Patent Application
20080110317
The present invention relates to the field of saw chains, and in particular to a saw chain having one or more links with foot portion with an offset feature.
Chain saws typically include an endless saw chain disposed to articulate around a saw bar comprising various coupled links including cutter links, drive links, and tie straps. The cutter links and tie straps are typically in sliding engagement on bar rails of the saw bar. The cutter links can be used for cutting wood, concrete, ice and other materials.
The cutter links and tie straps which ride on the saw bar rails are generally sized to match the bar rail width/thickness. This allows the bar rail and the respective bottoms of the cutter links and tie straps to wear against each other evenly and keep one or the other from getting a non-worn area known as a “knife edge”. A knife edge is undesirable because it can cause tight joints or burrs or be a source of crack initiation.
The kerf of the saw chain is generally the width of the cut that a chain makes as it cuts through material. It is controlled by the distance from the farthest outside offset dimension of the cutting portion of the cutter link on respective opposite sides of the chain. Making the kerf of the chain as narrow as possible is desirable to minimize the power necessary for cutting. Prior attempts to narrow the Kerf, however, has generally resulted in 1) knife edging occurring on the bar rails and/or the links by using thinner chain components; 2) an unacceptable decrease of kerf to bar clearance; 3) weakening of and/or limiting the length of the bar by virtue of narrowing the bar in conjunction with narrowing the components and/or to maintain a satisfactory kerf to bar clearance; and 4) reducing the cutter offset, which undesirably reduces the amount of clearance between the kerf wall and the bar, thereby negatively affecting the chip flow up the side of the bar and chain.
Embodiments of the present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings. Embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings.
In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments in accordance with the present invention is defined by the appended claims and their equivalents.
Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments of the present invention; however, the order of description should not be construed to imply that these operations are order dependent.
The description may use perspective-based descriptions such as up/down, back/front, and top/bottom. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of embodiments of the present invention.
The terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” may mean that two or more elements are in direct physical or electrical contact. However, “coupled” may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other.
For the purposes of the description, a phrase in the form “A/B” or in the form “A and/or B” means (A), (B), or (A and B). For the purposes of the description, a phrase in the form “at least one of A, B, and C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C). For the purposes of the description, a phrase in the form “(A)B” means (B) or (AB) that is, A is an optional element.
The description may use the phrases “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present invention, are synonymous.
Embodiments in accordance with the invention provide a saw chain that may help to reduce power consumption, improve performance, and/or efficiency when cutting material, such as wood, concrete, and the like. In various embodiments, the rail engaging components, such as cutter links and/or tie straps may have an offset foot print, either within the link itself and/or among multiple links. Embodiments in accordance with the invention may provide a cutting chain that also allows for a bar thickness that is practical for the desired cut length (e.g. >20 inches), while still utilizing a thinner chain width. Such an offset may have a number of uses, including, but not limited to allowing the use of narrower chain components without decreasing the bar width or cutter portion width, resist knife edging on bar rails that are wider than the thickness of a link, providing space for transporting and/or depositing lubricant (such as water or oil) onto the bar rail itself, and allow for improved penetration of the drive sprocket into the chassis of the chain without the need to include strength sacrificing notches in the link.
In various embodiments, the foot print of the individual rail engaging link (e.g. tie strap 102 or cutter link 100) may have an offset feature and/or configuration within the footprint from a first portion of the foot to a second portion of the foot (referred to herein as an internal offset). In one embodiment, a link first portion 116 and a link second portion 118 may be separated by a notch 117. The link first portion 116 may be offset towards the outer portion of the rail 110, while the link second portion 118 may be offset towards the inner portion of the rail 110. Other embodiments may include an opposite configuration for offsetting the footprint.
In various embodiments, the offset of the link foot print may be from rail engaging link to rail engaging link, which is referred to herein as alternating offset. In one embodiment, for example, the first portion and the second portion of a first rail engaging may be the same and offset to a first portion of the bar rail (e.g. offset towards the inner portion of the bar rail), and a second or trailing rail engaging link may have a first portion and a second portion having a footprint that is offset towards a second portion of the bar rail (e.g. offset towards the outer portion of the bar rail). In various embodiments, such an alternating offset foot print may help ensure generally even wear on the rail.
In various embodiments, second rail engaging link 302 may be disposed to engage a second guide bar rail 313, which may be disposed on an opposite side of groove 308 from first guide bar rail 312. Second rail engaging link 302 may be, for example, an opposing tie strap, and illustrates an alternating offset footprint in accordance with various embodiments. Both the forward portion 316′ and rearward portion 318′ may be offset towards a first portion 322′ of guide bar rail 313, for example by virtue of being narrower or thinner in configuration to help improve efficiency. A leading and/or trailing rail engaging link (not shown) may have a forward portion and rearward portion having the same offset, but rather directed towards the outer portion 324′ of rail 313.
As discussed,
In various embodiments, offset feature 430 may help carry lubricating fluid (e.g. oil, water, etc.) for distribution along the path of travel. In various embodiments, fluid carried by the cavity 432 of offset feature 430 may be directly deposited onto the guide bar rail at the wear interface, thereby lubricating the rail for the rail engaging links. Such enhanced lubrication may improve chain longevity, as well as improve performance and efficiency as the additional lubrication of the rail helps resist rail wear, which in turn helps reduce the power input required for the same abrading activity.
In various embodiments, offset feature 430 may be disposed anywhere along the link bottom 410. In some embodiments, the offset feature 430 may be disposed generally in the central portion of the link 402, e.g. between the center axis of the rivet holes 440 and 442. In such an embodiment, the cavity 432 of the offset feature 430 may allow for improved penetration of a drive sprocket tooth into the chassis of the chain. Such a configuration may have the benefit of allowing for thinner, but generally stronger chain to be used, as the links such as tie straps would not need to include the typical notch/cut out to allow drive sprocket tooth penetration. Further, in various embodiments, a narrower link body could be used to again improve efficiency of the cutting chain and reduce power demands.
Various embodiments may include saw chains having a mix of cutter links and/or tie straps, some or all of which may have an offset footprint. Further, the offset may be an internal offset and/or an alternating offset. In various embodiments, the rail engaging link offset may be formed in the rail engaging link in a variety of ways, such as pressing, bending, coining, stamping, etc.
In addition to the discussion and illustrations of various embodiments above, it is to be understood, however, that a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope of the present invention. Those with skill in the art will readily appreciate that embodiments in accordance with the present invention may be implemented in a very wide variety of ways. This application is intended to cover any adaptations or variations of the embodiments discussed herein.
The present application claims priority to U.S. Provisional Patent Application No. 60/866,004, filed Nov. 15, 2006, entitled “SAW CHAIN LINK WITH TAPER AND/OR OFFSET,” the entire disclosure of which is hereby incorporated by reference in its entirety, and Provisional Patent Application No. 60/957,427, filed Aug. 22, 2007, entitled “AGGREGATE CUTTING SAW CHAIN,” the entire disclosure of which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60866004 | Nov 2006 | US | |
| 60957427 | Aug 2007 | US |
