JP4355111B2 - Manufacturing method of elastomer composite steel cord - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a steel cord that is embedded in a tire or the like and used as a reinforcing material, and more specifically, can exhibit sufficient corrosion resistance and fatigue resistance when used as a tire reinforcing material, for example. In addition, the present invention relates to a method for producing an elastomer composite steel cord having a two-layer structure capable of shortening the vulcanization time at the time of molding a tire and achieving energy saving.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a steel cord for reinforcing tires has a two-layer structure in which a plurality of strands (steel filaments) are twisted into two layers inside and outside. FIG. 7 shows an example of a steel cord having a two-layer structure, in which three steel filaments 1 are twisted to form a core strand 2, and nine steel filaments 3 are formed as outer layer filaments around the twisted core strand 2. A cross-sectional structure of a steel cord 4 having a so-called 3 + 9 structure in which the core strand 2 is twisted with a twist direction or a twist pitch different from that of the core strand 2 is shown.
[0003]
In the steel cord in which a plurality of steel filaments are twisted into two layers in this way, as shown in FIG. 7, a gap 5 extending in a straw shape in the longitudinal direction of the strand is formed at the center of the core strand 2, and the outer layer A gap 6 is formed inside the steel filament 3 (between the core strand 2).
[0004]
The example shown in FIG. 7 is the case of the 3 + 9 structure, but the two-layer structure of m + n (m = 2 to 4) is the same, and a void is formed at the center of the strand and a void is formed inside the outer filament.
[0005]
In the case of these steel cords having an m + n structure, conventionally, it is expected that rubber penetrates between the filaments of the steel cord at the time of tire molding (vulcanization) and the rubber is filled into the gaps inside the cord. It was. However, since these two-layer steel cords have a small gap between the filaments arranged in the outer layer, a sufficient amount of rubber does not penetrate into the cord during molding of the tire. In particular, in the case of a steel cord densely twisted to the outer layer, the amount of rubber that permeates is small, and the voids inside the cord are not completely filled. As a result, fretting (scratching) wear occurs inside the steel cord during use of the tire, and moisture etc. infiltrate into the steel cord due to damage on the tire surface, which significantly deteriorates the fatigue resistance of the tire cord. The tire life may be shortened.
[0006]
In addition, the effect of the air gap remaining inside the steel cord is not only that, but the air remaining in the air gap is exhaled at the time of tire molding, and it remains in the rubber as an air reservoir, which reduces the strength of the tire body. Also become. Therefore, in order to disperse such air and eliminate the air trap, it is necessary to lengthen the vulcanization time at the time of molding the tire, the productivity is deteriorated and the energy consumed is increased.
[0007]
As an improvement on the steel cord of this m + n structure, the number of filaments in the outer layer of the steel cord is set to be a few less than the number of filaments in the case of dense twisting, and there is a gap between the outer layer filaments, so that rubber penetrates during tire molding It is also considered to make it easier to do. For example, in the steel cord disclosed in Japanese Patent Laid-Open No. 7-109685, the number of sheath filaments (outer layer filaments) is set to 7 to 8 for three core filaments, so that the gap between the sheath filament and the core filament is reduced. Rubber is allowed to enter. However, even with such a structure, it is difficult to completely fill the gap inside the steel cord with rubber, and although it can slightly increase the tire life compared to the dense twist, it is not sufficient.
[0008]
In addition, when the outer layer filaments are twisted around the core strand to form a two-layer structure in this way, the twisted wire has two steps, which increases the manufacturing cost. 1 is formed by arranging a plurality (n) of outer layer filaments around a plurality (m) of core filaments, and twisting all the steel filaments into a two-layer structure in the same direction and at the same pitch. A steel cord having a two-ply structure is also considered. FIG. 8 shows an example of such a single-twisted two-layer steel cord in which nine steel filaments 3 ′ as outer filaments are arranged around three steel filaments 1 ′ as core filaments, and all the steel The filament is twisted into a two-layer structure in the same direction and the same pitch. A cross-sectional structure of a steel cord 7 having a so-called 3/9 structure is shown.
