Patent Application
20090302677
The present invention is an invention for improving the durability of a rubber crawler track, and in particular an invention that improves flaw due to wear of edge portions of the rubber crawler track.
Generally two kinds of rubber have been used for configuring metal core-containing rubber crawler tracks or metal core-less rubber crawler tracks (referred to below simply as rubber crawler tracks where appropriate), an outer peripheral side rubber (lug side rubber) and an inner peripheral face rubber. Of these two rubbers the lug side rubber is for the surface that contacts the ground, and compounding is in that the wear resistance and durability to cuts thereof are particular important. The inner peripheral face side rubber is for the surface driven by roller, mud and sand that gets caught up presses against the rubber surface, and this repeatedly occurs so it can lead to an eroded state of the surface, so a rubber that is excellent in resistance to external damage is disposed here. These two kinds of rubber are stacked in an unvulcanized state within a mold for molding the rubber crawler track, and then the whole body is vulcanized together to give a construction with the internal and outer peripheral side rubbers laminated at the end portions of the rubber crawler track in the width direction.
Explanation will now be given of a conventional metal core-containing rubber crawler track 10 with reference to
As shown in
The rubber crawler track runs while it is spanned across between an idler and a sprocket provided at a shaft extending from a drive device of the machine body side. However, mud and gravel etc. readily accumulates between the machine body and the rubber crawler track, and in particular in the vicinity of the shaft provided to the sprocket. When such piled material dries it readily hardens, with wear and cracking readily occurring at a portion where this material contacts the rubber crawler track, in particular at the width direction ends thereof.
Namely such piled material is sandwiched between the machine body and the rubber crawler track, and scratch damage occurs at the ends 10A in the width direction of the rubber crawler track 10 (mainly on the inner peripheral side), as shown in
The use of rubber of high hardness for the left and right edges of rubber crawler tracks is a feature already employed in patent document 1 (see patent document 1). However the objective to be solved in patent document 1 is only to prevent the occurrence of cracks in the vicinity of the edges of the metal core.
Therefore, in patent document 1 a fiber layer is embedded so as to wrap around the edges of the metal core, disposed in a circular arc manner, and a high hardness rubber layer is also disposed as a similar circular arc manner along the fiber layer. Namely in the invention of patent document 1 the technical idea is to embed a high hardness rubber layer in the rubber crawler track edges, but regarding the rubber layers of the inner and outer peripheral side, theses are configured as conventional.
The technology shown in patent document 1 simply shows that, for preventing cracks in the vicinity of the edges of the metal core, a fiber layer being curved is disposed with a rubber type of high hardness covering the fiber layer being also curved, and is embedded within ordinary rubber. The type of rubber used in the ends of the rubber crawler track (the external portions exposed to the outside) are fundamentally no different from conventional rubbers, resulting in a structure unable to prevent wear at the position of the rubber crawler track by contacting the piled and hardened mud and sand etc.
The objective of the present invention is to address the above problem, to reduce wear at the rubber crawler track edges, and improve durability.
The structure of a rubber crawler track of claim 1 is in that the rubber crawler track is configured to include at least three kinds of rubbers including: an inner peripheral side rubber (a) that is disposed at the inner peripheral side of the rubber crawler track, an outer peripheral side rubber (b) that is disposed at the outer peripheral side of the rubber crawler track, and edge rubbers (c) that are disposed at both end portions in the width direction of the rubber crawler track.
Explanation will now be given of the operation of the rubber crawler track structure of claim 1.
The required characteristics of the kinds of rubber used in the rubber crawler track depend on their locations of disposition, in the present invention, changing the kind of rubber applied according to the location for the ground contact side, inner peripheral side, and width direction end portions, enables the optimum rubber to be used for the ground contact side, inner peripheral side and width direction end portions, enabling the functionality of the rubber crawler track to be effectively achieved.
The invention of claim 2 is the rubber crawler track structure of claim 1, wherein the edge rubber (c) at least one in the rubber crawler track width direction is a rubber layer with the highest hardness.
Explanation will now be given of the operation of the rubber crawler track structure of claim 2.
Lessening of wear and improvement in durability is enabled at the location, the wear in the location being caused by contacting with harden hardly and piled material, by the edge rubber (c) being the rubber layer with the highest hardness.
In particular, the edge rubber (c) at least one in the rubber crawler track width direction (at the machine body side when mounted) is preferably the rubber layer with the highest hardness, since wear is severe at the rubber crawler track end on the machine body side. It should be noted that it is preferable for the edge rubber (c) at both sides to be the rubber layer with the highest hardness when taking into consideration of reversing of the mounting direction.
The invention of claim 3 is the rubber crawler track structure according to claim 2, wherein the hardness of the edge rubber (c) is 72 hardness degrees or greater (JIS A).
Explanation will now be given of the operation of the rubber crawler track structure of claim 3.
