CONTAINER PROVIDED WITH A DEFORMABLE BASE WITH A DOUBLE ARCH

Abstract

Container (1) made of plastics material, including a body (5) which extends along a main axis (X), and a base (6) which extends at a lower end of the body (5), the base (6) being provided with protruding feet (7) that are provided with crowns (11) which extend in a common setting-down plane (12), pairs of the feet (7) being separated by recessed grooves (15) which extend radially from a central region (8) of the base (6), each foot (7) having two flanks (17) that each laterally border a groove (15), characterized in that the flanks (17) of two adjacent feet (7) which border one and the same groove (15) form between one another, at the level of the setting-down plane (12) and in a plane transverse to the radial direction of extension of the groove (15), an obtuse angle (A) at the crown.

Description

The invention relates to the field of containers, such as bottles or jars, made of plastic material, obtained by blow molding or stretch-blow molding from a parison (whether it is a preform or an intermediate container having undergone a pre-blow molding operation of a preform), and comprising a body, which extends at an upper end by a neck through which the filling and the emptying of the container are performed, and, at a lower end, by a bottom that closes the container.

The operations of blow molding and of stretch-blow molding, performed in a mold having the impression of the container, impart to the material a certain rigidity, resulting from the double orientation that it undergoes, both axially (parallel to the general axis of the mold—or of the container) and radially (perpendicular to the axis).

This rigidity is not, however, always sufficient to enable the container to withstand the stresses—both external and internal—to which it is subjected during its life cycle, as soon as it is filled.

The internal stresses comprise, primarily, the temperature or the pressure of the contents.

It is known to initiate thermosetting (i.e., thermal crystallization) to increase the resistance of the container to deformations resulting from thermal stresses experienced during a hot filling (on the order of 90° C. for certain beverages such as pasteurized fruit juices or even tea). Thermosetting, however, because of its cost and its high cycle time, cannot be generalized to more ordinary applications such as plain water.

It is also known to resort to particular bottom shapes, referred to as petaloids, comprising projecting feet, whose apexes define a standing plane for the container, separated by deep valleys, which offer an increased resistance to the high internal pressure caused by certain contents (particularly carbonated beverages). The petaloid-shaped bottoms, because of the complexity of their shapes and the depth of their valleys (this depth represents generally at least 50% of the overall diameter of the bottom), however, require a relatively large amount of material, which makes them unsuited to the ordinary applications such as plain water, for which instead it is sought to minimize the amount of material used.

The external stresses comprise, primarily, the axial compression forces to which the palletized containers are subjected, each container supporting the weight of the column of containers above it. If the thermoset containers and/or containers having a petaloid-shaped bottom generally support this type of stress well, thanks to their increased mechanical performance, the containers allocated to the ordinary applications such as plain water bear them less readily, and crushing events are sometimes unfortunate during the palletizing of this type of container.

It is known to make the bottoms of these types of containers rigid by means of radial ribs that extend from a central area of the bottom and spread from the bottom through the standing plane formed by it, see, for example, French patent FR 2 932 458 (SIDEL) or its U.S. equivalent US 2009/308835. The performance offered by this bottom is good, but it is, however, desirable to improve it to minimize the crushing risks and thus to promote the stability of the pallets. It should be noted that the widening alone of the grooves, which could make the bottom rigid, is not necessarily a good solution, because it results in a greater difficulty in blow molding the bottom (in other words, it diminishes the blowability of the container—i.e., its ability to be correctly blow molded).

A first objective is to propose a container whose bottom exhibits, given an equal amount of material, improved mechanical performance, or performance that is identical with a reduced amount of material.

A second objective is to propose a container whose bottom exhibits an improved blowability.

A third objective is to propose a container whose bottom imparts to it a better mechanical resistance to crushing under axial compression.

For this purpose, a container made of plastic material is proposed, said container comprising a body that extends along a main axis, and a bottom that extends at a lower end of the body, the bottom being provided with projecting feet having apexes that extend into a common standing plane, the feet being separated into pairs by recessed grooves that extend radially from a central area of the bottom, each foot exhibiting two sides that each laterally border a groove, the sides of two adjacent feet bordering the same groove forming between them, in the area of the standing plane and in a plane crosswise to the radial direction of extension of the groove, an angle A at the obtuse apex.

Under axial compression, the angle A has a tendency to be opened, which makes possible a slight axial compression of the bottom, having as a consequence an increase in the pressure of the contents of the container, and therefore a greater rigidity of it.

Various additional characteristics can be envisaged, alone or in combination:

• • angle A at the apex between the sides is between 90° and 150°.
  • angle A at the apex between the sides is about 120°.
  • each side exhibits a concavity turned toward the exterior of the container.
  • each groove exhibits a depth H, measured on a level with the standing plane between it and the bottom of the groove, such that:

$\frac{H}{D}\le \frac{1}{10}$

where D is an overall transverse dimension of the bottom, measured at its junction with the body.

