JP2017144644A - Mold for tire vulcanization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for tire vulcanization capable of manufacturing a pneumatic tire excellent in appearance compared to conventional ones without generating catching of a low cover during a closing operation and closing air even when a groove part for preventing biting is arranged in a split position.SOLUTION: There is provided a mold for tire vulcanization which has a tread segment divided into a plurality and a pair of side plates upper and lower, and a ring groove part along a split position when the tread segment and the side plates are matched, a cavity surface of the tread segment and the side plate has inclination with a predetermined inclination angle to a diameter direction in an area of 10 mm toward the tread segment side and 10 mm toward a side plate side with a split position as a center and both of a wall surface of a tread segment side and a wall surface of the side plate side of the ring groove have inclination with an inclination angle of 40 to 80° to the diameter direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire vulcanizing mold used for raw cover vulcanization molding.

  Generally, a split mold type tire vulcanization mold (hereinafter also simply referred to as “mold”) is used for vulcanization molding of a low cover in the production of a pneumatic tire.

  FIG. 6 is a cross-sectional view schematically showing a tire vulcanization mold in a closed state, and shows a left half of a symmetric mold. As shown in FIG. 6, the tire vulcanization mold includes a tread segment 2 divided into a plurality in the circumferential direction and a pair of upper and lower side plates 1. Each of the tread segment 2 and the side plate 1 has cavity surfaces 2a and 1a on which a tire pattern is engraved.

  The vulcanization molding of the raw cover is performed by placing the raw cover inside the open mold and closing it, then expanding the bladder and pressing and heating the raw cover while pressing the raw cover against each cavity surface 1a, 2a. Done.

  In this vulcanization molding, conventionally, in the closing operation in the middle of closing the mold, the raw cover bites into the portion where the tread segment 2 and the side plate 1 are in contact (hereinafter referred to as “split position 3”). In rare cases, there is a risk that overspewing occurs in the bite portion and the appearance is impaired.

  Therefore, in recent years, as shown in FIG. 7, a technique has been proposed in which an annular groove 36 is provided along the split position 3 to prevent the raw cover T from being caught (for example, Patent Document 1). In the case of this mold, the rubber of the low cover T flows into the entire groove portion 36 in the closing operation and then reaches the split position 3. At that time, the closing operation of the mold has already been completed. Can be prevented from being bitten into the split position 3.

Japanese Patent Laid-Open No. 2015-20419

  However, when the mold provided with the groove 36 is used, the raw cover T may be caught on the corner 2b of the tread segment 2 in the closing operation as shown in FIG. In such a case, more rubber than expected enters the groove portion 36, and the rubber that does not fit in the groove portion 36 is bitten into the split position 3 to cause overspew.

  Further, as shown in FIG. 8B, the air in the groove 36 cannot be properly released from the gap at the split position 3 during the closing operation, and the air is trapped in the groove 36 when the closed state is reached. There is also a risk that bears may occur in the vulcanized tire.

  These problems are particularly likely to occur when vulcanizing a low cover having a profile in which a side surface and a tread surface intersect each other at a right angle, such as a race tire.

  Therefore, the present invention provides a pneumatic tire that has a better appearance than the conventional tire, even if a groove portion for preventing biting is provided at the split position, so that the low cover is not caught or the air is not closed in the groove portion during the closing operation. It is an object of the present invention to provide a tire vulcanization mold capable of manufacturing a tire.

The invention described in claim 1
A tire vulcanization gold comprising a tread segment divided into a plurality of parts and a pair of upper and lower side plates, and an annular groove is provided along a split position when the tread segment and the side plate are matched. Type,
Centering on the split position, the cavity surface of the tread segment and the side plate has a predetermined inclination angle with respect to the radial direction in a region of 10 mm toward the tread segment side and 10 mm toward the side plate side. Inclined at
The tire vulcanization mold, wherein both the wall surface on the tread segment side and the wall surface on the side plate side of the annular groove portion are inclined at an inclination angle of 40 to 80 ° with respect to the radial direction. It is.

