JP2019010780A - Method for manufacturing tire vulcanization bladder - Google Patents

Abstract

To provide a method for manufacturing a bladder for vulcanizing tire which makes it possible to improve bladder productivity by effectively utilizing existing equipment and to improve quality of bladder to be obtained.SOLUTION: In a method of manufacturing a bladder for vulcanizing tire, a metal mold 1 is used which has an outer mold 2 for molding an outer surface of a tire vulcanization bladder 10 having a cylindrical shape or a closed bag shape at one end and a core 3 for molding an inner surface of the tire vulcanization bladder 10, with the outer mold 2 divided into a lower mold 4 and an upper mold 5, and an unvulcanized rubber is arranged in an annular material arrangement space 6 formed between the lower mold 4 and the upper mold 5 and the unvulcanized rubber is introduced into a cavity 7 between the outer mold 2 and the core 3 based on a compression force at a time of mold closing. The unvulcanized rubber is heated to a temperature lower than a mold temperature at a time of vulcanization and preformed into an annular molded body 11 that can be accommodated in the material arrangement space 6, and the annular molded body 11 is loaded into the annular material arrangement space 6, and the upper mold 5 is pressed toward the lower mold 4 to vulcanize the annular molded body 11 while the metal mold 1 is closed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a bladder for tire vulcanization by compression molding, and more specifically, a tire that can improve the quality of the resulting bladder while improving the productivity of the bladder by effectively utilizing existing equipment. The present invention relates to a method for manufacturing a vulcanizing bladder.

  As a method for manufacturing a bladder for tire vulcanization, vulcanization by compression molding is widely performed. This compression molding has an outer mold that molds the outer surface of a tire vulcanizing bladder that has a cylindrical shape or a bag shape with one end closed, and a core that molds the inner surface of the tire vulcanizing bladder. Using a mold divided into a lower mold and an upper mold, and a predetermined amount of string-like body made of unvulcanized rubber in an annular material arrangement space formed between the lower mold and the upper mold The unvulcanized rubber is introduced into the cavity between the outer mold and the core based on the compression force when the mold is closed, and vulcanized in a state where the entire area of the cavity is filled with unvulcanized rubber. (For example, refer to Patent Document 1).

  However, when a tire vulcanizing bladder is manufactured by compression molding, it is complicated to load a string-like body made of unvulcanized rubber into a material arrangement space between the lower mold and the upper mold so that a predetermined amount is obtained. In addition, there is a disadvantage that the weight distribution in the circumferential direction of the bladder becomes uneven when the unvulcanized rubber is loaded. In addition, since unvulcanized rubber with high viscosity moves in the cavity while in contact with the mold surface when the mold is closed, it takes a long time to fill the unvulcanized rubber. Therefore, the temperature of the part on the material supply side of the mold becomes relatively low, and the temperature distribution of the rubber before vulcanization becomes non-uniform. And if the vulcanization starts partly before the rubber temperature becomes uniform, there is a problem that residual strain is generated in the bladder, resulting in a deterioration in quality such as non-uniform gauge and a decrease in yield. .

  In order to increase the productivity of bladders by making effective use of existing equipment, it is effective to increase the vulcanization temperature. However, when the vulcanization temperature is increased, a rubber film that has been gelled on the mold surface is formed. There are problems that the quality of the bladder deteriorates due to peeling from the mold surface and mixing into the rubber, and that the temperature distribution of the rubber is made non-uniform.

JP 2011-161830 A

  An object of the present invention is to provide a method for producing a bladder for tire vulcanization, which makes it possible to improve the quality of the resulting bladder while improving the productivity of the bladder by effectively utilizing existing equipment.

In order to achieve the above object, the tire vulcanization bladder manufacturing method of the present invention comprises a cylindrical shape or an outer mold for molding an outer surface of a tire vulcanization bladder having a bag shape with one end closed, and the tire vulcanization. An annular surface formed between the lower mold and the upper mold using a mold in which the outer mold is divided into a lower mold and an upper mold. Method for manufacturing a tire vulcanizing bladder in which unvulcanized rubber is arranged in a material arrangement space, and the unvulcanized rubber is introduced into a cavity between the outer mold and the core based on a compressive force when the mold is closed In
Uncured rubber is heated at a temperature lower than the mold temperature at the time of vulcanization and preformed into an annular molded body that can be accommodated in the material placement space, and the annular shape is placed in the annular material placement space. The molded body is loaded, and the upper mold is pressurized toward the lower mold, and vulcanization is performed with the mold closed.

