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Paramétrages

1. WO1983001408 - TRONÇONNEUSE UTILISANT UNE DENT DE COUTEAU LATERALE AMELIOREE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique
Description

A SAW CHAIN USING AN IMPROVED SIDE CUTTER TOOTH

Technical Field
This invention relates to saw chains for chain saws. More particularly, this invention relates to a new and improved saw chain using a novel side cutter tooth.

Background Art
United States Patent 3,745,870 disclosed a new and improved saw chain construction, including novel side cutter and raker teeth. The side cutter teeth could be easily formed and inexpensively manufactured. Flexible cutter elements permitted the tooth to flex laterally under cutting loads, thereby accommodating shocks from binding of the saw chain by forces directed inwardly upon the elements of the saw chain during cutting. The improved side cutter tooth included cutter element which had a complex curvature. First (as shown in Figure 4 of that patent) , each element curved outwardly in a radius indicated by arrow 29. Second, each cutter element curved upwardly in a second radius indicated by arrow 31. Third, each cutter element extended in a substantially straight course from the second radius 31 upwardly at a constant angle to the tip 32. Due to this final, straight portion, the side cutter element bent at the second radius 31 when it experienced inwardly directed forces. These inwardly directed forces reduced the 7β angle of the element by moving the tip inwardly toward the centerline of the kerf. The forces lowered the relative "position of the second radius 31 with respect to the first radius 29 and the body of the tooth, forming a crimp in the cutter element. Within a short time, the tooth would break at the crimp. Better performance is achieved by removing the complex bend fashioned in the side cutter teeth of United States Patent 3,745,870, as will be further described.

Disclosure of Invention
An improved side cutter tooth, having about three times better performance and longer life than earlier developed teeth, has a cutter element that includes a continuous-ly curved portion which is attached to the body of the side cutter tooth and which extends outwardly in a half-space adjacent the body to end in a cutter tip. The continuous curve of the cutter element causes the cutter element to bend substantially at the intersection of the body and the cutter element when the cutter element is exposed to inwardly directed forces (which tend to flatten the curved portion from the half-space into the plane of the body) . In this way, crimping of the cutter element is substantially eliminated. The intersection between the body and the cutter element provides greater resistance to deforming and, therefore, ensures that the tooth will perform better and have a lorfger life than elements having a complete curvature. The cutter elements, however, still flex laterally under cutting loads to reduce binding of the saw chain and to promote better performance. Thus, the improved side cutter teeth retain the advantages disclosed in United States Patent 3,745,870 and increase the cutting life of the teeth and saw chain.
Better performance for the side cutter teeth may also be achieved with a novel side cutter tooth having a substantially straight cutter element extending outwardly from the body. In this tooth, also, the area exposed to substantial bending stress will be the intersection of the cutter element and the body.
Saw chains for chain saws using the improved side cutter teeth of this invention perform better and require less maintenance due to reduction of breakage of'the side cutter elements. A particularly desirable repeating sequence of cutter teeth is disclosed and claimed. This repeating series includes, in order, an improved side cutter tooth, a right-hand raker tooth, a second side cutter tooth, and a left-hand raker tooth.

Brief Description of the Drawings
Figure 1 is a front elevation of a preferred side cutter tooth of this invention.
Figure 2 is a front elevation of an another preferred side cutter tooth of this invention.
Figure 3 is a side . elevation of a preferred repeating series of cutter teeth in a saw chain using the side cutter teeth of Figure 1.

Best Mode for Carrying Out the Invention
Figure 3 illustrates a repeating series of center- mounted cutting teeth, namely, side cutter teeth 10, right- hand raker teeth 12R, and left-hand raker teeth 12L. In a preferred chain, this repeating series continues, forming an endless belt of saw chain. Preferably, spacer links 14 separate the cutting teeth 10, 12R and 12L. . The spacer links 14 engage the drive sprocket to help drive the saw chain and space the cutter teeth sufficiently far apart so that the teeth perform optimally. Side links 16 and rivets 18 join the spacer links 14 and cutting teeth 10, 12R, and 12L in end-to-end pivotal relationship in the well-known manner, with the bottom surfaces of the side links 16 providing a surface for supporting the saw chain on the rails of a bar (not shown). The side links 16 are positioned on opposite sides of the center-mounted cutting teeth 10, 12R, and 12 and spacer links 14. The side links 16 preferably are identical and interchangeable.
United States Patent 3,745,870 is incorporated by reference into this patent application specification for its disclosure concerning saw chain and cutting teeth.
One improved side cutter tooth 10 of this invention is illustrated in Figure 1. The side cutter-tooth 10 comprises a first and a second link which are mirror images of one another and which are positioned adjacent one another to form a generally U-shaped cutting tooth capable of simultaneously, slitting both sides of the kerf when run as part of a saw chain. Each link has a body 20 including two rivet holes '32 for pivotal attachment of the tooth to the side

