JP2019077127A - Tire vulcanization mold and tire manufacturing method - Google Patents

Abstract

To provide a tire vulcanization mold capable of enhancing appearance quality by preventing the molding of an unintentional cut-in in a TWI (tire wear indicator), and a tire manufacturing method using the same.SOLUTION: A tire vulcanization mold includes: a bone part 2 for molding a groove protruded inward in the tire radial direction from a tread molding surface 1; a recess 3 for forming a TWI provided by receding the top surface of the bone part 2; and a blade 4 for molding a sipe installed in the tread molding surface 1. The blade 4 arranged adjacent to the recess 3 has a first part 41, and a second part 42 laid continuous to the first part 41 in the sipe length direction. An inside end 41X of the first part 41 in the tire radial direction positions in the outer side than an inside end 42X of the second part 42 in the tire radial direction, and a step is formed therebetween. At least a part of the inside end 41X in the tire radial direction is embedded in the bone part 2 and positions in the outside of the recess 3 in the tire radial direction. The inside end 42X in the tire radial direction is exposed to a cavity 15 without being embedded in the bone part 2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a tire vulcanizing mold used for vulcanizing and forming a tire and a method of manufacturing the tire.

  The tire vulcanizing mold has a tread molding surface in contact with the tread surface of the tire. The tread molding surface is provided with a concavo-convex shape for forming a tread pattern. Such an uneven 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 a use limit due to wear is formed by a depression provided by recessing the top surface of the bone (eg, Patent Documents 1 and 2).

  When a cut called sipe is formed on the tread surface, a large number of sipe forming blades are attached to the tread forming surface of the mold. The sipe disposed adjacent to the TWI is molded by a blade 94 disposed adjacent to the recess 93 for TWI molding as shown in FIG. The blade 94 is partially embedded in the bone portion 92. In order to secure the sipe depth, the tire radial direction inner end 94 </ b> X of the blade 94 is brought close to the bottom surface of the recess 93. The sipe is formed by the non-embedded part of the blade 94, i.e. the part exposed to the cavity. Typically, the blade 94 is formed of a harder material than the bone 92.

  By the way, if the mold is repeatedly cleaned by blast treatment such as shot blasting, the bone portion 92 is worn out although it is very slight. On the other hand, the progress of the 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 wear of the bone portion 92, the tire radial direction inner end 94X of the blade 94 may be exposed on the bottom surface of the recess 93. As a result, an unintended cut is formed in the TWI, and although there is no problem in performance, there is a problem that the appearance quality is deteriorated.

Unexamined-Japanese-Patent No. 2003-251632 JP 2012-236301 A

  The present invention has been made in view of the above situation, and an object thereof is to provide a tire vulcanizing mold capable of preventing appearance of an unintended cut in a tread wear indicator to improve appearance quality, and a tire manufacturing method using the same. To provide.

  The above object can be achieved by the present invention as described below. That is, the tire vulcanizing mold according to the present invention comprises a tread molding surface in contact with a tread surface of a tire set in a cavity, and a groove molding groove portion projecting inward in the tire radial direction from the tread molding surface. A treadwear indicator recess formed by recessing the top surface of the bone and a sipe forming blade mounted on the tread molding surface, the blade being disposed adjacent to the recess The blade has a first portion and a second portion contiguous with the first portion in the length direction of the sipe, and the tire radial direction inner end of the first portion is closer to the tire radial direction inner end of the second portion Are also located radially outward of the tire, whereby a step is formed between the first portion and the second portion, and at least a portion of the tire radial direction inner end of the first portion is in the bone portion Buried in the above Mino located in the tire radial direction outer side, in which the tire radial direction inside end of the second portion is exposed to the cavity without being embedded in the bone. According to such a configuration, the blade (first portion) can be appropriately separated from the bottom of the recess to the outside in the tire radial direction, and as a result, the appearance of an unintended cut in the treadwear indicator (TWI) can be prevented. I can improve the quality.

  In order to prevent the formation of an unintended cut in the TWI, it is preferable that the tire radial direction 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.

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

  The method of manufacturing a tire according to the present invention includes the steps of setting an unvulcanized tire in the cavity of the above-described tire-vulcanized mold, and applying heat and pressure to the unvulcanized tire to perform vulcanization. According to this method, as described above, the appearance quality can be improved by preventing the formation of an unintended cut in the TWI.

