Process and apparatus for manufacturing tyres for vehicle wheels

Abstract

A process for manufacturing tyres for vehicle wheels includes associating at least one reinforcing structure with at least one surface portion of at least one tyre component laid on a forming support, wherein associating the at least one reinforcing structure includes bringing, through a handling and deposition member, at least one reinforcing element to the forming support and depositing, through said handling and deposition member, the reinforcing element on a respective deposition part defined on a surface portion of the component. The depositing includes gradually laying the reinforcing element on the deposition part following the profile of the deposition part in a circumferential direction.

Claims

1. A process for manufacturing a tyre for a vehicle wheel, comprising associating at least one reinforcing structure with at least one surface portion of at least one tyre component laid on an annular forming support, wherein associating said at least one reinforcing structure comprises: bringing, through a handling and deposition member, at least one reinforcing element to said annular forming support, said handling and deposition member comprising a holding device configured for engaging and holding said at least one reinforcing element, and two thin plate elements symmetrically arranged at opposite sides with respect to said holding device and adapted to interact with said at least one reinforcing element, each of said thin plate elements being flexible at least in a circumferential direction of the annular forming support, and each of said thin plate elements being coupled at a first free end to one of the opposite sides of the holding device such that no relative movement is allowed between the first free ends of the thin plate elements and the holding device; engaging and holding said at least one reinforcing element at a central portion thereof with said holding device of said handling and deposition member; and depositing, through said handling and deposition member, said at least one reinforcing element on a respective deposition part defined on at least one surface portion of said at least one tyre component, wherein said depositing comprises gradually laying said at least one reinforcing element on said respective deposition part starting from said central portion and following a profile of said respective deposition part in a circumferential direction.

2. The process according to claim 1, wherein gradually laying said at least one reinforcing element on said respective deposition part, is carried out starting from said central portion of the at least one reinforcing element up to opposite end portions thereof.

3. The process according to claim 2, wherein gradually laying said at least one reinforcing element on said respective deposition part, comprises: positioning said central portion of said at least one reinforcing element on said respective deposition part; and depositing a remaining portion of said at least one reinforcing element on said respective deposition part.

4. The process according to claim 3, wherein depositing the remaining portion of said at least one reinforcing element is obtained in reaction to a predetermined thrust action exerted on said respective deposition part at said central portion of said at least one reinforcing element after said central portion has been positioned.

5. The process according to claim 3, wherein depositing the remaining portion of said at least one reinforcing element comprises bending said remaining portion along at least one first predetermined direction.

6. The process according to claim 5, wherein said at least one first predetermined direction is inclined by a predetermined angle with respect to said circumferential direction.

7. The process according to claim 6, wherein depositing the remaining portion of said at least one reinforcing element comprises bending said remaining portion along at least one second predetermined direction.

8. The process according to claim 7, wherein said at least one second predetermined direction is orthogonal to said first predetermined direction.

9. The process according to claim 1, comprising, after said at least one reinforcing element has been deposited, rotating said annular forming support by a predetermined angle about a rotation axis thereof and pressing said at least one reinforcing element against said respective deposition part during such rotation.

10. The process according to claim 1, wherein said at least one tyre component is at least one carcass ply.

11. The process according to claim 1, wherein associating said at least one reinforcing structure comprises: feeding a continuous reinforced band-like element close to said annular forming support; and cutting said continuous reinforced band-like element to form at least one reinforcing element.

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 simplified schematic plan view of an apparatus for manufacturing a tyre for vehicle wheels according to the present invention, such apparatus being in an operating configuration;

(3) FIG. 2 is an enlarged and partly cutaway perspective view of a portion of the apparatus of FIG. 1 in a non operating configuration;

(4) FIG. 3 is a perspective bottom view of a detail of the portion of FIG. 2;

(5) FIG. 4 is an orthogonal view of the portion of apparatus of FIG. 2 in a first operating configuration;

(6) FIG. 5 is an orthogonal view of the portion of apparatus of FIG. 2 in a second operating configuration.

DETAILED DESCRIPTION

(7) In FIG. 1, reference numeral 100 globally indicates an exemplary embodiment of an apparatus for manufacturing a tyre for vehicle wheels according to the present invention.

