The present invention relates to a method of producing a tire equipped with an electronic device (in particular a transponder).
In recent years, so-called “smart” tires have emerged, which are capable of forming an active part of modern vehicles, supplying information concerning the type of tires mounted, information concerning the status of the tires and also information concerning environmental conditions.
A “smart” tire is normally equipped with a transponder (that is, an electronic device suitable for communicating in radio frequency) which permits remote communication (that is, to both the vehicle whereupon the tire is mounted and to an operator who must carry out the checking or the replacement of the tire) of the identification, the characteristics and the history of the tire.
Recently, the integration has been proposed of RFID (“Radio-Frequency IDentification”) technology, based upon the presence of transponders, and TPMS (“Tire Pressure Monitoring Systems”) technology, which measures the effective inflation pressure in order to store within transponders the effective inflation pressure and then remotely communicate the effective inflation pressure by means of the transponders themselves.
Generally, a transponder intended to be coupled to a tire is inserted beforehand into a rubber support (housing) that completely surrounds the transponder on all sides. Subsequently, in order to couple a transponder to a tire, it is possible to attach the transponder to an inner surface of the tire (typically above the innerliner that ensures the air tightness of the tire) or else it is possible to integrate the transponder inside the components that make up the tire structure (i.e., arrange the transponder in the middle of the various layers that make up the tire). Attaching the transponder to an inner surface of the tire does not change the structure of the tire in any way concerning the presence of foreign bodies and therefore ensures that the tire may offer the expected performance. A transponder may be attached to the inner surface of the tire when the tire is still green (i.e., before vulcanizing the tire) or when the tire has already been vulcanized.
During the vulcanization, a layer of lubricant is generally applied which has the function of facilitating the detachment of the tire from the vulcanization mould at the end of the vulcanization process; in particular, the lubricant is interposed between an inner surface of the tire and an inner membrane (expansion bladder) of the vulcanization mould. Consequently, at the end of the vulcanization process, the inner surface of the vulcanized tire has a layer of lubricant which must be locally removed (for example by cleaning with a laser beam) in the area where the transponder is applied (otherwise the transponder may not be able to adhere with adequate force to the tire surface). Consequently, attaching the transponder to the inner surface of the tire when the tire has already been vulcanized requires additional processing (cleaning the area where the transponder is applied) which increases production times and costs. Alternatively, the inner membrane (expansion bladder) of the mould may consist of particular materials, preferably silicone, which contribute to the detachment of the tire without using any additional lubricant (release material); however, in the current state of technology, such inner membranes which do not require lubricant are expensive and of limited life.
In addition, to ensure adequate adhesion of the transponder to the surface of the vulcanized tire, it is necessary to use an adhesive (glue) that is sufficiently strong and compatible with the rubber compound that makes up the tire innerliner, and that does not in any way damage the integrity of the tire innerliner; this adhesive constitutes an additional cost in economic and environmental terms.
It would therefore be preferable, in order to reduce production times and costs, to attach the transponder to the inner surface of the tire when the tire is still green (i.e., before vulcanizing the tire). It has, however, been observed that the high pressure and high temperature reached during the vulcanization process may cause parts of the transponder to emerge outside the rubber support thereof (the so-called “surfacing” phenomenon), often causing a malfunction (if not the complete failure) of the transponder. In addition, the high pressure and high temperature reached during the vulcanization process may bring parts of the transponder into contact with the carcass cords, thereby often causing a malfunction (if not complete failure) of the transponder and as a further consequence, this may negatively interfere with the operation of the carcass cords. Finally, the high pressure and high temperature that are reached during the vulcanization process may cause irregularities in the innerliner (particularly at the edge of the rubber support of the transponder) that in the long run may cause cracks in the innerliner, to the detriment of retention of the air inside the tire with consequent pressure losses.
The purpose of the present invention is to provide a production method for a tire equipped with an electronic device that avoids damage to the tire and to the electronic device and that is at the same time easy and economical to implement.
According to the present invention, a production method for a tire equipped with an electronic device is provided as set forth in the appended claims.
