JP2019093611A - Pneumatic tire and tire mold - Google Patents

Abstract

To provide a tire mold and a pneumatic tire mold capable of suppressing vulcanization defect compared to prior art when a pneumatic tire is manufactured, and suppressing deterioration of uniformity.SOLUTION: The tire mold having a side formation surface forming a side wall of a pneumatic tire, has a continuous groove arranged on the side wall formation surface and extending while making a round around in a mold circumferential direction, and a gas exhausting passage for exhausting a gas during vulcanization of a tire using the tire mold. Since the continuous groove has at least 3 or more deep groove parts of which groove depth is deeper than surroundings of both sides in the mold circumferential direction in the continuous grooves, the groove depth is waved along the mold circumferential direction and the gas exhausting passage opens even at any groove bottom of the deep grove parts. The pneumatic tire is manufactured by using the tire mold.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a pneumatic tire having ridge-like continuous protrusions extending circumferentially in the circumferential direction of the tire, and a tire mold for manufacturing the pneumatic tire.

  The tire mold used for producing a pneumatic tire is vented to discharge gas such as air remaining in the tire mold at the time of tire vulcanization and gas generated at the time of vulcanization to the outside of the mold. A large number of gas removal passages such as holes are provided. Thereby, the outer surface of the green tire being vulcanized can be in contact with the high temperature inner surface of the tire mold to accelerate the vulcanization of the green tire. If residual gas not discharged from the gas release passage exists between the outer surface of the tire and the inner surface of the tire mold, heat is not transmitted from the tire mold to the green tire, and the green tire is partially cured. In the tire mold, it is required that the gas between the outer surface of the tire and the inner surface of the tire mold be completely exhausted from the degassing passage, since a vulcanization defect which is not sufficiently generated occurs.

  On the other hand, due to the gas venting passage such as the vent hole, in the tire after vulcanization, a large amount of rubber pushed into the gas venting passage remains as spew (spout-like protrusions) on the tire surface. Therefore, additional work is performed to cut and remove the spew after the end of vulcanization. When this spew cut is performed, many cut marks of spew remain on the tire surface to deteriorate the appearance. In addition, it takes time to cut and remove by the amount of spew, and the production efficiency of the tire is lowered. Moreover, since the removed spew is disposed of as industrial waste, the material is wasted, and the amount of spew increases the amount of industrial waste.

On the other hand, tire molds and pneumatic tires that can further reduce the occurrence of spew are known (Patent Document 1).
In this tire mold, a groove extending along the circumferential direction of the mold is provided on the sidewall forming surface for molding the sidewall of the tire. The groove is configured such that the groove depth is the deepest at two points on the tire circumference. The groove is configured to communicate with the gas vent passage (the passage forming the vent hole) at the deepest portion of the groove.

JP, 2004-136616, A

  In recent years, the demand for weight reduction of the tire and the demand for reduction of the rolling resistance of the tire due to the reduction of fuel consumption of the vehicle have been severe, and the thickness of the sidewall of the tire has become thin. For this reason, the gap between the outer surface of the green tire disposed in the tire mold for vulcanization and the inner surface of the tire mold becomes larger than before, and the outer surface of the green tire and the tire mold Between the inner surface and the inner surface, gas is not easily exhausted from the degassing passage and tends to remain. For this reason, the frequency of vulcanization failure tends to be high.

Even in the case of the tire mold having the above-described structure in which the groove extending in the circumferential direction of the mold on the sidewall formation surface is communicated with the gas vent passage at the deepest portion of this groove, the frequency of vulcanization failure is It's getting higher.
Further, in the case of the tire mold in which the gas removal passage and the deepest part of the groove are provided at two places on the mold circumference, the two places where the gas release passage and the deepest part are provided are opposite positions on the mold circumference (180 Of the depth of the deepest part of the groove and the depth of the shallowest part of the groove so that a large amount of gas to be discharged can travel a long distance in the tire mold. The difference must be increased. For this reason, it becomes easy to flow many side rubbers with movement of gas. Due to the flow of the side rubber, the thickness of the side rubber varies on the circumference of the tire, and the uniformity of the tire tends to deteriorate.

  Then, when manufacturing a pneumatic tire, this invention can suppress a vulcanization failure compared with the former, and it aims at providing a tire mold and a pneumatic tire which can control aggravation of uniformity. I assume.

