Process and apparatus for building tyres for bicycles

Abstract

In the process of building tyres (2) for bicycles, prior to laying at least one of the components, the respective semi-finished product (20a, 20b, 20c, 20d) is first subjected to a dimensional cutting process, and the semi-finished product is advanced with the lower surface (S1) of the semi-finished product abutting against an advancing plane (P) defined by a conveyor belt (23) comprising a feed section (24) and a preparation section (25) which are aligned one after the other. The advancing of the semi-finished product is stopped when the head end (A) of the semi-finished product reaches a predetermined cutting distance (K) with respect to the cutting plane (Q). A cut portion (T) of the semi-finished product is lifted at a cutting plane (Q) relative to an advancing plane (P) and the semi-finished product is cut transversely along a cutting line (L) in order to separate a section (21) of a predetermined length. The section (21) is advanced along a conveyor belt (23) in order to position and stop the head end (A) on a laying surface (15) of a building drum (13) which rotates while the conveyor belt (23) moves the section (21) at an advance speed related to the peripheral speed of the laying surface (15) in order to circumferentially lay the section (21).

Description

Technical Field

[0001] The present invention relates to a process for building tyres for bicycles. The object of the present invention is also an apparatus for building tyres for bicycles, said apparatus being suitable for carrying out the above-mentioned process. Background Art

[0002] The terms “radial” and “axial” and the expressions “radially inward / outward” and “axially inward / outward” are used with reference to the radial direction and the axial direction, respectively, of a building drum for building the tyre and / or of the tyre itself, i.e. with reference to a direction perpendicular to and parallel to the axis of rotation of the building drum / tyre, respectively.

[0003] The term "application surface" is intended to denote a substantially cylindrical surface located in a radially outer position relative to the building drum. The application surface belongs to the actual building drum when no tire components are applied to the building drum. In intermediate steps of the building process, the application surface may be represented by tire components already applied to the building drum.

[0004] Building a bicycle tire typically requires applying one or more carcass plies in a cylindrical configuration around the outer surface of a building drum. Each of a pair of bead cores is assembled or applied around one of the two axially opposing end flaps of the carcass ply. The end flaps are then turned up around the respective bead core. The tread band, typically in the form of a strip of elastomeric material cut to size, is then applied and wrapped around the carcass plies laid against the building drum, axially centered relative to the bead core.

[0005] At the end of the winding, the opposite ends of the tread band slightly overlap and are joined to each other by a head-to-head joint.

[0006] Throughout the entire building process, including the application of the tread band, the mutual axial distance between the bead cores remains constant. This aspect of the process represents a significant feature that distinguishes tyres for bicycles from tyres for motor vehicles. In practice, in tyres for motor vehicles, a step is usually provided for bringing the bead cores closer together in order to give the carcass structure a toroidal configuration during association with a belt structure having a diameter greater than that of the bead cores.

[0007] After building is complete, the built green tyre for bicycles is removed from the drum and transferred to a vulcanizing press in order to undergo a molding and vulcanizing process aimed at determining the structural stability through cross-linking of the elastomeric material present therein and optionally imparting the desired tread design to the tread band.

[0008] For example, in the video clip https: / / youtu.be / e3sHyJKaFMo?t=879 (timing from 14'37" to 15'50" - last viewed on December 14, 2022), one can see the sequential laying of the carcass ply, bead core, sidewall reinforcement, bead reinforcement and tread band in order to build a tire for a bicycle on a building drum. Each of these components is made, in a manner simultaneous with its laying, from a semi-finished product in the form of a continuous strip coming from a corresponding feed group, which guides the semi-finished product to a position in the immediate vicinity of the application point on the building drum, where an operator performs the operations required for applying said semi-finished product. The application of each component provides for the manual fixing of the head end of the corresponding semi-finished product on the laying surface of the drum, after which the drum is rotated one or more times about its axis of rotation so as to determine the circumferential winding of the semi-finished product around the laying surface. For several components, such as, for example, the carcass plies, sidewall reinforcements, reinforcing beads and tread band, operators are required to manually manipulate the semi-finished product and / or the building drum during the winding process in order to facilitate the correct distribution and application of the material.

[0009] For the sidewall reinforcements, the operator is also required to manually guide the semi-finished product for proper alignment and to manually control its tension. At the end of each winding of a component, the drum stops rotating and the operator must manually cut the semi-finished product and attach the tail end of the resulting component to the head end previously applied to the layup surface.

[0010] Therefore, at the current state of the art, even with the aid of automatic or semi-automatic feeding systems for the semi-finished products, the assembly operations of the parts on the building drum require the use of a specialized workforce in order to obtain the correct positioning, distribution, tensioning and / or cutting to size of the semi-finished products themselves in order to manufacture the parts on the building drum.

[0011] The Applicant has proposed automating the above-mentioned existing construction process, but the Applicant has found that the machines and methods usually used in the manufacture of tires for motor vehicles (for example, cars and / or motorcycles) cannot be used to manufacture tires for bicycles. In fact, the construction operation of tires for bicycles requires the preparation and manipulation of extremely slender and delicate finished products. The thickness of many components (for example, liners, carcass plies and other textile reinforcement structures) can be between 0.1 mm and 1 mm, for example about 0.3 mm, while the extension in the width direction can reach and exceed values of 450 mm. In addition, components made of elastomeric materials (for example, liners) can have a thickness within the above-mentioned range, for example less than 0.35 mm, but a width greater than 120 mm. These dimensional characteristics almost always result in the semi-finished products used lacking sufficient structural consistency, so as not to allow them to be properly manipulated by the machines usually used to build tires for motorcycles or cars.

[0012] However, the need to use a specialized workforce involves a reduction in productivity and a significant increase in production costs, especially in situations where a certain level of production precision and uniformity (i.e., repeatability) must be achieved, such as in the production of tires intended for sports use (where structural precision translates into performance). There are also issues with the safety of the operators, who often have to use their hands to perform the various work operations in close proximity to and / or in direct contact with moving parts, exposing them to the risk of injury.

[0013] The applicant believes that by adding a cutting step to the above-mentioned sequence of operations, the disadvantages previously encountered can be overcome.

[0014] More precisely, the Applicant has discovered that the correct manipulation of the material for the purpose of manufacturing the individual components of the tyre on the building drum can be facilitated by separating sections of appropriate length from each semi-finished product before its application.

[0015] According to the present invention, the applicant has also found that by appropriately lifting the semi-finished product relative to its advancement plane in the section through which the cutting line passes, it is helpful to separate this section from the rest of the semi-finished product by performing a precise cut without causing stress and / or excessive distortion in the material under the action of the cutting blade due to the limited thickness and reduced consistency of the semi-finished product. Summary of the Invention

[0016] According to a first aspect, the invention relates to a process for building tyres for bicycles, wherein a plurality of components of the tyre being processed are laid circumferentially around a laying surface carried by a building drum.

[0017] Preferably, provision is made for at least one carcass ply to be laid circumferentially around said deposition surface.

[0018] Preferably, provision is made for applying a pair of bead cores around the carcass ply at a predetermined mutual axial distance.

[0019] Preferably, provision is made for the axially outer end flaps of the carcass ply to be turned up around the bead core.

[0020] Preferably, provision is made for the tread band to be applied circumferentially around the application surface, keeping the mutual axial distance of the bead cores substantially constant.

[0021] Preferably, before laying down at least one of the components, the corresponding semi-finished product in the form of a continuous strip is subjected to a process of cutting to size along cutting lines in order to separate sections of predetermined cutting length from the semi-finished product itself.

[0022] Preferably, the process of cutting to size comprises positioning the semi-finished product with its lower surface against a propulsion plane defined by a conveyor belt comprising a feed section and a preparation section aligned successively.

[0023] Preferably, the process of cutting to size comprises advancing the semi-finished product longitudinally along an advancing plane.

[0024] Preferably, the cutting to size process provides for stopping the advancement of the semi-finished product when the head end of the semi-finished product reaches a predetermined cutting distance relative to the cutting plane, after the semi-finished product has passed a cutting plane intersecting the advancement plane and containing the cutting line.

[0025] Preferably, the process of cutting to size provides for raising the semi-finished product relative to the advancement plane at the cutting portion where the semi-finished product intersects the cutting plane.

[0026] Preferably, the cutting-to-size process provides for cutting the semi-finished product transversely along a cutting line in order to separate said sections of predetermined length from the semi-finished product itself.

[0027] Preferably, provision is made for the segments to be advanced along the conveyor belt in order to position and stop the head end on the deposition surface.

