Process and apparatus for building tyres for bicycles

Abstract

When building tyres (2) for bicycles, before laying at least one of the components, a process of cutting a semi-finished product (20a, 20b, 20c, 20d) according to dimensions is first performed, said semi-finished product being advanced against an advancing plane (P) defined by a conveyor belt (23) comprising a feed section (24) and a preparation section (25) which are continuously aligned. The advancing of the semi-finished product is stopped and an abutment plate (50) placed between the feed section (24) and the preparation section (25) is lifted together with the cut section (T) of the semi-finished product relative to the advancing plane (P). A cutting member (51) translates transversely to the semi-finished product to cut the semi-finished product along a cutting line (L). An abutment plate (50) carrying the tail end (B) and the head end (A) of the cut semi-finished product is repositioned coplanar with the advancing plane (P).

Description

TECHNICAL FIELD

[0001] The present invention relates to a process for constructing a tire for a bicycle. The object of the present invention also lies in a device for constructing a tire for a bicycle, which device is adapted to carry out the above process. BACKGROUND ART

[0002] The terms "radial" and "axial", and the expressions "radially inner / outer" and "axially inner / outer" are used with reference to the radial direction and the axial direction of the building drum used for constructing the tire and / or of the tire itself, i.e., with reference to the direction perpendicular to the axis of rotation of the building drum / tire and the direction parallel to the axis of rotation of the building drum / tire, respectively.

[0003] For the term "application surface", it is intended to denote a substantially cylindrical surface existing in a radially outer position with respect to the building drum. When no tire component is applied on the building drum, the application surface belongs to the actual building drum. In an intermediate step of the building process, the application surface can be represented by the tire components already applied on the building drum.

[0004] The construction of a tire for a bicycle generally provides that one or more carcass plies are applied around the outer surface of the building drum in a cylindrical configuration. Each of a pair of bead cores is assembled or applied around one of the axially opposite end flaps of the carcass ply. Then the end flaps are turned up around the respective bead cores. Thereafter, a tread band is applied, which tread band is generally in the form of a cut-to-size strip made of an elastomeric material and is wound around the carcass ply laid against the building drum and is axially centered with respect to the bead cores.

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

[0006] During 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 differentiates a tire for a bicycle from a tire for a motor vehicle. In fact, for a tire for a motor vehicle, steps are usually provided to bring the bead cores closer to each other so that the carcass structure takes the form of a toroidal configuration when joined to a belt structure having a diameter greater than the diameter of the bead cores.

[0007] After construction, the green tire for a bicycle that has been constructed is removed from the building drum and transferred to a vulcanization press to undergo a molding and vulcanization process aimed at determining the structural stability through crosslinking of the elastomeric material present therein and, optionally, imparting a desired tread design to the tread band.

[0008] For example, in the video clip at https: / / youtu.be / e3sHyJKaFMo?t=879 (timing from 14'37" to 15'50" - last viewed on December 14, 2022), the successive laying of the carcass ply, bead core, sidewall reinforcement, bead reinforcement, and tread band can be seen to build a tire for a bicycle on a building drum. Each of these components is made from a semi-finished product in the form of a continuous strip from a respective feed group in a manner synchronized with its laying process, the feed group guiding the semi-finished product to a position adjacent to the application point on the building drum where the operator performs the operations required to apply the semi-finished product. The application of each component provides for the manual fixing of the head end of the respective semi-finished product on the laying surface of the building drum, after which the building drum makes one or more revolutions about its axis of rotation to define the circumferential winding of the semi-finished product around the laying surface. For several components, such as the carcass ply, sidewall reinforcement, reinforced bead, and tread band, the operator is required to perform manual operations on the semi-finished product and / or the building drum during the winding process to assist in the correct distribution and application of the material.

[0009] For the sidewall reinforcement, the operator is also required to manually guide the semi-finished product for correct alignment and manually control its tension. At the end of the winding of each component, the building drum stops rotating and the operator must manually cut the semi-finished product and join the tail end of the resulting component to the head end previously applied on the laying surface.

[0010] Therefore, in the current state of the art, even with the assistance of an automatic or semi-automatic feed system for the semi-finished products, the assembly operations of the components on the building drum require specialized labor to obtain the correct positioning, distribution, tensioning, and / or dimensional cutting of the semi-finished products themselves for the manufacture of the components on the building drum. Summary of the Invention

[0011] The Applicant has proposed to automate the above-described existing building process, but the Applicant has found that the machines and methods commonly used to manufacture tires for motor vehicles (e.g., cars and / or motorcycles) cannot be used to manufacture tires for bicycles. In fact, the building operations for tires for bicycles require the preparation and manipulation of extremely thin and precise finished products. The thickness of many components (e.g., liners, carcass plies, and other fabric 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 a value of 450 mm. Additionally, components made of elastomeric materials (e.g., liners) can have a thickness within the above range, for example, less than 0.35 mm, but a width greater than 120 mm. These dimensional characteristics almost always result in a lack of structural consistency in the semi-finished products used that is sufficient to allow the machines commonly used to build tires for motorcycles or cars to correctly process the semi-finished products.

[0012] However, the need to use specialized labor involves a reduction in productivity and a significant increase in production costs, especially in cases where specific production precision and consistency (i.e., repeatability) are required, such as when producing tires intended for sports use (where the structural precision is reflected in performance). There are also problems in terms of the safety of the operators, who often have to perform different work operations with their hands in the vicinity of and / or in direct contact with movable parts, which poses a risk of injury.

[0013] The present applicant has realized that by adding a cutting step to the above operation sequence, the previously encountered drawbacks may be overcome.

[0014] More precisely, the present applicant has found that by separating workpieces of appropriate length from each semi-finished product before applying the semi-finished product, it may contribute to the correct manipulation of the material to manufacture individual components of the tire on a building drum.

[0015] According to the present invention, the present applicant has also found that by appropriately lifting the semi-finished product relative to the advancement plane of the semi-finished product in the section where the cutting line passes, it helps to separate the workpiece from the remaining semi-finished product by performing precise cutting 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.

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

[0017] Preferably, it is provided that at least one carcass ply is applied around the laying surface.

[0018] Preferably, it is provided that a pair of bead cores is applied around the carcass ply at a predetermined mutual axial distance.

[0019] Preferably, it is provided that the outer end flaps of the carcass ply are axially turned up around the bead cores.

[0020] Preferably, it is provided that the tread band is laid around the laying surface while keeping the mutual axial distance of the bead cores substantially unchanged.

[0021] Preferably, before laying at least one of the components, the corresponding semi-finished product in the form of a continuous strip is dimensionally cut along a cutting line so as to separate a workpiece having a predetermined cutting length from the semi-finished product itself.

[0022] Preferably, the sizing process comprises positioning the semi-finished product such that its lower surface abuts against a propulsion plane defined by a conveyor belt, said conveyor belt comprising a continuously aligned feed section and a preparation section.

[0023] Preferably, the sizing process comprises longitudinally advancing the semi-finished product along the propulsion plane and above an abutment plate disposed between the feed section and the preparation section.

[0024] Preferably, the sizing process comprises stopping the advancement of the semi-finished product relative to a cutting plane that includes a cutting line and intersects the propulsion plane at the abutment plate when the head and tail ends of the semi-finished product are separated from the cutting plane by a measurement equal to the cutting length.

[0025] Preferably, the sizing process comprises lifting the abutment plate and the cut section of the semi-finished product disposed on said abutment plate relative to the propulsion plane.

[0026] Preferably, the sizing process comprises translating a cutting member transversely to the semi-finished product to cut the semi-finished product along the cutting line.

[0027] Preferably, provisions are made to reposition the abutment plate carrying the tail end of the cut workpiece and the head end of the cut semi-finished product to be coplanar with the propulsion plane.

[0028] In another aspect, the present invention relates to a device for constructing a tire for a bicycle, said device comprising a building drum and a laying group, said laying group being configured to circumferentially lay a plurality of components around a laying surface carried by the building drum.

[0029] Preferably, the laying group includes a carcass ply applying device configured to lay at least one carcass ply around the laying surface.

[0030] Preferably, the laying group includes a bead core applying device for applying a pair of bead cores around the carcass ply at a predetermined mutual axial distance.

[0031] Preferably, the laying group includes a turning-up device configured to axially turn up the outer end flaps of the carcass ply around the bead cores.

[0032] Preferably, the laying group includes a tread applying device configured to apply a tread around the laying surface and to position the tread in an axially centered position between bead cores arranged at said predetermined mutual axial distance.