• • the depth of the groove is such that

$\frac{H}{D}\cong \frac{1}{20}$

• • the sides bordering the same groove define, in a plane parallel to the standing plane, a maximum angular opening B, measured on the axis of the body, greater than the angular opening C defined by the apex of each foot, measured in the standing plane on the axis of the body.
  • the maximum angular opening B of the sides is such that

$\frac{B}{C}\cong 2$

• • the bottom of the container exhibits two concentric regions, namely a central region and a peripheral region, separated by a median axial step that extends annularly in a continuous manner, such that the central region is axially offset in relation to the peripheral region toward the interior of the container;
  • the grooves extend beyond the standing plane onto an outer lateral wall of the bottom.

Other objects and advantages of the invention will come to light from the description of an embodiment, given below with reference to the accompanying drawings in which:

FIG. 1 is a realistic bottom view, in perspective, of a container made of plastic material;

FIG. 2 is a realistic perspective view, in larger scale, showing the bottom of the container of FIG. 1; for a better understanding of the shapes of the bottom, lines marking the curvature of its surfaces have been left;

FIG. 3 is a realistic bottom plan view of the container;

FIG. 4 is a partial cutaway view of the container of FIG. 3, along the cutting plane IV-IV;

FIG. 5 is a side view showing the silhouette of the container, in solid lines in the absence of stress, and in broken lines under an axial compression stress, with, in an inset, a detail centered on a portion of the bottom that is deformed by the axial compression.

Shown in FIG. 1 is a container 1, in this particular case a bottle, made by stretch-blow molding from a preform of thermoplastic material, for example of PET (polyethylene terephthalate). This container 1 is intended to receive still contents (particularly plain water).

This container 1 comprises, at an upper end, a threaded neck 2, provided with a rim 3. In the extension of the neck 2, the container 1 comprises in its upper part a shoulder 4 that flares out in the direction opposite the neck 2, this shoulder 4 being extended by a lateral wall or body 5, with a generally rotationally cylindrical shape around a main axis X of the container 1.

The container 1 further comprises a bottom 6 that extends opposite the neck 2, from a lower end of the body 5. Marked D is an overall crosswise dimension of the bottom 6, measured at its junction with the body 5. When the shape of the container 1 is circular, as in the example illustrated, the overall crosswise dimension D of the bottom 6 corresponds to its overall diameter.

The bottom 6 is provided with feet 7 that are formed by protrusions projecting toward the exterior of the container 1 and that extend from a central area 8 of the bottom 6; said central area 8 extends recessed toward the interior of the container 1 and includes a button 9 obtained from the injection molding of the preform from which the container 1 comes, and where the material has remained approximately amorphous.

Each foot 7 has a lower face 10 that is arched with concavity turned toward the exterior of the container 1. As illustrated in FIG. 4, this lower face 10 extends radially gently sloping (less than or equal to about 10° in relation to a transverse plane perpendicular to the axis X of the container) from the central area 8, to an apical face 11, hereafter more simply called apex, which forms the most protruding part of the foot 7. The apexes 11, which form the most protruding part of the feet 7, extend in a common transverse plane 12, referred to as standing plane, by which the container 1 can rest on a flat surface such as a table.

As can be seen in FIGS. 2 and 3, in which two of the apexes 11 have been filled in with a honeycomb pattern to clearly indicate their footprint, the apexes 11 exhibit, in the standing plane 12, a fan-shaped contour, and connect with an outer lateral wall 13 of the bottom by a large-radius fillet 14. Marked C is the median angular opening defined by the apex 11 of each foot 7, measured in the standing plane 12 and centered on the axis X (FIG. 3).

As illustrated in FIGS. 2 and 3, the bottom 6 is provided with a series of recessed grooves 15 that extend radially from the central area 8 and separate the feet 7 into pairs. As is seen in FIGS. 2 and 4, the grooves 15, which form in bottom view (FIG. 3) a starred pattern, extend radially beyond the standing plane 12, and each exhibit an outer end portion 16 that rises on the outer lateral wall 13 of the bottom 6. For more clarity, in FIGS. 2 and 3, a groove 15 has been filled in with a broken-line pattern. In the example illustrated, the bottom 6 comprises seven grooves 15 (and seven feet 7), but this number could be lower (at least three) or higher (for example up to eleven grooves 15 and feet 7).

