JPH0482982A - Metallic cord - Google Patents

Abstract

PURPOSE:To obtain a metallic cord excellent in strength by providing an outer layer of plural intertwisted filaments around an inner layer of several intertwisted core filaments and arranging both in a specific state. CONSTITUTION:An outer layer of plural intertwisted filaments is arranged around an inner layer of 3 to 5 intertwisted core filaments and both are intertwisted into two layers. The whole filaments are simultaneously arranged so as to afford the sum total of the shortest distance of interstices between the filaments in the inner and the outer layers of >=5% based on the sum total of the distances between the centers of mutual filaments. Thereby, the objective metallic cord is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a metal cord used as a reinforcing material for tires and other articles.

[Conventional technology]

The metal cords mentioned above are known to be made by twisting multiple metal filaments together, and by embedding such metal cords in rubber products such as tires or synthetic resin products, they can be reinforced. Efforts are being made to achieve this goal.

For example, Japanese Patent Application Laid-Open No. 54-50640 discloses strands (hereinafter referred to as core filaments) that are twisted together.

), an intermediate layer consisting of a plurality of filaments and an outer layer are arranged around the inner layer, and a free space is secured between the filaments constituting the intermediate layer and the outer layer. ing.

[Problem to be solved by the invention]

In the code shown in the above publication, a free space is provided between the wires forming the intermediate layer and the outer layer.
All the core filaments are arranged in contact with each other, and the space inside is confined by the core filaments, creating a so-called compact type or compact structure. Therefore, when this cord is buried in a product, rubber materials, synthetic resin materials, etc. will penetrate into the area around the core filament, but the material will not penetrate into the inside of the core filament, leaving voids in this area. It will be left behind. For this reason, if a product in which the metal cord is buried, such as a tire, is traumatized and moisture enters through the wound, this moisture will easily spread through the gap, causing generation in the metal cord. This has the disadvantage of promoting the propagation of rust and causing a decrease in strength.

In addition, since the core filaments are in direct contact with each other, when using this metal cord, the core filaments are likely to rub against each other (fretting), and this fretting thins the core filaments, which can also cause the metal cord to rub against each other (fretting). This has the disadvantage of accelerating a decrease in strength.

Furthermore, when a bending load is applied to this metal cord,
It has also been confirmed that a localized compressive load acts on the core filaments that are in contact with each other, potentially causing brittle fracture of the core filaments.

On the other hand, in recent years, it has become increasingly important to reduce the weight of products such as tires, but open cord structures like the one described above tend to be larger in diameter than compact structures. The use of such materials tends to increase the weight of the entire product, and solving this problem is also a major issue.

In view of these circumstances, the present invention aims to provide an open type metal cord that can prevent strength reduction due to rust propagation, filament fretting, etc. It is an object of the present invention to provide a metal cord that can achieve the above objectives without being too enlarged.

[Means to solve the problem]

The present invention is characterized in that an outer layer made of a plurality of filaments is arranged around an inner layer made of three to five core filaments twisted together, and the two layers are twisted together. All the filaments are arranged so that the sum of the shortest distances between the filaments is 5% or more of the sum of the distances between the centers of the filaments (Claim 1). Here, "the shortest distance of the gap between filaments" is equivalent to the difference between the center-to-center distance between filaments and the filament diameter.

Further, the present invention provides a first outer layer made of a plurality of filaments twisted together around an inner layer made of three to five core filaments twisted together, and a plurality of core filaments arranged around the first layer. 3 by placing a second layer of twisted filaments.
The filaments are twisted into layers, and all the filaments are arranged so that the sum of the shortest distances between the filaments in each layer including the inner layer is 5% or more of the sum of the distances between the centers of the filaments (claim 2).

