JP6133159B2 - Tire vulcanization mold - Google Patents

Description

  The present invention relates to a tire vulcanization mold used for vulcanization molding of a raw cover (unvulcanized tire) in the manufacture of a pneumatic tire.

  In recent years, in the vulcanization process in the manufacture of pneumatic tires, generally, a tire vulcanization comprising a tread segment divided into a plurality of pieces and engraved with a tread pattern on each cavity surface, and a pair of upper and lower side plates. A mold is used.

  A raw cover molded in a predetermined shape is placed inside the tire vulcanizing mold, the tire vulcanizing mold is closed, and then placed inside the tire vulcanizing mold and the raw cover. The raw cover is vulcanized and molded by pressurizing and heating the raw cover from both the inner and outer surfaces using the bladder.

  When the tire vulcanizing mold is closed, the tread segment and the side plate are moved so that they coincide with each other. Conventionally, at this time, a low cover is provided between the tread segment and the side plate (split position). Was sometimes bitten. When such biting occurs, in the tire after vulcanization, a protruding rubber 12 as shown in FIG. 4 is generated at the boundary 11 between the tread T and the sidewall SW shown in FIG. There was a risk of damaging the appearance.

  In order to reduce the occurrence of biting of the low cover during vulcanization molding, a concave portion of a predetermined size is provided in advance in a place that is supposed to come into contact with the boundary between the tread segment and the side plate during molding of the raw cover. It has been practiced to improve the occurrence of protruding rubber (for example, Patent Document 1).

JP-A-6-23864

  However, demands from users for the appearance of pneumatic tires are becoming stricter year by year, and further improvements are strongly demanded.

  Then, this invention makes it a subject to provide the metal mold | die for tire vulcanization which can reduce the generation | occurrence | production of the raw material of a raw cover at the time of vulcanization molding, and can manufacture the pneumatic tire which was excellent in the external appearance. To do.

The invention described in claim 1
A tire vulcanization mold that includes a tread segment divided into a plurality of parts and a pair of upper and lower side plates, and performs vulcanization molding of a tire in a closed mold state in which the tread segment and the side plate are matched. And
When the mold is closed, an annular groove is formed in the cavity surface at the split position where the tread segment and the side plate are matched ,
The groove is provided on a cavity surface of the side plate;
Furthermore, the tire vulcanization mold is characterized in that annular protrusions are provided along the inner peripheral side and the outer peripheral side of the groove portion .

The invention described in claim 2
The tire vulcanization mold according to claim 1, wherein a cross-sectional shape of the groove portion is substantially rectangular.

The invention according to claim 3
The depth of the groove from the cavity surface is 2.0 to 5.0 mm,
The tire vulcanization mold according to claim 1 or 2 , wherein a width of the groove portion is 8.0 mm or less.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the low cover biting at the time of vulcanization molding can be reduced more, and the tire vulcanization metal mold | die which can manufacture a pneumatic tire with the more excellent external appearance can be provided.

It is sectional drawing which shows the tread segment and side plate in the closed state of the metal mold | die for tire vulcanization | cure which concerns on one embodiment of this invention. It is sectional drawing to which the crack position vicinity in the closed state of the tire vulcanization metal mold concerning one embodiment of the present invention was expanded. It is a figure which shows the cross-sectional shape of a pneumatic tire. It is a perspective view which shows the external appearance of the pneumatic tire which the protrusion rubber generate | occur | produced.

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

  FIG. 1 is a sectional view showing a tread segment and a side plate in a closed state of a tire vulcanizing mold according to the present embodiment. FIG. 2 is an enlarged cross-sectional view of the vicinity of the split position in the closed state of the tire vulcanization mold according to the present embodiment. In FIG. 1, only the left side cross section of the tire vulcanization mold that is symmetrical is shown, and in FIG. 2, only the lower half of FIG. 1 is shown.

  As shown in FIG. 1, the tire vulcanization mold according to the present embodiment includes a tread segment 2 divided into a plurality of parts and a pair of upper and lower side plates 1, 10. After the plates 1 and 10 are brought into a closed state by matching each other at the split position 3, the raw cover is vulcanized by applying pressure and heating from both the inner and outer surfaces of the raw cover put into the tire vulcanizing mold. The molding is the same as the conventional tire vulcanization mold. In FIG. 1, reference numerals 1 a and 10 a denote cavity surfaces of the side plates 1 and 10 disposed above and below, and 2 a denotes a cavity surface of the tread segment 2.

  However, as shown in FIG. 2, the tire vulcanizing mold according to the present embodiment has a cavity surface at the split position 3 where the tread segment 2 and the side plate 1 are matched when the mold is closed. It differs from the conventional tire vulcanization mold in that the annular groove 5 is formed.

  Thus, when the tire vulcanization mold configured to form the annular groove portion 5 is used, when the tread segment 2 and the side plate 1 are moved to coincide with each other to be in the closed state, The rubber of the raw cover flows into the tread pattern engraved on the cavity surface 2 a of the tread segment 2 and then flows into the groove 5.

