Patent GB-1096570-A (GB)
Title: Improvements in or relating to machines for grinding tools with a helical cutting edge
IPC: B24B3/02
Filed: 1966-05-27
Abstract: 1,096,570. Grinding. R. HABIB. May 27, 1966 [May 31, 1965], No. 23869/66. Heading B3D. [Also in Division G3] A machine for grinding a helical cutter comprises a headstock 6 and tailstock 7, which are adapted to receive a tool to be ground and are mounted on a table 2, reciprocable relative to a wheel-head 3, a device for permitting the relative position of the wheel and cutter to be varied during grinding, a device for angularly driving the spindle to the headstock during movement of the table comprising a rectilinear cam 21 inclined with respect to the spindle at an angle corresponding to the helix of the cutter and a feeler in contact with the cam and controlling a servo-motor for angularly rotating the spindle, a first-slider 33, Fig. 8, movable perpendicularly to the axis of the spindle, a traversing screw 32 engaging the slider, a second slider 22 kinematically connected to the screw and carrying the cam 21, means for displacing the first slider by a determined quantity in one direction when the table reaches one of its end positions and in the opposite direction when the table reaches its other end position, and means for rotating the screw to displace the second slider in a manner corresponding to the variation desired for the relative positions of the wheel and tool. The table is reciprocated on a frame 1 relative to the wheelhead 3 which is mounted on a slide 5 movable perpendicularly to the table 2. The headstock 6 has a spindle 6a, Fig. 3, rotatable in bearing 6b, 6c and in a bearing 6d in a sleeve 8 formed with a gear 8a. A second gear 10 is rotatable on the spindle and both gears engage planet gears 11 on a carrier 12 rotatable on the spindle. Two gears 13, 14 are rotatable on the sleeve and can be selectively connected to the sleeve by a gripping ring 15 the gears being engaged by racks 16, 17 movable by the cylinder 18a of the servo-motor 18. The servo-motor has a fixed piston on which the cylinder 18a is slidable under the control of differential pressure across the piston controlled by the movement of valves actuated by one end of the pivoted feeler, the other end of which has a roller engaging the cam 21. To compensate for wear and the error induced by the feeler upon reversal of the movement of the table, a piston is reciprocable in a bore in one direction or the other according to the direction of the table movement by a distance determined by a micrometer screw and is connected by a rod and leg to one end of a lever 35, the other end of which is connected to the first slider 33, Fig. 8, movable in a bore 23a in a casing 23 carried by the machine. The slider 33 is engaged by the screw 32 in a housing 31 mounted on the second slider 22 carrying the cam 21 for adjustment about a pin 21b according to the helix of the cutter. The screw 32 can be rotated by a handle 32a or by rotation of one or other of a pair of ratchet wheels 38, 39 by a respective pawl 40, 43, Fig. 7. The pawls are mounted on a bar 41 pivoted on a lever 42 and a second lever 44 having a spring-pressed pin 44a is movable relative to lever 42 to engage the selected pawl with its respective wheel 38, 39 so that when lever 42 is rocked by operation of a solenoid 46 the slider 22 is moved relative to casing 23 in one direction or the other, the amount of movement being determined by a screw 47 and being effected to determine the depth of cut at each pass of the work past the grinding wheel. An index plate 29, is secured to a worm wheel 9 keyed to the sleeve 8 and is rotated by a worm driven by a vane motor in increments determined by engagement of a pivoted pawl with notches in the plate 29, each movement of the pawl operating an interrupter which, after producing a predetermined number of impulses reverses the supply to the vane motor so that the pawl firmly abuts the face of the selected notch in the plate. The rotation of the plate 29 is imparted through the gears 8a, 11, 10 to the spindle 6a after each or a number of complete to-and-fro movements of the table 2.