JP4735124B2 - Pneumatic tire manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic tire, and more particularly, to a method for manufacturing a pneumatic tire that effectively improves poor rubber flow during vulcanization.

  Generally, in the production of pneumatic tires, when a molded green tire (unvulcanized tire) is vulcanized, a green tire set in a mold of a vulcanizer is blown with a vulcanizing bladder that is inflated with a predetermined internal pressure. It is pressed from the inside and pressed against the inner surface of the mold for vulcanization.

  The inflating vulcanizing bladder first contacts the crown portion of the green tire, then contacts the sidewall portion, and then contacts the shoulder portion to press the green tire from the inside. In a tire with a low flatness ratio, when the green tire is pressed with a bladder for vulcanization in this way, there is a problem that a rubber flow failure is likely to occur.

Therefore, a technique for changing the shape of an inflated vulcanizing bladder by adjusting the thickness of the vulcanizing bladder is known (for example, see Patent Document 1). By making the thickness of the bladder part that presses the sidewall part thinner than the thickness of the bladder part that presses the tread part, the vulcanizing bladder to be inflated is first brought into contact with the sidewall part side, and then on the tread part. The green tire can be pressed from the inside by abutting. As a result, the carcass layer extending to the bead portion can be fixed first on the bead portion side, so that the green tire can easily follow the mold shape and suppress the occurrence of poor rubber flow during vulcanization. It becomes possible. However, a tire with a low flatness that complicates the change in curvature of the side profile line is insufficient in improving the rubber flow failure, and further improvement has been demanded.
Japanese Patent Laid-Open No. 2003-231128

  The objective of this invention is providing the manufacturing method of the pneumatic tire which can improve the rubber | gum flow defect at the time of vulcanization effectively.

  The method for producing a pneumatic tire of the present invention that achieves the above object is to press a green tire set in a mold of a vulcanizer from the inside with a vulcanizing bladder inflated with a predetermined internal pressure and push it on the inner surface of the mold. When vulcanizing by applying a plurality of vulcanization bladders that can press the tread part and both side wall parts of the green tire independently, the internal pressure of the vulcanization bladder that presses both side wall parts is adjusted. It is characterized by being higher than the internal pressure of the vulcanizing bladder that presses the tread portion.

  According to the present invention described above, in the vulcanization step, vulcanization is performed by using a plurality of vulcanization bladders that can independently press the tread portion and both sidewall portions of the green tire and pressing both sidewall portions. By making the internal pressure of the bladder for pressure higher than the internal pressure of the vulcanizing bladder that presses the tread part, the vulcanizing bladder that presses both side wall parts is first brought into contact with both side wall parts, and both side wall parts Can be pressed against the inner surface of the mold with high pressure, and the carcass layer extending to the bead portion can be firmly fixed to the bead portion, so that the curvature change of the side portion profile line becomes complicated. Even if the tire has a low flatness ratio, the green tire can easily follow the mold shape, and it is possible to effectively improve the rubber flow failure during vulcanization.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a cross-sectional view of the main part of a vulcanization process in the method for producing a pneumatic tire of the present invention, where 1 is a vulcanizer, 2 is a mold, 3, 4 and 5 are vulcanization bladders, and T is a metal mold. A green tire (unvulcanized tire) set in the mold 2.

  The mold 2 includes an upper mold 2a for molding one sidewall portion Ta of the green tire T, a lower mold 2b for molding the other sidewall portion Tb of the green tire T, and a tread portion Tc of the green tire T. Are provided with a plurality of segments 2c and upper and lower bead rings 2d.

  The plurality of vulcanization bladders 3, 4, and 5 are each composed of a rubber layer in which a knitted fabric or a woven fabric is embedded. The vulcanization bladder 3 is formed so as to be able to press the tread portion Tc of the green tire T, and vulcanized. The bladders 4 and 5 are formed so as to be able to press both side walls Ta and Tb, respectively. When the plurality of vulcanization bladders 3, 4 and 5 are inflated by applying an internal pressure, as shown in FIG. The tread portion Tc of the tire T and both sidewall portions Ta and Tb can be pressed independently.

