The present invention relates to a cutter for an endless cutter device movable along a path for cutting a kerf in a work piece, said cutter in an upright position comprising:
A cutter of the above preamble is known from US-A-4,911,050, which discloses a bent-over depth gauge, whereby there is a face of the depth gauge sliding of a kerf produced. The present invention relates to an improved cutter, and more particularly to a cutter which has an improved depth gauge.
Cutters for endless cutter devices movable along a path for cutting a kerf in a work piece, such as may be found in a saw chain for cutting wood, generally have a cutter portion with a leading cutting edge and a depth gauge portion spaced forwardly of the cutting edge to control the depth of cut taken by the cutter. The depth gauge is instrumental in reducing the possibility of kickback during operation of the saw on which the chain runs.
Depth gauges in the past generally have included a single thickness of cutter material which extends upwardly in a region spaced forwardly from the cutter edge as disclosed in Silvon U.S. Patent No. 4,353,277. others have included bent-over depth gauge portions such as disclosed in U.S. Patents Nos. 5,085,113 and 4,989,489 to Pinney, U.S. Patent No. 4,911,050 to Nitschmann and U.S. Patent No. 4,841,825 to Martin.
The single thickness upright depth gauge as illustrated in 4,353,277 may have a tendency to dig into the work piece and not provide consistent cutting depth control. Further it is less stable than a bent-over depth gauge. The bent-over depth gauges illustrated in 4,911,050; 4,989,489; and 5,085,113 generally have substantially rectangular configurations as viewed in plan. The depth gauge of 4,841,825 wraps over the majority of the chain width and substantially encloses the space leading the cutter edge. Although these prior devices produce depth of cut control, they can produce excessive friction and drag and also inhibit the free flow of chips produced by the cutters. Explaining further if chips produced by the cutter are not allowed to flow easily under the top plate of the cutter they will continue to build up in the kerf, and the depth gauge and cutter will tend to ride thereover producing inefficient cutting.
The object of the present invention is to lend additional stability to the cutter during operation.
The invention is defined by independent claims 1 and 10.
Referring to the drawings, and first more particularly to Fig. 1, at 10 is indicated generally a section of a cutter chain for use with a chain saw. The chain includes left and right hand cutter links 12, 14, center drive links 16 and connector links 18, 20. All of these links have bores extending therethrough adjacent opposite ends. Rivets 22, acting as pivot pins, extend through aligned bores in the links to pivotally interconnect the cutter, drive, and connector links together.
The chain is supported for travel on a guide bar, a portion of which is indicated at 26 having a groove 28 in which depending tang portions of drive links 16 slidably move. The undersides of the cutter links and connector links ride slidably along supporting guide rails 26a, 26b at opposite sides of groove 28.
Referring to Figs. 2, 3 and 4, a left-hand cutter link 12 is illustrated in enlarged form to illustrate an embodiment of the present invention. The cutter, or cutter link, 12 includes a substantially planar upright body portion 32 having a center plane noted generally at 33. A pair of spaced apart rivet receiving bores 34, 36 extend through the rear, or heel, region 32a and the front, or toe, region 32b, respectively, of body 32. The centers of bores 34, 36 are aligned on a center line 39 which is generally parallel to the guide rails 26a, 26b on which the chain runs.
As is best seen in Fig. 2 the underside 41 of the cutter body under bore 36 in the toe region adjacent the front of the cutter is spaced a selected distance 41a beneath the center of bore 36. The underside 43 of the cutter body under the center of bore 34 is clipped so that it angles upwardly on progressing to the rear at an angle of 1-1/20 to 50 relative to centerline 39. The distance 43a to the underside of portion 43 from the center of bore 34 is less than distance 41a, preferably in a range of 0.01 to 0.08inch. This distance will vary in relation to the size and style of cutter.
The rear end region 32a of the body has a cutter portion 40 thereon. The cutter portion includes a cutter top plate portion 42 and a forwardly facing cutting edge 44. The cutter top plate portion is bent over at substantially a right angle relative to and overlies body portion 32 of the cutter. The cutting edge 44 extends transversely of the plane of the body portion and overlies the body portion.
The cutting edge 44 is spaced a selected elevation above the body portion for cutting purposes. The free outer end of the cutting edge 44 is spaced a distance 45 from the center plane 33 of the body portion.
