Method and application unit for applying sound absorbing material in the inner cavity of a pneumatic tire

Abstract

A method and an application unit (3) for applying a sound absorbing material (2) to the inner cavity of a pneumatic tire (1) using a strip (4) of sound absorbing material (2), one side of the strip (4) of sound absorbing material (2) being provided with an adhesive layer (6), the adhesive layer (6) being covered by a protective liner (7). The steps are provided as follows: attaching an initial portion of the protective liner (7) to a recovery drum (26); partially winding the strip of sound absorbing material (2) onto an application roller (24); pressing the strip (4) of sound absorbing material (2) against the inner cavity of the pneumatic tire (1) by means of the application roller (24) while the pneumatic tire (1) is rotated; and rotating the recovery drum (26) synchronously with the pneumatic tire (1) so as to gradually wind the protective liner (7) around the recovery drum (26) as the protective liner (7) separates from the strip (4) of sound absorbing material (2).

Description

Technical Field

[0001] The invention relates to a method and an application unit for applying a sound-absorbing material in the inner cavity of a pneumatic tire. Background Art

[0002] As is well known, a pneumatic tire comprises a toroidal carcass with two annular beads supporting a toroidal tread. A tread belt, comprised of multiple tread plies, is interposed between the carcass and the tread. Within the carcass plies lies an airtight inner liner, forming an inner liner layer and retaining air within the pneumatic tire to maintain its inflation pressure.

[0003] In recent years, pneumatic tires have been developed in the direction of pneumatic tires provided with a sound absorbing material (typically sponge) inside for reducing noise generated by the pneumatic tire rolling on the road surface.

[0004] The sound absorbing material is applied to an already vulcanized pneumatic tire (because the sound absorbing material cannot withstand the combination of heat and pressure applied during the vulcanization process without being damaged) and is glued to the inner surface of the pneumatic tire (including the inner liner) particularly at the tread (i.e., corresponding to the area of the pneumatic tire in contact with the asphalt) and may also be glued to part of the sidewalls.

[0005] The sound absorbing material is provided with an adhesive layer which is applied to the surface intended to come into contact with the inner cavity of the pneumatic tire and is initially covered (protected) with a removable protective liner ("liner") which serves both to protect the adhesive layer and to allow the sound absorbing material to be wound into a roll without the sound absorbing material sticking to itself.

[0006] Typically, the process of applying sound-absorbing material to the inner cavity of a pneumatic tire provides for starting with a standard length of sound-absorbing material strip (capable of being wound into a roll) that is greater than the required length; the sound-absorbing material strip then initially needs to be cut to remove the excess, thereby giving the sound-absorbing material strip the required length depending on the inner circumference of the pneumatic tire to which it is to be glued; in other words, the sound-absorbing material strip initially needs to be cut to size. After being cut to size, the sound-absorbing material strip is wound onto itself, thus forming a roll.

[0007] In practice, the operator loads a roll of sound-absorbing material strips cut to appropriate size into an application device comprising an application roller configured to press the sound-absorbing material against the inner surface of the pneumatic tire after the protective liner has been removed (which occurs immediately before the sound-absorbing material is pressed against the inner surface); the application device further comprises a protective liner recovery drum on which the protective liner is wound after it has been separated from the sound-absorbing material (i.e., after completing its function). The application roller and the recovery drum are provided with actuating means adapted to rotate the application roller and the recovery drum at appropriate and synchronous speeds about their respective rotation axes, in such a manner as to prevent the protective liner and / or the sound-absorbing material from tearing due to excessive tension or too much looseness.

[0008] When the operator loads the strip of sound-absorbing material into the application device, the operator must manually separate the initial portion of the protective liner from the sound-absorbing material, which must then be (again manually) inserted into the slot in the recovery drum. During the application of the sound-absorbing material, in order to prevent foreign matter (debris, dust, dirt, insects, etc.) from accidentally adhering to the adhesive layer, the protective liner is preferably separated from the sound-absorbing material just before application in such a way that the adhesive is exposed to air for as short a time as possible.

