Patent GB-150898-A (GB)
Title: Improvements in or relating to drill grinders
IPC: B24B3/24
Filed: 1919-08-21
Abstract: 150,898. Hinz, J. C. Aug. 21, 1919. Twist drills, sharpening.-A machine for grinding and sharpening twist &c. drills comprises means whereby the drill support may be oscillated in a vertical plane relative to the grinding-wheel and means for imparting an oscillatory rotation to the drill during such movement in the vertical plane. The machine as illustrated is adapted for grinding right-handed and left-handed drills, the construction of the support for each type of drill being the same, and comprises grinding-wheels 5 mounted in bearings 7 on a bed-plate 8 on which are formed transverse flanges 12. In the flanges is mounted an adjustable slide 13 carrying in dovetail guides thereon, extending at right-angles to the slide, a base 20 adjustable by means of a screw 25. The plate carries a turret 22 adjustable about a bolt 23 and having a pivot 29 thereon adapted to carry the vertical end portion 31 of a rail 30. The rail is of dovetail section and has thereon a slidable drill carriage a2 and a bar 35 adapted to be secured in adjusted position on the rail and carrying in one end a screw 36 engaging a lug 37 on the carriage whereby this may be adjusted to and from the grinding-wheel; after adjustment, the carriage may be locked to the rail by a screw 33. In the carriage is a rotatable sleeve 39 and within this sleeve is a drill-holder 40 adapted to be held frictionally for rotation with the sleeve 39 and also capable of independent manually-operated rotation. On the sleeve 39 is formed a large interrupted gear 44, and on the holder 40 is mounted, between a flange 45 and a knurled collar 47 thereon, a sleeve 48 adapted to be locked thereto by a screw 55 and having an extension forming a socket 50 in which is a spring-pressed pin 52 adapted to engage in holes in the gear 44 spaced to index the drill to bring the various cutting- edges thereof into position for grinding. On the end of the rail 30 nearest the grinding-wheel is formed an inclined guide 57 adapted to receive a drill rest 59 having a V-shaped upper end 58 and lifted by a spring 60. On one side of the upper end of the turret is an arcuate flange 61 having thereon a gear segment 62 in engagement with a pinion 64 fixed on the end of a shaft 65 carried by the rail and extending parallel thereto and slidably keyed to a pinion 67 in gear with the gear 44. The oscillatory movement of the rail about the pivot 29 is limited by a stud on the part 31 of the rail which projects into an arcuate recess in the turret head, and the rail &c. is counterbalanced by a weight 71. The turret is set to give the correct angle to the drill point by means of a stop pin 82 thereon adapted to be brought into engagement with the end of a bar 77 mounted on the plate 20 and adjustable thereon relatively to a scale 81 on the turret. For positioning the lips of the drill, a gauge is provided comprising an arm 83 pivotally mounted on the rail and having a plate 85 thereon with a finger 86; the arm is normally held in the inoperative position by a spring 87 and may be moved by hand to bring the finger 86 into line with the drill centre, when, by adjustment of the screw 36, the drill point is brought into contact with the finger. A wheel guard 89 is provided, open at one side and movable with the slide 13 as this is adjusted to compensate for wear of the grinding- wheel; by adjustment of the plate 20 on the slide, undue wear of one part of the wheel is prevented. In operation, the rail 30 is moved up and down the engagement of the gear 62, 64 and 67, 44 during the movement producing an oscillatory rotation of the drill. A modification is also described, the rail being of tubular form and the drill carriage having a split sleeve, adapted to be clamped to the rail after adjustment by means of a screw extending axially of the tubular rail; a modified form of drill-holder is also described. Separate machines may be employed for grinding right and left handed drills.