CN-122029033-A - Method for producing a vulcanisation mould for tyres for vehicle wheels

Abstract

A method for producing a vulcanisation mould for tyres for vehicle wheels, comprising a plurality of sectors, wherein each sector comprises a moulding surface of a tread band portion of the tyre, comprises, for each sector, -imparting to at least one surface portion of said moulding surface a surface roughness by means of a numerical control apparatus (110) starting from a digital model in which said surface roughness is defined by a predetermined algorithm.

Inventors

• R. Balochino
• C. R. E. Rawiza
• A. Longqi
• D.E. Speziari

Assignees

• 倍耐力轮胎股份公司

Dates

Publication Date

20260512

Application Date

20241016

Priority Date

20231019

Claims (20)

1. 1. A method for producing a vulcanisation mould for tyres for vehicle wheels, comprising a plurality of sectors, wherein each sector comprises a moulding surface of a tread band portion of the tyre, the method comprising, for each sector: -manufacturing at least one surface portion of the molding surface with a surface roughness by means of a numerical control device (110) starting from a digital model in which the surface roughness is defined by means of a predetermined algorithm.
2. 2. The production method according to claim 1, wherein the predetermined algorithm is a berlin noise algorithm.
3. 3. A production method according to claim 1 or 2, comprising, for each sector, manufacturing a main pattern (20) of the sector, the main pattern comprising a pattern outer surface (21) representative of a negative of the molding surface.
4. 4. A production method according to claim 3, comprising, for each sector, a silicone casting on the outer surface (21) of the mould to produce a silicone overmold of the main mould, the silicone overmold comprising an inner surface of a male mould representative of the moulding surface.
5. 5. The production method of claim 4, comprising, for each sector, a gypsum casting on the inner surface of the silicone overmold to produce a gypsum overmold comprising an outer surface of a negative mold representing the molding surface.
6. 6. The production method according to claim 5, comprising, for each sector, metal casting on the outer surface of the plaster overmold to produce a metal overmold comprising an inner surface constituting the molding surface of the sector of the mold.
7. 7. The method according to claim 6, wherein the surface roughness on the at least one surface portion of the molding surface is achieved for each sector simultaneously with the manufacture of the main mold (20) or the plaster overmolded or the metal overmolded.
8. 8. The method according to claim 7, wherein, for each sector, when the surface roughness is achieved while manufacturing the main mould (20), the mould outer surface (21) comprises at least one surface portion with the surface roughness.
9. 9. The method according to claim 8, wherein the master model (20) is manufactured by 3D printing and the numerical control device (110) comprises a 3D printer controlled by the digital model to form the surface roughness as defined by the predetermined algorithm on the at least one portion of the model outer surface (21).
10. 10. The method according to claim 8, wherein the master model (20) is manufactured by means of the numerical control device (110) for each sector, which device implements a material removal or laser engraving technique on a suitable starting material block and is controlled by the digital model to form the surface roughness as defined by the predetermined algorithm on the at least one portion of the model outer surface (21).
11. 11. The method according to claim 7, wherein for each sector, when the surface roughness is achieved while manufacturing the plaster overmold, the surface roughness is achieved by implementing a material removal technique on the plaster overmold by the numerical control device (110) starting from the digital model in which the surface roughness is defined by the predetermined algorithm.
12. 12. The method according to claim 7, wherein, for each sector, when the surface roughness is achieved while manufacturing the metal overmold, the surface roughness is achieved by subjecting the metal overmold to a material removal technique or a laser engraving technique by the numerical control device (110) starting from the digital model in which the surface roughness is defined by the predetermined algorithm.
13. 13. The method of any of claims 6 to 12, comprising, for each sector, removing the plaster overmold from the metal overmold so as to achieve a mold sector with the molding surface.
14. 14. The method according to any one of the preceding claims 3 to 13, wherein the mould outer surface (21) comprises, for at least one sector, a plurality of first protrusions (22).
15. 15. The method of claims 4 and 14, wherein for the at least one segment, fabricating the silicone overmold includes forming a plurality of grooves in the inner surface of the silicone overmold at the plurality of first protrusions (22).
16. 16. The method of claim 15, comprising, for the at least one segment, inserting a plurality of second protrusions into an interior of the plurality of grooves formed in the inner surface of the silicone overmold, respectively.
17. 17. The method of claims 5 and 16, wherein for the at least one segment, gypsum casting is performed on the inner surface of the silicone overmold after inserting the second plurality of protrusions into the interior of the plurality of grooves.
18. 18. The method of claim 17, wherein for the at least one segment, fabricating the gypsum overmold comprises encapsulating the plurality of second protrusions in the outer surface of the gypsum overmold.
19. 19. The method of claims 6 and 18, wherein manufacturing the metal overmold for the at least one segment includes encapsulating the plurality of second protrusions in the inner surface of the metal overmold.
20. 20. The method of claims 13 and 19, wherein the plaster overmold is removed from the metal overmold for the at least one segment by the plurality of second protrusions still being encapsulated in the inner surface of the metal overmold.

