WO2019106540A1 - Moulding element with a plurality of enlargements - Google Patents

Abstract

The invention relates to a moulding element (1) for inserting into a mould for the vulcanisation of a tyre tread, said moulding element being produced by additive manufacturing, said moulding element (1) comprising a main enlargement (4) substantially in the form of a water drop profile arranged on one of the ends of said moulding element, the main enlargement (4) being used to mould a corresponding profile groove in the tyre, said moulding element (1) comprising at least one distal secondary enlargement (5, 6) of said main enlargement (4), said secondary enlargements (5, 6) having a total volume higher than or equal to 50% of the volume of said main enlargement (4).

Description

 MOLDING ELEMENT WITH PLURALITY OF ENLARGEMENTS

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a molding element for molding a cut in a tread of a tire. The invention also relates to a set of molding elements forming a network of molding elements in a mold.

STATE OF THE PRIOR ART

FR2961741 discloses a strip for a liner of a mold for vulcanizing a tread of a tire, said strip being manufactured by selective laser melting. The sipe includes an anchor portion configured to anchor the sipe in a liner body, a molding portion configured to mold at least one cut in the tread of the tire. The lamella further comprises reinforcing means entirely present at the anchoring portion of said lamella.

[0003] The document WO2015 / 086974 relates to a molding element for molding a cutout in a tread of a tire. The molding element comprises an assembly means capable of bonding this molding element with another molding element to form a set of molding elements. This set of molding elements is intended to be reported in a mold. These molding elements are manufactured by laser sintering.

WO2016 / 200695 discloses a set of molding elements interconnected with each other. Some of the molding elements have a non-planar face. Other molding elements comprise an area provided with a teardrop-shaped enlargement. These molding elements are manufactured by additive manufacturing. In the previous examples, the manufacture by addition of material of the molding elements is relatively difficult to implement, especially when the lamella has an enlargement in the vicinity of a thin zone. Due to the internal tensions generated during the manufacturing process, the thin zone is likely to be deformed.

There is therefore a need to find a solution to obtain a set of molding elements of good mechanical strength, respecting manufacturing tolerances, which is simple and convenient to manufacture, and which allows to limit the risk of deformation .

DEFINITIONS

 By "tire" is meant all types of elastic bandages subjected to internal pressure or not.

By "tread" of a tire is meant a quantity of rubber material bounded by side surfaces and by two main surfaces, one of which is intended to come into contact with a roadway when the tire is rolling and the other is oriented towards the inside of the tire.

By "cutting in a tread" means either a fine cut also called incision or a wide cut also called groove.

By "molding element" means an element disposed in a mold adapted to make cuts in the tread of a tire. A molding element capable of making an incision in the tread is called a coverslip. A molding element adapted to make a groove in the tread is called a bead. SUMMARY OF THE INVENTION

First, a first object of the invention is to reduce the deformations of the blades with protruding and thin during their manufacture, handling and use.

A second object of the invention is to optimize the properties of thin strips while reducing the risk of deformation.

To do this, the invention provides a molding element intended to be mounted in a mold for vulcanizing a tread of a tire, said molding element being manufactured by additive manufacturing, said molding element comprising an enlargement main substantially shaped water droplet located at one end of said molding member, said main enlargement being for molding a corresponding profile groove in the tire, said molding element having one or more secondary enlargements distal of said main enlargement, said secondary enlargement having a volume greater than or equal to 50%, and more preferably greater than or equal to 75% of the volume of said main enlargement, or said secondary enlargements having a total volume greater than or equal to 50% and more preferably greater than or equal to 75%; % of the volume of said main enlargement.

The molding elements having these characteristics are less subject to deformations that may occur during the use of thin strips with large enlargement.

In an advantageous embodiment, the protrusion is both located in the anchoring zone and in the molding zone, at the interface between these two zones. The mold-molded tire provided with this arrangement exhibits improved performance with respect to sound level and water discharge. According to an advantageous embodiment, the total volume of said secondary enlargement or said secondary enlargements is less than or equal to 100% of the volume of said main enlargement. This volume corresponds to an optimal compromise allowing a good level of resistance to deformation without affecting the other properties of the lamella.

According to an advantageous embodiment, a secondary enlargement is arranged in a substantially median position of said molding element. This type of arrangement makes it possible to provide an enlargement at the level of the interface zone between the molding part and the anchoring part of the lamella when the lamella is put in place in a mold.

According to yet another advantageous embodiment, a secondary enlargement is arranged at the other end of said molding element.

In an exemplary embodiment, the shape of the section of at least one secondary enlargement is different from the shape of the section of said main enlargement.

According to another embodiment, the shapes of the sections of at least two secondary enlargements differ from one another.

According to various embodiments, the secondary enlargements may be at a distance from one another or in close proximity to each other.

All these examples make it possible to achieve a wide range of shapes and arrangements.

According to an advantageous embodiment, the molding element is a lamella. The invention also provides a mold for vulcanizing a tread of a tire, comprising a plurality of molding elements as previously described.

According to an advantageous embodiment, the mold comprises at least one molding element comprising an anchoring portion configured to anchor the molding elements in a body of said mold and a molding portion configured to mold at least one cutout in the strip. of a tire to be molded, a secondary enlargement being arranged at the interface (or junction) of said anchoring zone and said molding zone. Such an arrangement makes it possible to consolidate the anchoring of the molding element in the body of the mold.

