Process and vulcanising mould for manufacturing tyres for vehicle wheels

Patent metadata

Field	Value
Publication number	US-10035314-B2
Application number	US-201414781568-A
Country	US
Kind code	B2
Filing date	Mar 31, 2014
Priority date	Apr 10, 2013
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

Abstract

A green tire has a symmetric profile in radial section having a radially outer tread band, two radially inner beads and two sidewalls each extended from one edge of the tread band to one of the beads. During a molding and vulcanization treatment of the green tire, a movement is imposed to the tread band with respect to the beads along a direction parallel to a rotation axis of the tire, to obtain a molded and vulcanized tire having an asymmetric profile in radial section. A mold for vulcanizing tires for vehicle wheels is also described, having a tread wall axially asymmetric with respect to a middle line plane of the mold.

First claim

The invention claimed is:

1. A process for manufacturing tyres for vehicle wheels, comprising:
building a green tyre having a symmetric profile in radial section, having a radially outer tread band, two radially inner beads and two sidewalls each being extended from one edge of the tread band to one of the beads;
moulding and vulcanising the green tyre; and
during moulding, imposing a movement to the tread band with respect to the beads along a direction parallel to a rotation axis of the tyre,
wherein, during moulding, imposing a movement to the tread band causes the tread band to be axially offset with respect to the beads and with respect to a middle line plane of the tyre,
wherein, during vulcanisation, the offset of the tread band with respect to the beads is retained with respect to the middle line plane of the tyre,
wherein, during vulcanisation, a middle circumferential line of the tread band is axially offset by a predefined distance with respect to the middle line plane of the tyre, and
wherein a moulded and vulcanised tyre having an asymmetric profile in radial section is obtained.

2. The process as claimed in claim 1 , also comprising introducing the green tyre in a moulding cavity, wherein the green tyre, before being introduced in the moulding cavity, is symmetric with respect to its own middle line plane orthogonal to the rotation axis of the tyre.

3. The process as claimed in claim 1 , also comprising closing the green tyre in a moulding cavity, wherein said green tyre, closed in the moulding cavity, is symmetric with respect to its own middle line plane orthogonal to the rotation axis of the tyre.

4. The process as claimed in claim 1 , wherein the movement of the tread band is actuated simultaneously with a closure action of the green tyre inside a moulding cavity.

5. The process as claimed in claim 1 , wherein the tyre is vulcanised in a moulding cavity having a plurality of sectors operating against the tread band, two bead seats operating against the beads of the tyre, and two sidewall plates each extending between said plurality of sectors and one of the bead seats.

6. The process as claimed in claim 5 , wherein said plurality of sectors is maintained spaced apart from the tread band during the movement of the tread band with respect to the beads.

7. The process as claimed in claim 5 , wherein the movement of the tread band with respect to the beads is carried out in absence of mechanical interferences between said plurality of sectors and the tread band.

8. The process as claimed in claim 1 , also comprising fixing the positioning of the tread band inside the mould during the movement of the tread band with respect to the beads.

9. The process as claimed in claim 8 , wherein said fixing action is carried out by a gripping action exerted by a plurality of sectors against the tread band.

10. The process as claimed in claim 5 , wherein the green tyre is closed in the moulding cavity by:
axially approaching the bead seats against the respective beads of the tyre; and
centripetally approaching at least a part of said plurality of sectors, in order to come into contact with the tread band of the tyre.

11. The process as claimed in claim 10 , wherein the movement of the tread band with respect to the beads is actuated simultaneously with the action of axially approaching the bead seats.

12. The process as claimed in claim 5 , wherein the green tyre is closed in the moulding cavity by:
axially approaching the sidewall plates against the respective sidewalls of the tyre; and
centripetally approaching at least a part of said plurality of sectors, in order to come into contact with the tread band of the tyre.

13. The process as claimed in claim 12 , wherein the movement of the tread band with respect to the beads is actuated simultaneously with the action of axially approaching the sidewall plates.

14. The process as claimed in claim 1 , wherein the movement of the tread band is at least partially actuated simultaneously with an action of pressing the green tyre against inner surfaces of the moulding cavity.

15. The process as claimed in claim 5 , wherein said plurality of sectors in its entirety defines a tread wall whose tread wall geometric conformation is a copy of a tread band geometric conformation of the vulcanised tyre.

Assignees

• Pirelli

Inventors

• Losi Piero

Classifications

• B29D30/0629

  with radially movable sectors · CPC title

• B29D30/08

  Building tyres · CPC title

• B29D30/0605 Primary

  Vulcanising presses characterised by moulds integral with the presses having radially movable sectors · CPC title

• B60C3/06

  asymmetric · CPC title

• B29L2030/003

  Plies; Breakers · CPC title