JP2010242279A - Circular coaxial twisted bead cord, method for producing the same, and tire for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circular coaxial twisted bead cord which can ensure a strength and can be simultaneously lightened, to provide a method for producing the same, and to provide a tire for a vehicle. <P>SOLUTION: This circular coaxial twisted bead cord is configured such that by helically curling a plurality of side wires 12 around a core material 21, untwisting the twisted raw cord 22, and then helically winding one side wire 12 of the untwisted side wires 12 on the circularly formed circular core a plurality of times to form a sheath layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an annular concentric stranded bead cord embedded in a bead portion of a pneumatic tire, a manufacturing method thereof, and a vehicle tire.

  Conventionally, as a method of manufacturing an annular metal cord, for example, as described in Patent Documents 1 and 2, after removing half of the wire constituting the wire rope by untwisting or cutting, a part of the remaining wire is removed. It is known that endless processing is performed by winding around the periphery of the ring.

  The wire rope simple endless processing method described in Patent Document 1 is a wire rope formed by twisting six strands having a length slightly more than twice the inner circumference of the design dimension ring. Prepare. This is separated into two strands of three strands to form a base yarn having an inner circumferential length and a margin slightly longer than the inner circumferential length. Next, by using one of the base yarns composed of the three strands of twisted wires, first, a ring portion that is the basis of the design dimension and a strand portion that extends from the combination portion are formed. In addition, the extending strand portion is wound around the ring portion while being twisted, and endless processing is performed in a state where two base yarns (six strands) are twisted together. Thereafter, the twisted end portion of the base yarn is locked or half-cage-inserted or half-cage-inserted and lock-stop combined processing is performed.

  The endless sling described in Patent Document 2 is manufactured as follows. First, a half of the total number of strands is cut out over the entire length of the wire rope of a predetermined length, and a heart rope of 1/2 of the total length of the wire rope is cut out. The both ends of the remaining heart rope are concentrically butted, and the strand on the side where the heart rope is cut is wound around the cut portion of the strand on which the heart rope is not cut to make a concentric endless. Thereafter, the sleeve is compressed over both ends of the cord and the strand.

Japanese Patent No. 3069996 JP-A-5-132881

  Each of the annular metal cords described in Patent Documents 1 and 2 is a sling hanging tool, and is not assumed to be used in a manner that repeatedly receives a load such as a predetermined bending or tension. These annular metal cords are obtained by temporarily halving the number of wires on the circumference of a wire rope in a cross section and rewinding the remaining length of the remaining wire in the remaining half of the space. For this reason, the contact resistance between adjacent wires is weak. Therefore, for example, when used for reinforcing a bead portion (contact portion with a rim) of an automobile tire, since the rigidity is small, the adhesion with the rim is weak and air leakage is likely to occur.

In addition, since half of the wire rope strands are used, there are a plurality of ends, and if each strand or each strand is connected together using a sleeve, it is not suitable for a tire reinforcing material that requires strength. . In particular, when connecting each strand with a sleeve, the working time increases and the productivity is poor. In addition, since the weight increases and the diameter increases, it is not suitable as a laminated bead cord laminated in a plurality of layers.
Here, even when the strand diameter is increased in order to compensate for the strength decrease due to the connection for each strand, the weight is increased and the weight is reduced.

  Accordingly, an object of the present invention is to provide an annular concentric stranded bead cord, a manufacturing method thereof, and a vehicle tire that can achieve weight reduction while ensuring strength.

The annular concentric stranded bead cord of the present invention that can solve the above-mentioned problem is an untwisted original cord in which a plurality of single strands are twisted around a core material, and an annular core formed in an annular shape, One of the untwisted single strands is spirally wound around a plurality of turns to form a sheath layer.
Thus, when twisted around the core material, only one of the single strands that have been preliminarily wound is wound around the annular core as a side line to form a sheath layer having a uniform helical wave shape. . Therefore, particularly when a tensile force is applied in the annular direction, the lateral contact stress, that is, the shear stress between the annular core and the side lines and between the side lines is reduced, so that the breaking strength can be improved. That is, the amount of the material used can be reduced correspondingly, and the weight can be reduced while securing the strength. And by using for reinforcement | strengthening of the bead site | part of a tire for motor vehicles, adhesiveness with a rim | limb is strong and a bead site | part can be favorably reinforced without malfunctions, such as an air leak.

Moreover, it is preferable that the said annular core consists of a twisted wire which twisted together the some metal strand, and the said single strand is wound in the reverse direction to the twist direction of the metal strand of the said annular core.
Thereby, since a single strand is wound without the drop to the twist of the metal strand which comprises an annular core, the unevenness | corrugation of an outer periphery can be suppressed as much as possible. Moreover, when winding a single strand further around an outer periphery, a single strand can be wound favorable. Moreover, the fluctuation | variation of the winding length of the single strand by the fall of the single strand to the twist of the metal strand of a cyclic | annular core can be suppressed, and a single strand can be wound with uniform winding force.

In addition, a single strand is wound around a ring core in a spiral shape, and a plurality of single strands are twisted around a core material having the same diameter as a cord having one or more sheath layers. When the cord is untwisted, one single strand of the untwisted single strand is spirally wound around the annular metal cord having one or more sheath layers, and the sheath layer It is preferable that
As a result, when twisted around the core material, only one of the single strands that have been laid in advance is used as a side line, so that one or a plurality of layers of the spiral wave shape is a uniform sheath layer. By using it for reinforcing the bead part of an automobile tire, the adhesion to the rim is strong, and the bead part can be reinforced well without problems such as air leakage.

