JP2020090064A - Mold for manufacturing tire - Google Patents

Abstract

To provide a mold for a tire, the mold having a sipe and capable of manufacturing the tire in which chip on a tread surface, RFV and RRO are prevented while preventing a blade from being broken.SOLUTION: This invention relates to a mold 2 for manufacturing a tire 34, on a tread surface 36 of which a plurality of sipes 44 are engraved. The mold 2 includes a plurality of segments 4 having a substantially arc shape, the inner surface of which abuts on a tread 16 of a raw cover R. Each segment 4 includes a main body 22, and a plate-like blade 24 for forming the sipe 44 radially extending from an inner surface of the main body 22. The blade 24 is a bent blade 24a including a bent part 30 for facilitating the bending. Preferably, the distance from a root part of the bent blade 24a to an end part on a tip side of the bent blade 24a in the bent part 30 is 30% or less the height of the bent blade 24a.SELECTED DRAWING: Figure 5

Description

The present invention relates to a mold for manufacturing a tire. More specifically, the present invention relates to a mold for producing a tire having a tread surface with sipe carved.

The mold for tire production includes a plurality of segments whose inner surface is in contact with the tread of the raw cover (tire that has not been vulcanized). The planar shape of the segment is substantially an arc. A plurality of segments are connected in a ring shape in the circumferential direction. The boundary between adjacent segments is called the split position.

In a tire for traveling on ice and snowy roads, a large number of elongated grooves (sipes) are usually engraved on the tread surface thereof in order to improve grip on ice. Even with general tires that are not for ice and snow roads, sipes may be engraved on the tread surface. In a mold for making a sipe-carved tire, the segment comprises a body and a plurality of blades for forming the sipe. The blade extends radially from the inner surface of the body. The shape of the blade corresponds to the shape of the sipe.

After vulcanization of the raw cover, the mold is opened and the tire is taken out. At this time, by moving each segment outward in the radial direction, the inner surface of the segment is separated from the tread. The blade is separated from the tread. Since the segments are arcuate, the radial direction at the center in the circumferential direction does not match the radial direction other than at the center. Since the segments are moved in the radial direction at the center in the circumferential direction, this moving direction does not coincide with the extending direction of the blade that is not located at the center in the circumferential direction. The difference in this direction becomes larger as it approaches the split position. When the segment is moved outward in the radial direction, the blade in the vicinity of the split position is subjected to a force directed toward the split position. This force tends to concentrate at the root of the blade. It is required to prevent breakage (plastic deformation and damage) of the blade and chipping of the tread surface due to this force. A study on a mold for preventing these problems is disclosed in JP2009-34933A.

JP, 2009-34933, A

In order to prevent the blade from breaking and the tread surface from chipping, there is a method of not arranging the blade near the split position and a method of reducing the height of the blade near the split position. When the blade is not arranged in the vicinity of the split position, in the manufactured tire, there is no sipe in the vicinity of the position corresponding to the split position of the tread (here, referred to as the split corresponding position). When the height of the blade near the split position is lowered, the depth of the sipe becomes shallow near the split corresponding position. In either case, the rigidity in the vicinity of the split corresponding position is higher than that in other portions. The rigidity of the tread changes periodically in the circumferential direction. A component of the same order as the number of segments (that is, the number of division positions) of the radial force variation (RFV) of the tire due to this periodic change in rigidity (for example, when the number of segments is 9, a 9th-order component) Another problem is to suppress radial runout (RRO).

In order to reduce the force applied to the blade, there is a method of pre-tilting the blade near the split position toward the split position. However, when the blade inclined in the split position direction is arranged in the vicinity of the split position, interference may occur between the blades of the adjacent segments. This blade cannot be placed in the immediate vicinity of the split position. A sipe cannot be formed in the immediate vicinity of the split corresponding position. Similar to the above, in the vicinity of the split corresponding position, the rigidity is higher than in other portions. Suppressing RFV and RRO is an issue.

An object of the present invention is to provide a mold for a tire having a sipe, which can be used to manufacture a tire having suppressed tread surface defects, RFV and RRO while suppressing blade breakage.

