JP4551820B2 - Flat wire for rubber reinforcement - Google Patents

Description

  The present invention is used to form a reinforcing layer by being spirally wound and embedded in various high-pressure hoses or braided and embedded in a blade shape, and is embedded in a rubber layer of a steel radial tire to form a reinforcing layer. The present invention relates to a flat wire for reinforcing rubber used in the manufacturing.

  Conventional high-pressure hoses are composed of tube rubber, cloth layer, interlayer rubber, wire reinforcement layer, cotton blade, cover rubber, etc., and the wire reinforcement layer is a round wire having high tensile strength drawn by cold working. A high carbon steel wire (circular cross section) is used as the hose wire, and a large number of hose wires are spirally wound or embedded in a rubber hose, or braided and embedded to increase the pressure resistance of the hose. It is the main rubber reinforcement mechanism.

  Patent Document 1 and Patent Document 2 make it possible to use a flat wire for the wire reinforcement layer of the high-pressure hose so that the wire filling degree of the wire reinforcement layer is larger than the limit value of 78.5% when using a round wire. The company proposes technologies to improve both pressure resistance and flexibility of high-pressure hoses.

Patent Document 3 proposes a technique of using a flat wire for the wire reinforcing layer of the high-pressure hose to prevent the wire from biting into the inner rubber layer and to prevent the tube pinhole.
JP-A-6-201077 JP-A-6-331069 JP-A-8-188776

  However, depending on the shape of the conventional flat wire 2B, as shown in FIG. 9A, the angle θ of the edge portion 23 corresponding to the boundary between the flat portion 21 and the curved portion 22 becomes sharp. As shown in FIG. 9B, separation of the rubber adhesive layer 28 from the wire is likely to occur at the edge portion 23 as shown in FIG. Further, the other wires 2B adjacent to the edge portion 23 of the flat wire 2B come into contact with each other and rub against each other, and as shown in FIG. 9C, fretting wear 9 is likely to occur. As described above, even with a flat wire, there is a problem that the occurrence of fretting and separation cannot be sufficiently prevented.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a flat wire for reinforcing rubber that can prevent separation and can reduce fretting wear between wires.

  With reference to FIG.1 (b), the geometric calculation method of edge angle (theta) in a flat wire cross section is demonstrated roughly.

  The cross-sectional shape of the flat wire is a track shape surrounded by a pair of flat portions 21 and a pair of curved portions 22. The contour of the curved portion 22 has a perfect circular arc shape or a pseudo arc shape approximated thereto. First, a center line LC that bisects the wire is drawn between the two lines L1 and L2 along the flat portion 21, and a point where the center line LC intersects with the contour of the curved portion 22 is defined as a B point. Next, a middle point C that bisects the line segment AB connecting the point B and the edge point A is obtained, a perpendicular line perpendicular to the line segment AB is drawn from the middle point C, and a point D where the perpendicular line intersects the center line LC is obtained. Ask. Next, a line L3 (tangent line) orthogonal to the line segment DA connecting the point D and the edge point A is drawn. An angle θ sandwiched between the tangent line L3 and the line L1 along the flat portion 21 is defined as an edge angle.

  The edge angle θ defined in this way greatly affects the adhesive force between the flat wire and the rubber. As a result of repeating the verification test by repeating earnest research on the relationship between the cross-sectional shape of the flat wire and the adhesive force of the rubber adhesive layer, the present inventor has controlled the separation of the edge angle θ in the range of 142 ° to 163 °. It has been found that since the surface pressure between the wires is less likely to occur and the fretting wear is less likely to occur (Table 1). The present invention has been made based on such findings.

  The flat wire for reinforcing rubber according to the present invention has a pair of flat portions and a pair of curved portions formed by flattening a round wire, and transitions from the flat portions to the curved portions in the projection field of the wire cross section. The edge angle θ of the portion to be adjusted is in the range of 142 ° to 163 °.

