JPH06200491A - Method for correcting steel cord and apparatus therefor - Google Patents

Abstract

PURPOSE:To reduce residual torsion of a steel cord twisted using Buncher twister, especially residual torsion generated with time even after carrying out treatment to remove the torsion by a twister. CONSTITUTION:Twist by which torsion is left is further applied to a steel cord twisted by Buncher tire twister in the direction where twist is further tightened, and then, this twist is returned and twist having same direction as this return of twist is applied to the steel cord, and again this twist is returned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for straightening steel cords used as a reinforcing material for rubber articles such as pneumatic tires and industrial belts, and in particular, a buncher type stranding machine twists the cords together. This is intended to suppress the change over time in the residual torsion of the cord, which occurs at that time.

[0002]

2. Description of the Related Art For example, a steel cord used for a belt portion of a pneumatic tire is a composite of a rubber and a rubber in which a plurality of cords are aligned in parallel and covered with a sheet-like rubber in a calendering process (hereinafter, treat). In the cutting step, the treat material is cut obliquely with respect to the cord longitudinal direction at regular intervals to prepare a treat material 1 as shown in FIG. 1, and then the side surface of the treat material 1 is cut. They are joined together and used as a belt ply of a tire as a belt-shaped treat material as shown in FIG.

Here, since the steel cord has a residual torsion added in the twisting process, when the cord restraint is released at the end of the treat material during the cutting, the steel cord will rotate in the direction along the peripheral surface of the cord. The power to generate is generated.
And the residual torsion of the normally aligned steel cords is biased in one direction between the steel cords, and the treat material cut in the above cutting process attempts to untwist the force or the force that the cords try to untwist themselves. The forces gather to work toward the outside, and when the treat material is left on the horizontal surface, the end portion of the treat material is deformed to jump up from the horizontal surface. In such a case, the treat material having the edges repelled is manually corrected when the joining as shown in FIG. 2 becomes impossible or the degree of the rebound is not large in the next joining step. It takes a lot of time and labor to join the cords, and in any case, there is a problem that the cords of the joints are disturbed and the appearance thereof is deteriorated and the durability of the tire belt is deteriorated.

From the above background, there is a demand for a steel cord having a small residual torsion, and in recent years, since a treat material is automatically joined, a demand for a cord having a small torsion is strong.

Conventionally, a steel cord used in a tire belt has a 1 × 4 or 1 × 5 single twist structure or a 2 + 6 layer twist structure, and is a buncher type twisting machine. In the case of twisting together, as shown in FIG. 3, the flyer bow 5 formed by the metal wire rods 3 formed by rotating the rotating frames 4a and 4b is used to unwind the plurality of metal wire rods 3 fed from the unwinding reel 2. The cord is manufactured by rotating the reel 2 around a plurality of wire rods 3 at a predetermined pitch.
Since the cord just after formation has a large residual torsion, the cord 6 that has passed through the fryer bow 5 is twisted a predetermined number of times by the twister 7 in the subsequent step, and then twisted back the same number of times to remove the residual torsion. Is being done.

[0006]

However, in the steel cord from which the residual torsion has been removed, the residual torsion disappears immediately after the production of the steel cord, but if left for a certain period of time after that, new torsion occurs, Since this torsion has already appeared when the treat material is used, the above-mentioned problem of the splash of the treat material has not been solved yet.

Therefore, an object of the present invention is to reduce the residual torsion of steel cords twisted together by using a buncher twisting machine, particularly the residual torsion which occurs over time even after the treatment for removing with a twister. The present invention provides a straightening method and a device therefor.

[0008]

The present invention is a buncher type twisting machine, in which steel cords twisted together are
In addition, after giving a twist in which the torsion remains in a direction in which the twist is tightened, returning this twist, and then giving a twist in the same direction as this unwinding, and then returning this twist. is there.

Further, according to the present invention, in the buncher twisting wire machine, twisters capable of adding twisting and untwisting at a desired rotation number to the twisted steel cords are installed in two stages in the steel cord conveying path. Is a steel cord straightening device.

