Effects of bit geometry in multiple bit-rock interaction

The impact of bit-coal/rock interaction during the cutting process in underground mines is great concern to the mining community of the world. Rock/coal cutting bears directly on rock/coal dust generation that causes black lung/silicosis in miners. On the other hand, rock cutting generates radiance of sparks that has potential to cause face ignition. Bit wear affects productivity, safety and economy. Hundreds of face ignitions and millions of dollars in productivity and compensation for respirable rock/coal dust related diseases are attributed to the cutting action of continuous miners/shearers. These undesirable impacts could be minimized by proper selection of bit types, bit design, cutting parameters of the cutting head, and amount of water and position of water jets. This thesis evaluates the effects of bit geometry in multiple bits---rock interaction, utilizing an automated rotary coal cutting simulator (ARCCS) and synthetic rock. Five types of bit/cutting tool with different cone and tip geometry were tested against the synthetic rock of 16&inches; x 14&inches; x 4&inches; dimension. The rotation of the cutting drum was kept at 100 rpm and the cutting drum was advanced at 0.14 in/sec of advance. Cutting force, penetration force, rate of advance and respirable dust were measured during the cutting process. Specific energy and specific dust were also calculated for each experiment