EP3352962A1

EP3352962A1 - Method for manufacturing a moulding element of a mould for vulcanizing a tyre

Info

Publication number: EP3352962A1
Application number: EP16784229.3A
Authority: EP
Inventors: Stéphane BOLLECKER; Marcin BANCEWICZ; Thong-Art SAKUD
Original assignee: Compagnie Generale des Etablissements Michelin SCA
Current assignee: Compagnie Generale des Etablissements Michelin SCA
Priority date: 2015-09-26
Filing date: 2016-09-23
Publication date: 2018-08-01
Also published as: FR3041562B1; WO2017051131A1; US20190054663A1; FR3041562A1; CN108136623A

Abstract

Method of manufacturing moulding elements (5) intended to be assembled in a mould for moulding a tread of a tyre, the method involving: a) a step of aligning, on a base support (4), a plurality of base elements (1); b) during the alignment step, a step of fitting at least one insert (9) between two adjacent base elements in the alignment, the insert comprising an external part (10) projecting from the two base elements in an opposite direction to the base support (4) and an internal part (11) separating the two base elements; c) a step of obtaining an intermediate support (3); d) a step of obtaining at least two moulding elements (5), the two moulding elements (5) being separated by the internal part (11) of the insert (9).

Description

METHOD OF MANUFACTURING A MOLDING ELEMENT OF A MOLD FOR THE VULCANIZATION OF A TIRE

TECHNICAL FIELD OF THE INVENTION [0001] The invention relates to a method for manufacturing molding elements for molds for molding tires with a tread comprising a circumferential arrangement of tread patterns.

STATE OF THE PRIOR ART

The manufacture of tires in large series uses a particularly complex and expensive industrial process, involving many machines, complex processes and multiple preparatory phases. The complexity of the process results in high rigidity, reducing the possibility of configuration or layout changes after the establishment of a production line. This rigidity is particularly applicable to the molds provided for the vulcanization and molding phases. However, more and more vehicles are produced in limited series, with features that make these vehicles unique and attractive compared to those manufactured in larger series. Among the specificities offered, tires are often one of the strong points of demarcation. There is therefore a significant and growing need to improve the flexibility of tire manufacturing processes. In addition, there is a growing need to simplify and facilitate the preparation of tires with attractive specificities. The application FR 3014351 discloses a method of manufacturing molding elements for molds for molding tires provided with a tread comprising a circumferential arrangement of patterns of sculpture, to partially meet these objectives.

This process comprises:

a) a step of aligning a plurality of base pads of flexible material to form a tread circumference base portion;

b) a step of generating, from the tread circumference base portion, an intermediate support, corresponding to the tread circumference portion; c) a step of obtaining a raw molding element from the intermediate support;

each of the basic seals corresponding to a pattern of the circumferential arrangement of the tread of the tire to be molded.

According to this method, the raw molding element must be separated into a plurality of sections that can be used for subsequent moldings. The separation step is particularly complex and time-consuming because it involves cuts for each of the many sections, under high precision conditions, without affecting the quality of the elements obtained.

There is therefore a need for a simpler process, cheaper, and faster, preserving the quality of the parts obtained.

SUMMARY OF THE INVENTION

An object of the invention is to provide a manufacturing method for facilitating the modification of the visual characteristics of the tires. Another object of the invention is to provide a manufacturing method for reducing the loss of raw materials during changes in the visual characteristics of the tires.

Yet another object is to provide a method for optimizing the manufacture of tires, particularly in the mold preparation phase. To do this, the invention provides a method of manufacturing molding elements to be assembled in a mold for molding a tread of a tire, each molding element being obtained by the use of a basic element of flexible material, the method comprising:

a) a step of aligning, on a base support, a plurality of basic elements;

b) during the alignment step, a step of placing at least one insert between two adjacent base elements in alignment, the insert having an outer portion projecting from the two elements of base in a direction opposite to the base support and an inner portion separating the two base members;

c) a step of obtaining an intermediate support from the plurality of aligned base elements, said intermediate support enclosing the outer portion of the insert;

d) a step of obtaining, from the intermediate support, at least two molding elements, the two molding elements being separated by the inner part of the insert.

With the method according to the invention, the molding elements are obtained more simply, faster and more economically than in the method used to date. The many cuts to be made for each molding element are replaced by a simple step of separating the elements already molded individually due to the presence of the inserts. This method allows a great flexibility in the configuration of the molds. Because each base liner corresponds to a pattern of the tread of the tire to be molded, the resultant molding elements benefit from this same characteristic. By using molding elements with different patterns, one can adapt or modify the architecture of the tread without having to replace the entire mold. Depending on the needs of the types of molds and the quantities required for each type of molding elements, the quantities produced for each type are easily adjustable since the intermediate mold makes it possible to house the basic fittings according to the production needs of these different types of molds. molding elements, favoring for example one type rather than another. The simultaneous manufacture of a plurality of molding elements optimizes the manufacturing process, with a simplification of the tooling and a reduction of material losses.

