JP2019214158A - Puncture detection method for tire vulcanizing bladder - Google Patents

Abstract

To provide a puncture detection method for a tire vulcanizing bladder 2, which can detect a puncture of the bladder 2 with high accuracy.SOLUTION: In this detection method, an internal pressure is maintained at a pressure Pf by introducing steam, a low cover R is pressed from the inside to a mold, and the internal pressure is maintained at a pressure Ps higher than the pressure Pf by introducing a gas medium other than steam, and the low cover R is further pressed against the mold from the inside. A method of detecting a puncture of a bladder includes a monitoring step of monitoring leakage of a gas medium from inside to outside of the bladder by measuring a concentration of the gas medium. The monitoring step includes a stage for maintaining the internal pressure of the bladder at a pressure Pt lower than the pressure Ps during a period from a start of discharging the steam and the gas medium introduced into the bladder to an end thereof.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a puncture detection method for a bladder for tire vulcanization.

  The tire is obtained by pressing and heating the raw cover in a mold. In the manufacture of tires, a bladder made of crosslinked rubber may be used instead of a rigid metal core for pressurizing and heating the raw cover. In a tire vulcanizer, the bladder is located inside the mold.

  In tire manufacturing, steam is introduced into a bladder when a raw cover is put into a mold. The bladder expands. The bladder presses the raw cover from the inside against the cavity surface of the mold. Nitrogen gas is further introduced into the bladder. Thereby, the raw cover is further pressed against the cavity surface.

  As described above, the bladder is made of a crosslinked rubber. In the manufacture of a tire, inflation and contraction are repeated in a bladder. Use may cause punctures on the bladder. If a puncture occurs and the internal pressure of the bladder cannot be increased, the bladder cannot sufficiently press the raw cover against the mold.

  In a vulcanizer, many tires are manufactured. In order to stably manufacture a high-quality tire while appropriately controlling the internal pressure of the bladder, various studies have been made on a bladder puncture detection method (for example, Patent Document 1).

  In Patent Document 1, bladder puncture is detected by confirming steam leakage. In Patent Literature 1, a sensor (specifically, a humidity sensor) is used for detecting steam leaked from the bladder. This sensor is installed in a sensor box into which steam leaking from the bladder is led.

JP 2010-115796 A

  In the detection method described in Patent Document 1, steam leakage is confirmed in the steps of introducing steam into the bladder to heat and pressurize the raw cover, and in the step of discharging steam and nitrogen gas from the bladder. In this detection method, the puncture detection accuracy is improved as compared with the conventional method of confirming steam leakage in the step of discharging steam and nitrogen gas from the bladder. However, the amount of steam to be checked is limited, and the steam is discharged from the bladder in the discharging process, so that there is a limit to improving the accuracy of detecting a puncture. In particular, when the amount leaking from the bladder is very small, it is undeniable that steam leakage cannot be confirmed.

  As described above, in Patent Document 1, in order to detect bladder puncture, leakage of steam is confirmed using a sensor. The detection of steam by this sensor is susceptible to changes in the measurement environment, that is, changes in humidity in the sensor box. The steam becomes water droplets when cooled, and adheres to, for example, the sensor box. If water accumulates in the sensor box, the accumulated water may cause erroneous detection of steam. The method of detecting a puncture of a bladder by confirming steam leakage lacks stability in terms of puncture detection accuracy.

  In order to stably produce high-quality tires, it is desired to grasp the bladder puncture at an early stage. From this viewpoint, there is a demand for establishment of a technology that can improve the accuracy of bladder puncture detection.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for detecting a puncture of a bladder for tire vulcanization, which can detect a puncture of a bladder with high accuracy.

The puncture detection method for a tire vulcanizing bladder according to the present invention is characterized in that, in the process of obtaining a tire by heating and pressurizing a raw cover in a mold, the raw cover expands by introducing steam, holds the internal pressure at a pressure Pf, and holds the raw cover from the inside. Pressed against the mold, expanded by the introduction of a gas medium other than steam, maintained at an internal pressure at a pressure Ps higher than the pressure Pf, further pressed the raw cover from the inside to the mold, and A method for detecting a puncture of a bladder that shrinks due to ejection,
A monitoring step of monitoring the leakage of the gas medium from the inside to the outside of the bladder by measuring the concentration of the gas medium,
The monitoring step includes a stage for maintaining the internal pressure of the bladder at a pressure Pt lower than the pressure Ps during a period from the start of discharging the steam and the gas medium introduced into the bladder to the end thereof.

