Full-Face Boring by the Undercutting Method
P. 0. SANDSTROM, Manager, Application Engineering Department, Atlas Copco Canada Ltd., Montreal, Que.
Atlas Copco is introducing a new patented method for full-face boring. This paper presents the basic principles of the boring action and discusses the present experience regarding performance and costs. The Atlas Copco "Fullfacers" are designed for hard-rock applications, although they are successfully boring in soft ground without major changes. The unique patented boring principle referred to as the 'Undercutting Method' permits these machines to bore, economically, in harder ground than machines based on the 'crushing principle'. This is mainly due to considerably lower cutting-tool costs, as the tungsten carbide tips only are in contact with one-third of the bored volume. The remaining rock is 'undercut' and peels off from a slight back pressure. The undercutting method also permits boring of noncircular headings and Atlas Copco has already manufactured two machines for rectangular drifts. This concept could revolutionize development work in mines employing trackless equipment.