Contour machining head

A machining head for use in a machine having a vertical displacement motor and a rotational drive motor for cutting an opening having a predetermined profile, the machining head comprising:

• an arbor having a proximal end and a distal end,
• a motor linked to the proximal end of the arbor for axially feeding and retracting the arbor along an axial line;
• a transmission linkage for transmitting rotational force from the rotational drive motor to the arbor for rotating the arbor around a rotational axis;
• a spindle concentrically disposed around and linked to the arbor so that the spindle rotates around the rotational axis;
• a housing attached to a distal end of the spindle;
• a carriage guide disposed at a lower portion of the housing;
• a carriage slidably retained within the carriage guide;
• a single point cutting bit extending from a lower portion of the carriage;
• a carriage feed assembly disposed within the housing, the carriage feed assembly comprising a first cantilever having a first arm pivotably linked to the distal end of the arbor and a second arm pivotably linked to the carriage, the first cantilever pivoting on a cantilever axis attached within the housing, wherein axial feed or retraction of the arbor causes the carriage to move within the carriage guide;
• a counterweight assembly disposed within the housing comprising a second cantilever having a first arm pivotably linked to the distal end of the arbor and a second arm pivotably linked to at least one counterweight;
• at least one counterweight guide disposed within the housing for slidably retaining the at least one counterweight, wherein axial feed or retraction of the arbor causes the at least one counterweight to move within the at least one counterweight guide;
• wherein movement of the carriage within the carriage guide is counterbalanced by movement of the at least one counterweight within the counterweight guide so that rotation of the housing around the rotational axis is balanced.

A method for machining an opening to form a predetermined profile in a work piece, the method comprising:

• linking a spindle and an arbor concentrically disposed within the spindle to a rotational drive motor;
• linking the arbor to a vertical displacement motor;
• attaching a machining head to the spindle and the arbor, the machining head comprising a housing, a carriage feed assembly with a single point cutting bit attached thereto, the carriage feed assembly being radially slidable on a lower portion of the housing, and a counterweight assembly, the carriage feed assembly and counterweight assembly being pivotably linked to the arbor;
• centering a machining head at a location on the work piece to be machined,
• activating the vertical displacement motor to vertically displace the arbor, wherein, through the pivotable link, the carriage feed assembly is moved relative to an axis of rotation to position the cutting tip at a starting point on the work piece, and the counterweight assembly is moved to counterbalance radial movement of the carriage feed assembly;
• before or after activating the vertical displacement motor, activating the rotational drive motor to rotate the spindle and the machining head so that the cutting tip removes material from the work piece;
• and
• further activating the vertical displacement motor to move the carriage feed assembly as the cutting tip removes material from the work piece to create a predetermined profile, wherein movement of the carriage feed assembly is counterbalanced by simultaneous movement of the counterweight assembly.