Patent GB-991181-A (GB)
Title: Machines for sharpening cutters
IPC: B24B3/02
Filed: 1962-01-12
Abstract: 991,181. Grinding machines. R. LIVET. Jan. 12, 1962 [Jan. 13, 1961], No. 1292/62. Heading B3D. A machine for sharpening milling cutters comprises a cup-shaped grinding-wheel 1, Figs. 1 and 2, mounted with its axis AA horizontal on a carriage which is traversable in a direction XX<SP>1</SP> inclined to such axis and to the direction OO<SP>1</SP> of traverse of the cutter-carrying table, and a tooth guide 5 defining a sharpening line on the front operative face 3 of the grinding-wheel, the generating line of such face in the horizontal plane coinciding with a point 9 on the edge of the tooth guide lying between the boundaries of the face 3 and being in the form of a straight line extending in substantial parallelism with the direction of traverse of the cutter table and the generating line of the outer face 2 of the grinding wheel in the same plane being a straight line perpendicular to the direction of traverse of the cutter table. The point 9 on the edge of the tooth guide defines the position of the sharpening line on the front operating surface of the grinding wheel and is arranged to lie on the vertical medial plane of the guide. If the selected sharpening plane is the horizontal plane passing through the axis of the grinding wheel, the surfaces 2, 3 of the latter are of frusto-conical form, as shown in Figs. 1 and 2, but, if the selected plane is shifted vertically above or below (as shown in Fig. 5) such horizontal plane, the surfaces 2, 3 are formed as hyperboloids. The inner surface 4 of the wheel is also of frustoconical or hyperboloid form. For shaping helical cutters the edge of the guide 5 is inclined at the helix angle of the cutter. The machine comprises a pedestal 21, Fig. 6, on which is mounted a horizontal slide 22, a cutter-carrying table 24 movable at right-angles to the slide 22, and a column 31 supporting a vertically-adjustable grinding head 32 in a casing 46. The grinding head comprising the grinding wheel 57, Fig. 11, spindle 45 and drive motor 41 is mounted on a carriage 35 slidable on guides in a direction at right-angles to the axis of the cutter 27 which is carried between centres on the table 24; the head is mounted on the carriage 35 by a base-plate 39 capable of being swung about a vertical axis so as to position the axis AA of the grinding wheel at the desired inclination on the carriage. The casing 46 of the head also carries the tooth guide 51 in a vertically-movable head 52 and a vertically movable wheel-dressing head 53 having diamonds for trueing the front and inner surfaces 3, 4 of the grinding wheel. The carriage 35, which is slidable by a hand-operated feed-screw 37, Fig. 11, is positioned in grinding position by an adjustable stop 47, the body of which carries a second pivoted stop 50 adapted to be swung upwardly to position the carriage for the trueing operation. The outer side face 2 of the grinding wheel is originally trued by a diamond 73, Fig. 10, carried by a hand-operated rack slidable in a slideway 66 which is mounted on a rotatable shaft 64 disposed in a mounting 62 on a baseplate 58 on the cutter table 24; the rack is operated by a hand wheel 70 and the diamond is movable axially during reciprocation by an adjustment 74. The diamond tool can be swung by the shaft 64 to either side of the mounting 62 depending upon whether the grinding wheel axis AA is to one side or the other of its central position on the carriage 35. If desired, this trueing device may be mounted on the pedestal 33, Fig. 6. The trueing head 51, Fig. 11, carries diamonds 77, 80, Fig. 13, for periodically dressing the front and inner surfaces 3, 4 of the grinding wheel when the carriage 35 has been moved to engage the then upwardly-swung stop 50 and the head 51 moved to its lower operating position. The diamond 77 is movable by a handoperated rack 78 for dressing the front surfaces of the wheel and one or other of the two diamonds 80, which are swingable through an arcuate path by the rack 78, is arranged to act upon the inner side 4 of the grinding wheel depending upon whether the grinding wheel axis AA is set to one side or the other of its central position on the carriage 35. Instead of the machine being arranged to work under manual control, the carriage 35, trueing head 53 and stop 50 may be operated hydraulically in a largely automatic cycle.