  In the present invention, by pre-molding the unvulcanized rubber into an annular molded body that can be accommodated in the material arrangement space, the annular molded body can be loaded in a short time into the annular material arrangement space. It is possible to make the weight distribution in the circumferential direction of the bladder uniform when the unvulcanized rubber is loaded. In addition, prior to loading into the mold, the unvulcanized rubber is heated at a temperature lower than the mold temperature during vulcanization, so the viscosity of the unvulcanized rubber is reduced and the filling time into the cavity is reduced. While shortening, vulcanization time can be shortened. Further, since the unvulcanized rubber is prevented from taking heat from the inner surface of the mold when the unvulcanized rubber is filled into the cavity, the temperature distribution of the rubber before vulcanization can be made uniform. As a result, residual strain is less likely to occur in the bladder, and the quality and yield of the bladder can be improved. Furthermore, since the unvulcanized rubber is discharged from the material placement space and smoothly flows in the cavity, the rubber film that has been gelled on the mold surface is prevented from being peeled off from the mold surface and mixed into the rubber. Therefore, it is possible to avoid the deterioration of the quality caused by it. As a result, it is possible to increase the productivity of the bladder by effectively utilizing the existing equipment and improve the quality of the obtained bladder.

  In the present invention, unvulcanized rubber is a temperature at which the difference from the mold temperature during vulcanization is 100 ° C. or less, more preferably at a temperature at which the difference from the mold temperature during vulcanization is 60 ° C. or less. It is preferable to preliminarily form an annular molded body that can be heated and accommodated in the material arrangement space. Thus, the quality of the resulting bladder can be improved by bringing the temperature of the unvulcanized rubber at the time of preforming close to the mold temperature at the time of vulcanization.

It is meridian sectional drawing which shows the metal mold | die (half-open state) used with the manufacturing method of the bladder for tire vulcanization | cure which concerns on this invention. It is meridian sectional drawing which shows the metal mold | die (closed mold state) used with the manufacturing method of the bladder for tire vulcanization | cure which concerns on this invention. It is a perspective view which shows the annular molded object which consists of unvulcanized rubber used with the manufacturing method of the bladder for tire vulcanization | cure which concerns on this invention. It is meridian sectional drawing which shows the injection molding apparatus for shape | molding the annular molded object which consists of unvulcanized rubber. It is sectional drawing which expands and shows the peripheral part of the material arrangement | positioning space of the metal mold | die of FIG. It is meridian sectional drawing which shows the cylindrical tire vulcanization bladder obtained by the present invention. It is meridian sectional drawing which shows the bag-shaped tire vulcanization bladder closed at one end obtained by the present invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG.1 and FIG.2 shows the metal mold | die used with the manufacturing method of the bladder for tire vulcanization | cure which concerns on this invention. As shown in FIGS. 1 and 2, the mold 1 includes an outer mold 2 that molds the outer surface of a tire vulcanizing bladder 10 that has a cylindrical shape or a bag shape with one end closed, and a tire vulcanizing bladder 10. The outer die 2 is divided into a lower die 4 and an upper die 5.

  In the half-open state of the mold 1 as shown in FIG. 1, an annular material arrangement space 6 is formed between the lower mold 4 and the upper mold 5. That is, the lower mold 4 forms the bottom surface and the outer peripheral surface of the material arrangement space 6, and the upper mold 5 forms the upper surface of the material arrangement space 6. Therefore, the unvulcanized rubber arranged in the material arrangement space 6 has a cavity 7 between the outer mold 2 and the core 3 based on the compression force when the upper mold 5 is pressurized toward the lower mold 4. Will be introduced. Further, a convex portion 8 is formed on the mating surface of the upper mold 5 so as to protrude downward at a portion on the cavity 7 side. By becoming narrower, it functions as a gate of the material arrangement space 6. Further, the lower mold 4 and the upper mold 5 are formed with surplus rubber receiving portions 9 communicating with the cavities 7 at the upper and lower end portions of the mating surfaces. The surplus rubber receiving portions 9 overflowed from the cavities 7. It is designed to accommodate surplus rubber.

