Methods and systems for applying sealant to the surface of the inner cavity of a pneumatic tire.

Abstract

A method and system for applying sealant to the surface (2) of the inner cavity (3) of a pneumatic tire, the method comprising: detecting the weight of the pneumatic tire (4) before and after the sealant is applied to the surface (2); calculating the difference between the amount of sealant applied to the surface (2) and a reference amount of sealant; storing the difference in short-term storage buffers (24) and long-term storage buffers (26); and determining a short-term compensation factor (K). ST ) and long-term compensation factor (K) LT ), and alternately use short-term compensation factors (K) ST ) or long-term compensation factor (K) LT To calculate the correction factor (K) EA ); and during the subsequent step of applying the sealant strip to surface (2), the correction factor (K) is used. EA (7) to actuate the applicator device.

Description

Technical Field

[0001] This invention relates to a method and system for applying a sealant to the surface of the inner cavity of a pneumatic tire. Background Technology

[0002] As is well known, a pneumatic tire comprises an annular carcass with two annular beads supporting an annular tread. A tread belt layer, comprising multiple tread plies, is inserted between the carcass and the tread. An airtight inner liner is arranged within the carcass plies, constituting the inner liner and functioning to retain air within the pneumatic tire to maintain its inflation pressure over time.

[0003] In recent years, the development of pneumatic tires has shifted towards pneumatic tires with an inner liner made of a sealant designed to seal any perforation. Typically, the sealant has a high viscosity to ensure a seal associated with any perforation and its stability within the cavity, regardless of the condition of the pneumatic tire.

[0004] The sealant is applied to the pre-cured pneumatic tire, and preferably to the inner liner of the pneumatic tire in the area that comes into contact with the road (or the area of ​​the pneumatic tire where a puncture may occur). In particular, the sealant is applied to the tread and at least partially to the sidewalls.

[0005] Typically, the treatment used to apply sealant provides the pre-cured pneumatic tire with a position on the frame that prevents any lateral translation of the pneumatic tire itself by blocking the pre-cured pneumatic tire via lateral tracks.

[0006] In response to operator commands, the sealant application process begins by inserting a sealant applicator into the inner cavity of the pneumatic tire, directly facing the surface of the cavity itself. The applicator is conveniently located via a movable arm positioned at one end of the nozzle and is designed to apply substantially uniform sealant beads to the inner surface of the cavity. Specifically, the applicator is designed to apply the sealant beads by reciprocating movement between two lateral ends of the cavity; specifically, the arm moves in a plane perpendicular to the equatorial plane of the pneumatic tire. The pneumatic tire is rotated by a support via an electric roller; the movement of the arm (continuous or alternatively stepwise) combined with the rotation of the pneumatic tire achieves sealant application, which must be as uniform as possible. In fact, sealant has a high specific gravity, and even small variations in the amount of sealant applied to the inner surface of the pneumatic tire can lead to significant variations in the tire's weight, resulting in an imbalance (i.e., eccentricity) in the total mass of the pneumatic tire. It has been observed that known and currently used application systems cannot achieve improved uniformity in the thickness of the sealant applied to the cavity surface; that is, the thickness of the sealant applied to the cavity surface may vary significantly between regions. Summary of the Invention

[0007] Therefore, the object of the present invention is to provide a method for applying a sealant to the surface of the inner cavity of a pneumatic tire, which does not have the disadvantages of the prior art and is particularly easy and inexpensive to implement.

[0008] Therefore, another object of the present invention is to provide a system for applying a sealant to the surface of the inner cavity of a pneumatic tire, which does not have the disadvantages of the prior art and is particularly easy and inexpensive to manufacture.

[0009] According to the present invention, a method and system for applying a sealant to the surface of the inner cavity of a pneumatic tire, as defined in the appended claims, are provided. Attached Figure Description

[0010] The invention will now be described with reference to the accompanying drawings, which illustrate several non-limiting exemplary embodiments, in which:

[0011] Figure 1 This is a schematic front view of a system that has been implemented for applying sealant to the surface of the inner cavity of a pneumatic tire, with some parts removed for clarity.

