JP4993729B2 - Steel cord - Google Patents

Description

  The present invention relates to a steel cord, and more particularly, to a steel cord used as a reinforcing member for rubber products, synthetic resin products and the like.

  In order to improve the durability of rubber products or synthetic resin products such as automobile tires and motorcycle tires, steel cords made by twisting multiple steel wires (single steel wires) are reinforced. It is used as a member. FIG. 9 shows an example of the internal structure of an automobile tire. The automobile tire 60 is configured by laminating a carcass layer 61, two belt layers 62, 63, and a tread layer 64, and a large number of steel cords 65 are embedded in each of the belt layers 62, 63. .

  The steel cord 65 embedded in the belt layers 62 and 63 includes, for example, one steel wire core wire (core wire) and a plurality of steel wire side wires (side wires) positioned around the steel wire core wire. Made by twisting together.

  When the core wire passing through the center of the steel cord 65 moves in the longitudinal direction of the steel cord 65, the core wire jumps out from the tip of the steel cord 65. For the movement of the core wire, the stress concentrates on the portion of the steel cord 65 where the core wire is no longer located, and the steel cord 65 breaks early, or the protruding core wire protrudes from the belt layer and is adjacent to the rubber. There is a risk of causing problems such as separation of members. It is important to suppress the movement of the heart wire.

  Japanese Patent Application Laid-Open No. H10-228561 describes that waveform shaping is applied to the core wire in order to prevent the movement of the core wire. However, if the core wire is molded, the strength of the core wire is inevitably reduced due to the processing. As a result, the cutting strength per unit mass of the steel cord is reduced, and the strength efficiency as a reinforcing member is lowered. .

Patent Document 2 describes that the movement of the core wire is suppressed by suppressing the molding rate of the side wires positioned around the core wire to a low level. The molding rate represents the degree of the molding (wave height) of the wire (elementary wire). By reducing the molding rate of the side wire, the force with which the side wire presses the core wire becomes relatively large, so that the movement of the core wire can be suppressed. However, if the molding rate of the side wire is lowered, the steel cord is likely to be loosened. In particular, when the above-described belt layer is formed by cutting a rubber sheet in which a steel cord is embedded, the steel cord is likely to be scattered at the cut portion (cut end). The looseness of the steel cord causes a decrease in strength of the steel cord and fretting wear.
Japanese Patent No. 3040025 Japanese Patent No. 3805007

  It is an object of the present invention to provide a steel cord that is suppressed with respect to both the movement of the core wire and the looseness of the steel cord.

  The steel cord according to the present invention includes one steel wire core wire (hereinafter referred to as a core wire) and a plurality of steel wire side wires (hereinafter referred to as side wires) positioned around the steel wire core wire. Are made by twisting together.

  Each of the plurality of side wires is spirally shaped. The spiral type of the side wire has a type rate that suppresses the movement of the core wire (movement of the core wire in the longitudinal direction of the steel cord). The molding rate represents the degree of helical molding (wave height) of the side wire (elementary wire), and a numerical value obtained by the following equation is used.

  Die rate of side wire = H / D x 100 (%)

  Here, H represents the size (wave height) of the spiral type of the side wire, and D represents the diameter of the steel cord.

Further, each of the side wires is provided with a residual rotational stress for preventing the steel cord from being scattered in the same direction as the twisting direction of the steel cord. In this application, the magnitude | size of a residual rotational stress is represented by the rotation speed of the other end when one end of a 6-m side wire is fixed and the other end of a side wire is open | released.

  For example, the side wire can be molded by running the side wire along a plurality of pins arranged at predetermined positions. The molding rate is adjusted by adjusting the interval or the arrangement position of the pins. The residual rotational stress can be applied to the side wire by twisting the side wire in a predetermined direction a predetermined number of times and twisting it back a predetermined number of times. The direction of the residual rotational stress is the same as the direction of twisting when twisting. By adjusting the number of twists of the side wire (twisting speed when twisting), the magnitude of the residual rotational stress is adjusted. By applying this residual rotational stress, the mold for the side wire becomes spiral.

