Process and plant for building tyres for vehicle wheels

Abstract

A plant for building tyres of at least two different models for vehicle wheels, includes at least a tyre building line, which in turn, includes: a plurality of work stations arranged according to a sequential series, each work station being adapted for building at least one structural component of each tyre and assembling at least one elementary component; at least one handling device for the tyres being processed on the respective forming supports associated to each work station; and at least one transfer device adapted for transferring the tyre being processed on its forming support from any first work station of the sequential series to any other second work station not adjacent thereto of the sequential series, so that the tyre being processed on its forming support only passes in the first and second work stations.

Claims

1. A plant for building tyres for vehicle wheels on forming supports, said tyres comprising multiple different models, each tyre comprising a carcass structure and a belt structure, the plant comprising a plurality of work stations arranged along a tyre building line, which in turn, comprises: a first carcass structure handling device configured to receive a forming support and associated with a first carcass structure building work station, the first carcass structure building work station comprising a strip-like element feeding unit, a ply application unit, and a bead core application unit and builds a complete first carcass structure with at least a ply and a bead core; a second carcass structure handling device to receive the forming support and associated with a second carcass structure building work station, the second carcass structure building work station comprising a strip-like element feeding unit, a ply application unit, and a bead core application unit and builds a complete second carcass structure with at least a ply and a bead core; a plurality of belt structure handling devices to receive the forming support and at least two belt structure building work stations, wherein: each of at least two of the belt structure handling devices is associated with a first belt building work station, the first belt building work station comprising a plurality of belt layer application units and builds a same complete first belt structure for one of the different models of tyre comprising two belt layers; and each of at least two belt structure handling devices is associated with a second belt building work station, the second belt building work station comprising a plurality of belt layer application units and builds a same complete second belt structure for another of the different models of tyre comprising a single belt layer; and a robotized arm, wherein the robotized arm: transfers and releases a first forming support holding a first model of tyre from the first carcass structure building work station to any one of the belt building work stations, the transfer and release of the first forming support occurs at the same time as the building of the complete second carcass structure of a second model of tyre held by a second forming support in the second carcass structure building work station; and, transfers and releases the second forming support holding the second model of tyre from the second carcass structure building work station to any one of the other belt building work stations, the transfer and release of the second forming support occurs at the same time as the building of the belt structure on the first forming support in the any one of the belt building work stations, and further wherein during the transfer of the first and second forming supports, each of the first and second forming supports follows different first and second paths respectively from start to finish in the tyre building line based on the model of tyre on the forming support and on the availability of the plurality of work stations.

2. The tyre building plant according to claim 1, wherein the plurality of work stations further comprises at least one tread band building work station.

3. The tyre building plant according to claim 2, wherein the tread band building work station comprises at least one tread band application unit.

4. The tyre building plant according to claim 3, comprising two tread band application units.

5. The tyre building plant according to claim 2, further comprising at least one tread band underlayer application unit provided with devices for applying at least one tread band underlayer.

6. The tyre building plant according to claim 5, wherein said one tread band underlayer application unit is arranged in the tread band building work station.

7. The tyre building plant according to claim 1, wherein each forming support is a toroidal support.

8. The tyre building plant according to claim 7, wherein said toroidal support has a radially external surface corresponding to a radially internal surface of a tyre processed.

9. The tyre building plant according to claim 1, wherein the first carcass structure building work station builds a carcass structure differing from the carcass structure built by the second carcass structure building work station.

10. The tyre building plant according to claim 1, wherein at least one work station builds at least one structural component of each tyre by assembling at least one elementary component.

11. The tyre building plant according to claim 10, comprising a line for preparing elementary components fed to said at least one work station.

12. The tyre building plant according to claim 1, wherein said bead core application unit within each carcass structure building work station comprises at least one device with a dispenser for dispensing a continuous elongated element shaped as a rubber coated metal reinforcing cord.

13. The tyre building plant according to claim 12, wherein at least one actuator is connected to each of the first and second carcass structure handling devices, for moving the forming support so as to apply said continuous elongated element according to radially overlapped coils.

