JP2001252991A - Method for manufacturing pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a pneumatic tire wherein reaction force of an upward habit-forming part at both side end parts of a carcass material to a bead core lock of a bead setter is decreased. SOLUTION: Previously upward habit-forming parts at two or more positions are applied to both bead core rewinding side end parts of a material for radial carcass ply wherein a steel cord is coated by unvulcanized rubber, knotching is applied to coated rubber part of the habit-forming end part, it is above cylindrically jointed to a forming drum, the bead core component is positioned at the habit-forming end part, and fixed by locking from inside. After deforming in a toroid state by being inflatedly projected under the fixed state, the habit- forming part is bonded by enfolding around the bead core component to form the unvulcanized tire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a pneumatic tire, and more particularly to a method for manufacturing an unvulcanized tire for a pneumatic radial tire in which a steel cord is applied to a carcass ply. In tire molding,
The present invention relates to a method for manufacturing a pneumatic tire capable of stably winding a carcass ply material around a bead core member with high accuracy.

[0002]

2. Description of the Related Art Among pneumatic radial tires, so-called heavy duty pneumatic radial tires used for heavy vehicles such as trucks and buses generally use a steel-coated rubber-coated ply as a carcass. Further, since this kind of tire is filled with a high internal pressure, a structure is adopted in which the carcass is turned around the bead core from the inside to the outside of the tire to lock the carcass on a pair of bead cores.

However, since the carcass fold is located radially in the rubber of the bead portion and has a cut-off end, a large strain is concentrated on the carcass fold end under the rolling load of the tire. However, separation failure is likely to occur from the folded end. Therefore, in order to avoid the strain concentration at the turning end, as shown in FIG. 13, a cross section of the bead portion 30 is replaced with the winding structure in which the end portion 31E of the carcass 31 wraps around the bead core 32 in place of the turning structure. Embedded structures have been proposed.

[0004] However, the winding end portion 31E is connected to the carcass 3
Because the steel cords of the carcass 31 are radially arranged and have a high rebound resilience, the steel cords of the carcass 31 have a large rebound resilience. Away from the bead core 32. As a result, it is difficult to achieve a desired bead core winding state, and eventually, the winding end 3
Concentrated strain acts on 1Ee, and a failure from a crack generation to a burst is likely to occur, and it is impossible to realize the expected improvement in bead portion durability. In addition, the excessive winding damages the steel cord and causes a problem of creating a defective bonding portion with rubber.

Accordingly, the present applicant has already filed Japanese Patent Application No. 11-1.
In the specification of No. 9847, the rubber coating of steel cord
The bead core of the carcass ply
Pneumatic tires with upper plastic deformation points
You. FIG. 12 shows the bead 3 core winding portion that becomes plastically deformed.
It is shown in the bead section view. The bead portion 20 shown in FIG.
And the carcass 21 is the winding portion 21R of the bead core 22.
And the bead core 22 has a substantially hexagonal cross section,
The winding part 21R is located at the plastic deformation point p.₁ , P_Two , P _Three Have
You.

[0006] A plastically deformed portion p ₁ ,
By providing p ₂ and p ₃ , since the winding portion 21R is located along the peripheral surface of the bead core 22, the strain acting on the winding end 21Re is significantly reduced, and the separation resistance of the winding end 21Re is greatly improved. It is confirmed that the durability of the bead portion 20 is significantly improved. Winding end 2
In order to position 1Re closer to the bead core 22, the plastically deformed portion near the winding end 21Re plays an especially important role.

[0007]

However, the winding portion 21
R is the plastic deformation point p₁ , P_Two , P_Three Make tires
The following issues exist when manufacturing
Do you get it. That is, the plastic deformation part p is added to the end 10AE.₁ ,
p_Two , P_Three Molded carcass ply material 10A
2 shows a cross section of a cylindrical band 10A wound on a ram 2B.
In FIG. 11, a pair of bead core members 15 are
Sexual deformation part p₁ , P_Two , P _Three When applying to
A pair of bead setters 4 holding the bead core member 15
Once the plastic deformation point p₁ , P_Two , P_Three Must pass
No.