The claims describe preferred embodiments of the present invention that form an integral part of the present description.
The present invention will now be described with reference to the attached drawings, which illustrate an exemplary, non-limiting embodiment, wherein:
In
The tire 1 is provided with a transponder 7 (shown in
As illustrated in
Each component 9 or 10 may have a monolayer structure (i.e., it may consist of a single type of material forming a single homogeneous layer) or it may have a multilayer structure (i.e., it may consist of two or more superimposed materials that form two or more layers).
The inner component 9 has a connection surface S, which faces the innerliner 6 of the tire 1 (i.e., it will be in direct contact with the innerliner 6 of the tire 1) and is therefore arranged on the opposite side of the transponder 7. That is, the inner component 9 has a connection surface S which will be in direct contact with the innerliner 6 of the tire 1 and is arranged on the opposite side of the transponder 7 and a surface opposite the connection surface S on which the transponder 7 rests.
The construction of the tire 1 includes forming (in a fully known manner) the green tire 1 and then (when the tire 1 is still green) applying a protective label 11 to a portion of the innerliner 6 (illustrated in
Preferably, the protective label 11 is made of polyethylene terephthalate (also known commercially by the name of Mylar). Furthermore, the protective label 11 is preferably larger than the support 8 containing the transponder 7 in such a way as to be able to “compensate” with its larger size for the positioning tolerances (i.e., errors) (both in the positioning of the label 11, and in the positioning of the support 8 containing the transponder 7).
The applicator device 12 is moved by a robotic arm 13 (or by a similar handling device), i.e., the applicator device 12 is mounted at one end of the robotic arm 13. Preferably, the applicator device 12 comprises a frame 14 which is rigidly constrained to the robotic arm 13 and supports both an application head 15 which is configured to pick up the protective label 11 and transfer the protective label 11 to the innerliner 6 of the green tire 1, and a camera 16 which frames the space in front of the application head 15 and is used for guiding the movements of the robotic arm 13.
Subsequently and as illustrated in
Subsequently and as illustrated in
At the end of the vulcanization process and as illustrated in
The removal device 21 is moved by a robotic arm 22 (or by a similar handling device), i.e., the removal device 21 is mounted at one end of the robotic arm 22. Preferably, the removal device 21 comprises a frame 23 which is rigidly constrained to the robotic arm 22 and supports both a pick-up head 24 which is configured to remove the protective label 11 from the innerliner 6 of the vulcanized tire 1, and a camera 25 which frames the space in front of the pick-up head 24 and is used for guiding the movements of the robotic arm 22.
As illustrated in
The applicator device 26 is moved by the robotic arm 22 (or by a similar handling device), i.e., the applicator device 26 is mounted at one end of the robotic arm 22. Preferably, the applicator device 26 comprises a frame 27 which is rigidly constrained to the robotic arm 22 and supports both an application head 28 which is configured to pick up the support 8 and transfer the support 8 to the innerliner 6 of the vulcanized tire 1, and a camera 29 which frames the space in front of the application head 28 and is used for guiding the movements of the robotic arm 22.
According to a possible embodiment, the same robotic arm 22 first moves the removal device 21 to remove the protective label 11 from the innerliner 6 of the vulcanized tire 1 and immediately afterwards exchanges the removal device 21 with the applicator device 26 (i.e., releases the removal device 21 and then withdraws the applicator device 26) to apply the support 8 to the innerliner 6 of the vulcanized tire 1. According to an alternative embodiment, two different robotic arms 22 are provided to move the removal device 21 and the applicator device 26 completely independently. According to a further embodiment illustrated in
The support 8 containing the transponder 7 is applied on the innerliner 6 of the vulcanized tire 1 after the tire 1 has been extracted from the vulcanization mould 20 and when a surface temperature of the innerliner 6 deriving from the heating of the vulcanization process is higher than 90° C. (preferably 100-110° C.). In other words, the support 8 containing the electronic device 7 is applied to the innerliner 6 after a certain latency time from the instant in which the vulcanized tire 1 has been extracted from the vulcanization mould 20 and in any case when the tire 1 is still (sufficiently) hot due to the heating applied during the vulcanization process; this latency time must not be too long (to prevent the surface temperature of the innerliner 6 deriving from the heating of the vulcanization process from being too low, i.e., lower than 90° C.).
