Process and apparatus for building tyres for vehicle wheels

Abstract

A process for building tyres for vehicle wheels comprises: arranging a semifinished product cut to size (13) and positioning it on a support surface (20); detecting positions of a plurality of points (P1-Rn) of the semifinished product (13) positioned on the support surface (20) while the support surface (20) and the semifinished product (13) are stationary, so as to determine a positioning of the semifinished product (13) with respect to the support surface (20); arranging one end of the support surface (20) close to a surface (14) radially external to the building drum (15); winding the semifinished product (13) on the radially external surface (14) by advancing the support surface (20) towards the building drum (15) and by rotating the building drum (15) around a main axis (X-X) thereof. During the winding, provision is made for causing a relative movement between the building drum (15) and the support surface (20) along a direction (48) parallel to the main axis (X-X) as a function of the positioning of the semifinished product (13) with respect to the support surface (20), so as to adjust a positioning of the semifinished product (13) on the radially external surface (14).

Description

[0001] “Process and apparatus for building tyres for vehicle wheels”

[0002] DESCRIPTION

[0003] Technical field of the invention

[0004] The present invention relates to a process and an apparatus for building tyres for vehicle wheels. The present invention is situated in the scope of the processes and apparatuses for producing tyres for vehicle wheels.

[0005] Definitions

[0006] With “continuous semifinished product” it is intended a belt-like element, i.e. flat, having a length equal to even hundreds or thousands of times its own width.

[0007] With “semifinished product cut to size” it is intended a piece of the continuous semifinished product having a length normally greater than its own width and substantially equal to the length of a component of the tyre to be built or of a part thereof.

[0008] With “surface radially external to the building drum” it is intended a surface belonging to said building drum and facing radially outward or a surface of a component already wound on the building drum and facing radially outward.

[0009] The terms "axial", "axially", "radial", "radially", “circumferential” and “circumferentially” are used with reference to a building drum on which semifinished products are deposited for building the tyre or with reference to a tyre.

[0010] In particular, with the terms "axial" and "axially" it is intended references / sizes arranged / measured or extended in a direction substantially parallel to a main rotation axis of the building drum or of the tyre.

[0011] With the terms "radial" and "radially" it is intended references / sizes arranged / measured or extended in a direction perpendicular to the main rotation axis of the building drum or of the tyre and lying in a plane comprising such rotation axis.

[0012] With the terms “circumferential” and “circumferentially” it is intended references / sizes arranged / measured or extended along a circumference that is extended around the main rotation axis of the building drum or of the tyre. With “curvature ratio” of the tyre it is intended the ratio between the distance comprised between the radially highest point of the tread band and the maximum transverse section width of the tyre, and the same maximum transverse section width of the tyre, in a transverse section thereof.

[0013] State of the art

[0014] In the field of tyre manufacturing, the document EP3141382 illustrates a method and a device for depositing belt strips in cylindrical form without generating undulations. The device comprises a forming drum, a first conveyor belt placed upstream of the forming drum, a second conveyor belt placed upstream of the first conveyor belt, a pre-winding position sensor, which detects positions of a reference line on a belt element placed on the first conveyor belt, and a post-winding position sensor, which detects positions of a reference line on the forming drum. During the winding of the belt element on the forming drum, based on data detected by the prewinding position sensor and position data of the reference line of the forming drum, a controller controls a movement mechanism for moving the forming drum in the direction of the width of the drum with respect to the conveyor belt in a manner such that the position of the reference line on the belt element matches with the position of the reference line on the forming drum.

[0015] The document WO2015069102A1 illustrates a method and a centring group for centring a tyre component. The method comprises: positioning and conveying the tyre component from a first conveyor towards a second conveyor, determining the position of a first longitudinal edge of the tyre component, transversely moving the first conveyor and hence aligning the first longitudinal edge along a first reference on the second conveyor, conveying the tyre component from the first conveyor to the second conveyor, determining the position of a second longitudinal edge, conveying the tyre component from the second conveyor towards a drum, laterally moving the drum in order to align the centre of the tyre component with the centre of a desired position of application of the tyre component on the drum and conveying the tyre component from the second conveyor to the drum.

[0016] Summary

[0017] In the context of the processes and apparatuses for building tyres for vehicle wheels which provide for the winding of a semifinished product cut to size on a building drum, like those described above, the Applicant has perceived the need to improve the accuracy of the positioning of the semifinished products on the building drum and hence the quality of the produced tyres.

[0018] The Applicant has in fact observed that, after the unwinding from a respective reel, the semifinished product can be moved and deformed during the transport towards the building drum, in particular when it is positioned and advanced on conveyor belts and when it is transferred from one conveyor belt to the next, for example according to that illustrated in the abovementioned documents.

[0019] The Applicant has in particular observed that, when the semifinished product cut to size reaches the conveyor belt closest to the building drum, i.e. on the conveyor belt configured for applying and winding the sem ifinished product cut to size on a surface radially external to the building drum, it is possible that the position of said semifinished product or of several portions thereof with respect to said conveyor belt are no longer known to the system and that the respective longitudinal edges are not perfectly aligned with a transport direction. This may involve an improper positioning of the semifinished product on the surface radially external to the building drum.

[0020] The Applicant has also observed that the controls illustrated in the abovementioned documents do not allow resolving such drawback, since the positions of the belt layer of EP3141382 and of the tyre component of WO2015069102A1 are detected while the belt layer and the tyre component are moving and therefore can be subjected to further deformations and / or misalignments before reaching the respective drums.

[0021] The Applicant has therefore perceived the need to provide for detecting, with greater precision, the position and the shape of the semifinished product cut to size when the latter is situated on the conveyor belt closest to the building drum and to use the data detected in this mode for controlling a relative axial movement between the building drum and said conveyor belt during the winding.

[0022] The Applicant has finally found that the above objective and still others can be obtained by detecting positions of points of the sem ifinished product cut to size while the latter is stationary and placed on a support surface situated immediately upstream of the building drum.

[0023] According to a first aspect, the invention relates to a process for building tyres for vehicle wheels. Preferably, provision is made for forming at least one component of a tyre on a building drum.

[0024] Preferably, said component is formed through arranging a semifinished product cut to size and positioning it on a support surface.

[0025] Preferably, said component is formed through detecting positions of a plurality of points of the semifinished product positioned on the support surface while the support surface and the semifinished product are stationary, so as to determine a positioning of said semifinished product with respect to said support surface.

[0026] Preferably, said component is formed through arranging one end of said support surface close to a surface radially external to the building drum; winding the semifinished product on the radially external surface by advancing the support surface towards the building drum and by rotating said building drum around a main axis thereof.

[0027] Preferably, said component is formed through during the winding of the semifinished product on the radially external surface, causing a relative movement between the building drum and the support surface along a direction parallel to the main axis as a function of said positioning of the sem ifinished product with respect to said support surface, so as to adjust a positioning of the semifinished product on said radially external surface.

