IMPROVED SAW CHAIN

Abstract: To provide removal of relatively uniform thickness chips by both the right-(19R) and left-hand (19L) rakers of a saw chain, the raker teeth (17) of this invention provide for an offset depth gauge (18) so that the raker element (19L) will run in the kerf at a substantially constant depth corresponding to the depth run for a side scoring element (16) and a first raker tooth (19R). Individual raker teeth (17) of this invention and saw chains incorporating the novel raker teeth (17) are described.

Description: Descript ion IMPROVED SAW CHAIN Technical Field The present invent ion re lates to an improved chain for a chain saw, particularly including a novel tooth including a laterally depth gauge. Background Art Many cutter teeth and raker teeth combinations have been used in prior art chain saw chains . A part icu¬ larly good example of- a saw chain is disclosed in United States Patent 3 ,745 , 870. ( This patent is incorporated by reference into this specification. ) Although effective , the raker teeth of United States Patent 3 , 745 , 870 will be modi¬ f ied to improve the overall cutting opera t ion of a saw chain. " In particular, because the depth gauge of the raker teeth is set at the centerline of the kerf , the raker teeth have a tendency to dig into the wood and to take too large- a chip at one time. The tendency to dig in is created because the depth gauge tends to run at the low point of the kerf rather than at a constant depth equal to the depth at which the side cutter element runs while scoring the kerf . By taking too thick a chip, the raker tooth makes cutt ing rougher, increases the tendency of the saw to kick , and reduces control for the saw. Taking too large a chip re¬ quires greater power to drive the saw chain with the conse- quent production of a greater amount of heat in cutting . Finally, raker teeth of the design of United States Patent 3 ,745,870 have a tendency to rock in the kerf, thereby lead¬ ing to crooked cuts as the chain runs in the kerf , .especial¬ ly in angular cutting at an acute angle to the grain . The rocking tendency is generated by the rakers taking ch ips of different, dimension, causing different slant angles for the chain in the kerf . Therefore , improvements are poss ible by provid ing a cha in wh ich will take relat ively the same OMPI thickness pf chips with each raker, and will take a chip only of a thickness to which the side cutter elements have scored the kerf. Disclosure of Invention An improved chain provides the chipping of relatively uniform thickness chips from the kerf. Optimal cutting efficiency is attained and, consequently, less power is consumed by using a raker tooth having an offset depth gauge. In a standard saw chain, the first raker tooth will cut a first chip from the kerf of a width approximately equal to one-half the width of the kerf plus one-half the thickness of the body element of the raker tooth. That is, the first chip will always be wider than one-half the width of the kerf which is formed by the chain. If a centerline depth gauge is used, the second raker tooth will tend to chip a double-thickness chip from the kerf because the depth gauge of the second raker tooth will run at the bottom of the kerf on the side where the first raker tooth removed its chip. An offset depth gauge overcomes this problem and pro¬ vides the more efficient saw chain of this invention. The offset bends the depth gauge out of the plane of the body of the raker tooth so that it will run on the unchipped portion of the kerf. In operation, then, a side cutter element will run along a generally flat kerf to score both sides of the kerf to a predetermined depth. A first raker tooth will run along the kerf at the same depth as the side cutter element to remove a first chip slightly greater in width than one- half the ultimate kerf width. Preferably, a second side cutter element will rescore the kerf. Then, a second raker tooth, with an offset depth gauge, will run at the same depth as the side cutter elements and first raker " tooth to remove the remaining chip in the kerf. The offset depth gauge for raker teeth of this invention improves chain saw efficiency by removing rela¬ tively constant thickness chips from the kerf. The work of the saw blade is balanced so less power is required and less heat is generated. The saw chain has less tendency to dig in or to kick and is, therefore, more controllable. Rocking of the chain is reduced because the chain tends to remain in a constant conformation with respect to the bottom of the kerf. Reduced rocking, in turn, reduces the tendency of the chain to cut crooked or to run in the kerf, especially when cutting at an acute angle with the grain. These features provide much greater chain saw efficiency and smoother cutting. Brief Description of the Drawings Fig. 1 is a side elevation of a preferred series of teeth in a saw chain made according to this invention. Fig. 2 is a top plan view of an offset depth gauge on a raker tooth of this invention. Fig. 3 is a detailed side elevation of the raker tooth of Fig. 2. Fig. 4 is a front elevation of the raker tooth of Fig. 2. Fig. 5 is a side elevation of another preferred series of teeth in a saw chain made according to this invention. Best Mode for Carrying Out the Invention Referring to Figure 1 , a repeating series of links is shown in one preferred order and arrangement for forming an endless loop of chain. The particular chain described by way of example in the present specification will be under¬ stood to be a 3/8-inch pitch chain, with all sizes and dimensions referred to being related thereto. The repeating series includes side links 11 attached with rivets 12 to center links in end-to-end pivotal relationship in a well- known manner. The bottom surfaces of the side link ' s 11 pro¬ vide a surface for supporting the chain on the rails of a saw bar. The side links 11 are merely positioned on oppo- site sides of the chain and are identical and interchange¬ able. The center links perform three different func¬ tions. Some are spacer links 13, including sprocket- OMPI