JP2007084979A - Steel cord and rubber composite - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide hand belt-reinforcing steel cord at low cost with long service life, usable stably without breakage occurrence over a long period, and to provide a rubber composite reinforced with the steel cord. <P>SOLUTION: The steel cord is to be used for reinforcing the hand belt for passenger-carrying conveyors. The steel cord comprises n strands 31, 31B each of which is made by laying m wires 32, 33, 32B, 33B together, wherein the n strands are laid together oppositely to the direction of laying the m wires. The steel cord has a core space 35 surrounded by the n strands and to be filled with a rubber. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a steel cord for reinforcing a hand belt (handrail) used for a passenger transport conveyor such as an escalator or a moving sidewalk, and a rubber composite reinforced with the steel cord.

  While being driven by a plurality of pairs of pinch rollers 12, the hand belt 10 used for the handrail of the escalator is greatly bent at the turning point R of the endless track and repeatedly undergoes severe bending deformation. In order to be able to withstand this bending deformation load, the hand belt 10 has a multi-layer laminate structure reinforced with a steel cord reinforcing layer 3 as described in, for example, Patent Document 1, and has strength and flexibility. It is supposed to be combined.

  For example, as shown in FIG. 8A, a conventional steel cord 100 for reinforcing a hand belt includes a core strand 103 in which four wires are twisted and six side strands 101 in which four wires 102 are twisted. And. A rubber composite 100A shown in FIG. 8B in which rubber is filled in the center portion of the steel cord 100 is embedded in a rubber sheet and integrated with the rubber, and the decorative rubber layer 7, the canvas 1, 2, 4- When laminated together with 6 and the bead rubber 8, the steel cord reinforcing layer 3 of the hand belt is obtained. In the steel cord reinforcing layer 3 thus produced, the core strand 103 and the side strand 101 are repeatedly deformed inside the cord due to the pinch roll 12 being sandwiched and bending at the turning point R.

  However, in the conventional rubber composite 100A, when the core strand 103 is repeatedly bent and deformed, the elongation of the core strand 103 is smaller than the elongation of the side strand 101. Disconnect to. If the operation is continued in a state in which the core strand constituting wire 102 is disconnected, the flatness of the decorative rubber layer 7 is lost, and in the worst case, the broken wire breaks through the decorative rubber layer 7 and protrudes to the surface. There is a risk that a person may injure his hand. Thus, the hand belt reinforced with the conventional steel core steel cord 100 cannot be said to have sufficient fatigue resistance when subjected to repeated bending deformation, and its life is relatively short.

  Further, in the conventional rubber composite 100A, since the core strand 103 exists in the cord core portion, the rubber does not enter the portion where the core strand 103 and the side strand 101 contact each other, and rust is generated from the portion. There are also problems.

  In order to avoid the protrusion of the core wire, for example, in the steel cord 200 and the rubber composite 200A described in Patent Document 2, as shown in FIGS. By using the fiber core 203 made of nylon or the like, the flexibility of the hand belt is improved, and even if the fiber core 203 is broken, the decorative rubber layer 7 is broken so as not to protrude to the outside.

However, since organic fibers and steel wires have greatly different physical properties such as elongation characteristics and bending rigidity, there is a drawback that a change in the outer diameter of the fiber core at the time of twisting is large, resulting in a large variation in steel cord diameter. Further, since the fiber core steel cord has a larger change in the shape of the fiber core 203 than the steel wire, the twisted shape of the steel cord is difficult to stabilize, and the adjustment and management of its production line is very complicated and difficult, which reduces the production cost. It is a factor that causes an increase.
Japanese Patent No. 3283644 JP 56-169886 A

  The present invention has been made in order to solve the above-described problems. A long-life and low-cost steel cord for reinforcing a hand belt that can be used stably without causing disconnection over a long period of time, and its steel cord. An object is to provide a reinforced rubber composite.

  The steel cord according to the present invention is a steel cord used to reinforce a hand belt for a passenger conveyor, and is formed by twisting m wires each of which is twisted in a direction opposite to the twisting direction of the wires. It is characterized by having n strands that have been combined, and a core space that is surrounded by the n strands and filled with rubber.

A rubber composite according to the present invention is a rubber composite used to reinforce a hand belt for a passenger conveyor, and the rubber composite is substantially parallel to a sheet-like rubber plate at a predetermined interval. A plurality of steel cords embedded in a plate,
Each of the steel cords is formed by twisting m wires, n strands twisted in a direction opposite to the twisting direction of the wires, and the circumference surrounded by the n strands, And a core filled with rubber.

