Machine adjustable boring bar assembly and method

A machine adjustable boring bar assembly for use with a rotatable spindle of a machine tool having interchangeable tools, said boring bar assembly including:

• an elongated boring bar body extending along a longitudinal axis;
• a mounting end on said body adapted to be inserted coaxially into and rotated by the machine tool spindle;
• a transversely movable tool mount on the distal end of said boring bar body;
• means to mount a cutting tool on said movable tool mount;
• planetary gearing including a ring gear member rotatably journaled on said boring bar body;
• a planet carrier member and a sun gear member in said planetary gearing;
• means providing a motion transmitting connection between said tool mount and one of said planetary gearing members;
• reaction means mounted for selective rotation around a second axis parallel to the axis of said spindle for selective engagement with one of said planetary gearing members to establish relative rotation among said members of said planetary gearing and said boring bar body to effect transverse adjustment of said tool mount while said boring bar assembly is mounted in the machine tool spindle;
• both said planet carrier and ring gear members being externally accessible;
• and
• said reaction means being selectively engageable with said planet carrier and ring gear members for rotation thereof relative to said body.

The method of adjusting the cutting diameter of an adjustable boring bar assembly for use with a rotatable machine tool spindle capable of accepting interchangeable tools, the boring bar assembly having a cutting tool on a transversely movable tool mount on a boring bar body, an externally accessible sleeve being rotatable on the body with a motion transmitting connection between the rotatable sleeve and the movable tool mount, said method including the steps of:

• providing in said motion transmission connection planetary gearing with two inputs and with an output connected to move the tool mount, and one of said inputs being connected to said sleeve;
• engaging the sleeve with a rotatable reaction member mounted on the stationary part of the machine tool adjacent the spindle;
• rotating the machine tool spindle through a given angle in a selected rotational direction;
• and
• acting on said reaction member and acting on the other of said inputs to establish relative rotation between the sleeve and the boring bar body in a selected rotational direction to effect transverse adjustment of the tool mount while the boring bar assembly is mounted in the machine tool spindle and the machine tool spindle is rotated.