Cutting – Processes
Reexamination Certificate
2001-06-26
2004-05-25
Shoap, Allan N. (Department: 3724)
Cutting
Processes
C083S835000
Reexamination Certificate
active
06739227
ABSTRACT:
FIELD OF THE INVENTION
The present invention is to an enhanced metal cutting saw blade, a method of making the saw blade and a method of using the saw blade. More particularly, the enhancement of the present invention provides a circular, steel saw blade that incorporates unique saw blade gullets and blade slots in combination with negative rake tungsten carbide tips. These enhancements allow a 4″ circular blade, rotating at speeds in excess of 10,000 rpm, to cold-cut steel of {fraction (1/32)}″ up to ⅝″ thick and provides a cold-cutting action without any lubricant, leaving the material touch-cool, with no distortion or burrs.
BACKGROUND OF THE INVENTION
Two basic types of prior art blades are used on cut-off saws: abrasive blades and diamond blades. Abrasive blades consist of hard, abrasive grains held together by a bonding material, usually a synthetic resin. Blades containing silicon carbide abrasive grains are used to cut concrete, masonry, stone and similar materials; aluminum oxide abrasives are incorporated into blades used to cut metal.
Diamond blades have diamond-impregnated segments welded around the perimeter of the blade core. Choosing a diamond blade is difficult because there's no reliable way to measure quality without actually using one. The diamond content of the segments is important, but it doesn't tell the whole story. The rate at which the metal matrix wears away to expose new diamonds also affects performance and blade life. The height of the diamond segments also is misleading because some blades have bigger non-diamond-bearing bases than others.
There is also a big difference in the cost and performance of abrasive and diamond blades. A 12-inch-diameter abrasive blade costs from $7 to $17, and a 14-inch-diameter blade costs $10 to $23. On the other hand, 12-inch-diameter diamond blades cost from $200 to $550, and 14-inch-diameter blades cost from $300 to $650. Manufacturers stress that paying the higher up-front cost for a diamond blade will ultimately result in a lower cost per cut. When extensive cut-off sawing is planned, investing in diamond blades is generally thought to be worth the expense. But many contractors opt for abrasive blades simply because if they are lost or stolen, the replacement costs are much lower.
Abrasive blades can only be operated when dry. Water cannot be used to cool the blade or to suppress dust. Dry-cutting diamond blades can be used either dry or wet, but a wet-cutting diamond blade can never be used without water. Using wet blades without water, even for a few seconds, generates excessive heat, resulting in blade damage and creating a safety hazard. As these blades are not made of metal, they are generally not resharpenable.
High speed steel blades have been used for cutting non-ferrous metals, and certain steel blades without carbide tips have been used to cut steel. However, these blades are very noisy, throw hot metal in the form of sparks, and leave large burrs.
A characteristic of all of these blades is that they are noisy, generate heat, and produce burrs when cutting metal, which must then be removed by additional finishing techniques. A resharpenable, quieter, cold-cutting blade which produces no burrs would therefore solve many problems in the prior art.
BRIEF SUMMARY OF THE INVENTION
The invention consists of a rotating steel saw blade for rotating at speeds in excess of 10,000 r.p.m. to cut steel of {fraction (1/32)}″ to ⅝″ thick without producing burrs. The blade has a 4″ diameter with a central mounting hole and ~20 teeth, such that the periphery of the 4″ blade travels at a speed in excess of 174.5 ft./sec. The blade has four arc-shaped, radial cooling slots that also reduce noise and vibration. The teeth have tungsten tips with negative/clearance rakes as shown on the attached drawing. A particularly unique feature is the gullets between the teeth, which have an angled leading portion (i.e., 35-40 degrees from radial) leading to a radius-portion of the gullet. This gullet design allows the blade to effectively clear the cut portions of metal. This combination of features allows a cold-cutting action without any lubricant, leaving the material touch cool with no distortion or burrs.
It is an object of the invention to provide a blade for cut-off saws that removes only {fraction (1/16)}″ of material.
It is a further object of the invention to provide a blade for cut-off saws that can cut steels from {fraction (1/32)}″ to ⅝″ thick.
It is a further object of the invention to provide a blade for cut-off saws that allows a cold-cutting action without any lubricant, leaving the material touch cool with no distortion or burrs.
It is a further object of the invention to provide a blade for cut-off saws that clears waste material by using forwardly-raked gullets between cutting teeth.
It is a further object of the invention to provide a blade for cut-off saws that is cooler, quieter, and has reduced vibration due to the inclusion of arced slots on the blade body.
It is another object of the invention to provide a blade for cut-off saws that is resharpenable and has high wear-resistance characteristics.
It is another object of the invention to provide a blade for cut-off saws that employs carbide inserted cutting teeth electronically welded with a shock absorbing medium to a high nickel high chrome heat stabilized base material, heat treated to 44 RHC.
It is yet another object of the invention to provide a blade for cut-off saws that rotates at speeds in excess of 10,000 r.p.m. to cut steel with negatively-raked tungsten carbide teeth.
It is yet another object of the invention to provide a retractable guard for the saw-blade of the present invention when in use.
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Hamilton Isaac
Roberts Abokhair & Mardula LLC
Shoap Allan N.
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