One aspect of the present invention is a pneumatic tire. The pneumatic tire has a ridge-like continuous protrusion extending in a circumferential direction of the tire on the side wall,
The continuous protrusion has a shape in which the height of the protrusions is corrugated along the circumferential direction of the tire, and includes at least three or more crests of the corrugated shape of the continuous protrusions.
Each surface of the top has spew or cut scars from which spew has been removed.

  It is preferable that the projection height Hhigh at the top is 105 to 180% of the average height Have of the projection height.

The top surface has the spew,
Preferably, the diameter of the spew is 0.3 to 1.2 mm, and the length of the spew is 2 to 10 mm.

  It is preferable that the tops be arranged at equal intervals in the tire circumferential direction.

  It is preferable that the number of the tops is eight or more.

One aspect of the present invention is a tire mold having a sidewall forming surface that forms a sidewall of a pneumatic tire. The tire mold is
A continuous groove provided on the side wall forming surface and extending in a circumferential direction of the mold, and provided in the inside of the tire mold for removing gas at the time of vulcanization of the tire using the tire mold And a degassing passage of
The continuous groove is provided with at least three or more deep groove portions whose groove depth is deeper than the periphery of the mold in the circumferential direction in the continuous groove. Waves along the direction,
The gas removal passage is open at any groove bottom of the deep groove portion.

  The groove depth Dhigh of the deep groove portion is preferably 105 to 180% of the average depth Dave of the groove depth.

  It is preferable that the diameter of the opening of the gas removal passage is 0.3 to 1.2 mm.

  The deep groove portions are preferably arranged at equal intervals in the circumferential direction of the mold.

  The number of deep groove portions is preferably eight or more.

  According to the above-described pneumatic tire and tire mold, when the pneumatic tire is manufactured, vulcanization failure can be suppressed as compared with the conventional case, and deterioration of uniformity can be suppressed.

It is a profile sectional view of a pneumatic tire of one embodiment. (A)-(c) is a figure explaining the continuous projection formed in the sidewall of the pneumatic tire of one embodiment. It is a figure explaining an example of the tire mold of one embodiment. It is a figure explaining a degassing passage and a continuous slot among tire molds of one embodiment.

  The pneumatic tire and tire mold of the present invention will be described with reference to the drawings. FIG. 1 is a profile cross-sectional view of a pneumatic tire according to an embodiment. Hereinafter, the pneumatic tire is simply referred to as a tire.

The tire 10 in FIG. 1 is, for example, a tire for a passenger car. The passenger car tire is a tire defined in Chapter A of JATMA YEAR BOOK 2012 (Japan Automobile Tire Association Standard). In addition, the invention can also be applied to the small truck tire defined in Chapter B and the truck and bus tire defined in Chapter C.
Numerical values of dimensions of each pattern element to be specifically described below are numerical examples in a passenger car tire, and the pneumatic tire according to the present invention is not limited to these numerical examples.

  The tire width direction described below is a direction parallel to the rotation axis of the tire 10. The tire width direction outer side is a side away from the tire center line CL in two directions in the tire width direction. Further, the inside in the tire width direction is the side closer to the tire center line CL among the two directions in the tire width direction. The tire circumferential direction is a direction in which the tread portion rotates about the rotation axis of the tire 10 as a center of rotation. The tire radial direction is a direction orthogonal to the rotation axis of the tire. The tire radial direction outer side means a side away from the rotation axis. Further, the inside in the tire radial direction refers to the side approaching the rotation axis.

(Tire structure)
The tire 10 has a tread portion T, side portions S, and bead portions B. The tire 10 has a carcass ply layer 12, a belt layer 14, and a bead core 16 as a framework, and around these frameworks, a tread rubber 18, a side rubber 20, a bead filler rubber 22, and a rim The cushion rubber 24 and the inner liner rubber 26 are mainly included.

  The carcass ply layer 12 is formed of a carcass ply material in which organic fibers are coated with rubber, which is formed into a toroidal shape by winding around between a pair of annular bead cores 16. The carcass ply layer 12 is wound around the bead core 16. On the tire radial direction outer side of the carcass ply layer 12, a belt layer 14 composed of two belt members 14a and 14b is provided. Each of the belts 14a and 14b is a member obtained by coating a rubber on a steel cord arranged at a predetermined angle, for example, 20 to 30 degrees with respect to the circumferential direction of the tire, and the lower belt 14b is an upper layer. The width in the tire width direction is wider than that of the belt member 14a. The inclination directions of the steel cords of the two layers of belt members 14a and 14b are opposite to each other. Therefore, the belts 14a and 14b form an alternating layer, and suppress the expansion of the carcass ply layer 12 due to the filled air pressure.