[0033] Preferably, the laying group includes at least one preparation unit configured to transversely cut along the cutting line to set the dimensions of the semi-finished product in the form of a continuous strip, so that workpieces with a predetermined cutting length are separated from the semi-finished product itself.

[0034] Preferably, the preparation unit includes a conveyor belt that includes a feeding section and a preparation section. The feeding section and the preparation section are continuously aligned according to a propulsion plane transverse to the cutting plane including the cutting line and are configured to support the semi-finished product with the lower surface of the semi-finished product abutting against the propulsion plane itself.

[0035] Preferably, the preparation unit includes control means for controlling the conveyor belt, the control means being configured to longitudinally advance the semi-finished product along the propulsion plane and to stop the advancement of the semi-finished product when the leading end of the semi-finished product is separated from the cutting plane by a measurement equal to the cutting length.

[0036] Preferably, the preparation unit includes an abutment plate disposed between the feeding section and the preparation section of the conveyor in the cutting plane and movable between a rest position and a working position. In the rest position, the abutment plate is substantially coplanar with the propulsion plane, and in the working position, the abutment plate is lifted relative to the propulsion plane to lift the cutting section of the semi-finished product traversed by the cutting plane relative to the propulsion plane.

[0037] Preferably, the preparation unit includes a cutting member movable transversely to the semi-finished product to cut the semi-finished product along the cutting line.

[0038] The Applicant believes that workpieces pre-cut to size are easier to handle than semi-finished products directly fed from the feed reel, such that their application can be carried out in an automated manner with high precision and repeatability without imposing excessive stress and / or risk of distortion on the component itself.

[0039] Then, it is possible to initiate an operation that appropriately automates the application of the tread strip of a tire intended for a bicycle to a building drum, thus contributing to obtaining higher processing precision, which is beneficial for improving the quality of the final product, reducing production costs and ensuring the safety of production supervisors.

[0040] The Applicant further believes that performing the lift near the cutting line allows for the creation of a tension-controlled area along the semi-finished product, which helps to perform the cutting and separate the trailing end of the resulting workpiece from the leading end of the continuous semi-finished product. Thus, even for very thin and less robust semi-finished products (in which the elastomer in the green state that makes up the semi-finished product tends to deform and generate stress under the action of the cutting member (i.e., deformation and the resulting local material buildup)), precise cutting is facilitated. Then, the workpiece pre-cut from the semi-finished product is adjusted to translate easily along the advancement plane until the application area, such that laying can be performed precisely around the building drum without applying uncontrolled stretching or twisting to the workpiece itself.

[0041] The Applicant finally believes that the abutment plate for determining the lift of the semi-finished product provides appropriate suppression of the stress transmitted from the cutting edge of the cutting member to the semi-finished product, thus helping to perform precise cutting even on very slender and / or less robust semi-finished products.

[0042] In at least one advantageous embodiment, the invention further includes one or more of the following preferred features.

[0043] Preferably, during the application of the tread strip, the axially central portion of the at least one carcass ply abuts against the laying surface, and the axially central portion extends axially through the axial midline plane equidistant from the bead cores.

[0044] Preferably, the lifting action includes holding the semi-finished product on the upper surface opposite to the lower surface of the semi-finished product along two side-by-side clamping lines respectively located on opposite sides of the cutting plane.

[0045] Preferably, after repositioning the abutment plate, the cutting member is brought back to the starting position.

[0046] Thus, the mobility of the abutment plate helps to perform precise processing, thereby preventing unwanted interference between the cutting member and the semi-finished product being cut during the return to the starting position and determining that the semi-finished product itself is misaligned relative to its ideal application position on the building drum.

[0047] Preferably, during the translation of the cutting member, the cutting edge of the cutting member transmits the thrust component directed towards the abutment plate to the semi-finished product.

[0048] Preferably, it is also provided that vibration is transmitted to the cutting member while transversely cutting the semi-finished product.

[0049] Preferably, the vibration has an ultrasonic frequency.

[0050] In particular, high-frequency vibrations, such as ultrasonic vibrations, improve the effectiveness of cutting in order to allow for effective cutting of semi-finished products with small thickness and limited consistency, thereby limiting the stress caused by the semi-finished products themselves and the resulting deformation.

[0051] Preferably, the translation of the cutting member occurs when the cutting member is not in direct contact with the abutment plate.

[0052] Due to the absence of direct contact, the vibration effect transmitted to the cutting member is optimized, thereby improving the efficiency of the cutting member.

[0053] Preferably, during the translation of the cutting member, the abutment surface of the abutment plate and the cutting edge of the cutting member are separated by a measured value of no more than 0.1 mm.

[0054] Therefore, during the cutting process, it helps to form an effective contrast with the thrust force transmitted to the semi-finished product, thereby preventing uncontrolled deformation of the semi-finished product itself.

[0055] Preferably, the cutting plane intersects the advancing plane in an inclined orientation that defines a first acute angle with respect to the advancing plane, and the vertex of the first acute angle points towards the building drum.

[0056] Preferably, the cutting plane intersects the advancing plane in an orientation perpendicular to the longitudinal extension of the semi-finished product.

[0057] Preferably, during the cutting operation, an action is applied to block the semi-finished product with respect to the advancing plane.

[0058] Therefore, due to the stress transmitted during the cutting process, the unwanted movement and / or lateral misalignment of the semi-finished product are prevented.

[0059] Preferably, with reference to the advancement of the semi-finished product, the blocking action is performed upstream of the cutting plane.

[0060] Preferably, with reference to the advancement of the semi-finished product, the blocking action is performed downstream of the cutting plane.

[0061] Preferably, the blocking action is performed on the abutment plate.

[0062] The subsequent proximity between the area where the blocking action is applied and the cutting plane reduces the possibility of deformation of the semi-finished product caused by the cutting member.

[0063] Preferably, the blocking action is performed by at least one thrust plate that acts elastically on the semi-finished product.

[0064] Preferably, the laying of the tread strip includes arranging the semi-finished tread strip in the form of a continuous strip.

[0065] Preferably, the laying of the tread band includes subjecting the tread band semifinished product to the sizing cut treatment.

[0066] Preferably, the thickness of the tread band semifinished product is included between 1 mm and 8 mm.

[0067] Preferably, the width of the tread band semifinished product is included between 20 mm and 120 mm.

[0068] Preferably, the component further includes an elastomeric substrate circumferentially arranged around the laying surface before laying the tread band.

[0069] Preferably, the elastomeric substrate is applied in an axially centered position relative to the bead core.

[0070] Preferably, the laying of the elastomeric substrate occurs after the end flaps are turned up.

[0071] Preferably, the laying of the elastomeric substrate includes arranging the elastomeric substrate semifinished product in the form of a continuous strip;

[0072] Preferably, the laying of the elastomeric substrate includes subjecting the elastomeric substrate semifinished product to the sizing cut treatment.

[0073] Preferably, the thickness of the elastomeric substrate semifinished product is included between 0.5 mm and 1.5 mm.

[0074] Preferably, the width of the elastomeric substrate semifinished product is included between 15 mm and 30 mm.

[0075] Preferably, the cutting member is movable along the cutting line from a starting position to an arrival position.

[0076] Preferably, the abutment plate is configured to be positioned in the working position, after which the cutting member moves to the arrival position to cut the semifinished product.

[0077] Preferably, the abutment plate is configured to be positioned in the stationary position, after which the cutting member returns to the starting position.

[0078] Preferably, the preparation unit further includes an ultrasonic transducer that operates on the cutting member to transmit ultrasonic frequency vibrations to the cutting member.

[0079] Preferably, the cutting member includes a blade movable along the cutting direction.

[0080] Preferably, the blade has an inclined orientation that defines a first acute angle relative to the advancement plane, the apex of the first acute angle facing the preparation section.

[0081] Preferably, the first acute angle has a value included between 15° and 30°.

[0082] Preferably, the cutting edge of the cutting member is located in the cutting plane in an inclined orientation relative to the cutting line.

[0083] Preferably, the cutting edge is in the cutting plane and forms a second acute angle relative to the advancing plane, the vertex of the second acute angle pointing towards the starting position.

[0084] Preferably, the second acute angle has a value included between 5° and 15°.

[0085] Preferably, parallel to the advancing plane, the cutting edge forms a third acute angle, the vertex of the third acute angle pointing towards the starting position.

[0086] Preferably, the third acute angle has a value included between 5° and 25°.

[0087] Preferably, the cutting member has a cutting vertex pointing towards the abutment plate and is configured to operate through the semi-finished product without directly abutting against the abutment plate itself.

