tailieunhanh - Ebook Failure analysis case studies II: Part 2

(BQ) Part 2 book "Failure analysis case studies II" has contents: Catastrophic failure of a raise boring machine, premature fracture of a composite nylon radiator, fatigue failure of the de havilland comet i, fatigue failure analysis of a leg press exercise machine, oxidation failure of radiant heater tubes, environmentally assisted cracking,. and other contents. | Fatigue Failure Analysis Case Studies I1 . Jones (Editor) 0 200 I Elsevier Science Ltd. All rights reserved IS9 CATASTROPHIC FAILURE OF A RAISE BORING MACHINE DURING UNDERGROUND REAMING OPERATIONS ALAN JAMES Metallurgical and Corrosion Services Programme, MATTEK, CSIR, Private Bag X28. Auckland Park 2006. Republic of South Africa (Received 29 August 1996) Abstract-This paper describes the investigation of the catastrophic failure of a raise boring machine used for underground reaming operations. The results of the investigation indicate that failure was due to the fracture of the 32 drive head bolts, 30 of which had failed as a result of corrosion-induced fatigue. Metallurgical examination confirmed that the bolts had been manufactured in accordance with the SAE 5429 Specification. A number of recommendations have since been implemented by the mine, who have also introduced a quality system specifically for the control of drive head bolt sets. The equipment has now operated without problems for several years. Q 1997 Elsevier Science Ltd. All rights reserved. I . INTRODUCTION The process of raise boring (or back reaming) has been in use for over 30years, and has proved to be a very successful technique in underground mining operations. Its primary use is in the production of interconnecting vertical or near vertical channels (raises) between underground levels in mines. However, this method of rock drilling can also be used for producing channels at any angle between the vertical and the horizontal [l]. This technique of underground drilling was developed to overcome some of the problems of personnel safety in the mining industry. Previously, the process of drilling and blasting was used, which required people to enter dangerous areas of mine workings. The development of raise boring techniques also gave the mining industry a new method to construct long ore passes and ventilation raises which is economical in both time and cost. Current raise boring .