JP6930893B2 - Tire vulcanization mold and tire manufacturing method - Google Patents

Description

The present invention relates to a tire vulcanization die and a tire manufacturing method used for vulcanization molding of a tire.

The tire vulcanization die includes a tread molded surface in contact with the tread surface of the tire. The tread molding surface is provided with an uneven shape for forming a tread pattern. Such a concave-convex shape includes a groove-forming bone portion protruding inward in the tire radial direction from the tread forming surface. A treadwear indicator (hereinafter sometimes referred to as "TWI") provided at the bottom of the groove to indicate the limit of use due to wear is formed by a recess provided by recessing the top surface of the bone (for example). See Patent Documents 1 and 2).

When a notch called a sipe is formed on the tread surface, a large number of blades for sipe forming are mounted on the tread-molded surface of the mold. The sipe arranged adjacent to the TWI is formed by a blade 94 arranged adjacent to the TWI forming recess 93 as shown in FIG. A part of the blade 94 is embedded in the bone portion 92. In order to secure the sipe depth, the tire radial inner end 94X of the blade 94 is brought close to the bottom surface of the recess 93. The sipe is formed by the unembedded portion of the blade 94, i.e. the portion exposed to the cavity. Usually, the blade 94 is made of a material that is harder than the bone 92.

By the way, when the mold is repeatedly cleaned by blasting such as shot blasting, the bone portion 92 is slightly worn. On the other hand, the progress of wear of the blade 94 is relatively slow. Therefore, when the bottom surface of the recess 93 is lowered (moved upward in FIG. 5) due to the abrasion of the bone portion 92, the tire radial inner end 94X of the blade 94 may be exposed on the bottom surface of the recess 93. As a result, an unintended notch is formed in the TWI, and although there is no problem in terms of performance, there is a problem that the appearance quality is deteriorated.

Japanese Unexamined Patent Publication No. 2003-251632 Japanese Unexamined Patent Publication No. 2012-236301

The present invention has been made in view of the above circumstances, and an object of the present invention is a tire vulcanization die capable of preventing unintended notch molding with a treadwear indicator and improving appearance quality, and a tire manufacturing method using the same. Is to provide.

The above object can be achieved by the present invention as described below. That is, the tire sulfide mold according to the present invention includes a tread forming surface in contact with the tread surface of the tire set in the cavity, and a groove forming bone portion protruding inward in the tire radial direction from the tread forming surface. A depression for forming a treadwear indicator provided by recessing the top surface of the bone portion and a blade for forming a sipe mounted on the tread forming surface are provided and arranged adjacent to the recess. The blade has a first portion and a second portion connected to the first portion in the tire radial direction, and the tire radial inner end of the first portion is from the tire radial inner end of the second portion. Is also located on the outer side in the tire radial direction, whereby a step is formed between the first portion and the second portion, and at least a part of the inner end in the tire radial direction of the first portion is on the bone portion. It is embedded and located on the outer side of the recess in the tire radial direction, and the inner end of the second portion in the tire radial direction is exposed in the cavity without being embedded in the bone portion. According to such a configuration, the blade (the first part) can be appropriately separated from the bottom surface of the recess outward in the radial direction of the tire, and as a result, the appearance of the treadwear indicator (TWI) is prevented from forming an unintended notch. The quality can be improved.

In order to prevent unintended notch molding in TWI, it is preferable that the tire radial inner end of the first portion is separated from the bottom surface of the recess by 0.5 mm or more outward in the tire radial direction.

The side edge portion of the step extending in the tire radial direction by connecting the tire radial inner end of the first portion and the tire radial inner end of the second portion is separated from the side surface of the bone portion outward in the groove width direction. However, it may be abutted against the side surface of the bone portion. In the latter case, it is convenient to secure the sipe depth near the groove wall.

The method for manufacturing a tire according to the present invention includes a step of setting an unvulcanized tire in the cavity of the tire vulcanization die described above and applying heat and pressure to the unvulcanized tire to perform vulcanization. According to such a method, it is possible to prevent unintended notch molding in TWI as described above and improve the appearance quality.

Longitudinal sectional view schematically showing an example of a tire vulcanization die according to the present invention. Cross-sectional view showing the periphery of a bone portion provided with a recess for TWI molding. Perspective view showing the periphery of the bone portion provided with the recess for TWI molding. Cross-sectional view showing a modified example of the blade Cross-sectional view showing the periphery of the bone to which a normal blade is attached

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross section of the tire vulcanization die 10 along the cross section of the tire meridian, and the tire vulcanization die 10 is in a closed state. The tire T is set with the tire width direction facing up and down. In FIG. 1, the left direction is the outside in the tire radial direction, and the right direction is the inside in the tire radial direction. FIG. 2 is an enlarged view of the main part of FIG. 1, and corresponds to the cross section taken along the line AA of FIG. In FIGS. 2 and 3, the upper direction is the outer side in the tire radial direction, and the lower direction is the inner side in the tire radial direction.

