JP2022161514A - Method and apparatus for manufacturing pneumatic tire - Google Patents

Abstract

To provide a method and apparatus for manufacturing a pneumatic tire, capable of stabilizing dimensions and performance of a pneumatic tire.SOLUTION: When performing post-cure inflation on a pneumatic tire T vulcanized in a mold, an inner surface temperature of the pneumatic tire T is measured by a temperature sensor 21 while cooling an outer surface of the pneumatic tire T by an external cooling device 18 during the post-cure inflation, and a control unit 22 controls cooling capacity of the external cooling device 18 on the basis of the inner surface temperature.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a pneumatic tire manufacturing method and manufacturing apparatus that performs post-cure inflation (PCI), and more particularly, to a pneumatic tire manufacturing method and manufacturing method that makes it possible to stabilize the dimensions and performance of the pneumatic tire. It relates to manufacturing equipment.

In the manufacturing process of a pneumatic tire with a carcass layer made of organic fiber cords, the pneumatic tire is vulcanized in the mold of a vulcanizer, and then the vulcanized pneumatic tire removed from the mold is subjected to internal pressure. Post-cure inflation is generally performed in which the pneumatic tire is naturally cooled in a state of being filled with (see, for example, Patent Document 1). Pneumatic tires are still hot even immediately after vulcanization and tend to undergo dimensional changes due to heat shrinkage of the carcass cords. can be done.

Conventionally, post-cure inflation is performed in the air for a predetermined period of time. However, the tire temperature during post-cure inflation fluctuates not only due to fluctuations in the temperature in the vulcanizer, but also due to fluctuations in the operating conditions of surrounding equipment and changes in the outside air temperature depending on the season and time of day. Therefore, the time required for the dimensional variation due to the heat shrinkage of the carcass cords to become non-problematic varies from tire to tire. Therefore, if the post-cure inflation time is fixed, the tire temperature varies at the end of the post-cure inflation, which causes variations in the dimensions. In addition, when the thermal history of the tire varies due to the surrounding environment, the degree of vulcanization of the tire material varies, which causes variations in the physical properties of the product.

JP 2008-273095 A

An object of the present invention is to provide a pneumatic tire manufacturing method and manufacturing apparatus that make it possible to stabilize the dimensions and performance of a pneumatic tire.

The method for manufacturing a pneumatic tire according to the present invention for achieving the above object is a pneumatic tire that has been vulcanized in a mold and is subjected to post-cure inflation during the post-cure inflation. While cooling the outer surface, the inner surface temperature of the pneumatic tire is measured, and the cooling ability for the outer surface of the pneumatic tire is controlled based on the inner surface temperature.

Further, the pneumatic tire manufacturing apparatus of the present invention includes a pair of rim plates fitted to a pair of bead portions of the pneumatic tire, and a supply path for supplying a pressurized medium into the pneumatic tire through the rim plates. a discharge passage for discharging pressurized medium in the pneumatic tire through the rim plate; an external cooling device for cooling the outer surface of the pneumatic tire; and a temperature sensor for measuring the inner surface temperature of the pneumatic tire. and a control unit for controlling the cooling capacity of the external cooling device based on the inner surface temperature measured by the temperature sensor.

In the pneumatic tire manufacturing method of the present invention, while the outer surface of the pneumatic tire is cooled during post-cure inflation, the inner surface temperature of the pneumatic tire is measured, and the temperature of the pneumatic tire is measured based on the inner surface temperature. Since the cooling capacity for the outer surface is controlled, the range of tire temperature fluctuations at the end of post-cure inflation regardless of temperature fluctuations in the vulcanizer, operating conditions of surrounding equipment, and fluctuations in outside air temperature due to the season and time of day. can be reduced and the dimensions and performance of pneumatic tires can be stabilized. In particular, since the carcass layer is generally positioned close to the inner surface of the tire, the use of the inner surface temperature as an index for controlling the cooling capacity of the outer surface of the pneumatic tire during post-cure inflation allows the dimensional The effect of improving stability and performance stability can be enhanced.

