Container having a corrugated base and mold base for manufacturing such a container

Abstract

Title: Container having a corrugated base and mold base for manufacturing such a container. The present invention relates to a plastic container (1) having a body (5) and a base (6) extending from a lower end of the body, said body (5) comprising at its upper end a shoulder (4) and a neck (2), and the base (6) comprising at least one peripheral heel (7) defining a seat (8), and an arch (10) extending from a central zone (11) to said heel (7), said heel (7) rising on a connecting wall (9) with the wall of the body (5) of the container (1), notable in that said base (6) has a plurality of radial corrugations (13) extending from at least the central zone (11) to near the seat (8), i.e.extending at the level of the vault (6), a corrugation being composed of a concave face (13a) and a convex face (13b) facing outwards, the depth, that is to say the distance between the crest of a convexity (13b) and the bottom of a concavity (13a) of said corrugations (13) increasing from the central zone (11) to near the base (8). Another object of the invention relates to a mold base (23) for the manufacture of such a container (1). Figure for the abstract: Figure 1.

Description

Title of the invention: Container having a corrugated base and mold base for manufacturing such a container. Technical field

[0001] The present invention relates to the field of containers, in particular bottles or pots, manufactured by blow molding or stretch blow molding from blanks made of plastic material such as polyethylene terephthalate (PET) and more particularly from blanks obtained in whole or in part from recycled polyethylene terephthalate (rPET). State of the art

[0002] It is well known that containers intended to hold a flat liquid (for example bottles intended to hold table water) are, in most cases, equipped with a domed bottom in the general shape of a spherical cap with its concavity facing outwards and of relatively low height.

[0003] Usually, the bottoms of these containers are provided with ribs radiating substantially radially which are distributed around a central recess, said ribs being able to have various conformations and possibly extending over the bottom of the body wall in order to reinforce the base (peripheral area by which the bottom rests on a support).

[0004] Such bases are shaped to support without deformation the flat liquid column above them. However, they do not have sufficient strength to withstand additional stress, which may, for example, be due to internal overpressure, even of a small value.

[0005] Now, it is known that, during the packaging of certain easily oxidizable flat liquids such as oil or fruit juices in particular, a small quantity of liquid such as a drop of a rapidly vaporizing inert substance, usually nitrogen, is poured onto the surface of the flat liquid at the end of the container filling phase in order to evacuate the air, and therefore the oxygen contained therein, from the free volume above the liquid surface immediately before the container is sealed, according to an operation called "inerting" or "nitrogenating", in order, for example, to strengthen bottles of light still water.

[0006] This small quantity of inert substance finishes vaporizing once the sealing is complete, so that in the closed container there remains inert gas under a low residual pressure of less than 1.5x105 Pa, typically on the order of 0.8x105 Pa, or even on the order of 0.5x105 Pa.

[0007] However, the slightly domed bottoms traditionally intended for containers intended for flat liquids are not able to reliably withstand, without deformation, a pressure even as low as that generated by the inerting process.

[0008] In order to remedy this drawback, it is well known that, for containers whose contents must undergo an inerting process, they should be equipped with bases improved in terms of resistance so that they do not deform under the action of internal overpressure.

[0009] A reinforced base of this type usually comprises a generally domed arch with its concavity facing outwards from the container and has an annular zone surrounding the arch, forming a substantially flat base on which the base can rest stably on a flat support. In its central part, the arch opens into a domed cup, also with its concavity facing outwards, the cup being thus set back towards the interior of the container relative to the arch. Outside the annular zone forming a base, the base has a return wall, also called the connecting wall with the body of the container.Several main ribs, open outwards and generally shaped like gutters with substantially parallel edges and of substantially constant depth, extend radially in a star shape from the wall at the bottom return to the dome in which they terminate, passing through the annular zone forming a base and the vault, the number of main ribs usually being odd, generally five.

[0010] Furthermore, to improve the mechanical strength of the bottom, secondary ribs are generally added. These secondary ribs may have essentially the same shape as the main ribs, but are interspersed between them. However, they extend radially in a star-like pattern from the bottom's return wall only to the middle of the arch, passing through the annular zone that forms a base. It should be emphasized that all the ribs, both the main and secondary ribs, are formed by hollowing out the arch, which has a smooth annular shape notched only by the ribs.

[0011] However, manufacturers of thermoplastic containers are constantly seeking to reduce the weight of the containers, which is reflected, among other things, in the weight of the bottoms of the containers.

[0012] Consequently, container bottoms with shapes that were initially satisfactory were no longer suitable due to the significant reduction in the amount of material used. Experience has shown that a reinforced bottom arranged as described above, even in its lighter version, could no longer provide satisfactory performance, even for overpressures of only about 0.5 x 0.5 Pa.

