JP2012035542A - Method for production of studdable tire and tire mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a studdable tire production method which can inhibit a hole crack while securing a stud retention performance, and to provide a tire mold used for vulcanization of a studdable tire.SOLUTION: The method for producing a studdable tire having a stud hole formed on a tire tread includes vulcanizing and molding a green tire 20 using a tire mold 10 provided with a plurality of sector molds 12 in which the straight type mold pins 14A being columnar and having fixed diameter are arranged at a circumferential end side and the flask type mold pins 14B having a flange part 14b which is provided at the top side of a body part 14a and has a larger diameter than the body part 14a are arranged at a central side.

Description

  The present invention relates to a method for manufacturing a studded tire in which stud embedding holes for embedding studs in a tire tread are formed, and a tire mold for manufacturing a studable tire.

Conventionally, as a winter tire, a stud tire in which a stud pin made of metal (hereinafter referred to as a stud) is driven into a land portion of a tread is known. One end of the stud protrudes from the tire tread surface, and the other end is buried deeper than the bottom of the groove formed in the tire tread. When a vehicle equipped with such a stud tire travels on a snowy road, the tip of the stud bites into the road surface, increasing the frictional force between the road surface and the tire, thus ensuring steering stability on the snowy road. Can do.
As a method of manufacturing a stud tire, a method of directly embedding a stud in a tire tread at the time of vulcanization of the tire (for example, refer to Patent Document 1) has been proposed, but for stud embedding for embedding a stud in a tire tread. In general, a studded tire having a hole formed therein is manufactured, and a stud is driven into the stud burying hole (see, for example, Patent Documents 2 and 3).

As shown in FIG. 5, the stud 50 has a body 51 having a larger diameter on the tire tread side than a diameter on the opposite side to the tire tread side, and a body 51 provided on the bottom side of the body 51 (opposite to the tire tread side). A flange 52 for preventing slipping having a diameter larger than the diameter of the tire 51 and a tip 53 protruding in the stud axial direction from the tire tread side end of the body 51 are provided.
On the other hand, as a hole for embedding a stud formed in the land portion of the tread 21, a straight hole 60A having no bulge from the tire tread side to the bottom as shown in the lower left of FIG. Such a flask-shaped hole 60B having a flange portion 60b bulging from the body portion 60a at the bottom.
The stud embedding hole 60A is formed using a tire mold having a plurality of sector molds 72A in which straight mold pins 71A are arranged on an arc-shaped inner peripheral surface as shown in FIG. 6 (a). The The stud embedding hole 60B is formed using a tire mold including a plurality of sector molds 72B on which flask-type mold pins 71B are arranged as shown in FIG. 6B.

JP 2001-38736 A JP 2010-70052 A JP 2010-111130 A

By the way, one of the important performances required for the holes for burying studs is the stud holding performance when the studs are buried.
When the hole for burying the stud is a straight hole 60A, the adhesion between the stud 50 and the hole 60A is lowered, so that the stud holding performance is lowered.
On the other hand, when the hole for burying the stud is a flask-shaped hole 60B, the adhesion between the stud 50 and the hole 60B is improved, but a crack is generated in the hole 60B when the pot is removed after vulcanization. There was a problem that “hole cracking” was likely to occur.

  The present invention has been made in view of conventional problems, and a stud mold for manufacturing a stud tire capable of suppressing hole cracking while ensuring stud holding performance, and a tire mold used for vulcanization of a stud tire. The purpose is to provide.

As shown in FIG. 7, when pulling out the sector mold 72 from the tire after vulcanization, in the heart of the sector mold 72 are matched and the extension direction N _p withdrawal direction M and the mold pin 71P of the sector mold 72 but at the circumferential end portion side of the sector mold 72, a large angle difference to the extension direction N _q withdrawal direction M and the mold pin 71q pins sector mold 72 has occurred.
When the mold pin 71 is a straight mold pin 71A, even if there is an angle difference, the stress applied to the rubber around the hole 60A when pulled out from the tread is small. However, as shown in FIG. 6B, in the case of the flask-shaped mold pin 71B, there is a flange portion 71b that swells from the barrel portion 71a at the bottom of the barrel portion 71a. It is considered that the stress applied to the rubber around the hole 60B by the mold pin 71B is large, and as a result, the hole 60B is likely to be cracked.