The present invention relates to a mold for producing a tire having a tread surface on which a plurality of sipes are carved. The mold comprises a plurality of substantially arcuate segments whose inner surface abuts the tread of the raw cover. Each segment includes a main body and a plate-shaped blade that extends radially from the inner surface of the main body to form the sipe. The blade is a bent blade having a bent portion for facilitating bending.

Preferably, the distance from the root of the bending blade to the end of the bending portion on the tip side of the bending blade is 30% or less of the height of the bending blade.

Preferably, in the circumferential direction, the bending blade is arranged in a region within 15.0 mm from the end of the segment.

Preferably, in a cross section perpendicular to the extending direction of the bending blade, the width of the bending portion is 0.5 mm or more and 5.0 mm or less.

Preferably, in a cross section perpendicular to the extending direction of the bending blade, the bending portion has an arc shape or a shape in which a plurality of arcs are arranged in series. In this cross section, the bent portion may have a trapezoidal shape.

Preferably, the bending blade is more flexible towards the circumferential end of the segment closer to the blade.

Preferably, the segment further comprises a flat blade without the bent portion, in the circumferential direction, all blades arranged in a region within 30.0 mm from the end of the segment are bent blades, and the segment The blades arranged in the area larger than 30.0 mm from the edge of are all flat blades.

The mold comprises a bending blade. The bending blade includes a bending portion for facilitating bending. In a bending blade, when a force is applied, the bending blade bends to disperse the force concentrated at the root of the blade. This contributes to prevention of plastic deformation and breakage of the bending blade. The bending blade is hard to break even if it is located near the split position. Bending blades are less likely to cause chipping on the tread surface. In this mold, breakage of the blade and chipping of the tread surface are prevented. With the bending blade, it is not necessary to reduce the height even near the split position. The bending blade can also be arranged near the split position. With this mold, a tire having excellent RFV and RRO can be manufactured.

FIG. 1 is a plan view showing a mold according to an exemplary embodiment of the present invention. FIG. 2 is a sectional view taken along the line II-II of FIG. FIG. 3 is a cross-sectional view perpendicular to the axial direction of the segment of FIG. FIG. 4 is a cross-sectional view perpendicular to the circumferential direction of the segment of FIG. FIG. 5 is a perspective view showing the vicinity of the end of the segment of FIG. 1. FIG. 6 is a sectional view showing a bending blade of the segment of FIG. FIG. 7 is a development view showing a part of the tread surface of the tire manufactured by this mold. FIG. 8A is a sectional view showing a bending blade of a mold according to another embodiment of the present invention, and FIG. 8B shows a bending blade of the mold according to yet another embodiment of the present invention. FIG. 8C is a sectional view showing a bending blade of a mold according to still another embodiment of the present invention.

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

FIG. 1 is a plan view showing a mold 2 according to an embodiment of the present invention. This is for tires with sipe carved on the tread surface. In FIG. 1, the direction indicated by a double-headed arrow A is the circumferential direction of the mold 2, and the direction perpendicular to the paper surface is the axial direction of the mold 2. FIG. 2 is a sectional view taken along line II-II of FIG. In FIG. 2, the vertical direction is the axial direction of the mold 2, the horizontal direction is the radial direction of the mold 2, and the direction perpendicular to the paper surface is the circumferential direction of the mold 2. FIG. 2 also shows the raw cover R (a tire in an unvulcanized state).

The mold 2 includes a plurality of segments 4, a pair of upper and lower side plates 6, and a pair of upper and lower bead rings 8. In FIG. 2, the mold 2 is closed. In this state, the inner surface 14 of the segment 4, the inner surface 18 of the side plate 6 and the inner surface 20 of the bead ring 8 are combined to form a cavity surface. The cavity surface contacts the raw cover R and forms the outer surface of the tire.

