Patent ID: 7021872
Filing Date: 2006-04-04
Classification: B23B,Y10T

Abstract:
1. A rock drill for cutting rock comprising an elongated helical shaft ( 2 ) having, at one end, an insertion part ( 2 ) and, at an opposite end, a tool head ( 4 ) with cutters ( 5 ) made of hard material, wherein the helical shaft ( 2 ) is at least partially coated with a colored layer ( 7 a , 7 b ) and wherein the colored layer ( 7 a , 7 b ) forms a wear indicator marking ( 9 ) running along its length inside the helical groove ( 8 ); wherein a radially smaller auxiliary helix spine ( 10 a , 10 b ) is coated with the colored layer ( 7 a , 7 b ) relative to a helix ( 6 ).