Patent GB-684737-A (GB)
Title: Improvements in drill grinding machines
IPC: B24B3/24
Filed: 1951-03-30
Abstract: 684,737. Grinding drills. GANAHL, A., and HEINTZ, J..March 30, 1951 [March 30, 1950], No. 7473/51. Class 60. A drill grinding machine includes a grinding wheel and a holder for the drill to be ground, the said holder, in order to permit setting to a desired relief grinding, being supported in a rocker which is pivotable about a horizontal axis and is fixable in desired position, this rocker in turn being supported on a table which can be rotated about a vertical axis and fixed in desired position for setting the tip angle, the arrangement being such that the working surface of the grinding wheel as well as the tip of the drill to be ground coincide with the point of intersection of the horizontal swivelling axis of the rocker and the vertical axis of the table. A grinding wheel 12 is mounted directly on the shaft of a motor 9 carried by a support 7 mounted on a shaft 2 supported by the machine base 1; the support 7 is centralised by springs 8, 8 secured to it and to the base, and has a handle 14 by means of which it can be oscillated. The support 7 is positioned axially of the shaft 2 by two set rings 3, 6; the shaft 2 is movable axially by a knob 15 having a stem 40 passing through a bush 16 in the base 1 and threaded into the end of the shaft 2. A grub screw 4 screwed into the set ring 3 and into the shaft 2 works in a slot 5 in the base 1, permitting axial movement of the shaft 2 while preventing rotation thereof; a spring 30 takes up backlash. A table 31 is adjustable about a vertical spindle 37, a scale 38 being provided, and is secured in adjusted position by a clamp 39. A rocker 32 is adjustable about a horizontal spindle 33 carried by a wall 36 of the table 31; the rocker 32 is secured in adjusted position by a clamping screw 34 passing through an arcuate slot 35 in the wall 36. A clamping head 25 is rigidly connected to a hollow spindle 27 pivotally supported in the rocker 32 and carrying a lever 28 at its free end; the clamping head 25 rotatably supports a bush 60 which can be secured in adjusted position by a set screw 64 screwed into the spindle 27. The drill holder comprises a sleeve 21 provided with slots 41 containing strips 45 and with an axial bore 42 containing two cylindrical resilient inserts 22. A bush 24 has an inclined surface 43 co-operating with oblique surfaces on one end of the strips 45; the strips 45 have at the other end oblique surfaces co-operating with an inclined surface 46 on a clamping head 47 fixed on the sleeve 21. The screw 23 carried by the sleeve 21 moves the-bush axially, thus displacing the strips 45 inwardly to compress the inserts 22 so as to grip the drill. The screw 23 is bored axially so that the drill can be passed through it. The sleeve 21 is inserted in the bush 60 and rotationally positioned therein by pins 26 in the bush 60 acted on by a spring 73 and engaging recesses 21a in the sleeve 21; this permits indexing through 180 degrees. For trueing the grinding wheel 12, a holder carrying a diamond is inserted into the clamping head 25 in place of the sleeve 21. Modified forms of holder are described for holding stepped drills and centre drills. To ensure that the drill projects a definite distance beyond its holder, a gauge 80 is used having a bore 81 to receive the tip of the drill, the' drill being pushed back in the holder until the gauge comes up against the holder. A drift 82 on the gauge 80 is used for pushing the drill out of'the holder. A magnifying lens 29 for observing the tip of the drill is carried by an arm 62 pivoted at 40a on the rocker 32.