  Preferably, in this method for detecting a puncture of a tire vulcanizing bladder, the pressure Pt is 0.7 times or more and 0.8 times or less of the pressure Ps.

  Preferably, in this method for detecting a puncture of a tire vulcanizing bladder, the time during which the internal pressure of the bladder is maintained at the pressure Pt is 10 seconds or more and 20 seconds or less.

  Preferably, in this method for detecting a puncture of a tire vulcanizing bladder, the gas medium is nitrogen gas.

  In the method for detecting a puncture of a bladder for tire vulcanization according to the present invention, in the monitoring step, leakage of the gas medium from the inside to the outside of the bladder is monitored. Since steam is not monitored, this detection method improves stability in terms of puncture detection accuracy. Moreover, in this detection method, the monitoring step includes a stage for maintaining the internal pressure of the bladder at the pressure Pt between the time when the discharge of steam and the gas medium is started and the time when the discharge is completed. This stage promotes leakage of gaseous media from inside to outside of the bladder when the bladder is punctured. Since the concentration of the gas medium outside the bladder increases, leakage of the gas medium from the bladder can be properly confirmed. According to this detection method, puncture of the bladder can be detected with high accuracy.

FIG. 1 is a diagram schematically illustrating an example of a vulcanizer provided with a vulcanizing bladder that is an object of a puncture detection method according to an embodiment of the present invention. FIG. 2 is a graph showing the internal pressure profile of the bladder. FIG. 3 is a diagram illustrating the operation of the vulcanizer.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the drawings as appropriate.

  FIG. 1 shows a part of a tire vulcanizer 4 having a vulcanizing bladder 2 to which a puncture detection method according to an embodiment of the present invention is applied. In the manufacture of the tire, the tire is obtained by pressurizing and heating the raw cover R (unvulcanized tire) in the tire vulcanizer 4. In FIG. 1, the left-right direction corresponds to the radial direction of the tire. The vertical direction corresponds to the axial direction of the tire.

[Tire vulcanizer 4]
The tire vulcanizer 4 shown in FIG. 1 (hereinafter, vulcanizer 4) has a configuration equivalent to the configuration of a vulcanizer generally used in tire production. In order to explain the puncture detection method, the mold 6, the bladder 2, and the center mechanism 8 in the configuration of the vulcanizer 4 will be described.

[Mold 6]
The mold 6 includes a plurality of segments 10 arranged in the circumferential direction, a pair of side rings 12, and a pair of bead rings 14. In the mold 6, a cavity surface 16 that forms the outer surface of the tire is formed by combining the plurality of segments 10, the pair of side rings 12, and the pair of bead rings 14. This mold 6 is a split mold. A two-piece mold may be used as the mold 6.

  In the vulcanizer 4, the upper side ring 12 and the bead ring 14 are fixed to the upper hot plate 18a. The lower side ring 12 and the bead ring 14 are fixed to the lower hot plate 18a. The upper heating plate 18a and the lower heating plate 18b heat the mold 6.

[Bladder 2]
The bladder 2 is located radially inside the mold 6. The bladder 2 is made of a bag-shaped crosslinked rubber. In the vulcanizer 4, the material of the bladder 2 is not particularly limited. In the vulcanizer 4, a bladder 2 generally used in the manufacture of a tire is used.

  For heating and pressurizing the raw cover, a gas medium such as steam or nitrogen gas whose pressure and temperature are adjusted is introduced into the bladder 2. Thereby, the bladder 2 expands. When the pressurization and heating of the raw cover R are completed, the gas medium is discharged from the bladder 2. Thereby, the bladder 2 contracts.

[Center mechanism 8]
The center mechanism 8 includes an upper clamp ring 20. The upper clamp ring 20 grips the upper open end 2 a of the bladder 2. In the center mechanism 8, the open end 2 a of the bladder 2 is sandwiched between the plate 20 a and the ring 20 b, and these are bolted, so that the open end 2 a is gripped by the upper clamp ring 20.

