| 摘要 |
1,107,915. Grinding; drilling. PILKING- TON BROS. Ltd., and G. PIONKE. 18 May, 1966 [3 June, 1965], No. 23767/65. Headings B3C and B3D. A tubular tool for cutting countersunk holes in glass articles comprises a countersinking element 10 clamped on to a cutting tube 2 so as to be axially adjustable thereon to maintain a predetermined distance between the grinding face 12 of the countersinking element and the cutting edge 3 of the cutting tube to take up wear of the edge. The tube may be bronze impregnated with diamond dust and is formed on the end of a bronze or steel body 1 having a thread 4 for engagement in the shaft of a drilling machine. The countersinking element consists of split collar 9 clamped by screws 13, 14 around two semi-circular shells 10 bevelled at their lower ends 12 and impregnated with diamond dust; as the end 3 of the tube wears, the collar 9 is slackened to permit adjustment of the shells. A bore 5 is formed in the body 1 for cooling liquid. Two tools may be used one above and the other below to drill a hole in a glass article, the upper tool being slightly larger in diameter than the other and slightly longer. The tools may be rotated in the same or opposite directions. In another embodiment, the grinding face is of tungsten carbide. In a further embodiment, the countersinking element is threaded at its upper end for engaging the shaft of the drilling machine, and the lower end is split and receives the cutting tube. |
