JP5930678B2 - Pneumatic tire manufacturing equipment - Google Patents

Description

  The present invention relates to an apparatus for manufacturing a pneumatic tire that is docked by bonding (stitching) a 2nd cover to a 1st cover in an inflated state.

  When forming a green tire, set a pre-formed cylindrical 1st cover on a shaping former, fill the 1st cover with pressurized air (shaping air), and inflate with a predetermined shaping pressure. Docking is performed by stitching a 2nd cover onto the surface of a 1st cover in a freight state (for example, Patent Document 1).

JP 2007-22045 A

  However, in the product tire obtained by vulcanizing the green tire formed as described above, the RFV waveform may have a large variation. Such variations in the RFV waveform greatly affect steering stability and ride comfort.

  In view of the above problems, an object of the present invention is to provide a manufacturing technique of a pneumatic tire that can sufficiently reduce variation in an RFV waveform in a vulcanized tire.

The invention described in claim 1
A shaping former having a holding means for holding the first cover and a main shaft for supporting the holding means, and injecting the pressurized fluid into the first cover to inflate the first cover;
Stitching means for stitching a 2nd cover to the inflated 1st cover;
A flow path for introducing the pressurized fluid from the shaft end portion and allowing the pressurized fluid to flow into the first cover is formed in the main shaft,
The shaft end of the main shaft is connected to the pressurized fluid supply pipe by a rotary joint,
A pressure sensor for measuring the fluid pressure of the pressurized fluid is installed in the rotary joint part ,
The pneumatic tire manufacturing apparatus is controlled so that the internal pressure in the shaping former is increased to a predetermined final shaping pressure and then reduced to a predetermined stitch pressure in accordance with a stitch start timing. It is.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing apparatus of the pneumatic tire which can fully reduce the dispersion | variation in the RFV waveform in a vulcanized tire can be provided.

It is a figure which shows the relationship between the shaping setting value and the actual shaping internal pressure by the manufacturing apparatus of the pneumatic tire which concerns on embodiment of this invention. It is a figure which shows the relationship between the shaping set value by the manufacturing apparatus of the pneumatic tire of a prior art example, and actual shaping internal pressure. It is the figure which showed typically the manufacturing apparatus of the pneumatic tire which concerns on embodiment of this invention, and piping of pressurized air. It is a figure which shows the relationship between the actual shaping pressure and the measured value of the pressure in the piping of pressurized air. It is a figure which shows the relationship between the actual shaping pressure and the measured value of the pressure in the piping of pressurized air. It is a figure which shows the experimental result of the dispersion | variation in RFV waveform. It is a figure which shows the experimental result of the dispersion | variation in RFV waveform. It is a figure which shows the measurement result of low-speed RFV. It is a figure which shows the measurement result of high-speed RFV and high-speed TFV. It is a figure explaining a tread stitch. It is a figure which shows the state in which the tread stitch is started under the condition where shaping pressure is unstable.

  The present inventor came to pay attention to the 1st cover internal pressure (shaping internal pressure) when inflating the 1st cover in the process of examining the factors that cause the above-described conventional problems.

  That is, if the stitching is started while the shaping internal pressure at the start of the tread stitch is unstable, the 2nd cover is docked while the 1st cover is unstablely inflated, leading to deterioration of the RFV waveform and the RFV level σ. . In particular, when the tire diameter is large, the volume in the raw cover increases, so that the shaping flow rate cannot catch up and such a problem is likely to occur.

  FIG. 10 and FIG. 11 show such a situation as an image diagram. Actually, although it is necessary to stabilize the pressure in the raw cover as shown in FIG. The pressure in the raw cover may be unstable. When stitching is started in such a state, the RFV or the like deteriorates as described above.

  The inventor considered the cause of the instability of the shaping internal pressure as follows.

  In other words, the actual shaping internal pressure (actual shaping internal pressure) can be accurately measured by using TPMS (Tire Pressure Monitoring System), but in the production process, it may fall during rotation of the former and cannot be used. The pressure in the raw cover is not measured directly, but is measured in the vicinity of the solenoid valve of the secondary side piping that supplies the shaping air. As a result, since there was a difference between the actual shaping internal pressure, it was considered that the shaping internal pressure was unstable.

  Therefore, the following experiment was performed next.

