JP2008230330A - Rubber crawler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber crawler using a core bar of such a shape as to prevent rubber cracking. <P>SOLUTION: A head end part 40 is respectively provided on each of head ends of vane parts 24. The distal end part 40 is in a roughly semi-spherical shape with a flat surface part 30 formed in the inner peripheral direction of the rubber crawler 10, and a lug part 16 formed of only rubber 34 is provided on the outside in the width direction of the rubber crawler from the distal end part 40. The head end part 40 is constituted of; a curved surface (r) formed on a distal end part in the outer peripheral side width direction of the rubber crawler 10; a curved surface r1 formed on the inner peripheral side of the width direction end part; a flat surface part 30 provided on the inner peripheral side from the curved surface r1; and a curved surface r2 tangentially connected to an inner peripheral side surface of the vane part 24 from a width direction inside end of the flat surface part 30 with a smooth curved surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rubber crawler, and more particularly to an endless rubber crawler in which a core metal is embedded and mounted on a construction vehicle or the like.

  In recent years, rubber crawlers have been widely adopted in place of iron shoe crawlers, and endless rubber crawlers in which a large number of metal cores are embedded in a rubber elastic body with a constant pitch, A crawler rubber shoe (hereinafter collectively referred to as a rubber crawler) in which a plurality of tracks are embedded is used (see, for example, Patent Document 1).

  As described above, the rubber crawler in which the core metal is embedded may peel off the core metal and the rubber, or the rubber portion of the rubber lug at the end of the core metal may deteriorate, resulting in a so-called ear cut or a core crack called a core metal end crack. . For example, since the R formed between the flat surface provided at the tip of the wing portion of the core metal and the side curved surface is small and the distortion of the end rubber cannot be alleviated, there is a risk of rubber cracking.

For this reason, the structure which prevents the rubber crack of a rubber lug part by making the front-end | tip part of the wing | blade part of a metal core into a substantially spherical shape is disclosed (for example, refer patent document 2). However, since there is no flat surface at the tip of the wing portion of the metal core, when riding on a curb or the like, stress may concentrate on the rubber at the upper part of the substantially spherical portion when the rubber lug portion is warped, and rubber cracking may occur.
JP 2001-88756 A JP 2004-345578 A

  In view of the above facts, an object of the present invention is to provide a rubber crawler using a mandrel having a shape that prevents rubber cracks in a rubber crawler using a mandrel.

  The rubber crawler according to claim 1 is a core metal embedded in an endless rubber elastic body and arranged in a circumferential direction at a constant pitch, and is wound and embedded around the core metal in the circumferential direction. A rubber crawler provided with a steel cord, wherein the core metal has a pair of corners sandwiching the sprocket engaging portion at the center in the width direction of the endless rubber elastic body. A flat wing portion on both outer sides of the corner portion, and a tip portion of the wing portion extending toward the center in the width direction of the endless rubber elastic body on the inner peripheral side, A curved surface r1 formed toward the outer peripheral side of the endless rubber elastic body from the flat portion, and a curved surface r formed continuously toward the outer peripheral side of the endless rubber elastic body with the curved surface r1. When the radius of curvature of the curved surface r is R and the radius of curvature of the curved surface r1 is R1, R R1 is characterized in that it is a 1 <R / R1 <5.

  In the invention with the above configuration, the concentration of rubber stress near the tip of the cored bar when the rubber crawler is reversely warped is alleviated, and so-called edge breakage can be prevented.

  The rubber crawler according to claim 2 is characterized in that the length L of the flat portion is 5 mm ≦ L ≦ 20 mm.

  In the invention of the above configuration, the stress concentration relaxation to the rubber due to the width of the flat portion being too narrow, the weight increase due to the width of the flat portion being too wide, and the distortion of the rubber due to insufficient rubber thickness on the inner peripheral surface side are increased. Can be prevented.

  The rubber crawler according to claim 3 is characterized in that a curved surface r2 tangentially connected from the flat portion toward the center portion in the width direction of the endless rubber elastic body is formed.

  In the invention with the above configuration, stress concentration on the rubber near the flat surface due to repeated bending of the rubber crawler can be reduced.

  The rubber crawler according to claim 4 is characterized in that the R / R1 is 1 <R / R1 <2.

  In the invention with the above-described configuration, the concentration of rubber stress near the tip of the cored bar during the reverse warping of the rubber crawler is alleviated, and so-called edge breakage can be more effectively prevented.

  Since the present invention has the above-described configuration, it is possible to provide a rubber crawler using a metal core having a shape that relieves stress concentration near the tip of the metal core of the rubber crawler and prevents rubber cracking.

<Example>
Hereinafter, the present invention will be described in more detail with reference to examples.