[0010]

The present invention is to eliminate the residual torsion of the cords twisted by the buncher twisting wire machine.
The basic idea is to remove the residual torsion and to suppress its change over time, using two twisters, twisting, then untwisting, and then twisting in the same direction as this untwisting. , To untwist this twist.

In the buncher twisting machine, the cord immediately after the flyer bow has a minus (-) saturated torsion that tries to be untwisted. Therefore, in order to eliminate the saturated residual torsion, it is further twisted and then twisted again. Processing by the twister 7 shown in FIG. 3 is performed. Then, as shown in FIG. 4, the residual torsion in the cord after this treatment is removed, but this phenomenon does not occur because all the torsional shearing forces inside the wire are eliminated, but in the cross section of the metal wire. It is considered that the torsional shearing forces at the central portion and the outer peripheral portion occur because they are well-balanced and suspended in the radial direction of the wire rod. That is, there is a force in the center of the wire in the direction where the twist returns, and in the outer circumference, there is a shearing force that tries to add twist, and since these forces are suspended as a whole, the residual torsion seems to disappear. . However, as shown in FIG. 4, when aging progresses due to standing or the like, the material of the metal changes, the shear stress changes accordingly, and as a result, the balance of the shear stress is lost, resulting in residual torsion. it is conceivable that.

Based on the above findings, various investigations have been made on various techniques for suppressing the change in residual torsion over time.
The inventors have found that it is effective to reduce the difference in shear stress distribution in the radial direction of the metal wire, and arrived at the present invention.

Specifically, as shown in FIG. 5, the cord 6 passed through the twister 7 of FIG. 3 is further twisted and untwisted in the direction opposite to the twister 7 in the twister 8 to generate the twister 7. This is achieved by applying a twisting process in a direction that cancels the shear stress in the inside and the surface layer of the formed strand. It is preferable to set the residual torsion in the twister 7 in the + direction and set the residual torsion in the twister 8 to − in order to reduce the residual torsion of the cord to zero on the output side of the twister 8.

Further, as shown in FIG. 6, the twister 7
By providing the drive pulley 9 between the twister 8 and
The tension tension in the treatment with the twister 8 can be set to a constant value, and more stable control of residual torsion can be performed. This is because, in the twister treatment, the tensile tension affects the degree of correction of residual shear strain in the filament.

[0015]

[Examples] Using a raw material of SWRH 82 A specified in JIS C 3506 or a composition similar thereto, a wire having a tensile strength of about 300 kg and a wire diameter of 0.23 mm was manufactured by heat treatment and wire drawing treatment. Then, as shown in Fig. 5, this strand was buncher type twisting machine with a twist pitch of 9.5 mm, 1 x 4
A closed type cord with a structure is twisted together. Here, the unwinding speed is the twisting condition in the buncher twisting machine.
The flyer bow rotation speed was 2000 rpm at 38 mm / min.

Further, after twisting with a large torsion in the twister 7 and then untwisting, twist in the same direction as this untwisting is applied with the twister 8, and then this twisting is unwound to remove the residual torsion. The torsion added by the twister 7 and the untwisting by the twister 8 can be set arbitrarily.

For comparison, a twist was given a predetermined number of times with a fryer bow, and the generated residual torsion was removed by a twister 7 to complete the production and obtain a comparative cord. In any case, after setting the twister rotation speed so that the residual torsion during stranded wire becomes zero, the twisted cord is left at room temperature (25 ° C) for 24 hours, and the residual torsion after leaving is measured. . Table 1 shows the measurement results of the rotational speed of the twister and the residual torsion.

The operations in the above Examples and Comparative Examples are
FIG. 7 shows the relationship between the added torsion and the residual torsion.
Shown in. As shown in the figure, in the comparative example, when twist is added along the curve of ab and then the restraint of the cord terminal is released, at the time of b, there is a negative residual torsion, and thus bx The twist returns along the line. Therefore, the twister 7 further twists and returns the twist, thereby adding a bcd twist to the cord and reducing the residual torsion to zero.

