JP6567405B2 - Tire vulcanization mold and tire manufacturing method - Google Patents

Description

  The present invention relates to a tire vulcanization mold and a tire manufacturing method.

  Characters, symbols, figures, and the like are displayed on the side portions of the pneumatic tire. These characters, symbols, figures, and the like are formed as raised portions that are raised from the surroundings. In order to form the raised portion, a recess is provided inside a tire vulcanization mold used for vulcanization molding of a pneumatic tire (for example, the embodiments of Patent Documents 1 and 2 and Patent Documents). 3 background art). A bulge is formed by rubber entering the recess during vulcanization molding.

  In addition, side protectors, rim protectors, and the like are also formed as raised portions on the side portions of the pneumatic tire. These raised portions are also formed by the recesses inside the tire vulcanization mold.

Japanese Unexamined Patent Publication No. 63-151410 JP 2007-230162 A JP 2008-221899 A

  However, in the conventional tire vulcanization mold, during the vulcanization molding, the fluid rubber and the surface of the recess are caught and resistance is generated, and it is difficult to fill the rubber to the corner of the recess. For this reason, a so-called bear in which a part of the raised portion is lost is easily generated.

  Therefore, an object of the present invention is to provide a tire vulcanization molding die and a tire manufacturing method in which rubber is easily filled up to the corner of the concave portion inside the mold during vulcanization molding.

  The tire vulcanization mold according to the embodiment is a tire vulcanization mold having a recess for forming a raised portion on a tire side portion, wherein the recess is from an opening end to the inside of the mold to the outside of the mold. It has a side wall surface extending toward the surface, and the surface roughness of the portion on the opening end side of the side wall surface is smaller than the surface roughness of the portion outside the mold.

  Moreover, the tire manufacturing method of the embodiment includes a step of setting an unvulcanized tire inside the tire vulcanization molding die and performing vulcanization molding by heating and pressurizing the unvulcanized tire. Features.

  According to the present embodiment, fluid rubber can travel to the corners of the recesses because it can proceed with almost no resistance from the side wall surface, either at the opening end side of the side wall surface or outside the mold. It is easy to be done.

FIG. 2 is a half sectional view in the width direction of a pneumatic tire 20 that is vulcanized and molded by a tire vulcanization mold 10. Sectional drawing of the axial direction of the tire vulcanization molding die 10 of embodiment. FIG. 3 is an enlarged cross-sectional view around a first recess 30 in FIG. 2. FIG. 3 is an enlarged cross-sectional view around a second recess 40 in FIG. 2. The figure showing a mode that the rubber | gum R penetrate | invades into the 1st recessed part 30 of FIG. The perspective view of the recessed part 50 for forming alphabet letter T as a protruding part in a tire side part.

  This embodiment will be described with reference to the drawings. The drawings may be exaggerated for the purpose of explanation.

  First, a pneumatic tire 20 vulcanized and molded by the tire vulcanization mold 10 is shown in FIG. FIG. 1 shows only a portion on the right side of the tire equator CL at the center in the tire width direction. In FIG. 1, the upper side is the tire radial direction outer side, the lower side is the tire radial direction inner side, the right side is the tire width direction outer side, and the tire equator CL side is the tire width direction inner side.

  The pneumatic tire 20 includes a bead portion on both sides in the tire width direction, a carcass that forms a tire skeleton between the bead portions, a belt layer provided on the outer side in the tire radial direction from the carcass, and an outer side in the tire radial direction from the belt layer. And a tread portion made of rubber and a side portion provided on the outer side in the tire width direction from the carcass. The surface of the tread portion on the outer side in the tire radial direction is a contact surface 21. The side portion of the pneumatic tire 20 is provided with a raised portion that is raised from the surroundings. As this raised part, the side protector 22, the rim protector 26, etc. are mentioned, for example.

  Here, the side protector 22 is for preventing the tire side portion from being damaged when it comes into contact with a curbstone or a step on the road, and is provided at a location near the ground contact surface 21 in the tire side portion. . The side protector 22 is formed as a raised portion that protrudes outward in the tire width direction from the periphery thereof. The side protector 22 has an outer surface 23 on the outer side in the tire width direction and a raised surface 24 that protrudes from the periphery of the side protector 22 toward the outer surface 23.