  When manufacturing the tire vulcanizing bladder 10 using the mold 1 as described above, first, as shown in FIG. 3, unvulcanized rubber heated at a temperature lower than the mold temperature at the time of vulcanization. An annular molded body 11 that is configured of R and can be accommodated in the material arrangement space 6 and has no joints is precisely preformed. When the annular molded body 11 is precisely formed, it is desirable that the fluctuation width of the cross-sectional area in the meridian section of the annular molded body 11 is small along the circumferential direction of the molded body 11, for example, the minimum value of the cross-sectional area It is desirable that the ratio of the difference between the minimum value and the maximum value is 3% or less.

  Although the method of preforming the annular molded body 11 is not particularly limited, for example, an injection molding apparatus 20 as shown in FIG. 4 can be used. The injection molding apparatus 20 includes a preforming mold 23 composed of a lower mold 21 and an upper mold 22 and an injection apparatus 24 for injecting unvulcanized rubber R. The lower mold 21 includes an annular cavity 25 corresponding to the annular molded body 11, and the upper mold 22 includes a plurality of rubber flow paths 26 communicating with the cavity 25 from the outside. The annular molded body 11 can be molded by injecting the heated unvulcanized rubber R from the injection device 24 and filling the cavity 25 via any of the rubber flow paths 26. .

  Next, the annular molded body 11 molded as described above is taken out from the preforming mold 23 and loaded into the annular material arrangement space 6 of the mold 1, and then the upper mold 5 is directed toward the lower mold 4. Pressurize and close the mold 1. As a result, the unvulcanized rubber R constituting the molded body 11 is introduced into the cavity 7 between the outer mold 2 and the core 3 based on the compression force at the time of closing. In this way, by vulcanizing the mold 1 while the mold 1 is closed, the vulcanized tire vulcanizing bladder 10 can be formed in the cavity 7.

  In the manufacturing method of the tire vulcanizing bladder 10 described above, the unvulcanized rubber R is preformed into an annular molded body 11 that can be accommodated in the material arrangement space 6. Thus, the annular molded body 11 can be loaded in a short time, and the weight distribution in the circumferential direction of the bladder when the unvulcanized rubber R is loaded can be made uniform. That is, when a string-like body made of unvulcanized rubber is cut into a predetermined length and loaded into the material arrangement space 6 as in the prior art, the string-like body needs to be wound around the material arrangement space 6 a plurality of times. In addition, since the number of turns of the string-like body varies depending on the position in the circumferential direction of the material arrangement space 6, the weight distribution in the circumferential direction of the unvulcanized rubber R becomes uneven. On the other hand, it is possible to load the unvulcanized rubber R with a simple and uniform weight distribution by preparing an annular molded body 11 having no joints.

  Prior to loading into the mold 1, the unvulcanized rubber R is heated at a temperature lower than the mold temperature at the time of vulcanization, so that the viscosity of the unvulcanized rubber R is lowered to enter the cavity 7. As well as shortening the filling time, the vulcanization time can be shortened. That is, the unvulcanized rubber R having a reduced viscosity rapidly diffuses to every corner of the cavity 7 based on the compression force at the time of mold closing, so that the filling time is shortened, and the unvulcanized rubber R is already Since it is heated, the vulcanization time can be set shorter than in the unheated state.

  Furthermore, since the unvulcanized rubber R has already been heated, the unvulcanized rubber R may take heat from the inner surface (molding surface) of the mold 1 when the unvulcanized rubber R is filled into the cavity 7. It is suppressed. Therefore, the temperature distribution of the unvulcanized rubber R can be made uniform in a state where the unvulcanized rubber R before vulcanization has spread to every corner of the cavity 7. As a result, it is difficult for residual distortion to occur in the bladder 10, and the quality and yield of the bladder 10 can be improved.