Further, in the pneumatic tire manufacturing apparatus of the present invention, in addition to the conventional post-cure inflation device configuration, an external cooling device for cooling the outer surface of the pneumatic tire and a temperature sensor for measuring the inner surface temperature of the pneumatic tire By providing a sensor and a control unit that controls the cooling capacity of the external cooling device based on the inner surface temperature measured by the temperature sensor, it is possible to implement the above-described method for manufacturing a pneumatic tire.

In the pneumatic tire manufacturing method of the present invention, the difference between the standard cooling model previously defined for the inner surface temperature of the pneumatic tire during post-cure inflation and the measured value of the inner surface temperature measured during post-cure inflation is determined. It is preferable to calculate and control the cooling capacity so that the difference becomes small. This allows the tire temperature to reach an arbitrary temperature at the end of post-cure inflation, and optimizes the dimensions and performance of the pneumatic tire.

In order to carry out such a manufacturing method, in the pneumatic tire manufacturing apparatus of the present invention, the control unit includes a predetermined standard cooling model for the inner surface temperature of the pneumatic tire during post-cure inflation and post-cure inflation. It is preferable to calculate the difference between the inner surface temperature measured inside and the actual measured value, and control the cooling capacity of the external cooling device so that the difference becomes small.

1 is a meridional cross-sectional view showing a pneumatic tire manufacturing apparatus (post-cure inflation apparatus) according to an embodiment of the present invention; FIG. FIG. 2 is a diagram showing a control system of the pneumatic tire manufacturing apparatus of FIG. 1; 4 is a graph showing the relationship between post-cure inflation time and tire inner surface temperature in a method for manufacturing a pneumatic tire.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire manufacturing apparatus according to an embodiment of the present invention, and FIG. 2 shows its control system.

As shown in FIG. 1, this pneumatic tire manufacturing apparatus includes a pair of rim plates 1 and 2 fitted to a pair of bead portions of a pneumatic tire T arranged so that the tire central axis is in the vertical direction. , support shafts 3 and 4 for driving the rim plates 1 and 2 in the vertical direction, a supply path 5 for supplying the pressurizing medium Mi into the pneumatic tire T through the lower rim plate 1, and the upper rim plate 2. and a discharge path 6 for discharging the pressurized medium Mi in the pneumatic tire T through. The pneumatic tire T may be arranged so that its center axis is horizontal. The rim plates 1 and 2 are configured to close the hollow portion of the pneumatic tire T by fitting into the bead portions of the pneumatic tire T. As shown in FIG. The supply channel 5 and the discharge channel 6 may be formed on either side of the rim plates 1 and 2, or may be a common channel. Air is preferably used as pressurized medium Mi, but other gases or liquids can also be used.

A horizontally extending support beam 11 is provided above the pneumatic tire T supported by the rim plates 1 and 2, and a plurality of support rods 12 are provided so as to hang down from the support beam 11. there is Two annular pipes 14 are attached to the support rod 12 via brackets 13 . Each annular pipe 14 extends so as to surround the pneumatic tire T and has a plurality of air injection holes 15 on its inner peripheral side. The annular pipe 14 is connected to a cooling medium supply source 17 (see FIG. 2) through a pipe 16, and the cooling medium Mo is supplied from the air injection holes 15 toward the outer surface of the pneumatic tire T during post-cure inflation. It is designed to be sprayed. The annular pipe 14 , the air injection holes 15 , the pipe 16 and the cooling medium supply source 17 constitute an external cooling device 18 . Air is preferably used as the cooling medium Mo supplied from the cooling medium supply source 17, but other gases or liquids can also be used.

