Verfahren zum elektrolytlschen Bohren

1,130,561. Electrolytic drilling tools. ROLLS-ROYCE Ltd. Sept. 3, 1965 [Sept. 4, 1964], No. 36328/64. Heading C7B. In a method of electrolytic drilling in which a tool 10 of electrically conducting material is advanced into a workpiece 12 whilst causing an electrolyte to flow through the tool and through the hole being drilled, an electrical potential is applied between tool and workpiece with the workpiece as the anode, the tool being insulated from the workpiece except at a tip portion, and the tool at or near its extreme tip has an abutment face insulated from the cathodic part of the tool, which abutment face extends laterally outwardly further than the adjacent part of the extreme tip of the tool, a force is established urging the tip of the tool towards the side wall of the hole so that the abutment face engages with said side wall. The force may be established by means of a spring 17, by use of a resilient tool which does not naturally lie in a straight line Fig. 3 (not shown) or by providing a hole through the side of the tube near its tip so that electrolyte flowing out therefrom provides a force Fig.4 (not shown). The tool may be provided near its tip with two sleeves one within the other Fig. 5 (not shown) the outer sleeve able to rotate relative to the inner sleeve, and therefore able to roll round the wall of the hole.