According to a possible embodiment, the (maximum) duration of the latency time is established in advance and is therefore kept constant; according to an alternative embodiment, the surface temperature of the innerliner 6 is measured (for example with a common infrared non-contact thermometer) and therefore the (maximum) duration of the latency time is continuously variable as it depends on when the surface temperature of the innerliner 6 reaches the minimum value. In this regard, it is important to observe that the tire 1 has a high thermal capacity combined with a low thermal conductivity (rubber is a thermal insulator) and therefore the cooling of the tire 1 extracted from the vulcanization mould 20 is relatively slow and therefore it is easy to apply the support 8 containing the electronic device 7 to the innerliner 6 when the surface temperature of the innerliner 6 deriving from the heating of the vulcanization process is still sufficiently high.
The support 8 (particularly the inner component 9 of the support 8) comprises at least partially green rubber which is subjected to vulcanization (also) due to the effect of the residual heat possessed by the tire 1 after the extraction of the tire 1 from the vulcanization mould 20 (i.e., of the residual heat that remains from the heating performed during the vulcanization process); it is therefore necessary that the support 8 containing the transponder 7 is applied onto the innerliner 6 of the vulcanized tire 1 within a certain time interval from the extraction of the tire 1 from the vulcanization mould 20, i.e., when the tire 1 is still sufficiently hot due to the heat received during the vulcanization process.
As previously stated, at least the inner component 9 of the support 8 consists of at least partially green rubber or of rubber which has not yet begun or in any case has not yet completed a vulcanization process; in other words, the inner component 9 has at least partially green rubber which constitutes the connection surface S (i.e., the surface in direct contact with the innerliner 6 of the tire 1). In particular, at least the rubber which constitutes the connection surface S of the inner component 9 (and therefore which is in direct contact with the innerliner 6 of the tire 1) has a lower degree of vulcanization than the rubber of the (possible) outer component 10 which it is not in direct contact with the innerliner 6 of the tire 1; for example, the rubber of the inner component 9 is completely green and the rubber of the (possible) outer component 10 is partially vulcanized, or the rubber of both components 9 and 10 is partially vulcanized but has different degrees of vulcanization (a higher degree of vulcanization for the outer component 10 and a lower degree of vulcanization for the inner component 9).
Preferably but not necessarily, the inner component 9 is composed of completely green rubber, i.e., rubber that has never been vulcanized in any way, not even partially), or of only partially vulcanized rubber, i.e., rubber wherein the vulcanization has begun but has not been completed, i.e., rubber that is neither completely green nor completely vulcanized. Preferably but not necessarily, the outer component 10 (if present) is composed of only partially vulcanized rubber, i.e., rubber wherein the vulcanization has begun but has not been completed, i.e., rubber that is neither completely green nor completely vulcanized, or completely vulcanized rubber.
The connection surface S of the inner component 9 which is in direct contact with the innerliner 6 must ensure adhesion with the innerliner 6 and therefore must be less vulcanized (and therefore have a greater adhesion capacity) while the outer component 10 (if present) which covers the transponder 7 must guarantee the protection of the transponder and therefore must be able to have a higher degree of vulcanization (and therefore be harder and more resistant, also to the detriment of the adhesion capacity).
According to a different embodiment, it is possible to spray, before inserting the green tire 1 into the vulcanization mould 20, on the inner surface of the green tire 1 or on the inner membrane (expansion bladder) of the vulcanization mould 20, a lubricating liquid 19 which does not hinder the adhesion of the support 8 containing the transponder 7 to the innerliner 6; in this embodiment, the presence of the protective label 11 (and therefore of the applicator device 12 and of the removal device 21) is no longer necessary, since the lubricating liquid 19 does not hinder the adhesion of the support 8 containing the transponder 7 to the innerliner 6.