[0028] In accordance with a second aspect, the invention relates to an apparatus for building tyres for vehicle wheels.

[0029] Preferably, a building drum and a conveyor are provided, the conveyor having a support surface configured for being moved along a feed direction and towards the building drum.

[0030] Preferably, an optical reader is provided, the optical reader being positioned above the support surface.

[0031] Preferably, a motor is provided, the motor being operatively coupled to the building drum in order to rotate it around a main axis thereof.

[0032] Preferably, first movement devices are provided for generating a relative movement between said building drum and said support surface along a direction parallel to said main axis.

[0033] Preferably, a control unit is provided, the control unit being operatively associated with the conveyor, with the optical reader, with the motor, with the first movement devices. Preferably the control unit is configured for detecting, through the optical reader, positions of a plurality of points of a semifinished product cut to size positioned on said support surface while the support surface is stationary.

[0034] Preferably, the control unit is configured for determining, starting from said positions of a plurality of points of said semifinished product, a positioning of said semifinished product with respect to said support surface.

[0035] Preferably, the control unit is configured for arranging one end of said support surface close to a surface radially external to the building drum.

[0036] Preferably, the control unit is configured for controlling the conveyor and the motor for winding the semifinished product on the surface radially external to the building drum by advancing the support surface along the feed direction and by rotating said building drum around the main axis thereof.

[0037] Preferably, the control unit is configured for controlling the first movement devices in order to cause a relative movement between the building drum and the support surface and along the direction parallel to the main axis as a function of said positioning of the semifinished product with respect to said support surface, so as to adjust a positioning of the semifinished product on said radially external surface. The Applicant deems that the present invention contributes to improving the quality of the produced tyres and to reducing the number of tyres that are not in compliance. The Applicant has in particular verified that the present invention allows knowing, with accuracy, the positions of the points of the semifinished product cut to size just before it is wound on the building drum and hence correcting in real time the relative position between the building drum and the semifinished product cut to size during the winding, increasing the accuracy of its positioning.

[0038] The invention according to any one of the aforesaid aspects may have one or more of the preferred features described hereinbelow.

[0039] Preferably, the building drum is a cylindrical drum.

[0040] Preferably, detecting the positions of the plurality of points of the semifinished product comprises: acquiring, through an optical reader, a digital image of the semifinished product positioned on the support surface.

[0041] Preferably, detecting the positions of the plurality of points of the semifinished product comprises: calculating the positions of the plurality of points from the digital image. Preferably, the control unit is configured for: acquiring, through the optical reader, a digital image of the semifinished product positioned on the support surface.

[0042] Preferably, the control unit is configured for: calculating the positions of the plurality of points from the digital image.

[0043] The Applicant has verified that the digital image contains many more points than those used in the calculation of the positions and for this reason allows selecting the most suitable points from which said positions are detected.

[0044] The Applicant has verified that, starting from the digital image of the semifinished product cut to size, it is possible to detect the position of the head and the form of a head edge, the form of longitudinal edges, the longitudinal length and the width, the profile of a tail edge and hence of the cut.

[0045] Preferably, the optical reader comprises a video camera, more preferably CCD. Preferably, the video camera is of 2D or 3D type.

[0046] The Applicant has verified that the scanning with the 2D video camera allows detecting the profile of the semifinished product or possible visual references present on the semifinished product and the 3D video camera allows detecting, in addition to the profile, also the thickness such to be able to identify possible joints present on the semifinished product.

[0047] Preferably, the video camera has a resolution comprised between 0.05 mm and 0.5 mm, e.g. 0.1 mm.

[0048] Preferably, the optical reader is fixed.

[0049] Preferably, the optical reader has a visual field such to frame the entire support surface or the entire semifinished product cut to size positioned on said support surface.

[0050] The Applicant has verified that the fixed optical reader allows acquiring the entire semifinished product cut to size without having to provide for movement systems placed above the support surface which would render the apparatus bulky and more complex.

[0051] Preferably, provision is made for moving the optical reader above the semifinished product in order to acquire the digital image.

[0052] Preferably, second movement devices are operatively coupled to the optical reader. Preferably, the control unit is configured for controlling the second movement devices and moving the optical reader above the support surface. Preferably, the second movement devices comprise: a guide placed above the support surface and extended parallel to the feed direction.

[0053] Preferably, the optical reader is coupled to the guide.

[0054] Preferably, a respective actuator is coupled to the optical reader and to the guide in order to move said optical reader along the guide.

[0055] Preferably, the control unit is operatively connected to the respective actuator. Preferably, the guide is extended for an entire length of the support surface.

[0056] The Applicant has verified that the movement of the optical reader allows acquiring the digital image of the entire semifinished product by using an optical reader that is relatively simple, that does not necessarily have to have a visual field wide enough to include the entire semifinished product.

[0057] Preferably, the points of said plurality of points belong to successive transverse sections of the semifinished product.

[0058] Preferably, through movements along the direction parallel to the main axis, the building drum is brought, with respect to the support surface, in a plurality of successive axial positions.

[0059] Preferably, each axial movement of the building drum is comprised between 0.5 mm and 5 mm, e.g. 1 -2 mm.

[0060] Preferably, each axial position corresponds to a transverse section of the semifinished product.

[0061] Preferably, the control unit is configured for: calculating positions of points belonging to successive transverse sections of the semifinished product.

[0062] Preferably, the control unit is configured for: bringing the building drum, with respect to the support surface, into a plurality of successive axial positions.

[0063] Preferably, each axial position corresponds to a transverse section of the semifinished product.

[0064] Preferably, a number of successive transverse sections is greater than 10.

[0065] Preferably, a number of successive transverse sections is lower than 50.

[0066] Preferably, the successive transverse sections are equidistant from each other.

[0067] Preferably, a distance between two successive transverse sections is equal to or greater than 2 cm.

[0068] Preferably, a distance between two successive transverse sections is equal to or lower than 15 cm. The Applicant has verified that the calculation of positions of a discrete and limited number of points corresponding to the abovementioned sections allows containing the necessary calculation power.

[0069] Preferably, movements between successive axial positions of the building drum with respect to the support surface are continuous and connected to each other.

[0070] The Applicant has verified that, in this manner, one prevents the formation of steps on the semifinished product deposited on the building drum.

[0071] Preferably, the control unit is configured for: calculating connecting functions between the successive axial positions.

[0072] Preferably, the control unit is configured for: moving the building drum with respect to the support surface between successive axial positions according to said connecting functions.

[0073] The Applicant has verified that the movement of the drum according to the connecting functions allows depositing the semifinished product with precision, without using an overly high number of points.

[0074] Preferably, the points of said plurality of points belong to at least one between a first longitudinal edge and a second longitudinal edge of the semifinished product.

