Stone working – Sawing – Rotary
Reexamination Certificate
2001-06-19
2003-07-22
Wilson, Lee D. (Department: 3724)
Stone working
Sawing
Rotary
C125S013030, C451S449000, C451S450000
Reexamination Certificate
active
06595196
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates broadly to system and apparatus for grinding or cutting masonry or stone products and typically comprise a disc-like cutting blade rotatable at high speeds. These cutters or grinders are used in rehabilitating old brick buildings to remove the mortar between the bricks commonly referred to as “tuck pointing”. When tuck pointing, workers use power grinders to dig into the mortar to a depth of an inch or less. The grinders operate at a high speeds of 12,000 rpms and create dust in the form of respirable crystalline silica. It has been observed that when workers are exposed to low concentrations of the respirable crystalline silica they develop silicosis which is a deadly lung disease. The workers wear protective masks. However, these masks have a limited effectiveness and are not a guarantee in preventing silicosis. Furthermore, in rehabilitating old buildings, the dust particles often migrate in the general vicinity and can be inhaled by persons outside the work area and present a risk of silicosis.
With the above in mind, it is an object of the present invention to provide an improvement in equipment of this type, which essentially eliminates the harmful dust formation generated, for example, in tuck pointing operations and others and essentially entrains the dust particles in the liquid coolant and creates a harmless slurry. It has been observed that the state of the art grinders or cutters operate at very high speeds and by reason of this the air flow across the face of the cutting blade is laminar which is believed to prevent dispersement of the coolant in a manner to co-mingle or entrain with all of dust particles. It has been found that smaller cutting tools having blades in the order of approximately 4-6 inches in diameter operated at comparatively low speeds in the order of 5000-7000 rpms produces turbulent air flow across the face of the blade which allows the coolant to disperse on the spinning blade and capture or entrain all of the dust particles and thereby create a harmless slurry. In other words, in the present application, the blade and coolant are configured and operate in such a manner to create a condition on the face of the blade believed to be turbulent flow which provides coolant flow paths to the face of the blade where it is directed peripherally to mix with and entrain dust particles and create a harmless slurry with the coolant.
In accordance with the present invention, the coolant is used for dust and particulate elimination and a byproduct is blade cooling. As noted, the coolant water dispersed on the spinning blade entrains the silica dust and produces a slurry which is now a harmless byproduct of the cutting process. More specifically, the point at which the water is directed onto the blade will greatly increase the efficiency and longevity of the blade by cooling it in addition to the conversion of the dust particles to a harmless slurry. In most cases, concrete cutting tools use large blades rotating at high speeds which creates the laminar air flow which causes difficulty in entraining the dust particulate formed during the cutting process and the air barrier created by laminar flow limits the cooling effect. The present invention, by providing the relatively small blade rotating at comparatively low speeds produces turbulent flow which enhances encapsulation or entraining of the dust particles and the cooling efficiency.
It has been found that the masonry cutting tools of the prior art do not operate in a manner wherein the coolant penetrates the air layer over the face of the blade and therefore there is no entrainment of dust particles in the coolant to form a harmless slurry. In accordance with the present invention, the cutting blade is operated in a predetermined manner and at a predetermined speed to create air flow conditions wherein the liquid coolant penetrates the layer of air on the cutting blades and by reason of this entrains the dust particles created during a cutting operation and converts the same to a harmless slurry.
With the foregoing in mind, it is the object of the present invention to provide a dust-free masonry cutting tool which minimizes operator health risks from silica dust and minimizing intrusion of this dust into the occupied spaces of the building where work is being performed.
BACKGROUND OF THE INVENTION
There are a number of prior art patents listed below which disclose water cooling systems for cooling the cutting blade, disclose water cooling systems for a blade of cutting apparatus for cutting concrete materials and the like. However, none of these prior art patents disclose or suggest the present invention which essentially removes the dust from the cutting process which if ingested can cause silicosis which is a disabling, nonreversible and sometimes fatal lung disease.
Hogue U.S. Pat. No. 4,570,609 discloses a water-cooling system for the saw hub and blade to maintain blade integrity and extend the life of the blade and is not designed for dust removal.
Long U.S. Pat. No. 4,870,946 and Lipanski U.S. Pat. No. 5,619,081 are directed to blade and hub cooling and debris removal to improve efficiency of the cutting action.
As Zerrer U.S. Pat. No. 5,826,478 discloses a nozzle for supplying a liquid to a rotating tool and discloses a specific arrangement facilitating attaching a water line to a V-belt cutter's protective cover.
Ward U.S. Pat. No. 4,236,356 shows a cutting apparatus having multiple blades used to cut safety grooves in concrete primarily in concrete steps.
Klingerman U.S. Pat. No. 4,484,417 is directed to blade cooling.
Bridwell U.S. Pat. No. 3,747,276 shows a method for contouring circular saws to maintain a sharp cutting edge while cutting hard but not abrasive materials.
Starr U.S. Pat. No. 159,048 discloses a protective device for cutting apparatus.
Tilghman U.S. Pat. No. Reissue 7,499 uses grains or globules of sand or metal to assist a cutting blade when cutting through a hard surfaces. The grains are fed into the saw-kerf with small streams of water.
Udert U.S. Pat. No. 5,468,176 discloses a disk-shaped tool to be used with an angle grinder. There is one variation of the disk utilizing water to reduce wear of the disk-like tool bits when the slot-like recesses are formed. When machining the slot-like recesses, a “U”-shaped structure remains between the disk-shaped tool bits. However, such parts can be removed by a suitable tool after the recess has been formed. This is a very inefficient operation that requires additional hand work to make a clean cut.
Grant U.S. Pat. No. 5,047,089 discloses a device and method for removing and cleaning a relatively softer material, such as asbestos, from a relatively harder surface, such as walls and ceilings. A cutting wheel is not involved. Instead, a plurality of knives are disposed adjacent a leading side of the housing for making longitudinal and generally continuous incisions in the asbestos-containing material layer. A liquid is sprayed onto the scraped surface to wash or remove residual asbestos-containing material from the surface. A vacuum source is connected to the housing for aspirating the sprayed liquid and the asbestos-containing material removed by cutting, scraping and washing.
Sakarcan U.S. Pat. No. 4,854,295 discloses an improved cutting blade when water is used to simply cool the blade and flush loose rock-like material, spent abrasive and the like from the cutting site.
Tanizaki U.S. Pat. No. 4,569,326 relates to a dicing apparatus for micro-electric circuit fabrication such as semiconductor integrated circuits or large scale integrated circuits in which a wafer is separated into individual small-dimensioned die. Water is sprayed to lower the temperature at the face, provide lubrication and flush the cutting debris away from the cutting area. If the debris is not cleaned away, damage can result to the wafer or die being cut.
Ogyu U.S. Pat. No. 4,406,274 discloses an invention designed to limit the sound produced from the cutting tool. The water used is to provide a means for the
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