The invention described in claim 2
2. The tire vulcanization mold according to claim 1, wherein a predetermined inclination angle with respect to a radial direction of a cavity surface of the tread segment and the side plate is 0 to 40 °.

The invention according to claim 3
The tire vulcanization mold according to claim 1 or 2, wherein a width of a bottom surface of the groove portion is 0.5 to 1.5 mm.

The invention according to claim 4
The tire vulcanization mold according to any one of claims 1 to 3, wherein a width of an upper surface of the groove portion is 1.0 to 3.0 mm.

The invention described in claim 5
The tire vulcanization mold according to any one of claims 1 to 4, wherein a depth of the groove portion from the cavity surface is 0.5 to 2.5 mm.

The invention described in claim 6
At least one annular second groove is provided on the cavity surface of the side plate on the radially inner side of the groove,
6. The wall surface on the radially outer side and the wall surface on the radially inner side of the second groove portion are inclined at an inclination angle of 40 to 80 degrees with respect to the radial direction. The tire vulcanization mold according to any one of the above.

The invention described in claim 7
The tire vulcanization mold according to claim 6, wherein 1 to 5 second groove portions are formed.

The invention according to claim 8 provides:
The tire vulcanization mold according to claim 6 or 7, wherein a width of a bottom surface of the second groove portion is 0.0 to 1.0 mm.

The invention according to claim 9 is:
9. The tire vulcanization mold according to claim 6, wherein a width of an upper surface of the second groove portion is 0.5 to 3.0 mm.

The invention according to claim 10 is:
The tire vulcanization mold according to any one of claims 6 to 9, wherein a depth of the second groove portion from the cavity surface is 0.5 to 1.5 mm. .

  According to the present invention, even if a groove portion for preventing biting is provided at the split position, the pneumatic tire has a better appearance than the conventional tire without being caught by the low cover during the closing operation or the air being trapped in the groove portion. It is possible to provide a tire vulcanization mold capable of manufacturing the tire.

It is a figure explaining the inclination-angle of the wall surface of the groove part of the metal mold | die for tire vulcanization | cure which concerns on one embodiment of this invention. It is a figure explaining the inclination angle of the split position vicinity of the metal mold | die for tire vulcanization | cure which concerns on one embodiment of this invention. It is a figure explaining the 2nd groove part of the metal mold | die for tire vulcanization | cure which concerns on one embodiment of this invention. It is an expanded sectional view showing the split position neighborhood in the closing operation of the tire vulcanization mold concerning one embodiment of the present invention. It is an expanded sectional view showing the split position neighborhood in the closed state of the mold for tire vulcanization concerning one embodiment of the present invention. It is sectional drawing which shows typically the metal mold | die for tire vulcanization | cure of a closed state. It is an expanded sectional view which shows the crack position vicinity of a closed state of an example of the conventional metal mold | die for tire vulcanization | cure. It is a figure explaining the problem which arises in the conventional mold for tire vulcanization, Comprising: (a) is a figure which shows the state where the raw cover was caught in the corner of a tread segment, (b) is the air confined in a slot. FIG.

  Hereinafter, a tire vulcanization mold according to an embodiment of the present invention will be described with reference to the drawings.

1. Outline of Mold According to the Present Embodiment The basic structure of the mold according to the present embodiment is the same as the conventional one. That is, the mold according to the present embodiment also includes a tread segment 2 divided into a plurality of parts in the circumferential direction and a pair of upper and lower side plates 1 as in the mold shown in FIG. A split position 3 is formed at a position where the tread segment 2 and the side plate 1 come into contact with each other in the closed state, and an annular groove portion is provided at the split position 3.

  However, the mold according to the present embodiment is different from the conventional structure in the vicinity of the split position 3. Hereinafter, the structure in the vicinity of the split position 3 of the mold according to the present embodiment will be described with reference to FIGS.