Two temperature sensors 21 for measuring the inner surface temperature of the pneumatic tire T are arranged on the upper rim plate 2 , and the inner surface temperature measured by these temperature sensors 21 is input to the controller 22 . It has become. As the temperature sensor 21, a non-contact temperature sensor typified by an infrared radiation thermometer is preferably used, but a contact temperature sensor can also be used. Also, the temperature sensor 21 is arranged to measure the inner surface temperature at two positions corresponding to both shoulder portions of the pneumatic tire T, but the measuring points of the inner surface temperature are not particularly limited. Instead, the inner surface temperature of the tread portion, sidewall portion, or bead portion can be used as an index.

As shown in FIG. 2, the control unit 22 controls the cooling capacity of the external cooling device 18 (for example, driving the cooling medium supply source 17) based on the inner surface temperature (for example, average value) measured by the two temperature sensors 21. force).

Next, a method for manufacturing the pneumatic tire T using the pneumatic tire manufacturing apparatus described above will be described. First, after vulcanizing the pneumatic tire T in a vulcanizer (not shown), the vulcanized pneumatic tire T removed from the mold of the vulcanizer is subjected to a post-cure inflation process. That is, as shown in FIG. 1, the pair of rim plates 1 and 2 are fitted to the pair of bead portions of the pneumatic tire T, and with the discharge passage 6 closed, the rim plates 1 and 2 are loaded into the pneumatic tire T from the supply passage 5. A pressure medium Mi is supplied. On the other hand, the cooling medium Mo is injected toward the outer surface of the pneumatic tire T from the air injection holes 15 of the annular pipe 14 that constitutes the cooling device 18 . Thus, the post-cure inflation for the pneumatic tire T is started.

In the post-cure inflation process, the inner surface temperature of the pneumatic tire T is measured by the temperature sensor 21 while the outer surface of the pneumatic tire T is cooled. Then, the control unit 22 controls the cooling capacity of the external cooling device 18 based on the inner surface temperature measured by the temperature sensor 21 . More specifically, when the inner surface temperature of the pneumatic tire T during post-cure inflation is within the assumed range, the cooling capacity of the external cooling device 18 is set to a standard level, but the pneumatic tire T during post-cure inflation is set to a standard level. If it is determined that the inner surface temperature of is higher than the assumed range, the cooling capacity of the external cooling device 18 is increased, and if the inner surface temperature of the pneumatic tire T during post-cure inflation is determined to be lower than the assumed range reduces the cooling capacity of the external cooling device 18 . After the post-cure inflation is performed in this manner and a preset time has elapsed, the post-cure inflation is terminated. That is, the pressurizing medium Mi in the pneumatic tire T is discharged from the discharge passage 6, and the pair of rim plates 1 and 2 are separated from the bead portions of the pneumatic tire T.

According to the pneumatic tire manufacturing method described above, the inner surface temperature of the pneumatic tire T is measured while the outer surface of the pneumatic tire T is cooled during post-cure inflation, and the pneumatic tire is measured based on the inner surface temperature. Since the cooling capacity for the outer surface of the T is controlled, the tire temperature at the end of post-cure inflation is maintained regardless of temperature fluctuations in the vulcanizer, operating conditions of surrounding equipment, and fluctuations in outside air temperature due to seasons and time zones. It is possible to reduce the fluctuation range and stabilize the dimensions and performance of the pneumatic tire. In particular, since the carcass layer is generally arranged at a position close to the inner surface of the tire, by using the inner surface temperature as an index for controlling the cooling ability for the outer surface of the pneumatic tire T in post-cure inflation, The effect of improving dimensional stability and performance stability can be enhanced.

FIG. 3 is a graph showing the relationship between the post-cure inflation time and the tire inner surface temperature in the pneumatic tire manufacturing method. In FIG. 3, A and B show test examples of pneumatic tires subjected to post-cure inflation in different environments. In Test Example B, the temperature decrease is gentler than in Test Example A.