[0009] At the same time, a previously vulcanized pneumatic tire is supported on a motorized roller, which rotates it and is equipped with fixed side rails that prevent any lateral translation of the tire itself. In response to an operator's command, an application device is inserted into the pneumatic tire supported by the motorized roller. The application device presses the leading end of the strip of sound-absorbing material against the inner surface of the pneumatic tire. The pneumatic tire is then rotated by the motorized roller so that the sound-absorbing material can be applied to the entire inner surface (i.e., it rotates a full circle, thereby imparting a toroidal shape to the material).

[0010] The above-described method for applying the sound-absorbing material in a pneumatic tire inevitably requires manual intervention by an operator in order to separate the initial portion of the protective liner from the sound-absorbing material; in addition, this operation is particularly long and complicated even for an experienced operator and may cause damage to the adhesive layer.

[0011] Additionally, it is important that during application within the cavity, the sound absorbing material does not undergo elongation or compression, which could lead to cracks in the sound absorbing material itself after several thousand kilometers of use of the pneumatic tire. Summary of the Invention

[0012] The object of the present invention is to provide a method and an application unit for applying a sound-absorbing material in the inner cavity of a pneumatic tire, which method and application unit make it possible to make the entire application cycle more efficient (i.e. faster and cheaper) and also more effective (i.e. making it possible to avoid damage to the adhesive layer during the initial separation of the protective liner from the sound-absorbing material).

[0013] According to the present invention, there is provided a method and an application unit for applying a sound absorbing material in the inner cavity of a pneumatic tire as set forth in the accompanying claims.

[0014] The claims describe preferred embodiments of the present invention and form an integral part of the present description. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will now be described with reference to the accompanying drawings, which show exemplary, non-limiting embodiments, and in which:

[0016] · Figure 1 is a schematic diagram of a pneumatic tire provided with a sound absorbing material disposed within an inner cavity of the pneumatic tire;

[0017] · Figure 2 A schematic diagram of an application unit for applying a sound absorbing material into the inner cavity of a pneumatic tire is shown;

[0018] · Figure 3 、 Figure 4 and Figure 5 yes Figure 2 a plurality of views of a separation station of an application unit at different operating moments, wherein the excess end is separated from the strip of sound-absorbing material; and

[0019] · Figures 6-10 yes Figure 2 Several views of a coupling station of an application unit at different operating moments, wherein a strip of sound-absorbing material is applied to the inner cavity of a pneumatic tire. DETAILED DESCRIPTION

[0020] exist Figure 1 In the figure, reference numeral 1 generally denotes a pneumatic tire mounted on a rim and provided with an annular carcass having two annular beads and supporting an annular tread. A tread belt is interposed between the carcass and the tread, and the tread belt comprises a plurality of tread plies. Within the carcass ply, an airtight inner liner is provided, which constitutes an inner liner layer and has the function of retaining air within the pneumatic tire so as to maintain the inflation pressure of the pneumatic tire itself for a period of time. A ring of sound-absorbing material 2 (usually sponge) is attached to the inner cavity of the pneumatic tire 1 (i.e., in contact with the inner surface of the pneumatic tire 1 including the inner liner) to reduce the noise generated by the pneumatic tire rolling on the road surface.

[0021] The sound absorbing material 2 is applied to the already vulcanized pneumatic tire 1 (because the sound absorbing material 2 cannot withstand the combination of heat and pressure applied during the vulcanization process without being damaged), and is glued to the inner surface of the pneumatic tire 1 (including the inner liner) particularly at the tread (i.e., corresponding to the area of the pneumatic tire in contact with the asphalt) and also (but not necessarily) at part of the sidewall.

[0022] exist Figure 2 In the drawing, reference numeral 3 denotes as a whole an application unit suitable for applying a sound absorbing material 2 having an annular form to the inner cavity of a pneumatic tire 1. The application unit 3 comprises a separation station S1 (in which the excess end 5 (in Figure 4 and Figure 5 ) separated from the strip 4 of sound absorbing material 2 ) and a joining station S2 where the strip 4 of sound absorbing material 2 (with the end 5 removed) is applied to the inner cavity of the pneumatic tire 1 .

[0023] In particular, depending on the inner circumference of the inner cavity of the pneumatic tire 1, the strip 4 of the sound absorbing material 2 initially has a standard length that is greater than the required length, and therefore it is initially necessary to cut the strip 4 of the sound absorbing material 2 to an appropriate size and remove the excess end 5 from the strip 4 of the sound absorbing material 2 in such a manner as to give the strip 4 of the sound absorbing material 2 the required length (calculated as a function of the inner circumference of the pneumatic tire 1).