The intermediate mold makes it possible to group the basic fittings in a simple, fast way, with precise positioning. The molding step of the intermediate support is therefore optimized, with optimization of the overall space and a particularly advantageous embodiment accuracy.

A single molding phase therefore allows the production of several sectors or molding elements.

According to an advantageous embodiment, the inserts are steel plates. Advantageously, the steel inserts are subjected to a conformation step before their insertion. According to another advantageous embodiment, the inserts are textile webs. Such an embodiment, with flexible textile plies, provides great ease for the arrangement of the plies with an infinity of different profiles, with a greatly facilitated implementation.

The textile webs can be woven or entangled. Advantageously, the textile plies have a sufficient density to prevent any interpenetration in the neighboring areas of intermediate support or molding element separated by said plies. Textiles are advantageously used with compositions such as alkaline earth silicate fibers.

It is advantageous to use inserts having a high temperature resistance, at least up to substantially 700 ° C, and preferably water-resistant inserts.

Each of the inserts is preferably substantially rigid in the normal direction to the main plane of said insert.

Furthermore, it is advantageous to use chemically neutral inserts relative to the material of the molding element.

Advantageously, the inserts have a thickness of 0.2 to 4 mm (for the textile) and greater than 0.2 mm for the metal.

According to an advantageous variant, during the stage of introduction of the inserts, there is provided a step of leaving a thin layer of molding element under at least a portion of the inserts, so as to create connections between the neighboring areas of molding element. This embodiment makes it possible to provide a raw molding element with a plurality inter-unitary elements interconnected, easy to handle because it is in one block before the elements are permanently separated. In addition, the step of removing the intermediate support is facilitated because of the connection between the multiple unitary elements.

According to another embodiment, the molding elements comprise at least one material thickness and are machined for final shaping of the dimensions before assembly in the mold. This step optimizes the precision of the molding elements.

According to another embodiment, the intermediate support is made of destructible material.

According to yet another embodiment, the raw molding element is made of reusable material.

According to yet another advantageous embodiment, the method comprises a preliminary step of producing a base matrix (or template) for obtaining corresponding basic liners.

According to yet another advantageous embodiment, the method comprises a step of removing the inserts by destruction with water at high pressure. In another variant, the base liner is made of silicone, and preferably of silastene. This gives the possibility of reusing the base trim for other productions.

The invention also provides a mold comprising a support on which a plurality of molding elements obtained by the previously described method are circumferentially aligned. The invention also provides a tire obtained by molding and vulcanization using a mold having a plurality of gaskets / circumferential sectors obtained by the previously described manufacturing method.

In an advantageous variant, the tire comprises a tread provided with a plurality of circumferentially alternating patterns, each of the patterns of the circumferential arrangement corresponding to a pattern of a base liner used in the method of the invention. manufacture described above.

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:

Figure 1 shows schematically the main elements for performing an intermediate support from an alignment of basic elements, with insertion of separation inserts; FIG. 2 is a schematic representation in perspective of an example of a basic element; Figure 3a is a diagrammatic representation in elevation of an intermediate support cooperating with a plurality of base members, inserts extending both in the intermediate support and between the base elements; Figure 3b is a perspective view of the assembly shown in Figure 3a; Figure 4 illustrates a schematic perspective representation of an intermediate support example in which the inserts are partially encompassed after removal of the base elements; Figure 5 illustrates a schematic perspective representation of an exemplary raw molding element, in which the inserts are partially enclosed, after removal of the intermediate support; FIG. 6 illustrates a schematic representation in perspective of an exemplary molding element after separation.

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

DETAILED DESCRIPTION OF THE INVENTION DEFINITIONS

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

By "tread" of a tire is meant a quantity of rubber material delimited by lateral surfaces and by two main surfaces, one of which is intended to come into contact with a roadway when the tire is rolling.

By "destructible material" means a material easy to remove after molding of the intended element, by destruction, such as by breaking or cutting.

By "reusable material" is meant a material whose mechanical characteristics allow reuse repeatedly in an industrial tire molding process.

FIG. 2 illustrates an example of a basic element 1 made of flexible material such as silicone, and preferably silastene. The base member has a substantially elongate profile, with at each of its ends a preferably dovetail-shaped attachment member. As shown in Figure 1, a plurality of base elements 1 are aligned transversely against each other on a base support 4 so as to reproduce a tread portion 2. To maintain the elements of base well assembled against one another, one or more supports such as wedges, a material of higher hardness than that of the base elements are provided, for example on each side of the base elements arranged at the lateral ends.