[0013] Moreover, due to increasingly higher production rates, the continuous and ultimately random injection of the quantity of inerting liquid and the variations in the free space between the liquid and the rim of the containers, the volume of inerting liquid can vary very significantly, causing pressure variations of plus or minus 0.2 bars for a target pressure of 0.6 bars, i.e. a variation of about 30% of the pressure.

[0014] Under these conditions, the aforementioned funds, in their lightweight version, are therefore not able to reliably withstand such overpressure without sagging.

[0015] To overcome these drawbacks, a container with a reinforced base has already been designed. This is the case, in particular, for documents FR 2 883 550 and FR2932458.

[0016] The aforementioned document FR 2 883 550 describes a container whose base comprises a double structure of domed panels, both with regard to the panels defined between the protruding indentations in the base of the container itself and with regard to the arches of said indentations. Thus, a double bracing system on two levels is constituted and, while not capable of withstanding high pressures, is nevertheless able to withstand, without significant deformation, a relatively low residual pressure not exceeding approximately 0.5 x 10⁵ Pa, such as that which remains after an inerting operation.

[0017] However, the manufacture of this type of container requires a significant amount of thermoplastic material which does not allow obtaining the lightweight version that manufacturers usually require.

[0018] Document FR2932458 describes a container, in particular a bottle, made of thermoplastic material such as PET, having a body extending between, at the top, a neck and, at the bottom, a base capable of withstanding without significant deformation the overpressure induced by an inerting operation not exceeding approximately 2105 Pa. Said base comprising a concave arch with concavity facing outwards from the container, a dome projecting inwards from the container and with concavity facing outwards, opening at the center of said arch, an annular zone surrounding the base of said arch and forming a substantially flat surface by which said base can rest stably on a flat support, and ribs in the form of grooves open outwards, of substantially radial extent crossing said annular zone forming a surface and rising up the wall connecting with the wall of the body of the container.The said base also includes claw-shaped areas, separated from each other, which extend the bottom of the body radially towards the central axis of the base and which are offset in external projection relative to the said vault, and radial grooves delimited between the said claw-shaped areas, the bottom of which is formed by sections. radial of said vault and which have a radially variable depth which is maximum approximately at the right of said annular zone forming a base.

[0019] All these types of container cannot be filled with flat and closed liquids in the presence of a relatively low pressure, in principle on the order of 0.5x10 5 Pa and in practice not exceeding about 1xl05 Pa, since said containers are obtained in recycled PET called rPET, said rPET having mechanical properties different from those of PET so that the bottoms of these containers do not have sufficient resistance to shocks. Disclosure of the invention

[0020] One of the aims of the invention is therefore to remedy all or part of these drawbacks by proposing a container of simple and inexpensive design, obtained from recycled PET called rPET, suitable for being filled with flat liquids and closed in the presence of a relatively low pressure in principle of the order of 0.5 x 0.5 Pa and in practice not exceeding about 1 x 0.5 Pa, requiring only a minimum of thermoplastic material, easy to conform correctly under the usual conditions of blow molding or stretch blow molding of containers intended for flat liquids, exhibiting good resistance to impacts and having a height substantially of the same order of magnitude as that of the bottoms of traditional containers for flat liquids.

[0021] To this end, and in accordance with the invention, a plastic container is proposed having a body and a base extending from a lower end of the body, said body comprising at its upper end a shoulder and a neck, and the base comprising at least one peripheral heel defining a base, and an arch extending from a central zone to said heel, said heel rising onto a connecting wall with the wall of the container body, notable in that said base has a plurality of radial undulations in continuous tangency extending from at least the central zone to near the base, i.e. extending to the level of the arch, an undulation being made up of a concave face and a convex face turned outwards, the depth, i.e. the distance between the crest of a convexity and the bottom of a concavity, of said undulations increasing from the central zone to near the seat.

[0022] Preferably, the radial undulations are in tangent continuity.

[0023] Alternatively, said radial undulations may comprise at least one facet, each facet extending radially or extending perpendicularly to a radius of the bottom, and each facet may be flat or concave or raised and may have any shape.

[0024] Preferably, the average radius of curvature of the concavities of the undulations is less than or equal to the average radius of curvature of the convexities of the undulations.

[0025] Furthermore, the average radius of curvature of the concavities of the undulations is between 0.5 and 1.1 times the average radius of curvature of the convexities of the undulations.

[0026] Preferably, said average radius of curvature of the concavities of the undulations is between 0.65 and 0.85 times the average radius of curvature of the convexities of the undulations.

[0027] Furthermore, the average radius of curvature of the concavities and / or convexities of the undulations is not constant along a radius of the bottom, from the central zone towards the support plane.