14. The tyre building plant according to claim 1, wherein each belt structure building work station comprises: an under-belt layer application unit provided with devices for applying an under-belt layer in a position radially external to said respective complete carcass structure.

15. The tyre building plant according to claim 1, wherein said first belt building work station applies said two belt layers as two radially overlapped belt layers, said layers arranged in such a way that cords of a first belt layer are slanting relative to an equatorial plane of a tyre being processed, whereas the cords of a second layer also have a slanting orientation but symmetrically crossed relative to the cords of the first layer.

16. The tyre building plant according to claim 1, wherein said second belt building work station applies said single belt layer as a layer of textile or metal cords oriented circumferentially at 0.

17. The tyre building plant according to claim 1, further comprising at least one sidewall building work station provided with a sidewall application unit for building at least one sidewall portion in a position axially external to a tyre processed.

18. The tyre building plant according to claim 1, further comprising a liner application work station provided with a liner application unit.

19. The tyre building plant according to claim 1, wherein at least one of said work stations comprises at least one device with a dispenser for dispensing a continuous elongated element of elastomeric material and a handling device.

20. The tyre building plant according to claim 19, wherein at least one actuator is connected to the handling device associated with said at least one of said work stations for moving the forming support so as to apply said continuous elongated element according to side by side or at least partially overlapped coils.

21. The tyre building plant according to claim 1, wherein the robotized arm moves on a guiding track.

22. The tyre building plant according to claim 21, wherein some of the plurality of work stations are positioned on one side of the guiding track, others of the plurality of work stations are positioned on the opposite side of the guiding track, and all work stations are proximate to the movable robotized arm.

23. The tyre building plant according to claim 22, wherein said some of the plurality of work stations include the first and second carcass structure building work stations.

24. The tyre building plant according to claim 23, wherein said others of the plurality of work stations include the second belt building work station.

25. The tyre building plant according to claim 24, wherein said some of the plurality of work stations include the first belt building work station.

26. The tyre building plant according to claim 1, wherein any of said handling devices comprises at least one robotized arm.

27. The tyre building plant according to claim 1, wherein at least one of the first model of tyre and the second model of tyre is for a two-wheel vehicle.

28. The tyre building plant according to claim 1, wherein the first model of tyre is a one-ply tyre, the second model of tyre is a two-ply tyre.

29. A plant for building tyres for vehicle wheels on forming supports, said tyres comprising at least two different models, each tyre comprising a carcass structure, a belt structure, and a tread structure, the plant comprising a plurality of work stations arranged along a tyre building line, which in turn, comprises: a first carcass structure handling device to receive a forming support and associated with a first carcass structure building work station; a second carcass structure handling device to receive the forming support and associated with a second carcass structure building work station; a plurality of belt structure handling devices to receive a forming support and at least two belt structure building work stations, wherein: each of at least two of the belt structure handling devices is associated with a first belt structure building work station having a plurality of belt layer application units to apply at least one belt layer with cords slanted relative to an equatorial plane for building a same complete belt structure on a first model of tyre; and each of other at least two belt structure handling devices is associated with a second belt structure building work station having a plurality of belt layer application units to apply at least one belt layer with cords oriented circumferentially at 0 to the equatorial plane for building a same complete belt structure on a second model of tyre; a plurality of tread band handling devices to receive the forming support and associated with a tread band building work station, the tread band building work station comprising two tread band application units and builds a same complete tread band for the at least two different models of tyre; and a robotized arm, wherein the robotized arm: transfers and releases a first forming support holding a first model of tyre from the first carcass structure building work station to any one of the belt building work stations, the transfer and release of the first forming support occurs at the same time as the building of a complete second carcass structure of a second model of tyre held by a second forming support in the second carcass structure building work station: and, transfers and releases the second forming support holding the second model of tyre from the second carcass structure building work station to any one of the other belt building work stations, the transfer and release of the second forming support occurs at the same time as the building of the complete belt structure on the first forming support in the any one of the belt building work stations, and further wherein during the transfer of the first and second forming supports, each of the forming supports follows different first and second paths respectively from start to finish in the tyre building line based on the model of tyre on the forming support and on the availability of the plurality of work stations.

