Expandable forming drum, and process for building tyres

Patent metadata

Field	Value
Publication number	US-11090891-B2
Application number	US-202016806130-A
Country	US
Kind code	B2
Filing date	Mar 2, 2020
Priority date	Dec 23, 2013
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

A toroidal forming drum and a process for building tyres. The toroidal forming drum ( 23 ) is expanded within a shaped carcass sleeve ( 12 ), for supporting the carcass sleeve ( 12 ) against an abutment surface (“S”) externally provided by the forming drum ( 23 ). An elementary semi-finished product ( 54 a, 54 b ) is applied around the shaped carcass sleeve ( 12 ), by pressing the elementary semi-finished product ( 54 a, 54 b ) towards the abutment surface (“S”). The abutment surface (“S”) has circumferential rows of solid portions ( 40 ) alternated with hollow portions ( 41 ). The solid portions ( 40 ), arranged along axially opposite circumferential edges of the abutment surface (“S”), have a transverse size comprised between 10% and 60% of a transverse size presented by the solid portions ( 40 ) arranged in proximity to an axial centreline plane of the abutment surface (“S”).

First claim

The invention claimed is:

1. A process for building tyres, comprising:
building a carcass sleeve,
shaping the carcass sleeve according to a toroidal configuration to form a shaped carcass sleeve,
engaging a toroidal forming drum within the shaped carcass sleeve, for supporting the shaped carcass sleeve against a radially external abutment surface provided by the forming drum, and
applying at least one elementary semi-finished product around the shaped carcass sleeve, by pressing the at least one elementary semi-finished product towards the abutment surface;
wherein the abutment surface has circumferential rows of solid portions alternated with hollow portions; and
wherein the solid portions arranged along axially opposite circumferential edges of the abutment surface have a transverse size between 10% and 60% of a transverse size presented by the solid portions arranged in proximity to an axial centreline plane of the abutment surface.

2. The process as claimed in claim 1 , wherein the transverse size of the solid portions arranged along axially opposite circumferential edges of the abutment surface are between 20% and 50% of the transverse size presented by the solid portions arranged in proximity to the axial centreline plane of the abutment surface.

3. The process as claimed in claim 1 , wherein the hollow portions of each circumferential row are circumferentially offset with respect to the hollow portions of axially adjacent circumferential rows.

4. The process as claimed in claim 1 , wherein the carcass sleeve comprises at least one carcass ply and a pair of anchoring annular structures engaged at axially opposite ends of the at least one carcass ply.

5. The process as claimed in claim 1 , wherein the shaped carcass sleeve engaged with the forming drum has axially opposite end flaps projecting cantilevered with respect to the abutment surface.

6. The process as claimed in claim 1 , wherein the at least one elementary semi-finished product is applied according to axially contiguous circumferential coils, in order to form a component of the tyre.

7. The process as claimed in claim 1 , wherein the at least one elementary semi-finished product is pressed against the abutment surface by a localised thrust action against a surface portion of the at least one elementary semi-finished product.

8. The process as claimed in claim 7 , wherein the thrust action is exerted by pressing an applicator roller against the at least one elementary semi-finished product while the forming drum rotates around a geometric rotation axis thereof.

9. The process as claimed in claim 7 , wherein the localised thrust action is applied against an action area having a transverse size smaller than a transverse size of the hollow portions.

10. The process as claimed in claim 9 , wherein the transverse size of the action area can be measured against the abutment surface in a radial plane of the forming drum.

Assignees

• Pirelli

Inventors

• Montanari Silvio
• Marchini Maurizio
• Haupt Oliver
• Mariani Mario
• Conti Davide Lupo

Classifications

• B29D30/16

  Applying the layers; Guiding or stretching the layers during application {(applying tread bands to carcasses B29D30/58; retreading B29D30/54)} · CPC title

• B29D30/12 Primary

  Cores · CPC title

• B29D30/245

  Drums for the single stage building process, i.e. the building-up of the cylindrical carcass and the toroidal expansion of it are realised on the same drum (expansion to a toroidal shape B29D30/36) · CPC title

• B29D2030/105

  the cores being movable · CPC title

• B29D30/10

  on round cores, i.e. the shape of the core is approximately identical with the shape of the completed tyre · CPC title