Servo control method for orbital machining with cutting tool and servo control system for orbital machining

A servo control system for orbital machining comprising:

• a first control means for controlling a first servo motor for moving a feed shaft to feed a work;
• a second control means for controlling a second servo motor for moving a spindle having a cutting tool attached thereto for an orbital machining of the work;
• first compensation means for compensating for a first follow-up delay in said first control means for controlling the first servo motor, in a feed forward manner;
• second compensation means for compensating for a second follow-up delay in said second control means for controlling the second servo motor, in a feed forward manner;
• moving a spindle and the work by way of a shaft control to make a relative displacement to each other along a plane perpendicular to an axis of rotation of the spindle, such that a mutual interpolation motion is achieved between the spindle and the work;
• and
• controlling a rotation angle of the spindle quantitatively and synchronously to have a predetermined correlation to the shaft control so that, at any angular position in rotation of the spindle, a blade direction of a cutting tool is maintained in a preset direction to thereby achieve a cutting into a configuration to be defined by an interpolation locus based on the mutual interpolation motion.

A servo control method comprising the steps of:

• controlling a first servo motor for moving a feed shaft to feed a work;
• controlling a second servo motor for moving a spindle having a cutting tool attached thereto for an orbital machining of the work;
• compensating for a first follow-up delay in said controlling of the first servo motor, in a feed forward manner;
• and
• compensating for a second follow-up delay in said controlling of the second servo motor, in a feed forward manner, wherein:
• said controlling of the first servo motor includes the steps of
• providing a first command responsible for a position in feed of the feed shaft,
• subjecting the first command to a first loop having a first gain, and
• controlling the first servo motor with the first command subjected to the first loop;
• and
• said controlling the second servo motor includes the steps of
• providing a second command responsible for a position in rotation of the spindle;
• subjecting the second command to a second loop having a second gain, and
• controlling the second servo motor with the second command subjected to the second loop, wherein
• said compensating for the first follow-up delay includes the steps of:
• calculating a quantity for compensation depending on a differential of the first command and a combination of a natural frequency and an attenuation constant of vibrations in a moving direction of a moving mechanism associated with the feed shaft;
• and
• compensating the first command by said quantity.

A servo control method comprising the steps of:

• controlling a first servo motor for moving a feed shaft to feed a work;
• controlling a second servo motor for moving a spindle having a cutting tool attached thereto for an orbital machining of the work;
• compensating for a first follow-up in said controlling of the first servo motor, in a feed forward manner;
• and
• compensating for a second follow-up delay in said controlling of the second servo motor, in a feed forward manner, wherein:
• said controlling of the first servo motor includes the steps of
• providing a first command responsible for a position in feed of the feed shaft,
• subjecting the first command to a first loop having a first gain, and
• controlling the first servo motor with the first command subjected to the first loop;
• and
• said controlling the second servo motor includes the steps of
• providing a second command responsible for a position in rotation of the spindle,
• subjecting the second command to a second loop having a second gain, and
• controlling the second servo motor with the second command subjected to the second loop, wherein
• said compensation for the first follow-up delay includes the steps of:
• calculating a quantity for compensation depending on a differential of the first command and a combination of a natural frequency and an attenuation constant of torsional vibrations of the feed shaft;
• and
• compensating the first command by said quantity.

A servo control method comprising the steps of:

• controlling a first servo motor for moving a feed shaft to feed a work;
• controlling a second servo motor for moving a spindle having a cutting tool attached thereto for an orbital machining of the work;
• compensating for a first follow-up in said controlling the first servo motor, in a feed forward manner;
• and
• compensating for a second follow-up delay in said controlling of the second servo motor, in a feed forward manner, wherein:
• said controlling of the first servo motor includes the steps of
• providing a first command responsible for a position in feed of the feed shaft,
• subjecting the first command to a first loop having a first gain, and
• controlling the first servo motor with the first command subjected to the first loop;
• and
• said controlling of the second servo motor includes the steps of
• providing a second command responsible for a position in rotation of the spindle,
• subjecting the second command to a second loop having a second gain, and
• controlling the second servo motor with the second command subjected to the second loop, wherein
• said compensating for the first follow-up delay includes the steps of:
• calculating a quantity for compensation depending on a differential of the first command and a combination of a natural frequency and an attenuation constant of torsional vibrations of the feed shaft;
• and
• compensating the first command by said quantity.

A servo control system comprising:

• first control means for controlling a first servo motor for moving a feed shaft to feed a work;
• second control means for controlling a second servo motor for moving a spindle having a cutting tool attached for an orbital machining of the work;
• first compensation means for compensating for a first follow-up delay in control of the first servo motor, in a feed forward manner;
• and
• second compensation means for compensating for a second follow-up delay in control of the second servo motor, in a feed forward manner, wherein:
• said first control means includes
• means for providing a first command responsible for a position in feed of the feed shaft,
• means for subjecting the first command to a first loop having a first gain, and
• means for controlling the first servo motor with the first command subjected to the first loop;
• and
• said second control means includes
• means for providing a second command responsible for a position in rotation of the spindle,
• means for subjecting the second command to a second loop having a second gain, and
• means for controlling the second servo motor with the second command subjected to the second loop, wherein
• said first compensation means includes:
• means for calculating a quantity for compensation depending on a differential of the first command and a combination of a natural frequency and an attenuation constant of vibrations in a moving direction of a moving mechanism associated with the feed shaft;
• and
• means for compensating the first command by said quantity.

A servo control system comprising:

• first control means for controlling a first servo motor for moving a feed shaft to feed a work;
• second control means for controlling a second servo motor for moving a spindle having a cutting tool attached thereto for an orbital machining of the work;
• first compensation means for compensating for a first follow-up delay in control of the first servo motor, in a feed forward manner;
• and
• second compensation means for compensating for a second follow-up delay in control of the second servo motor, in a feed forward manner, wherein:
• said first control means includes
• means for providing a first command responsible for a position in feed of the feed shaft,
• means for subjecting the first command to a first loop having a first gain, and
• means for controlling the first servo motor with the first command subjected to the first loop;
• and
• said second control means includes
• means for providing a second command responsible for a position in rotation of the spindle,
• means for subjecting the second command to a second loop having a second gain, and
• means for controlling the second servo motor with the second command subjected to the second loop, wherein
• said first compensation means includes:
• means for calculating a quantity for compensation depending on a differential of the first command and a combination of a natural frequency and an attenuation constant of torsional vibrations of the feed shaft;
• and
• means for compensating the first command by said quantity.

A servo control system comprising:

• first control means for controlling a first servo motor for moving a feed shaft to feed a work;
• second control means for controlling a second servo motor for moving a spindle having a cutting tool attached thereto for an orbital machining of the work;
• first compensation means for compensating for a first follow-up delay in control of the first servo motor, in a feed forward manner;
• and
• second compensation means for compensating for a second follow-up delay in control of the second servo motor, in a feed forward manner, wherein:
• said first control means includes
• means for providing a first command responsible for a position in feed of the feed shaft,
• means for subjecting the first command to a first loop having a first gain, and
• means for controlling the first servo motor with the first command subjected to the first loop;
• and
• said second control means includes
• means for providing a second command responsible for a position in rotation of the spindle,
• means for subjecting the second command to a second loop having a second gain, and
• means for controlling the second servo motor with the second command subjected to the second loop, wherein
• said second compensation means includes:
• means for calculating a quantity for compensation depending on a differential of the second command and a combination of a natural frequency and an attenuation constant of torsional vibrations of the spindle;
• and
• means for compensating the second command by said quantity.