Neck ring for a blow-moulding mould

Abstract

The present invention relates to a so-called neck ring (1) for a blow-moulding mould, which ring consists of two semi-annular parts (1a, 1b), each semi-annular part (1a, 1b) of the ring (1) comprising a semicircular inner peripheral edge forming a so-called under-neck segment (2) which extends below the peripheral edge from the upper face (3) to the lower face (4) of each semi-annular part (1a, 1b), a semicircular outer peripheral edge (5) and two diametrically opposite lateral edges (6), the lateral edges (6) connecting the ends of the outer (5) and inner (2) peripheral edges, each semi-annular part (1a, 1b) of the ring (1) also comprising, on its upper face (3), a planar semi-annular shoulder (7) extending along the inner peripheral edge (2), from one lateral edge (6) to the other, the collar (22) of a neck (21) of a preform (20) being able to bear on the shoulder (7), characterized in that the under-neck segment (2) comprises, from the upper face (3) to the lower face (4) of each semi-annular part (1a, 1b), at least one so-called convex upper section (8) forming the edge between the shoulder (7) and all or part of the under-neck segment (2), and a so-called substantially semi-frustoconical lower section (9) flaring from the convex section (8) towards the lower face (4) of each semi-annular part (1a, 1b).

Description

Neck ring for blow mold

[0001] The present invention relates to the field of molding containers such as bottles from preforms in polyethylene terephthalate (PET) and / or recycled polyethylene terephthalate (rPET), or in any other equivalent material such as polypropylene (PP) for example, which are blown into a mold and, more particularly, a neck ring for a blow mold, said ring enabling the blowing of containers with lightweight necks to be secured. State of the art

[0002] In the field of plastic bottle production, it is well known that a plastic blank, also called a parison or preform, can be heated, placed in a blow mold, and then blow-molded to its final size. This is typically done using blow molds, which are closed around the outside of the blank to be blown, and then compressed air is injected through the mold opening.

[0003] The opening of the future bottle, commonly called the neck, is already formed on the parison and is not further processed. For the actual blowing operation, a circumferential edge or collar of the parison rests on a circumferential edge of the blow mold, commonly called the neck ring, thus preventing the preform from collapsing inside the blow mold, the neck of the preform, and more specifically the collar of said neck, resting on said neck ring.

[0004] In other words, as soon as the blow mold is closed, the preform rests directly on a plane of the blow mold and / or a neck ring, said neck ring being usually removable in order in particular to adapt the dimensions of said neck ring according to the dimensions of the preforms used.

[0005] Such collar rings are well known and are described in documents WO0185435, US6113377 and EP1964660 among others.

[0006] Document WO0185435 describes an apparatus and method for blow molding large-capacity containers. More specifically, this document describes a blow mold for use in a rotary blow molding machine, comprising at least two blow-molded segments that together define a container-shaped inner cavity and a cooling circuit incorporated within each segment. The mold consists of two mold segments, divided along a radial plane. The mold segments together define a container-shaped inner cavity. The mold can be hinged open and / or closed about the radial plane. The mold segments align at their upper edge to form a neck ring that defines an opening capable of receiving a preform inside, forming a seat with said neck ring.

[0007] US patent 6113377A describes a mold forming a cavity for extruding / blowing articles using an extrusion / blowing apparatus. The mold comprises a support attached to the extrusion / blowing apparatus, the wall of which defines a recess in the support, and a removable insert called a neck ring that fits into the recess and whose surface forms part of the molding cavity. The support and the neck ring are aligned by means of cooperating locating means located respectively on the insert and the support element.

[0008] This type of neck ring has the disadvantage of not securing the blowing of containers with so-called lightweight necks.

[0009] To address this drawback, a neck ring has already been designed to secure the blowing of containers with lightweight necks. This is the case, in particular, with document EP1964660.

