JPH03189112A - Mold for molding tire - Google Patents

Abstract

PURPOSE:To attempt both to improve traveling characteristics on ice- and snow-converted road and to improve resistance to shifted wearing of the surface of a tread by providing a specified relation between the thickness at the free end of a bone for molding of a sipe and the thickness from the molding surface of a tire to the free end. CONSTITUTION:In a mold M for molding of a tire having a bone 3 for molding a sipe on the molding face of the tire, when the thickness of at the free end 5 of the bone 3 for molding the sipe is T and the thickness of the main part in a resion from the molding face 1 of the tire to the free end 5 is t, these thicknesses T and t satisfy equations (1)-(3). 0.6<=mm T (1); 0.1 mm<=t<=0.8 mm (2); t<T (3). When a tire is molded by using such a mold as this, as a sipe with a narrower gap is formed on the surface of a tread, it is possible to improve traveling characteristics on an ice- and snow-covered road of the tire and furthermore, it is possible to improve resistance against shifted wearing of the surface of the tread.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a tire with narrow sipes (sipes) on the tread surface of a tire.
This invention relates to a tire molding mold that can form thin cuts.

[Conventional technology]

BACKGROUND ART Conventionally, in pneumatic tires for driving on icy and snowy roads provided with a block pattern, sipes are provided on the surface of the blocks in order to improve the performance on icy and snowy roads. In general, the narrower the gap between the sipes, the better for improving driving performance on icy and snowy roads.

This sipe is formed, for example, by molding the tire with a mold having a sipe molding rib (kerf) on the tire molding surface. Figure 11 (A).

(B) shows an example of this mold. FIG. 11(A) is an explanatory cross-sectional view of the main part of the mold M in a direction corresponding to the tire meridian direction, and FIG. 11(B) is a cross-sectional view of the main part of the mold M in a direction corresponding to the tire circumferential direction. It is a diagram. In FIG. 11(A), the tire molding surface (inner surface of the mold) 1 of the mold M is provided with a protruding leading molding rib 2 for forming a main groove extending in the circumferential direction of the tire on the tread surface of the tire. It is being As can be seen from FIG. 11(B), a plate-shaped sipe forming bone 3 having a predetermined thickness is provided protrudingly between the main forming bones 2. , reference numeral 4 denotes a sub-groove forming bone for forming a sub-groove extending in the width direction of the tire on the tread surface of the tire.

FIG. 12(A) shows the trend part of the tire molded using the mold shown in FIGS. 11(A) and 11(B).

(B) and (C), FIG. 12 (A) is a cross-sectional explanatory diagram of the main part of the trend part in the tire meridian direction, FIG. 12 (B) is a cross-sectional explanatory diagram of the main part of the tread part in the tire circumferential direction, and FIG. Figure (C
) is a plan view explanatory diagram of main parts when the tread surface is viewed in the circumferential direction. In these figures, a tread surface 10 is formed with a main groove 2a extending in the tire circumferential direction corresponding to the main groove forming rib 2, and a sub groove extending in the tire width direction corresponding to the minor groove forming bone 4. Grooves 4a are formed, and these main grooves 2a
The block 11 is divided by the sub-groove 4a. Further, on the tread surface 10, FIG. 12(B),
As shown in (C), sipes 3a are formed corresponding to the sipe-forming bones 3.

However, with such a conventional mold, the size forming bone 3 cannot be made very thin due to strength problems. For this reason, there is a problem in that even if the gap between the molded sipes 3a is made narrower to improve driving performance on icy and snowy roads, there is a limit.

[Problem to be solved by the invention]

The present invention has been made in view of these circumstances, and an object of the present invention is to provide a tire molding die that can form sipes with even narrower gaps on the tread surface of a tire and improve running performance on icy and snowy roads. shall be.

[Means to solve the problem]

The present invention provides a tire molding die having a sipe molding bone on a tire molding surface, wherein the thickness of the free end of the size molding bone is T, and the main part of the area from the tire molding surface to the free end is T. It is characterized in that these thicknesses T and t satisfy the following formulas (1) to (3), where the thickness of the part is t.

0.6 vw≦T・ ・ ・ ・ ・ ・ ・ ・(
1) 0.1 mm5 t SO, 8 between both sides
・ ・ ・ (2) t<T ・ ・ ・ ・ ・ ・
・ ・ ・ ・ (3) When a tire is molded using such a mold, sipes with narrower gaps are formed on the tread surface, which improves the tire's running performance on icy and snowy roads. Furthermore, it becomes possible to improve the uneven wear resistance of the tread surface.