OMPI links 16 and, subsequently, to the other cutting teeth or spacer links. A root 22 extends outwardly from each body 20 in the plane of the body and is capable of engaging a sprocket of the chain saw when the saw chain is moving around the bar of the chain saw. (Similarly, the spacer links 14 include roots 22.) A leading depth gauge 24 extends laterally outwardly from the body 20 in a direction substantially opposite the root 22 and in the plane of the body 20. As its name indicates, the depth gauge regulates the depth of cut scored by the cutter tooth 10. The right-hand raker tooth 12R and left-hand raker 12L also have analogous depth gauges 24, which commonly are offset from the centerline of the saw chain to provide more efficient performance. Offset depth gauges 24 better ensure that the raker teeth 12L and 12R run at the same depth in the kerf as the side cutter tooth 10, and chip wood chips of more constant thickness, thereby improving the overall performance of the saw chain and chain saw. The value of offset depth gauges is more completely disclosed in a copending United States patent application to Mr. Lemery entitled "IMPROVED SAW CHAIN."
A trailing cutter element 26 extends laterally outwardly from the body 20 in a direction substantially opposite the root 22, yet is spaced somewhat behind the depth gauge 24. As best illustrated in Figure 1, the trailing cutter element 26 includes a continuously curved portion which is attached to the body 20 and which extends in a simple arc outwardly to a cutter tip 28. Thus, the continuously curved portion curls out of the plane defined by the body 20 into one of half-spaces defined by the plane. Analogously, the cutter element 26 of the adjacent, mirror- image link of the side cutter tooth extends outwardly in an arc into the other half-space defined by the plane. Figure 1 illustrates that the cutter tip 28 has a steeply angled internal bevel (preferably at 50" to the horizontal) and a narrow planar end to do the slitting and scoring. The angle from the vertical changes steadily along the continuous curve of the cutter element 26 rather than extending substantially at a. constant angle (as illustrated in Figure 4 of United States Patent 3,745,870). The continuous curve forces the cutter element 26 to bend, if at all, substantially at the intersection of the body 20 and the cutter element 26 when the cutter element 26 is exposed to inwardly * directed forces that tend to flatten the curved portion of the cutter element 26 from its half-space into the plane defined by the body 20. No longer does the cutter element 26 crimp (plastically deform) at a curve of the cutter ele- ment displaced from the body of the element, as commonly occurred in the side cutter teeth of United States Patent 3,745,870. The intersection of the cutter element 26 with the body 20 provides greater resistance to crimping of the cutter element 26, while it does not significantly hinder the flexing of the cutter element 26 during normal operation ' of the tooth 10 and saw chain.
For purposes of this description, "continuous curve" shall mean an arc of a circle of predetermined radius. A "continuous curve" curves concavely upwardly from the intersection of the body and curved portion of the link over the entire distance between the body and the cutter tip.
Preferably, each link of the side cutter tooth 10 includes a spur 30 which extends laterally outwardly from the body 20 substantially in the same direction as the root 22, yet spaced somewhat ahead of the root 22 in the same plane as the root 22. As more completely described in Mr. Lemery' s copending United States patent application entitled "AN ANTI-KICK SAW CHAIN AND A KICK-REDUCING METHOD," the spur 30 is a general thickening of the body 20 of the cutting tooth to allow the tooth to cock when the tooth engages an idler sprocket on the end of the bar of a chain saw. When the tooth moves in an arc around the bar, the relative distance between the leading depth gauge 24 and the trailing cutter element (in this case, 26) is substantially no greater than the distance between the leading depth gauge 24 and the trailing cutter element 26 when the saw chain is moving in a straight line along the bar. Cocking of the cutting teeth as they pass around the outer end bar greatly reduces the possibility of. encountering a kick by the saw chain and chain saw.
As illustrated in Figure 2 , an alternate embodiment of the side cutter tooth 10* of this invention includes a trailing cutter element 26* which extends laterally - outwardly from the body 20 in. a direction substantially opposite the root 22. The cutter element 26 includes a substantially straight portion attached to the body 20. The substantially straight portion ends in a cutter tip 28 f as shown. Like the continuously curved cutter element 26, the substantially straight cutter element 26' extends outwardly from the body 20 in one half-space defined by the plane of the body 20. The substantially straight portion of the cutter element 26' ensures that the cutter element 26' bends substantially at the intersection between the cutter element 26* and the body 20 when the cutter element 26' is exposed to inwardly directed -forces which tend to flatten the straight portion of the cutter element 26 ' out of the half-space into which it extends and into the plane of the body 20.
A saw chain including a repeating series of cutter teeth is illustrated in Figure 3. Preferably, an improved side cutter tooth 10 leads a right-hand raker tooth 12R. The right-hand raker tooth 12R leads a second side cutter tooth 10, which in turn leads a left-hand raker tooth 12L. The alternating chipping and scoring of the kerf improves performance and efficiency of the preferred saw chain of this invention.
While preferred embodiments of this invention have been illustrated and described, the invention is capable of modification and addition without departing from its basic principles. Accordingly, the invention is not intended to be limited to the exact embodiments illustrated, which are presented only as examples. The scope of the invention should be determined by reference to the claims interpreted in light of the prior art.