[0010] Document EP1964660 describes a neck ring for a blow mold with a flat peripheral edge against which the neck of a container to be treated can rest, and with a cylindrical segment extending perpendicularly to the plane of the peripheral edge. A spacer means projecting radially from the cylindrical segment inward is provided against the cylindrical segment. This spacer means is capable of reducing a forming gap between the container to be treated and a neck area of ​​the blow mold, and a radially reduced area of ​​the neck area of ​​the container to be treated can be obtained by the spacer means. Furthermore, the gap between a wall of the spacer means and a wall of the cylindrical segment is between 0.2 and 1.2 mm.

[0011] However, this type of neck ring has the disadvantage of not sufficiently securing the blowing of containers with lightweight necks.

[0012] Indeed, since the inception of PET stretch blow molding, it has been agreed that the centering of a preform within the mold is achieved using the neck diameter. Thus, there is a gap between the neck of the preform and the mold, this gap being less than that between the area under the neck and the mold. This gap between the neck and the mold is therefore 0.35 mm at the diameter, while the gap between the area under the neck and the mold is generally around 0.5 mm.

[0013] The area under the neck which has a 0.5mm gap is historically straight on the plan, but in fact this same area on the bottle is never completely straight, this is due to the fact that the heating of the preform cannot be applied immediately under the neck without overheating the necks, and also to the fact that, during unclipping, the straight area under the neck also acts as a stop for unclipping the preforms even though, theoretically, only the collar should have this role.

[0014] Thus, the area under the neck of blown containers is generally partially straight on one side where the unclipping force was applied, and rather conical on the opposite side. However, the final impression in this area is never completely homogeneous, and the stretching of the amorphous area under the neck can often be slightly slanted.

[0015] This principle works, but it has a limitation with very thin necks, which often have a small and fragile collar. Indeed, on these thin-neck containers, a 0.5mm gap in the diameter below the neck can be enough to deform the collar during stretching due to the thin neck, the temperature transferred to the PET, and the stretching speed, among other factors.

[0016] Therefore, there is a need to provide a solution to secure the blowing of containers with lightweight necks and to improve the stretching under the neck.

[0017] Furthermore, this type of neck ring as described in document EP1964660, and more particularly the means of protruding spacing of the neck ring, has the disadvantage of generating an annular groove under the collar of the blown container, said annular groove being likely to create problems in conveying the blown containers to the so-called post-blow units such as the filler, the labeler, etc. Indeed, said annular groove thus produced under the collar is likely to affect the proper gripping of the containers by the conveying devices usually used such as trays or guides for example. Disclosure of the invention

[0018] One of the aims of the invention is therefore to remedy all or part of these disadvantages by proposing a neck ring of design and low cost which makes it possible to secure the blowing of containers with lightweight necks, to improve the stretching under the neck and to avoid the appearance of an annular groove under the collar.

[0019] To this end, and in accordance with the invention, a neck ring for a blow mold is proposed, consisting of two semi-annular parts, each semi-annular part of said ring comprising an internal semi-circular peripheral edge forming a segment called the sub-neck which extends below the peripheral edge from the upper face to the lower face of each semi-annular part, an external semi-circular peripheral edge and two diametrically opposed lateral edges, said lateral edges connecting the ends of the external and internal peripheral edges, each semi-annular part of said ring also comprising on its upper face a flat semi-annular shoulder extending along the internal peripheral edge, from one lateral edge to the other, the collar of a neck of a preform being adapted to bear against said shoulder, said neck ring being notable in that said sub-neck segment comprises,From the upper to the lower face of each hemi-annular part, at least one convex upper section forming the ridge between the shoulder and all or part of the segment below the neck, and a substantially semi-conical lower section flaring out from the convex section towards the lower face of each hemi-annular part.

[0020] The said segment under the neck includes an intermediate section, between the convex upper section and the substantially semi-truncated lower section, which forms a semi-cylindrical or semi-truncated segment and extends substantially perpendicularly to the plane of the shoulder.

[0021] The said convex upper section has a radius of curvature between 0.2 and 1mm.

[0022] Preferably, said convex upper section has a radius of curvature equal to 0.5mm.

[0023] Furthermore, the upper convex section has an angular sector between 70° and 90° and, preferably, the upper convex section has an angular sector equal to 90°.

