JP2008195136A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire in which trouble with the vulcanization of an emblem formed on the outer surface of a side wall part is improved. <P>SOLUTION: This pneumatic tire has the emblem 8 on the outer surface 2A of the side wall part 2. The emblem 8 comprises an emblem body 9 projecting from the outer surface 2 of the side wall part 2 and an outline part 10 projecting along the peripheral edge of the emblem body 9. The surface 9x of the emblem body 9 surrounded by the profile part 10 is so recessed in the direction separating from the profile part 10 inward that the height of the side wall part 2 from the outer surface 2A is gradually reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire in which marks such as letters, numbers, symbols, and figures are provided on the outer surface of a sidewall portion, and more particularly, a pneumatic tire that improves a vulcanization failure of a mark. About.

  Generally, marks such as letters, numbers, symbols and figures are engraved on the outer surface of the sidewall portion of the pneumatic tire. In order to improve the visibility of the mark, as shown in FIG. 12, the mark 21 protrudes from the outer surface 23 of the sidewall portion 22, and the contour portion 24 protrudes along the peripheral edge portion. Those are known (for example, see Patent Document 1).

In this way, a pneumatic tire provided with the mark 21 with the contour portion 24 protruding and bordered, particularly a heavy duty pneumatic tire used for trucks and buses, and a small truck air used for light trucks and the like. In tires and the like, groove-like streaks (vulcanization failure) due to poor rubber flow often occur on the surface 25 of the mark 21 surrounded by the contour portion 24 after vulcanization, and countermeasures have been strongly demanded.
JP-A-10-67208

  The objective of this invention is providing the pneumatic tire which can improve the vulcanization failure of the mark provided in the outer surface of a side wall part.

  The pneumatic tire of the present invention that achieves the above object is provided with a mark on the outer surface of the sidewall portion, the mark body protruding from the outer surface of the sidewall portion, and the periphery of the mark body In a pneumatic tire constituted by a contour portion protruding along a portion, the outer surface of the sidewall portion is directed in a direction in which the surface of the mark body surrounded by the contour portion is spaced inward from the contour portion. It is characterized by being recessed so that the height from is gradually lowered.

  According to the above-described present invention, the concave bottom surface of the mold for molding the mark is protruded outward from the conventional state by denting the surface of the main body of the mark as described above, so that it flows into the concave portion of the mold. It is possible to vulcanize the rubber while pressing the rubber against the bottom of the recess. Therefore, it is possible to suppress the occurrence of streak-like vulcanization failure on the surface of the mark body and to improve the vulcanization failure of the mark.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a tire meridian half sectional view of an embodiment of a pneumatic tire of the present invention, wherein 1 is a tread portion, 2 is a sidewall portion, 3 is a bead portion, and CL is a tire equatorial plane. Since the structure is symmetrical with respect to the tire equatorial plane CL, the left portion is omitted.

  Between the left and right bead portions 3 inside the tire, a carcass layer 4 in which reinforcing cords such as steel cords extending in the tire radial direction are arranged at predetermined intervals in the tire circumferential direction and embedded in the rubber layer is extended, Both end portions 4a are folded back from the inside of the tire to the outside so as to sandwich the bead filler 6 around the bead core 5 embedded in the bead portion 3. On the outer peripheral side of the carcass layer 4 of the tread portion 1, a plurality of belt layers 7 in which steel cords are inclined and embedded in a rubber layer are arranged.

  On the outer surface 2A of the left and right sidewall portions 2, a plurality of marks 8 made of letters, numbers, symbols, figures and the like are provided at predetermined intervals in the tire circumferential direction. As shown in FIGS. 2 to 4, the mark 8 made of rubber integrally formed with the sidewall portion 2 includes a mark body 9 protruding from the outer surface 2 </ b> A of the sidewall portion 2, and the mark body 9. It is comprised from the outline part 10 protrudingly provided over the perimeter along the peripheral part. The illustrated mark 8 indicates a circle of a figure.