[0012] Figure 2 yes Figure 1 A schematic diagram of the system, in which some components have been removed for clarity; and

[0013] Figure 3 schematically shown Figure 1 The control unit of the system implements the method for applying sealant to the surface of the inner cavity of a pneumatic tire, as arranged according to the invention. Detailed Implementation

[0014] refer to Figure 1 Reference numeral 1 generally indicates a system 1 for applying sealant to the surface 2 of the inner cavity 3 of the pneumatic tire 4. It should be understood that the phrase "outline of the inner cavity 3 of the pneumatic tire 4" refers to the surface outline of the pneumatic tire 4.

[0015] An inflatable tire 4 is arranged on a frame 5, which is adapted to support the inflatable tire 4 by means of an electric roller 6 and to rotate the inflatable tire 4 about its central X-axis. The frame 5 is designed to allow the inflatable tire 4 to rotate at a substantially constant speed (and preferably between 1 m / min and 15 m / min). Preferably, the inflatable tire 4 is housed within the frame 5 in a manner that prevents any lateral translation of the inflatable tire 4 itself during rotational movement about the X-axis.

[0016] like Figure 1As shown, system 1 includes a sealant applicator device 7, which is conveniently implemented by a robot with an arm 8 that is movable and designed to apply substantially uniform sealant beads to surface 2.

[0017] The applicator device 7 is designed to apply sealant beads by reciprocating movement between the two lateral ends of the inner cavity 3; specifically, the arm 8 moves in a plane substantially orthogonal to the equatorial plane of the pneumatic tire 4. The rotation of the frame 5 about axis X and the movement of the arm 8 achieve application with helical forward movement. More specifically, the applicator device 7 is designed to apply sealant beads to the portion of the pneumatic tire 4 intended to contact the road, i.e., at the tread and at least partially at the sidewalls.

[0018] The applicator device 7 is connected to the sealant supply circuit 9, which includes a tank 10, a conduit 11, and a pumping device 12. The tank 10 is preferably made of metal and contains sealant. The conduit 11 is preferably heated and originates from the tank 10 and is hydraulically connected to the applicator device 7. The pumping device 12 extracts sealant from the tank 10 and supplies sealant to the applicator device 7 under pressure.

[0019] According to a preferred variant, the applicator device 7 is implemented by a nozzle 13 for non-contact application of a semi-fluid sealant; the nozzle 13 is preferably arranged at one axial end of the movable arm 8.

[0020] The applicator device 7 is implemented in such a way that the distance between the nozzle 18 and the surface 5 remains substantially constant. It should be emphasized that by keeping the distance between the nozzle 18 and the surface 5 substantially constant, more uniform application can be achieved in terms of the thickness and width of the beads and the precision of the sealant application area.

[0021] According to the first embodiment, a weighing station 14 is provided upstream of the frame 5. The weighing station 14 includes a plurality of load sensors 15, wherein each load sensor 15 includes a measuring device of a known type connected to a control unit 16, which in turn includes a signal processing device 17. The signal processing device 17 is configured to receive signals from the load sensors 15 indicating the weight of the pneumatic tire 4 before the application of sealant.

[0022] Upstream of frame 5 is another weighing station 18, which in turn includes a plurality of load sensors 19, each load sensor 19 including a known type of measuring device connected to control unit 16. Signal processing unit 17 is configured to receive signals from load sensors 19 indicating the weight of inflated tire 4 after sealant is applied.

[0023] According to the second embodiment, a weighing station 20 is provided corresponding to the position of the frame 5. The weighing station 20 includes a plurality of load sensors 21, wherein each load sensor 21 includes a measuring device of a known type connected to the control unit 16. The signal processing device 17 is configured to receive both signals from the load sensors 21 indicating the weight of the inflated tire 4 before the application of sealant and signals indicating the weight of the tire 4 after the application of sealant.