[0028] Preferably, provision is made for the building drum to be actuated in rotation while the conveyor belt translates the segments at an advancement speed related to the peripheral speed of the deposition surface, so as to deposit the segments circumferentially around the deposition surface.

[0029] In another aspect, the invention relates to an apparatus for building tyres for bicycles, comprising a building drum and a laying group configured for laying down a plurality of components circumferentially around a laying surface carried by the building drum.

[0030] Preferably, said laying group comprises a carcass ply application device configured to lay at least one carcass ply circumferentially around a laying surface carried by the building drum.

[0031] Preferably, means are provided for applying a pair of bead cores around the carcass ply at a predetermined mutual axial distance.

[0032] Preferably, a turning-up device is provided, which is configured to turn up the axially outer end flap of the carcass ply around the bead core.

[0033] Preferably, a tread band application device is provided, configured to apply the tread band circumferentially around the deposition surface and in an axially centred position between the bead cores arranged at said predetermined mutual axial distance.

[0034] Preferably, the laying group comprises at least one preparation unit configured to cut the semi-finished product in the form of a continuous strip transversely to size along cutting lines so as to separate sections of predetermined cutting length from the semi-finished product itself.

[0035] Preferably, the preparation unit comprises a conveyor belt comprising a feed section and a preparation section aligned successively according to an advancement plane configured to support the semi-finished product, wherein the lower surface of the semi-finished product rests on the advancement plane itself.

[0036] Preferably, the preparation unit comprises means for controlling the conveyor belt, said means being configured to advance the semi-finished product longitudinally along the advancement plane and to stop the advancement of the semi-finished product when the head end of the semi-finished product reaches a predetermined distance relative to a cutting plane intersecting the advancement plane and containing said cutting line.

[0037] Preferably, the preparation unit comprises a lifting device configured to raise the semi-finished product relative to the advancement plane at a cutting portion of the semi-finished product intersecting the cutting plane.

[0038] Preferably, the preparation unit comprises a cutting group configured to cut the semi-finished product transversely along a cutting line so as to separate said sections of predetermined length from the semi-finished product itself.

[0039] Preferably, means are provided for actuating the building drum in rotation while the conveyor belt translates the segments at an advancement speed related to the peripheral speed of the deposition surface, so as to deposit said segments circumferentially around the deposition surface.

[0040] The Applicant believes that pre-cut sections to size are easier to manage than semi-finished products fed directly from a feed reel, allowing their application to be carried out in an automated manner with high precision and repeatability without the risk of causing excessive stress and / or distortion to the component itself.

[0041] In this way, it is possible to activate suitable automation of the operations aimed at applying the components of tyres for bicycles on the building drum, thus helping to obtain a higher throughput in the treatment of the individual components, to the benefit of the quality of the final product, production costs and the safety of production supervisors.

[0042] The Applicant has also recognized that lifting near the cutting line allows for the creation of a controlled tension zone along the semi-finished product, which facilitates the cutting and separation of the trailing end of the resulting segment from the leading end of the continuous semi-finished product. Thus, precise cutting can be performed even with very thin and less robust semi-finished products, where the elastomer of which it is composed, in its unprocessed (green) state, tends to deform and generate stresses (i.e., deformation and the resulting local accumulation of material) under the action of the cutting elements. The pre-cut segment from the semi-finished product is then adapted to be easily translated along the advancing plane up to the application zone, allowing precise placement around the build drum without imparting uncontrolled stretching or distortion to the segment itself.

[0043] In at least one convenient embodiment, the present invention further includes one or more of the following preferred features.

[0044] Preferably, during application of the tread band, said at least one carcass ply bears against the laying surface with an axially central portion thereof, said axially central portion extending axially through an axial mid-line plane equidistant from the bead core.

[0045] Preferably, provision is also made for the tail end of the segment to be joined to the head end previously applied to the deposition surface.

[0046] Preferably, the cutting distance is related to the circumferential extension of the deposition surface.

[0047] Thereby, correctly performing the mutual joining of the ends of the segments laid around the laying surface is facilitated.

[0048] Preferably, the length of the section on the detection preparation section is also specified.

[0049] Preferably, provision is made for the length of the detected section to be compared with the circumferential extension of the deposition surface.

[0050] Preferably, during the laying of the segments on the building drum, provision is made to adjust the translation speed of the conveyor belt relative to the rotation speed of the building drum in order to vary the length of the segments and conform them to the circumferential extension of the laying surface.

[0051] It is thus possible to compensate for any elastic contraction of the material that may occur after the cutting has been carried out and before application on the building drum, so as to facilitate a correctly carried out mutual joining of the ends of the segments.

[0052] Preferably, the component comprises a lining.

[0053] Preferably, the laying of the liner is activated before laying of said at least one carcass ply.

[0054] Preferably, laying of the lining comprises arranging the lining semi-finished product in the form of a continuous strip.

[0055] Preferably, laying of the lining comprises subjecting a lining blank to said cutting to size process.

[0056] Preferably, the thickness of the lining blank is between 0.35 mm and 1 mm.

[0057] Preferably, the width of the lining blank is between 70 mm and 120 mm.

[0058] Preferably, the laying of said at least one carcass ply comprises arranging a carcass ply semi-finished product in the form of a continuous strip.

[0059] Preferably, laying of said at least one carcass ply comprises subjecting a carcass ply semi-finished product to said cutting-to-size treatment.

[0060] Preferably, the thickness of the carcass ply semi-finished product is between 0.3 mm and 0.8 mm.

[0061] Preferably, the width of the carcass ply semi-finished product is between 110 mm and 450 mm.

[0062] Preferably, the carcass ply semifinished product incorporates mutually parallel reinforcing cords inclined at an angle comprised between 35° and 55° with respect to the longitudinal extension of the carcass ply semifinished product.

[0063] Preferably, the component comprises a sidewall reinforcement.

[0064] Preferably, the laying of the sidewall reinforcement is activated after turning up the terminal flap and before laying of the tread band.

[0065] Preferably, the laying of the side wall reinforcement comprises arranging a pair of side wall reinforcement semi-finished products, each side wall reinforcement semi-finished product being in the form of a continuous strip.

[0066] Preferably, the laying of the side wall reinforcement comprises subjecting a side wall reinforcement semi-finished product to said cutting-to-size process.

[0067] Preferably, the component comprises at least one protective strip.

[0068] Preferably, the laying of said at least one protective band is activated before the laying of the tread band.

[0069] Preferably, the laying of the at least one protective tape comprises arranging a protective tape semi-finished product in the form of a continuous strip.

[0070] Preferably, the applying of said at least one protective tape comprises subjecting a semi-finished protective tape product to said cutting-to-size process.

[0071] Preferably, the protective strip is applied in an axially centred position relative to the bead core.

[0072] Preferably, the application of the protective tape occurs before the turning up of the end flap.

[0073] Preferably, the protective tape is applied after the end flap is folded up.

[0074] Preferably, the thickness of the semi-finished protective tape is between 0.3 mm and 0.6 mm.

[0075] Preferably, the width of the semi-finished protective tape is between 15 mm and 50 mm.

[0076] Preferably, the width of the semi-finished protective tape is between 50 mm and 200 mm.

[0077] Preferably, said component comprises an elastomeric substrate, the application of which is activated before application of the tread band.

[0078] Preferably, the laying down of the elastomeric substrate comprises arranging an elastomeric substrate semi-finished product in the form of a continuous strip.

[0079] Preferably, said laying down of the elastomeric substrate comprises subjecting an elastomeric substrate semi-finished product to said cutting-to-size process.

[0080] Preferably, the elastomeric substrate is applied in an axially centered position relative to the bead core.

[0081] Preferably, the application of the elastomeric substrate occurs after the end flaps have been turned up.

[0082] Preferably, the thickness of the elastomeric substrate semi-finished product is between 0.5 mm and 1.5 mm.

[0083] Preferably, the width of the elastomeric substrate semi-finished product is between 15 mm and 30 mm.

[0084] Preferably, said laying of the tread band comprises arranging a tread band semi-finished product in the form of a continuous strip.

[0085] Preferably, said applying of the tread band comprises subjecting a tread band semi-finished product to said cutting-to-size process.

[0086] Preferably, the thickness of the tread band semi-finished product is between 1 mm and 8 mm.

[0087] Preferably, the width of the tread band blank is between 20 mm and 120 mm.

[0088] Preferably, means are provided for measuring the length of the segments on the preparation section.

[0089] Preferably, provision is made for the comparator to be configured to compare the length of the segment detected by the measuring device with the circumferential extension of the deposition surface.