[0024] Furthermore, the lower section, which is essentially semi-conical, has a straight wall.

[0025] Preferably, the lower section is substantially hemi-truncated conical and has a concave wall.

[0026] The said concave wall of the lower section, substantially hemi-truncated cone, has a radius of curvature between 2mm and 100mm and, preferably, the concave wall of the lower section, substantially hemi-truncated cone, has a radius of curvature between 10mm and 50mm.

[0027] Furthermore, the lower section, substantially hemi-truncated cone, extends over a height of between 1.5mm and 4.5mm and, preferably, the lower section (9), substantially hemi-truncated cone, extends over a height of 4mm.

[0028] In addition, the lower section forms an angle between 1° and 40° with the vertical axis of revolution of each hemi-annular part and, preferably, the lower section forms an angle between 10° and 30° with the vertical axis of revolution of each hemi-annular part.

[0029] Preferably, the lower section forms an angle of 15° with the vertical axis of revolution of each hemi-annular part.

[0030] Furthermore, the intermediate section which forms a semi-cylindrical segment extends over a height of between 0.1mm and 1.5mm and, preferably, the intermediate section which forms a semi-cylindrical segment extends over a height of 1mm.

[0031] Another object of the invention relates to a mold for manufacturing a container by blowing or stretch-blowing a plastic blank, said mold comprising at least one mold bottom suitable for being mounted movably in a side wall which defines a cavity in the impression of a part of the container, said side wall comprising two half-molds each defining a half-impression of the body of the container and mounted in rotation relative to each other, between a so-called open position, in which the half-molds are angularly separated from each other and the mold bottom is lowered relative to the half-molds to allow the introduction of the blank and the evacuation of the formed container, and a so-called closed position, in which the half-molds are applied against each other and trap the mold bottom between them to thus form the cavity and define the total impression of the container to be formed;said mold is remarkable in that each half-mold is shaped, at its upper end, to form a semi-annular part of the neck ring according to the invention.

[0032] Other advantages and features will become clearer from the following description of several embodiments, given by way of non-limiting examples, of the neck ring according to the invention, with reference to the attached drawings in which:

[0033] is a perspective view of a semi-annular portion of the neck ring according to the invention,

[0034] is a partial radial cross-sectional view of a hemi-annular portion of the neck ring according to the invention,

[0035] is a partial radial cross-sectional view of a hemi-annular portion of the neck ring according to the invention, with a preform bearing on said neck ring,

[0036] is a partial radial cross-sectional view of a semi-annular portion of an embodiment of the neck ring according to the invention, with a preform bearing on said neck ring,

[0037] is a partial radial cross-sectional view of a hemi-annular portion of a second embodiment of the neck ring according to the invention, with a preform bearing on said neck ring,

[0038] is a partial radial cross-sectional view of a hemi-annular portion of a final embodiment of the neck ring according to the invention, with a preform bearing on said neck ring.

[0039] is an exploded perspective view of a mold for the production of a container, said mold comprising a neck ring according to the invention. Method of embodiment of the invention

[0040] In the following description of the neck ring according to the invention, the same numerical references designate the same elements. Furthermore, the different views are not necessarily drawn to scale.

[0041] Furthermore, the two semi-cylindrical parts of the mold on which the neck ring according to the invention is fixed, the blow nozzle and all the other constituent elements of the blower are not described in detail; In this regard, reference may be made to European patent EP0989931 in the name of the applicant in particular.

[0042] With reference to figures 1 to 3 on which a single hemi-annular part 1a,1b of a so-called neck ring according to the invention is shown, the neck ring being made up of two hemi-annular parts 1a,1b suitable for being mounted at the upper end of each half-mold of a blow mold, not shown in the figures, each hemi-annular part 1a,1b of said ring 1 comprising an internal hemi-circular peripheral edge forming a segment called sub-neck 2 which extends below the peripheral edge from the upper face 3 to the lower face 4 of each hemi-annular part 1a,1b, an external hemi-circular peripheral edge 5 and two diametrically opposed lateral edges 6, said lateral edges 6 connecting the ends of the external peripheral edge 5 and internal peripheral edge 2.