  In the steel cord of the present invention, since the core portion is the core wireless, the problem of the difference in elongation of the constituent wire between the core portion and the side portion itself is eliminated, the flexibility of the entire cord is increased, and the bending performance is improved. . As a result, the endurance (fatigue resistance) of the cord against cycle fatigue in which bending deformation is repeated is improved, and the life of the cord is extended.

  In the steel cord of the present invention, it is preferable that the number m of wires constituting the side strand is an integer of 5-7. This is because the number m of constituent wires needs to be 5 or more in order to obtain the predetermined strength, flexibility and fatigue resistance as a hand belt. On the other hand, when the number of constituent wires m is 8 or more, not only the twisted shape of the steel cord becomes unstable, but also the strand diameter becomes too large, and eventually the cord diameter becomes too large to be embedded in the rubber sheet. This is because the sheet forming becomes difficult, or if the constituent wire is made thin in order to suppress the strand diameter, the strength becomes insufficient and there is a risk of early disconnection. Therefore, in the present invention, the maximum value of the number m of constituent wires is set to seven.

  Moreover, it is preferable that the number n of side strands shall be an integer in any one of 4-6. This is because the number of side strands n needs to be four or more in order to obtain the predetermined strength, flexibility and fatigue resistance as a hand belt. On the other hand, when the number of side strands n is 7 or more, not only is the structure unstable as a cord having a space in the center, but the cord diameter becomes too large to be embedded in the rubber sheet, making sheet molding difficult. Because it becomes. Therefore, in the present invention, the maximum number of side strands n is set to six.

In addition, the material of the constituent wire can be a piano wire (strength level 250 kg / mm ² or more, carbon content 0.72 to 0.82 mass%) defined in JIS G3502.

  According to the present invention, in a passenger transport conveyor such as an escalator, a long-life steel cord that can be used stably over a long period of time without disconnection, and a hand belt including a rubber composite reinforced with the steel cord Is provided.

  According to the present invention, since the flexibility and bending fatigue resistance of the hand belt are improved, the pressing force by the pinch roller can be set large, and the number of pinch rollers can be reduced as compared with the conventional art. Moreover, when the number of pinch rollers is the same, the path of the passenger transport conveyor can be set longer than before.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 2, the hand belt 10 according to the present embodiment is used for a handrail of an escalator having two turning points R, and is driven along an endless track by 4 to 12 pairs of pinch rollers 12. It has become so. The pinch roller 12 includes a drive wheel biased by a spring so as to press one side of the hand belt 10 and a backup roller in contact with the other side of the hand belt 10. For example, it supports so that conveyance is possible at 60-100 kg / cm < ² >). The hand belt 10 is loaded with a tension of about 300 kg in the longitudinal direction so as not to easily fall off from the guide rail.

  As shown in FIG. 1A, the hand belt 10 is formed by laminating canvases 1 and 2 as cushioning materials, steel cord reinforcing layers 3 as reinforcing materials, canvases 3 to 6 and a decorative rubber layer 7 in order from the inside. A multilayer laminate structure. By attaching the bead rubber 8 to the end portion of the hand belt 10, the hand belt 10 is maintained in the cross-sectional shape as shown in the drawing.

  As shown in FIG. 1B, the steel cord reinforcing layer 3 is made of a rubber sheet in which a rubber composite 30A is embedded at a predetermined pitch interval. Each of the rubber composites 30 </ b> A is a tension bar that handles a part of the tension applied to the hand belt, and is therefore calendared in parallel with the length of the hand belt 10. For example, as shown in FIG. 3B, the rubber composite 30A is obtained by filling a rubber 39 in the central portion of a 5 × 5 steel cord 301 shown in FIG.

Example 1
Next, the steel cord 301 and the rubber composite 30A of Example 1 will be described.

  As shown in FIG. 3A, the steel cord 301 according to the first embodiment has a center space 35 as a planned space to be filled with the rubber 39. Around the center space 35, five side strands 31 are arranged at substantially equal intervals. The side strand 31 is formed by S-twisting four wires 33 having the same diameter around one core wire 32. The steel cord 301 is formed by Z-twisting the five side strands 31. Further, the steel cord 301 is sandwiched between the rubber sheets, and the rubber 39 is infiltrated into the cord by heating / pressing from above and below to form the rubber filling core portion 36 filled with rubber in the core space 35, as shown in FIG. A rubber composite 30A shown in (b) was obtained.

(Example 2)
Next, the steel cord 302 and the rubber composite 30B of Example 2 will be described.