[0075] Preferably, the plurality of points comprises pairs of points.

[0076] Preferably, each pair of points comprises a first point placed on the first longitudinal edge and a second point placed on the second longitudinal edge.

[0077] Preferably, the points of each pair are situated on a line parallel to the main axis.

[0078] Preferably, the points of each pair are situated on a respective transverse section of the semifinished product.

[0079] Preferably, the building drum is moved with respect to the support surface and along the direction parallel to the main axis so as to position the first longitudinal edge and the second longitudinal edge along respective reference circumferences of the radially external surface.

[0080] Preferably, the points of said plurality of points belong to a middle line of the semifinished product.

[0081] Preferably, the building drum is moved with respect to the support surface and along the direction parallel to the main axis so as to centre the middle line with respect to a reference circumference of the radially external surface.

[0082] Preferably, the reference circumference is a median circumference of the building drum. Preferably, each point of the middle line is situated on a respective transverse section of the semifinished product.

[0083] Preferably, the points of said plurality of points comprise at least one point belonging to a head edge of the semifinished product.

[0084] Preferably, the points of said plurality of points comprise at least one point belonging to a tail edge of the semifinished product.

[0085] The Applicant has verified that the knowledge of the position of the head of the semifinished product allows rendering the first contact of the semifinished product with the surface radially external to the building drum more suitable for building.

[0086] Preferably, provision is made for, or the control unit is configured for: comparing the detected positions of the plurality of points with a profile of a virtual reference semifinished product.

[0087] Preferably, the control unit is configured for emitting a signal of non-compliance if the detected positions of the plurality of points differ from positions of corresponding points of said profile of the virtual reference semifinished product with respect to an acceptable threshold value.

[0088] Preferably, provision is made for, or the control unit is configured for: discarding the semifinished product (more preferably unloading it from the distal end of the conveyor) before winding said semifinished product on the radially external surface if the detected positions of the plurality of points differ from positions of corresponding points of said profile of the virtual reference semifinished product beyond an acceptable threshold value. Said threshold preferably being measured as distance over unit of length.

[0089] Preferably, the threshold is evaluated based on the variation of the transverse positions, i.e. parallel to the main axis “X-X”, of the points “Pi-Pn” belonging to successive transverse sections.

[0090] Preferably, let x and y be the coordinates of a point of said plurality of points “Pi-Pn” on the first longitudinal edge or on the second longitudinal edge, the semifinished product cut to size is not compliant if a transverse position Xi of a point on said first longitudinal edge or on said second longitudinal edge with respect to a transverse position of a preceding point xi-i on the same first longitudinal edge or on the same second longitudinal edge is such that: (xi - Xi-i) / (yi - ys-i) <= S; in which (xi - xi-i) is the transverse movement of the first longitudinal edge or of the second longitudinal edge between the point PM and the point Pi, (yi - ys-1 ) is the longitudinal distance between the point Pi-1 and the point Pi and S is the threshold.

[0091] Preferably, acceptable threshold values S are comprised between 0.017 and 0.025, more preferably equal to 0.02.

[0092] The Applicant has verified that the invention allows signalling and possibly discarding semifinished products cut to size that are not compliant in automatic manner and before they are wound on the building drum. In this manner, one avoids having to remove the semifinished product already deposited on the drum and / or building non-compliant tyres that must then be discarded once completed.

[0093] Preferably, along the direction parallel to the main axis, the support surface is fixed and the building drum is movable.

[0094] Preferably, the conveyor is fixed along the direction parallel to the main axis and the first movement devices are operatively coupled to the building drum for moving said building drum along said direction parallel to the main axis.

[0095] Preferably, along the direction parallel to the main axis, the support surface is movable and the building drum is fixed.

[0096] Preferably, the building drum is fixed along the direction parallel to the main axis and the first movement devices are operatively coupled to the conveyor for moving said conveyor along said direction parallel to the main axis.

[0097] Preferably, the conveyor comprises a conveyor belt wound on motorised rollers and the support surface is defined by an upper branch of the conveyor belt.

[0098] Preferably, the control unit is configured for maintaining stopped the conveyor belt during the detection, through the optical reader, of the positions of the plurality of points of the semifinished product.

[0099] Preferably, the conveyor is movable along the feed direction between a first position and a second position.

[0100] Preferably, in the first position, a distal end of the conveyor is spaced from the surface radially external to the building drum.

[0101] Preferably, in the second position, the distal end of the conveyor is associated with the surface radially external to the building drum in order to transfer the semifinished product from the support surface to the radially external surface.

[0102] Preferably, the apparatus comprises an actuator coupled to the conveyor in order to move it between the first position and the second position. Preferably, the conveyor translates or oscillates between the first position and the second position.

[0103] Preferably, a base is abutted against the ground and the conveyor is mounted on the base in order to be moved between the first position and the second position.

[0104] Preferably, the conveyor comprises wheels abutted against the base and configured for moving the conveyor between the first position and the second position.

[0105] Preferably, in the second position, the distal end of the conveyor is situated below the building drum.

[0106] Preferably, in the second position, the distal end of the conveyor is tangent to the surface radially external to the building drum.

[0107] Preferably, provision is made for retaining the semifinished product cut to size so that it is not moved laterally on the support surface during the winding on the building drum.

[0108] Preferably, the conveyor comprises retention devices configured for preventing lateral movements of the semifinished product cut to size on the support surface during the winding of said semifinished product cut to size on the building drum. Preferably, the retention devices are of suction or magnetic type.

[0109] Preferably, arranging the semifinished product cut to size comprises: unwinding a continuous semifinished product from a reel.

[0110] Preferably, arranging the semifinished product cut to size comprises: positioning an initial section of the continuous semifinished product unwound from the reel on an auxiliary support surface placed upstream of said support surface.

[0111] Preferably, arranging the semifinished product cut to size comprises: transferring the initial section on the support surface.

[0112] Preferably, arranging the semifinished product cut to size comprises: cutting the continuous semifinished product at a cutting line situated upstream of the initial section in order to obtain the semifinished product cut to size positioned on the support surface.

[0113] Preferably, positioning the initial section on the auxiliary support surface comprises: adjusting a transverse position of the initial section of the semifinished product unwound from the reel with respect to the auxiliary support surface while said initial section is deposited on said auxiliary support surface. Preferably, transferring the initial section on the support surface comprises: adjusting a transverse position of the initial section with respect to the support surface while said initial section is transferred onto the support surface.

[0114] Preferably, an auxiliary conveyor is placed upstream of the conveyor and has an auxiliary support surface configured for being moved along a respective auxiliary feed direction and towards the conveyor.

[0115] Preferably, the auxiliary conveyor comprises an auxiliary conveyor belt wound on motorised rollers and the auxiliary support surface is defined by an upper branch of the auxiliary conveyor belt.