Moreover, it is preferable that the diameter type | mold rate of the said single strand in the cyclic | annular concentric twist bead cord after the said sheath layer is formed is 20% or more and 108% or less.
In this way, the diameter utilization rate of the single strand wound around the annular core is 20% or more and 108% or less, so that the strength utilization rate of the single strand can be improved. As a result, there is no need to expect an excessive safety factor when using it as a reinforcing material for tires, and strength can be ensured even if the diameter of the annular core and the single element wire is reduced, and weight reduction can be achieved. . Even if the diameter die attachment ratio exceeds 100%, rubber penetrates into the gap between the annular core and the side wire, so if the diameter die attachment ratio is 108% or less, the strength utilization rate of the annular core and the single strand is greatly reduced. There is nothing.
More preferably, the diameter ratio of the single strand is 64% or more and 102% or less.
In addition, the diameter attaching ratio is the diameter of the annular concentric stranded bead cord (the sectional diameter (wire diameter) of the annular core + sheath layer) is D, and the wave height (including the self diameter) of the formed single strand is H. Then, it is expressed by “Diameter mold attachment ratio (%) = H / D × 100”.

Moreover, it is preferable that the winding direction of the said single strand is made into the reverse direction in the sheath layer adjacent to radial direction.
Thereby, since the winding direction of the single strands in the sheath layer adjacent in the radial direction is the reverse direction, the unevenness in the surface layer can be suppressed as much as possible, and other sheath layers can be interposed between the single strands. It is possible to eliminate the problem that the single strand enters and the layer collapses.

Further, the cyclic core is comprised of 0.08 mass% or more and 0.27 mass% or less of carbon (C), 0.30 mass% or more and 2.00 mass% or less of silicon (Si), 0.50 mass% or more and 2 or more. Containing 0.000 mass% or less manganese (Mn) and 0.20 mass% or more and 2.00 mass% or less chromium (Cr), and aluminum (Al), niobium (Nb), titanium (Ti), and vanadium ( V) is contained from at least one kind in the range of 0.001% by mass or more and 0.10% by mass or less, and the balance is formed from alloy steel composed of iron (Fe) and impurities inevitably mixed in. It is preferable.
Thereby, the ductile fall inhibitory effect in the welding part of the both ends at the time of setting it as cyclic | annular form can be acquired.

Moreover, it is preferable that the said cyclic | annular core is formed from the carbon steel containing 0.28 mass% or more of carbon (C).
Thereby, since the weldability of a junction part becomes high, the intensity | strength required as an annular core is securable.

Moreover, the manufacturing method of the annular concentric stranded bead cord of the present invention that can solve the above-described problems is formed by untwisting an original cord in which a plurality of single strands are twisted around a core material, and is formed in an annular shape. A sheath layer is formed by winding a single strand of untwisted single strands in a spiral manner around the annular core.
In this way, when twisted around the core material, only one of the single strands that have been previously laid is wound around the annular core as a side line to form a sheath layer having a uniform helical wave shape. Therefore, particularly when a tensile force is applied in the annular direction, the lateral contact stress, that is, the shear stress between the annular core and the side lines and between the side lines is reduced, so that the breaking strength can be improved. That is, the amount of the material used can be reduced correspondingly, and the weight can be reduced while securing the strength. And by using for reinforcement | strengthening of the bead site | part of a tire for motor vehicles, adhesiveness with a rim | limb is strong and a bead site | part can be favorably reinforced without malfunctions, such as an air leak. Moreover, the connection place of a single strand can be made into one place.

Further, when forming the sheath layer by winding the single element wire around the annular core a plurality of times, the single strand is bent to a diameter not less than 0.55 times and not more than 2.0 times the center diameter of the annular core to be formed. It is preferable. It is efficient to perform this bending process before untwisting the original cord.
Thereby, the cyclic | annular uniform formation of an annular concentric twist bead cord can be facilitated, and productivity can be improved.

Moreover, it is preferable to use a twisted wire obtained by twisting a plurality of metal strands as the annular core, and to wind the single strand in a direction opposite to the twisting direction of the metal strands of the annular core.
Thereby, a single strand can be wound without the metal strand which comprises a cyclic | annular core falling into the twist line, and the unevenness | corrugation of an outer periphery can be suppressed as much as possible. Furthermore, when winding a single strand around an outer periphery, a single strand can be wound favorable. Moreover, the fluctuation | variation of the winding length of the single strand by the fall of the single strand to the twist of the metal strand of a cyclic | annular core can be suppressed, and a single strand can be wound with uniform winding force.

In addition, a single strand is wound around a ring core in a spiral shape, and a plurality of single strands are twisted around a core material having the same diameter as a cord having one or more sheath layers. The cord is untwisted, and one single strand of the untwisted single strand is spirally wound around the annular metal cord having one or more sheath layers to form a sheath layer. It is preferable.
As a result, when twisted around the core material, only one of the single strands that are preliminarily brazed is wound around an annular metal cord having one or more sheath layers as a side line to form a spiral wave shape. Forms a uniform sheath layer. Therefore, particularly when a tensile force is applied in the annular direction, the lateral contact stress, that is, the shear stress between the annular core and the side lines and between the side lines is reduced, so that the breaking strength can be improved. That is, the amount of the material used can be reduced correspondingly, and the weight can be reduced while securing the strength. And by using for reinforcement | strengthening of the bead site | part of a tire for motor vehicles, adhesiveness with a rim | limb is strong and a bead site | part can be favorably reinforced without malfunctions, such as an air leak.

Moreover, it is preferable that the winding direction of the said single strand in the sheath layer adjacent to radial direction is made into a reverse direction.
As a result, the winding direction of the single strands in the sheath layer adjacent in the radial direction is reversed, so that unevenness in the surface layer can be suppressed as much as possible, and the single strands of other sheath layers can be interposed between the single strands. It is possible to eliminate the problem that the line enters and the layer collapses.

