Electric heating – Metal heating – By arc
Reexamination Certificate
2000-12-15
2002-03-05
Dunn, Tom (Department: 1725)
Electric heating
Metal heating
By arc
C219S121700, C219S121680, C051S295000
Reexamination Certificate
active
06353205
ABSTRACT:
This invention relates to improvements in laser cut saw blades.
This invention relates to a tungsten carbide tipped circular saw blade, and an improved method for making the same.
The fabrication of tungsten carbide tipped circular saw blades is a time consuming and expensive process. With the advent of laser cutting equipment, a typical 7¼ inch (184 mm) saw blade can be cut out in about one minute. Because of the variety of machines which use these blades, it is often necessary to provide blades with different sized arbors, which suit the particular machines for which they are supplied. So far as circular arbors are concerned, it is usual to make the blade with the largest sized arbor typically 30 mm and then provide a series of collars to cater for other sizes.
Certain markets such as the United States require arbors that are diamond shaped and these have been particularly hard to provide to date.
To date, all circular saw bodies have been made from carbon steel which has a tendency to rust when exposed to moisture. It is seen as extremely desirable if a saw blade body could be completely made from a rust resistant material such as stainless steel. To date, it has not been possible to achieve this because substituting stainless steel for carbon steel in the conventional saw blade fabrication process results in a product that has an unsatisfactory surface finish (severely discoloured) and is not suitable for presentation to the buying public.
Clearly, it would be advantageous if a method could be found to produce a tungsten carbide tipped circular saw with a rust resistant stainless steel body. It would also be advantageous if a method could be found to provide for the different shaped arbors when manufacturing the blade so that additional items such as adaptation collars are no longer necessary.
It is believed that the present invention provides for these wishes and has further additional advantages.
The invention provides a method of manufacturing a tungsten carbide tipped circular saw blade characterised by the steps:
(a) supplying a stainless sheet steel strip or blank to a laser cutting machine;
(b) laser cutting an arbor and the periphery profile of the blade according to a predetermined computer controlled pattern;
(c) brazing the tungsten carbide saw tips to their respective locations on the periphery of the blade;
(d) electropolishing the blade to remove brazing residues and heat discolouration from the surfaces; and
(e) grinding the final cutting profile to each of the tungsten carbide tips.
Preferably a number of different sized arbors are cut by the laser at the time of manufacture said arbors each being retained by tags which hold each cut arbor portion to the main body of the saw blade. Optionally heat expansion slots/patterns may also be cut by the laser at the time of manufacture.
In a preferred embodiment, the process of step (b) is performed with the aid of nitrogen gas to provide a clean non-carbonized cut.
The invention also provides a tungsten carbide tipped circular saw blade made in accordance with the method described above.
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patent: 4488882 (1984-12-01), Dausinger et al.
patent: 4495398 (1985-01-01), Bredow et al.
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patent: 5226404 (1993-07-01), Mogi et al.
patent: 5471970 (1995-12-01), Sakarcan
patent: 6110031 (2000-08-01), Preston et al.
patent: 6273082 (2001-08-01), Tselesin
patent: 2 088 267 (1982-06-01), None
patent: 32 17 362 (1983-08-01), None
patent: WO 85/00280 (1985-01-01), None
Patent Abstracts of Japan, JP 60-135116, Jul. 18, 1985.
Click Clack Limited
Dunn Tom
Johnson Jonathan
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