  The center mechanism 8 includes a vertically movable center post 22. The upper clamp ring 20 is supported by the center post 22. In the vulcanizer 4, by raising the center post 22, the open end 2 a of the bladder 2 gripped by the upper clamp ring 20 is raised. By lowering the center post 22, the opening end 2a is lowered. In the vulcanizer 4, the position of the opening end 2a in the vertical direction (in other words, the axial direction) is controlled by moving the center post 22 up and down.

  The center mechanism 8 includes a lower clamp ring 24. The lower clamp ring 24 grips the lower open end 2 b of the bladder 2. In the center mechanism 8, the lower clamp ring 24 and the lower bead ring 14b sandwich the open end 2b of the bladder 2 and tighten the bolts to hold the open end 2b with the lower clamp ring 24. Is done.

  The center mechanism 8 includes a hub 26. The hub 26 supports the lower clamp ring 24. Thereby, the lower clamp ring 24 is fixed to the center mechanism 8.

  Although not shown, an intervening member such as a seal member is inserted between the hub 26 and the center post 22 in order to prevent a gas medium from leaking between the center post 22 and the hub 26. In the center mechanism 8, a cap 28 is attached to the tip of the hub 26 to prevent the inclusion from coming off. In the vulcanizer 4, the cap 28 is fixed to the hub 26 by bolting the cap 28 and the hub 26 together.

  The cap 28 has a disk shape. The outer surface 30 of the cap 28 has a top surface 30a that expands in the radial direction and a side surface 30b that extends in the thickness direction from the outer edge of the top surface 30a.

  As described above, in the vulcanizer 4, when the raw cover R is pressurized and heated, a gas medium is introduced into the bladder 2. When the pressurization and heating of the raw cover R are completed, the gas medium is discharged from the bladder 2. The vulcanizer 4 includes a supply / discharge device 32 for introducing a gas medium into the bladder 2 and discharging the gas medium from the bladder 2.

[Supply / discharge device 32]
The supply / discharge device 32 includes an introduction route 34 for introducing the gas medium into the bladder 2 and a discharge route 36 for discharging the gas medium from the bladder 2. In the vulcanizer 4 having the supply / discharge device 32, an introduction pipe 38 as a part of the introduction route 34 and a discharge pipe 40 as a part of the discharge route 36 are provided in the central mechanism 8.

  The introduction route 34 extends between a tank (not shown) containing a gas medium and the inside of the bladder 2. In the vulcanizer 4, the gas medium in the tank is supplied into the bladder 2 through the introduction route 34. On the other hand, the discharge route 36 bridges the inside of the bladder 2 and the outside. In the vulcanizer 4, the gas medium in the bladder 2 is discharged through the discharge route 36 to the outside.

  In the vulcanizer 4, an introduction valve (not shown) such as a piston valve is provided in the middle of the introduction route. A discharge valve (not shown) such as a piston valve is provided in the middle of the discharge route 36. In the vulcanizer 4, the opening and closing of the introduction valve and the opening and closing of the discharge valve are controlled by control means. Examples of the control means include a programmable sequencer, a microcomputer, a personal computer, and other control devices.

  In the vulcanizer 4, the end of the introduction route 34 is an introduction port 42 for introducing a gaseous medium into the bladder 2. The start end of the discharge route 36 is a discharge port 44 for discharging the gas medium from inside the bladder 2. In the vulcanizer 4, an inlet 42 and an outlet 44 are provided on the outer surface 30 of the cap 28.

[Manufacture of tires]
In the manufacture of a tire using the vulcanizer 4, the raw cover R is prepared by combining the components of the tire in a molding machine (not shown). The raw cover R is put into the mold 6. After the introduction, steam is introduced into the bladder 2 as a gas medium through the introduction route 34, and the mold 6 is closed.