[0024] like Figure 3 、 Figure 4 and Figure 5 As shown, one side of the strip 4 of sound absorbing material 2 is provided with an adhesive layer 6 intended to attach the sound absorbing material 2 to the inner surface of the pneumatic tire and is covered by a protective liner 7 (i.e., having a strip of plastic material removably adhered to the adhesive layer 6). That is, the adhesive layer 6 is applied to the surface of the sound absorbing material 2 intended to come into contact with the inner cavity of the pneumatic tire 1 and initially covered (protected) with the removable protective liner 7, which serves both to protect the adhesive layer 6 and to allow the strip 4 of sound absorbing material 2 to be wound into a roll without the sound absorbing material 2 sticking to itself.

[0025] As previously described, initially, in the separation station S1, the strip 4 of the sound absorbing material 2 is cut to separate the excess end portion 5 in such a manner as to give the strip 4 of the sound absorbing material 2 a desired length (in order to implement one turn of the sound absorbing material 2 within the pneumatic tire 1 without overlapping); normally, the strip 4 of the sound absorbing material 2 initially has a length only slightly greater than the desired length, and therefore, cutting the strip 4 of the sound absorbing material 2 to size involves only a small piece of the sound absorbing material 2 being wasted (i.e., the size of the excess end portion 5 is small, typically ranging from a few centimeters to several tens of centimeters).

[0026] like Figure 5As shown, a separation opening 8 is formed by means of the strip 4 of the sound-absorbing material 2, which starts from the opposite side of the protective lining 7, ends at the protective lining 7 which remains intact, and separates the excess end 5 from the rest of the strip 4 of the sound-absorbing material 2; in other words, the separation opening 8 involves the entire depth of the sound-absorbing material 2, separates the excess end 5 from the rest of the strip 4 of the sound-absorbing material 2, and the separation opening 8 does not involve the protective lining 7 which remains intact, and the protective lining 7 constitutes a residual connection between the excess end 5 and the rest of the strip 4 of the sound-absorbing material 2.

[0027] like Figure 3 、 Figure 4 and Figure 5 As shown, the implementation of the separation opening 8 foresees cutting the strip 4 of the sound absorbing material 2 starting from the opposite side of the protective lining 7, leaving a residual portion 9 of the sound absorbing material 2 intact near the protective lining 7 (at Figure 4 then, by making the excess end portion 5 relative to the rest of the strip 4 of sound absorbing material 2 bend the remaining portion 9 of the sound absorbing material 2 ruptures, so as to complete the separation opening 8 (as Figure 5 shown).

[0028] According to a preferred embodiment, the remaining portion 9 of the sound-absorbing material 2 is cooled to allow it to break cleanly by bending. That is, in order to break the remaining portion 9 of the sound-absorbing material 2 by bending, the remaining portion 9 must be sufficiently brittle, i.e., not elastic enough. To achieve sufficient brittleness, the remaining portion 9 is cooled to a (suitable) brittle state by cooling the sound-absorbing material 2 to a temperature close to its glass transition temperature (determined according to ISO 11357-2). Therefore, the remaining portion 9 of the sound-absorbing material 2 is cooled to a temperature no higher than 10°C relative to the glass transition temperature (determined according to ISO 11357-2) of the sound-absorbing material 2, and preferably to a temperature 5°C lower than the glass transition temperature (determined according to ISO 11357-2). Cooling of the sound-absorbing material 2 can be performed by blowing low-temperature refrigerant gas 10 toward the remaining portion 9, immersing the sound-absorbing material 2 in a refrigerant liquid (bathroom), or placing the sound-absorbing material 2 in (or allowing it to pass through) a cooling chamber with open ends. The operating temperature of the cooling system depends on the glass transition temperature of the sound absorbing material 2 (determined according to ISO 11357-2 standard) and must be such as to impart sufficient brittleness to the sound absorbing material 2 constituting the residual portion 9 to cause it to break when bent.

