Patent GB-1397696-A (GB)
Title: Abrading device
IPC: B24D7/00
Filed: 1973-05-30
Abstract: 1397696 Abrasive tools L R OLIVER & CO Inc 30 May 1973 [24 July 1972] 25724/73 Heading B3D An abrading device 20, Fig. 1, comprises a base member 11, a plurality of relatively smallsized fixed protrusions 10 on the base member, abrasive grit particles means 14, Fig. 2a, supported on the outer surfaces of the protrusions for abrading contact with objects to be abraded in use of the device, the abrasive grit particle means being magnetically orientated generally to render the longest axis of each particle means in an internally directed orientation relative to the outer surface of the protrusion, and bonding material 10a for holding the grit means and the protrusions in proper relative position. In one embodiment, the protrusions are in the form of metal spheres, such as steel shot, which are bonded to the surface 12 of the body. The outermost surface of each sphere has a single grit, a single layer of abrasive grit 14, or a structure 16, Fig. 4a, of a plurality of grits bonded thereto. The bonding is effected by a brazing metal. The protrusions may be of other sintered metal or alloy and be in the form of cubes, pyramids or cylinders. The base member may be in disc or plane form and the protrusions 110, Fig. 9a, may be formed from the base member and have flat, part cylindrical or part spherical outer surfaces to which the abrasive grit particles are bonded. The particles may be wettable by the bonding material so as to be held thereby on the protrusions. The abrasive grit particles are of metal, or a material, such as tungsten carbide containing cobalt, iron or nickel so as to render them magnetizable, or are coated with a magnetizable material so that, prior to bonding, the particles can be acted upon by a magnet so as to orientate the particles with their longest axes parallel to one another and at an angle of between 45 and 90 degrees from the outer surface of the protrusions. The protrusions may be of steel, metal or ceramic, and the abrasive grit particles may be of tungsten, silicon or titanium carbide, aluminium oxide, refractory oxide, refractory boride, garnet or diamond. The protrusions may be harder than the base member and may be spaced apart so as to provide a free passage therebetween for cooling fluid, and the abrasive grit particles may be brazed together so as to have only substantially point contact with one another to provide a porous structure. The abrading device may form a circular saw blade, straight or curved blade or segment, a hole saw or core bit. In the manufacture of the abrading device, a temporary binder, such as a resin, is coated over the base member and the protrusions in the form of steel shot are held by the coating. A brazing metal or bonding material in finely powdered form is then applied to the device followed by a further layer of the temporary binder. An elongated bar magnet is engaged with the base member so that when the abrasive grit particles are applied to the binder they are orientated with their longest axes extending outwardly from the device. Additional brazing metal may then be applied and the device heated to effect brazing of the base member, protrusions and particles to one another.