[0090] Preferably, the comparator is operatively connected to the means for controlling the conveyor belt and to the means for actuating the rotation of the building drum so as to regulate the translation speed of the conveyor belt relative to the peripheral speed of the deposition surface.

[0091] Preferably, the at least one preparation unit has a substantially horizontal longitudinal extension.

[0092] Preferably, the at least one preparation unit converges substantially in a radial direction towards the building drum.

[0093] Preferably, the laying group comprises at least two preparation units.

[0094] Preferably, the laying group includes at least three preparation units.

[0095] Preferably, the preparation units are placed one above the other in succession.

[0096] In this way, an optimization of the machine size is achieved.

[0097] Preferably, the preparation units converge towards the building drum on the same side.

[0098] Preferably, the feed section comprises a strip-shaped feed belt which is engaged around respective first drive rollers.

[0099] Preferably, the preparation section comprises a strip-like preparation belt engaged around the second drive roller.

[0100] Preferably, the respective upper sections of the feed belt and the preparation belt are coplanar and aligned to define the aforementioned advancing plane.

[0101] The use of two successive belts facilitates the correct separation of the cut sections from the semi-finished product.

[0102] Preferably, the feed section and the preparation section are driven independently of each other.

[0103] Thus, the respective feed and preparation belts can be actuated at respectively equal or different translation speeds, depending on requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0104] Further features and advantages will become apparent from the detailed description of a preferred but non-exclusive embodiment of a process and a related apparatus for building a tire for a bicycle according to the present invention. Such description will be made with reference to the accompanying drawings, which are provided for non-limiting purposes only, in which:

[0105] - Figures 1 to 4Several operational steps for building a green tire for a bicycle are schematically shown in radial section;

[0106] - Figure 5 schematically depicts, in side view, an apparatus according to the invention for building tyres for bicycles;

[0107] - Figure 6 shows a schematic top view of one of the units for preparing a semi-finished product forming part of the present apparatus according to a first embodiment which can be used, for example, for manufacturing a carcass ply;

[0108] - Figure 7 Shown Figure 3 Detail of the preparation unit, showing details of the cutting group and the lifting device in a side view;

[0109] - Figure 8 A detail of the preparation unit in the transition area between the infeed section and the preparation section of the conveyor belt is shown, and a front view of the cutting group with the lifting device in the raised position is shown;

[0110] - Figure 9 Shown Figure 8 details of which the lifting device is in the lowered position;

[0111] - Figure 10 shows a detail of another preparation unit according to an embodiment variant, wherein details of the cutting group and the lifting device are shown in a side view;

[0112] - Figure 11 Shown Figure 10 Detail of the preparation unit located in the transition zone between the infeed section and the preparation section of the conveyor belt, showing the cutting group and the lifting device in a front view;

[0113] - Figure 12 shows a schematic top view of another preparation unit of a semi-finished product forming part of the present apparatus according to another embodiment particularly suitable, for example, for manufacturing a tread band;

[0114] - Figure 13 Shown in side view Figure 12 a preparation unit located in a transition zone between the feed section and the preparation section of the conveyor belt;

[0115] - Figure 14 Shown Figure 12 and Figure 13 Detail of the preparation unit showing the cutting group and the lifting device in front view;

[0116] - Figure 15 Shown Figure 12 and Figure 14Detail of the preparation unit showing the cutting group and the lifting device in front view;

[0117] - Figure 16 The structural concept of a hypothetical tire for a bicycle is shown in radial section. DETAILED DESCRIPTION

[0118] exist Figure 5 In the drawing, reference numeral 1 denotes as a whole an apparatus for building tyres for bicycles, said apparatus being suitable for starting a building process according to the invention.

[0119] The present invention is intended to be used for processing Figure 16 Schematically illustrated is a tire 2 for a bicycle of the type used, for example, on road bicycles, track bicycles, mountain bicycles, electric bicycles, etc.

[0120] In the tyre 2 , it is possible to identify a radially inner surface 2 a , which is substantially facing towards the geometrical axis of rotation “X” of the tyre 2 , and a radially outer surface 2 b , which is substantially facing away from the geometrical axis of rotation “X”.

[0121] The tyre 2 for a bicycle has a carcass structure 3 comprising at least one carcass ply 4 having mutually parallel cords incorporated in an elastomeric base.

[0122] The axially opposite end flaps 4a of the carcass ply or plies 4 are joined to respective bead cores 5, i.e. annular anchoring structures integrated in the area generally identified by the name "bead", where a mechanical connection exists between the tyre 2 in use and the respective mounting rim.

[0123] A tread band 6 made of elastomeric material is applied in a radially outer position with respect to the carcass structure 3 .

[0124] Preferably, in the carcass structure 3, at least two cord layers are applied with their respective cross-direction orientations. The cords belonging to each layer have an extension inclined according to a predetermined angle, said predetermined angle being between approximately 35° and approximately 55° relative to the circumferential extension of the tire 2. Provision can be made for two carcass plies 4, radially superposed on one another, each having respective cords extending in a direction inclined relative to the circumferential extension of the tire 2 and in an orientation inclined relative to the cords belonging to the other carcass ply 4. Alternatively, as shown in the example illustrated, provision can be made for the end flaps 4a of a single carcass ply 4, turned up around the bead core 5, to extend at least as far as the axial midline plane M of the tire 2, such that each end flap defines another radially outer layer of cords having a cross-direction orientation relative to the cords present in the radially inner layer.

[0125] However, in a bicycle tire 2, provision may be made for at least one protective belt 7 to extend circumferentially between the tread band 6 and the carcass structure 3, or between two radially superposed carcass plies. If provided, the at least one protective belt 7 (whose function is, for example, to protect the tire 2 from punctures) may have a textile structure incorporating respectively parallel or respectively crossing cords and preferably have a thickness not greater than approximately 0.6 mm, preferably between 0.3 mm and 0.6 mm. In one possible embodiment, the axial extension of the protective belt / belts is less than the axial extension of the tread band 6 and is preferably between 15 mm and 50 mm. In a possible embodiment variant, provision may be made for an extended protective belt 8, often referred to as an "inter-bead protection belt," to have an axial extension that is, instead, greater than the axial extension of the tread band 6 and, for example, between 50 mm and 200 mm, preferably terminating axially at each of the bead cores 5. In another possible embodiment, not shown, provision can be made for the width of the first protection band 7 to be smaller than the width of the tread band, and for the enlarged protection band 8 to extend from one of the bead cores 5 to the other bead core 5 .

[0126] Between the carcass ply / plies 3 and the tread band 6, there may also be interposed, in the form of a layer, an elastomeric base 9, preferably in an axially centered position relative to the bead core and radially on the inside relative to the optionally present protective band 7. The elastomeric base may have an axial width of approximately between 15 and 30 mm and a thickness of between 0.5 and 1.5 mm.

[0127] The radially inner surface of the carcass structure 3 may be covered with a so-called liner 10 consisting of an airtight composite layer, the thickness of which may be approximately between 0.35 mm and 1 mm. The liner 10 extends from one of the beads to the other according to an axial extension of approximately between 70 mm and 120 mm.

[0128] Near the bead core 5 and on the outside of the bead, a respective reinforcing bead 11, generally called a "chafer", may also be applied. It is in the form of a textile strip incorporating mutually parallel or respectively crossed cords, the purpose of which is to protect the bead from contact with the rim of the wheel on which the tire is mounted. Each reinforcing bead 11 may have a width between 8 mm and 15 mm and a thickness between 0.3 mm and 1 mm.

[0129] Preferably, on the radially outer surface 2b of the tyre 2 for bicycles, portions of the carcass ply 4 can be identified between the axially outer edges of the tread band 6 and the bead cores 5, these portions of the carcass ply 4 being directly exposed to the external environment. In fact, the tyre 2 for bicycles generally lacks sidewalls (i.e. layers of elastomeric material applied laterally to the outside of the carcass structure 3), each of said sidewalls extending between one of the beads and the respective axially outer edge of the tread band 6. However, provision may also be made for the so-called "sidewall reinforcements" 12 to each comprise a strip of rubberized textile material incorporating mutually parallel or crossed cords, wherein said cords have a thickness of approximately between 0.3 mm and 0.8 mm and each extend between the respective bead and the tread band 6 with a width of between 30 mm and 60 mm.

[0130] The apparatus 1 comprises a substantially cylindrical building drum 13 rotatably supported about its horizontal axis of rotation XX. Figure 5 A laying group, indicated as a whole at 14 , serves to lay the various components of the tyre 2 circumferentially around a laying surface 15 present on the outside of the building drum 13 .