[0088] Preferably, the cutting vertex is configured to operate through the semi-finished product in the case where the lower surface of the semi-finished product abuts against the abutting surface of the abutment plate.

[0089] Preferably, the distance between the abutting surface of the abutment plate and the cutting vertex is spaced apart by a measured value not greater than 0.1 mm.

[0090] Preferably, a blocking device is further provided, which operates near the abutment plate to block the semi-finished product relative to the advancing plane.

[0091] Preferably, the blocking device is configured to operate on the semi-finished product upstream of the cutting plane with reference to the advancement of the semi-finished product.

[0092] Preferably, the blocking device is configured to operate on the semi-finished product downstream of the cutting plane with reference to the advancement of the semi-finished product.

[0093] Preferably, the blocking device is configured to push the semi-finished product against the abutment plate.

[0094] Preferably, the blocking device includes at least one thrust plate, which is configured to act on the semi-finished product elastically through the end edge.

[0095] Preferably, the thrust plate is manufactured in the form of an elastically deformable plate.

[0096] Preferably, the thrust plate has a plurality of elastically deformable sheets that are respectively parallel and distributed along the end edge.

[0097] Subdividing the active edge into deformable sheets allows for a more uniform action on the semi-finished product, while enabling the thrust plate to adapt to the cross-sectional profile of the semi-finished product itself.

[0098] Preferably, the cutting member is movable along a guide having a transverse orientation with respect to the longitudinal extension of the conveyor belt.

[0099] Preferably, the cutting member is movable along a guide having a vertical orientation with respect to the longitudinal extension of the conveyor belt.

[0100] Preferably, the preparation section of the belt feeder is configured to advance at the same speed as the feeding section during the transfer of the semi-finished product from the feeding section to the preparation section. Description of the Drawings

[0101] Further features and advantages will become more apparent from a detailed description of the preferred but non-exclusive embodiments of the process and related equipment for constructing a tire for a bicycle according to the present invention. This description will be elaborated with reference to the accompanying drawings, which are provided for illustrative purposes only and in which:

[0102] - Figures 1 to 4 Schematically shows in a radial cross-sectional view several operating steps for constructing a green tire for a bicycle;

[0103] - Figure 5 Schematically shows in a side view an apparatus for constructing a tire for a bicycle according to the present invention:

[0104] - Figure 6 Shows a schematic top view of one of the preparation units forming part of the apparatus, according to a first embodiment that can be used, for example, for manufacturing a carcass ply;

[0105] - Figure 7 Shows Figure 3 details of the preparation unit, in which details of the cutting group and the lifting device are shown in a side view;

[0106] - Figure 8 Shows details of the preparation unit in the transition area between the feeding section and the preparation section of the conveyor belt, and shows the cutting group and the lifting device in the raised position in a front view;

[0107] - Figure 9 Shows Figure 8 details of, in which the lifting device is in the lowered position;

[0108] - Figure 10 Shows details of another preparation unit according to a variant of the embodiment, in which details of the cutting group and the lifting device are shown in a side view;

[0109] -Figure 11 shows Figure 10 details of the preparation unit located in the transition area between the feed section and the preparation section of the conveyor belt, and shows the cutting group and the lifting device in a front view;

[0110] - Figure 12 shows a schematic top view of another preparation unit of a semi-finished product that forms part of this equipment according to another embodiment that is particularly suitable for, for example, manufacturing a tread strip;

[0111] - Figure 13 shows in a side view Figure 12 the preparation unit located in the transition area between the feed section and the preparation section of the conveyor belt;

[0112] - Figure 14 shows Figure 12 and Figure 13 details of the preparation unit, which shows the cutting group and the lifting device in a front view;

[0113] - Figure 15 shows Figure 12 and Figure 14 details of the preparation unit, which shows the cutting group and the lifting device in a front view;

[0114] - Figure 16 shows a structural scheme of a hypothetical tire for a bicycle in a radial cross-sectional view. Detailed implementation

[0115] In Figure 5 , the reference numeral 1 as a whole represents a device for constructing a tire for a bicycle, and the device is adapted to initiate a construction process according to the present invention.

[0116] The present invention aims to process Figure 16 a tire 2 for a bicycle of the type schematically illustrated in , for example, tires used on road bicycles, track bicycles, mountain bicycles, electric bicycles, etc.

[0117] In the tire 2, the following information can be identified: a radially inner surface 2a that generally faces the geometric rotation axis "X" of the tire 2; and a radially outer surface 2b that generally faces away from the geometric rotation axis "X".

[0118] The tire 2 for a bicycle has a carcass structure 3 that includes at least one carcass ply 4 having cords bonded in an elastomeric matrix and parallel to each other.

[0119] Axially opposite end flaps 4a of one or more carcass plies 4 are joined to respective bead cores 5, i.e., to the annular anchoring structures integrated in the region generally identified by the name "bead", where, in the use state, there is a mechanical engagement between the tire 2 and the respective mounting rim.

[0120] The tread band 6 made of elastomeric material is applied in a radially outer position with respect to the carcass structure 3.

[0121] Preferably, in the carcass structure 3, at least two cord plies are applied with crosswise orientations respectively. The cords belonging to each ply have extensions inclined at a predetermined angle, the predetermined angle being close to being comprised between about 35° and about 55° with respect to the circumferential extension direction of the tire 2. It may be provided that two carcass plies 4 overlap radially with respect to each other, each said carcass ply having respective cords extending along a direction inclined with respect to the circumferential extension of the tire 2 and with an orientation inclined with respect to the cords belonging to the other carcass ply 4. Alternatively, as shown in the example shown, it may be provided that the end flaps 4a of a single carcass ply 4 turned up around the bead core 5 extend at least to the axial midplane M of the tire 2, such that each end flap defines another radially outer ply of cords, which has a crosswise orientation with respect to the cords present in the radially inner layer.

[0122] However, in the tire 2 for a bicycle, it may be provided that at least one belt 7 extends between the tread band 6 and the carcass structure 3, or extends circumferentially between two carcass plies overlapping each other in the radial direction. If a belt 7 is provided, the at least one belt (which serves, for example, to protect the tire 2 from being punctured) may have a fabric structure incorporating cords that are respectively parallel or respectively crosswise, and the thickness of the cords is preferably not greater than about 0.6 mm, preferably being comprised between 0.3 mm and 0.6 mm. In a feasible embodiment, the axial extension of one or more belts is less than the axial extension of the tread band 6 and is preferably comprised between 15 mm and 50 mm. In a feasible embodiment variant, it may be provided that the axial extension of the enlarged belt 8, generally referred to as "bead-to-bead", is instead greater than the axial extension of the tread band 6 and is, for example, comprised between 50 mm and 200 mm, preferably axially terminating at each of the bead cores 5. In another feasible embodiment (not shown), it may be provided that the width of the first belt 7 is less than the width of the tread band, and the enlarged belt 8 extends from one bead core 5 to the other bead core 5.

[0123] Between one or more carcass plies 3 and the tread band 6, an elastomeric substrate 9 may also be interposed in the form of a layer, preferably axially centered relative to the bead core and radially internal relative to an optional protective band 7 that may be present. The elastomeric substrate may have an axial width approximately comprised between 15 mm and 30 mm and a thickness comprised between 0.5 mm and 1.5 mm.

[0124] The radially inner surface of the carcass structure 3 may be coated with a so-called liner 10, which consists of a layer of air-impermeable composite, the thickness of which may be approximately comprised between 0.35 mm and 1 mm. The liner 10 extends axially from one bead to the other bead according to an axial extension approximately comprised between 70 mm and 120 mm.

[0125] Proximal to the bead core 5 and outside the bead, a respective reinforcing bead 11, commonly referred to as a "bead filler", may also be applied, in the form of a strip of fabric incorporating cords that are parallel to each other or cross each other, for the purpose of protecting the bead from contact with the rim of the wheel on which the tire is mounted. The width of each reinforcing bead 11 may be comprised between 8 mm and 15 mm and the thickness may be comprised between 0.3 mm and 1 mm.

[0126] Preferably, on the radially outer surface 2b of the tire 2 for a bicycle, portions of the carcass plies 4 may be identified between the axial outer edge of the tread band 6 and the bead core 5, and these portions of the carcass plies 4 are directly exposed to the external environment. In fact, the tire 2 for a bicycle usually lacks sidewalls (i.e., layers of elastomeric material laterally applied outside the carcass structure 3, extending between one bead and the corresponding axial outer edge of the tread band 6). However, it may also be provided that the so-called "sidewall reinforcements" 12 each comprise a strip of rubber-coated fabric material incorporating cords that are parallel or cross each other, wherein the thickness thereof is approximately comprised between 0.3 mm and 0.8 mm and all extend between the respective bead and the tread band according to a width comprised between 30 mm and 60 mm.