[0009]
However, in the case of a steel cord in which a plurality of core filaments and a plurality of outer layer filaments are twisted at once in the same direction and the same pitch, the twist direction and the twist pitch of the core filament and the outer layer filament are the same. For this reason, a drop occurs in the outer-layer filament in such a manner that it is in close contact with the filament of the core strand formed by twisting a plurality of core filaments. And as shown in FIG. 8, not only the space | gap 8 of strand center part but the space | gap 9 inside outer-layer filament 3 'will also be in the sealed state.
[0010]
Therefore, the space inside the outer layer filament is smaller in volume than in the case of a steel cord having a double-twisted two-layer structure, and the amount of air discharged into the rubber at the time of tire molding is reduced. Almost no rubber penetrates. As a result, fretting wear occurs inside the steel cord while the tire is in use, and the tire cord's fatigue resistance significantly deteriorates due to moisture entering the steel cord due to damage to the tire surface. Tire life may be shortened.
[0011]
In addition, although the volume is reduced as compared to the case of a steel cord having a double twisted two-layer structure, a void remains, and the air remaining in the void is expelled at the time of molding the tire and remains in the rubber as an air reservoir. Therefore, in order to disperse such air and eliminate the air trap, it is necessary to lengthen the vulcanization time at the time of molding the tire, which deteriorates productivity and consumes the tire body. Energy increases.
[0012]
Further, in such a steel cord having a single-twisted two-layer structure, for example, as disclosed in JP-A-62-125085, the diameter of the core filament is made larger than that of the outer-layer filament, and the gap between the filaments is increased. It is also considered to secure rubber and allow the rubber to penetrate into the inside of the cord, but even with such a structure, it is difficult to completely fill the gap inside the cord with rubber and slightly increase the tire life. It can be done, but not enough.
[0013]
In addition, for example, as shown in Japanese Patent Laid-Open No. 6-49786, a water-absorbing polymer is present in the voids inside the steel cord, and as shown in Japanese Patent Laid-Open No. 61-138789, steel is used. A cord filled with an organic material core, or one using vulcanized rubber as the core material of a steel cord, as disclosed in Japanese Patent Publication No. 59-24239, is considered. When using such water-absorbing polymers and organic materials, it is necessary to consider both the adhesion of the tire body to the rubber and the adhesion to the steel filament. It must be disadvantageous.
[0014]
[Problems to be solved by the invention]
As described above, the conventional two-layer steel cord does not allow a sufficient amount of rubber to penetrate into the cord during molding of the tire, creating a void in the center of the strand and a void inside the outer layer filament. In addition, fretting wear occurs inside the steel cord, and moisture may enter the steel cord due to damage on the tire surface, which may significantly deteriorate the fatigue resistance of the tire cord and shorten the tire life. Also, if the air remaining in the voids inside the steel cord remains in the rubber as an air reservoir, the strength of the tire body is impaired, so the vulcanization time when molding the tire to eliminate such air reservoir In order to solve such problems, there is a problem that productivity is deteriorated and energy consumed is increased. Even if the outer layer filaments are reduced to create gaps between the filaments to facilitate rubber penetration, it is difficult to completely fill the voids inside the steel cord with rubber. In a steel cord with a layered structure, the outer layer filaments drop, the gaps between the filaments become sealed, again causing fretting wear, leading to deterioration of fatigue resistance due to ingress of moisture etc., and air accumulation It is necessary to lengthen the vulcanization time in order to eliminate the problem, and there is a problem that the productivity is deteriorated and the consumption energy is increased. Also, in the case of using a water-absorbing polymer or an organic material, the rubber of the tire body is used. It is necessary to consider both the adhesion to the steel and the adhesion to the steel filament. There is a cormorant problem.
[0015]
The present invention is for solving such problems, and is a method for manufacturing a steel cord having a two-layer structure that is embedded in a tire or the like and used as a reinforcing material, does not cause fretting wear, and has sufficient corrosion resistance and Exhibiting fatigue resistance, extending the life of the steel cord itself, extending the life of tires etc. that use it as a reinforcing material, and shortening the vulcanization time at the time of tire molding etc. to achieve energy saving An object of the present invention is to provide a production method capable of
[0016]
[Means for Solving the Problems]
This invention provides the manufacturing method of the elastomer composite steel cord for solving the said subject.