[0028] In addition, the bottom has between 5 and 15 radial undulations in continuity of tangency and, preferably, between 8 and 10 radial undulations in continuity of tangency.

[0029] Preferably, the height of the vault, i.e. the distance separating the seating plane from the upper end of the vault, is between 0.15 and 0.35 times the diameter of the seating.

[0030] Preferably, the height of the vault is between 0.2 and 0.25 times the diameter of the base, and preferably equal to 0.228 times the diameter of the base.

[0031] Furthermore, the depth of an undulation at the level of the seating plane is between 0.2 and 0.45 times the height of the vault.

[0032] In addition, the depth of a wave at the level of the central zone is between 0.03 and 0.15 times the height of the vault.

[0033] Moreover, between the central zone and the seating plane, the depth of an undulation is between 0.2 and 0.45 times the height of the vault.

[0034] According to one embodiment, said undulations extend beyond the seat.

[0035] According to another embodiment, the concave face of the undulations extends beyond the seat and the convex face of the undulations extends from the central area to near the seat.

[0036] Furthermore, the so-called external radius of curvature of the heel, i.e. the radius of curvature of the heel between the base and the connecting wall, is between 0.07 and 0.2 times the diameter of the base and, preferably, is equal to 0.13 times the diameter of the base.

[0037] Furthermore, the so-called inner radius of curvature of the heel, i.e. the radius of curvature of the heel between the distal end of the convex face of the undulations and the seat, is between 0.6 and 1.4 times the outer radius of curvature of said heel and, preferably, is equal to 0.92 times the outer radius of curvature of said heel.

[0038] Furthermore, the height of the vault, i.e. the distance separating the central area from the ground plane, is between 0.2 and 0.4 times the diameter of the ground.

[0039] In addition, the width of the seat is between 0.1 and 2 mm and, preferably, equal to 0.5 mm.

[0040] Another object of the invention relates to a mold base for manufacturing a container according to the invention from a plastic preform, said mold base being suitable for mounting at one end of a mold comprising two walls movable relative to each other and intended to form the body of the container, said mold base comprising at least a first annular portion intended to form at least part of the base, i.e.the base plane, a second dome-shaped part intended to come into contact with an amorphous central zone of the preform to form the vault, or comprising a bottom disc allowing to form the heel of the container and a vault piece inserted into said bottom disc; said mold base is remarkable in that said second part or vault piece comprises a plurality of radial undulations extending from at least a central zone to the first annular part or to the bottom disc, i.e. extending at least to the level of the second dome-shaped part, the depth, i.e. the distance between the crest of a convexity and the bottom of a concavity, of said undulations being increasing from the central zone to the periphery of the second part or to the bottom disc.

[0041] Preferably, the average radius of curvature of the concavities of the undulations is less than or equal to the average radius of curvature of the convexities of the undulations.

[0042] Moreover, the average radius of curvature of the concavities of the undulations is between 0.5 and 1.1 times the average radius of curvature of the convexities of the undulations and, preferably, is between 0.65 and 0.85 times the average radius of curvature of the convexities of the undulations.

[0043] Furthermore, the average radius of curvature of the concavities and / or convexities of the undulations is not constant along a radius of the bottom of the mold base, from the central area towards the periphery of the second part, the bottom washer.

[0044] Preferably, the bottom of the mold has between 3 and 15 radial undulations in continuity of tangency and, preferably, has between 8 and 10 radial undulations in continuity of tangency. Brief description of the drawings

[0045] Other advantages and features will become clearer from the following description of several embodiments, given by way of non-limiting examples, of the container and the mold base for manufacturing said container according to the invention, with reference to the accompanying drawings in which:

[0046] [Fig. 1] is a perspective view from below of a plastic container according to the invention,

[0047] [Fig.2] is a perspective view from below of the bottom of a plastic container according to the invention,

[0048] [Fig.3] is a bottom view of the base of the plastic container according to the invention represented in figures 1 and 2,

[0049] [Fig.4] is a side view of the bottom of the plastic container according to the invention represented in figures 1 to 3,

[0050] [Fig.5] is a torn perspective view from below of the bottom of the container in plastic according to the invention shown in figures 1 to 4,

[0051] [Fig.6] is a torn perspective top view of the bottom of the container in plastic according to the invention shown in figures 1 to 5,

[0052] [Fig.7] is a radial cross-sectional view of the bottom of the following plastic container the invention shown in figures 1 to 6,

[0053] [Fig.8] is a perspective view from below of an embodiment of the plastic container according to the invention,

[0054] [Fig.9] is a perspective view from below of the bottom of the embodiment variant of the container according to the invention shown in [Fig.8],