  The mark main body 9 of the mark 8 has a sidewall portion extending over the entire area from the boundary position x with the contour portion 10 to the center portion 9b in a direction in which the surface 9x is inwardly spaced from the boundary portion x. 2 is recessed so that the height from the outer surface 2A gradually decreases. In the illustrated example, in the cross-sectional shape (FIGS. 3 and 4) cut in the protruding direction of the mark 8, an example in which the recessed surface 9x is constituted by a straight line is shown. It may be a curve or a combination thereof. The contour portion 10 that borders the mark 8 is formed in a rectangular cross section, and includes a top surface 10a having a surface (including a flat surface) substantially parallel to the outer surface 2a of the sidewall portion 2.

  As another example of the mark 8, a mark 8 composed of the alphabet M is shown in FIGS. Similarly to the above, the mark main body 9 of the mark 8 has a surface 9x surrounded by the contour portion 10 in the entire region from the boundary position x with the contour portion 10 toward the center portion 9b in the direction away from the inside. It is dented so that the height from the outer surface 2A of the sidewall portion 2 gradually decreases. The mark 8 is a cross-sectional shape cut in the protruding direction (FIGS. 6 and 7), and the recessed surface 9x is formed by an arc-shaped curve. Also good. The contour portion 10 for edging the mark 8 is formed in a rectangular cross section like the above, and includes a top surface 10a having a surface (including a plane) substantially parallel to the outer surface 2a of the sidewall portion 2. ing.

  As still another example of the mark 8, an example of the mark 8 composed of the numeral 8 is shown in FIGS. The mark 8 is provided with contour portions 10 (an outer contour portion 10o and an inner contour portion 10i) projecting along the outer peripheral edge portion and the inner peripheral edge portion of the mark main body 9. The surface 9x of the mark body 9 surrounded by the outer contour portion 10o and the inner contour portion 10i reaches the central portion 9b facing in the direction away from the boundary position x (xo, xi) between the contour portions 10o and 10i. In the entire region, the sidewall portion 2 is recessed so that the height from the outer surface 2A gradually decreases. In the mark 8, in the cross-sectional shape (FIGS. 9 and 10) cut in the protruding direction, the recessed surface 9 x is configured by an arcuate curve, but is a straight line or a combination thereof as described above. Also good. Both the contour portions 10o and 10i for bordering the mark 8 are formed in a rectangular cross section like the above, and have a top surface (including a plane) substantially parallel to the outer surface 2a of the sidewall portion 2. 10a.

  Generally, a pneumatic tire is vulcanized in a state where it is pressed from the inside by a bladder and pressed against the inner surface of a mold in a vulcanization process. At that time, in the conventional mark 21 shown in FIG. 11, the rubber that has flowed into the recess of the mold for molding the mark 21 is sufficiently pressed against the bottom of the recess of the mold for molding the surface 26 of the mark body 25. It was found that a groove-like streak (vulcanization failure) occurred because it was vulcanized in the absence. Usually, a vent hole for venting air is formed in the contour molding groove formed around the bottom surface of the recess, which is a deeper position in the mold, and rubber is formed in the contour molding groove where the vent hole is formed. This is presumably because part of the rubber forming the surface 26 portion of the mark 21 is drawn into the contour forming groove when.

  Therefore, in the present invention, as described above, the surface 9x of the mark main body 9 is recessed so that the height from the outer surface 2A of the sidewall portion 2 gradually decreases in the direction away from the contour portion 10 inward. I did it. As a result, the bottom surface of the concave portion of the mold for molding the mark 8 protrudes to the outside, so that part of the rubber forming the surface 9x portion of the mark body 9 is drawn into the contour molding groove. Even in such a case, it is possible to vulcanize the rubber flowing into the concave portion of the mold while being pressed against the bottom surface of the concave portion. Therefore, the occurrence of groove-like streaks (vulcanization failure) on the surface 9x of the mark body 9 after vulcanization is suppressed, and the vulcanization failure of the mark 8 can be improved.

  As shown in FIG. 11, when one of the contour portions 10 side of the surface 9x is not deepened so as to be deepest, rather than the central portion of the surface 9x, a vulcanization failure occurs at the portion of the one contour portion 10 adjacent thereto. Further, it becomes difficult for rubber to flow into the contour portion forming groove, and accordingly, vulcanization failure such as chipping is likely to occur in the contour portion 10.