As shown in FIG. 1, the planar shape of the segment 4 is substantially an arc shape. The plurality of segments 4 are connected in the circumferential direction. The plurality of segments 4 are arranged in a ring shape. The circumferential end 10 of the segment 4 is in contact with the circumferential end 10 of the segment 4 adjacent thereto. The boundary between the segments 4 is called a split position 12. In this embodiment, nine segments 4 are arranged. In this embodiment, there are nine split positions 12. The number of segments 4 may not be nine. The number of segments 4 may be more or less than 9.

As shown in FIG. 2, the inner surface 14 of each segment 4 abuts the tread 16 of the raw cover R. The inner surface 14 of the segment 4 forms the tread surface of the tire. In addition, in this figure, a protrusion for forming a groove on a tread 16 described later and a blade for forming a sipe are omitted.

As shown in FIG. 2, the inner surface 18 of each side plate 6 contacts the side portion of the raw cover R. The inner surface 18 of the side plate 6 forms the outer surface of the side portion of the tire.

As shown in FIG. 2, the inner surface 20 of each bead ring 8 abuts the bead portion of the raw cover R. The inner surface 20 of the bead ring 8 forms the outer surface of the bead portion of the tire. The bead ring 8 is fixed to the side plate 6.

FIG. 3 is a cross-sectional view perpendicular to the axial direction of the segment 4 of FIG. FIG. 4 is an enlarged view of a cross section of the segment 4 of FIG. This is a sectional view perpendicular to the circumferential direction of the segment 4 of FIG. As shown in FIGS. 3 and 4, the segment 4 comprises a body 22 and a plurality of blades 24. The inner surface of the main body 22 includes a protrusion 26 and a bottom 28. The blade 24 projects radially inward from the bottom portion 28. The protruding direction of the blade 24 is the radial direction. The blade 24 has a plate shape. The blade 24 extends in the axial direction. The extending direction of the blade 24 is the axial direction. The thickness of the blade 24 is typically 0.3 mm to 2.0 mm. A typical material for the blade 24 is steel.

In FIG. 5, the vicinity of one circumferential end of the segment 4 is shown in an enlarged manner. In this figure, the vicinity of the split position 12 is shown. In this figure, a body 22 and four blades 24 located on the body 22 are shown.

As shown in FIG. 5, this segment 4 includes a bending blade 24a and a flat blade 24b. The bending blade 24 a includes a bending portion 30. The bent portion 30 facilitates the bending of the blade 24. In this embodiment, the blades 24 located first and second from the split position 12 side are the bending blades 24a. The bending blade 24 a is located immediately near the split position 12. Although not shown, the blades 24 located at the first and second positions from the split position 12 side at the other end of the segment 4 are bending blades 24a. In this embodiment, the third and subsequent blades 24 from the split position 12 side on both sides do not include the bent portion 30. The blades 24 on the both sides, which are the third and subsequent blades from the split position 12 side, are flat blades 24b. Note that the bending portion 30 of the bending blade 24a is omitted in FIG.

As shown in FIG. 5, the bent portion 30 extends in the extending direction of the bent blade 24a. FIG. 6 is a cross-sectional view of the bending blade 24a cut perpendicularly to its extending direction. In this cross section, the bent portion 30 is bent in a direction orthogonal to the protruding direction (radial direction) of the blade 24. The bent portion 30 has a shape in which two arcs 32 are arranged in series. These arcs 32 project in the same direction.

FIG. 7 shows a part of the tire 34 manufactured by the mold 2. This drawing is a part of a development view of the tread surface 36 of the tire 34. In FIG. 7, the direction indicated by a double-headed arrow A is the circumferential direction of the tire 34, the left-right direction is the axial direction of the tire 34, and the direction perpendicular to the paper surface is the radial direction of the tire 34. The alternate long and short dash line CL represents the equator of the tire 34. The tire 34 is for traveling on ice and snow roads.