The hardness degree of the edge rubber (c) is preferably 72 hardness degrees or greater (JIS A), with a hardness degree of 72 to 90 (JIS A) more preferable. High wear resistance is obtained by the edge rubber (c) being 72 hardness degrees or greater, and the end portion of the rubber crawler track is not readily worn down.
The invention of claim 4 is the rubber crawler track structure of any one of claim 1 to claim 3 wherein the edge rubber (c) is disposed so as to cover an edge portion of the steel cord.
Explanation will now be given of the operation of the rubber crawler track structure of claim 4.
Prevention of the edge portion of the steel cord being laid bare due to wear, and an increase in the durability of the rubber crawler track is enabled by disposing the edge rubber (c) so as to cover the edge portion of the steel cord.
The invention of claim 5 is the rubber crawler track structure of any one of claim 1 to claim 4 wherein the edge rubber (c) is disposed so as to cover an edge portion of a metal core.
Explanation will now be given of the operation of the rubber crawler track structure of claim 5.
Prevention of the edge portion of the metal core being laid bare due to wear, and an increase in the durability of the rubber crawler track is enabled by disposing the edge rubber (c) so as to cover an edge portion of the metal core.
The invention of claim 6 is the rubber crawler track structure of any one of claim 1 to claim 5 wherein the edge rubber (c) has a width of at least 25 mm or greater from the end portion of the rubber crawler track.
Explanation will now be given of the operation of the rubber crawler track structure of claim 6.
The effect by providing the edge rubber (c) is obtainable as long as the edge rubber (c) has a width of at least 25 mm or greater from the end portion of the rubber crawler track, for example the effect is obtainable even in a metal core-less rubber crawler track.
The invention of claim 7 is the rubber crawler track structure of any one of claim 1 to claim 6 wherein the edge rubber (c) is present at least at the inner peripheral side of the rubber crawler track.
Explanation will now be given of the operation of the rubber crawler track structure of claim 7.
In the rubber crawler track, the edge rubber (c) is preferably disposed on the inner peripheral side, this is since wear due to the piled material occurs at from the end portion to the inner peripheral side.
The invention of claim 8 is the rubber crawler track structure of any one of claim 1 to claim 7 wherein the edge rubber (c) is present at least at the ground contact face of the rubber crawler track.
Explanation will now be given of the operation of the rubber crawler track structure of claim 8.
The edge rubber (c) is preferably disposed at the ground contact face of the rubber crawler track since the ground contact face end portion is worn by flexing of the machine underbody.
The invention of claim 9 is the rubber crawler track structure of any one of claim 1 to claim 8 wherein the edge rubber (c) is continuous in the peripheral direction.
Explanation will now be given of the operation of the rubber crawler track structure of claim 9.
The wear resistance over the entire end portion in the peripheral direction can be raised by provision of the edge rubber (c) continuous in the longitudinal direction of the rubber crawler track 10.
The invention of claim 10 is the rubber crawler track structure of any one of claim 1 to claim 9 wherein the edge rubber (c) is an SBR rubber.
Explanation will now be given of operation of the rubber crawler track structure of claim 10.
The wear resistance of the end portion of the rubber crawler track can be improved by using an SBR rubber for the edge rubber (c).
The invention of claim 11 is the rubber crawler track structure of any one of claim 1 to claim 10 further comprises a metal core with at least a portion thereof embedded in the rubber, in addition to the inner peripheral side rubber (a), the outer peripheral side rubber (b) and the edge rubber (c), the rubber crawler track includes at least one of: a covering rubber covering the steel cords; an intermediate rubber disposed between the metal core and the steel cords; or a rubber for forming a guide projection for engaging in a driving recess provided in a sprocket surface.
Explanation will now be given of the operation of the rubber crawler track structure of claim 11.
The rubber configuring the rubber crawler track requires at least the three rubbers of the inner peripheral side rubber (a), the outer peripheral side rubber (b) and the edge rubber (c). However, one or more other rubber may also be used from a covering rubber covering the steel cords; an intermediate rubber disposed between the metal core and the steel cords; and a rubber for forming a guide projection for engaging in a driving recess provided in a sprocket surface. Optimum rubbers can also be used for other positions than the inner peripheral side, outer peripheral side and end portions, enabling functionality of the rubber crawler track to be achieved more effectively.
The required characteristics of types of rubber used in a rubber crawler track differ depending on the disposition locations, however since in the rubber crawler track structure of claim 1, the type of rubber applied can be varied according to the location at the ground contact side, inner peripheral side, and width direction end portions, this enables functionality of the rubber crawler track to be achieved effectively.
In the rubber crawler track structure of claim 2, an improvement can be made in the wear resistance by the edge rubber (c) being the rubber layer with the highest hardness degree.
In the rubber crawler track structure of claim 3, high wear resistance can be obtained by the edge rubber (c) being 72 hardness degree or above, and the end portion of the rubber crawler track is not readily worn.
In the rubber crawler track structure of claim 4, the edge portion of the steel cord can be prevented from being laid bare due to wear, enabling an increase in the durability of the rubber crawler track.