  When the edge angle θ is less than 142 °, the local stress concentration is increased and separation is likely to occur, and fretting wear between wires is likely to occur. On the other hand, when the edge angle θ exceeds 163 °, the wire circumferential length WL becomes small, so that the contact area between the wire and the rubber cannot be increased, and the effect of improving the adhesive strength cannot be obtained.

  The generation of fretting between wires and the adhesive force between wire / rubber will be described with reference to FIGS. 6 and 7 by comparing round wire and flat wire.

  As shown in FIG. 6 (a), the conventional round wire has a high surface pressure per unit area between the wires 2, and thus is susceptible to fretting. On the other hand, as shown in FIG. 6B, the flat wire has a low surface pressure per unit area between the wires 2A and hardly causes fretting.

  Further, as shown in FIG. 7B, the flat wire 2A has a high adhesive force with the rubber because the wire circumferential length WL becomes long. For this reason, the adhesive layer between the wire / rubber is not easily broken, and separation is unlikely to occur. Assuming that the adhesive force per unit length is constant, the absolute value of the rubber adhesive force of the flat wire 2A is larger than that of the round wire 2 by the amount of the increase in the wire circumferential length WL.

  Further, the flat wire of the present invention is formed by flattening a round wire by pressing down from the vertical direction using a flat profile roller.

  In addition, the flat wire of the present invention is flattened by flattening a round wire by using a flat profile roller and then flattening by using a curved profile roller to adjust the cross-sectional shape of the transition part. It has been.

  In the flat wire of the present invention, the cross-sectional shape of the transition portion is adjusted using a multi-stage rolling mill in which the planar profile rollers and the curved profile rollers are alternately arranged.

  According to the present invention, since the local stress concentration is reduced at the edge portion, separation in which the wire / rubber adhesive layer is separated is less likely to occur, and the surface pressure between the wires is reduced, thereby reducing fretting wear. It becomes difficult to occur.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  FIG. 2 is a block diagram showing the outline of the flattening apparatus. A round wire 2 is supplied continuously or intermittently from a wire feeding device (not shown) toward the wire drawing machine 3 and drawn to a predetermined diameter by the wire drawing machine 3. For the round wire 2 as a raw material, a piano wire equivalent to SWRS72A or SWRS82A defined in JIS G3502 was used. For the round wire 2, for example, a high carbon steel wire containing 0.72% by mass of carbon is subjected to copper and zinc plating by a diffusion plating method and then heat-treated to form an alloy, whereby Cu = 63. It is also possible to use a wire having a predetermined wire diameter that is plated with 5% and the adhesion amount = 5.0 g / kg, and this wire is drawn into a small diameter sequentially several times by a die. .

  A flattening device 4, a take-up capstan 7 and a winder 8 are arranged in this order along a path line on the outgoing side of the wire drawing machine 3. The flattening device 4 includes a plurality of processing rollers that reduce the wire 2 coming out of the wire drawing machine 3 from above and below to obtain a flat wire having a desired flatness ratio, and setting the edge portion of the flat wire to a desired edge angle θ. ing.

  Various combinations of the plurality of processing rollers included in the flattening device 4 are possible. For example, three flattening rollers 5 may be arranged in series as shown in FIG. 3A, or one flattening roller 5 (planar profile roller) as shown in FIG. 3B. Later, one side roller 6 (curved profile roller) may be arranged, and as shown in FIG. 3 (c), the flattening roller 5 and the side roller 6 are arranged alternately so that a tandem rolling mill is provided. You may make it comprise. In the first combination roller, the edge angle θ is controlled by controlling the short diameter DS (= control of the flatness ratio).