As shown in FIGS. 1 to 3, the tire vulcanization mold 10 protrudes inward in the tire radial direction from the tread forming surface 1 in contact with the tread surface of the tire T set in the cavity 15 and the tread forming surface 1. A bone portion 2 for grooving, a recess 3 for forming a tread wear indicator (TWI) provided by denting the top surface of the bone portion 2, and a blade 4 for sipe forming mounted on the tread forming surface 1. To be equipped with. FIG. 3 shows one blade 4 arranged adjacent to the recess 3 and one blade 5 arranged not adjacent to the recess 3, but in reality, many blades are tread-formed. It is mounted on surface 1.

In the tire vulcanization die 10 of the present embodiment, the tread mold portion 11 for forming the tread portion of the tire T, the side mold portions 12 and 13 for forming the sidewall portion of the tire T, and the bead portion of the tire T are fitted. It includes a pair of bead rings 14 to be combined. The tread molding surface 1 is provided on the inner surface of the tread mold portion 11. As the material of the tread molded surface 1 and the bone portion 2, an aluminum material is exemplified. This aluminum material is a concept that includes not only pure aluminum-based materials but also aluminum alloys. For example, Al-Cu-based, Al-Mg-based, Al-Mg-Si-based, Al-Zn-Mg-based, and Al-Mn-based. , Al-Si system can be mentioned. The blades 4 and 5 are made of a harder material such as stainless steel.

The tread molding surface 1 is provided with an uneven shape for forming a tread pattern. The uneven shape is composed of a bone portion 2 and a recess defined by the bone portion 2. The tread surface of the tire after vulcanization is provided with ribs and blocks by rubber filled in the recesses, and a groove for partitioning them is formed by the bone portion 2. The bone portion 2 extending along the tire circumferential direction CD forms a main groove on the tread surface. Although FIG. 3 shows only the bone portion 2 extending along the tire circumferential direction CD, it may include a bone portion extending in a direction intersecting the tire circumferential direction CD to form a lateral groove.

As shown in an enlarged manner in FIGS. 2 and 3, a recess 3 is provided on the top surface (inner side surface in the tire radial direction) of the bone portion 2. At the bottom of the groove formed by the bone portion 2, TWI is formed by the rubber filled in the recess 3. The TWI is provided so as to rise from the bottom of the groove and is used as an index indicating the limit of use due to wear of the tread surface. The depth of the recess 3 is set to, for example, 1.6 mm or more.

The blade 4 arranged adjacent to the recess 3 has a first portion 41 and a second portion 42 connected to the first portion 41 in the sipe length direction (left-right direction in FIG. 2). The first portion 41 is connected to the bone portion 2 side (left side in FIG. 2) of the second portion 42. The tire radial inner end 41X of the first portion 41 is located outside the tire radial inner end 42X of the second portion 42, thereby creating a step between the first portion 41 and the second portion 42. It is formed. The blade 4 shown in FIG. 2 has a shape in which one of the four corners of the rectangle close to the recess 3 is cut out.

At least a part of the tire radial inner end 41X of the first portion 41 is embedded in the bone portion 2 and is located on the tire radial outer side of the recess 3. In the present embodiment, a part of the tire radial inner end 41X is embedded in the bone portion 2, and the rest is exposed in the cavity 15. The tire radial medial end 42X of the second portion 42 is exposed in the cavity 15 without being embedded in the bone portion 2. The tire radial outer end 41Y of the first portion 41 and the tire radial outer end 42Y of the second portion 42 are both embedded in the tread forming surface 1.

According to such a configuration, the blade 4 (the first portion 41) can be appropriately separated from the bottom surface of the recess 3 outward in the tire radial direction. As a result, even if the bone portion 2 is worn away by blasting such as shot blasting and the bottom surface of the recess 3 is slightly lowered, the tire radial inner end of the blade 4 (the tire radial inner end 41X of the first portion 41) remains. Since it is difficult to expose to the bottom surface of the recess 3, it is possible to prevent unintended notch molding in TWI and improve the appearance quality.

In order to prevent unintended notch molding in TWI, it is preferable that the tire radial inner end 41X of the first portion 41 is separated from the bottom surface of the recess 3 by 0.5 mm or more outward in the tire radial direction. That is, the distance D1 from the bottom surface of the recess 3 to the inner end 41X in the tire radial direction is preferably 0.5 mm or more, and more preferably 0.1 mm or more. The distance D1 and D2 and D3 described later are both measured along the sipe depth direction (vertical direction in FIG. 2).

The tire radial inner end 41X of the first portion 41 is preferably separated from the tread molding surface 1 inward by 2 mm or more in the tire radial direction. That is, the distance D2 from the tread molding surface 1 to the inner end 41X in the tire radial direction is preferably 2 mm or more. If this is less than 2 mm, the sipe depth near the groove wall becomes too small, causing a difference in rigidity between the sipe not adjacent to the TWI (for example, the sipe formed by the blade 5), which causes uneven wear. There is a risk of becoming.

From the viewpoint of ensuring the sipe depth, the tire radial inner end 42X of the second portion 42 is arranged at a height corresponding to the extension line EL3 of the bottom surface of the recess 3, or is slightly (for example, 0.2 mm or less). ), It is preferable that the tires are arranged at a height outside the extension line EL3 in the radial direction of the tire. That is, the distance D3 from the extension line EL3 to the inner end 42X in the tire radial direction is preferably 0 to 0.2 mm.