(8) Preferably, apparatus 100 may be used, in a process for manufacturing a tyre for vehicle wheels, for building a carcass ply. Such building comprises the arrangement of an annular reinforcing structure 1 at each end edge 2a of a carcass ply 2 previously laid on a forming support 150 which is preferably cylindrical. The above end edges 2a are defined at axial end zones of ply 2 adapted to define the bead region of the tyre.

(9) The reinforcing structure 1 therefore is conveniently formed directly on the forming support 150. It is defined by a predetermined number of reinforcing elements 5, of same length and width, laid one after the other on respective parts of a portion la of deposition surface defined on the opposite end edges 2a of the carcass ply 2 and extended in the circumferential direction. FIG. 1 shows a reinforcing structure 1 while it is formed at each end edge 2a of the carcass ply 2.

(10) In the apparatus 100 according to the present invention, the positioning and the subsequent complete laying of the reinforcing element are carried out by a single mechanical member, illustrated in detail in FIGS. 2-5 and described hereinafter.

(11) In FIGS. 2-5, the bending radius of the forming support 150 and the size in the circumferential direction of the reinforcing element 5 (and of the relative mechanical member supporting it) have been intentionally altered for higher clarity of the description relating to the deposition of the reinforcing element 5 on the carcass ply 2 laid on the forming support 150.

(12) In order to allow the subsequent laying in circumferential direction of the reinforcing elements 5, the forming support 150 is periodically controlled in rotation about the axis of rotation X-X thereof by an angle corresponding to a predetermined circumferential step.

(13) The reinforcing elements 5 are preferably obtained by cut to size operations of at least one continuous reinforced band-like element 4 extended along a longitudinal extension direction indicated in FIG. 1 with G.

(14) The continuous reinforced band-like element 4 has a defined and constant width L, preferably comprised between 1 and 100 mm, more preferably between 30 and 70 mm.

(15) The continuous reinforced band-like element 4 preferably comprises a plurality of reinforcing cords (not shown in the figures) of metal or textile material embedded in a matrix of elastomeric material or coated by a layer of elastomeric material. Such reinforcing cords extend parallel to one another along the longitudinal extension direction G of the continuous reinforced band-like element 4.

(16) The continuous reinforced band-like element 4 is fed along the longitudinal extension direction G thereof by a feeding device 20, which is illustrated in FIG. 1 in a totally schematic manner. The feeding takes place with a predetermined pre-advance step, such step defining the cutting length of the continuous reinforced band-like element 4, which corresponds to the width of the reinforcing elements 5 when laid on the forming support 150.

(17) Downstream of the feeding device 20, with reference to the advance direction of the continuous reinforced band-like element 4, there is provided a cutting unit 30 suitable for carrying out the sequential operations of cutting to size the continuous reinforced band-like element 4 for obtaining in a sequence the reinforcing elements 5. The cutting unit 30 acts on the continuous reinforced band-like element 4, with a predetermined cutting frequency, along a cutting direction that on the lying plane of the continuous reinforced band-like element 4, defines a predetermined cutting angle with the longitudinal extension direction G of the continuous reinforced band-like element 4.

(18) In the preferred embodiments of the present invention, the cutting angle is set to a value greater than zero, preferably comprised between about 15 and about 90, more preferably between about 20 and about 50, even more preferably between about 22 and about 45.

(19) When the cutting angle is equal to 90, the length of the reinforcing elements 5 laid on the forming support 150 corresponds to the width of the continuous reinforced band-like element 4. When the cutting angle is smaller than 90 the length of the reinforcing elements 5 is equal to the width of the continuous reinforced band-like element 4 divided the sine of angle . Preferably, the length of the reinforcing elements 5 is in any case comprised between 1 mm and 100 mm, more preferably between 30 mm and 70 mm.

(20) Downstream of the cutting unit 30, that is between the cutting unit 30 and the forming support 150, a pick up device 40 of the reinforcing elements 5 is provided. Such a pick up device 40 comprises a pair of arms 41a, 41b adapted to alternatively pick up the reinforcing element 5 just formed to move it towards the forming support 150.

(21) Apparatus 100 further comprises, between the pick up device 40 and the forming support 150, a pair of handling members 50a, 50b, each adapted to pick up a respective reinforcing element 5 from a respective arm 41a, 41b of the pick up device 40 after such arm has made a predetermined angular movement (preferably by 90) starting from the cutting unit 30.