According to a further embodiment, the protective label 11 is not applied and the removal device 21 is replaced by a cleaning device which cleans (for example by means of a laser) the area of the innerliner 6 on which the support 8 containing the transponder 7 must then be applied.
According to a further embodiment, no lubricating liquid 19 is applied to the inner surface of the green tire 1 or to the inner membrane (expansion bladder) of the vulcanization mould 20, since the inner membrane (expansion bladder) of the vulcanization mould 20 has a low adherence surface which does not require the presence of the lubricating liquid 19; obviously in the absence of the lubricating liquid 19, the presence of the protective label 11 (and therefore of the applicator device 12 and of the removal device 21) is no longer necessary.
According to a preferred embodiment shown in
According to a possible embodiment, a surface of the contrast element 33 which comes into contact with the outside of the vulcanized tire 1 bears a (small) relief pattern 35 (an inscription and/or a logo) which indicates the presence and the position of transponder 7; preferably, the relief pattern 35 is heated to be able to better impress the relief pattern 35 on the outside (tread 4 or side) of the vulcanized tire 1. The function of the relief pattern 35 imprinted on the outside (tread 4 or side) of the vulcanized tire 1 is to indicate from the outside the position of the transponder 7.
According to a preferred, non-binding embodiment, the support 8 containing the transponder 7 is heated before applying the support 8 to the innerliner 6 of the vulcanized tire 1; more generally, at least the connection surface S of the inner component 9 of the support 8 containing the transponder 7 is heated before applying the support 8 to the innerliner 6 of the vulcanized tire 1. According to a preferred embodiment, the support 8 containing the transponder 7 (or better at least the connection surface S of the inner component 9) has, at the time of application to the innerliner 6 of the vulcanized tire 1, a temperature between 90° C. and 110° C. and preferably equal to about 100° C. According to a different embodiment, the support 8 containing the transponder 7 (or rather at least the connection surface S of the inner component 9) has, at the time of application to the innerliner 6 of the vulcanized tire 1, a temperature substantially equal (similar) to the surface temperature of the innerliner 6.
According to a possible embodiment illustrated in
To summarize what has been described above, upon the opening of the vulcanization mould 20 the vulcanization of the tire 1 is practically completed but the high vulcanization temperature and its thermal inertia lead to having sufficient thermal energy to complete the vulcanization of the support 8 containing the transponder 7 (especially if the support 8 is partially pre-vulcanized); the degree of pre-vulcanization of the support 8 is selected to guarantee the complete (or almost complete) vulcanization of the support 8 in the “dead” time which elapses from the extraction of the vulcanized tire 1 from the vulcanization mould 20 to the subsequent processing step of the vulcanized tire 1. In this way, optimal adhesion of the support 8 to the innerliner 6 of the vulcanized tire 1 is ensured without damaging the innerliner 6.
In particular, it has been observed that overall the best result is obtained if the support 8 containing the transponder 7 is applied to the innerliner 6 of the vulcanized tire 1 when the surface temperature of the innerliner 6 is (still) high enough to ensure adequate vulcanization of the support 8.
The embodiments described herein may be combined without departing from the scope of protection of the present invention.
The production method described above has many advantages.
Firstly, the production method described above is particularly simple and cost-effective to implement as it requires the execution of a few easily automatable operations and as it exploits, for the application of the support 8 containing the transponder 7, the dead times existing in the production cycle of the tire 1 in the instants following the extraction of the vulcanized tire 1 from the vulcanization mould 20.
Furthermore, the production method described above allows damage to the tire and to the transponder 7 to be prevented.
The production method described above does not require the use of any adhesive to glue the support 8 containing the transponder 7 to the innerliner 6, since only the adhesion force established between two rubber layers subjected to pressure at a certain temperature is used to have the support 8 adhere to the innerliner 6; in this way, both the cost and the environmental impact are reduced.
Finally, the production method described above ensures adequately strong and resistant adhesion of the transponder 7 to the tire 1, thereby avoiding the risk that the transponder 7 may detach itself, even partially, from the tire 1.
Number | Date | Country | Kind |
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102021000032225 | Dec 2021 | IT | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2022/087455 | 12/22/2022 | WO |