[0043] Each hemi-annular part 1a,1b of said ring 1 comprising on its upper face 3 also a hemi-annular shoulder 7 plan extending along the internal peripheral edge 2, from one lateral edge 6 to the other, the collar 22 of a neck 21 of a preform 20 being able to bear on said hemi-annular shoulder 7.

[0044] Furthermore, in order to allow the fixing of each semi-annular part 1a,1b respectively on a half-mold of a mold, each semi-annular part 1a,1b has, for example, three through holes suitable for receiving screws, not shown in the figures, the upper end of each half-mold having three tapped holes extending in line with said through holes and suitable for cooperating with said screws.

[0045] Said segment under neck 2 comprises, from the upper face 3 to the lower face 4 of each hemi-annular part 1a,1b, at least one upper convex section 8 forming the edge between the shoulder 7 and all or part of the segment under neck 2, and an lower section 9 substantially hemi-truncated conical flaring out from the convex section 8 towards the lower face 4 of each hemi-annular part 1a,1b.

[0046] The said upper convex section 8 has a radius of curvature between 0.2 and 1mm and, preferably, the said upper convex section 8 has a radius of curvature equal to 0.5mm.

[0047] Furthermore, preferably, the upper convex section 8 has an angular sector equal to 90°; However, it should be noted that the upper convex section 8 may have an angular sector between 70° and 90° without going out of the scope of the invention.

[0048] Furthermore, the lower, substantially semi-conical section 9 has a straight wall. This lower section 9 forms an angle of between 1° and 40° with the vertical axis of revolution of each semi-annular portion 1a, 1b, which is substantially coaxial with the axis of revolution of the preform 20 whose collar rests on the semi-annular shoulder 7. Preferably, the lower section 9 forms an angle of between 10° and 30° with the vertical axis of revolution of each semi-annular portion 1a, 1b. Preferably, the lower section 9 forms an angle of 15° with the vertical axis of revolution of each semi-annular portion 1a, 1b.

[0049] Furthermore, the lower section 9, substantially hemi-truncated conical, extends over a height of between 1.5mm and 4.5mm and, preferably, the lower section 9, substantially hemi-truncated conical, extends over a height of 4mm.

[0050] According to a first variant of the embodiment, with reference to the, the neck ring is made up, in the same way as before, of two hemi-annular parts 1a,1b suitable for being mounted at the upper end of each half-mold of a blow mold, each hemi-annular part 1a,1b of said ring 1 comprising an internal hemi-circular peripheral edge forming a segment called sub-neck 2 which extends below the peripheral edge from the upper face 3 to the lower face 4 of each hemi-annular part 1a,1b, an external hemi-circular peripheral edge 5 and two diametrically opposed lateral edges 6, said lateral edges 6 connecting the ends of the external peripheral edge 5 and internal peripheral edge 2.

[0051] Each hemi-annular part 1a,1b of said ring 1 comprising on its upper face 3 also a hemi-annular shoulder 7 plan extending along the internal peripheral edge 2, from one lateral edge 6 to the other, the collar 22 of a neck 21 of a preform 20 being able to bear on said hemi-annular shoulder 7.

[0052] Furthermore, in order to allow the fixing of each semi-annular part 1a,1b respectively on a half-mold of a mold, each semi-annular part 1a,1b has three through holes suitable for receiving screws, not shown in the figures, the upper end of each half-mold having three tapped holes extending in line with said through holes and suitable for cooperating with said screws.

[0053] Said segment under neck 2 comprises, from the upper face 3 to the lower face 4 of each hemi-annular part 1a,1b, at least one upper convex section 8 forming the edge between the shoulder 7 and all or part of the segment under neck 2, and an lower section 9 substantially hemi-truncated conical flaring out from the convex section 8 towards the lower face 4 of each hemi-annular part 1a,1b.