  In the manufacture of this tire, the bladder 2 expands due to the introduction of steam. The expanded bladder 2 presses the raw cover R against the cavity surface 16 of the mold 6 from the inside. Thereby, the raw cover R is heated and pressed. In the production of this tire, the step of introducing steam into the bladder 2 to heat and press the raw cover R is called a primary inflation step. In the production of the tire, the temperature of the steam introduced into the bladder 2 is set in a range from 180 ° C. to 200 ° C.

  In the manufacture of the tire, when a predetermined time elapses after the steam is introduced into the bladder 2, a gas medium different from the steam is introduced into the bladder 2 through the introduction route 34. Thereby, the bladder 2 expands. The bladder 2 further presses the raw cover R against the cavity surface 16 of the mold 6 from the inside. The raw cover R is further heated and pressed. In the manufacture of this tire, the step of introducing a gas medium other than steam into the bladder 2 to heat and pressurize the raw cover R is called a secondary inflation step.

  In the manufacture of this tire, an inert gas such as a nitrogen gas is used as a gas medium supplied to the bladder 2 in the secondary inflation step. From the viewpoint of preventing a rise in temperature due to adiabatic compression, the gas medium is preferably nitrogen gas at normal temperature.

  In the manufacture of the tire, when a predetermined time has elapsed after introducing a gas medium other than steam into the bladder 2, steam and a gas medium other than the steam are discharged from the bladder 2 through the discharge route 36. You. Thereby, the bladder 2 contracts. In the manufacture of the tire, the step of discharging the gas medium from the bladder 2 is called a discharging step.

  In the manufacture of this tire, the raw cover R is heated and pressed in the primary inflation step and the secondary inflation step. Thereby, the rubber composition of the raw cover R is vulcanized, and a tire is obtained. In the discharging step, the gas medium is discharged from the bladder 2 as described above. The mold 6 is opened and the tire is removed from the mold 6.

[Pressure profile]
FIG. 2 shows a profile of the internal pressure of the bladder 2 in a process of obtaining a tire by heating and pressing the raw cover R in the mold 6. The horizontal axis indicates the time elapsed since the introduction of steam into the bladder 2 was started. The vertical axis indicates the internal pressure of the bladder 2. In FIG. 2, a double arrow R1 is a time range corresponding to the primary inflation step. Double arrow R2 is a time range corresponding to the secondary inflation process. A double arrow R3 is a time range corresponding to the discharging process.

  In the primary inflation step R1, the internal pressure of the bladder 2 is maintained at the pressure Pf by introducing steam. In the manufacture of this tire, the pressure Pf in the primary inflation step R1 is set in a range from 1.5 MPa to 2.5 MPa. The holding time at this pressure Pf is set in a range from 1 minute to 15 minutes.

  In the secondary inflation step R2, the internal pressure of the bladder 2 is maintained at the pressure Ps by introducing a gas medium other than steam. The pressure Ps in the secondary inflation step R2 is set in a range from 1.5 MPa to 2.5 MPa. In the manufacture of this tire, as shown in FIG. 2, the pressure Ps in the secondary inflation step R2 is set to be higher than the pressure Pf in the primary inflation step R1. The holding time at this pressure Ps is set in a range from 1 minute to 15 minutes.

  In the manufacture of this tire, after the second inflation step R2, the discharging step R3 is started. As described above, the gas medium is discharged from the bladder 2 in the discharging step R3. The time required from opening the discharge valve to starting the discharge and ending the discharge is set in a range of 30 seconds to 60 seconds.

  As described above, in the manufacture of a tire, the introduction of the gas medium causes the bladder 2 to expand. The expanded bladder 2 presses the raw cover R against the mold 6 from the inside. The bladder 2 is made of a crosslinked rubber, and expansion and contraction are repeated in the manufacture of the tire. For this reason, a puncture may occur in the bladder 2. When a puncture occurs in the bladder 2, there is a concern that the force with which the bladder 2 presses the raw cover R against the mold 6 may be insufficient depending on the degree of the puncture. For this reason, the vulcanizer 4 is provided with a gas medium detection device 46 in order to confirm leakage of the gas medium due to puncture and detect puncture. That is, the vulcanizer 4 includes the gas medium detecting device 46.