  A steel cord is formed by twisting a core wire and a plurality of side wires spirally formed and applied with residual rotational stress in the same direction as the direction of residual rotational stress of the side wire.

  According to the present invention, the movement of the heart wire can be suppressed by adjusting the die forming rate of the spiral die forming of the side wire. Also, the steel cord scatter that tends to occur with the adoption of a molding rate that suppresses the movement of the core wire is suppressed by the residual rotational stress in the same direction as the twist direction of the steel cord applied to the side wire. Is done. For this reason, both the movement of the core wire and the dispersion of the steel cord can be suppressed.

  Preferably, the mold rate of the spiral mold of the side wire is 70% or more and less than 100%. If the rate of spiral-type molding of the side wire is less than 100%, the force with which the side wire presses the core wire becomes relatively large, so that the movement of the core wire can be suppressed relatively reliably. It should be noted that setting the molding rate to 70% or more is that if the molding rate is too low, it may not be possible to prevent the steel cord from being scattered even if residual rotational stress is applied to the side wire. This is to prevent this.

  More preferably, the residual rotational stress applied to the side wire is not less than 2 times and not more than 6 times. If the residual rotational stress is twice or more, the dispersion of the steel cord is surely suppressed. Further, if the residual rotational stress applied to the side wire is large, rotational stress may be generated (remaining or remaining) in the entire steel cord due to the residual rotational stress of the side wire. If rotational stress remains in the entire steel cord, the rubber sheet in which the steel cord is embedded (the belt member (FIG. 9) described above is formed by cutting the rubber sheet) The belt member may be warped by the rotational stress of the entire cord, and the production efficiency of the belt member may deteriorate. If the residual rotational stress applied to the side wire is 6 times or less, the residual rotational stress applied to the side wire causes relatively no rotational stress to remain in the entire steel cord. It is possible to prevent the production efficiency from being affected.

  More preferably, the residual rotational stress applied to the side wire is 4 times or less. If the residual rotational stress is 4 times or less, the certainty that the rotational stress does not remain in the entire steel cord increases.

  The present invention also provides a composite made of rubber or synthetic resin using a steel cord for reinforcement.

  The composite made of rubber or synthetic resin according to the present invention is such that the steel cord is embedded in rubber or synthetic resin.

  As described above, in the steel cord according to the present invention, since the movement of the core wire is suppressed and the steel cord is not easily scattered, the composite is obtained by embedding the steel cord in rubber or synthetic resin. The fatigue strength of can be increased.

(About steel cord manufacturing equipment)
FIG. 1 shows an example of the overall configuration of a steel cord manufacturing apparatus. FIG. 2 shows the configuration of a preformer (molding machine), and FIG. 3 shows the configuration of a rotational stress adjusting device.

  The steel cord manufacturing apparatus in this embodiment has a single core wire (core wire) (core wire) cw made of steel as a center, and is positioned around the core wire cw and the core wire cw. The steel side wire (elementary wire) (sheath wire) sw is bundled while being twisted, and a so-called 1 + 5 steel cord (stranded wire) is formed. The core wire cw is supplied from the bobbin 41 around which the core wire cw is wound, and the five side wires sw are supplied from the five bobbins 42 around which the side wires sw are wound. The core wire cw and the side wire sw are fed out from the bobbins 41 and 42 at a conveyance speed of about 100 m / min, for example.

  The core wire cw fed from the bobbin 41 is directly guided to the twisting machine 3. On the other hand, each of the five side wires sw passes through the preformer 1 and the rotational stress adjusting device 2 before being drawn out from the bobbin 42 and before being guided to the twisting machine 3.