[0055] [Fig. 10] is a bottom view of the bottom of the embodiment of the container according to the invention shown in Figures 8 and 9,

[0056] [Fig. 11] is a radial cross-sectional view of the bottom of the embodiment of the plastic container according to the invention shown in Figures 8 to 10,

[0057] [Fig. 12] is an exploded perspective view of a mold, including a mold base, for manufacturing a container according to the invention,

[0058] [Fig. 13] is a perspective top view of a mold bottom for obtaining a container according to the invention shown in Figures 1 to 7,

[0059] [Fig. 14] is a top view of the mold bottom for obtaining a container according to the invention shown in Figures 1 to 7,

[0060] [Fig. 15] is a radial cross-sectional view of the mold bottom according to the invention shown in Figures 13 and 14,

[0061] [Fig. 16] is a perspective top view of an embodiment variant of a mold base for obtaining a container according to the invention shown in Figures 8 to 11,

[0062] [Fig. 17] is a perspective top view of the embodiment variant of the mold bottom according to the invention shown in [Fig. 16],

[0063] [Fig. 18] is a radial cross-sectional view of the embodiment variant of the mold bottom according to the invention shown in [Fig. 16]. Method of embodiment of the invention

[0064] In the remainder of the description of the container and the mold base for obtaining said container according to the invention, the same numerical references designate the same elements. Furthermore, the different views are not necessarily drawn to scale.

[0065] With reference to [Fig.1], the container 1 according to the invention consists, in this case, of a bottle made by stretch blow molding from a preform in thermoplastic material, for example in PET (polyethylene terephthalate) and / or rPET (recycled polyethylene terephthalate), or similar.

[0066] Said container 1 comprises, at an upper end, a neck 2, provided with a mouth 3. In the extension of the neck 2, in the direction of the lower end of the container 1, the latter usually comprises, in its upper part, a shoulder 4 going outward in the opposite direction to the neck 2, this shoulder 4 being extended by a lateral wall or body 5, generally substantially cylindrical in shape of revolution about a vertical longitudinal axis X, represented in dashed lines, of the container 1.

[0067] The container 1 further comprises a base 6 extending opposite the neck 2 from a lower end of the body 5. Said base 6 comprises a peripheral heel 7 in the form of an annular ridge extending substantially axially in line with the body 5. The heel 7 terminates in a support 8, also called a base, perpendicular to the longitudinal axis X of the container 1, said support 8 defining the lower end of the container 1 and enabling the container 1 to be placed vertically on a flat surface. In addition, said heel 7 extends up a wall called a connecting wall 9 with the wall of the body 5 of the container 1.

[0068] DI denotes the diameter of the mounting plane 8, the term "diameter" covering not only the case (illustrated) where the container 1 (and therefore the base 6) has a circular contour, but also the case where the container 1 would have a polygonal contour (for example square), in which case the term "diameter" would designate the diameter of the circle in which this polygon would be inscribed without going out of the scope of the invention.

[0069] Furthermore, the bottom 6 also includes a concave vault 10, in the form of a substantially spherical cap with its concavity facing outwards from the container 1 in the absence of stress, i.e. in the absence of contents in the container 1. The vault 10 extends from the heel 7 to a central area 11 of the bottom 6 forming a pin projecting towards the inside of the container 1, with in its center an amorphous pellet 12 which corresponds to the injection area of ​​the material constituting the preform used to make the container and can fulfill a centering function during the blow forming of the container 1.

[0070] Furthermore, with reference to Figures 1 to 6, said base 6 comprises a plurality of radial undulations 13 in continuous tangency extending from at least the central zone 11 to near the heel 7, i.e. extending at the level of the arch 10, an undulation 13 being composed of a concave face 13a and a convex face 13b turned outwards, the depth, that is to say the distance between the crest of a convexity and the bottom of a concavity, of said undulations 13 being increasing from the central zone 10 to near the heel 7.

[0071] It is quite clear that the said radial undulations 13 may not be in continuity of tangency and may include, for example, one or more facets of any shape, flat and / or hollow and / or raised, extending radially or perpendicularly to a radius of the bottom 6, without going out of the scope of the invention.

[0072] In this first embodiment of the container according to the invention, the concave face 13a of the corrugations 13 extends beyond the seat 8 and the convex face 13b of the corrugations 13 extends from the central area to near the seat 8. “Near the seat” means a few millimeters before the seat 8. Thus, in this embodiment, the convex face 13b of the corrugations 13 extends to the level of the connecting wall forming feet 14 at the level of the seat 8, which is thus discontinuous.