Because of the slight height of the feet 7, the bottom 6 should not be considered as a petaloid-shaped bottom. More specifically, as illustrated in FIG. 4, each groove 15 exhibits a depth H, measured on a level with the standing plane 12 between the latter and the bottom of the groove 15, such that:

$\frac{H}{D}\le \frac{1}{10}$

More specifically, in the example illustrated, H and D have a ratio such that:

$\frac{H}{D}\cong \frac{1}{20}$

By comparison, in a petaloid-shaped bottom, the depth of the valleys perpendicular to the standing plane has a ratio on the order of less than ⅕ with the overall crosswise dimension of the bottom.

As is seen in FIG. 5, and more particularly in the inset associated with it, each groove 15 exhibits, in vertical cross-section (in a plane parallel to the axis X and perpendicular to the radius according to which the groove extends), an arch-shaped profile (in other words, a flared U), having concavity turned toward the exterior of the container 1.

As illustrated in FIGS. 2 and 3, each foot 7 has two sides 17 that each laterally border a groove 15, such that a groove 15 is laterally bordered by two sides 17 belonging respectively to the two adjacent feet 7 framing this groove 15. For better visibility, in FIGS. 2 and 3, two sides 17 on both sides of the same groove 15 (itself filled in with a pattern of broken lines) have been shaded by a dot pattern.

As illustrated in FIG. 5, and more visibly in its inset, the sides 17 bordering the same groove 15 form between them, in the area of the standing plane 12 and in a plane transverse to the radial direction of extension of the groove 15 and parallel to the axis X, an angle A that is obtuse at the apex.

The angle A at the apex between the sides 17 bordering the same groove 15 is preferably between 90° and 150°. According to a preferred embodiment, illustrated in the figures, the angle A is about 120°.

Each side 17 is preferably concave, having concavity turned toward the exterior of the container 1. As is clearly seen in the inset of FIG. 5, the radius of curvature of the side 17 is much greater than that of the groove 15. According to a preferred embodiment, the ratio between the radius of curvature of the groove 15 and that of the side 17 is less than 1/10, and particularly on the order of 1/15. The sides 17 thus form, on both sides of the groove, an open secondary arch, whose function will be brought to light below.

Each side 17 is connected, on the one hand, to the apex 11 of the foot 7, and, on the other hand, to the groove 15, by small-radius fillets.

Furthermore, as is clearly seen in FIGS. 2 and 3, each side 17 exhibits, seen from below, a contour in the shape of an arrow feather, which is flaring out from a point located in the vicinity of the central area 8 to a widened central portion on a level with the standing plane 12, then narrowing from the central portion to a point located on a level with the outer lateral wall 13 of the bottom 6.

Together, two sides 17 bordering the same groove 15 define, in a plane parallel to the standing plane 12, a maximum angular opening B (centered on the axis X and measured in the standing plane 12 between the outer edges of the central portions of the sides 17). The angular opening B is, preferably, greater than the angular opening C defined by each apex 11. According to a preferred embodiment illustrated in the figures, the angular opening B is in a ratio with the angular opening C defined by each apex, such that:

$\frac{B}{C}\cong 2$

As is seen in the figures, and more clearly in FIGS. 2 and 3, the bottom 6 of the container 1 can also be subdivided into two concentric regions, namely an annular central region 18 surrounding the central area 8 of the bottom 6, and an annular peripheral region 19 surrounding the central region 18, separated by an annular step 20 that extends axially over a predetermined height. This step 20 is approximately median in relation to the bottom 6, i.e., the central region 18 and the peripheral region 19 exhibit approximately the same radial extension.

The step 20 extends continuously, i.e., it is interrupted neither on a level with the grooves 15 but extends to the bottom of them, nor on a level with the feet 7 but extends straddling them, even on their lower faces 10 and on their sides 17.

In the embodiment shown, where the container 1 has an approximately rotationally cylindrical shape around its axis X, the step 20 forms a ring having a circular contour.

By the presence of the axial step 20, the central region 18 of the bottom 6 is found slightly offset in height in relation to the peripheral region 19 toward the interior of the container 1.

The step 20 has the function of maintaining the stability of the container 1 by making the bottom 6 rigid in its median region.

Thus structured, the bottom 6 has a good blowability (thanks in particular to the large angular opening A of the sides 17), while imparting to the container 1 a better mechanical performance than an ordinary container having an equivalent amount of material.

Actually, under the effect of an axial compression (indicated by the arrow in FIG. 5) exerted on the neck 2 of the container 1 standing flat on its standing plane 12, the sides 17 are deformed by opening up (i.e., opening the angle A) and by flattening in the direction of the standing plane 12, as illustrated in broken lines in the inset of FIG. 5.

The result is a slight deformation by axial compression of the bottom 6, which causes a translational movement of the whole body 5 (without significant deformation of it, because of its annulated structure with small radii of curvatures) in the direction of the standing plane 12, as illustrated in broken lines in FIG. 5.