  As shown in FIG. 4A, the steel cord 302 of the second embodiment has a center space 35 as a planned space to be filled with the rubber 39. Around the center space 35, five side strands 31B are arranged at substantially equal intervals. The side strand 31B is formed by S twisting six wires 33B having the same diameter around one core wire 32B. The steel cord 302 is formed by Z-twisting the five side strands 31B. Further, a rubber-filled core portion 36 filled with rubber was formed in the core space 35 to obtain a rubber composite 30B shown in FIG.

(Comparative Example 1)
Next, the steel cord 303 and the rubber composite 30C of Comparative Example 1 will be described.

  As shown in FIG. 5A, the steel cord 303 of Comparative Example 1 has a core strand 35C at the center, and five side strands 31C are arranged at substantially equal pitch intervals around the core strand 35C. The core strand 35C is made of three twisted wires having the same diameter. The side strand 31C is formed by S twisting six same-diameter wires 33C around a single core wire 32C. A steel cord 303 of Comparative Example 1 was obtained by Z-twisting the five side strands 31C around the core strand 35C. Furthermore, using the steel cord 303, a rubber composite 30C shown in FIG.

(Conventional example 1)
Next, the steel cord 100 and the rubber composite 100A of Conventional Example 1 will be described.

  As shown in FIG. 8A, the steel cord 100 of the prior art example 1 has a core strand 103 at the center, and six side strands 101 are arranged at substantially equal pitches around the core strand 103. The core strand 103 is formed by S twisting four wires having the same diameter. The side strand 101 is formed by S-twisting four wires 102 having the same diameter. With the core strand 103 as the center, the six side strands 101 were Z-twisted around the core strand 103 to obtain the steel cord 100 of Conventional Example 1. Furthermore, using the steel cord 100, a rubber composite 100A shown in FIG.

(Conventional example 2)
Next, the steel cord 200 and the rubber composite 200A of Conventional Example 2 will be described.

  As shown in FIG. 9 (a), the steel cord 200 of Conventional Example 2 has a fiber core 203 at the core, and six side strands 201 are arranged at substantially equal pitches around the fiber core 203. The fiber core 203 is a monofilament of nylon fiber (material: nylon 6, diameter: 0.54 mm). The side strand 201 is formed by S twisting four same-diameter wires 202. With the fiber core 203 as the center, six side strands 201 are Z-twisted around the fiber core 203 to obtain a steel cord 200 of Conventional Example 2. Furthermore, using the steel cord 200, a rubber composite 200A shown in FIG.

  Next, the case where the steel cord 30B of Example 2 is manufactured will be described as an example.

(Manufacture of steel cord)
First, a wire (0.98 mm in diameter) brass-plated on a piano wire defined in JIS G3502 was drawn into a 0.155 mm strand. The strands were fed from 7 feeding reels to a buncher stranding machine, and 7 strands having the same diameter were collectively twisted to produce a side strand 31B having a (1 + 6) configuration. At this time, the twist direction was S and the twist pitch was 6.0 mm.

  Next, the (1 + 6) configuration side strand 31B is fed from the five supply reels to the buncher stranding machine, and the five side strands 31B are twisted together to form a 5 × 7 (1 + 6) configuration steel cord (coreless structure). 30B was obtained. At this time, the twist direction was Z, and the twist pitch was 12.7 mm. The diameter of the steel cord 30B finally obtained was 1.26 mm.

(Manufacture of rubber composites)
The steel cord 30B having a 5 × 7 (1 + 6) structure thus obtained was cut into a length of 150 mm, and the cut five steel cords 30B were rubber sheets (thickness 1 mm, width 30 mm, A grip margin L2 of 20 mm at both ends was secured on the length 140 mm), and laid in parallel at a pitch of 5 mm. Therefore, the length L1 of the free steel cord excluding the gripping margins at both ends is 100 mm.

  Next, this is covered with a rubber sheet having a thickness of 1 mm, and a steel cord is sandwiched in a sandwich shape and vulcanized. The vulcanization temperature was about 130 ° C. After the vulcanization molding, the steel cord protruding outside the rubber sheet was cut and removed. In this way, a rubber composite 40 was obtained.