[0116] Preferably, a reel-holder is operatively situated upstream of the auxiliary conveyor and carries or is configured for carrying a reel of a continuous semifinished product. Preferably, a pre-centring device is operatively situated between the reel-holder and the auxiliary conveyor in order to adjust a transverse position of the continuous semifinished product unwound from the reel with respect to the auxiliary support surface.

[0117] Preferably, the pre-centring device comprises: a movable guide interposed between the reel-holder and the auxiliary conveyor for moving the continuous semifinished product transversely; a pre-centring optical reader situated at the movable guide and configured for detecting a position of a portion of the continuous semifinished product situated between the movable guide and the auxiliary conveyor.

[0118] Preferably, the control unit is operatively associated with the pre-centring device in order to move the movable guide as a function of the position of the portion of the continuous semifinished product detected through the pre-centring optical reader. Preferably, a cutting device is situated on the auxiliary conveyor and is configured for cutting the continuous semifinished product placed on the auxiliary support surface.

[0119] Preferably, the cutting device has a blade movable along a trajectory that is tilted with respect to the auxiliary feed direction.

[0120] Preferably, the auxiliary conveyor is movable along a direction transverse to the auxiliary feed direction.

[0121] Preferably, the apparatus comprises an auxiliary actuator coupled to the auxiliary conveyor in order to move it along the direction transverse to the auxiliary feed direction. Preferably, an auxiliary base is abutted against the ground and the auxiliary conveyor is mounted on the auxiliary base in order to be moved along said direction transverse to the auxiliary feed direction.

[0122] Preferably, the auxiliary conveyor comprises wheels abutted against the auxiliary base and configured for moving the auxiliary conveyor along said direction transverse to the auxiliary feed direction.

[0123] Preferably, a centring optical reader is situated between the auxiliary conveyor and the conveyor and is configured for detecting a position of a portion of the continuous semifinished product situated between the auxiliary conveyor and the conveyor.

[0124] Preferably, the control unit is operatively associated with the centring optical reader and with the auxiliary actuator, in order to move the auxiliary conveyor along the direction transverse to the auxiliary feed direction as a function of the position of the portion of the continuous semifinished product detected through the centring optical reader.

[0125] Preferably, the built tyres are tyres for motorcycle.

[0126] Preferably, the built tyres have a curvature ratio equal to or greater than 0.15.

[0127] The Applicant has verified that, for the tyres for motorcycle and more generally for the tyres that have a high curvature ratio, the centring of the semifinished products contributes significantly in obtaining a quality product, so that the solution of the present invention results particularly effective.

[0128] Preferably, the semifinished product cut to size is a belt layer.

[0129] Preferably, the semifinished product cut to size is a carcass ply.

[0130] Preferably, the semifinished product cut to size comprises textile, metallic or hybrid cords, tilted with respect to a circumferential direction of the building drum and of the built tyre.

[0131] Preferably, provision is made for winding successive belt layers on the building drum, wherein a first belt layer has cords tilted in one sense with respect to the circumferential direction and a second belt layer has cords tilted in an opposite sense with respect to said circumferential direction.

[0132] Preferably, provision is made for winding successive carcass plies on the building drum, wherein a first carcass ply has cords tilted in one sense with respect to the circumferential direction and a second carcass ply has cords tilted in a sense that is opposite with respect to said circumferential direction. Further features and advantages will be clearer from the detailed description of preferred but not exclusive embodiments of a process and of an apparatus for building tyres for vehicle wheels according to the present invention.

[0133] Description of the drawings

[0134] Such description will be set forth hereinbelow with reference to the enclosed drawings, provided only as a non-limiting example, in which: figure 1 illustrates a schematic three-dimensional view of an apparatus for building tyres for vehicle wheels according to the present invention; figures 2 and 3 respectively illustrate a top view and a side elevation view of the apparatus of figure 1 in an operative configuration; figures 4 and 5 respectively illustrate a top view and a side elevation view of the apparatus of figure 1 in a different operative configuration; figures 6 and 7 respectively illustrate a top view and a side elevation view of the apparatus of figure 1 in a different operative configuration; figure 6A is a top view of a part of the apparatus in the operative configuration of figure 6 and 7; figures 8 and 9 respectively illustrate a top view and a side elevation view of the apparatus of figure 1 in a different operative configuration; figures 10 and 11 respectively illustrate a top view and a side elevation view of the apparatus of figure 1 in a different operative configuration; figure 12 illustrates a flow diagram of a process for building tyres for vehicle wheels according to the present invention; figure 13 is a radial half-section of a tyre for motor vehicles attained through the apparatus and in accordance with the process according to the present invention; figure 14 is a radial section of a tyre for motorcycles attained through the apparatus and in accordance with the process according to the present invention.

[0135] Detailed description

[0136] Reference number 1 overall indicates an apparatus for building tyres for vehicle wheels in accordance with the present invention. The apparatus 1 is configured for actuating a process for building tyres for vehicle wheels according to the present invention. The apparatus 1 is part of a plant for building tyres for vehicle wheels, not illustrated here in its entirety.

[0137] A tyre 2 for motor vehicles is for example illustrated in figure 13 and comprises a carcass structure 3 having two carcass plies 4a, 4b. A layer of impermeable elastomeric material or so-called liner 5 can be applied inside the carcass ply / plies 4a, 4b. Two anchoring annular structures 6, each comprising a so-called bead core 6a bearing an elastomeric filler 6b in radially outer position, are engaged with respective end flaps of the carcass plies 4a, 4b. The anchoring annular structures 6 are integrated in proximity to zones normally identified with the name “beads”, at which there is normally the engagement between the tyre 2 and a respective mounting rim. A belt structure 8 comprising multiple belt layers 8a, 8b is circumferentially applied around the carcass plies 4a, 4b, and a tread band 9 is circumferentially superimposed on the belt structure 8. Each belt layer 8a, 8b comprises a plurality of reinforcement cords, textile or metallic, parallel to each other, immersed in an elastomeric material matrix and tilted by an angle predefined with respect to a circumferential extension direction “Y-Y” of the tyre 2. The reinforcement cords of two adjacent belt layers 8a, 8b are preferably crossed. The belt structure can also comprise a so-called zero-degree layer (not illustrated), in which a rubber-coated hybrid, metallic or textile cord is wound circumferentially in radially outer position with respect to the belt layers 8a, 8b. The belt structure 8 can be associated with so-called “under-belt inserts” 10, each situated between the carcass plies 4a, 4b and one of the axially opposite terminal edges of the belt structure 8. Two sidewalls 11 , each extended from the corresponding bead to a corresponding lateral edge of the tread band 9, are applied in laterally opposite positions on the carcass plies 4a, 4b.