Further, the present invention provides a first layer in which a plurality of filaments are twisted around an inner layer in which three to five core filaments are twisted together, and a plurality of filaments are arranged around this first layer. A second layer of strands is arranged, and this second layer
A third layer consisting of a plurality of filaments twisted together is arranged around the layer, and the filaments are twisted into four layers, and the sum of the shortest distances of the gaps between the filaments in each layer including the inner layer is the center-to-center distance between the filaments. All the filaments are arranged so that they account for 5% or more of the total sum (Claim 3).

Furthermore, in each of the above metal cords, the diameter of the filament constituting any layer except the outermost layer is equal to or smaller than the diameter of the filament constituting the layer immediately outside, and the diameter of the core filament is It is more effective if the diameter is smaller than the diameter of the filament constituting the outermost layer (claim 4).

[For production]

According to the above configuration, in any cross section, not only the filament of the outer layer but also the inner layer has an open structure, so the rubber material or synthetic resin material can easily penetrate into the inner space. The space is filled with material. Therefore, even if moisture enters through a wound in the product, this moisture will not spread within the cord, and fretting between the core filaments or local compressive loads will not occur easily.

Furthermore, according to the metal cord according to claim 4, any two
When comparing the two layers, the filaments in the inner layer should always have the same or smaller diameter than the filaments in the outer layer, and the core filament should always have a smaller diameter than the filaments in the outermost layer. By making the core filament small in diameter, the diameter of the entire metal cord is made small while ensuring the spacing between the filaments and the flexibility of the entire metal cord. By making the diameter of the metal rod large, the strength of the entire metal rod can be maintained sufficiently.

〔Example〕

i) First Embodiment The metal cord shown in FIG. 1 has an inner layer 11 consisting of three metallic core filaments 10 twisted together.
around which an outer layer 14 is provided in which eight metallic filaments 12 are twisted together.

Furthermore, in this code, the inner layer 11 and the outer layer 14
In both cases, the sum of the shortest distances of the gaps between filaments 1o (12), in other words, filaments 10 (12)
The sum of the dimensions obtained by subtracting the diameter of filament 10 (12) from the center-to-center distance, and filament 10 (12)
The ratio (porosity) of the total distance between the centers is maintained at 5% or more. In other words, in each layer 11.14 at least two filaments 1 in any cross section
It has a completely open structure in which the core filaments 10 and 12 are always spaced apart, and the space inside the core filament 10 and the space outside the core filament 10 are communicated with each other. The above porosity will be detailed later.

In addition, although this FIG. 1 depicts a state in which the filaments 10 (12) are spaced at equal intervals in each layer 11.14, in reality, the intervals between the filaments 10 (12) are random. , any of the filaments 10 (12) are in contact with or close to each other in any cross section.

The present invention thus provides that each filament 10. (12) The gist is not that the two are all separated from each other,
Optional filaments 10 (12) in each layer 11.14
) with a free space secured between them.

According to the above structure, since a sufficient gap is ensured between the core filaments 10, rubber materials, synthetic resin materials, etc. can easily penetrate into the inner region of the core filaments 10 when using the metal coat. do. For this reason, rust propagation, fretting between the core filaments 10, or localized compressive loads are less likely to occur as in the conventional case, and a decrease in strength due to these factors is prevented.

Moreover, by forming the core filament 10 into an open structure, the diameter of the inscribed circle 16 of the core filament 10 also increases, so that the distance between the filaments 12 of the outer layer 14 increases accordingly, allowing penetration of the rubber material or synthetic resin material. Sexuality increases.

Note that the following modifications can be considered for this two-layer metal cord.

(1) Although FIG. 1 shows that each filament 10.12 all has the same diameter, it is possible for the diameter of the core filament 10 to be smaller than the diameter of the filament 12 of the outer layer 14.

As a result, the diameter of the entire metal cord can be kept small despite having an open structure, so there is no need to increase the layer of rubber etc. in which the metal cord is buried.
It is possible to reduce the weight of products such as tires. In addition, when making the open type as described above, a method of twisting and twisting is generally adopted, which tends to increase the rigidity of the cord, but it is possible to reduce the diameter of the core filament 10 as described above. This improves the flexibility of the metal cord as a whole, so it is effective, especially when used as a tire carcass, to ensure a comfortable ride and sufficient vibration suppression.