[Detection device 46]
The detecting device 46 includes detecting means 48 for detecting leakage of the gas medium, and a guiding route 50 for guiding the gas medium leaked from the bladder 2 to the detecting means 48. The guidance route 50 extends between the outside of the bladder 2 and the detection means 48. In the vulcanizer 4, a guide route 50 is formed by a guide hole 52 penetrating the upper side ring 12 and the hot plate 18a, and a guide tube 54 extending from the guide hole 52 to the detecting means 48.

  In the detecting device 46, the leakage of the gas medium is confirmed by tracking a change in the concentration of the target gas medium. In the detecting device 46, there is no particular limitation on the detecting means 48 as long as the change in the concentration of the gas medium can be tracked. For example, when the tracking target is nitrogen gas, a product name “Nitrogen concentration meter (2-7925-11)” of AS ONE Corporation can be used as the detecting means 48.

  In the vulcanizer 4 having the detection device 46 described above, a puncture of the bladder 2 is detected while manufacturing a tire. Next, a puncture detection method of the bladder 2 will be described.

[Punk detection method]
In the method of detecting puncture of the bladder 2, in the process of obtaining a tire by heating and pressurizing the raw cover R in the mold 6, the raw cover is expanded by introduction of steam, the internal pressure is maintained at the pressure Pf, and the raw cover R is pressed against the mold 6 from the inside. , Is expanded by the introduction of a gas medium other than the steam, the internal pressure is maintained at a pressure Ps higher than the pressure Pf, and the raw cover R is further pressed against the mold 6 from the inside, and the steam and a gas medium other than the steam are separated. This is a method for detecting a puncture of the bladder 2 which contracts due to the discharge of the bladder.

  The puncture detection method of the bladder 2 (hereinafter, detection method) includes a monitoring step. In this monitoring step, the leakage of the gas medium from the inside to the outside of the bladder 2 is monitored by directly or indirectly measuring the concentration of the gas medium. Specifically, the change with time of the gas medium concentration obtained by the detecting means 48 is tracked. In this monitoring step, leakage of the gas medium is confirmed by detecting an increase in the gas medium concentration.

  In this detection method, the monitoring target of the leak is not the steam introduced into the bladder 2 in the first inflation step R1, but the gas medium introduced into the bladder 2 in the second inflation step R2. In other words, in this detection method, in the monitoring step, leakage of a gas medium other than steam from the inside to the outside of the bladder 2 is monitored. Since steam is not to be monitored, this detection method is more stable in terms of puncture detection accuracy than the conventional detection method in which steam is to be monitored.

  As described above, the gas medium introduced into the bladder 2 in the second inflation step R2 is discharged in the discharge step R3. In this detection method, the gas medium leaked from the bladder 2 in the second inflation step R2 and the discharge step R3 is a monitoring target.

  In the discharge step R3, the internal pressure of the bladder 2 gradually decreases due to the discharge of the gas medium. In particular, in this detection method, as shown in FIG. 2, the pressure profile in the discharge step R3 is maintained at a pressure Pt lower than the pressure Ps in the second inflation step R2 for a predetermined time. In other words, the monitoring step of this detection method includes a stage (hereinafter, referred to as a holding stage) for holding the internal pressure of the bladder 2 at the pressure Pt from the time when the discharge of the steam and the gas medium is started to the time when the discharge ends. . This holding stage promotes leakage of the gaseous medium from the inside to the outside of the bladder 2 when the bladder 2 is punctured. Since the concentration of the gas medium outside the bladder 2 increases, the leakage of the gas medium from the bladder 2 is properly confirmed. As described above, since the monitoring target of this detection method is not steam but a gas medium different from this steam, stability is improved in terms of puncture detection accuracy. According to this detection method, the puncture of the bladder 2 can be detected with high accuracy.

  As described above, in this detection method, the pressure Pt of the holding stage provided in the discharge step R3 is lower than the pressure Ps in the second inflation step R2. Specifically, the pressure Pt is preferably 0.7 times or more the pressure Ps, and more preferably 0.8 times or less. By setting the pressure Pt to be equal to or more than 0.7 times the pressure Ps, when a puncture occurs in the bladder 2, leakage of the gas medium from the inside to the outside of the bladder 2 is promoted. Since the concentration of the gas medium outside the bladder 2 increases, leakage of the gas medium from the bladder 2 is more appropriately confirmed. By setting the pressure Pt to be equal to or less than 0.8 times the pressure Ps, the time required for the discharge step R3 is appropriately maintained. In the production of a tire to which this detection method is applied, good productivity is maintained.