  The rim protector 26 is a portion that contacts the rim flange when the pneumatic tire 20 is assembled to the rim. The rim protector 26 is formed as a raised portion that protrudes outward in the tire width direction from both sides in the tire radial direction. The rim protector 26 has two raised surfaces 28 that protrude from both sides in the tire radial direction toward the top 27 of the rim protector 26. The rim protector 26 is provided over one circumference in the tire circumferential direction.

  Next, FIG. 2 shows a tire vulcanization mold 10 according to this embodiment. The tire vulcanization mold 10 includes a plurality of sectors 12 arranged on the circumference, a pair of side plates 14 provided on both sides in the axial direction of the circumference formed by the plurality of sectors 12, and a pair of beads (not shown). With a ring. At the time of vulcanization molding, an unvulcanized tire 20a is set inside the tire vulcanization molding die 10 as indicated by a broken line in the drawing. The sector 12, the side plate 14, and the bead ring are molding members that mold the pneumatic tire 20, and the inner surfaces of these molds are molding surfaces 18 that mold the tire surface. The plurality of sectors 12 mainly form a tread part, the pair of side plates 14 form a tire side part, and the pair of bead rings form a bead part. The material of the sector 12 is not limited, but is, for example, aluminum or an aluminum alloy (for example, an Al—Cu, Al—Mg, Al—Mn, or Al—Si alloy). Moreover, although the material of the side plate 14 and the bead ring is not limited, for example, a steel material such as a general structural rolled steel material (for example, SS400) is used. The material of the side plate 14 and the material of the bead ring may be the same or different.

  The side plate 14 is provided with a plurality of recesses that are recessed from the periphery when viewed from the inside of the mold. These concave portions are for forming the above-described raised portions in the tire side portion. As this recessed part, the 1st recessed part 30 which forms the side protector 22, and the 2nd recessed part 40 which forms the rim protector 26 are mentioned, for example.

  As shown in FIG. 3, the first recess 30 forming the side protector 22 has a bottom surface 32 and a side wall surface 34. The side wall surface 34 is a surface that extends from the opening end 31 to the inside of the mold toward the outside of the mold, and the bottom surface 32 is a surface that connects the end portions of the side wall surface 34 outside the mold. A portion of the side wall surface 34 on the opening end 31 side toward the inside of the mold is an R-shaped curved surface. This curved surface is referred to as an opening-side curved surface 35. On the other hand, a portion of the side wall surface 34 on the back side of the concave portion (outside the mold) from the opening-side curved surface 35 is a flat surface. This plane is referred to as a back side wall surface 36. The opening-side curved surface 35 and the back side wall surface 36 are continuous.

  In the first recess 30, the surface roughness of the opening-side curved surface 35 is the smallest, the surface roughness of the bottom surface 32 is the next smallest, and the surface roughness of the back side wall surface 36 is the largest. That is, the opening-side curved surface 35 is the smoothest, the bottom surface 32 is the next smoothest, and the back side wall surface 36 is the roughest. Here, there are various types of surface roughness such as arithmetic average roughness, maximum height, ten-point average roughness, etc., but this relationship is established at least in arithmetic average roughness Ra defined in JIS B 0601-2001. It ’s fine.

  Although the specific value of arithmetic mean roughness Ra is not limited, For example, it is a value within the following range. The arithmetic mean roughness Ra of the opening-side curved surface 35 is 1.1 μm or more and less than 2.0 μm, preferably 1.2 μm or more and less than 1.5 μm. The arithmetic average roughness Ra of the bottom surface 32 is 1.1 μm or more and less than 2.0 μm, preferably 1.4 μm or more and less than 1.8 μm. The arithmetic average roughness Ra of the back side wall surface 36 is 1.1 μm or more and less than 2.5 μm, preferably 2.0 μm or more and less than 2.5 μm. The arithmetic average roughness Ra of the molding surface 18 is not limited, but is, for example, not less than 2.5 μm and less than 4.5 μm.

  As shown in FIG. 4, the second recess 40 forming the rim protector 26 has two side wall surfaces 44. The two side wall surfaces 44 are connected at the bottom 42. The two side wall surfaces 44 are curved so that the second recess 40 expands toward the inside of the mold. The side wall surface 44 has a curved surface on the opening end 41 side to the inner side of the mold (this curved surface is referred to as an opening-side curved surface 45) and a curved surface on the back side of the concave portion (outside the mold) from the opening-side curved surface 45 Wall surface 46). The opening-side curved surface 45 and the back side wall surface 46 continuously form one curved surface.