[0024] Therefore, in both embodiments, the signal processing device 17 calculates the amount of sealant applied based on the difference between the weight of the pneumatic tire 4 after the sealant is applied and the weight of the pneumatic tire 4 before the sealant is applied.

[0025] Data relating to the amount of sealant applied to each pneumatic tire 4 (calculated based on the difference between the weight of each pneumatic tire 4 after sealant application and the weight of the same pneumatic tire 4 before sealant application) is stored in a one-dimensional array 22 or short-term vector within a storage buffer 23 in the control unit 16. The short-term vector 22 defines the short-term storage buffer 24.

[0026] It is important to emphasize that the amount of sealant to be applied can vary depending on the reference characteristics of the pneumatic tire 4 (particularly based on its size / size). According to the first variant, a plurality of short vectors 22 are stored in a short-term storage buffer 24, wherein each short vector 22 corresponds to a different type of pneumatic tire 4, thereby allowing the application of a sealant layer processed by system 1.

[0027] According to the second preferred variant, data relating to all different types of pneumatic tires 4 to which a sealant layer can be applied by system 1 is stored in a single short-term vector 22 within a short-term storage buffer 24. Reference amounts of sealant to be applied to each different type of pneumatic tire 4 processed by system 1 are stored in control unit 16. The reference amounts of sealant to be applied to each different type of pneumatic tire 4 are preferably determined during the experimental fine-tuning step of system 1 based on reference characteristics (particularly based on size / size) of each different type of pneumatic tire 4. Preferably, the reference amounts of sealant to be applied to each different type of pneumatic tire 4 processed by system 1 are fixed and not modified during operation of system 1.

[0028] Once the type of pneumatic tire 4 to be processed is selected, the control unit 16 is configured to compare the amount of sealant applied to each pneumatic tire 4 with a corresponding reference amount. Specifically, the control unit 16 is configured to calculate the difference between the amount of sealant applied to each pneumatic tire 4 and the corresponding reference amount. This difference is stored in a short-term vector 22. Clearly, in this way, the data contained in the short-term vector 22 is independent of the reference characteristics of the pneumatic tire 4 (particularly based on size / size), and data related to different types of pneumatic tires 4 can be stored. Therefore, the control unit 16 can assess the direction / orientation of the deviation relative to the reference amount of sealant to be applied (i.e., whether there is a tendency to apply more or less sealant compared to the reference amount) and the absolute value of the deviation relative to the reference amount (i.e., how much the amount of sealant to be applied deviates from the reference amount).

[0029] Short-term vector 22 comprises a plurality of elements between 80 and 120, preferably between 95 and 105, and particularly equal to 100. Short-term vector 22 is preferably processed using FIFO (First-In, First-Out) logic.

[0030] Similarly, data relating to the amount of sealant applied to each pneumatic tire 4 (which is calculated based on the difference between the weight of each pneumatic tire 4 after the sealant is applied and the weight of the same pneumatic tire 4 before the sealant is applied) is stored in a one-dimensional array 25 or a long-term vector within the storage buffer 23. The long-term vector 25 defines the long-term storage buffer 26.

[0031] According to the first variant, a plurality of long-term vectors 25 are stored in a long-term storage buffer 26, wherein each long-term vector 22 corresponds to a different type of pneumatic tire 4, thereby allowing the application of a sealant layer processed by the system 1.

[0032] According to the second preferred variant, a single long-term vector 25 within the long storage buffer 26 is used to store data related to all different types of pneumatic tires 4 to which a sealant layer can be applied by system 1. A reference amount of sealant to be applied to each different type of pneumatic tire 4 processed by system 1 is stored in control unit 16. This reference amount of sealant to be applied to each different type of pneumatic tire 4 is preferably determined during the experimental fine-tuning step of system 1 based on reference characteristics (particularly based on size / size) of each different type of pneumatic tire 4. Preferably, the reference amount of sealant to be applied to each different type of pneumatic tire 4 processed by system 1 is fixed and not modified during operation of system 1.

