GB2319210A

GB2319210A - Circular saw blades

Info

Publication number: GB2319210A
Application number: GB9623891A
Authority: GB
Inventors: Geoff Turner; Steve Harris
Original assignee: Black and Decker Inc
Current assignee: Black and Decker Inc
Priority date: 1996-11-18
Filing date: 1996-11-18
Publication date: 1998-05-20
Also published as: GB9623891D0

Abstract

A circular saw blade 2 includes a plurality of noise reduction slots 12. The slots are formed from a first portion 14 having relatively large width and a second portion 20 having relatively small width. The second portion 20 is formed to have a region 22 extending linearly in a direction orthogonal to the first portion 14. The slot terminates in a hole 24 and may be formed by laser cutting.

Description

Improvements in or relating to Saw Blades This invention relates to saw blades and in particular circular saw blades having means for reducing noise levels during use.

It is known to provide various forms of cut-out in a saw blade in order to reduce noise levels during use. These take various forms and one type is shown, for example, in European Patent No. 0 155 314.

It is an object of this invention to provide a saw blade having an alternative and improved form of noise reduction slot and to this end the invention consists in a circular saw blade having one or more noise reduction cut-outs or slots extending radially inwardly from the circumference characterised in that a radially extending portion extends from the circumference which has a first width and connected to the radially inward end thereof is a second grooved portion having a second narrower width, the second portion including a linear run extending substantially perpendicular to the radial first portion and spaced therefrom.

In a preferred embodiment the second portion is a segment of an extended oval and its free end may terminate in a circular or other shaped cut-out.

In one embodiment one or more of these slots are arranged to extend inwardly from the roots of slotted inter-tooth gaps.

In order that the invention may be more readily understood an exemplary embodiment thereof will be described with reference to the accompanying drawings in which Figure 1 is a plan view of a circular saw blade according to the invention, and; Figure 2 is an enlarged view of a section of the circumference showing a sample noise reduction slot.

Referring firstly to figure 1 it can be seen that a circular saw blade, shown generally as 2, comprises a metallic disc formed with a central hole 4 for mounting the blade 2 on a drive spindle. The periphery of the blade 2 is formed so as to define a plurality of teeth 6. Each tooth 6 carries a tip 8 formed preferably of tungsten carbide as this has been found to exhibit good cutting properties. It will be noticed that between each successive tooth, there is an inter-tooth gap 10.

Referring now also to figure 2, one noise reduction slot 12 (or cut-out) in accordance with the present invention is shown. The entire slot is formed by a high-power laser beam cutting through the metallic material of the blade 2. Such techniques are common to the art and so will not be described herein.

It can be seen that the slot 12 is formed in the inter-tooth gap 10. Although this is not necessary, it is advantageous because this is the position on the blade 2 where a recess on the periphery already exists. The slot 12 commences with a first radial portion, in this example a relatively wide cut 14 formed radially inwardly of the circumference 16 of the blade 2. At a point 18 the slot 12 is formed relatively narrowly as compared with the cut 14. From this point 18 the slot is formed as a second grooved portion, here as a cut 20 which has at least a portion, in this example a run, 22, extending linearly substantially perpendicular to the radially formed cut 14. In the example shown here, the cut 20 is formed as a part-oval shape.

It will be seen that the cut 20 is radially spaced from the relatively wide cut 14. Furthermore, it can be seen from the example shown that it is preferable for the cut 20 to terminate in a circular cut-out 24. The purpose of the cut-out 24 is to cause any stresses or strains in the slot 12 to travel back along the slot where their energy may dissipate. Without such a cut-out 24, these stresses or strains may cause a crack to form at the end 26 of the slot 12. It will be appreciated that shapes other than circular cut-outs 24 may be employed, for example ovals.

Although in the example shown, the slot 12 has been formed in the inter-tooth gap 10, the invention will work if the slot is formed at some other location along the circumferential periphery of the blade 2. The slots 12 could, for example, be formed through the tip 8.

It will be understood that, although in the above example, an oval-shaped cut 22 has been shown, other shapes may be suitable.

The requirement that at least a portion of such a cut 22 be linear and extend substantially perpendicularly to the cut 14 is, however, essential.

It has been found that a circular saw blade embodying the present invention exhibits the characteristics of quieter running noise as compared with hitherto known designs.

Claims

1. A circular saw blade having one or more noise reduction cut-outs or slots extending radially inwardly from the circumference characterised in that a radially extending portion extends from the circumference which has a first width and connected to the radially inward end thereof is a second grooved portion having a second narrower width, the second portion including a linear run extending substantially perpendicular to the radial first portion and spaced therefrom.

2. A circular saw blade according to claim 1 wherein the second portion is a segment of an extended oval.

3. A circular saw blade according to either claim 1 or claim 2 wherein the free end of the second portion terminate in a circular, or other shaped, cut-out.

4. A circular saw blade according to any one of the preceding claims wherein the saw blade comprises a plurality of teeth formed around the circumferential periphery thereof and between each successive tooth is an inter-tooth gap, and wherein the noise reduction slots are arranged to extend inwardly from the radially inward end of said inter-tooth gaps.

5. A circular saw blade according to any one of the preceding claims, the saw blade being formed by laser cutting.

6. A circular saw blade as substantially herein before described and with reference to the accompanying drawings.