Abrading – Rigid tool
Reexamination Certificate
1996-12-23
2001-02-20
Scherbel, David A. (Department: 3723)
Abrading
Rigid tool
C451S535000, C451S536000, C057S293000
Reexamination Certificate
active
06190246
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to material used for or to provide for “sanding” surfaces, cutting, grinding, filing, shaping, deburring, deflashing, trimming or sawing articles and more particularly to tungsten carbide brazed perforated sheet steel and wire cloth or mesh for use on or as tools to achieve these varied operations. The word “sanding” herein is used generally to indicate the action of removing or the removal of material whether by sanding, cutting, grinding, filing, shaping, deburring, deflashing, trimming or sawing.
BACKGROUND OF THE INVENTION
The manufacture of sanding and shaping tools for use by hobbyists, do-it-yourselfers and others is well known. The manufacture of such tools using tungsten carbide particles or grit has also been done, the tool using tungsten carbide particles usually being sharper, longer lasting and superior in performance to ordinary or regular sandpaper. Solid sheet steel with tungsten carbide particles welded thereto is available in grit grades generally equivalent to sandpaper. Flexible sheet steel with tungsten carbide particles adhered thereto can be cut and shaped into various hand held tools.
The advantage of such material in tools over regular sandpaper include the material being sharper and providing cleaner cutting on a far more diverse range of materials. The life of the tool is longer and the grit particles do not tear loose as they do with regular sandpaper.
Tungsten carbide grit welding to steel, having been used to coat various steel grinding and shaping tools, is a known process, particularly in the auto tire and shoe leather industries. Welding tungsten carbide grit to relatively thin (0.010 inch) solid steel sheeting has provided a sandpaper-like product that can be bent or shaped and is consistent with other tungsten carbide coated tools in that the coated surface remains “sharp” over a relatively long period of time. When painted, the gritted solid steel sheet even resembles the look of regular sandpaper.
However, a drawback of the solid sheet steel with tungsten grit adhered thereto is that it tends to clog when working on softer materials because the material removed during the use of the device tends to form a layer or thin surface between the device and the article being worked on. This layer or thin surface of removed material clogs the grit material necessitating greater pressure between the device and article to continue effective and efficient removal of material and to overcome the detrimental effect caused by the build up of the layer. This is particularly so with “sanding” devices with fine grit particles. Not only is frequent cleaning of the surface of the device required but brushing a layer of fine removed material from the surface of the article may also be required in order to regain some of the efficiency of the working action, whether sanding, filing, grinding or the like.
It would be desirable to produce a sanding-type device or product which reduces the tendency for removed material to form the layer that lessens the cutting action of the grit particles and which reduces the tendency of the grit material to clog so quickly. A device or product which enhances the efficiency of the cutting action and requires less stoppages to clean the device and the surface of the article would be advantageous.
SUMMARY OF THE INVENTION
Accordingly we discovered after some trial, that perforations in the sheet steel to which the tungsten carbide grit is welded (copper brazed) significantly reduces the clogging of the grit and the formation of the layering effect.
More particularly, the gritted, perforated sheet steel has advantages over and is superior to the gritted, unperforated sheet steel and regular sandpaper. Removed material collects in the holes, thereby greatly reducing clogging of the grit. The removed material which collects in the holes is easily cleaned by tapping/ wrapping the sanding/shaping tool on a hard surface. In some tool applications, the removed material passes through the holes. Further, when the perforated sheet steel is gritted with tungsten carbide, some of the grit attaches to the perimeters of the holes on the vertical plane as it falls through the holes, as well as on the horizontal plane. As a tool with the perforated sheet steel is used and some wearing of grit occurs, grit pieces on the perimeter or the periphery of the holes on the vertical plane are revealed, thus providing new sanding/shaping surfaces. This is particularly so when wire mesh cloth is used as the substrate for the grit material.
Accordingly, the performance and efficiency of the device is enhanced significantly due to the additional cutting facets of the grit particles that fall into the edges of the holes in the sheet steel or wire mesh during the welding process and come into play as the other facets eventually wear down.
In summary, the tools which use the perforated sheet material are much less likely to clog, are much easier to clean and they last longer than the tools which use the unperforated sheet material.
In addition, the perforations help reduce overheating when the gritted perforated steel sheets are formed into rotary devices as the perforations cause heat to be dissipated more effectively from the device. Further, we have found that when incorporated into certain rotary forms of the tools, the perforations help cool the tool due to the passage of air at high speed through the perforations. Even when the rotary form has a backing as in the case of a disc sander, the perforations tend to create more air turbulence on the face of the tool which dissipates heat more readily. In addition, when the gritted material is used on vacuum power sanders such as orbital sanders, the residue is suctioned through the perforations into the bag or vacuum. Unlike some orbital sanding tools using sandpaper with a few large holes in a single concentric circle which have to be aligned with the vacuum holes in the platen of the tool, the discs developed according to the invention provide vacuum through any number of smaller holes whichever holes communicate with the larger pattern holes of the tool. The additional perforations also help to prevent clogging and aid in cooling. The above benefits are enhanced when perforated mesh gritted with the tungsten carbide is used.
Accordingly, the invention in one aspect pertains to an article of manufacture comprising perforated steel sheet having apertures therethrough and at least one surface having tungsten carbide grit material welded thereto. Preferably, the grit material is copper braze-welded to at least one surface and permeates at least the upper peripheral edge of at least some of the apertures, but without substantially restricting the apertures.
Another aspect of the invention pertains to an article of manufacture comprising steel wire cloth having tungsten carbide grit material copper brazed to at least one surface thereof, the grit material also penetrating the interstices of the wire cloth whereby the grit material adheres also to peripheral sides of the wire of the cloth but without completely restricting all of the apertures of the cloth.
Other aspects and advantages of the invention will become evident from the detailed description of preferred embodiments of the invention as set forth herein.
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Brochure, Printed in Canada by Dura-GRIT Inc., distributed end of Oct. 1996 and disclosing certain tools, some with perforated metal plate material.
Mason Roger W.
Parrott Brian H.
Boukus, Jr. Charles P.
Nguyen George
Scherbel David A.
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