JPH07238480A - Production of steel cord for reinforcing rubber and production device therefor - Google Patents

Abstract

PURPOSE:To provide a method for producing a steel cord for reinforcing rubber capable of efficiently twisting high-strength steel filaments while suppressing reduction in breakage ratio and tensile strength and to supply a production device. CONSTITUTION:Steel filaments 2 supplied from a feed reel 1 are provided with torsion in the cord twisting direction and in the opposite direction and three to five of the filaments are twisted by a twice twisting twister to cancel normal and reverse torsion and to reduce an additional twisting amount to remove residual torsion by a false twisting device 9. The groove of a flyer guide is made semicircular to smoothly advance an offset of normal and reverse torsion near a twisting inlet die 6, the radius R of the groove is made 6D to 10D (D: diameter of the cord) and the guide 7 is provided with a swinging angle theta in a specific direction. Consequently, the twisted amount of the filaments is lessened, breakage is reduced and a drop in tensile strength is suppressed to the minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel cord used for reinforcing a rubber structure such as an automobile tire or a conveyor belt, and more particularly to a method and a device for manufacturing a steel cord suitable for reinforcing a belt layer of a radial tire.

[0002]

2. Description of the Related Art In recent years, there has been a tendency for the operating speed to increase further due to the expansion of expressways and the accompanying increase in transportation efficiency. Along with this, of course, the improvement of high-speed durability of automobile tires, but has been increasing more and more demand for weight reduction of the tire, the tire that has been reinforced with steel cord, inevitably becomes heavy for the specific gravity of the steel cord is large. Therefore, as a measure to reduce the weight, the strength of the steel filament that constitutes the steel cord is improved by increasing the carbon content or increasing the total area reduction rate up to the final finished wire diameter,
It has been considered to reduce the weight of the cord by making the filament diameter smaller in proportion to that.

However, from the viewpoint of the steel cord manufacturing side, this method improves the filament breakage rate in the final wire drawing step, increases the frequency of die replacement, and twists the steel filament in the twisting step. It is difficult to say that it is the best measure because frequent disconnection (this is 3 to 10 times the disconnection rate in the wire drawing process) is inevitable and a decrease in productivity cannot be avoided.

The increase in the number of broken steel filaments in the twisting process is also due to the twisting equipment.

That is, in the conventional double twisting type twisting machine, the supply filament is wound on a reel both inside and outside the machine, and naturally the terminal is restrained. Therefore, as is well known, in this type of twisting machine, the same number of twists as the number of twists is applied to the steel filament. This twist is
In the case of a soft metal filament made of copper, aluminum, etc., it is plastically deformed and absorbed, but in the case of an elastic steel filament, twisting by the elastic limit remains. Therefore, as an additional process, a false twist (overtwisting) device provided before and after the twisting machine is used to add a twist equivalent to the twist of the elastic limit, and then the overtwisted part is untwisted to leave a residual twist (residual twist). (Torsion) is removed. In this way, the double twist type twisting machine imparts extra twist to the filament to be twisted by the number of times of twisting by the false twisting device, so when twisting steel filaments, the tensile strength of the filament decreases. In addition, wire breakage is likely to occur in the twisted state. The disconnection has a carbon content of 0.67 to 0.75% by weight.
It also occurs when twisting ordinary steel filaments. Therefore, the carbon content should be 0.78-0.90% by weight.
In addition, the high strength steel filament that has been strengthened by work hardening by increasing the total area reduction rate of wire drawing is the conventional method,
It can be said that many wire breakages occur when twisted by a device.

An object of the present invention is to fully utilize the feature (high productivity) of a double twist type twisting wire machine that can obtain a twist twice the number of revolutions even when using a high strength steel filament. The aim is to reduce the breakage of the steel filament in the twisting process and to minimize the reduction in the tensile strength of the filament.