Next, as shown in FIG. 11, in order to set each bead core member 15 at a predetermined position with respect to the band 10A, the bead setter 4 applies plastically deformed portions p _{1 to} p _{2 to} p ₃ of the end 10AE of the band 10A. Must be forcibly deformed from the position indicated by the two-dot chain line to the position indicated by the solid line. In this state, the bead core member 15 is locked and fixed to the band 10A by expanding the diameter of the locking means 16 in the direction of the arrow.

However, the plastic deformation part p ₁ of the bead setter 4
Ｐp ₂ ｐp ₃ and the forced deformation cause a large reaction force to the bead setter 4. Since this reaction force places a large burden on the bead setter 4, the forced deformation takes time, and eventually, the molding cycle time increases, and the molding productivity decreases. Further, in order to oppose the large reaction force, it is necessary to strengthen the output system of the molding machine. On the other hand, serious problems such as insufficient durability of the molding machine due to the reaction force occur. Also, there is a problem that molding accuracy is impaired, such as inconvenience in accurate positioning of the bead core member 15.

Accordingly, an object of the present invention described in claims 1 to 4 of the present invention is to completely solve the above-mentioned remaining problems, and more specifically, to significantly reduce the reaction force of a bead core member against a bead setter. By this, with the conventional molding machine, maintaining sufficient durability and high productivity,
An object of the present invention is to provide a method for manufacturing a pneumatic tire that can be molded with high precision.

In order to achieve the above object, the invention described in claim 1 of the present invention relates to a radial carcass ply in which an unvulcanized rubber is coated on a number of parallel-arranged steel cords in molding an unvulcanized tire. Two or more upward curlings are applied in advance to both ends of the material, where the bead core is wound along the tire carcass circumferential direction, and then cut at a predetermined pitch into the coated rubber parts on both side ends having the curling parts. Put the material having a plurality of cuts on both sides to the forming drum and join it cylindrically, supply a pair of bead core members at both ends with a habit of cylindrical material, and position them, Each bead core member at this position is locked and fixed from the inside through the above-mentioned material, and under this fixing, the above-mentioned material is swelled and deformed in a toroidal shape. Was close contact winding around the bead core members, then, it is a manufacturing method of a pneumatic tire which comprises bringing Hariawa the unvulcanized belt unvulcanized tread rubber on the outer peripheral side of the toroidal material.

According to the first aspect of the present invention, there is provided a second aspect.
As in the invention described in (1), the predetermined pitch to be cut is set to 1
According to the first and second aspects of the present invention, the cut length from the edge of each side end is set to be within a range of 3/12 to 9/12 times the cross-sectional circumferential length of the bead core member. Is suitable.

According to the first to third aspects of the present invention, as in the fourth aspect of the present invention, when each of the customizing portions is wound around and adhered to the periphery of the bead core member, the cut positions are sandwiched from both sides. The ends of the steel cords are inclined in opposite directions from each other at the cut position.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic plan view of a molding machine used in the present invention, FIG. 2 is a plan view of a material for a radial carcass ply immediately before supplying a forming drum according to the present invention, and FIG. 3 is a radial carcass shown in FIG. FIG. 4 is a right half sectional view of the ply material, FIG. 4 is a partial sectional view of the radial carcass ply material according to the present invention after being wound around a forming drum, and FIG. 5 is a material when a bead core member is positioned. FIG. 6 is a cross-sectional view of a hammered end and a bead setter, and FIG. 6 swells and deforms the material shown in FIG.
FIG. 7 is a schematic cross-sectional view of the whole when the hammered end is wound around and adhered to the bead core member, and FIG. 7 shows the inclination angle on the forming drum, the tensile strength retention rate of the steel cord, and the hammered end. FIG. 8 is a diagram showing a relationship between a cutting pitch and a reaction force to a bead setter, and FIG. 9 is a diagram showing a hammering end and a bead core member shown in FIG. 6 according to the present invention. FIG. 10 is a partial perspective view of FIG.
FIG. 7 is a side view of the steel cord and the bead core member at the set ends shown in FIG. 6 according to the present invention.