A depth gauge portion 46 is mounted on the front end region 32b of the body portion. The depth gauge portion includes a plate portion 48 which is bent over at a substantial angle relative to the plane of the body portion and has a substantially planar upper surface 48a which is inclined continuously downwardly on progressing forwardly in the cutter. The depth gauge portion in the illustrated cutter is bent over at substantially a right angle relative to the plane of the body portion and overlies the body portion. As is best seen in Fig. 4 a juncture section 52 disposed at a slight angle relative to the plane of body portion 32 interconnects the body portion and depth gauge portion and the depth gauge is cantilevered outwardly therefrom with a free outer edge.
Referring to Fig. 3, it will be seen that the depth gauge plate portion 48 is multi-angular, and in this embodiment is substantially pentagonal. The rearwardly facing rear edge of the plate portion 48 has a central portion 56 nearest cutting edge 44. The rear edge has opposed side portions 58, 60 which in the illustrated embodiment extend forwardly from central portion 56 and diverge from each other on progressing forwardly from the central portion. As is seen in Fig. 3, the central portion 56 is formed by the juncture of side portions 58, 60, is substantially a convex curve, and has a width which is a minor portion of the overall width of the depth gauge. The side portion 58 could extend perpendicular to center plane 33 from central portion 56, if desired, with side portion 60 alone extending forwardly and downwardly from the central portion. However, it is believed that operational benefits occur by having both sides 58, 60 angled forwardly from the central portion.
Referring to Figs. 3 and 4, cutting edge 44 has a defined width 47 extending laterally, or transversely, of the cutter, and central portion 56 of the rear edge of the depth gauge is disposed intermediate, and here substantially centrally of, opposite ends of the cutting edge.
As side portions 58, 60 extend forwardly from central portion 56, not only do they diverge from each other but they also slope downwardly from central portion 56. Thus, central portion 56 is disposed at the greatest elevation relative to the body portion and nearest the elevation of cutter edge 44. The central portion 56 of the rear edge of the depth gauge is aligned forwardly of an intermediate region of the cutting edge 44.
Extending forwardly from rear edge side portions 58, 60 are opposed side edges 64, 66. These side edges converge toward each other as they progress forwardly from their junctures with side portions 58, 60. They join with opposite ends of front edge 68 which extends substantially laterally of the plane of the body portion.
The juncture between rear edge side portion 60 and side edge 66 is formed in a convexly curved outer edge 70 which is at the region of maximum width for the depth gauge. Since the depth gauge plate portion 48 is joined only along side edge 64 to juncture portion 52, it has a free side region extending away from the body portion which includes rear edge side portion 60 and side edge 66 which converge in the convex curve at central region 70. As is best seen in Figs. 3 and 4, the maximum width portion 70 of the depth gauge is disposed at an elevation intermediate the highest and lowest portions of the depth gauge, between the front and rear edges of the depth gauge. As seen in Figs. 3 and 4 in the embodiment illustrated the maximum width 71 of the depth gauge portion is at least as great or greater than the width 47 of the cutter portion 40 following it. Further, the outer edge 70 of the depth gauge projects a distance 73 laterally of central plane 33 which is greater than the distance 45 for cutter edge 44.
Referring to Fig. 4, a right-hand cutter 14 is illustrated which follows cutter 12 in the chain as shown in Fig. 1. A major portion of the top plate of the cutter 14 and its depth gauge are broken away so that they do not interfere with illustration of the major portions of cutter 12. However, it will be seen that central region 70 of depth gauge 46 in the embodiment of cutter 12 illustrated extends outwardly beyond the width of top plate 44 toward the side of the kerf which would be cut by the side cutting edge of cutter 14. Such extension of the depth gauge toward the opposite side of the chain has been found to improve chain stability during cutting.
In Fig. 2 distance 74 denotes the elevational distance that the uppermost portion of depth gauge 46 is spaced below the uppermost edge of cutting edge 44. This is known generally as the depth gauge setting for the cutter.
Referring still to Fig. 2, depth gauge 46 is spaced a distance forwardly of cutter portion 40 to provide an open gullet space 78 therebetween.
Various angular relationships between the sides, or edges, of the depth gauge are illustrated in Fig. 3. A line 82 is drawn extending normal to the central plane of the cutter body. Angles 84 and 86 denote the orientations of rear edge side portions 58, 60, respectively, relative to line 82. An included angle 88 is defined between rear edge side portions 58, 60. Another line 90 is drawn extending normal to the central plane of the cutter adjacent the forward end of the depth gauge. Angles 94, 96 denote the orientations of side edge 66 and front edge 68, relative to line 90.