[0131] The type, number and / or structural and dimensional characteristics of the components are selected according to the type of tire produced for bicycles (road, track, mountain, etc.), and the components include carcass ply / multiple carcass plies 4, bead cores 5, tread band 6, and possibly liner 10, sidewall reinforcement 12, elastomeric base 9, reinforcing beads 11, protection belts 7, 8, etc.

[0132] More specifically, if Figures 1 to 4 As shown, the building of a tire 2 for a bicycle provides for the carcass ply or plies 4 to be laid down in a cylindrical configuration by liner / ply applicators 16, 17 which assist in winding the carcass ply / plies 4 around a laying surface 15 present on the outside of a building drum 13. Possible liner 10 (for simplicity of illustration, not shown on the Figure 16 The liner / carcass ply application devices 16, 17 may be laid down on the deposition surface 15 before the carcass ply / plies 4 are applied.

[0133] A pair of bead cores 5 are applied at a predetermined mutual axial distance D by a bead core application device (not shown in the figure), wherein the bead cores are made of, for example, a composite material based on natural or synthetic fibers and / or of a metal material, and each of the bead cores surrounds one of the axially opposite end flaps 4a of the carcass cord layer 4.

[0134] Provision may be made for each bead core 5 (prefabricated in the form of a finished component) to be first fitted around the carcass ply or plies 4 in an axial position corresponding to a circumferential recess 18 optionally arranged on the building drum 13. A slight radial expansion of the building drum 13 (for example by means of a lever forming part of said bead core application device) determines the application of the bead core 5 against the carcass ply or plies 4, each of said bead cores being located at a respective circumferential recess 18.

[0135] Alternatively, the bead core application device can be configured for manufacturing each bead core 5 directly on the building drum 13 and winding one or more continuous cords 4 around the carcass ply or plies 4 in the form of multiple coils axially close and / or radially superimposed on each other.

[0136] Thus the turning-up device 13a (at the Figure 3 ) the end flaps 4a of the carcass ply 4 are turned up around the corresponding bead cores 5. During the turning up process, the end flaps 4a may at least partially overlap each other and may optionally be joined in a manner that they are in direct contact with each other.

[0137] The tread band application device 19 assists in applying the tread band 6 around the carcass ply 4 in an axially centered position relative to the bead core 5. The tread band 6 can be applied in a radially superimposed manner relative to the turned-up end flaps 4a. After application, the end flaps 4a can thus be partially arranged in an axially inner position relative to the axially opposite lateral edges of the tread band 6. During the application of the tread band 6, the axially central portion of the at least one carcass ply 4 (which axially extends through an axial midline plane M equidistant from the bead core 5) rests against the building drum 13 ( Figure 16 ) and / or on the laying surface 15.

[0138] Preferably, the tread band 6 is applied keeping substantially constant the mutual axial distance D between the bead cores 5. More particularly, the mutual axial distance D between the bead cores 5 is preferably kept constant throughout the entire building process (including the application of the tread band 6).

[0139] If desired, the at least one protective band 7, the sidewall reinforcement 12 and the elastomeric base 9 may be applied in an axially centered position relative to the bead core 5 before applying the tread band 6. The elastomeric base 9 is preferably applied before turning up the end flaps, while the application of the protective band 7 and / or the extended protective band 8 may take place before or after said turning up, as required. Possible reinforcement beads 11 may be applied simultaneously near each of the beads before or after the application of the tread band 6.

[0140] After the building is complete, the green tire 2 is removed from the building drum 13 in order to undergo further processing steps, for example, to be transferred to a vulcanizing press. To this end, the building drum 13 can be radially retracted to facilitate the axial removal of the built tire 2. Conveniently, provision is made for the respective semi-finished product 20a, 20b, 20c, 20d in the form of a continuous strip to be cut to size along a cutting line L before at least one of the above-mentioned tire components is laid, so as to separate sections 21 of predetermined cut length from the semi-finished product itself. The sections 21 are then brought to the building drum 13 in order to be applied around the lay-up surface 15.

[0141] To achieve this, the laying group 14 comprises at least one preparation unit 22a, 22b, 22c, 22d configured to cut the semi-finished product 20a, 20b, 20c, 20d transversely to size along a cutting line L so as to separate sections 21 of predetermined cutting length from the semi-finished product itself. More particularly, provision is preferably made for more than one of the preparation units 22a, 22b, 22c, 22d to be each dedicated to preparing a corresponding tire component. More specifically, in Figure 2 In the embodiment of the present invention, in addition to the first preparation unit 22a, for example dedicated to preparing the liner 10, it is possible to identify a second preparation unit 22b and a third preparation unit 22c, respectively dedicated for example to preparing the carcass ply 4 and the tread band 6. The fourth preparation unit 22d may be dedicated to preparing the sidewall reinforcement 12 or the reinforcement bead 11. The preparation units 22a, 22b, 22c, 22d may have a substantially horizontal and / or inclined longitudinal extension and may be placed one after the other successively so as to converge towards the building drum 13 from the same side.

[0142] Each of the preparation units 22a, 22b, 22c, 22d has a feed unit Ha, Hb, Hc, Hd, in which the corresponding semi-finished products 20a, 20b, 20c, 20d in the form of continuous strips are arranged, for example, the semi-finished products are wound in the form of reels or appropriately stored in containers, and these semi-finished products are gradually pulled out from the reels or containers during processing.

[0143] Each semi-finished product 20a, 20b, 20c, 20d has structural and geometrical characteristics suitable for obtaining the corresponding component to be manufactured and applied to the building drum 13. For example, in the first preparation unit 22a, a liner semi-finished product 20a made of airtight elastomeric material with a thickness between approximately 0.35 mm and 1 mm and a width between 70 mm and 120 mm can be arranged. In the second preparation unit 22b, a second semi-finished product can be arranged, such as a carcass ply semi-finished product 20b with a thickness between approximately 0.3 mm and 0.6 mm and a width between 110 mm and 450 mm, incorporating mutually parallel reinforcing cords inclined at an angle between 35° and 55° relative to the longitudinal extension of the semi-finished product itself. In the third preparation unit 22c, a third semi-finished product can be arranged, such as a tread band semi-finished product 20c made of elastomeric material with a thickness between approximately 1 mm and 8 mm and a width between 20 mm and 120 mm.

[0144] For ease of description, only the corresponding structural and functional characteristics of the preparation units 22a, 22b, 22c, and 22d are described below, mainly referring to the second preparation unit 22b, but these characteristics can be universally applied to each of the preparation units themselves.

[0145] exist Figure 6 In the embodiment of the present invention, each of the preparation units 22a, 22b, 22c, 22d comprises a conveyor belt 23 having a feed section 24 and a preparation section 25, which are aligned one after the other so as to define a substantially horizontal advancement plane P.

[0146] Preferably, the feed section 24 includes a strip-shaped feed belt 26 that is engaged around a respective first drive roller 27. The preparation section 25 further includes a respective strip-shaped preparation belt 28 that is engaged around a second drive roller 29. The upper sections of the respective feed belts 26 and 28 are coplanar and aligned with each other to define the aforementioned advancement plane P.

[0147] Preferably, the feed section 24 and the preparation section 25 are driven independently of each other at at least one of the respective first and second drive rollers 27 and 29 so as to be able to translate the respective feed belt 26 and preparation belt 28 at the same or different speeds as required.

[0148] The conveyor belt 23 is adapted to support semifinished products 20a, 20b, 20c, 20d coming from the respective feeding units Ha, Hb, Hc, Hd, wherein the lower surface S1 of said semifinished products rests against the advancement plane P, the preparation belt 28 and / or the feeding belt 26.

[0149] The cutting group 30 is suitable for transversely cutting the semi-finished products 20a, 20b, 20c, 20d so as to separate the said sections 21 of predetermined length from the semi-finished products themselves. The cutting group 30 operates along the aforementioned cutting line L, which is defined by the intersection of the semi-finished products 20a, 20b, 20c, 20d with a cutting plane Q which is transverse to the advancing plane P and completely intersects the semi-finished products themselves and is situated in the vicinity of the transition zone N between the feed section 24 and the preparation section 25.

