Machine with rotating cutting tool

A machine tool comprising:

• a headstock;
• a spindle assembly mounted for rotation about an axis upon the headstock;
• a radial slide adapted to hold a cutting tool mounted upon the spindle assembly for radial movement along an axis extending radially of the axis of rotation of the spindle assembly;
• a counterbalance structure mounted in spindle assembly to generate a variable centrifugal force in opposition to that of the radial slide for providing dynamic balance of the spindle assembly during rotation;
• a motor mounted upon the spindle assembly for rotation therewith, the motor being in driving association with the radial slide such that the speed of the motor is proportional to the radial velocity of the radial slide;
• a slip-ring assembly mounted on the headstock for supplying power to the motor;
• an incremental position transducer mounted upon the headstock and operatively connected to the motor for sensing the sum of the speed of the spindle assembly and the speed of the motor;
• and
• an incremental position transducer mounted upon the headstock and operatively connected to the spindle assembly for sensing the speed of the spindle assembly.

A machine tool comprising:

• a headstock;
• a spindle assembly mounted for rotation about an axis upon the headstock;
• a radial slide adapted to hold a cutting tool parallel to the axis of rotation of the spindle assembly mounted in the spindle assembly;
• drive screw means for radially moving the radial slide along an axis extending radially of the axis of rotation of the spindle assembly between a radially inner position in which the cutting tool is aligned with the axis of rotation of the assembly and a radially outer position in which the cutting tool is spaced from the axis of rotation of the assembly;
• counterbalance means responsive to the radial positioning of the radial slide to generate a variable centrifugal force in opposition to that of the radial slide for providing dynamic balance of the spindle assembly during spindle assembly rotation;
• a motor mounted upon the spindle assembly for rotation therewith;
• drive means to establish a driving connection between the motor and the drive screw such that the speed of the motor is proportional to the radial velocity of the radial slide;
• transducer means to sense the sum of the speed of the spindle assembly and the speed of the motor and generate a series of pulses having a frequency proportional thereto;
• transducer means to sense the speed of the spindle assembly and generate a series of pulses having a frequency proportional thereto;
• and
• means responsive to the pulses generated by the first and second mentioned transducer means to sum quantitites indicative of a commanded motor speed, the sum of the speed of the spindle assembly and the speed of the motor and the speed of the spindle assembly for producing a quantity indicative of the speed error of the motor.

A method of operating a machine tool having a machining head which is rotatable about an axis and a radial slide carrying a cutting tool mounted in the machining head for radial movement, comprising the steps of:

• moving the slide radially by rotating a drive screw in engagement therewith;
• counterbalancing the centrifugal force exerted by the radial slide on the machining head;
• sensing a parameter indicative of the combined speeds of rotation of the machining head and the drive screw;
• and
• sensing a parameter indicative of the speed of rotation of the machining head.

In a machine tool with a rotating cutting tool of the type having a headstock, a spindle mounted for rotation about an axis in the headstock and a machining head in driving connection with the spindle, the improvement comprising:

• a precision drive screw mounted for rotation in the machining head with its axis extending radially of the spindle axis;
• a beveled drive gear mounted upon the drive screw;
• a radial slide mounted upon the drive screw in threaded engagement therewith for radial movement in response to rotation of the drive screw about its axis, the radial slide being adapted to receive the cutting tool;
• a threaded shaft mounted for rotation in the machining head in driving connection with the drive screw and in parallel spaced relationship thereto, the threaded shaft having a threaded section, a portion of the threaded section extending alongside the drive gear;
• a counterbalance block mounted upon the threaded section in threaded engagement therewith and in a generally diametrically opposed position to the radial slide such that rotation of the drive screw produces opposite radial movements of the radial slide and the block whereby the block may generate a centrifugal force in opposition to that of the radial slide for providing dynamic balance during spindle rotation, the block being shaped such that it may travel upon the threaded section alongside the drive gear without interference therebetween;
• and
• a servo motor in driving connection with the drive gear for rotating the drive screw relative to the machining head.