  Reference numeral 6 denotes a supply path for supplying the pressurized medium and the heating medium to the air chamber 5 a of the vulcanizing bladder 5, and the pressurized heating medium is supplied into the vulcanizing bladder 5 from the supply path 6 through the connection path 7. It is supposed to be. Similarly, a pressure medium and a heating medium are supplied to the air chamber 3a from a supply path (not shown) to the vulcanization bladder 3 via a connection path 8, and further to the vulcanization bladder 4 from a supply path (not shown). A pressurizing medium and a heating medium can be supplied to the air chamber 4a through the connection path 9.

Hereinafter, the manufacturing method of the pneumatic tire of this invention is demonstrated, referring FIG.
First, the green tire T is formed by the same process as the conventional one. After the obtained green tire T is set in the mold 2 of the vulcanizer 1, vulcanization is started. The vulcanization bladders 3, 4, 5 are respectively supplied with a pressurizing medium having a predetermined internal pressure and a heating medium having a predetermined temperature through the connection paths 7, 8, 9, and are inflated. Presses the green tire T from the inside and presses it against the inner surface of the mold 2.

  At this time, the pressure of the pressurized medium supplied to the vulcanizing bladders 4 and 5 that press both sidewall portions Ta and Tb is higher than the pressure of the pressurized medium supplied to the vulcanizing bladder 3 that presses the tread portion Tc. Thus, the internal pressure of the vulcanizing bladders 4 and 5 is set higher than the internal pressure of the vulcanizing bladder 3. For example, in the case of a tire for a passenger car, the internal pressure of the vulcanizing bladders 4 and 5 can be set to 2.0 to 3.0 MPa, and the internal pressure of the vulcanizing bladder 3 can be set to 1.5 to 2.0 MPa.

  As a result, the vulcanizing bladders 4 and 5 come into contact with both sidewall portions Ta and Tb, the vulcanizing bladder 3 comes into contact with the tread portion Tc, and further presses both sidewall portions Ta and Tb with high pressure. Therefore, a carcass layer (not shown) extending to the bead portion Td is firmly fixed to the bead portion Td. Preferably, after a pressurized medium is supplied to the vulcanizing bladders 4 and 5 that press both sidewall portions Ta and Tb (applying an internal pressure), the pressurized medium is applied to the vulcanizing bladder 3 that presses the tread portion Tc. Supply (apply internal pressure) is good.

  The vulcanization bladders 3, 4 and 5 may be supplied with a heating medium having the same temperature. Preferably, the vulcanization bladders 4 and 5 for pressing both sidewall portions Ta and Tb are provided with It is preferable to supply a heating medium having a temperature lower than that of the heating medium supplied into the vulcanizing bladder 3 that presses the tread portion Tc. For example, the temperature of the heating medium supplied into the vulcanizing bladder 3 that presses the tread portion Tc is 220 ° C., and the temperature of the heating medium that is supplied into the vulcanizing bladders 4 and 5 that press both sidewall portions Ta and Tb. Is 180 ° C.

  Usually, since the tread portion of the tire is thicker than the sidewall portion, when vulcanized at a single temperature, vulcanization is performed until the vulcanization of the tread portion is completed, and thus the sidewall portion becomes overvulcanized. Therefore, by reducing the temperature of the heating medium supplied into the vulcanization bladders 4 and 5 that press both side wall portions Ta and Tb, the overvulcanization of the side wall portions can be avoided and the crosslink density can be made uniform. Is possible.

  After the vulcanization is completed, the vulcanized tire is taken out from the vulcanizer 1 to complete the production of the pneumatic tire.