[0017]
In the method for producing an elastomer composite steel cord of the present invention, after uncoated rubber is coated around all the 2 to 4 steel filaments used as core filaments, the 2 to 4 all steel filaments are simultaneously twisted. In addition, a core strand in which the unvulcanized rubber is filled in the center of the strand and the periphery is coated with the unvulcanized rubber is formed, and then a plurality of unvulcanized rubbers are formed as outer layer filaments around the core strand. By twisting steel filaments that are not coated with an outer layer, the two-layered elastomer composite steel cord in which the gap between the outer core steel filaments and the inner core strand is filled with unvulcanized rubber is characterized. To do.
[0018]
According to this method for producing an elastomer composite steel cord, after two to four steel filaments coated with unvulcanized rubber are twisted to form a core strand, a plurality of steel filaments are twisted around the core strand. By combining them, an elastomer composite steel cord having a two-layer structure is obtained.
[0019]
This elastomer composite steel cord is coated with unvulcanized rubber in advance around all of the 2 to 4 steel filaments used as core filaments, and they are twisted together to create internal voids. A core strand filled with unvulcanized rubber and coated with unvulcanized rubber is obtained. Then, a plurality of steel filaments, which are outer layer filaments, are twisted around the core strand, so that the voids inside the outer layer steel filaments (between the core strands) are filled with unvulcanized rubber.
[0020]
In this way, an elastomer composite steel cord is obtained in which all the internal voids are filled with unvulcanized rubber and the cord surface does not protrude from the unvulcanized rubber. And this steel cord is embedded in the rubber of the tire body at the time of molding the tire as a tire reinforcing material, for example, so that the unvulcanized rubber is vulcanized and the gap inside the cord is completely filled with rubber. Therefore, fretting wear does not occur, corrosion from the inside of the cord due to moisture and the like can be prevented, the fatigue resistance of the steel cord can be improved, and the life of rubber products such as tires can be extended. Further, since the gap inside the cord is filled, the amount of air brought into the rubber when molding the tire is small, a stable tire can be manufactured, the vulcanization time can be shortened, and the energy loss can be reduced. Further, the unvulcanized rubber has good adhesion to the rubber of the tire body and adhesion to the steel filament, and does not cause a problem in terms of technology and cost.
[0021]
In these methods for producing an elastomer composite steel cord, the unvulcanized rubber previously coated on the steel filament is preferably the same quality as the tire rubber from the standpoints of adhesion and cost.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
1 and 2 show a method for manufacturing elastomeric composite steel cord according to the embodiment of this invention. In this example, an elastomer composite steel cord having a 3 + 9 structure is manufactured. The manufacturing method includes a step of manufacturing a core strand (shown in FIG. 1) and a step of twisting outer layer filaments around the core strand (FIG. 2). As shown in FIG. In FIG. 1, 11 is an unvulcanized rubber coating apparatus, 12 is a line dividing apparatus, 13 is a collective voice, 14 is a buncher twisting machine, 15 is a line dividing apparatus, 16 is a collective voice, and 17 is a buncher twist. It is a wire machine. In any case, the apparatus itself is a conventionally known one.
[0024]
In the process of manufacturing the core strand shown in FIG. 1, three steel filaments 18 serving as core filaments are fed out in parallel and supplied toward the twist port of the buncher twisting machine 14. During the supply, the three steel filaments 18 are coated with unvulcanized rubber around the filaments by the unvulcanized rubber coating apparatus 11. Then, the steel filament coated with rubber is divided into three pieces by the wire dividing device 12 and sent to the collective voice 13, gathered by the collective voice 13, supplied to the buncher twisting machine 14, and simultaneously three at a predetermined pitch. Twisted together.
[0025]
In this way, the core strand 19 having a cross-sectional shape shown in FIG. 3 is obtained. Before the core strand 19 is twisted, all the steel filaments 18 are coated with unvulcanized rubber 20, and the filaments coated with these unvulcanized rubber 20 are twisted together, as shown in FIG. The strand center portion 21 is filled with the unvulcanized rubber 20 and the periphery is covered with the unvulcanized rubber 20.
