JP7488452B2 - Manufacturing method and manufacturing device for pneumatic tire - Google Patents

Description

The present invention relates to a manufacturing method and manufacturing apparatus for pneumatic tires that perform post cure inflation (PCI), and more specifically, to a manufacturing method and manufacturing apparatus for pneumatic tires that enables improved dimensional stability and quality stability.

In the manufacturing process of pneumatic tires 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 is removed from the mold and allowed to cool naturally while inflated with internal pressure (see, for example, Patent Documents 1 to 3). Pneumatic tires are still hot immediately after vulcanization and tend to change in size due to thermal shrinkage of the carcass cords, so by performing post-cure inflation, the dimensional stability and uniformity of the pneumatic tire can be improved.

Conventionally, in post-cure inflation, an annular pipe with multiple air injection holes is arranged to surround the pneumatic tire, and the pneumatic tire is cooled by blowing air from this annular pipe onto the outer surface of the pneumatic tire. Here, pneumatic tires of various different tire sizes are used in the post-cure inflation process, and when the tire size is different, the position where the air hits varies in the tire width direction depending on the tire size. If the cooling points in the pneumatic tire during post-cure inflation differ in this way, the dimensional change due to the thermal contraction of the carcass cord becomes non-uniform. Furthermore, the intermediate elongation of the band cord extending in the circumferential direction of the tire in the belt cover layer and the physical properties of the cap tread rubber layer are also likely to vary. Therefore, the difference in the position where the air hits depending on the tire size causes variation in tire dimensions, which in turn causes variation in tire quality including uniformity.

JP 2007-190808 A JP 2008-273095 A JP 2017-94613 A

The object of the present invention is to provide a method and apparatus for manufacturing pneumatic tires that allows for improved dimensional stability and quality stability.

In order to achieve the above object, the present invention provides a method for producing a pneumatic tire, comprising the steps of:
a tire width detection device that detects the width of the pneumatic tire, which is a width measured in the central axial direction of the tire, using an apparatus including a pair of rim plates that fit into a pair of bead portions of a pneumatic tire, a supply passage that supplies a pressurized medium into the pneumatic tire through the rim plates, a discharge passage that discharges the pressurized medium in the pneumatic tire through the rim plates, an annular pipe that blows air onto an outer surface of the pneumatic tire, a pipe drive device that displaces the annular pipe along the tire width direction independently of the rim plates,
The invention is characterized in that the width of the pneumatic tire is detected while the pneumatic tire is attached to the pair of rim plates and the pressurized medium is supplied into the pneumatic tire , the annular pipe is displaced along the tire width direction independently of the rim plates, and the position of the annular pipe is automatically adjusted based on the width of the pneumatic tire.

In addition, the pneumatic tire manufacturing apparatus of the present invention is characterized in that it comprises a pair of rim plates that fit into a pair of bead portions of a pneumatic tire, a supply path that supplies pressurized medium into the pneumatic tire through the rim plates, a discharge path that discharges the pressurized medium within the pneumatic tire through the rim plate, an annular pipe that blows air onto the outer surface of the pneumatic tire, a pipe drive device that displaces the annular pipe along the tire width direction independently of the rim plate, a tire width detection device that detects the width of the pneumatic tire, which is the width measured in the central axial direction of the tire , and a control unit that controls the pipe drive device based on the width of the pneumatic tire detected by the tire width detection device.

In the manufacturing method of the pneumatic tire of the present invention, the width of the pneumatic tire is detected, and the position of the annular pipe that blows air onto the outer surface of the pneumatic tire is automatically adjusted based on the width of the pneumatic tire. This makes it possible to effectively and uniformly cool the pneumatic tire regardless of the tire size, thereby suppressing dimensional changes due to thermal shrinkage of the carcass cords and improving the dimensional stability and quality stability of the pneumatic tire.

In addition to the conventional post-cure inflation device configuration, the pneumatic tire manufacturing device of the present invention is equipped with a pipe drive device that displaces the cooling ring pipe along the tire width direction, a tire width detection device that detects the width of the pneumatic tire, and a control unit that controls the pipe drive device based on the width of the pneumatic tire detected by the tire width detection device, making it possible to implement the above-mentioned pneumatic tire manufacturing method.

In the present invention, the width of the pneumatic tire can be detected by a camera or a laser sensor. In other words, a camera or a laser sensor can be used as a tire width detection device. The camera or the laser sensor can accurately detect the width of the pneumatic tire.

1 is a meridian cross-sectional view showing a pneumatic tire manufacturing apparatus (post-cure inflation apparatus) according to an embodiment of the present invention. 4A to 4C are diagrams illustrating an example of a process for producing the pneumatic tire of FIG. 1;

The configuration of the present invention will be described in detail below with reference to the attached drawings. Figure 1 shows a pneumatic tire manufacturing device according to an embodiment of the present invention.

