JP2018030238A - Mold for tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold capable of preventing residual air at a bead part.SOLUTION: A mold for a tire 12 includes a bead ring 18 configured to abut on a bead part of a low cover. The bead ring 18 includes: a plurality of vent holes 30 penetrating from a cavity surface 20 thereof to a rear surface 22; first exhaust grooves 32 respectively extending from the vent holes 30 to an inner peripheral surface of the bead ring 18 on the rear surface 22; and a second exhaust groove 34 connecting between neighboring vent holes 30 on the rear surface 22. Preferably, the second exhaust groove 34 has a width W2 of 3-5 mm. Preferably, the second exhaust groove 34 has a depth T2 of 0.5-2.0 mm.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a tire mold.

  In the tire vulcanization process, the raw cover is heated while being pressed in the mold. In the vulcanization process, air may remain between the mold cavity surface and the raw cover. The remaining air can cause a bear on the surface of the tire. Preventing the remaining of air contributes to the improvement of tire quality.

  The mold includes a bead ring that contacts the bead portion of the raw cover. FIG. 5 shows a part of the back surface 4 (surface opposite to the cavity surface) of the conventional bead ring 2. The bead ring 2 is provided with a plurality of vent holes 6 penetrating from the cavity surface to the back surface 4 and exhaust grooves 8 extending from the vent holes 6 to the inner peripheral surface of the bead ring 2. Air between the bead portion of the low cover and the cavity surface passes through the vent hole 6 and the exhaust groove 8 and is discharged to the outside. Studies on bead rings for preventing air from remaining are disclosed in Japanese Unexamined Patent Application Publication Nos. 2012-166460 and 2015-93431.

JP2012-166460A JP2015-93431A

  When the exhaust groove on the back surface of the bead ring is clogged, the exhaust of air from the vent hole connected to the exhaust groove is prevented. The air present in the vicinity of the vent hole may remain.

  An object of the present invention is to provide a mold in which air remains at the bead portion.

  The tire mold according to the present invention includes a bead ring with which a bead portion of the raw cover comes into contact. The bead ring includes a plurality of vent holes penetrating from the cavity surface to the back surface, first exhaust grooves extending from the respective vent holes to the inner peripheral surface of the bead ring on the back surface, and the adjacent vent holes on the back surface. And a second exhaust groove connecting the two.

  Preferably, the diameter D of the vent hole on the back surface is 3 mm or more and 5 mm or less.

  Preferably, the width of the first exhaust groove is narrowed from the vent hole toward the inner peripheral surface. The maximum width W1x of the first exhaust groove is 3 mm or more and 5 mm or less, and the minimum width W1y of the first exhaust groove is 1 mm or more and 4 mm or less.

  Preferably, the width W2 of the second exhaust groove is 3 mm or more and 5 mm or less.

  Preferably, the depth T1 of the first exhaust groove is not less than 0.5 mm and not more than 2.0 mm.

  Preferably, the depth T2 of the second exhaust groove is not less than 0.5 mm and not more than 2.0 mm.

  The mold according to the present invention includes a first exhaust groove extending from the vent hole to the inner peripheral surface of the bead ring and a second exhaust groove connecting adjacent vent holes on the back surface of the bead ring. Even if the first exhaust groove extending from one vent hole is clogged, the air from the vent hole can reach the other vent hole through the second exhaust groove. This air can be exhausted through a first exhaust groove leading to another vent hole. In this mold, air remains at the bead portion.

FIG. 1 is a sectional view showing a part of a mold according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the bead ring of the mold of FIG. FIG. 3 is a plan view showing a part of the bead ring of the mold of FIG. 1. FIG. 4 is a plan view in which a part of the bead ring of FIG. 3 is enlarged. FIG. 5 is a plan view showing a bead ring of a conventional mold.