[0150] The cutting-to-size process ensures that, at the beginning of each operating cycle, the end A of the semi-finished product 20a, 20b, 20c, 20d is positioned at the cutting line L. The execution of a new cutting process provides for the longitudinal advancement of the semi-finished product 20a, 20b, 20c, 20d along the advancement plane P and its gradual transfer from the feed section 24 to the preparation section 25, while the feed section 24 and the preparation section 25 are simultaneously activated. Preferably, during the transfer of the semi-finished product 20a, 20b, 20c, 20d from the feed section 24 to the preparation section 25, the feed section 24 and the preparation section 25 advance at the same speed in order to avoid subjecting the semi-finished product itself to undesirable stresses. Since the semi-finished product 20a, 20b, 20c, 20d is generally made of a green elastomeric material of limited thickness, it is, in practice, quite sensitive to tensile or compressive stresses generated by the speed difference between the feed section 24 and the preparation section 25, which can alter the length and / or width of the semi-finished product itself. Alternatively, the advancement speeds of the preparation section 25 and the feed section 24 can be differentiated in a controlled manner. For example, the translation speed of the preparation section 25 can be set slightly higher than the translation speed of the feed section 24 in order to facilitate the relaxation of the semi-finished products 20a, 20b, 20c, 20d or parts thereof along the advancement plane P.

[0151] Photoelectric cells, encoders or other suitable control means 31 (represented schematically only since they can be implemented in any convenient way) running on the conveyor belt allow to control the simultaneous actuation of the feed section 24 and the preparation section 25 so as to stop the advancement of the semi-finished product 20a, 20b, 20c, 20d when the head end A of the semi-finished product 20a, 20b, 20c, 20d, after having exceeded the cutting plane Q, reaches a predetermined cutting distance K relative to the cutting plane itself, as Figure 6 shown.

[0152] The cutting distance K is related to the circumferential extension of the deposition surface 15, for example so that the length of the obtained segment 21 corresponds to this circumferential extension. Alternatively, it can be provided that the cutting distance K and the resulting length of the obtained segment 21 are different relative to the circumferential extension of the deposition surface 15, for example slightly larger, in order to compensate for any elastic shrinkage of the material that may occur after the cutting is carried out and before application on the building drum 13.

[0153] In the vicinity of the transition zone N between the feed section 24 and the preparation section 25 , a lifting device 32 is also in operation, by means of which the semi-finished products 20 a, 20 b, 20 c, 20 d are adapted to be spaced apart from the advancement plane P. When the advancement of the semi-finished products 20 a, 20 b, 20 c, 20 d has ceased, the lifting device 32 engages the semi-finished products themselves at their cut portion T intersecting the cutting plane Q and raises them slightly from the advancement plane P in order to facilitate subsequent cutting by the cutting group 30 . The cutting group 30 is then activated so as to translate it transversely to the semi-finished product 20a, 20b, 20c, 20d and cut said semi-finished product along the cutting line L so as to determine the separation of the segment 21 having a desired length corresponding to the cutting distance K defined between its head end A1 and its tail end B, said head end previously belonging to the semi-finished product 20a, 20b, 20c, 20d, said tail end being obtained by the cutting operation together with the new head end A of the cut semi-finished product 20a, 20b, 20c, 20d.

[0154] After cutting, preparation section 25 is activated to advance segment 21 along conveyor belt 23 until head A1 carried by segment 21 reaches an end of conveyor belt 23 opposite feed units Ha, Hb, Hc, Hd and close to building drum 13 .

[0155] By means of the application devices 16, 17, 19 and / or the possible translation of the preparation section 25, the head end A1 of the segment 21 is positioned on the deposition surface 15 of the building drum 13 and held thereon, for example, by the action of a suction nozzle arranged on the deposition surface 15 itself or by adhering to the deposition surface or to a component previously deposited on the building drum 13. The building drum 13 is then actuated in rotation by means of a motor 33 or other suitable actuation means (not shown), while the conveyor belt 23 translates the segment 21 via the preparation section 25 at an advancement speed related to the peripheral speed of the deposition surface 15, so as to deposit the segment 21 circumferentially around the deposition surface 15.

[0156] Measuring devices can be arranged on the conveyor belt 23, these measuring devices optionally being fully or partially integrated into the aforementioned control device 31, and are configured to detect the length of the segments 21 on the preparation section 25 immediately before they are applied to the building drum 13. The measuring devices can be combined with a comparator 34 configured to compare the detected lengths of the segments 21 with the circumferential extension of the deposition surface 15. The comparator 34 is operatively connected to the aforementioned device 31 for controlling the conveyor belt 23, as well as to the motor 33 and / or other device configured to rotate the building drum 13, in order to adjust the translation speed of the conveyor belt itself relative to the peripheral speed of the deposition surface 15. For example, if the length of the segments 21 detected by the measuring devices differs slightly from the circumferential extension of the deposition surface 15, the translation speed of the conveyor belt 23 can be conveniently adjusted relative to the rotational speed of the building drum 13 in order to modify the length of the segments 21 and bring them into line with the circumferential extension of the deposition surface 15.

[0157] When the building drum 13 completes one full rotation about its axis of rotation XX, the trailing end B of the segment 21 joins the leading end A1 previously applied on the deposition surface 15, thereby completing the application of the tyre component.

[0158] The structural specifications of the preparation units 22a, 22b, 22c, 22d, with reference in particular to the lifting device 32 and the cutting group 30, can vary depending on the type of component to be obtained.

[0159] exist Figures 6 to 9 , a possible embodiment is shown for a second preparation unit 22b configured to manufacture a carcass ply / plies 4. To simplify the description and maintain consistency, this embodiment will be described herein with reference to the processing of a carcass ply semi-finished product 20b. Nevertheless, in addition to or as an alternative to what is described herein, the same embodiment can optionally be used, for example, on the first preparation unit 22a for manufacturing a liner 10 by processing a liner semi-finished product 20a, and / or for manufacturing other components by processing corresponding semi-finished products 20a, 20b, 20c, 20d.

[0160] like Figure 6As shown, the lifting device 32 and the cutting group 30 are mounted on a support structure 36 extending transversely above the conveyor belt 23. The support structure 36 (e.g., suspended from above at hinge pins 35) can be positioned at an angle about a vertical orientation axis YY. The orientation of the support structure 36 depends on the orientation of the cutting plane Q, which is appropriately inclined relative to the longitudinal extension of the carcass ply semi-finished product 20b for the purpose of processing the carcass ply 4. The angle of the cutting plane Q and the cutting line L can thus be modified depending on the orientation of the cords incorporated in the semi-finished product itself (preferably at an angle between 35° and 55° relative to the longitudinal extension of the carcass ply semi-finished product 20b).

[0161] The lifting device 32 comprises a plurality of suction cups 37 or another type of gripping elements, facing the propulsion plane P and distributed along two gripping lines situated side by side on opposite sides of the cutting plane Q and respectively upstream and downstream with respect to the propulsion direction of the carcass ply semi-finished product 20b. A pneumatic activation / deactivation circuit leads to the suction cups 37.

[0162] By one or more fluid powered cylinders 38 ( Figure 7 ), the suction cup 37 can be moved vertically toward and away from the propulsion plane P, between a lowered position and a raised position relative to the support structure 36. In the lowered position, the suction cup 37 acts on the upper surface S2 of the carcass ply semi-finished product 20b, while the lower surface S1 of the carcass ply semi-finished product 20b abuts against the propulsion plane P, as shown in FIG. Figure 9 As shown. The suction cup 37 holds the carcass ply semi-finished product 20b by applying a suction force at the upper surface S2 under the action of the suction force generated by the pneumatic activation / deactivation circuit (not shown). Then, by translating to the lifting position, the suction cup 37 lifts the carcass ply semi-finished product 20b from the pushing plane P at the cutting portion T, as shown. Figure 8 shown.

[0163] In order to achieve greater precision in performing the cuts, the suction cups 37, respectively arranged on each of the gripping lines, are spaced apart by a distance not exceeding 20 mm from one another, and they travel not exceeding 20 mm between their lowered and raised positions. This elevation is sufficient to allow the cutting group 30 to penetrate the carcass ply semi-finished product 20 b (or other semi-finished product) without interfering with the underlying mechanical components of the conveyor belt 23. The lifting action also generates a slight tension in the cut portion T of the carcass ply semi-finished product 20 b, which facilitates the separation of the segments 21 along the cutting line L.

[0164] exist Figures 6 to 9In the example of , the cutting group 30 preferably comprises a cutting member 39 in the form of a knife 39 arranged coplanar with the cutting plane Q. The knife 39 is fixed to a slide 40 movable along a guide 41 integral with the support structure 36 and parallel to the cutting plane Q.

