JP2003311743A - Tire vulcanizing mold and pneumatic tire molded thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the generation of an air sump at the root of a transverse groove molding surface in a slit vent type mold for performing exhaustion from the gap between segments. <P>SOLUTION: Vent slits 27 opened to the reference surface 25 for molding the tread profile surface 10 of a tire are formed between the divided surfaces 22S of a large number of segments 22 divided in the peripheral direction of the tire. The transverse groove molding surface 34 for forming a transverse groove has grooved wall molding surfaces 35 and 35 extending from the reference surface 25 to a tire molding inner cavity and a grooved bottom molding surface 36 splicing them. Each of the grooved wall molding surfaces 35 has a first slope 35A extending from the grooved bottom molding surface 36 along a grooved wall gradient, and a second slope 35B connected at a bent point Q and extending to the reference surface 25 so as to form a gentle slope. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slit vent type mold for exhausting gas from a gap between segments, and when forming a lateral groove intersecting a longitudinal groove in the tire circumferential direction, a bare groove caused by the lateral groove is formed. TECHNICAL FIELD The present invention relates to a tire vulcanizing mold that suppresses generation, and a pneumatic tire manufactured thereby.

[0002]

2. Description of the Related Art When vulcanizing and molding a tire, it is necessary to efficiently exhaust air trapped between the mold surface and the raw tire, and for that purpose, a tread for molding the mold surface, especially the tread portion. The molding surface usually has several hundred to 200 pieces.
There are as many as 0 small vent holes for exhaust.

However, although rubber material flows into the vent hole, a large number of spews (cylindrical burrs) are formed on the surface of the product tire, for example, 10 to 10.
It will be formed in a bristle shape with a length of 25 mm. Since this spew significantly impairs the appearance of the tire, it has been conventionally cut short by a trimming device using a cutter, but this cutting work requires a lot of labor and time, and the equipment cost of the trimming device is high. In addition, maintenance costs are also required, which causes an increase in manufacturing costs.

Therefore, in recent years, in place of the vent hole, as shown in the sectional view in the circumferential direction of FIG.
In a so-called sectional type die divided into, a slit vent type in which the number of divisions is increased to about 40 to 100 and air is discharged from a slit-like small gap d formed between the dividing surfaces c, c is For example, Japanese Patent Laid-Open No. 4-2
It is proposed in Japanese Patent No. 23108. The symbol t indicates the tread portion of the tire.

[0005]

On the other hand, in a tire, the tread pattern is often formed by a groove including a vertical groove in the tire circumferential direction and a lateral groove intersecting with the vertical groove. At this time, in the segment b, Generally, as schematically shown in FIG. 13B, a vertical groove forming surface e for forming a vertical groove and a horizontal groove forming surface f for forming a horizontal groove that intersects with the vertical groove forming surface e are provided in a protruding manner.

However, since the lateral groove forming surface f extends in the tire axial direction without intersecting the dividing surface c, it hinders exhaust gas. As a result, air is trapped at the root portion f1 of the lateral groove forming surface f, which is a so-called bear. There is a problem that a so-called rubber flow failure occurs.

Therefore, according to the present invention, the groove wall forming surface portion of the lateral groove forming surface is provided with a first sloped surface portion on the groove bottom side and a gently sloped second sloped surface portion connected to the first sloped surface portion at a bending point. Based on the above, it is an object of the present invention to provide a tire vulcanizing mold capable of effectively suppressing the generation of bare even when a lateral groove forming surface is provided, and a pneumatic tire manufactured by the mold.