[0073] Preferably, the average radius of curvature of the concavities of the undulations 13 is less than or equal to the average radius of curvature of the convexities of said undulations 13. More precisely, the average radius of curvature of the concavities of the undulations 13 is between 0.5 and 1.1 times the average radius of curvature of the convexities of the undulations 13. It will be noted that the term "convexities of the undulations" refers to the convex faces 13b of said undulations.

[0074] Furthermore, said average radius of curvature of the concavities of the undulations 13 is between 0.65 and 0.85 times the average radius of curvature of the convexities of the undulations 13. It should be noted that "concavities of the undulations" means the concave faces 13a of said undulations.

[0075] Furthermore, the average radius of curvature of the concavities and / or convexities of the undulations 13 is not constant along a radius of the bottom 6, from the central zone 11 towards the base 8.

[0076] In this particular embodiment, the bottom 6 has 10 radial undulations 13 in tangent continuity. However, depending on the dimensions of the container and / or the application of said container, said bottom 6 may include between 5 and 15 radial undulations in tangent continuity and, preferably, between 8 and 10 radial undulations in tangent continuity.

[0077] Furthermore, the height of the vault 10, i.e. the distance separating the ground plane from the upper end of the vault 10, is preferably between 0.15 and 0.35 times the diameter DI of the ground 8. Preferably, the height of the vault 10 is between 0.2 and 0.25 times the diameter DI of the ground 8 and, preferably, is equal to 0.228 times the diameter DI of the ground 8.

[0078] Advantageously, the depth of a condulation 13 at the level of the ground plane, that is to say the distance between the crest of a convexity 13b and the bottom of a concavity 13a, is preferably between 0.2 and 0.45 times the height of the vault 10.

[0079] In addition, the depth of a wave at the level of the central zone is between 0.03 and 0.15 times the height of the vault.

[0080] Moreover, between the central zone 11 and the ground plane, the depth of a wave is between 0.2 and 0.45 times the height of the vault 10.

[0081] Advantageously, the so-called external radius of curvature of the heel, i.e. the radius of curvature of the heel between the seat and the connecting wall, is between 0.07 and 0.2 times the seat diameter and, preferably, is equal to 0.13 times the seat diameter.

[0082] Furthermore, the so-called inner radius of curvature of the heel 7, i.e. the radius of curvature of the heel 7 between the distal end of the convex face 13b of the undulations 13 and the seat 8, is between 0.6 and 1.4 times the outer radius of curvature of said heel 7 and, preferably, is equal to 0.92 times the outer radius of curvature of said heel 7.

[0083] Furthermore, the height of the vault 10, i.e. the distance separating the central zone 11 from the seating plane, is between 0.2 and 0.4 times the diameter DI of the seating, the width of the seating being between 0.1 and 2 mm and, preferably, equal to 0.5 mm.

[0084] According to a second embodiment of the container according to the invention with reference to figures 8 to 11, the container 1 consists, in the same way as before, of a bottle made by stretch blow molding from a preform in thermoplastic material, for example in PET (polyethylene terephthalate) and / or rPET (recycled polyethylene terephthalate), or similar.

[0085] Said container 1 comprises, at an upper end, a neck 2, provided with a mouth 3. In the extension of the neck 2, towards the lower end of the container 1, the latter usually comprises, in its upper part, a shoulder 4 going outwards in the opposite direction to the neck 2, this shoulder 4 being extended by a lateral wall or body 5, generally substantially cylindrical in shape of revolution about a vertical longitudinal axis X, represented in dashed lines, of the container 1.

[0086] The container 1 further comprises a base 6 extending opposite the neck 2 from a lower end of the body 5. Said base 6 comprises a peripheral heel 7 in the form of an annular ridge extending substantially axially in line with the body 5. The heel 7 terminates in a support 8, also called a base, perpendicular to the longitudinal axis X of the container 1, said base 8 defining the lower end of the container 1 and enabling the container 1 to be placed vertically on a flat surface. In addition, said heel 7 extends up a wall called a connecting wall 9 with the wall of the body 5 of the container 1.

[0087] DI denotes the diameter of the mounting plane 8, the term "diameter" covering not only the case (illustrated) where the container 1 (and therefore the base 6) has a circular contour, but also the case where the container 1 would have a polygonal contour (for example square), in which case the term "diameter" would designate the diameter of the circle in which this polygon would be inscribed without going out of the scope of the invention.

[0088] Furthermore, the bottom 6 also includes a concave vault 10, in the form of a substantially spherical cap with its concavity facing outwards from the container 1 in the absence of stress, i.e. in the absence of contents in the container 1. The vault 10 extends from the heel 7 to a central area 11 of the bottom 6 forming a pin projecting towards the inside of the container 1, with in its center an amorphous pellet 12 which corresponds to the injection area of ​​the material constituting the preform used to make the container and can fulfill a centering function during the blow forming of the container 1.