  According to the present invention described above, a plurality of vulcanization bladders 3, 4, and 5 capable of independently pressing the tread portion Tc and both sidewall portions Ta and Tb of the green tire T are used in the vulcanization process. In order to make the internal pressure of the vulcanizing bladders 4 and 5 that press both side wall portions Ta and Tb higher than the internal pressure of the vulcanizing bladder 3 that presses the tread portion Tc, a carcass layer (not non-circular) extends to the bead portion Td. (Shown) can be firmly fixed to the bead portion Td, so that even if the tire has a low flatness that complicates the change in the curvature of the side portion profile line, the green tire can easily follow its mold shape. It is possible to effectively improve poor rubber flow during vulcanization.

  FIG. 2 shows another example of the vulcanization process in the method for manufacturing a pneumatic tire according to the present invention, and a plurality of vulcanization bladders that can be pressed independently of each other to press both sidewall portions Ta and Tb. The vulcanization bladders 11 and 12 and the vulcanization bladder 13 that presses the crown portion Te of the tread portion Tc and the vulcanization bladders 14 and 15 that press both shoulder portions Tf are used. Same as 1. In FIG. 2, the thickness of the adjacent bladder portion is omitted, and the drawing is simplified.

  When vulcanizing using such vulcanizing bladders 11, 12, 13, 14, and 15, the pressure of the pressurized medium supplied to the vulcanizing bladders 11 and 12 that press both sidewall portions Ta and Tb. Is made higher than the pressure of the pressurized medium supplied to the vulcanizing bladders 13, 14, 15.

  Further, when the temperature of the heating medium supplied to the vulcanizing bladders 11, 12, 13, 14, and 15 is made different, the vulcanizing bladders 14 that press both shoulder portions Tf that are usually thickest are usually used. The temperature of the heating medium supplied to 15 is the highest, and then the temperature of the heating medium supplied to the vulcanizing bladder 13 that presses the crown portion Te where the thickness is increased is increased, and both the sidewall portions Ta and Tb are pressed. The temperature of the heating medium supplied to the vulcanizing bladders 11 and 12 is made the lowest. However, in the case where rubber whose vulcanization progress speed is faster than that of the rubber of both side wall portions Ta and Tb is used for the crown portion Te, the vulcanizing bladder from the temperature of the heating medium supplied to the vulcanizing bladders 11 and 12 The temperature of the heating medium supplied to 13 is lowered.

  In the present invention, the plurality of vulcanization bladders are configured as independent single bladders as described above, and the single vulcanization bladder is divided into a plurality of air chambers by partition walls. In addition, it shall be regarded as a plurality of vulcanizing bladders. For example, if a single vulcanizing bladder is divided into three air chambers, it shall have three vulcanizing bladders, and the number of air chambers filled with a pressurized heating medium will be the number of vulcanizing bladders. And

  The present invention can be preferably used for producing a pneumatic tire having an aspect ratio of 55% or less, but is not limited thereto.

It is principal part sectional drawing of the vulcanization | cure process in the manufacturing method of the pneumatic tire of this invention. It is principal part sectional drawing which shows the other example of the vulcanization | cure process in the manufacturing method of the pneumatic tire of this invention.

Explanation of symbols

1 Vulcanizer 2 Mold 3, 4, 5 Vulcanization bladder 11, 12, 13, 14, 15 Vulcanization bladder T Green tire Ta, Tb Side wall portion Tc Tread portion

Claims (3)

  When a green tire set in a mold of a vulcanizer is pressed from the inside by a vulcanizing bladder that is inflated with a predetermined internal pressure and pressed against the inner surface of the mold, the tread and both sides of the green tire are vulcanized. Use multiple vulcanizing bladders that can press the wall part independently, and make the internal pressure of the vulcanizing bladder that presses both side wall parts higher than the internal pressure of the vulcanizing bladder that presses the tread part. Tire manufacturing method.   The method for producing a pneumatic tire according to claim 1, wherein an internal pressure is applied to the vulcanizing bladder that presses the tread portion after an internal pressure is applied to the vulcanizing bladder that presses the both sidewall portions. The vulcanization bladder that presses both the side wall portions is vulcanized by supplying a heating medium having a temperature lower than that of the heating medium supplied to the vulcanization bladder that presses the tread portion. The manufacturing method of the pneumatic tire of description.

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