[0008]

In order to achieve the above object, the invention of claim 1 of the present application is a tread molding in which a tire tread portion is formed by dividing the tire in the circumferential direction and combining the divided surfaces so that they are joined together. A tire vulcanizing mold comprising a tread molding die portion composed of a plurality of face-shaped segments, wherein the tread molding surface is a reference surface for molding a tread profile surface of a tire, and a tread recessed from the tread profile surface. With a convex groove forming surface that can form the groove of the pattern and that protrudes to the tire forming lumen side,
A vent slit, which opens at least in the reference plane and guides the air inside the mold to the outside of the mold, is formed between the adjacent divided surfaces of the segments, and the slit width W1 of the vent slit in the tire circumferential direction is 0.01. ~ 0.06 mm, and the opening length L1 along the reference plane of the opening of the vent slit
60 to 95% of the length L along the reference surface of the tread molding surface
On the other hand, the groove forming surface intersects with a vertical groove forming surface for forming a vertical groove that extends the segment in the tire circumferential direction and communicates with the dividing surface, and intersects the vertical groove forming surface and the divided surface of the segment. Without including a lateral groove forming surface for forming a lateral groove extending in the tire axial direction, and the lateral groove forming surface, both groove wall forming surface portion extending from the reference surface to the tire forming lumen side, and the groove bottom forming surface portion connecting the two In addition, the groove wall forming surface portion has a first inclined surface portion extending from the groove bottom forming surface portion toward the reference surface with a groove wall gradient in a cross section perpendicular to the lateral groove length direction, and the first inclined surface portion. And a second slope portion which is connected to the slope portion at a bending point and extends to the reference surface with a gentler inclination than the first slope portion and which intersects with the reference surface at a groove edge.

Further, in the second aspect of the present invention, the second sloped surface portion has a height Hb from the reference surface which is at least at the intersection where the vertical groove forming surface and the horizontal groove forming surface intersect. 0.05 to 0.40 times the height HB, and the width W between the bending point and the groove edge in the cross section in the right angle direction.
b is 0.1 of the width WB between the groove edges in the cross section in the right angle direction.
It is characterized by being set to 0 to 0.30 times.

Further, the invention of claim 3 is characterized in that the height Hb and the width Wb of the second slope portion are gradually reduced as the distance from the intersecting portion is increased in the lateral groove length direction.

Further, the invention of claim 4 is characterized in that the second slope portion is a flat surface or a curved surface.

A fifth aspect of the present invention is a pneumatic tire invention, characterized by being molded by the vulcanization mold according to any one of the first to fourth aspects.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below.
This will be described together with the illustrated example. FIG. 1 is a meridional cross-sectional view illustrating a pneumatic tire molded by a tire vulcanizing mold of the present invention.

In FIG. 1, a pneumatic tire 1 comprises a tread portion 2, a pair of sidewall portions 3 extending inward in the radial direction from both ends thereof, and a bead located at the radially inner end of each sidewall portion 3. And part 4. Further, the pneumatic tire 1 is reinforced by a known cord reinforcing member including a carcass 6 spanned between the bead portions 4 and 4, and a belt layer 7 arranged outside the carcass 6 and inside the tread portion 2. As a result, required strength, rigidity, etc. are secured.

The carcass 6 is composed of one or more carcass plies in which carcass cords are arranged, and both ends thereof are folded back around the bead core 5 and locked. Further, the belt layer 7 has two or more belt cords arranged therein (normally two tires for passenger cars and usually three tires for heavy loads).
.About.4 sheets) of belt plies, and the belt cords intersect each other to enhance belt rigidity and reinforce the tread portion 2 with a hoop effect.

The tread portion 2 has a contoured tread profile surface 10 as shown in FIG.
A groove 11 that forms a tread pattern by being recessed from the tread profile surface 10 is formed in the groove. The groove 11 is configured to include a vertical groove 11G extending in the tire circumferential direction and a horizontal groove 11Y intersecting with the vertical groove 11G.

A vulcanization mold 20 described below is used to vulcanize and mold the pneumatic tire 1.

