JP2002052537A - Mold for vulcanizing pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the discharge capacity of air and the others remaining in a mold to the outside in order to prevent the generation of a bare at the time of vulcanization molding of a tire. SOLUTION: A vulcanizing mold consists of a tread ring 5 consisting of a plurality of segments 5a displaced so as to advance and retreat radially, a pair of side rings 7, and a bead ring 9. An annular decorative groove zone 11 consisting of a plurality of side ridge grooves 15 is provided to the surface opposed to the tire surface of each of the side rings 7, the side ring 7 is divided into a plurality of annular sub-rings 7a, 7b at least at one place of the decorative groove zone 11, and the venting gap 12 piercing through the sub-rings is demarcated between the divided surfaces of the sub-rings 7a, 7b over the entire periphery thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for vulcanizing a pneumatic tire, and more particularly, to a mold for vulcanizing a pneumatic tire. This improves the performance of discharging air and other components outside the mold.

[0002]

2. Description of the Related Art In vulcanizing and curing a green tire, a vulcanizing mold including a tread ring composed of a plurality of segments that move forward and backward in a radial direction, a pair of side rings, and a bead ring is used. In general, air remaining in the mold and gas generated therein are discharged to the outside of the mold to prevent the occurrence of bears. When a large number of vent holes that can be sufficiently discharged are formed in a mold, the discharge of air and the like is effectively performed through these vent holes.

On the other hand, when a large number of vent holes cannot be formed in a mold, by making the rubber thickness of the side portion considerably large, the vulcanization allows smooth flow of the rubber in the side portion. Squeezing and discharging air and other materials outside the mold.

[0004]

However, when a large number of vent holes are provided in a mold, a large number of spews extruded into the vent holes remain in the product tire after vulcanization and curing. Because of the occurrence of many spews, there is a problem that the cut marks of spews appearing on the surface of the product tire impair the appearance of the tire, while if the thickness of the side part of the tire is considerably increased, the tire weight will be excessive However, there is a problem in that the present invention tends to increase the rolling resistance, and in this day, there is a tendency to reduce the weight of the tire, which goes against the demands of the times.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the problems of the prior art, and it is an object of the present invention to provide almost no vent hole and to increase the thickness of the rubber at the side portion. In addition, the air and the like inside the mold are smoothly and sufficiently discharged out of the mold to advantageously prevent the occurrence of bears, thereby providing an excellent appearance of the product tire. It is to provide a sulfur mold.

[0006]

SUMMARY OF THE INVENTION A vulcanizing mold for a pneumatic tire according to the present invention comprises a tread ring comprising a plurality of segments which advance and retreat in a radial direction, a pair of side ring, and a bead ring. A ring-shaped decorative groove band comprising a plurality of side ridge grooves is provided on a surface of each side ring facing the tire surface, and the side ring is formed in an annular shape at at least one position of the decorative groove band. It is divided into a plurality of sub-rings, and a gas vent gap penetrating into and out of the ring over the entire circumference is defined between the divided surfaces of the sub-rings.

In this vulcanizing mold for a pneumatic tire, a gas vent gap penetrating through the inside and outside of the sub-ring is defined between the divided surfaces of the sub-rings, so that the vent is formed in the mold as in the prior art. There is almost no need to form holes, and as a result, the number of spews also decreases naturally, resulting in a reduction in the number of man-hours for cutting off spews and the like, and at the same time, a reduction in the appearance of the tire can be advantageously prevented. .

Further, in the vulcanizing mold for a pneumatic tire, the dividing position for dividing the side ring into an annular shape is within the extending width of the decorative groove band, so that the valley portion of the side ridge groove is formed. , The gas vent gap defined between the divided surfaces,
It is possible to smoothly and satisfactorily discharge air remaining in the mold and other parts outside the mold.

Here, this gas venting gap is, for example,
It is divided into side rings for molding the side part, which is a narrow gap that allows outflow of gas but prevents inflow of rubbery material, and has an annular narrow gap provided in at least one place in the tire radial direction. And, by the side ridge grooves surrounding the gap, under the formation of a much smaller number of vent holes compared to the prior art or under the condition of no vent holes, to sufficiently prevent gas from remaining in the mold, The generation of bears can be effectively prevented, and as a result, even if the rubber thickness of the side part is reduced in order to realize the weight reduction of the tire according to the demand of the times, the gas is out of the mold. The discharge can be sufficiently performed, and the occurrence of bears can be effectively prevented. Further, since the rubber material does not flow into the narrow gap of the side ring, the material yield can be improved.