[0165] While the carcass ply semi-finished product 20b is held in the raised position by the suction cup 37, an actuator (for example in the form of a threaded rod 42 and driven in rotation) moves the slide 40 and the knife 39 it carries along the cutting line L from the starting position to the arrival position, thereby determining the separation of the segment 21 from the carcass ply semi-finished product 20b, said segment and said carcass ply semi-finished product being located downstream or upstream of the cutting plane Q, respectively.

[0166] The ultrasonic transducer 43 may be conveniently operated on the cutting group 30 to impart ultrasonic frequency vibrations thereto that assist in performing the cutting. Figure 7 As can be seen more clearly in FIG, the knives 39 of the cutting group 30 preferably have cutting edges 39a extending in an oblique direction relative to the propulsion plane P, so as to form an acute angle β with the propulsion plane itself, the apex of which points towards the arrival position, i.e., upwards during the translation of the cutting group 30 towards the arrival position. This ensures that, during the cutting operation, the cutting edges 39a transmit a vertical thrust component directed away from the propulsion plane P to the carcass ply semi-finished product 20b, so as to facilitate the holding action of the suction cups 37. Furthermore, the end edges of the carcass ply semi-finished product 20b and of the segment 21 cut along the cutting line L will tend to point upwards, so as to limit the risk of undesirable jamming during subsequent movement in the propulsion plane P.

[0167] Provision is also preferably made that, during the cutting of the carcass ply semi-finished product 20b, the cutting group 30 is translated towards the building drum 13. This advantageous measure ensures that, when the cutting edge 39a of the knife 39 encounters the edge of the carcass ply semi-finished product 20b, possible stresses or other deformations imparted on the material tend to be concentrated on the terminal apex of the trailing end B of the cut segment 21, rather than on the terminal apex of the leading end upstream of the cutting line L.

[0168] After the cut has been carried out, the new head end A formed on the carcass ply semi-finished product 20b just cut engages with the suction cups 37 arranged along the gripping line situated upstream of the cutting plane Q. The tail end B of the segment 21 obtained is then held in place by the suction cups 37 arranged along the gripping line situated downstream of the cutting plane Q. After the cutting group 30 has reached the arrival position, the suction cups 37 respectively situated upstream and downstream of the cutting plane Q can be brought back to the lowered position simultaneously or at different times in order to reposition the head end A of the cut carcass ply semi-finished product 20b and the tail end B of the cut segment 21 respectively against the thrust plane P.

[0169] After the repositioning is completed, the cutting group 30 can be brought back to the starting position without interfering with the head end A of the cut carcass ply semi-finished product 20 b and / or the tail end B of the segment 21 .

[0170] The cutting plane Q can advantageously be positioned so as to completely intersect the carcass ply semi-finished product 20b at a position slightly upstream of the transition zone N between the feed section 24 and the preparation section 25, so that the cutting group 30 operates above the feed section 24, adjacent to the transition zone itself. Thus, as the suction cup 37 descends towards the lowering position, the tail end B of the cut segment 21 is deposited on the terminal portion of the feed section 24 and thus reaches the transition zone N. When the repositioning is completed, the activation of the preparation belt 28 determines the transfer of the tail end B onto the preparation section 25, while the entire segment 21 is advanced towards the building drum 13. During the transfer of the tail end B towards the preparation section 25, the feed belt 26 can be temporarily kept inactive in order to facilitate the movement of the segment 21 away from the carcass ply semi-finished product 20b.

[0171] Alternatively, provision may be made for the simultaneous activation of the feed belt 26 and the preparation belt 28 so as to also determine the advancement of the carcass ply semi-finished product 20b on the feed section 24 so as to cause it to pass through the transition zone N and continue along the advancement plane P at the same preparation section 25. In this case, it is preferred that, during the transfer of the trailing end B, the segment 21 on the preparation section 25 is translated at a speed greater than the advancement speed of the carcass ply semi-finished product 20b on the feed section 24 so as to drive the trailing end B onto the preparation section 25, thereby facilitating the release of possible stresses and / or other deformations generated during the cutting action, thereby facilitating its movement away from the head end of the carcass ply semi-finished product 20b that has just been cut.

[0172] After the tail end B of the section 21 has been transferred to the preparation section 25, the advancement speeds of the carcass ply semi-finished product 20b on the preparation section 25 and the feed section 24 can be made equal relative to each other, so that the carcass ply semi-finished product 20b can be evenly advanced through the transition zone N without subjecting the same semi-finished product to undesirable tensile stresses. It should be observed that what has been described above with respect to the processing of the carcass ply semi-finished product 20b is also intended to apply to any other type of semi-finished product 20a, 20b, 20c, 20d being processed.

[0173] exist Figure 10 and Figure 11, a possible embodiment variant is shown, which is applied to a fourth preparation unit 22d configured to manufacture a sidewall insert 12. This embodiment variant is in fact also particularly suitable for operating on semi-finished products incorporating reinforcing cords running in a cross direction, such as those generally suitable for manufacturing sidewall reinforcements 12, reinforcing beads 11 and / or protective strips 7, 8. Therefore, for the sake of simplicity of description and consistency, only reference will be made to the processing of the sidewall insert semi-finished product 20d. Figures 7 to 9 However, in addition to or as an alternative to what is described here, the same embodiment can optionally be used, for example, on the first preparation unit 22a and the second preparation unit 22b for manufacturing a carcass ply 4 by processing the carcass ply semi-finished product 20b, and / or for manufacturing other components.

[0174] This embodiment variant is conceptually similar to the above embodiment, but differs due to the structural and functional characteristics of the cutting group 30 and the lifting device 32. Structural components and details not specified can be referred to Figures 7 to 9 An embodiment of is manufactured in a manner conceptually similar to that described above.

[0175] In this case, the lifting device 32 does not employ the aforementioned suction cup 37, but instead comprises a lifting insert 44 arranged flush with the advancing plane P so that the sidewall insert semi-finished product 20d passing over it passes over it. The lifting insert 44 is generally rod-shaped, with its longitudinal extension parallel to the cutting plane Q. The width of the lifting insert 44 is defined between an entry edge 45 directed toward the sidewall insert feed unit Hd (i.e., in a direction opposite to the direction of advancement of the sidewall insert semi-finished product 20d along the advancing plane P) and an exit edge 46 directed toward the building drum 13 (i.e., in the direction of advancement of the sidewall insert semi-finished product 20d). A sliding surface 47 extends upward between the entry edge 45 and the exit edge 46, which is oriented obliquely relative to the advancing plane P, in a direction away from the advancing plane P toward the building drum 13 (i.e., in the direction of advancement of the sidewall insert semi-finished product 20d).

[0176] The sliding surface 47 is suitable for supporting the side wall insert half-finished product 20 d while its lower surface S1 slidably rests against the lifting insert 44 itself during its translation along the advancement plane P. The diverging course of the sliding surface 47 ensures that a recess 48 is formed between the lower surface S1 of the side wall insert half-finished product 20 d and the advancement plane P along the outlet edge 46 .

[0177] Instead of the knife 39, the cutting member comprises a rotating blade 49, which is disc-shaped and is actuated to rotate at high speed about its geometric axis ZZ, which is parallel to the propulsion plane P and orthogonal to the cutting plane Q. The rotating blade 49 is located in the cutting plane Q and is operatively carried by a corresponding slide 40 that is movable along a guide 41. During the cutting operation, the rotating blade 49 rotates about its geometric axis ZZ and translates along the guide 41 from a starting position to an arrival position, while its own peripheral edge 49a traverses the sidewall insert blank 20d, thereby translating in a recess 48 laterally delimited by the outlet edge 46 of the lifting insert 44.

[0178] Preferably, the direction of rotation of the rotary blade 49 is selected in such a way that, at the point of intersection of its cutting edge 39a with the side wall insert blank 20d, the rotary blade 49 rotates in a direction opposite to the direction of its own advancement towards the arrival position. Thus, the action of the rotary blade 49 advantageously tends to move the edge of the leading end A of the newly cut side wall insert blank 20d and the edge of the trailing end B of the resulting segment 21 away from the advancement plane P.

[0179] Figures 12 to 15 A possible further embodiment is shown, which is applied to a third preparation unit 22 configured for manufacturing a tread band 6. In this case too, for the sake of simplicity and coherence, this further embodiment variant will be described herein with reference to the processing of a tread band semi-finished product 20 c. Nevertheless, in addition to or as an alternative to what is described herein, the same embodiment can optionally be used, for example, on the first preparation unit 22 a for manufacturing a liner 10 by processing a liner semi-finished product 20 a, an elastomeric substrate 9, and / or for manufacturing other components by processing corresponding semi-finished products 20 a, 20 b, 20 c, 20 d.

