KR20210065724A - Pneumatic tire for mono-filament belt sheet - Google Patents

Abstract

The present invention relates to a pneumatic tire, which has a single filament belt layer with an elliptical shape and positioned for supporting load of a vehicle and steering stability. A single filament with the elliptical shape having a ratio of a short axis to a long axis which is 1:1.1-1.5 and made of carbon steel is mounted in the belt layer. According to the present invention, the weight of the tire and rolling resistance of the tire are more reduced and durability of the tire is increased.

Description

Pneumatic tire for mono-filament belt sheet

The present invention relates to a pneumatic tire having a single filament belt layer, and more particularly, to a pneumatic tire having a single filament belt layer having an elliptical cross-section, which is positioned for the purpose of load bearing and steering stability of a vehicle.

In general, a plurality of belts, which are reinforcing parts of a tire, are installed between the carcass and the tread, and a plurality of wires are wound inside the belt to maintain the rigidity of the belt. In this way, the rigidity of the belt is maintained by the cords arranged therein, and the rigidity of the belt greatly affects the performance of the tire.

The belt distributes the stress transmitted from the ground during driving and maintains the ground shape of the tire so that it can have excellent driving, wear, and braking performance. In particular, the reinforcing belt controls the flow of the belt and maintains the optimal belt shape during driving, so that the tire always maintains a good belt shape.

On the other hand, when the rigidity of the belt is large, the steering stability is improved, but the riding comfort is deteriorated and the road noise may be rapidly increased. On the other hand, if the rigidity of the belt is too low, the riding comfort increases and the noise generation is lowered, but it has the opposite characteristic of lowering the steering stability, so it is desirable to maintain the appropriate rigidity of the belt.

The steel belt used in general pneumatic tires uses a steel cord made by twisting several strands of steel wire to support load and control stability, absorb shock, improve adhesion, and improve fatigue resistance. These steel cords are used according to the required performance of the tire, such as 1x2, 1x4, 2+7, 3+6, 3+9+15, depending on the shape and size of the twist.

In this twisted steel cord, it is very important for rubber to penetrate between the filaments. For this reason, it is very important to manage the tension of the steel cord during calendering, and when excessive tension acts, the rubber penetrates between the filaments. does not penetrate, creating an empty space, which causes corrosion in the belt layer when moisture and salt penetrate through the end of the cut surface, thereby reducing the durability of the tire. 3 is a cross-sectional view showing an example in which a twisted steel cord is applied to the first and second belt layers of a conventional pneumatic tire.

Recently, steel cords of pneumatic tires have been made lighter through high strength in order to improve RR (rolling resistance) through weight reduction of the tire. Accordingly, Korean Patent Application Laid-Open No. 2014-0126706 discloses a radial tire having a single filament structure, Also, the weight and rolling resistance reduction configuration according to the weight reduction of the tire is presented.

Korea Patent Publication No. 2014-0126706 (published date: October 31, 2014)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic tire having a single filament belt layer that further increases the effect of reducing the weight and rolling resistance of the tire by changing the shape of the single filament of the belt layer and increasing the durability of the tire.

In the pneumatic tire having a single filament belt layer according to an embodiment of the present invention, a single filament of an oval cross-section having a ratio of short axis: long axis length ratio of 1:1.1 to 1.5 made of carbon steel is embedded in the belt layer. .

The length of the minor axis is 0.25 ~ 0.5mm. In addition, the material of carbon steel is carbon steel containing 0.7 to 1.2 wt% of carbon.

The single filament is made of brass plating or bronze plating on the part in contact with the rubber. In the case of brass plating, copper is 60 to 70 parts by weight and zinc is made in a composition ratio of 30 to 40 parts by weight. In addition, in the case of bronze plating, copper is 85 to 99 parts by weight, and tin is 1 to 15 parts by weight.

A single filament is a straight steel wire with no features or corrugations.

According to the pneumatic tire having a single filament belt layer according to the present invention as described above, there is an effect of further increasing the weight reduction and rolling resistance reduction effect of the tire, and increasing the durability of the tire.

1 is a schematic cross-sectional view of a pneumatic tire having a single filament belt layer according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating an example of a state in which a single filament is disposed inside the first and second belt layers in FIG. 1 .
3 is a cross-sectional view showing an example in which a twisted steel cord is applied to the first and second belt layers of the conventional pneumatic tire.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. At this time, it should be noted that in the accompanying drawings, the same components are denoted by the same reference numerals as much as possible. In addition, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some components are exaggerated, omitted, or schematically illustrated in the accompanying drawings.

1 is a diagram schematically showing a cross-section of a pneumatic tire having a single filament belt layer according to an embodiment of the present invention, and FIG. 2 is a single filament disposed inside the first and second belt layers of FIG. It is a cross-sectional view showing an example of the finished state.