By the way, such a degassing gap of the side ring can be partitioned between sub-rings located inside and outside in the radial direction. In particular, when these sub-rings are integrated with each other, When vulcanizing is divided into two or three places, three or four sub-rings are usually connected to each other in a concentric manner, because the gas venting space is divided into two or three places, since handling during vulcanization is easy. Will be needed.

Here, the sub-rings are connected to each other in a rigid structure under the action of bolts, connecting pins, etc., so that a predetermined degassing gap dimension is secured accurately, and the side ring is handled. Is preferred in facilitating the following.

Therefore, in this vulcanizing mold for a pneumatic tire, a degassing gap penetrating through the inside and outside of the ring is defined between the divided surfaces of the sub-rings over the entire circumference, so that the air and other parts outside the mold are separated. Under excellent discharge action to
Even in the case of producing a pneumatic tire having a small rubber thickness, excellent appearance of a product tire can be provided by advantageously preventing the occurrence of bears without providing vent holes.

[0013] In such a vulcanizing mold for a pneumatic tire, more preferably, at least one of the sub-rings adjacent to each other on the surface of the side ring facing the tire surface, and the divided surface of the other sub-ring. A notch or a chamfer located adjacent to the first. According to this, upon vulcanization and curing of the green tire in the mold,
By allowing a part of the sidewall rubber to flow into the notch or chamfer, the rubber pressure during vulcanization is reduced.
As compared with the case where they are not provided, it is possible to reduce advantageously, and therefore, it is possible to more advantageously prevent the penetration of the sidewall rubber into the gas release gap and, consequently, the generation of burrs as a result. .

The notch or chamfer is
By appropriately selecting the cross-sectional shape thereof, it can be made to function also for forming a design rib for the purpose of improving the appearance of the tire, protecting the side wall portion, and the like.

Preferably, the side ridge groove is inclined and curved in an angle range of 0 ° to 50 ° with respect to the virtual radial line segment, and the curvature of each groove is set to 0.5 to the width of the decorative groove band. 5 times. According to such a pneumatic tire vulcanizing mold, while simultaneously reducing the rubber pressure during vulcanization and smoothly entering the sidewall rubber into the degassing gap,
The effect of decoratively designing the side ridge groove can be achieved.

In the above-described mold for vulcanizing a pneumatic tire, when the side ridge grooves are extended in the same direction through the dividing surface, the air remaining in the mold is quickly gasified. When the side ridge groove is extended in a different direction through the dividing surface, it is guided in the same direction through the dividing surface as in the case where the side ridge groove is extended in the same direction through the dividing surface. ,
It has the effect of producing design-like decoration while achieving the degassing effect and the effect of suppressing the occurrence of bears. here,
Extending the side ridge groove in the same direction (different direction) through the division surface means extending the tangents at the respective end points of the side ridge groove sandwiching the division surface in the same direction (different direction). It means to let.

An edge groove is provided in the decorative groove band of the side ring, and a character ridge groove is provided in a region surrounded by the edge groove in a direction crossing the side ridge groove or in a direction parallel to the side ridge groove. In the case of providing the character ridge groove, also in the region of the character ridge groove, effectively degassing effect and the effect of suppressing the occurrence of bear, in such a case, when the extending direction of the character ridge groove is the tire circumferential direction In addition, the degassing effect and the effect of suppressing bear generation can be sufficiently achieved.

When at least one of the arrangement pitch and the extending direction of the character ridge grooves is made different from each other at the dividing surface, the cutout portion or the chamfered portion, the gas release effect and the effect of suppressing the occurrence of bear are provided. While maintaining the above, the design decoration by the character ridge groove is advantageously produced, and in such a case, the arrangement pitch at the wide pitch portion of the character ridge groove is reduced by the arrangement pitch at the narrow pitch portion of the character ridge groove. When the ratio is 1.3 to 2 times, it is possible to realize a decoration with a finer character ridge groove.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a vulcanization curing step of a tire using a vulcanization mold, in which 1 is a vulcanization mold, 2 is a bladder, and 3 is
The green tire before vulcanization and hardening which is pressed by the bladder 2 against the inner surface as the molding surface of the vulcanization mold 1 in the mold closing posture is shown.

The vulcanizing mold 1 includes a tread ring 5 that contributes to the molding and vulcanization and curing of the tread portion 4 of the green tire, and a side portion ring 7 that mainly contributes to the molding of the sidewall portion 6 and the like. And a bead ring 9 contributing to the formation of the bead portion 8. According to the vulcanizing mold 1, for example, 1 to 3 mm outside the carcass 10 near the maximum width position of the tire, Preferably 1.
Having a sidewall rubber thickness in the range of 5 to 2 mm,
In other words, it is possible to manufacture a tire having a smaller rubber thickness than the conventional tire.

