JPH09301231A - Elastic crawler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a steel cord, which is embedded in a crawler body and serves as a tension member, from being broken. SOLUTION: The core strand 7 of this elastic crawler 1 formed by embedding, in an endless crawler body 2 consisting of elastic members, steel cords 3 where a plurality of side strands 8 are twisted outside a core strand 7 so as to be endless in the band longitudinal direction has a twisted structure of two or more layers consisting of two or more core-wires 7A and a plurality of side wires 7B twisted around them. The twisting coefficient Kc of the core-wire 7A satisfies a condition of 12.0<=Kc<=30.0, and the twisting coefficient Kj of the side wire 7B satisfies a condition of 12.0<=Kj(R)65.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastic crawler used as a traveling device for agricultural machines, construction machines, snow vehicles, various transport vehicles, and the like, and more particularly to a tensile body embedded in the elastic crawler body. It is related to the improvement of the steel cord as.

[0002]

2. Description of the Related Art In an elastic crawler in which an endless strip-shaped crawler body made of an elastic material is embedded with a steel cord in which a core strand and a plurality of side strands are twisted on the outside in an endless strip in the longitudinal direction of the strip. Since a steel cord is required to have good bending fatigue resistance and high cord strength, a 7 × n structure (for example, 7 × 12 structure) is generally adopted.

In order to prevent core slippage and prevent rusting, the present applicant has proposed a technique in which the diameter of the core wire forming the core strand is 1.04 times or more the diameter of the side wire in contact with the core wire. Have been proposed (see JP-A-7-69253).

[0004]

In the case of a steel cord of 7 × n structure, six bundles of side strands are twisted around a core strand, and the core strand itself is linearly arranged in the center of the cord. Therefore, the core strand may be broken due to the compressive bending stress generated on the inner peripheral side of the overlapped portion of the steel cord, and in some cases, the cord may be broken to eventually lead to crawler cutting. there were.

Therefore, in the present invention, by specifying the twisting coefficient of the core wire and the side wire constituting the core strand, the core strand absorbs the compressive bending stress by the spring effect to prevent the cord from breaking. is there.

[0006]

According to the present invention, a steel cord 3 in which a plurality of side strands 8 are twisted outside a core strand 7 is provided in a crawler main body 2 made of an elastic material and having an endless strip shape. The elastic crawler 1 is embedded in the endless shape, and the following technical measures are taken in order to achieve the above-mentioned object.

That is, according to the present invention, the core strand 7
Has a layer twist structure of two or more layers consisting of two or more core wires 7A and a plurality of side wires 7B twisted around this, and the twist coefficient Kc of the core wires 7A is 12.0 ≦ Kc. ≤3
Satisfies the condition of 0.0, and further, twist coefficient K of the side wire 7B
An elastic crawler characterized in that j satisfies the condition of 12.0 ≦ Kj ≦ 65.0.

Where Kc = Pc / Dc, where Pc is the twist pitch (mm) of the core wire, and Dc is the filament diameter (mm) of the core wire.
And Kj = Pj / Dj and Pj is the twist pitch (m
m) and Dj are filament diameters (mm) of the lateral lines. When Dc is 0.20 mm and Dj is 0.20 mm, P
c is 5.0 mm, Pj is 10.0 mm, and Kc is 25.
0, Kj is preferably set to 50.0, and further, when Dc is 0.20 mm and Dj is 0.20 mm, P
c is 3.5 mm, Pj is 5.0 mm and Kc is 17.5,
It is desirable that Kj be 25.0.

By adopting the above construction, the core strand 7 absorbs the compressive bending stress by the spring effect and prevents the core strand 7 from breaking.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 (1) and (2), an elastic crawler 1 according to the present invention has a steel cord 3 embedded in an endless strip-shaped crawler body 2 made of an elastic material such as rubber or other elastomer in the longitudinal direction of the strip. are doing.

A plurality of steel cords 3 are driven into the outer periphery of a horizontal reinforcing body (core bar) 4 arranged in the crawler main body 2 at intervals in the longitudinal direction of the band, and one end 3A thereof is formed. And the other end 3B overlap at the joint. The crawler body 2 is wound around a drive sprocket 5 and a driven sprocket (not shown), and a lug 6 is provided on the ground side in correspondence with the lateral reinforcement 4 having a guide protrusion 4A.
Is provided integrally.

The steel cord 3 is formed by twisting six side strands 8 in the figure on the outside of the core strand 7 as shown in FIG. 1 (3). In the figure, the core strand 7 has a layered structure of two or more layers consisting of three side wires 7A and nine side wires 7B, and the side strands 8 also have 9 layers around the three core wires 8A. It has a layer-twisted structure of two or more layers composed of the side wires 8B of the book.

