Process and apparatus for manufacturing tyres

Patent metadata

Field	Value
Publication number	US-9738044-B2
Application number	US-201314651126-A
Country	US
Kind code	B2
Filing date	Dec 13, 2013
Priority date	Dec 17, 2012
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

A process for building tyres provides for building a carcass sleeve around a forming drum having an application diameter and two lateral half-portions axially moveable relative to each other. The carcass sleeve includes at least one carcass ply coaxially engaged around each of the axially opposite end flaps thereof to an annular anchoring structure defining a fitting diameter smaller than the application diameter. The building of the carcass sleeve includes: applying and stopping a leading end of a semi-finished product in the form of a continuous strip cut to size against a continuous surface of the forming drum; winding the semi-finished product in the form of a continuous strip cut to size circumferentially around the forming drum; and joining a trailing end of the semi-finished product to the leading end at said continuous surface. The continuous surface is extended only partly around the forming drum. The semi-finished product, except for the leading end and the trailing end, is laid against a discontinuous circumferential surface of the forming drum adjacent to the continuous surface and belonging to the two lateral half-portions.

First claim

The invention claimed is:

1. A process for manufacturing a tyre comprising: building a carcass sleeve around a forming drum having an application diameter, said carcass sleeve comprising a carcass ply with axially opposite end flaps, each of which is coaxially engaged to an annular anchoring structure defining a fitting diameter smaller than the application diameter, wherein the building of said carcass sleeve comprises:
providing the drum so that it has two lateral half-portions which are axially moved relative to one another, each lateral half-portion comprising a circumferentially continuous axially outer shoulder and a plurality of teeth which are axially extended from this shoulder towards the other half-portion, the teeth of each half-portion being circumferentially alternating relative to those of the other half-portion so that the teeth of the half-portions mesh with each other and the teeth of each half-portion are slidably inserted in alternating sequence between the teeth belonging to the other half-portion, free spaces which remain by the end of each of the teeth of one of the half-portions and by the two adjacent teeth of the other half-portion providing openings in a discontinuous surface of the drum,
wherein the drum is further provided with a single plate extending only partly around the circumference of the drum and arranged radially more external relative to the half-portions and providing a continuous surface on the drum such that the continuous surface covers a section of the half-portions and the half-portions slide against the radial interior of the plate as they move axially with respect to one another, the use of the single plate causing the radially peripheral surface of the drum to have the same peripheral diameter, except only for a portion limited to the continuous surface of the drum,
wherein the step of building the carcass sleeve comprises applying and retaining a leading end of a semi-finished product, which was cut to size from a continuous strip, against the continuous surface of the plate, then rotating the drum so that the cut semi-finished product is wound around the drum until a trailing end of the semi-finished product becomes superimposed on the leading end over the plate while the remaining circumferential portion of the semi-finished product, between the leading and trailing ends, is laid on a central portion of the two lateral half-portions, against the openings;
after superimposing the leading and trailing ends, pressing the trailing end on the leading end and against the forming drum for mutually joining said leading and trailing ends while the leading end rests against the plate; and
wherein the lateral half-portions are radially contractible and the radial position of the plate is adjusted as a function of the radial configuration of the half-portions by a radially movable structure arranged between the lateral half-portions such that the plate is always radially more external relative to the half-portions.

2. The process as claimed in claim 1 , wherein after the winding, the semi-finished product laid against the forming drum has a difference of circumferential extension between a central portion thereof and lateral portions thereof less than 2 mm.

3. The process as claimed in claim 1 , wherein after the winding, the semi-finished product laid against the forming drum has a difference of circumferential extension between a central portion thereof and lateral portions thereof less than 1 mm.

4. The process as claimed in claim 1 , wherein after the winding, the leading end and the trailing end of the semi-finished product laid against the forming drum have parallel end edges thereof.

5. The process as claimed in claim 1 , comprising:
exerting a substantially uniform pressure along an entire axial extension of the trailing end and the leading end.

6. The process as claimed in claim 1 , wherein during an application of said carcass ply on the forming drum, the end flaps of said carcass ply are supported on respective support surfaces extending on a continuation of the two lateral half-portions of the forming drum.

7. The process as claimed in claim 6 , further comprising: removing the support surfaces before turning up each of the axially opposite end flaps of the carcass ply around a respective one of the annular anchoring structures.

8. The process as claimed in claim 1 , comprising positioning an external sleeve comprising at least one belt structure in a coaxially centered position around the carcass sleeve built on the forming drum.

9. The process as claimed in claim 8 , comprising shaping the carcass sleeve according to a toroidal configuration to achieve application thereof against a radially internal surface of the external sleeve.

10. The process as claimed in claim 9 , wherein the shaping of the carcass sleeve comprises: mutually approaching said two lateral half- portions of the forming drum.

11. The process as claimed in claim 9 , wherein the shaping of the carcass sleeve comprises: introducing a fluid through the discontinuous surface.

12. The process as claimed in claim 8 , wherein the forming drum is transferred from a building station to a shaping station before the positioning of the external sleeve.

13. The process as claimed in claim 1 , wherein said semi-finished product is a liner.

14. The process as claimed in claim 1 , wherein said semi-finished product is a complex comprising a liner, an under-liner and elongated anti-abrasive elements.

Assignees

• Pirelli

Inventors

• Marchini Maurizio
• Mancini Gianni

Classifications

• B29D30/3042

  by feeding cut-to-length pieces in a direction perpendicular to the drum axis and in a plane parallel to the drum axis, and placing the pieces side-by-side to form an annular element · CPC title

• B29D30/08

  Building tyres · CPC title

• B29D30/244 Primary

  for manufacturing substantially cylindrical tyre components with cores or beads, e.g. carcasses (mechanisms for folding layers around cores or blads per se B29D30/32) · CPC title

• B29D30/24 Primary

  Drums · CPC title

• B29D2030/2664

  the drum comprising at least two portions that are axially separable, e.g. the portions being supported by different shafts, e.g. in order to facilitate the insertion of the beads · CPC title