  In the present invention, the height at the center portion 9b of the surface 9x of the mark body 9, that is, the height at the bottom of the depression (the height at the lowest position) h and the contour portion from the outer surface 2A of the sidewall portion 2 The ratio h / H to the height H of 10 is preferably in the range of 0.4 to 0.7. If the ratio h / H is smaller than 0.4, that is, if the surface 9x is excessively depressed, it becomes difficult for the rubber to flow into the contour portion forming groove for forming the contour portion 10, which causes a vulcanization failure. If the ratio h / H is higher than 0.7, that is, if the depression of the surface 9x is too small, groove-like streaks (vulcanization failure) are likely to occur on the surface 9x of the mark body 9 after vulcanization.

  The height hx at the boundary position x of the mark body 9 is about 0.4 mm to 2.5 mm, and the protrusion height Hp of the contour portion 10 from the surface 9x (boundary position x) of the mark body 9 is as follows. The height H of the contour portion 10 can be about 0.5 mm to 3.0 mm, and can be appropriately selected depending on the size and type of the tire.

  The present invention can be preferably used for heavy-duty pneumatic tires used for trucks and buses, and small truck pneumatic tires used for light trucks, but is not limited thereto. It may be a pneumatic tire.

  Tires of the present invention 1 to 4 (Examples 1 to 4) and tires having a tire size of 275 / 70R22.5, a tire structure common to those in FIG. 1, and a ratio h / H as shown in Table 1 are shown in FIG. Comparison tire (comparative example) with a mark with the surface of the chapter body recessed so that one contour side is deepest, and a conventional tire (conventional example) without the surface of the mark body being normal 50 were produced by the production method described above.

  In each manufactured tire, the height H of the contour portion from the outer surface of the sidewall portion is 1.0 mm, and the protrusion height Hp of the contour portion from the surface of the mark body is 0.2 mm.

  The mark of each tire after manufacture was visually observed and the rate of occurrence of vulcanization failure in the mark was examined. The results shown in Table 1 were obtained. In Table 1, ○ indicates a vulcanization failure rate of less than 1%, △ indicates a vulcanization failure rate of 1% to less than 3%, and X indicates a vulcanization failure rate of 3% or more. .

  From Table 1, it can be seen that the tire of the present invention can improve the vulcanization failure of the mark.

It is a tire meridian half section view showing one embodiment of a pneumatic tire of the present invention. It is the enlarged view of the mark seen from the tire side. It is R1-R1 arrow sectional drawing of FIG. It is R2-R2 arrow sectional drawing of FIG. It is an enlarged view which shows the other example of a mark. It is R3-R3 arrow sectional drawing of FIG. It is R4-R4 arrow sectional drawing of FIG. It is an enlarged view which shows the other example of a mark. It is R5-R5 arrow sectional drawing of FIG. It is R6-R6 arrow sectional drawing of FIG. It is sectional drawing of the mark which hollowed one outline part side. It is sectional drawing of the conventional mark.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 2A Outer surface 3 Bead part 8 Mark 9 Mark main body 9b Center part 9x Surface 10 Outline part 10a Top surface 10o Outer outline part 10i Inner outline part x, xi, xo Boundary position

Claims (6)

A mark is provided on the outer surface of the sidewall portion, and the mark is composed of a mark body protruding from the outer surface of the sidewall portion, and a contour portion protruding along the peripheral edge of the mark body. In pneumatic tires,
A pneumatic tire in which the surface of the main body of the mark surrounded by the contour portion is recessed such that the height from the outer surface of the sidewall portion gradually decreases toward the inside away from the contour portion.   The pneumatic tire according to claim 1, wherein the surface of the main body of the mark is recessed from the boundary position x with the contour portion to the center portion so that the height from the outer surface of the sidewall portion gradually decreases.   The ratio h / H between the height h at the bottom of the depression on the surface of the mark body and the height H of the contour portion from the outer surface of the sidewall portion is 0.4 to 0.7. Or the pneumatic tire of 2.   The pneumatic tire according to claim 3, wherein the height H is 0.5 mm to 3.0 mm.   The pneumatic tire according to any one of claims 1 to 4, wherein a protruding height Hp of the contour portion from the surface of the mark main body is 0.1 mm to 1.0 mm.   The pneumatic tire according to claim 1, wherein the contour portion has a top surface substantially parallel to an outer surface of the sidewall portion.

Images