JP2013111859A - Vulcanization-shaping method for pneumatic tire for passenger car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vulcanization-shaping method for a pneumatic tire for a passenger car by which a pneumatic tire for a passenger car having excellent outward appearances and quality can be produced by preventing rubber-biting even when a raw cover lower part has high rigidity.SOLUTION: There is provided the vulcanization-shaping method for a pneumatic tire for a passenger car that performs vulcanization-shaping of a raw cover using a vulcanization device including a vulcanization mold constituted of a plurality of molds including a segment mold and a side mold. The vulcanization-shaping method for a pneumatic tire for a passenger car is characterized in that mold closing operation is temporarily stopped for 2-5 seconds in a mold closing process by the time when the distance between a joint surface of the segment mold and a joint surface of the side mold becomes zero, and then restarted.

Description

  The present invention relates to a vulcanization shaping method for passenger car pneumatic tires used for raw cover vulcanization molding.

  A pneumatic tire such as a pneumatic tire for a passenger car is generally manufactured through a process of vulcanizing and shaping a raw cover (unvulcanized tire). FIG. 2 is a diagram for explaining a vulcanization shaping method, and is a cross-sectional view showing an example of a configuration of a vulcanization mold used for vulcanization shaping. As shown in FIG. 2, the vulcanization mold 1 includes a pair of upper and lower segment molds 2, a side mold 3 and a bead ring 4. 5 is a bladder.

  The vulcanization shaping is performed by mounting the raw cover T inside the vulcanizing mold 1, applying internal pressure to the bladder 5 and heating the raw cover T against the cavity surface of the vulcanizing mold 1.

  In vulcanization shaping, when the vulcanization mold 1 is closed (when the mold is closed), for example, the raw cover is engaged (rubber engagement) between the joint surface of the segment mold 2 and the joint surface of the side mold 3. May occur.

  In order to prevent such a rubber biting of the low cover, for example, a vulcanization that keeps the shaping pressure almost constant by discharging inert gas from the bladder in response to an increase in pressure in the bladder accompanying mold clamping. A shaping method has been proposed (for example, Patent Document 1).

JP-A-4-369534

  However, the tire vulcanization shaping method described in Patent Document 1 may not sufficiently prevent rubber biting. That is, as shown in FIG. 3, the surface Ts1 (the portion from the position where the maximum width of the raw cover reaches the bead) does not sufficiently contact the cavity surface of the side mold 3 during the mold closing operation, It may be in a state separated from the surface. In FIG. 3, Ts is the surface of the raw cover, Ts <b> 2 is the surface of the upper portion of the raw cover, and S is the gap between the joint surfaces of the segment mold 2 and the side mold 3.

  When the mold closing operation is continued in this state, the upper surface Ts2 (the portion from the buttress to the position where the maximum width of the low cover is reached) is further strongly pressed against the mold, and the segment mold 2 and the side There is a possibility that rubber biting may occur in the gap S between the joint surface of the mold 3. In particular, this tendency becomes more prominent as the rigidity of the lower cover lower portion T1 is higher.

  Accordingly, the present invention provides a method for vulcanizing and shaping a pneumatic tire for a passenger car, which can prevent a rubber bite even when the rigidity of the lower portion of the raw cover is high and can produce a pneumatic tire for a passenger car having a good appearance and quality. This is the issue.

  As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by the invention described below, and has completed the present invention.

The invention described in claim 1
A method for vulcanizing and shaping a pneumatic tire for a passenger car, wherein a raw cover is vulcanized and shaped using a vulcanizing device comprising a vulcanizing mold comprising a plurality of molds including a segment mold and a side mold,
In the mold closing step, after the mold closing operation is temporarily stopped for 2 to 5 seconds until the distance between the joint surface of the segment mold and the joint surface of the side mold becomes zero, the mold is closed. A method for vulcanizing and shaping a pneumatic tire for a passenger car, wherein the operation is resumed.

The invention according to claim 2
The temporary closing of the mold closing operation for 2 to 5 seconds is performed within a distance of 1 to 10 mm between the joint surface of the segment mold and the joint surface of the side mold. It is a vulcanization shaping method of the pneumatic tire for passenger cars of Claim 1.

The invention described in claim 3
3. The vulcanization shaping method for a pneumatic tire for a passenger car according to claim 1, wherein a pressure for pressurizing the raw cover from the inside with a bladder is 0.05 to 0.20 MPa. 4.

  ADVANTAGE OF THE INVENTION According to this invention, the vulcanization shaping method of the pneumatic tire for passenger cars which can prevent rubber | gum biting even when the low cover lower part rigidity is high can be provided.

In the vulcanization shaping method of this invention, it is sectional drawing which shows typically the state of a vulcanization metal mold | die and a raw cover when a metal mold | die closing operation is stopped temporarily. It is a figure explaining a vulcanization shaping method. It is sectional drawing which shows typically the state of the raw cover in the conventional vulcanization shaping method.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing a state of a vulcanization mold and a raw cover when a mold closing operation is temporarily stopped in the vulcanization shaping method of the present invention. In FIG. 1, 2 is a segment mold, 3 is a side mold, S is a gap between the joint surface of the segment mold 2 and the joint surface of the side mold 3, d is a distance of the gap S, Ts is a low cover surface, Ts1 Is the lower surface of the raw cover, and Ts2 is the upper surface of the raw cover. The following description will be given with reference to FIGS.

  First, the raw cover is attached to the vulcanizing mold 1, and then the vulcanizing mold closing operation is started and the heating and pressurizing medium is injected into the bladder 5 (see FIG. 2). When the distance d of the gap S becomes 1 to 10 mm, the mold closing operation is temporarily stopped for 2 to 5 seconds. After the temporary stop, the mold closing operation is resumed and vulcanization shaping is continued.