Furthermore, by setting the diameters of the core filaments 10 arranged in a relatively narrow area to be small in this way, it is possible to secure sufficient spacing between these core filaments 10, while the spacing between the filaments is By making the diameter of the outer filament 12 large enough to maintain sufficient strength, the strength of the entire metal cord can be ensured sufficiently, which is very rational.

Note that the specific diameter of the core filament 10 can be reduced to about 55% of the diameter of the filament 12 of the outer layer 14, considering the strength of the metal cord. If the reduction exceeds 55%, the stiffness of the cord due to the thicker filament 12 will become relatively excessive, resulting in poor strength balance of the cord.

(2) The number of the above core filaments “O” is 3 to 5.
The number of filaments 12 in the outer layer 14 may be appropriately set according to the number of core filaments 10.

As an example, FIG. 2 shows a structure with four core filaments 10 (4+9 structure), and FIG. 3 shows a structure with five core filaments 10 (5+10 structure).

In addition, when the number of core filaments 10 is two, there is an advantage that there is no inner space, but since the anisotropy of the rigidity of the cord becomes significant, it is not very suitable as a reinforcing material. On the other hand, if the number of core filaments 10 is six or more, the number of filaments in the entire cord increases, resulting in an excessive diameter, which increases the thickness of the embedded rubber layer, resulting in the disadvantage of a large increase in weight. . In this case, if two metal cords each having three core filaments 10 are used in parallel, the thickness of the embedded rubber layer will not become too large. It is lighter than using a metal cord from a book. That is, a metal cord having six or more core filaments 10 is also not suitable for practical use.

Table 1 below shows an example of a suitable number of two-layer cords.

Table 1 ii) Second Embodiment Here, as shown in FIG. 4, the layer 14 of the metal cord (hereinafter referred to as the first layer in this embodiment) shown in FIG. A second layer 20 in which a large number of filaments 18 are twisted is arranged around the periphery, and the entire cord is made up of 3 layers.
It has a layered structure.

Also, in this second layer 20, the filaments 18 are arranged at sufficient intervals so that the porosity is 5% or more.

Even in such a cord, the same effect as in the first embodiment can be obtained by penetrating the rubber, synthetic resin, etc. into the inner region of the core filament 10.

Furthermore, in this cord, the core filament 10 and the filament 12 of the first layer are twisted in the same direction, and only the filament 20 of the second layer 18 is twisted in the opposite direction to the above direction to stabilize the structure. be able to.

Regarding this three-layer cord, the core filament 1
The filament 12 in the first layer 14 has a diameter of 0
If the diameter of is d□ and the diameter of the filament 18 in the second layer 20 is d2, then do≦d1≦d2 and do<d
2, and by reducing the diameter do to approximately 55% of the diameter d2, the entire cord diameter can be kept small and the cord can be made flexible. Further, the number of core filaments 10 may be set in the range of 3 to 5 as in the above embodiment, and the number of other filaments 12 and 18 may be set accordingly. The structure when there are four core filaments 10 (4+
9+14 structure) and 5-piece structure (5+10+1
5 structure), and Table 2 below shows examples of suitable numbers.

Table 2 iii) Third embodiment (FIG. 7) Here, a third layer in which a large number of filaments 22 are twisted is further outside the second layer 20 of the metal cord shown in FIG. 4. A layer 24 is arranged, and the entire cord has a four-layer structure. Also, in this third layer 24,
The porosity is set to 5% or more, and sufficient spacing between the filaments 22 is ensured.

In the fC cord as shown in No. 1, the same effect as in the above embodiment can be obtained by infiltrating the rubber, synthetic resin, etc. into the inner region of the core filament 10.

