EP2989015B1 - Container provided with a deformable base with a double arch - Google Patents

Description

The invention relates to the field of containers, such as bottles or pots, made of plastic material, obtained by blow molding or stretch blow molding from a blank (whether it be a preform or an intermediate container having has undergone pre-blowing operation of a preform), and comprising a body, which is extended at an upper end by a neck through which the filling and emptying of the container are made, and, at a lower end, by a closed bottom the recipient.

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

However, this rigidity is not always sufficient to allow the container to withstand the external and internal stresses to which it is subjected during its life cycle, as soon as it is filled.

Internal stresses include, for the most part, the temperature or pressure of the contents.

It is known to thermofixation (that is to say a thermal crystallization) to increase the resistance of the container to the deformations resulting from thermal stresses undergone during hot filling (of the order of 90 ° C for some drinks such as pasteurized fruit juice or tea). But heat setting, because of its cost and its high cycle time, can not be generalized to more ordinary applications such as still water.

It is also known to use special bottom forms, called petaloïdes, including projecting feet, whose tops define a laying plane for the container, separated by deep valleys, which offer increased resistance to the high internal pressure induced by certain contents (notably carbonated drinks). The petaloid bottoms, because of the complexity of their shapes and the depth of their valleys (this depth generally represents at least 50% of the overall diameter from the bottom), however, require a relatively large amount of material, which makes them unsuitable for ordinary applications such as still water, for which on the contrary it is sought to minimize the amount of material used.

The external stresses essentially comprise the axial compressive forces to which the palletized containers are subjected, each container carrying the weight of the column of containers above it. While thermofixed and / or petaloid-based containers generally withstand this type of constraint, thanks to their increased mechanical performance, the containers devolved to ordinary applications such as flat water are more difficult to withstand, and crushing phenomena are sometimes to deplore when palletizing this type of container.

It is known to stiffen the bottom of these types of containers by means of radial ribs which extend from a central zone of the bottom and overflow from the bottom through the laying plane formed by it, cf. eg. the French patent FR 2 932 458 (SIDEL) or its American counterpart US 2009/308835 . The performance offered by this background is good, but it is desirable to improve them to minimize the risk of crushing and thus promote the stability of the pallets. It should be noted that the only digging of the grooves, which could stiffen the bottom, is not necessarily a good solution, because it causes a greater difficulty in blowing the bottom (in other words, it reduces the blowing of the container - that is to say, its ability to be properly blown). It is known from the document JPH0939934A a plastic container comprising a body, which extends along a main axis, and a bottom which extends to a lower end of the body, the bottom being provided with feet which are formed by outwardly protruding protuberances of the container and extend from a central zone of the bottom including a pellet resulting from injection molding of the preform from which the container is derived, and where the material has remained substantially amorphous, the feet being provided with vertices which extend in a common laying plan, the bottom of the feet being separated in pairs by hollow grooves which extend radially from a central zone of the bottom, each foot having two flanks which each border laterally a groove and the flanks of two adjacent feet which border the same groove form between them, at the level of the laying plane and in a plane transverse to the radial direction of extension of the groove, an obtuse angle at the top. A first objective is to provide a container whose bottom has, in equal amount of material, improved mechanical performance, or identical performance with reduced material amount.

A second objective is to provide a container whose bottom has an improved puffability.

A third objective is to provide a container whose bottom gives it a better mechanical resistance to compression under axial compression.

For this purpose, there is provided a container according to claim 1 attached. Under axial compression, the angle A tends to open, which allows a slight axial compression of the bottom, resulting in an increase in the pressure of the contents of the container, and therefore a greater rigidity thereof.

• l'angle A au sommet entre les flancs est compris entre 90° et 150°.
• l'angle A au sommet entre les flancs est d'environ 120°.
• chaque flanc présente une concavité tournée vers l'extérieur du récipient.
• la profondeur de la gorge est telle que $$\frac{H}{D}\cong \frac{1}{20}$$
  
• les flancs bordant une même gorge définissent, dans un plan parallèle au plan de pose, une ouverture angulaire B maximale, mesurée sur l'axe du corps, supérieure à l'ouverture angulaire C définie par le sommet de chaque pied, mesurée dans le plan de pose sur l'axe du corps.
• l'ouverture angulaire B maximale des flancs est telle que $$\frac{B}{C}\cong 2$$
  
• le fond du récipient présente deux régions concentriques, à savoir une région centrale et une région périphérique, séparées par un décrochement axial médian qui s'étend annulairement de manière continue, de sorte que la région centrale se trouve décalée axialement par rapport à la région périphérique vers l'intérieur du récipient ;
• les gorges se prolongent au-delà du plan de pose sur une paroi latérale externe du fond.

