JP5318682B2 - Tire vulcanization method - Google Patents

Description

  The present invention relates to a tire vulcanizing method, and more particularly, to a tire vulcanizing method that suppresses a temperature decrease of a vulcanization mold during tire vulcanization.

  In vulcanization molding of tires, particularly vulcanization molding of large tires, a multi-segment segment mold (split mold) has recently been used as a vulcanization mold (hereinafter also simply referred to as “mold”) (for example, Patent Document 1).

  An example of such a split mold is shown in FIG. FIG. 1 is a schematic cross-sectional view schematically showing the internal structure of a split mold (die A), which is arranged in the circumferential direction and constitutes a tire vulcanizing apparatus, including a container.

  As shown in FIG. 1, the mold A is sandwiched between upper and lower platen boards 4 and 5 included in a tire vulcanizer, and a pair of upper and lower side molds 1 and 2 that form a sidewall portion of the tire, and a tire And a tread segment 3 forming a tread portion (and a shoulder portion). The tread segment 3 is a split remolded portion that is divided into a plurality of portions in the circumferential direction, and a sector shoe 6 that is a part of the container B that holds the tread segment 3 from the outer surface side is provided on the outer side thereof. An actuator 7 which is a part of the container B fixed to the upper platen board 4 is disposed on the outer peripheral side of the sector shoe 6. A platen jacket 9 is provided inside the upper and lower platen boards 4 and 5, and a container jacket 8 is provided inside the actuator 7.

  The raw tire is vulcanized using the tire vulcanizer as follows. First, a heating medium such as steam is introduced into the container jacket 8 and the platen jacket 9 to heat the mold A.

  Next, the actuator 7 is raised by the driving means (not shown) as the upper platen board 4 is raised. In accordance with this, the sector shoe 6 moves radially outward together with the tread segment 3, and the mold A is opened.

  Next, an unvulcanized raw tire is mounted on the mold A that is in the open state, and the actuator 7 is lowered as the upper platen board 4 is lowered by driving means (not shown). In accordance with this, the sector shoe 6 moves inward in the radial direction together with the tread segment 3, and the mold A is closed. The green tire mounted on the mold A is then vulcanized by receiving heat and pressure from the mold A and a bladder (not shown).

  The green tire which has been vulcanized by heating under pressure for a predetermined time is removed from the mold A after the mold A is opened. Then, the next green tire is mounted on the mold A, and the same vulcanization process is repeated.

  In the conventional tire vulcanization method as described above, the temperature of the heating medium such as steam introduced into the container jacket 8 or the platen jacket 9, that is, the jacket temperature is a constant temperature from the start to the end of the vulcanization operation. It was set and controlled to be.

  However, in such conventional tire vulcanization methods, the dry cycle, that is, the removal of the vulcanized tire from the mold or the mounting of the next green tire on the mold, etc., the mold is opened and then closed. Even when the jacket temperature was kept constant, the mold temperature was unavoidably lowered during the time required for the state. For this reason, when the vulcanization is started from the open state to the closed state after the next green tire is mounted on the mold, it takes time to increase the mold temperature again, and the tire temperature is increased. For this reason, extra time is required, so it is necessary to set a longer vulcanization time, which deteriorates productivity.

  In addition, since the thermal expansion of molds with reduced temperature is small, there is a risk that a minute space will be generated on the mating surface between the molds when the molds are changed from the open state to the closed state. There was a risk of spewing. This overspew not only deteriorates the appearance quality but also causes abnormal sounds during use.

  These problems occur not only in the vulcanization molding of large tires but also in the vulcanization molding of small tires, but the influence is particularly great in the vulcanization molding of large tires, and improvements have been demanded.

JP 2005-186277 A

  In view of the above problems, the present invention suppresses a decrease in mold temperature even when the mold is placed in an open state (during the dry cycle), particularly in vulcanization molding of a large tire, It is an object of the present invention to provide a tire vulcanization method that can suppress deterioration of productivity and suppress over spew of a vulcanized tire to obtain a tire product with stable quality.

The tire vulcanizing method according to the present invention includes:
A tire vulcanizing method for vulcanizing a large green tire,
When vulcanizing the green tire by setting the temperature of the container jacket of the vulcanization mold to a predetermined reference temperature,
In addition to the time from the end of vulcanization of the previous tire to the start of vulcanization of the next tire, a predetermined time within 15 minutes before the end of vulcanization of the previous tire and / or after the start of vulcanization of the next tire The temperature of the container jacket is increased by 2 to 7 ° C. from the predetermined reference temperature for a predetermined time within 10 minutes.

And the vulcanization method of the said tire is
The predetermined reference temperature is 140 to 155 ° C.

The tire vulcanizing method is
The predetermined reference temperature is 150 ± 5 ° C.