In FIG. 1, a molding machine includes a housing 1 containing a motor for driving each rotating part, a molding drum 2 mounted on a shaft extending from the housing 1, and a radial carcass ply material (described later) formed on the molding drum 2. A servicer 3 for supplying a carcass material), a pair of bead setters 4 for conveying a pair of bead core members to the forming drum 2 and fixing them at predetermined positions, and a carcass material on the forming drum 2 being in close contact with the bead core member. And a pair of stitcher rolls 5. The forming drum 2
An inflatable bladder 2B is provided at the center.

The molding machine includes a belt / tread band drum (BT drum) 7 for laminating an unvulcanized belt and an unvulcanized tread rubber supplied from another servicer 6 in a cylindrical shape.
And an O-ring 8 for transporting the belt / tread band stacked on the BT drum 7 onto the forming drum 2.

2 and 3, referring to FIG. 12, the carcass material 10 is unvulcanized into a number of parallel-arranged steel cords 11 that are substantially perpendicular to the circumferential direction (around the tire axis) of the carcass 21 of the tire. It is a member coated with rubber 12. In FIG. 2, the steel cord 11 is indicated by a broken line.
Reference symbol C is a width center line of the carcass material 10.

As shown in each figure, a bead core 2 is provided on a carcass material 10 along a circumferential direction of a carcass 21 of a tire.
Both end portions 10E corresponding to both end portions 21R where 2 is wound
The carcass material 10 is supplied from the servicer 3 to the forming drum 2 beforehand at two or more locations, in the illustrated example, three locations in advance.

This habit is applied to the steel cord 11 plastically.
Refers to the state in which sexual deformation has occurred. As shown in FIG.
When the raw material 10 is supplied to the molding drum 2,
Hacking part p₁ , P_Two , P_Three Is upward
I do. Habit attaching part p₁ , P_Two, P_Three The car of the tire
Hammering part p of both ends 21R₁ , P_Two , P _Three 
Is equivalent to

Here, before being supplied to the molding drum 2,
In advance, the hammering portions p ₁ , p ₂ , p _{3 of} the carcass material 10
Cuts 13 are made at a predetermined pitch P in the coated rubber 12 at both end portions 10E. However, per one winding of the carcass material 10 around the forming drum 2,
A plurality of cuts 13 are provided at both end portions 10E. The cut 13 is preferably cut from the edge 10Ee of the side end 10E. The carcass material 10 having the plurality of cuts 13 is jointed in a cylindrical shape on the bladder 2B of the molding drum 2. The cylindrical carcass material 1 at this time
The state of 0 is shown in the sectional view of FIG. The symbol X is a molding drum 2
Is the rotation axis.

Thereafter, the pair of bead core members 15 held by the pair of bead setters 4 are transported toward the forming drum 2 and, as shown in FIG. 5, the hammering portions p ₁ , p ₂ , p ₃ of the cylindrical carcass material 10. Each bead core member 15 is located at both side end portions 10E having the following. At this position, each bead core member 15 held by each bead setter 4 is
Lock the bladder 2B from the inside through 0. This locking method uses, for example, a pair of locking means 16 provided on the molding drum 2, which can be freely enlarged and reduced in diameter, directly below the bead core member 15 positioned with respect to the molding drum 2.

Thereafter, each bead setter 4 is released from holding of each bead core member 15 and is retracted from the forming drum 2. Then, as shown in FIG.
In the state where the lock 5 is held, for example, a pressurized gas is supplied into the bladder 2B, and at the same time, the mutual interval between the pair of lock means 16 is narrowed, and the carcass material 10 is expanded and deformed in a toroidal shape.

At the same time as the swelling deformation, the stitching roll 5 is moved in the direction of the arrow while rotating the stitching roll 5 about the axis and pressing the stitching roll 5 to thereby cause each of the hammered ends 10E of the swelling deformed carcass material 10 to move. Wrap and adhere around the bead core member. At this time, the customizing portions p ₁ , p ₂ , and p ₃ are adjusted to each refraction angle portion of the bead core member 15.

Thereafter, a band (not shown) of an unvulcanized belt and an unvulcanized tread rubber laminated on the BT drum 7 is conveyed to a predetermined position of the molding drum 2 by the O-ring 8, and the band is The molding of the unvulcanized tire is completed by being attached to the outer peripheral side of the carcass material 10. Thereafter, the unvulcanized tire is subjected to vulcanization molding to complete a pneumatic tire having a bead portion 20 shown in FIG.

