KR100484412B1 - The Building Drum for Heavy Duty Pneumatic Radial Tire - Google Patents

Abstract

The present invention relates to a forming drum of a pneumatic radial tire for heavy load,

The shoulder part 7 profile of the forming drum has four rounding parts R1, R2, R3, and R4 formed in a continuous shape.

The diameter D of the forming drum 6, the vertical height H of the shoulder portion 7, and the horizontal distance W of the shoulder portion 7 are 0.075D ≦ H ≦ 0.095D, 0.81H ≦ W Made in a relationship of ≤0.91H, and on a vertical extension line connecting the lower end point V and the upper end point N of the vertical line R3, the vertical distance A from V to N, and V to N The vertical distance (B) between the point (Q) and N located, the intersection (U) between the vertical extension line connecting N at V and the upper horizontal line (X) of the forming drum (6) and Q , 0.20H ≤ A ≤ 0.30H, 0.27H ≤ B ≤ 0.37H, 0.21H ≤ C ≤ 0.31H, where R1 is defined to pass through Q while in contact with X, and R2 is in contact with R1 at N Since it is in contact with the vertical line R3, R4 is in contact with R3, passing through V and in contact with the horizontal line (Z), characterized in that 20mm ≤ R2 ≤ 40mm, 8mm ≤ R3 ≤ 10mm,

Since the wave phenomenon of the rim flange component and the folding of the nylon chaper can be prevented, the durability of the tire bead portion can be greatly improved.

Description

Building drum for heavy duty pneumatic radial tires

The present invention relates to a forming drum for heavy-load pneumatic radial tires, and more particularly to a forming drum for heavy-load pneumatic radial tires that can improve the durability of the tire bead portion.

The molding process of the tire refers to a step of forming each semi-finished product by assembling and attaching each other to the green tire for vulcanization. The assembly attachment is usually made in the forming drum, the profile of the shoulder part (outer shape) is shown in FIG. As shown, the profile of the conventional forming drum 6 has a shape in which the shoulder portion 7 is sharply bent. In addition, the part where the turn-up starts is rapidly rounded.

As such, since the forming drum shoulder portion 7 is sharply bent, when the semifinished product including the bead portion is assembled in the forming drum as shown in FIG. 2, the turn-up end point 8 of the carcass 4 is assembled. ) Is also formed in a bent form. When vulcanization is made after the green case is made in a bent state, as shown in FIG. 3, folding occurs in the nylon chafer 5 and waving occurs in the rim flange component 2.

When traveling with the defective tires, repeated flexural movement and radiant heat transmitted from the brake drum are concentrated on the bead part, in particular the folding part of the nylon chafer and the wave generating part of the rim flange component. (flow crack) and bead separation were often linked. This means that it may lead to a safety accident while driving, and efforts have been made to prevent this.

Conventionally, edge strips 9 have been inserted at the turn-up end points 8 of the carcass 4 in order to prevent such folding of the nylon chafer 5 and the weaving of the rim flange components 2. However, in this case, there is a problem that the molding time, which is a process of making the green case of the tire, is increased and productivity is lowered.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a forming drum of a heavy-load pneumatic radial tire that can improve the durability of the bead portion by specifying a shoulder portion profile.

In order to achieve the above object, the shoulder portion profile of the forming drum according to the present invention has four rounded portions (R1) (R2) (R3) (R4) is formed in a continuous shape,

The diameter (D) of the forming drum, the vertical height (H) of the shoulder portion 7, the horizontal distance (W) of the shoulder portion,

0.075D ≤H ≤0.095D

0.81H ≤W ≤0.91H

Made of a relationship

Lower point (V) and upper point (N) of the vertical line (R3), H, between the vertical distance (A) from V to N, between the point (Q) and N located on the vertical extension line connecting N in V The vertical distance (B) of, the distance (C) between the intersection point (U) and Q of the vertical extension line connecting V to N and the upper horizontal line (X) of the forming drum,

0.20H ≤A ≤0.30H

0.27H ≤B ≤0.37H

0.21H ≤C ≤0.31H

Is made of

R1 is defined to pass through Q while in contact with X, R2 is in contact with R1 which is perpendicular to N while in contact with R1, and R4 is in contact with R3 through V and in contact with the horizontal line (Z), 20 mm ≤ R2 ≤ 40 mm, 8 mm ≤ R3 ≤ 10 mm.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

Figure 4 shows the configuration of the profile of the forming drum according to the invention, Figure 5 shows a configuration in which the semi-finished product including the tire bead portion in the forming drum of Figure 4 is assembled.

As shown, in the shoulder portion 7 profile of the forming drum 6 according to the invention, four rounding portions R1, R2, R3 and R4 are formed continuously. Among these, R3 has a vertical line shape. Therefore, there is no sudden bending shape in the shoulder part 7. More specifically, the configuration of the profile is as follows.

First, the diameter (D) of the forming drum (6), the vertical height (H) of the forming drum shoulder portion 7, the horizontal distance (W) of the forming drum shoulder portion 7 must satisfy the following formula (1).

0.075D ≤H ≤0.095D

0.81H ≤W ≤0.91H ... (Equation 1)

Here, when H is less than 0.075D, the vertical height of the forming drum shoulder portion 7 becomes too low, thereby deteriorating the effect of the webbing of the rim flange component 2 and the folding of the nylon chafer 5. On the other hand, when H exceeds 0.095D, withdrawal of the green case from the forming drum 6 becomes difficult. Most preferred is the case when H = 0.083D.

