JP5230216B2 - Rubber crawler - Google Patents

Description

  According to the present invention, an endless rubber elastic body, a steel cord reinforcing layer embedded in the elastic body and extending endlessly, and an outer peripheral surface of the rubber elastic body are formed at intervals in the circumferential direction. A plurality of lugs extending in the width direction of the rubber elastic body, and a predetermined number of core bars extending in the width direction of the rubber elastic body on the inner peripheral side of the steel cord reinforcing layer into the rubber elastic body. This is related to a rubber crawler that can be embedded at a fixed pitch, especially when the rubber crawler is driven to run around the sprocket and idler to reduce bending distortion that occurs at the protruding base of the lug. This is a proposal for the technology to be applied.

  In this specification and claims, “prone to extend in the width direction of the rubber elastic body” means that the extending component of the rubber elastic body in the width direction relates to the extension length of the lug. It shall mean greater than the extending component in the circumferential direction of the body.

  In this type of rubber crawler, which has lugs that act on the road surface and cause the running, stopping, etc. of work equipment on the outer peripheral surface of an endless rubber elastic body with an endless steel cord reinforcement layer embedded in it, it is used as a sprocket and idler. It is inevitable that the part of the rubber crawler that is wrapped around the sprocket or the like is bent and deformed when it is wound and driven. In this bending deformation, the deformation resistance is small. It is generally known that there is a concentration of strain in the protruding base portion of the lug where the rubber elastic body is thin, which is a small portion.

In such concentrated areas of strain, cracks due to bending fatigue are likely to occur in the rubber elastic body. When the cracks reach the steel cord reinforcement layer, moisture etc. that has reached the steel cord reinforcement layer through the cracks are Corrosion of the cord is caused to proceed, so that conventionally, the lug is selected by selecting the shape of the lug, the manner of arrangement of the lug, and the like, thereby reducing the concentration of strain.
However, with this measure, it has been impossible to effectively suppress the occurrence of cracks in the protruding base portion of the lug as expected.

On the other hand, Patent Document 1 discloses that one or more concave grooves extending in the width direction of the rubber crawler are formed between two types of long and short lugs within a range not exceeding the extended length of the short lugs. According to this, it is easy to bend and deform the concave groove part located in the winding part of sprockets etc. and make it easy to open between the lugs, so that mud etc. clogged between the lugs can float and fall off Suppose that it can be made easy.
JP 2007-133102 A

  However, this conventional technique reduces the thickness of the rubber elastic body in the groove portion by forming the groove, thereby reducing the bending deformation resistance in the direction in which the groove extends, in other words, lowering the bending rigidity, Since this is based on the technical idea of concentrating the bending deformation, according to this, there is a problem that it is unavoidable that the occurrence of earlier cracks due to the bending fatigue of the rubber elastic body due to the concentration of strain in the concave groove. was there.

  In the present invention, when the rubber crawler is bent and deformed by being wound around a sprocket or the like, the steel cord reinforcing layer is positioned on the neutral axis of the bending, and the deformation is performed. Is based on the idea that the portion closer to the steel cord reinforcement layer in the thickness direction of the rubber elastic body is less, and depends on the thickness of the rubber elastic body up to the steel cord reinforcement layer of the rubber crawler, An object of the present invention is to provide a rubber crawler that can effectively prevent the concentration of strain on the protruding base portion of the lug and thereby the occurrence of cracks in the rubber elastic body without impairing the damage resistance as much as possible. It is.

  The rubber crawler according to the present invention is formed with an endless rubber elastic body, a steel cord reinforcing layer embedded in the rubber elastic body and extending endlessly, and an outer peripheral surface of the rubber elastic body at intervals in the circumferential direction. A plurality of lugs that tend to extend in the width direction of the rubber elastic body, for example, a plurality of core bars extending in the width direction of the rubber elastic body on the inner peripheral side of the steel cord reinforcing layer, It is embedded in an elastic body at a predetermined pitch, and is driven to run around a sprocket and an idler at the central portion in the width direction of the inner peripheral surface of the rubber elastic body. More preferably, at least one side in the circumferential direction of each lug formed continuously on the outer peripheral surface of the body over the entire width of the rubber elastic body or discontinuously formed across the central portion in the width direction of the rubber elastic body. Ku is on both sides, the protruding base of the lug, smoothly continuous to the protruding wall of the lug is made by providing a groove extending over the entire length of the lugs.

  Preferably, the cross-sectional shape orthogonal to the center line of the groove is a single arc or a curved shape consisting of a plurality of arcs, or the cross-sectional shape orthogonal to the center line of the groove is reinforced with a steel cord. It is assumed to be formed by a flat groove bottom parallel to the layer and a curved groove wall made of a single arc or a plurality of arcs smoothly continuing on both sides of the flat groove bottom.

  By the way, the depth of the groove here can be gradually changed as required in the extending direction of the groove.