  Referring to FIG. 2, the preformer 1 includes a cylindrical body 10 provided with three rotatable rotation pins 1a to 1c. The cylinder 10 is fixedly provided on a frame (not shown). The rotation pins 1a to 1c are arranged at a predetermined interval, and the rotation pin 1b is arranged to be displaceable between the rotation pins 1a and 1c. A side wire sw is hung on each of the rotating pins 1a, 1b, 1c. The side wire sw passes between the rotating pins 1a to 1c. Furthermore, the side wire sw delivered from the preformer 1 by the rotational stress adjusting device 2 described later is twisted. As a result, the side wire sw is spirally shaped.

  The degree of helical typing applied to the side wire sw can be expressed by the molding rate. The molding rate can be controlled by changing the arrangement position of the rotary pin 1b. Details of the molding rate of the side wires sw will be described later.

  The side wire sw delivered from the preformer 1 is sent to the rotational stress adjusting device 2.

  Referring to FIG. 3, rotational stress adjusting device 2 is configured such that rotatable first and second rolls 2 a and 2 b each having two grooves (not shown) formed in parallel are spaced apart from each other in a straight line. The cylinder 20 is provided. The side wire sw passes through the side of the first roll 2a in the cylinder 20 and is hooked on the first groove of the second roll 2b, and is subsequently hooked on the first groove of the first roll 2a. ing. The side wire sw is hung from the first groove of the first roll 2a to the second groove of the second roll 2b and the second groove of the first roll 2a, and the side of the second roll 2b. After passing, it is fed out of the cylinder 20.

  A hollow rotary shaft 51 is rotatably supported by a bearing 52 on a frame (not shown) of the rotational stress adjusting device 2. The cylindrical body 20 is fixed to one end of the hollow rotating shaft 51, and the pulley 53 is fixed to the other end of the rotating shaft 51. A belt 54 applied to the pulley 53 is driven by a motor (not shown). The rotating shaft 51 and the cylindrical body 20 rotate via the belt 54. A motor may be provided in each of the rotational stress adjusting devices 2 to rotate each of the motors synchronously, or one motor may be shared by each of the five rotational stress adjusting devices 2.

  When the cylindrical body 20 rotates, the side wire sw is twisted on the inlet side of the cylindrical body 20 and its twist is returned on the outlet side. By rotating the cylindrical body 20 at a relatively high speed, the side wire sw exceeds the elastic region (twisting to the extent that the torsion is completely restored) to a plastic region (twisting to the extent that the torsion is not completely restored). The torsion is put in until it reaches, and then twisted back. Thereby, residual rotational stress is given to the side wire sw. When the other end is opened while one end of the side wire sw is fixed, the side wire sw is rotated in the direction in which the twist is inserted due to the residual rotational stress. That is, the rotational direction of the cylinder 20 and the direction of the residual rotational stress applied to the side wire sw coincide. The magnitude of the residual rotational stress can be adjusted by varying the number of twists of the side wire sw (rotational speed of the cylindrical body 20). The cylindrical body 20 rotates in the same direction as the twisting direction (the rotation direction of the flyer) by the twisting machine 3 to be described later. Therefore, the direction of the residual rotational stress applied to the side wire sw is the steel cord (stranded wire). ) In the same direction as the twisting direction.

  Returning to FIG. 1, five side wires sw spirally formed by the preformer 1 and the rotational stress adjusting device 2 and applied with residual rotational stress, and the core wire cw fed out from the bobbin 41 are: They are collected by an aggregator 44 through a guide roller 43. The bundled core wire cw and the five side wires sw are sent to the twisting machine 3 via the voice 45. The side wire sw is sent to the twisting machine 3 with the residual rotational stress remaining.

  Two hollow rotary shafts 17 and 18 are rotatably supported by bearings 39 and 40 on a frame (not shown) of the stranding machine 3, respectively. These hollow rotary shafts 17 and 18 are provided apart from each other and arranged in a straight line. As will be described later, the hollow rotary shafts 17 and 18 are driven to rotate synchronously.