[0029] According to a different embodiment (not shown), the separation opening 8 is not partially implemented by mechanical cutting (i.e., using a sharp instrument) and partially by breaking it when bent, but is completely implemented by laser cutting. In fact, simple mechanical cutting (i.e., using a sharp instrument) may not provide sufficient precision to completely cut the sound-absorbing material 2 while leaving the protective lining 7 intact, while laser cutting can ensure such sufficient precision (also because the laser can etch the sound-absorbing material 2 in a better way and the protective lining 7 in a worse way). As an alternative to laser cutting, water jet cutting can be used (which can etch the sound-absorbing material 2 in a better way and the protective lining 7 in a worse way), or ultrasonic cutting can be used (which can etch the sound-absorbing material 2 in a better way and the protective lining 7 in a worse way).

[0030] The separation station S1 comprises a support plane 11 having a portion 12 and a portion 13, the strip 4 of the sound-absorbing material 2 resting on the portion 12, the excess end 5 resting on the portion 13 and the portion 13 being hinged to the portion 12 so as to be movable relative to the portion 12 about an axis of rotation 14 arranged at the separation opening 8 ( Figure 3 According to a preferred embodiment, the portion 13 of the support plane 11 is rotated by means of an elastic element 15 (e.g. a coil spring, Figure 4 ) is maintained parallel to the portion 12 of the support plane 11; the separation station S1 comprises a pusher 16 (driven by an actuator device 17) which, by pressing against the excess end 5, causes the portion 13 of the support plane 11 to rotate relative to the portion 12 of the support plane 11 about the axis of rotation 14, in such a way as to bend the strip 4 of sound-absorbing material 2 and thereby determine the brittle fracture of the residual portion 9.

[0031] At the axis of rotation 14 (i.e. at the boundary between the two parts 12 and 13 of the support plane 11 where the separation opening 8 is located), a nozzle 18 is arranged facing the support plane 11, connected to a container containing the cryogen gas 10 and suitable for emitting a jet of cryogen gas 10, the jet (mainly) impacting the residual part 9, so as to freeze the residual part 9 and thus make it brittle.

[0032] According to a preferred embodiment, the pusher 16 initially pushes the excess end portion 5 to rotate it, moving it away from the rest of the strip 4 of the sound-absorbing material 2 in a manner that widens the separation opening 8, thereby exposing the residual portion 9 to the nozzle 18. At this point, the pusher 16 is temporarily stopped, and the nozzle 18 emits a jet of refrigerant gas 10, which (primarily) impacts the residual portion 9 (now well exposed to the nozzle 18). Only when the jet of refrigerant gas 10 ends does the pusher 16 resume its movement to further rotate the excess end portion 5, thereby ensuring the brittle fracture of the already frozen residual portion 9. By way of example, the pusher 16 can initially rotate the excess end portion 5 by 20° to 40° to expose the residual portion 9 to the nozzle 18; subsequently, the pusher 16 can rotate the excess end portion 5 until the excess end portion 5 reaches 60° to 90°, thereby causing the brittle fracture of the already frozen residual portion 9.

[0033] In other words, initially, in the separation station S1, the excess end portion 5 is bent relative to the remaining portion of the strip 4 of the sound-absorbing material 2 until the excess end portion 5 reaches a first bending angle (e.g., equal to 20° to 40°), thereby widening the separation opening 8 and blowing the low-temperature refrigerant gas 10 toward the residual portion 9. Finally, the excess end portion 5 is further bent relative to the remaining portion of the strip 4 of the sound-absorbing material 2 until the excess end portion 5 reaches a second bending angle (e.g., equal to 60° to 90°) that is larger than the first bending angle, so as to break the residual portion 9.

[0034] like Figure 3 and Figure 4 As shown, the separation station S1 comprises a sharp instrument 19 (eg a rotating circular blade) for carrying out an initial portion of the separation opening 8 by means of mechanical cutting, or for cutting the strip 4 of the sound-absorbing material 2 until the residual portion 9 is reached.

[0035] like Figure 2 As shown, once the strip 4 of sound-absorbing material 2 has completed the processing cycle of the strip 4 in the separation station S1 (i.e. when the separation opening 8 separating the excess end 5 from the rest of the strip 4 of sound-absorbing material 2 has been completed, leaving the protective lining 7 intact), the strip 4 of sound-absorbing material 2 is wound onto itself so as to form a roll (the roll terminating externally at the excess end 5) and then transferred (in a substantially automatic manner) to the joining station S2.

