Replaceable tooth for a circular saw

Abstract

A replaceable tooth for a circular saw with a base and angled cutting surfaces defining nadirs of intersection between adjacent cutting surfaces. Inserts are provided to cover facets of the angled cutting surfaces of the replaceable tooth. Plugs of a hardened material are provided immediately below each nadir of intersection to prevent erosion of the tooth base below the intersections of the inserts.

Claims

1. A replaceable tooth for a circular saw comprising: a tooth base of a first material; a plurality of substantially triangular cutting surfaces extending above said base; each substantially triangular cutting surface of said plurality of substantially triangular cutting surfaces having a facet that is angled in relation to the facets of adjacent substantially triangular cutting surfaces of said plurality of substantially triangular cutting surfaces; said adjacent substantially triangular cutting surfaces defining nadirs of intersection between said adjacent substantially triangular cutting surfaces; a plurality of inserts covering said angled facets; and, at least one plug of a second material located immediately below at least one of said nadirs of intersection, said second material being more erosion resistant than said first material.

2. The replaceable tooth of claim 1 wherein each of said nadirs of intersection has a plug of said second material immediately below.

3. The replaceable tooth of claim 2 wherein said first material is steel and wherein said second material is carbide.

4. The replaceable tooth of claim 3 wherein said carbide is tungsten carbide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) At least one mode for carrying out the invention in terms of one or more examples will be described by reference to the drawings thereof in which:

(2) FIG. 1 is plan view of a circular saw with prior art teeth before use of the teeth;

(3) FIG. 2 is a plan view of a circular saw with prior art teeth after use of the teeth and showing a groove etched by wear extending down the length of the teeth and across a portion of the saw holders for the teeth;

(4) FIG. 3 is a plan view of a portion of the saw blade shown in FIG. 1, one tooth, and a bolt for securing the tooth to the saw blade;

(5) FIG. 4 is a plan view of a portion of the saw blade shown in FIG. 2, one tooth, and a bolt for securing the tooth to the saw blade;

(6) FIG. 5 is a plan view of a circular saw blade with teeth according to the preferred embodiment of the invention;

(7) FIG. 6 is a plan view of a portion of the saw blade shown in FIG. 5, one tooth according to the preferred embodiment, and a bolt for securing the tooth to the saw blade;

(8) FIG. 7 is a perspective view of the tooth according to preferred embodiment;

(9) FIG. 8 is a side elevation of the tooth shown in FIG. 7;

(10) FIG. 9 is plan view of the tooth shown in FIG. 7;

(11) FIG. 10 is a view taken along line 10-10 of FIG. 9 and without the inserts; and,

(12) FIG. 11 is a view taken along line 11-11 of FIG. 9.

DETAILED DESCRIPTION OF AT LEAST ONE MODE FOR CARRYING OUT THE INVENTION IN TERMS OF EXAMPLE(S)

(13) FIGS. 5 and 6 show tooth 100 according to the preferred embodiment mounted on tooth holder 26 of circular saw 2. A series of tooth holders (for instance eighteen holders) normally extend around the circumference of the circular saw. FIG. 5 (and FIGS. 1 and 2) show only three tooth holders 26 of the series around the saw (i.e. the remaining tooth holders are not depicted).

(14) FIGS. 7 to 11 collectively show several views of tooth 100 in isolation.

(15) The tooth 100 includes a base 112 having angled V-shaped cutting surfaces 114 extending above the base 112 and terminating in raised tips 116. The cutting surfaces 114 are substantially triangular or frusto-pyramidal in shape having facets 130 (FIG. 10 wherein the inserts are not shown) that are angled in relation to the facets of adjacent cutting surfaces 114. The base 112 and the cutting surfaces 114 are typically made of metal such as steel.

(16) The tips 116 of the cutting surfaces 114 define apices of the outer perimeter of the tooth 100. The bottom edges 118 of each cutting surface terminate at the bottom edge of the adjacent cutting surface thereby defining nadirs of intersection 122 of the adjacent cutting surfaces.

(17) The tooth 100 typically includes a central threaded bore 124 used to secure the tooth to a tooth holder 26 with a bolt 20 (see FIGS. 6 and 7).

(18) Inserts 128, typically of carbide (for example tungsten carbide) cover the angled facets 130 of the cutting surfaces. As do the cutting surfaces 114, the inserts 128 meet by abutment at nadirs of intersection 122 about the upper surface of the tooth. The inserts 128 are of a material that is more resistant to erosion than the base 112 and cutting surfaces 114 of the tooth.

(19) Without further modification, the wear from repeated cutting of material erodes the edges of the inserts 28 that meet at the nadirs of intersection 22, such erosion eventually forming the grooves in the base 12 of the tooth as shown in FIG. 4, and ultimately damaging the underlying holders 26 in a similar manner.

(20) According to the invention, plugs 134 of hardened material, such as tungsten carbide, extends into the base 112 of the tooth, each at a point immediately below the nadir of intersection 122 between adjacent inserts 128. The plugs 134 being of a hardened material compared to the base 112 and cutting surfaces 114 are more erosion resistant and act to interrupt the progression of an etched groove by presenting a hardened obstacle to erosion. Preferably the plugs 134 are provided immediately below each nadir of intersection 122. While plugs 134 are shown as being cylindrical, it will be appreciated that other shapes are possible.

(21) Now referring to the cross-sectional view of the tooth 100 in FIG. 10, there may be gaps 135 in the metal above each of the plugs 134. When the carbide inserts 128 (shown in FIG. 7) are brazed to the tooth, the gaps 135 are filled in with carbide.

(22) In the foregoing description, a preferred means of carrying out the invention has been described. However, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.