JP2014015005A - Method for producing bead member, and bead member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a method for producing a bead member ensuring that the position of a bead core in a tire is a stable proper position; and the bead member.SOLUTION: A method for producing a beam member includes: a rubber coating step of coating an annular bead core 2, except for a partial peripheral surface thereof, with a rubber member 3 so as to constitute a bead member structure 1'; and a press step of pressing the bead member structure 1' in a center direction of the cross section of the bead member structure 1' so as to form a bead member 1 having a predetermined shape. A bead member is formed in a predetermined shape in which an annular bead core except for a partial peripheral surface thereof is coated with a rubber member.

Description

  The present invention relates to a method for manufacturing a bead member for a tire and a bead member.

In the pneumatic tire molding process, an inner liner is usually wound around a molding drum, a pair of left and right chafers are wound around both side edges thereof, and a carcass is wound around the inner liner and the pair of left and right chafers so as to be wide. A pair of bead assemblies consisting of a bead core and a stiffener are fitted on the left and right sides of the carcass on both sides of the carcass so that the bead portions are brought close to each other while the center is swollen. The chafer is folded around the bead core and the stiffener to form a toroid. A belt and a tread are attached to the bulged center, and sidewalls are attached to both outer peripheral surfaces of the carcass.
The green tire thus formed is vulcanized and molded by a vulcanizer to form a pneumatic tire.

Here, since the bead core is positioned in direct contact with the chafer, there is a problem that the relative position of the bead core with respect to the molded tire is directly influenced by the shape of the chafer and is not stable.
Therefore, an example in which a cylindrical rubber is fitted around the entire circumference of the bead core to form a bead member has been proposed (see Patent Document 1).

JP 59-1555028 A

  The manufacturing method of a bead member disclosed in Patent Document 1 is a daylight comprising an upper die on the outer peripheral side and a lower die on the inner peripheral side by fitting a cylindrical rubber having a substantially C-shaped cross section around the entire circumference of the annular bead core. It is press-molded with a press to vulcanize and bond cylindrical rubber.

Since the bead core is covered with cylindrical rubber all around, the bead core does not directly contact the chafer due to the cylindrical rubber, but at the time of press molding by pressing between the upper and lower molds in daylight press, the cylindrical rubber The relative position of the bead core is not stable, and the relative position of the bead core depends on the gauge of the cylindrical rubber.
That is, there is variation in the position of the bead core in the cross section of the press-molded bead member.

  If there is a variation in the position of the bead core in the bead member, when the tire is molded using this bead member, the position of the bead core in the tire, that is, the position of the bead core relative to the axis of the tire will be shifted. It adversely affects performance (especially tire uniformity).

  This invention is made | formed in view of this point, and the process made into the objective exists in the point which provides the method and bead member which manufacture the bead member which can make the position of the bead core in a tire into the stable appropriate position.

In order to achieve the above object, the invention according to claim 1
A rubber coating step of forming a bead member structure by covering an annular bead core with a rubber member except for a part of the peripheral surface;
A pressing step of forming the bead member having a predetermined shape by pressing the bead member structure in the center direction of the cross section of the bead member structure;
It is a bead member manufacturing method characterized by comprising.

Invention of Claim 2 is a bead member manufacturing method of Claim 1,
The rubber coating step is characterized in that at least a peripheral surface on the inner peripheral side except a peripheral surface on the outer peripheral side of the bead core is covered with a hard rubber member having a large elastic modulus.

Invention of Claim 3 is a bead member manufacturing method of Claim 2,
The rubber coating step is characterized in that the hard rubber member covers both the peripheral surface on the inner peripheral side of the bead core and the peripheral surface on both side surfaces continuous with the peripheral surface on the inner peripheral side.

Invention of Claim 4 is a bead member manufacturing method of Claim 3,
The bead core has a rectangular cross section;
The both sides of the hard rubber member covering the circumferential surfaces on both side surfaces of the bead core are characterized by forming tapered surfaces by gradually decreasing the thickness from the inner circumferential side toward the outer circumferential side.

The invention according to claim 5
The bead member is characterized in that an annular bead core is covered with a rubber member except for a part of the peripheral surface and molded into a predetermined shape.

The invention described in claim 6 is the bead member according to claim 5,
Except for the outer peripheral surface of the bead core, at least the inner peripheral surface is covered with a hard rubber member having a high elastic modulus.

The invention according to claim 7 is the bead member according to claim 6,
The hard rubber member covers both the peripheral surface on the inner peripheral side of the bead core and the peripheral surface on both side surfaces that are continuous with the peripheral surface on the inner peripheral side.

