Core bar of elastic body track shoe

Details Core bar of elastic body track shoe Core bar of elastic body track shoe

2003-10-09

2004-12-21

Stormer, Russell D. (Department: 3617)

Wheel substitutes for land vehicles

Endless belt having nonmetallic track or tread

Track formed of endless flexible belt

C305S157000, C305S165000

Reexamination Certificate

active

06832820

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a core bar inserted to an elastic body of an elastic body track shoe used for an endless rubber crawler in a construction machine or the like.
BACKGROUND OF THE INVENTION
An endless rubber crawler structured such that elastic body track shoes having core bars inserted to elastic bodies such as rubbers or the like are mounted at a predetermined interval via a pair of joint links and connection pins in a circumferential direction is frequently employed in a construction machine such as a hydraulic excavator or the like, and an industrial vehicle such as a crawler type conveyance vehicle or the like.
As a first conventional art of the elastic body track shoe, for example, there has been known a structure shown in FIG.
11
. In
FIG. 11
, an elastic body track shoe
20
has an elastic body
22
such as a rubber or the like, and a core bar
21
inserted to the elastic body
22
. The core bar
21
employs a reduction roll material cut in a predetermined shape, and is structured such that both end portions in a direction of width of a crawler belt (that is, both right and left wing portions) are inclined upward at a predetermined angle in a direction of a non-grounded surface and the other portions than both end portions in the direction of the crawler belt width are manufactured in the same cross sectional shape in a side view.
However, since the core bar
21
mentioned above is manufactured by the sheet material obtained by cutting the reduction roll material, there is provided the flat core bar
21
having the same thickness all around the portions except both end portions
21
a
and
21
a
in the direction of the crawler belt width which is chamfered in a manner shown in
FIG. 11
, and a weight thereof becomes heavy.
As a second prior art against the problem mentioned above, for example, there is a core bar for a rubber crawler disclosed in Japanese Patent No. 3033674, and
FIGS. 12 and 13
are respectively inside plan view and a front elevational view of a core bar described in the publication. In accordance with the publication, thick portions
34
and
34
extending in a longitudinal direction of a core bar
31
are formed in front end portions of right and left wing portions
33
and
33
of the core bar
31
, and there are disclosed a matter that a rib reinforcing effect is achieved by increasing a thickness of the thick portions
34
and
34
so as to form the core bar
31
in a shape protruding upward from the surface, a matter that a strength of a core bar is increased by forming the rib so as to achieve a light structure, and a matter that a plurality of hole portions
32
and
32
are provided in the right and left wing portions
33
and
33
for the purpose of improving an adhesion property between the core bar
31
and the rubber elastic body so as to achieve a light structure.
However, in the core bar for the rubber crawler disclosed in the publication, there is a problem that in a core bar lightening means forming the rib by protruding upward the front end portion of the core bar
31
from the surface and having an increased strength, an elastic deformation of the rubber elastic body adhered to the core bar
31
is restricted in a freedom of deformation at the portion of the protruded upward rib, and an elastic strain is concentrated so as to quicken a fatigue crack of the rubber elastic body.
Further, in the core bar lightening means having a hole pierced in the core bar
31
, since a plurality of hole portions
32
and
32
are provided in both wing portions
33
and
33
of the core bar
31
, there are problems that a strength of the core bars in both wing portions
33
and
33
is reduced and the rubber elastic body deformed due to the applied weight is in contact with an edge of the hole so as to be easily cut.
SUMMARY OF THE INVENTION
The present invention is made by taking into consideration a matter that a strength required in each of portions of a core bar is not uniform in all around the portions and a matter that the core bar is rigidly integrated via a crawler belt connection link and a link connection pin. Further, an object of the present invention is to provide the core bar of an elastic body track shoe structured such as to achieve a light structure by making a stress excess portion in the core bar thin, prevent an elastic body from strain deforming by forming a smooth rib reinforcing portion in which an edge portion of the core bar does not protrude from a core bar surface, secure a strength even when a hole is pierced in the core bar, and make the elastic body not be cut by an edge portion of the hole.
In order to achieve the object mentioned above, in accordance with a first aspect of the present invention, there is provided a core bar of an elastic body track shoe inserted to an elastic body such as a rubber or the like in the elastic body track shoe fastened to each pair of joint links of a crawler by bolts and formed in a substantially flat surface shape on both of front and back surfaces, wherein recess portions formed in a substantially inverse-trapezoidal shape are formed in non-grounded surface sides of right and left wing portions in a direction of a crawler width.
In accordance with the first aspect, since the recess portions are formed in the right and left wing portions of the core bar, it is possible to achieve a light structure and it is possible to reduce a manufacturing cost. Further, since the recess portions are formed in the non-grounded surface sides while grounded surface sides of the right and left wing portions are kept in the flat surfaces, the grounded surface sides of the core bar are formed in a shape having no stress concentration, and it is possible to widely improve a durability. Further, in an outer peripheral portion of the recess portion, since a non-recess portion (having the same thickness and strength as those before forming the recess portion) is left along the direction of the crawler width in both end portions in a longitudinal direction of the crawler, it is possible to secure a necessary strength. Further, since a surface changing to the recess portion from the non-recess portion on the flat surface is formed in a smooth surface having a substantially inverse-trapezoidal shape, it is possible not only to increase an adhesive strength with respect to the elastic body but also to avoid a concentration of elastic strain.
In accordance with a second aspect of the present invention, there is provided a core bar of an elastic body track shoe inserted to an elastic body such as a rubber or the like in the elastic body track shoe fastened to each pair of joint links of a crawler by bolts and formed in a substantially flat surface shape on both of front and back surfaces, wherein recess portions formed in a substantially inverse-trapezoidal shape open toward a front end portion are formed in non-grounded surface sides of right and left wing portions in a direction of a crawler width.
In accordance with the second aspect, since the recess portion open to the front end portion is formed in the non-grounded surface sides of the right and left wing portions in the core bar, it is possible to further lighten in comparison with the core bar in accordance with the first aspect, and it is possible to reduce a manufacturing cost. The other operations and effects are the same as those of the first invention.
In accordance with a third aspect of the present invention, there is provided a core bar of an elastic body track shoe inserted to an elastic body such as a rubber or the like in the elastic body track shoe fastened to each pair of joint links of a crawler by bolts and formed in a substantially flat surface shape on both of front and back surfaces, wherein a recess portion formed in a substantially inverse-trapezoidal shape is formed in a center portion in a direction of a crawler width.
In accordance with the third aspect of the present invention, since the recess portion is formed in the center portion in the direction of the crawler width of the core bar, it is po

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