The tread ring 5 is composed of segments 5a which are divided into a plurality in the circumferential direction and which are displaced inward and outward in the radial direction.
Of the tread ring from the position adjacent to the segment 5a of the tread ring to the position corresponding to the intermediate position of the contact portion of the bead portion 8 of the product tire with the rim flange. Between the green tire 3 and the bead ring 9
Contacts the green tire 3 from a position adjacent to the side ring 7 over a portion corresponding to a bead base of the product tire.

Here, an annular decorative groove band 11 having a constant width is provided on the side portion ring 7 on the surface facing the tire surface, and at least one portion of the decorative groove band 11, in FIG. It extends annularly around the circumference and defines a venting gap 12 penetrating into and out of the ring.

The gas release gap 12 of the side ring 7 is defined by dividing the side ring 7 by two sub-rings 7a and 7b concentrically located inside and outside in the radial direction. , 7b can be formed by a clearance when connected to a rigid structure with a connecting pin, a bolt 13 and the like under a predetermined clearance, and in the figure, at a location corresponding to the vicinity of the maximum width position of the product tire. The provided gas venting gap 12 has a size that allows the gas inside the mold to be discharged to the outside of the mold but prevents rubber from entering.

The gas venting gap 12 can be divided into two or three places in the radial direction, or four or more places. When provided at a plurality of places, the fluidity of the side wall rubber is low. In addition, it is possible to make the gas in the mold smoother and discharge the gas outside the mold more sufficiently.

Here, more preferably, the side ring 7
Of the sub-rings 7a, 7b adjacent to each other on the surface facing the tire surface.
b) is provided with a notch or a chamfer located adjacent to the division surface of the other sub-ring 7b (7a), notch 14 in the figure, and the cross-sectional dimension of the notch 14 is set to a width of 0. 0.4 to 2 mm × height 0.5 to 3 mm, preferably 0.4 to 1 mm width × 0.5 to 1.5 mm height, for example, 0.6 mm width × 0.8 mm height.

According to the vulcanizing mold thus configured, as shown in FIG. 1, the bladder 2 is expanded and the green tire 3 is pressed against the inner surface of the mold in a state where the mold 1 is closed. When vulcanizing and curing, the side wall 6
Then, even if the thickness of the sidewall rubber is small and the flow amount of the rubber is small, only the residual air in the mold, generated gas, and the like are removed by the gas vent gap 12 extending over the entire periphery of the sidewall portion 6. As it can be discharged smoothly and reliably out of the mold without involving rubber, the number of vent holes and, consequently, the number of spews can be reduced significantly compared to the conventional technology, and the occurrence of bears can be sufficiently prevented. can do.

In addition, as shown in FIG. 1, during such vulcanization and curing, a part of the sidewall rubber is intentionally flowed into the cutout portion 14 to reduce the internal pressure of the sidewall rubber. It is possible to more effectively prevent accidental entry of rubbery material into the gas vent gap 12.
Moreover, as a result, the ridge formed annularly by the notch portion 14 can also function as a design rib. According to this, the post-processing for the product tire requires cutting a small number of spews. Will suffice.

FIGS. 2 to 5 are side views respectively showing an example of the decorative groove band 11 of the vulcanizing mold configured as described above, in which 12 is a gas vent gap, 15 is a side ridge groove,
Reference numeral 16 denotes a rim groove, and reference numeral 17 denotes a character ridge groove.

Here, as shown in these figures, the side ridge groove 15 is set at 0 ° to 5 ° with respect to the virtual radial line segment.
Each groove 1 is inclined and curved at an angle range of 0 °.
5 is set to 0.5 to 5 times the width h of the decorative groove band, and in particular, as shown in FIG. 2, each of the side ridge groove portions 15a and 15b divided by the degassing gap 12 as a boundary. May be the same direction or different directions as shown in FIGS. 3 to 5.

Here, as shown in FIGS. 2 to 5, a rim groove 16 is provided in the decorative groove band 11, and in a region surrounded by the rim groove 16, a direction intersecting with the side ridge groove 15, or The character ridge groove 17 may be provided in a direction parallel to the side ridge groove 15, and in particular, as shown in FIG. 4, the extending direction of the character ridge groove 17 may be the tire circumferential direction.