[0054] The said upper convex section 8 has a radius of curvature between 0.2 and 1mm and, preferably, the said upper convex section 8 has a radius of curvature equal to 0.5mm.

[0055] Furthermore, preferably, the upper convex section 8 has an angular sector equal to 90°; However, it should be noted that the upper convex section 8 may have an angular sector between 70° and 90° without going out of the scope of the invention.

[0056] This embodiment differs from that previously described in that the lower section 9, which is substantially hemi-truncated conical, has a concave wall.

[0057] The said concave wall of the lower section 9, substantially hemi-truncated conical, has a radius of curvature between 2mm and 100mm and, preferably, the concave wall of the lower section 9, substantially hemi-truncated conical, has a radius of curvature between 10mm and 50mm.

[0058] Furthermore, the lower section 9, substantially hemi-truncated conical, extends over a height of between 1.5mm and 4.5mm and, preferably, the lower section 9, substantially hemi-truncated conical, extends over a height of 4mm.

[0059] In addition, the lower section 9 forms with the vertical axis of revolution of each hemi-annular part 1a,1b an angle between 1° and 40° and, preferably, the lower section 9 forms with the vertical axis of revolution of each hemi-annular part 1a,1b an angle between 10° and 30°.

[0060] Preferably, the lower section 9 forms an angle of 15° with the vertical axis of revolution of each hemi-annular part 1a,1b.

[0061] According to a second embodiment, with reference to the, the neck ring is made up, in the same way as before, of two hemi-annular parts 1a,1b suitable for being mounted at the upper end of each half-mold of a blow mold, each hemi-annular part 1a,1b of said ring 1 comprising an internal hemi-circular peripheral edge forming a segment called sub-neck 2 which extends below the peripheral edge from the upper face 3 to the lower face 4 of each hemi-annular part 1a,1b, an external hemi-circular peripheral edge 5 and two diametrically opposed lateral edges 6, said lateral edges 6 connecting the ends of the external peripheral edge 5 and internal peripheral edge 2.

[0062] Each hemi-annular part 1a,1b of said ring 1 comprising on its upper face 3 also a hemi-annular shoulder 7 plan extending along the internal peripheral edge 2, from one lateral edge 6 to the other, the collar 22 of a neck 21 of a preform 20 being able to bear on said hemi-annular shoulder 7.

[0063] Furthermore, in order to allow the fixing of each semi-annular part 1a,1b respectively on a half-mold of a mold, each semi-annular part 1a,1b has three through holes suitable for receiving screws, not shown in the figures, the upper end of each half-mold having three tapped holes extending in line with said through holes and suitable for cooperating with said screws.

[0064] Said segment under neck 2 comprises, from the upper face 3 to the lower face 4 of each hemi-annular part 1a,1b, at least one upper convex section 8 forming the edge between the shoulder 7 and all or part of the segment under neck 2, and an lower section 9 substantially hemi-truncated conical flaring out from the convex section 8 towards the lower face 4 of each hemi-annular part 1a,1b.

[0065] This embodiment differs from those previously described in that said segment under neck 2 has an intermediate section 10, between the upper convex section 8 and the lower section 9 substantially hemi-truncated cone, which forms a hemi-cylindrical segment and extends perpendicularly to the plane of the shoulder 7.

[0066] In the same way as before, said upper convex section 8 has a radius of curvature between 0.2 and 1mm and, preferably, said upper convex section 8 has a radius of curvature equal to 0.5mm.

[0067] Furthermore, preferably, the upper convex section 8 has an angular sector equal to 90°; However, it should be noted that the upper convex section 8 may have an angular sector between 70° and 90° without going out of the scope of the invention.

[0068] Furthermore, the lower, substantially semi-conical section 9 has a straight wall. This lower section 9 forms an angle of between 1° and 40° with the vertical axis of revolution of each semi-annular portion 1a, 1b, which is substantially coaxial with the axis of revolution of the preform 20 whose collar rests on the semi-annular shoulder 7. Preferably, the lower section 9 forms an angle of between 10° and 30° with the vertical axis of revolution of each semi-annular portion 1a, 1b. Preferably, the lower section 9 forms an angle of 15° with the vertical axis of revolution of each semi-annular portion 1a, 1b.

