BLOW MOULDED CONTAINER WITH SELF- SUPPORTING BASE

Abstract: A blow molded plastic container (10) used in packaging of carbonated beverages having a hollow tubular body (14) terminating at its lower end in an integral base (16). The base includes a frusto-conical shaped wall (20) projecting into the hollow interior of the tubular body. The frusto-conical shaped wall terminates at a substantially planar wall (22). A plurality of ribs (24) are formed radially about the base between the frusto-conical wall and the tubular body to thus form a plurality of symmetrical feet (26) which support the container in an upright stable position.

Description: Background and Summary of the Invention The present invention relates to hollow plastic containers and, more particularly, to blow molded plastic containers with self-supporting bases. The base has sufficient strength to withstand internal pressures like those encountered in the packaging of carbonated beverages and the like, and in addition has distinct supporting feet which enable the container to stand without rocking. With the movement to plastic bottles for packaging carbonated beverages, the art has moved to plastic containers with self-supporting bases. Such a container must be able to withstand the internal pressure necessary to maintain the desired carbonation. Such a pressure is on the order of 5.2 bar (75 p.s.i.). Several types of containers exist in the art that include integral bases with molded bottom configurations. However, there still exists a need for a container of this type which requires a reasonable amount of material in the base, withstands internal pressures and will stand upright with out rocking. The present invention provides a container having a tubular body and an integral base, the junction of the two having a smooth, continuous exterior surface. The present invention eliminates any sharp bends deviations, or the like at the junction of the body and base. The present invention provides the container with good distribution of plastic throughout the container surface. Also, the present invention eliminates stress cracks and enables the use of a minimum amount of plastic material to mold the container. Also, when the container is full of a carbonated beverage or the like, the container will withstand the pressure necessary to maintain carbonation and will exhibit a very sturdy and rigid outer body. Once the beverage has been removed from the container, the container is very flexible and enables the container to be discarded and the plastic recycled. GB-A-2 044 211 discloses a container in accordance with the prior art portion of claim 1. In order to improve the resistance to internal pressure causing deformation, the present invention, as defined in claim 1, provides a truly frustoconical inner wall extending well above radial foot-defining grooves with the grooves themselves being generally of inverted V-shaped as upwardly projecting ribs when viewed in cross-section. The strengthening effect resistive of deformation is emphasised by the substantial extent, twice the depth of the ribs, to which the frustoconical wall extends above the ribs. In a preferred embodiment, further strengthening ribs are provided, preferably radially aligned with the first ribs, with the direction of projection of the further ribs being opposite to that of the first ribs so as to provide a cooperating action to resist distending of the body under higher internal pressure. From the subsequent description and claims taken in conjunction with the accompanying drawings, other objects and advantages of the present invention will become apparent to those skilled in the art. Brief Description of the Drawings Figure 1 is a side elevation view of a container in accordance with the present invention; Figure 2 is a bottom plan of the container in Figure 1; Figure 3 is an enlarged sectional view of a portion of the container as seen from substantially the line 3-3 in Figure 2; Figure 4 is an enlarged sectional view of a portion of the container as seen from substantially the line 4-4 in Figure 2; Figure 5 is a fragmentary side elevational view of a modified form of container of the present invention; Figure 6 is a bottom plan view of the container shown in Figure 5; Figure 7 is an enlarged sectional view of a portion of the container as seen from substantially the line 7-7 Figure 5. Detailed Description of the Preferred Embodiment With reference to the drawing, the blow molded plastic container of this invention is illustrated and designated generally at 10 in Fig. 1. The container 10 includes an integral tapered top portion 13 which includes a flange 12 and a threaded neck 18. The container also has a hollow tubular body 14 and an integral base 16. The tubular thin wall body 14 is manufactured, as is the entire container, from a blow molded plastic material such as polyethylene terephthalate (PET). The base 16 includes a frusto-conical upwardly narrowing inner wall 20 and a substantially circular and planar wall 22 projecting into the interior of the hollow tubular body 14. Outwardly of the inner wall 20, the container 10 has a downwardly concave annular chamber 23 bounded on the radially inner side by the wall 20 and on the radially outer side by the outer wall 25 (Fig. 3) of the base 16. A plurality of internal ribs 24 are formed in these base 16 between the walls 20 and 25, the ribs 24 being symmetrical relative to the longitudinal axis 11 of the container 10. A plurality of feet 26 are formed between adjacent ribs 24 to enable the container 10 to stand upright. The ribs 24 are formed by elongated narrow indentations formed on the surface of the base 16 as seen in Figures 2-4 so that the ribs 24 extend radially of the base 16. The positioning of the ribs 24 such that the ribs 24 are on radii about 30° to 60° apart and preferably about 45° apart, about the circular base. The ribs 24 are of generally inverted V-shape in cross-section when viewed transverse to the longitudinal axes of the ribs 24, as seen in Figure 4. The intersection of the V, forming the ribs 24, along the ribs longitudinal axis 27 is somewhat planar, as seen in Figures 3 and 4. The ribs 24 are all of substantially the same vertical height and are of small height so that they are all positioned well below the planar top wall 22. Thus, a ratio of the distance "x" from the rounded bottom 17 of the base 16 to the planar top wall 22 to the distance "y" from the bottom 17 to the top of the ribs 24 is about 3:1. The positioning of the ribs 24 below the planar top 22 enhances the strength of the container base 16. Also, the positioning of the ribs 24 enables the container 10 to stand level and to be resistive to incidental tipping. The feed 26 also include angular side walls 31 that form the legs of the rounded, flattened inverted V-shape indentation of the ribs 24. A modified form of the container of this invention is shown in Figs. 5-7 and indicated generally at 10a. Like elements will be identified with the same references numerals. The base 16 in the container 10a includes all of the structure in the base 16 in the container 10 and in addition includes a second set of reinforcing or stiffening ribs 28 (Fig. 6) as shown in Fig. 5. The ribs 28 are formed in the frusto-conical wall 20 and the top wall 22 and are located above the ribs 24. The ribs 28 are of an internal design having an overall U-shaped cross-section when viewed transverse to the rib's longitudinal axis 32, as shown in Figure 7. Also, the ribs 28 may protrude from the base 16 and have a bulging inverted U-shaped configuration in cross-section when viewed transverse to the longitudinal axis 32 of the ribs 28. The ribs 28 are aligned with the ribs 24 in a direction radially of the base 16. Thus, the axes 27 and 32 of the ribs 24 and 28 are substantially coincident. The ribs 28 add additional support and strength to the base 16 and prevent the generally concave bottom of the container 10a from inverting when filled with a carbonated beverage under a pressure of about 5.2 bar (75 p.s.i.).