1 to 3 show a rubber crawler and a metal core according to the present invention.
FIG. 1 is a perspective view showing a rubber crawler according to the present embodiment, FIG. 2 is a plan view and a cross-sectional view of the cored bar of the present invention, FIG. 3 is a trihedral view, and FIG. 4 is an enlarged view of the cored bar.

  As shown in FIGS. 1 and 2, the rubber crawler 10 is formed as a rubber crawler 10 by covering the core metal 12 arranged in the circumferential direction and the steel cord 14 wound around the outer periphery of the core metal 12 with a rubber 34. Has been.

  The metal core 12 is a substantially rod-shaped metal member extending in the width direction of the rubber crawler 10. A sprocket engaging portion 28 and a sprocket engaging portion 28 are provided in the vicinity of the center in the length direction (= the width direction of the rubber crawler 10). A pair of corner portions 26 are sandwiched, a pair of flat wing portions 24 are provided at the ends of the corner portions 26, and tip portions 40 are provided at the tips of the wing portions 24.

  The sprocket engaging portion 28 is a concave portion sandwiched between the corner portions 26. When the sprocket engaging portion 28 is formed as a rubber crawler 10 as shown in FIGS. The driving force is transmitted from the sprocket 20 to the rubber crawler 10 when the tip of the sprocket 20 is engaged with the sprocket engagement hole 22 formed between the core bars 12.

  As shown in FIG. 1, the corner portion 18 projects in the inner circumferential direction of the rubber crawler 10, and guides the wheel 18 and the sprocket 20 so as not to come off in the width direction of the rubber crawler 10. The roller 18 is suspended from the apparatus main body by a suspension device (not shown), and supports the apparatus main body on the rubber crawler 10.

  A flat wing portion 24 is provided outside the corner portion 18 (= outside in the width direction of the rubber crawler 10) to ensure the rigidity of the rubber crawler 10 in the width direction.

  Steel cords 14 are respectively wound in the circumferential direction on the outer peripheral side of the wing part 24, and are fixed by rubber 34 to serve as strength members that support stress on the outer peripheral side. A lug 36 made of only the rubber 34 is provided on the outer peripheral surface of the rubber crawler 10 at a predetermined interval, and forms a ground contact surface of the rubber crawler 10.

  A tip 40 is provided at the tip of each wing 24. The distal end portion 40 has a substantially hemispherical shape in which the flat portion 30 is formed in the inner circumferential direction of the rubber crawler 10, and the ear portion 16 formed only by the rubber 34 on the outer side in the width direction of the rubber crawler 10 than the distal end portion 40. Is provided.

  As shown in FIGS. 3A and 4, the tip 40 is a curved surface r formed on the outer circumferential side width direction tip of the rubber crawler 10, a curved surface r1 formed on the inner circumferential side of the width direction tip, and a curved surface. The flat portion 30 is provided on the inner peripheral side from r1, and the curved surface r2 is tangentially connected to the inner peripheral side surface of the wing portion 24 from the inner end in the width direction of the flat portion 30 with a smooth curved surface.

<Ratio of curvature radius>
Conventionally, as shown in FIG. 5A, a structure is disclosed in which the tip of the wing part 108 of the cored bar 112 has a substantially spherical shape to prevent rubber cracks in the ear part 116. However, since the tip portion 118 provided at the tip of the wing portion 108 of the metal core 112 does not have a flat portion, when the rubber lug portion 116 is warped on the curb stone 120 or the like, the top portion 118 (inner circumference) There is a possibility that stress concentrates on the rubber at the side portion and a rubber crack 114 occurs.

  Further, since the tip end portion 118 has a substantially spherical shape, the ear portion 116 covered with rubber is formed with a convex portion 126 toward the inner peripheral side, and as shown in FIG. There is a possibility that earth and sand 124 accumulates on the inner peripheral side of the flat surface portion 122 formed on the inner side, and this is difficult to be discharged by the convex portion 126 toward the inner peripheral side of the ear portion 116.

  As shown in FIG. 6, the cored bar 12 according to the present embodiment includes a curved surface r formed at the distal end portion of the distal end portion 40 in the width direction and a curvature radius of the curved surface r1 formed at the inner circumferential side of the distal end portion in the width direction. Are R and R1, respectively, R / R1 is in the range represented by 1 <R / r1 <5.

  As a result, as shown in FIG. 5A, when the rubber crawler 110 rides on the curb 120 (at the time of reverse warping), it is possible to prevent the occurrence of the crack 114 in the ear portion 116. That is, if the curved surfaces r and r1 are set so that R / R1 <5, more preferably R / R1 <2, stress is applied to the rubber 34 on the flat surface portion 30 (inner peripheral side portion) provided at the distal end portion 40. Concentrates and rubber cracks (cracks) occur, and it is possible to prevent ear cuts during reverse warping. At this time, the thickness of the rubber 34 from the flat portion 30 to the inner peripheral surface of the rubber crawler 10 is about 10 to 15 mm.