  A cradle 19 is rotatably supported by bearings 24 and 25 at both ends of the inner ends of the hollow rotary shafts 17 and 18. Even when the hollow rotary shafts 17 and 18 rotate, the cradle 19 is kept almost stationary.

  The cradle 19 has a winding bobbin 23 for winding a steel cord (twisted wire), a capstan 21 for stabilizing the steel cord before winding the steel cord, and a bobbin from the capstan 21 to the steel cord. A guide roller 22 for guiding to 23, a rotational stress adjusting device 26 for adjusting the rotational stress of the entire steel cord by twisting and untwisting the entire steel cord, and the like are provided.

  An arcuate flyer 11 is fixed to the hollow rotary shafts 17 and 18 via a flyer mounting member 13. The flyer 11 rotates together with the hollow rotary shafts 17 and 18. The flyer 11 is provided with a plurality of guide tips 12 for guiding the steel cord.

  Further, a bearing 35 for rotatably supporting a drive shaft (pass shaft) 34 and a drive motor 30 are fixed to the frame. A belt 32 is hung between a pulley 31 attached to the output shaft of the drive motor 30 and a pulley 33 fixed to the drive shaft 34. Pulleys 36 are also attached to both ends of the drive shaft 34. Further, pulleys 37 are fixed to the outer ends of the rotary shafts 17 and 18, respectively, and a belt 38 is hung between the pulleys 36 and 37. Accordingly, the hollow rotary shafts 17 and 18 are rotated by the motor 30 in the same direction and at the same rotational speed, whereby the flyer 11 is rotated. The rotational direction of the flyer 11 is the same as the rotational direction of the rotational stress adjusting device 2 as described above.

  The bundled core wire cw and the five side wires sw pass through one hollow rotary shaft 17, pass through guide rollers 14 and 15, and are hung on the guide tip 12 of the flyer 11 and guided along the flyer 11. Then, it passes through the inside of the guide roller 16 and the hollow rotary shaft 18, is wound around the capstan 21 via the stress adjusting device 26, and is wound around the winding bobbin 23 from the capstan 21 via the guide roller 22. As the hollow rotary shafts 17 and 18 and the flyer 11 rotate, a twist is added to the bundle of the core wire cw and the five side wires sw to form a steel cord (twisted wire) tw. Since the rotation direction of the flyer 11 and the rotation direction of the cylindrical body 20 of the rotational stress adjusting device 2 are the same direction, the direction of the residual rotational stress applied to the side wire sw and the twist direction of the steel cord tw match. . Note that the stress adjusting device 26 provided in the twisting machine 3 is for adjusting the rotational stress of the entire steel cord tw as described above, and here, the entire steel cord tw reaches the plastic region. Twisted and untwisted. The stress adjusting device 26 provided in the stranded wire machine 3 has the same configuration as the above-described stress adjusting device 2 (FIG. 3).

  FIG. 4 is a perspective view of a steel cord tw having a 1 + 5 structure manufactured by a steel cord manufacturing apparatus, and FIG. 5 is an enlarged sectional view thereof. By changing the number of side wires sw, the steel cord manufacturing apparatus can also be used to manufacture 1 + 4 steel cords (FIG. 6A) and 1 + 6 steel cords (FIG. 6B). it can.

(About the evaluation test)
Tables 1 and 2 show the results of an evaluation test of a steel cord tw (test object) having a 1 + 5 structure. Table 1 shows that the diameter of the core wire cw is 0.32 mm and the diameter of the side wire sw is 0. Table 2 shows the results of an evaluation test of a 37 mm steel cord tw (1 × 0.32 + 5 × 0.37). Table 2 shows a steel cord tw in which the diameter of the core wire cw is 1 mm and the diameter of the side wire sw is 0.25 mm. The result of the evaluation test of (1 + 5 × 0.25) is shown. Tables 1 and 2 show the evaluation test results for 10 specimens (1) to (10), respectively.