As shown, the pneumatic tire 100 according to the embodiment of the present invention includes a tread part 110 that is a part in direct contact with the road surface, a carcass part 120 constituting the skeleton of the tire, and a tread part 110 . ) and the carcass part 120 formed between the belt part 130, the inner liner part 140 to prevent air leakage, and the sidewall part ( 150), a shoulder portion 160 positioned between the tread portion 110 and the sidewall portion 150, and a bead portion 170 surrounding the end of the carcass portion 120 and mounting the tire on the rim. do.

Hereinafter, detailed descriptions of the tread part 110 , the carcass part 120 , the inner liner part 140 , the sidewall part 150 , the shoulder part 160 , and the bead part 170 will be omitted, and the present invention Only the belt unit 130 corresponding to the gist will be described in detail.

In the embodiment of FIG. 1 , the belt unit 130 includes a first belt layer 131 , a second belt layer 132 , and a reinforcing belt layer 133 stacked in an order close to the carcass unit 120 . A single filament MF serving as a steel cord is embedded inside the belt unit 130 . In the embodiment of the present invention, only the first belt layer 131 and the second belt layer 132 are exemplified as having a single filament (MF) built-in, but a single filament (MF) having higher rigidity even in the reinforcing belt 133 . is built-in

As shown in FIG. 2, the single filament (MF, Mono-Filament) is made of carbon steel, and the length ratio of the length of the short axis (c): the length of the long axis (d) is 1: an ellipse having a ratio of 1.1 to 1.5. A single filament of a cross-sectional shape is embedded in the first and second belt layers 131 and 132 at regular intervals. In the drawing, the spacing a indicates the top and bottom rubber thickness of the single filament, and the spacing b indicates the distance between the single filaments. It is preferable that the space|interval a and the space|interval b become substantially equal.

The single filament (MF) uses a straight steel wire (steel wire) having no shape or wrinkle. The corrugated steel wire has better adhesion than the straight steel wire, but an additional process for corrugation occurs, and there are many difficulties in maintaining the uniform tension of the steel wire during rubber topping (rolling process). , it is easier to separate from the press roller of the rolling mill than the straight steel wire, which increases the possibility of non-conformity. When cutting to size in the cutting process, the size of the semi-finished product due to residual stress (shrinkage of the width of the semi-finished product) becomes larger. There are disadvantages.

If the length ratio of the length of the minor axis (c) and the length of the major axis (d) is less than 1:1, it is difficult to accurately implement the length ratio compared to the circular cross-section due to the tolerance of the machinability of the elliptical filament. As the ratio between the major axis and the minor axis increases, processing is more difficult due to the concentration of stress at the end of the minor axis in the third drawing stage for realizing the filament shape.

The length of the minor axis is preferably 0.25 to 0.5 mm. If the length of the minor axis is less than 0,25mm, processing is difficult, and if the length of the minor axis exceeds 0.5mm, it is difficult to obtain a benefit considering the interval a in FIG. 2 . That is, since the elliptical filament of the present invention can implement a thin topping thickness (a) for the same area compared to a circular filament, it is possible to implement thin first and second belt layers with similar or identical rigidity, so that the entire It has the effect of improving tire performance through a reduction in tire weight and a reduction in rolling resistance, but it is difficult to obtain these benefits.

On the other hand, the material of the elliptical single filament (MF) of the present invention is carbon steel, preferably carbon steel containing 0.7 to 1.2 wt% of carbon, and in the elliptical single filament (MF), the portion in contact with the rubber is brass plating or bronze It is preferably made by plating. At this time, in the case of brass plating, it is preferable that the composition ratio of copper is 60 to 70 parts by weight and zinc is 30 to 40 parts by weight, and in the case of bronze plating, it is preferable that copper is 85 to 99 parts by weight and tin is 1 to 15 parts by weight. Do.

[Table 1] is an example of rubber adhesion evaluation (Pull-Out Test) and hot water resistance evaluation on the steel cord of the comparative example and the steel cord of the oval cross-section type single filament of the embodiment of the present invention. Initial (rubber) adhesive strength evaluation was performed according to ASTM D2229 regulations, and hot water resistance evaluation was evaluated after 4 days of hot water aging in a 70 degree chamber.

adhesion Comparative Example 1 Comparative Example 2 Example 1 Example 2 Steel cord of 1st and 2nd belt layer 1x2 (0.30mm)
compact structure 0.33mm,
round single filament long axis 0.36mm,
short axis 0.30mm,
oval single filament long axis 0.4mm,
short axis 0.33mm,
oval single filament Initial adhesion evaluation
(Kgf/0.5in) 71 15.4 17.2 19.6 Evaluation of adhesive strength in hot water
(Kgf/0.5in) 60 14 16.5 19

As shown in Table 1, it can be seen that the adhesive strength of the single filament of the oval cross-section is slightly higher than that of the single filament of the circular cross-section through the evaluation of the rubber adhesion. In addition, through the evaluation of the hot water adhesive strength, in the case of the conventional 1x2 (0.30 mm) steel cord (Comparative Example 1) compared to the initial adhesive force compared to the hot water adhesive strength evaluation result, the adhesive strength decreased by about 15%, whereas in the case of a single filament, 10 It can be seen that a decrease in adhesion within % occurred. In addition, as a result of comparing the adhesive strength of the oval filament (Example 1) compared to the circular filament (Comparative Example 2) of the same area, it can be seen that the adhesive strength slightly increased due to the larger adhesive area.

