JP2022161513A - Method and apparatus for manufacturing pneumatic tire - Google Patents

Abstract

To provide a method and apparatus for manufacturing a pneumatic tire, capable of stabilizing quality and dimensions of a pneumatic tire.SOLUTION: When performing post-cure inflation on a pneumatic tire T vulcanized in a mold, an outer 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 outer 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 make it possible to stabilize the quality and dimensions 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 dimensions and quality.

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 quality and dimensions of pneumatic tires.

The method for manufacturing a pneumatic tire according to the present invention for achieving the above object is to perform post-cure inflation on a pneumatic tire vulcanized in a mold, during the post-cure inflation. It is characterized by measuring the outer surface temperature of the pneumatic tire while cooling the outer surface, and controlling the cooling ability for the outer surface of the pneumatic tire based on the measured outer 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 the 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 outer surface temperature of the pneumatic tire. and a control unit for controlling the cooling capacity of the external cooling device based on the outer surface temperature measured by the temperature sensor.

In the pneumatic tire manufacturing method of the present invention, the outer surface temperature of the pneumatic tire is measured while cooling the outer surface of the pneumatic tire during post-cure inflation, and the outer surface temperature of the pneumatic tire is measured based on the outer surface temperature. Because it controls the cooling capacity of the tire, the range of tire temperature fluctuations at the end of post-cure inflation is reduced 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. and stabilize the quality and dimensions of the pneumatic tire.

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 outer surface temperature of the pneumatic tire By providing a sensor and a control section that controls the cooling capacity of the external cooling device based on the outer surface temperature measured by the temperature sensor, it is possible to carry out 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 outer surface temperature of the pneumatic tire during post-cure inflation and the actual value of the outer 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 quality and dimensions 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 outer surface temperature of the pneumatic tire during post-cure inflation and post-cure inflation. It is preferable to calculate the difference between the outer 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 outer surface temperature in a pneumatic tire manufacturing method.

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.

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 it is also possible to use other gases or liquids.

Two temperature sensors 21 for measuring the outer surface temperature of the pneumatic tire T are arranged on the support rod 12 , and the outer surface temperature measured by these temperature sensors 21 is input to the controller 22 . ing. 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. The temperature sensors 21 are arranged to measure the outer surface temperature at two positions corresponding to both shoulder portions of the pneumatic tire T, but the outer surface temperature measurement points are not particularly limited. Instead, the temperature of the outer surface 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 outer 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 outer surface temperature of the pneumatic tire T is measured by the temperature sensor 21 at the same time as 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 outer surface temperature measured by the temperature sensor 21 . More specifically, when the outer 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 outer surface temperature of is higher than the assumed range, the cooling capacity of the external cooling device 18 is increased, and if it is determined that the outer surface temperature of the pneumatic tire T during post-cure inflation is 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 outer 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 outer 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 quality and dimensions of the pneumatic tire.

FIG. 3 is a graph showing the relationship between the post-cure inflation time and the tire outer 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 quality and dimensions. It is a factor that makes a difference in Therefore, as described above, the outer 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 outer 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, adjusting the flow rate and temperature of the cooling medium Mo or changing the type of the cooling medium Mo can be considered. The flow rate of the cooling medium Mo can be varied, for example, within the range of 5 cm ³ /s to 3000 cm ³ /s. 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 above-described pneumatic tire manufacturing apparatus, the control unit 22 controls a predetermined standard cooling model for the outer surface temperature of the pneumatic tire T during post-cure inflation and actual measurement of the outer 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 outer 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 increased, and the cooling capacity of the external cooling device 18 is reduced when the measured value of the outer 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 the post-cure inflation can reach an arbitrary temperature, and the quality and dimensions 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 outer surface temperature that can be observed in one year. By adopting such a standard cooling model, control for stabilization can be easily performed.

As shown in FIG. 1, when post-cure inflation is performed with the pneumatic tire T arranged so that its center axis is in the vertical direction, the warm air inside the tire tends to stay in the upper side. The temperature of the upper portion of T may be higher than the temperature of the lower portion. Therefore, two temperature sensors 21 are arranged at two positions corresponding to both shoulder portions of the pneumatic tire T, for example, and the cooling capacity of the upper external cooling device 18 is controlled based on the measured value of the upper temperature sensor 21. On the other hand, it is preferable to control the cooling capacity of the lower external cooling device 18 based on the measured value of the lower temperature sensor 21 . When the cooling capacity is controlled for each part in this way, the temperature difference in the vertical direction of the pneumatic tire T, that is, the temperature difference between the upper part and the lower part of the pneumatic tire T bordering on the tire equator can be reduced. It is possible to further improve quality stability and dimensional stability.