As shown in FIG. 3, when the post-cure inflation of the tires of Test Examples A and B is completed at a constant time t1, a difference occurs in the tire temperatures of Test Examples A and B at time t1, which affects the dimensions and performance. It is a factor that causes a difference in Therefore, as described above, the inner surface temperature of the pneumatic tire T is measured while the outer surface of the pneumatic tire T is cooled during the post-cure inflation, and the cooling of the outer surface of the pneumatic tire T is performed based on the inner surface temperature. By controlling the capacity, it is possible to reduce the fluctuation width of the tire temperature at the end of the post-cure inflation. For example, by increasing the cooling capacity of the external cooling device 18 in the case of Test Example B than in the case of Test Example A, it is possible to reduce the fluctuation range of the tire temperatures of Test Examples A and B at the end of post-cure inflation. .

As a method of controlling the cooling capacity of the external cooling device 18, it is conceivable to adjust the flow rate and temperature of the cooling medium Mo or change the type of the cooling medium Mo. The flow rate of the cooling medium Mo can be changed, for example, within the range of 5.0 m ³ /min to 25.0 m ³ /min. The temperature of the cooling medium Mo can be varied, for example, within the range of 10°C to 35°C. When changing the type of the cooling medium Mo, for example, multiple types of gases with different heat capacities can be used.

In the pneumatic tire manufacturing apparatus described above, the control unit 22 controls a predetermined standard cooling model for the inner surface temperature of the pneumatic tire T during post-cure inflation and actual measurement of the inner surface temperature during post-cure inflation. It is preferable that the cooling capacity of the external cooling device 18 is controlled so that the difference from the value is calculated over time and the difference is reduced. For example, when the curve of test example A in FIG. 2 is used as a standard cooling model, when the measured value of the inner surface temperature of the pneumatic tire T is on the higher side than the standard cooling model (above the curve of test example A) The cooling capacity of the external cooling device 18 is enhanced, and the cooling capacity of the external cooling device 18 is reduced when the measured value of the inner surface temperature is lower than the standard cooling model (below the curve of test example A). As a result, the tire temperature at the end of post-cure inflation can reach an arbitrary temperature, and the dimensions and performance of the pneumatic tire T can be optimized based on the standard cooling model. Although the standard cooling model is not particularly limited, it is possible to adopt an intermediate cooling curve among cooling curves of the inner surface temperature that can be observed in one year. By adopting such a standard cooling model, control for stabilization can be easily performed.

When controlling the cooling capacity for the outer surface of the pneumatic tire T based on the inner surface temperature of the pneumatic tire T during post-cure inflation, the influence of the control of the cooling capacity for the outer surface of the pneumatic tire T is The timing reflected in the inner surface temperature of the tire T is delayed from the control timing. Therefore, during control, it is preferable to preset the extent and time for increasing or decreasing the cooling capacity according to the magnitude of the difference between the standard cooling model and the measured value of the inner surface temperature measured during the post-cure inflation. . That is, if there is a large difference between the standard cooling model and the measured value of the inner surface temperature at an arbitrary time, the extent to which the cooling capacity is increased or decreased should be increased, or the time period for which the cooling capacity is increased or decreased should be increased. Conversely, if the difference between the standard cooling model and the measured value of the inner surface temperature at any given time is small, the extent to which the cooling capacity is increased or decreased should be reduced, or the time for which the cooling capacity is increased or decreased should be shortened.

In the above-described embodiment, the case of controlling the cooling capacity of the external cooling device 18 consisting of the annular pipe 14, the air injection holes 15, the pipe 16, and the cooling medium supply source 17 has been described. The structure of the external cooling device that cools the surface is not particularly limited. In addition, while the cooling capacity of the external cooling device 18 consisting of the annular pipe 14, the air injection holes 15, the pipe 16 and the cooling medium supply source 17 is fixed, another external cooling device (for example, a spot cooler) is added, The cooling capacity of the added external cooling device may be controlled.

Further, in the above-described embodiment, in the post-cure inflation process, the inner surface temperature of the pneumatic tire T is measured while cooling the outer surface of the pneumatic tire T, and based on the inner surface temperature that changes during the post-cure inflation. In the present invention, the inner surface temperature is measured before starting the cooling of the outer surface of the pneumatic tire T, and the cooling is started. The cooling capacity for the outer surface of the pneumatic tire T may be controlled based on the previous inner surface temperature.