In this tire 34, the tread 37 has a plurality of main grooves 38. Each of these main grooves 38 extends substantially in the circumferential direction. The tread 37 further has a plurality of lateral grooves 40. These lateral grooves 40 extend substantially in the axial direction. The main groove 38 and the lateral groove 40 are formed by the protrusion 26 on the inner surface of the main body 22 described above. In the tread 37, a region divided by the main groove 38 and the lateral groove 40 is called a block 42. The block 42 is formed by the bottom portion 28 of the body 22 described above. The surface of the block 42 is engraved with a plurality of elongated grooves (sipe 44). The sipes 44 are provided over substantially the entire surface of the block 42. The sipe 44 is formed by the blade 24 described above.

In FIG. 7, a chain double-dashed line DL represents a position on the tread surface 36 corresponding to the split position 12 (referred to as a split corresponding position). The split corresponding position DL is a position on the tread surface 36 with which the split position 12 is in contact. As described above, the bending blade 24a is provided in the immediate vicinity of the split position 12. For this reason, in the tire 34, the sipe 44 is carved even immediately near the split corresponding position DL. The sipe 44 contributes to an improvement in grip on ice. Typically, the width of sipe 44 is 0.3 mm to 2.0 mm.

In the manufacture of the tire 34 using the mold 2 of FIG. 1, the raw cover R of the tire 34 is put into the mold 2. The raw cover R is heated while being pressurized in a cavity surrounded by the mold 2 and the bladder. The rubber composition of the raw cover R flows in the cavity due to the pressurization and heating. Each blade 24 is in a state of being pierced by the tread 16 of the raw cover R. The rubber causes a crosslinking reaction when heated. Thereby, the tire 34 is obtained.

The obtained tire 34 is taken out of the mold 2. At this time, each segment 4 is moved in the X direction of FIGS. 1 and 3. The direction X is a radial direction in the circumferential center of each segment 4. Due to this movement, the segment 4 is separated from the tread 37 of the tire 34. Each blade 24 is pulled out from the tread 37. In FIG. 1, the moved segment 4 is indicated by a chain double-dashed line.

As shown in FIG. 3, since the segment 4 has an arc shape, the direction X and the protruding direction of the blade 24 do not coincide with each other except the center of the segment 4 in the circumferential direction. Except for the center of the segment 4 in the circumferential direction, the protruding direction of the blade 24 is inclined with respect to the direction X. Reference numeral θ in FIG. 3 represents an angle formed by the protruding direction of the blade 24 and the direction X. The angle θ is larger as the blade 24 is closer to the split position 12. When the segment 4 is moved, the blade 24 is pulled out from the tread 37 in a direction inclined by an angle θ with respect to the protruding direction thereof. At this time, a force is applied to the blade 24 whose angle θ is not 0 in the direction of the split position 12. This force is greater as the blade 24 is closer to the split position 12. The bending blade 24 a easily bends at the bending portion 30. When the segment 4 is moved, the bending blade 24 a bends in the bending portion 30 toward the split position 12. The bending blade 24a elastically deforms. When the entire bending blade 24a comes off the tread 37, the bending blade 24a returns to its original state.

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

When the segment is moved, a large force is applied to the blade located near the split position in the split position direction. This force tends to concentrate at the root of the blade. It is important to suppress breakage (plastic deformation and damage) of the blade and chipping of the tread surface due to this force.

The mold 2 includes a bending blade 24a. In the bending blade 24 a, the force concentrated at the base of the blade 24 is dispersed by bending at the bending portion 30 when a force is applied. This contributes to prevention of plastic deformation and breakage of the bending blade 24a. When the bending blade 24a comes off the tread 37, the bending blade 24a returns to the original state. Even if the bending blade 24a is located in the vicinity of the split position 12, it is hard to break. The bending blade 24a is unlikely to cause a chip on the surface of the tread 37. In this mold 2, breakage of the blade 24 and chipping of the surface of the tread 37 are prevented.

In this mold 2, since the bent blade 24a can prevent the blade 24 from being broken and the surface of the tread 37 to be broken even near the split position 12, it is not necessary to reduce the height of the blade 24 near the split position 12. In this mold 2, the blade 24 can be arranged near the split position 12. In the tread 37 of the tire 34 manufactured with this mold 2, the difference in rigidity between the vicinity of the split corresponding position and other portions is small. With this mold 2, the tire 34 excellent in RFV and RRO can be manufactured.

