CATASTROPHIC FAILURE OF A RAISE BORING MACHINE DURING UNDERGROUND REAMING OPERATIONS

This paper describes the investigation of the catastrophic failure of a raise boring machine used for underground reaming operations. The re sults of the investigation indicate that failure was due to the fractu re of the 32 drive head bolts, 30 of which had failed as a result of c orrosion-induced fatigue. Metallurgical examination confirmed that the bolts had been manufactured in accordance with the SAE J429 Specifica tion. A number of recommendations have since been implemented by the m ine, who have also introduced a quality system specifically for the co ntrol of drive head bolt sets. The equipment has now operated without problems for several years. (C) 1997 Elsevier Science Ltd.