[0026]
The core strand 19 is once wound on a reel. Then, in the next step, as shown in FIG. 2, the core strand 19 and nine steel filaments 22 as outer layer filaments are drawn out in parallel in an arrangement in which the nine outer layer filaments surround the core strand 19, It is supplied toward the twisting opening of the buncher twisting machine 17. Then, the core strand 19 and the nine steel filaments 22 of the outer layer are separated by the line dividing device 15 and sent to the collecting voice 16, gathered by the collecting voice 16, supplied to the buncher twisting machine 17, and the core strand 19. Nine steel filaments 22 of the outer layer are twisted around each other.
[0027]
Thus, an elastomer composite steel cord 23 having a two-layer structure whose cross-sectional shape is shown in FIG. 4 is obtained. The elastomer composite steel cord 23 has a shape in which the core strand 19 is filled with the unvulcanized rubber 20 in the center portion 21 of the strand as described above, and the periphery is covered with the unvulcanized rubber 20. By twisting the nine steel filaments 22 as the outer layer filaments, the voids inside the steel filaments 22 of the outer layer (between the core strands) are filled with the unvulcanized rubber 20.
[0028]
The elastomer composite steel cord 23 is, for example, embedded in a tire body rubber as a tire reinforcing material when the tire is molded. In this case, the unvulcanized rubber 20 covered with the steel filament 18 as a core filament is the same quality as the tire rubber. Is used. The unvulcanized rubber 20 is vulcanized at the time of tire molding (vulcanization), and the gap inside the cord is completely filled with rubber. Therefore, fretting wear does not occur, corrosion from the inside of the cord due to moisture and the like can be prevented, the fatigue resistance of the steel cord can be improved, and the life of rubber products such as tires can be extended. Further, since the gap inside the cord is filled, the amount of air brought into the rubber during tire molding is small, and a stable tire can be manufactured, and the vulcanization time can be shortened and the energy loss can be reduced.
[0029]
Although the illustrated embodiment shows the case of a 3 + 9 structure, the present invention can be similarly implemented in the case of another double-twisted two-layer structure in which the core strand is formed of 2 to 4 steel filaments.
[0030]
FIG. 5 shows a manufacturing process of the elastomer composite steel cord of the reference example . This example is a case where an elastomer composite steel cord having a 3/9 structure is manufactured. In FIG. 5, 24 is an unvulcanized rubber coating device, 25 and 26 are line dividing devices, 27 is a collective voice, and 28 is a buncher twisting machine, both of which are conventionally known.
[0031]
In this example, three steel filaments 29 serving as core filaments and nine steel filaments 30 serving as outer layer filaments are composed of three steel filaments 29 serving as core filaments and nine outer filaments serving as outer layer filaments. The steel filaments 30 are fed out in parallel with each other so as to surround the steel filaments 30 and supplied toward the twisting opening of the buncher stranding machine 28. In the middle of the supply, the three steel filaments 29 serving as core filaments are each coated with unvulcanized rubber around the filaments by an unvulcanized rubber coating device 24, passed through a line-separating device 25 in the previous stage, and in the subsequent stage. Assembly is performed by the line dividing device 26. Further, the outer layer steel filament 30 is directly sent to the subsequent line dividing device 26. The aggregated unvulcanized rubber-coated steel filament 29 and the outer nine steel filaments 30 are separated by a line-separating device 26 at the subsequent stage and sent to a collective voice 27. Supplied to the wire machine 28, the core filaments and the outer layer filaments are twisted together in the same direction and the same pitch.
[0032]
Thus, an elastomer composite steel cord 31 having a two-layer structure whose cross-sectional shape is shown in FIG. 6 is obtained. This elastomer composite steel cord 31 is coated with unvulcanized rubber in advance around all of the three steel filaments 29 as core filaments, and these are twisted at once with nine steel filaments 30 as outer layer filaments. As a result, the gap between the central portion and the surrounding filaments is in a sealed state, and the unsealed rubber 32 is filled in the sealed gap.