In FIG. 6, a double-headed arrow H indicates the height of the bending blade 24a. This is the distance from the root to the tip of the bending blade 24a. Reference symbol E represents the end of the bent portion 30 on the tip side of the bent blade 24a. The double-headed arrow HC represents the distance from the root of the bending blade 24a to the end E. The ratio of the distance HC to the height H (HC/H) is preferably 30% or less. By setting the ratio (HC/H) to 30% or less, the bending blade 24a can bend in its low portion. This effectively relieves the force applied to the root of the bending blade 24a. In this mold 2, breakage of the blade 24 and breakage of the surface of the tread 37 are effectively prevented. From this viewpoint, the ratio (HC/H) is more preferably 20% or less, still more preferably 10% or less.

In FIG. 5, a double-headed arrow L represents the distance between the split position 12 and the end of the blade 24 opposite to the split position 12 at the root of the blade 24 in the circumferential direction. In the bending blade 24a, the distance L is preferably 30 mm or less. In other words, the bending blade 24a is preferably arranged in a region where the circumferential distance from the split position 12 is within 30 mm. As described above, the blade 24 closer to the split position 12 has a larger force applied when the segment 4 is moved. By disposing the bending blade 24a in a region where the circumferential distance is within 30 mm, the bending of the blade 24 and the lack of the tread 37 are effectively prevented even in the vicinity of the split position 12.

All the blades 24 having a distance L of 5 mm or less are preferably bent blades 24a. By doing so, the breakage of the blade 24 and the chipping of the tread 37 are effectively prevented even in the vicinity of the split position 12. From this viewpoint, it is more preferable that all the blades 24 having the distance L of 10 mm or less are the bending blades 24a, and it is further preferable that all the blades 24 having the distance L of 30 mm or less are the bending blades 24a.

It is preferable that all the blades 24 having a distance L of 40 mm or more are flat blades 24b. With the blade 24 separated from the split position 12, the force applied to the blade 24 when the segment 4 is moved is small. Even if the blade 24 is a flat blade 24b, the chipping of the blade 24 is unlikely to occur. Since the flat blade 24b does not have the bent portion 30, it can be easily pulled out from the tread 37. This contributes to the prevention of chipping of the surface of the tread 37. By using all the blades 24 having the distance L of 40 mm or more as the flat blades 24b, chipping of the surface of the tread 37 is effectively prevented. From this viewpoint, it is more preferable that all the blades 24 having the distance L larger than 30 mm are flat blades 24b.

All the blades 24 having an angle θ of 18° or more are preferably bent blades 24a. The larger the angle θ, the greater the force exerted on the blade 24 when the segment 4 is moved. The bending of the blade 24 and the breakage of the tread 37 are effectively prevented by using the blade 24 having the angle θ of 18° or more as the bending blade 24a. From this viewpoint, it is more preferable that all the blades 24 having the angle θ of 16° or more are the bent blades 24a.

It is preferable that all the blades 24 having an angle θ of 10° or less are flat blades 24b. With the blade 24 having a small angle θ, the force applied to the blade 24 when the segment 4 is moved is small. Even if the blade 24 is a flat blade 24b, the chipping of the blade 24 is unlikely to occur. Since the flat blade 24b does not have the bent portion 30, it can be easily pulled out from the tread 37. This contributes to the prevention of chipping of the surface of the tread 37. By using all the blades 24 with the angle θ of 10° or less as flat plate blades 24b, chipping of the tread 37 surface is effectively prevented. From this point of view, it is more preferable that all the blades 24 having the angle θ of 12° or less are flat blades 24b.