Furthermore, in this code, the core filament 10, the first
The structure is stabilized by twisting the filaments 12 of the layer 14 and the filaments 18 of the second layer 20 in the same direction, and twisting only the filaments 22 of the third layer 24 in the opposite direction to the above direction. I can do it.

Regarding this four-layer cord, the core filament 1
The filament 12 in the first layer 14 has a diameter of 0
If the diameter of is d□, the diameter of the filament 18 in the second layer 2o is d2, and the diameter of the filament 22 in the third layer 24 is d3, then do≦d1≦d2≦d3 or -)
By setting dO<d3 and reducing the diameter do to approximately 55% of the diameter d3, the cord can be made flexible. Further, the number of core filaments 1o may be set in the range of 3 to 5 as in the embodiment described above, and the numbers of the other filaments 12, 18, and 24 may be set accordingly. Table 3 below shows examples of suitable numbers.

Table 3 i) Porosity of core filament As mentioned above,
The degree of opening of the core filament 10, that is, the porosity R is expressed by the following equation.

R=100
It is characterized by the above.

That is, when the porosity R is less than 5%, the structure becomes close to the conventional closed structure, and it is difficult for the rubber material etc. to penetrate into the inner region of the core filament 10, making it impossible to obtain the effects described above. Conversely, this porosity is 35
It is desirable not to exceed %. This is because if it exceeds 35%, the twisted structure of the metal cord itself becomes unstable.

For reference, the porosity R of the core filament 10 is 5%,
The actual structures of the two-layer cord and the three-layer cord when the ratio is 10% and 15% are shown in FIGS. 8(a) to 8(f).

V) Regarding the method for manufacturing metal cords In the present invention, since the core filaments 10 also have an open structure, these filaments 10 may be shaped in advance before manufacturing the cord. In principle, the outermost layer, i.e. the outer layer 14 in the first embodiment and the second layer 20 in the second embodiment
In the third embodiment, the third layer 24 is preferably manufactured using a tubular twisting machine, and the other layers (including the core filament 10) are preferably manufactured using a puncher twisting machine. . In this way, a stable product can be obtained by ply-twisting the metal cords using a tubular twisting machine. However, by adjusting the precision of the molding, the outermost layer can also be manufactured using a puncher type.

vi) Results of various tests The following various tests were conducted on the metal cord of the present invention and a conventional metal cord (a cord in which core filaments are in close contact with each other).

(1) Air permeability test As shown in Figure 9, a metal cord C taken out from a tire with rubber attached was used as a sample, and the middle part of this metal cord C was hardened with epoxy resin from above the rubber. A cylindrical body 26 is formed, and this cylindrical body 26 is press-fitted into one end of a rubber tube 28 as shown in FIG. 10 and fixed with a seal band 30, and air of 2.0 bg/Cd is fed from the other end. The air supply flow rate at this time is q. , if the air flow rate leaking from metal cord C is q, then the ratio between the two is q/qo
represents the air permeability of the metal cord.

Table 4 on the next page shows the ratio q/
It shows qo. In addition, in the same table, the code marked with * is a code with a compact structure, that is, as an example, as shown in Figure 11, adjacent filaments 1
This code has a structure in which 0, 12, 18, and 22 are arranged close to each other, and the other codes are the codes of the present invention.

Also, in the "air permeability" column, "micro" means the ratio q
/qo means less than 1%.

Table 4 As can be seen from this table, in any of the 2 to 4 layer cords, the ones with a compact structure marked with an asterisk (*) allow almost all of the air to pass through, whereas the cords of the present invention allow almost all of the air to pass through. do not have. From this, it can be inferred that in the cord of the present invention, the spaces between the filaments are filled with epoxy resin and there are almost no gaps. In other words, this data shows that the metal cord of the present invention has extremely high permeability to rubber and synthetic resin.