[0033]
This elastomer composite steel cord 31 is also embedded in the rubber of the tire body at the time of molding the tire as a tire reinforcing material, for example. In this case, the unvulcanized rubber 32 covered with the steel filament 29 as the core filament is tire rubber. The same quality is used. The unvulcanized rubber 32 is vulcanized at the time of tire molding (vulcanization), and the gap inside the cord is completely filled with rubber. Therefore, fretting wear does not occur, corrosion from the inside of the cord due to moisture and the like can be prevented, the fatigue resistance of the steel cord can be improved, and the life of rubber production for tires and the like can be extended. In addition, even if it is a two-layer structure twisted once, the gap inside the cord is completely filled with rubber, so the amount of air that is brought into the rubber when molding the tire is small, and stable tire production is possible, and vulcanization is possible. Time can be shortened and energy loss can be reduced.
[0034]
The illustrated reference example shows the case of the 3/9 structure, but the same applies to the case of another one-twisted two-layer structure in which a plurality of steel filaments are used as core filaments.
[0035]
Of course, the present invention can also be applied to a method of manufacturing a steel cord other than for tire reinforcement.
[0036]
【The invention's effect】
As is apparent from the above description, according to the present invention, in the case of a steel cord having a double-twisted two-layer structure, not only the center space but also the space inside the outer steel filament (between the core strands). An elastomer composite steel cord filled with unvulcanized rubber is obtained, and when this elastomer composite steel cord is used for tire reinforcement etc., the gap inside the cord is completely filled with rubber, and fretting wear does not occur It can prevent corrosion from the inside of the cord due to moisture, etc., improve the fatigue resistance of the steel cord, and reduce the amount of air brought into the rubber when molding the tire, which makes stable tire production It is possible to shorten the vulcanization time and reduce energy loss.
[0037]
And since the material which fills a space | gap can be made into the same quality as rubber | gum, such as a tire, there is also no problem at all with adhesiveness with a filament.
[Brief description of the drawings]
FIG. 1 is a schematic view of a process for producing a core strand in an embodiment of the present invention.
FIG. 2 is a schematic view of a step of twisting outer layer filaments around a core strand in the embodiment of the present invention.
FIG. 3 is a cross-sectional view of a core strand in the embodiment of the present invention.
FIG. 4 is a cross-sectional view of an elastomer composite steel cord obtained by the manufacturing method according to the embodiment of the present invention.
FIG. 5 is a schematic view of a production process of an elastomer composite steel cord of a reference example .
FIG. 6 is a cross-sectional view of an elastomer composite steel cord obtained by the manufacturing method of the reference example .
FIG. 7 is a cross-sectional view of a conventional steel cord having a double twist two-layer structure.
FIG. 8 is a cross-sectional view of a conventional steel cord having a single twist two-layer structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Unvulcanized rubber coating device 12 Line dividing device 13 Collecting voice 14 Buncher twisting machine 15 Line dividing device 16 Collecting voice 17 Buncher twisting machine 18 Steel filament (core filament)
19 core strand 20 unvulcanized rubber 21 strand center 22 steel filament (outer layer filament)
23 Elastomer composite steel cord (twisted twice)
24 Unvulcanized rubber coating device 25 Line dividing device 26 Line dividing device 27 Aggregate voice 28 Buncher stranding machine 29 Steel filament (core filament)
30 Steel filament (outer layer filament)
31 Elastomer composite steel cord (twisted once)
32 Unvulcanized rubber

Claims (2)

After coating the unvulcanized rubber around all the 2 to 4 steel filaments used as the core filament, the 2 to 4 all steel filaments are twisted at the same time, and the unvulcanized rubber is placed at the center of the strand. By forming a core strand that is filled and coated with unvulcanized rubber around the core strand, and then twisting a plurality of unfiltrated rubber-coated steel filaments around the core strand as outer layer filaments A method for producing an elastomer composite steel cord, characterized in that an elastomer composite steel cord having a two-layer structure in which a gap between the core strands inside the steel filament of the outer layer is filled with unvulcanized rubber is used. 2. The method for producing an elastomer composite steel cord according to claim 1, wherein the unvulcanized rubber is the same quality as a rubber of a tire.

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