In manufacturing a pneumatic tire for a passenger car (tire size: 195/65R15), post-cure inflation was performed for a certain period of time, and only the cooling conditions for the outer surface of the tire were changed. The method was carried out for one year and produced 10000 pneumatic tires each.

In Conventional Example 1, the outer surface of the pneumatic tire was naturally cooled during post-cure inflation. In Conventional Example 2, the outer surface of the pneumatic tire was cooled under constant conditions during post-cure inflation. In Example 1, in post-cure inflation, the inner surface temperature of the pneumatic tire was measured while cooling the outer surface of the pneumatic tire, and the inner surface temperature measured during post-cure inflation was compared with a predetermined standard cooling model. The difference from the measured value was calculated, and the cooling capacity was controlled so that the difference would be small.

The test tires obtained by the pneumatic tire manufacturing method described above were evaluated for variations in RFV yield and steering stability by the following evaluation methods. Table 1 shows the results.

RFV Yield:
The radial force variation (RFV) of each test tire was measured, and the yield (percentage of non-defective products) was determined from the viewpoint of RFV. The evaluation results are shown as indices with Conventional Example 1 being 100. A larger index value means a better yield.

Variation in steering stability:
For each test tire, a set of four continuously manufactured tires was assembled on a wheel with a rim size of 15 x 5.5J, mounted on a test vehicle, and tested on a test course consisting of a dry road surface at an air pressure of 230 kPa. A sensory evaluation (out of 100 points) was conducted by the driver regarding the steering stability. Such sensory evaluation was performed on 50 sets of tires manufactured in different seasons and different time periods for each of Conventional Examples 1 and 2 and Example 1, and the standard deviation of the sensory evaluation scores was obtained. The evaluation results are shown as indices with Conventional Example 1 being 100. A smaller index value means less variation in steering stability.

As can be seen from Table 1, the tire obtained by the method of Example 1 had a good RFV yield and a small variation in steering stability in comparison with Conventional Examples 1 and 2. According to the method of Example 1, the dimensions and performance of the pneumatic tire could be stabilized.

Reference Signs List 1, 2 Rim plate 3, 4 Support shaft 5 Supply path 6 Discharge path 11 Support beam 12 Support rod 13 Bracket 14 Annular pipe 15 Air injection hole 16 Piping 17 Cooling medium supply source 18 External cooling device 21 Temperature sensor 22 Control section Mi Addition Pressure medium Mo Cooling medium T Pneumatic tire

Claims (4)

When post-cure inflation is performed on a pneumatic tire vulcanized in a mold, the inner surface temperature of the pneumatic tire is measured while cooling the outer surface of the pneumatic tire during the post-cure inflation. and controlling the cooling capacity for the outer surface of the pneumatic tire based on the inner surface temperature. calculating a difference between a predetermined standard cooling model for the inner surface temperature of the pneumatic tire during the post-cure inflation and the measured value of the inner surface temperature measured during the post-cure inflation, so that the difference is small; 2. The method of manufacturing a pneumatic tire according to claim 1, wherein the cooling capacity is controlled such that A pair of rim plates fitted to a pair of bead portions of a pneumatic tire, a supply path for supplying a pressurizing medium into the pneumatic tire through the rim plates, and pressurization inside the pneumatic tire through the rim plates. a discharge passage for discharging a medium; an external cooling device for cooling the outer surface of the pneumatic tire; a temperature sensor for measuring the inner surface temperature of the pneumatic tire; and a controller for controlling the cooling capacity of the external cooling device. The control unit calculates a difference between a standard cooling model defined in advance for the inner surface temperature of the pneumatic tire during the post-cure inflation and the measured value of the inner surface temperature measured during the post-cure inflation. 4. The apparatus for manufacturing a pneumatic tire according to claim 3, wherein the cooling capacity of the external cooling device is controlled so that the difference is small.

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