engaging root portions 14 which engage the drive, sprocket of the engine or power input of the chain saw for driving the chain in the direction indicated by the arrow 15. The root portion 14 of all center links is identical, as shown in Figure 1. Some center links are side cutter elements 16. These side cutter elements 16 are fully described in United States Patent 3,745,870, which is incorporated by reference into this specification for this purpose and for the remain- der of its description. Some of the center links are raker teeth 17, having either a right- or left-hand conformation. The side cutter elements 16 and raker teeth 17 include depth gauges 18 spaced a predetermined distance ahead of the cutting elements of the center links. As best shown in Figure 2, a preferred raker tooth 17 of this invention includes an offset depth gauge 18 and a raker cutting element 19R. Line 20 defines the centerline for the chain and the centerline of the kerf. The line 20 also is used to define a plane dividing the kerf into two half-spaces. As shown in Figure 2, the depth gauge 18 and raker cutting element 19R are bent out of the plane of the centerline 20 into one of the half-spaces defined by the centerline. The raker element 19R is designed to remove chips of wood from the kerf at a depth set by the depth gauge 18. To ensure that the raker cutting element 19 will cut a relatively uniformly thick chip from the kerf, the depth gauge 18 preferably is offset from the plane defined by the centerline 20 of the chain by a distance at least equal to the width of the body portion 20 of the raker tooth 17. This offset is best shown in the front elevational view of Figure 4. Offset is necessary because the rake ' cutting element 19R will tend to remove a chip equal in width to or slightly greater than one-half the desired width of the kerf plus one-half the width of the body portion 21 of the tooth 17. If the depth gauge 18 is merely of the centerline vari¬ ety, as disclosed in United States Patent 3,745,870, the second raker tooth in any repeating series will run along the bottom of the kerf in the cut made by the first raker tooth. At this depth, the raker cutting element will tend to chip out a double-thickness chip of wood rather than the desired chip of equal thickness. This tendency to chip thicker chips from the kerf causes the saw to operate inefficiently. An example may make the problem more easily under¬ stood. If the depth gauge of the side cutter element 16 is set at 0.035 inch, the score of the initial side cutter element will be 0.035 inch on both the left and right edges of the kerf. The first raker tooth 17 (a right-hand raker tooth as shown in Figure 1) will have its depth gauge run along the same level as the depth of the side cutter element 16. Therefore, the raker element 19R (designating a right- hand raker tooth) will remove a chip of approximately 0.035- inch thickness from the kerf. The second raker tooth (a left-hand raker tooth with a aker element designated 19L in Figure 1 ) will also run at the same depth as the side cutter element 16 and first raker tooth because of its offset depth gauge 18. That is, the depth gauge 18 will run upon th.at portion of the kerf which was not chipped away by the first raker tooth 17. Again, the depth gauge 18 of the second raker tooth will regulate the cutting of the left-hand raker element to remove a chip approximately 0.035 inch in thick- ness. Thus the kerf will have a generally smooth bottom after passage of the side cutter element and two raker teeth. With a centerline depth gauge configuration, however, the side cutter element will score the edges of the kerf to the depth of 0.035 inch. The first raker tooth will remove a chip of thickness 0.035 inch from slightly more than one-half of the kerf. The second raker tooth will often run upon the low point of the kerf where the first raker tooth has removed a chip already, and, therefore, the second raker tooth will remove a chip 0.070 inch in thick¬ ness. Because the side cutter element has only scored the sides of the kerf to 0.035-inch thickness, removal of the extra-thick chip will require additional power. Also, for OMPI the further work of the repeating series of cutting ele¬ ments, the chain will be slighlty tilted by the 0.035-inch offset between the two portions of the kerf. Not all the depth gauges 18 in the chain need be offset depth gauges. In fact, only one of the depth gauges need be offset if the series of. Fig. 1 is used. The offset depth gauge need only be on the center links of the second raker tooth 17, which follows the first raker tooth. If more than three cutting elements are used in a repeating series, of course, all raker tooth depth gauges following the first raker tooth should be offset. Thus, in another preferred chain repeating series (shown in Fig. 5), the chain has the following sequence: a side cutter element, a right-hand raker, a second side cutter element (having an offset depth gauge, if desired), and a left-hand raker hav¬ ing an offset depth gauge. Offset depth gauges are unneces¬ sary for the elements before the first raker tooth because, prior to passage of the first raker tooth, the kerf is rela¬ tively smooth. Because the kerf is relatively smooth, how- ever, it does no harm to have offset depth gauges for all of the elements. When using an offset depth gauge, the offset should be such that the depth gauge will contact that por¬ tion of the kerf which has not been removed in earlier cut¬ ting in that series of teeth. Ordinarily, bending the depth gauge into the half-space in which the raker element of that depth gauge is disposed at least a distance of one-half the width of the body of the element will provide the desired offset. Offset depth gauges on the side cutter elements generally are not used, because their use would result in a large increase in the production cost of the saw chain. Offsetting these elements would result in four teeth por¬ tions to make the side cutter elements and would complicate the assembly accordingly. Therefore, ordinarily, " only the raker teeth use offset depth gauges.