A tread rubber 18 is provided on the outer side in the tire radial direction of the belt member 14a. The tread rubber 18 has a first tread rubber 18a which is the outermost layer, and a second tread rubber 18b provided on the inner side in the tire radial direction of the first tread rubber member 18a. Side rubbers 20 are connected to both ends of the tread rubber 18 to form sidewalls. A rim cushion rubber 24 is provided at an inner end in the tire radial direction of the side rubber 20 and is in contact with a rim on which the tire 10 is mounted. On the radially outer side of the bead core 16, between the portion of the carcass ply layer 12 before being wound around the bead core 16 and the wound portion of the carcass ply layer 12 wound around the bead core 16 The bead filler rubber 22 is provided on the An inner liner rubber 26 is provided on the inner surface of the tire 10 facing the air-filled tire cavity area surrounded by the tire 10 and the rim.
In addition to this, the tire 10 may be provided with a belt cover which covers the belt layer 14 from the outer side in the tire radial direction of the belt layer 14 and reinforces the belt layer 14 and which is coated with organic fibers and rubber. The tire 10 may also include a bead reinforcement between the carcass ply layer 12 and the bead filler rubber member 22 wound around the bead core 16.

  The tire 10 has such a tire structure, but the tire structure of the pneumatic tire of the present invention is not limited to the tire structure shown in FIG.

Fig.2 (a)-(c) is a figure explaining the continuous protrusion formed in the sidewall of the tire 10 of one Embodiment. Specifically, FIG. 2A schematically describes the side portion S of the tire 10.
On the sidewall surface of the side portion S, as shown in FIG. 1, a ridge-shaped continuous protrusion 30 is provided, which extends one round in the tire circumferential direction. In FIG. 2A, continuous projections 30 are shown by thick lines.
The continuous protrusions 30 have a shape in which the heights of the protrusions undulate along the circumferential direction of the tire. At this time, the continuous protrusion 30 has at least three or more of the tops of the ruffled shape, that is, the portion of the maximum protrusion height. In the example shown to Fig.2 (a), the top part is provided in eight places and equal intervals on tire circumference. The spew 32 is formed on any of the eight tops of the continuous projections 30. The spew 32 is a rubber-like protrusion extruded into a gas vent passage such as a vent hole.
The cross-sectional shape of the continuous protrusion 30 may be, for example, a trapezoidal shape, a rectangular shape of rectangular or square, or a semi-cylindrical shape, and the cross-sectional shape is not particularly limited. The protrusion height of the continuous protrusion 30 is corrugated in the circumferential direction of the tire, and therefore, has a top at which the protrusion height is maximum and a bottom at which the protrusion height is minimum. With regard to the wave shape, the projection height may be linearly changed between the top and bottom adjacent to each other in the tire circumferential direction, or may be a curved shape such as a sine wave shape, and the shape is It is not restricted.
The spew 32 may be cut off if necessary. In this case, on each top of the continuous projections 30, cut marks are formed by removing spew. The cut mark is a trace of the spew 32 in which a part of the protruding base of the spew 32 remains.

The continuous projections 30 are formed by the tire mold, and the tire is adapted to induce gas between the inner surface of the tire mold and the outer surface of the green tire in order to make vulcanization failure unlikely to occur. It is possible to correspond to the continuous groove provided on the inner surface of the mold. The shape of the continuous projections 30 is also provided to suppress deterioration of the uniformity of the tire.
The top protrusion height Hhigh is preferably 105 to 180% of the average height Have of the protrusion height. By forming the tire mold so that three or more such top portions are provided, it is possible to prevent the occurrence of a vulcanization failure in a tire having a thin sidewall and to make it difficult to deteriorate uniformity.
If the top projection height Hhigh is lower than 105% of the average height Have, tire vulcanization failure rapidly increases, which is not preferable. When the top protrusion height Hhigh is higher than 180% of the average height Have, the top protrusion height Hhigh is too high, and many side rubbers are likely to flow and deteriorate the uniformity of the tire.
The protrusion height Hhigh at the top is, for example, 0.6 to 0.8 mm, and the protrusion height H low at the bottom is, for example, 0.2 to 0.4 mm.