[0069] The said intermediate section 10 which forms a semi-cylindrical segment extends over a height between 0.1mm and 1.5mm and, preferably, the intermediate section 10 which forms a semi-cylindrical segment extends over a height of 1mm.

[0070] Alternatively, said intermediate section 10 may form a semi-truncated conical segment. In this case, said intermediate section 10 will form with the vertical axis of revolution of each hemi-annular part 1a,1b, which is substantially coaxial with the axis of revolution of the preform 20 whose collar rests on the hemi-annular shoulder 7, an angle of between 1° and 40° and, preferably, the intermediate section will form with the vertical axis of revolution of each hemi-annular part 1a,1b an angle of between 10° and 30°; However, said intermediate section 10 will form with the vertical axis of revolution of each hemi-annular part 1a,1b an angle less than the angle formed by the lower section 9.

[0071] According to a third and final embodiment, with reference to the, the neck ring is made up, in the same way as before, of two hemi-annular parts 1a,1b suitable for being mounted at the upper end of each half-mold of a blow mold, each hemi-annular part 1a,1b of said ring 1 comprising an internal hemi-circular peripheral edge forming a segment called sub-neck 2 which extends below the peripheral edge from the upper face 3 to the lower face 4 of each hemi-annular part 1a,1b, an external hemi-circular peripheral edge 5 and two diametrically opposed lateral edges 6, said lateral edges 6 connecting the ends of the external peripheral edge 5 and internal peripheral edge 2.

[0072] Each hemi-annular part 1a,1b of said ring 1 comprising on its upper face 3 also a hemi-annular shoulder 7 plan extending along the internal peripheral edge 2, from one lateral edge 6 to the other, the collar 22 of a neck 21 of a preform 20 being able to bear on said hemi-annular shoulder 7.

[0073] Furthermore, in order to allow the fixing of each semi-annular part 1a,1b respectively on a half-mold of a mold, each semi-annular part 1a,1b has three through holes suitable for receiving screws, not shown in the figures, the upper end of each half-mold having three tapped holes extending in line with said through holes and suitable for cooperating with said screws.

[0074] Said segment under neck 2 comprises, from the upper face 3 to the lower face 4 of each hemi-annular part 1a,1b, at least one upper convex section 8 forming the edge between the shoulder 7 and all or part of the segment under neck 2, and an lower section 9 substantially hemi-truncated conical flaring out from the convex section 8 towards the lower face 4 of each hemi-annular part 1a,1b.

[0075] In the same way as the second embodiment of the neck ring according to the invention previously described, said sub-neck segment 2 comprises an intermediate section 10, between the convex upper section 8 and the substantially hemi-truncated lower section 9, which forms a hemi-cylindrical segment and extends perpendicularly to the plane of the shoulder 7.

[0076] In the same way as before, said upper convex section 8 has a radius of curvature between 0.2 and 1mm and, preferably, said upper convex section 8 has a radius of curvature equal to 0.5mm.

[0077] Furthermore, preferably, the upper convex section 8 has an angular sector equal to 90°; However, it should be noted that the upper convex section 8 may have an angular sector between 70° and 90° without going out of the scope of the invention.

[0078] This embodiment differs from that previously described with reference to the fact that the lower section 9, substantially hemi-truncated conical, has a concave wall.

[0079] The said concave wall of the lower section 9, substantially hemi-truncated cone, has a radius of curvature between 2mm and 50mm and, preferably, the concave wall of the lower section 9, substantially hemi-truncated cone, has a radius of curvature between 3mm and 10mm.

[0080] Furthermore, the lower section 9, substantially hemi-truncated conical, extends over a height of between 1.5mm and 4.5mm and, preferably, the lower section 9, substantially hemi-truncated conical, extends over a height of 4mm.