[0036] The coupling station S2 comprises a support device suitable for supporting and rotating the pneumatic tire 1 around its central axis. In particular, the support device 20 comprises motorized rollers on which the pneumatic tire 1 rests and side rails (not shown) that accommodate the pneumatic tire 1, preventing the pneumatic tire 1 from performing any form of lateral translation during its rotational movement.

[0037] The joining station S2 comprises an application device 21 adapted to apply the strip 4 of sound-absorbing material 2 to the inner surface of the pneumatic tire 1, gradually removing the protective liner 7. That is, as the strip 4 of sound-absorbing material 2 is applied to the inner cavity of the pneumatic tire 1, the application device 21 gradually separates the protective liner 7 from the strip 4 of sound-absorbing material 2; in particular, the application device 21 initially pulls the excess end 5 relative to the rest of the strip 4 of sound-absorbing material 2, in such a way as to separate the protective liner 7 from the strip 4 of sound-absorbing material 2, i.e., the application device 21 uses the excess end 5 as a gripping point in order to begin separating the protective liner 7 from the strip 4 of sound-absorbing material 2.

[0038] The coupling station S2 comprises a mobile device 22 which supports the application device 21 and is adapted to move the application device 21 between a loading / unloading position in which the application device 21 is separated from the pneumatic tire 1 (i.e., outside the pneumatic tire 1) and a working position in which the application device 21 is located inside the pneumatic tire 1 (i.e., Figure 2 In the loading / unloading position, a new strip 4 of sound absorbing material 2 wound into a roll is loaded into the application device 21, with only the protective lining 7 of the previously applied strip 4 of sound absorbing material 2 being unloaded (removed) from the application device 21. Conversely, in the working position ( Figure 2 ), a new strip 4 of sound absorbing material 2 inserted into the application device 21 is applied to the inner cavity of the pneumatic tire 1.

[0039] according to Figures 6-10 As shown, the application device 21 includes: a housing 23 adapted to accommodate the strip 4 of sound-absorbing material 2 wound into a roll; an application roller 24 mounted to rotate about a rotation axis 25 and adapted to press the strip 4 of sound-absorbing material 2 against the inner surface of the pneumatic tire 1 so as to adhere the strip 4 of sound-absorbing material 2 to the inner surface of the pneumatic tire 1; and a recovery roller 26 mounted to rotate about a rotation axis 27 parallel to the rotation axis 25 and adapted to gradually wind up the protective liner 7 so that the protective liner 7 is separated from the strip 4 of sound-absorbing material 2. In particular, the housing 23 is arranged above the application roller 24 and above the recovery roller 26. In other words, the applying device 21 includes: an applying roller 24, which is configured to press the sound absorbing material 2 against the inner surface of the pneumatic tire 1 after the protective liner 7 is removed immediately before the sound absorbing material 2 is pressed against the inner surface of the pneumatic tire 1; and further, the applying device 21 includes a protective liner recovery drum 26, on which the protective liner 7 is wound after being separated from the sound absorbing material 2, that is, after completing its function.

[0040] During application of the sound absorbing material 2, preferably just before application of the sound absorbing material 2, the protective liner 7 is separated from the sound absorbing material 2 in such a way that the adhesive layer 6 is exposed to the air for as short a time as possible in order to prevent foreign matter (debris, dust, dirt, insects, etc.) from accidentally adhering to the adhesive layer.

[0041] The application roller 24 and the recovery drum 26 are provided with actuating means adapted to rotate the application roller 24 and the recovery drum 26 about their respective rotation axes 25 and 27 at an appropriate and synchronous speed in such a way as to prevent the protective lining 7 and / or the sound absorbing material 2 from tearing due to excessive tension or too much looseness.

[0042] The recovery drum 26 is provided with a motorized gripping member 28 (e.g. a gripper provided with two opposing jaws) adapted to grip the excess end 5 of the strip 4 of sound-absorbing material 2 wound into a roll and located in the housing 23; i.e. the recovery drum 26 supports the motorized gripping member 28 adapted to grip the excess end 5 of the strip 4 of sound-absorbing material 2.

