JP2012011684A - Production method of tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a tire which controls difference of vulcanization degree due to a part location and reduces generation of bubbles, etc.SOLUTION: A semi-vulcanized tire 22 is taken out from a vulcanizing machine 10 when vulcanization has sufficiently progressed on the surface of a raw tire 20 (at the time of ending of pre-vulcanization). Then, the semi-vulcanized tire 22, once opened to atmosphere outside of the vulcanizing machine 10, is again moved into a pressurizing vessel 30 and is provided with gas pressure or liquid pressure from surrounds, so that vulcanization of an inner part (a most-delayed part) of the semi-vulcanized tire 22, which is not sufficiently vulcanized yet, is made to progress.

Description

  The present invention relates to a tire manufacturing method, and more particularly to a pneumatic tire manufacturing method.

  In general tire manufacturing methods, a raw tire molded on a rigid core is vulcanized by heating and pressing in the mold together with the rigid core to determine the product pattern and physical properties required for the rubber material. The temperature and pressure exerted on the tire during vulcanization are factors that determine the vulcanization degree and physical properties of the tire.

  Conventionally, the degree of vulcanization in the vulcanization process generally proceeds in two stages. The first stage is generally called pre-vulcanization. The raw tire is stored in a vulcanizer and heated and pressurized for a predetermined period of time by controlling the temperature and pressure. The temperature and pressure of the vulcanizer are controlled so that the vulcanization degree of the slowest part, which is the slow part, becomes the desired vulcanization degree.

  The subsequent second stage is called post-vulcanization, and this post-vulcanization is a vulcanization that proceeds from the time when the pre-cured tire is taken out of the vulcanizer until it is naturally cooled, In some cases, this is performed by attaching a tire to a post-cure inflation device (usually called a PCI device) or the like. The degree of vulcanization from the start of vulcanization to the end of post-vulcanization is controlled to a vulcanization degree within a predetermined range.

  However, in post-vulcanization, which is left to natural cooling, for example, a place where the post-vulcanization is performed such as a place deep inside the room or a place where it is easily exposed to outside air, for example, a position where a PCI device is installed, or a change in temperature. The progress of vulcanization varies depending on the degree of vulcanization, and the degree of vulcanization (post-vulcanization degree) from the start to the end of post-vulcanization varies. Moreover, it takes too much time to wait for the vulcanization to be completed in the vulcanization mold and put it into the PCI device, resulting in poor productivity.

  Therefore, as a countermeasure against the above problem, a manufacturing method has been proposed in which a tire is vulcanized with a vulcanizer until the middle of the target vulcanization amount, and then the fluid is filled into the semi-vulcanized tire and heated and cooled ( For example, see Patent Document 1). Further, a manufacturing method has been proposed in which post-vulcanization is performed using microwaves in a PCI device kept warm (see, for example, Patent Document 2). Or the manufacturing method which controls the atmospheric temperature in the post-vulcanization | curing | vulcanization | curing material is proposed (for example, refer patent document 3).

  However, both of the examples disclosed in Patent Document 1 and Patent Document 2 require additional equipment such as a device for injecting a liquid into a semi-vulcanized tire or a microwave generator, which increases the cost. In the example of Patent Document 3, there is a disadvantage that the equipment for controlling the atmospheric temperature in the post-vulcanization requires a cost as compared with the method of allowing to cool and naturally cooling.

JP-A-6-238669 Japanese Patent Laid-Open No. 9-193159 JP-A-7-032374

  By the way, in each of the above manufacturing methods, the tire is discharged from the vulcanizer at the time when the pre-vulcanization is completed, but it is necessary to secure the vulcanization degree of the slowest part in the tire that is the slowest vulcanization. Since temperature (amount of heat) is constantly supplied from the inner surface and the outer surface of the tire, vulcanization has already progressed in the vicinity of the surface layer of the tire even at the initial stage of vulcanization.

  For this reason, vulcanization tends to be excessive at the tire surface, and a partial difference in the degree of vulcanization progresses as a whole. In the initial stage of vulcanization, both the tire and the core have a small amount of thermal expansion, and the vulcanization of the tire surface proceeds under the condition that the pressure of the tire is small. There's a problem.

