Patent GB-190107349-A (GB)
Title: Apparatus for Relieving Cutters with Straight or Spiral Teeth.
Inventor: SCHAERER OTTO
Filed: 1901-04-09
Granted: 1902-03-27
Abstract: 7349. Schaerer, O. April 9. Lathes.-An apparatus for backing-off milling- cutters is arranged as a lathe attachment, or may be made as a separate machine and provided with suitable driving-gear. When made as an attachment, a base-plate a, Fig. 1, is mounted on the lathe bed, and carries a slide b with bearings c', c<2> Fig. 3, for an axially-movable sleeve e in which is mounted a spindle f carrying the work. The spindle is rotated by a lever q from the lathe headstock, the lever being directly secured to the spindle or driving it through gearing r<0>, r r<1>, r<3>. The wheel r drives a shaft t on the slide connected by change gearing (not shown) on a quadrant u to a spindle o<1> having a cam o, Fig. 4, which engages a roller on a rack p, engaging a wheel l on a shaft k, mounted in bearings i on the base-plate. The cam is pressed against the rack by a coiled spring k<3> on the shaft k. A variable-throw eccentric m, angularly adjustable on the wheel l, engages between standards d on the slide, thus slowly moving the slide towards the cutting-tool on the slide-rest and quickly withdrawing it during each revolution of the cam o. The number of revolutions of the cam for one revolution of the cutter blank and spindle f is adjusted by the change gearing to equal the number of teeth in the cutter being backed-off. When the teeth are required to be backed-off at the sides, a sleeve h, with interchangeable segments having grooves of various pitches, is clamped on the sleeve e with the groove engaging a bowl h<2> on a stud h<1> on the slide, the sleeve being turned so that a toothed segment e<1> on its front end engages the rack p. The sleeve e thus imparts to the spindle f and blank a longitudinal reciprocation for each to andfro movement of the slide, thus backing-off one side of the teeth, an oppositely-grooved segment being used for the other side. When only the tops of the teeth are to be backed-off, the sleeve h, is disengaged from the bowl and clamped against the bearing c<1> to prevent longitudinal movement of the sleeve e, the latter being turned and held out of engagement with the rack by a pin x, Fig. 4. For backing-off worm wheel cutters &c. in which the cutting-edges are arranged spirally as shown at 1, Fig. 8, the apparatus is arranged so that the number of reciprocations of the slide b by the cam o, corresponding to the number of spiral grooves or cutting-edges on the cutter, occupy slightly less than one turn of the cutter, the deficit depending on the pitch of the spiral. This is effected by disconnecting the wheel s with which the wheel r engages from the shaft t. The wheel s and a wheel s' attached to it then run loosely on the shaft, the wheel s<1> engaging a wheel v<1> on a spindle v, which drives the shaft t through change gearing (not shown) on a quadrant z, the shaft t being driven slightly faster than the spindle v. The cam o is driven by a pawl and ratchetwheel from the spindle o<1>, so that it is idle when the mechanism is reversed to return the tool. The cam o and spring k<3> may be replaced bv a grooved face-cam. The outer end of the arbor carrying the cutter blank is supported by an adjustable spindle g<2> with interchangeable bushings g<3>, mounted in an adjustable overhanging arm g<1>. A slide g' on the arm has a bush g<5> fitting a plug in the poppet spindle to act as a steady-rest.