  In the evaluation test, as shown in Tables 1 and 2, a large number of steel cords tw (devices under test) were produced with different “side wire moldability” and “side wire residual rotational stress”. (In Tables 1 and 2, as described above, the evaluation test results of 10 test objects (1) to (10) are shown) And “movement of the cardiac wire” were evaluated. As described above, the molding rate of the side wire sw is adjusted by changing the arrangement position of the rotary pin 1b (see FIG. 2) provided in the preformer 1, and the residual rotational stress of the side wire sw is changed to the side. Adjustment is made by varying the number of twists of the wire sw (the rotational speed of the cylinder 20 (see FIG. 3) of the rotational stress adjusting device 2).

  The molding rate of the side wire sw is calculated by the following equation.

  Molding rate of side wire sw = H / D × 100 (%)

  Here, H is the size (wave height) of the spiral type of the side wire sw, and D is the diameter of the steel cord tw (test object).

  Here, the wave height H of the side wire sw was measured as follows.

The produced steel cord tw (test object) is cut to an appropriate length, and the side wire sw is loosened to form a strand. As shown in FIG. 7, the side wire sw is projected by a projector, and the projection image of the side wire sw is projected on a screen or the like, and the heights h ₁ to h ₄ of the spirally shaped waves are measured at four locations. This measurement is performed for all of the five side wires sw constituting the device under test, and the average value is defined as the wave height H of the side wire sw of the device under test.

  As the diameter D of the steel cord tw (test object), a numerical value obtained by the following equation was used.

The diameter D = d _c + 2d _s of the steel cord tw

Here d _c heart wire cw diameter, d _s is the diameter of the side wire sw.

  The residual rotational stress of the side wire sw was measured as follows.

  Cut the produced steel cord tw (test object) to 6m, and rotate the entire steel cord tw in the direction opposite to the twist direction, taking care not to release the residual rotational stress (side wire sw The side wires sw are separated from each other so that they do not rotate themselves. When one end of the separated side wire sw is fixed and the other end of the side wire sw is opened, the side wire sw rotates in the same direction as the twist direction due to residual rotational stress. The number of rotations at the other end of the side wire sw (the number of rotations until the stationary wire sw comes to rest) is measured in 1/4 rotation units. This measurement is performed for all of the five side wires sw constituting the device under test, and the average value is defined as the residual rotational stress (unit: times) of the side wire sw of the device under test.

  In the evaluation test, the residual rotational stress is also measured for the entire steel cord tw (test object).

  The evaluation of the “break” of the side wire and the “movement of the core wire” for each of the test objects was performed as follows.

  First, the evaluation of the fluctuation of the side wires will be described. In the evaluation of the fluctuation of the side wires, four stages of evaluation from A judgment to D judgment were performed as follows.

Prepare a steel cord (test object), hold a part 50 mm away from the part to be cut, and cut the cut part with pliers.
(1) When there is no scatter when cutting If there is no scatter when cutting, apply a light impact to the cutting area (striking with a pliers, striking on a desk, etc.). Repeat this cutting and impact three times, changing the cutting location.
(1-1) If the variation does not occur three times in succession, the judgment is A.
(1-2) If a light impact is applied and even one out of three times occurs, the cutting location is changed and only cutting is repeated three times (no impact is applied). If there is no variation for three consecutive times, B is determined.
(2) If a break occurs at the time of cutting, or a break occurs even once in (1-2) In this case, hold the hand near the cutting point, cut with pliers, Gently release the hand holding nearby. This cutting is repeated three times while changing the cutting position.
(2-1) Among the three times, if no variation occurs even once, C determination is made.
(2-2) If the variation occurs three times in succession, the judgment is D.

  In the evaluation of “movement of the cardiac wire”, the movement of the cardiac wire “with” or the movement of the cardiac wire “without” was evaluated as follows.

  A steel cord tw (test object) having a diameter of about several meters is prepared in a coil shape having a diameter of, for example, about 150 mm (wrapped several times). Hold the coiled steel cord tw with both hands and repeat the deformation (for example, bring both hands closer or separated).