[0127] The apparatus 1 includes a substantially cylindrical building drum 13, which is rotatably supported about its horizontal axis of rotation X-X. In Figure 5 this, a laying group, generally designated 14, serves to circumferentially lay a plurality of components of the tire 2 around a laying surface 15 present outside the building drum 13.

[0128] The type, quantity, and / or structural and dimensional characteristics of components, including one or more carcass plies 4, bead cores 5, tread bands 6, and possibly liners 10, sidewall reinforcements 12, elastomeric bases 9, reinforced beads 11, protection bands 7, 8, etc., are selected according to the type of tire for bicycles (road bicycles, track bicycles, mountain bicycles, etc.) to be produced.

[0129] More particularly, as Figures 1 to 4 shown, the construction of a tire 2 for a bicycle provides that one or more carcass plies 4 are laid by liner / carcass ply application devices 16, 17 in a cylindrical configuration, which assist in the winding of one or more carcass plies 4 around a laying surface 15 existing on the outside of a building drum 13. A possible liner 10 (shown only in dashed lines in Figure 16 for simplicity of illustration) can be laid on the laying surface 15 by the liner / carcass ply application devices 16, 17 before applying one or more carcass plies 4.

[0130] A pair of bead cores 5 are applied by a bead core application device (not shown in the figure) at a predetermined mutual axial distance D. The bead cores are made, for example, of a composite material based on natural or synthetic fibers and / or of a metallic material, and each bead core is laid around one of the axially opposite end flaps 4a of the carcass ply 4.

[0131] It can be provided that each bead core 5 (previously made in the form of a finished component) is first assembled around one or more carcass 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 rods forming part of the bead core application device) determines the application of the bead core 5 against one or more carcass plies 4, with each bead core located at the corresponding circumferential recess 18.

[0132] Alternatively, the bead core application device can be configured to place each bead core 5 directly on the building drum 13 and wind one or more continuous cords 4 around one or more carcass plies 4 in the form of multiple coils that are axially close to each other and / or radially overlap each other.

[0133] Thus, a turning-up device 13a operating at the building drum 13 (schematically shown in Figure 3 ) provides for turning up the end flaps 4a of the carcass ply 4 around the corresponding bead cores 5. During the turning-up process, the end flaps 4a can at least partially overlap each other and are optionally joined in a directly contacting manner.

[0134] 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 cores 5. The tread band 6 can be applied in a radially overlapping manner relative to the turned-up end flap 4a. After the application is completed, the end flap 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 (axially extending through the axially median plane M equidistant from the bead cores 5) abuts against the building drum 13 ( Figure 16 ).) and / or the laying surface 15.

[0135] Preferably, the tread band 6 is applied while keeping the mutual axial distance D between the bead cores 5 substantially constant. More particularly, during the entire building process (including the application of the tread band 6), the mutual axial distance D between the bead cores 5 is preferably kept constant.

[0136] If necessary, before applying the tread band 6, the at least one protective band 7, the sidewall reinforcement 12, and the elastomeric matrix 9 located axially centered relative to the bead cores 5 can be applied first. The elastomeric substrate 9 is preferably applied before turning up the end flap, and the application of the protective band 7 and / or the extended protective band 8 can be carried out before or after the turning up as required. The possible bead reinforcements 11 can be applied simultaneously near each bead in the bead during or after the application of the tread band 6.

[0137] After the building is completed, the green tire 2 is removed from the building drum 13 to undergo other processing steps, for example, to be transferred to a vulcanization press. For this purpose, the building drum 13 can be radially contracted to facilitate the axial removal of the built tire 2. Conveniently, it is stipulated that before laying at least one of the above tire components, the corresponding semi-finished products 20a, 20b, 20c, 20d in the form of continuous strips are processed by size cutting along the cutting line L to separate workpieces 21 having a predetermined cutting length from the semi-finished products themselves. Subsequently, the workpieces 21 are brought to the building drum 13 for application around the laying surface 15.

[0138] For this purpose, the laying group 14 includes at least one preparation unit 22a, 22b, 22c, 22d, which is configured to laterally cut along the cutting line L to set the dimensions of the semi-finished products 20a, 20b, 20c, 20d to separate workpieces 21 having a predetermined cutting length from the semi-finished products themselves. More particularly, it is preferably stipulated that more than one of the preparation units 22a, 22b, 22c, 22d are each dedicated to preparing the corresponding tire components. More specifically, in Figure 2In the embodiment, in addition to, for example, the first preparation unit 22a dedicated to preparing the liner 10, the second preparation unit 22b and the third preparation unit 22c are also recognizable, for example, dedicated to preparing the carcass ply 4 and the tread band 6 respectively. The fourth preparation unit 22d may be dedicated to preparing the sidewall reinforcement 12 or the bead reinforcement 11. The preparation units 22a, 22b, 22c, 22d may have a substantially horizontal and / or inclined longitudinal extension, and may be successively overlapped one by one so as to converge towards the building drum 13 from the same side.

[0139] Each of the preparation units 22a, 22b, 22c, 22d has a feeding unit Ha, Hb, He, Hd in which respective 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 in a container or are suitably stored in a container, and these semi-finished products are gradually drawn out of the container during processing.

[0140] Each semi-finished product 20a, 20b, 20c, 20d has structural and geometric characteristics suitable for obtaining the corresponding component to be manufactured and applied on the building drum 13. For example, in the first preparation unit 22a, a liner semi-finished product 20a made of an airtight elastomeric material may be arranged, the thickness of which is approximately between 0.35 mm and 1 mm and the width is between 70 mm and 120 mm. In the second preparation unit 22b, a second semi-finished product, for example, a carcass ply semi-finished product 20b, may be arranged, the thickness of which is approximately between 0.3 mm and 0.6 mm and the width is between 110 mm and 450 mm, and which incorporates reinforcing cords parallel to each other, the reinforcing cords being inclined at an angle between 35° and 55° with respect to the longitudinal extension of the semi-finished product itself. In the third preparation unit 22c, a third semi-finished product, for example, a tread band semi-finished product 20c made of an elastomeric material, may be arranged, the thickness of which is approximately between 1 mm and 8 mm and the width is between 20 mm and 120 mm.

[0141] For the sake of description, below, the structural and functional characteristics of the preparation units 22a, 22b, 22c, 22d relative to each other will be described only once mainly with reference to the second preparation unit 22b, but it is intended that these structural and functional characteristics can be generally applied to each of the preparation units themselves.

[0142] In Figure 6 each of the preparation units 22a, 22b, 22c, 22d includes a conveyor belt 23 having a feeding section 24 and a preparation section 25, the feeding section and the preparation section being continuously aligned to define a substantially horizontal advancing plane P.

[0143] Preferably, the feeding section 24 includes a strip-shaped feeding belt 26 which engages around a corresponding first driving roller 27. The preparation section 25 further includes a corresponding strip-shaped preparation belt 28 which engages around a second driving roller 29. The corresponding upper sections of the feeding belt 26 and the preparation belt 28 are coplanar and aligned with each other to define the aforementioned advancing plane P.

[0144] Preferably, the feeding section 24 and the preparation section 25 are each independently driven from each other at at least one of the corresponding first driving roller 27 and the second driving roller 29, so as to be able to translate the corresponding feeding belt 26 and the preparation belt 28 at the same or different speeds according to requirements. The conveyor belt 23 is adapted to support the semi-finished products 20a, 20b, 20c, 20d from the corresponding feeding units Ha, Hb, He, Hd, and the lower surface S1 of the semi-finished product abuts against the advancing plane P, the preparation belt 28 and / or the feeding belt 26.