The invention according to claim 8 is the bead member according to claim 7,
The bead core has a rectangular cross section,
The both sides of the hard rubber member covering the peripheral surfaces on both side surfaces of the bead core are characterized by forming tapered surfaces by gradually decreasing the thickness toward the outer peripheral surface side.

  According to the bead member manufacturing method according to claim 1, a rubber coating step of forming a bead member structure by covering an annular bead core with a rubber member except for a part of the peripheral surface, and a bead member structure A pressing process in which a bead member having a predetermined shape is formed by pressing in the center direction of the cross section of the body, so that when the bead member constituent body is pressed in the center direction of the cross section of the bead member constituent body in the pressing process, Since the press die directly presses the peripheral surface not covered with the rubber member, the bead core itself can be reliably positioned and press-molded, and therefore the bead core position in the bead member does not vary, so the bead core in the tire Can be easily set to a stable and appropriate position, and the performance of the tire can be improved.

  According to the bead member manufacturing method according to claim 2, since at least the inner peripheral surface of the bead core is covered with the hard rubber member having a large elastic modulus except for the outer peripheral surface of the bead core in the rubber coating step, The bead core itself can be positioned by directly pressing the outer peripheral surface that is not covered with a member from the outside, and the inner peripheral surface of the bead core is coated with a hard rubber member having a high elastic modulus and pressed. Since it is molded, the carcass and chafer that are folded back so as to be wound around the bead member can be stably held, and the position of the bead core in the tire can be firmly maintained at a more stable and appropriate position.

  According to the bead member manufacturing method according to claim 3, in the rubber coating step, the peripheral surface on both side surfaces continuous with the peripheral surface on the inner peripheral side is covered with the hard rubber member together with the peripheral surface on the inner peripheral side of the bead core. Therefore, the hard rubber member is covered at a predetermined position so as to be fitted to the inner peripheral surface and the both peripheral surfaces of the bead core, and the bead member having a predetermined shape can be easily press-molded.

  According to the bead member manufacturing method of claim 4, the bead core has a rectangular cross section, and both side portions of the hard rubber member covering the peripheral surfaces on both side surfaces of the bead core gradually increase in thickness toward the outer peripheral surface side. Since the taper surface is formed by reducing the thickness of the bead member, both sides of the bead member face the tapered surface of the hard rubber member toward the outer peripheral side, thereby facilitating the attachment of the stiffener provided around the outer peripheral side.

  In the bead member according to claim 5, since the annular bead core is covered with a rubber member except for a part of the peripheral surface and formed into a predetermined shape, the bead core is used by utilizing the peripheral surface of the bead core not covered with the rubber member. The rubber member coated with a precise positioning can be accurately molded into a predetermined shape, so that there is no variation in the position of the bead core in the bead member, so that the position of the bead core in the tire is a stable and appropriate position. Can be easily achieved and the performance of the tire can be improved.

  In the bead member according to claim 6, since at least the inner peripheral surface of the bead core is covered with a hard rubber member having a large elastic modulus except for the outer peripheral surface of the bead core, the inner peripheral surface of the bead core is elastic. Since a hard rubber member with a high rate is coated and press-molded, the carcass and chafer that folds around the bead portion can be stably held, and the position of the bead core in the tire is firmly established at a more stable and appropriate position. Can be maintained as.

  In the bead member according to claim 7, since the peripheral surface on both sides continuous to the peripheral surface on the inner peripheral side as well as the peripheral surface on the inner peripheral side of the bead core is covered with the hard rubber member, the hard rubber member is the bead core. A bead member having a predetermined shape can be easily formed by being covered at a predetermined position so as to be fitted into the peripheral surface on the inner peripheral side and the peripheral surfaces on both side surfaces.

  In the bead member according to claim 8, the bead core has a rectangular cross section, and both side portions of the hard rubber member covering the peripheral surfaces on both side surfaces of the bead core are gradually tapered toward the outer peripheral surface side to taper. Since the surface is formed, both sides of the bead member face the tapered surface of the hard rubber member toward the outer peripheral side, facilitating attachment of the stiffener provided around the outer peripheral side.

It is the side view and sectional drawing of a bead core. It is the side view and sectional drawing of a hard rubber member. It is the side view and sectional drawing of a bead member structure. It is the side view and sectional drawing of the metal mold | die of a press machine. It is explanatory drawing which shows the procedure of the press process which shape | molds a bead member. It is a disassembled sectional view of a bead assembly. It is sectional drawing of a bead assembly. It is a fragmentary sectional view of the pneumatic tire which uses this bead member.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
The bead member 1 according to the present embodiment is formed by covering an annular bead core 2 with a hard rubber member 3 having a large elastic modulus except for a part of the peripheral surface, and molding it into a predetermined shape.

