JP2003278085A - Cord for elastic crawler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent running off of a core of core strand of cord for crawler. <P>SOLUTION: The cord for elastic crawler has a core strand 9 composed of a core 10 formed by twisting three core filaments 10A, a first sheath 11 formed by twisting 6 side filaments 11A arranged around the core 10 and a second sheath 12 formed by twisting 12 side filaments 12A and having a structure of 1×3+6+12, and percent of a diameter d1 of the core 10 of the core strand 9 is 110-125% based on a diameter d2 of the side filament 11A constituting the first sheath 11. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cord for an elastic crawler used in a crawler type traveling device employed in a traveling section of an agricultural machine, a construction machine, an automobile, or the like. It is. 2. Description of the Related Art A crawler-type traveling device is mainly constructed by, for example, winding a crawler belt around a driving wheel (sprocket), an idler, and a plurality of rolling wheels, and rotating the driving wheel. The crawler belt is configured to run by being driven to circulate around the crawler belt in the circumferential direction. As a crawler belt of the crawler-type traveling device, there is an elastic crawler having a main body made of a rubber-like elastic body. As shown in FIGS. 3 and 4, the elastic crawler 1 includes a crawler body 2 formed in an endless belt shape by an elastic body, for example.
The core metal 3 is buried at intervals in the circumferential direction A, and a tensile member 4 surrounding the core metal 3 is buried in the circumferential direction A (the core metal 3 is buried). Not all). A lug 5 is provided on the outer peripheral side of the crawler main body 2, and an engagement protrusion 6 for preventing the wheel from being dislodged (separation of the elastic crawler) is provided on the inner peripheral side of the crawler main body 2. . The tensile member 4 is constituted by, for example, arranging a plurality of endless cords 7 wound one turn in the crawler circumferential direction A in parallel in the crawler width direction B. The cord 7 is formed into an annular shape by overlapping (lap joint) the end portions 7a so as to wrap in the crawler thickness direction C.
As the cord 7 constituting the tensile member 4, there is a cord formed by twisting six side strands around one core strand (for example, a 7 × 19 structure, around the core strand). The core strand 9 of the elastic crawler cord 7 is generally composed of one core filament as shown in FIG. A core 10, a first sheath 11 formed by twisting six side filaments 11A arranged around the core 10, and twelve side filaments arranged around the first sheath 11. 1 + 6 composed of a second sheath 12 formed by twisting 12A.
It has a +12 strand structure. [0005] Since the core 10 of the core strand 9 having the structure of 1 + 6 + 12 is composed of a single core filament and is non-twisted, the core 10 of the first sheath 11 around the core is not twisted. The restraining force in the axial direction by the six side filaments 11A is weak. Code 7 is
Vulcanized and bonded to the crawler body 2
However, since the rubber does not penetrate up to the core 10 of the core strand 9, the core 10 constituted by one core filament can move in the axial direction. For this reason, in the elastic crawler 1 in which the tensile member 4 is constituted by the cords 7 having the core strands 9 having the structure of 1 + 6 + 12 (high-speed crawlers, heavy-load crawlers, particularly crawlers for construction machinery) The core 10 of the core strand 9 gradually moves in the axial direction due to the load and bending repeatedly acting on the cord 7 during running, and protrudes from the end 7b of the cord 7, and eventually the outer peripheral surface of the elastic crawler 1 There is a problem that jumps out of the. The present invention has been made in view of the above problems, and has as its object to provide a crawler cord in which a core of a core strand is prevented from jumping out. [0007] The technical means taken by the present invention to solve the technical problem is a core formed by twisting three core filaments, and a core formed around the core. A first sheath formed by twisting the arranged six side filaments and a second sheath formed by twisting the twelve side filaments arranged around the first sheath It has a core strand having a structure of 1 × 3 + 6 + 12, and the diameter of the core of the core strand is 110 to 12 of the diameter of the side filament constituting the first sheath.
It is characterized by being 5%. Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2, reference numeral 7 denotes a cord such as a steel cord constituting a tensile body of an elastic crawler employed in the crawler type traveling device.
It is configured by helically twisting six side strands 13 around the core strand 9. The core strand 9 is formed by helically twisting a core 10 formed by helically twisting three core filaments 10A, and helically twisting six side filaments 11A disposed around the core 10. 1 × 3 + 6 + 12 composed of a first sheath 11, and a second sheath 12 formed by helically twisting twelve side filaments 12 </ b> A arranged around the first sheath 11. The structure is. The first sheath 11 is stranded so as to restrict the axial movement of the core 10 and prevent the core 10 from jumping out of the axial end of the cord 7. Thereby, the core 1 of the core strand 9 can be
0 is prevented from moving in the axial direction and protruding from the axial end of the cord 7. The code 7 shown in FIG.
Shows an example, and the structure of the side strand 13 is
Although a structure similar to the structure of the core strand 9 is illustrated, the side strand 13 is used as the core strand 9.
A structure different from that of, for example, 1+
A structure having a structure of 6 + 12 or 3 + 9 may be employed. The filaments 10A, 11A, 12
As the material of A, besides steel filament, commonly known as
Synthetic fibers called nylon and tetron, inorganic glass fibers, and the like are used. Next, Table 1 shown below
7 shows the results of the core pull-out force, the core pop-out by an actual vehicle test, the fatigue test result, and the presence or absence of twisting failure according to Comparative Examples 1, 2, and 3, and Examples 1 and 2. In Comparative Example 1, a cord 7 having a conventional structure having a core strand 9 having a structure of 1 + 6 + 12 is used as the cord 7, and Comparative Examples 2 and 3 and Examples 1 and 2 have a structure of 1 × 3 + 6 + 12 as the cord 7. A cord 7 having a core strand 9 is used. Each cord 7 is formed by twisting six side strands 13 having the same structure as the core strand 9 around one core strand 9. The side filament 1 constituting the second sheath 12
