Apparatus for building a carcass structure of a tire for vehicle wheels

Abstract

A process for manufacturing tyres for vehicle wheels, comprising the step of building on a forming support a carcass structure comprising at least one carcass ply and, at least one end edge of the carcass ply, at least one annular anchoring structure comprising at least one substantially circumferential annular insert and at least one filling insert associated to said at least one substantially circumferential annular insert. The step of building the carcass structure comprises the steps of positioning the annular anchoring structure on the carcass ply by moving the annular substantially circumferential insert into contact with an end edge of the carcass ply by means of a special positioning member, pulling down the filling insert on the end edge of the carcass ply and turning up a free end portion of the end edge of the carcass ply so as to form a turned up end portion of the carcass ply including said annular anchoring structure. The pulling down of the filling insert on the end edge of the carcass ply is carried out by a special pulling down member while the substantially circumferential annular insert is retained into a contact position with the end edge of the carcass ply by said positioning member.

Claims

1. A process for manufacturing a tyre for a vehicle wheel, comprising building on a forming support a carcass structure comprising a carcass ply, and, at an end edge of the carcass ply, an annular anchoring structure comprising a substantially circumferential annular insert and a filling insert associated with the substantially circumferential annular insert, wherein building the carcass structure comprises: positioning the annular anchoring structure on the carcass ply by a positioning member which moves along a pressing direction to bring the substantially circumferential annular insert into contact with the end edge of the carcass ply; pressing the filling insert onto the end edge of the carcass ply; and turning up, with a turning-up member, the end edge onto itself so as to form a turned up end portion of the carcass ply comprising the annular anchoring structure, wherein at the end of the turning up the end edge, the turning-up member is in contact with a free end portion of the end edge; wherein pressing the filling insert onto the end edge of the carcass ply is carried out while the substantially circumferential annular insert is retained in a contact position with the end edge of the carcass ply by the positioning member; wherein pressing the filling insert comprises pushing the filling insert by exerting thrust on a predetermined portion of a side surface of the filling insert by a ring having a side surface with a predetermined profile; and wherein the predetermined profile of the side surface of the ring before the filling insert is pulled down on the end edge of the carcass ply is conjugated to the profile of the side surface of the filling insert after the filling insert is pulled down on the end edge of the carcass ply to act on the entire side surface of the filling insert annularly and radially.

2. The process according to claim 1, wherein the positioning member comprises a tubular portion extending parallel to an axis of rotation of the forming support and having, on a radially outer annular surface thereof, sliding guides extending parallel to the axis of rotation, and wherein the ring is slidingly mounted on the sliding guide and slides with respect to the tubular portion of the positioning member.

3. The process according to claim 1, wherein pressing the filling insert comprises pushing the filling insert against the forming support while the substantially circumferential annular insert is retained by thrust against the forming support by the positioning member.

4. The process according to claim 1, wherein the ring is controlled by a hydraulic cylinder with a piston.

5. The process according to claim 4, wherein the ring axially pushes the filling insert onto the edge of the carcass ply by the piston of the hydraulic cylinder.

6. The process according to claim 1, wherein the turning-up member comprises an air tube, and turning up the end edge includes inflating the air tube to lift the free end portion of the end edge.

7. The process according to claim 1, wherein the ring is removably associated with the positioning member.

8. The process according to claim 1, wherein the filling insert has a height not greater than 30 mm.

9. The process according to claim 1, wherein the filling insert has a height not lower than 7 mm.

10. The process according to claim 1, wherein the filling insert has a substantially triangular shape, with a base having a length shorter than 12 mm.

11. The process of claim 1, wherein the thrust is exerted by the ring initially on a radially outer annular portion of the side surface of the filling insert and then on progressively larger portions of the side surface of the filling insert starting from the radially outer portion along the whole radial extension of the side surface of the filling insert.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of the present invention will appear more clearly from the following detailed description of some preferred embodiments of an apparatus and process according to the present invention, made with reference to the annexed drawings. In such drawings:

(2) FIG. 1 is a schematic partly cutaway view of a longitudinal section of a portion of a first embodiment of an apparatus that carries out a process according to the present invention, such apparatus being in a first operating configuration thereof;

(3) FIG. 2 is a schematic view of the apparatus of FIG. 1 in a second operating configuration thereof;

(4) FIG. 3 is a schematic partly cutaway view of a longitudinal section of a portion of a second embodiment of an apparatus that carries out a process according to the present invention, such apparatus being in a first operating configuration thereof;

(5) FIG. 4 is a schematic view of the apparatus of FIG. 3 in a second operating configuration thereof;

(6) FIG. 5 is a schematic view of the apparatus of FIG. 3 in a third operating configuration thereof;

(7) FIG. 6 is a schematic side view of a portion of the apparatus of FIG. 3;

(8) FIG. 7 is a schematic view showing a step of the process of the present invention following that Illustrated in FIGS. 2 and 5.