Hereinafter, the above means will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory cross-sectional view of a main part of an example of a tire molding die of the present invention in a direction corresponding to the tire meridian direction, and FIG. 2 is a cross-sectional explanatory view of a main part thereof in a direction corresponding to the tire circumferential direction.

As can be seen from these figures, as well as FIG. 3 showing the cross section taken along the line A-A in FIG. 1, and FIG. 4 showing the cross section taken along the B-B line in FIG. Compared to the conventional molds shown in (A) and (B), the thickness T of the free end 5 of the sipe molding rib 3 is compared to the thickness t from the tire molding surface 1 to the free end 5. (1<T). By increasing the thickness T in this way, the part that bites the green (the tip of the sipe forming bone 3 inserted into the green tire), which is subjected to the most force during tire vulcanization, Because the rigidity is greater than other parts,
It is possible to prevent the sipe molding rib 3 from being bent during tire vulcanization.

The thickness T of this free end 5 must be 0.6IllII≦T, because if it is thinner than this, the sipe forming rib 3 will be bent during tire vulcanization.

The thickness T should be as thick as possible, but if it is too thick, the sipe molding rib 3 will not be able to be extracted from the tire after the tire is vulcanized, so it should be set in consideration of the elasticity of the tire after vulcanization. It is best to adjust the thickness accordingly.

In addition, the thickness t of the main part of the region from the tire molding surface 1 to the free end 5 must be within the range of 0.1 mm to 0.8I1ml (0.1am≦t≦0.8 mex).
If the thickness is less than 0.1 wa, it becomes too thin, and the sipe-forming rib 3 may be bent or damaged during tire vulcanization. 0.8 m
This is because if it exceeds m, it becomes too thick and it becomes impossible to form sipes with narrow gaps on the tire tread surface.

As an example of the sipe molding bone 3, the thickness T of the free end 5 is the same as that of the sipe molding bone in a conventional mold, and the thickness t of the main part of the region from the tire molding surface 1 to the free end 5.
It is better to make it thinner than that.

The length from the tire molding surface l to the tip of the free end 5 and the length l from the tire molding surface 1 to the free end 5 may be appropriately selected and are not particularly limited.

Next, another specific example of the tire molding mold of the present invention will be shown.

As shown in FIGS. 5(A) and 5(B), the sipe forming bone 3
An inflatable portion 5a having the same thickness T as the free end 5 may be provided at at least one location between the tire molding surface 1 and the free end 5. Thereby, the rigidity of the sipe-forming bone 3 can be further increased. From the tire molding surface 1 to the inflation section 5
The length 11 to a, the length IRl of the expansion part 5a, and the length l from the expansion part 5a to the free end 5 may be selected as appropriate. As shown, in addition to the free end 5 of the sipe-forming bone 3, expansion portions 5a having the same thickness T may be provided on both sides thereof.

As shown in FIGS. 7(A), (B), and (C), in addition to the free end 5 of the sipe-forming bone 3, an expanded portion 5a having the same thickness T may be provided on one side thereof.

As shown in FIGS. 8(A), (B), and (C), in addition to the free end 5 of the sipe-forming bone 3, an expanded portion 5a having the same thickness T is provided around the sipe-forming bone 3. You can.

As shown in FIGS. 9(A), (B), and (C), the sipe forming bone 3 is placed between the leading forming bones 2 with a gap on one side, and in addition to the free end 5, the sipe forming bone 3 is placed on the side of the gap. An expanded portion 5a having the same thickness T may be provided on the side of the sipe molding bone 3.

As shown in FIGS. 10(A), (B), and (C), the sipe forming bones 3 are placed between the leading forming bones 2 with gaps on both sides, and in addition to the free end 5, the sipe forming bones 3 are placed between the leading forming bones 2 with gaps on both sides. Expanded portions 5a having the same thickness T may be provided on both sides of the bone 3.

Examples are shown below.

Example The following conventional tires A and B and tires C and D of the present invention of tire size 10.00 R2014PR were evaluated for braking performance, uneven wear resistance, and bending of the bone for forming sipes (hereinafter referred to as kerf bending). did. The results are shown in Table 1.

■ Conventional tire A0 Tire e manufactured using the mold shown in Fig. 11 (A) and (B)
12 = L = 12 arm, t = T = 1.0
m1m5■ Conventional tire B.

Tires manufactured using the molds shown in FIGS. 11(A) and (B), ff1-L=12 am, t=T=0.
5 1111゜■ Tire of the present invention C0 Tire manufactured using the mold shown in Fig. 1, L-12++v+
, l −9vw s T=1.0 mm, t
-0.5 mm.

■ Inventive tire D.