Therefore, when a stud-type tire having a block pattern was vulcanized, a crack generated in the hole 60B when the flask-shaped mold pin 71B was pulled out of the tire was examined. As shown in FIG. It was found that a large number of cracks occurred on the circumferential end side. In particular, in the hole 60B located closest to the end of the sector mold, the size of the generated crack was large.
As a result of intensive studies, the present inventor has found that the mold pin disposed on the end side of the sector mold is the end side of the sector mold when viewed from the axial direction of the sector mold, such as the straight mold pin 71A. If the mold pin is a straight mold pin and the mold pin disposed on the center side of the sector mold is a flask-type mold pin 71B, cracking of the stud embedding hole can be suppressed, The present inventors have found that stud holding performance can be ensured and have arrived at the present invention.

That is, the present invention relates to a tire mold including a pair of side molds for forming a tire side portion and a plurality of sector molds provided with a plurality of protrusions for forming a tread pattern on the inner peripheral surface. In the sector mold, a plurality of mold pins that protrude from the inner peripheral surface inward in the radial direction of the sector mold and that form stud embedding holes in the land portion of the tire tread are disposed, Among them, the mold pin disposed on the circumferential end side of the sector mold has a linear shape on the circumferential end side of the sector mold when viewed from the axial direction of the tire mold. The mold pin arranged on the center side has a cylindrical body part and a flange provided with a diameter larger than the diameter of the body part provided on the tip side of the body part. And having a part.
The sector mold has an arc-shaped inner peripheral surface, and a plurality of sector molds are arranged in an annular shape to constitute a tread molding portion of the tire mold, so the radial direction, the width direction, and the circumferential direction of the sector mold are The axial direction of the tire mold is the tire axial direction in the same direction as the tire radial direction, tire width direction, and tire circumferential direction, respectively.

In the present invention, the mold pin arranged at the position closest to the circumferential end of the sector mold and the mold pin arranged at the second closest position from the circumferential end of the sector mold are both It is a mold pin in which the shape on the direction end side is a linear shape.
Thereby, while being able to suppress a hole crack, the fall of stud holding performance can be suppressed to the minimum.
Further, the invention of the present application is characterized in that the mold pin disposed on the end side in the circumferential direction of the sector mold is cylindrical.
Thereby, manufacture of a mold pin becomes easy and a hole crack can be suppressed reliably.
The invention of the present application is characterized in that the diameter of the flange portion of the mold pin disposed on the center side of the sector mold is 1.5 times or more the diameter of the body portion.
Thereby, the stud retention performance of the whole tire can further be improved.

Further, the invention of the present application uses a tire mold including a plurality of sector molds provided with a plurality of protrusions and mold pins for forming a tread pattern on an inner peripheral surface, and embeds studs in land portions of the tire tread. A studded tire manufacturing method for manufacturing a studded tire in which a hole is formed, wherein the sector mold has a shape on a circumferential end side of the sector mold when viewed from an axial direction of the tire mold. A linear mold pin is disposed on the circumferential end portion side of the sector mold, and has a cylindrical body portion and a flange portion whose diameter is provided on the front end side of the body portion is larger than the diameter of the body portion. A sector mold in which a mold pin is arranged on the center side of the sector mold is used.
As a result, it is possible to manufacture a studded tire that has excellent stud holding performance and is greatly reduced in cracking of holes for burying studs.

  The summary of the invention does not list all necessary features of the present invention, and a sub-combination of these feature groups can also be an invention.

It is a figure which shows the structure of the tire mold which concerns on this Embodiment. It is a figure which shows arrangement | positioning of the sector mold which concerns on this Embodiment. It is a figure which shows an example of the cross-sectional view and tread pattern of the studded tire vulcanized and molded with the tire mold of the present invention. It is a figure which shows the other example of the mold pin by this invention. It is a figure which shows an example of a stud and a stud hole. It is a figure which shows the formation method of the conventional stud hole. It is a figure for demonstrating the stud retention performance of a stud hole. It is a figure which shows the relationship between the position of a mold pin, and the number of crack generation.

