Patent Application
20100212782
The present invention broadly relates to a flail chain for use in debarking trees.
Bark needs to be removed from felled trees prior to the process of wood chipping. An apparatus commonly used for debarking trees is a flailing apparatus comprising a rotatable drum with a plurality of flail chains, each having one end fixed to the rotatable drum. Generally the flail chain comprises a plurality of substantially oblong shaped linkage elements.
During the debarking process, minor wear is caused to external surfaces of the linkage elements of the flail chains as they strike the tree bark. Significant wear occurs on internal surfaces of the linkage elements, particularly in opposing end regions where adjacent chain linkage elements engage with one another.
As a result of the aforementioned wear, flail chains must be regularly replaced. Consequently, the replacement of flail chains results in high capital expenditure and, by necessity, lost productivity in down time.
The present invention seeks to overcome at least some of the aforementioned disadvantages.
In accordance with a first aspect of the present invention there is provided a linkage element for a flail chain, the linkage element comprising more than two shank portions and more than two angled portions connecting said shank portions, wherein said shank portions and said angled portions define an interior space of the linkage element.
It will be understood that, in use, no more than two angled portions of the linkage element may be arranged to engage with corresponding angled portions of adjacent opposing linkage elements. Accordingly, at any one time, one or more of the remaining angled portions will be unengaged. As it is unlikely in the course of use that any one of the angled portions will always remain engaged or unengaged, the wear arising from friction between adjacent engaged angled portions is substantially distributed between the angled portions of the linkage element, thus prolonging the wear period in comparison with prior art linkage elements. For instance, a linkage element of the present invention having four engaging regions is likely to take substantially twice as long to wear to the same extent as a prior art linkage element having only two portions to engage adjacent opposing linkage elements.
In one embodiment of the invention, the interior space of the linkage element is regularly shaped. The term “regularly shaped” as used herein refers to a substantially symmetric polygon. For example, in one form of the invention four shank portions and four angled portions may define a substantially square shaped interior space. In an alternative form, six shank portions and six angled portions may define a substantially hexagonal shaped interior space. In a further alternative form five shank portions and five angled portions may define a substantially pentagonal shaped interior space.
A regularly shaped interior space advantageously promotes even distribution of wear amongst all of the angled portions in the linkage element as no single angled portion is shaped in a manner which would bias its engagement or otherwise with a corresponding angled portion of an adjacent linkage element in comparison to the other angled portions of the linkage element.
In one form of the invention an exterior surface of any one of said angled portions may be curved. In an alternative form an exterior surface of any one of said angled portions may define a substantially straight edge transversely extending across the exterior surface.
A further advantage of the present invention is that the exterior surface of the one or more unengaged angled portions protrude outwardly from the linkage element and contribute to the flailing efficiency of a flailing chain comprised of said linkage elements.
It will also be appreciated that wear on an exterior surface of the linkage element of the present invention will also be prolonged and evenly distributed in comparison with prior art linkage elements because of the foregoing reasons.
In one embodiment, a cross section of any one of said shank portions may be substantially circular.
In accordance with a second aspect of the present invention there is provided a flail chain for debarking trees, the flail chain comprising a plurality of sequentially linked linkage elements as defined in accordance with the first aspect of the invention.
In accordance with a third aspect of the present invention there is provided a flailing apparatus for debarking trees, the flailing apparatus comprising:
a shows a front elevation of a linkage element for a flail chain in accordance with one embodiment of the present invention.
b shows a cross-sectional view A-A of the linkage element of Figure la.
a shows a front elevation of a linkage element in accordance with a further embodiment of the present invention.
b shows a cross-sectional view B-B of the linkage element of
Referring to
The linkage element 10 shown in
The linkage element 10′ shown in
In other embodiments the linkage element 10 may be provided with an even number of shank portions 13 and angled portions 13 connecting said shank portions. Alternatively, the linkage element 10 may be provided with an odd number of shank portions 13 and angled portions 15 connecting said shank portions 13.
