Process and apparatus for manufacturing tyres for vehicle wheels

Abstract

A process and apparatus for manufacturing tyres for vehicle wheels includes the step of building, on a forming support, a belt structure including at least one reinforcing structure of the so-called zero-degree type. The reinforcing structure is formed by depositing a continuous elongated reinforcing element on a deposition surface arranged in a radially outer position with respect to the forming support. The aforementioned deposition includes the step of exerting, through at least one element made from magnetic material, a magnetic attraction on a portion of the continuous elongated reinforcing element arranged at at least one pressing member and moving said at least one pressing member toward the forming support until the continuous elongated reinforcing element is brought into contact with the deposition surface.

Claims

1. An apparatus for manufacturing a tyre for vehicle wheels, the tyre comprising a belt structure arranged between a carcass structure and a tread band, wherein the belt structure comprises at least one zero-degree reinforcing structure, the apparatus comprising: (1) at least one forming support for building said zero-degree reinforcing structure by depositing at least one continuous elongated reinforcing element on a deposition surface arranged in a radially outer position with respect to said forming support; (2) at least one deposition member of the continuous elongated reinforcing element on said deposition surface, wherein said at least one deposition member comprises: at least one pressing roller movable between a rest position in which the pressing roller is in a moved-away position from the forming support and an operative position in which the pressing roller is in a moved-close position to the forming support; and at least one element adapted to exert a magnetic force arranged at said at least one pressing roller, wherein the at least one element adapted to exert a magnetic force is an element made from magnetic material and the magnetic material is defined by a coating of magnetic material applied to a radially outer surface of said at least one pressing roller; (3) a guide channel configured to guide the continuous elongated reinforcing element toward the at least one forming support and the continuous elongated reinforcing element is cantilevered out of the guide channel before being attracted to the at least one pressing roller through the at least one element and said guide channel and said at least one pressing roller are adjacent to each other; and (4) an arm configured for movement around a pivoting axis F between said rest position and said operative position and the arm comprises a plate connected to the at least one pressing roller at a rotation axis R and the plate is rotatably associated with at least one inlet roller at the pivoting axis F.

2. The apparatus according to claim 1, comprising at least one cutting member of the continuous elongated reinforcing element.

3. The apparatus according to claim 1, wherein said element made from magnetic material comprises at least one magnet arranged inside or alongside said at least one pressing roller.

4. The apparatus according to claim 3, wherein said at least one magnet does not rotate integrally with said at least one pressing roller.

5. The apparatus according to claim 1, wherein the guide channel has a closed cross section.

6. The apparatus according to claim 1, wherein the guide channel comprises an upstream portion with progressively decreasing cross sections along a feeding direction of the continuous elongated reinforcing element and a downstream portion with a substantially constant cross section.

7. The apparatus according to claim 6, wherein the upstream portion is longer than the downstream portion.

8. The apparatus according to claim 7, wherein the upstream portion is at least two times longer than the downstream portion.

9. The apparatus according to claim 1, wherein, when said arm is in said operative position the guide channel extends along a direction which is not tangent to the deposition surface.

10. The apparatus according to claim 1, wherein, when said arm is in said rest position the guide channel extends along a direction which is substantially tangent to the deposition surface.

11. The apparatus according to claim 1, wherein the at least one inlet roller is arranged upstream of the guide channel, and said at least one inlet roller is arranged to define a feeding direction which is substantially tangent to said at least one pressing roller.

12. The apparatus according to claim 1, further comprising an actuator adapted to adjust the pressure for driving movement of said at least one pressing roller toward the forming support.

13. The apparatus according to claim 1, wherein the plate is connected to a base at the pivoting axis F, the at least one inlet roller is arranged at an area defined in an end portion of the plate proximal to the base and the guide channel is arranged between the at least one inlet roller and the pressing roller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further characteristics and advantages of the present invention will become clearer from the following detailed description of some preferred embodiments of an apparatus and of a process in accordance with the present invention, made with reference to the attached drawings. In such drawings

(2) FIG. 1 is a schematic perspective view of a portion of an apparatus in accordance with the present invention, such an apparatus being shown in a configuration corresponding to an intermediate operative step of the process of the present invention;

(3) FIG. 2A is a schematic side view of the apparatus of FIG. 1 in a first operative step of the process of the present invention;