30. The tyre building plant according to claim 29, wherein the robotized arm moves on a guiding track.

31. The tyre building plant according to claim 30, wherein some of the plurality of work stations are positioned on one side of the guiding track, others of the plurality of work stations are positioned on the opposite side of the guiding track, and all work stations are proximate to the robotized arm.

32. The tyre building plant according to claim 31, wherein said others of the plurality of work stations include the tread band building work station.

33. The tyre building plant according to claim 32, wherein said others of the plurality of work stations include the second belt building work station.

34. The tyre building plant according to claim 33, wherein said some of the plurality of work stations include the first belt building work station.

35. The tyre building plant according to claim 29, wherein each forming support is a toroidal support.

36. The tyre building plant according to claim 35, wherein said toroidal support has a radially external surface corresponding to a radially internal surface of a tyre processed.

37. The tyre building plant according to claim 29, wherein the first carcass structure building work station builds a carcass structure differing from the carcass structure built by the second carcass structure building work station.

38. The tyre building plant according to claim 37, wherein said first and second carcass structure building work stations each comprises a ply application unit and a bead core application unit, wherein said bead core application unit comprises at least one device with a dispenser for dispensing a continuous elongated element shaped as a rubber coated metal reinforcing cord.

39. The tyre building plant according to claim 38, wherein at least one actuator is connected to a handling device associated with said carcass structure building work stations, for moving the forming support so as to apply said continuous elongated element according to radially overlapped coils.

40. The tyre building plant according to claim 29, wherein at least one work station builds at least one structural component of each tyre by assembling at least one elementary component.

41. The tyre building plant according to claim 40, further comprising a line for preparing elementary components fed to said at least one work station.

42. The tyre building plant according to claim 29, wherein the belt structure building work stations each comprises: an under-belt layer application unit provided with devices for applying an under-belt layer in a position radially external to said carcass structure.

43. The tyre building plant according to claim 29, wherein the first belt structure building work station applies at least two radially overlapped belt layers, said layers arranged in such a way that cords of a second layer also have a slanting orientation but symmetrically crossed relative to the cords of the first layer.

44. The tyre building plant according to claim 29, further comprising at least one tread band underlayer application unit provided with devices for applying at least one tread band underlayer.

45. The tyre building plant according to claim 44, wherein said one tread band underlayer application unit is arranged in the tread band building work station.

46. The tyre building plant according to claim 29, further comprising at least one sidewall building work station provided with a sidewall application unit for building at least one sidewall portion in a position axially external to a tyre processed.

47. The tyre building plant according to claim 29, further comprising a liner application work station provided with a liner application unit.

48. The tyre building plant according to claim 29, further comprising at least one strip-like element feeding unit.

49. The tyre building plant according to claim 29, wherein at least one of said work stations comprises at least one device with a dispenser for dispensing a continuous elongated element of elastomeric material and a handling device.

50. The tyre building plant according to claim 49, wherein at least one actuator is connected to the handling device associated with said at least one of said work stations for moving the forming support so as to apply said continuous elongated element according to side by side or at least partially overlapped coils.

Description

(1) Further features and advantages of invention will appear more clearly from the following description of some preferred examples of methods for selecting work stations, processes for manufacturing tyres and tyre building plants according to the invention, made by way of an indicative non-limiting example with reference to the annexed drawings, wherein:

(2) FIG. 1 shows a schematic layout of a plant for building tyres for vehicle wheels wherein the method for selecting work stations and the process for manufacturing tyres according to an embodiment of the present invention are carried out.

(3) With reference to such FIGURE, reference numeral 1 globally indicates a building line of a plant for building tyres for vehicle wheels according to the present invention. The tyres to be built are at least of two different models. Such models may differ in terms of size, structural components and/or elementary components.