Further, the tire vulcanizing method is:
The predetermined reference temperature is 150 ± 1 ° C.

  According to the tire vulcanization method of the present invention, in the vulcanization molding of a large tire, when the mold is placed in an open state from the end of the vulcanization of the previous tire to the start of vulcanization of the next tire ( Even during the dry cycle), a decrease in mold temperature can be suppressed. As a result, it is possible to suppress the deterioration of productivity, to suppress the occurrence of overspew in the vulcanized tire, and to obtain a tire product with stable quality.

It is a schematic sectional drawing which shows typically the internal structure of the split mold which comprises a tire vulcanizer. It is a schematic diagram explaining the change of the jacket temperature in the tire vulcanization molding process of an experiment example. It is a figure which shows typically the metal mold | die temperature and the change of tire temperature in the continuous vulcanization | cure process of the tire of an experiment example.

  Hereinafter, the present invention will be described based on embodiments. Note that the present invention is not limited to the following embodiments. Various modifications can be made to the following embodiments within the same and equivalent scope as the present invention.

  The present embodiment is an example in which a tire vulcanizing apparatus having a mold A shown in FIG. 1 is used to vulcanize a tire having a tire size of 11R22.5 (for trucks and buses). (Hereinafter, simply referred to as “jacket temperature”) is a predetermined reference temperature (hereinafter referred to as “jacket reference value”), specifically, a predetermined value with respect to 150 ° C. empirically determined in the vulcanization of the tire. This is an embodiment in which vulcanization is carried out by raising the temperature by a predetermined temperature, specifically, the time for opening the vulcanizer, and the time obtained by adding the specific time before and after the time to the above time. For comparison, vulcanization with the jacket temperature kept constant according to the jacket reference value and vulcanization with the jacket temperature increased to a temperature defined by the present invention or higher were also performed.

(Comparative Example 1)
In Comparative Example 1, the jacket temperature during the vulcanization operation is kept constant according to the jacket reference value in accordance with predetermined vulcanization conditions that have been conventionally performed, so that a predetermined vulcanization amount can be obtained. This is an example of continuous vulcanization of green tires.

  Specifically, the jacket temperature was set to 150 ° C. and the raw tire was continuously vulcanized. During the vulcanization operation, the jacket temperature was controlled so as to maintain the initial set temperature of 150 ° C. even when the tire was changed upon completion of vulcanization, that is, when the vulcanizer was open.

  The relationship between the jacket temperature and the vulcanization process in the continuous vulcanization process of the tire described above is shown in FIG. In FIG. 2A, the upper part shows the jacket temperature, and the lower part shows the progress of the continuous vulcanization process. As shown in FIG. 2A, in Comparative Example 1, the jacket temperature is equal and constant when the vulcanizer is open and during tire vulcanization.

Example 1
In Example 1, the jacket reference value is set to 150 ° C., which is the same as that of Comparative Example 1, and the jacket temperature is set at the time of tire replacement accompanying the completion of vulcanization, that is, the time from the vulcanization device to the closed state. The raw tire was continuously vulcanized in the same manner as Comparative Example 1 except that the temperature was raised by 2 ° C. from the reference value, that is, 150 ° C.

(Example 2)
In Example 2, the jacket reference value is set to 150 ° C., which is the same as that in Comparative Example 1, and the vulcanization is started in addition to the time when the tire is changed upon completion of vulcanization, that is, from the time when the vulcanizer is brought into the closed state. The raw tire was continuously vulcanized in the same manner as in Comparative Example 1 except that the jacket temperature was raised by 4 ° C. from the jacket reference value, that is, 150 ° C. for 5 minutes after the completion and 7 minutes before the end of vulcanization.

  The relationship between the jacket temperature and the vulcanization process in the continuous vulcanization process of the tire of Example 2 is shown in FIG. As in FIG. 2A, the upper part shows the jacket temperature, and the lower part shows the progress of the continuous vulcanization process.

(Comparative Example 2)
In Comparative Example 2, the raw tire was continuously vulcanized in the same manner as in Example 2 except that the jacket temperature was raised by 8 ° C. from the jacket reference value.

(Measurement item)
For each comparative example and example, during the continuous vulcanization, the minimum mold temperature at the time of tire replacement, the tire temperature one minute after the start of vulcanization, the required vulcanization time, and the maximum tire temperature during vulcanization It was measured. In addition, the presence or absence of occurrence of overspew in the tire after vulcanization was visually confirmed. Further, the wear performance of the tire after vulcanization was measured. The wear performance was measured by the Lambone wear test method.

