GB693690A - Improvements in or relating to grinding machines - Google Patents

Abstract

693,690. Grinding drill bits. RIP-BITS, Ltd. March 12, 1951 [March 10, 1950], No. 6121/50. Class 60. A grinding machine comprises a baseplate or tray adapted for securement to a bench or to supporting legs, the baseplate or tray carrying a prime mover operatively associated with a grinding wheel or wheels; drill bit holding and rotating means adjustably mounted upon a compound slide carried by the baseplate or tray and adapted to be manipulated for presenting a drill bit to the grinding wheel, or one of the grinding wheels, for peripheral grinding of the drill bit, and an adjustable hand rest provided adjacent the grinding wheel, or each of them, to permit of the drill bit being held by hand with its cutting face presented to the wheel periphery for grinding the cutting edges thereof. A machine for grinding the detachable drill bits of rock drills comprises a tray 10 supported by a pair of end frames 11 connected by tie rods 12. An air or electric motor 14 mounted on a raised part 13 of the tray drives a grinding wheel 15. The motor shaft drives the grinding wheel directly or through gearing; there may be a grinding wheel on both sides of the motor. The grinding wheel 15 is provided with a guard 16 secured to the tray by screws 17 and providing a support 18 for a hand rest 19; a bolt 22 passes through the support 18 and through a slot 21 in a depending lug 20 integral with the hand rest 19. The hand rest 19 permits of a drill bit 23 being presented, by hand, with its cutting edges at the faces 24 thereof to the periphery of the grinding wheel for grinding said cutting edges. When the hand rest is not required for use it can be swung down away from the wheel after slackening the bolt 22; the lug of the hand rest may abut a stop in its operative position to locate it correctly in relation to the wheel. At the other end of the tray 10 a drill bit holding and rotating means is provided for presenting the peripheral faces 25 of the bit 23 to the periphery of the grinding wheel 15. The means comprises a carrier bed 30 having a transverse slot 33 engaging an upstanding locating rib 34 on a base block 35; the carrier bed 30 is secured in desired position by bolts 37 passing through slots 36. The bed 30 carries a lower slide 32 operable by a feed screw 39 having a handwheel 40. The lower slide 32 carries an upper slide 46; pivotally mounted on the top of the upper slide 46 is a housing 47 for a drill bit holder 48, the pivot 41 for the housing being vertical. The drill bit holder 48 is journaled in the housing within a sleeve 49a and is rotatable about a horizontal axis by a handwheel 50; the drill bit holder consists of a hollow spindle 51 provided with detachable and interchangeable chucks designed to receive and hold any desired type of rock drilling bit. Movement of the upper slide 46 relative to the lower slide 32 is effected by a handlever 52 pivoted on a pillar 53 detachably secured to a lateral extension of the lower slide 32. A headed pin 55 screwthreaded into the top of the housing 47 fits in a slot in the handlever 52. When the drill bit to be held has at its rear end a screwthreaded projecting stud, a chuck 56 is used having an internally screwthreaded socketed end 57 for receiving the stud of the drill bit. When the drill bit has a tapering socket a chuck is used having a split collet or nose 58 and a draw-rod 59. The draw-rod 59 for expanding the collet or nose extends through the chuck spindle 51 and handwheel 50 for rotation therewith as well as being axially slidable therein, the extent of such slidable movement of the draw rod being determined by a milled nut 60 engaging the screwthreaded end thereof which projects beyond the handwheel 50; the latter has splined engagement 61 with the chuck spindle. The base of the housing 47 has a plurality of holes 64 and a corresponding number of holes are provided in the upper slide 46 which come into register at predetermined angles; a removable pin 65 is inserted in two registering holes. Specification 693,689 is referred to.