In FIG. 6, the alternate long and short dash line LC is a center line that connects the center of the bending blade 24a in the thickness direction at the root and the center of the bending blade 24a in the thickness direction at the tip. The double-headed arrow W represents the width of the bent portion 30. The width W of the bent portion 30 is the distance between the center line LC and the end of the bent portion 30 in the direction perpendicular to the center line LC (the position of the bent portion 30 where the distance from the center line LC is maximum). The width W is preferably 0.5 mm or more. The bent portion 30 having a width W of 0.5 mm or more easily bends. By setting the width W to 0.5 mm or more, the force applied to the root of the bending blade 24a is effectively dispersed. The bending blade 24a is hard to break even if it is located near the split position 12. The bending blade 24a is unlikely to cause a chip on the surface of the tread 37. In this mold 2, breakage of the blade 24 and chipping of the surface of the tread 37 are prevented. From this viewpoint, the width W is more preferably 1.0 mm or more.

The width W is preferably 5.0 mm or less. The bent portion 30 having a width W of 5.0 mm or less is unlikely to be an obstacle when the blade 24 is pulled out from the tread 37. The bending blade 24a is unlikely to cause a chip on the surface of the tread 37. In this mold 2, chipping of the surface of the tread 37 is prevented. From this viewpoint, the width W is more preferably 4.0 mm or less.

It is preferable that the bending blade 24a is particularly easy to bend toward the split position 12 side (the end side of the segment 4) close to the bending blade 24a. As described above, when the segment 4 is moved, a force is applied to the blade 24 toward the split position 12. By making the bending blade 24a particularly easy to bend toward the split position 12, the force applied to the root of the bending blade 24a is effectively dispersed. The bending blade 24a is hard to break even if it is located near the split position 12. The bending blade 24a is unlikely to cause a chip on the surface of the tread 37. In this mold 2, breakage of the blade 24 and chipping of the surface of the tread 37 are prevented.

As shown in FIG. 6, in this cross section, the bent portion 30 has a shape in which two arcs 32 are arranged in series. The bending portion 30 having the arc 32 effectively disperses the force applied to the bending blade 24a. Further, when the bent portion 30 has a shape in which two arcs 32 are arranged, the bent blade 24a can be effectively bent. The blade 24 is hard to break even if it is located near the split position 12. In this mold 2, breakage of the blade 24 is effectively prevented.

FIG. 8A is a sectional view showing a bending blade 50a of a mold according to another embodiment of the present invention. In this cross section, the bent portion 52 has a shape in which two arcs 54 are arranged in series. These arcs 54 project in different directions. With such a shape, the bending blade 50a can be effectively bent. The blade 50 is hard to break even if it is located near the split position. In this mold, breakage of the blade 50 is effectively prevented.

FIG. 8B is a sectional view showing a bending blade 60a of a mold according to still another embodiment of the present invention. In this cross section, the bent portion 62 has an arc shape. The bent portion 62 has only one arc-shaped portion. By making the bent portion 62 one arc 64, the blade 60 can be more easily pulled out from the tread 37. The bending blade 60a is unlikely to cause a chip on the surface of the tread 37. In this mold, chipping of the tread 37 surface is more effectively prevented.

FIG. 8C is a sectional view showing a bending blade 70a of a mold according to still another embodiment of the present invention. In this cross section, the bent portion 72 has a trapezoidal shape. The bent portion 72 has only one trapezoidal portion. With such a shape, the bent portion 72 is unlikely to be an obstacle when the blade 70 is pulled out from the tread 37. The bending blade 70a is unlikely to cause a chip on the surface of the tread 37. In this mold, chipping of the surface of the tread 37 is prevented.

The shape of the bent portion is not limited to the above shape. For example, in the above cross section, the bent portion may have a polygonal shape other than the trapezoid. The shape may be a combination of polygons and arcs.

Hereinafter, the effects of the present invention will be clarified by examples, but the present invention should not be limitedly interpreted based on the description of the examples.

[Example 1]
The mold shown in FIGS. 1-2 was produced. This mold is for the manufacture of ice and snow tires with sipes. The mold comprises 9 segments. This segment comprises a flat blade and a bent blade. Among these, the specifications of the bending blade are shown in Table 1. In this mold, the bending blade is arranged within 5 mm in the circumferential direction from the split position. Blades within 5 mm in the circumferential direction from the split position are all bent blades. This is shown as "5 mm" in the distance L column of Table 1. In this mold, the shape of the bent portion is the shape shown in FIG. This is shown as "FIG. 6" in the "Bent blade shape" column of Table 1. The thickness of this blade was 0.3 mm.