  FIG. 1 is a view for explaining the inclination angle of the wall surface of the groove, FIG. 2 is a view for explaining the inclination angle in the vicinity of the split position of the mold according to the present embodiment, and FIG. 3 is for explaining the second groove. FIG. 1 to 3 are cross-sectional views in which the vicinity of the split position on the lower side of the mold according to the present embodiment is enlarged, and only the auxiliary lines and reference numerals in the drawings are different.

  In the mold according to the present embodiment, the wall surfaces 6a and 6b of the annular groove 6 are inclined at inclination angles β1 and β2 of 40 to 80 ° (see FIG. 1), and the cavity surface 1a in the vicinity of the split position 3 2a is different from the prior art in that it is inclined at a predetermined inclination angle α1 (see FIG. 2).

  By using the mold having such a shape, even when the groove portion 6 for preventing biting is provided at the split position 3, the raw cover is caught on the corner 2b of the tread segment 2 as shown in FIG. It does not occur, and no air is trapped in the groove 36 as shown in FIG. As a result, it is possible to prevent the occurrence of overspew and bear in the vulcanized tire, and to manufacture a pneumatic tire having a better appearance than before.

2. Hereinafter, the characteristic structure of the mold according to the present embodiment will be described in detail.

(1) Inclination of the wall surface of the groove portion In the present embodiment, as shown in FIG. 1, both the wall surface 6a on the tread segment 2 side and the wall surface 6b on the side plate 1 side of the annular groove portion 6 are in the radial direction R. In contrast, the first feature is that it is inclined at an inclination angle of 40 to 80 °.

(A) Inclination of the wall surface on the tread segment side Specifically, as shown in FIG. 1, the wall surface 6 a on the tread segment 2 side in both the wall surfaces 6 a and 6 b of the groove portion 6 is arranged in the radial direction R of the mold. On the other hand, since the angle of the corner 2b of the tread segment 2 that comes into contact with the raw cover T during the closing operation becomes larger than that of the conventional case as shown in FIG. The rubber can be closed without being caught by the corner 2b of the tread segment 2.

  As a result, it is possible to prevent the rubber of the raw cover from being bitten than before, and it is possible to prevent over spew from occurring in the vulcanized tire.

  In addition, it is preferable to use the metal mold | die which gave R chamfering process as a metal mold | die at this time. Even with a die that has undergone normal chamfering instead of R chamfering, it has the effect of preventing the raw cover from getting caught, but R chamfering has been applied to allow the mold to close while escaping air so as to slide on the raw cover surface. It is preferable to use a mold.

(B) Inclination of the wall surface on the side plate side In the present embodiment, the wall surface 6b on the side plate 1 side of the groove 6 is also inclined at an inclination angle β2 of 40 to 80 ° with respect to the radial direction R of the mold. (See FIG. 1). As a result, as shown in FIG. 5, the closing operation is performed while letting the air in the groove portion 6 escape along the inclination of the wall surface 6b on the side plate 1 side. It is possible to prevent the occurrence of bear in the vulcanized tire.

(2) Inclination of the cavity surface in the vicinity of the split position As shown in FIG. 2, the mold according to this embodiment is such that the cavity surfaces 1a and 2a in the vicinity of the split position 3 are inclined at an inclination angle α1 of 0 to 40 °. This is the second feature.

  As shown in FIG. 2, “near the split position” in the present embodiment refers to an area of 10 mm toward the tread segment 2 side and 10 mm toward the side plate 1 side with the split position 3 as the center. . The reason why the “near the split position” is set in such a region is that, if it is outside this region, there is a possibility that the raw cover rubber bites in actual production regardless of the size.

  Further, “inclination angle α1 of the cavity surfaces 1a, 2a” in the present embodiment refers to an angle formed by the straight line S1 in FIG. 2 and the radial direction R of the mold.

  As described above, in the present embodiment, the inclination angle α1 of the cavity surfaces 1a and 2a is set to 0 to 40 °.

(3) Effects of the present embodiment As described above, according to the present embodiment, even if the groove portion for preventing biting is provided at the split position, the low cover is caught during the closing operation and the air to the groove portion is Therefore, it is possible to manufacture a pneumatic tire having a better appearance than the conventional one.