(Measurement result)
Table 1 summarizes the conditions relating to the jacket temperature of each comparative example and example. The measurement results are shown in Table 2. In Table 2, the minimum mold temperature at the time of tire replacement (when the vulcanizer is open), the tire temperature 1 minute after the start of vulcanization, and the vulcanization time, respectively, with the measured values in Comparative Example 1 as reference values, The difference from the reference value is shown. The tire maximum temperature during vulcanization is indicated by the difference from the actual measurement value with the management temperature in Comparative Example 1 as the reference value. Further, the wear performance of the tire after vulcanization is indicated by an index when the measured value in Comparative Example 1 is set to 100.

  From the results shown in Table 2, by increasing the jacket temperature by 2 to 8 ° C. at least for the time from the vulcanization device to the closed state (Example 1, Example 2, Comparative Example 2), It can be seen that the mold temperature can be prevented from lowering when the vulcanizer is open, and that the tire temperature can be raised quickly even after vulcanization is started. And the tire maximum temperature during vulcanization also becomes high, and as a result, it can be seen that vulcanization time can be reduced, especially in Example 2 and Comparative Example 2, which can be sufficiently reduced.

  Furthermore, in the case of Example 1, Example 2, and Comparative Example 2, there was no occurrence of overspew, and in Examples 1 and 2, sufficient wear performance could be obtained. The reason why sufficient abrasion performance could not be obtained in Comparative Example 2 was that the jacket temperature was raised by 8 ° C., so that the tire maximum temperature during vulcanization became too high, and an optimum vulcanization state was obtained. It is presumed that there was not.

  FIG. 3 shows changes in mold temperature and tire temperature in Comparative Example 1 and Example 2. In FIG. 3, the broken line indicates Comparative Example 1 and the solid line indicates Example 2.

  As shown in FIG. 3, compared to Comparative Example 1, in Example 2, it is possible to suppress a decrease in mold temperature at the start of vulcanization. As a result, since the temperature rise of the tire can be accelerated after the start of vulcanization, the vulcanization time can be shortened.

  As described above, by raising the jacket temperature by 2 ° C. or more from the reference value for a predetermined time, it is possible to suppress the occurrence of overspew and to shorten the vulcanization time. If the temperature rise is less than 2 ° C., the effect of raising the jacket temperature cannot be obtained. In addition, as described above, the wear performance decreases at an elevated temperature of 8 ° C. For this reason, 2-7 degreeC is suitable as a raise temperature. Further, in order to perform vulcanization promptly and not adversely affect the performance of the tire, the reference temperature is preferably 150 ± 5 ° C., more preferably 150 ± 1 ° C.

  As described above, in order to exhibit the effect of suppressing the decrease in the mold temperature by increasing the jacket temperature, it is necessary to set the jacket temperature increase time to at least the time for opening the vulcanizer. And in order to exhibit the effect which suppresses the fall of metal mold | die temperature more, as above-mentioned, in addition to the time of vulcanization | cure apparatus opening time, jacket temperature is raised also in the specific time before and behind the said time. It is preferable. The specific time is preferably a time obtained by adding a predetermined time within 15 minutes before the end of vulcanization of the tire and / or a predetermined time within 10 minutes after the start of vulcanization of the next tire. If the time to be raised before the vulcanization of the tire exceeds 15 minutes or the time to be raised after the start of tire vulcanization exceeds 10 minutes, the temperature of the tire will increase excessively, and the tire performance may be adversely affected. For this reason, it is necessary to avoid raising over the above time.

  As described above, in the present embodiment, the container jacket temperature is increased to suppress the decrease in the mold temperature, but the platen jacket temperature may be increased at the same time to suppress the decrease in the mold temperature. In this case, the rising temperature is preferably about 1 to 4 ° C.

A Mold B Container 1 Upper side mold 2 Lower side mold 3 Tread segment 4 Upper platen board 5 Lower platen board 6 Sector shoe 7 Actuator 8 Container jacket 9 Platen jacket

Claims (4)

A tire vulcanizing method for vulcanizing a large green tire,
When vulcanizing the green tire by setting the temperature of the container jacket of the vulcanization mold to a predetermined reference temperature,
In addition to the time from the end of vulcanization of the previous tire to the start of vulcanization of the next tire, a predetermined time within 15 minutes before the end of vulcanization of the previous tire and / or after the start of vulcanization of the next tire A tire vulcanizing method, wherein the temperature of the container jacket is increased by 2 to 7 ° C from the predetermined reference temperature for a predetermined time within 10 minutes.   The tire vulcanizing method according to claim 1, wherein the predetermined reference temperature is 140 to 155 ° C.   The tire vulcanizing method according to claim 1, wherein the predetermined reference temperature is 150 ± 5 ° C.   The tire vulcanizing method according to claim 1, wherein the predetermined reference temperature is 150 ± 1 ° C.

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