[0138] Figure 14 illustrates a tyre 2 for motorcycles which comprises substantially the same components illustrated above with reference to figure 13, which are marked with the same reference numbers. Shown in figure 14 is the distance (also termed arrow “f”) comprised between the radially outermost point of the tread band 9, the maximum transverse section width (also termed maximum chord “C”) and the height “H“, intended as radial distance between the beads and said radially highest point of the tread band 9. The tyre 2 for motorcycles has a curvature ratio “f / C” higher than that of the tyre of figure 13 and usually greater than 0.15. The abovementioned components of the tyre 2 are built on one or more building drums by moving said building drums between different work stations, at each of which suitable devices apply, on the building drum(s), different semifinished products in order to obtain the aforesaid components. In a preferred embodiment, the tyre production plant (not illustrated in its entirety) comprises a carcass building line, at which one or more building drums are sequentially moved between different work stations arranged to form, on each building drum, a carcass sleeve comprising the carcass plies 4a, 4b, the liner 5, the anchoring annular structures 6 and possibly at least one part of the sidewalls 11 . Simultaneously, in an external sleeve building line, one or more building drums are sequentially moved between different work stations arranged for form, on each building drum, an external sleeve, comprising at least the belt structure 8, the tread band 9, and possibly at least one part of the sidewalls 11. The plant also comprises an assembly station at which the external sleeve is coupled to the carcass sleeve. The built tyres 2 are transferred to a vulcanising and moulding unit.

[0139] In a different building mode, it too not illustrated, the external sleeve is attained directly on the radially external surface of the carcass sleeve, already toroidally shaped.

[0140] The apparatus 1 illustrated in figures 1 to 11 is arranged to cut to size a continuous semifinished product 12 in order to attain a semifinished product cut to size 13 and the winding of the latter on a surface 14 radially external with respect to a cylindrical building drum 15 for the formation of one of the abovementioned belt layers 8a, 8b. The present invention is in any case applicable for attaining components of different type, such as for example carcass plies.

[0141] The apparatus 1 comprises a conveyor 16 mounted on a base 17 abutted against the ground. The conveyor 16 comprises a conveyor belt 18 wound on motorised rollers 19, i.e. operatively connected to a respective motor adapted to rotate them, not illustrated. An upper branch of the conveyor belt 18 defines a support surface 20 movable along a feed direction 21. A distal end 16A of the conveyor 16 is situated in proximity to the building drum 15 and the feed direction 21 is directed towards said building drum 15.

[0142] The conveyor 16 comprises wheels or rollers 22 abutted against rails 23 situated or made on an upper portion of the base 17. The rails 23 are parallel to the feed direction 21. An actuator, not illustrated, is coupled to the conveyor 16 in order to translate it, due to the wheels 22 and to the rails 23, along a direction parallel to the feed direction 21 and in two senses 24, 25 (figure 8), between a first position and a second position. In the first position (illustrated in figures 1 -7), the distal end 16A of the conveyor 16 is spaced from the surface 14 radially external to the building drum 15. In the second position, the distal end 16A of the conveyor 16 is situated below the building drum 15, associated with the surface 14 radially external to the building drum 15 and tangent to said radially external surface 14, as in figures 8-11 .

[0143] The conveyor 16 also comprises retention devices of suction type, not illustrated in the figures, configured for suctioning air through the upper branch of the conveyor belt 18.

[0144] The apparatus 1 comprises an auxiliary conveyor 26 placed upstream of the conveyor and mounted on an auxiliary base 27 abutted against the ground. The auxiliary conveyor 26 comprises an auxiliary conveyor belt 28 wound on motorised rollers 29, i.e. operatively connected to a respective motor adapted to rotate them. An upper branch of the auxiliary conveyor belt 28 defines an auxiliary support surface 30 movable along an auxiliary feed direction 31 . A distal end 26A of the auxiliary conveyor 26 is situated in proximity to a proximal end 16B of the conveyor 16 and the auxiliary feed direction 31 is directed towards said conveyor 16.

[0145] The auxiliary conveyor 26 comprises wheels or rollers 32 abutted against rails 33 situated or made on an upper portion of the auxiliary base 27. The rails 33 are perpendicular to the auxiliary feed direction 31 , so that the auxiliary conveyor 26 is movable along a direction 34 transverse to the auxiliary feed direction 31. An auxiliary actuator, not illustrated, is coupled to the auxiliary conveyor 26 in order to move it, due to the respective wheels 32 and rails 33, along the direction 34 transverse to the auxiliary feed direction 31 , in one sense or in the opposite sense (figure 4).

[0146] A cutting device 35 is situated above the auxiliary support surface 30 of the auxiliary conveyor 26. The cutting device 35 comprises a tilted guide 36 which carries a blade 37 movable along the tilted guide 36 and hence along a trajectory tilted with respect to the auxiliary feed direction 31. The tilted guide 36 is parallel to the auxiliary support surface 30 and is tilted with respect to the auxiliary feed direction 31 by an angle which, in the illustrated embodiment, is about 30°. The blade 37 is moved along the tilted guide 36 and in proximity to the auxiliary support surface 30 through a respective actuator, not illustrated in the figures. A reel-holder 38 is operatively situated upstream of the auxiliary conveyor 26 and carries or is configured for carrying a reel 39 of the continuous semifinished product 12. In the illustrated embodiment, the reel-holder 38 is positioned below a part of the auxiliary conveyor 26 which projects overhanging from the auxiliary base 27.

[0147] A pre-centring device 40 is positioned at a proximal end 26B of the auxiliary conveyor 26 and is operatively situated between the reel-holder 38 and the auxiliary conveyor 26. The pre-centring device 40 comprises a movable guide defined by a series of vertical rollers 41 spaced from each other and aligned along a transverse direction 42, i.e. parallel to the direction 34 transverse to the auxiliary feed direction 31. A respective actuator, not illustrated, is configured for moving together the vertical rollers 41 in the abovementioned transverse direction 42 and in the two senses (figure 2).

[0148] The apparatus 1 also comprises an optical reader 43 positioned above the support surface 20, a centring optical reader 44 situated between the auxiliary conveyor 26 and the conveyor 16 and above the auxiliary conveyor 26 and the conveyor 16, and a pre-centring optical reader 45 situated above the movable guide.

[0149] The building drum 15 is operatively coupled to a motor 46, schematically represented in the enclosed figures, configured for rotating said building drum 15 around a main axis “X-X” thereof. The building drum 15 is also operatively coupled to first movement devices 47, schematically represented in the enclosed figures, configured for moving the building drum 15 along a direction 48 parallel to the main axis “X-X” in one sense or in the opposite sense (figures 1 and 10). Therefore, the first movement devices 47 generate a relative movement between the building drum 15 and the support surface 20 along the abovementioned direction 48 parallel to said main axis “X-X”.