[0081] In addition, the lower section 9 forms with the vertical axis of revolution of each hemi-annular part 1a,1b an angle between 1° and 40° and, preferably, the lower section 9 forms with the vertical axis of revolution of each hemi-annular part 1a,1b an angle between 10° and 30°.

[0082] Preferably, the lower section 9 forms an angle of 15° with the vertical axis of revolution of each hemi-annular part 1a,1b.

[0083] The said intermediate section 10 which forms a semi-cylindrical segment extends over a height between 0.1mm and 1.5mm and, preferably, the intermediate section (10) which forms a semi-cylindrical segment extends over a height of 1mm.

[0084] Alternatively, said intermediate section 10 may form a semi-truncated conical segment. In this case, said intermediate section 10 will form with the vertical axis of revolution of each hemi-annular part 1a,1b, which is substantially coaxial with the axis of revolution of the preform 20 whose collar rests on the hemi-annular shoulder 7, an angle of between 1° and 40° and, preferably, the intermediate section will form with the vertical axis of revolution of each hemi-annular part 1a,1b an angle of between 10° and 30°; However, said intermediate section 10 will form with the vertical axis of revolution of each hemi-annular part 1a,1b an angle less than the angle formed by the lower section 9.

[0085] In accordance with all the embodiments described above, the neck ring according to the invention is mounted removably at the upper end of the half-molds of a mold of a blow molding machine; However, the hemi-annular parts of the neck ring and the respective half-molds may be monobloc without going out of the scope of the invention.

[0086] In this regard, with reference to the, a molding unit 23 according to the invention is described for forming, from a blank, usually a preform, not shown in the figure, a container 1 such as a bottle or a can, for example.

[0087] The molding unit 23, referred to in the figure, comprises a mold 24 having a side wall 25 that defines a cavity 26 in the shape of a portion of the container. The mold 24 further comprises a base 27 in the shape of the base of the container, the mold 24 being made of metal, for example steel or aluminum (this term also covering aluminum alloys). The cavity 26, and ultimately the container 1, 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 25 comprises two half-molds 24A, 24B, each defining a half-imprint 28A, 28B of the body of the container and mounted in rotation relative to each other around a common axis formed by a hinge, not shown in the figures, between an open position, in which the half-molds 24A, 24B are angularly separated from each other and the bottom of the mold 27 is lowered relative to the half-molds 24A, 24B to allow the introduction of the blank and the evacuation of the formed container, and a closed position, in which the half-molds 24A, 24B are applied against each other and enclose the bottom of the mold 27 between them to form the cavity 26 and define the imprint of the container to be formed.Thus, the mold base 27 is suitable for being mounted movably within the mold 24, which comprises two walls movable relative to each other and intended to form the body of the container. The movable mold base 27 pushes the plastic material constituting the container towards its opening. The half-cavities 28A, 28B of the side walls 25 and / or the mold base 27 are shaped to produce a container 1.

[0088] Each half-mold 24A, 24B is shaped, at its upper end, to form a hemi-annular part 1a and respectively 1b of the neck ring according to the invention as described above.

[0089] Incidentally, it will be noted that said sub-col 2 segment of the collar ring according to the invention, for all the variants of embodiment described above, may be interrupted on one or more certain angular segments, preferably on angular segments of the order of 1 to 5°, of its internal semicircular peripheral edge, the said angular segment(s) on which the sub-col segment is interrupted being preferably at the level of the ends of the internal semicircular peripheral edge.

[0090] Finally, it is quite clear that the examples we have just given are only particular illustrations and in no way limiting as to the fields of application of the invention.