The vehicle tire according to the present invention is characterized in that the annular concentric stranded bead cord is embedded.
As described above, since the annular concentric stranded bead cord that is reduced in weight while ensuring good manufacturability and handleability is used, it is possible to realize an eco-tire that is excellent in manufacturability and lightened.

  ADVANTAGE OF THE INVENTION According to this invention, the cyclic | annular concentric twist bead cord which can achieve weight reduction, ensuring its intensity | strength, its manufacturing method, and a vehicle tire can be provided.

It is sectional drawing of the tire for vehicles. (A) is a general view of a bead cord, (b) is a perspective view showing a portion of a bead cord. It is a perspective view of the metal cord explaining the squeezing process of a side line. (A) is a side view of the brazing apparatus when making a wire into an annular shape, and (b) is a front view thereof. It is a top view which shows the state which started winding the side line around the annular core. It is a top view which shows the state in the middle of winding which shows the state which wound the side line around the annular core once. It is a perspective view of the cyclic | annular concentric twist bead cord which has the cyclic | annular core which consists of a strand wire. It is a perspective view of an annular concentric stranded bead cord having a plurality of sheath layers. It is a perspective view of the metal cord explaining the manufacturing method of the annular concentric twist bead cord which has a plurality of layers of sheath layers. It is a figure which shows the jig | tool used for the tension test of a cyclic | annular bead cord, (a) is the side view, (b) is the sectional drawing.

Embodiments of an annular concentric stranded bead cord and a vehicle tire using the same according to the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view of a vehicle tire, FIG. 2 (a) is an overall view of a bead cord, and FIG. 2 (b) is a perspective view showing a bead cord portion.

As shown in FIG. 1, a vehicle tire 1 is a pneumatic tire for a passenger car, and bead portions 3 on both sides through which a bead cord (annular concentric stranded bead cord) 2 passes and a radial direction from each bead portion 3. A sidewall portion 4 extending outward and a tread portion 5 connecting between upper ends thereof are provided.
Further, a carcass 6 is bridged between the bead portions 3, and a belt layer 7 is wound in the circumferential direction outside the carcass 6 and inside the tread portion 5.

  As shown in FIGS. 2 (a) and 2 (b), the bead cord 2 passed through the bead portion 3 of the vehicle tire 1 is a single side wire (single strand) that is preliminarily spiraled. 12 is prepared, and the side line 12 is wound around the annular core 11 a plurality of times (six rounds in this example) to form the sheath layer 13. The side line 12 is passed from the outside of the ring of the annular core 11 into the ring, and is again passed from the outside of the ring into the ring, so that the side line 12 is spirally wound around the annular core 11 at a predetermined winding pitch. Yes. In addition, in this example, the case where it has the sheath layer 13 of one layer is illustrated.

  The annular core 11 is formed by forming one wire that is curved in advance into an annular shape, and joining both end faces thereof by welding. In this case, it can be simply joined without causing an increase in the diameter of the joining portion of the wires of the annular core 11.

  The annular core 11 is made of an alloy steel wire, and the material thereof is 0.08 to 0.27% by mass of carbon (C), 0.30 to 2.00% by mass of silicon (Si), 0.50. -2.00 mass% manganese (Mn) and 0.20-2.00 mass% chromium (Cr), and aluminum (Al), niobium (Nb), titanium (Ti) and vanadium (V) Is an alloy steel composed of at least one kind in the range of 0.001 to 0.100% by mass, the balance being iron (Fe) and impurities inevitably mixed. If it is such a composition, the ductile fall suppression effect in the welding part of both ends at the time of forming an alloy steel wire annularly and making it the cyclic | annular core 11 can be acquired.

  Moreover, the cyclic | annular core 11 may be formed with the medium carbon steel wire which contains carbon (C) 0.28-0.56 mass%. Even if a wire made of such a material is used, the weldability of the joint is improved, so that the strength required for the annular core 11 can be ensured. The surface of the annular core 11 may be subjected to a copper alloy (for example, brass) or zinc plating treatment.

  The side wire 12 is made of, for example, a high carbon steel wire containing 0.7% by mass or more of carbon (C). The surface of the side wire 12 may be subjected to a copper alloy (for example, brass) or zinc plating treatment.

  The diameter (wire diameter) of the wire constituting the annular core 11 is preferably equal to or larger than the diameter (wire diameter) of the wire of the side wire 12. For example, the diameter of the wire of the annular core 11 is 1.5 mm. The diameter of the wire is 1.4 mm.

Next, a method for manufacturing the above annular concentric stranded bead cord will be described.
(Pretreatment process)
First, as a pretreatment process, the side wire 12 and the annular core 11 are coiled.

(1) Side wire kneading process As shown in FIG. 3, a plurality of (6 in this example) side wires 12 are twisted on a core material 21 having the same diameter as the annular core 11 to form an original cord 22. When the original cord 22 is formed, the original cord 22 is untwisted to separate the side wires 12. In addition, before twisting to the core material 21, the side wire | line 12 is good to pass an appropriate | suitable type | mold (diameter type | mold rate is 93 +/- 5%) by letting a knotting pin etc. pass.

(2) Coilization process of annular core FIG. 4A is a side view of a kneading device when a wire is annular, and FIG. 4B is a front view thereof. As shown in FIGS. 4 (a) and 4 (b), the brazing device 30 includes a pair of free rollers 32a and 32b, which are first rollers rotatably provided at a predetermined interval on a base 31, and The drive roller 33 is one second roller that can freely approach and separate (in the direction of arrow A in FIG. 4) with respect to the pair of free rollers 32a and 32b. The drive roller 33 is positioned on a vertical bisector L of a line segment connecting the centers of the pair of free rollers 32a and 32b, and the distance between the pair of free rollers 32a and 32b is adjusted by the moving unit 34. Yes. The driving roller 33 is driven to rotate by driving means (not shown).