This general deformation has the effect of putting the contents of the container 1 under pressure, and as a consequence increasing the rigidity of the container 1, benefiting its resistance to the axial compression. The bottom 6, and more generally the container 1, thus act as a compression spring whose stiffness increases with the axially-applied compression force.

The step 20 makes it possible to limit the axial deformation of the bottom 6 by forming a piston that forms an end-of-travel stop that, under the effect of a strong axial compression stress, joins the standing plane 12 and thus increases the contact surface of the container with its support.

The result of these advantages is that it is possible to palletize the container 1 without significant risk of deformation, which makes it possible to increase productivity and to facilitate the handling of the pallets.

Claims

1. Container (1) made of plastic material comprising a body (5), which extends along a main axis (X), and a bottom (6) that extends at a lower end of the body (5), the bottom (6) being provided with projecting feet (7) having apexes (11) that extend into a common standing plane (12), the feet (7) being separated into pairs by recessed grooves (15) that extend radially from a central area (8) of the bottom (6), each foot (7) exhibiting two sides (17) that each laterally border a groove (15), wherein the sides (17) of two adjacent feet (7) that border the same groove (15) form between them, in the area of the standing plane (12) and in a plane crosswise to the radial direction of extension of the groove (15), an angle (A) that is obtuse at the apex, each groove (15) having a depth H, measured on a level with the standing plane (12) between it and the bottom of the groove (15), such that: H D ≤ 1 10 where D is an overall transverse dimension of the bottom (6), measured at its junction with the body (5).

2. Container (1) according to claim 1, wherein the angle A at the apex between the sides (17) is between 90° and 150°.

3. Container (1) according to claim 2, wherein the angle A at the apex between the sides (17) is about 120°.

4. Container (1) according to claim 1, wherein each side (17) exhibits a concavity turned toward the exterior of the container (1).

5. Container (1) according to claim 1, wherein the depth of the groove (15) is such that H D ≅ 1 20

6. Container (1) according to claim 1, wherein the sides (17) bordering the same groove (15) define, in a plane parallel to the standing plane (12), a maximum angular opening B, measured on the axis (X) of the body (5), greater than the angular opening C defined by the apex (11) of each foot (7), measured in the standing plane (12) on the axis (X) of the body (5).

7. Container (1) according to claim 6, wherein the maximum angular opening B of the sides (17) is such that B C ≅ 2

8. Container (1) according to claim 1, wherein the bottom (6) of the container exhibits two concentric regions, namely a central region (18) and a peripheral region (19), separated by a median axial step (20) that extends annularly in a continuous manner, such that the central region (18) is axially offset in relation to the peripheral region (19) toward the interior of the container (1).

9. Container (1) according to claim 1, wherein the grooves (15) extend beyond the standing plane (12) onto an outer lateral wall (13) of the bottom.

10. Container (1) according to claim 2, wherein each side (17) exhibits a concavity turned toward the exterior of the container (1).

11. Container (1) according to claim 3, wherein each side (17) exhibits a concavity turned toward the exterior of the container (1).

12. Container (1) according to claim 2, wherein the depth of the groove (15) is such that H D ≅ 1 20

13. Container (1) according to claim 2, wherein the sides (17) bordering the same groove (15) define, in a plane parallel to the standing plane (12), a maximum angular opening B, measured on the axis (X) of the body (5), greater than the angular opening C defined by the apex (11) of each foot (7), measured in the standing plane (12) on the axis (X) of the body (5).

14. Container (1) according to claim 13, wherein the maximum angular opening B of the sides (17) is such that B C ≅ 2

15. Container (1) according to claim 2, wherein the bottom (6) of the container exhibits two concentric regions, namely a central region (18) and a peripheral region (19), separated by a median axial step (20) that extends annularly in a continuous manner, such that the central region (18) is axially offset in relation to the peripheral region (19) toward the interior of the container (1).

16. Container (1) according to claim 2, wherein the grooves (15) extend beyond the standing plane (12) onto an outer lateral wall (13) of the bottom.

17. Container (1) according to claim 4, wherein the depth of the groove (15) is such that H D ≅ 1 20

18. Container (1) according to claim 5, wherein the sides (17) bordering the same groove (15) define, in a plane parallel to the standing plane (12), a maximum angular opening B, measured on the axis (X) of the body (5), greater than the angular opening C defined by the apex (11) of each foot (7), measured in the standing plane (12) on the axis (X) of the body (5).

19. Container (1) according to claim 18, wherein the maximum angular opening B of the sides (17) is such that B C ≅ 2

20. Container (1) according to claim 4, wherein the bottom (6) of the container exhibits two concentric regions, namely a central region (18) and a peripheral region (19), separated by a median axial step (20) that extends annularly in a continuous manner, such that the central region (18) is axially offset in relation to the peripheral region (19) toward the interior of the container (1).