[0180] This further embodiment variant is also similar in concept to the above embodiment and differs from the above embodiment mainly by the structural and functional characteristics of the cutting group 30 and the lifting device 32. The structural components and details not specified can be replaced by those in a conceptually similar manner to those of reference 1. Figures 7 to 9 The embodiments are manufactured in the manner described above.

[0181] exist Figures 12 to 15 , the lifting device 32 comprises an abutment plate 50 inserted in the transition zone N between the feed section 24 and the preparation section 25 of the conveyor belt 23 and located at the cutting plane Q. In practice, the cutting plane Q intersects the advancement plane P at the abutment plate 50 .

[0182] The abutment plate 50 is movable between a rest position, in which it is substantially coplanar with the propulsion plane P (e.g., Figure 13In the working position, the abutment plate is raised relative to the propulsion plane P (as shown in FIG. Figure 14 shown).

[0183] When the conveyor belt 23 is activated to advance the tread band semi-finished product 20c towards the building drum 13, the semi-finished product itself slides on the abutment plate 50 in the rest position. After the tread band semi-finished product 20c has stopped advancing and the required cutting distance K is reached between its head end A and the cutting plane Q, the abutment plate 50 is then brought into the working position. Thus, the tread band semi-finished product 20c is raised relative to the advancing plane P at its cutting portion T, which is passed through by the cutting plane Q.

[0184] The cutting members of the cutting group 30 are in the form of blades 51 rigidly carried by respective slides 40 capable of movement along guides 41 which are in turn integral with the support structure 36 extending transversely above the conveyor belt 23. The orientation of the guides 41 is transverse to the longitudinal extension of the conveyor belt 23 and preferably perpendicular thereto, so that the cutting plane Q intersects the advancing plane P in an orientation perpendicular to the longitudinal extension of the tread band semi-finished product 20c. Furthermore, the blades 51 and therefore the cutting plane Q have an inclined orientation defining a first acute angle β1 ( Figure 14 ), the apex of said first acute angle being directed in the direction of advancement of the semi-finished product itself, i.e. towards the preparation section 25 and towards the building drum 13. This inclination facilitates obtaining oblique cuts at the head end A1 and the tail end B of the segment 21 separated from the tread band semi-finished product 20c, thus facilitating its joining on the building drum 13. Preferably, the value of the first acute angle β1 is between 15° and 30°.

[0185] When the abutment plate 50 is in the working position, the cutting group 30 is adapted to be translated from the starting position towards the arrival position by moving the blade 51 along the cutting line L, so as to determine the separation of the segment 21 from the corresponding tread band semi-finished product 20 c. The execution of the cutting can be facilitated by high-frequency vibrations, preferably ultrasonic waves, transmitted to the cutting group 30 by the corresponding ultrasonic transducer 43 .

[0186] It is also preferably provided that the cutting edge 51a of the blade 51 is located in the cutting plane Q in an orientation inclined relative to the cutting line L. Thus, at one end of the cutting edge 51a, a cutting vertex 52 pointing toward the abutment plate 50 can be identified. During the execution of the cut, the cutting edge 51a, starting from the cutting vertex 52, moves away from the abutment surface 50a present on the upper part of the abutment plate 50 ( Figure 12 More specifically, the cutting edge 51a is in the cutting plane Q and forms a second acute angle β2 with respect to the advancing plane P ( Figure 15), the apex of the second acute angle pointing towards the starting position. In this way, the cutting edge 51a is suitable for transmitting a thrust component directed towards the abutment plate 50 to the tread band semi-finished product 20c during the translation of the cutting group 30 towards the arrival position. Preferably, the value of the second acute angle β2 is between 5° and 15°.

[0187] Furthermore, the cutting edge 51a forms a third acute angle β3 ( Figure 12 ), the apex of the third acute angle points towards the starting position. In this way, the cutting edge 51a is facilitated to penetrate into the tread band semi-finished product 20c. Preferably, the value of the third acute angle β3 is between 5° and 25°.

[0188] During the translation of the cutting group 30, the cutting apex 52 is preferably adapted to operate through the tread band semi-finished product 20c without the presence of direct contact between the cutting group 30 and the abutment plate 50 itself. In practice, it is convenient to provide that the abutment surface 50a of the abutment plate 50 and the cutting apex 52 of the cutting group 30 are separated by a value not greater than 0.05 mm. Thus, a clean cut of the tread band semi-finished product 20c can be achieved without determining mechanical interference between the cutting group 30 and the abutment plate 50, to the benefit of the service life of the cutting edge 51a and the effectiveness of the ultrasonic vibrations transmitted to the cutting group 30.

[0189] Preferably, the action of the cutting group 30 is assisted by blocking means 53 of the tread band semi-finished product 20c relative to the propulsion plane P, said blocking means operating near the abutment plates 50. These blocking means 53 comprise at least one push plate configured to bear elastically, by its terminal edge, against the tread band semi-finished product 20c during the execution of the cuts.

[0190] More particularly, provision is preferably made for a first thrust plate 54a and a second thrust plate 54b to operate respectively upstream and downstream of the cutting plane Q and to be selectively activated so as to push the tread band semi-finished product 20c and thus exert a holding action on the semi-finished product itself, preferably against the abutment plate 50. Each of the first thrust plate 54a and the second thrust plate 54b can conveniently be made in the form of an elastically deformable plate having a plurality of elastically deformable tabs 55 respectively parallel and distributed along their terminal edges.

[0191] Before the cutting group 30 acts on the tread band semi-finished product 20c, the first and second pushing plates 54a, 54b are adapted to be moved from a waiting position (eg Figure 13 shown, in which they are spaced apart from the semi-finished product itself) to a pushing position (as shown Figure 14As shown, in said pushing position they operate against the tread band semi-finished product 20c so as to hold it gently against the abutment plate 50). Thus, the tread band semi-finished product 20c is suitably stabilized against the abutment plate 50 and cutting can be performed without causing undesired lateral movements of the semi-finished product itself under the effect of the thrust transmitted by the blades 51.

[0192] After the cutting is completed, the first and second push plates 54a, 54b can be returned to the waiting position and the abutment plate 50 is brought back to the rest position so as to reposition the trailing end B of the cut segment 21 and the new leading end A formed on the freshly cut tread band semi-finished product 20c coplanar with the advancement plane P.

[0193] Similarly to the above, the cut segments 21 are therefore adapted to be advanced towards the building drum 13 under the action of the preparation section 25 of the conveyor belt 23 in order to determine the winding of the tread band around the deposition surface 15 by the tread band application device 19 .

[0194] In addition to or as an alternative to at least one of these tire components, the cut-to-size process described above, in particular with reference to the carcass ply(s) 4, the sidewall insert 12, and the tread band 6, can advantageously be performed on other components, such as the liner 10, the elastomeric base 9, the reinforcing beads 11, and / or the protective belt(s) 7, 8, which may optionally be provided in the construction of the tire 2. For each of these components, provision is generally made for the arrangement of a corresponding semi-finished product 20a, 20b, 20c, 20d in the form of a continuous strip, the structural, width, and thickness characteristics of which correspond to those of the corresponding tire component, which is subjected to the cut-to-size process before being applied around the laying surface 15 of the building drum 13. For the treatment of components applied in pairs, such as the sidewall reinforcement 12, provision can be made for the arrangement of a pair of sidewall reinforcement semi-finished products, the cutting-to-size process being performed on them simultaneously or independently, and then the resulting segments being applied simultaneously or independently.