  The timing of the low cover rubber flowing between the tread segment 2 and the side plate 1 is after the low cover rubber has completely flowed into the entire groove portion 5, so that the low cover rubber is bitten by the mold closing operation. Generation | occurrence | production of this can be suppressed and generation | occurrence | production of a protrusion rubber | gum can fully be reduced.

  An annular convex portion corresponding to the groove portion 5 is formed at the boundary between the tread and the sidewall of the pneumatic tire after vulcanization molding. The formed convex portion is one of the designs of the pneumatic tire. Therefore, the appearance of the pneumatic tire is not impaired.

  The shape of the groove 5 is preferably substantially rectangular in cross section. For example, as shown in FIG. 2, the groove 5 is provided on the cavity surface 1a of the side plate 1 so as to be formed at the split position 3 in the closed state. It is preferable that Also, this groove may be provided on the cavity surface of the tread segment, not on the side plate, or on the cavity surface of both the tread segment and the side plate, so that both grooves match when closed. May be.

  However, considering the ease of processing, it is preferable to provide the groove 5 on the cavity surface 1a of the side plate 1 as shown in FIG. 2 instead of on the cavity surface 2a of the tread segment 2 divided into a plurality of parts. . Such a groove 5 can be provided by, for example, notching.

  If the depth and width of the groove 5 to be formed are too large, rubber will be sucked up during vulcanization molding, and air will remain in the rubber part of the tire after vulcanization, resulting in scrap (occurrence of air-containing scrap) Therefore, the depth A from the cavity surface 1a of the groove 5 is preferably 2.0 to 5.0 mm, and the width B is preferably 8.0 mm or less.

  Moreover, in this Embodiment, as shown in FIG. 2, the cyclic | annular protrusion 6 along the inner peripheral side and outer peripheral side of the cyclic | annular groove part 5 is provided.

  By providing such an annular protrusion 6 sandwiching the groove 5, the protrusion 6 first hits the raw cover at the initial stage of vulcanization and prevents rubber from entering the groove 5. It is possible to further suppress the flow of the raw cover into the rubber splitting position 3 and to further reduce the occurrence of biting.

  Hereinafter, the present invention will be described more specifically with reference to examples.

1. Manufacture of pneumatic tires (1) Examples 1-5
A tire vulcanization mold in which notches are formed on the cavity surface of the side plate so that grooves of depth A and width B from the cavity surface shown in Table 1 are formed in the cavity surface at the split position. The tires of 235 / 55R19 GR TOURING A / S were vulcanized and molded, and 30 pneumatic tires of Examples 1 to 5 were produced.

(2) Comparative Example A pneumatic tire of a comparative example was manufactured in the same manner as in Examples 1 to 5 except that a conventional tire vulcanization mold in which no groove was formed at the split position was used.

2. Evaluation Method and Evaluation Results (1) Evaluation Method For each of the pneumatic tires obtained in Examples 1 to 5 and Comparative Example, the length (mm) of the protruding rubber from the tire surface is measured as the protruding amount D of the protruding rubber. At the same time, the generation rate (%) of the air-filled scrap by sucking up the rubber was determined.

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

  From Table 1, in each of Examples 1 to 5, the amount D of the protruding rubber is smaller than that of the comparative example, and an annular groove is formed at the split position of the tire vulcanization mold in the closed state. Thus, it was confirmed that the generation of the protruding rubber due to the biting of the raw cover is sufficiently suppressed.

  In Examples 1 to 5, in Example 4 in which the depth A of the groove portion exceeds 5.0 mm, and in Example 5 in which the width B of the groove portion exceeds 8.0 mm, generation of pneumatic scrap is observed. Further, in Example 1 where the groove portion depth A is 2.0 mm, the occurrence of some protruding rubber is observed, while in Examples 2 and 3, both the occurrence of protruding rubber and the generation of pneumatic scrap are observed. However, it was confirmed that a more preferable effect can be obtained by appropriately setting the depth A and the width B of the groove.

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

DESCRIPTION OF SYMBOLS 1, 10 Side plate 1a, 10a Side plate cavity surface 2 Tread segment 2a Tread segment cavity surface 3 Split position 5 Groove 6 Projection 11 Boundary between tread and sidewall 12 Extruded rubber A Groove depth B Groove width T Tread SW sidewall

Claims (3)

A tire vulcanization mold that includes a tread segment divided into a plurality of parts and a pair of upper and lower side plates, and performs vulcanization molding of a tire in a closed mold state in which the tread segment and the side plate are matched. And
When the mold is closed, an annular groove is formed in the cavity surface at the split position where the tread segment and the side plate are matched ,
The groove is provided on a cavity surface of the side plate;
A tire vulcanization mold , further comprising annular protrusions along the inner and outer peripheral sides of the groove .   The tire vulcanization mold according to claim 1, wherein a cross-sectional shape of the groove portion is substantially rectangular. The depth of the groove from the cavity surface is 2.0 to 5.0 mm,
The tire vulcanization mold according to claim 1 or 2 , wherein a width of the groove is 8.0 mm or less.

Images