Various additional features may be provided, alone or in combination:

• the angle A at the top between the flanks is between 90 ° and 150 °.
• the angle A at the top between the flanks is about 120 °.
• each side has a concavity turned towards the outside of the container.
• the depth of the throat is such that $$\frac{H}{D}\cong \frac{1}{20}$$
  
• the flanks bordering the same groove define, in a plane parallel to the laying plane, a maximum angular aperture B, measured on the axis of the body, greater than the angular aperture C defined by the apex of each foot, measured in the plane laying on the axis of the body.
• the maximum angular aperture B of the flanks is such that $$\frac{B}{\mathrm{VS}}\cong 2$$
  
• the bottom of the container has two concentric regions, namely a central region and a peripheral region, separated by a median axial recess which extends annularly so continuous, so that the central region is axially offset from the peripheral region towards the interior of the container;
• the grooves extend beyond the laying plane on an outer side wall of the bottom.

• la figure 1 est une vue réaliste de dessous, en perspective, d'un récipient en matière plastique ;
• la figure 2 est une vue en perspective réaliste, à échelle agrandie, montrant le fond du récipient de la figure 1 ; pour une meilleure compréhension des formes du fond, on a laissé des traits marquant la courbure des surfaces de celui-ci ;
• la figure 3 est une vue réaliste en plan de dessous du récipient ;
• la figure 4 est une vue partielle en coupe du récipient de la figure 3, selon le plan de coupe IV-IV ;
• la figure 5 est une vue de côté montrant la silhouette du récipient, en trait plein, en l'absence de contrainte, et en pointillés sous une contrainte de compression axiale, avec, en médaillon, un détail centré sur une partie du fond déformée par la compression axiale.

Other objects and advantages of the invention will become apparent in the light of the description of an embodiment, given hereinafter with reference to the accompanying drawings, in which:

• the figure 1 is a realistic view from below, in perspective, of a plastic container;
• the figure 2 is a realistic perspective view, on an enlarged scale, showing the bottom of the container of the figure 1 ; for a better understanding of the shapes of the bottom, we have left marks marking the curvature of the surfaces of this one;
• the figure 3 is a realistic plan view from below of the container;
• the figure 4 is a partial sectional view of the container of the figure 3 according to section plane IV-IV;
• the figure 5 is a side view showing the silhouette of the container, solid line, in the absence of stress, and dotted under axial compressive stress, with, inset, a detail centered on a part of the bottom deformed by the axial compression .

On the figure 1 there is shown a container 1, in this case a bottle, made by stretch blow molding from a thermoplastic preform, for example PET (polyethylene terephthalate). This container 1 is intended to accommodate a flat content (including flat 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 flaring in the direction opposite to the neck 2, this shoulder 4 being extended by a side wall or body 5, of generally cylindrical shape of revolution about a main axis X of the container 1.
The container 1 further comprises a bottom 6 which extends opposite the neck 2, from a lower end of the body 5. A D denotes an overall transverse dimension of the bottom 6, measured at its junction with the 5. When the outline of the container 1 is circular, as in the example illustrated, the overall transverse dimension D of the bottom 6 corresponds to its overall diameter.

The bottom 6 is provided with feet 7 formed by protuberances protruding outwardly of the container 1, and which extend from a central zone 8 of the bottom 6, which central zone 8 extends recessed towards the inside of the 1 and includes a pellet 9 after injection molding of the preform from which the container 1, and where the material remained substantially amorphous.

Each foot 7 has a concavely lower, domed face 10 facing outwardly of the container 1. As illustrated in FIG. figure 4 This bottom face 10 extends radially sloping (less than or equal to 10 ° with respect to a transverse plane perpendicular to the axis X of the container) from the central area 8 up to a face 11 uppermost, it -after referred to simply more vertex, which forms the most prominent part of the foot 7. The peaks 11, which form the most protruding part of the feet 7, extend in a common transverse plane 12 , said laying plane, by which the container 1 can rest on a flat surface such as a table.

