1. Field of the Invention
The present invention relates generally to saw blades and, more particularly, to circular saw blades including a plurality of teeth along the periphery thereof.
2. Discussion of the Prior Art
It is known to provide a saw blade having a plurality of evenly sized and spaced cutting teeth formed around its circumference. This standard circular saw blade design has found many applications in the cutting of wood as well as metal members and may be modified to provide certain types of cutting and planing functions. For example, a standard saw blade may include a small number of rip saw type teeth around its circumference so as to provide a rapid cutting of the work material, or a large number of planing type teeth which perform a slow yet smooth cutting of work material. Typically, a blade with a relatively small number of teeth is employed for applications where it is desired to make fast cuts with little concern for the smoothness of the cuts. Alternatively, when smoothness is of importance in an application, a blade having a relatively large number of teeth is employed. Such a blade presents more teeth to the area of the work material to be cut so as to smooth the cut surface as the blade cuts therethrough. However, the speed of the cut is ordinarily reduced.
It has been, and will continue to be, an object of saw blade designers to design saw blades capable of providing both fast and smooth cuts which permit the number of operations to be performed on work materials to be reduced along with the amount of time of cutting operations. It is a further goal of many designers to provide a saw blade capable of providing an acceptable level of performance for an extended period of use relative to the typical life span of other known saw blades.
One known design is illustrated in U.S. Pat. No. 156,748, to Andrews, wherein a single saw blade is comprised of four groups of teeth, each including a number of variably spaced cutting teeth. In the Andrews patent, the first tooth of each group of teeth is the longest and each succeeding tooth has a gradually diminished pitch so that the last one in the group has the shortest pitch. All of the teeth of the Andrews patent are of the same radial depth. As disclosed in the Andrews patent, the purpose of this construction is to increase the amount of work that can be done with a fixed amount of power.
Another known saw blade construction is disclosed in U.S. Pat. No. 352,867, to Greist, and includes the use of two types of cutting teeth in a single blade. In the Greist patent, groups of each type of cutting tooth are arranged around the circumference of the blade to provide alternating types of sawing and planing action during each rotation of the blade. For instance, in an illustrated embodiment of the Greist patent, evenly spaced rip saw teeth having a large pitch and deep radial depths are grouped together and these groups are separated by groups of evenly spaced cross-cut teeth having a small pitch and shallow radial depths. In this manner, Greist attempts to achieve a smooth cutting action with less power than is required by conventional blades.
The circular saw blade illustrated in U.S. Pat. No. 2,720,229, to Drake, includes a substantially standard construction in which a plurality of evenly spaced teeth are provided around the circumference of the blade. However, in the Drake blade, a plurality of, e.g., three, short teeth are provided at equally spaced intervals along the circumference to separate the remaining teeth into groups. In addition, carbide tips having differing configurations are alternately positioned on the teeth to provide a varied cutting path of the saw.
One problem addressed by known saw blade designs is that of vibration which occurs due to harmonic vibration in the moving blade. In U.S. Pat. No. 4,270,429, to Brown, this problem is presented and discussed. In the Brown patent, a saw blade is provided having an odd number of segments each including a number of randomly spaced cutting teeth. By this construction, the goal of reducing such vibrations during a cutting operation is sought to be achieved.
Another blade design attempting to reduce the amount of vibration occurring during a sawing operation is disclosed in U.S. Pat. No. 4,311,075, issued to Sundstrom. In the Sundstrom patent, a circular saw blade is divided into a number of tooth groups in which the pitch of successive cutting teeth varies. All of the groups are provided with the same varied spacing arrangement and all of the teeth have a constant radial depth regardless of the spacing therebetween.
Because reduced noise and vibration and increased cutting speed are objects which are continuously sought, it is desirable to provide further improvements in the construction of circular saw blades to achieve these objects. In addition, it is desired to provide a saw blade capable of operating at least as quickly and quietly as known saw blades, which also has a long life expectancy so as to increase the value thereof.