[0150] Second movement devices 49 are operatively coupled to the optical reader 43 in order to move it above the support surface 20. The second movement devices 49 comprise a guide 50 placed above the support surface 20, extended parallel to the feed direction 21 and substantially for an entire length of the support surface 20. The optical reader 43 is coupled to the guide 50 and a respective actuator, not illustrated, is coupled to the optical reader 43 and to the guide 50 in order to move said optical reader 43 along the guide 50 in one sense 50A or in the opposite sense 50B (figures 1 , 6 and 7). For example, the optical reader comprises a video camera CCD of 2D or 3D type with a resolution comprised between 0.05 mm and 0.5 mm, e.g. 0.1 mm.

[0151] The apparatus 1 comprises a control unit 51 operatively associated with the conveyor 16, with the optical reader 43, with the motor 46, with the first movement devices 47, with the second movement devices 49. For the sake of simplicity, figures 1 and 10 schematically indicate only the connections with the motor 46, the first movement devices 47, the second movement devices 49. The control unit 51 is an electronic unit provided with a CPU, with a memory and with input and output devices.

[0152] The control unit 51 is also operatively connected to the other above-described elements of the apparatus 1 in order to determine the operation thereof in accordance with the process for building tyres for vehicle wheels of the invention detailed hereinbelow according to an exemplifying embodiment illustrated in figures 2-11 and in the flow diagram of figure 12.

[0153] The continuous semifinished product 12 of the reel 39 comprises textile cords (or alternatively metallic or hybrid cords) immersed in an elastomeric material. The textile cords are parallel to each other and tilted with respect to the longitudinal extension of the continuous semifinished product 12.

[0154] The continuous semifinished product 12 is unwound from the reel 39 and an initial section of the continuous semifinished product 12 which comprises a head of said continuous semifinished product 12 is positioned on the auxiliary support surface 30 at the proximal end 26B of the auxiliary conveyor 26. The continuous semifinished product 12 lies between the two vertical rollers 41 of the pre-centring device 40 (figure 2 and 3). The auxiliary support surface 30 is advanced along the auxiliary feed direction 31 and carries therewith the initial section of the continuous semifinished product 12.

[0155] During such advancement, the continuous semifinished product 12 is moved transversely in one sense or in the opposite sense in order to adjust a transverse position thereof with respect to the auxiliary support surface 30 and thus pre-centre the continuous semifinished product 12 on said auxiliary support surface 31. For such purpose, the pre-centring optical reader 45 detects a position of one portion of the continuous semifinished product 12 situated between the movable guide and the auxiliary conveyor 26 and the control unit 51 moves the movable guide in the transverse direction 42 as a function of the position of the portion of the continuous semifinished product 12 detected through the pre-centring optical reader 45.

[0156] Through the movement of the auxiliary support surface 30 along the auxiliary feed direction 31 , the head of the continuous semifinished product 12 is brought up to the distal end 26A of the auxiliary conveyor 26 and then transferred onto the support surface 20 at the proximal end 16B of the conveyor 16 (figures 4 and 5). The support surface 20 advances along the feed direction 21 , transporting therewith the continuous semifinished product 12. Simultaneously, a transverse position of the initial section is adjusted with respect to the support surface 20 by moving the auxiliary conveyor 26 along the direction 34 transverse to the auxiliary feed direction 31 as a function of the position of the continuous semifinished product 12 detected through the centring optical reader 44. In this manner, the continuous semifinished product 12 is centred on the support surface 20.

[0157] The support surface 20 is advanced along the feed direction 21 until a length of the continuous semifinished product 12 section placed downstream of the cutting device 35 is equal to a desired value corresponding to a circumferential extension of the surface 14 radially external to the building drum 15. The support surface 20 and the auxiliary support surface 30 are at this point stopped and the blade 37 is moved along the tilted guide 36 so as to cut the continuous semifinished product 12 placed on the auxiliary support surface 30 along a cutting line that is tilted according to the slope of the cords of the continuous semifinished product 12, so as to obtain the semifinished product cut to size 13 positioned on the support surface 20.

[0158] At this point, the support surface 20 is advanced up to bringing the entire semifinished product cut to size 13 on said support surface 20 and then stopped (figures 6 and 7). While the control unit 51 maintains stopped the conveyor belt 16 and hence also the semifinished product cut to size 13 situated on the support surface 20, the control unit 51 activates the optical reader 43 and, by controlling the second movement devices 49, moves the optical reader 43 along the guide 50, above the support surface 20 and for the entire length of the semifinished product cut to size 13. In this manner, the apparatus 1 acquires a digital image of the semifinished product cut to size 13 positioned on the support surface 20 while said semifinished product cut to size 13 is stationary.

[0159] The control unit 51 is configured and programmed for processing the digital image of the semifinished product cut to size 13, calculating positions of a plurality of points “Pi-Pn” of the semifinished product cut to size 13 and determining a positioning of said semifinished product cut to size 13 with respect to the support surface 20.

[0160] The profile of the semifinished product cut to size 13 has a head edge, a tail edge, a first longitudinal edge 52 and a second longitudinal edge 53. According to the embodiment described herein, the points of said plurality of points “Pi-Pn” belong to a head end, to a plurality of successive transverse sections and to a tail end of the semifinished product cut to size 13. In particular, the plurality of points “Pi-Pn” of the transverse sections comprises pairs of points and each pair of points comprises a first point placed on the first longitudinal edge 52 and a second point placed on the second longitudinal edge 53 of the semifinished product cut to size 13 (figure 6A). The points of each pair are situated on a line parallel to the main axis “X-X” of the building drum 15. For example, a number of successive transverse sections is comprised between 10 and 50 and the successive transverse sections are equidistant from each other by a distance comprised between 2 cm and 15 cm.

[0161] While the semifinished product cut to size 13 is still stationary on the support surface 20, the control unit 51 is configured and programmed for comparing the detected positions of the plurality of points with positions of points corresponding belonging to a profile 54 of a virtual reference semifinished product (figure 6A) and for emitting a signal of non-compliance if the detected positions of the plurality of points “Pi-Pn” differ from positions of corresponding points of said profile 54 of the virtual reference semifinished product beyond an acceptable threshold value S, said threshold S preferably being measured as distance over unit of length.

[0162] More precisely, the threshold S is evaluated based on the variation of the transverse positions, i.e. parallel to the main axis “X-X”, of the points “Pi-Pn” belonging to successive transverse sections. Let x and y be the coordinates of a point of said plurality of points “Pi-Pn” on the first longitudinal edge 52 (or on the second longitudinal edge 53), the semifinished product cut to size 13 is considered compliant if a transverse position Xi of a point on said first longitudinal edge 52 (or on the second longitudinal edge 53) with respect to a transverse position of a preceding point xi-i on the same first longitudinal edge 52 (or on the same second longitudinal edge 53) is such that:

[0163] (Xi - Xi-i) / (ys - yi-i) <= S in which:

[0164] - (xi - Xi-i ) is the transverse movement of the first longitudinal edge 52 (or of the second longitudinal edge 53) between the point PM and the point Pi;

[0165] - (y- - yi-i) is the longitudinal distance between the point P and the point Pi, i.e. the distance between two successive transverse sections.