(4) The building line 1 of the plant comprises a plurality of work stations 4, 4, 5, 5, 6, 12, 14, each of which is adapted for building at least one structural component of each tyre, by assembling at least one elementary component. The work stations 4, 4, 5, 5, 6, 12, 14 are arranged according to a sequential series, according to the definition given above.

(5) The building line 1 of the system further comprises at least one handling device 3 for the tyres being processed on the respective forming supports associated to each work station 4, 4, 5, 5, 6, 12, 14. Each handling device 3 is adapted for cooperating with the respective work station 4, 4, 5, 5, 6, 12, 14 for assembling said elementary components.

(6) The building line 1 also comprises at least one transfer device 2, which is adapted for transferring the tyre being processed on its forming support from any first work station of the sequential series to any other second work station even not adjacent to the first one, so that the tyre being processed on its forming support only passes in said first and second work station along a transfer path.

(7) Said transfer path is the path followed by the forming support 2 and may be of any type (rectilinear, zigzag, etc.). If the transfer takes place from one work station 4, 4, 5, 5, 6, 12, 14 to a subsequent one and not adjacent thereto, said transfer path is generally different from the path that would be followed by the transfer support 2 for moving from one work station 4, 4, 5, 5, 6, 12, 14 to the work station 4, 4, 5, 5, 6, 12, 14 adjacent and subsequent thereto in said sequential series.

(8) In particular, the plurality of work stations 4, 4, 5, 5, 6, 12, 14 comprises:

(9) at least one carcass structure building work station 4, 4;

(10) at least one belt structure building work station 5, 5; and

(11) at least one tread band building work station 6;

(12) wherein the carcass structure comprises at least one carcass ply and a pair of annular anchoring structures and the belt structure comprises at least one belt layer.

(13) As shown in the FIGURE, the first carcass structure building work stations 4, 4 are two, a first carcass structure building work station 4 adapted for building a carcass structure which may be different from the carcass structure built by a second carcass structure building work station 4. As an alternative, the first carcass structure building work station 4 and the second carcass structure building work station 4 may carry out the building of the same carcass structure on a respective forming drum, for example in the case of two-ply tyres.

(14) Each carcass structure building work station 4, 4 comprises a ply application unit 7 and a bead core application unit 8.

(15) The bead core application unit 8 is preferably provided with a device exhibiting a dispenser of a continuous elongated element shaped as a rubber metal reinforcing cord, whereas actuators preferably connected to each handling device 3 associated to the carcass structure building work stations 4, 4, move the forming support so as to wind said continuous elongated element according to preferably radially overlapped coils for manufacturing annular anchoring structures.

(16) In the embodiment shown in the FIGURE, said belt structure building work stations 5, 5 are two (whereof only one is detailed in FIG. 1). Each of them comprises an under-belt layer application unit 9 provided with devices for applying an under-belt layer in a position radially external to said carcass structure.

(17) Each belt structure building work station 5, 5 further comprises at least one belt layer application unit 10 provided with devices for applying at least a first belt layer in a position radially external to said carcass structure.

(18) A first belt structure building work station 5 is preferably adapted for applying at least two radially overlapped belt layers, said layers being arranged in such a way that the cords of the first belt layer are oriented sideways relative to the equatorial plane of the tyre being processed, whereas the cords of the second layer also exhibit a slanting orientation but symmetrically crossed relative to the cords of the first layer.

(19) A second belt structure building work station 5 of the tyre building plant shown in the FIGURE comprises two belt layer application units 10.

(20) Preferably, said second belt structure building work station 5 is adapted for applying at least one belt layer comprising a layer of textile or metal cords, oriented circumferentially at 0.

(21) The tread band building work station 6 of the building line 1 comprises at least one tread band application unit 11.

(22) In the embodiment shown in the FIGURE, the tread band building work station 6 comprises two tread band application units 11 and one tread band underlayer application unit 13. The latter is provided with devices for applying at least one tread band underlayer.

(23) However, such tread band underlayer application unit 13 may be arranged outside the tread band building work station 6 in a dedicated building work station.

(24) The building plant 1 further comprises at least one sidewall building work station 12 provided with a sidewall application unit 17 for building at least a sidewall portion in a position axially external to the tyre being processed.

