Machine and method for flexible line boring

A line boring apparatus comprising:

• a support frame;
• a spindle supported on the support frame for three-dimensional translational motion relative to the support frame, the spindle configured to releasably engage and rotate a boring bar on a rotational spindle axis;
• a tool cradle supported adjacent the spindle and configured to support boring bars in respective ready positions for selective engagement by the spindle and to receive boring bars deposited by the spindle;
• an axes drive connected between the spindle and the support frame and configured to move the spindle translationally relative to the support frame;
• a controller operatively connected to the axes drive and configured to operate the axes drive to move the spindle relative to the support frame;
• and
• a tool support disposed along the spindle axis and supported on the support frame for two-dimensional translational motion with the spindle relative to the support frame, the spindle being axially movable along the spindle axis relative to the tool support, the tool support configured to support a rotating boring bar as the bar is advanced axially through the tool support to machine a long interrupted line bore in a workpiece disposed axially opposite the tool support from the spindle, without additional tool supports.

A method for boring a long interrupted line bore using a line boring apparatus comprising a spindle supported on a support frame, a tool cradle supported adjacent the spindle, an axes drive connected between the spindle and the support frame, and a tool support disposed along a rotational spindle axis and supported on the support frame;

• the method including the steps of:
• providing a workpiece having a first long interrupted line bore in a position adjacent the support frame, the workpiece being disposed on a side of the tool support axially opposite the spindle;
• providing a first boring bar on the tool cradle, the first boring bar configured to bore the first long interrupted line bore in the workpiece;
• retrieving the first boring bar from the tool cradle by moving the spindle and tool support translationally relative to the support frame then actuating the spindle to engage and grasp the first boring bar;
• actuating the axes drive to move the spindle, the first boring bar and the tool support translationally relative to the support frame to a position where the spindle axis is coaxially aligned with the first long interrupted line bore of the workpiece;
• moving the first boring bar to a position supported in the tool support by actuating the axes drive to advance the spindle along the spindle axis relative to the tool support;
• and
• boring the first long interrupted line bore in the workpiece by rotating the first boring bar on the spindle axis and continuing to advance the first boring bar along the spindle axis, through the tool support and into the first long interrupted line bore of the workpiece.

A method for boring a long interrupted line bore using a line boring apparatus comprising a spindle supported on a support frame, a tool cradle supported adjacent the spindle, an axes drive operatively connected between the spindle and the support frame, the axes drive including a Y axis drive configured to move the spindle vertically relative to the support frame and including two independently controllable spaced-apart drive members connected between the spindle and the support frame, and a tool support disposed along a rotational spindle axis and supported on the support frame;

• the method including the steps of:
• providing a workpiece having a first long interrupted line bore in a position adjacent the support frame, the workpiece being disposed on a side of the tool support axially opposite the spindle;
• providing a first boring bar on the tool cradle, the first boring bar configured to bore the first long interrupted line bore in the workpiece;
• retrieving the first boring bar from the tool cradle by moving the spindle and tool support translationally relative to the support frame, then actuating the spindle to engage and grasp the first boring bar;
• actuating the axes drive to move the spindle, the first boring bar and the tool support translationally relative to the support frame to a position where the spindle axis is coaxially aligned with the first long interrupted line bore of the workpiece;
• moving the first boring bar to a position supported in the tool support by actuating the axes drive to advance the spindle along the spindle axis relative to the tool support;
• boring the first long interrupted line bore in the workpiece by rotating the first boring bar on the spindle axis and continuing to advance the first boring bar along the spindle axis, through the tool support and into the first long interrupted line bore of the workpiece;
• and
• during the boring step, tilting the spindle about a horizontal droop axis disposed perpendicular to the Z axis by differentially controlling the two independently controllable spaced-apart drive members of the Y axis drive to compensate for increasing boring bar droop as the boring bar protrudes further from the tool support during boring.