  As shown in FIG. 4B, each of the rollers 32 a, 32 b, 33 is provided with a groove 35 having an arcuate cross section corresponding to the outer diameter of the wire 11 a serving as the annular core 11. Further, it is desirable to provide a free roller 36 that supports and guides the wire 11a fed to each of the rollers 32a, 32b, and 33.

In order to coil the wire 11a by the kneading device 30, first, the driving roller 33 is separated from the pair of free rollers 32a and 32b, and the wire is interposed between the driving roller 33 and the pair of free rollers 32a and 32b. 11a is inserted, and the driving roller 33 is pressed against the pair of free rollers 32a and 32b to sandwich the tip end portion of the wire 11a between the driving roller 33 and the free rollers 32a and 32b. Then, the drive roller 33 is rotationally driven to pass the wire 11a and bend in an arc shape. Thereby, the wire 11a before making the annular core 11 is curved.
Further, the original cord 22 can be coiled by the above-described kneading device 30 before untwisting. By winding the original cord 22 into a coil, the side wire 12 may be curved to a diameter not less than 0.55 times and not more than 2.0 times the center diameter of the annular core 11. Here, the center diameter of the annular core 11 is a diameter from the center of the ring to the center axis of the wire 11 a constituting the annular core 11.

(3) Joining process The both end surfaces of the wire 11 a that have been brazed as described above are brought into contact with each other and welded together to form the annular core 11. At this time, since the wire 11a is curved, both end surfaces can be easily butted and welded.

(Winding process)
Next, a case where an annular concentric stranded bead cord is manufactured by winding the side wire 12 around the annular core 11 will be described.
FIG. 5 is a plan view showing a state in which the side wire 12 is started to be wound around the annular core 11, and FIG. 6 is a plan view showing a state in the middle of winding showing a state in which the side wire 12 is wound around the annular core 11 once.
First, as shown in FIG. 5, the start end 12 a of one side wire 12 obtained by untwisting the original cord 22 by the above-described kneading process is not added with the same material as the rubber of the vehicle tire 1. The annular core 11 is temporarily fixed with a sulfur rubber sheet. At this time, the side line 12 has both the spiral wave shape formed by the molding performed before forming the original cord 22 and the curved shape obtained by coiling the original cord 22.

Then, for example, by hand winding, the side wire 12 is wound around the annular core 11 so that the annular core 11 is placed inside the spiral wave shape of the side wire 12. At this time, since the side line 12 is curved to a diameter not less than 0.55 times and not more than 2.0 times the center diameter of the annular core 11, the winding operation along the annular direction of the annular core 11 can be performed smoothly. . Therefore, it is possible to facilitate the uniform formation of the annular concentric stranded bead cord, and the productivity can be improved.
FIG. 6 shows a state in which the side wire 12 is wound around the annular core 11 by one turn, and the side wire 12 is continuously wound around the annular core 11 five times. Then, after winding continuously for a predetermined number of times (six rounds in this embodiment), the starting end temporarily fixed to the annular core 11 is removed, and the starting end and the end are connected and fixed by a metal sleeve.

In this way, the bead cord 2 having the sheath layer 13 in which the side wires 12 are spirally wound around the annular core 11 is obtained.
Note that the start end and the end may be connected and fixed by, for example, a sleeve made of brass or a lightweight material (plastic, fluororesin, etc.).

  As described above, when the bead cord 2 of the present embodiment is twisted around the core material 21, only one of the side wires 12 that are preliminarily attached is wound around the annular core 11 to form a spiral wave shape. A uniform sheath layer 13 is formed. Therefore, especially when a tensile force is applied in the annular direction of the bead cord 2, the lateral contact stress, that is, the shear stress between the annular core 11 and the side lines 12 and between the side lines 12 is reduced, so that the breaking strength is improved. be able to. That is, the amount of the material used can be reduced correspondingly, and the weight can be reduced while securing the strength. And by using for reinforcement of the bead part of a tire for vehicles, adhesion nature with a rim is strong and it can reinforce a bead part favorably without problems, such as air leakage. Moreover, the connection location of the side line 12 can be made into one location.

  Moreover, since the side line 12 is curved in advance to a diameter not smaller than 0.55 times and not larger than 2.0 times the center diameter of the annular core 11 to be formed, it is possible to facilitate the formation of the annular shape of the bead cord 2. , Can increase productivity.

Further, as shown in FIG. 7, as the annular core 11, a stranded wire obtained by twisting a plurality of metal strands 11 b may be used. In this case, the side wire 12 wound around the annular core 11 is formed of the annular core 11. It is preferable to wind in the direction opposite to the twisting direction of the metal strand 11b.
If it does in this way, since the side wire 12 is wound without the metal strand 11b which comprises the annular core 11 falling into the twist line, the unevenness | corrugation of an outer periphery can be suppressed as much as possible. Further, when the side wire 12 is further wound around the outer periphery, the side wire 12 can be wound well. Moreover, the fluctuation | variation of the winding length of the side wire 12 by the fall of the side wire 12 to the twist of the metal strand 11b of the annular core 11 can be suppressed, and the side wire 12 can be wound with a uniform winding force.

  In the above embodiment, the side wire 12 is subjected to the squeezing process using the core material 21 different from the wire 11 a constituting the annular core 11, but the wire 11 a constituting the annular core 11 may be used as the core material 21. good.

  When such a bead cord 2 is embedded in the vehicle tire 1, a rubber sheet to which a vulcanization accelerator is added is attached to the bead cord 2 to obtain a bead cord with rubber. Then, a bead cord with rubber is incorporated into the bead portion 3 of the vehicle tire 1 and is put into a tire molding machine as an unvulcanized rubber composite having a tire shape. Thereafter, the molding die is pressurized and vulcanized to complete the tire. When the side wire 12 is plated, the sulfur component contained in the rubber sheet reacts with and adheres to the plating of the side wire 12.