A longitudinal sectional view schematically showing an example of a tire vulcanizing mold according to the present invention Cross-sectional view showing the periphery of a bone provided with a recess for TWI molding A perspective view showing the periphery of a bone provided with a recess for TWI molding Sectional view showing a modified example of the blade Sectional view showing the periphery of a bone part on which a normal blade is mounted

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

  FIG. 1 shows a cross section of a tire vulcanizing mold 10 along a tire meridian cross section, which 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 tire radial direction outer side, and the right direction is the tire radial direction inner side. FIG. 2 is an enlarged view of the main part of FIG. 1 and corresponds to a cross section taken along line A-A of FIG. In FIGS. 2 and 3, the upper direction is the tire radial direction outer side, and the lower direction is the tire radial direction inner side.

  As shown in FIGS. 1 to 3, the tire vulcanizing mold 10 protrudes from the tread molding surface 1 inward in the tire radial direction from the tread molding surface 1 in contact with the tread surface of the tire T set in the cavity 15. A groove 2 for forming a groove, a recess 3 for forming a treadwear indicator (TWI) formed by recessing the top surface of the bone 2, and a blade 4 for forming a sipe mounted on the tread forming surface 1 Equipped with Although FIG. 3 shows one blade 4 disposed adjacent to the recess 3 and one blade 5 disposed at a position not adjacent to the recess 3, actually, a large number of blades are tread-formed. It is attached to the surface 1.

  In the tire vulcanizing mold 10 of the present embodiment, a tread mold portion 11 for molding a tread portion of a tire T, side mold portions 12 and 13 for molding a sidewall portion of the tire T, and a bead portion of the tire T are fitted. And a pair of bead rings 14 to be engaged. The tread molding surface 1 is provided on the inner surface of the tread mold portion 11. As a material of the tread molding surface 1 and the bone portion 2, an aluminum material is exemplified. This aluminum material is a concept including not only pure aluminum-based materials but also aluminum alloys, and for example, Al-Cu-based, Al-Mg-based, Al-Mg-Si-based, Al-Zn-Mg-based, Al-Mn-based. And Al-Si systems. The blades 4 and 5 are formed of a harder material, such as stainless steel.

  The tread molding surface 1 is provided with a concavo-convex shape for forming a tread pattern. The uneven | corrugated shape is comprised by the bone part 2 and the recessed part divided by the bone part 2. As shown in FIG. On the tread surface of the tire after vulcanization, ribs and blocks are provided by the rubber filled in the recessed portions, and grooves for dividing them are formed by the bone portion 2. The bone portion 2 extending along the tire circumferential direction CD forms the main groove of the tread surface. Although only the bone 2 extending along the tire circumferential direction CD is shown in FIG. 3, the bone may extend in a direction intersecting with the tire circumferential direction CD to include a lateral groove.

  As shown in an enlarged manner in FIGS. 2 and 3, a recess 3 is provided on the top surface (inner 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 protruding from the groove bottom and is used as an index indicating the use limit due to the wear of the tread surface. The depth of the depression 3 is set to, for example, 1.6 mm or more.

  The blade 4 disposed adjacent to the recess 3 has a first portion 41 and a second portion 42 which is continuous with the first portion 41 in the sipe length direction (the left-right direction in FIG. 2). The first portion 41 is continued to the bone portion 2 side (left side in FIG. 2) of the second portion 42. The tire radial direction inner end 41X of the first portion 41 is located on the tire radial direction outer side with respect to the tire radial direction inner end 42X of the second portion 42, whereby a step is generated between the first portion 41 and the second portion 42 It is formed. The blade 4 shown in FIG. 2 has a shape obtained by cutting out one of the four corners of the rectangle that is close to the recess 3.

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

  According to this configuration, (the first portion 41 of) the blade 4 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 2 is worn away by blasting treatment such as shot blasting and the bottom surface of the recess 3 is slightly lowered, the tire radial direction inner end (the tire radial direction inner end 41X of the first portion 41) of the blade 4 is Since it becomes difficult to expose on the bottom of the recess 3, it is possible to prevent the formation of an unintended cut in TWI and improve the appearance quality.

  In order to prevent the formation of an unintended cut in the TWI, the tire radial direction inner end 41X of the first portion 41 is preferably separated by 0.5 mm or more from the bottom surface of the recess 3 outward in the tire radial direction. That is, the distance D1 from the bottom surface of the recess 3 to the tire radial direction inner end 41X 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 direction inner end 41X of the first portion 41 is preferably separated by 2 mm or more from the tread molding surface 1 inward in the tire radial direction. That is, the distance D2 from the tread molding surface 1 to the tire radial direction inner end 41X 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 with the sipe not adjacent to the TWI (for example, the sipe formed by the blade 5), causing uneven wear Could be

  From the viewpoint of securing the sipe depth, the tire radial direction inner end 42X of the second portion 42 is disposed at a height that matches the extension line EL3 of the bottom surface of the recess 3, or slightly (for example, 0.2 mm or less Is preferably provided at a height which is on the outer side in the tire radial direction than the extension line EL3. That is, the distance D3 from the extension line EL3 to the tire radial direction inner end 42X is preferably 0 to 0.2 mm.

