GB836128A - Improved machine for drilling very fine holes - Google Patents

Abstract

836,128. Drilling-machines. FERNSEH G.m.b.H. Oct. 19, 1956 [Oct. 29, 1955], No. 31866/56. Class 83 (3). A machine for drilling fine-holes comprises a drill 1 retained in bearings 5 and supported only by the force exerted by a driving belt 7 engaging a pulley 4 on the drill and located between the bearings, and means 10, 13, 18 for alternately thrusting the drill against the work and removing the thrust to allow the drill to be withdrawn by the axial component of the force exerted by the belt. Before drilling, a variable speed D.C. electric motor 9 for driving the endless rubber belt 7 is adjusted vertically by a handle 37, to position the pulley between the V-shaped white-metal, agate or synthetic jewel bearings 5 in a block 6. The work on a table 23, is brought up to the drill by a control 31 operating a lever which carries a thrustbearing for the table. A lever 10, pivoted at 11 and loaded by weights 12, bears on the drill to effect the feed and is raised, to enable the belt to raise the drill and clear swarf, by a lever-operated push-rod 14a operated by a cam 18 rotated by a knob 32, or by cams or eccentrics 13, 20 driven at a variable-speed by an electric motor 15 driving through gearing 15a, the lever 14 being urged towards the cams by a spring 22. The angular relationship between the eccentrics 13, 20, and thus the relationship between the drilling periods and pauses between them, may be varied by a knob 21. A screw 16 in the lever 10 cooperates with a feed-stop 17, and a contact 21a is closed, at the end of the feed-stroke, by the lever to energize a lamp 26. A lamp 25 of a different colour is energized through a contact 19 closed by the eccentrics 13, 20 during each advance of the drill. The work is positioned with the aid of a microscope 36 rotatable about the axis of the drill, and having a graduated eye-piece. A volatile lubricant, supplied to the work through a hyperdermic needle 28 by a hand-operated pump 29, is evaporated by a lamp 24 having an optical projection system, the brightness of the lamp being controlled by a variable resistance operated by a handle 34. In a modification, the cam 13 is rotated only once during the drilling of a hole and is so formed as to raise the lever 10 a number of times before allowing it to fall slowly to a predetermined level at the end of the operation. Reference has been directed by the Comptroller to Specification 705,451.