  In the second and third combination rollers, the edge angle θ is controlled by adjusting the reduction amount of the planar profile roller 5, the shape of the curved profile roller, and the reduction amount. That is, as shown in FIG. 4, the flattening roller 5 which is a flat profile roller flattens the round wire by vertically reducing the wire from above and below, and the side roller 6 which is a curved profile roller horizontally flattens the wire from the left and right. The shape of the edge portion of the wire is corrected by reducing. The roller surface of the side roller 6 is formed in a three-dimensional shape capable of adjusting the curved portion of the wire to a desired shape (arc or pseudo arc profile) and correcting the flattened edge portion of the wire to an unsharp shape. Yes. In such a tandem rolling mill, the operations of flattening → edge shape correction → flattening → edge shape correction are smoothly performed by the flattening roller 5 and the side roller 6 without congestion.

  In the present embodiment, the round wire 2 is rolled by a flattening roller immediately after being drawn by passing the die of the wire drawing machine 3, and further the shape of the curved portion 22 is formed by the side roller 6. The shape of the edge portion 23 is adjusted. Thus, after flattening → edge shape correction → flattening → edge shape correction in the order of tandem rolling, the flat wire 2 </ b> A is wound around the drum-shaped winder 8.

  FIG. 5 shows the flatness ratio H when the flatness ratio H (%) is taken on the horizontal axis, the wire circumference WL (mm) is taken on the vertical axis, and the flatness ratio H is variously changed for a wire having a diameter of 0.35 mm. It is a characteristic diagram which shows a correlation with wire circumference length WL. As is apparent from the figure, as the flatness ratio H decreases, the wire circumferential length WL increases.

Table 1 shows the initial diameter D ₀ , major diameter DL, minor diameter DS, flatness ratio H, tensile strength, edge angle θ, and drawing force of Examples 1 to 10 and Comparative Examples 1 to 9, respectively.

The initial diameter D ₀ was set to 0.35 mm and 0.36 mm.

The tensile strength was 2497 to 2830 N / mm ² .

  The long diameter DL is measured using a micrometer, or a wire sample is embedded in a resin, and the cut surface of the wire (cross section perpendicular to the wire longitudinal direction) is photographed and measured using the photograph image. .

  Similarly, the short diameter DS is measured using a micrometer, or a wire sample is embedded in a resin, the cut surface of the wire (cross section perpendicular to the wire longitudinal direction) is photographed, and the photograph image is used. Measured.

  The flatness ratio H was obtained by calculation from the measured major axis DL and minor axis DS using the formula H = (DS / DL) × 100.

  The flat portion length F was measured by embedding a wire sample in a resin, taking a photograph of a cut surface of the wire (cross section perpendicular to the longitudinal direction of the wire), and using the photograph image.

  As described above, the edge angle θ is geometrically calculated using the wire cross-sectional view shown in FIG.

  The arc length AL corresponds to the contour length of the curved portion 22 and was obtained by calculation as follows. However, X is the length of the line segment DA in FIG.1 (b).

AL = 2πX × (2α / 360) = πX × (α / 90) (1)
X = (DS / 2) / sin α = DS / 2 sin (θ−90) (2)
From equations (1) and (2)
AL = π × {DS / 2sin (θ−90)} × (α / 90)
= DSπ (θ−90) / 180sin (θ−90) (3)
The wire peripheral length WL was obtained by the following equation.

WL = 2 (AL + F) (4)
In each sample shown in Table 1, Comparative Example 1 is a round wire, Examples 1 to 3, 5, 7 to 10, and Comparative Examples 5 to 9 are the combination rollers of FIG. 3 and 4 and Comparative Examples 2 to 4 are manufactured by the combination roller of FIG. 3 (c) (tandem rolling in the order of flattening → edge shape correction → flattening → edge shape correction). Flat wire.

  These sample wires were manufactured into various types of hose wires, and the pulling force was evaluated using the method shown in FIGS. 8A to 8D described later for the rubber reinforcing layer formed by the respective hose wires. Each of the flat wires of Examples 1 to 10 having an edge angle θ in the range of 142 ° to 163 ° exceeded the pulling force of the round wire of Comparative Example 1 serving as a reference.