[0145] The cutting group 30 is adapted to transversely cut the semi-finished products 20a, 20b, 20c, 20d to separate the workpieces 21 having a predetermined length from the semi-finished products themselves. The cutting group 30 operates along the above-mentioned cutting line L, which is defined by the intersection line of the semi-finished products 20a, 20b, 20c, 20d and the cutting plane Q, and the cutting plane Q is transverse to the advancing plane P and completely intersects the semi-finished products themselves near the transition region N located between the feeding section 24 and the preparation section 25. Performing the sizing cutting process ensures that at the start of each operating cycle, the semi-finished products 20a, 20b, 20c, 20d position their own head ends A at the cutting line L. Performing a new cutting process stipulates that when the feeding section 24 and the preparation section 25 are started simultaneously, the semi-finished products 20a, 20b, 20c, 20d are longitudinally advanced along the advancing plane P and gradually transferred from the feeding section 24 to the preparation section 25. Preferably, it is stipulated that during the transfer of the semi-finished products 20a, 20b, 20c, 20d from the feeding section 24 to the preparation section 25, the feeding section 24 and the preparation section 25 are advanced at the same speed so that the semi-finished products themselves do not bear undesired stresses. Since the semi-finished products 20a, 20b, 20c, 20d are usually made of a green elastomeric material with a limited thickness, in fact, the semi-finished products are quite sensitive to the tensile stress or compressive force generated by the speed difference between the feeding section 24 and the preparation section 25, and the tensile stress or compressive force may change the length and / or width of the semi-finished products themselves. Alternatively, the advancing speed of the preparation section 25 and the feeding section 24 may be differentiated in a controlled manner. For example, it may be stipulated that the translation speed of the preparation section 25 is slightly higher than the translation speed of the feeding section 24 to help the semi-finished products 20a, 20b, 20c, 20d or parts thereof to relax along the advancing plane P.

[0146] A photoelectric cell, encoder, or other suitable control device 31 operating on the conveyor belt 23 (shown only schematically since they can be implemented in any convenient manner) allows controlling the simultaneous start of the feed section 24 and the preparation section 25 so that when the leading ends A of the semi-finished products 20a, 20b, 20c, 20d have exceeded the cutting plane Q and reached a predetermined cutting distance K relative to the cutting plane itself, the advancement of the semi-finished products 20a, 20b, 20c, 20d is stopped, as Figure 6 shown.

[0147] The cutting distance K is related to the circumferential extension of the laying surface 15, for example such that the length of the obtained workpiece 21 is consistent with this circumferential extension. Alternatively, it can be provided that the cutting distance K and the length of the obtained workpiece 21 are different from the circumferential extension of the laying surface 15, for example slightly larger than the circumferential extension of the laying surface 15, to compensate for the possible elastic shrinkage of the material after the cutting is performed and before it is applied to the building drum 13.

[0148] Near the transition zone N between the feed section 24 and the preparation section 25, the lifting device 32 is also operating, by means of which the semi-finished products 20a, 20b, 20c, 20d are made suitable to be spaced apart from the advancement plane P. When the advancement of the semi-finished products 20a, 20b, 20c, 20d has stopped, the lifting device 32 engages with the semi-finished products themselves at the cutting section T intersecting the cutting plane Q and slightly lifts them from the advancement plane P to facilitate the subsequent cutting by the cutting group 30. Then, the cutting group 30 is started to laterally translate to the semi-finished products 20a, 20b, 20c, 20d and cut the semi-finished products along the cutting line L to determine the separation of the workpieces 21, which have a desired length corresponding to the cutting distance K defined between their leading end A1 and their trailing end B, where the leading end A1 previously belonged to the semi-finished products 20a, 20b, 20c, 20d, and the trailing end B is obtained together with the new leading end A of the cut semi-finished products 20a, 20b, 20c, 20d by the cutting operation.

[0149] After the cutting is completed, the preparation section 25 is started to advance the workpiece 21 along the conveyor belt 23 until the leading end A1 carried by the workpiece 21 reaches the end of the conveyor belt 23 opposite to the feed units Ha, Hb, He, Hd and approaches the building drum 13.

[0150] By means of possible translations of the application devices 16, 17, 19 and / or the preparation section 25, the head end A1 of the workpiece 21 is positioned on the laying surface 15 of the building drum 13 and is held on said laying surface, for example, by the action of suction nozzles arranged on the laying surface 15 itself or via adhesion to the laying surface or to components previously laid on the building drum 13. Then, the building drum 13 is actuated to rotate by the motor 33 or other suitable actuating means (not shown), while the conveyor belt 23 translates the workpiece 21 through the preparation section 25 at a feed rate related to the circumferential speed of the laying surface 15 to circumferentially lay the workpiece 21 around the laying surface 15.

[0151] Measuring devices can be arranged on the conveyor belt 23, and these measuring devices are optionally fully or partially integrated in the above-mentioned control device 31, which is configured to detect the length of the workpiece 21 on the preparation section 25 immediately before the workpiece 21 is applied to the building drum 13. The measuring devices can be combined with a comparator 34, which is configured to compare the detected length of the workpiece 21 with the circumferential extension of the laying surface 15. The comparator 34 is operatively connected to the aforementioned control device 31 for controlling the conveyor belt 23 and to the motor 33 and / or other devices provided for actuating the rotation of the building drum 13 to adjust the translational speed of the conveyor itself relative to the peripheral speed of the laying surface 15. For example, if the length of the workpiece 21 detected by the measuring devices is slightly different from the circumferential extension of the laying surface 15, the translational speed of the conveyor belt 23 can be conveniently adjusted relative to the rotational speed of the building drum 13 to modify the length of the workpiece 21 and make it consistent with the circumferential extension of the laying surface 15.

[0152] When the building drum 13 has completed a full rotation about its axis of rotation X-X, the tail end B of the workpiece 21 is joined to the head end A1 previously applied to the laying surface 15, thus completing the laying of the tyre component.

[0153] The structural specifications of the preparation units 22a, 22b, 22c, 22d (especially with reference to the specifications of the lifting device 32 and the cutting group 30) can vary according to the type of component to be obtained.

[0154] In Figures 6 to 9 a possible embodiment is shown, which is applied to the second preparation unit 22b configured for manufacturing one or more carcass plies 4. For the sake of simplicity of description and to maintain coherence, this embodiment will be described herein with reference to the treatment of the carcass ply semi-finished product 20b. However, as an additional option or alternative to what is described herein, the same embodiment can also optionally be used, for example, for the first preparation unit 22a for manufacturing the liner 10 by treating the liner semi-finished product 20a, and / or for manufacturing other components by treating the corresponding semi-finished products 20a, 20b, 20c, 20d.

[0155] As can be seen in Figure 6 , the lifting device 32 and the cutting group 30 are mounted on a support structure 36 that extends transversely above the conveyor belt 23. The support structure 36 (e.g., suspended from above at hinge pin 35) can be angularly positioned about a vertically oriented axis Y-Y. The orientation of the support structure 36 depends on the orientation of the cutting plane Q, which is appropriately inclined with respect to the longitudinal extension of the carcass ply semi-finished product 20b for the purpose of processing the carcass ply 4. Thus, it is possible to modify the angle of the cutting plane Q and the cutting line L according to the orientation of the cords incorporated in the semi-finished product itself, preferably by an angle included between 35° and 55° with respect to the longitudinal extension of the carcass ply semi-finished product 20b.

[0156] The lifting device 32 includes a plurality of suction cups 37 or another type of clamping element that face the advancing plane P and are distributed along two side-by-side clamping lines located on opposite sides of the cutting plane Q, the two clamping lines being located upstream and downstream, respectively, with respect to the advancing direction of the carcass ply semi-finished product 20b. A pneumatic activation / deactivation circuit is led to the suction cups 37.

[0157] By means of one or more fluid power cylinders 38 ( Figure 7 ), the suction cups 37 can be vertically moved between a lowered position and a raised position relative to the support structure 36 towards and away from the advancing plane P. In the lowered position, the suction cups 37 act 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 advancing plane P, as Figure 9 shown. The suction cups 37 hold the carcass ply semi-finished product 20b by applying an attractive force at the upper surface S2 under the suction force generated by a pneumatic activation / deactivation circuit (not shown). Then, the suction cups 37 lift the carcass ply semi-finished product 20b from the advancing plane P at the cutting section T by translating to the raised position, as Figure 8 shown.

[0158] In order to obtain higher precision during the cutting operation, the suction cups 37 arranged on each of the clamping lines are spaced from each other by a measurement of no more than 20 mm, and the stroke they complete between the lowered position and the raised position is no more than 20 mm. The measured value of the lift is sufficient to allow the cutting group 30 to penetrate the carcass ply semi-finished product 20b (or other semi-finished product) without disturbing the underlying mechanical components of the conveyor belt 23. The lifting action also creates a slight tension in the cutting section T of the carcass ply semi-finished product 20b, which helps to separate the workpiece 21 along the cutting line L.

[0159] In Figures 6 to 9In the example of, the cutting group 30 preferably includes a tool-like cutting member 39, which is arranged to be coplanar with the cutting plane Q. The tool 39 is fixed to a slide 40, which is movable along a guide 41 integral with the support structure 36 and parallel to the cutting plane Q.