Further, at least one of the arrangement pitch and the extending direction of the character ridge groove 17 (in FIG. 5, the extending direction of each of the character ridge groove portions 17a and 17b divided by the gas vent gap 12 as a boundary). ) May be made different. In such a case, the arrangement pitch at the wide pitch portion of the character ridge groove 17 is set to 1.3 to 2 times the arrangement pitch at the narrow pitch portion of the character ridge groove. Is preferred.

With the vulcanizing mold for a pneumatic tire configured as described above, not only can the occurrence of bears be sufficiently prevented, but also the material yield can be increased while reducing the number of vent holes and spews, and The number of working steps required for the treatment can be advantageously reduced, and at the same time, the appearance itself of the tire can be improved.

[0033]

As described above, according to the present invention, even if the amount of rubber flowing during vulcanization and curing is reduced by reducing the rubber thickness of the side wall portion, the gas release gap provided in the side portion ring is provided. As a result, the gas inside the mold can be made smooth and sufficient out-of-mold discharge can be performed, thereby reducing the number of vent holes and sufficiently preventing the occurrence of bears, thus improving the yield of sidewall rubber. However, the number of man-hours required for cutting and removing the spew is greatly reduced, and a reduction in the appearance due to the spew cutting marks is effectively prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in the tire width direction showing an embodiment of a vulcanizing mold according to the present invention.

FIG. 2 is a side view showing one embodiment of a decorative groove band of a vulcanizing mold according to the present invention.

FIG. 3 is a side view showing another embodiment of the decorative groove band of the vulcanizing mold according to the present invention.

FIG. 4 is a side view showing another embodiment of the decorative groove band of the vulcanizing mold according to the present invention.

FIG. 5 is a side view showing another embodiment of the decorative groove band of the vulcanizing mold according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vulcanization mold 2 Bladder 3 Green tire 4 Tread part 5 Tread ring 5a Segment 6 Side wall part 7 Side part ring 7a, 7b Sub ring 8 Bead part 9 Bead part ring 10 Carcass 11 Decorative groove band 12 Gas release gap 13 Bolt 14 Notch part 15 Side ridge groove 15a, 15b Each part of side ridge groove divided by gas release gap 16 Border groove 17 Character ridge groove 17a, 17b Each part of character ridge groove divided by gas release gap h Decorative groove width

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 30:00 B29L 30:00

Claims (9)

[Claims] 1. A vulcanizing mold comprising a plurality of segments which are displaced in a radial direction, a pair of side rings, and a bead ring, wherein each side ring faces a tire surface. On the surface, an annular decorative groove band composed of a plurality of side ridge grooves is provided, and the side part ring is divided into a plurality of annular sub-rings at at least one position of the decorative groove band, and between the divided surfaces of the sub-rings. A vulcanizing mold for a pneumatic tire, wherein a degassing gap penetrating the ring is formed around the entire circumference of the tire. 2. A notch or a chamfer located on at least one of the sub-rings adjacent to each other on the surface of the side ring facing the tire surface and adjacent to a division surface of the other sub-ring. The mold for vulcanizing a pneumatic tire according to claim 1, further comprising: 3. The side ridge groove is inclined and curved in an angle range of 0 ° to 50 ° with respect to a virtual radial line segment, and the curvature of each groove is set to 0.5 to the width of the decorative groove band.
The mold for vulcanizing a pneumatic tire according to claim 1 or 2, which is five times as large. 4. The vulcanizing mold for a pneumatic tire according to claim 1, wherein the side ridge grooves extend in the same direction via a dividing surface. 5. The vulcanizing mold for a pneumatic tire according to claim 1, wherein the side ridge grooves extend in different directions via a dividing surface. 6. A rim groove is provided in a decorative groove band of the side ring, and a character ridge is formed in a region surrounded by the rim groove in a direction crossing the side ridge groove or in a direction parallel to the side ridge groove. Claim 1 provided with a groove.
6. The mold for vulcanizing a pneumatic tire according to any one of claims 5 to 5. 7. The vulcanizing mold for a pneumatic tire according to claim 6, wherein the extending direction of the character ridge groove is the tire circumferential direction. 8. The pneumatic tire according to claim 6, wherein at least one of the arrangement pitch and the extending direction of the character ridge grooves is different from each other at a dividing surface, a cutout portion or a chamfered portion. Vulcanizing mold. 9. The pneumatic pump according to claim 8, wherein the arrangement pitch of the character ridge grooves at the wide pitch portion is 1.3 to 2 times the arrangement pitch of the character ridge grooves at the narrow pitch portion. Mold for vulcanizing tires.