[0089] Furthermore, with reference to Figures 8 to 11, said base 6 comprises a plurality of radial undulations 13 in continuity of tangency extending from at least the central zone 11 to near the course 8, i.e. extending to the level of the vault 10, an undulation 13 being made up of a concave face 13a and a convex face 13b turned outwards, the depth, i.e. the distance between the crest of a convexity and the bottom of a concavity, of said undulations 13 being increasing from the central zone 10 to near the course 8.

[0090] In this second embodiment of the container according to the invention, the concave face 13a and the convex face 13b of the undulations 13 extend from the central zone 11 to near the seat 8. "Near the seat" means a few millimeters before the seat 8. Thus, unlike the previous embodiment, the base 6 does not have feet at the level of the seat 8, the seat 8 being continuous.

[0091] In the same way as before, the average radius of curvature of the concavities of the undulations 13 is preferably less than or equal to the average radius of curvature of the convexities of said undulations 13. More precisely, the average radius of curvature of the concavities of the undulations 13 is between 0.5 and 1.1 times the average radius of curvature of the convexities of the undulations 13. It will be noted that the term "convexities of the undulations" refers to the convex faces 13b of said undulations.

[0092] Furthermore, said average radius of curvature of the concavities of the undulations 13 is between 0.65 and 0.85 times the average radius of curvature of the convexities of the undulations 13. It should be noted that "concavities of the undulations" means the concave faces 13a of said undulations.

[0093] Moreover, the average radius of curvature of the concavities and / or convexities of the undulations 13 is not constant along a radius of the bottom 6, from the central zone 11 towards the base 8.

[0094] In this particular embodiment, the bottom 6 has 9 radial undulations 13 in tangent continuity. However, depending on the dimensions of the container and / or the application of said container, said bottom 6 may include between 5 and 15 radial undulations in tangent continuity and, preferably, between 8 and 10 radial undulations in tangent continuity.

[0095] Furthermore, the height of the vault 10, i.e. the distance separating the ground plane from the upper end of the vault 10, is preferably between 0.15 and 0.35 times the diameter DI of the ground 8. Preferably, the height of the vault 10 is between 0.2 and 0.25 times the diameter DI of the ground 8 and, preferably, is equal to 0.228 times the diameter DI of the ground 8.

[0096] Moreover, between the central zone 11 and the ground plane, the depth of a wave is between 0.2 and 0.45 times the height of the vault 10.

[0097] Finally, the height of the vault 10, i.e. the distance separating the central zone 11 from the seating plane, is between 0.2 and 0.4 times the diameter DI of the seating, the width of the seating being between 0.1 and 2 mm and, preferably, equal to 0.5 mm.

[0098] With reference to figures 12 to 18, a molding unit 19 according to the invention is described for forming, from a blank, usually typically a preform, a container according to the invention, such as a bottle or a can, according to the invention.

[0099] Said molding unit 19, with reference to [Fig. 12], comprises a mold 20 having a lateral wall 21 that defines a cavity 22 in the shape of a portion of the container. Said mold 20 further comprises a base 23 in the shape of the base of the container, said mold 20 being made of metal, for example steel or aluminum (this term also covering aluminum alloys). The cavity 22, and ultimately the container 20, extends along a principal axis X that defines a vertical direction. Any plane perpendicular to the principal axis X is said to be horizontal.According to an embodiment illustrated in the drawings, the side wall 21 comprises two half-molds 20A, 20B, each defining a half-cavity 24A, 24B of the container body, and mounted in rotation relative to each other about a common axis formed by a hinge, not shown in the figures, between an open position, in which the half-molds 20A, 20B are angularly separated from each other and the mold bottom 23 is lowered relative to the half-molds 20A, 20B to allow the introduction of the blank and the evacuation of the formed container, and a closed position, in which the half-molds 20A, 20B are applied against each other and enclose the mold bottom 23 between them, as shown in figures 6 to 8, thus forming the cavity 22 and defining. the imprint of the container to be formed. Thus, the said mold base 23 is suitable for being mounted movably in the mold 20 comprising two walls movable relative to each other and intended to form the body of the container.

[0100] With reference to Figures 13 to 15, for the manufacture of a container according to the invention shown in Figures 1 to 7, said mold bottom 23 comprises a plurality of radial undulations 113 in continuity of tangency extending from a central zone 111 to near a base 108, i.e. extending at the level of an arch 110, an undulation 113 being made up of a concave face 113a and a convex face 113b turned outwards, the depth, i.e. the distance between the crest of a convexity and the bottom of a concavity, of said undulations being increasing from the central zone 11 to near the base 108.

[0101] Preferably, the average radius of curvature of the concavities of the undulations 113 is less than or equal to the average radius of curvature of the convexities of the undulations 113.