  In addition, the bead cord 2 and the rubber sheet may be bonded to each other by a metal rubber adhesive suitable for bonding metal and rubber without adding a vulcanization accelerator to the rubber sheet. This is effective in the case where the rubber sheet is not applied, and the rubber sheet can be securely fixed to the side wire 12. For example, Chemlock (registered trademark, manufactured by Road Far East, Inc.) can be used as an adhesive for metal rubber.

  Since the vehicle tire 1 manufactured in this way uses the above-described bead cord 2 that is lightened while ensuring strength, it is easy to manufacture, can be reduced in weight, and is an eco-friendly eco-tire. can do.

In the above embodiment, the single sheath layer 13 is provided around the annular core 11, but a plurality of sheath layers 13 may be provided.
And in the cyclic | annular concentric twist bead cord 2 which has the sheath layer 13 of two or more layers, the winding direction of the side line 12 in the sheath layer 13 adjacent to radial direction is made into a reverse direction.

  FIG. 8 shows an annular concentric stranded bead cord 2 having a two-layer sheath layer 13, which has an annular metal cord 61 having a first sheath layer 13 and a side wire 12 spirally formed. A plurality of turns (12 turns in this example) are wound to form a second sheath layer 13. The side line 12 constituting the second sheath layer 13 is one of a plurality of side lines 12 wound around a cord having the first sheath layer 13.

  When the annular concentric stranded bead cord 2 having a plurality of sheath layers 13 is manufactured, as shown in FIG. 9, one or more sheath layers are formed by spirally winding the side wires 12 around the annular core 11. An original cord 22 is formed by twisting a plurality of side wires 12 around a core material 21 having the same diameter as the metal cord having 13. Then, the original cord 22 is untwisted, and one side wire 12 of the untwisted side wires 12 is spirally wound around the annular metal cord 61 having one or more layers of the sheath layer 13 to make a sheath. Layer 13 is formed. At this time, the winding direction of the side wires 12 in the sheath layer 13 that is adjacent in the radial direction is the reverse direction.

  In this way, when twisted around the core material 21, only one of the side wires 12 that are preliminarily attached is wound around an annular metal cord 61 having one or more sheath layers 13. Thus, the sheath layer 13 has a uniform spiral wave shape. Therefore, especially when a tensile force is applied in the annular direction of the bead cord 2, the lateral contact stress, that is, the shear stress between the annular core 11 and the side lines 12 and between the side lines 12 is reduced, so that the breaking strength is improved. be able to. That is, the amount of the material used can be reduced correspondingly, and the weight can be reduced while securing the strength. And by using for reinforcement of the bead part of a tire for vehicles, adhesion nature with a rim is strong and it can reinforce a bead part favorably without problems, such as air leakage.

  Moreover, since the winding direction of the side line 12 in the sheath layer 13 adjacent to the radial direction is the reverse direction, the unevenness in the surface layer can be suppressed as much as possible, and the side line of the other sheath layer 13 is between the side lines 12. The trouble that 12 enters and the layer collapses can be eliminated.

Further, in any of the bead cord 2 having the above-described one sheath layer 13 and the bead cord 2 having the plurality of sheath layers 13, the ratio of the diameter type of the side line 12 in the bead cord 2 is 20% or more and 108%. The following is preferable.
If the diameter-type ratio of the side wire 12 that has become the sheath layer 13 exceeds 108%, a large shearing stress is generated between the annular core 11 and the strength utilization factor is reduced. In addition, if the ratio of the diameter type of the side wire 12 that becomes the sheath layer 13 is less than 20%, the difference in elongation between the annular core 11 and the sheath layer 13 becomes large, and the uniform load distribution is lost, and the strength is used. The rate will be lowered.

The strength utilization factor of the side line 12 can be improved by setting the diameter-type attachment ratio of the side line 12 to 20% or more and 108% or less. As a result, it is not necessary to expect an excessive safety factor when used as a tire reinforcing material, and even if the diameters of the annular core 11 and the side wires 12 are reduced, the strength can be ensured and the weight can be reduced. . Even if the diameter mold attachment ratio exceeds 100%, rubber penetrates into the gap between the annular core 11 and the side wire 12, so that if the diameter mold attachment ratio is 108% or less, the strength utilization ratio of the annular core 11 and the side wire 12 is large. There is no decline.
Further, the diameter type attachment ratio of the side line 12 is 64% or more and 102% or less.

(First embodiment)
A bead cord having a single sheath layer was produced under various conditions, and evaluation of the side-by-side diameter type attachment rate, the bead cord strength utilization rate, the weight reduction rate, and the side-line spiral winding property was performed.

(1) Raw metal cord to be used (1 × 1.8 + (7) × 1.4 metal cord)
(1-1) Production of core material Pick a 5.5 mm diameter hard steel wire containing 0.51% by mass of carbon (C) and draw it to a diameter of 1.8 mm through a wire drawing process. A core material is produced. And in order to supply this core material to a stranding machine, only a required amount is wound up on a reel.
(1-2) Production of side wire Pickle a 4.5 mm diameter hard steel wire containing 0.82% by mass of carbon (C), apply copper and zinc plating, and produce a brass plating intermediate wire by diffusion. . Then, a 1.4 mm diameter side wire is produced through a wire drawing process. In order to supply the side wire to the twisting machine, only a necessary amount is wound on 7 reels.
(1-3) Production of metal cord Using a tubular type twisted wire machine with a preform that can be twisted without including a core material, seven side wires around the core material at a twist pitch of 153.8 mm Are twisted by S twist to produce a 1 + 7 metal cord.
In addition, the number of rotations of the twisting machine is adjusted to 600 (rpm), the diameter forming rate of the side wires is adjusted to an average of 93%, and the coil diameter adjustment after twisting is 0.75D1 (D1: layer core of the bead cord to be manufactured) Diameter).
(1-4) Untwisting the metal cord Prepare a metal cord that is approximately 23 times ((D1) π × 7 + α) the annular diameter (layer core diameter: D1) of the bead cord to be manufactured including the terminal portion (α). , Untwisting over the entire length and separating into a core material and seven side wires.