(22) The handling members 50a, 50b (which are absolutely identical to one another) are preferably arranged symmetrically at opposite sides with respect to the centre line plane M of apparatus 100 and are moved synchronously with arms 41a, 41b. Each reinforcing element 5 is thus transferred by a respective arm 41a, 41b of the pick up device 40 to a respective handling and deposition member 50a, 50b, which then lays it on a respective part of the portion la of the deposition surface, as better described hereinafter.

(23) In the present description only one of said handling and deposition members (herein indicated with reference numeral 50a) is described in detail, it being understood that what said also applies to the other handling and deposition member 50b.

(24) As illustrated in detail in FIG. 2, the handling and deposition member 50a is defined by an articulated arm comprising a first vertical arm element 51 pivoted on a base 101 (FIG. 1) of apparatus 100 at a vertical pivoting arm Y.sub.1 and a second arm element 52 pivoted to the arm element 51 at a horizontal pivoting axis Y.sub.2 defined on a top end portion of arm 51.

(25) The handling and deposition member 50a further comprises a deposition member 60 pivoted at a horizontal pivoting axis Y.sub.3 defined at a free end of the second arm element 52 opposite that of pivoting to the first arm element 51.

(26) As shown in FIGS. 2-5, the deposition member 60 comprises a support member 61 which in turn comprises a first central upright 62 pivotally mounted about a pivoting axis Y.sub.4 perpendicular to the pivoting axis Y.sub.3.

(27) Two brackets 63 are symmetrically arranged at opposite sides with respect to the first upright 62, each bracket 63 being integrally associated with a free end of the first upright 62 opposite that of pivoting to the arm element 52.

(28) On the first upright 62 sliding guides (not visible) extending parallel to the pivoting axis Y.sub.4 are provided. A second upright 64 is slidingly mounted on such guides. In operation, the deposition member 60 is oriented relative to the forming support 150 so that, subsequent to a thrust action exerted by the handling and deposition member 50a (and thus by the first upright 62) against the forming support 150, the second upright 64 may slide relative to the first upright 62 on said sliding guides along a direction perpendicular to the rotation axis X-X of the forming support 150.

(29) The second upright 64 is associated with each of brackets 63 through a respective elastic element 65 which, in the specific case illustrated herein, consists of a tension spring.

(30) As shown in FIG. 3, at the distal end of the second upright 64 relative to axis Y.sub.3 a holding device 70 of the reinforcing element 5 is associated, said holding device 70 facing the forming support 150. Thanks to such device 70 the reinforcing element 5 is prevented from falling once picked up by arm 41a, 41b of the pick up device 40, during the movement thereof towards the forming support 150.

(31) In the specific embodiment illustrated herein, the cords provided within the reinforcing element 5 are metal cords and the holding device 70 comprises a plurality of magnetic elements arranged on parallel rows (only one of these rows is indicated with reference numeral 71 in FIGS. 3-5) adapted to magnetically interact with said metal cords thus preventing the reinforcing element 5 from falling during the movement towards the forming support 150.

(32) In an alternative embodiment not shown, the cords provided within the reinforcing element 5 are of textile material and the holding device comprises a suction device or suction cup device.

(33) The deposition member 60 further comprises a pair of thin plate elements 80 each being associated, at a first free end 80a thereof, with the holding device 70 and at an opposite free end 80b thereof, to the free end of a respective bracket 63.

(34) Each thin plate element 80 preferably consists of a thin plate 81 of harmonic steel having a thickness preferably comprised between 0.1 mm and 3 mm, more preferably comprised between 0.3 mm and 1 mm.

(35) Said thin plate element 80 is flexible in any direction. In particular, as shall be better described hereinafter, the thin plate element 80 is deformed to bending, by the effect of the thrust action exerted by the handling and deposition member 50a, along two orthogonal directions inclined by a predetermined single with respect to the circumferential direction. Said bending deformations produce a bending deformation along the circumferential direction.

(36) The coupling between the free end 80a of each thin plate element 80 and the holding device 70 is of the firm type, that is, such as not to allow relative movements. The coupling between the opposite free end 80b of each thin plate element 80 and the free end of the respective bracket 63, on the other hand, is of the non firm type, that is, such as to allow relative movements.