  In the present embodiment, by temporarily stopping the mold closing operation during the mold closing operation, the lower cover T1 is pressed against the mold 3 so that the surface Ts of the raw cover changes from the state shown in FIG. In other words, the surface Ts1 at the lower portion of the low cover is in contact with the cavity surface of the side mold 3. As a result, the curve shape from the surface Ts1 at the lower portion of the low cover to the surface Ts2 at the upper portion of the raw cover becomes gentle and the internal pressure of the bladder 5 with respect to the upper portion T2 (see FIG. 2) is relatively lowered. The pressing force against the mold 2 and the side mold 3 is suppressed.

  The distance d between the joint surface of the segment mold 2 and the joint surface of the side mold 3 when the mold closing operation is temporarily stopped is preferably 1 to 10 mm. The reason why the distance d is 1 mm or more is that if the distance d is less than 1 mm, rubber biting may occur before the low cover T comes into contact (contact) with the mold reliably. Further, if the distance d exceeds 10 mm, the subsequent die closing operation weakens the contact of the lower cover lower portion T1 (see FIG. 2) with the die and the desired shaping may not be performed. is there.

  In addition, since the higher effect is acquired when the joint surface height of the segment metal mold | die 2 and the side metal mold | die 3 is 20 to 30% of section height, it is preferable. Further, the present invention exerts a more remarkable effect when applied to the manufacture of a high flat type tire in which rubber biting is likely to occur.

  In addition, when the internal pressure of the bladder is less than 0.05 MPa, there is a risk that bear will be generated due to insufficient pressing, while when it exceeds 0.20 MPa, the overall pressing force may increase and biting may occur. is there. For this reason, the internal pressure of the bladder is preferably 0.05 to 0.20 MPa.

  Hereinafter, the present invention will be described more specifically by way of examples.

1. Raw cover vulcanization shaping (Examples 1 to 4)
Vulcanization shaping of a low cover for a pneumatic tire for passenger cars was carried out under the conditions of the following tire size, vulcanization shaping pressure, and vulcanization mold.
Tire size: 195 / 65R15
Vulcanizing shaping pressure: 0.1 MPa
Vulcanization mold: Split mold
9 segments
Segment / side interface height 23%

  In the implementation, the maximum thickness of the lower portion of the low cover is 13 mm, and the gap (distance d) between the segment mold 2 and the side mold 3 when the mold closing operation is temporarily stopped is 1 mm, 5 mm, 10 mm 3 The level and stop time were set to 3 levels of 2 seconds, 3.5 seconds, and 5 seconds. Table 1 shows the gaps and stop times of Examples 1 to 4.

(Comparative Examples 1 and 2)
The maximum thickness of the raw cover was set to 10 mm and 13 mm, and vulcanization shaping was performed in the same manner as in Example except that the temporary closing period was not provided for the mold closing operation.

(Examples 5 and 6, Comparative Examples 3 and 4)
Vulcanization shaping was carried out in the same manner as in Examples 1 to 4, except that the gap was set to three levels of 0.5 mm, 5 mm, and 11 mm, and the stop time was set to three levels of 1 second, 3.5 seconds, and 6 seconds. Each gap and stop time are shown in Table 1.

2. Evaluation (Examples 1-6, Comparative Examples 1-4)
(1) Evaluation method Immediately after the mold was fully closed, the raw cover was taken out and examined for occurrence of rubber biting.

(2) Evaluation results Table 1 summarizes the evaluation results.

  From Table 1, when the maximum thickness of the lower portion of the lower cover is 10 mm, that is, when the rigidity of the lower portion of the lower cover is low, rubber biting does not occur even if the temporary stop is not performed. In addition, even when the temporary stop was performed, rubber biting occurred when either the gap or the stop time did not fall within the range of 2 to 5 seconds. On the other hand, when both the gap and the stop time fall within the range of 1 to 10 mm and 2 to 5 seconds, the maximum thickness of the lower portion of the lower cover is 13 mm, that is, the rubber bite does not occur even if the rigidity of the lower portion of the lower cover is high. .

  While the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above-described embodiments within the same and equivalent scope as the present invention.

1 Vulcanizing mold 2 Segment mold 3 Side mold 4 Bead ring 5 Bladder d Distance between the joining surface of the segment mold and the joining surface of the side mold S Joining of the joining surface of the segment mold and the side mold Gap between the surfaces T Raw cover T1 Raw cover lower T2 Raw cover upper Ts Raw cover surface Ts1 Raw cover lower surface Ts2 Raw cover upper surface

Claims (3)

A method for vulcanizing and shaping a pneumatic tire for a passenger car, wherein a raw cover is vulcanized and shaped using a vulcanizing device comprising a vulcanizing mold comprising a plurality of molds including a segment mold and a side mold,
In the mold closing step, after the mold closing operation is temporarily stopped for 2 to 5 seconds until the distance between the joint surface of the segment mold and the joint surface of the side mold becomes zero, the mold is closed. A method for vulcanizing and shaping a pneumatic tire for a passenger car, wherein the operation is resumed.   The temporary closing of the mold closing operation for 2 to 5 seconds is performed within a distance of 1 to 10 mm between the joint surface of the segment mold and the joint surface of the side mold. The vulcanization shaping method of the pneumatic tire for passenger cars according to claim 1.   The vulcanization shaping method for a pneumatic tire for a passenger car according to claim 1 or 2, wherein a pressure for pressurizing the raw cover from the inside with a bladder is 0.05 to 0.20 MPa.

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