[0166] For example, the distance between two successive transverse sections (yi - yn ) is equal to 10 cm and S = 0.02, which means that the transverse movement of the first longitudinal edge 52 (or of the second longitudinal edge 53) between the point P and the point Pi must be less than or equal to 1 cm each 50 cm of length of the semifinished product. Preferably, acceptable threshold values S are comprised between 0.017 (1 cm each 60 cm) and 0.025 (1 cm each 40 cm).

[0167] The control unit 51 may also be configured and programmed for unloading, from the support surface 20, the semifinished product cut to size 13 that is not compliant, advancing it beyond the distal end 16A, i.e. without winding it on the surface 14 radially external to the building drum 15.

[0168] If instead the semifinished product cut to size 13 falls within the acceptable considered values, the control unit 51 controls the conveyor 16 in a manner such that it translates from the first position in which it is situated to the second position, in a manner such that the head of the semifinished product cut to size 13 comes to be abutted against the surface 14 radially external to the building drum 15 and is retained on the radially external surface 14, for example through suction or magnetic systems or due to the adhesivity of components already deposited on the building drum 15 (figures 8 and 9).

[0169] At this point, the control unit 51 controls the conveyor 16 in order to advance the support surface 20 along the feed direction 21 and towards the building drum 15 and also controls the motor 46 in order to rotate the building drum 15 around the main axis “X-X” thereof. A peripheral speed of the surface 14 radially external to the building drum 15 is substantially equal to an advancement speed of the support surface 20 or slightly higher and the semifinished product cut to size 13 is wound around the building drum 15 (figures 10 and 11 ). The peripheral speed of the radially external surface 14 and the advancement speed of the support surface 20 may be managed in order to confer a stretch to the semifinished product cut to size 13 applied on the building drum 15 and a possible overlap between the head and the tail.

[0170] During the winding, the control unit 51 controls the first movement devices 47 which move the building drum 15 along the direction 48 parallel to the main axis “X-X”, in one sense or in the opposite sense, as a function of the positions of the points of each pair or of the deviance of such points with respect to the points corresponding belonging to the profile 54 of the virtual reference semifinished product. Therefore, with each transverse section of the semifinished product cut to size 13, there corresponds an axial movement of the building drum 15 in one sense or in the opposite sense and an axial position of said building drum 15. In this manner, a positioning of the semifinished product cut to size 13 is adjusted on said radially external surface 14. Each axial movement is comprised between 0.5 mm and 5 mm, e.g. 1 -2 mm.

[0171] In order for the movements between successive axial positions of the building drum 15 with respect to the support surface 20 to be continuous and connected to each other, the control unit 51 uses connecting functions (e.g. polynomial or spline functions) in order to interpolate the positions of the pairs of successive points and then the transverse positions of the successive transverse sections of the semifinished product cut to size 13 and the successive axial positions of the building drum 15. The building drum 15 is then axially moved between the successive axial positions according to said connecting functions.

[0172] For example, if the first longitudinal edge 52 and the second longitudinal edge 53 are not rectilinear but follow a curve, as represented in figure 6A, the building drum 15 is moved with continuity in one sense or in the opposite sense such to follow such curves and so as to position the first longitudinal edge 52 and the second longitudinal edge 53 along respective circumferences on the radially external surface 14.

[0173] Alternatively, the abovementioned points of said plurality of points “Pi-Pn” belong to a middle line of the semifinished product cut to size 13 and the building drum 15 is moved with respect to the support surface 20 and along the direction parallel to the main axis “X-X” so as to centre the middle line with respect to a median circumference of the radially external surface 14.

[0174] During the winding, the retention devices prevent undesired lateral movements of the semifinished product cut to size 13 on the support surface 20. In alternative embodiments of the apparatus 1 , not illustrated in the enclosed drawings, the optical reader 43 is fixed, i.e. it is not moved on the guide 50 placed above the support surface 20 and has a visual field such to frame the entire support surface 20 or at least the entire semifinished product cut to size 13 positioned on the support surface 20.

[0175] In alternative embodiments of the apparatus 1 , not illustrated in the enclosed drawings, the building drum 15 is not moved along the direction 48 parallel to the main axis “X-X” and it is instead the conveyor 16 that is moved along such direction according to the connecting functions.

[0176] In alternative embodiments of the apparatus 1 , not illustrated in the enclosed drawings, in place of translating between the first and the second position, the conveyor 16 rotates or oscillates between said first and second position or the building drum 15 is brought against the distal end 16A of the conveyor 16.

[0177] In alternative embodiments of the apparatus 1 , not illustrated in the enclosed drawings, if the continuous semifinished product 12 and hence the semifinished product cut to size 13 comprise metallic cords, the retention devices can be of magnetic type.

[0178] In embodiment variants of the process, not illustrated in the enclosed drawings, provision is made for winding, on the building drum 15, a first belt layer having cords tilted in one sense with respect to the circumferential direction and a second belt layer having cords tilted in an opposite sense with respect to said circumferential direction.

[0179] In embodiment variants of the process, not illustrated in the enclosed drawings, provision is made for winding on the building drum 15 a first carcass ply having cords tilted in one sense with respect to the circumferential direction and a second carcass ply having cords tilted in a sense opposite with respect to said circumferential direction.

Claims

CLAIMS1 . Process for building tyres for vehicle wheels, comprising: forming at least one component of a tyre (2) on a building drum (15), wherein said component is formed through:- arranging a semifinished product cut to size (13) and positioning it on a support surface (20);- detecting positions of a plurality of points (Pi-Pn) of the semifinished product (13) positioned on the support surface (20) while the support surface (20) and the semifinished product (13) are stationary, so as to determine a positioning of said semifinished product (13) with respect to said support surface (20);- arranging one end of said support surface (20) close to a surface (14) radially external to the building drum (15);- winding the semifinished product (13) on the radially external surface (14), by advancing the support surface (20) towards the building drum (15) and rotating said building drum (15) around a main axis (X-X) thereof;- during the winding of the semifinished product (13) on the radially external surface (14), causing a relative movement between the building drum (15) and the support surface (20) along a direction (48) parallel to the main axis (X-X) as a function of said positioning of the semifinished product (13) with respect to said support surface (20), so as to adjust a positioning of the semifinished product (13) on said radially external surface (14).

2. Process according to claim 1 , wherein detecting the positions of the plurality of points (Pi-Pn) of the semifinished product (13) comprises:- acquiring, through an optical reader (43), a digital image of the semifinished product (13) positioned on the support surface (20);- calculating the positions of the plurality of points (Pi-Pn) from the digital image.

