JPH0688253B2 - Tire mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a mold comprising a radially divisible segment, in which a knife blade for forming a narrow groove provided on a tire tread surface is provided close to the segment. Being able to be planted in such a way that the mold dividing position and the tire narrow groove arrangement position can be formed without being restricted in terms of dimensions, and the degree of freedom regarding the mold design and the tire design can be increased. A tire mold that can be improved.

[Conventional technology]

In order to improve grip and stabilize steering on the tread outer surface of the tire, for example, as shown in FIG. 8, a narrow groove S having a groove width of about 0.5 mm to 3 mm is arranged in a direction intersecting with the tire equator. Is often provided.

In order to form such a narrow groove S, for example, as shown in FIGS. 9 and 10, a thin plate-like knife blade a is planted on the inner peripheral surface c of a ring-shaped mold b, and The narrow groove was formed by using a mold together with vulcanization during tire vulcanization.

Further, the mold b is composed of a plurality of segments e ... Divided by a dividing surface d extending in the radial direction as shown in FIG. 10, and the base f of the knife blade a is embedded in each segment.

The fine grooves S ... Are arranged at equal intervals on the outer peripheral surface O of the tread, but the number thereof is preferably an odd number, preferably a prime number, in order not to induce secondary and tertiary vibrations in the tire.

[Problems to be Solved by the Invention]

Therefore, between the embedded portion of the knife blade a and the dividing surface d,
For example, in FIG. 1, as shown in the upper part of the drawing, the excess thickness A
It can happen that is extremely small. As a result, when a force in the inner peripheral surface direction acts on the knife plate a during vulcanization, the knife blade a often breaks at the rear end of the base portion f, and the mold is often damaged.

Further, in order to prevent such damage of the mold, a method of shifting a knife blade close to the dividing surface in a direction opposite to the dividing surface, a method of shifting the dividing surface of the mold to thicken a surplus thickness A, and the like are available. It is conceivable that the former has a risk that vibrations may occur during running and the appearance may be poor due to the uneven groove intervals in the molded tire. In the latter case, the segment of the die is unevenly divided, which complicates the production of the die, and exerts an uneven force on each segment during vulcanization, which makes the finished tire less accurate. descend. Therefore, the setting of the narrow groove is not only restricted by the tire function but also restricted by the structure of the mold, so that the degree of freedom in design has been extremely low.

The present invention is based on the provision of a blade portion extending in the opposite direction to the dividing surface to the implanting portion of the knife blade located in the vicinity of the dividing surface of the segment forming the die, which can prevent damage to the die, It is an object of the present invention to provide a tire mold in which the setting position of the narrow groove and the dividing position of the mold can be easily selected, the degree of freedom in design can be increased, and the appearance of the molded tire can be improved.

[Means for Solving the Problems]

The present invention, a knife blade for forming a fine groove on the outer peripheral surface of the tread of the tire is implanted in the inner peripheral surface, consisting of a plurality of segments divided by a dividing surface extending in a substantially radial direction, and The knife blade comprises a narrow groove forming portion protruding from the inner peripheral surface, and an implanting portion implanted in the inner peripheral surface, and at least the implanting portion of the knife plate located near the dividing surface is A tire mold comprising a base portion connected to the narrow groove forming portion and a blade portion integrally extending from the base portion in a direction away from the dividing surface.

[Action]

The knife blade is connected to the narrow groove forming portion that forms the narrow groove and has the implant portion that is implanted on the inner peripheral surface of the segment, so that the knife blade is securely fixed to the segment.

Further, in the knife blade located in the vicinity of the split surface, since the implant portion has a blade portion that is separated from the split surface from the base portion, both the base portion and the blade portion are planted in the knife blade. By further strengthening the fixing, damage can be prevented even if the gap between the slicing groove for planting the knife blade and the dividing surface provided in the mold is thin.

〔Example〕

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

1 to 5, the tire mold 1 of the present invention is a tire T
Is a mold for forming a plurality of narrow grooves S ... on the outer peripheral surface O of the tire mold 1, and the tire mold 1 is composed of a plurality of segments 3 divided by a dividing surface 2 extending in a substantially radial direction. A plurality of knife blades 5 are planted on the inner peripheral surface 4, and at least the knife blades 5A located in the vicinity of the dividing surface project from the inner peripheral surface 4 to form the narrow groove S. 6 and an implanting portion 7 that is planted on the inner peripheral surface 4, and further, in the implanting portion 7, a base portion 9 that continues to the narrow groove forming portion 6, and a wing portion 10 that extends from the base portion in a direction away from the dividing surface 2. It is equipped with

Further, the tire mold 1 has a wide ring shape having an inner peripheral surface 4 for forming a tread outer peripheral surface O of the tire T. Further, in this embodiment, as shown in FIG. 2, the tire T extends from both sides of the tire mold 1 toward the center in the tire radial direction, and the tire T
The mold tool W is formed together with the side mold U capable of forming the outer surface of the sidewall and the inner mold V made of an elastic body that can be formed by pressing the inner peripheral surface of the tire T from the inside.

As described above, the tire mold 1 is formed by a plurality of divided surfaces 2 ... Which extend in the radial direction, and in the present embodiment, a plurality of segments 3 ...

The segment 3 has a fan-shaped cross section in the circumferential direction, and a plurality of knife blades 5 ... Are attached to the inner peripheral surface 4 of the segment 3 at substantially equal pitches with the narrow groove forming portions 6 protruding from the inner peripheral surface 4. .