  This invention considers the said fact and makes it a subject to provide the tire manufacturing method which suppresses the difference in the vulcanization degree by a site | part, and reduces generation | occurrence | production of a bubble etc.

  The invention according to claim 1 is a pre-curing step of pressurizing and heating a tire in a vulcanizing mold in a vulcanizer, and a step of taking out the tire from the vulcanizing die before vulcanization is completed. And a post-vulcanization step in which the tire is transferred to a pressure vessel and held under pressure, and vulcanization is completed with residual heat.

  In the above invention, the tire is taken out of the vulcanizer before the slowest slowest vulcanization inside the tire finishes vulcanization, so that the tire is placed in the pressure vessel again while preventing excessive vulcanization on the tire surface. By completing the vulcanization with residual heat while applying pressure, the generation of bubbles and blown due to insufficient pressure can be suppressed, and the vulcanization can proceed without any shortage to the slowest part.

  According to a second aspect of the present invention, in the configuration according to the first aspect, in the pre-curing step, an amount of heat sufficient to vulcanize the entire tire is imparted to the tire.

  In the above invention, heat sufficient to sufficiently vulcanize the slowest vulcanization part inside the tire has already been applied in the pre-vulcanization process. By adding the heat of conduction from the surface, it is sufficiently vulcanized to the slowest part, and the difference in the degree of vulcanization between the surface part already vulcanized and the slowest part can be kept small.

  According to a third aspect of the present invention, in the configuration according to the first or second aspect, the tire is pressurized in a liquid in the post-vulcanization step.

  In said invention, a high pressure can be provided compared with the pressurization in the air by pressurizing a tire in a liquid in a post-vulcanization process.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the tire manufacturing method which suppresses the difference in the vulcanization degree by a site | part, and reduces generation | occurrence | production of a bubble etc.

It is a conceptual diagram which shows the manufacturing method of the tire which concerns on this invention. It is a conceptual diagram which shows the pressure provided to a tire in the manufacturing method of the tire shown in FIG. It is a conceptual diagram which shows the manufacturing method of the conventional tire. It is a conceptual diagram which shows the pressure provided to a tire in the manufacturing method of the tire shown in FIG.

<Overall configuration>
Hereinafter, as an embodiment of the present invention, a method for producing a pneumatic tire will be described as an example, and will be described in accordance with this method.

    FIG. 1A is a schematic sketch showing the vulcanizer 10 of the present embodiment. As shown in a conceptual diagram in FIG. 1A, the vulcanizer 10 includes a mold unit 16 including an upper mold 12 and a lower mold 14 that wraps the raw tire 20 from the outside, and the raw tire 20 from the inside. A bladder unit (not shown) that can be deformed so as to press outward.

  Due to the expansion of the bladder unit disposed inside the green tire 20, the outer surface of the green tire 20 is pressed against the inner surfaces of the upper mold 12 and the lower mold 14 to form a product pattern, and the raw tire 20 is heated by heating. Vulcanization is started from the surface, and rubber physical properties as a tire are given.

  The periphery of the mold unit 16 is covered with a jacket 18. A heating fluid (for example, steam) flows through the jacket 18. The jacket 18 heats the side of the mold unit 16 (upper mold 12 and lower mold 14) corresponding to the outer peripheral surface of the raw tire 20.

  In the vulcanizer 10 thus configured, a mold unit temperature sensor (not shown) for detecting the temperature of the mold unit 16 and a bladder temperature sensor (not shown) for detecting the temperature of the internal space of the raw tire 20 are included. Based on the temperatures detected by these sensors, a vulcanization control circuit (not shown) causes the heating fluid to flow so that the mold unit 16 and the bladder unit have a predetermined temperature.

  At this time, the mold unit 16 and the bladder unit add necessary heat to the raw tire 20 so that the raw tire 20 can obtain a sufficient degree of vulcanization as a whole. The amount of heat is calculated, the heated fluid is flowed, etc., and the amount of heat necessary for the entire raw tire 20 to obtain the degree of vulcanization is applied at the stage until the end of pre-vulcanization within the vulcanizer 10 where the processing is completed.

  As shown in FIG. 1B, when a product pattern is formed on the surface of the raw tire 20 by the pressurization and heating by the upper mold 12 and the lower mold 14, and the vulcanization sufficiently proceeds on the surface of the raw tire 20. At the end of the pre-vulcanization, the upper mold 12 and the lower mold 14 are opened and the semi-vulcanized tire 22 is taken out from the vulcanizer 10. At this point, the pre-vulcanization is complete.