Alternatively, at least 50% of the volume of at least one secondary enlargement extends into said molding zone. Such an arrangement makes it possible to create chamfer areas in the molded tire, thus contributing to the improvement of the performance of the tire molded by such a mold.

DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will become apparent from the following description, given by way of example, without limitation, with reference to the accompanying drawings, in which:

 - Figures 1a, 1b and 1c and 1d schematically illustrate examples of molding elements according to the invention;

 FIGS. 2a, 2b, 2c and 2d schematically illustrate examples of protrusion profiles for molding elements according to the invention;

- Figures 3 and 4 show schematically two other embodiments of molding element according to the invention. DETAILED DESCRIPTION OF THE INVENTION

In the following description, substantially identical or similar elements will be designated by identical references.

Figure 1 has a molding element 1 for molding a cut in a tread of a tire. This molding element 1 has the shape of a "water droplet" type plate comprising a main enlargement 4 or thickening, at the free end of the molding zone 3. This molding element 1 also comprises a secondary enlargement 5, of volume less than or equal to the volume of the main enlargement 4. In this example, the secondary enlargement is arranged at the interface between the anchoring zone 2 and the molding zone 3.

Figures 1b and 1c show alternative embodiments in which a second secondary expansion 6 is provided. In the example of FIG. 1b, the secondary widening 6 is housed in the anchoring zone 2, at a distance from the secondary widening 5. In the example of FIG. 1c, the secondary widening 6 is in the vicinity of secondary enlargement 5.

In all these examples, the total volume occupied by a single enlargement 5 (as in the examples of FIGS. 1a and 1d), or by a plurality of enlargements 5 and 6 (as in the examples of FIGS. 1 c) is preferably between 50% and 100% of the volume occupied by the main enlargement 4.

Figure 1 d illustrates a variant of Figure 1a, wherein the enlargement 5 has a triangular profile profile.

Examples of profiles that can make it possible to constitute a secondary enlargement are illustrated in FIGS. 2a, 2b, 2c and 2d: profile rounded (Figure 2a), triangular (Figure 2b), slot-shaped (Figure 2c), or combined (Figure 2d).

Figures 3 and 4 illustrate other embodiments in which a secondary enlargement 5 is arranged at the end of the anchoring zone 2 (example of Figure 3) or in the vicinity of the end of the anchoring zone 2 (example of FIG. 4). These embodiments provide an effective and robust anchoring of the molding element in the mold body. The height of the anchor can also be reduced, helping to make the solution more economical. The positioning of the lamella during the manufacture of the mold is facilitated by the presence of at least one protuberance at the mold body.

In the example of Figure 3, the main widening 4 and secondary 5 have identical volumes and profiles and form a symmetrical arrangement.

The molding elements are manufactured by laser sintering. Alternatively, these molding elements are manufactured by any other manufacturing process, such as foundry, machining, etc.

Claims

A molding element (1) to be attached in a mold for vulcanizing a tread of a tire, said molding element being manufactured by additive manufacturing, said molding element (1) comprising a main enlargement (4) substantially shaped water drop profile located at one end of said molding element, said main enlargement (4) being intended to mold a groove of corresponding profile in the tire, characterized in that said molding element (1) comprises a or a plurality of secondary enlargements (5, 6) spaced apart from said main enlargement (4), said secondary enlargement (5) having a volume greater than or equal to 50% of the volume of said main enlargement (4), or said secondary enlargements (5, 6) having a total volume greater than or equal to 50% of the volume of said main enlargement (4). 2. A molding element (1) according to claim 1, wherein the total volume of said secondary widening (5) or said secondary enlargements (5, 6) is greater than or equal to 75% of the volume of said main enlargement (4). 3 molding element (1) according to one of claims 1 or 2, wherein the total volume of said secondary widening (5) or said secondary enlargements (5, 6) is less than or equal to 100% of the volume of said main enlargement (4 ). 4. A molding element according to one of claims 1 to 3, wherein a secondary enlargement (5) is arranged in a substantially central position of said molding element (1). 5. A molding element according to one of claims 1 to 3, wherein a secondary enlargement (5) is arranged at the other end of said molding element (1). 6. A molding element according to any one of the preceding claims, wherein the shape of the section of at least one secondary enlargement (5) is different from the shape of the section of said main enlargement (4). 7. A molding element according to any one of the preceding claims, wherein the shapes of the sections of at least two secondary enlargements (5, 6) differ from each other. 8. A molding element according to any one of claims 1 to 7, wherein the secondary enlargements (5, 6) are spaced from each other. 9. A molding element according to any one of claims 1 to 7, wherein the secondary enlargements (5, 6) are in close proximity to each other. 10. A molding element (1) according to any one of the preceding claims, wherein the molding element (1) is a lamella. 11. Mold (10) for vulcanizing a tread of a tire, comprising a plurality of molding elements (1) according to any one of claims 1 to 10. 12. Mold according to claim 11, comprising at least one molding element provided with an anchoring portion (2) configured to anchor the molding elements (1) in a body of said mold and a molding portion (3) configured to mold at least one cut in the tread of a tire to be molded, characterized in that a secondary widening (5) is arranged at the interface of said anchoring zone (2) and said molding zone (3 ). The mold of claim 12, wherein at least 50% of the volume of at least one secondary enlargement (5) extends into said molding zone.