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

  FIG. 1 is a sectional view of a mold 12 according to the present invention. In FIG. 1, the vertical direction is the axial direction of the tire, the horizontal direction is the radial direction of the tire, and the direction perpendicular to the paper surface is the circumferential direction of the tire. In this figure, the raw cover R is also shown. This is a split type mold 12. The mold 12 includes a large number of tread segments 14, a pair of upper and lower side plates 16, and a pair of upper and lower bead rings 18. Although not shown, the planar shape of the segment 14 is substantially arcuate. A number of segments 14 are arranged in a ring shape. The side plate 16 and the bead ring 18 are substantially ring-shaped.

  As shown in FIG. 1, the inner surface of the bead ring 18 contacts the bead portion of the raw cover R during vulcanization. The surface in contact with the raw cover is referred to as the cavity surface 20 of the bead ring 18. The surface opposite to the cavity surface 20 is referred to as a back surface 22.

  FIG. 2 is an enlarged cross-sectional view of the bead ring 18 of FIG. FIG. 3 is a partial plan view of the bead ring 18. FIG. 3 shows a part of the rear surface 22 of the bead ring 18. In FIG. 3, the direction perpendicular to the paper surface is the axial direction of the tire. The direction indicated by the double arrow A is the circumferential direction. FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

  The bead ring 18 includes a main body 24 and a plurality of vent pieces 26. The main body 24 is provided with a plurality of holes from the cavity surface 20 to the back surface 22. This hole is referred to as a socket 28. The inner diameter of the socket 28 changes between the cavity surface 20 and the back surface 22. The inner diameter of the socket 28 on the cavity surface 20 side is larger than the inner diameter of the back surface 22 side. The vent piece 26 is fitted in the socket 28. The vent piece 26 is fitted on the cavity surface 20 side of the socket 28. The vent piece 26 includes a through hole extending in the longitudinal direction. The through hole of the vent piece 26 and the socket 28 form a hole 30 (vent hole 30) from the cavity surface 20 to the back surface 22. The vent hole 30 of the bead ring 18 is formed by the through hole of the vent piece 26 and the socket 28.

  As shown in FIG. 3, the bead ring 18 is provided with a plurality of vent holes 30. In this embodiment, twelve vent holes 30 are arranged in the bead ring 18 at equal intervals in the circumferential direction. FIG. 3 shows some of them. The bead ring 18 includes first exhaust grooves 32 extending from the respective vent holes 30 to the inner peripheral surface of the bead ring 18. In this embodiment, the width of the first exhaust groove 32 is gradually narrowed from the vent hole 30 toward the inner peripheral surface.

  As shown in FIG. 3, the bead ring 18 includes a second exhaust groove 34 connecting the adjacent bend holes on the back surface 22 thereof. The second exhaust groove 34 extends in the circumferential direction. In this embodiment, the second exhaust groove 34 has a ring shape.

  Hereinafter, the function and effect of the present invention will be described.

  The mold 12 according to the present invention includes a second exhaust groove 34 connecting the adjacent vent holes 30 on the back surface 22 of the bead ring 18. The second exhaust groove 34 forms a path through which air passes between all the vent holes 30. Even if the first exhaust groove 32 extending from one vent hole 30 is clogged, the air from the vent hole 30 can reach the other vent hole 30 through the second exhaust groove 34. This air can be discharged through the first exhaust groove 32 connected to the other vent hole 30. In this mold 12, the remaining of air in the bead portion is prevented.

  In this embodiment, the inner diameter of the vent hole 30 is larger than the inner diameter of the conventional vent hole on the back surface 22 of the bead ring 18. Enlarging the inner diameter of the vent hole 30 prevents the vent hole 30 from being clogged. In this mold 12, the remaining of air in the bead portion is prevented.

  FIG. 4 is an enlarged view of the vicinity of the vent hole 30 of the bead ring 18 of FIG. In FIG. 4, a double-headed arrow D is the inner diameter of the vent hole 30 on the back surface 22 of the bead ring 18. The inner diameter D is preferably 3.0 mm or more. By setting the inner diameter D to 3.0 mm or more, the vent hole 30 is effectively prevented from being clogged. In this mold 12, the remaining of air in the bead portion is prevented. From this viewpoint, the inner diameter D is more preferably 3.5 mm or more. The inner diameter D is preferably 5.0 mm or less. By setting the inner diameter D to 5.0 mm or less, the influence of the vent hole 30 on the durability of the mold 12 is suppressed.