As is visible on the figures 2 and 3 , on which two peaks 11 have been filled by a honeycomb pattern, in order to properly materialize their grip, the vertices 11 have, in the plane 12 of laying a fan-shaped outline, and are connected to a lateral wall 13 external of the bottom by a leave 14 with large radius. C is the average angular aperture defined by the apex 11 of each foot 7, measured in the laying plane 12 and centered on the axis X ( figure 3 ).

As illustrated on figures 2 and 3 the bottom 6 is provided with a series of recessed grooves 15 which extend radially from the central zone 8 and separate the legs 7 in pairs. As we see on the figures 2 and 4 , the grooves 15, which form in a view from below ( figure 3 ) a star pattern, extend radially beyond the laying plane 12 , and each have an outer end portion 16 which rises on the outer side wall 13 of the bottom 6. For clarity, it has, on the figures 2 and 3 filled a groove 15 with a dotted pattern. In the illustrated example, the bottom 6 comprises seven grooves 15 (and seven feet 7 ), but this number could be less (at least three) or greater (for example up to eleven grooves 15 and 7 feet).

Due to the low height of the feet 7, the bottom 6 can not be considered as a petaloid bottom. More specifically, as illustrated on the figure 4 each groove 15 has a depth H, measured in line with the laying plane 12 between it and the bottom of the groove 15, such that: $$\frac{H}{D}\le \frac{1}{10}$$

More precisely, in the illustrated example, H and D are in a report such that: $$\frac{H}{D}\cong \frac{1}{20}$$

By comparison, in a petaloid bottom, the depth of the valleys in line with the laying plane is in a ratio of less than 1/5 with the overall transverse dimension of the bottom.

As we see on the figure 5 , and more particularly in the medallion associated with it, each groove 15 has, in vertical section (in a plane parallel to the axis X and perpendicular to the radius along which the groove extends), a profile in the form of arch (in other words flared U), concavity turned towards the outside of the container 1.

As illustrated on figures 2 and 3 each foot 7 has two flanks 17 which each laterally border a groove 15, so that a groove 15 is bordered laterally by two flanks 17 respectively belonging to the two adjacent feet 7 flanking the groove 15. For a better visibility it has, on the figures 2 and 3 , grayed out by a dot pattern, two sides 17 on either side of the same groove 15 (itself filled with a dotted pattern).

As illustrated on the figure 5 and more obviously in its medallion, the flanks 17 bordering the same groove 15 form between them, at the level of the laying plane 12 and in a plane transverse to the radial direction of extension of the groove 15 and parallel to the X axis , an obtuse angle A at the top.

The angle A at the top between the flanks 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 approximately 120 °.

Each flank 17 is preferably concave, concavity turned towards the outside of the container 1. As can be seen in the medallion of the figure 5 , the radius of curvature of the flank 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 sidewall 17 is less than 1/10, and in particular of the order of 1/15. The flanks 17 thus form, on either side of the groove, an open secondary arch whose function will be highlighted below.

Each flank 17 is connected, on the one hand, to the top 11 of the foot 7, on the other hand, to the groove 15, by leave of small radius.

Moreover, as can be seen from the figures 2 and 3 each flank 17 has, seen from below, a contour in the form of an arrow tail, which flares from a point located in the vicinity of the central zone 8 to an enlarged central portion to the right of the laying plane 12 , then tapers from the central portion to a point located to the right of the outer lateral wall 13 of the bottom 6.

Together, two flanks 17 bordering the same groove 15 define, in a plane parallel to the laying plane 12 , a maximum angular aperture B (centered on the axis X and measured in the laying plane 12 between the outer edges of the central portions of the flanks 17 ). The angular aperture B is preferably greater than the angular aperture C defined by each apex 11. According to a preferred embodiment illustrated in the figures, the angular aperture B is in a ratio with the angular aperture C defined by each vertex, such as: $$\frac{B}{\mathrm{VS}}\cong 2$$

As we see in the figures, and more clearly on the figures 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 zone 8 of the base 6, and an annular peripheral region 19 surrounding the central region 18 , separated by a ring recess 20 which extends axially on a predetermined height. This recess 20 is substantially median with respect to the base 6, that is to say that the central region 18 and the peripheral region 19 have substantially the same radial extension.