The vulcanization mold 20 is a so-called sectional mold having a known structure, and as shown in FIGS. 3 and 4, an annular tread forming a tread molding surface 21S for molding the tread portion 2 of the tire. The molding die part 21 is composed of a large number of segments 22 divided in the tire circumferential direction. At this time, in the tread molding die portion 21, the number of divisions of the tread molding die portion 21, that is, the number of the segments 22 is set to 40 to 100 in order to eliminate the conventional vent holes or greatly reduce the number of formation thereof. preferable.

Further, in the tread mold 21, the segments 22 move inward in the radial direction, so that the divided surfaces 22S of the adjacent segments 22 are joined together to form a ring. Reference numeral 23 in FIG. 3 is a sidewall molding die for molding the sidewall portion 3, and reference numeral 24.
Is a bead molding die for molding the bead portion 4, each having the same structure as the conventional one.

The tread molding surface 21S is shown in FIGS.
As shown in FIG. 3, a reference surface 25 for forming the tread profile surface 10, and a tire forming bore H from the reference surface 25.
Groove forming surface 2 in the shape of a convex rib projecting to the side and forming the groove 11
6 and 6.

Further, in this embodiment, in order to exhaust air from between the adjacent divided surfaces 22S, 22S of the segment 22, at least the reference surface 25 is opened between the divided surfaces 22S, 22S and the inside of the mold is opened. A vent slit 27 is formed to guide air out of the mold.

The vent slit 27 has a slit width W1 of 0.0 in the tire circumferential direction, as shown in FIGS. 5 and 7, in order to prevent the rubber material from entering while reliably exhausting air.
In the range of 1 to 0.06 mm, the opening length L1 of the vent slit 27 along the reference surface 25 of the opening K in the dividing surface direction (the direction perpendicular to the tire circumferential direction) is set to the tread forming surface 21.
60 to 95 of the length L in the direction of the dividing surface along the reference surface 25 of S
It is formed in the range of%. 7 is a perspective view of a part of the opening K of the vent slit 27 as seen from the tire forming lumen H side.

In this example, the vent slit 27 is formed by forming a shallow groove 28 for forming a vent slit in one of the adjacent divided surfaces 22S with a depth corresponding to the slit width W1. There is.

Here, the slit width W1 is 0.01 mm.
When it is smaller and the opening length L1 is smaller than 0.6 × L, the exhaust efficiency tends to be insufficient, and conversely, the slit width W1 is 0.0.
If it exceeds 6 mm, the rubber material tends to be excessively penetrated. The vent slit 27 may be opened at the groove forming surface 26 in addition to the reference surface 25 as long as it is opened at least in the reference surface 25 in the range of L1 ≧ 0.6 × L.

As a matter of course, the vent slit 27
When the vent slit 27 is divided into a plurality of (four in this example) slit portions 27a, the opening length L1 is the sum Σ of the opening lengths L1a of the respective slit portions 27a.
Represented as L1a.

Further, in this example, as shown in FIGS. 7 and 8 (A), the opening K of the vent slit 27 has a substantially triangular shape in a cross section orthogonal to the dividing surface 22S and has the vent slit. A small groove 30 extending along 27 is formed.

The small groove 30 is divided into two surfaces 22S, 22 separating the reference surface 25 and the vent slit 27 from each other.
It is formed by notching the corner portion P where S intersects with the oblique notch surface 30S. In this example, the cutout surface 30
Although the case where S is a plane is shown as an example, as shown in FIG. 8B, the cutout surface 30S can be formed as a curved surface. In such a case, the arc center O is defined as the inside of the mold. It is preferable to form the convex arc shape.

Here, the linear groove 30 functions as follows. As shown in FIG. 9A, the vent slit 27
When the slit width W1 is small, the exhaust efficiency becomes low and the air pool r may occur in the linear groove 30. However, at least the excess rubber g can flow into the linear groove 30, so that the occurrence of a bear occurs. Is suppressed. Conversely, the slit width W
When 1 is large, as shown in FIG. 9 (B), the excess rubber g fills the small groove 30 and then becomes a spew Sp to project to the outside. At this time, since the sectional volume of the linear groove 30 is larger than the slit width W1, most of the surplus rubber g is accommodated in the linear groove 30. As a result, the Spew S
The protrusion height h of p can be suppressed to, for example, 1.0 mm or less.