[0033] Once the type of pneumatic tire 4 to be processed is selected, the control unit 16 is configured to compare the amount of sealant applied to each pneumatic tire 4 with a corresponding reference amount. Specifically, the control unit 16 is configured to calculate the difference between the amount of sealant applied to each pneumatic tire 4 and the corresponding reference amount. This difference is stored in a long-term vector 25. Clearly, in this way, the data contained in the long-term vector 25 is independent of the reference characteristics of the pneumatic tire 4 (particularly based on size / size), and data related to different types of pneumatic tires 4 can be stored. Therefore, the control unit 16 can assess the direction / orientation of the deviation relative to the reference amount of sealant to be applied (i.e., whether there is a tendency to apply more or less sealant compared to the reference amount) and the absolute value of the deviation relative to the reference amount (i.e., how much the amount of sealant to be applied deviates from the reference amount).

[0034] Long-term vector 25 comprises a plurality of cells between 450 and 500, preferably between 480 and 520, and particularly equal to 500. FIFO (First-In, First-Out) logic is preferably used to process long-term vector 25.

[0035] Finally, data relating to the amount of sealant applied to each pneumatic tire 4 (calculated based on the difference between the weight of each pneumatic tire after sealant application and the weight of the same pneumatic tire before sealant application) is stored in a one-dimensional array 27 or a history storage vector within the storage buffer 23. The history storage vector 27 defines the history storage buffer 28. The history storage buffer 28 collects production data for approximately 500,000 pneumatic tires. For each pneumatic tire 4, in addition to data relating to the amount of sealant applied, the history storage buffer 28 also stores, for example, additional production data, such as the time of year in which the production of the pneumatic tire 4 occurred, the type of nozzle 13 used to produce the pneumatic tire 4, etc.

[0036] like Figure 3 As shown, the prediction algorithm 29 is stored in the control unit 16, which in particular receives data at the input from the short-term storage buffer 24, the long-term storage buffer 26 and the history storage buffer 28.

[0037] Specifically, prediction algorithm 29 receives the following input data:

[0038] (a) The average amount of sealant stored in the short-term storage buffer 24;

[0039] (b) The direction / orientation of the amount of sealant stored in the short-term storage buffer 24 (i.e., whether there is a tendency to apply more or less sealant compared to a reference amount of sealant to be applied);

[0040] (c) The average amount of sealant stored in the long-term storage buffer 26;

[0041] (d) The direction / orientation of the amount of sealant stored in the long-term storage buffer 26 (i.e., whether more or less sealant is preferred to be applied compared to a reference amount of sealant to be applied);

[0042] (e) Production data provided by the historical storage buffer 28;

[0043] (f) The amount of time during which the applicator device 7 is not in operation (i.e., the amount of time during which the applicator device 7 remains stationary; it has been experimentally verified that the stationary nature of the sealant within the supply circuit 9 negatively affects the properties of the sealant, particularly its density);

[0044] (g) Historical data related to the sealant (the sealant may have been produced even 1 to 3 months before application and kept in the barrel; obviously, the amount of time elapsed from production to application on the pneumatic tire 4 adversely affects the characteristics of the sealant, especially its density).

[0045] Based on all the received input data, prediction algorithm 29 generates a short-term compensation factor K. ST and long-term compensation factor K LT .

[0046] Prediction algorithm 29 includes a mathematical model in which different previously processed input data are used to calculate the short-term compensation factor K. ST and long-term compensation factor K LT .

[0047] Short-term compensation factor K ST and long-term compensation factor K LT The following is determined:

[0048] K ST, K LT = k1*(a) + k2*(b) + ... + k7*(g)

[0049] Where (a) to (g) represent different input data and k i (where i = 1, 2, ... 7) represents the weight assigned to each input data.

[0050] weight k i It is not constant, but depends on the compensation factor being calculated, thus distinguishing the short-term compensation factor K. ST and K LTCompensation factor. In calculating the short-term compensation factor K... ST In the case of data (a) and (b) obtained from short-term storage buffer 24, a weight greater than that is assigned; conversely, in calculating the long-term compensation factor K... LT In the case of data (c) and (d) obtained from long-term storage buffer 26, a weight greater than that is assigned.