  First, three types of tires with different diameter sizes (245 / 70R16, 265 / 75R16, 285 / 75R16) are shaped by setting the pressure in the raw cover in the vicinity of the solenoid valve of the secondary piping while maintaining the conventional conditions. Then, the actual shaping internal pressure in each case was measured.

  The results are shown in FIG. In FIG. 2, the vertical axis is pressure, the horizontal axis is the elapsed time after the first cover is set in the shaping former, the solid line is 245 / 70R16, the alternate long and short dash line is 265 / 75R16, and the broken line is the shaping at 285 / 75R16. It shows the temporal change in actual internal pressure. A thick solid line, an alternate long and short dash line, and a broken line drawn vertically indicate the stitch start timing of each tire. Moreover, the thick broken line with an unevenness | corrugation has shown the change of the setting value of the shaping pressure in the above-mentioned conventional measurement location.

  From the results shown in FIG. 2, it was found that there is a difference between the set value of the shaping pressure and the actual shaping internal pressure, and the difference increases as the tire size increases.

  Then, next, the optimal measurement location was examined. As a result, when measured at the rotary joint part of the main shaft of the shaping former, it was found that there was almost no difference between the setting value of the shaping pressure and the actual shaping internal pressure, and it was found that the rotary joint part was the optimum measurement location. .

  This point will be described with reference to FIGS. FIG. 3 schematically shows a shaping air supply path. In FIG. 3, P1 is a pressure sensor (TPMS) that measures the pressure in the first cover (low cover), that is, a shaping internal pressure, P2 is a pressure sensor that measures the pressure at the rotary joint portion of the main shaft of the above-described shaping former, and P3. Is a pressure sensor that measures the pressure at a location where the shaping pressure has been conventionally set. Further, 51 is a main shaft, 52 is a flow path, 53 is a shaping former, 54 is a rotary joint section, and 55 is a supply pipe for pressurized fluid.

  FIG. 4 is a diagram showing the results of measuring the pressure at each position when shaping air is supplied into the 1st cover. As can be seen from FIG. 4, the shaping internal pressure P1 has a large difference with the conventional set pressure P3, but is approximately 1: 1 with P2.

  And FIG. 5 is the figure which measured the time change of the shaping air pressure in P2, and when measuring the pressure in P1 after 35 seconds, it is 0.2 MPa which is the same as P2, and corresponds by 1: 1. You can see that

  As described above, it is understood that the actual shaping internal pressure can be managed with high accuracy by using the pneumatic tire manufacturing apparatus configured to manage the shaping pressure at P2, that is, the rotary joint portion of the main shaft of the shaping former. By managing the shaping pressure in this manner, the 2nd cover can be stitched and docked in a properly inflated state, so that a tire with small variations in the RFV waveform can be provided. .

  Specifically, the above manufacturing apparatus is specified as follows.

A shaping former having a holding means for holding the first cover and a main shaft for supporting the holding means, and injecting the pressurized fluid into the first cover to inflate the first cover;
Stitching means for stitching a 2nd cover to the inflated 1st cover;
A flow path for introducing the pressurized fluid from the shaft end portion and allowing the pressurized fluid to flow into the first cover is formed in the main shaft,
The shaft end of the main shaft is connected to the pressurized fluid supply pipe by a rotary joint,
A pneumatic tire manufacturing apparatus, wherein a pressure sensor for measuring a fluid pressure of a pressurized fluid is installed in the rotary joint portion.

  Next, the inventor further studied, and in the conventional method, the cause of the unstable shaping internal pressure is not only the management of the shaping internal pressure described above, but also the pressurizing method. I understood.

  That is, as shown in FIG. 2, in the past, the shaping pressure was initially set to an ultra-high pressure, then switched to a low pressure, and further set to a high pressure in accordance with the stitch start timing. For this reason, since the stitching is started in a state where the actual shaping internal pressure is not sufficiently increased, it was found that the shaping internal pressure became unstable at the initial stage of stitching, resulting in variations in RFV.

  Therefore, the present inventor abolished the switching to the low pressure in the conventional method and immediately set the high pressure after the ultra-high pressure as shown in FIG. It has been found that stitching can be performed under stable shaping internal pressure. As a result, it has become possible to reduce the variation in RFV.