DETAILED DESCRIPTION

(9) In FIGS. 1 and 2, reference numeral 100 globally indicates a first illustrative embodiment of an apparatus usable in a process for manufacturing a tyre for vehicle wheels, according to a first embodiment of the present invention. In particular, apparatus 100 is used in a step of building a carcass structure of the tyre for arranging one or more annular anchoring structures 10 (hereinafter also called bead cores) at that region of the carcass structure that will constitute the bead of the tyre. Such annular anchoring structures 10 are intended to keep the tyre well fixed to the anchoring seat specifically provided in the rim of the vehicle wheel.

(10) The building of the carcass structure of the tyre comprises the preliminary step of arranging a carcass ply 2 on a substantially cylindrical forming support 50 and after that, the step of associating each annular anchoring structure 10 to an end edge 2a of the carcass ply 2.

(11) In the embodiment illustrated in FIGS. 1-2, the annular anchoring structure 10 is associated to the end edge 2a of the carcass ply 2 at a side shoulder 51 of the forming support 50, such forming support 50 being rotatably mounted about an axis of rotation X-X in a totally conventional manner.

(12) The structure of the forming support 50 is not described in detail herein as it can be made in any convenient manner by a man skilled in the art.

(13) As illustrated in FIGS. 1 and 2, each annular reinforcing structure 10 comprises at least one substantially circumferential annular insert 11 on which at least one filling insert 12 is applied in a radially outer position thereof.

(14) Always with reference to FIGS. 1 and 2, apparatus 100 comprises a member 110 sliding parallel to the axis of rotation X-X of the forming support 50, and thus in the two opposite ways of the direction indicated in FIGS. 1 and 2 by arrow F, so as to move close to, or away from, the forming support 50. The movement of ring 110 towards, and away from, the forming support 50 is carried out in a totally conventional manner by means known by a man skilled in the art.

(15) Ring 110 is intended to bring the annular anchoring structure 10 in contact with the end edge 2a of the carcass ply 2. In particular, as illustrated in FIGS. 1 and 2, ring 110 acts on the substantially circumferential annular insert 11 of the annular anchoring structure 10 pushing it against shoulder 51 of the forming support 50, thus positioning the annular anchoring structure 10 in the desired position on the end edge 2a of the carcass ply 2. Throughout the present description, ring 110 shall also be defined as “bead core holder ring”.

(16) The bead core holder ring 110 comprises a tubular portion 111 extending parallel to the axis of rotation X-X of the forming support 60 and an annular portion 112 extending perpendicular to the aforementioned axis of rotation X-X. Sliding guides 113 extending parallel to the axis of rotation X-X of the forming support 50 are provided on the radially outer annular surface of the tubular portion 111 of the bead core holder ring 110.

(17) According to the present invention, apparatus 100 of FIGS. 1 and 2 comprises a member 120 slidingly mounted, by special guides 123, on the sliding guides 113 of the bead core holder ring 110.

(18) In the specific embodiment illustrated in FIGS. 1 and 2, member 120 is made in the shape of a ring 121, but it is possible to envisage different embodiments, such as for example a plurality of members arranged side by side in circumferential direction so as to substantially define a ring.

(19) Ring 121 is intended to slide with respect to the bead core holder ring 110 in the direction indicated in FIG. 1 by arrow G for pushing the filling insert 12 of the annular anchoring structure 10 against shoulder 51 of the forming support 50, thus obtaining the pulling down of the filling insert 12 on the end edge 2a of the carcass ply 2, substantially as illustrated in FIG. 2. Throughout the present description, ring 121 shall be defined as “filling insert pulling down ring.”

(20) In the specific embodiment illustrated in FIGS. 1 and 2, the movement of the filling insert pulling down ring 121 is controlled by a piston 131 of a hydraulic cylinder 130 suitably arranged in the proximity of the forming support 50, for example on a support bracket 61 of a support frame 60. Piston 131 is rigidly associated to the filling insert pulling down ring 121 and crosses a hole-62 formed on a side wall 63 of the support frame 60 and a hole 115 formed on the annular portion 112 of the bead core holder ring 110 and axially aligned to hole 62.

(21) Of course, in place of the hydraulic cylinder 130 any other conventional device may be used which in any case guarantees a thrust sufficient for deforming the filling insert 12 of the annular anchoring structure 10.