[0051] Finally, the control unit 16 includes a module 30 for calculating the compensation parameters and short-term compensation factor K received at the input from the prediction algorithm 29. ST and long-term compensation factor K LT Both of these, as well as further production data (usually indicated by REP (recipe extrusion parameter)) (such as the size of the pneumatic tire 4 being processed, the type of nozzle 13, the extrusion speed, etc.).

[0052] Based on the short-term compensation factor K provided by prediction algorithm 29 ST Or long-term compensation factor K LT Based on REP production data, calculation module 30 generates an extrusion processing correction factor K. EA .

[0053] Calculation module 30 includes a function for calculating correction factor K. EA The mathematical model. Specifically, the correction factor K. EA It has been determined as follows:

[0054] K EA =p1*K ST / K LT +p2*REP

[0055] Where K ST / K LT And REP has the meaning previously introduced, and p i (where i = 1, 2) represent the short-term compensation factor K assigned respectively. ST Or long-term compensation factor K LT Weights of REP production data. Weight p i Preferably, it is constant.

[0056] Short-term compensation factor K from prediction algorithm 29 ST and long-term compensation factor K LT They are not used simultaneously, but exclusively within the formula to determine the correction factor K. EA .

[0057] During normal production processes, a short-term compensation factor K is used in the formula. ST Determine the correction factor K EAConversely, in the case of system 1 restarting, for example, after a production shutdown period, a long-term compensation factor K is used in the formula. LT Determine the correction factor K EA .

[0058] The operation method of System 1 will be described below, which includes the following steps in sequence:

[0059] - An operator or alternatively an automated manipulator positions the pneumatic tire 4 on the support 5 and blocks the pneumatic tire 4 by means of a lateral track to prevent any lateral translation of the pneumatic tire 4 itself.

[0060] -At weighing station 18, measure the weight of pneumatic tire 4 before applying sealant;

[0061] - Insert the applicator device 7 into the inner cavity 3;

[0062] - Nozzle 13 is positioned in the initial position to begin applying sealant;

[0063] - The pneumatic tire 4 is rotated around the X-axis by the frame, while the nozzle 13 begins to apply sealant;

[0064] - During the rotation of the pneumatic tire 4 around axis X, the nozzle 13 moves in a manner that keeps the distance between the nozzle 13 and the surface 5 substantially constant in order to achieve a more uniform application to the surface 2;

[0065] -At the end of the step of applying sealant to surface 2, at weighing station 20, measure the weight of pneumatic tire 4 at the end of sealant application;

[0066] - The frame 5 stops, allowing the applicator device 7 to be withdrawn from the inner cavity 3, and the pneumatic tire 4 to be withdrawn from the frame 5;

[0067] - and the data recorded at weighing stations 18 and 20 are sent to control unit 16 to determine the correction factor K according to the method described in the foregoing discussion. EA .

[0068] The advantages of System 1, as described in the preceding discussion, are obvious.

[0069] Specifically, the correction factor K EA The determination of this allows the sealant to be applied very uniformly and constantly to surface 2, provided that variations caused by the extrusion process and the oscillations of the sealant flow within the supply circuit 9 can be taken into account.

Claims

1. A method for applying a sealant to the surface (2) of the inner cavity (3) of a pneumatic tire (4), the method comprising the steps of: While the pneumatic tire (4) is rotated about the axis (X) of the pneumatic tire (4), a strip of sealant is applied to the surface (2) of the inner cavity (3) using the applicator device (7). The method is characterized by further comprising the following steps: Measure the weight of the pneumatic tire (4) before the sealant is applied to the surface (2); Measure the weight of the pneumatic tire (4) after the sealant is applied to the surface (2); The amount of sealant applied to the surface (2) is calculated based on the difference between the weight of the pneumatic tire (4) after the sealant is applied to the surface (2) and the weight of the pneumatic tire (4) before the sealant is applied to the surface (2). Calculate the difference between the amount of sealant applied to the surface (2) and a reference amount of sealant to be applied to the surface (2), the reference amount varying depending on the type of pneumatic tire; The difference is stored in a short-term storage buffer (24) and a long-term storage buffer (26), wherein the long-term storage buffer (26) has a greater number of cells than the short-term storage buffer (24); The short-term compensation factor (K) is determined based on both the short-term storage buffer (24) and the long-term storage buffer (26). ST ) and long-term compensation factor (K) LT ); Alternately use the aforementioned short-term compensation factor (K) ST ) or the long-term compensation factor (K) LT To calculate the correction factor (K) EA ); During the subsequent step of applying the sealant strip to the surface (2), the correction factor (K) is used. EA (7) to actuate the applicator device.