(25) The building plant 1 shown in FIG. 1 further comprises work station for applying a liner 14 provided with a liner application unit 18.

(26) The building line 1 is provided with a strip-like element feeding unit 16 for each carcass structure building work station 4, 4. Similar strip-like element feeding units may be provided for each belt structure building work station 5, 5.

(27) Preferably, at least one of the above work stations 4, 4, 5, 5, 6, 12, 14 in sequential series comprises a device that exhibits a dispenser of a continuous elongated element of elastomeric material. In this case, each work station provided with such device also comprises one or more actuators for moving the forming support so as to wind the continuous elongated element according to side by side and/or at least partially overlapped coils. Even more preferably, at least the under-belt layer application unit 9, the tread band underlayer application unit 13, the tread band application units 11, the sidewall application unit 17, the liner application unit 18, comprise each the above device.

(28) The tyre building plant according to an embodiment of the invention may comprise a preparation line for some elementary components (generally strip-like elements and/or rubber cords) adapted for being fed to the work stations 4, 4, 5, 5. Such line is not shown in the FIGURE.

(29) The transfer device 2 adapted for transferring the tyre being processed on its forming support from a work station to another work station of the sequential series comprises a robotized arm. Preferably, the transfer device 2 is associated to a guiding track 15 whereon such robotized arm moves.

(30) Preferably, each handling device 3 for the tyres being processed on the respective forming supports comprises at least one robotized arm.

(31) According to preferred embodiments of the present invention, at least one model of tyre to be built is for two-wheel vehicles, wherein the bending ratio R between the distance between the radially outer distance of the tread band and the line passing by the laterally opposite ends of the tread band itself, measured on the equatorial plane of the tyre, and the distance measured along the tyre chord between said ends is more than or equal to, about 0.15.

(32) In particular, said bending ratio R is less than or equal to, about 0.3 or less than or equal to, about 0.45, based on the fact that the tyre to be built is of the rear or front type.

(33) Preferably, the forming support is a toroidal support. Even more preferably, the toroidal support has a radially external surface corresponding to a radially internal surface of the tyre being processed (and built).

(34) The method for selecting work stations 4, 4, 5, 5, 6, 12, 14 in a building line 1 of tyres in at least two different models, wherein said building line 1 comprises a plurality of work stations 4, 4, 5, 5, 6, 12, 14 arranged according to a sequential series, wherein each work station 4, 4, 5, 5, 6, 12, 14 is adapted for building at least one structural component of each tyre, preferably by assembling at least one elementary component, according to the present invention, comprises the step of:

(35) selecting at least two work stations 4, 4, 5, 5, 6, 12, 14 not adjacent to each other whereto a tyre being processed is transferred based on the tyre model, on the structural component to be built and on the availability of the work stations themselves.

(36) The transfer is carried out so that the tyre being processed only passes in said at least two work stations 4, 4, 5, 5, 6, 12, 14 along a transfer path.

(37) The method for selecting work stations 4, 4, 5, 5, 6, 12, 14 comprises, prior to the selection step, the step of receiving information on the model of tyre to be built and on the availability of the work stations 4, 4, 5, 5, 6, 12, 14.

(38) In other words, the selection method according to the invention provides for the reception of the above information and the processing thereof so as to select the most suitable work stations 4, 4, 5, 5, 6, 12, 14 to transfer the tyres being processed.

(39) Preferably, according to a step a), the tyre building process provides for arranging a plurality of elementary components of the tyres to be built at a plurality of work stations 4, 4, 5, 5, 6, 12, 14.

(40) Afterwards, the process provides for a step b) of building at least a first and a second model of tyre on respective forming supports, building each structural component, preferably by assembling at least one of said elementary components, at the work stations 4, 4, 5, 5, 6, 12, 14. The latter are arranged according to a sequential series in a tyre building line 1, wherein the tyres being processed on the respective forming supports are transferred from one work station 4, 4, 5, 5, 6, 12, 14 to the other by a transfer device 2.