Each base element 1 is separated from its neighbor by an insert 9 serving as a separator. The zone serving as separator is designated internal part 1 1 in what follows. This inner part 1 1 is advantageously extended towards the base support 4 up to this one. Alternatively, the inner portion is interrupted before joining the base support 4. This space without separation will be used for the molding step of the molding elements 5 to form a connection zone between the molding elements 5. In this variant, the inter-connected molding elements can for example be handled in one block before being subsequently separated. The connection zone is provided in a sufficiently fine manner that the separation between the elements is easy to achieve. The set of basic elements 1 aligned and separated by the inserts used to mold an intermediate support 3, reproducing an inverse image of the tread portion. This intermediate support 3 is advantageously made of destructible material such as plaster. Figures 3a and 3b illustrate in more detail (in elevation and in perspective) the result obtained when the intermediate support 3 is molded, and the basic elements still in place. Each of the inserts 9 has an internal part 1 1 (separating two base elements) and an outer portion 10 protruding from the base elements 1 so as to be included in the intermediate support 3. According to an exemplary embodiment, the outer portion projects at least 1 cm in average, in the length of the room.

When the basic elements 1 are removed, as shown for example in Figure 4, the inner parts 1 1 are released, and the inserts 9 are at this stage maintained by the outer portions 10. The inner parts 1 1 released will allow, in the subsequent step, delimit and separate the molding elements 5, during molding of the latter, against the intermediate support 3.

Figure 5 shows a set of molding elements 5 after molding and removal of the intermediate support 3, for example by destruction. The figure makes it possible to clearly observe the inserts 9 with the external parts 10 again free, and the internal parts 1 1 separating each of the molding elements 5. Being elements that are likely to be used many times in production phases , the molding elements 5 are made of "reusable material" such as light metal alloy, for example aluminum. This material also has the advantage of being easily moldable and machinable. In the example illustrated in Figure 5, the inner parts 1 1 of the inserts 9 extend over the entire side of the molding elements. Figure 6 shows the result of the subsequent step after removal of the inserts and separation of the individual molding elements.

The invention is not limited to the examples described and shown and various modifications can be made without departing from its scope. References used in the figures

1 Basic element

2 Tread

3 Intermediate Support

4 Basic support

5 molding element

9 Inserts

10 External part (protruding basic elements)

11 Internal part (separating two basic elements)

Claims

CLAIMS. A method of manufacturing molding elements (5) intended to be assembled in a mold for molding a tread of a tire, each molding element (8) being obtained by the use of a base element ( 1) of flexible material, the method comprising:

a) a step of aligning, on a base support (4), a plurality of base elements (1);

b) during the alignment step, a step of placing at least one insert (9) between two adjacent base elements in alignment, the insert having an outer portion (10) projecting from the two base elements in a direction opposite to the base support (4) and an inner part (11) separating the two base elements;

c) a step of obtaining an intermediate support (3) from the plurality of aligned base elements (1), said intermediate support (3) enclosing the external part (10) of the insert (9); );

d) a step of obtaining, from the intermediate support (3), at least two molding elements (5), the two molding elements (5) being separated by the inner part (11) of the insert (9). ).

2. Manufacturing process according to claim 1, characterized in that the inserts (9) are steel plates.

3. The manufacturing method according to claim 2, characterized in that the inserts (9) of steel are subjected to a shaping step before their insertion.

4. Manufacturing process according to claim 1 characterized in that the inserts (9) are textile webs.

5. Manufacturing process according to claim 4 wherein the textile webs are woven or entangled.

6. The manufacturing method according to claim 4 wherein the textile webs have a density sufficient to prevent interpenetration in the neighboring areas of intermediate support (3) or molding element (5) separated by said webs.

7. Production method according to one of the preceding claims, characterized in that the inserts (9) have a high temperature resistance, at least up to substantially 700 ° C.

8. Manufacturing process according to one of the preceding claims, characterized in that each of the inserts is substantially rigid in the normal direction to the main plane of said insert.

9. Manufacturing process according to one of the preceding claims, characterized in that the inserts (9) are water-repellent.

10. Manufacturing process according to one of the preceding claims, characterized in that the inserts (9) are chemically neutral with respect to the material of the molding element.

11. Manufacturing method according to one of claims 4 to 6, characterized in that the inserts (9) have a thickness of 0.2 to 4 mm.

12. Method according to one of the preceding claims, wherein, during the step of placing the inserts (9), there is provided a step of leaving a thin layer of molding element (5) in at least one part of the inserts, so as to create connections between the neighboring areas of molding element.

13. Method according to one of the preceding claims, comprising a step of removing the inserts by destruction with high pressure water.

14. Mold comprising a support on which a plurality of molding elements (5) obtained by the method according to one of claims 1 to 13 are circumferentially aligned.