On the other hand, when the linear groove 30 is not provided, the variation of the excess rubber g is not absorbed and relaxed by the linear groove 30, and
Since the protrusion height h of the spew Sp directly appears, the protrusion height h is large and its variation is very large.

In order to effectively bring out the above effect, as shown in FIGS. 8A and 8B, the linear groove 30 has a groove width Wa of 0.10 on the reference surface 25 in the cross section. ~
Range of 0.50 mm and groove height Da from the reference surface 25
Is preferably in the range of 0.10 to 0.50 mm.
At this time, the ratio Wa / Da of the groove width Wa and the groove height Da is
The range of 0.5 to 1.5 is desirable.

The groove width Wa and the groove height Da are each 0.1.
If it is less than 0 mm, the groove volume becomes too small to sufficiently exhibit the above effects. Further, in the tire 1, as shown in an exaggerated manner in FIG. 2, the rib-shaped projection 31 is formed by the excess rubber g with which the small groove 30 is filled, and the tread profile surface 10 is formed.
Stick out from. Therefore, when the groove width Wa and the groove height Da exceed 0.50 mm and become too large, the rib-like protrusions 31 may impair the ground contacting property of the tire and deteriorate the running performance.

Although the narrow groove 30 is formed over the entire length of the opening K of the vent slit 27, it can be extended beyond the opening K. That is, when the opening K of the vent slit 27 is formed in the range of L1 <L, the rib groove is formed in the tire by forming the narrow groove 30 over the entire length of the length L of the reference surface 25. The protrusions 31 can be formed over the entire width of the tread profile surface 10 in the tire axial direction, and the appearance can be improved.

Further, when the linear groove 30 is continuously formed on both the reference surface 25 and the groove forming surface 26, the rib-like projection 31 continuously connects the tread profile surface 10 and the inside of the vertical groove 11G. Since it is formed over the entire width of the tread portion 2, the appearance can be further improved.

Next, as shown in FIG. 6, the groove forming surface 26 extends the segment 22 in the tire circumferential direction and communicates with the dividing surface 22S.
And intersects with the vertical groove forming surface 33 and divides the surface 22S.
And a lateral groove forming surface 34 for forming a lateral groove that extends in the tire axial direction without intersecting with each other.

In this embodiment, the lateral groove forming surface 34 extends between the vertical groove forming surfaces 33, 33, that is, the lateral groove forming surface 34M in which both ends intersect the vertical groove forming surface 33, and the vertical groove forming surface 34M. Three
3 extends outward in the tire axial direction, that is, has an outer lateral groove forming surface 34E that intersects the vertical groove forming surface 33 at only one end.

Among these, the outer lateral groove forming surfaces 34M and 34E
As shown in FIG. 10 (A) showing a cross section perpendicular to the lateral groove length direction, groove wall forming surface portions 35, 35 extending from the reference surface 25 to the tire forming lumen H side, and groove bottoms connecting the groove wall forming surface portions 35, 35, respectively. And the molding surface portion 36.

In the present embodiment, the groove wall forming surface portion 35 and the first sloped surface portion 35A extending from the groove bottom forming surface portion 36 toward the reference surface 25 with the groove wall gradient are formed in the right-angled cross section. The first sloped portion 35A is continuous with the first sloped portion 35A at the bending point Q and extends to the reference surface 25.
And a groove edge E on the reference surface 25.
And the second slope portion 35B that intersects with each other.

The second slope portion 35 having such a gentle slope
B smoothes the rubber flow and gradually pushes the air between the tread molding surface 21S and the raw tire to the split surface side,
At the root portion of the lateral groove forming surface 34, it is possible to effectively suppress the generation of a bare due to air accumulation.

