Method and apparatus for indexing attachment

A method of indexing an attachment detachably mounted on a spindle head of a machine tool through an angle positioning means, comprising the steps of:

• storing a stop position angle of the attachment at an operation stop period in a memory means;
• calling back the stop position angle of the attachment from the storing means;
• and
• indexing and rotating the attachment to the called back stop position angle, wherein
• the attachment is once returned to an original position and
• the attachment is thereafter indexed and rotated to the called back stop position angle.

An apparatus for indexing an attachment detaching mounted on a spindle head of a machine tool through an angle positioning means comprising:

• an indexing rotation angle indication means for indicating an objective indexing position angle of the attachment;
• a position angle detecting means for detecting the present position angle of the attachment;
• an angle comparing means for comparing the objective indexing position angle with the present position angle;
• an indexing rotation direction determining means for determining the indexing rotation direction of the attachment in accordance with the compared result;
• an indexing rotation angle calculating means for calculating the indexing rotation angle of the attachment in accordance with the compared result and the determined indexing rotation direction;
• an indexing rotation means for indexing and rotating the attachment in accordance with the result of the rotation direction determination from the rotation direction determining means and the indexing rotation angle from the indexing rotation angle calculating means;
• a rotation direction comparing means for comparing the indexing rotation direction with a rotation direction of a driving system performed just before as to whether or not the indexing direction is the same as the rotation direction of the driving system;
• and
• a rotation error correction means for correcting a rotation angle error of the indexing rotation angle in accordance with the compared result of the rotation direction comparison means.

An apparatus for indexing an attachment detachably mounted on a spindle head of a machine tool through an angle position determining means, comprising:

• a memory means for storing a stop position angle of the attachment at an operation stop instant;
• an indexing rotation means for calling back the stop position angle of the attachment from the memory means;
• indexing and rotating the attachment to the called back stop position angle of the attachment;
• an original position returning means for returning the attachment to an original position;
• and
• a re-indexing means for indexing and rotating the attachment to the called back stop position angle of the attachment after the returning to the original position.