  And when such a method was employ | adopted, since shaping internal pressure can be managed appropriately, it turned out that a shoulder closing speed can be made quick and the cycle of a process becomes possible.

  Next, while controlling the shaping pressure using the pneumatic tire manufacturing apparatus of the present invention, the tire uniformity characteristics of the new shaping internal pressure setting method shown in FIG. 1 and the conventional setting method shown in FIG. Evaluation was performed.

  The evaluation was performed using three types of tires “245 / 70R16”, “LT265 / 75R16”, and “LT285 / 75R16”.

  Specifically, the average values of RFV and RH1, σ, and variations in the shape of the RFV waveform were evaluated for each tire.

  FIG. 6 and FIG. 7 show the test results of the tire of “LT285 / 75R16” having the largest tire size (N = 4).

  FIG. 6 shows an RFV waveform of a tire produced by a conventional method. In FIG. 6, the horizontal axis indicates the tire circumferential direction as an angle (0 to 360 °), and the vertical axis indicates the RFV value.

  FIG. 7 shows an RFV waveform of a tire created by the new method. The horizontal and vertical axes in FIG. 7 are the same as those in FIG.

  From FIG. 6 and FIG. 7, it can be seen that the variation of the RFV waveform is reduced in the new method compared to the conventional method.

  Next, as shown in Table 1, the pressure at the start of stitching was set to 0.12 MPa for the conventional method and 0.20 MPa for the new method, and the above three types of tires were created and tested for low speed FV. The uniformity characteristics were evaluated.

  The results are shown in FIG. In FIG. 8, the vertical axis represents the low speed uniformity level (unit: N), and the horizontal axis represents the average value and σ of RFV, and the average value and σ of RH1.

  FIG. 8A shows the test result of “245 / 70R16”. From FIG. 8A, it can be seen that the σ of RFV is improved in the new method. FIG. 8B shows the test result of “LT265 / 75R16”. FIG. 8B shows that the average value of RFV and RH1 is improved in the new method. FIG. 8C shows the test results of the tire “LT285 / 75R16”. FIG. 8C shows that the average values and σ of RFV and RH1 are improved. From the above comprehensive judgment, it can be seen that the new method has improved uniformity characteristics.

  Next, with respect to the tire of “LT285 / 75R16” in which the improvement amount of the low speed FV was large, the high speed FV test was performed and the RFV and TFV were measured. The results are shown in FIG.

  FIG. 9A shows the measurement result of RFV. In FIG. 9A, the vertical axis represents the high-speed uniformity level (unit: N), and the horizontal axis represents the RFV average value and σ, and the RH1 average value and σ. From FIG. 9A, it can be seen that σ of RFV, the average value of RH1, and σ are improved in the new method.

  Moreover, FIG.9 (b) shows the measurement result of TFV. In FIG. 9B, the vertical axis represents the high-speed uniformity level (unit: N), and the horizontal axis represents the average value and σ of TFV and the average value and σ of RH1. From FIG. 9B, it can be seen that the average value of TFV, the σ of TFV1H, the average value of TFV2H, and σ are improved in the new method.

  From the above comprehensive judgment, it can be seen that the new method has improved uniformity characteristics.

  As described above, it is understood that the uniformity characteristic is improved by applying the shaping internal pressure by the new method of immediately increasing the pressure without using the low pressure after the ultrahigh pressure.

  While the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above-described embodiments within the same and equivalent scope as the present invention.

51 Main shaft 52 Flow path 53 Shaping former 54 Rotary joint 55 Pressurized fluid supply piping P1, P2, P3 Pressure sensor

Claims (1)

A shaping former having a holding means for holding the first cover and a main shaft for supporting the holding means, and injecting the pressurized fluid into the first cover to inflate the first cover;
Stitching means for stitching a 2nd cover to the inflated 1st cover;
A flow path for introducing the pressurized fluid from the shaft end portion and allowing the pressurized fluid to flow into the first cover is formed in the main shaft,
The shaft end of the main shaft is connected to the pressurized fluid supply pipe by a rotary joint,
A pressure sensor for measuring the fluid pressure of the pressurized fluid is installed in the rotary joint part ,
The pneumatic tire manufacturing apparatus is controlled so that the internal pressure in the shaping former is increased to a predetermined final shaping pressure and then reduced to a predetermined stitch pressure in accordance with a stitch start timing. .

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