Process for applying noise-reducing elements to a tyre for vehicle wheels

1. A process for applying noise-reducing elements to a tyre for vehicle wheels by an automated gluing apparatus comprising a control unit and a gripping member controlled by said control unit, said tyre having a radially inner surface comprising at least one service area and having a circumferential dimension, said process comprising:

determining by the control unit a position in circumferential direction of said at least one service area on said radially inner surface of the tyre;

determining by the control unit a position in circumferential direction of at least one target area on said radially inner surface of the tyre based on the position in circumferential direction of said at least one service area; and

applying by the gripping member at least one noise-reducing element at said at least one target area,

wherein determining the position in circumferential direction of said at least one service area comprises:

circumferentially inspecting said radially inner surface of the tyre starting from a reference position;

detecting an angular position of said at least one service area with respect to said reference position; and

determining the position in circumferential direction of said at least one service area based on said angular position and on the circumferential dimension of said radially inner surface of the tyre.

2. The process according to claim 1 , wherein inspecting said radially inner surface of the tyre comprises:

analyzing at least one circumferential portion of said radially inner surface of the tyre by means of a sensor operative to the control unit; and

moving said sensor around a reference axis parallel to or coinciding with a rotation axis of the tyre starting from said reference position.

3. The process according to claim 2 , wherein detecting the angular position of said at least one service area comprises:

acquiring a first image of said at least one service area when said sensor detects a contrast element provided on said radially inner surface of the tyre at said at least one service area; and

determining a circumferential distance travelled by said sensor with respect to said reference position when said first image has been acquired.

4. The process according to claim 3 , wherein the position in circumferential direction of said at least one service area is determined based on said circumferential distance.

5. The process according to claim 3 , wherein said contrast element is defined on a film removably associated with said radially inner surface of the tyre at said at least one service area.

6. The process according to claim 5 , wherein said film comprises a main portion and a detection portion adjacent to said main portion and having a first length in circumferential direction and a second length in axial direction, wherein said contrast element is defined on said detection portion.

7. The process according to claim 6 , wherein before determining the position in circumferential direction of said at least one service area, said tyre is moved along a feeding direction, and wherein said film is associated with said radially inner surface of the tyre so that said detection portion is arranged upstream of said main portion with reference to said feeding direction, or downstream of said main portion with reference to said feeding direction, or parallel to said main portion with reference to said feeding direction.

8. The process according to claim 7 , comprising determining the position of said detection portion with respect to said main portion with reference to said feeding direction by comparing said first image with a second image acquired by said sensor after said first image.

9. The process according to claim 3 , wherein determining the position in circumferential direction of said at least one target area comprises calculating a first linear dimension as a function of said circumferential distance.

10. The process according to claim 9 , wherein calculating said first linear dimension comprises adding to said circumferential distance, or subtracting from said circumferential distance, a second linear dimension.

11. The process according to claim 2 , wherein said sensor is a first camera.

12. The process according to claim 1 , wherein the radially inner surface of the tyre comprises at least two service areas, and wherein said process comprises:

determining the position in circumferential direction of said at least two service areas;

calculating the circumferential distance between said at least two service areas;

determining the position in circumferential direction of said at least one target area on said radially inner surface of the tyre based on the position in circumferential direction of said at least two service areas and on the circumferential distance between said at least two service areas; and

applying at least one noise-reducing element at said at least one target area.

13. The process according to claim 12 , wherein said noise-reducing elements have a set length in circumferential direction and wherein said process comprises determining a number of noise-reducing elements that can be applied between said at least two service areas as a function of said set length in circumferential direction.