The twisting coefficient Kc of the core wire 7A in the core strand 7 is set to 12.0≤Kc≤30.0,
The twist coefficient Kc is Pc / Dc, where Pc is the twist pitch (mm) of the core wire 7A, and Dc is the filament diameter (m of the core wire 7A.
m). Here, the value of the twist coefficient Kc is set to 12.0 or more. When the twist coefficient Kc is less than 12.0, it is difficult to apply the twist, the production effect is poor, the cost is high, and the strength is reduced by the twist. On the other hand, Kc
The value of 3 is set to 30.0 or less because if it exceeds 30.0, it is difficult to absorb the compressive bending stress by the spring effect.

Further, the twist coefficient Kj of the side wire 7B in the core strand 7 is set to 12.0≤Kj≤65.0, and the twist coefficient Kj is Pj / Dj, and Pj is the twist pitch (mm). ) And Dj are filament diameters (mm). Here, the value of the twist coefficient Kj is set to 12.0 or more. If the twist coefficient Kj is less than 12.0, it is difficult to twist, the production effect is poor, the cost is high, and the strength is reduced by twisting. This is because the value of Kj becomes 65.
The reason why it is set to 0 or less is that when it exceeds 65.0, the effect of absorbing the compressive bending stress is lost.

Unlike Kc, 30.0 <Kj ≦ 6
Even with 5.0, the effect is that the filament of the side wire 7B is twisted around the core wire 7A, so that the twist angle of the filament with respect to the longitudinal direction of the cord becomes large and 30.0 <K
This is because even if j ≦ 65.0, the compressive bending stress is absorbed and the breakage of the core strand 7 is prevented.

[0016]

EXAMPLE (3 + 9 × 0.20) +6 (1 × 12 × 0.
20) Steel cord crawler size 55 (width) c
The following table shows the number of broken core strands in the overlapped portion between Example 1 and Example 2 and Comparative Examples 1 and 2 when embedded at m-90 (pitch) mm × 56 (number of links) with 30 driving lines. Shown in 1.

However, the number of breakages was run for 600 hours in an actual machine, and after running, the cord was taken out and investigated.

[0018]

[Table 1]

As is clear from Table 1 above, the number of breaks was 0 in Examples 1 and 2 of the present invention, whereas the total number of breaks was 35 in Comparative Example 1 and 20 in Comparative Example 2.
It was a book. Although the number of the core strands 7 is three in the embodiment, this may be a plurality of two or more.

[0020]

As described in detail above, according to the present invention, the breakage of the core strand due to the compressive bending stress generated on the inner peripheral side of the wound portion is relieved by the spring effect of the strand. By absorbing it, it can be surely prevented, and an elastic crawler with high durability can be provided here.

[Brief description of drawings]

1 shows an embodiment of the present invention, (1) is a cross-sectional view of a crawler winding portion, (2) is an AA enlarged cross-sectional view of (1),
(3) is a sectional view of a steel cord, and (4) is a sectional view of a core strand.

[Explanation of symbols]

 1 Elastic Crawler 2 Crawler Main Body 3 Steel Cord 7 Core Strand 7A Core 7B Side Wire

Claims (3)

[Claims] 1. A steel cord (3) having a plurality of side strands (8) twisted outside a core strand (7) in an endless strip-shaped crawler body (2) made of an elastic material. An elastic crawler (1) embedded as an endless structure in the core strand (7), comprising two or more core wires (7A),
2 consisting of multiple side wires (7B) twisted around this
It has a layer twist structure of more than one layer, the twist coefficient Kc of the core wire (7A) satisfies the condition of 12.0 ≦ Kc ≦ 30.0, and the twist coefficient Kj of the side wire (7B) is 12. 0 ≦
An elastic crawler, which satisfies the condition of Kj ≦ 65.0. However, Kc = Pc / Dc, where Pc is the twist pitch of the core wire (mm), and Dc is the filament diameter of the core wire (m
m), Kj = Pj / Dj, Pj is the twist pitch (mm) of the side wire, and Dj is the filament diameter (mm) of the side wire. 2. The Dc is 0.20 mm and the Dj is 0.2.
Pc is 5.0 mm at 0 mm and Kc is Pj at 10.0 mm
Is 25.0 and Kj is 50.0. The elastic crawler according to claim 1, wherein 3. The Dc is 0.20 mm and the Dj is 0.2.
The elastic crawler according to claim 1, wherein Pc is 3.5 mm at 0 mm, Pj is 5.0 mm, Kc is 17.5, and Kj is 25.0.