On the other hand, in the embodiment, the twisting and untwisting in the twister 7 are performed more excessively than in the comparative example, and the torsion history of the cord is bee (h) -f (i). Next, since the cord has a positive residual torsion at the time of f (i), in order to correct this, after twisting in the same direction as twisting in the twister 7 with the twister 8, it is returned, Add f (i) -g (i) -d torsion history to the code.

Here, the residual torsion was evaluated by pulling the cord out of the reel for 5 m with the terminal restrained, and then measuring the rotation of the cord when the restraint of the terminal was released. The value of the torsion was measured with a positive value in the direction in which the cord was twisted. In addition, the reason why the cord was left to stand at room temperature for 24 hours for aging was that the change in residual torsion of the cord reached equilibrium by 24 hours.

[0021]

[Table 1]

It can be seen from Table 1 that the cord according to the present invention has a significantly reduced change in residual torsion over time as compared with the cord obtained by the conventional method.

FIG. 8 shows the twister 7 in the above embodiment.
5 is a graph showing the amount of change over time in the residual torsion when the rotational speed of the and the rotational speed of the twister 8 are changed.
As shown in the figure, the ratio of the residual torsion added by the twister 8 to the saturated residual torsion (hereinafter referred to as the overtwist rate) shows a good correlation with the residual torsional change amount of the cord. The number is 2280r.pm and the rotation speed of Twister 8 is 670r.pm.
At that time, the residual torsion becomes zero.

The set rotational speeds of the twisters 7 and 8 can be set by the value of the allowable residual torsion, and can be appropriately changed depending on the type of metal wire material used or the conditions of the twisted wire. It is not preferable to increase the rotation speed of both the twister 7 and the twister 8 from the viewpoint of disconnection of the cord or the strand due to the twisting process by the twister, but for example, the torsional change due to the aging of the steel cord required in the tire manufacturing process is -0.5 times / 5m, the rotation speed of the twister 8
By setting the rotation speed of the twister 7 to 1680-2280r.pm so that the residual torsion after exiting the twister 8 becomes almost zero at 240 to 670 rpm, the residual torsion is almost zero and changes with time. It is possible to manufacture a cord that does not cause

[0025]

As described above, according to the present invention, it is possible to suppress the change over time in the residual torsion when the cord after being twisted is left unattended, and to prevent the residual torsion even when the cord is put to practical use. It is possible to provide a code that does not exist and is industrially useful.

[Brief description of drawings]

FIG. 1 is a schematic view showing a treat material.

FIG. 2 is an explanatory diagram for creating a treat material.

FIG. 3 is a schematic diagram of a twisted wire device according to a conventional method.

FIG. 4 is a diagram showing a change with time of residual torsion.

FIG. 5 is a schematic view of an apparatus for twisting wires according to the present invention.

FIG. 6 is a schematic diagram of an apparatus for twisting wires according to the present invention.

FIG. 7 is a graph showing the relationship between additional torsion and residual torsion.

FIG. 8 is a view showing a relationship between changes in additional torsion and residual torsion in the twister 8 with time.

[Explanation of symbols]

 1 Treat Material 2 Unwinding Reel 3 Metal Wire Material 4a Rotating Frame 4b Rotating Frame 5 Flyer Bow 6 Cord 7 Twister 8 Twister 9 Drive Pulley

Claims (2)

[Claims] 1. A buncher type twisting machine, after twisting a twisted steel cord in a direction in which the twist is tightened, in which twist remains, and then returning the twist.
Next, a method of straightening a steel cord, which comprises applying a twist in the same direction as the untwisting and then returning the twist. 2. A twister capable of adding a desired number of twists and untwisting to a twisted steel cord in a buncher twisting machine is provided in a steel cord conveying path.
Steel cord straightening device characterized by being installed in steps.