  At this time, if the depth or width of the groove 6 is too large, the rubber is sucked up during vulcanization molding, and air may remain in the rubber portion of the vulcanized tire, resulting in scrap. For this reason, the depth of the groove 6 is 0.5 to 2.5 mm, the width of the bottom surface 6c is 0.5 to 1.5 mm, the width of the upper end region, that is, the width of the upper surface is 1.0 to 3.0 mm. It is preferable to be within the range.

3. Other Configurations As shown in FIG. 3, in the mold according to the present embodiment, in addition to the groove 6 described above, annular second grooves 8, 10, 12 are provided on the cavity surface 1 a of the side plate 1. It has been. These second groove portions 8, 10, 12 are provided on the radially inner side than the above-described groove portion 6.

  Specifically, the second groove portions 8, 10, and 12 are formed at predetermined intervals, and each wall surface is inclined by 40 to 80 ° with respect to the radial direction R, similarly to the groove portion 6 described above. It is inclined at an angle β3. As a result, air that has escaped from the groove 6 in the closing operation of the mold can be sequentially released to the second grooves 8, 10, and 12 and discharged, thereby more reliably preventing the occurrence of bears due to residual air. Can do.

  In the present embodiment, three annular second groove portions are provided, but the number of second groove portions is not limited to this. However, when six or more second groove portions are formed, the appearance on the tire design may be deteriorated, so 1 to 5 are preferable. In addition, it is more preferable to form three or more second groove portions because it is possible to prevent the rubber material from being disturbed inside the vulcanized tire.

  In addition, if the depth and width of the second groove portions 8, 10, and 12 are too large, air may remain in the rubber portion of the tire after vulcanization. It is preferable that 1.0 mm, the width of the upper end region, that is, the width of the upper surface is 0.5 to 3.0 mm, and the depth is 0.5 to 1.5 mm. Note that a width of 0 mm at the bottom surface of the second groove portion means a V-shaped groove.

  Hereinafter, the present invention will be specifically described based on examples.

1. Examples and Comparative Examples (1) Examples 1 and 2
A pneumatic tire was manufactured by performing vulcanization molding of a raw cover using the mold according to the above-described embodiment. In Examples 1 and 2, the inclination angles β1 and β2 of the wall surface of the groove near the split position were set as shown in Table 1. Further, the number of second grooves and the inclination angle β3 of the wall surface were also set as shown in Table 1.

(2) Comparative Example In the comparative example, the raw cover T was vulcanized using the conventional mold shown in FIG. In addition, as for the groove part of the metal mold | die of a comparative example, the inclination angle of the wall surface of the both sides of the tread segment side and the side plate side was set to 90 degrees.

2. Evaluation method and evaluation results (1) Evaluation on occurrence of overspew For the pneumatic tires produced in Examples 1 and 2 and the comparative example, the portion in contact with the split position of the mold was visually observed during vulcanization molding. The incidence of overspew was measured. Moreover, the length and thickness of the generated overspew were measured using calipers. The results are shown in Table 1.

(2) Evaluation of the appearance of the semi-vulcanized tire (hot press cover) The semi-vulcanized tire (hot press cover) is visually observed, and the mold is in the vicinity of the part that is in contact with the mold split position. It was evaluated whether or not there was a post-clogging due to, and whether or not the rubber inside the pneumatic tire was disturbed. The results are shown in Table 1. Note that the hot press cover refers to a raw cover when the die is opened immediately after shaping the raw cover, fully closing the die, and confirming the state of the cover when the segment is closed.

(3) Evaluation regarding generation | occurrence | production of bear About the pneumatic tire after preparation, the part which was contacting with the split position of the metal mold | die during vulcanization molding was observed visually, and the incidence rate of the bear was measured. The results are shown in Table 1.