Claims: I claim: 1. A center-link-mounted raker tooth for -use with the saw chain of a chain saw, comprising, in an integral unit: (a) a body defining a plane for the tooth; (b) a root extending from the body in the plane and being capable of engaging a sprocket of the chain saw; (c) a raker cutting element extending from the body laterally opposite the root, capable of raking chips from a kerf, and bending into a tip in one half-space defined by the plane; and . (d) an offset depth gauge extending from the body laterally opposite the root and bending into the same half-space as the tip of the raker cutting element. 2. The tooth of claim 1 wherein the depth gauge is offset by at least the thickness of the body of the tooth. 3. The tooth of claim 1 wherein the depth gauge is offset at least one-half of the width of the body of the tooth to ensure that the tooth will sense a constant depth in the kerf and will produce relatively constant thickness chips. 4. A chain for a chain saw comprising a plurality of pivotally joined links joined in a repeating series wherein each series includes a plurality of center links pivotally connected to side links, wherein the center links include bodies having sprocket-engaging roots, wherein the center links include some raker teeth to remove chips and at least one side side element to score a kerf, and wherein each raker tooth includes an offset depth gauge, which runs in the kerf displaced from the center¬ line of the kerf, thereby providing a substantially constant- depth run for the chain in the kerf and providing more even thickness chips removed by the raker teeth. 5. The chain of claim 4 wherein the series includes at least one side cutter element, at least one right-hand raker tooth, and at least one left-hand raker tooth. 6. The chain of claim 5 wherein the side cutter elements and raker teeth have at least one spacer link between one another. 7. The chain of claim 6 wherein the side cutter elements are made from flexible metal to allow flexing and deformation under normal cutting loads in the region between the cutter element and the body portion of each center link. 8. The chain of claim 7 wherein the side cutter elements are disposed to flex laterally outwardly during cutting to reach laterally beyond the mechanical width of the link. 9. A chain for a chain saw comprising a plurality of pivotally joined links assembled in a repeating series to form an endless belt wherein each series includes at least one flex¬ ible metal side cutter element, including a depth gauge, to score a kerf, at least one spacer link, -a first raker tooth, including an offset depth gauge, which runs in the kerf dis¬ placed from the centerline of the kerf, wherein the first raker tooth removes chips from one side of the kerf, at least one spacer link, and a second raker tooth, including an offset depth gauge, which runs in the kerf displaced from the centerline of the kerf, wherein the second raker tooth removes chips from the other side of the kerf, thereby creating a substantially smooth bottom for the kerf after passage of both raker teeth. 10. The chain of claim 9 wherein the first and second raker teeth are mirror images of one another. 11. The chain of claim 9 wherein the depth gauges are set so that each raker tooth removes chips only where previously scored by the side cutter element by maintaining the depth gauge track height the same for the side cutter element and raker teeth by means of the offset depth gauges. 12. The chain of claim 9 wherein only the second raker tooth has an offset depth gauge and wherein the side cutter element and first raker tooth have a centerline depth gauge. 13. The chain of claim 9, further including a second side cutter element disposed in the series between the first raker tooth and second raker tooth.

Inventors: LEMERY DOUGLAS J, LEMERY, DOUGLAS, J.
Applicants: LEMERY KOLVE CHAIN CO, LEMERY-KOLVE CHAIN COMPANY
Application year: 1982
Main classification: B27B33
IPC codes: B27B33