As shown in FIG. 1, this pneumatic tire manufacturing device includes a pair of rim plates 1, 2 that fit into a pair of bead portions of a pneumatic tire T that is arranged so that the tire center axis is vertical, support shafts 3, 4 that drive the rim plates 1, 2 in the vertical direction, a supply path 5 that supplies a pressurized medium M into the pneumatic tire T through the lower rim plate 1, and a discharge path 6 that discharges the pressurized medium M from the pneumatic tire T through the upper rim plate 2. The pneumatic tire T may be arranged so that its center axis is horizontal. The rim plates 1, 2 are configured to close the cavity of the pneumatic tire T by fitting into the bead portions of the pneumatic tire T. The supply path 5 and the discharge path 6 may be formed on either side of the rim plates 1, 2, or may be a common flow path. It is preferable to use air as the pressurized medium M, but it is also possible to use other gases or liquids.

Above the pneumatic tire T supported by the rim plates 1 and 2, a support beam 11 extending in the horizontal direction is arranged, and multiple support rods 12 are arranged so as to hang down from the support beam 1. Two annular pipes 14 are attached to the support rods 12 via a pipe drive device 13. The pipe drive device 13 is composed of a pair of upper and lower rods 13a connected to the annular pipes 14 and extending in the tire width direction, and a drive unit 13b that moves the rods 13a forward and backward along their longitudinal direction, so that the annular pipes 14 are displaced along the tire width direction by the forward and backward movement of the rods 13a. Each annular pipe 14 extends to surround the pneumatic tire T and has multiple air injection holes 15 on its inner periphery. The annular pipes 14 are connected to an air supply source (not shown), and cooling air is injected from the air injection holes 15 toward the outer surface of the pneumatic tire T during post-cure inflation.

In addition, a tire width detection device 21 for detecting the width of the pneumatic tire T is disposed on one of the annular pipes 14, and the width of the pneumatic tire T detected by the tire width detection device 21 is input to the control unit 22. It is preferable to use a camera or a laser sensor as the tire width detection device 21. In the case of a camera, the width of the pneumatic tire T can be detected from a captured image. On the other hand, in the case of a laser sensor, the width of the pneumatic tire T can be detected based on the state of laser light blocking. With a camera or a laser sensor, the width of the pneumatic tire T can be accurately detected, and the output data can be used for control as is. The control unit 22 controls the pipe drive device 13 based on the width of the pneumatic tire T detected by the tire width detection device 21. It is possible to measure the width of the pneumatic tire T as a whole, but if the center position of the pipe drive device 13 and the center position of the pneumatic tire T are coincident, it is sufficient to only detect the end position in the tire width direction of the pneumatic tire T. In other words, it is possible to determine the tire width direction positions of the pair of annular pipes 14 so that they are symmetrical with respect to the center position of the pneumatic tire T based on the end position in the tire width direction of the pneumatic tire T.

Next, a method for manufacturing a pneumatic tire T using the above-mentioned pneumatic tire manufacturing apparatus will be described. First, the pneumatic tire T is vulcanized in a vulcanizer (not shown), and then 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, a pair of rim plates 1, 2 are fitted to a pair of bead portions of the pneumatic tire T, and a pressurized medium M is supplied into the pneumatic tire T from the supply path 5 with the discharge path 6 closed. Meanwhile, the width of the pneumatic tire T is detected by the tire width detection device 21, and the control unit 22 controls the pipe drive device 13 based on the width of the pneumatic tire T detected by the tire width detection device 21, and the position of the annular pipe 14 is automatically adjusted based on the width of the pneumatic tire T. For example, the position of the annular pipe 14 can be adjusted so that the air injection hole 15 of the annular pipe 14 is near the shoulder portion of the pneumatic tire T.

After adjusting the position, cooling air is sprayed from the air injection holes 15 of the annular pipe 14 toward the outer surface of the pneumatic tire T. In this way, post-cure inflation of the pneumatic tire T is started. To end the post-cure inflation, the pressurized medium M in the pneumatic tire T is discharged from the discharge passage 6, and the pair of rim plates 1, 2 are detached from the bead portion of the pneumatic tire T.

Figure 2 shows a schematic of the operation of the annular pipes. As shown in Figure 2, when performing post-cure inflation on a relatively narrow pneumatic tire T1 and a relatively wide pneumatic tire T2, a pair of annular pipes 14 is placed at position P1 for the narrow pneumatic tire T1, and a pair of annular pipes 14 is placed at position P2 for the wide pneumatic tire T2.

According to the above-mentioned method for manufacturing a pneumatic tire, the width of the pneumatic tire T is detected, and the position of the annular pipe 14 that blows air onto the outer surface of the pneumatic tire T is automatically adjusted based on the width of the pneumatic tire T. This makes it possible to effectively and uniformly cool the pneumatic tire T regardless of the tire size, thereby suppressing dimensional changes due to thermal contraction of the carcass cord and improving the dimensional stability of the pneumatic tire T. Furthermore, it is possible to suppress variations in intermediate elongation and uniformity of the band cord, improving the quality stability of the pneumatic tire T.