Tire e manufactured using the mold shown in Fig. 5 (A) and (B)
L=12 saw %11-4mta, l, =2
11@I,j! 1-3 +sg, , T=1.2
smS t =0.6 sn.

■Study blood■ Tomohiro Biichi: Installing each tire on all wheels of a large car, initial speed of 40 on a compressed snow road
Apply the brakes from km/h, evaluate based on the braking distance, and express the results as an index; the larger the number, the better.

：Equip each tire on all wheels of a large vehicle, run it on a paved road for 10,000 times, evaluate it based on the amount of heel and toe difference, and express the result as an index. The higher the number, the better.

Curfing: Vulcanize 20 tires each using each mold,
The subsequent curve bending was evaluated by the number of curves that were distorted by 11 or more; the smaller the number, the better.

As is clear from Table 1, the mold of the present invention does not cause kerf bending even when the thickness t is reduced. In addition, tires manufactured using the mold of the present invention (tires of the present invention C and D
) is found to have excellent braking performance and wear resistance on compacted snow roads.

〔Effect of the invention〕

As explained above, according to the present invention, in a mold having a sipe molding bone on the tire molding surface, the thickness T of the free end of the sipe molding bone and the thickness t from the tire molding surface to the free end. Having a predetermined relationship between the two makes it possible to form sipes with narrower gaps on the trend surface during tire manufacturing. Furthermore, since the resulting tire has narrow gaps between the sipes, it is possible to improve running performance on icy and snowy roads, and it is also possible to improve uneven wear resistance of the tread surface.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view of a main part of an example of a tire molding mold of the present invention in a direction corresponding to the tire meridian direction, FIG. 2 is a cross-sectional explanatory view of a main part in a direction corresponding to the tire circumferential direction, The figure is a cross-sectional view taken along the line A--A in FIG. 1, and FIG. 4 is a cross-sectional view taken along the line B--B in FIG. 5 to 10 respectively show separate tire molding molds of the present invention, and FIG. B) is a cross-sectional view taken along the line A-A in FIG. 5(A), FIG. 6(A) is a cross-sectional explanatory diagram of a main part in a direction corresponding to the tire meridian direction, and FIG. 6(B)
6(A) is a section taken along line AA in FIG. 6(A), FIG. 6(C) is a section taken along line BB in FIG. 6(A), and FIG. 7(A) is a main point in the direction corresponding to the tire meridian direction. 7(B) is a cross-sectional view taken along the line A-A of FIG. 7(A), and FIG. 7(C) is a cross-sectional view of FIG. 7(A).
), FIG. 8(A) is a cross-sectional explanatory diagram of the main part in a direction corresponding to the tire meridian direction, and FIG. 8(B) is a cross-sectional view taken along A-A of FIG. 8(A), 8(C) is a cross-sectional view taken along the line B-B of FIG. 8(A), FIG. 9(A) is an explanatory cross-sectional view of a main part in a direction corresponding to the tire meridian direction, and FIG. 9CB) is a cross-sectional view of FIG. 9(A). A
), Figure 9(C) is the cross section of Figure 9(A) along line A-A.
B-line cross section, FIG. 10(A) is an explanatory diagram of a main part cross-sectional view in a direction corresponding to the tire meridian direction, FIG. 10(B) is a cross-sectional view of FIG.
A) A-A cross section, Figure 10<C) is Figure 1O (A)
This is a cross section taken along line B-B. FIG. 11(A) is an explanatory cross-sectional view of a main part of an example of a conventional tire molding mold in a direction corresponding to the tire meridian direction;
Figure (B) is an explanatory cross-sectional view of the main part in the direction corresponding to the tire circumferential direction, Figure 12 (A) is an explanatory cross-sectional view of the main part of the tread in the tire meridian direction, and Figure 12 (B) is an explanatory view of the main part of the tread in the tire meridian direction. FIG. 12(C) is a cross-sectional explanatory view of the main part of the tread portion, and is a plan view explanatory view of the main part when the tread surface is viewed in the circumferential direction. 1... Tire molding surface, 2... Main molding bone, 3...
- Bone for forming sipe, 4... Bone for forming minor groove, 5... Free end, 2a... Main groove, 3a... Sipe.

Claims (1)

[Claims] A mold having a sipe molding bone on a tire molding surface,
When the thickness of the free end of the sipe molding bone is T and the thickness of the main part of the region from the tire molding surface to the free end is t, these thicknesses T and t can be calculated using the following formula (1 )～(
A tire molding die characterized by satisfying 3). 0.6mm≦T・・・・・・・・・(1) 0.1mm≦t≦0.8mm・・・(2) t<T・・・・・・・・・(3)