The operation and effect of the pneumatic tire described above will be described below. That is, in FIGS. 2 to 4, the portion excluding the imprint end 10E of the previous carcass material 10 is supplied to the forming drum 2 exhibits a planar, the imprint unit p ₁ ~ imprint unit p ₂ for this plane The inclination angle α changes to the inclination angle β of the cylindrical carcass material 10 on the molding drum 2 with respect to the axis X direction of the molding drum 2.

When the carcass material 10 changes from a planar shape to a cylindrical shape, both end portions try to increase the circumferential length.
At this time, the curled end of the conventional carcass material is deformed outward, and the inclination angle β tends to be smaller than the inclination angle α.

On the other hand, the carcass material 10 having a plurality of cuts 13 at each of the hammered ends 10E on both sides is opened on both sides in the circumferential direction with the cut 13 as a boundary, so that as shown in FIG. The hammering end 10E is inclined outward, so that the inclination angle β is larger than the inclination angle α. According to the experimental results, when the peripheral length of the inner peripheral surface of the cylindrical carcass material 10 is 1654 mm, α = 53 ° becomes β =
For 60 °, α = 50 ° for 1800 mm becomes β = 60
°.

In short, FIG. 7 is a graph showing the relationship between the inclination angle β and the retention (%) of the tensile strength of the steel cord 11 at the hauling end 10E. In addition, when viewed at the same inclination angle β, the embodiment shown by the solid line exhibits an effect of having a larger retention (%) than the conventional one shown by the broken line. In addition, the customization part p ₁
Causes plastic deformation of the steel cord 11, the inclination angle β returns to the inclination angle α when the bead core member 15 is locked.

The bead setter 4 which passes through the hammering end 10E due to the presence of the cut 13 which is left there.
Of the bead setter 4 when the bead core member 15 is positioned at a predetermined position.
The reaction force of E is greatly reduced. This eliminates the need for modification of the conventional molding machine, guarantees sufficient durability of the bead setter 4 as it is, can maintain high productivity in the molding process, and has a high precision. Molding becomes possible.

Here, it is preferable that the cutting pitch P is 150 mm or less. This is because in FIG. 8, the cutting pitch P (mm) and the reaction force (MP
This is because the reaction force saturates when the cutting pitch P exceeds 150 mm, as is clear from the diagram showing the relationship with (a).

The bead core member 15 shown in each figure is a so-called hexagonal bead core having a hexagonal cross section, but may have a polygonal cross section of a quadrangle or more, or a round shape. good. Bead core member 15 to be applied
In relation to the above, the cut length of the cut 13 from the edge 10Ee of each hammering end portion 10E is preferably in the range of 3/12 to 9/12 times the cross-sectional circumferential length of the bead core member 15. .

As shown in FIG. 9, when each hammered end 10E is wound around and adhered to the periphery of the bead core member 15, both sides of the cut 13 are cut from the end of the cut 13 to the edge 10Ee of the hammered end 10E. And is wound around the bead core member 15 so as to be in close contact with the fan core.

At this time, as shown in FIG.
A steel cord 11 sandwiching a plane Q including the original cut 13 and extending radially from the axis X from both sides at three positions;
The ends are inclined in opposite directions with respect to the plane Q at an inclination angle θ with respect to the plane Q. Thereby, even if a crack occurs at the end of the steel cord 11 located at the winding end 21Re of a certain portion of the carcass 21 in the tire, a circumferential direction is formed between the winding ends 21Re on both sides of the plane Q. In this case, the crack is prevented from progressing in the circumferential direction, so that the effect of improving the durability of the bead portion 20 can be obtained.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A radial ply tire for trucks and buses having a size of 435 / 45R22.5, a bead core member 15 having a hexagonal bead core and hammering portions p ₁ , p
_2, the plastic deformation interior angles in p ₃ with the carcass material 10 which was 120 °. The cross-sectional circumferential length of the hexagonal bead core 15 is 56 mm, the cut pitch P is 30 mm,
The length of the cut 13 was 40 mm.