In manufacturing pneumatic tires for passenger cars, the tire manufacturing methods of Conventional Examples 1 and 2 and Examples 1 and 2, which differ only in the structure of the cooling annular pipe in post-cure inflation and the tire size, were carried out, and 120 pneumatic tires were manufactured for each.

In conventional example 1, the position of the cooling annular pipe is fixed, and a pneumatic tire with a tire size of 195/65R15 is used. In conventional example 2, the position of the cooling annular pipe is fixed, and a pneumatic tire with a tire size of 225/60R18 is used. In example 1, a structure is adopted in which the position of the cooling annular pipe is automatically adjusted based on the width of the pneumatic tire, and a pneumatic tire with a tire size of 195/65R15 is used. In example 2, a structure is adopted in which the position of the cooling annular pipe is automatically adjusted based on the width of the pneumatic tire, and a pneumatic tire with a tire size of 225/60R18 is used.

The test tires obtained by the above-mentioned method for manufacturing pneumatic tires were evaluated for dimensional stability, uniformity, and intermediate elongation of the band cord using the following evaluation methods, and the results are shown in Table 1.

Dimensional Stability:
The profile of each test tire was measured, and the standard deviation of the profile measurement values was calculated for each of Conventional Examples 1 and 2 and Examples 1 and 2. The evaluation results were expressed as an index with Conventional Example 1 being set at 100. The smaller the index value, the better the dimensional stability.

Uniformity:
The radial force variation (RFV) of each test tire was measured, and the standard deviation of the RFV values was calculated for each of Conventional Examples 1 and 2 and Examples 1 and 2. The evaluation results were expressed as an index with Conventional Example 1 being set at 100. The smaller the index value, the better the uniformity.

Band cord intermediate elongation:
A band cord of the belt cover layer was taken from the shoulder portion of each test tire, and its intermediate elongation was measured, and the standard deviation of the intermediate elongation of the band cord was calculated for each of Conventional Examples 1 and 2 and Examples 1 and 2. The evaluation results were expressed as an index with Conventional Example 1 being set at 100. The smaller the index value, the smaller the variation in the intermediate elongation of the band cord.

As can be seen from Table 1, the tire obtained by the method of Example 1 had improved dimensional stability and uniformity compared to Conventional Example 1, and also had less variation in intermediate elongation of the band cord. Furthermore, Conventional Example 2, which had a tire size larger than Conventional Example 1, had worse results than Conventional Example 1 because the relative position of the annular pipe to the pneumatic tire was inappropriate. In contrast, Example 2, which had the same tire size as Conventional Example 2, obtained results equivalent to those of Example 1.

Reference Signs List 1, 2 Rim plate 3, 4 Support shaft 5 Supply passage 6 Discharge passage 11 Support beam 12 Support rod 13 Pipe drive device 13a Rod 13b Drive unit 14 Annular pipe 15 Air injection hole 21 Tire width detection device 22 Control unit M Pressurized medium T, T1, T2 Pneumatic tire

Claims (6)

When performing post-cure inflation on a pneumatic tire vulcanized in a mold,
a tire width detection device that detects the width of the pneumatic tire, which is a width measured in the central axial direction of the tire, using an apparatus including a pair of rim plates that fit into a pair of bead portions of a pneumatic tire, a supply passage that supplies a pressurized medium into the pneumatic tire through the rim plates, a discharge passage that discharges the pressurized medium in the pneumatic tire through the rim plates, an annular pipe that blows air onto an outer surface of the pneumatic tire, a pipe drive device that displaces the annular pipe along the tire width direction independently of the rim plates,
a pressure medium supplying unit that supplies a pressure medium to the pneumatic tire and a pressure adjusting unit that adjusts a position of the pneumatic tire based on the width of the pneumatic tire; a pressure adjusting unit that adjusts a position of the pneumatic tire based on the width of the pneumatic tire and a pressure adjusting unit that adjusts a position of the pneumatic tire based on the width of the pneumatic tire; The method for manufacturing a pneumatic tire according to claim 1, characterized in that the width of the pneumatic tire is detected by a camera. The method for manufacturing a pneumatic tire according to claim 1, characterized in that the width of the pneumatic tire is detected by a laser sensor. a supply path for supplying pressurized medium into the pneumatic tire through the rim plate; a discharge path for discharging the pressurized medium within the pneumatic tire through the rim plate; an annular pipe for blowing air onto an outer surface of the pneumatic tire; a pipe drive device for displacing the annular pipe along the tire width direction independently of the rim plate ; a tire width detection device for detecting the width of the pneumatic tire , which is the width measured in the central axial direction of the tire; and a control unit for controlling the pipe drive device based on the width of the pneumatic tire detected by the tire width detection device. The pneumatic tire manufacturing device according to claim 4, characterized in that the tire width detection device is a camera. The pneumatic tire manufacturing device according to claim 4, characterized in that the tire width detection device is a laser sensor.

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