Description

Method for producing a vulcanisation mould for tyres for vehicle wheels Technical Field The present invention relates to a method for producing a vulcanisation mould for tyres for vehicle wheels. Background Tires for vehicle wheels generally comprise a carcass structure shaped according to a substantially toroidal configuration and comprising at least one carcass ply having axially opposite ends. The axially opposite ends described above are engaged with respective annular anchoring structures, each of which is generally formed by at least one substantially circumferential annular insert (known as "bead core") on which at least one filler insert is generally applied, said filler insert tapering radially away from the axis of rotation. The annular anchoring structures are located in the areas commonly referred to as "beads". The inner diameter of the bead corresponds substantially to the so-called "fitting diameter" of the tyre on the respective mounting rim. The tire further comprises a crown structure comprising at least one belt strip in a radially external position with respect to the carcass ply, and a tread band radially external with respect to the belt strip. Longitudinal and transverse incisions are typically formed in the tread band, which are arranged to define a desired tread pattern. Between the tread band and the belt strip or strips, a so-called "underlayer" may be arranged, which underlayer is made of an elastomeric material having suitable properties in order to achieve a firm bond between the belt strip or strips and the tread band. The tyre also comprises a pair of so-called sidewalls made of elastomeric material, said sidewalls representing the axially external surface of the tyre with respect to a median plane perpendicular to the rotation axis of the tyre. For example, the sidewalls represent an axially external surface with respect to the annular anchoring structure, one or more carcass plies, one or more belt strips and possibly at least a portion of the tread band. In a "tubeless" tyre, at least one layer of elastomeric material (commonly referred to as "liner") is provided in a radially internal position with respect to the carcass ply, said layer of elastomeric material having airtight characteristics and generally extending from one bead to the other. The production cycle of the tire provides the building process of the green tire and the subsequent molding and curing processes. In particular, the green tyre building process comprises the steps of building a carcass structure, building a crown structure and shaping and assembling steps in which the carcass structure is given a toroidal shape by assembling it to the crown structure. The green tyre thus built is transferred to a moulding and vulcanisation line where a moulding and vulcanisation process is carried out, which is adapted to define the tyre structure according to the desired geometry and tread pattern. For this purpose, the green tyre is arranged in a moulding cavity defined inside the vulcanisation mould. Generally, the curing mold includes a first sidewall plate, a second sidewall plate opposite the first sidewall plate, and a crown of circumferential sectors configured to be coupled to the first sidewall plate and the second sidewall plate when the curing mold is closed for curing the green tire. The circumferential sectors surround the molding cavity and are typically provided with a plurality of shaped projections intended to create a series of grooves in the tread band suitably arranged according to the desired tread pattern. In particular, the surfaces of the circumferential sectors are shaped in such a way as to jointly reproduce the negative of the tread pattern desired for the tyre. The term "elastomeric material" is used to refer to a composite comprising at least one elastomeric polymer and at least one reinforcing filler. Such composites may also include additives such as, for example, cross-linking agents and/or plasticizers. Due to the presence of the cross-linking agent, such materials can be cross-linked by heating to form the final product. The terms "axial", "radial", "circumferential" and "circumferentially" are used with reference to the tire or to the vulcanization mold used in the tire production process. In particular, the terms "axial" and "axially" are used to refer to references/quantities arranged/measured or extended in a direction substantially parallel to the rotation axis of the tyre or vulcanisation mould. The terms "radial" and "radially" are used to indicate references/quantities arranged/measured or extended in a direction perpendicular to the rotation axis of the tyre or of the vulcanisation mould and lying in a plane comprising such rotation axis. The terms "circumferential" and "circumferentially" are used to indicate references/quantities arranged/measured or extended along a circumference developing around the rotation axis of the tyre or of the vulcanisation mould. The term "gre