Claims

A ring (1), referred to as the neck ring, for a blow mold, consisting of two semi-annular parts (1a, 1b), each semi-annular part (1a, 1b) of said ring (1) comprising an internal semi-circular peripheral edge forming a segment called the sub-neck (2) which extends below the peripheral edge from the upper face (3) to the lower face (4) of each semi-annular part (1a, 1b), an external semi-circular peripheral edge (5), and two diametrically opposed lateral edges (6), said lateral edges (6) connecting the ends of the external (5) and internal (2) peripheral edges, each semi-annular part (1a, 1b) of said ring (1) also comprising on its upper face (3) a flat semi-annular shoulder (7) extending along the internal peripheral edge (2), from one lateral edge (6) to the other, the collar (22) of a neck (21) of a preform (20) being capable of bearing on said shoulder (7), characterized in that said segment under the neck (2) comprises,from the upper face (3) to the lower face (4) of each hemi-annular part (1a,1b), at least one so-called upper convex section (8) forming the ridge between the shoulder (7) and all or part of the sub-neck segment (2), and a so-called lower section (9) substantially hemi-truncated conical flaring out from the convex section (8) towards the lower face (4) of each hemi-annular part (1a,1b). Neck ring according to claim 1 characterized in that said sub-neck segment (2) comprises an intermediate section (10), between the upper convex section (8) and the lower section (9) substantially hemi-truncated conical, which forms a hemi-cylindrical or hemi-truncated conical segment and extends substantially perpendicularly to the plane of the shoulder (7). Neck ring according to any one of claims 1 or 2 characterized in that the upper convex section (8) has a radius of curvature between 0.2 and 1mm. Collar ring according to claim 3 characterized in that the convex upper section (8) has a radius of curvature equal to 0.5mm. Neck ring according to any one of claims 3 or 4 characterized in that the upper convex section (8) has an angular sector between 70° and 90°. Collar ring according to claim 5 characterized in that the upper convex section (8) has an angular sector equal to 90°. Neck ring according to any one of claims 1 to 6 characterized in that the lower section (9) substantially hemi-truncated cone has a straight wall. Neck ring according to any one of claims 1 to 6 characterized in that the lower section (9) substantially hemi-truncated conical has a concave wall. Neck ring according to claim 8 characterized in that the concave wall of the lower section (9) substantially hemi-truncated cone has a radius of curvature between 2mm and 100mm. Neck ring according to claim 9 characterized in that the concave wall of the lower section (9) substantially hemi-truncated cone has a radius of curvature between 10mm and 50mm. Neck ring according to any one of claims 7 to 10 characterized in that the lower section (9) substantially hemi-truncated cone extends over a height between 1.5mm and 4.5mm. Neck ring according to claim 11 characterized in that the lower section (9) substantially hemi-truncated conical extends over a height of 4mm. Neck ring according to any one of claims 7 to 12 characterized in that the lower section (9) forms with the vertical axis of revolution of each hemi-annular part (1a,1b) an angle between 1° and 40°. Neck ring according to claim 13 characterized in that the lower section (9) forms with the vertical axis of revolution of each hemi-annular part (1a,1b) an angle between 10° and 30°. Neck ring according to claim 14 characterized in that the lower section (9) forms with the vertical axis of revolution of each hemi-annular part (1a,1b) an angle of 15°. Neck ring according to any one of claims 2 to 15 characterized in that the intermediate section (10) which forms a semi-cylindrical segment extends over a height between 0.1mm and 1.5mm. Neck ring according to claim 16 characterized in that the intermediate section (10) which forms a semi-cylindrical segment extends over a height of 1mm. Mold (24) for manufacturing a container (1) by blow molding or stretch-blowing a plastic blank, said mold (24) comprising at least one mold base (27) movably mounted in a side wall (25) which defines a cavity (26) in the shape of a portion of the container (1), said side wall comprising two half-molds (24A, 24B) each defining a half-cavity (28A, 28B) of the body (2) of the container (1) and mounted to rotate relative to each other, between an open position, in which the half-molds (24A, 24B) are angularly separated from each other and the mold base (27) is lowered relative to the half-molds (24A, 24B) to allow the introduction of the blank and the evacuation of the formed container (1), and a closed position, in which the half-molds (24A,24B) are applied against each other and trap the mold base (27) between them to form the cavity (26) and define the total imprint of the container (1) to be formed, characterized in that each half-mold (24A, 24B) is shaped, at its upper end, to form a semi-annular part (1a) and respectively (1b) of the neck ring according to any one of claims 1 to 17.

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