3. Process according to claim 2, comprising: moving the optical reader (43) above the semifinished product (13) in order to acquire the digital image.

4. Process according to one of claims 1 to 3, wherein the points of said plurality of points (Pi-Pn) belong to successive transverse sections of the semifinished product (13) and wherein, through movements along the direction (48) parallel to the main axis (X-X), the building drum (15) is brought, with respect to the support surface (20), into a plurality of successive axial positions, each axial position corresponding to a transverse section of the semifinished product (13).

5. Process according to claim 4, wherein movements between successive axial positions of the building drum (15) with respect to the support surface (20) are continuous and connected to each other.

6. Process according to one of claims 1 to 5, wherein the points of said plurality of points (P1 -Pn) belong to at least one between a first longitudinal edge (52) and a second longitudinal edge (53) of the semifinished product (13).

7. Process according to claim 6, wherein the plurality of points (Pi-Pn) comprises pairs of points and each pair of points comprises a first point placed on the first longitudinal edge (52) and a second point placed on the second longitudinal edge (53).

8. Process according to claim 7, wherein the points of each pair are situated on a line parallel to the main axis (X-X).

9. Process according to one of claims 6 to 8, wherein the building drum (15) is moved with respect to the support surface (20) and along the direction (48) parallel to the main axis (X-X) so as to position the first longitudinal edge (52) and the second longitudinal edge (53) along respective reference circumferences of the radially external surface (14).

10. Process according to one of claims 1 to 5 wherein the points of said plurality of points (Pi-Pn) belong to a middle line of the semifinished product (13).11 . Process according to claim 10, wherein the building drum (15) is moved with respect to the support surface (20) and along the direction (48) parallel to the mainaxis (X-X) so as to centre the middle line with respect to a reference circumference of the radially external surface (14).

12. Process according to claim 11 , wherein the reference circumference is a median circumference of the building drum (15).

13. Process according to one of claims 1 to 5 wherein the points of said plurality of points (P-i-Pn) comprise at least one point belonging to a head edge of the semifinished product (13) and at least one point belonging to a tail edge of the semifinished product (13).

14. Process according to one of claims 1 to 13, comprising:- comparing the detected positions of the plurality of points (P1 -Pn) with a profile (54) of a virtual reference semifinished product;- discarding the semifinished product (13) before winding said semifinished product (13) on the radially external surface (14) if the detected positions of the plurality of points (P1 -Pn) differ from positions of corresponding points of said profile (54) of the virtual reference semifinished product with respect to an acceptable threshold value (S).

15. Apparatus for building tyres for vehicle wheels, comprising: a building drum (15); a conveyor (16) having a support surface (20) configured for being moved along a feed direction (21 ) and towards the building drum (15); an optical reader (43) positioned above the support surface (20); a motor (46) operatively coupled to the building drum (15) in order to rotate it around a main axis (X-X) thereof; first movement devices (47) for generating a relative movement between said building drum (15) and said support surface (20) along a direction (48) parallel to said main axis (X-X); a control unit (51 ) operatively associated with the conveyor (16), with the optical reader (43), with the motor (46), with the first movement devices (47); the control unit (51 ) being configured for:- detecting, through the optical reader (43), positions of a plurality of points (P1 -Pn) of a semifinished product cut to size (13) positioned on said support surface (20) while the support surface (20) is stationary;- determining, starting from said positions of a plurality of points (P1 -Pn) of said semifinished product (13), a positioning of said semifinished product (13) with respect to said support surface (20);- arranging one end of said support surface (20) close to a surface (14) radially external to the building drum (15);- controlling the conveyor (15) and the motor (46) in order to wind the semifinished product (13) on the surface (14) radially external to the building drum (15), by advancing the support surface (20) along the feed direction (21 ) and rotating said building drum (15) around the main axis (X-X) thereof;- controlling the first movement devices (47) in order to cause a relative movement between the building drum (15) and the support surface (20) along the direction (48) parallel to the main axis (X-X) as a function of said positioning of the semifinished product (13) with respect to said support surface (20), so as to adjust a positioning of the semifinished product (13) on said radially external surface (14).

16. Apparatus according to claim 15, comprising second movement devices (49) operatively coupled to the optical reader (43); wherein the control unit (51 ) is configured for controlling the second movement devices (49) and moving the optical reader (43) above the support surface (20).

17. Apparatus according to claim 16, wherein the second movement devices (49) comprise: a guide (50) placed above the support surface (20) and extended parallel to the feed direction (21 ), wherein the optical reader (43) is coupled to the guide (50); a respective actuator coupled to the optical reader (43) and to the guide (50) in order to move said optical reader (43) along the guide (50); wherein the control unit (51 ) is operatively connected to the respective actuator.

18. Apparatus according to claim 17, wherein the guide (50) is extended over an entire length of the support surface (20).

19. Apparatus according to one of claims 15 to 18, wherein the control unit (51 ) is configured for:- acquiring, through the optical reader (43), a digital image of the semifinished product (13) positioned on the support surface (20);- calculating the positions of the plurality of points (P1 -Pn) from the digital image.

20. Apparatus according to one of claims 15 to 19, wherein the control unit (51 ) is configured for:- calculating positions of points belonging to successive transverse sections of the semifinished product (13);- bringing the building drum (15), with respect to the support surface (20), into a plurality of successive axial positions, each axial position corresponding to a transverse section of the semifinished product (13).

21. Apparatus according to claim 20, wherein the control unit (51 ) is configured for:- calculating connecting functions between the successive axial positions;- moving the building drum (15) with respect to the support surface (20) between the successive axial positions according to said connecting functions.

22. Apparatus according to one of claims 15 to 21 , wherein the conveyor (16) is fixed along the direction (48) parallel to the main axis (X-X) and the first movement devices (47) are operatively coupled to the building drum (15) in order to move said building drum (15) along said direction (48) parallel to the main axis (X-X).

23. Apparatus according to one of claims 15 to 22, wherein the conveyor (16) is movable along the feed direction (21 ) between a first position, wherein a distal end (16A) of the conveyor (16) is spaced from the surface (14) radially external to the building drum (15), and a second position, wherein the distal end (16A) of theconveyor (16) is associated with the surface (14) radially external to the building drum (15) in order to transfer the semifinished product (13) from the support surface (20) to the radially external surface (14); wherein the apparatus (1 ) comprises an actuator coupled to the conveyor (16) in order to move it between the first position and the second position.

24. Apparatus according to claim 23, comprising a base (17) abutted against the ground, wherein the conveyor (16) is mounted on the base (17) in order to be moved between the first position and the second position.

25. Apparatus according to claim 23 or 24, wherein, in the second position, the distal end (16A) of the conveyor (16) is situated below the building drum (15).

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