In particular, at the intersection J between the vertical groove forming surface 33 and the horizontal groove forming surface 34 where air is easily trapped, in order to sufficiently suppress the accumulation of air, at least the second sloped surface portion 35B is formed. At the intersection portion J, the height Hb from the reference surface 25 is set to 0.05 to 0.40 times the height HB of the groove wall forming surface portion 35, and the bending point Q and the groove edge E are The width Wb in the right-angled cross section between the groove edges E, E in the right-angled cross-section.
It is preferably 0.10 to 0.30 times B.

The height Hb is less than 0.05 × HB,
And the width Wb is less than 0.10 × WB, the second slope 3
5B becomes too small, and there is a risk that air will be trapped at the intersection J. Further, in the tire 1, as shown exaggeratedly in FIG. 2, the chamfered portion 32 is formed at the groove edge of the lateral groove 11Y by the second slope portion 35B. Therefore,
If the height Hb of the second sloped portion 35B is larger than 0.40 × HB and the width Wb is larger than 0.30 × WB, the chamfered portion 32 becomes excessively large, which impairs the traction performance to improve running performance. There is a fear of lowering it. From the above viewpoint,
The height Hb is 0.12 × HB to 0.31 × HB, and the width W is
More preferably, b is in the range of 0.15 × WB to 0.23 × WB.

Although the second sloped portion 35B exemplifies a case of forming a flat surface in this example, it can be formed of the curved surface as shown in FIG. 10B, and in such a case. Preferably has a concave arc shape with the center O of the arc having the inner side of the tire forming cavity.

Further, as described above, the air pocket is most likely to occur at the intersection J, and tends to be less likely to occur as the distance from the intersection J increases. Therefore, in the case where the outer lateral groove forming surface 34E has the intersecting portion J only at one end, the height Hb and the width Wb of the second inclined surface portion 35B are defined as conceptually shown in FIG. , The intersection J
Can be gradually reduced as the distance from the groove increases. At this time, the height Hb and the width Wb at the other end can be reduced to zero.

When the transverse groove forming surface 34M has the intersecting portions J at both ends, the height Hb and the width Wb are set to respective positions in the transverse groove length direction as conceptually shown in FIG. It is preferable to set it to be substantially constant. If desired, the height Hb and the width Wb of the outer lateral groove forming surface 34E can be set to be substantially constant at each position in the lateral groove length direction.

Although a particularly preferred embodiment of the present invention has been described above in detail, the present invention is not limited to the illustrated embodiment and can be modified into various modes.

[0045]

EXAMPLE A vulcanization mold having a vent slit between the divided surfaces of adjacent segments was prototyped according to the specifications shown in Table 1, and a pneumatic tire was vulcanized and molded using each mold. It was inspected whether or not air pockets (bears) were generated at the base of the lateral groove forming surface.

[0046]

[Table 1]

[0047]

Since the present invention is constructed as described above,
It is possible to effectively suppress the generation of an air pocket (bare) at the root portion of the lateral groove forming surface.

[Brief description of drawings]

FIG. 1 is a meridional sectional view showing an embodiment of a pneumatic tire molded by a tire vulcanizing mold of the present invention.

FIG. 2 is a partial perspective view showing the tread surface.

FIG. 3 is a meridional sectional view showing a vulcanizing mold.

FIG. 4 is a circumferential cross-sectional view showing a tread molding die.

FIG. 5 is a perspective view showing a part of a tread molding die section.

FIG. 6 is a perspective view showing a segment.

FIG. 7 is a diagram showing an opening of a vent slit.

8A and 8B are cross-sectional views illustrating a linear groove.

9 (A) and 9 (B) are diagrams for explaining the function and effect of the linear groove.

10 (A) and 10 (B) are cross-sectional views showing cross-sectional shapes of a lateral groove forming surface in a direction perpendicular to the lateral groove length direction.

