Patent Application
20130291702
The present invention relates to a cutting chain for a chainsaw. In particular, the present invention relates to a chain link used in the cutting chain.
Chainsaws are well known in the art, which typically include a cutting chain that rides over a guide bar, a drive sprocket and a nose sprocket, the sprockets being located at two ends of the guide bar. The drive sprocket is driven by a drive shaft whereas the nose sprocket rotates idly. The cutting chain has multiple drive links that have tangs for engaging with the drive sprocket, thereby imparting a motion to the cutting chain. The tangs also extend into a peripheral channel of the guide bar, thereby securing the cutting chain in place during the motion. The drive links also include one or more rivet holes for connection with other components of the cutting chain, such as, cutting links and tie straps. A cutting link may include a cutting portion and an integrally formed depth gauge such that, during operation, the depth gauge leads the cutting portion and controls a depth of cut into a wood portion.
However, while traversing over the nose sprocket the depth gauges may not properly work to control the depth of cut, thereby resulting in a kickback. This is not desirable as it may lead to personal injuries, damage to the chainsaw and improper cutting. In the prior art, modifications in the shape of the drive link for kickback reduction and an improved cutting performance are disclosed. For example, U.S. Pat. No. 7,637,192 issued on Dec. 29, 2009 and assigned to Blount, Inc. titled “Saw chain drive link with tail”, discloses a drive link having an extended portion at a tail of the drive link. The extended portion at the tail extends into a space in the gullet region of the cutting link. However, this type of design may not affect the cutting characteristics as the depth gauge setting remains unchanged. Also, there are chances that chips and other debris might get stuck in between the cutting link and the extended portion of the drive link.
In light of the foregoing, there is a need for a design which would control the cutting characteristics reducing the kickback effects along with reduced need for maintenance.
In view of the above, it is an objective of the present invention to solve or at least reduce the problems discussed above. In particular, the objective is to provide a novel design for a drive link used in a cutting chain of a chainsaw.
The objective is achieved according to a novel cutting chain described in claim 1. The cutting chain, which traverses in a cutting direction, includes at least one cutting link and at least one bumper drive link. The cutting link includes a cutting portion, a depth gauge, and a space in between the cutting portion and the depth gauge. The bumper drive link includes a body and a tail. Further, the bumper drive link is pivotally connected to and precedes the cutting link, in the cutting direction. The tail of the bumper drive link may include a straight portion and a bent portion; and the bent portion is oriented substantially perpendicular relative to a plane of the body of the bumper drive link. The bent portion extends into the space between the cutting portion and the depth gauge. This arrangement reduces kickback occurring during operation of the cutting chain.
According to claim 2, the height of the bent portion is lower then the height of the straight portion.
According to claim 3, the bent portion of the bumper drive link remains below the depth gauge of the cutting link while traversing a straight portion of a guide bar. Due to such an arrangement, the bent portion does not affect a cutting operation of the cutting chain, while the cutting chain is traversing along a straight path on the guide bar.
According to claims 4, the bent portion of the bumper drive link aligns with the depth gauge to form a substantially continuous edge while traversing a nose portion of the guide bar. Further, according to claim 5, the straight portion aligns with the depth gauge of the cutting link. This changes an effective area of the depth gauge, resulting in an improved control of the depth of cut, and reducing kickback effects.
According to claim 6, a free space is provided between the bent portion and the straight portion of the tail. This free space facilitates the elimination of chips from the cut portion, reducing maintenance needs. Further, according to claim 7, the free space between the bent portion and the straight portion of the tail is covered by the depth gauge of the cutter link while traversing a nose portion of a guide bar. This may reduce the occurrence of kickbacks.
According to claim 8, the cutting chain further includes at least one drive link. This drive link does not have the modified bent portion and does not precede any cutting link.
According to claim 9, the cutting chain is adapted to be used in a chainsaw for performing the cutting/sawing operation.
The invention will in the following be described in more detail with reference to the enclosed drawings, wherein:
The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments of the invention incorporating one or more aspects of the present invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. For example, one or more aspects of the present invention can be utilized in other embodiments and even other types of devices. In the drawings, like numbers refer to like elements.
As illustrated in
Typically, a cutting link 106 includes a depth gauge 118, a cutting portion 120, and a space 122 which is provided between the depth gauge 118 and the cutting portion 120. The space 122 between the depth gauge 118 and the cutting portion 120 is henceforth referred to as the gullet 122. The gullet 122 may facilitate a flow chips, produced from a cut portion, out of the cutting chain 100. According to various alternative embodiments of the present invention, the cutting portion 120 of the cutting link 106 may be of different shapes such as, but not limited to, chipper, semi-chisel, chisel and the like. Alternatively, the cutting portion 120 may also include cutting inserts made of suitable material, such as, composites, carbide, diamond, or the like.
Further, the bumper side link 112, following the cutting links 106 in a cutting direction 124, may have a structure with an elevated tail portion 126. This provides stability to the cutting chain 100 and also reduces the kickback effects occurring in the cutting chain 100. The other side links 110 may have a rectangular shape and connect the different components of the cutting chain 100.
According to an embodiment of the present invention, as illustrated in
According to an embodiment of the present invention, the bent portion 206 is substantially perpendicular to a plane of the body 202 of the bumper drive link 104. Further, the bent portion 206 includes a top surface 220 which have a quadrilateral shape, as illustrated in
As illustrated in
As illustrated in
As illustrated in
It may be apparent to a person ordinarily skilled in the art that the dimensions disclosed above are purely exemplary in nature, and various parts of the bumper drive link 104 may have any other dimensions within the scope of the present invention.
As illustrated in
In a further embodiment of the present invention, a thickness of the juncture bend 262 may be more then a thickness 264 of the body 202. This may further improve the mounting strength of the bent portion 206 on the body 202. Moreover, at the juncture bend 262, a convex projecting member may bulge in the direction of the bent portion 206. This may shift the tension point from the farther end of the bent portion 206 towards the body 202 of the bumper drive link 104. This may further increase the resistance of the bent portion 206 against breakage.
However, relative spacing between the bumper drive link 104 and the cutting link 106 is such that the bent portion 206 of the bumper drive link 104 aligns with the depth gauge 118 of the cutting link 106 while traversing the nose sprocket 302. Further, the bent portion 206 may form a continuous edge with the depth gauge 118 of the cutting link 106. Thus, an effective area of the depth gauge 118 increases and this may provide improved depth of cut control, thereby reducing kickback. Further, the bent portion 206 extends above the depth gauge 118 when the bent portion 206 of the bumper drive link 104 aligns with the depth gauge 118 of the cutting link 106. Moreover, the free space 210 between the bent portion 206 and the straight portion 208 is covered by the depth gauge 118. The height of the straight portion 208 also becomes substantially to the height of the the depth gauge 118 such that the straight portion 208 laterally aligns with the depth gauge 118 while traversing the nose sprocket 302. As a result, the effective area of the depth gauge 118 further increases, thereby reducing the occurrence of kickbacks. It may also be apparent from
In the drawings and specification, there have been disclosed preferred embodiments and examples of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation, the scope of the invention being set forth in the following claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP11/50398 | 1/13/2011 | WO | 00 | 7/12/2013 |