(4) FIG. 2B is a schematic view indicative of the aforementioned first operative step;

(5) FIG. 3A is a schematic side view of the apparatus of FIG. 1 in a second operative step of the process of the present invention;

(6) FIG. 3B is a schematic view indicative of the aforementioned second operative step;

(7) FIG. 4A is a schematic side view of the apparatus of FIG. 1 in a third operative step of the process of the present invention;

(8) FIG. 4B is a schematic view indicative of the aforementioned third operative step;

(9) FIG. 5 is a schematic view from above of the apparatus of FIG. 1;

(10) FIG. 6 is a schematic side view of a portion of the apparatus of FIG. 1;

(11) FIG. 7 is a section view taken along the lines H of FIGS. 5 and 6;

(12) FIG. 8 is a section view of a tyre obtainable in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(13) In FIG. 1, reference numeral 100 wholly indicates an example embodiment of an apparatus for depositing a continuous elongated reinforcing element on a forming support. Such an apparatus 100 is used, in particular, in a process for manufacturing tyres for vehicle wheels. More specifically, the apparatus 100 allows a reinforcing structure of the so-called zero degree type to be made in the building process of the belt structure of tyres for vehicle wheels.

(14) As schematically indicated in FIG. 8, a tyre 2 obtainable by the apparatus and the process of the present invention essentially comprises a carcass structure 3 having one or more carcass plies 4 each formed by reinforcement cords incorporated in an elastomeric matrix.

(15) Each carcass ply 4 comprises respective axially opposite end edges 4a, engaged with respective annular anchoring structures 5 arranged at the circumferentially inner edges of the tyre, i.e. in the areas of the tyre usually identified by the name beads.

(16) Each annular anchoring structure 5 is formed by a substantially circumferential annular insert 5a (commonly identified as bead core) on which at least one filling insert 5b is applied, in a radially outer position thereof.

(17) The carcass plies 4 can be internally coated with a so-called liner (not illustrated) essentially formed by an elastomeric layer that is impermeable to air or other fluid used for inflating the tyre 2.

(18) In a radially outer position with respect to the carcass structure 3 a belt structure 6 is applied, comprising one or more belt layers 7 reinforced through textile or metallic cords arranged according to an orientation properly inclined with respect to the circumferential extension of the tyre 2 and preferably crossed with respect to the orientation of the cords belonging to the adjacent layer or layers.

(19) The belt structure 6 also comprises at least one reinforcing structure, of the type usually called zero degree layer, applied in a radially outer position with respect to the aforementioned belt layers 7.

(20) The zero degree layer is normally made up of at least one continuous elongated element 200 wound according to axially adjacent coils, in a moved-close relationship or suitably spaced apart from one another, along to the axial extension of the tyre 2.

(21) In the depicted example, the zero degree layer consists of two distinct portions 8a extending towards the equatorial plane M of the tyre from respective axially opposite edges of the underlying belt layers 7.

(22) Between the carcass structure 3 and the belt structure 6 a layer of elastomeric material (not illustrated), called under-belt layer, can be provided, said layer having the function of making the radially outer surface of the carcass structure 3 as uniform as possible for the subsequent application of the belt structure 6. Sub-belt inserts 6a can also be applied between the carcass structure 3 and the belt structure 6 at the respective axially opposite end edges.

(23) A tread band 10 made from elastomeric material extends circumferentially in a radially outer position with respect to the belt structure 6. Between each axially outer edge of the tread band 10 and a respective bead extends a sidewall 11 to cover the respective side portion of the carcass structure 3.

(24) The apparatus 100 of the present invention is suitable for making the zero degree layer of the tyre 2 described above, or for making analogous reinforcement structures.

(25) With reference to FIG. 1, the apparatus 100 comprises a forming support 500, generally cylindrical or toroidal, pivotally mounted around a rotation axis X-X. A deposition surface 501 is defined on the forming support 500. Typically, such a deposition surface 501 corresponds to the radially outer surface of a belt layer 7 of the belt structure 6 of the tyre 2.

(26) At the forming support 500 there is a base 101, of the conventional type, to which an arm 105 is connected, at a pivoting axis F. Through such an arm 105 a continuous elongated reinforcing element 200 is fed towards the forming support 500 to then be deposited on the deposition surface 501, so as to form on such a deposition surface 501 the zero degree layer.