  In the second recess 40, the surface roughness of the opening-side curved surface 45 is smaller than the surface roughness of the back side wall surface 46. That is, the opening-side curved surface 45 is smoother than the back side wall surface 46. As in the case of the first recess 30, it is sufficient that this relationship is satisfied at least in the arithmetic average roughness Ra defined in JIS B 0601-2001.

  Although the specific value of arithmetic mean roughness Ra is not limited, For example, it is a value within the following range. The arithmetic mean roughness Ra of the opening-side curved surface 45 is 1.1 μm or more and less than 2.0 μm, preferably 1.2 μm or more and less than 1.5 μm. The arithmetic average roughness Ra of the back wall surface 46 is 1.1 μm or more and less than 2.5 μm, and preferably 2.0 μm or more and less than 2.5 μm.

  The first recess 30 and the second recess 40 are provided with vent holes (not shown) that communicate with the outside of the mold. The air remaining in these recesses during vulcanization molding is discharged to the outside of the mold through the vent hole.

  When vulcanization molding is performed with the tire vulcanization mold 10, the unvulcanized tire 20 a is set inside the tire vulcanization mold 10. The unvulcanized tire 20a is a tire before vulcanization molding in which the constituent members of the pneumatic tire 20 are manufactured in a predetermined order on a molding drum, and the detailed manufacturing method is not limited. After the unvulcanized tire 20a is set, a bladder (not shown) disposed inside the unvulcanized tire 20a expands, and the surface of the unvulcanized tire 20a is pressed against the molding surface 18. Further, the inside of the mold is held at a vulcanization molding temperature (for example, 130 to 200 ° C.). Then, the rubber of the unvulcanized tire 20a having fluidity reaches the vulcanization molding temperature and starts to enter the recess of the side plate 14.

  A state in which the rubber R enters the first recess 30 is shown in FIG. In addition, the arrow in a figure has shown the direction where rubber | gum R advances. First, as shown in FIG. 5A, the rubber R advances from an oblique direction with respect to the normal direction of the opening-side curved surface 35 of the first recess 30 and is pressed against the opening-side curved surface 35 as it is. The rubber R pressed against the opening-side curved surface 35 proceeds toward the bottom surface 32 along the opening-side curved surface 35. At this time, since the surface roughness of the opening-side curved surface 35 is small and there is no large unevenness on the opening-side curved surface 35 that the rubber R trying to advance along the opening-side curved surface 35 is caught, Proceed without great resistance.

  Next, as shown in FIG. 5B, the rubber R that has reached the back side wall surface 36 proceeds in parallel to the back side wall surface 36 toward the bottom surface 32 while being in contact with the back side wall surface 36. Here, since the surface roughness of the back side wall surface 36 is large and the back side wall surface 36 has relatively large irregularities, the rubber R advances while contacting only the upper part of the convex portion. Therefore, the contact area between the rubber R and the back side wall surface 36 is reduced, and the rubber R advances without receiving a large resistance due to contact from the back side wall surface 36.

  Next, as shown in FIG. 5C, the rubber R reaches a part of the bottom surface 32. At this time, the rubber R advances from the normal direction of the bottom surface 32 or an oblique direction with respect to the normal direction, and is pressed against the bottom surface 32 as it is. The rubber R pressed against the bottom surface 32 starts to advance parallel to the bottom surface 32 toward the corner of the first recess 30 while contacting the bottom surface 32. Here, the surface roughness of the bottom surface 32 is larger than the surface roughness of the opening-side curved surface 35 and smaller than the surface roughness of the back side wall surface 36. For this reason, the bottom surface 32 has few large irregularities so that the rubber R which is pressed against the bottom surface 32 and starts to advance along the bottom surface 32 is caught. Therefore, the rubber R pressed against the bottom surface 32 starts to travel along the bottom surface 32 without receiving a large resistance from the bottom surface 32. However, since the bottom surface 32 has some irregularities, when the rubber R continues to advance parallel to the bottom surface 32 while being in contact with the bottom surface 32, the rubber R continues to be in contact with the top of the convex portion. Therefore, the contact area between the rubber R and the bottom surface 32 is reduced to some extent, and the rubber R continues to travel along the bottom surface 32 without receiving a large resistance from the bottom surface 32 due to contact. Finally, the rubber R is filled up to the corners of the first recess 30.