[Table 2] shows the results of testing the tire performance by applying the steel cord of the comparative example and the steel cord having an oval cross-section type single filament of the embodiment of the present invention to the first and second belt layers.

Classification (Index)
225/45R17 Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Steel cord of 1st and 2nd belt layer 1x2 (0.30mm)
compact structure 0.33mm,
round single filament 0.33mm,
round single filament long axis 0.36mm,
short axis 0.30mm,
oval single filament long axis 0.4mm,
short axis 0.33mm,
oval single filament steel strength >390
kgf/㎟ >390
kgf/㎟ >390
kgf/㎟ >390
kgf/㎟ >390
kgf/㎟ steel belt angle 27 degrees 27 degrees 30 degrees 30 degrees 30 degrees Ends per Inch (EPI) 19 28 28 28 28 steel belt
Thickness (Top Thickness Index) 100 77 77 72 77 Tire weight (Index) 100 96.5 96.5 95.8 97 RRc 100 104 102.8 103.5 103 KV static characteristics 100 100 96.8 98.2 100.7 KL static 100 98.5 102.8 103.5 103.9 KD Characteristics 100 97.3 99.6 100 101.4 KT Jeong Seongseong 100 100 100.2 102.7 103.7 Vehicle handling performance (Point) 6.25 6 6.25 6.5 6.5 Endurance
(high speed)
(hh:mm) 1:40 OK 1:40 OK 1:40 OK 1:40 OK 1:40 OK Endurance
(Long term)
(hh:mm) 220:00 OK 220:00 OK 220:00 OK 220:00 OK 220:00 OK

As shown in [Table 2], the example in which a single filament was applied (Comparative Example 2, Comparative Example 3, Example 1, and Example 2) had a topping thickness compared to the example in which a twisted steel cord was applied (Comparative 1). It can be applied thinly, which can reduce the weight of the tire and improve the RRc (rolling resistance). However, when applied at the same belt angle, the handling performance is deteriorated due to a decrease in lateral force. Accordingly, when the belt angle is slightly increased to satisfy the tire handling performance while improving the RRc performance, a balanced and improved tire performance can be obtained. Here, when applying the single filament of the oval shape (Examples 1 and 2), it was possible to implement a slightly improved handling performance than when applying the single filament of the circular shape (Comparative Example 2, Comparative Example 3).

As described above, in the present invention, the pneumatic tire of the present invention in which a single filament of an oval cross-section is embedded in the first and second belt layers is a pneumatic tire in which a single filament of a circular cross-section is embedded in the first and second belt layers. Since it is possible to implement a thin top thickness compared to the same area compared to the previous model, it is possible to implement a thin belt layer compared to similar or identical rigidity, which has the effect of improving tire performance by reducing the overall tire weight and reducing rolling resistance.

Although the present invention has been described with reference to the embodiment shown in the drawings, which is only exemplary, it will be understood that various modifications and equivalent other embodiments are possible by those skilled in the art will be. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

100: pneumatic tire 110: tread part
120: carcass unit 130: belt unit
131: first belt layer 132: second belt layer
133: reinforced belt layer 140: inner liner unit
150: side wall portion 160: shoulder portion
170: bead unit

Claims (6)

A pneumatic tire having a single filament belt layer, characterized in that a single filament in the form of an elliptical cross-section having a ratio of short axis: long axis length ratio of 1:1 to 1.5 made of carbon steel is embedded in the belt layer. According to claim 1,
The length of the minor axis is a pneumatic tire having a single filament belt layer, characterized in that 0.25 ~ 0.5mm. According to claim 1,
The carbon steel is a pneumatic tire having a single filament belt layer, characterized in that it contains 0.7 to 1.2 wt% of carbon. According to claim 1,
The single filament is a pneumatic tire having a single filament belt layer, characterized in that the portion in contact with the rubber is made of brass plating or bronze plating. 5. The method of claim 4,
In the case of the brass plating, copper is 60 to 70 parts by weight and zinc is made in a composition ratio of 30 to 40 parts by weight,
In the case of the bronze plating, copper is 85-100 parts by weight, and tin is a pneumatic tire having a single filament belt layer, characterized in that it consists of 1-15 parts by weight. According to claim 1,
The single filament is a pneumatic tire having a single filament belt layer, characterized in that the steel wire in a straight shape without any shape or wrinkle.

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