Regardless of the number of shank and angled portions 13, 15 in the linkage element 10 it is preferable that the body 12 of the linkage element 10 defines a regularly shaped interior space 14. In other words, it is preferable that the shank portions 13 of the linkage element 10 are substantially the same length as one another and the angled portions 15 of the linkage element 10 are disposed at substantially the same angle as one another.
A cross-section of the body 12 may be circular as shown in
In the embodiments shown in
It will be understood by a skilled person in the art that by virtue of a typical mode of manufacture of the linkage element 10 of the present invention, the inner and outer corners, 20, 20′, 22, 22′ of the body 12, 12′ of the linkage element 10, 10′ are curved. Additionally, over time the inner and outer corners 20, 20′, 22, 22′ are likely to become further curved by virtue of frictional wear.
In use, a plurality of linkage elements 10 are arranged to be sequentially linked with one another, thereby forming a flail chain 50 as shown in
It can be seen that adjacent linkage elements 10a, 10b are linked together by engaging respective angled portions 15a, 15b. The arrangement is such that outer corner 22a is disposed in interior space 14b of linkage element 10b, outer corner 22b is disposed in interior space 14a of linkage element 10a, and inner corners 20a, 20b bear against one another when the linkage elements 10a, 10b are placed under opposing tension. However, in contrast to prior art flail chains, in the embodiment shown in Figure 3, two opposing angled portions 15a′, 15b′ for each linkage element 10a, 10b remain unengaged. Furthermore, the two opposing outer corners 22a′, 22b′ for each linkage element 10a, 10b protrude outwardly from the flail chain 50. In use, the outwardly protruding outer corners 22a′, 22b′ strike the tree and therefore assist in flailing and removing bark from the tree. The outwardly protruding outer corners 22a′, 22b′ thus contribute to the flailing efficiency of both the flail chains 50 and a flailing apparatus 70, such as shown in
When linked together as described above, the interior space 14 of the linkage element 10 facilitates rotation of the linkage element 10 about a respective central longitudinal axis C such that there may be a period in which the unengaged angled portions 15a′, 15b′are engaged with adjacent angled portions 15, and the engaged angled portions 15a, 15b become disengaged from one another and protrude outwardly from the flail chain 50.
Over time, the ability of the linkage element 10 to rotate about its central longitudinal axis C ensures that any one of the angled portions 15 is likely to be disposed for a similar period of time in an engaged location as in an unengaged location in the flail chain 50. It follows that frictional wear on the external surface of the linkage element 10 caused by the flail chain 50 striking trees, although minor, is likely to be evenly distributed. The more frictional wear on the internal surface of the linkage element 10, particularly in the internal corners which bear against one another when adjacent angled portions are mutually engaged is likely to be evenly distributed because each angled portion spends a similar period in the engaged and unengaged locations in the flail chain 50.
As the frictional wear is distributed over more than two angled portions, the period of wear is effectively lengthened in comparison with prior art linkage elements where only two engaging portions of the linkage element are available for mutual engagement with adjacent linkage elements at any one time.
Flail chain 50 may comprise any combination of linkage elements 10 and prior art oblong linkage elements 52. Although
Referring now to
The drum 72 further comprises a shaft 78 for engaging with a drive so as to rotate the drum. The rotatable drum further comprises access holes 80 for accessing the rod 76 for maintenance purposes and the like.
It is to be understood that, although prior art use and publications may be referred to herein, such reference does not constitute an admission that any of these form a part of the common general knowledge in the art, in Australia or any other country.
For the purposes of this specification it will be clearly understood that the word “comprising” means “including but not limited to”, and that the word “comprises” has a corresponding meaning.
Numerous variations and modifications will suggest themselves to persons skilled in the relevant art, in addition to those already described, without departing from the basic inventive concepts. All such variations and modifications are to be considered within the scope of the present invention, the nature of which is to be determined from the foregoing description.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009200745 | Feb 2009 | AU | national |