  Further, since the unvulcanized rubber R is discharged from the material arrangement space 6 and smoothly flows in the cavity 7, for example, as shown in FIG. 5, the rubber film R1 in which gelation has progressed to the surface of the material arrangement space 6 Is formed, the unvulcanized rubber R that has not been gelled is preferentially extruded from the material arrangement space 6, and the rubber film R1 is prevented from being mixed into the unvulcanized rubber R. be able to. When the rubber film R1 (that is, the heat-degraded rubber piece) is mixed in the bladder 10, cracks starting from the interface easily occur. However, by promoting the flow of the unvulcanized rubber R, the rubber film R1 It is possible to avoid deterioration in quality due to the above.

  According to the manufacturing method of the tire vulcanization bladder 10 described above, it is possible to improve the quality of the obtained tire vulcanization bladder 10 while improving the productivity of the tire vulcanization bladder 10 by effectively utilizing existing equipment. It becomes possible.

  According to the manufacturing method of the tire vulcanization bladder 10 described above, a tire vulcanization bladder 10 having a cylindrical shape can be obtained as shown in FIG. By the same manufacturing method, as shown in FIG. 7, it is also possible to obtain a tire vulcanizing bladder 10 having a bag shape with one end closed. In any case, the obtained tire vulcanizing bladder 10 has a uniform gauge and excellent durability.

  In the method for manufacturing the tire vulcanization bladder 10 described above, a temperature lower than the set temperature (vulcanization temperature) of the mold 1 during vulcanization of the unvulcanized rubber R (that is, the temperature at which the crosslinking reaction does not substantially proceed). ). In particular, the temperature of the unvulcanized rubber R is lower than the set temperature of the mold 1 during vulcanization and the difference from the set temperature of the mold 1 during vulcanization is 100 ° C. or less, more preferably vulcanized. An annular molded body that is warmed at a temperature that is lower than the set temperature of the mold 1 at the time and that is different from the set temperature of the mold 1 at the time of vulcanization by 60 ° C. or less, and can be accommodated in the material arrangement space. 11 may be preformed. In this way, by bringing the temperature of the unvulcanized rubber R at the time of pre-molding close to the set temperature of the mold 1 at the time of vulcanization, the unvulcanized rubber R becomes gold when filling the cavity 7 with the unvulcanized rubber R. Since deprivation of heat from the inner surface of the mold 1 is suppressed, the temperature distribution of the unvulcanized rubber R in the state before vulcanization can be made uniform, and the quality of the resulting bladder can be improved.

  The difference between the temperature when heating the unvulcanized rubber R and the set temperature of the mold 1 during vulcanization is preferably 40 ° C. or more. This is because if the temperature at which the unvulcanized rubber R is heated is too close to the set temperature (vulcanization temperature) of the mold 1, vulcanization proceeds before filling the cavity 7. For example, since the vulcanization temperature is generally 180 ° C. to 200 ° C., the temperature for heating the unvulcanized rubber R may be 80 ° C. to 150 ° C., more preferably 120 ° C. to 150 ° C.

  A gold having an outer mold for molding the outer surface of a cylindrical tire vulcanization bladder and a core for molding the inner surface of the tire vulcanization bladder, the outer mold being divided into a lower mold and an upper mold A mold is used, an unvulcanized rubber is arranged in an annular material arrangement space formed between the lower mold and the upper mold, and the outer mold and the core are arranged on the basis of the compression force when the unvulcanized rubber is closed. In the method for manufacturing a tire vulcanizing bladder introduced into the cavity between the vulcanized rubber and the vulcanized rubber, the conditions for loading unvulcanized rubber into the material arrangement space are varied as shown in Table 1 (Examples). 1-4 and comparative example).

Examples 1-4:
The unvulcanized rubber is heated at a temperature lower than the mold temperature at the time of vulcanization, pre-formed into an annular molded body by a precision injection molding device, and the annular molded body is loaded into the material arrangement space of the mold. Then, vulcanization was performed for a predetermined vulcanization time.