The carcass material 10 is wound around the forming drum 2 to form a cylindrical shape, and the bead setter 4 holding the hexagonal bead core 15 is transported to a predetermined position.
The reaction force acting on the bead setter 4 when passing through E and the reaction force acting on the bead setter 4 when positioning the hexagonal bead core 15 at the lock position were measured, and were compared between the embodiment and the conventional example.

In the embodiment, when the measurement results are expressed by indices with the two reaction forces of the conventional example being 100, the reaction force at the time of passage is 86 and that at the time of lock positioning is 82 in the embodiment. From these results, the effectiveness of the example can be demonstrated.

[0037]

According to the invention described in claims 1 to 4 of the present invention, the carcass material is provided on both sides of the carcass material.
The reaction force caused by the passage of the bead setter for holding the bead core and the reaction force of the bead setter at the time of locking the bead core can be greatly reduced. Thus, it is possible to provide a pneumatic tire manufacturing method capable of maintaining high productivity and enabling high-precision molding.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a molding machine used in the present invention.

FIG. 2 is a plan view of a carcass material immediately before a forming drum is supplied according to the present invention.

FIG. 3 is a right half sectional view of the carcass material shown in FIG. 2;

FIG. 4 is a partial cross-sectional view of the carcass material according to the present invention after being wound around a forming drum.

FIG. 5 is a cross-sectional view of a bend setter and a bead setter when positioning a bead core member according to the present invention.

6 is a schematic sectional view of the entire carcass material shown in FIG. 5 when the carcass material is swollen and deformed, and a hammered end is wound around and adhered to a bead core member.

FIG. 7 is a diagram showing a relationship between a tilt angle on a forming drum and a tensile strength retention of a steel cord with respect to a hammered end.

FIG. 8 is a diagram showing a relationship between a cutting pitch and a bead setter reaction force.

FIG. 9 is a partial perspective view of a hammered end and a bead core member shown in FIG. 6;

FIG. 10 is a side view of a steel cord and a bead core member at a hammered end shown in FIG. 6;

FIG. 11 is a cross-sectional view of a conventional set end and a bead setter when positioning a conventional bead core member.

FIG. 12 is a sectional view of a bead portion of a tire using the carcass material according to the present invention.

FIG. 13 is a sectional view of a bead portion of a conventional tire having no habituation portion.

[Explanation of symbols]

Reference Signs List 1 housing 2 forming drum 2B bladder 3 carcass material servicer 4 bead setter 5 stitcher roll 6 servicer 7 BT drum 8 o-ring 10 carcass material 10E both side edges having hammered portion 10Ee edges of both side edges 11 steel cord 12 covering rubber 13 cut 15 bead core member 16 locking means p _1, p _2, p ₃ imprint unit alpha, steel cords with respect to the plane θ plane Q containing the axis Q cut angle of inclination P cut pitch X building drum of β imprint unit p ₁ ~p ₂ Tilt angle

Claims (4)

[Claims] 1. Both ends of a radial carcass ply material in which a number of parallel-arranged steel cords are coated with an unvulcanized rubber in forming an unvulcanized tire, and a bead core is wound around the tire in a carcass circumferential direction. To each of two or more upwardly-curved parts in advance, and then make cuts at a predetermined pitch in the coated rubber parts on both side ends with the curly parts, and form a material with a plurality of cuts on both sides into a molding drum. Supplied and jointed in a cylindrical shape, a pair of bead core members are supplied and positioned at both ends having a habit of cylindrical material, and each bead core member at this position is locked and fixed from inside through the above material Then, the material is swelled and deformed in a toroidal shape under this fixation, and each hammered portion of the swelled and deformed material is wound around the bead core member and brought into close contact therewith. A method for manufacturing a pneumatic tire, comprising bonding an unvulcanized belt and an unvulcanized tread rubber to an outer peripheral side of a rubber material. 2. The manufacturing method according to claim 1, wherein the predetermined pitch at which the cut is made is 150 mm or less. 3. The manufacturing method according to claim 1, wherein the cut length from the edge of each side end is set to be within a range of 3/12 to 9/12 times the cross-sectional circumferential length of the bead core member. 4. The steel cord ends sandwiching the cut position from both sides are inclined in directions opposite to each other with the cut position as a boundary when each of the customizing portions is wound around and adhered to the periphery of the bead core member. 3. The production method according to any one of the above items 3.