2. The method according to claim 1, wherein, According to the short-term compensation factor (K) ST ) or the long-term compensation factor (K) LT The correction factor (K) is calculated using multiple production data (REP). EA The production data includes the dimensions of the pneumatic tire (4) being processed, the type of nozzle (13) of the applicator device (7), and the extrusion speed.

3. The method according to claim 1 or 2, further comprising the following step: The difference is stored in a history storage buffer (28), which collects production data of approximately 500,000 pneumatic tires (4); The short-term compensation factor (K) is determined based on the historical storage buffer (28). ST ) and the long-term compensation factor (K) LT ).

4. The method according to claim 1 or 2, wherein, The short-term storage buffer (24) is defined by a first vector (22) having multiple cells between 80 and 120 and is processed using FIFO logic, i.e., first-in-first-out logic.

5. The method according to claim 4, wherein the first vector (22) has a plurality of units between 95 and 105.

6. The method according to claim 5, wherein the first vector (22) has a plurality of units equal to 100.

7. The method according to claim 1 or 2, wherein, The long-term storage buffer (26) is defined by a second vector (25) having multiple units between 450 and 550 and is processed using FIFO logic, i.e., first-in-first-out logic.

8. The method according to claim 7, wherein, The second vector (25) has multiple units between 480 and 520.

9. The method according to claim 8, wherein, The second vector (25) has multiple units equal to 500.

10. The method according to claim 1 or 2, further comprising the step of: Based on multiple input data ((a) to (g)) obtained from the short-term storage buffer (24) and the long-term storage buffer (26), and multiple weights (k) assigned to the input data. i The short-term compensation factor (K) is determined using a mathematical model. ST ) and the long-term compensation factor (K) LT ), where the weight (k) i The factor is not constant, but rather depends on the short-term compensation factor (K) calculated in the forward calculation. ST ) / Long-term compensation factor (K) LT And change.

11. The method according to claim 10, wherein, The input data ((a) to (g)) includes the average amount of sealant stored in the short-term storage buffer (24) and the long-term storage buffer (26), and the trend of applying more or less sealant compared to that in the short-term storage buffer (24) and the long-term storage buffer (26).

12. The method according to claim 10, wherein, The input data ((a) to (g)) includes production data provided by the history storage buffer (28).

13. The method according to claim 10, wherein, The input data ((a) to (g)) includes the duration of time during which the applicator device (7) is not in operation.

14. The method of claim 10, wherein, The input data ((a) to (g)) includes historical data related to the sealant.

15. A system (1) for implementing a method for applying a sealant to the surface (2) of the cavity (3) of a pneumatic tire (4) according to any one of claims 1 to 14.

16. The system of claim 15, further comprising a control unit (16) connected to the applicator device (7) and configured to adjust according to the correction factor (K). EA (7) to actuate the applicator device.

17. The system of claim 16, comprising: A weighing station (14) connected to the control unit (16) and configured to send a signal indicating the weight of the pneumatic tire (4) before the application of sealant; as well as A weighing station (18) connected to the control unit (16) and configured to send a signal indicating the weight of the pneumatic tire (4) after the application of sealant.

18. The system of claim 16, comprising: A weighing station (20) is connected to the control unit (16) and configured to send signals indicating the weight of the pneumatic tire (4) before the application of sealant and signals indicating the weight of the pneumatic tire (4) after the application of sealant.

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