FIG. 2 (b) shows the shape of the continuous projection 30 at the bottom, and FIG. 2 (c) shows the shape of the continuous projection 30 at the top. As shown in FIG. 2 (c), the spew 32 protrudes from the top surface. The spew 32 is formed by flowing side rubber into a gas vent passage such as a vent hole. Therefore, the outer diameter W of the spew 32 is a dimension corresponding to the opening diameter of the gas vent passage. The opening diameter of the gas removal passage is such a size that all gas between the inner surface of the tire mold and the outer surface of the green tire can be discharged when the green tire in the tire mold is vulcanized. As described above, since the spew 32 is provided at three or more places on the tire circumference, the inner surface of the tire mold is also provided with openings for three or more gas vent passages. Therefore, the opening diameter of the gas removal passage is set in accordance with the number of the openings of the gas removal passage. Therefore, the opening diameter of the gas removal passage can be reduced as the number of openings of the gas removal passage increases. By reducing the opening diameter of the gas vent passage, the rubber flowing in the gas vent passage is likely to be cured by receiving heat from the outer periphery of the passage, and hence the length L of the spew 32 also decreases.
When the outer diameter (diameter) W of the spew 32 is equal to or less than a predetermined value, cutting and removal of the spew can be made unnecessary. For example, if the outer diameter (diameter) W is smaller than the predetermined value, the spew cutting and removal requirements will not be satisfied. Further, when the outer diameter (diameter) W is smaller than a predetermined value, tire performance substantially equivalent to the case of cutting and removing the spew can be maintained, and the spew 32 can be left and provided to the market. In this respect, a tire having a small outer diameter of the spew 32 to be formed does not need to cut and remove the spew 32, which is effective in terms of tire manufacturing efficiency. In this case, the outer diameter (diameter) W of the spew 32 is preferably 0.3 to 1.2 mm, and the length L of the spew 32 is preferably 2 to 10 mm.

The tops of the continuous projections 30 are arranged at equal intervals in the circumferential direction of the tire, so that when the green tire is vulcanized, the gas between the inner surface of the tire mold and the outer surface of the green tire is efficiently discharged to the outside It is preferable from the point of In this case, it is preferable that the bottom portion be provided at the position of the middle point on the tire circumference, at the top portion adjacent in the tire circumferential direction.
It is preferable that the number of tops of the continuous projections 30 be eight or more, because the outer diameter of the spew 32 can be reduced and the length L of the spew 32 can also be reduced.
The position in the tire radial direction of the continuous projection 30 is not particularly limited, and may be outside the tire radial direction with respect to the tire maximum width position and between the tire maximum width position and the position of the tread end, or the tire maximum width The position may be on the inner side in the tire radial direction and between the tire maximum width position and the bead portion B.

  Such a tire 10 can be manufactured using a tire mold 100 described below. FIG. 3 is a view for explaining an example of the tire mold 100. As shown in FIG. An annular side mold 104 including an annular upper mold 101 for forming one side portion S of the tire 10, an annular lower mold 102 for forming the other side portion S, and a plurality of sectors 103 for forming the tread portion T. And.

  The upper mold 101 has sidewall formation surfaces 105 and 106 for forming the side portion S on the lower surface side and the lower mold 102 on the upper surface side. The side mold 104 is provided with a tread molding surface 107 for molding the tread portion T on the inner surface side.

  As shown in FIG. 3, annular continuous grooves 108 and 109 are provided on the side wall forming surfaces 105 and 106, respectively, along the circumferential direction of the mold. The continuous grooves 108 and 109 are provided to collect and exhaust the gas existing between the tire mold 10 and the green tire at the time of vulcanization of the green tire. The continuous grooves 108 and 109 correspond to the continuous projections 30 of the tire 10. FIG. 4 is a view for explaining the change in groove depth along the mold circumferential direction of the continuous groove 108. As shown in FIG. The continuous groove 109 also has the same form as the continuous groove 108, but in the following, the continuous groove 108 will be representatively described. As shown in FIG. 4, the continuous grooves 108 periodically change in depth along the circumferential direction of the mold. The change of the groove depth may be a linear change of the groove depth between the deepest portion of the groove depth and the shallowest portion of the groove depth adjacent to the mold circumferential direction, sine wave It may change smoothly like a shape, and the change is not limited.

  The deepest portions of the continuous grooves 108 and 109 respectively communicate with openings of one end of gas vent passages 110 and 111 such as one vent hole as shown in FIG. 3. The gas removal passage 110, 111 penetrates the upper mold 101 and the lower die 102, and the other end is open to the outside, and the gas collected at the deepest part of the continuous grooves 108, 109 is made outside from the gas removal passage 110, 111 It is configured to discharge. In addition, in FIG. 3, in order to facilitate understanding, the continuous grooves 108 and 109 and the gas vent passages 110 and 111 are shown in a state of being expanded from the actual state.