  In this embodiment, the width of the first exhaust groove 32 of the bead ring 18 is larger than the width of the exhaust groove of the conventional bead ring 18 at the end on the vent hole 30 side. Furthermore, as described above, the width of the first exhaust groove 32 gradually decreases from the vent hole 30 toward the inner peripheral surface. Increasing the width of the first exhaust groove 32 and forming the first exhaust groove 32 in this shape effectively prevents the first exhaust groove 32 from being clogged. In this mold 12, the remaining of air in the bead portion is prevented.

  In FIG. 4, the double-headed arrow W <b> 1 x is the maximum width of the first exhaust groove 32. A double-headed arrow W1x is the width of the first exhaust groove 32 at the end on the vent hole 30 side. The maximum width W1x is preferably 3.0 mm or more. By setting the maximum width W1x to 3.0 mm or more, the first exhaust groove 32 is effectively prevented from being clogged. In this mold 12, the remaining of air in the bead portion is prevented. In this respect, the maximum width W1x is more preferably equal to or greater than 3.5 mm. The maximum width W1x is preferably 5.0 mm or less. By setting the maximum width W1x to 5.0 mm or less, the influence of the first exhaust groove 32 on the durability of the mold 12 is suppressed.

  In FIG. 4, the double arrow W <b> 1 y is the minimum width of the first exhaust groove 32. A double-headed arrow W1y is the width of the first exhaust groove 32 at the end on the inner peripheral side of the bead ring 18. The minimum width W1y is preferably 1.0 mm or more. By setting the minimum width W1y to 1.0 mm or more, the first exhaust groove 32 is effectively prevented from being clogged. In this mold 12, the remaining of air in the bead portion is prevented. In this respect, the minimum width W1y is more preferably 1.5 mm or more. The minimum width W1y is preferably 4.0 mm or less. By setting the minimum width W1y to 4.0 mm or less, the influence of the first exhaust groove 32 on the durability of the mold 12 is suppressed.

  In FIG. 2, the double arrow T <b> 1 is the depth of the first exhaust groove 32. The depth T1 is preferably 0.5 mm or more. By setting the depth T1 to 0.5 mm or more, the first exhaust groove 32 has a sufficient size to exhaust air effectively. In this mold 12, the remaining of air in the bead portion is prevented. In this respect, the depth T1 is more preferably 1.0 mm or more. The depth T1 is preferably 2.0 mm or less. By setting the depth T1 to 2.0 mm or less, the first exhaust groove 32 is effectively prevented from being clogged. In this mold 12, the remaining of air in the bead portion is prevented. Further, by setting the depth T1 to 2.0 mm or less, the influence of the first exhaust groove 32 on the durability of the mold 12 is suppressed.

  In FIG. 4, the double arrow W <b> 2 is the width of the second exhaust groove 34. The width W2 is preferably 3.0 mm or more. By setting the width W2 to 3.0 mm or more, the second exhaust groove 34 is effectively prevented from being clogged. In this mold 12, the remaining of air in the bead portion is prevented. In this respect, the width W2 is more preferably equal to or greater than 3.5 mm. The width W2 is preferably 5.0 mm or less. By setting the width W2 to 5.0 mm or less, the influence of the second exhaust groove 34 on the durability of the mold 12 is suppressed.

  Although not shown, the symbol T2 is the depth of the second exhaust groove 34. The depth T2 is preferably 0.5 mm or more. By setting the depth T2 to 0.5 mm or more, the second exhaust groove 34 has a size sufficient to exhaust air effectively. In this mold 12, the remaining of air in the bead portion is prevented. In this respect, the depth T2 is more preferably 1.0 mm or more. The depth T2 is preferably 2.0 mm or less. By setting the depth T2 to 2.0 mm or less, the second exhaust groove 34 is effectively prevented from being clogged. In this mold 12, the remaining of air in the bead portion is prevented. Furthermore, by setting the depth T2 to 2.0 mm or less, the influence of the second exhaust groove 34 on the durability of the mold 12 is suppressed.