(2) Annular concentric stranded bead cord to be produced An annular core is produced by making a core material separated from a metal cord into an annulus so that the layer core diameter D1 = 440.7 mm, and abutting and welding both ends.
Around the annular core, one of the seven side lines separated from the metal cord is used, and the first sheath layer is formed by spirally winding the winding core at a winding pitch of 153.8 mm. At the start and end of the side wire, the extra length is cut and inserted into a brass sleeve.

(3) Evaluation test Table 1 shows the results.

  The evaluation items in Table 1 were evaluated by the following method.

(3-1) Side wire diameter mold rate (%)
A sample having a length of 15 cm is cut out from an annular concentric stranded bead cord. At that time, if the annular bead cord is cut without any treatment, the side wires are easily untwisted and loosened. Therefore, the vicinity of the cut portion is previously bound with a bind wire or the like and then cut. The curvature of the cut sample (bead cord annular curvature) is slightly corrected so as to be linear, and then the diameter D of the straight portion is measured by a cord diameter measuring micrometer.

Using the same cut sample, the bound binding wire is removed, and the six side wires are removed from the annular core in an unloaded state. The six side lines are cut into lengths that can measure the wave height for three pitches if necessary, and the number of samples n = 3 (that is, the height of each wave of three pitches) on one side line by a universal projector. The average value is taken as the wave height of the one side line. The remaining five side lines are measured in the same manner, and the average value of the wave heights of the six side lines is defined as the wave height H of the side lines in the bead cord.
Using the diameter D and the wave height H obtained in this way, the diameter mold attachment ratio is calculated by the equation “diameter mold attachment ratio (%) = H / D × 100”.

(3-2) Strength utilization rate of bead cord (%)
For the annular cores and side wires used in a total of 14 cases, a tensile test is performed in advance using a tensile tester with the number of samples n = 3, and an average cutting load is calculated. The calculation formula is “cutting load W ₀ (kN) at the strand = average cutting load of the strand of the annular core + average cutting load of the side line × 6”.
The annular bead cord, in advance using the jig 60 of the annular bead cord shown in FIG. 10, performs a tensile test with a sample number n = 2, and calculates the average cutting load W _{1 (kN)} at the bead cord.

Here, a tensile test method using the annular bead cord jig 60 shown in FIG. 10 will be described. The jig 60 for an annular bead cord holds the bead cord 2 on a pair of grooved semi-disc shaped holding members 61, and connects each traction member 62 connected to each holding member 61 via a bolt 64. These are each pulled by the chuck 63 in the direction of separation (vertical direction in FIG. 10). For example, the position of the lower chuck 63 is fixed, and the upper chuck 63 is pulled upward. By measuring the tensile load of the chuck 63, the cutting load of the bead cord 2 can be measured.
From the cutting loads W ₀ and W ₁ obtained as described above, the strength utilization rate η (%) is calculated by the formula “strength utilization rate η (%) = W ₁ / W ₀ × 100”.

(3-3) Bead cord weight reduction rate (%)
Since the wire diameter can be reduced by an amount corresponding to the increase in the strength utilization factor η of each example on the basis of the strength utilization factor η of Comparative Example 1 twisted with a diameter molding rate of 4%, the expression “weight reduction rate ( %) = (Strength utilization ratio η of each example−strength utilization ratio η of comparative example 1) / strength utilization ratio η × 100 of comparative example 1 ”. In Comparative Example 1 serving as a reference, the weight reduction rate is 0% from the above equation.

(3-4) Surface state of side line The change of the spiral winding property of the side line due to the difference in the diameter molding rate is observed.
In Table 1, the evaluations of spiral wrapping properties ◯, Δ, × indicate the following.
◯: When the side line is wound around the annular core along the helical pitch, it is naturally wound.
(Triangle | delta): The state which requires pressing of the side line to an annular core when winding a side line along a spiral pitch with respect to an annular core.
X: When winding a side line around the annular core along the helical pitch, it is not possible to wind the side line in a short time even if the side line is pressed against the annular core.

  As can be seen from Table 1, in Comparative Example 1, the diameter shaping rate of the side line was as small as 4%, and thus the strength utilization factor of the bead cord was 76.0%. In Comparative Example 2, the bead cord of Comparative Example 1 is heated to the vulcanization temperature (150 ° C.) of rubber when embedding as a bead cord of a vehicle tire. The diameter molding rate of the bead cord was as small as 10%, and thus the strength utilization factor of the bead cord was 77.2%. For this reason, in Comparative Examples 1 and 2, when the side line is wound around the annular core along the spiral pitch, the spiral winding property can be wound in a short time even if the side line is pressed against the annular core. It was not possible (evaluation x).

  On the other hand, in Examples 1-11 other than the comparative examples 1 and 2, since the diameter shaping | molding rate is as high as 20% or more, the intensity | strength utilization factor is also rising in connection with it. For this reason, in Examples 1 to 11, when the side line is wound around the annular core along the helical pitch, the spiral winding property is in a state where the side line needs to be pressed against the annular core (evaluation Δ), or in the annular core. On the other hand, when the side line was wound along the helical pitch, it was in a state of being naturally wound (evaluation ○). However, in Example 11 in which the diameter shaping ratio was 108% exceeding 105%, the winding property was good, but the outer periphery of the sheath layer was uneven. Although the strength utilization rate of the bead cord is as low as 78.5%, this is a result of the cord alone, and it is considered that the strength utilization rate is surely improved if measured with a practical rubber covered state.