[0043] The recovery drum 26 is movably mounted in the application device 21 so as to move itself to different positions ( Figures 6-10 ); that is, in addition to being mounted so as to rotate about a central axis of rotation 27 for self-rotation, the recovery roller 26 is pivotally mounted so as to rotate about another axis of rotation 29 that is parallel and eccentric (i.e., non-coaxial) with respect to the axes of rotation 25 and 27 (i.e., with respect to the application roller 24 and the recovery roller 26). In particular, an actuator device 30 is provided as will be explained below, which moves the recovery roller 26 by causing it to rotate about the axis of rotation 29 (i.e., causing the recovery roller 26 to complete a circular path).

[0044] The application device 21 comprises a pressure roller 31 adapted to press the strip 4 of sound-absorbing material 2 against the application roller 24 and idlingly mounted at one end of an arm articulated to rotate about a rotation axis 32 (parallel to the rotation axes 25, 27 and 29) under the control of an actuator device 33. During rotation about the rotation axis 32, the pressure roller 31 can be moved in a passive position ( Figure 6 and Figure 7 ) and the active position ( Figure 8 、 Figure 9 and Figure 10 ), in the negative position, the pressure roller 31 is at a certain distance from the application roller 24 and the strip 4 of the sound absorbing material 2, and in the positive position, the pressure roller 31 presses the strip 4 of the sound absorbing material 2 against the application roller 24.

[0045] With the application device 21 in the loading / unloading position (i.e., outside the pneumatic tire 1), the strip 4 of the sound absorbing material 2 is inserted and rolled into the housing 23 of the application device 21, with the excess end 5 arranged outside the housing 23 and facing downward. Subsequently, the motorized gripping member 28 of the recovery drum 26 grasps the excess end 5, thereby integrating the excess end 5 with the recovery drum 26; during this step, the recovery drum 26 is arranged in the initial position ( Figure 6 ), in the initial position, the recovery roller 26 is configured to the left side of the application roller 24 (ie, the first side of the application roller 24) and faces the outlet of the housing 23.

[0046] Subsequently, the actuator device 30 moves the recovery roller 26 holding the excess end 5 from the initial position ( Figure 6 ) moves to the middle position ( Figure 7 ) (shown in the middle position, the recovery roller 26 is arranged to the right side of the application roller 24 (i.e., the second side of the application roller 24 opposite to the first side)), so that the strip 4 of the sound absorbing material 2 is partially wound around the application roller 24. In other words, the actuator device 30 moves the recovery roller 26 holding the excess end 5 from the first side of the application roller 24 to the second side of the application roller 24 opposite to the first side, so that the strip 4 of the sound absorbing material 2 is partially wound around the application roller 24.

[0047] Then and as Figure 8 As shown, the actuator device 33 moves the pressure roller 31 from the passive position ( Figure 7 ) moves to the active position ( Figure 8 ), so that the strip 4 of sound absorbing material 2 is pressed against the application roller 24.

[0048] Then and as Figure 9 As shown, the actuator device 30 moves the recovery roller 26 holding the excess end 5 from the middle position ( Figure 7 and Figure 8 ) moves to the final position ( Figure 9 ) (shown in FIG) (in the final position, the recovery roller 26 is arranged to the left side of the application roller 24 (i.e., the first side of the application roller 24)), so as to separate the portion of the protective liner 7 from the strip 4 of the sound absorbing material 2. In other words, the actuator device 30 moves the recovery roller 26 holding the excess end 5 from the second side of the application roller 24 to the first side of the application roller 24, so as to separate the portion of the protective liner 7 from the strip 4 of the sound absorbing material 2. When the recovery roller 26 is moved from the middle position ( Figure 7 and Figure 8 ) moves to a final position (shown in FIG) on the first side of the application roller 24 Figure 9 and Figure 10), the protective liner 7 is partially wound around the recovery drum 26.

[0049] Thus, the application device 21 is suitable for pulling the excess end 5 relative to the rest of the strip 4 of sound-absorbing material 2 , in such a way as to separate the protective lining 7 from the strip 4 of sound-absorbing material 2 .

[0050] In particular, the final position of the recovery drum 26 ( Figure 9 ) is different from the initial position of the recovery drum 26 ( Figure 7 ), that is, when the recovery roller 26 moves from the second side of the application roller 24 to the first side of the application roller 24 and then is configured in the final position ( Figure 9 ), the final position is different from the initial position ( Figure 6 ).

