Top-hammer drilling sees new interest in the UK

摘要

During the 1960s and 70s many UK quarries were littered with drilling tool scrap in the form of bent and broken extension rods, extracted after becoming stuck in the hole. At this time the majority of holes drilled by top hammer were between 89mm and I 15mm in diameter.The small, 38mm diameter extension rods were soon exchanged for the DTH (down-the-hole) method, using tubes, hammers and bits.