  Further, if the curved surfaces r and r1 are set so that R / R1> 1, more preferably 1 <R / R1 <2, the amount of protrusion of the tip 40 toward the inner peripheral side of the rubber crawler 10 can be suppressed. In addition, the convex portion toward the inner peripheral side of the rubber crawler 10 is not formed on the flat surface portion 32, and it is possible to prevent a situation in which earth and sand are accumulated and are not easily discharged.

  Further, on the side of the rubber crawler 10 that contacts the ground (the lug side), that is, on the outer peripheral side, the cored bar 12 has a semicircular cross section as in the conventional case, and the effect of preventing rubber cracks that easily occur when the rubber crawler 10 is bent is unchanged. Can be maintained.

<Plane shape and width>
As shown in FIG. 4, in this embodiment, the flat portion 30 of the core metal 12 is tangentially connected to the curved surface r <b> 2 on the inner side in the width direction of the rubber crawler 10, and is connected to the wing portion 24 with a smooth curved surface. Thereby, when the rubber crawler 10 is repeatedly bent in the inner circumferential direction, the stress concentration generated in the rubber 34 near the inner side in the width direction of the flat portion 30 can be alleviated and the occurrence of cracks can be prevented.

  Further, the flat portion 30 of the core metal 12 has a length of 5 mm or more and 20 mm or less in the width direction of the rubber crawler 10 when the dimension in the width direction of the rubber crawler 10 itself is about 150 to 1000 mm.

  If this length is too short, the effect of relieving stress concentration on the rubber 34 on the inner peripheral side of the cored bar 12 may be impaired. If it is too long, the tip 40 of the cored bar 12 will be heavy and flat. Since it becomes difficult to sufficiently increase the thickness of the rubber 34 from the portion 30 to the inner peripheral surface of the rubber crawler 10 (black arrow in FIG. 4), there is a risk of distortion due to insufficient thickness of the rubber 34.

  In the present embodiment, since the flat portion 30 of the cored bar 12 has a length of 5 mm or more and 20 mm or less in the width direction, the distal end portion 40 is maintained while maintaining the effect of reducing stress concentration on the rubber 34 on the inner peripheral side. And the occurrence of distortion due to insufficient thickness of the rubber 34 at the flat surface portion 30 can be prevented.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. Further, it goes without saying that the scope of rights of the present invention is not limited to these embodiments and can be implemented in various modes without departing from the gist of the present invention.

It is a perspective view which shows the rubber crawler which concerns on embodiment of this invention. It is the top view and sectional drawing which show the rubber crawler which concerns on embodiment of this invention. It is a three-plane figure which shows the metal core of the rubber crawler which concerns on embodiment of this invention. It is sectional drawing to which the core metal of the rubber crawler concerning embodiment of this invention was expanded. It is sectional drawing which shows the conventional rubber crawler. It is a table | surface which shows the relationship between the front-end | tip part shape of a metal core of the rubber crawler which concerns on embodiment of this invention, and performance. It is a table | surface which shows the relationship between the front-end | tip part shape of a metal core of the rubber crawler which concerns on embodiment of this invention, and performance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rubber crawler 12 Core metal 14 Steel cord 16 Ear part 18 Rolling wheel 20 Sprocket 22 Sprocket engagement hole 24 Wing part 26 Corner part 28 Sprocket engagement part 30 Plane part 32 Plane part 34 Rubber 36 Lug 40 Tip part r Curved surface r1 Curved surface r2 curved surface

Claims (4)

A cored bar embedded in an endless rubber elastic body in a circumferential direction with a constant pitch, and a steel cord wound around the outer side of the cored bar and embedded in the circumferential direction. A rubber crawler,
The core metal has a sprocket engaging portion at the center in the width direction of the endless rubber elastic body, a pair of corner portions sandwiching the sprocket engaging portion, and flat wing portions on both outer sides of the corner portions, With
The tip part of the wing part has a flat part extending toward the center in the width direction of the endless rubber elastic body on the inner peripheral side, and a curved surface formed from the flat part toward the outer peripheral side of the endless rubber elastic body r1 and a curved surface r formed continuously toward the outer peripheral side of the endless rubber elastic body with the curved surface r1;
When the radius of curvature of the curved surface r is R and the radius of curvature of the curved surface r1 is R1, R / R1 is 1 <R / R1 <5.
Rubber crawler characterized by being. The length L of the flat portion is 5 mm ≦ L ≦ 20 mm
The rubber crawler according to claim 1, wherein: 3. The rubber crawler according to claim 1, wherein a curved surface r <b> 2 that is tangentially connected from the flat portion toward the center in the width direction of the endless rubber elastic body is formed. R / R1 is 1 <R / R1 <2
The rubber crawler according to any one of claims 1 to 3, wherein the rubber crawler is any one of the above.

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