[Comparative Example 1]
The mold of Comparative Example 1 does not include a bending blade. All blades are flat blades. Other than this, this mold is the same as the mold of the first embodiment.

[Example 2]
A mold of Example 2 was produced in the same manner as in Example 1 except that the shape of the bending blade was changed to that shown in FIG.

[Example 3-4]
A mold of Example 3-4 was produced in the same manner as in Example 2 except that the width W of the bent portion was changed as shown in Table 1.

[Example 5-6]
Molds of Examples 5-6 were produced in the same manner as in Example 2 except that the ratio (HC/H) was changed as shown in Table 2.

[Example 7]
A mold of Example 7 was produced in the same manner as in Example 2 except that the shape of the bending blade was changed to that shown in FIG.

[Blade break]
Tires were prototyped using the molds of Examples and Comparative Examples. Twenty tires were made for each example and comparative example. The tire size was 195/65R15. After the production of these tires, the breakage of the blade was evaluated visually. The results are shown in Table 1-2 in 5 stages of 1 to 5. The larger the value, the more the blade is prevented from breaking. The larger the value, the better.

[Tire missing]
Regarding the tire obtained by the evaluation of the above-mentioned blade breakage, the chipping of the tire was visually evaluated. The results are shown in Table 1-2 in 5 stages of 1 to 5. The larger the value, the more the tire is prevented from chipping. The larger the value, the better.

As shown in Table 1-2, the examples are totally superior to the comparative examples. From this evaluation result, the superiority of the present invention is clear.

The technique according to the present invention can be applied to the manufacture of various tires having sipes.

2... Mold 4... Segment 6... Side plate 8... Bead ring 10... Segment end 12... Split position 14... Segment inner surface 16... Raw cover tread 18 ...Inside surface of side plate 20...Inside surface of bead ring 22...Main body 24, 50, 60, 70... Blade 24a, 50a, 60a, 70a... Bending blade 24b... Flat blade 26 ... Projection part 28... Bottom part 30, 52, 62, 72... Bent part 32, 54, 64... Arc 34... Tire 36... Tread surface 37... Tire tread 38・・・ Main groove 40 ・・・ Horizontal groove 42 ・・・ Block 44 ・・・ Sipe

Claims (8)

A mold for manufacturing a tire with sipe carved on the tread surface,
The mold has a plurality of substantially arc-shaped segments whose inner surface abuts the tread of the raw cover,
Each segment comprises a body and a plate-shaped blade for forming the sipe extending radially from the inner surface of the body,
The tire mold, wherein the blade is a bent blade having a bent portion for facilitating bending. The mold according to claim 1, wherein the distance from the root of the bending blade to the end of the bending portion on the tip side of the bending blade is 30% or less of the height of the bending blade. The mold according to claim 1 or 2, wherein in the circumferential direction, the bending blade is arranged in a region within 15.0 mm from an end of the segment. The mold according to any one of claims 1 to 3, wherein a width of the bent portion is 0.5 mm or more and 5.0 mm or less in a cross section perpendicular to a direction in which the bending blade extends. The mold according to any one of claims 1 to 4, wherein the bent portion has an arc shape or a shape in which a plurality of arcs are arranged in series in a cross section perpendicular to a direction in which the bending blade extends. The mold according to claim 1, wherein the bent portion has a trapezoidal shape in a cross section perpendicular to a direction in which the bent blade extends. The mold according to any one of claims 1 to 6, wherein the bending blade is more easily bent toward a circumferential end of the segment closer to the blade. The segment further comprises a flat blade without the bent portion,
Blades arranged in a region within 30.0 mm from the end of the segment in the circumferential direction are all bending blades, and blades arranged in a region larger than 30.0 mm from the end of the segment are all flat blades. The mold according to items 1 to 7.

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