  Hereinafter, the present invention will be described in detail through embodiments, but the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

FIGS. 1A and 1B are views showing the configuration of the tire mold 10 according to the present embodiment, and FIG. 2 is a view showing the arrangement of the sector mold 12. This example demonstrates the case where the stud mold tire which has a block pattern using the tire mold 10 is manufactured. The axial direction of the tire 20 to be vulcanized is hereinafter referred to as the up-down direction.
The tire mold 10 is placed between the upper and lower side molds 11A and 11B and the side molds 11A and 11B to form the side portion 22 of the tire 20 to be vulcanized, and is vulcanized. And a plurality of sector molds 12 for forming a tread (hereinafter referred to as a tire tread) 21 of the tire 20.
The sector mold 12 is obtained by dividing an annular mold into a plurality (9 in this example) along the circumferential direction. The sector mold 12 is annular so as to surround the outer side of the tire 20 to be vulcanized. To constitute a tread molding portion of the tire mold 10.
One or both of the upper and lower side molds 11A and 11B can move in the vertical direction, and each sector mold 12 can move in the radial direction indicated by an arrow in FIG.

A plurality of protrusions 13A, 13B and a plurality of mold pins 14 (14A, 14B) are provided on the inner peripheral surface 12a of each sector mold 12.
The protrusions 13A and 13B are provided so as to protrude radially inward from the inner peripheral surface 12a of the sector mold 12, and form a groove in the tire tread 21. The protrusion 13A extending in the circumferential direction forms a circumferential groove 23 as shown in FIGS. 3 (a) and 3 (b), and the protrusion 13B extending in the width direction is a lug as shown in FIG. 3 (b). A groove 24 is formed.
In FIG. 3A, reference numeral 27 denotes a carcass ply straddling a pair of bead cores 28 </ b> C arranged in the bead portion 28 in a toroidal form, and reference numeral 29 is arranged outside the carcass ply 27 in the tire radial direction. A belt layer composed of a plurality of belts.
A block 25 that is a land portion of the tire tread 21 is partitioned by a circumferential groove 23 and a lug groove 24 formed by the protruding portions 13A and 13B. The heights of the protrusions 13A and 13B determine the groove depths of the circumferential groove 23 and the lug groove 24. Hereinafter, the region surrounded by the protrusions 13A and 13B indicated by the symbol R in FIG. 1B is referred to as a block formation region R.

As shown in FIGS. 1A and 1B, the mold pins 14 (14A and 14B) are embedded in the pin installation holes 12b provided in the block formation region R of the inner peripheral surface 12a of the sector mold 12. It has a base part 141 and a pin part 142 protruding from the base part 141 to the inside in the radial direction of the sector mold 12. The length of the pin portion 142 is set to a value larger than the height of the protruding portions 13A and 13B.
3A and 3B, a stud 25 is embedded in the block 25 which is the land portion of the tire tread 21 and has a depth greater than the groove depth of the circumferential groove 23 and the lug groove 24 (26A). , 26B; hereinafter referred to as a stud hole).
In addition, in the sector mold of the type which does not attach the mold pin 14 later, neither the pin installation hole 12b nor the base 141 is required.
In the studded tire, a blade is provided in the block forming region R in addition to the mold pins 14 (14A, 14B) to form a sipe (not shown) in the block 25. And Sipe are omitted.

In this example, as shown in FIG. 2, among mold pins 14 provided in the sector mold 12, the position closest to the circumferential end of the sector mold 12, that is, the closest to the circumferential end of the sector mold 12. The mold pin 14 disposed in the block forming region R and the mold pin 14 disposed in the block forming region R second closest from the circumferential end of the sector mold are defined as straight mold pins 14A, and the sector mold 12 The mold pin 14 disposed in the block forming region R provided on the center side of the flask was used as a flask-type mold pin 14B.
The straight type mold pin 14A is a cylindrical mold pin having a constant diameter, and the flask type mold pin 14B is a flange having a diameter larger than that of the body part 14a and the diameter of the body part 14a. Part 14b. In this example, the diameter b of the flange portion 14b of the flask-type mold pin 14B is 1.5 times or more the diameter a of the body portion 14a.
In addition, although the ratio of the flask-shaped mold pin 14B depends on the size of the tire 20 and the tread pattern, it is about 70% of the entire mold pin in this example.