[0051] It should be noted that before the application device 21 (comprising the application roller 24 and the recovery drum 26) is inserted into the pneumatic tire 1, the recovery drum 26 is moved from the middle position ( Figure 7 and Figure 8 ) moves to a final position (shown in FIG) on the first side of the application roller 24 Figure 9 and Figure 10 shown in ).

[0052] At this time and as Figure 10 As shown, the moving device 22 moves the application device 21 to a loading / unloading position ( Figure 6-Figure 9 ) and the application device 21 is located in the working position inside the pneumatic tire 1 ( Figure 2 and Figure 10 In the working position ( Figure 2 and Figure 10 ), with the pneumatic tire 1 rotated, the application roller 24 presses the strip 4 of sound absorbing material 2 against the inner cavity of the pneumatic tire 1, and simultaneously, the recovery drum 26 is rotated synchronously with the pneumatic tire 1 so as to gradually wind the protective liner 7 around the recovery drum 26 as the protective liner 7 separates from the strip 4 of sound absorbing material 2.

[0053] In other words, when the application device 21 is in its working position inside the pneumatic tire 4 , the application device 21 is configured to gradually separate the protective liner 7 from the strip 4 of sound absorbing material 2 as the strip 4 of sound absorbing material 2 is applied to the inner cavity of the pneumatic tire 1 .

[0054] According to a preferred embodiment, the pressure roller 31 is moved away from the strip 4 of the sound absorbing material 2 before the pneumatic tire 1 starts to rotate; that is, the actuator device 33 moves the pressure roller 31 from the active position ( Figure 8 、 Figure 9 and Figure 10 ) moves to the negative position ( Figure 6 and Figure 7 shown in ).

[0055] The embodiments described herein may be combined without departing from the scope of protection of the present invention.

[0056] The application unit 3 described above has many advantages.

[0057] Firstly, also with regard to the separation of the initial portion of the protective lining 7 from the sound-absorbing material 2, the above-described application unit 3 makes it possible to fully automate the processing cycle; this result is obtained due to the fact that the initial portion of the protective lining 7 can also be grasped in an automated manner by clamping the excess end 5 (of considerable dimensions and substantially disconnected from the rest of the strip 4 of sound-absorbing material 2) which can be easily grasped.

[0058] Furthermore, the above-described application unit 3 enables the entire application cycle to be made more efficient (i.e. faster and cheaper, in particular due to the possibility of full automation) and also more effective (i.e. enabling high-quality application, thus avoiding any damage to the sound-absorbing material 2).

[0059] In particular, during application inside the inner cavity of the pneumatic tire 1 , the aforementioned application unit 3 ensures that the sound absorbing material 2 does not undergo elongation or compression that could lead to cracks in the sound absorbing material 2 after several thousand kilometers of use of the pneumatic tire 1 .