(41) According to the invention, the step b) of building at least a first and a second tyre model comprises at least one step c) of transferring a tyre being processed on its own forming support from a first work station 4, 4, 5, 5, 6, 12, 14 of the building line 1 to a second work station 4, 4, 5, 5, 6, 12, 14 not adjacent thereto in said sequential series.

(42) Moreover, according to the process of the invention, each transfer step c) is carried out so that the tyre being processed on its forming support only passes in said first and second work station 4, 4, 5, 5, 6, 12, 14 along a transfer path.

(43) According to a preferred embodiment, the building step b) comprises, upstream of the transfer step c), a step of:

(44) d) selecting the work station 4, 4, 5, 5, 6, 12, 14 whereto a tyre being processed is transferred based on the tyre model, on the structural component to be built and on the availability of the work stations 4, 4, 5, 5, 6, 12, 14 themselves.

(45) The building step b) is preferably carried out by transferring the tyre being processed from a work station 4, 4, 5, 5, 6, 12, 14 to a subsequent work station 4, 4, 5, 5, 6, 12, 14 of said sequential series. That is, the transfer takes place according to a travelling direction of the building line 1.

(46) In particular, the building step c) comprises the steps of:

(47) i) building a carcass structure, which comprises at least one carcass ply and a pair of annular anchoring structures;

(48) ii) building a belt structure, which comprises at least one belt layer; and

(49) iii) building a tread band.

(50) According to a preferred embodiment, the above step ii) comprises building a belt structure provided with a layer of textile or metal cords, oriented circumferentially at 0.

(51) The process for manufacturing tyres further comprises a pre-step of feeding elementary components into the corresponding work station.

(52) With reference to the tyre building line 1, an operating example of the plant illustrated in FIG. 1 shall now be described, for example in the case of two models of tyres A and B, where A is a one-ply tyre and B is a two-ply tyre, A and B having both a layer of metal cords at 0 as belt structure.

(53) A forming support for tyre A being processed is transferred to the liner application work station 14 wherein the liner application unit 18 applies a liner layer thereon, preferably by the application of at least one continuous elongated element of elastomeric material according to side by side and/or overlapped coils. Such liner application step may be preceded by an application step of at least one bead reinforcing fabric and/or by an application step of an abrasion-proof element on the forming support of tyre A.

(54) Afterwards it is also possible to apply a under-liner layer in a position radially external to the liner layer.

(55) Tyre A being processed is transferred to a carcass structure building work station 4 or 4according to the type of ply required by tyre A or to the availability of said work stations 4, 4where, according to step i), the building of the carcass structure is carried out. In this example, the one-ply tyre A is carried by the transfer device 2 from the liner application work station 14 directly to the second carcass structure building work station 4 as the latter is free, without passing by the first carcass structure building work station 4, according to what provided in the selection step of said method and with step c) of the process according to the invention.

(56) In said second carcass structure building work station 4, a carcass ply is applied in a position radially external to the liner layer or to the under-liner layer (if provided), by the ply application unit 7, preferably by laying a plurality of strip-like elements side by side to each other. According to different project specifications, further elementary components may be applied to manufacture further structural components of the carcass structure.

(57) Afterwards, step i) provides for applying at least a pair of annular anchoring structures at the axially opposite ends of the carcass ply. Such step is carried out by the bead core application unit 8, the operation whereof has been illustrated hereinbefore.

(58) Afterwards it is possible to apply, at the carcass ply of tyre A being processed, a plurality of inside and/or outside reinforcing elements and/or an abrasion-proof element.

(59) At the same time as the building of tyre A, also tyre B is built according to step b) of the process illustrated above.

(60) More precisely, the forming support of tyre B being processed is transferred to the liner application work station 14 as soon as this is left free by tyre A being processed. The same process described above for tyre A is carried out in the above liner application work station 14.

(61) According to step i) of the present invention, the carcass structure building is then carried out: Tyre B being processed is transferred by the transfer device 2 into the first carcass structure building work station 4 for applying the first carcass ply, such work station is free since tyre A has been transferred to the second carcass structure building station 4. After that, the transfer device 2 transfers tyre B into the second carcass structure building work station 4 for applying the second carcass ply once that tyre A, completed its carcass structure building step, has been transferred from the above work station.