  In the rubber crawler according to the present invention, in particular, each lug formed on the outer circumferential surface of the rubber elastic body is smoothly and continuously connected to the projecting base of the lug on at least one side in the circumferential direction. In addition, the amount of tensile strain generated around the steel cord reinforcement layer is reduced against bending deformation that occurs especially at the base of the lug when a groove is provided extending over the entire length of the lug and the rubber crawler is wound around a sprocket. The cracks in the protruding base portion of the lug caused by bending fatigue can be reduced over a long period of time by reducing the above-mentioned groove, particularly the groove bottom, located close to the steel cord reinforcing layer. It can be effectively prevented.

  Here, the rubber elastic body thickness of the base portion of the lug is locally thinned by the formation of the groove, and the groove bottom is brought close to the steel cord reinforcing layer as necessary. Then, since the required thickness is given to the rubber elastic body, there is almost no possibility that the scratch resistance of the rubber crawler, which is proportional to the thickness of the rubber elastic body, is reduced.

  Further, since the groove here is formed smoothly and continuously on the protruding wall surface of the lug without any irregularities or the like, local stress concentration occurs during the bending deformation of the rubber crawler as described above. The risk of strain concentration can be removed sufficiently.

  In such a rubber crawler, when the cross-sectional shape of the groove is a curved shape composed of a single or a plurality of arcs, the risk of stress concentration, strain concentration, etc. in the groove can be effectively removed. This means that the cross-sectional shape of the groove is formed by a flat groove bottom parallel to the steel cord reinforcing layer and a curved groove wall consisting of a single arc or a plurality of arcs smoothly connected to the flat groove bottom. The same is true when it comes to.

By the way, in such a rubber crawler, the depth of the groove of the protruding base of the lug is gradually changed so as to be deeper at a portion where the bending strain becomes larger and shallower at a portion where the bending strain is smaller when it is wound around a sprocket or the like. In this case, the crack durability of the protruding base portion of the lug can be made sufficiently uniform in the width direction of the rubber crawler.
In this case, the groove depth can be gradually changed through a flat inclined surface, a convex or concave curved surface, or a plurality of stepped partial surfaces.

  FIG. 1 is a perspective view showing an essential part of a rubber crawler according to an embodiment of the present invention in a winding position around a sprocket. In FIG. 1, 1 is a rubber crawler and 2 is a rubber crawler 1 wound. Each of the sprockets is applied to the crawler 1 so as to transmit the driving force to the crawler 1, and 3 is a wheel that rolls the central portion in the width direction of the rubber crawler 1 while supporting the weight of the construction machine or other body. Show.

  Here, the illustrated rubber crawler 1 includes an endless rubber elastic body 4, a steel cord reinforcing layer 5 embedded in the rubber elastic body 4 and extending endlessly, and an outer peripheral surface of the rubber elastic body 4 in the circumferential direction. A plurality of lugs 6 that are formed at intervals and that tend to extend in the width direction of the rubber elastic body 4, in the figure, staggered in each side region across the central portion in the width direction of the rubber elastic body 4. A plurality of lugs 6 formed, and in the rubber elastic body 4 on the inner peripheral side of the steel cord reinforcing layer, the core metal 7 and the inner peripheral surface of the rubber elastic body 4 in the width direction. The rubber crawler 1 having a sprocket 2 and an idler engaging portion 8 (not shown) provided at the central portion is driven while being wound around the sprocket 2 and an idler (not shown).

  By the way, the illustrated sprocket 2 allows the teeth formed around the sprocket 2 to enter the through-hole 8a as is apparent from the partial development plan view shown in FIG. 2 provided in the engaging portion 8 of the rubber crawler 1. At the same time, the rubber elastic body 4 and by extension, the central portion of each cored bar 7 extending in the width direction of the crawler 1 is covered between the respective teeth 2a under the rubber elastic body 4 covering the teeth 2a and the cored bar. By engaging 7, the rotational driving force can be smoothly transmitted to the rubber crawler 1.

  Further, in the illustrated wheel 3, the peripheral surfaces of the pair of small diameter portions 3 b positioned with the one large diameter portion 3 a therebetween are provided with a portion corresponding to the engaging portion 8 of the core metal 7. By placing on the pair of protrusions 7a via the rubber elastic body coating layer and disposing one large diameter part 3a between the pair of protrusions 7a at a part corresponding to the engaging part 8, As the rubber crawler 1 travels, the small-diameter portion 3b can be smoothly rolled on the projection 7a under the action of preventing the wheel from being removed by the cooperation of the large-diameter portion 3a and the projection 7a.

  In such a rubber crawler 1, for example, at least one of the lugs 6 in the circumferential direction can be provided on the outer peripheral surface of the rubber elastic body 4 so as to extend continuously over the entire width of the rubber elastic body 4. 2, on both sides in the circumferential direction in the drawing, extending smoothly over the entire length of the lug 6, smoothly and continuously to the protruding wall surface 6 a of the lug 6, as shown in a sectional view in FIG. 3. An extending groove 9 as illustrated in the plan view is provided, and the groove bottom of the groove 9 is positioned sufficiently close to the steel cord reinforcing layer 7.