(27) The apparatus 100 comprises, upstream of the arm 105 with respect to the feeding direction A of the continuous elongated reinforcing element 200, a conventional cutting member 106 (for example of the type illustrated and described in WO 2007/054984 to the same Applicant).

(28) In accordance with the present invention, the arm 105 comprises a plate 110 pivoted to the base 101 at the aforementioned pivoting axis F, so as to be moveable between a rest position in which the arm 105 is in a moved-away position from the forming support 500 and an operative position in which the arm 105 is in a moved-close position to the forming support 500 (as illustrated by the arrow 0 in FIG. 1).

(29) The movement of the arm 105 around the pivoting axis F is driven by a suitable pneumatic actuator 115 operatively associated with the plate 110 and with the base 101 (as illustrated by the arrow T in FIG. 1), Such a pneumatic actuator 115, of the per se conventional type, allows the force with which the arm 105 is pushed towards the forming support 500 to be adjusted,

(30) A pressing roller 120 is rotatably associated with the plate 110 at a rotation axis R defined in an end portion of the plate 110 distal from the base 101. Therefore, the movement of the plate 110 of the arm 105 around the pivoting axis F causes a corresponding movement of the pressing roller 120 towards/away from the forming support 500.

(31) In accordance with the present invention, an element adapted to generate a magnetic force, for example an element 121 made from magnetic material, like for example Neodymium (Nd Fe B), is associated on the radially outer surface of the pressing roller 120.

(32) Such an element 121 can be made in the form of a coating band or, alternatively, defined by a plurality of elements adapted to be associated at suitable seats specifically provided on the radially outer surface of the pressing roller 120.

(33) Alternatively, the element 121 can be a magnet arranged inside or alongside the pressing roller 120. In this case, the aforementioned magnet is kept in a fixed position with respect to the pressing roller 120, i.e. it does not rotate integrally with the pressing roller 120.

(34) Alternatively, said element 121 can comprise at least one electromagnet.

(35) An inlet roller 130 is rotatably associated with the plate 110 at the pivoting axis F. Such a roller 130 supports the continuous elongated reinforcing element 200, during its movement by the devices provided upstream of the arm 105 towards the forming support 500, at an area defined in an end portion of the plate 110 proximal to the base 101.

(36) In a version of the apparatus 100 that is not illustrated, there are two inlet rollers, arranged one above the other with axes parallel to one another so as to guide the continuous elongated reinforcing element 200 at the lower and upper surfaces thereof.

(37) The arm 105 comprises, between the inlet roller 130 and the pressing roller 120, a guide channel 140 inside which the continuous elongated reinforcing element 200 is intended to run.

(38) As illustrated in FIG. 1 and in greater detail in FIG. 7, the guide channel 140 has a closed cross section, with height greater H than the height h of the continuous elongated reinforcing element 200 and width L greater than the width 1 of the continuous elongated reinforcing element 200. This is in order to avoid as much as possible accidental contacts of the continuous elongated reinforcing element 200 with the upper and side walls of the guide channel 140, so as not to generate undesired friction or stretching on the continuous elongated reinforcing element 200 running in the guide channel 140.

(39) As illustrated in FIG. 1 and in greater detail in FIGS. 5 and 7, the guide channel 140 comprises an upstream portion 141 with progressively decreasing cross sections along the feeding direction of the continuous elongated reinforcing element 200 and a downstream portion 142 with a substantially constant cross section. The upstream portion 141 is longer than the downstream portion, preferably at least 2 times longer than the downstream portion.

(40) In a specific embodiment developed by the Applicant, the height H of the guide channel 140 is roughly twice the height h of the continuous elongated reinforcing element 200. In a preferred solution, at the downstream portion 142 having a substantially constant cross section, H is equal to about 3.5 mm and h is equal to about 1.8 mm, whereas the width L of the guide channel 140 is equal to about 7.6 mm and the width 1 of the continuous elongated reinforcing element 200 is equal to about 6.3 mm.

(41) As illustrated in FIG. 6, the mutual arrangement between pressing roller 120, inlet roller 130 and guide channel 140 is studied so that the continuous elongated reinforcing element 200 runs through the guide channel 140 keeping a condition of tangency with the inlet roller 130 and the pressing roller 120, without sliding on the base surface of the guide channel 140.