  According to Table 1, in Example 1, there is no scratches or rubber disturbance and the occurrence of bear is 0%. In Example 2, although the rubber disturbance is observed, the occurrence rate of bear is only 10%. I understand. On the other hand, in the comparative example, there are scratches and rubber disturbance, and it can be seen that the bear generation rate reaches 30%. In addition, it can be seen that the over spew that occurred 100% in the comparative example is greatly reduced in Examples 1 and 2, and the size thereof is small.

  After this, when the second groove portion was not provided and the angles β1 and β2 of the wall surface of the groove portion were changed to 40 °, 60 °, and 80 °, and the bear occurrence rates were determined, 20% and 25%, respectively. 15%, and it was found that even when the second groove portion was not provided, the bare generation rate was smaller than that of the comparative example.

  From the above, even if the groove portion for preventing biting is provided at the split position by inclining both wall surfaces of the groove portion at an inclination angle of 40 to 80 ° with respect to the radial direction, It was confirmed that it was possible to manufacture a pneumatic tire having an appearance superior to that of the conventional tire by preventing air from being trapped in the groove.

  Further, comparing the results of Example 1 and Example 2, by setting the number of the second groove portions to 3 or more, it is possible not only to appropriately prevent the occurrence of overspewing due to biting, but also the tire after vulcanization. It was confirmed that the rubber disturbance on the inside could be prevented.

  Then, when the mold of Example 1 was actually introduced into the manufacturing process of a pneumatic tire, the number of overspew generation can be reduced by 1000 / month compared to the prior art, and the cutting work for removing overspewing can be performed. The time was reduced by 33 hours / month.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to said embodiment. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

1 Side plate 1a Side plate cavity surface 2 Tread segment 2a Tread segment cavity surface 2b Tread segment corner 3 Split position 6, 36 Groove portion 6a, 6b Groove wall surface 6c Groove bottom surface 8, 10, 12 Second groove portion R diameter Direction S1 Straight line T Low cover α1 Inclination angle of cavity surface near split position β1, β2 Inclination angle of wall surface of groove β3 Inclination angle of wall surface of second groove

Claims (10)

A tire vulcanization gold comprising a tread segment divided into a plurality of parts and a pair of upper and lower side plates, and an annular groove is provided along a split position when the tread segment and the side plate are matched. Type,
Centering on the split position, the cavity surface of the tread segment and the side plate has a predetermined inclination angle with respect to the radial direction in a region of 10 mm toward the tread segment side and 10 mm toward the side plate side. Inclined at
The tire vulcanization mold, wherein both the wall surface on the tread segment side and the wall surface on the side plate side of the annular groove portion are inclined at an inclination angle of 40 to 80 ° with respect to the radial direction. .   2. The tire vulcanization mold according to claim 1, wherein a predetermined inclination angle with respect to a radial direction of a cavity surface of the tread segment and the side plate is 0 to 40 °.   The tire vulcanization mold according to claim 1 or 2, wherein a width of a bottom surface of the groove portion is 0.5 to 1.5 mm.   The tire vulcanization mold according to any one of claims 1 to 3, wherein a width of an upper surface of the groove portion is 1.0 to 3.0 mm.   The tire vulcanization mold according to any one of claims 1 to 4, wherein a depth of the groove portion from the cavity surface is 0.5 to 2.5 mm. At least one annular second groove is provided on the cavity surface of the side plate on the radially inner side of the groove,
6. The wall surface on the radially outer side and the wall surface on the radially inner side of the second groove portion are inclined at an inclination angle of 40 to 80 degrees with respect to the radial direction. The tire vulcanization mold according to any one of the above.   The tire vulcanization mold according to claim 6, wherein 1 to 5 second groove portions are formed.   The tire vulcanization mold according to claim 6 or 7, wherein a width of a bottom surface of the second groove portion is 0.0 to 1.0 mm.   The tire vulcanization mold according to any one of claims 6 to 8, wherein a width of an upper surface of the second groove portion is 0.5 to 3.0 mm.   10. The tire vulcanization mold according to claim 6, wherein a depth of the second groove portion from the cavity surface is 0.5 to 1.5 mm.

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