  Although not shown, even when the rubber R enters the second recess 40, the rubber R first advances from an oblique direction with respect to the normal direction of the opening-side curved surface 45 and is pressed against the opening-side curved surface 45. The rubber R pressed against the opening-side curved surface 45 proceeds toward the bottom 42 along the opening-side curved surface 45. Here, since the surface roughness of the opening-side curved surface 45 is small, the rubber R proceeds without receiving a large resistance from the opening-side curved surface 45.

  Next, the rubber R that has reached the back side wall surface 46 proceeds in parallel with the back side wall surface 46 toward the bottom 42 while being in contact with the back side wall surface 46. Here, since the surface roughness of the back side wall surface 46 is large, the contact area between the rubber R and the back side wall surface 46 is reduced in the same manner as described above, and the rubber R does not receive a large resistance due to contact from the back side wall surface 46. Proceed along the back side wall surface 46. Finally, the rubber R is filled up to the bottom 42 which is the corner of the second recess 40.

  When the vulcanization molding starts and a predetermined time elapses, the pneumatic tire 20 is taken out from the tire vulcanization mold 10. By this time, the rubber R has been filled into the corners of the first recess 30 and the second recess 40.

  As described above, in the tire vulcanization mold 10 of the present embodiment, of the side wall surface of the recess, the portion on the opening end side of the recess toward the inside of the mold (the opening-side curved surface 35 of the first recess 30 and the first 2) The surface roughness of the opening-side curved surface 45 of the recess 40 is smaller than the surface roughness of the portion outside the mold (the back wall surface 36 of the first recess 30 and the back wall surface 46 of the second recess 40). . Therefore, as described above, when the rubber R advances in the recess, it does not receive a large resistance from the opening end side portion of the side wall surface or the portion outside the mold. Therefore, the rubber R is easily filled up to the corners of the recesses.

  In the first recess 30, since the surface roughness of the bottom surface 32 is smaller than the surface roughness of the back side wall surface 36, when the rubber R pressed against the bottom surface 32 starts to advance along the bottom surface 32, the bottom surface 32. You can begin to progress without much resistance. Further, since the surface roughness of the bottom surface 32 is larger than the surface roughness of the opening-side curved surface 35, when the rubber R continues to advance parallel to the bottom surface 32 while being in contact with the bottom surface 32, the rubber R continues to proceed without receiving a large resistance from the bottom surface 32. Can do. Therefore, the rubber R is easily filled up to the corner of the first recess 30.

  Here, since the opening-side curved surface 35 of the first recess 30 and the opening-side curved surface 45 of the second recess 40 are curved surfaces, the rubber R is pressed against a part of these curved surfaces (specifically, the rubber R is pressed against the curved surface). And the rubber R is likely to receive resistance from these curved surfaces. Therefore, the effect of the small surface roughness of these curved surfaces is great.

  Various changes, substitutions, omissions, and the like can be made to the above embodiments without departing from the scope of the invention.

  First, the concave portion of the tire vulcanization mold 10 is not limited to the first concave portion 30 and the second concave portion 40 of the above embodiment. For example, on the side portion of the pneumatic tire 20, characters (including alphabets, numbers, kana characters, and other various characters including decorative ones), symbols (including signs, marks, pictures, etc.) Symbol) and at least one of the figures is provided as a raised portion. The tire vulcanization mold 10 is provided with a recess for forming at least one of the letters, symbols, and figures. As an example, a recess 50 for forming the letter T is shown in FIG. Similar to the first recess 30, the recess 50 has a bottom surface 52 and a sidewall surface 54, and the sidewall surface 54 has an opening-side curved surface 55 on the opening end side and a back sidewall surface 56 on the outside of the mold. In each of these surfaces, the surface roughness is determined in the same manner as the first recess 30 of the above embodiment.

  Further, the surface roughness of the side wall surface 34 of the first recess 30 is different between the opening-side curved surface 35 which is a curved surface and the back side wall surface 36 which is a flat surface. And the back side wall surface 36, which is a flat surface, may not be a boundary between a portion having a small surface roughness and a portion having a large surface roughness. It is only necessary that the surface roughness of the opening end side portion of the side wall surface 34 is smaller than the surface roughness of the portion outside the mold, and the boundary between the small surface roughness portion and the large surface roughness portion is the opening side. It may be somewhere on the curved surface 35 or somewhere on the back side wall surface 36.