  The embedded length L1 of the blade 4 with respect to the bone 2 is preferably 50% or less of the width W2 (see FIG. 3) of the bone 2. The buried length L 1 is measured at the height of the tread molding 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 this embodiment, the side edge 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 the groove width direction outer side from the side of the bone 2 (from the bone 2 Away). The length L2 of the portion of the tire radial direction inner end 41X exposed to the cavity 15 is set to, for example, 0.5 mm or more. The length L2 is set to, for example, 2 mm or less.

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

  Since the modification of FIG. 4 is the same structure as the above-mentioned embodiment except for the shape of the blade 4, the common points are omitted and the differences are mainly described. The same parts as the parts described in the above-described embodiment are denoted by the same reference numerals, and redundant description will be omitted. In this example, the side edge 4S of the step extending in the tire radial direction butting the tire radial inner end 41X and the tire radial inner end 42X in a row is butted to 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 direction 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 in the vicinity of the groove wall is secured, it is possible to prevent uneven wear by eliminating the difference in rigidity with other sipe.

  The method of manufacturing a tire using the mold 10 described above includes the steps 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 mold 10 after use is subjected to cleaning by blasting as required. Repeated cleaning wears out the bone 2 and even if the bottom of the recess 3 is lowered slightly, the tire radial direction inner end of the blade 4 is hard to be exposed on the bottom of the recess 3 and therefore an unintended cut is formed in TWI Can improve the appearance quality.

  The tire vulcanizing mold described above is equivalent to a conventional tire vulcanizing mold except that the blade disposed adjacent to the recess for TWI molding is configured as described above, and the conventionally known shape and material are used. Any of the mechanisms, etc. can be employed in the present invention.

  The present invention is not limited to the embodiment described above, and various improvements and modifications can be made without departing from the spirit of the present invention. For example, in the above-mentioned embodiment, although the mold structure provided with a tread type part and a pair of side type parts was adopted, it is not limited to this, for example Alternatively, a mold structure may be adopted. The sipe forming blade may have a wavelike shape extending along the length of the sipe.

DESCRIPTION OF REFERENCE NUMERALS 1 tread forming surface 2 bone portion 3 dent 4 blade 4S step side edge 10 tire vulcanizing mold 15 cavity 41 first portion 41X first portion of tire radial direction inner end 41 Y first portion of tire radial outer end 42 Second portion 42X Tire radial direction inner end 42Y of second portion Tire radial direction outer end of second portion

Claims (5)

A tread molding surface in contact with the tread surface of the tire set in the cavity;
A groove-forming bone portion protruding inward in the tire radial direction from the tread molding surface;
A treadwear indicator molding recess provided by recessing the top surface of the bone portion;
A sipe forming blade mounted on the tread forming surface;
The blade disposed adjacent to the recess has a first portion, and a second portion contiguous with the first portion in the length direction of the sipe,
The tire radial direction inner end of the first portion is positioned on the tire radial direction outer side than the tire radial direction inner end of the second portion, whereby a step is formed between the first portion and the second portion Yes,
At least a part of the tire radial direction inner end of the first portion is embedded in the bone portion and positioned on the tire radial direction outer side of the recess, and the tire radial direction inner end of the second portion is embedded in the bone portion A tire vulcanizing mold exposed to the cavity without being damaged.   The tire vulcanizing mold according to claim 1, wherein the tire radial direction 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.   A side edge portion of the step extending in the tire radial direction connecting the tire radial direction inner end of the first portion and the tire radial direction inner end of the second portion is separated outward in the groove width direction from the side surface of the bone portion The tire vulcanizing mold according to claim 1 or 2.   A side edge portion of the step extending in the tire radial direction by connecting the tire radial direction inner end of the first portion and the tire radial direction inner end of the second portion butts against the side surface of the bone portion. The tire vulcanizing mold according to 1 or 2.   The tire manufacturing method including the process of setting an unvulcanized tire in the cavity of the tire vulcanizing mold according to any one of claims 1 to 4 and applying heat and pressure to the unvulcanized tire to perform vulcanization. .

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