An exemplary cutter will now be described having a pitch distance between the center of bores 34, 36 of approximately 0.390 inch, and an overall height of approximately 0.520 inch, depth gauge setting distance 74 may be in a range of 0.015 to 0.030 inch. The following sizes, angles and distances are measured along a horizontal plane, indicated generally at 91 in Fig. 2, and as viewed in plan in Fig. 3. Depth gauge portion 46 may have an overall length of approximately 0.175-0.30 inch. Outer edge 70 of the depth gauge would be in a range of 0.050 to 0.150 inch forwardly of rear edge central portion 56. Angle 84 may be in a range of 00 to 300 (preferably 100 to 300), angle 86 in a range of 100 to 400, and included angle 88 in a range of 1100-1700, and preferably 1100 to 1600. Angle 94 is in a range of 100-550 and angle 96 in a range of 00 to 150. The downward slope 98 of the upper planar surface 48a as shown in Fig. 2 is in a range of 250 to 350.
Referring to Fig. 4, a dashed line 100 illustrates generally the outline of substantially rectangular depth gauges of prior art devices. Such have not permitted free flow of cut chips to pass easily into the gullet region and under the top plate 42 of the cutter. This inability to free the kerf of debris has resulted in vibration, excessive friction, and other impediments to efficient cutting.
The configuration of the present embodiment with a depth gauge portion which has angularly disposed sides 58, 60 and a central region 56 at its greatest elevation intermediate the width of the cutter edge permits free flow of chips past the depth gauge rear edge side portions so that debris flows freely into the gullet region and under the cutter top plate toward the chassis of the chain. This free flow of chips is further enhanced by the positioning of the side edges and front edge. Further, friction is minimized by minimizing the amount of the depth gauge which engages the kerf and debris within the kerf.
It will be seen that central portion 56 is the highest and rearwardmost portion of the depth gauge and that remainder portions of the depth gauge incline downwardly and forwardly therefrom.
Although the bent-over depth gauge is described here on a cutter with a clipped heel, it should be recognized that the depth gauge configuration can be used in cutters without a clipped heel. The depth gauge of the present invention provides many operational benefits independently of, as well as in conjunction with, a clipped heel configuration.
Figs. 5-7 illustrate another embodiment of the invention. A cutter 12a is illustrated having a cutter portion 40a with a forwardly facing cutting edge 44a.
A depth gauge portion 46a is mounted on the front end of the body portion of the cutter and is bent over at a substantial angle relative to the plane of the body portion. It has a substantially planar upper surface 48b which is inclined downwardly on progressing forwardly in the cutter.
The depth gauge portion 46a illustrated in Figs. 5-7 is multi-angular, and in this embodiment is substantially hexagonal.
The configuration of the depth gauge 46a is somewhat similar to that previously described for depth gauge 46, except that in this configuration, rather than having a convexly curved outer edge region 70 between edges 60 and 66, there is a substantially flat side 70a provided between side edges 60a, 66a.
In operation of a saw chain having a cutter constructed as illustrated, as the saw chain is driven forwardly the depth of cut is controlled by depth gauge portion 46 leading cutting edge 44. The depth gauge portion having the configuration illustrated provides effective depth gauge control, chain stability and kickback minimization while permitting chips produced in the kerf of the work piece to flow freely past the depth gauge and into the chassis region of the chain underlying the bent-over cutter portion 42 of the cutter.
Further, with the clipped heel portion of the cutter, and a connector link on the opposite side with a clipped heel portion paralleling the clipped heel of the cutter as illustrated for link 18 in Fig. 1, such is able to rock rearwardly in the articulated chain to reduce vibration. When this occurs the effective depth gauge setting 74 is reduced to reduce vibration in the chain. The configuration of the bent-over depth gauge acts in conjunction with the clipped heel portion to provide lateral stability in the chain should such rocking occur. Explaining further, previous cutting chains which may have had clipped heel portions have included a generally planar upright depth gauge which produced very narrow contact with the work piece. This could allow rotation of chain parts about the central axis extending longitudinally of the chain. With the present depth gauge configuration, having a width which is major portion of or greater than the width of the cutter, the depth gauge will engage the kerf to provide greater stability, and reduce the tendency of the chain parts to rotate about the central axis of the chain.
The bent-over depth gauge design of the present embodiment provides sufficient width to produce kickback control for safety, while still producing improved chip flow.
It shall be noted that the two diverging sides 58 and 60 of the rear edge extend forwardly and downwardly with respect to the cutting edge, whereby thus none of these sides extends perpendicular to the plane 33 of the body portion.
While a preferred embodiment of the invention has been disclosed herein, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the spirit of the invention, as defined by the appendant claims.