[0007]

In order to solve the above problems, in the present invention, a steel filament having a tensile strength of 300 kgf / mm ² or more, which has been subjected to metal plating such as brass plating on the surface thereof, is used, for example, When 5 pieces are twisted to form a steel cord, a twist equal to or more than the number of times of cord twist (preferably 1 to 1.25 times) is added to each of the steel filaments in advance in the direction opposite to the cord twist direction,
On the other hand, in the twisting machine, the guide groove shape of the flyer guide is semicircular, and the radius R (mm) of the groove is 6D ≦ R ≦ 10D (D:
(Cord diameter), and the guide is 5 ° to the guide shaft in the direction opposite to the cord twisting direction.
A method of introducing a reversely twisted steel filament into the twisting machine, and twisting the positive twist caused by twisting and the reverse twist in the vicinity of the twisting port while offsetting the forward twist in the vicinity of the twisting opening. Take.

Further, regarding the manufacturing apparatus, a rotary supply device composed of a swingable cradle having the same number of flyer guides as the number of supply reels, a tension applying device and supply reels, a semicircular guide groove shape, and Radius R (mm)
Is a size satisfying the condition of 6D ≦ R ≦ 10D (D: cord diameter), and a swing angle of 5 ° to 13 ° is given to the wire passage axis in the direction opposite to the cord twisting direction, The above-described method is carried out in this apparatus with a double-twisting type twisting machine constituted by a swingable cradle having a false twisting device, a take-up capstan and a take-up reel.

The steel filaments twisted by the method of the present invention are preferably limited in diameter to the range of 0.20 to 0.30 mm. The maximum number of twists T _max added to each steel filament in the process in which the steel filament becomes a steel cord by twisting.
It is desirable that twisting be performed by controlling the twisting so as to satisfy the following formula.

[0010]

[Equation 2]

The twist control can be realized by controlling the number of revolutions of each rotating part of the above-mentioned manufacturing apparatus.

[0012]

[Function] When steel filaments having a tensile strength of 300 kgf / mm ² or more, which have been hard-worked, are twisted together by the conventional twisting machine shown in FIG. 2, the steel filaments 2 constituting the steel cord are connected to the fryer guides 7, 7 Since the maximum twisting amount reaches 800 times / 6 m when the twisting pitch is 10 mm, for example, when the twisting is performed twice by ', and when the twisting is performed by the false twisting device 9 provided to remove the residual twisting of the cord, a frequent disconnection rate occurs. , A significant decrease in tensile strength is inevitable.

On the other hand, in the method of the present invention, the reverse twist given in advance cancels the twist that occurs during double twisting in the vicinity of the twisting opening, so that the residual twist during double twisting becomes extremely small. Further, as a result, the residual twist can be removed by reducing the number of rotations of the false twisting device, so that the maximum twist amount during twisting by the false twisting device also becomes small. Twisting during twisting is also canceled depending on the amount of reverse twist imparted. Therefore, according to the present invention, the filament after twisting is not severely twisted, and the breakage of the filament and the decrease in tensile strength are reduced. . The filament breakage prevention effect is also exhibited when the cord is used, which leads to improvement in durability of the completed cord.

Next, the above explanation is based on the premise that the positive twist caused by the twisting and the reverse twist given in advance are well offset, but in the double twist type twisting machine having two flyer guides. Since the twisting wire tension is applied, it is not easy for the second twist generated in the fryer guide 7 to propagate to the twisting die 6 (the first twist is the fryer guide). 7'is close to the twisting die, so it easily propagates). For example, in the conventional method and apparatus, the ratio of the second twist reaching the twisting hole is as small as about 20%. Therefore, the twist cancellation cannot be performed well unless some twist is made to propagate the second twist smoothly and the cord twist pitch immediately after passing through the twist die is made the same as the finished product.

As a result of researching a method therefor, the inventor puts the flyer guide into a direction opposite to the cord twisting direction.
It was found that the twist can be smoothly propagated while obtaining a good guide function by shaking (inclining the direction of the guide groove with respect to the line axis) by 13 °.

In order to give the guide a swing angle of 5 ° to 13 °, the conventional guide groove shape (groove bottom radius R is 1.0D
Since it is impossible with V-grooves of up to 2.0 D), trial manufacture and examination of guides are also conducted, and it is appropriate that the guide grooves have a semicircular shape from both sides of the propagation of twist and the guide function, and the groove radius R is 6D to 10D. I also found a thing.

The present invention achieves the object by adding the above-mentioned device to the flyer guide of the twisting machine.