Comparative example:
Unvulcanized rubber is preformed into a string-shaped molded body by an extrusion molding device, and the string-shaped molded body is cut to a required length without heating, and then the cut piece is used as a mold material. It was loaded into the arrangement space and vulcanized for a predetermined vulcanization time.

  About the manufacturing method of the bladder for tire vulcanization concerning Examples 1-4 mentioned above and a comparative example, while measuring the loading time at the time of loading the preforming object which consists of unvulcanized rubber in the material arrangement space of a metallic mold, The thickness accuracy pass rate of the bladder and the average life of the bladder were evaluated by the following evaluation methods, and the results are also shown in Table 1.

Bladder thickness accuracy pass rate:
For 10 bladders obtained by each method, the film thickness of the bladder was measured at 20 locations per piece, and the percentage (%) of locations that satisfied the allowable thickness was determined.

Bladder life expectancy:
The 10 bladders obtained by each method are installed in a pneumatic tire vulcanizer, the pneumatic tire is repeatedly vulcanized, and the number of vulcanization times until it becomes unusable is measured. Asked.

  As can be seen from Table 1, in the tire vulcanizing bladder manufacturing method of Example 1, the unvulcanized rubber was heated at a temperature lower than the mold temperature at the time of vulcanization and preformed into an annular molded body. However, since the annular molded body is loaded in the annular material arrangement space, the thickness accuracy pass rate of the obtained bladder is high in comparison with the comparative example, and the average life of the bladder is long. It was. Further, in the method for manufacturing the tire vulcanization bladder of Example 1, not only the vulcanization time of the bladder but also the loading time of the preform is shortened, so the overall productivity is about 1.7 times that of the comparative example. It was.

  Further, in Examples 2 to 4 in which the pre-molding temperature of the unvulcanized rubber was higher than that in Example 1, there was an advantage that the vulcanization time could be shortened or the average life of the bladder was increased. . That is, in Example 2, since the preforming temperature was increased while keeping the vulcanization temperature the same as in Example 1, the vulcanization time could be shortened. In Example 3, since the preforming temperature was increased while the vulcanization temperature was lower than that in Example 1, the average life of the bladder was increased. In Example 4, the preforming temperature was increased while the vulcanization temperature was higher than that in Example 1, so that the average life of the bladder was reduced, but the vulcanization time could be significantly shortened.

DESCRIPTION OF SYMBOLS 1 Mold 2 Outer mold | type 3 Core 4 Lower mold | type 5 Upper mold | type 6 Material arrangement space 7 Cavity 8 Convex part 9 Surplus rubber receiving part 10 Tire vulcanization bladder 11 Molded object 20 Injection molding apparatus R Unvulcanized rubber

Claims (3)

An outer mold for forming an outer surface of a tire vulcanizing bladder having a cylindrical shape or a bag shape with one end closed; and a core for molding an inner surface of the tire vulcanizing bladder, wherein the outer mold is a lower mold A mold divided into an upper mold and an upper mold is used, an unvulcanized rubber is disposed in an annular material arrangement space formed between the lower mold and the upper mold, and the unvulcanized rubber is closed In a method of manufacturing a tire vulcanizing bladder to be introduced into a cavity between the outer mold and the core based on a compressive force at the time,
Uncured rubber is heated at a temperature lower than the mold temperature at the time of vulcanization and preformed into an annular molded body that can be accommodated in the material placement space, and the annular shape is placed in the annular material placement space. A method for producing a tire vulcanizing bladder is provided, wherein the molded body is loaded, the upper mold is pressed toward the lower mold, and vulcanization is performed with the mold closed.   The unvulcanized rubber is preliminarily molded into an annular molded body that can be accommodated in the material arrangement space by heating at a temperature at which the difference from the mold temperature during vulcanization is 100 ° C. or less. The manufacturing method of the tire vulcanization bladder according to claim 1.   The unvulcanized rubber is preliminarily molded into an annular molded body that can be accommodated in the material arrangement space by heating at a temperature at which the difference from the mold temperature during vulcanization is 60 ° C. or less. The manufacturing method of the tire vulcanization bladder according to claim 1.

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