Image Number 4 for United States Patent #5512005.
The present invention relates to process and apparatus for automatically engraving stone memorial markers comprised of granite or marble. The markers have their polished facing surfaces covered with a cut-out blast-resistant stencil having prescribed lettering, numerals, decorative patterns and the like. The markers are conveyed through a sand blast chamber at a uniform rate and plural direct-air-feed nozzles are moved uniformly transversely thereover to effect precisely uniform engraving of the facing surfaces. The engraving is more precisely defined to a prescribed uniform depth with finer detail than heretofore possible by manual or other automated single-nozzle methods. The plural nozzles are essentially continuously fed with pressurized air and blast cutting media to obtain faster and more accurate engraving.