The reason why the reverse twist given to the steel filament in advance is preferably 1.00 to 1.25 times the number of times of twisting the cord is that in the present invention as well, in order to remove the residual twist after twisting twice, This is because the twisting (overtwisting) device performs overtwisting and untwisting, but if a large amount of reverse twisting is performed, this twisting during twisting can be finally canceled.

The diameter of the steel filament used in the present invention is preferably 0.20 to 0.30 mm because the tensile strength is 300 kgf /
This is because it becomes more difficult to manufacture a steel filament having a size of ² mm ² or more and capable of withstanding a twisting process, while a thin filament having a diameter of less than 0.20 mm is expensive to manufacture. Furthermore, when using the filaments in this range, it is said that the condition of the above formula should be satisfied, not only the effect of the invention is sufficiently exhibited, but also the production by the device of the present invention can be carried out without difficulty, This is because the quality of the code that has been increased.

[0020]

FIG. 1 shows a specific example of the manufacturing method and manufacturing apparatus of the present invention.

This figure shows the direction of rotation of each of the rotating parts of the double twisting type twisting machine B and the rotation supply device A when manufacturing the S twist steel cord, and the groove of the flyer guide of the double twisting type twisting machine. The shape, the swing direction and swing angle with respect to the line axis of the flyer guide are shown.

In FIG. 1, the rotation of a motor (not shown), which is a drive source, is transmitted to the flyer guides 7 and 7'through a drive system, and the steel cord is rotated in the direction of S twist to the right and left 2 Twisted twice at the flyer guides 7 ', 7'. Further, the twice twisted steel cord is once taken up by the take-up capstan 8 to which power is applied via the drive system gear, and then guided to the false twisting device 9. The twist of the twice twisted steel cord has a twist corresponding to the elastic limit, and this residual twist (which is less than that of the conventional twist) is removed by overtwisting by the false twisting device 9 and subsequent untwisting. Then, the straightening roller 10 finely adjusts the straightness and the residual twist. After that, the steel cap 11 is wound around the take-up capstan 8 several times, and the completed steel cord 11 is wound around the take-up reel 13 via the traverse roller 12.

The flyer guides 7 and 7'use rollers here. The outer two guides 7, 7 out of the four flyer guides have a guide groove with a semicircular shape as shown in FIG. 1B, and the radius R of the guide groove is equal to the cord diameter D. 6 to 10 times. Further, the guides 7 and 7 are provided with a swing angle of θ ° (= 5 to 13 °) so that the direction of the groove inclines in the direction opposite to the twisting direction with respect to the line axis. With this guide structure, the second twist generated at the position of the guide 7 on the left side also propagates smoothly to the twisting die 6, and even in the continuous twisting, the offset of the forward and reverse twists added to the steel filament is smoothly performed. move on.

Reference numeral 22 denotes a swingable cradle in which at least a take-up capstan 8, a false twisting device 9 and a take-up reel 13 are provided. The straightening roller 10 is a preferred element, but may be omitted.

Next, the process from the supply section to the twisting port will be described.

The steel filament 2 constituting the steel cord is supplied in a tension-adjusted state from the supply reel 1 in a tension adjusting device (not shown) provided in the swingable cradle 21. This steel filament 2 is twisted twice in the direction opposite to the twisting direction of the steel cord in the course of passing through the flyer guide 3 of the roller and the flyer guide 4 of the disc. It is guided to No. 5 and is gathered by the twisting die 6 and twisted successively.

Although the figure shows only two cradle of the rotary supply device A, the steel filament 2 is
3 to 5 are supplied while twisting and twisted.
Further, the twist imparted to the steel filament 2 before twisting is performed by setting the rotation speed of the rotary supply device A to be larger than that of the double twisting type twisting wire machine B (preferably 1 to
Make the number of twists in the opposite direction equal to or greater than the number of twists of the cord.

As a result, the twists entering the steel filament during the production of the steel cord are canceled out almost continuously,
Filament breakage and reduction in tensile strength during the twisting process are reduced. In addition, since the finished steel cord has a small amount of twist of the filament, the quality and durability of the cord are also improved.

The results of experiments for confirming the effects will be described below.