The wire pulling force was measured as follows using the evaluation method shown in FIGS.
First, the sample wires 2A cut to an appropriate length are arranged at appropriate intervals, and vulcanized and molded so as to be positioned at the center of the rubber block 28 having a cross section of 12.7 mm × 12 mm. Prepare the test piece shown in. Next, as shown in FIGS. 8B and 8C, the wire terminal on one side is cut at a position flush with the surface of the rubber block 28. As shown in FIG. 8D, the other wire terminal is held by a jig of a drawing tester (not shown), and a wire 2A is drawn from the rubber block 28 by applying a drawing force in the wire longitudinal direction. The maximum load when the wire 2A was pulled out from the rubber block 28 was measured and evaluated as the pulling force.

  In the above embodiment, the case where the wire is spirally wound and embedded in the rubber hose has been described, but the present invention is not limited to this, and the wire is braided and embedded in the rubber hose. The present invention can also be applied.

  In the above embodiment, the case of the rubber hose has been described. However, the present invention is not limited to this. The present invention is also applicable to reinforcing the rubber layer by embedding a wire in the rubber layer of the steel radial tire. Can be applied.

  The flat wire for reinforcing rubber of the present invention can be used as a reinforcing member for a high-pressure hose through which a high-pressure fluid flows, for example, a fire hose, a water jet cutter hose, or a hydraulic hose. The flat wire for reinforcing rubber of the present invention can be used to form a reinforcing layer by being embedded in a rubber layer of a steel radial tire.

(A) And (b) is a cross-sectional view which shows the hose wire for rubber reinforcement of this invention, respectively. The block diagram which shows the outline | summary of a flat processing apparatus. (A) is a figure which shows the processing roller provided in the flattening apparatus, (b) is a figure which shows another processing roller, (c) is a figure which shows another processing roller. The expanded sectional view which shows the wire rolled alternately by the flattening roller and the side roller. The characteristic diagram which shows the relationship between flatness H and wire peripheral length WL. (A) is a cross-sectional schematic diagram for demonstrating the surface pressure of a round wire, (b) is a cross-sectional schematic diagram for demonstrating the surface pressure of a flat wire. (A) is a cross-sectional schematic diagram which shows the round wire embedded in rubber | gum, (b) is a cross-sectional schematic diagram which shows the flat wire embedded in rubber | gum. (A)-(d) is a schematic diagram for demonstrating the procedure which measures and evaluates the pulling force when pulling out the embedded wire from rubber | gum. (A)-(c) is a cross-sectional schematic diagram which respectively shows the conventional flat wire.

Explanation of symbols

2 ... Round wire,
2A, 2B ... flat wire,
3 ... Wire drawing machine,
4 ... Flattening device,
5. Flattening roller (planar profile roller, processing roller)
6 ... side rollers (curved profile rollers, processing rollers),
7 ... take-up capstan,
8 ... winding machine,
21 ... Flat part, 22 ... Arc part, 23 ... Edge part, 28 ... Rubber,
DL ... major axis, DS ... minor axis,
F: Flat part length,
θ: Edge angle.

Claims (4)

  It has a pair of flat portions and a pair of curved portions formed by flattening the round wire, and the edge angle θ of the portion that transitions from the flat portion to the curved portion in the projection field of the wire cross section is 142 ° to 163. A flat wire for reinforcing rubber characterized by being in the range of °.   2. The flat wire for reinforcing rubber according to claim 1, wherein the round wire is flattened by being flattened by using a flat profile roller.   The flat cross-sectional shape of the transition region is adjusted by flattening a round wire by flattening from a vertical direction using a flat profile roller, and then flattening from a horizontal direction by using a curved profile roller. The flat wire for reinforcing rubber according to 1.   2. The flat wire for reinforcing rubber according to claim 1, wherein a cross-sectional shape of the transition portion is adjusted using a multi-stage rolling mill in which the flat profile rollers and the curved profile rollers are alternately arranged.

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