The embedded length L1 of the blade 4 with respect to the bone portion 2 is preferably 50% or less of the width W2 of the bone portion 2 (see FIG. 3). The buried length L1 is measured at the height of the tread forming surface 1. The width W2 corresponds to the opening width of the main groove formed by the bone portion 2, and is measured along the groove width direction of the main groove.

In the present embodiment, the side edge portion 4S of the step extending in the tire radial direction by connecting the tire radial inner end 41X and the tire radial inner end 42X is outside the groove width direction from the side surface of the bone portion 2 (from the bone portion 2). It is separated in the direction of separation). The length L2 of the portion exposed to the cavity 15 of the inner end 41X in the tire radial direction is set to, for example, 0.5 mm or more. Further, the length L2 is set to, for example, 2 mm or less.

In the present embodiment, the tire radial inner end 41X of the first portion 41 extends parallel to the bottom surface of the recess 3. Further, the side edge portion 4S of the step is connected to the inner end 41X in the tire radial direction via the arc R. This arc R forms a rounded portion at the sipe bottom formed at the inner end of the blade 4 in the tire radial direction. This prevents the concentration of distortion at the bottom of the sipe and suppresses the occurrence of chunking.

Since the modified example of FIG. 4 has the same configuration as the above-described embodiment except for the shape of the blade 4, the differences will be mainly described by omitting the common points. The same parts as those described in the above-described embodiment are designated by the same reference numerals, and duplicate description will be omitted. In this example, the side edge portion 4S of the step extending in the tire radial direction by connecting the tire radial inner end 41X and the tire radial inner end 42X is abutted against the side surface of the bone portion 2. The side edge portion 4S is inclined along the side surface of the bone portion 2 while extending in the tire radial direction. In this case, the entire tire radial inner end 41X of the first portion 41 is embedded in the bone portion 2, and the length L2 shown in FIG. 2 is 0 mm. According to this, since the sipe depth near the groove wall is secured, it is possible to eliminate the difference in rigidity with other sipe and prevent uneven wear.

The method for manufacturing a tire using the mold 10 described above includes a step of setting an unvulcanized tire in the cavity 15 of the mold 10 and applying heat and pressure to the unvulcanized tire to perform vulcanization. .. The tire is expanded and deformed by the expansion of a rubber bag called a bladder (not shown), and the tread surface is pressed against the tread molding surface 1. The used mold 10 is cleaned by blasting if necessary. Even if the bone portion 2 is worn away by repeated cleaning and the bottom surface of the recess 3 is slightly lowered, the inner end of the blade 4 in the tire radial direction is not easily exposed to the bottom surface of the recess 3, so that an unintended notch is formed by TWI. Can be prevented and the appearance quality can be improved.

The tire vulcanization die described above is the same as a normal tire vulcanization die except that the blades arranged adjacent to the recess for TWI molding are configured as described above, and has a conventionally known shape and material. , Mechanism, etc. can all be adopted in the present invention.

The present invention is not limited to the above-described embodiment, and various improvements and changes can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, a mold structure including a tread mold portion and a pair of side mold portions has been adopted, but the present invention is not limited to this, and for example, the central portion of the tread mold portion is divided into upper and lower parts. A mold structure may be adopted. Further, the blade for sipe forming may have a shape extending in a wavy shape along the sipe length direction.

1 Tread molding surface 2 Bone 3 Depression 4 Blade 4S Step side edge 10 Tire vulcanization mold 15 Cavity 41 1st part 41X 1st part tire radial inner end 41Y 1st part tire radial outer end 42 2nd part 42X 2nd part tire radial inner end 42Y 2nd part tire radial outer end

Claims (3)

The tread molded surface in contact with the tread surface of the tire set in the cavity,
A bone portion for groove forming protruding inward in the tire radial direction from the tread forming surface, and
A recess for forming a treadwear indicator provided by recessing the top surface of the bone portion, and a recess for forming the tread wear indicator.
A blade for sipe molding mounted on the tread molding surface is provided.
The blade arranged adjacent to the recess has a first portion and a second portion connected to the first portion in the sipe length direction.
The tire radial inner end of the first portion is located outside the tire radial inner end of the second portion, whereby a step is formed between the first portion and the second portion. And
At least a part of the tire radial medial end of the first portion is embedded in the bone portion and located outside the tire radial direction of the recess, and the tire radial medial end of the second portion is embedded in the bone portion. Rukoto is exposed to the cavity without
A tire addition in which a side edge portion of the step extending in the tire radial direction by connecting the tire radial inner end of the first portion and the tire radial inner end of the second portion is abutted against the side surface of the bone portion. Vulcanization mold. The tire vulcanization die according to claim 1, wherein the inner end in the tire radial direction of the first portion is separated from the bottom surface of the recess by 0.5 mm or more outward in the tire radial direction. A tire manufacturing method including a step of setting an unvulcanized tire in the cavity of the tire vulcanizing die according to claim 1 or 2 and applying heat and pressure to the unvulcanized tire to perform vulcanization.

Images