In the experiment, steel filaments for steel cords shown in Table 1 were prepared and the filaments shown in FIG.
The method of the present invention using the apparatus of FIG. 2, the conventional method of using the apparatus of FIG. 2 and the pre-applied twist amount by the apparatus of FIG. 1 and the method of setting the configuration of the fryer guide outside the conditions of the present invention Performance comparison was performed for the obtained steel cords in Table 2. The results are shown in Table 3.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

As can be seen from these results, according to the method and apparatus of the present invention, the filament breakage rate in the twisting step is remarkably reduced, and the reduction rate of the tensile strength of the steel filament is suppressed to 1% or less.

[0035]

As described above, according to the present invention,
In particular, when twisting steel filaments having a tensile strength of 300 kgf / mm ² or more, it is possible to reduce the twisting caused by the twisting of the steel filaments, which is the cause of the wire breakage, and reduce the wire breakage in the twisting process. It is possible to improve productivity and significantly reduce stranded wire costs by increasing the operating rate of equipment.

Further, it is possible to minimize the decrease in the tensile strength of the steel filament obtained by the difficult processing until the final finish wire drawing, and further, the steel filament having a small amount of twist can endure repeated bending. Therefore, it is possible to realize and provide a low-cost steel cord for rubber reinforcement, which is high in quality and excellent in durability.

The steel cords produced by the method and apparatus of the present invention can be used for various rubber structures, but especially when used as reinforcing cords for vehicle tires, conveyor belts, high pressure hoses, etc. Can be expected.

[Brief description of drawings]

FIG. 1 (a) is a simplified view showing an example of a rubber reinforcing steel cord manufacturing apparatus of the present invention. (B): An enlarged plan view showing a flyer guide of a double twist type twisting machine of the same apparatus.

FIG. 2 is a view showing a simplified example of a conventional rubber-reinforced steel cord manufacturing apparatus.

[Explanation of symbols]

 A rotating supply device B double twisting type twisting machine 1 steel filament supply reel 2 steel filament 3 roller flyer guide 4 disc fryer guide 5 type eye plate 6 twist spout die 7, 7'roller flyer guide 8 Take-up capstan 9 False twisting (overtwisting) device 10 Straightening roller 11 Steel cord 12 Traverse roller 13 Take-up reel 21 Cradle of rotating supply device 22 Cradle of double twisting twisting machine

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[Procedure amendment]

[Submission date] October 12, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

[0033]

[Table 3]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B60C 9/00 J 7615-3D

Claims (3)

[Claims] 1. A steel filament having a tensile strength of 300 kgf / mm ² or more and having a metal plating on the surface thereof is 3-5.
A method for manufacturing a rubber-reinforced steel cord obtained by main twisting, wherein twisting equal to or more than the number of cord twists is added to each of the steel filaments in the opposite direction to the cord twist direction in advance. , The guide groove shape of the fryer guide is semi-circular, and the radius R (mm) of the groove is 6D ≦ R
It is assumed that the size satisfies the condition of ≦ 10D (D: cord diameter), and that a swing angle of 5 ° to 13 ° is given to this guide in the direction opposite to the cord twisting direction with respect to the wire passing axis.
A method for producing a steel cord for rubber reinforcement, which comprises introducing the reverse twisted steel filament into the twisting machine, and twisting the filament while canceling the forward twist and the reverse twist caused by twisting in the vicinity of the twisting opening. . 2. A rotary supply device comprising a swingable cradle having the same number of flyer guides as the number of supply reels, a tension applying device, and supply reels, a guide groove shape of a semicircle, and a radius R (mm) of the groove. 6D ≦ R ≦ 10D
(D: Cord diameter), and 5 ° to 13 in the direction opposite to the cord twisting direction with respect to the wire shaft.
Flyer guide with a swing angle of °, false twisting device,
A double twisting type twisting machine consisting of a swingable cradle with a take-up capstan and a take-up reel is provided. An apparatus for manufacturing a steel cord for rubber reinforcement, in which a twist of equal or more is added and the steel filaments are twisted together by the double twist type twisting machine. 3. The maximum number of twists T _max added to each steel filament in the process of forming a steel cord by twisting a steel filament having a diameter of 0.20 to 0.30 mm using the manufacturing apparatus according to claim 2. The method for producing a rubber-reinforced steel cord according to claim 1, wherein twisting is performed so that the twisting is performed so that the following expression is satisfied. [Equation 1]