(Evaluation test method)
Next, a bending bending fatigue test for evaluating the durability of the rubber composite produced as described above will be described with reference to FIG.
The rubber composite 40 was used as a test sample, which was used as a bending test piece. In a state where both ends of the bending test piece 40 are clamped by the pair of chucks 42, the mutual distance between the chucks 42 is approached from the position shown in FIG. 7A to the position shown in FIG. Repeated at cycle / second (1 round trip 0.5 seconds). That is, the distance L1 from the grip end portion to the end portion of the bending test piece 40 at the time of extension shown in FIG. 7A is set to 100 mm, and the grip end of the bending test piece 40 at the time of bending shown in FIG. The distance L3 from the part to the end was set to 50 mm. When the number of repetitions reached a specified value (for example, 10,000 times), the test was stopped, the test piece 40 was disassembled, and the steel cord 30B was taken out. The residual strength F ₂ of the steel cord 30B taken out was measured with a tensile tester. The ratio F (= F ₂ / F ₁ ) between this measured value F ₂ and the strength F ₁ of an untested steel cord not subjected to the bending bending fatigue test is obtained, and the percentage of the ratio F is taken to evaluate the bending fatigue resistance. Was done.

(Evaluation test results)
Table 1 shows the evaluation test results.
As Conventional Example 1, a rubber composite 100A including a steel cord having a structure of 7 × 4 × 0.175 was used. As Conventional Example 2, a rubber composite 200A including a steel cord having a nylon core + 6 × 4 × 0.175 configuration was used.

  As Example 1, a rubber composite 30A including a steel cord having a structure of 5 × 5 × 0.155 was used. As Example 2, a rubber composite 30B including a steel cord having a configuration of 5 × 7 × 0.155 was used.

  As Comparative Example 1, a rubber composite 30C including a steel cord having a configuration of 1 × 3 + 5 × 7 × 0.15 was used.

  Bending fatigue resistance was evaluated using the ratio of the conventional example 1 as a reference (100).

  The bending fatigue resistance indexes of Examples 1 and 2 were 157 and 162, both significantly exceeding the result (110) of Comparative Example 1.

  Incidentally, the bending fatigue resistance index (110) of Comparative Example 1 is improved from that of Conventional Example 1 (100) as a reference, but is smaller than the result (120) of Conventional Example 2.

Conventional example 2 has many occurrence frequency of the twist defect.

  The present invention can be used to reinforce hand belts (handrails) of passenger conveyors such as escalators and moving walkways.

(A) is sectional drawing which cuts and shows a part of hand belt, (b) is sectional drawing which shows the steel cord reinforcement layer of a hand belt. The side view which shows typically the escalator in which a hand belt is used. (A) is sectional drawing which shows the steel cord of the Example of this invention, (b) is sectional drawing which shows the rubber complex of the Example of this invention. (A) is sectional drawing which shows the steel cord of the other Example of this invention, (b) is sectional drawing which shows the rubber complex of the other Example of this invention. (A) is sectional drawing which shows the steel cord of a comparative example, (b) is sectional drawing which shows the rubber complex of a comparative example. The perspective view which shows the test piece which consists of a steel cord embedding rubber sheet. (A) is a figure which shows the test piece hold | gripped with the chuck | zipper of a testing machine, (b) is a figure which shows the test piece bent. (A) is sectional drawing which shows the conventional steel cord, (b) is sectional drawing which shows the conventional rubber composite. (A) is sectional drawing which shows the other conventional steel cord, (b) is sectional drawing which shows another conventional rubber composite.

Explanation of symbols

1, 2, 4 to 6 ... canvas (cushion material), 3 ... steel cord reinforcing layer, 7 ... decorative rubber layer, 8 ... bead rubber,
10 ... hand belt (handrail), 12 ... pinch roller,
35C, 103 ... core strand (steel core), 203 ... fiber core,
100, 200, 301, 302, 303 ... steel cord,
30A, 30B, 30C, 100A, 200A ... rubber composite,
31, 31B, 31C, 101, 201 ... side strands,
32, 32B, 32C, 33, 33B, 33C, 102, 202 ... wire,
35 ... heart space, 36 ... rubber-filled core, 39 ... rubber,
40: bending test piece (rubber composite, rubber sheet), 42: chuck.

Claims (4)

A steel cord used to reinforce a hand belt for a passenger conveyor,
N strands each formed by twisting m wires, and twisted in a direction opposite to the twisting direction of the wires,
A steel cord having a core space surrounded by the n strands and filled with rubber. The steel cord according to claim 1, wherein m is an integer of 5 to 7, and n is an integer of 4 to 6. A rubber composite used to reinforce a hand belt for a passenger conveyor,
A sheet-like rubber plate;
A plurality of steel cords embedded in the rubber plate so as to be substantially parallel at a predetermined interval; and
The steel cord is
N strands each formed by twisting m wires, and twisted in a direction opposite to the twisting direction of the wires,
A rubber composite having a core part surrounded by the n strands and filled with rubber. The rubber composite according to claim 3, wherein m is an integer of 5 to 7, and n is an integer of 4 to 6.

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