Mold for tire having a removable annular insert

Abstract

A mold for vulcanizing and molding a tire, the tire having a tread delimited by two sidewalls, at least one of which is provided with a complex protuberance, the mold having a ring for molding the tread of the tire and two shells for molding the sidewalls, the mold having an annular insert that separates the mold into at least two portions, namely a ring portion and a shell portion in the radially lower region of the sidewalls, the insert having two adjacent concentric elements that are intended to mold the complex protuberance, namely a radially outer element associated with the ring, and a radially inner element associated with the shell.

Claims

1. A mold for vulcanizing and molding a tire, the tire comprising a tread delimited by two sidewalls, at least one of the sidewalls having a complex protuberance, the mold including a ring for molding the tread of the tire and two shells for molding the sidewalls, the mold including an annular insert, wherein the insert separates the mold into at least two portions, namely a ring portion and a shell portion in a radially lower region of the sidewalls, the insert having two adjacent concentric elements for molding the complex protuberance, namely a radially outer element associated with the ring, and a radially inner element associated with the shell.

2. The mold according to claim 1, wherein the insert comprises a concentric groove, having an interface region between two adjacent concentric elements that passes through one of the edges of the groove.

3. The mold according to claim 2, wherein the groove includes a profile with a distal region followed by a narrower connection region between the protuberance and the sidewall of the tire.

4. The mold according to claim 1, wherein one of the two adjacent concentric elements is movable radially outwards with the ring of the mold during demolding.

5. The mold according to claim 1, wherein one of the two adjacent concentric elements is movable axially outwards with the shell of the mold during demolding.

6. The mold according to claim 2, wherein the insert is formed from a plurality of insert parts that are positioned one after another to form an annulus.

7. The mold according to claim 6, wherein at least one insert part is produced by laser sintering, the insert part having all or part of the groove in the insert.

8. The mold according to claim 2, wherein the groove is interrupted at regular intervals by projections that are distributed angularly around the circumference of the insert.

9. The mold according to claim 8, wherein the projections extend radially inwards from one of the two adjacent concentric elements to windows having corresponding shapes and dimensions that are provided on the element in line with the projections.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of embodiments of the invention will become apparent from the following description, given by way of nonlimiting example, with reference to the attached drawings, in which:

(2) FIGS. 1A and 1B show examples of complex protuberances for tire sidewalls;

(3) FIG. 2 schematically shows a view in cross section in a meridian plane of a first example of a part of a mold according to an embodiment of the invention;

(4) FIG. 3 schematically shows a view in cross section in a meridian plane of a second example of a part of a mold according to an embodiment of the invention;

(5) FIG. 4 schematically shows a perspective view of an example of an annular insert suitable for the mold in FIG. 2 and produced in a plurality of parts;

(6) FIG. 5 schematically shows one of the pans of the insert in FIG. 4;

(7) FIG. 6 schematically shows one of the parts of the insert in FIG. 4 with the two portions separated.

(8) In the following description, elements which are substantially identical or similar will be denoted by identical references.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

(9) Definitions

(10) A tyre means all types of resilient tread whether or not it is subjected to an internal pressure.

(11) The tread of a tyre means a quantity of rubber compound delimited by lateral surfaces and by two main surfaces, one of which is intended to come into contact with a road surface when the tyre is running.

(12) The sidewall of a tyre means a lateral surface of the tyre, said surface being disposed between the tread of the tyre and a bead of this tyre.

(13) The bead of a tyre means a part of the tyre that is intended to be seated on a wheel rim.

(14) A mould means a collection of separate moulding elements which, when brought closer together, delimit a toroidal moulding space 20 for vulcanizing and moulding a tyre.

(15) The equatorial plane means a plane perpendicular to an axis of revolution of the mould, separating this mould into two identical half-moulds.

(16) The meridian plane means a plane containing the axis of revolution of the mould.

(17) A complex protuberance means a protuberance in at least two parts, with discontinuity between the parts.

(18) FIGS. 1A and 1B illustrate examples of complex protuberances for tires. The example in FIG. 1A consists of a protuberance with two substantially perpendicular profiled elements 20 and 21 that are connected together in a T-shape.

(19) FIG. 1B shows a similar example of a protuberance, with two substantially perpendicular profiled elements 30 and 31 that are connected together in a T-shape. The profiled element 30 is provided with circumferentially distributed windows 32.

(20) As can be seen in FIGS. 2 and 3, the mold 1 according to an embodiment of the invention comprises a ring 3 intended for molding the tread of a tire and two shells 5 for molding the sidewalls. An insert 4 is mounted removably between the ring 3 and the shells 5. The insert 4 comprises two concentric elements 6 and 7 that are intended to mold a protuberance on the tire, namely a radially outer element 6 associated with the ring 3, and a radially inner element 7 associated with the shell 5. Each element is designed to be able to carry out the demolding process by moving the elements 6 and 7 as indicated by the arrows in FIGS. 2 and 3, that is to say radially outwards for the crown element 6 and axially outwards for the shell element 7.

(21) A groove 8 is provided on the sidewall side of the insert. This groove opens up the volume required to form a complex protuberance on the sidewall of the tire produced by means of this mold. The profile and the dimensions of the groove are provided as a function of those of the protuberance on the tire to be molded. The complex-protuberance groove 8 comprises a distal region or sector 81, spaced apart from the sidewall, and a connection region or sector 82 for connecting to the sidewall of the tire. In this example, the two sectors are substantially perpendicular, with a T-shaped arrangement.

(22) In these figures, both the profile and the position of the groove 8 can easily be seen. The groove 8 and the insert 4 are advantageously concentric.

(23) As shown in an exemplary embodiment in FIG. 4, the insert 4 is advantageously formed from a plurality of insert parts 4a to 4h that are aligned angularly one after another so as to form an annulus with suitable shapes and dimensions for positioning between the two mold portions separated thereby.

(24) FIGS. 5 and 6 show the groove 8 interrupted at regular intervals by projections 11 that are distributed angularly around the circumference of the insert 4. These projections 11 extend radially inwards from the element 6 to windows 12 having corresponding shapes and dimensions that are provided on the element 7 in line with the projections 11.

(25) In a variant embodiment that is not illustrated, the interface between the two insert sections produces a joining region With a contact surface. A bridge or joining element makes it possible to fix two adjacent parts of the insert together. The bridge is advantageously provided in the central region of the contact surface. In alternative embodiments, a plurality of bridges can be provided. The profile and the surface of the bridges can vary depending on the embodiment. The bridges are advantageously provided during the manufacture of the insert, in particular when the insert is produced by laser sintering. In order to change an insert part, the bridge(s) connecting the parts in question are broken or cut. Even though the parts are separable by breaking the bridges when the insert is removed from the mold, mounting in the mold, preferably with a tight fit, confers sufficient rigidity for the molding operations to be able to be carried out without risking breaking the bridges.

(26) The figures and their descriptions given above illustrate embodiments of the invention rather than limit it. In particular, various embodiments have just been described in relation to a particular example in which the groove is T-shaped.

(27) Nonetheless, it is clear to a person skilled in the art that embodiments of the invention may be extended to other alternatives in which grooves with different shapes, such as Y-shaped or -shaped grooves, etc., are provided.

(28) The verbs comprise and have do not exclude the presence of elements other than those listed in the claims.