When W is less than 0.81H, it is difficult to sufficiently expect the rounding effect of the forming drum shoulder portion 7. When W is larger than 0.91H, the shoulder portion may show a bent shape, and various defects as in the prior art are generated. Done. The most preferable value is about W = 0.86H.

Moreover, it is necessary to satisfy the relationship of following formula (2).

0.20H ≤A ≤0.30H

0.27H ≤B ≤0.37H

0.21H ≤C ≤0.31H ... (Equation 2)

here,

V: lower point of vertical line R3

N: upper point of vertical line R3

H: vertical height of the shoulder portion 7

A: vertical distance from V to N

Q: Point located on the vertical extension line connecting V to N

B: vertical distance between Q and N

X: upper horizontal line of the forming drum (6)

U: intersection of X with vertical extension line connecting V to N

C: distance between U and Q

Respectively.

At this time, when A is less than 0.20H, a bending occurs in the rim flange component 2 and the nylon chaper 5 at the shoulder portion 7 of the forming drum 6, and when A exceeds 0.30H, The vertical height of the shaping drum shoulder portion 7 becomes too high to bend the portion in contact with the rounding portions R1 and R2, which is undesirable. Also, a value of A = 0.25H is most suitable.

In addition, when B is less than 0.27H, the rounding range of the forming drum shoulder portion 7 becomes too large, which is not preferable. When the B exceeds 0.37H, the vertical height A of the forming drum shoulder portion 7 is exceeded. Is relatively small, which is undesirable. Most preferred is B = 0.32H.

Moreover, when C is less than 0.21H, the rounding range of the shaping | molding drum shoulder part 7 becomes too large, and it is not preferable, and when it exceeds 0.31H, the rounding range of the shoulder part 7 becomes too small, and it is unpreferable. C = 0.26H is the most preferred value.

On the other hand, as mentioned above, the shoulder part 7 profile consists of rounding parts R1, R2, R3, and R4. R1 is a rounding part that passes through Q while contacting X at the point P at which the shoulder portion 7 of the forming drum 6 starts, R2 is a rounding part that contacts R3 which is perpendicular to N at R1 while contacting R1, and R3 Is a vertical line connecting N to V, and R4 is a rounding part that passes through V and contacts the horizontal line Z while being in contact with R3.

At this time, it is good to form such that 20mm ≦ R2 ≦ 40mm and 8mm ≦ R3 ≦ 10mm.

This is because the rounding range becomes excessively small when R2 is smaller than 20 mm, and the rounding range is too large when it is larger than 40 mm, which is not preferable. More preferably, it is a value of R2 = 30mm.

In addition, the value of R4 is sufficient not to interfere with the turn-up band (not shown) included in the forming drum 6, so 8mm ≦ R3 ≦ 10mm is preferable. The most preferred value is R3 = 9.5 mm.

FIG. 5 shows a configuration in which a semifinished product including a tire bead part is assembled to a forming drum according to the present invention, and can maintain a smoothly curved shape without sharply bending at the turn-up end 8 when forming the semifinished product. .

Thus, as in FIG. 6, it can be clearly seen that the wave weaving of the rim flange component 2 and the folding of the nylon chaper 5 do not occur even after the semifinished product is vulcanized.

According to the present invention having the above-described configuration, it is possible to prevent the phenomena of folding of the rim flange component and the folding of the nylon chaper by forming various rounding portions without forming the shoulder portion of the forming drum sharply bent. There is an advantage that the durability of the bead portion can be greatly improved.

In addition, the edge strips that have been conventionally disposed on the carcass ply can be deleted, which greatly contributes to shortening the molding time and improving productivity.

1 is a cross-sectional view showing a profile of a conventional forming drum.

FIG. 2 is a cross-sectional view illustrating a configuration in which a semifinished product including a tire bead part is assembled to the forming drum of FIG. 1.

3 is a cross-sectional view illustrating a state in which a defect is generated in a tire formed by the molding drum of FIG. 1.

Figure 4 is a cross-sectional view showing a profile of the forming drum according to the present invention.

FIG. 5 is a cross-sectional view illustrating a configuration in which a semifinished product including a tire bead part is assembled to the forming drum of FIG. 4.

6 is a cross-sectional view showing a state where there is no defect in a tire formed by the forming drum of FIG. 4.

※ Explanation of Major Drawings

2. Rim Flange Components

4 ... Carcass

5 ... Chaper

6. Tire forming drum

7. Shoulder part of molding drum

8 ... Carcass Turn-Up End Point

9 ... edge strip

Claims (1)

In the tire forming drum, The shoulder part 7 profile of the forming drum has four rounding parts R1, R2, R3, and R4 formed in a continuous shape. The diameter (D) of the forming drum (6), the vertical height (H) of the shoulder portion 7, the horizontal distance (W) of the shoulder portion 7, 0.075D ≤H ≤0.095D 0.81H ≤W ≤0.91H Made of a relationship Lower point (V) and upper point (N) of the vertical line (R3), H, between the vertical distance (A) from V to N, between the point (Q) and N located on the vertical extension line connecting N in V The vertical distance (B) of, the distance (C) between the intersection point (U) and Q of the vertical extension line connecting N in V and the upper horizontal line (X) of the forming drum (6), 0.20H ≤A ≤0.30H 0.27H ≤B ≤0.37H 0.21H ≤C ≤0.31H Is made of R1 is defined to pass through Q while in contact with X, R2 is in contact with R1 which is perpendicular to N while in contact with R1, and R4 is in contact with R3 through V and in contact with the horizontal line (Z), 20 mm ≤ R2 ≤ 40 mm, 8 mm Tire forming drum, characterized in that ≤ R3 ≤ 10 mm.