(22) As illustrated in FIG. 2, the filling insert pulling down ring 121 acts on the filling insert 12 of the annular anchoring structure 10 while the bead core holder ring 110 pushes the substantially circumferential annular insert 11 of the annular anchoring structure 10 against the shoulder 51 of the forming support 50.

(23) Preferably, the filling insert puffing down ring 121 is removably associated to the bead core holder ring 110 so as to be removed for any maintenance and/or replacement operations.

(24) The filling insert pulling down ring 121 preferably has a side surface 125 having a predetermined profile. More preferably, the profile of the side surface 125 is conjugated to that of the corresponding side surface 12a of the filling insert 12 when such insert is pulled down on the end edge 2a of the carcass ply 2, so as to act on the entire annular and radial extension of the side surface 12a during the pulling down of the filling insert 12.

(25) With reference to FIGS. 1 and 2, a preferred embodiment of the process that can be carried out by apparatus 100 described above shall now be described.

(26) In a first process step, illustrated in FIG. 1, the annular anchoring structure 10 is pushed by the bead core holder ring 110 against the shoulder 51 of the forming support 50. In particular, the bead core holder ring 110 acts by thrust on the substantially circumferential annular insert 11 up to bring it in contact with the end edge 2a of the carcass ply 2 previously positioned on the forming support 50. The radial position of the substantially circumferential annular insert 12 on the end edge 2a of the carcass ply is predetermined in the design stage.

(27) In this step, the end portion 2b of the end edge 2a is kept shifted towards the axis of rotation X-X of the forming support 50 by special members (not shown), so as to allow the bead core holder ring 110 to come close to the forming support 50. Moreover, in this step, the filling insert pulling down ring 121 is kept into a position axially spaced from the filling insert 12.

(28) In a subsequent step, illustrated in FIG. 2, while the bead core holder ring 110 continues to act by thrust on the substantially circumferential annular insert 11 for retaining it into position against shoulder 51 of the forming support 50, the filling insert pulling down ring 120 is axially pushed by the hydraulic cylinder 130, by means of the piston 131 thereof, against shoulder 51 of the forming support 50. In this step, the pulling down of the filling insert 12 on the end edge 2a of the carcass ply 2 is carried out.

(29) In particular, such pulling down takes place by first exerting a predetermined thrust on a radially outer portion of the side surface 12a of the filling insert 12 and then, by axially moving the thrust ring 121 towards the forming support 50, exerting such thrust on a progressively larger portion of the side surface 12a of the filling insert 12 starting from the aforementioned radially outer portion along all the radial extension of the side surface 12a.

(30) The aforementioned step allows the steady anchoring of the annular anchoring structure 10 on the end edge 2a of the carcass ply 2. Such steady anchoring is ensured by the stickiness with the rubber mixture of the carcass ply 2 both of the rubber mixture of the substantially circumferential annular insert 11 of the annular anchoring structure 10 and of the rubber mixture of the pull down filling insert 12.

(31) FIGS. 3 to 5 show in a sequence the operating steps of an alternative embodiment of the apparatus of the present invention, globally indicated with reference numeral 200. In such embodiment, elements identical to those described before with reference to apparatus 100 of FIGS. 1 and 2 are indicated with the same reference numeral.

(32) Apparatus 200 of FIG. 3-5 differs from apparatus 100 of FIG. 1-2 only in that the pulling down of the filling insert 12 on the end edge 2a of the carcass ply 2 takes place by a member 220 of a different type from the filling insert pulling down ring 120 used in apparatus 100 of FIGS. 1 and 2. Apart from this, apparatus 200 is totally identical to apparatus 100 of FIGS. 1 and 2.

(33) In particular, in apparatus 200 of FIG. 3 the filling insert pulling down member 220 comprises a thrust ring 221 slidingly associated to the bead core holder ring 110 in a manner totally similar to the filling insert pulling down ring 121 of apparatus 100 of FIGS. 1 and 2, and a plurality of pressing members 222 (only one of which being illustrated in FIGS. 3-5) arranged side by side in a circumferential direction (FIG. 6) and each elastically associated to the thrust ring 221.

(34) In particular, each pressing member 222 comprises a respective arm 223 pivoted on the thrust ring 221 at a special pin 224 having a pivoting axis substantially perpendicular to a radial plane of the forming support 50.

