Automatic control system for forming fluted cutting tools

Claim 1

In a machine tool for cutting flutes in a workpiece including a base, a horizontally movable bed mounted on said base, a rotatable chuck on said bed for holding a workpiece, a motor means coupled to said chuck for rotation thereof, a cutting tool mounted on said base and being adapted to engage said workpiece for cutting flutes therein, a cam mounted to said chuck and adapted to rotate therewith, said cam having a plurality of recesses therein which correspond to the desired flutes to be cut in said workpiece, a follower mounted to said bed and engaging the recesses in said cam for causing said bed to move horizontal in a first direction and a second direction as said chuck rotates, and control means coupled to said motor means for controlling speed and direction of said motor means, said control means including: a source of alternating electrical energy; a first electrical path coupled between said source and the field winding of said motor means for energizing the magnetic field in said motor; a first rectifier means in said first electrical path for converting the alternating energy into D.C. energy for said field; a second electrical path coupled to the armature of said motor means for activating said motor means to cause rotation of said armature; a Second rectifier means in said second path for converting alternating energy to D. C. energy for said armature; a variable transformer in said second path said variable transformer including a winding thereon, said transformer including a first wiper arm and a second wiper arm spacially positioned to engage the winding of said transformer for providing output voltages at different levels on each wiper arm; switching means responsive to position of said bed; a holding pulse relay switching means connected to said switching means of the type which changes positions when energized and retains the established position, said holding pulse relay switching means including a ganged pair of two position switches, one of said two-position switches being coupled between said second rectifier means and said motor means and adapted to engage either a first terminal or a second terminal, said first terminal coupled to said first wiper arm of said transformer, said second terminal coupled to said second wiper arm of said transformer, whereby with said first terminal in engagement, said motor means is operated at a first selected speed by positioning of said first wiper arm, with said second terminal in engagement, said motor means is operated at a second selected speed by positioning of said second wiper arm, said second selected speed being normally greater than said first selected speed; and the other of said pair of two-position switches coupled to means for reversing motor direction.