  In this detection method, the pressure Pt of the holding stage provided in the discharging step R3 is preferably 0.5 MPa or more, and more preferably 2.0 MPa or less. When the pressure Pt is set to 0.5 MPa or more, leakage of the gas medium from the inside to the outside of the bladder 2 is promoted when the bladder 2 is punctured. Since the concentration of the gas medium outside the bladder 2 increases, leakage of the gas medium from the bladder 2 is more appropriately confirmed. By setting the pressure Pt to 2.0 MPa or less, the time required for the discharge step R3 is appropriately maintained. In the production of a tire to which this detection method is applied, good productivity is maintained.

  In FIG. 2, the double-headed arrow S indicates the time during which the pressure Pt is maintained in the discharge process R3. In other words, the time S is a time required for the holding stage (hereinafter, a holding time) included in the monitoring process.

  In this detection method, the holding time S is preferably 10 seconds or more, and more preferably 20 seconds or less. By setting the holding time S to 10 seconds or more, when a puncture occurs in the bladder 2, leakage of the gas medium from the inside to the outside of the bladder 2 is promoted. Since the concentration of the gas medium outside the bladder 2 increases, leakage of the gas medium from the bladder 2 is more appropriately confirmed. By setting the holding time S to 20 seconds or less, the time required for the discharging step R3 is appropriately maintained. In the production of a tire to which this detection method is applied, good productivity is maintained.

  As described above, in this detection method, the monitoring step includes the holding stage that holds the internal pressure of the bladder 2 at the pressure Pt from the time when the discharge of the steam and the gas medium is started to the time when the discharge ends. In order to maintain the internal pressure of the bladder 2 at the pressure Pt, the opening and closing of the introduction valve and the discharge valve are controlled. In this detection method, the internal pressure of the bladder 2 may be adjusted to the pressure Pt by closing the discharge valve after a lapse of a predetermined time from the start of the discharge step R3. After a lapse of a predetermined time from the start of the discharge step R3, the discharge valve is closed and the introduction valve is opened to introduce a gas medium other than steam into the bladder 2, whereby the internal pressure of the bladder 2 is adjusted to the pressure Pt. Is also good. From the viewpoint that the leakage of the gas medium from the inside of the bladder 2 to the outside is promoted, and the concentration of the gas medium outside the bladder 2 can be effectively increased, in this detection method, after the discharge step R3 is started. After a lapse of a predetermined time, it is preferable that the internal pressure of the bladder 2 be adjusted to the pressure Pt by closing the discharge valve and opening the introduction valve to introduce a gas medium other than steam into the bladder 2. In this case, a gas medium different from the gas medium introduced in the second inflation step R2 may be used as the gas medium introduced into the bladder 2 to maintain the internal pressure of the bladder 2 at the pressure Pt. However, from the viewpoint that the concentration of the gas medium outside the bladder 2 can be effectively increased, the gas medium introduced into the bladder 2 to maintain the internal pressure at the pressure Pt is introduced in the second inflation step R2. More preferably, it is the same as the gas medium used.

  As described above, in the manufacture of the tire, the gas medium introduced in the second inflation step R2 is preferably a normal temperature nitrogen gas. Therefore, in this detection method, from the viewpoint that the concentration of the gas medium outside the bladder 2 can be effectively increased when the gas medium introduced in the second inflation step R2 is nitrogen gas at room temperature. The gas medium introduced into the bladder 2 to maintain the internal pressure at the pressure Pt is preferably a normal temperature nitrogen gas, like the gas medium introduced in the second inflation step R2. In other words, in this detection method, the gas medium for which leakage is confirmed for the detection of puncture in the monitoring step is preferably nitrogen gas.

  In FIG. 2, a double-headed arrow L indicates a time (hereinafter, referred to as an induction time L) from when the discharge valve is opened to start the discharge process R3 to start the holding stage.