As shown in FIG. 1, the annular bead core 2 is a strand bead in which a bead wire 2 w whose cross section is a parallelogram is overlapped and wound into an annular shape, and has an inner peripheral surface (inner peripheral surface). 2i, the outer peripheral surface (outer peripheral surface) 2o, and both peripheral surfaces (side peripheral surfaces) 2s, 2s have a rectangular cross section.
The rectangular cross section of the bead core 2 has an inclination with respect to the annular central axis of the bead core 2, and the outer peripheral side peripheral surface 2o, the inner peripheral side peripheral surface 2i, and the both side side peripheral surfaces 2s and 2s of the bead core 2 are tapered. ing.

As shown in FIG. 2, the hard rubber member 3 covered with the bead core 2 includes an inner peripheral portion 3 i that covers the inner peripheral peripheral surface 2 i and both peripheral side peripheral surfaces except for the outer peripheral peripheral surface 2 o of the bead core 2. The cross section is U-shaped from both side portions 3s and 3s covering 2s and 2s (see FIG. 2B).
The inside of the U-shaped cross section of the hard rubber member 3 forms a rectangle that is the same shape as the rectangular cross section of the bead core 2.
And both the side parts 3s and 3s of the hard rubber member 3 are gradually reduced in thickness from the inner peripheral side toward the outer peripheral side, and the leading edges are sharp.

  A hard rubber member 3 having a U-shaped cross-section as shown in FIG. 2 (b) has a bead core 2 formed of a bowl-shaped long member extruded by a rubber extruder having a die having the same U-shape. It can be formed by cutting with a circumferential length of.

In the rubber coating step, the hard rubber member 3 is fitted into the bead core 2 from the inner peripheral side, and the outer peripheral side peripheral surface 2o of the bead core 2 is removed, as shown in FIG. The bead member structure 1 ′ is formed by covering the both side surface side surfaces 2 s and 2 s continuous with the side surface 2 i with the inner periphery portion 3 i having a U-shaped cross section of the hard rubber member 3 and both side portions 3 s and 3 s. Configure.
Since the hard rubber member 3 has the length of the circumference of the bead core 2, both end faces fitted into the bead core 2 in an annular shape come into contact with each other to form an annular shape, and gradually increase in thickness from the inner peripheral side toward the outer peripheral side. The left and right side portions 3s, 3s that are made smaller are formed with tapered surfaces on the outside.

The bead member structure 1 ′ in which the bead core 2 is thus coated with the hard rubber member 3 is press-molded by the press 10 to form the bead member 1.
The hard rubber member 3 is covered at a predetermined position so as to be fitted to the inner peripheral side peripheral surface 2i of the bead core 2 and the both side peripheral side peripheral surfaces 2s, 2s. Therefore, the bead member 1 having a predetermined shape is easily formed by press molding. can do.

FIG. 4 shows a side view and a cross-sectional view of the die of the press 10.
The press machine 10 includes an outer peripheral mold 11, an inner peripheral mold 12, a left mold 13 and a right mold 14, all of which are annular, and the outer mold 11 is fixed and disposed on the inner peripheral side of the outer mold 11. The inner peripheral mold 12 is divided in the circumferential direction and provided so as to be movable in the radial direction.
The left side mold 13 and the right side mold 14 disposed opposite to each other between the outer peripheral mold 11 and the inner peripheral mold 12 are provided so as to be movable in the axial direction of the central axis of the outer peripheral mold 11.

The outer peripheral mold surface 11 a on the inner periphery of the outer peripheral mold 11 forms the same tapered surface as the outer peripheral peripheral surface 2 o that is not covered with the hard rubber member 3 of the bead core 2.
The inner peripheral mold surface 12a on the outer periphery of the inner peripheral mold 12 forms a mold surface corresponding to the inner peripheral surface of the inner peripheral portion 3i of the hard rubber member 3, and the cross section is curved inward (center side).

The left mold surface 13 a of the left mold 13 forms a taper surface that is substantially the same as the outer tapered surface 3 t of the left side portion 3 s of the hard rubber member 3.
The right mold surface 14 a of the right mold 14 forms a tapered surface that is substantially the same as the outer tapered surface 3 t of the right side portion 3 s of the hard rubber member 3.

  When the inner peripheral mold 12, the left mold 13 and the right mold 14 are combined with the outer peripheral mold 11, the bead member 1 is press-formed by the outer peripheral mold surface 11a, the inner peripheral mold surface 12a, and the left and right mold surfaces 13a, 14a. Is formed (see FIG. 4B).