  Further, the side wall surface of the concave portion does not have to have the opening-side curved surface 35 that is a curved surface and the rear side wall surface 36 that is a flat surface, like the side wall surface 34 of the first concave portion 30 described above. The whole may be a single plane. Even in this case, the surface roughness differs between the portion on the opening end side of the side wall surface and the portion outside the mold, and the surface roughness of the portion on the opening end side of the side wall surface is the surface of the portion outside the mold on the side wall surface. It is smaller than the roughness. When rubber enters the recess, the rubber is first pressed in an oblique direction against the opening end side portion of the side wall surface. Here, since the surface roughness of the portion on the opening end side of the side wall surface is small, the pressed rubber is not easily caught on the side wall surface, and starts to proceed along the side wall surface with almost no resistance from the side wall surface. Next, the rubber progresses in parallel to the portion on the side of the recess on the side wall surface (outside the mold), but the surface roughness of the portion on the side of the recess on the side wall surface is large and the contact area with the rubber is small, so Proceed with almost no resistance. Therefore, rubber is filled up to the corners of the recesses.

  A pneumatic tire was vulcanized using the tire vulcanization molds of Comparative Examples 1 to 3 and Examples 1 to 3 shown in Table 1, and the presence or absence of a bear in the pneumatic tire after vulcanization was examined. .

  Each tire vulcanization mold was provided with a recess having a bottom surface and a side wall surface, similar to the first recess 30 described above. The side wall surface was composed of a curved surface (opening side curved surface) on the opening end side to the inside of the mold and a flat surface (back side wall surface) outside the mold (bottom surface side) from the opening side curved surface. Table 1 shows the surface roughness of the bottom surface, the opening-side curved surface, and the back side wall surface of each tire vulcanization mold. The surface roughness in Table 1 is the arithmetic average roughness Ra defined in JIS B 0601-2001, and the unit is μm.

  The results are as shown in Table 1. In Comparative Examples 1 to 3, bares were generated, whereas in Examples 1 to 3, bares were not generated. From this, when the surface roughness of the opening side curved surface was smaller than the surface roughness of the back side wall surface, it was confirmed that rubber was easily filled up to the corners of the recesses.

DESCRIPTION OF SYMBOLS 10 ... Tire vulcanization molding die, 12 ... Sector, 14 ... Side plate, 18 ... Molding surface, 20 ... Pneumatic tire, 20a ... Unvulcanized tire, 21 ... Grounding surface, 22 ... Side protector, 23 ... Outer surface , 24 ... raised surface, 26 ... rim protector, 27 ... top portion, 28 ... raised surface, 30 ... first recess, 31 ... open end, 32 ... bottom surface, 34 ... side wall surface, 35 ... open side curved surface, 36 ... back side Wall surface 40... Second recess 41. Opening end 42. Bottom portion 44. Side wall surface 45. Open-side curved surface 46. Back side wall surface 50. Recess side 52 52 Bottom surface 54 Side wall surface 55 Opening Side curved surface, 56 ... Back side wall surface

Claims (6)

In a tire vulcanization mold having a recess for forming a raised portion on the tire side portion,
The concave portion has a side wall surface extending from the opening end to the inside of the mold toward the outside of the mold,
A tire vulcanization mold in which a surface roughness of a portion of the side wall surface on the opening end side is smaller than a surface roughness of a portion outside the mold. The recess has a bottom surface;
The tire vulcanization according to claim 1, wherein a surface roughness of the bottom surface is larger than a surface roughness of a portion of the side wall surface on the opening end side and smaller than a surface roughness of a portion of the side wall surface outside the mold. Molding mold.   The tire vulcanization mold according to claim 1 or 2, wherein a portion of the side wall surface on the opening end side is a curved surface.   The tire vulcanization mold according to any one of claims 1 to 3, wherein the raised portion displays at least one of characters, symbols, and figures.   The tire vulcanization mold according to any one of claims 1 to 3, wherein the raised portion is a side protector.   A step of setting an unvulcanized tire inside the tire vulcanization molding die according to any one of claims 1 to 5 and applying vulcanization molding to the unvulcanized tire by heating and pressing. Including tire manufacturing method.

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