Claims

1. A process for building a tire for a bicycle, wherein: Laying down a plurality of components of a tyre (2) being processed circumferentially around a laying surface (15) carried by a building drum (14), wherein the process comprises: laying at least one carcass ply (4) circumferentially around the laying surface (15); applying a pair of bead cores (5) around the carcass ply (4) at a predetermined mutual axial distance; Turning up the axially outer end flap (4a) of the carcass ply (4) around the bead core (5); applying the tread band (6) circumferentially around the application surface (15), keeping the mutual axial distance of the bead cores (5) substantially constant; wherein, before laying at least one of the components, the corresponding semi-finished product (20a, 20b, 20c, 20d) in the form of a continuous strip is subjected to a process of cutting to size along a cutting line (L) in order to separate sections (21) of predetermined cutting length from the semi-finished product itself; The cutting process according to size includes: Positioning the semi-finished products (20a, 20b, 20c, 20d) with their lower surfaces (S1) against a propulsion plane (P) defined by a conveyor belt (23) comprising a feed section (24) and a preparation section (25) aligned successively; longitudinally advancing the semi-finished product (20a, 20b, 20c, 20d) along the advancing plane (P); After the semi-finished product (20a, 20b, 20c, 20d) has exceeded a cutting plane (Q) intersecting the advancing plane (P) and containing the cutting line (L), the advancement of the semi-finished product (20a, 20b, 20c, 20d) is stopped when the head end (A) of the semi-finished product (20a, 20b, 20c, 20d) reaches a predetermined cutting distance (K) relative to the cutting plane (Q); At a cutting portion (T) of the semi-finished product (20a, 20b, 20c, 20d) intersecting the cutting plane (Q), the semi-finished product (20a, 20b, 20c, 20d) is lifted relative to the advancing plane (P); cutting the semi-finished product (20a, 20b, 20c, 20d) transversely along the cutting line (L) so as to separate the segments (21) of predetermined length from the semi-finished product itself; Advancing the segment (21) along the conveyor belt (23) so as to position and stop the head end (A) on the deposition surface (15); The building drum (13) is actuated in rotation while the conveyor belt (23) translates the segments (21) at an advancement speed related to the peripheral speed of the deposition surface (15) so as to deposit the segments (21) circumferentially around the deposition surface (15).

2. The process according to claim 1, wherein The cutting distance (K) is related to the circumferential extension of the deposition surface (15).

3. The process according to claim 1 or 2, further comprising: detecting the length of the section (21) on the preparation section (25); comparing the detected length of the segment (21) with the circumferential extension of the deposition surface (15); During the laying of the segments (21) on the building drum (13), the translation speed of the conveyor belt (23) is adjusted relative to the rotation speed of the building drum (13) so as to vary the length of the segments (21) and bring it into line with the circumferential extension of the laying surface (15).

4. Process according to one or more of the preceding claims, wherein Said components comprise a liner (10) the laying of which is activated before the laying of said at least one carcass ply (4) and which comprises: Arranging a lining semi-finished product (20a) in the form of a continuous strip; The lining semi-finished product (20a) is subjected to the cutting-to-size process.

5. The process according to claim 4, wherein The thickness of the lining semi-finished product (20a) is between 0.35 mm and 1 mm.

6. Process according to one or more of the preceding claims, wherein The laying of the at least one carcass ply (4) comprises: Arranging a carcass ply semi-finished product (20b) in the form of a continuous strip; The carcass ply semi-finished product (20b) is subjected to the cutting-to-size process.

7. The process according to claim 6, wherein The thickness of the carcass ply semi-finished product (20b) is between 0.3 mm and 0.8 mm.

8. Process according to one or more of the preceding claims, wherein Said component comprises a sidewall reinforcement (12), the laying of which is activated after turning up of said terminal flap (4a) and before laying of said tread band (6), wherein the laying of said sidewall reinforcement (12) comprises: Arranging a pair of side wall reinforcement semi-finished products (20d), each side wall reinforcement semi-finished product being in the form of a continuous strip; The side wall reinforcement semi-finished product (20d) is subjected to the cutting-to-size process.

9. Process according to one or more of the preceding claims, wherein Said components comprise at least one protective belt (7, 8), the laying of which is activated before the laying of said tread band (6), wherein the laying of said at least one protective belt (7, 8) comprises: Arrangement of the protective tape semi-finished product in the form of a continuous strip; The protective tape semi-finished product is subjected to the cutting-to-size process.

10. Process according to one or more of the preceding claims, wherein Said components comprise an elastomeric substrate (9), the laying of which is activated before the laying of said tread band (6), wherein the laying of said elastomeric substrate (9) comprises: Arranging the elastomeric substrate semi-finished product in the form of a continuous strip; The elastomeric substrate semi-finished product is subjected to the cutting-to-size process.

11. Process according to one or more of the preceding claims, wherein The laying of the tread band (6) comprises: Arranging a tread band semi-finished product (20c) in the form of a continuous strip; The tread band semi-finished product (20c) is subjected to the cutting-to-size process.

12. The process according to claim 11, wherein The thickness of the tread band semi-finished product (20c) is between 1 mm and 8 mm.

13. An apparatus for building tires for bicycles, the apparatus comprising: Construct drum (13); a layup group (14) configured to lay down a plurality of components circumferentially around a layup surface (15) carried by the building drum (13); Wherein, the laying group (14) includes: a carcass ply application device (16) configured for laying at least one carcass ply (4) circumferentially around a laying surface (15) carried by the building drum (13); means for applying a pair of bead cores (5) around said carcass ply (4) at a predetermined mutual axial distance; a turning-up device (13) configured to turn up the axially outer end flap (4a) of the carcass ply (4) around the bead core (5); a tread band application device (19) configured for applying a tread band (6) circumferentially around said laying surface (15) and in an axially centered position between said bead cores (5) arranged according to said predetermined mutual axial distance; wherein the laying group (14) comprises at least one preparation unit (22a, 22b, 22c, 22d) configured for cutting a semi-finished product (20a, 20b, 20c, 20d) in the form of a continuous strip transversely to size along a cutting line (L) so as to separate sections (21) of predetermined cutting length from the semi-finished product itself; Wherein, the preparation unit (22a, 22b, 22c, 22d) includes: a conveyor belt (23) comprising a feed section (24) and a preparation section (25), the feed section and the preparation section being aligned successively according to a propulsion plane (P), the propulsion plane being configured for supporting the semi-finished products (20a, 20b, 20c, 20d), wherein the lower surface (S1) of the semi-finished products rests on the propulsion plane (P) itself; a device (31) for controlling the conveyor belt (23), configured to advance the semi-finished products (20a, 20b, 20c, 20d) longitudinally along the advancing plane (P) and to stop the advancement of the semi-finished products (20a, 20b, 20c, 20d) when the head end (A) of the semi-finished products (20a, 20b, 20c, 20d) reaches a predetermined distance relative to a cutting plane (Q) intersecting the advancing plane (P) and containing the cutting line (L); a lifting device (32) configured to raise the semi-finished product (20a, 20b, 20c, 20d) relative to the advancing plane (P) at a cutting portion (T) of the semi-finished product (20a, 20b, 20c, 20d) intersecting the cutting plane (Q); a cutting group (30) configured to cut the semi-finished product (20a, 20b, 20c, 20d) transversely along the cutting line (L) so as to separate the segments (21) of predetermined length from the semi-finished product itself; Means (33) for actuating the building drum (13) in rotation while the conveyor belt (23) translates the segments (21) at an advancement speed related to the peripheral speed of the deposition surface (15) so as to deposit the segments (21) circumferentially around the deposition surface (15).

14. Apparatus according to claim 13, further comprising means for measuring the length of the section (21) on the preparation section (25).

15. The device according to claim 13 or 14, further comprising: a comparator (34) configured to compare the length of the segment (21) detected by the measuring device with the circumferential extension of the deposition surface (15); wherein the comparator (34) is operatively connected to the means (31) for controlling the conveyor belt (23) and the means (33) for actuating the rotation of the building drum (13) so as to regulate the translation speed of the conveyor belt (23) relative to the peripheral speed of the laying surface (15).

16. Apparatus according to one or more of claims 13 to 15, wherein The at least one preparation unit (22a, 22b, 22c, 22d) has a substantially horizontal longitudinal extension.

17. Apparatus according to one or more of claims 13 to 16, wherein The laying group (14) comprises at least two preparation units (22a, 22b, 22c, 22d).

18. Apparatus according to one or more of claims 13 to 15, wherein The laying group (14) includes at least three preparation units (22a, 22b, 22c, 22d).

19. The apparatus according to claim 17 or 18, wherein The preparation units (22a, 22b, 22c, 22d) are stacked one on top of another.

20. Apparatus according to one or more of claims 17 to 19, wherein The preparation units (22a, 22b, 22c, 22d) converge towards the building drum (13) from the same side.

21. Apparatus according to one or more of claims 13 to 20, wherein The feed section (24) comprises a strip-shaped feed belt (26) engaged around respective first drive rollers (27).

22. Apparatus according to one or more of claims 13 to 21, wherein The preparation section (25) comprises a strip-shaped preparation belt (28) engaged around a second drive roller (29).

23. Apparatus according to one or more of claims 13 to 22, wherein The respective upper sections of the feed belt (26) and the preparation belt (28) are aligned in a coplanar manner to define the aforementioned advancing plane (P).

24. Apparatus according to one or more of claims 13 to 22, wherein The feed section (24) and the preparation section (25) are driven independently of each other.

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