The procedure of the pressing process by the pressing machine 10 will be described with reference to FIG.
First, as shown in FIG. 5 (1), a bead member constituting body 1 'is fitted from the right side to the outer peripheral die 11 of the press 10 with the die open.
In the bead member constituting body 1 ′, the outer peripheral side peripheral surface 2 o that is not covered with the hard rubber member 3 of the bead core 2 is in direct contact with the outer peripheral mold surface 11 a of the outer peripheral mold 11, and the bead core 2 is directly positioned by the outer peripheral mold 11. Holds firmly.

  As shown in FIG. 5 (2), with the outer peripheral mold 11 holding the bead member structure 1 ′, the divided inner peripheral mold 12 is moved radially toward the outer peripheral mold 11, The inner peripheral mold surface 12a is pressed against the inner peripheral surface of the inner peripheral portion 3i of the hard rubber member 3, and the left mold 13 and the right mold 14 are moved in the axial direction so as to sandwich the bead member constituting body 1 'from the left and right, The left and right mold surfaces 13a and 14a of the left mold 13 and the right mold 14 are pressed against the tapered surfaces 3t and 3t of the left and right side portions 3s and 3s of the hard rubber member 3, respectively.

  That is, as shown in FIG. 5 (3), the press machine 10 is configured such that the bead member constituting body 1 ′ is cross-sectioned by the outer circumference die 11, the inner circumference die 12, the left die 13 and the right die 14. The bead member 1 having a predetermined shape is formed by pressing in the center direction.

  The bead core 2 itself can be reliably positioned by directly pressing the outer peripheral side peripheral surface 2o not covered with the rubber member of the bead core 2 so that the inner peripheral side peripheral surface 2i and both side surface peripheral surfaces of the bead core 2 can be positioned. 2s and 2s can improve the precision of press molding performed by covering the hard rubber member 3 having a large elastic modulus, and therefore, the bead member 1 does not vary in the position of the bead core 2.

  In this pressing step, the hard rubber member 3 may be welded to the bead core 2 and vulcanized.

  The annular bead member 1 manufactured in this way is coated with a hard rubber member 3 having a large elastic modulus on the inner peripheral side and both side surfaces of the bead core 2 and is press-molded into a predetermined shape. A hard stiffener 21 made of rubber having a high elastic modulus and a soft stiffener 22 made of rubber having a low elastic modulus are sequentially fitted and vulcanized to form a bead assembly 20 (see FIG. 6).

  The hard stiffener 21 and the soft stiffener 22 are simultaneously bonded by an extruder and can be extruded and formed while forming the cross-sectional shape shown in FIG. 6, and cut into a length approximately equal to the circumferential length of the bead member 1. Then, the bead member 1 is wound around the outer periphery.

Referring to FIG. 6, bead member 1 is an outer peripheral side peripheral surface 2 o of bead core 2 whose outer peripheral surface is not covered with a rubber member, and left and right side surfaces are tapered surfaces of left and right side portions 3 s and 3 s of hard rubber member 3. 3t and 3t, and the tapered surfaces 3t and 3t are directed to the outer peripheral side.
The hard stiffener 21 in which the soft stiffener 22 is previously provided on the outer peripheral side has a left and right tapered surface 21t corresponding to a convex line formed by an outer peripheral side peripheral surface 2o on the outer peripheral side of the bead member 1 and a left and right tapered surface on the inner peripheral surface. , 21t are formed, and the hard stiffener 21 and the soft stiffener 22 are wound by fitting the concave groove 21v of the hard stiffener 21 to the outer peripheral ridge of the bead member 1.

Therefore, the tapered surfaces 3t, 3t of the left and right side portions 3s, 3s of the hard rubber member 3 of the bead member 1 and the left and right tapered surfaces 21t, 21t of the corresponding hard stiffener 21 are in contact with each other, and are in close contact with the bead member 1. 21 and 22 are stably held at predetermined relative positions.
Thus, the bead assembly 20 is formed by vulcanization molding in a state where the hard stiffener 21 and the soft stiffener 22 are wound and held around the outer periphery of the bead member 1 (see FIG. 7).

  As shown in FIG. 7, the hard rubber member 3 of the bead member 1 and the hard stiffener 21 are vulcanized and bonded, and the bead assembly 20 surrounds the bead core 2 with hard rubber, and the soft stiffener 21 is surrounded by the outer periphery of the hard stiffener 21. 22 extends continuously.