  (1) If the core wire cw does not protrude from the end of the steel cord tw even after a plurality of deformations, the movement of the core wire is evaluated as “none”.

  (2) When the core wire cw protrudes from the end of the steel cord tw, the movement of the core wire is evaluated as “present”.

  FIG. 8 plots the results of the measurement test based on Tables 1 and 2 on the coordinate axis with the horizontal axis representing the side wire moldability and the vertical axis representing the residual rotational stress of the side wire. Black circles show the measurement results in Table 1, and white circles show the measurement results in Table 2. Further, in the vicinity of each plot point, the numbers of the test objects shown in Tables 1 and 2 (numbers (1) to (10)) are shown.

(i) When the molding rate exceeded 100%, the core wire cw moved (test object (8)). If the molding rate was less than 100%, the movement of the core wire cw did not occur.

(ii) When the molding rate was less than 70%, the evaluation of the variation was D (test object (7)). When the molding rate was 70% or more, as described later, when the residual rotational stress was 2 times or more, the evaluation of variation was A determination or B determination.

(iii) When the residual rotational stress of the side wire sw was smaller than one time, the evaluation of scatter was judged as D even when the molding rate was about 85% (test object (9)). If the residual rotational stress was 2 times or more and the molding rate was 70% or more, the evaluation of the dispersion was A judgment or B judgment.

(iv) When the residual rotational stress of the side wire sw is larger than 6 times, rotational stress may remain in the entire steel cord tw (test object) (the test objects in Tables 1 and 2). Ten)). This is because the residual rotational stress of the side wire sw affects the rotational stress of the entire steel cord tw because the residual rotational stress of the side wire sw is large. If the rotational stress remains in the entire steel cord tw, the rubber sheet in which the steel cord tw is embedded is warped by the rotational stress, and the belt member in which the steel cord tw used for an automobile tire or the like is embedded (see FIG. 9)), the production efficiency deteriorates.

  According to the result of the measurement test, the core wire cw does not move by setting the molding rate of the side wire sw to 70% or more and less than 100% and the residual rotational stress of the side wire sw to be twice or more, and It was found that suppression was also achieved (A determination or B determination). It was also found that the rotational stress hardly remains in the entire steel cord tw by making the residual rotational stress of the side wire sw 6 times or less.

  Further, according to the result of the measurement test, if the residual rotational stress of the side wire sw was suppressed to 4 times or less, it was possible to reliably prevent the rotational stress from remaining in the entire steel cord tw.

The overall structure of the steel cord manufacturing equipment is shown. The structure of the preformer is shown. The structure of a rotational stress adjusting device is shown. 1 shows a perspective view of a steel cord in a 1 + 5 configuration. FIG. 1 shows an enlarged cross-sectional view of a steel cord with a 1 + 5 configuration. (A) is an enlarged sectional view of a steel cord having a 1 + 4 configuration, and (B) is an enlarged sectional view of a steel cord having a 1 + 6 configuration. The state of measurement of the wave height of the side wire is shown. It is a graph which shows the result of an evaluation test. The structure of an automobile tire is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Preformer 1a, 1b, 1c Rotating pin 2 Rotational stress adjusting device 2a, 2b Roll 3 Stranding machine cw Steel wire core wire (core wire)
sw Steel wire side wire (side wire)
tw Steel cord (stranded wire)

Claims (2)

In the steel cord in which one steel wire core wire and a plurality of steel wire side wires located around the steel wire core wire are twisted together,
Each of the steel wire side wires is spirally molded with a molding rate of 70% or more and less than 100% ,
Residual rotational stress of 2 to 4 times is applied to each of the steel wire side wires in the same direction as the twist direction of the steel cord.
Steel cord. A composite of the steel cord and rubber or synthetic resin, wherein the steel cord according to claim 1 is embedded in rubber or synthetic resin.

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