[0160] When 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 to rotate) causes the slide 40 and the tool 39 carried thereby to move along the cutting line L from the starting position to the arrival position, thereby determining the separation of the workpiece 21 from the carcass ply semi-finished product 20b, the workpiece and the carcass ply semi-finished product being located downstream or upstream of the cutting plane Q, respectively.

[0161] An ultrasonic transducer 43 can be conveniently operated on the cutting group 30 to transmit ultrasonic frequency vibrations to the cutting group that contribute to performing the cutting. As Figure 7 more clearly visible in, the tool 39 of the cutting group 30 preferably has a cutting edge 39a extending in a direction inclined with respect to the advancing plane P, so as to form an acute angle β with respect to the advancing plane itself, the vertex of which points towards the arrival position, that is, in the translational direction of the cutting group 30 towards the arrival position. This situation ensures that during the execution of the cutting, the cutting edge 39a transfers the vertical thrust component directed away from the advancing plane P to the carcass ply semi-finished product 20b to contribute to the holding action of the suction cup 37. In addition, the end edges of the carcass ply semi-finished product 20b and the workpiece 21 being cut along the cutting line L will tend to be guided upwards to limit the risk of an unwanted jamming occurring during subsequent movement on the advancing plane P.

[0162] It is also preferably provided that during the execution of the cutting of the carcass ply semi-finished product 20b, the cutting group 30 translates towards the building drum 13. This expedient ensures that when the cutting edge 39a of the tool 39 encounters the edge of the carcass ply semi-finished product 20b, the possible stresses or other deformations applied to the material tend to concentrate on the end vertex of the trailing end B of the cut workpiece 21, rather than on the end vertex of the leading end upstream of the cutting line L.

[0163] After the execution of the cutting, the new leading end A formed on the freshly cut carcass ply semi-finished product 20b engages with the suction cup 37 arranged along the clamping line located upstream of the cutting plane Q. The trailing end B of the obtained workpiece 21, in turn, remains held fixed by the suction cup 37 arranged along the clamping line located downstream of the cutting plane Q. After the cutting group 30 reaches the arrival position, the suction cups 37 located upstream and downstream of the cutting plane Q, respectively, can return to the lowered position simultaneously or at different times to reposition the leading end A of the cut carcass ply semi-finished product 20b and the trailing end B of the cut workpiece 21 against the advancing plane P, respectively.

[0164] After the repositioning is completed, the cutting group 30 can return to the starting position without disturbing the head end A of the carcass ply semi-finished product 20b being cut and / or the tail end B of the workpiece 21.

[0165] The cutting plane Q can be advantageously positioned 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, such that the cutting group 30 operates adjacent to the transition zone itself above the feed section 24. Thus, as the suction cup 37 descends towards the lowered position, the tail end B of the cut workpiece 21 is deposited on the end portion of the feed section 24 and thus reaches the transition zone N. When the repositioning is completed, the start of the preparation belt 28 determines the transfer of the tail end B onto the preparation section 25 while the entire workpiece 21 is advanced towards the building drum 13. During the transfer of the tail end B to the preparation section 25, the feed belt 26 can be temporarily kept inactive to assist in moving the workpiece 21 away from the carcass ply semi-finished product 20b.

[0166] Alternatively, it can be provided that the feed belt 26 and the preparation belt 28 are started simultaneously in order to also determine the advancement of the carcass ply semi-finished product 20b on the feed section 24 so that it crosses the transition zone N and continues to travel along the advancement plane P at the preparation section 25. In this case, it is preferred that during the transfer of the tail end B, the translational speed of the workpiece 21 on the preparation section 25 is greater than the advancement speed of the carcass ply semi-finished product 20b on the feed section 24 in order to drive the tail end B onto the preparation section 25, thereby helping to release any possible stresses and / or other deformations generated during the cutting operation and thus facilitating the removal of the workpiece from the head end of the just-cut carcass ply semi-finished product 20b.

[0167] After the tail end B of the workpiece 21 has been transferred onto 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 equal to each other such that the carcass ply semi-finished product 20b can continue to advance uniformly through the transition zone N without subjecting the semi-finished product to undesired tensile stresses. It should be noted that what has been described above with respect to the treatment of the carcass ply semi-finished product 20b also applies to any other type of semi-finished product 20a, 20b, 20c, 20d being processed.

[0168] At Figure 10 and Figure 11In it, a possible embodiment variant is shown, which is applied to the fourth preparation unit 22d configured for manufacturing the sidewall insert 12. This embodiment variant is actually also particularly suitable for operating on semi-finished products incorporating crosswise reinforcing cords, such as those typically suitable for manufacturing sidewall reinforcements 12, reinforcing beads 11, and / or belts 7, 8. Therefore, for the sake of simplicity of description and maintaining coherence, the embodiment variant will be described herein only with reference to the processing of the sidewall insert semi-finished product 20d. Figures 7 to 9 As an additional solution or alternative to what is described herein, the same embodiment can optionally be used, for example, on the first preparation unit 22a and the second preparation unit 22b for manufacturing the carcass ply 4 by processing the carcass ply semi-finished product 20b, and / or for manufacturing other components.

[0169] This embodiment variant is conceptually similar to the above-described embodiment, but is different due to the structural and functional characteristics of the cutting group 30 and the lifting device 32. Unspecified structural components and details can be manufactured in a manner conceptually similar to that described in the embodiment with reference to Figures 7 to 9 above.

[0170] In this case, instead of using the above-described suction cup 37, the lifting device 32 includes a lifting insert 44, which is arranged on the advancing plane P and flush with the advancing plane P so that the sidewall insert semi-finished product 20d passing above the lifting insert can cross over the lifting insert. The lifting insert 44 is generally rod-shaped, and the rod has a longitudinal extension parallel to the cutting plane Q. The width of the lifting insert 44 is defined between the inlet edge 45 pointing to the sidewall insert feeding unit Hd (i.e., in the direction opposite to the advancing direction of the sidewall insert semi-finished product 20d along the advancing plane P) and the outlet edge 46 pointing to the building drum 13 (i.e., along the advancing direction of the sidewall insert semi-finished product 20d). A sliding surface 47 extends above between the inlet edge 45 and the outlet edge 46, and the sliding surface has an inclined orientation relative to the advancing plane P in a direction diverging from the advancing plane P towards the building drum 13 (i.e., along the advancing direction of the sidewall insert semi-finished product 20d).

[0171] The sliding surface 47 is suitable for supporting the sidewall insert semi-finished product 20d, which enables the lower surface S1 of the sidewall insert semi-finished product 20d to slide against the lifting insert 44 itself during the translation of the sidewall insert semi-finished product 20d along the advancing plane P. The divergent orientation of the sliding surface 47 ensures that a recess 48 is formed between the lower surface S1 of the sidewall insert semi-finished product 20d and the advancing plane P along the outlet edge 46.

[0172] Instead of the cutting tool 39, the cutting member includes a rotary blade 49 which is disc-shaped and is actuated to rotate at high speed about its geometric axis Z-Z, which is parallel to the advancing plane P and orthogonal to the cutting plane Q. The rotary blade 49 is located within the cutting plane Q and is operatively carried by a respective slide 40 which is movable along a guide 41. During the execution of the cutting, the rotary blade 49 rotates about its geometric axis Z-Z and translates along the guide 41 from a starting position to an arrival position, while its peripheral edge 49a traverses the sidewall insert semi-finished product 20d and translates within a recess 48 laterally delimited by the exit edge of the lifting insert 44.

[0173] Preferably, the direction of rotation of the rotary blade 49 is selected in such a way that at the intersection of its cutting edge 39a with the sidewall insert semi-finished product 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 conveniently tends to move away from the advancing plane P the edges of the head end A of the sidewall insert semi-finished product 20d just cut and the edges of the tail end B of the resulting workpiece 21.

[0174] Figures 12 to 15 Another possible embodiment is shown, which is applied to a third preparation unit 22 configured for manufacturing a tread strip 6. Also in this case, for the sake of simplicity of description and to maintain coherence, this variant of the other embodiment will be described herein with reference to the treatment of the tread strip semi-finished product 20c. However, as an additional solution or alternative to what is described herein, the same embodiment can optionally be used, for example, on a first preparation unit 22a for manufacturing a lining 10 by treating a lining semi-finished product 20a, an elastomeric substrate 9, and / or for manufacturing other components by treating the respective semi-finished products 20a, 20b, 20c, 20d.