  The tire includes a pair of bead portions that are fitted to the rim of the wheel, a tread portion that is in contact with the road surface, and a pair of sidewall portions that extend from each bead portion outward in the radial direction of the tire and are continuous with the tread portion. The bead assembly 20 is used for the bead portion.

In FIG. 8, the fragmentary sectional view of the pneumatic tire 30 is shown.
The toroidal carcass 31 passes through the tread portion and the side wall portion and wraps around the bead member 1 so that the periphery of the bead assembly 20 is folded from the inside to the outside and is attached to the soft stiffener 22 of the bead assembly 20. ing.
An inner liner 32 is lined on the inner side of the carcass 31, and a chafer 33 is wound around a portion of the bead portion of the carcass 31 where the rim that wraps around the bead member 1 is fitted. It is pasted.

  As described above, since the bead core 1 has no variation in the position of the bead core 2 in the bead member 1, the position of the bead core 2 in the pneumatic tire 30 can be easily set to a stable and appropriate position, such as uniformity. The performance of the tire can be improved.

  Further, since the hard rubber member 3 having a large elastic modulus is coated on the inner peripheral surface of the bead core 2 and press-molded, the carcass 31 and the chafer 33 that are folded back so as to be wound around the bead member 1 can be stably provided. It can hold | maintain and the position of the bead core 2 in the pneumatic tire 30 can be firmly maintained in the more stable appropriate position.

Therefore, bead durability is also improved.
Even if the position of the bead core 2 in the pneumatic tire 30 is displaced by an external force, the bead core 2 touches the carcass 31 and is damaged because the hard rubber member 3 is coated on the inner peripheral surface of the bead core 2. Never give.
Further, the gauge of the chafer 33 between the rim and the bead member 1 in the bead portion fitted to the rim of the wheel of the pneumatic tire 30 is equally stabilized over the entire circumference.

DESCRIPTION OF SYMBOLS 1 ... Bead member, 1 '... Bead member structure, 2 ... Bead core, 2o ... Outer peripheral side peripheral surface, 2i ... Inner peripheral side peripheral surface, 2s ... Side surface side peripheral surface, 3 ... Hard rubber member, 3i ... Inner peripheral part 3s ... side, 3t ... tapered surface,
DESCRIPTION OF SYMBOLS 10 ... Press machine, 11 ... Outer peripheral type, 11a ... Outer peripheral type surface, 12 ... Inner peripheral type, 12a ... Inner peripheral type surface, 13 ... Left side type, 13a ... Left type surface, 14 ... Right side type, 14a ... Right type surface ,
20 ... bead assembly, 21 ... hard stiffener, 21v ... concave, 21t ... tapered surface, 22 ... soft stiffener,
30 ... Pneumatic tires, 31 ... Carcass, 32 ... Innerina, 33 ... Chefa, 34 ... Sidewall.

Claims (8)

A rubber coating step of forming a bead member structure by covering an annular bead core with a rubber member except for a part of the peripheral surface;
A pressing step of forming the bead member having a predetermined shape by pressing the bead member structure in the center direction of the cross section of the bead member structure;
A method for producing a bead member, comprising:   2. The bead member manufacturing method according to claim 1, wherein, in the rubber coating step, at least the peripheral surface on the inner peripheral side except the peripheral surface on the outer peripheral side of the bead core is covered with a hard rubber member having a large elastic modulus.   3. The bead according to claim 2, wherein the rubber covering step covers the peripheral surface on both side surfaces continuous with the peripheral surface on the inner peripheral side together with the peripheral surface on the inner peripheral side of the bead core with the hard rubber member. Member manufacturing method. The bead core has a rectangular cross section;
4. A tapered surface is formed by gradually decreasing the thickness of both side portions of the hard rubber member covering the peripheral surfaces on both side surfaces of the bead core from the inner peripheral side toward the outer peripheral side. The bead member manufacturing method as described.   A bead member, characterized in that an annular bead core is covered with a rubber member except for a part of the peripheral surface and molded into a predetermined shape.   6. The bead member according to claim 5, wherein at least a peripheral surface on the inner peripheral side except the peripheral surface on the outer peripheral side of the bead core is covered with a hard rubber member having a large elastic modulus.   The bead member according to claim 6, wherein a peripheral surface on both side surfaces continuous with an inner peripheral surface along with an inner peripheral surface of the bead core is covered with the hard rubber member. The bead core has a rectangular cross section,
8. The bead according to claim 7, wherein both side portions of the hard rubber member covering the peripheral surfaces on both side surfaces of the bead core are formed with tapered surfaces by gradually decreasing the thickness toward the outer peripheral surface side. Element.

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