Preliminary Evaluation of the Relationship of Bit Wear to Cutting Distance, Forces, and Dust Using Selected Commercial and Experimental Coal- and Rock-Cutting Tools

摘要

The report describes the initial results of long-range research on bit life conducted by the Bureau of Mines. Three commercial bit designs--a round-nose radial, 60 deg conical, and 90 deg conical with tungsten carbide (WC) inserts--and five experimental bits were tested. Four of the experimental bits were radial designs using polycrystalline diamond compact (PDC) inserts. The fifth was a 90 deg conical with an oversize WC insert. Bits were worn on a high-silica sandstone typical of coal mine roofs. The bits were mounted on a 34-in-diam drum section that provided a bit speed of 565 ft/min. Cutting forces were measured on a modified vertical slotter using a three-axis force dynamometer and recorded on an FM magnetic tape recorder. Changes in cutting forces, bit weight, and airborne dust due to gradual abrasive wear and catastrophic insert failure are presented. Tabulated and graphed data, photographs of the progression of bit wear, and selected qualitative visual and auditory observations of the bits taken throughout the experiment are found in the appendixes.