The knife blades 5 are composed of an outer knife blade 5A arranged near the dividing surface 2 and an intermediate knife blade 5B arranged at an intermediate position.

The outer knife blade 5A has a thin groove forming portion 6 protruding from the inner peripheral surface 4 and having a thickness of 0.5 mm to 4 mm, and the segment 3
The implant part 7 is embedded in the. Moreover, the implanting part 7 is
A flat plate-shaped base portion 9 which is continuous with the narrow groove forming portion 6, and two blade portions which extend from both side ends of the base portion 9 in a direction substantially perpendicular to the base portion 9.
It has a U-shaped cross section with 10 and 10. Knife blade in the middle
As shown in FIG. 9, 5B is formed only by the base portion 9 without providing the wing portion 10 on the implant portion 7, and has a flat plate shape as a whole.

As shown in FIG. 4, the inner circumferential surface 4 has a lateral groove portion 13 into which the base portion 9 of the implant portion 7 is fitted at a position close to the dividing surface 2.
And a vertical groove portion 14, 14 into which the wing portions 10, 10 are fitted, and a U-shaped bottomed outer implantation groove 15A directs the vertical groove portion 14 away from both ends of the horizontal groove portion 13 from the dividing surface. Is provided.

The lateral groove portion 13 and the base portion 9 are press-fitted in the thickness direction with a tight margin, and the vertical groove portion 14 and the blade portion 10 are also press-fitted with a tight margin so that the outer knife blade 5A Is
The narrow groove forming part 6 is projected from the inner peripheral surface 4 of the segment 3 and the implanting part 7 is implanted in the segment 3.

It should be noted that when implanting the implanting portion 7 into the implanting groove 15A, it is possible to perform strong press-fitting by hammering, and further, such as shrinkage fitting and cooling fitting, between the lateral groove portion 13 and the base portion 9 and between the vertical groove portion 14 and the blade portion 10.
It is fixed without rattling between and.

Therefore, even when the outer knife blade 5A is implanted in the vicinity of the dividing surface 2, in addition to the lateral groove portion 13 gripping the base portion 9, the vertical groove portion 14 grips the wing portion 10. become. Therefore, as a result of the knife blade 5A being firmly and reliably fixed, even if bending is applied to the segment 3 due to the circumferential force being applied to the narrow groove molding portion 6 during tire molding, The bending stress generated in the surplus portion A between the lateral groove portion 13 and the dividing surface is small, and the surplus portion A can be prevented from being damaged.

The intermediate knife blade 5B is press-fitted and implanted into the intermediate implantation groove 15B formed only by the lateral groove portion 13.

In the knife blade 5B in the middle, the implantation pitch interval P is at least 2 as compared with the thinnest portion of the extra thickness portion A.
Since it exceeds twice, there is no risk of the knife blade 5 being damaged even if the blade 10 is not provided.

Therefore, the number of the narrow grooves S and the number of divided dies do not take into consideration the surplus portion A, and even if both the number of the narrow grooves S and the number of divided dies are prime numbers, they can be freely set. It becomes possible to set.

In addition, in the present invention, as shown in FIG.
The wing portion 10 may be extended from the intermediate position of the base portion 9 in the direction away from the split surface, and as shown in FIG.
May be formed by bending deeply into a small angle of more than 90 in the direction facing each other. Further, even in the intermediate knife blade 5B, a blade portion can be provided similarly to the outer knife blade 5A, and the present invention can be modified into various aspects.

〔The invention's effect〕

As described above, in the tire mold of the present invention, since the implanting portion of the knife blade located at least in the vicinity of the dividing surface includes the blade portion that is separated from the dividing surface from the base portion, there is a margin between the dividing surface and the implanting portion. Even if there is little meat, segment damage can be prevented, fine grooves can be formed at equal intervals on the tread outer peripheral surface of the tire to stabilize running performance and improve its appearance, while the mold can be divided evenly. Therefore, the degree of freedom in design can be increased and the quality can be stabilized.

[Brief description of drawings]

FIG. 1 is a radial sectional view showing an embodiment of the present invention, FIG. 2 is an axial sectional view thereof, FIG. 3 is a circumferential sectional view showing a part of a segment in an enlarged scale, and FIG. Perspective view, FIG. 5 is a perspective view showing an outer knife blade, FIGS. 6 and 7 are circumferential sectional views showing other examples of segments, and FIG. 8 is a tire formed using the mold of the present invention. Fig. 9 is a perspective view showing a tread of Fig. 9, Fig. 9 is a perspective view showing an intermediate knife blade and a conventional knife blade, and Fig. 10 is a sectional view showing a segment of a conventional mold. 2 ... Dividing surface, 3 ... Segment, 4 ... Inner peripheral surface, 5, 5A, 5B ... Knife blade, 6 ... Fine groove forming part, 7 ... Implanting part, 9 ... Base part, 10 ... Wing, O ... Tread outer surface, S ... Fine groove, Y ... Tire.

Claims (1)

[Claims] 1. A knife blade for forming fine grooves on the outer peripheral surface of a tread of a tire is planted on the inner peripheral surface, and
The knife blade is composed of a plurality of segments divided by a dividing surface extending in a substantially radial direction, and the knife blade includes a narrow groove forming portion protruding from the inner peripheral surface and an implanting portion implanted in the inner peripheral surface. In addition, at least the implanting portion of the knife blade located in the vicinity of the dividing surface includes a base portion connected to the narrow groove forming portion and a blade portion integrally extending from the base portion in a direction away from the dividing surface. Type.