Claims: A blow moulded plastic container (10) comprising: a hollow tubular body (14) having a side wall of annular shape, and terminating at its lower end in a integral aligned base (16); said base having a reentrant inner wall (20) projecting upwardly into said hollow tubular body, a top wall (22) at the upper end of said inner wall, and an annular downwardly concave chamber (23) extending about said inner wall (20), said chamber having an outer wall which merges at its upper end with said tubular side wall (14) and at its lower end with said inner wall (20) to form a bottom surface (17), a plurality of radially extending hollow ribs (24) formed in said bottom surface so as to extend upward therefrom a small distance so as to intersect said inner and outer walls at a position below said top wall; said bottom surface between said ribs forming a plurality of container support feet (17) each of which is of substantial width in a direction circumferentially of said base relative to said ribs (24) to provide firm support for said container (10), said ribs being symmetrically arranged relative to the longitudinal axis of said container to provide for a symmetrically uniform support of said container on said feet without tipping of the container, characterised in that said inner wall (20) is of truncated frustoconical shape, in that the tops of the hollow ribs (24) where they intersect said inner and outer walls are well below the top wall (22) extending to a height of substantially one-third of the height of the top wall (22) from the bottom surface (17) and in that the ribs (24), in cross-section when viewed transverse to their longitudinal axes (27), have an inverted V-shape with the feet (17) formed between adjacent ribs (24) having rounded sides and bottoms providing the container with a smooth continuous outer surface. A container according to claim 1, further comprising a plurality of second hollow ribs (32) formed in said base frustoconical shaped inner wall (20) and in said top wall (22) for further stiffening said base (16) against deformation by internal pressure in said container. A container according to claim 2, wherein said second ribs (32) extend radially with respect to the longitudinal axis (1) of said container (10) and are aligned with the first ribs (24).

Inventors: HOWARD, CARL ROBERT, JR.
Applicants: HOOVER UNIVERSAL, INC.
Application year: 1989
Main classification: B65D1
IPC codes: B65D1