In the rubber crawler track structure of claim 5, the edge portion of the metal core can be prevented from being laid bare due to wear, enabling an increase in the durability of the rubber crawler track.
In the rubber crawler track structure of claim 6, wear at the end portion provided with the edge rubber (c) is lessened, and an improvement in the durability can be achieved with certainty.
In the rubber crawler track structure of claim 7, wear from the end portion up to the inner peripheral side is lessened, and the durability can be improved.
In the rubber crawler track structure of claim 8, wear at the ground contact face end portion is lessened, and the durability can be improved.
In the rubber crawler track structure of claim 9, high wear resistance over the entire end portion in the peripheral direction can be obtained.
In the rubber crawler track structure of claim 10, high wear resistance at the end portion of the rubber crawler track is obtainable.
In the rubber crawler track structure of claim 11, the functionality of the rubber crawler track can be achieve even more effectively.
Normally, rubbers used for configuring the inner and outer peripheral faces of rubber crawler tracks are rubbers of about 60 to 65 hardness. A rubber layer having hardness of distinctly different properties of those is disposed at locations, where wear may readily occur, of the rubber crawler track. It should be noted that an SBR rubber type is usually used for such a rubber layer, and there are no particular limitations thereto. In order to improve wear resistance it is possible to fill a filler of a reinforcement material within the rubber, such as a resin material, cut fibers or the like. It is also preferable for the edge rubber (c) to be present at least at the inner peripheral side of the rubber crawler track (claim 7).
With respect to the properties of the rubber of the edges of the rubber crawler track, obviously rubber is used with excellent wear resistance and resistance to external damage, however there are only moderate requirements for bendability in comparison to the rubber used for the ground contact portions on the outer peripheral side. Use of the rubber type of the present invention is also a counter measure against disorder of the steel cord during vulcanization molding.
Further explanation will now be given of the present invention by use of the drawings.
A rubber crawler track 10 is formed with inner peripheral side rubber a on the inner peripheral side thereof, and outer peripheral side rubber b formed on the outer peripheral side thereof, using SBR rubbers (degree of hardness 65 (JIS A)) with respective characteristics; the end portions of the rubber crawler track 10 further outside than the left and right edges of the metal core 11 are edge rubber c formed from an SBR rubber (degree of hardness 72 (JIS A)) (claims 1 to 3, and 10).
As a molding method, formation is made by, as shown in
According to the configuration of the present invention, the left and right end portions of the rubber crawler track 10 where contact hardened hardly, piled material are of edge rubber c that is different to conventional rubber type. Therefore wear is dramatically reduced, providing greatly contributing to an increase in the durability of the rubber crawler track 10.
In consideration of the problems with the related technology shown in
A fundamental difference of invention between the related technology (patent document 1) and the present invention is that the wear resistances thereof are greatly different depending on whether or not a rubber of high hardness degree is used for the whole of the end portion in the width direction of the rubber crawler track. To go further, the technology shown in related technology (patent document 1) simply shows that, for preventing cracks in the vicinity of the edges of the metal core, a fiber layer being curved is disposed with a rubber type of high hardness covering the fiber layer being also curved, and is embedded within ordinary rubber. The type of rubber used in the end portions of the rubber crawler track are fundamentally no different from conventional rubbers, resulting in a structure unable to prevent wear at the position of the rubber crawler track by contacting the piled and hardened mud and sand etc.
High wear resistance is obtained across the whole of the end portions in the peripheral direction of the rubber crawler track 10, by provision of the edge rubber c continuously in the peripheral direction of the rubber crawler track 10 (claim 9).
With regard to the relationship to the steel cord 12, the edge rubber c is present at the edge of the steel cord 12 when vulcanization molding the rubber crawler track 10, this therefore provides the effect of suppressing the flow of the steel cord 12 during vulcanization, namely suppressing running of the steel cord 12 within the rubber.
While not illustrated in the figures, the ground contact face side of the rubber crawler track 10 may be configured with edge rubber c (namely the outer peripheral side rubber b of the outer peripheral side may be configured with the edge rubber c. Claim 8). This enables the durability to be improved by stopping wear at the ground contact face end portion.
There are also guide projections 16 of projecting shape disposed regularly at the inner peripheral side of the rubber crawler track 10, formed from the inner peripheral side rubber a. The rubber crawler track 10 is wrapped around a non-illustrated sprocket provided at the machine body side, and the guide projections 16 engage with driving recesses provided to the surface of the sprocket. The rubber crawler track 10 is driven by transmission of driving force from the rotating sprocket. In the example of
In the present invention as above, by employing a different rubber at the left and right end portions of the rubber crawler track to that of the inner peripheral side and outer peripheral side, there is distinctly lower wear of the edge portions even with contact with hardened, piled material. This technology can be employed in a wide range of rubber crawler tracks, irrespective of whether they are of metal core-containing or metal core-less construction.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-173128 | Jun 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2007/062631 | 6/22/2007 | WO | 00 | 12/22/2008 |