  Here, as shown in FIG. 1B, the raw tire 20 that has finished the pre-vulcanization process is opened to the atmosphere outside the vulcanizer 10 as a semi-vulcanized tire 22. At this time, for example, the surface of the semi-vulcanized tire 22 may be cooled to a temperature at which the vulcanization does not proceed any further due to natural cooling. Also good. On the other hand, in the inside of the semi-vulcanized tire 22, the heat applied by the vulcanizer 10 penetrates from the surface by heat conduction, and if it is pressurized, further vulcanization proceeds.

  Further, as shown in FIG. 1C, the semi-vulcanized tire 22 is moved into the pressure vessel 30 and is given atmospheric pressure or hydraulic pressure from the surroundings. At this time, as described above, vulcanization inside the semi-vulcanized tire 22 (latest part) in which vulcanization has not sufficiently progressed is advanced by the heat (residual heat) already applied in the vulcanizer 10. . In the tire manufacturing method according to the present invention, this step corresponds to post-vulcanization.

  That is, in the conventional tire manufacturing method, after the pre-cured tire is taken out of the vulcanizer, it is attached to a post-cure inflation device (PCI device) or the like, and the degree of vulcanization that progresses until it is naturally cooled ( Whereas the vulcanization degree from the start of vulcanization to the end of post-vulcanization is set to a vulcanization degree within a predetermined range, in the tire manufacturing method according to the present invention, the semi-vulcanized tire 22 in which the pre-vulcanization has been completed. The process in which the degree of vulcanization progresses with the residual heat during the pressurization process in the pressure vessel 30 is referred to as a post-vulcanization process.

  The change of the pressure (vulcanization pressure) applied to the raw tire 20 (semi-vulcanized tire 22) in each step shown in FIGS. 1A to 1C is shown in relation to the vulcanization time. A conceptual diagram is shown in FIG.

  In FIG. 2, the portion A is maintained at a predetermined pressure by the mold unit 16 and the bladder unit in the vulcanizer 10, and the semi-vulcanized tire 22 is opened to the atmosphere when the pre-curing is completed. In this state, no pressure is applied. At this time, since the vulcanization is not completely completed depending on the part, the pressure becomes insufficient as described above, and there is a possibility that bubbles or blown may occur.

  Next, in part B, since the semi-vulcanized tire 22 is opened to the atmosphere and is not pressurized from the outside, vulcanization does not proceed further on the surface of the semi-vulcanized tire 22, and only the surface is excessively vulcanized. On the other hand, the so-called slowest part in which the vulcanization has not progressed sufficiently inside the semi-vulcanized tire 22 is still in a state where the vulcanization is still insufficient.

  Finally, in part C, the pressure is applied again by pressurizing the semi-vulcanized tire 22 with the atmospheric pressure or the hydraulic pressure inside the pressure vessel 30. The vulcanization pressure applied at this point does not necessarily need to be applied with the same pressure as the pressure applied inside the vulcanizer 10 at the A portion. That is, the surface of the semi-vulcanized tire 22 has already been molded by the mold unit 16 in the pre-vulcanization process and has physical properties that can maintain the shape of the tire, so that the pressure is insufficient as described above. Therefore, it is sufficient to apply a pressure that can prevent the occurrence of bubbles and blown.

<Effect>
In the conventional tire manufacturing method, as shown in FIGS. 3A and 3B, the semi-vulcanized tire 22 that has been pre-cured inside the vulcanizer 100 is taken out of the vulcanizer 100 and is naturally Allow to cool until cooled, or attach the tire to a post-cure inflation device and post-vulcanize. At this time, the change in pressure applied to the tire is not heated or pressurized after being heated and pressurized inside the vulcanizer 100 as shown in FIG. Sulfur proceeds.

  At this time, the heat and pressure applied inside the vulcanizer 100 are controlled such that the slowest part, which is the slowest part of vulcanization inside the tire, has a desired degree of vulcanization. However, since the pressure and heat necessary to secure the vulcanization degree of the slowest part are applied from the inner surface and outer surface of the raw tire 20 (not shown), the vulcanization degree is accelerated on the tire surface where the vulcanization degree progresses quickly. There was a tendency for the vulcanization to be excessive, and there was a risk of a difference in the progress of the vulcanization degree as a whole tire.