  As described above, the vent piece 26 is preferably formed by the socket 28 provided in the main body 24 and the through hole of the vent piece 26. Rubber may remain in the vent hole 30. It takes time and effort to remove this residue. In the mold 12, the vent piece 26 can be removed to remove the residue in the vent piece 26. This removal is easy. Or the residue of the vent hole 30 can be removed by exchanging the vent piece 26. In this mold 12, the residue on the vent piece 26 can be easily removed.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
The mold shown in FIGS. 1-4 was prepared. The specifications of the bead ring of this mold are shown in Table 1.

[Comparative Example 1]
A mold having a bead ring shown in FIG. 5 was prepared. The specifications for this bead ring are shown in Table 1. This mold is the same as the mold of Example 1 except for the bead ring. This mold is a conventional mold.

[Comparative Example 2]
A mold of Comparative Example 2 was prepared in the same manner as Example 1 except that the bead ring was not provided with the second exhaust groove.

[Example 2-3]
A mold of Example 2-3 was prepared in the same manner as Example 1 except that the inner diameter D of the vent hole was set to the value shown in Table 1.

[Example 4-5]
A mold of Example 4-5 was prepared in the same manner as in Example 1 except that the maximum width W1x of the first exhaust groove was set to the value shown in Table 2.

[Example 6-7]
A mold of Example 6-7 was prepared in the same manner as in Example 1 except that the minimum width W1y of the first exhaust groove was set to the value shown in Table 2.

[Example 8-9]
Molds of Examples 8-9 were prepared in the same manner as Example 1 except that the depth T1 of the first exhaust groove was set to the value shown in Table 2.

[Example 10-11]
A mold of Example 10-11 was prepared in the same manner as in Example 1 except that the maximum width W2 of the second exhaust groove was set to the value shown in Table 3.

[Example 12-13]
Molds of Examples 12-13 were prepared in the same manner as Example 1 except that the depth T2 of the second exhaust groove was set to the value shown in Table 3.

[Bear occurrence rate]
Tires were produced using the molds of the above examples and comparative examples. For each mold, the bear generation rate of the produced tire was measured. The result is shown in Table 1-3 as an index with Comparative Example 1 as 100. The smaller the value, the less bear is generated. The smaller the value, the better.

  As shown in Table 1-3, the mold of the example has a higher evaluation than the mold of the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The mold described above can be applied to the manufacture of various tires.

2 ... Bead ring 4 ... Back 6 ... Vent hole 8 ... Exhaust groove 12 ... Mold 14 ... Tread segment 16 ... Side plate 18 ... Bead ring 20 ... Cavity surface 22 ... Back surface 24 ... Body 26 ... Vent piece 28 ... Socket 30 ... Vent hole 32 ... First exhaust groove 34 ... Second exhaust groove

Claims (6)

A bead ring with which the bead portion of the low cover abuts,
A plurality of vent holes through which the bead ring penetrates from the cavity surface to the back surface, first exhaust grooves extending from the respective vent holes to the inner peripheral surface of the bead ring on the back surface, and the adjacent vent holes on the back surface A tire mold including a second exhaust groove connecting the two.   The tire mold according to claim 1, wherein a diameter D of the vent hole on the back surface is 3 mm or more and 5 mm or less.   The width of the first exhaust groove is narrower from the vent hole toward the inner peripheral surface, the maximum width W1x of the first exhaust groove is 3 mm or more and 5 mm or less, and the minimum width of the first exhaust groove is W1y is 1 mm or more and 4 mm or less, The mold for tires of Claim 1 or 2.   The tire mold according to any one of claims 1 to 3, wherein a width W2 of the second exhaust groove is 3 mm or more and 5 mm or less.   The tire mold according to any one of claims 1 to 4, wherein a depth T1 of the first exhaust groove is not less than 0.5 mm and not more than 2.0 mm.   The tire mold according to any one of claims 1 to 5, wherein a depth T2 of the second exhaust groove is not less than 0.5 mm and not more than 2.0 mm.

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