The recess 20 extends continuously, that is to say, it is not interrupted to the right of the grooves 15 but extends to the bottom thereof, or to the right of the feet 7, but extends astride thereof, including their lower faces 10 and 17 on their sides.

In the embodiment shown, where the container 1 is of substantially cylindrical shape of revolution about its axis X, the recess 20 forms a ring with a circular contour.

By the presence of the axial recess 20 , the central region 18 of the bottom 6 is slightly offset in height with respect to the peripheral region 19 towards the interior of the container 1.

The recess 20 serves to maintain the stability of the container 1 by inducing a stiffening of the bottom 6 in its central region.

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

Indeed, under the effect of an axial compression (indicated by the arrow on the figure 5 ) exerted on the neck 2 of the container 1 lying flat on its laying plane 12 , the flanks 17 are deformed by opening (that is to say opening the angle A) and flattening towards the 12 laying plan, as illustrated in dotted lines on the medallion of the figure 5 .

This results in a slight deformation by axial compression of the bottom 6, which causes a translation of the entire body 5 (without significant deformation thereof, due to its annular structure with small radii of curvature) towards the plane 12 laying, as illustrated in dotted lines on the figure 5 .

This general deformation has the effect of pressurizing the contents of the container 1, and consequently to increase the rigidity of the container 1, in favor of its resistance to axial compression. The bottom 6, and more generally the container 1, thus behave as a compression spring whose stiffness increases with the compression force applied axially.

The recess 20 makes it possible to limit the axial deformation of the bottom 6 by forming a piston which forms an end stop which, under the effect of a high axial compressive stress, joins the laying plane 12 and thus increases the contact surface of the container with its support.

It follows from these advantages that it is possible to palletize the container 1 without major risk of deformation, which increases productivity and facilitate the handling of pallets.

Claims (9)

1. Plastic container (1) comprising a body (5), which extends along a main axis (X), and a bottom (6) which extends at a lower end of the body (5), the bottom (6) being provided with feet (7) which are formed by protrusions projecting towards the outside of the container (1) and extend from a central zone (8) of the bottom (6), which central zone (8) extends in a recessed manner towards the inside of the container (1) and includes a disc (9) resulting from the injection-moulding of the preform from which the container (1) results and where the material has remained substantially amorphous, the feet (7) being provided with apexes (11) which extend in a common standing plane (12), the feet (7) being separated in pairs by recessed grooves (15) which extend radially from a central zone (8) of the bottom (6), each foot (7) having two flanks (17) which each laterally border a groove (15), in which container the flanks (17) of two adjacent feet (7) which border one and the same groove (15) form between them, at the standing plane (12) and in a plane transverse to the radial direction of extent of the groove (15), an obtuse angle (A) at the apex, each groove (15) having a depth H, measured in line with the standing plane (12) between the latter and the bottom of the groove (15), such that: $$\frac{H}{D}\le \frac{1}{10}$$

   

   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, characterized in that the angle A at the apex between the flanks (17) is between 90° and 150°.
3. Container (1) according to Claim 2, characterized in that the angle A at the apex between the flanks (17) is approximately 120°.
4. Container (1) according to one of the preceding claims, characterized in that each flank (17) has a concavity facing the outside of the container (1).
5. Container (1) according to one of the preceding claims, characterized in that the depth of the groove (15) is such that $$\frac{H}{D}\cong \frac{1}{20}$$

   
6. Container (1) according to one of the preceding claims, characterized in that the flanks (17) bordering one and 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 7, characterized in that the maximum angular opening B of the flanks (17) is such that $$\frac{B}{C}\cong 2$$

   
8. Container (1) according to one of the preceding claims, characterized in the bottom (6) of the container has two concentric regions, namely a central region (18) and a peripheral region (19), separated by a median axial step (20) which extends annularly in a continuous manner, with the result that the central region (18) is offset axially with respect to the peripheral region (19) towards the inside of the container (1).
9. Container (1) according to one of the preceding claims, characterized in that the grooves (15) extend beyond the standing plane (12) on an external lateral wall (13) of the bottom.

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