[0060] List of reference numerals in the accompanying drawings

[0061] 1 pneumatic tire

[0062] 2 Sound-absorbing materials

[0063] 3 Application unit

[0064] 4 strips

[0065] 5 Excess end

[0066] 6 Adhesive layer

[0067] 7 Protective lining

[0068] 8 Separation opening

[0069] 9 Remaining parts

[0070] 10 Refrigerant gas

[0071] 11 Support plane

[0072] 12 parts

[0073] 13 parts

[0074] 14 Rotation axis

[0075] 15 elastic element

[0076] 16 Pusher

[0077] 17 Actuator device

[0078] 18 nozzles

[0079] 19 Sharp instruments

[0080] 20 motorized rollers

[0081] 21 Application device

[0082] 22 mobile devices

[0083] 23 housing

[0084] 24 Application Roller

[0085] 25 Rotation axis

[0086] 26 Recycling Roller

[0087] 27 Rotation axis

[0088] 28 Compression member

[0089] 29 Rotation axis

[0090] 30 actuator device

[0091] 31 pressure roller

[0092] 32 Rotation axis

[0093] 33 Actuator device

[0094] S1 Separation Station

[0095] S2 Connection Station

Claims

1. A method for applying a sound absorbing material (2) to the inner cavity of a pneumatic tire (1) using a strip (4) of sound absorbing material (2), one side of which is provided with an adhesive layer (6), the adhesive layer (6) being covered by a protective liner (7); the method comprising the following steps: attaching an initial portion of the protective liner (7) to a recovery drum (26); partially winding the strip (4) of sound absorbing material (2) around an application roller (24); pressing the strip (4) of sound absorbing material (2) against the inner cavity of the pneumatic tire (1) by means of the application roller (24) while the pneumatic tire (1) is rotated; as well as rotating the recovery drum (26) synchronously with the pneumatic tire (1) so as to gradually wind the protective liner (7) around the recovery drum (26) as the protective liner (7) separates from the strip (4) of sound absorbing material (2); The application method is characterized by further comprising the following steps: With the recovery drum (26) on a first side of the application roller (24), gripping an initial portion of the protective liner (7) by means of a gripping member (28) integral with the recovery drum (26); as well as The recovery roller (26) holding the initial portion is moved from a first side of the application roller (24) to a second side of the application roller (24) opposite the first side, thereby partially winding the strip (4) of sound absorbing material (2) around the application roller (24).

2. The application method according to claim 1, further comprising the following steps: pressing the strip (4) of sound-absorbing material (2) against the application roller (24) by means of a pressing roller (31); as well as The recovery roller (26) holding the initial portion is moved from the second side of the application roller (24) to the first side of the application roller (24) to separate a portion of the protective liner (7) from the strip (4) of sound absorbing material (2).

3. The application method according to claim 2, wherein: Prior to inserting the application roller (24) and the recovery drum (26) into the pneumatic tire (1), the recovery drum (26) is moved from the second side of the application roller (24) to the first side of the application roller (24).

4. The application method according to claim 2 or 3, wherein: When the recovery roller (26) is moved from the second side of the application roller (24) to the first side of the application roller (24), the protective liner (7) is partially wound onto the recovery roller (26).

5. The application method according to claim 2 or 3, wherein When the recovery roller (26) is moved from the second side of the application roller (24) to the first side of the application roller (24), the recovery roller (26) is configured in a position different from the initial position assumed for grasping the initial portion of the protective liner (7).

6. The application method according to claim 2 or 3, wherein: Before starting the rotation of the pneumatic tire (1), the pressing roller (31) is moved away from the strip (4) of sound absorbing material (2).

7. The application method according to claim 2 or 3, further comprising the following steps: implementing a separation opening (8) by means of the strip (4) of sound-absorbing material (2), said separation opening (8) starting from the opposite side of the protective lining (7) and ending at the protective lining (7) which remains intact, and said separation opening (8) separating the excess end (5) from the rest of the strip (4) of sound-absorbing material (2); as well as The excess end (5) is grasped by means of a gripping member (28) integral with the recovery drum (26) in order to attach the initial portion of the protective lining (7) to the recovery drum (26).

8. The application method according to claim 2 or 3, wherein: The recovery drum (26) is mounted for rotation about a second axis of rotation which is parallel to and eccentric to the application roller (24).

9. The application method according to claim 2 or 3, wherein: The strip (4) of sound absorbing material (2) is wound to form a roll and is located within a housing arranged above the application roller (24) and above the recovery drum (26).

10. An application unit (3) for applying a sound absorbing material (2) into the inner cavity of a pneumatic tire (1) using a strip (4) of sound absorbing material (2), one side of the strip (4) of sound absorbing material (2) being provided with an adhesive layer (6), the adhesive layer (6) being covered by a protective liner (7); the application unit (3) comprising: a recovery roller (26) adapted to catch an initial portion of the protective liner (7); an application roller (24) around which the strip (4) of sound absorbing material (2) is partially wound; a first actuator device configured to press the strip (4) of sound absorbing material (2) against the inner cavity of the pneumatic tire (1) by means of the application roller (24) while the pneumatic tire (1) is rotating; a second actuator device configured to rotate the recovery drum (26) synchronously with the pneumatic tire (1) so as to progressively wind the protective liner (7) around the recovery drum (26) as the protective liner (7) separates from the strip (4) of sound absorbing material (2); The applying unit (3) is characterized by comprising: a gripping member (28) integral with the recovery drum (26) and configured to grasp an initial portion of the protective liner (7) with the recovery drum (26) positioned on a first side of the application roller (24); as well as a third actuator device configured to move the recovery roller (26) holding the initial portion from a first side of the application roller (24) to a second side of the application roller (24) opposite the first side, thereby partially winding the strip (4) of sound absorbing material (2) around the application roller (24).

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