Next, the manufacturing method of the studable tire by this invention is demonstrated.
First, a raw tire is disposed on the lower side mold 11B, the sector mold 12 is reduced in diameter while the upper side mold 11A is lowered, and the tires 20 are vulcanized by combining the molds 11A, 11B, and 12 together. Is sealed in the tire mold 10.
Next, a bladder (not shown) is inflated inside the green tire, and the tire 20 is vulcanized while pressing the tire 20 against the inner surfaces of the molds 11A, 11B, and 12.
The protrusions 13A, 13B and the mold pins 14A, 14B provided on each sector mold 12 are pressed against the surface of the tire 20 raised to the vulcanization temperature and inserted into the tire tread 21.
After the vulcanization treatment, the sector mold 12 is expanded while the upper side mold 11A is raised, and the molds 11A, 11B, 12 are separated from the tire 20, and then the vulcanized tire 20 is tire molded. As shown in FIGS. 3A and 3B, the area where the straight stud hole 26A is formed in the block 25 and the area where the flask stud hole 26B is formed are shown in FIG. Studable tires 20 arranged alternately in the direction can be obtained. In addition, the thin dashed-dotted line shown with the code | symbol CL of FIG.3 (b) represents a center line, and the thick dashed-dotted line shown with the code | symbol L shows the boundary line of the sector mold 12 at the time of vulcanization | cure.

The mold pins 14 </ b> A and 14 </ b> B are pulled out from the tire 20 when the diameter of the sector mold 12 is expanded. In the tire mold 10 of this example, the mold disposed in the block forming region R closest to the circumferential end of the sector mold 12. Since the pin and the mold pin disposed in the block forming region R that is the second closest from the circumferential end of the sector mold are the straight mold pins 14A, the mold pin 14A can pull out the mold pin 14A when the vulcanizing pot is removed. Even if it deviates from the direction of the formed stud hole 26A, no cracking occurs in the stud hole 26A.
On the other hand, the flask-shaped mold pin 14B, which is prone to hole cracking, is disposed in the block forming region R provided on the center side of the sector mold 12, and therefore, the drawing direction of the mold pin 14B and the extending direction of the mold pin 14B The angle difference with is small. Therefore, since the stress that the mold pin 14B gives to the rubber around the stud hole 26B at the time of drawing is small, the stud hole 26B is not cracked.

As described above, in the present embodiment, when the studded tire 20 in which the stud hole 26 is formed in the tire tread 21 is manufactured, the straight mold pin 14A is disposed on the circumferential end side as the tire mold 10. Since the tire mold 10 including the plurality of sector molds 12 having the flask-shaped mold pins 14B arranged on the center side is used, even if the flask-shaped mold pins 14B are provided, the flask-shaped mold pins 14B The hole cracking of the stud hole 26B formed by can be significantly reduced. Further, in the formed stud hole 26B, the diameter b of the flange portion 14b is 1.5 times or more the diameter a of the body portion 14a, and the ratio of the stud hole 26B to the entire stud hole 26 is about 70%. The stud holding performance of the entire tire can be sufficiently ensured.
Further, in the studded tire 20 of the present invention, the regions where the straight stud holes 26A are formed and the regions where the flask stud holes 26B are formed are alternately arranged in the tire circumferential direction. Even if the ratio of 26B is about 70%, it is possible to ensure a stud holding performance substantially equivalent to that of a studded tire in which all stud holes 26 are flask-type stud holes 26B.

In the above-described embodiment, a case where a studded tire having a block pattern is manufactured has been described, but the present invention is also applicable to a tire having another tread pattern such as a rib pattern.
The present invention is also applicable when the sector mold 12 is a piece mold in which a plurality of pieces divided into a plurality of pieces in the tire circumferential direction or the tire width direction are held in a holder.
Moreover, in the said example, although the mold pin arrange | positioned at the circumferential direction edge part side of the sector mold 12 was made into the straight mold pin 14A, it is not restricted to this, When it sees from the axial direction of the sector mold 12 If the shape of the end of the sector mold is straight, the mold pin can reduce the stress applied to the rubber around the stud hole when the vulcanizer is pulled out. Can be prevented.

FIGS. 4A and 4B are diagrams showing another example of mold pins arranged in the sector mold 12. In this example, instead of the mold pin 14A, a mold pin 14J in which the end side of the sector mold 12 of the flange portion 14b of the flask-type mold pin 14B is removed is disposed on the circumferential end side. The mold pin 14J includes a body portion 14c and a bulge portion 14d provided on the front end side of the body portion 14c and protruding toward the center side of the sector mold 12.
When the flask-shaped mold pin 14B is pulled out from the tire tread 21, a large stress acts on the end side in the circumferential direction of the sector mold 12 of the stud hole 26B formed by the mold pin 14B. Similarly to the mold pin 14A, the shape of the sector mold on the circumferential end side is linear. Therefore, since the stress acting on the stud hole 26J formed by the mold pin 14J when the vulcanizing pot is removed can be reduced, the mold pin 14J can be easily pulled out without causing a hole crack.
Further, since the stud hole 26J formed by the mold pin 14J has a bulging portion 26f bulging from the body portion 26a at the bottom, the stud holding performance is superior to the straight stud hole 26A. The performance can be further improved.