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.

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 tire manufacturing method was implemented, and 120 pneumatic tires were manufactured for each time slot.

In Conventional Example 1, during the day and night in July, the outer surface of the pneumatic tire was cooled under constant conditions during the post-cure inflation, and the post-cure inflation was performed for 13 minutes. In Conventional Example 2, the outer surface of the pneumatic tire was cooled under constant conditions during the post-cure inflation at day and night in December, and the post-cure inflation was performed for 13 minutes. In Example 1, during the day and night in July, the outer surface temperature of the pneumatic tire was measured while cooling the outer surface of the pneumatic tire during post-cure inflation. The cooling capacity was controlled based on the outer surface temperature to be 50°C. In Example 2, the outer surface temperature of the pneumatic tire was measured during the day and night in December while cooling the outer surface of the pneumatic tire during post-cure inflation. The cooling capacity was controlled based on the outer surface temperature to be 50°C. In Examples 1 and 2, the cooling capacity was controlled for each of the upper portion and the lower portion of the pneumatic tire.

The test tire obtained by the method for manufacturing a pneumatic tire described above was evaluated in terms of temperature difference between upper and lower ends, dimensional stability, and uniformity at the end of the test, and the results are shown in Table 1.

Upper and lower temperature difference at the end:
For each of Conventional Examples 1 and 2 and Examples 1 and 2, the temperature of the upper sidewall portion and the lower sidewall portion of the test tire was measured at the end of the post-cure inflation, and the temperature difference between the upper and lower sides was calculated and averaged. sought the value. The evaluation results are shown as indices with the average value of test tires manufactured at night in Conventional Example 2 being 100. A smaller index value means a smaller upper and lower temperature difference at the end of the test.

Dimensional stability:
The profile of each test tire was measured, and the standard deviation of the profile measurement values was obtained for each of Conventional Examples 1 and 2 and Examples 1 and 2. The evaluation results are shown as an index with the standard deviation of the test tire manufactured at night in Conventional Example 2 being 100. A smaller index value means better dimensional stability.

Uniformity:
The radial force variation (RFV) of each test tire was measured, and the standard deviation of the RFV values for each of Conventional Examples 1 and 2 and Examples 1 and 2 was obtained. The evaluation results are shown as an index with the standard deviation of the test tire manufactured at night in Conventional Example 2 being 100. A smaller index value means better uniformity.

As can be seen from Table 1, the tires obtained by the methods of Examples 1 and 2 were improved in both dimensional stability and uniformity in comparison with Conventional Examples 1 and 2.

Reference Signs List 1, 2 rim plate 3, 4 support shaft 5 supply passage 6 discharge passage 11 support beam 12 support rod 13 bracket 14 annular pipe 15 air injection hole 16 pipe 17 cooling medium supply source 18 external cooling device 21 temperature sensor 22 control unit Mi addition Pressure medium Mo Cooling medium T Pneumatic tire

Claims (4)

When performing post-cure inflation on a pneumatic tire vulcanized in a mold, measuring the outer surface temperature of the pneumatic tire while cooling the outer surface of the pneumatic tire during the post-cure inflation, A method for manufacturing a pneumatic tire, comprising controlling a cooling capacity for the outer surface of the pneumatic tire based on the temperature of the outer surface. calculating a difference between a predetermined standard cooling model for the outer surface temperature of the pneumatic tire during the post-cure inflation and the measured value of the outer surface temperature measured during the post-cure inflation, and making the difference 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 outer surface temperature of the pneumatic tire; and a controller for controlling the cooling capacity of the external cooling device. The controller calculates a difference between a standard cooling model defined in advance for the outer surface temperature of the pneumatic tire during the post-cure inflation and the measured value of the outer surface temperature measured during the post-cure inflation. 4. The apparatus for manufacturing a pneumatic tire according to claim 3, wherein the cooling capacity is controlled so that the difference between the two is small.

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