(42) Such a provision, in combination with suitable sizing of the height and of the width of the guide channel 140 according to the height and width of the continuous elongated reinforcing element 200 (in accordance with what has been described above), allows the continuous elongated reinforcing element 200 to substantially run without sliding in the guide channel 140.

(43) The mutual arrangement between base 101 of the apparatus 100 of the present invention and forming support 500 is also studied so that when the arm 105 is in a moved-close position to the forming support 500 the guide channel 140 extends along a direction which is not tangent to the deposition surface 501 (FIGS. 2A and 4A), whereas when the arm 105 is in a moved-away position from the forming support 500 the guide channel 140 extends along a direction substantially tangent to the deposition surface 501 (FIG. 3A).

(44) The deposition process carried out through the apparatus 100 is described below with reference to FIGS. 2A-2B, 3A-3B and 4A-4B.

(45) In a first step of the process, the continuous elongated reinforcing element 200 is fed towards the arm 105 along a feeding direction A. In such a step the cutting member 106 is deactivated.

(46) As illustrated in FIG. 2A, once the arm 105 has been reached, the continuous elongated reinforcing element 200 is guided by the inlet wheel 130 inside the guide channel 140 and through this towards the forming support 500. The portion of continuous elongated reinforcing element 200 that projects cantilevered out of the guide channel 140 is attracted by the pressing roller 120 through the magnetic interaction between the element 121 made from magnetic material associated with the pressing roller 120 and the metallic elements provided inside the continuous elongated reinforcing element 200. The position of the portion of continuous elongated reinforcing element 200 projecting cantilevered from the deposition apparatus 100 is thus frozen, in this way allowing the continuous elongated reinforcing element 200 to be kept in the desired position with respect to the forming support 500. In such a step, the continuous elongated reinforcing element 200 is in a tangent condition with respect to both the inlet roller 130 and the pressing roller 120 and runs without sliding in the guide channel 140.

(47) While carrying out the aforementioned step, the arm 105 is pushed by the pneumatic actuator 115 into a moved-close position to the deposition surface 501 (as illustrated by the arrows 01 and T1 in FIG. 2A) and the forming support 500 is made to rotate around the rotation axis X (for example in the anti-clockwise direction, as indicated by the arrow S in the attached figures).

(48) The continuous elongated reinforcing element 200 is then pressed by the pressing roller 120 against the deposition surface 501 and the pressing roller 120 is pulled into rotation by friction (as indicated by the arrow P in the attached figures).

(49) In this way the deposition of the continuous elongated reinforcing element 200 on the deposition surface 501 begins, as schematically shown in FIG. 2B. Such deposition takes place according to a direction which is not tangent to the deposition surface 501 of the forming support 500.

(50) In a subsequent step of the process of the present invention, illustrated in FIG. 3A and corresponding to the intermediate step of the deposition of the continuous elongated reinforcing element 200 on the deposition surface 501, the arm 105 is moved away from the deposition surface 501 as indicated by the arrows 02 and T2 in FIG. 3A. In this step, the deposition of the continuous elongated reinforcing element 200 on the deposition surface 501 takes place according to a direction tangent to the deposition surface 501. The continuous elongated reinforcing element 200 is deposited according to adjacent coils perpendicular to the rotation axis X-X of the forming support 500, as illustrated in FIG. 3B.

(51) In a subsequent step, illustrated in FIG. 4A, the cutting member 106 is activated so as to shear the continuous elongated reinforcing element 200. After this cutting the deposition of the continuous elongated reinforcing element 200 on the deposition surface 501 is completed. In this step, the arm 105 is once again pushed by the pneumatic actuator 115 into a moved-close position to the deposition surface 501 (as illustrated by the arrows 03 and T3 in FIG. 4A). The deposition takes place according to a direction which is not tangent to the deposition surface 501 of the forming support 500.

(52) From what has been described above, it is clear how the process and the apparatus of the present invention allow the deposition of the continuous elongated reinforcing element 200 on the forming support 501 to be carried out avoiding undesired stretching or friction on the continuous elongated reinforcing element 200 and at the same time counteracting possible twisting or lateral deviation of the continuous elongated reinforcing element 200.

(53) Of course, a man skilled in the art can bring further modifications and variants to the invention described above in order to satisfy specific and contingent application requirements, said variants and modifications being in any case within the scope of protection as defined by the following claims.