(37) In particular, the free end 80b of each thin plate element 80 is associated to a support member 66 which in turn is associated with the free end of the respective bracket 63 (FIGS. 2, 4 and 5). As well shown in FIGS. 4 and 5, between each support member 66 and the free end of the respective bracket 63 a spherical hinge 67 and a spring 68 are provided. The spherical hinge 67 allows a freedom of movement to the support member 66 in the three axes, whereas the spring 68 limits the extent of such movement based on the value of the elastic constant thereof.

(38) The coupling between free end 80b of each thin plate element 80 and respective support member 66 comprises a sliding block 66a. Such block ensures the possibility of relative sliding between the free end 80b of the thin plate element 80 and the support, member 66 in the longitudinal direction of the thin plate element 80.

(39) Each thin plate element 80 is further associated, at a body portion defined between the opposite ends 80a, 80b, with a respective bracket 63, through a spring 69 for ensuring a fixed position at rest of the thin plate element 80.

(40) As clearly shown in FIGS. 4 and 5, the second upright 64 is capable of sliding on the first upright 62 for moving between a rest position, shown in FIG. 4, wherein the thin plate elements 80 are in a non deformed configuration, and an operating position, shown in FIG. 5, wherein the thin plate elements 80 are deformed according to the circumferential profile of the forming support 150. As shall be better explained hereinafter, such deformation takes place after the deposition member 60 is moved in abutment against the forming support 150, by the effect of the reaction exerted by the forming support 150 to a thrust action exerted by the handling and deposition member 50a against the forming support 150.

(41) An element 90 of elastomeric material is associated with the bottom surface of each thin plate element 80 (that is, on the surface that in operation is facing the forming support 150). Such element 90 preferably has a thickness comprised between about 1 mm and about 20 mm, more preferably between about 4 mm and about 10 mm.

(42) As well shown in FIG. 3, each element 90 comprises an end portion 91 arranged at the end portion 80a of the respective thin plate element. Such end portion 91 has a substantially rectangular shape in plan. The remaining portion 92 of each element 90 is shaped as a V or U and at each branch of the V or U it has a respective free end portion 92a having a rectangular shape in plan.

(43) Apparatus 100 further comprises a pair of idle rollers (not shown in the figures) movable perpendicularly to the rotation axis (X-X) of the forming support 150. Such rollers are coated with a deformable material and are arranged at opposite sides with respect to the centre line plane M of apparatus 100, each one in the proximity of a respective handling and deposition member 50a, 50b.

(44) As better described hereinafter, the above rollers are adapted to be activated when the reinforcing structure 1 has been completed at each end edge 2a of the carcass ply 2 laid on the forming support 150, for improving the compaction and the adhesion of said reinforcing structure 1 on the respective end edge 2a of the carcass ply 2.

(45) With reference to FIGS. 1-5, a preferred embodiment of the process carried out by apparatus 100 described above shall now be described. In such process, the positioning and the subsequent complete laying of the reinforcing element 5 are carried out only by the articulated arm comprising the handling and deposition member 50a (and 50b), and the deposition member 60.

(46) Before starting the above process, the forming support 150 is mounted on frame 101 and apparatus 100 is set up according to the features of the tyre to be made. The apparatus setup comprises the positioning of the cutting unit 30 at the desired cutting angle relative to the longitudinal direction G of the continuous reinforced band-like element 4.

(47) As described above, in the above process the reinforcing elements 5 are made in a sequence from the continuous reinforced band-like element 4 and alternately laid each on a respective end edge 2a of the carcass ply 2. In particular, the laying of a reinforcing element 5 on an end edge 2a takes place immediately after another reinforcing element 5 has been laid on the other end edge 2 and vice-versa, so as to make a reinforcing structure 1 on an end edge 2a while another reinforcing structure 1 is being made on the other end edge 2a.

(48) At the normal condition, therefore, there is a situation wherein at least one reinforcing element 5 has already been laid on one end edge 2a and at least another reinforcing element 5 has already been laid on the other end edge 2a. Such situation is shown in FIG. 1.

(49) For simplicity of description, forming of a reinforcing structure 1 at one of the end edges 2a of the carcass ply 2 shall be described hereinafter, it being understood that forming of the other reinforcing structure 1 at the other end edge 2a of the carcass ply 2 takes place in a totally similar manner.

(50) The continuous reinforced band-like element 4 is made to advance by a predetermined step along the above longitudinal direction G. During such advance, the pick up device 40 is made to rotate so as to bring arm 41a at the cutting unit 30. In this position, arm 41a is activated to pick up a free end of the continuous reinforced band-like element 4.