[0102] Moreover, the average radius of curvature of the concavities 113a of the undulations is between 0.5 and 1.1 times the average radius of curvature of the convexities 113b of the undulations and, preferably, is between 0.65 and 0.85 times the average radius of curvature of the convexities 113b of the undulations 113.

[0103] Furthermore, the average radius of curvature of the concavities 113a and / or convexities 113b of the undulations 113 is not constant along a radius of the bottom of the mold bottom 23, from the central zone 111 towards the periphery of the seat 108.

[0104] Preferably, the mold bottom 23 has between 5 and 15 radial undulations 113 in continuity of tangency and, preferably, has between 8 and 10 radial undulations 113 in continuity of tangency.

[0105] According to one embodiment, with reference to Figures 16 to 18, for manufacturing a container according to the invention shown in Figures 8 to 11, said mold base 23 consists of a base washer 200 for forming the base of the container and an arch piece 201 inserted into said base washer 200. Said arch piece 201 of the mold base 23 comprises a plurality of radial undulations 113 in tangent continuity extending from a central zone 111 to near a base 108, i.e., extending at the level of an arch 110, an undulation 113 being composed of a concave face 113a and a convex face 113b facing outwards, the depth, i.e., the distance between the crest of a convexity and the bottom of a concavity, said undulations being increasing from the central zone 11 to near the base 108.

[0106] Preferably, the average radius of curvature of the concavities of the undulations is less than or equal to the average radius of curvature of the convexities of the undulations 113.

[0107] Furthermore, the average radius of curvature of the concavities 113a of the undulations is between 0.5 and 1.1 times the average radius of curvature of the convexities 113b of the undulations and, preferably, is between 0.65 and 0.85 times the average radius of curvature of the convexities 113 b of the undulations 113.

[0108] Furthermore, the average radius of curvature of the concavities 113a and / or convexities 113b of the undulations 113 is not constant along a radius of the bottom of the mold bottom 23, from the central zone 111 towards the periphery of the seat 108.

[0109] Preferably, the mold bottom 23 has between 5 and 15 radial undulations 113 in tangent continuity and, preferably, has between 8 and 10 radial undulations 113 in tangent continuity.

[0110] Finally, it is quite clear that the examples just given are only particular illustrations and in no way limiting as to the fields of application of the invention.

Claims

Demands

1. A plastic container (1) having a body (5) and a base (6) extending from a lower end of the body, said body (5) comprising at its upper end a shoulder (4) and a neck (2), and the base (6) comprising at least one peripheral heel (7) defining a seat (8), and an arch (10) extending from a central area (11) to said heel (7), said heel (7) extending up a connecting wall (9) with the wall of the body (5) of the container (1), characterized in that said base (6) has a plurality of radial corrugations (13) extending from at least the central area (11) to near the seat (8), i.e.extending at the level of the vault (6), an undulation being made up of a concave face (13a) and a convex face (13b) turned outwards, the depth, that is to say the distance between the crest of a convexity (13b) and the bottom of a concavity (13a) of said undulations (13) being increasing from the central zone (11) to near the base (8).

2. Container (1) according to claim 1 characterized in that the radial undulations (13) are in continuity of tangency.

3. Container (1) according to claim 1 characterized in that the radial undulations (13) comprise at least one facet.

4. Container (1) according to claim 3 characterized in that each facet extends radially.

5. Container (1) according to claim 3 characterized in that each facet extends perpendicularly to a radius of the bottom (6).

6. Container (1) according to any one of claims 3 to 5 characterized in that each facet is flat or concave or raised.

7. Container (1) according to any one of claims 1 to 6 characterized in that the average radius of curvature of the concavities (13a) of the undulations (13) is less than or equal to the average radius of curvature of the convexities (13b) of the undulations (13).

8. Container according to any one of claims 1 to 7 characterized in that the average radius of curvature of the concavities (13a) of the undulations (13) is between 0.5 and 1.1 times the average radius of curvature of the convexities (13b) of the undulations (13).

9. Container according to claim 8 characterized in that the average radius of curvature of the concavities (13a) of the undulations (13) is between 0.65 and 0.85 times the average radius of curvature of the convexities (13b) of the undulations (13).

10. Container according to any one of claims 1 to 9 characterized in that the average radius of curvature of the concavities (13a) and / or convexities (13b) of the undulations (13) is not constant along a radius of the bottom (6), from the central area (11) towards the base (8).

11. Container according to any one of claims 1 to 10 characterized in that the bottom (6) has between 3 and 15 radial undulations (13).

12. Container according to claim 11 characterized in that the bottom (6) preferably has between 8 and 10 radial undulations (13).