[0175] This variant of the other embodiment is also conceptually similar to the above-described embodiment, and the main differences lie in the structural and functional characteristics of the cutting group 30 and the lifting device 32. The unspecified structural components and details can be manufactured in a way that is conceptually similar to the embodiment described above with reference to Figures 7 to 9 the embodiment.

[0176] In Figures 12 to 15 this case, the lifting device 32 includes a contact plate 50 which is disposed within a transition zone N between the feed section 24 and the preparation section 25 of the conveyor belt 23 in the cutting plane Q. In fact, the cutting plane Q intersects the advancing plane P at the contact plate 50.

[0177] The contact plate 50 is movable between a rest position and a working position, in which rest position the contact plate is substantially coplanar with the advancing plane P (as Figure 13 shown), and in which working position the contact plate is lifted relative to the advancing plane P (asFigure 14 as shown).

[0178] When the conveyor belt 23 is activated to advance the green tire tread 20c towards the building drum 13, the green tire tread itself slides over the abutment plate 50 in the rest position. After the green tire tread 20c has stopped advancing, the abutment plate 50 is brought to the working position while obtaining the required cutting distance K between the head end A of the green tire tread itself and the cutting plane Q. Thus, the green tire tread 20c is lifted relative to the advancing plane P at the cutting section T where it is crossed by the cutting plane Q.

[0179] The cutting members of the cutting group 30 are in the form of blades 51, which are rigidly carried by respective sliders 40 that are movable along guides 41, which in turn are integral with a support structure 36 that extends 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 to the longitudinal extension of the conveyor belt 23, such that the cutting plane Q intersects the advancing plane P in an orientation perpendicular to the longitudinal extension of the green tire tread 20c. In addition, the blades 51 and thus the cutting plane Q have an inclined orientation that defines a first acute angle β1 ( Figure 14 ) with respect to the advancing plane P and the upper surface S2 of the green tire tread 20c, the vertex of which points in the advancing direction of the green tire tread itself, i.e., towards the preparation section 25 and the building drum 13. This inclination helps to obtain inclined cuts at the head end A1 and the tail end B of the workpiece 21 separated from the green tire tread 20c, thus facilitating the joining on the building drum 13. Preferably, the value of the first acute angle β1 is included between 15° and 30°.

[0180] When the abutment plate 50 is in the working position, the cutting group 30 is adapted to translate from the starting position towards the arrival position by moving the blades 51 along the cutting line L to determine the separation of the workpiece 21 from the respective green tire tread 20c. The execution of the cutting can be facilitated by high-frequency vibrations (preferably ultrasonic) transmitted by respective ultrasonic transducers 43 to the cutting group 30.

[0181] 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 with respect to the cutting line L. Thus, at one end of the cutting edge 51a, a cutting vertex 52 pointing towards the abutment plate 50 can be identified. During the execution of the cutting, the cutting edge 51a extends away from the abutment surface 50a ( Figure 12 ) present above the abutment plate 50 starting from the cutting vertex 52. More particularly, the cutting edge 51a forms a second acute angle β2 in the cutting plane Q with respect to the advancing plane P ( Figure 15), whose vertex points to the starting position. In this way, the cutting edge 51a is adapted to transmit the thrust component directed against the abutment plate 50 to the green strip 20c during the translation of the cutting group 30 towards the arrival position. Preferably, the value of the second acute angle β2 is included between 5° and 15°.

[0182] In addition, the cutting edge 51a forms a third acute angle β3 in a plane parallel to the advancing plane P ( Figure 12 ), whose vertex points to the starting position. In this way, it helps the cutting edge 51a to penetrate into the green strip 20c. Preferably, the value of the third acute angle β3 is included between 5° and 25°.

[0183] During the translation of the cutting group 30, the cutting vertex 52 is preferably adapted to operate through the green strip 20c without direct contact between the cutting group 30 and the abutment plate 50 itself. In fact, it is conveniently provided that the abutting surface 50a of the abutment plate 50 is separated from the cutting vertex 52 of the cutting group 30 by a measured value not exceeding 0.05 mm. Thus, a neat cutting of the green strip 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.

[0184] Preferably, the operation of the cutting group 30 is assisted by a blocking device 53 of the green strip 20c relative to the advancing plane P, and the blocking device operates near the abutment plate 50. These blocking devices 53 include at least one thrust plate, which is configured to act elastically on the green strip 20c through its terminal edge during the execution of the cutting.

[0185] More particularly, it is preferably provided that the first thrust plate 54a and the second thrust plate 54b operate respectively upstream and downstream of the cutting plane Q and can be selectively activated to push the green strip 20c and thus exert a holding action on the semi-finished product itself, preferably exert a holding action on the semi-finished product itself against the abutment plate 50. Each of the first thrust plate 54a and the second thrust plate 54b can be conveniently made in the form of an elastically deformable plate, which has a plurality of elastically deformable sheets 55 distributed parallel and along its terminal edge respectively.

[0186] Before the cutting group 30 acts on the green strip 20c, the first thrust plate 54a and the second thrust plate 54b are adapted to be brought from a waiting position (as Figure 13 shown, in which waiting position they are spaced above the semi-finished product itself) to a thrust position (as Figure 14As shown, in the thrust positions, they operate against the tread band semi-finished product 20c to gently hold the semi-finished product against the abutment plate 50). Thus, the tread band semi-finished product 20c is properly stably held against the abutment plate 50, and cutting can be performed without causing an undesired lateral movement of the semi-finished product itself under the thrust force transmitted by the blade 51.

[0187] After cutting is completed, the first thrust plate 54a and the second thrust plate 54b can return to the waiting position, and the abutment plate 50 is brought back to the stationary position to reposition the tail end B of the cut workpiece 21 and the new head end A formed on the just-cut tread band semi-finished product 20c to be coplanar with the advancing plane P.

[0188] Similarly to the above, thus, the cut workpiece 21 is adapted to be advanced towards the building drum 13 under the action of the preparation section 25 of the conveyor belt 23 to determine the winding of the tread band around the laying surface 15 by the tread band applying device 19.

[0189] The size-cutting process, which has been particularly described above with reference to one or more carcass plies 4, sidewall inserts 12, and tread bands 6, can be conveniently initiated. As an additional or alternative solution for at least one of such tire components, this process can be conveniently initiated on other components such as the liner 10, elastomeric substrate 9, reinforcing bead 11, and / or one or more belt plies 7, 8, which are optionally provided in the structural solution of the tire 2. For each of these components, it is basically provided that the corresponding semi-finished products 20a, 20b, 20c, 20d are arranged in the form of continuous strips, and their structural, width, and thickness characteristics correspond to the structural, width, and thickness characteristics of the corresponding tire components. Before applying the semi-finished products around the laying surface 15 of the building drum 13, the semi-finished products are subjected to the size-cutting process. For components applied in pairs (such as sidewall reinforcements 12), it can be provided that a pair of sidewall reinforcement semi-finished products are arranged and the size-cutting process is performed on them simultaneously or independently, and then the obtained workpieces are applied simultaneously or independently.

Claims

1. A process for constructing a tire for a bicycle, wherein, A plurality of components of the tyre (2) being processed are circumferentially laid around a laying surface (15) carried by a building drum (13), wherein the process comprises: Applying at least one carcass ply (4) around the laying surface (15); Applying a pair of bead cores (5) around the carcass ply (4) at a predetermined mutual axial distance; Axially turning up the axially outer end flaps (4a) of the carcass ply (4) around the bead cores (5); Applying a tread band (6) around the laying surface (15), maintaining substantially unchanged the mutual axial distance of the bead cores (5); Wherein, before laying at least one of the components, a corresponding semi-finished product (20a, 20b, 20c, 20d) in the form of a continuous strip is dimensionally cut along a cutting line (L) to separate from the semi-finished product itself a workpiece (21) having a predetermined cutting length; Wherein the dimensional cutting process comprises: Positioning the semi-finished product (20a, 20b, 20c, 20d) such that its lower surface (S1) abuts against a propulsion plane (P) defined by a conveyor belt (23), the conveyor belt comprising a continuously aligned feed section (24) and a preparation section (25); Longitudinally advancing the semi-finished product (20a, 20b, 20c, 20d) along the propulsion plane (P) and above an abutment plate (50) disposed between the feed section (24) and the preparation section (25); Stopping the advancement of the semi-finished product (20a, 20b, 20c, 20d) relative to a cutting plane (Q) when the head end (A) of the semi-finished product (20a, 20b, 20c, 20d) is spaced apart from the cutting plane (Q) by a measurement equal to the cutting length, the cutting plane containing the cutting line (L) and intersecting the propulsion plane (P) at the abutment plate (50); Lifting the abutment plate (50) and the cutting section (T) of the semi-finished product (20a, 20b, 20c, 20d) disposed on the abutment plate relative to the propulsion plane (P); Translating a cutting member (51) transversely to the semi-finished product (20a, 20b, 20c, 20d) to cut the semi-finished product along the cutting line (L); Repositioning the abutment plate (50) such that the abutment plate is coplanar with the propulsion plane (P), the abutment plate carrying the tail end (B) of the cut workpiece (21) and the head end (A) of the cut semi-finished product (20a, 20b, 20c, 20d).