  As described above, the tire mold 100 is provided on the sidewall forming surfaces 105 and 106, and is provided in the continuous groove 108 and 109 extending around the mold circumferential direction and inside the tire mold 100. And venting passages 110 and 111 for venting gas during vulcanization of the tire. The continuous grooves 108 and 109 have, as shown in FIG. 4, at least three or more deep grooves, for example, the groove depth is deeper than the circumference of the mold circumferential direction in the continuous grooves 108 and 109, for example By providing a portion of the continuous grooves 108 and 109 where the groove depth is the deepest, the groove depth is corrugated along the circumferential direction of the mold. At the bottom of any of the deep groove portions, gas vent passages 110, 111 are opened. Therefore, all the gas between the inner surface of the tire mold and the outer surface of the green tire can be exhausted. Therefore, vulcanization defects can be reduced as compared with the prior art. In addition, since the amount of gas passing through the gas vent passage is reduced, the amount of side rubber flowing along with the flow of gas is small, the variation of the rubber thickness of the side rubber on the tire circumference becomes small, and the uniformity of the tire is deteriorated. It becomes difficult. In particular, since the amount of gas exhausted from one gas vent passage decreases, the inner diameter of the gas vent passages 110 and 111 can be reduced. For this reason, the spew 32 can be thinned, and the spew 32 need not be cut and removed.

According to one embodiment, it is preferable that the groove depth Dhigh of the deep groove portion of the continuous grooves 108 and 109 be 105 to 180% of the average depth Dave of the groove depth. By providing the groove depth Dhigh as described above, it is possible to prevent the occurrence of a vulcanization failure in a tire provided with a thin sidewall and to make it difficult to deteriorate uniformity. When the groove depth Dhigh of the deep groove portion is lower than 105% of the average groove depth Dave, the number of vulcanization failures of the tire rapidly increases, which is not preferable. When the groove depth Dhigh of the deep groove portion is higher than 180% of the average groove depth Dave, the groove depth Dhigh of the deep groove portion becomes too deep, and many side rubbers flow to easily deteriorate the uniformity of the tire.
The groove depth Dhigh of the deep groove portion is, for example, 0.6 to 0.8 mm, and the shallow groove depth of the continuous grooves 108 and 109 is, for example, 0.2 to 0.4 mm.
Further, according to one embodiment, the number of the deep groove portions of the continuous grooves 108 and 109 is three or more, and the openings of the gas vent passages 110 and 111 are provided in the respective deep groove portions. Since the opening diameter (diameter) of can be made 0.3 to 1.2 mm, the outer diameter W of spew 32 is made 0.3 to 1.2 mm (the outer diameter W is made smaller), and the length of spew 32 L can be reduced. For this reason, cutting and removal of the spew 32 can be made unnecessary.
According to one embodiment, the deep groove portions of the continuous grooves 108 and 109 are preferably arranged at equal intervals in the mold circumferential direction. Thereby, when the green tire is vulcanized, the gas between the inner surface of the tire mold and the outer surface of the green tire can be efficiently discharged to the outside. The number of deep groove portions is preferably eight or more. Thus, the outer diameter W of the spew 32 can be reduced, and the length L of the spew 32 can also be reduced.

(Experimental example)
In order to confirm the effect of the present embodiment, a tire mold is manufactured by variously changing the number of deep groove portions of the continuous grooves 108 and 109 of the tire mold 100 and the ratio of Dhigh to the average groove depth Dave. Tire size: 155 / 60R14) was produced. With regard to the thickness of the side rubber in the green tire, the cross-sectional shape which was conventionally the maximum thickness of 4.0 mm was 3.5 mm (the maximum thickness was reduced by 0.5 mm). The tires were evaluated for the number of occurrence of vulcanization failure and tire uniformity (RFV: Radial Force Variation: tire internal pressure 200 kPa, load 292 kgf).
In the evaluation of vulcanization failure, the number of vulcanization failures (number of defects caused by gas remaining) of 100 tires is checked, and the number of occurrence of vulcanization failures is zero level A (pass), the number of occurrence of vulcanization failures is 1 or more 2 The following was made into level B (pass), and the number of vulcanization failure occurrence evaluated three or more as level C (reject).
Moreover, in evaluation of uniformity, the value of RFV is divided into three types, those with small values of RFV are regarded as level A (pass), those with large values of RFV are regarded as level C (failed), and Those with values in between were evaluated as level B (pass).
Tables 1 and 2 below show specifications of continuous grooves (continuous protrusions) and evaluation results thereof.