13. Container according to any one of claims 1 to 12 characterized in that the height of the arch (10), i.e. the distance separating the seating plane from the upper end of the arch (10), is between 0.15 and 0.35 times the diameter (Dl) of the seat (8).

14. Container according to claim 13 characterized in that the height of the arch (10) is between 0.2 and 0.25 times the diameter (Dl) of the base (8) and, preferably, is equal to 0.228 times the diameter (Dl) of the base (8).

15. Container according to any one of claims 1 to 14 characterized in that the depth of a corrugation (13) at the level of the seating plane is between 0.2 and 0.45 times the height of the arch (10).

16. Container according to any one of claims 1 to 15 characterized in that the depth of a corrugation (13) at the level of the central zone (11) is between 0.03 and 0.15 times the height of the arch (10).

17. Container according to any one of claims 1 to 16 characterized in that, between the central zone (11) and the base (8), the depth of a corrugation (13) is between 0.2 and 0.45 times the height of the arch (10).

18. Container according to any one of claims 1 to 17 characterized in that said corrugations (13) extend beyond the seat (8).

19. Container according to any one of claims 1 to 17 characterized in that the concave face (13a) of the corrugations (13) extends beyond the seat (8) and in that the convex face (13b) of the corrugations (13) extends from the central area (11) to near the seat (8).

20. Container according to claim 19 characterized in that the so-called external radius of curvature of the heel (7), i.e. the radius of curvature of the heel (7) between the seat (8) and the connecting wall (9), is between 0.07 and 0.2 times the diameter of the seat (Dl).

21. container according to claim 20 characterized in that the external radius of curvature of the heel (7) is equal to 0.13 times the seat diameter (Dl).

22. Container according to any one of claims 20 or 21 characterized in that the so-called inner radius of curvature of the heel (7), i.e. the radius of curvature of the heel (7) between the distal end of the convex face (13b) of the corrugations (13) and the seat (8), is between 0.6 and 1.4 times the outer radius of curvature of said heel (7).

23. Container according to claim 22 characterized in that the inner radius of curvature of the heel (7) is equal to 0.92 times the outer radius of curvature of said heel (7).

24. Container according to any one of claims 1 to 23 characterized in that the height of the arch (10), i.e. the distance separating the central zone (11) from the seating plane, is between 0.2 and 0.4 times the diameter (Dl) of the seat (8).

25. Container according to any one of claims 1 to 23 characterized in that the width of the seat (8) is between 0.1 and 2 mm and, preferably, equal to 0.5 mm.

26. Mold base (23) for manufacturing a container (1) according to any one of claims 1 to 25 from a plastic preform, said mold base (23) being able to be mounted at one end of a mold (20) comprising two walls movable relative to each other and intended to form the body (5) of the container (1), said mold base (23) comprising at least a first annular portion intended to form at least in part the base (7), i.e. the seat surface, and a second dome-shaped portion intended to come into contact with an amorphous central zone of the preform to form the arch (10), or comprising a base washer (200) for forming the base (7) of the container (1) and a piece of vault (201) fitting into said bottom washer (200), characterized in that said second part or said vault piece (201) of the bottom of mold (23) comprises a plurality of radial undulations (113) extending from at least a central zone (111) to the first annular part or to the bottom washer (200), i.e. extending at least to the level of the second dome-shaped part or the vault piece (201), the depth, i.e. the distance between the crest of a convexity (113b) and the bottom of a concavity (113a), of said undulations (113) increasing from the central zone (111) to the periphery of the second part or to the bottom washer (200).

27. ​​Mold base according to claim 26 characterized in that the average radius of curvature of the concavities (113a) of the undulations (113) is less than or equal to the average radius of curvature of the convexities (113b) of the undulations (113).

28. Mold base according to any one of claims 26 or 27 characterized in that the average radius of curvature of the concavities (113a) of the undulations (113) is between 0.5 and 1.1 times the average radius of curvature of the convexities (113b) of the undulations (113).

29. Mold base according to claim 28 characterized in that the average radius of curvature of the concavities (113a) of the undulations (113) is between 0.65 and 0.85 times the average radius of curvature of the convexities (113b) of the undulations (113).

30. Mold bottom according to any one of claims 26 to 29 characterized in that the average radius of curvature of the concavities (113a) and / or convexities (113b) of the undulations (113) is not constant along a radius of the bottom of the mold bottom (23), from the central area (111) towards the periphery of the second part or towards the bottom washer (200).

31. Mold bottom according to any one of claims 26 to 30 characterized in that the mold bottom (23) has between 3 and 15 radial undulations in continuity of tangency.

32. Mold bottom according to claim 31 characterized in that the mold bottom has between 8 and 10 radial undulations in continuity of tangency.

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