  By forming such a groove 9, the rubber crawler 1 has a steel cord reinforcing layer 5 in a neutral position when the rubber crawler 1 is bent and deformed when it is wound around the sprocket 2 as shown in FIG. 6 can be advantageously reduced at the groove bottom portion of the groove 9, which is positioned closest to the steel cord reinforcing layer 5, so that the groove 9 is formed in the protruding base portion. Compared with the prior art which does not form, the bending fatigue | exhaustion of a protrusion base part can be removed advantageously, and generation | occurrence | production of the crack to the protrusion base part can be suppressed effectively.

It is not essential that the depth of the groove 9 is constant over the entire length of the groove 9. For example, when the rubber crawler 1 is wound around the sprocket 2, It can also be formed deeper in the portion where the amount increases, and shallower in the portion where the amount of distortion is small.
In this case, the portions having different groove depths can be smoothly connected by a flat bottom view, a groove bottom portion having a concave or convex curved surface, etc. It is preferable in preventing concentration of the water.

On the other hand, the groove 9 causes a reduction in the thickness of the rubber elastic body with respect to the steel cord reinforcing layer 5, and thereby, at the place where the groove 9 is formed, the damage resistance against the sticking of the protrusion on the road surface or the like. And the bending fatigue resistance, the depth and opening width of the groove 9 are related to the thickness of the rubber elastic body 4 from the steel cord reinforcing layer 5, the pitch of the lugs 6 and the like. It is preferred to select below.
Incidentally, when the thickness from the steel cord reinforcing layer of the rubber elastic body 4 to the lug surface is 5 to 20 mm and the pitch of the lugs 6 is 40 to 100 mm, the depth of the groove 9 is 3 to 5 mm and the opening width is 5 to 5 mm. It is preferable to be 20 mm.

  FIG. 4 is a cross-sectional view showing a specific example of forming the groove 9. FIG. 4A shows a case where the groove 9 having a depth of 3 mm is formed by a single arc having a radius of 10 mm. b) The bottom of the groove 9 having a depth of 3 mm is a flat surface having a width of 5 mm, and each curved groove wall formed by a single arc having a radius of 10 mm is smoothly connected to the bottom of the flat groove. Show the case.

  When each groove 9 as shown in FIGS. 4A and 4B is formed, and for each of the conventional techniques as shown in FIG. When the maximum distortion rate was analyzed using the finite element method, the maximum distortion rate was 22% in the prior art shown in FIG. 5, whereas those shown in FIGS. 4 (a) and 4 (b) In all cases, the value was 21%, and the strain reduction effect based on the formation of the grooves 9 could be confirmed specifically.

  Although the present invention has been described above based on the illustrated embodiment and the like, the groove 9 as described above can be provided only on one side of the lug 6 in the circumferential direction. Of course, the bending strain generated in the protruding base portion can be reduced.

It is a principal part perspective view which shows embodiment of this invention in the state wound around a sprocket. It is a partial expansion | deployment top view of the outer peripheral surface of a rubber crawler. FIG. 3 is a cut end view taken along line III-III in FIG. 2. It is sectional drawing which shows the specific example of formation of a groove | channel. It is sectional drawing similar to FIG. 4 which shows a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rubber crawler 2 Sprocket 2a Tooth 3 Roller wheel 3a Large diameter part 3b Small diameter part 4 Rubber elastic body 5 Steel cord reinforcement layer 6 Lug 6a Lug wall surface 7 Core metal 7a Protrusion 8 Engagement part 8a Through hole 9 Groove

Claims (4)

An endless rubber elastic body, a steel cord reinforcement layer embedded in the rubber elastic body and extending endlessly, and formed on the outer peripheral surface of the rubber elastic body at intervals in the circumferential direction. A rubber crawler that has a plurality of lugs extending in the width direction of the belt and is driven to run around the sprocket and idler.
At least one side in the circumferential direction of each lug formed continuously on the outer peripheral surface of the rubber elastic body over the entire width of the rubber elastic body or discontinuously across the central portion in the width direction of the rubber elastic body, A rubber crawler in which a groove extending over the entire length of the lug is provided on the projecting base of the lug, smoothly and continuously on the projecting wall surface.   The rubber crawler according to claim 1, wherein the cross-sectional shape of the groove is a single circular arc or a curved shape including a plurality of circular arcs.   The transverse cross-sectional form of the groove is formed by a flat groove bottom parallel to the steel cord reinforcing layer and a curved groove wall consisting of a single arc or a plurality of arcs smoothly continuing on both sides of the flat groove bottom. Item 2. A rubber crawler according to item 1.   The rubber crawler according to any one of claims 1 to 3, wherein the depth of the groove is gradually changed in the extending direction thereof.

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