2. The process according to claim 1, wherein The cutting member (51) translates from a starting position to an arrival position during the cutting of the semi-finished product (20a, 20b, 20c, 20d) and is brought back to the starting position after the repositioning of the abutment plate (50).

3. The process according to claim 1 or 2, wherein During the translation of the cutting member (51), the cutting edge (51a) of the cutting member (51) transfers a thrust component directed towards the abutment plate (50) to the semi-finished product (20a, 20b, 20c, 20d).

4. The process according to one or more of the preceding claims, the process further comprising transmitting ultrasonic frequency vibrations to the cutting member (51) while transversely cutting the semi-finished product (20a, 20b, 20c, 20d).

5. The process according to one or more of the preceding claims, wherein, The translation of the cutting member (51) occurs when the cutting member is not in direct contact with the abutment plate (50).

6. The process according to one or more of the preceding claims, wherein, During the translation of the cutting member (51), the abutment surface (50a) of the abutment plate (50) is spaced apart from the cutting edge (51a) of the cutting member (51) by a measured value of no more than 0.1 mm.

7. The process according to one or more of the preceding claims, wherein, The cutting plane (Q) intersects the advancing plane (P) in an inclined orientation that defines a first acute angle (β1) relative to the advancing plane (P), the vertex of the first acute angle pointing towards the building drum (13).

8. The process according to one or more of the preceding claims, wherein, During the execution of the cutting, a blocking action of the semi-finished product (20a, 20b, 20c, 20d) is performed relative to the advancing plane (P).

9. The process according to one or more of the preceding claims, wherein, With reference to the advancement of the semi-finished product (20a, 20b, 20c, 20d), the blocking action is performed upstream and downstream of the cutting plane (Q).

10. The process according to one or more of the preceding claims, wherein, The blocking action is performed against the abutment plate (50).

11. The process according to one or more of the preceding claims, wherein, Laying the tread strip (6) includes: Arranging the tread strip semi-finished product (20c) in the form of a continuous strip; Performing the sizing cutting process on the tread strip semi-finished product (20c).

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

13. The process according to one or more of the preceding claims, wherein, The component further includes an elastomeric substrate (9) arranged circumferentially around the laying surface (15) before laying the tread strip (6).

14. The process according to claim 13, wherein, Laying the elastomeric substrate (9) includes: Arranging the elastomeric substrate semi-finished product in the form of a continuous strip; Performing the sizing cutting process on the elastomeric substrate semi-finished product.

15. The process according to claim 14, wherein, The thickness of the elastomeric substrate semi-finished product (9) is between 0.5 mm and 1.5 mm.

16. A device for constructing a tire for a bicycle, the device comprising: A building drum (13); A laying group (14) configured to circumferentially lay a plurality of components around a laying surface (15) carried by the building drum (13); Wherein, the laying group (14) includes: A carcass ply applying device (16) configured to apply at least one carcass ply (4) around the laying surface (15); A bead core applying device for applying a pair of bead cores (5) around the carcass ply (4) at a predetermined mutual axial distance; A turning-up device (13a) configured to axially turn up the outer end flap (4a) of the carcass ply (4) around the bead core (5); A tread strip applying device (19) configured to apply a tread strip (6) around the laying surface (15) such that the tread strip is axially centered between the bead cores (5) arranged according to the predetermined mutual axial distance; Among them, the laying group (14) includes at least one preparation unit (22a, 22b, 22c, 22d), and the preparation unit is configured to transversely cut the semi-finished products (20a, 20b, 20c, 20d) in the form of a continuous strip along the cutting line (L) according to size, so as to separate workpieces (21) with a predetermined cutting length from the semi-finished products themselves; Among them, the preparation unit (22a, 22b, 22c, 22d) includes: A conveyor belt (23), the conveyor belt includes a feeding section (24) and a preparation section (25), the feeding section and the preparation section are continuously aligned according to a propulsion plane (P) transverse to a cutting plane (Q) including the cutting line (L), and the conveyor belt is configured to support the semi-finished products (20a, 20b, 20c, 20d) so that the lower surface (S1) of the semi-finished products abuts against the propulsion plane itself; Control means (31) for controlling the conveyor belt (23), the control means is configured to longitudinally advance the semi-finished products (20a, 20b, 20c, 20d) along the propulsion plane (P), and 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) is spaced apart from the cutting plane (Q) by a measurement equal to the cutting length; A butting plate (50), the butting plate is disposed between the feeding section (24) and the preparation section (25) of the conveyor belt in the cutting plane (Q), and can move between a stationary position and a working position. In the stationary position, the butting plate is substantially coplanar with the propulsion plane (P). In the working position, the butting plate is lifted relative to the propulsion plane (P) to lift the cutting section (T) of the semi-finished products (20a, 20b, 20c, 20d) traversed by the cutting plane (Q) relative to the propulsion plane (P); A cutting member (51), the cutting member can move transversely to the semi-finished products (20a, 20b, 20c, 20d) to cut the semi-finished products along the cutting line (L).

17. The apparatus according to claim 16, wherein, The cutting member (51) can move along the cutting line (L) from a starting position to an arrival position, wherein the butting plate (50) is configured to be positioned in the stationary position before the cutting member (51) returns to the starting position.

18. The device according to claim 17 or 18, wherein The preparation unit (22a, 22b, 22c, 22d) further includes an ultrasonic transducer (43), and the ultrasonic transducer operates on the cutting member (51) to transmit ultrasonic frequency vibrations to the cutting member.

19. The device according to one or more of claims 16 to 18, wherein, The cutting member includes a blade (51) that can move along the cutting direction.

20. The apparatus according to claim 19, wherein The blade (51) has an inclined orientation, and the inclined orientation defines a first acute angle (β1) relative to the propulsion plane (P), and the vertex of the first acute angle points to the preparation section (25).

21. The device according to one or more of claims 16 to 20, wherein, The cutting edge (51a) of the cutting member (51) lies in the cutting plane (Q) in an orientation inclined with respect to the cutting line (L).

22. The apparatus according to claim 21, wherein The cutting edge (51a) forms a second acute angle (β2) in the cutting plane (Q) and with respect to the advancing plane (P), the vertex of the second acute angle pointing towards the starting position.

23. The device according to claim 21 or 22, wherein, The cutting edge (51a) forms a third acute angle (β3) parallel to the advancing plane (P), the vertex of the third acute angle pointing towards the starting position.

24. The apparatus according to one or more of claims 16 to 23, wherein, The cutting member (51) has a cutting vertex (52) pointing towards the abutment plate (50), and the cutting vertex is configured to operate through the semi-finished products (20a, 20b, 20c, 20d) without directly contacting the abutment plate (50) itself.

25. The device according to claim 24, wherein, The cutting vertex (52) is configured to operate through the semi-finished products (20a, 20b, 20c, 20d) when the lower surface (S1) contacts the abutment surface (50a) of the abutment plate (50), wherein the abutment surface (50a) is spaced from the cutting vertex (52) by a measured value of not more than 0.1 mm.

26. The apparatus according to one or more of claims 16 to 25, the apparatus further comprising a blocking device (53) for operating close to the abutment plate (50) to block the semi-finished products (20a, 20b, 20c, 20d) with respect to the advancing plane (P).

27. The apparatus according to claim 26, wherein, The blocking device (53) is configured to press the semi-finished products (20a, 20b, 20c, 20d) against the abutment plate (50).

28. The device according to claim 26 or 27, wherein, The blocking device (53) includes at least one thrust plate (54a, 54b), the thrust plate being configured to act elastically on the semi-finished products (20a, 20b, 20c, 20d) through the end edge of the thrust plate.

29. The device according to claim 28, wherein, The thrust plate (54a, 54b) is obtained in the form of an elastically deformable plate.

30. The device according to claim 28 or 29, wherein, The thrust plate (54a, 54b) has a plurality of elastically deformable sheets (55) that are respectively parallel and distributed along the end edge.

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