIGS.1-4). Air can continue to be expelled to blowing pressure into the stretch rod in the blow mold cavity during displacement of the base mold portion66to the extended position, or alternatively, the supply of air can be turned off. Referring toFIGS.1-4, by “deeply set” it is meant that the pressure panel26is located entirely between the standing plane P and the upper portion12of the container when the pressure panel26is in the outwardly-inclined position (FIG.2) and when it is in the inwardly-inclined position (FIG.3). In the exemplary embodiment ofFIGS.12A-C, the base mold portion66moves substantially along the longitudinal axis of the plastic container being formed in the mold cavity68, however, other orientations are possible.

Once the plastic container has been formed in the mold cavity68, the base mold portion66can return to the retracted position, and the side mold portions62,64can separate to release the formed container.

By utilizing the blow molding method of the present invention, it is possible to initially form the general container shape with a generally flat bottom portion, and then deflect the bottom upwardly at orientation temperature. As a result, the container base and deeply-set pressure panel can be of improved material thickness and uniformity. In addition, the base and pressure panel can be multi-axially stretch oriented to provide increased strength without the attendant thinness or weakness at the heel portion of the bottle.

The base of the plastic container according to the present invention is preferably crystallized to some extent. Some degree of crystallinity and/or biaxial orientation can be achieved normally during the blow molding process. However, crystallization can be promoted through heat setting of the container. For example, the walls and base of the mold can be held at an elevated temperature to promote crystallization. When the container is heat set at a temperature of about 180 degrees F., the container sidewalls, base, pressure panel, etc., can be typically crystallized to about 20%. This degree of crystallinity is typical for a blow molding process and does not represent a significant amount of heat setting or increased crystallinity or orientation, as compared with a typically prepared container. However, the properties of the base and pressure panel of the present invention can be advantageously enhanced by heat setting the container, and particularly the base and pressure panel, at ever higher temperatures. Such temperatures can be, for example, greater than 250 degrees F. and can be 325 degrees F. or even higher. When these elevated heat set temperatures are utilized, crystallinity can be increased to greater than 20% or 25% or more. One drawback of increasing crystallinity and biaxial orientation in a plastic container is that this process introduces opacity into the normally clear material. However, unlike bases in prior art containers, which can require a crystallinity of 30% or more, utilizing crystallinities of as low as 22-25% with a base structure according to the present invention can achieve significant structural integrity, while maintaining the substantial clarity of a base that is preferred by manufacturers, packagers and consumers.

U.S. Pat. Nos. 4,465,199; 3,949,033; 4,378,328; and 5,004,109, all of which are incorporated herein by reference, disclose further details relating to blow molding methods utilizing displaceable mold portions. The methods disclosed in these references can also be implemented to form plastic containers according to the present invention. According to an alternative embodiment of the invention, the plastic container can be removed from the blow mold prior to forming the deeply-set pressure panel. Outside of the mold, the pressure-panel and related structure(s) can be formed in the base of the plastic container using a mandrel or similar device. U.S. Pat. No. 4,117,062, the entire content of which is incorporated herein by reference, provides further details on this type of post-mold processing.