  In the tire manufacturing method according to the present invention, in the pre-vulcanization process performed in the vulcanizer 10 in FIG. Yes. Thereafter, when the semi-vulcanized tire 22 is released to atmospheric pressure in FIG. 1B, the heat applied to the raw tire 20 in the pre-curing process is still sufficiently vulcanized from the surface where the progress of the vulcanization degree is fast. It is supplied as conduction heat to the so-called slowest part that is not. On the other hand, on the surface where the progress of the vulcanization degree is fast, the temperature is lowered by stopping the heating, and the progress of vulcanization is stopped.

  Next, in the step of pressurizing the semi-vulcanized tire 22 in the pressure vessel 30 as shown in FIG. 1 (C), the temperature of the surface portion of the semi-vulcanized tire 22 has already decreased due to the stop of heating, and further vulcanization is performed. Does not progress. On the other hand, in the semi-vulcanized tire 22 where the progress of vulcanization is slow, heat is supplied as the conduction heat from the surface as described above, so that the degree of vulcanization proceeds even after the heating is stopped.

  As a result, on the surface of the semi-vulcanized tire 22 where the degree of vulcanization has already progressed, no further progress of the degree of vulcanization occurs, while on the other hand, the semi-vulcanized tire 22 whose degree of vulcanization has not sufficiently progressed Internally, the degree of vulcanization proceeds further due to the heat of conduction from the surface. And since it is pressurized inside the pressure vessel 30, the generation | occurrence | production of the bubble by the pressure shortage and a blown can be prevented.

  For this reason, the difference which arises in progress of a vulcanization degree by the surface and the inside of the semi-vulcanized tire 22 can be suppressed small, and it becomes possible to set it as the tire manufacturing method with few nonuniformity of the vulcanization degree by a site | part as a whole. . In particular, since the vulcanization degree on the surface is not excessively advanced, the tire performance such as the wear degree can be improved.

  Furthermore, since the post-vulcanization step pressurizes the semi-vulcanized tire 22 in the pressure vessel 30 instead of the vulcanizer 10 and may apply a hydraulic pressure without being limited to the atmospheric pressure, Since the degree of freedom is large and the specific heat of the liquid is larger than that of the gas, the temperature does not easily change, and temperature management and the like can be easily performed.

  Further, since the semi-vulcanized tire 22 is temporarily released to atmospheric pressure in a state where the internal vulcanization has not sufficiently progressed, the tire itself can be moved to any place (not limited to the place where the pressure vessel 30 is installed). Become. At the same time, since the time for the raw tire 20 to occupy the vulcanizer 10 can be shortened, the work can be performed more efficiently.

  Further, as described above, when the pressure is insufficient when the vulcanization degree of the tire is low, it is often impossible to obtain sufficient pressure to suppress the volatile matter in the tire and the expansion of the air, and blown (dent) or air Although the problem of entering (bubbles) or the like is known, even if the blower is generated when the semi-vulcanized tire 22 is taken out from the vulcanizer 10, the inventors have the pressure vessel 30. It has been found that the blown already generated can be reduced by maintaining pressure inside.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and the scope of rights of the present invention is not limited to these embodiments, and does not depart from the gist of the present invention. Needless to say, various modifications can be made.

DESCRIPTION OF SYMBOLS 10 Vulcanizer 12 Upper mold 14 Lower mold 16 Mold unit 18 Jacket 20 Raw tire 22 Semi-vulcanized tire 30 Pressure vessel

Claims (3)

A pre-curing step of pressurizing and heating the tire in the vulcanizing mold in a vulcanizer;
Removing the tire from the vulcanization mold before vulcanization is completed;
After the tire is transferred to a pressure vessel and held under pressure, vulcanization is completed with residual heat;
The tire manufacturing method characterized by including.   2. The tire manufacturing method according to claim 1, wherein in the pre-vulcanization step, an amount of heat sufficient to vulcanize the entire tire is imparted to the tire.   The tire manufacturing method according to claim 1, wherein the tire is pressurized in a liquid in the post-vulcanization step.

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