As can be seen from Table 1, in the tire mold, the number of deep groove portions in the continuous grooves 108 and 109 provided with the openings of the gas vent passages 110 and 111 is three or more, and in the tire, the top of the continuous projections on which the spew 32 is formed. By providing three or more, it can be seen that the number of vulcanization failures is reduced as compared with the prior art. In addition, uniformity can also be improved. In Examples 1 to 6, compared with the conventional example, the inner diameter of the gas vent passages 110 and 111 can be made smaller, so the flow of the side rubber is reduced, and the level of uniformity can be said to be improved.
Further, from the comparison of Examples 1 to 6, it is understood that it is preferable that Dhigh / Dave and Hhigh / Have be 105 to 180% from the viewpoint of reduction in number of vulcanization failures and improvement in uniformity level. .
In the conventional example, even if Dhigh / Dave is as high as 150%, the number of deep groove portions is two, so the number of vulcanization failures is low and the uniformity is also large.

  As can be seen from Table 2, the number of deep groove portions in the continuous grooves 108 and 109 provided with the gas release passages 110 and 111 is four or more, and in the tire, four or more crests of the continuous protrusions 30 on which the spew 32 is formed In Examples 7 to 10 in which the inside diameter of the gas release passages 110 and 111 is 0.3 to 1.6 mm, it can be seen that the number of vulcanization failures is reduced and the level of uniformity is improved.

  As mentioned above, although the pneumatic tire and tire mold of the present invention were explained in detail, the present invention is not limited to the above-mentioned embodiment, and within the range which does not deviate from the main point of the present invention, various improvement and change may be made. Of course.

DESCRIPTION OF REFERENCE NUMERALS 10 tire 12 carcass ply layer 14 belt layer 14a, 14b belt material 16 bead core 18 tread rubber 18a first tread rubber 18b second tread rubber 20 side rubber 22 bead filler rubber 24 rim cushion rubber 26 inner liner rubber 30 continuous liner 32 spew 100 tire Mold 101 Upper mold 102 Lower mold 103 Sector 104 Side mold 105, 106 Side wall forming surface 107 Tread molding surface 108, 109 Continuous groove 110, 111 Gas vent passage

Claims (10)

The tire has a ridge-like continuous protrusion extending around the tire circumferential direction on the sidewall of the pneumatic tire,
The continuous protrusion has a shape in which the height of the protrusions is corrugated along the circumferential direction of the tire, and includes at least three or more crests of the corrugated shape of the continuous protrusions.
A pneumatic tire characterized by having spew or cut marks removed of spew on any surface of the top.   The pneumatic tire according to claim 1, wherein the protrusion height Hhigh at the top is 105 to 180% of the average height Have of the protrusion height. The top surface has the spew,
The pneumatic tire according to claim 1, wherein a diameter of the spew is 0.3 to 1.2 mm, and a length of the spew is 2 to 10 mm.   The pneumatic tire according to any one of claims 1 to 3, wherein the apexes are arranged at equal intervals in the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 4, wherein the number of the tops is eight or more. A tire mold having a sidewall forming surface that forms a sidewall of a pneumatic tire, comprising:
A continuous groove provided on the side wall forming surface and extending in a circumferential direction of the mold, and provided in the inside of the tire mold for removing gas at the time of vulcanization of the tire using the tire mold And a degassing passage of
The continuous groove is provided with at least three or more deep groove portions whose groove depth is deeper than the periphery of the mold in the circumferential direction in the continuous groove. Waves along the direction,
A tire mold characterized in that the gas removal passage is opened at any groove bottom of the deep groove portion.   The tire mold according to claim 6, wherein the groove depth Dhigh of the deep groove portion is 105 to 180% of the average depth Dave of the groove depth.   The tire mold according to claim 6, wherein a diameter of the opening of the gas removal passage is 0.3 to 1.2 mm.   The tire mold according to any one of claims 6 to 8, wherein the deep groove portions are arranged at equal intervals in a circumferential direction of the mold.   The tire mold according to any one of claims 6 to 9, wherein the number of the deep groove portions is eight or more.

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