表１に示すように、フラスコ型のモールドピンのみを配置して製造したタイヤでは、穴割れが発生したスタッド穴が５個もあるのに対し、ストレート型のモールドピンのみを配置して製造したタイヤと本発明のタイヤモールドを用いて製造したタイヤでは、いずれも、穴割れの発生が見られなかった。
これにより、セクターモールドの端部側に配置されるモールドピンのみをストレート型のモールドピンとするだけで、「穴割れ」を大幅に改善できることが確認された。 Straight mold pins are placed in the block formation region closest to the end and in the block formation region closest to the end, and flask type mold pins are placed in the block formation region provided on the center side. A studded tire (invention) manufactured using a tire mold provided with a sector mold, a tire (Comparative Example 1) manufactured by arranging only straight mold pins around the circumference, and a flask-type tire around the circumference Table 1 below shows the results of manufacturing tires (Comparative Example 2) manufactured by arranging only mold pins and examining “hole cracks”.
The tire size was 195 / 65R15, and 110 stud holes were provided per tire.
In the tire of the present invention, 32 straight stud holes are provided.
Regarding "hole cracking", the occurrence of cracks was investigated for the total number of stud holes in the tire after the vulcanizer was removed.

As shown in Table 1, in the tire manufactured by arranging only the flask-type mold pin, there are five stud holes in which hole cracking occurred, and only the straight-type mold pin was arranged and manufactured. In any of the tires manufactured using the tire and the tire mold of the present invention, no occurrence of hole cracking was observed.
As a result, it was confirmed that “hole cracking” can be significantly improved by using only straight mold pins as the mold pins arranged on the end side of the sector mold.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is apparent from the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  As described above, according to the present invention, even in a tire having a flask-shaped stud hole, cracking of the stud hole can be reliably suppressed, so that the production efficiency of the tire having excellent stud holding performance can be improved. It can be significantly improved.

10 tire mold, 11A, 11B side mold, 12 sector mold,
12a Inner peripheral surface, 13A, 13B protrusion, 14, 14A, 14B Mold pin,
14a trunk, 14b flange,
20 Studable tires (tires), 21 tire treads, 22 side portions,
23 circumferential grooves, 24 lug grooves, 25 blocks,
26, 26A to 26C Stud burying holes (stud holes).

Claims (5)

A pair of side molds for molding the tire side portions;
A tire mold including a plurality of sector molds provided with a plurality of protrusions for forming a tread pattern on an inner peripheral surface,
In the sector mold, a plurality of mold pins that protrude from the inner peripheral surface to the inside in the radial direction of the sector mold and form holes for burying studs in the land portion of the tire tread are arranged,
Of the mold pins, the shape of the mold pins arranged on the circumferential end side of the sector mold is linear when viewed from the axial direction of the tire mold in the circumferential direction of the sector mold,
The mold pin arranged on the center side of the sector mold has a cylindrical body portion and a flange portion having a diameter provided on the front end side of the body portion larger than the diameter of the body portion. mold.   The shape of the mold pin arranged at the position closest to the circumferential end of the sector mold and the mold pin arranged at the second closest position from the circumferential end of the sector mold are both shapes on the circumferential end side of the sector mold. The tire mold according to claim 1, wherein the tire mold is a linear mold pin.   3. The tire mold according to claim 1, wherein a mold pin disposed on a circumferential end portion side of the sector mold has a cylindrical shape.   The tire mold according to any one of claims 1 to 3, wherein a diameter of a flange portion of a mold pin arranged on a center side of the sector mold is 1.5 times or more of a diameter of a trunk portion. . Using a tire mold having a plurality of sector molds provided with a plurality of protrusions and mold pins for forming a tread pattern on the inner peripheral surface, holes for stud embedment are formed in the land portion of the tire tread. When manufacturing studded tires,
As the sector mold,
A mold pin having a linear shape on the circumferential end side of the sector mold when viewed from the axial direction of the tire mold is disposed on the circumferential end side of the sector mold, and a cylindrical body and the body A studded tire characterized by using a sector mold in which a mold pin having a flange portion having a diameter larger than a diameter of the body portion is disposed on the center side of the sector mold. Production method.

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