(2) Corrosion and durability test Tires (hereinafter referred to as example tires) using the metal cord of the present invention for the case cord (cord constituting the carcass) and belt cord, and a tire using the conventional metal cord for the case cord and belt cord. After manufacturing the tires used as belt cods (hereinafter referred to as comparative tires) and installing the above example tire on one side of a Lot car and the comparative example tire on the other side, the car was driven for a long distance. Corrosion and durability tests were conducted. The test conditions are as follows.

■Structure of the metal cord used for the case and belt *Case code Of the metal cords with a conventional structure shown here, those marked with a ★ have a compact structure in which all filaments are in contact with each other, and a wrapping wire is wound around the outer periphery. Codes without a ★ mark are cords in which only the core filaments are in contact with each other, other filaments are open, and no wrapping wire is used. In addition, each code CC1 to CC3 has a width of 5C in the tire.
Bury 16 pieces per II+.

*Belt code (used as 2nd code and 3rd code) The meaning of the ★ mark is the same as the case code above. In addition, 26 of each code Be□ to [lC3 are buried per 5 cm width in the tire.

■Tyres used: R22,514PR rib tires ■Running conditions Load: 11 Speed: Average 90km/h Maximum 110km/h Internal pressure (initial pressure) 28.0~/cd Mileage, 150,000 km ■Test details a) Belt cord Corrosion Test After driving under the above conditions, remove all the tire tres, and examine the propagation of rust due to cut scratches caused by nails etc. on the 3+D belt and 2nd belt. Dimensions! and the dimension m in the direction perpendicular to this, the product 1xm.

(Example) Case cord durability test After running, remove 15 case cords from each tire with the rubber still attached. A tensile test is performed on the 10 pieces, and the ratio σ/σ0 of the tensile strength σ0 before running to the tensile strength σ after running is determined as the residual strength ratio.

For the remaining five filaments, we loosened the filaments, examined the fretting scratches on their surfaces, and compared this with a sample prepared in advance that had fretting scratches in multiple stages to evaluate the fretting status of the filaments. , expressed as a fretting index. The higher the value of this fretting index, the more pronounced the fretting is.

FIG. 12 shows the results of the belt cord corrosion test. In this figure, the obtained value (A'
) is expressed as a percentage when code BC It can be seen that the propagation of is very slow. This is thought to be due to the fact that the inside of the cord is filled with a rubber material, and moisture penetration is almost completely suppressed.

FIG. 13 shows the residual strength ratio of the case cord obtained by the durability test. As shown in this graph, the strength of the conventional cords CC1 and CC2 decreases somewhat due to running, whereas the strength of the cord CC3 of the present invention decreases to some extent.
Nearly 100% strength is maintained even after running.

FIG. 14 shows the fretting index obtained from the durability test. As shown in this graph, the degree of fretting in the code CC3 of the present invention is extremely small compared to the conventional codes CC□ and CC2. This result indicates that the rubber material sufficiently penetrates into the cord, so that there is almost no contact between the filaments.

〔Effect of the invention〕

As described above, the present invention is a metal cord having a two- to four-layer structure having an inner layer composed of three to five core filaments, and in the inner layer, at least two core filaments are connected to each other. It has an open structure with sufficient distance between the core filament and the rubber material or synthetic resin material that easily penetrates into the inner region of the core filament when this metal cord is used. While suppressing the propagation of rust due to moisture penetration, it also prevents fretting between core filaments, and suppresses the occurrence of localized compressive loads when bending loads are applied to the cord. This has the effect of preventing a decrease in the strength of the cord itself.

Furthermore, in the metal cord according to claim 4, when comparing any two layers, the diameter of the filament constituting the inner layer is equal to or smaller than the diameter of the filament constituting the outer layer. , and the diameter of the core filament is set smaller than the diameter of the filament constituting the outermost layer, so by using a small-diameter inner filament arranged in a relatively narrow area, it is possible to prevent the filaments from interacting with each other. While maintaining sufficient spacing, the diameter of the entire metal cord can be kept small and the flexibility of the entire metal cord can be improved.