2A has a diameter d3 of 0.175 mm. [Table 1] In Table 1, the test of the core pull-out force was carried out by applying a tensile load to the core 10 of the core strand 9 in the axial direction. Comparative Example 1 had 150 N /
The core 10 came off with a force of 10 cm. In the case of Comparative Example 2, the core came off with a force of 62 N / 10 cm. Further, the cores of Examples 1 and 2 and Comparative Example 3 did not come off even when pulled until the core 10 was cut. Further, in the actual vehicle test, the core 10 protruded in Comparative Examples 1 and 2, and the core 10 did not protrude in Examples 1, 2 and Comparative Example 3. In Comparative Examples 1 and 2, and Examples 1 and 2,
No twisting failure occurred, but in Comparative Example 3, a twisting failure occurred. Also. In the fatigue test, Comparative Examples 1 and 2 and Examples 1 and 2 were good, but Comparative Example 3 was poor in fatigue resistance. From the above test results, etc., 1 × 3 + 6
Even in the case of the cord 7 having the core strand 9 having the structure of +12, as shown in Comparative Example 2, the diameter d1 of the core 10 is
Depending on the relationship with the diameter d2 of the side filament 11A constituting the first sheath 11, the six side filaments 11A may be used.
A may be weak in the binding force of the core 10, and therefore, the interval L between the side filaments 11 </ b> A of the first sheath 11 needs to be some space, and the core 10
Is made to be 110% or more of the diameter d2 of the side filament 11A constituting the first sheath 11, thereby effectively preventing the core 10 from coming off. The diameter d1 of the core 10 is equal to the diameter d2 of the side filament 11A constituting the first sheath 11.
If it exceeds 25%, the interval L between the side filaments 11A of the first sheath 11 becomes too large, and in this case, it is difficult to make a uniform gap between the side filaments 11A, and a bias is generated, resulting in a stable shape. However, as shown in Comparative Example 3, the fatigue resistance deteriorates. Therefore, the diameter d1 of the core 10 of the core strand 9 is 110 to 1 of the diameter d2 of the side filament 11A constituting the first sheath 11.
It is better to be 25%. The side filament 12A constituting the second sheath 12 has a side filament 12A having a diameter d3 of 0.12 mm to 0.20 mm in order to improve the bending fatigue of the cord 7. Adopted. Further, according to the core strand 9 described above, it is possible to provide a cord 7 (steel cord) for a high-load crawler, which secures strong strength against elongation of the cord 7 and has good bending fatigue properties. That is, as the number of filaments constituting the core strand 9 increases, the strength of the core strand 9 increases, but the workability deteriorates, the cost increases, and it is difficult to bend and is unsuitable for use in a crawler. It will be. Therefore, the core strand 9 employed in the crawler cord 7 needs to have a certain degree of bendability at the same time as ensuring the strength. The core strand comprises a core formed by twisting three core filaments, and a sheath formed by spirally twisting six side filaments disposed around the core. It is conceivable that the filament has a two-layer structure of 1 × 3 + 6. In the two-layer structure, one of the filaments constituting the core strand is cut, and comes out and comes out to the surface of the crawler due to slippage or other reasons. May have a quality problem, but the core strand is 1 × 3 + 6 +
This problem can be solved by adopting a three-layer structure of twelve structures. However, if a three-layer structure is simply adopted, the cord must be too thick, the crawler must be heavy, the bending resistance must be increased, and members such as sprockets and idlers must be enlarged or the strength must be increased. There are many inconveniences such as not being able to. Therefore, in the core strand 9 according to the present embodiment, a three-layer structure is used to secure the strength, and the diameter d4 of the core filament 10A is smaller than the generally used 0.15 mm. The diameter d3 of the side filament 12A of the second sheath 12 is set to 0.15 mm while suppressing the increase in the cord diameter and increasing the adhesion.
By setting the thickness to 0.2 mm, the fatigue strength of bending is improved, and the diameter d1 of the core 10 of the core strand 9 is set to:
By setting the diameter d2 of the side filament 11A constituting the first sheath 11 to 110 to 125%, the core 10
High-quality cord 7 that eliminates eccentricity and unbalanced twist
Can be provided. According to the present invention, the core strand of the crawler cord is formed by twisting three core filaments, and the six side filaments arranged around the core. 1 × 3 composed of a first sheath formed by twisting the first sheath and a second sheath formed by twisting twelve side filaments disposed around the first sheath.
By making the structure of + 6 + 12 and making the diameter of the core 110 to 125% of the diameter of the side filament of the first sheath, the protrusion of the core can be effectively prevented and the fatigue resistance is not impaired. A crawler code can be provided.

[Brief description of the drawings] FIG. 1 is a sectional view of a core strand according to the present invention. FIG. 2 is a sectional view of a cord. FIG. 3 is a cross-sectional view of the elastic crawler in a width direction. FIG. 4 is a sectional view of an elastic crawler in a circumferential direction. FIG. 5 is a sectional view of a conventional core strand. [Explanation of symbols] 9 core strand 10 core 10A core filament 11 First sheath 11A side filament 12 Second sheath 12A side filament d1 Core diameter d2 Diameter of side filament of first sheath

Claims (1)

Claims: 1. A core formed by twisting three core filaments, and a first sheath formed by twisting six side filaments disposed around the core. And a second sheath formed by twisting 12 side filaments arranged around the first sheath.
An elastic crawler cord having a core strand having a structure of + 6 + 12, wherein a core diameter of the core strand is 110 to 125% of a diameter of a side filament constituting the first sheath. .