(62) In particular, in the second carcass structure building work station 4 a second carcass ply is applied in a position radially external to the first carcass ply of tyre B with methods similar to those of application of the first carcass ply. Such step is followed by the application of at least a further pair of annular anchoring structures at the axially opposite ends of the second carcass ply.

(63) According to step c), tyre A being processed is then transferred by the transfer device 2 into the second belt structure building work station 5.

(64) In other words, in the example illustrated herein, tyre A being processed is transferred from the second carcass structure building work station 4 to the second belt structure building work station 5 without passing through the first belt structure building work station 5.

(65) In such second belt structure building work station 5 there is carried out the step ii) of building the belt structure which, in this specific example, provides first for the application of an under-belt layer in a position radially external to tyre A being processed by the under-belt layer application unit 9, preferably by the application of at least one continuous elongated element of elastomeric material according to side by side and/or partially overlapped coils, then the application of a belt layer obtained by the application of a rubber metal cord layer oriented circumferentially at 0, in a special belt layer application unit 10.

(66) According to the above step c), tyre B being processed is transferred by the transfer device 2 into the second belt structure building work station 5.

(67) In other words, tyre B being processed is transferred from the first carcass structure building work station 4 to the second belt structure building work station 5 without passing through the work stations 4 and 5.

(68) Moreover, it should be noted that thanks to the preferred configuration of the second belt structure building work station 5 (two belt layer application units 10), the transfer of tyre B in the above work station can advantageously take place even if in said work station there is still tyre A.

(69) The step ii) of building the belt structure of tyre B is carried out in such work station 5 similarly to what described above for building tyre A.

(70) Tyre A being processed is then transferred by the transfer device 2 into the tread band building work station 6 wherein the tread band building step iii) is carried out. Such step iii) may comprise the sub-step iii) of applying at least one tread band underlayer in a position radially external to the belt structure, in the tread band underlayer application unit 13. The step iii) finally comprises the sub-step iii) of applying at least one tread band layer in a position radially external to said tread band underlayer, if provided, or to said belt structure, in a tread band application unit 11. If the tread band layers are two, these are preferably applied in a sequence in the two respective tread band application units 11. Preferably, at least one between the above steps iii) and iii) are carried out by applying at least one continuous elongated element of elastomeric material according to side by side and/or at least partially overlapped coils.

(71) At the end of the building of the belt structure, also tyre B being processed is transferred by the transfer device 2 into the tread band building work station 6 wherein the tread band building step iii) is carried out with methods similar to those described for building the tread band of tyre A.

(72) Also in this case, thanks to the preferred configuration of the tread band building work station 6 (two tread band application units 11), tyre B can be transferred to the above tread band building work station 6 while tyre A is still present, further improving productivity.

(73) Afterwards, tyre A being processed is transferred by the transfer device 2 into the sidewall building work station 12. In such work station 12 the sidewall application unit 17 provides to applying at least one portion of sidewalls of tyre A in a position axially external to said tread band, carrying out step iv), by the application of at least one continuous elongated element of elastomeric material according to side by side and/or partially overlapped coils.

(74) After that, also tyre B being processed is transferred by the transfer device 2 into the sidewall building work station 12 wherein the sidewall application unit 17 provides to applying at least one portion of sidewalls of tyre B with methods similar to those described for tyre A.

(75) Tyres A and B thus built are transferred to optional further work stations for the application of optional elements such as barcodes, labels, etc. or in output from the building line 1 to proceed towards a moulding and vulcanisation unit, not shown herein.

(76) Within the scope of the above present description and in the following claims, all numerical values indicating amounts, parameters, percentages and so on are always to be deemed as preceded by the term about, if not otherwise stated. Moreover, all numerical value ranges include all possible combinations of the maximum and minimum numerical values and all possible intermediate ranges, besides those specifically indicated in the text.