(51) At the same time as the rotation of the pick up 40, a synchronous rotation of the handling members 50a and 50b takes place.

(52) Afterwards, the cutting which obtains the reinforcing element 5 from the continuous reinforced band-like element (4) is carried out.

(53) As shown in FIG. 1, the reinforcing element 5 just made is moved by the pick up device 40 by about 90 to then transfer it to the handling and deposition member 50a, which in the meantime moves towards the pick up device 40.

(54) Afterwards, arm 41a of the pick up device 40 transfers the previously cut reinforcing element 5 to the handling and deposition member 50a.

(55) After having picked up the reinforcing element 5, the handling and deposition member 50a rotates about axis Y.sub.1 to bring the above reinforcing element 5 to the end edge 2a of the carcass ply 2. During such rotation, the reinforcing element 5 is held into position by the holding device 70, as shown in FIG. 3.

(56) Meanwhile, the forming support 150 is made to rotate by a predetermined angle corresponding to a movement in the circumferential direction by a portion of length equal to (if the circumferentially consecutive reinforcing elements 5 must be laid in contact and without overlapping) or greater than (if the reinforcing elements 5 must be laid leaving a free space between two circumferentially consecutive reinforcing elements) the pre-advance step of the continuous reinforced band-like element 4.

(57) FIG. 3 shows the particular orientation of the reinforcing element 5 with respect to the thin plate elements 80.

(58) In particular, it is first seen that the shape of elements 90 of elastomeric material is such as to ensure in any case contact with the reinforcing element 5 on the entire surface of the latter. This ensures an even thrust action on the entire surface above during the deposition of the reinforcing element 5 on the carcass ply 2.

(59) Moreover, again in FIG. 3 it is seen that a side of the reinforcing element 5 is oriented along a direction T inclined by a predetermined angle with respect to the longitudinal direction R of the thin plate elements 80. As a result, in order to lay the reinforcing element 5 so that the aforementioned side is oriented along the circumferential direction of the forming support 150, the deposition member 60 shall be oriented with respect to the forming support 150 so that the longitudinal direction R of the thin plate elements 80 is inclined by angle with respect to plane extension S of the circumferential direction of the forming support 150.

(60) Once the handling and deposition member 50a is in a radially external position with respect to the forming support 150, it moves towards the forming support 150 (and thus in a direction perpendicular to the rotation axis X-X of the forming support 150) up to preferably positioning a central portion of the reinforcing element 5 on a respective end edge 2a of the carcass ply 2.

(61) Afterwards, the handling and deposition member 50a exerts a predetermined thrust action (arrow B1 in FIG. 5) against the forming support 150 at said central portion of the reinforcing element 5. The reaction exerted by the forming support 150 to said thrust action causes a movement of the second upright 64 away from the forming support (arrow B2 in FIG. 5). In turn, such movement causes a bending deformation of the thin plate elements 80 according to the circumferential profile of the part of the surface of carcass ply 2 whereon said thin plate elements 80 are pressed. Finally, a gradual laying of the reinforcing element 5 on the carcass ply 2 is thus obtained; such gradual laying preferably starts at the central portion of the reinforcing element 5 and continues affecting always different portions of the reinforcing element 5 up to affecting the opposite free ends of said element.

(62) Because of the particular position taken by the thin plate elements 80 with respect to the forming support 150, a bending deformation of the reinforcing element 5 is obtained both along a direction inclined by angle with respect to the plane extension S of the circumferential direction R of the forming support 150, and along a direction orthogonal to said direction R. The combined effect of said bending deformations generates the desired bending deformation of the reinforcing element 5 in the circumferential direction.

(63) The process described above is repeated cyclically through the handling and deposition members 50a and 50b, each time laying a new reinforcing element 5 up to completing the reinforcing structures 1 on both end edges 2a of the carcass ply 2.

(64) Afterwards, each one of the idle rollers described above is brought in contact with the respective reinforcing structure 1 just formed. The rotation of the forming support 150 is then activated for at least one full revolution. The action of the rollers during such rotation produces the compaction of the reinforcing structures 1 on the respective end edges 2a of the carcass ply 2.

(65) Of course, a man skilled in the art may make further changes and variants to the invention described hereinbefore in order to meet specific and contingent application requirements, these changes and variants in any case falling within the scope of protection defined by the following claims.