ES363347A1 - Armored metal tools - Google Patents

Abstract

An abrasive tool, such as a band saw, file, rasp, disc and the like comprises a base metal, at least a portion of which is coated with a relatively thin layer of matrix metal fusion bonded to the base metal and alloyed therewith throughout an interlayer therebetween, the matrix metal layer being overcoated with hard high melting abrasive particles partially embedded in the matrix metal and projecting therefrom and forming a myriad of sharp cutting and abrading edges. As described, the tool comprises a band saw which is formed from a strip of heat treatable alloy steel. One edge of the strip may be punched with arcuate or elongated gullets and wire brushed and grit blasted to remove burrs. The strip is then fed from a reel 50 through a guide 51 to a unit 52 which applies a mixture of paste flux and brazing metal powder to the upper edge of the strip. The paste flux may be boride-fluoride and the brazing metal a nickel-base or cobalt-base alloy or an alloy of cobalt, chromium and tungsten. The coated strip is then fed past a vibrator 57 which feeds diamond substitute particles, such as tungsten-carbide particles over an edge 56 so as to fall on the strip. The particles consist of borides, nitrides, silicides or mixtures thereof. Thereafter the strip passes an inspection station 59, a wiper assembly 62, air blast unit 70 for removing loose particles, and a unit 73 which pulls the strip from the reel 50. From the unit 73 the strip passes through an infra-red heating unit, a tensioning unit 82, an exhaust blower 83 which prevents accumulation of a conductive atmosphere, into an induction heating coil 86 which heats the strip to 1900 to 2000 F. to fuse the brazing metal with the strip and to austenitize the alloy of the strip. The strip then passes into a housing 87 containing a chill plate, which transfers the strip into a fully martensitic structure, and then to a tempering chamber 107. Finally the strip passes through strengthening rolls 108, a drive unit 109 and under a counter 110 on to a take-up reel 112. In an alternative arrangement, the paste flux and brazing metal powder are supplied from separate vibratory feeders. The magnetic effect of the induction heating is stated as having the effect of causing the abrasive particles to project from the brazing metal. The abrasive coating may be continuous along the edge of a strip formed without gullets or may be at spaced points, the coating being applied continuously and blown-off at spaced intervals by pulsating air jets. The abrasive particles project by about 1/ 3 to 1/ 2 of their average transverse dimension from the metal matrix which has a thickness varying from about 0À002 to 0À01 inch.