(35) Arm 223 is further elastically associated to the thrust ring 221 by a traction spring 225 active along a predetermined direction defined in the above radial plane for keeping arm 223 pressed against portion 111 of the bead core holder ring 110. In substance, arm 223, when stressed in a direction opposite that wherein the elastic return stress exerted by spring 225 acts, is movable in clockwise direction around pin 224 in the radial plane of the forming support 50.

(36) Each pressing member 222 further comprises a roller 226 rotatably associated to the respective arm 223. Roller 226 preferably has a concave profile, with a bending radius greater than 3 mm, and more preferably smaller than 5 mm, compared to the radius of the forming support 50.

(37) Preferably, the coupling between rollers 226 and arms 223 and that between arms 223 and thrust ring 221 is of removable type.

(38) The process carried out by apparatus 200 of FIG. 3-5 is totally similar to that carried out by apparatus 100 of FIG. 1-2 described above, with the only difference that, as shown in the sequence of FIGS. 3 to 5, the pulling down of the filling insert 12 on the end edge 2a of the carcass ply 2 in this case takes place by the effect of the rolling of rollers 226 on the side surface 12a of the filling insert 12 starting from a radially inner portion of such side surface 12a to continue on a radially outer portion of the side surface 12a with respect to the aforementioned radially inner portion. Such rolling takes place by the effect of the axial movement of the thrust ring 221 which, actuated by the hydraulic cylinder 130 by means of piston 131, is pushed against shoulder 51 of the forming support 50. During their rolling, rollers 226 are kept pressed on the filling insert 12 by the elastic return action exerted by spring 225.

(39) Also in this case, as shown in particular in FIGS. 4 and 5, rollers 226 act on the filling insert 12 of the annular anchoring structure 10 while the bead core holder ring 110 pushes the substantially circumferential annular insert 11 of the annular anchoring structure 10 against shoulder 51 of the forming support 50.

(40) In the building step of the carcass structure of the tyre, the aforementioned steps of positioning the annular anchoring structure 10 on the end edge 2a of the carcass ply 2 and of pulling down the filling insert 12 are repeated several times if more than one annular anchoring structure 10 must be associated to the end edge 2a of the carcass ply 2.

(41) Moreover, further operating steps may be provided besides those described above, wherein specific reinforcing structures (not shown) are associated to the carcass ply 2 in radially and/or axially outer and/or inner position with respect to each annular anchoring structure 10.

(42) Both in the case in which apparatus 100 of FIG. 1-2 or apparatus 200 of FIG. 3-5 is used, subsequent to the step of pulling down the filling insert 12 and optionally to the step of laying the above, reinforcing structures, an operating step is provided wherein the end edge 2a of the carcass ply 2 is turned up on itself so as to form a turned up end portion 20 of the carcass ply 2 comprising the annular anchoring structure 10 and optionally the above reinforcing structures (FIG. 7) therein.

(43) Such step can be carried out in a conventional manner, for example by the use of an air tube 140 of the conventional type and of a shaped ring 150, also of the conventional type, movable in a direction E parallel to the axis of rotation X-X of the forming support 50 (FIG. 7). In particular, the air tube 140, once inflated, lifts a free end portion 2b of the end edge 2a of the carcass ply 2. At that point, the shaped ring 150 pushes such air tube 140 towards shoulder 51 of the forming support 50 thus forming the turned up end portion 20 of the carcass ply 2 and thus, the tyre bead.

(44) According to the present invention, therefore, the member 140 that carries out the turning up of the end portion of the carcass ply 2 is operatively separate from member 120, 220 that carries out the puffing down of the filling insert 12 of the annular anchoring structure 10.

(45) A step of passing a pressing member (not shown) on the turned up end 20 of the carcass ply 2 is also preferably provided in order to compact the tyre bead.

(46) The use of apparatus 100 and 200 of the present invention is particularly advantageous when the filling insert to be pulled down is particularly low and stocky, with a height not greater than 30 mm, more preferably not greater than 25 mm, and even more preferably not smaller than 7 mm.

(47) Preferably, moreover, the filling insert has a substantially triangular shape, with a base having a length shorter than 12 mm.

(48) Of course, what said above also applies when filling inserts having different height and shape than those mentioned above are used.

(49) From the above description it is clear that the various embodiments of the process and of the apparatus described above allow manufacturing high efficiency tyres, even of the high performance lowered type, wherein the bead core position is the one desired and defined in the design stage, such position not being altered by the effect of the stresses the bead core is subjected to during the steps of pulling down the filling insert and turning up the free end portion of the carcass ply. This occurs thanks to the fact that the step of puffing down the filling insert is carried out before the turning up step and in particular, while the bead core is retained into a contact position with the end edge of the carcass ply by a special bead core positioning member.