(Second embodiment)
Bead cords having two sheath layers were produced under various conditions, and evaluations of the diameter-type attachment ratio of the side wires, the strength utilization rate of the bead cords, the weight reduction rate, and the spiral winding properties of the side wires were performed.

(1) Raw metal cord to be used (1 × 1.8 + (7 + 13) × 1.4 metal cord)
(1-1) Production of core material The bead cord produced in the first example is used as a temporary core material.
(1-2) Production of side wire Pickle a 4.5 mm diameter hard steel wire containing 0.82% by mass of carbon (C), apply copper and zinc plating, and produce a brass plating intermediate wire by diffusion. . Then, a 1.4 mm diameter side wire is produced through a wire drawing process. In order to supply the side wire to the twisting machine, the necessary amount is wound on 13 reels.
(1-3) Production of metal cords 13 wires around the temporary core material at a twist pitch of 173.1 mm using a preformed tubular twisted wire machine that can be twisted 13 wires without including the temporary core material These side wires are twisted by Z-twisting to produce a metal cord having a 1 + 7 + 13 structure.
In addition, the number of rotations of the twisting machine is adjusted to 600 (rpm), the diameter forming rate of the side wires is adjusted to an average of 93%, and the coil diameter adjustment after twisting is 0.75D1 (D1: layer core of the bead cord to be manufactured) Diameter).
(1-4) Untwisting of the metal cord Prepare a metal cord that is approximately 42 times ((D1) π × 13 + α) the annular diameter (layer core diameter: D1) of the bead cord to be manufactured including the terminal (α). , Untwisting over the entire length and separating into one core material, seven side wires and thirteen side wires.

(2) Annular concentric stranded bead cord to be produced An annular core is produced by making a core material separated from a metal cord into an annulus so that the layer core diameter D1 = 440.7 mm, and abutting and welding both ends.
Around the annular core, one of the seven side lines separated from the metal cord is used, and the first sheath layer is formed by spirally winding the winding core at a winding pitch of 153.8 mm. At the start and end of the side wire, the extra length is cut and inserted into a brass sleeve.
Subsequently, one of the 13 side wires separated from the metal cord is used around the first layer, and the second sheath layer is wound around the first layer by spirally winding 13 turns at a winding pitch of 173.1 mm. Form. At the start and end of the side wire, the extra length is cut and inserted into a brass sleeve.

(3) Evaluation test Table 2 shows the results.

  The evaluation items in Table 2 were evaluated by the following method.

(3-1) Side wire diameter mold rate (%)
A sample having a length of 15 cm is cut out from an annular concentric stranded bead cord. At that time, if the annular bead cord is cut without any treatment, the side wires are easily untwisted and loosened. Therefore, the vicinity of the cut portion is previously bound with a bind wire or the like and then cut. The curvature of the cut sample (bead cord annular curvature) is slightly corrected so as to be linear, and then the diameter D of the straight portion is measured by a cord diameter measuring micrometer.

Using the same cut sample, the bound binding wire is removed, and the six side wires are removed from the annular core in an unloaded state. The six side lines are cut into lengths that can measure the wave height for three pitches if necessary, and the number of samples n = 3 (that is, the height of each wave of three pitches) on one side line by a universal projector. The average value is taken as the wave height of the one side line. The remaining five side lines are measured in the same manner, and the average value of the wave heights of the six side lines is defined as the wave height H of the side lines in the bead cord.
Using the diameter D and the wave height H obtained in this way, the diameter mold attachment ratio is calculated by the equation “diameter mold attachment ratio (%) = H / D × 100”.

(3-2) Strength utilization rate of bead cord (%)
For the annular cores and side wires used in a total of 14 cases, a tensile test is performed in advance using a tensile tester with the number of samples n = 3, and an average cutting load is calculated. The calculation formula is “cutting load W ₀ (kN) at the strand = average cutting load of the strand of the annular core + average cutting load of the side line × 6”.
For each example of the bead cord wound with raw rubber and pressure vulcanized, a tensile test was performed at n = 2 using the jig 60 described above, and the average cutting load W ₁ (kN) of the bead cord with rubber was measured. Is calculated.
From the cutting loads W ₀ and W ₁ obtained as described above, the strength utilization rate η (%) is calculated by the formula “strength utilization rate η (%) = W ₁ / W ₀ × 100”.

(3-3) Bead cord weight reduction rate (%)
Since the wire diameter can be reduced by the amount of increase in the strength utilization factor η of each example based on the strength utilization factor η of Comparative Example 3 twisted together with a diameter molding rate of 3%, the expression “weight reduction rate ( %) = (Strength utilization ratio η of each example−strength utilization ratio η of comparative example 3) / strength utilization ratio η × 100 of comparative example 3 ”. In Comparative Example 3 serving as a reference, the weight reduction rate is 0% from the above equation.

(3-4) Surface condition of side line The change of the spiral winding property of the side line with respect to the annular temporary core having one sheath layer due to the difference in the diameter molding rate is observed.
In Table 2, the evaluations of spiral winding property ○, Δ, × indicate the following.
◯: When the side line is wound around the annular temporary core along the helical pitch, it is naturally wound.
Δ: When the side line is wound around the annular temporary core along the helical pitch, the side line needs to be pressed against the annular core.
X: When winding the side line around the annular temporary core along the helical pitch, it is impossible to wind the side line in a short time even if the side line is pressed against the annular core.