FIG. 11 is a perspective view conceptually illustrating an outer lateral groove forming surface.

FIG. 12 is a perspective view conceptually explaining a lateral groove forming surface therein.

13A and 13B are diagrams illustrating a conventional technique.

[Explanation of symbols]

2 tread section 10 tread profile surface 11 tread pattern grooves 20 tire vulcanization mold 21 Tread Mold Section 21S tread molding surface 22 segments 22S division plane 25 reference plane 26 Groove forming surface 27 Vent slit 30 narrow grooves 30S Notched surface 33 Vertical groove forming surface 34 Lateral groove forming surface 35 Groove wall forming surface 35A First slope portion 35B Second slope portion 36 Groove bottom molding surface E groove edge H Tire forming lumen J fellowship K opening P corner section Q bending point

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshihiro Sawara             3-6-9 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo               Sumitomo Rubber Industries, Ltd. (72) Inventor Motoki Shiiki             3-6-9 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo               Sumitomo Rubber Industries, Ltd. F-term (reference) 4F202 AG28 AH20 AR12 CA21 CU01                       CU07 CU14 CU20                 4F203 AG28 AH20 AM32 AR12 AR13                       DA11 DB01 DC01 DL10                 4F212 AH20 VA13 VP37

Claims (5)

[Claims] 1. A tire vulcanizing die having a tread molding die formed of a plurality of segments forming a tread molding surface which are divided in the tire circumferential direction and are joined together by joining the divided surfaces to form a tread portion of the tire. A mold, wherein the tread molding surface is a reference surface for molding a tread profile surface of a tire, and a groove having a tread pattern which is recessed from the tread profile surface, and which is a convex groove molding surface protruding toward the tire molding inner cavity side. And a vent slit that opens at least in the reference surface and guides air in the mold to the outside of the mold between the adjacent division surfaces of the segment, and the vent slit has a slit in the tire circumferential direction. The width W1 is 0.01 to 0.06 mm, and the opening length L1 along the reference surface of the opening of the vent slit is L1.
60 to 95% of the length L along the reference surface of the tread molding surface
On the other hand, the groove forming surface intersects with the vertical groove forming surface for forming a vertical groove that extends the segment in the tire circumferential direction and communicates with the dividing surface, and intersects the vertical groove forming surface and the divided surface of the segment. Without forming a lateral groove forming surface for forming a lateral groove extending in the tire axial direction, and the lateral groove forming surface includes both groove wall forming surface portions extending from the reference surface to the tire forming inner cavity side, and a groove bottom forming surface portion connecting the two. In addition, the groove wall molding surface portion has a first sloped surface portion extending from the groove bottom molding surface portion toward the reference surface with a groove wall gradient in a cross section perpendicular to the lateral groove length direction, and the first sloped surface portion. A tire sloped portion that is connected to the sloped surface of the vehicle at a bending point and extends to the reference surface at a gentler slope than the first sloped surface and that intersects the reference surface with a groove edge. Sulfur mold. 2. A height Hb from the reference surface of the second slope portion is at least at an intersection where the vertical groove forming surface and the horizontal groove forming surface intersect with each other, and a height HB of the groove wall forming surface is 0. .05 to 0.40 times, and the width Wb between the bending point and the groove edge in the cross section in the perpendicular direction is 0.10 to the width WB in the cross section in the perpendicular direction between the groove edges.
The tire vulcanizing mold according to claim 1, wherein the mold is 0.30 times. 3. The height Hb and width Wb of the second slope portion.
And, as it goes away from the intersection in the lateral groove length direction,
The tire vulcanization mold according to claim 1 or 2, wherein the mold is gradually reduced. 4. The tire vulcanizing mold according to claim 1, wherein the second slope portion is a flat surface or a curved surface. 5. A pneumatic tire formed by the vulcanizing mold according to claim 1.