Therefore, even with an open structure in which the filaments are spaced apart and are generally manufactured using a manufacturing method that uses combing, it is possible to reduce the weight of the product and ensure sufficient flexibility similar to the conventional compact type. There is an effect that can be done. On the other hand, by using a large diameter filament for the outer filament where it is easy to secure a relatively large gap,
The overall strength of the metal cord can be maintained sufficiently.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a metal cord with three core filaments in the first embodiment of the present invention, Fig. 2 is a sectional view of a metal cord with four core filaments in the same embodiment, and Fig. 3 is a sectional view of a metal cord with four core filaments in the first embodiment. FIG. 4 is a cross-sectional view of a metal cord with five core filaments in the second embodiment of the present invention, and FIG. 5 is a cross-sectional view of a metal cord with three core filaments in the second embodiment of the present invention. A cross-sectional view of a metal cord with four core filaments; FIG. 6 is a cross-sectional view of a metal cord with five core filaments in the same embodiment;
FIG. 7 is a cross-sectional view of a metal cord with three core filaments in the third embodiment of the present invention, and FIGS. 8(a) to (f)
) are cross-sectional views of metal cords with various porosity, Figure 9 is a perspective view showing the state in which epoxy resin is placed around the metal cord in the air permeability test, and Figure 10 is the test for the above air permeability test. An explanatory diagram showing the device, FIG. 11 is a cross-sectional view of a metal cord with a compact structure, FIG. 12 is a graph showing the results of a corrosion test conducted on a conventional metal cord and the metal cord of the present invention, and FIG. A graph showing the residual strength ratio which is the result of the durability test conducted on the conventional metal cord and the metal cord of the present invention, FIG. 14 is the result of the durability test conducted on the conventional metal cord and the metal cord of the present invention. 1 is a graph showing a certain fretting index. C... Metal cord, 10... Core filament, 1
DESCRIPTION OF SYMBOLS 1... Inner layer, 12... Filament of outer layer (first layer), 14... Outer layer (first layer), 18...
Second layer filament, 20...Second layer, 22.
...Third layer filament, 24...Third layer. Patent Applicant Sumitomo Rubber Industries Co., Ltd. Representative Patent Attorney Etsushi Kotani Patent Attorney Chief 1) Masamukai Patent Attorney Takao Ito (Method) Case Description Patent Application No. 197215, 2000 2゜Name of the invention Metal coat 3゜Relationship with the person making the amendment case

Claims (1)

[Claims] An outer layer made of a plurality of twisted filaments is arranged around an inner layer made of one or more than three core filaments and less than or equal to five core filaments twisted together to form two layers, and these inner layers And in the outer layer, the sum of the shortest distances of the gaps between filaments is 5 of the sum of the distances between the centers of the filaments.
A metal cord characterized by having all the filaments arranged in such a way that it is more than %. A first outer layer made of a plurality of filaments twisted together is arranged around an inner layer made of two or three to five core filaments twisted together, and a plurality of filaments are twisted around this first layer. The combined second layer is arranged and twisted into three layers, and in each layer including the inner layer, the sum of the shortest distances of the gaps between the filaments is 5% or more of the sum of the center-to-center distances of the filaments. A metal cord characterized by having all filaments. 3. A first layer made of a plurality of filaments twisted together is arranged around an inner layer made of three to five core filaments twisted together, and a plurality of filaments are twisted around this first layer. A second layer is arranged, and a third layer in which a plurality of filaments are twisted is arranged around this second layer to make four layers. A metal cord characterized in that all filaments are arranged so that the sum of the shortest distances is 5% or more of the sum of the distances between the centers of the filaments. 4. In the metal cord according to any one of claims 1 to 3, the diameter of the filament constituting any layer other than the outermost layer is equal to or greater than the diameter of the filament constituting the layer immediately outside thereof. A metal cord that is small and characterized in that the diameter of the core filament is smaller than the diameter of the filament constituting the outermost layer.