  As can be seen from Table 2, in Comparative Example 3, the diameter shaping rate of the side line was as small as 3%, and thus the strength utilization factor of the bead cord was 76.4%. In Comparative Example 4, the bead cord of Comparative Example 3 was heated to the vulcanization temperature (150 ° C.) of rubber when embedding as a bead cord of a vehicle tire. The diameter forming rate of the bead cord was as small as 10%, and therefore the strength utilization factor of the bead cord was 77.6%. For this reason, in Comparative Examples 3 and 4, when winding the side line along the spiral pitch with respect to the annular temporary core having one sheath layer, the spiral winding property is devised such as pressing the side line against the annular temporary core. Even in such a case, it was in a state where it could not be wound in a short time (evaluation x).

  On the other hand, in Examples 12 to 19 other than Comparative Examples 3 and 4, since the diameter molding rate is as high as 26% or more, the strength utilization rate is also increased accordingly. For this reason, in Examples 12 to 19, the spiral winding property is determined when the side line of the second layer is wound around the annular temporary core along the spiral pitch (evaluation Δ) or when the side line is pressed. When the side line was wound around the core along the helical pitch, the core was naturally wound (evaluation ○). However, in Example 19 in which the diameter molding rate was 107% exceeding 105%, the winding property was good, but the outer periphery of the second layer was uneven. Although the strength utilization rate of the bead cord is as low as 79.5%, this is a result of the cord alone, and it is considered that the strength utilization rate is surely improved if measured with a practical rubber covered state.

As a result of Example 1 and Example 2, it was found that the side line forming rate of each sheath layer was 90 to 100% with the highest strength utilization rate.
In other words, in this way, if an annular concentric stranded bead cord having a high strength utilization rate is used for a vehicle tire so that the breaking strength is constant, the mass of the tire can be reduced while ensuring sufficient strength. It can be a tire with excellent ecology.

DESCRIPTION OF SYMBOLS 1 ... Vehicle tire, 2 ... Bead cord (annular concentric twist bead cord), 11 ... Cylindrical core, 11b ... Metal element wire, 12 ... Side wire, 13 ... Sheath layer, 21 ... Core material, 22 ... Original cord

Claims (13)

  An original cord in which a plurality of single strands are twisted around a core material is untwisted, and one single strand of the untwisted single strands is in a spiral shape on a ring-shaped annular core An annular concentric stranded bead cord which is wound around a plurality of turns into a sheath layer. The annular concentric stranded bead cord according to claim 1,
The annular core is composed of a stranded wire obtained by twisting a plurality of metal strands, and the single strand is wound in a direction opposite to the twisting direction of the metal strands of the annular core. Core twist bead cord. An annular concentric stranded bead cord according to claim 1 or 2,
An original cord in which a plurality of single strands are twisted around a core material having the same diameter as that of a cord having one or more sheath layers by spirally winding a single strand around an annular core. One single strand of the untwisted single strand is spirally wound around a ring-shaped metal cord having one or more sheath layers and formed into a sheath layer. An annular concentric stranded bead cord characterized by An annular concentric stranded bead cord according to any one of claims 1 to 3,
An annular concentric stranded bead cord, wherein the diameter of the single strand in the annular concentric stranded bead cord after the sheath layer is formed is 20% or more and 108% or less. An annular concentric stranded bead cord according to claim 4,
An annular concentric stranded bead cord, wherein the sheath layer adjacent in the radial direction has a winding direction of the single element wire reversed. An annular concentric stranded bead cord according to any one of claims 1 to 5,
The cyclic core is comprised of 0.08 mass% or more and 0.27 mass% or less of carbon (C), 0.30 mass% or more and 2.00 mass% or less of silicon (Si), 0.50 mass% or more and 2.00 mass% or more. Containing manganese (Mn) of not more than mass% and chromium (Cr) of not less than 0.20 mass% and not more than 2.00 mass%, and aluminum (Al), niobium (Nb), titanium (Ti) and vanadium (V) Each containing at least one kind in the range of 0.001% by mass to 0.10% by mass, and the balance being made of an alloy steel made of iron (Fe) and impurities inevitably mixed in. Characteristic annular concentric stranded bead cord. An annular concentric stranded bead cord according to any one of claims 1 to 5,
The said cyclic | annular core is formed from the carbon steel containing 0.28 mass% or more and 0.56 mass% or less carbon (C), The cyclic | annular concentric twist bead cord characterized by the above-mentioned.   Untwist the original cord in which a plurality of single strands are twisted around the core material, and spirally form one single strand of the untwisted single strands in a ring-shaped annular core A method for producing an annular concentric stranded bead cord, wherein a sheath layer is formed by winding a plurality of turns. A method for producing the annular concentric stranded bead cord according to claim 8,
When forming the sheath layer by wrapping the single strand around the annular core a plurality of times, it is curved to a diameter of 0.55 to 2.0 times the center diameter of the annular core to be formed. A manufacturing method of a featured annular concentric stranded bead cord. A method for producing the annular concentric stranded bead cord according to claim 8 or 9,
An annular concentric stranded bead, wherein a twisted wire obtained by twisting a plurality of metal strands is used as the annular core, and the single strand is wound in a direction opposite to the twisting direction of the metal strands of the annular core. Code manufacturing method. It is a manufacturing method of the annular concentric twist bead cord according to any one of claims 8 to 10,
An original cord in which a plurality of single strands are twisted around a core material having the same diameter as a cord having one or more sheath layers by spirally winding a single strand around an annular core Untwisting and winding one single strand of the untwisted single strands in a spiral manner around the annular metal cord having one or more sheath layers to form a sheath layer A manufacturing method of a featured annular concentric stranded bead cord. It is a manufacturing method of the annular concentric twist bead cord according to claim 11,
A method for producing an annular concentric stranded bead cord, characterized in that a winding direction of the single element wire in a sheath layer adjacent in a radial direction is set in a reverse direction.   The annular concentric stranded bead cord according to any one of claims 1 to 7 or the annular concentric stranded bead cord produced by the method for producing the annular concentric stranded bead cord according to any one of claims 8 to 12. A vehicle tire characterized in that a bead cord is embedded.

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