  In this detection method, the induction time L is preferably 5 seconds or more from the viewpoint that leakage of the gas medium can be more appropriately confirmed. From the viewpoint of suppressing the influence of the induction time L on the productivity of the tire, the induction time L is preferably 15 seconds or less.

  As described above, in manufacturing the tire, the bladder 2 presses the raw cover R against the mold 6 from the inside. For this reason, the bladder 2 adheres to the tire obtained by heating and pressing the raw cover R. In the manufacture of the tire, when the tire is obtained by heating and pressurizing the raw cover R, the gas medium is discharged from the bladder 2, the mold 6 is opened, and the tire is taken out.

  As shown in FIG. 3, in the manufacture of the tire T, the opening end 2a of the bladder 2 is lowered to take out the tire T, and the bladder 2 is peeled off from the tire T. As a result, a gap is formed between the bladder 2 and the tire T, and guidance of the gas medium existing between the bladder 2 and the tire T to the detection means 48 through the guidance route 50 is promoted. As described above, the holding stage in the discharging step R3 promotes leakage of the gas medium from the inside to the outside of the bladder 2, and increases the concentration of the gas medium outside the bladder 2. From the viewpoint that the leakage of the gas medium from the bladder 2 is more appropriately confirmed, after the opening end 2a of the bladder 2 is lowered and the bladder 2 is peeled off from the tire T, the internal pressure of the bladder 2 is reduced in the discharging step R3. It is preferable that the holding stage held at the pressure Pt be set.

  In this detection method, the monitoring step is applied in the second inflation step R2 and the discharging step R3 in the tire T manufacturing process. This monitoring step may be applied only in the discharging step R3. This monitoring step may be applied in the first inflation step R1, the second inflation step R2, and the discharge step R3.

  As is clear from the above description, the puncture detection method of the vulcanizing bladder 2 of the present invention can detect puncture of the bladder 2 with high accuracy.

  The embodiment disclosed this time is an example in all respects and is not restrictive. The technical scope of the present invention is not limited to the above-described embodiment, and includes all modifications within a scope equivalent to the configuration described in the claims.

  The puncturing detection method of the vulcanizing bladder described above can be applied to various tire vulcanizers.

2 ... Vulcanizing bladder 4 ... Tire vulcanizer 6 ... Mold 8 ... Central mechanism 10 ... Segment 12 ... Side ring 14 ... Bead ring 16 ... Cavity surface Reference Signs List 20 upper clamp ring 22 center post 24 lower clamp ring 26 hub 28 cap 30 outer surface 32 supply / discharge device 34 introduction route 36 ... discharge route 38 ... introduction pipe 40 ... discharge pipe 42 ... introduction port 44 ... discharge port 46 ... detection device 48 ... detection means 50 ... guidance route 52 ...・ Induction hole 54 ・ ・ ・ Induction tube

Claims (4)

In the process of obtaining the tire by heating and pressurizing the raw cover in the mold, it is expanded by the introduction of steam, maintains the internal pressure at the pressure Pf, presses the raw cover against the mold from the inside, and introduces a gas medium different from steam. Method for detecting a puncture of a bladder that expands and holds the internal pressure at a pressure Ps higher than the pressure Pf, further presses the raw cover from the inside against the mold, and contracts due to the discharge of the steam and the gaseous medium. And
A monitoring step of monitoring the leakage of the gas medium from the inside to the outside of the bladder by measuring the concentration of the gas medium,
A tire including a stage for maintaining the internal pressure of the bladder at a pressure Pt lower than the pressure Ps during a period from the start to the end of the discharge of the steam and the gas medium introduced into the bladder, to the end thereof. Puncture detection method for vulcanizing bladders.   The puncture detection method for a tire vulcanizing bladder according to claim 1, wherein the pressure Pt is 0.7 times or more and 0.8 times or less of the pressure Ps.   The puncture detection method for a tire vulcanizing bladder according to claim 1 or 2, wherein the time during which the internal pressure of the bladder is maintained at the pressure Pt is 10 seconds or more and 20 seconds or less. The puncture detection method for a tire vulcanizing bladder according to any one of claims 1 to 3, wherein the gas medium is a nitrogen gas.

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