Speed controlled machine tool

A tool attachable to a spindle of a machine tool comprising:

• a machining tool for machining a workpiece;
• an electric motor for driving said machining tool;
• and
• a generator for generating electric power to drive said electric motor by the rotation of said spindle;
• wherein said generator and said electric motor change the rotational speed of said machining tool from the rotational speed of said spindle by a predetermined ratio determined based on a pole number of said generator and said electric motor.

A tool attachable to a spindle of a machine tool comprising:

• a machining tool for machining a workpiece;
• an induction motor for driving said machining tool;
• and
• an alternating current generator for generating electric power to drive said induction motor by the rotation of said spindle at a frequency in accordance with the rotational speed of said spindle, said induction motor rotating at a rotational speed in accordance with said frequency.

A tool attachable to a spindle of a machine tool comprising:

• a machining tool for machining a workpiece;
• an electric motor for driving said machining tool;
• a generator for generating electric power to drive said electric motor by the rotation of said spindle;
• control means for controlling a supply of electric power generated by said generator to drive and control said machining tool;
• and
• rotation detecting means for detecting a rotational position and/or rotational speed of said electric motor;
• wherein:
• said control means controls said electric motor based on the detected rotational position and/or the detected rotational speed.

A tool attachable to a spindle of a machine tool comprising:

• a machining tool for machining a workpiece;
• an electric motor for driving said machining tool;
• a generator for generating electric power to drive said electric motor by the rotation of said spindle;
• control means for controlling a supply of electric power generated by said generator to drive and control said machining tool;
• rotation detecting means for detecting a rotational position and/or rotational speed of said electric motor;
• and
• rotation detecting means for detecting a rotational position and/or rotational speed of said spindle;
• wherein
• said control means controls said electric motor based on the detected rotational position and/or rotational speed of both of said spindle and said electric motor.

A machine tool comprising:

• a machine tool body provided with a spindle, a driving means for driving said spindle, and at least one control axis for changing a relative position between said spindle and a workpiece;
• a control apparatus for controlling said driving means and said control axis in accordance with a machining program;
• and
• a tool attachable to said spindle and provided with a machining tool for machining a workpiece, an electric motor for driving said machining tool, and a generator for generating electric power to drive said electric motor by the rotation of said spindle;
• wherein
• said tool changes the rotational speed of said machining tool from the rotational speed of said spindle by a predetermined ratio determined based on pole numbers of said generator and said electric motor.

A tool holder attachable to a spindle of a machine tool for rotatably holding a machining tool for machining a workpiece, said tool holder comprising:

• an electric motor for driving said machining tool;
• and
• a generator for generating electric power to drive said electric motor by the rotation of said spindle;
• wherein
• said generator and said electric motor change the rotational speed of said machining tool from the rotational speed of said spindle by a predetermined ratio determined based on a pole number of said generator and said electric motor.

A machine tool comprising:

• a machine tool body provided with a spindle, a driving means for driving said spindle, and at least one control axis for changing a relative position between said spindle and a workpiece;
• a control apparatus for controlling said driving means and said control axis in accordance with a machining program;
• and
• a tool attachable to said spindle and provided with a machining tool for machining a workpiece, an electric motor for driving said machining tool, and a generator for generating electric power to drive said electric motor by the rotation of said spindle;
• wherein
• said generator and said electric motor change the rotational speed of said machining tool from the rotational speed of said spindle by a predetermined ratio determined based on a pole number of said generator and said electric motor.

A rotation speed changing apparatus comprising:

• an AC generator having an input shaft connectable to a first rotatable portion and rotatable in response to a rotation of the first rotatable portion, said AC generator generating AC electric power when the input shaft is rotated;
• an AC motor having an output shaft that is rotated when the AC motor receives the AC electric power generated by the AC generator;
• and
• a case, accommodating and holding the AC generator and the AC motor, the AC generator and the AC motor being arranged in the case along a center axis and a longitudinal direction of the first rotatable portion,
• wherein a rotation speed of the output shaft of the AC motor is based on a rotation speed of the input shaft of the AC generator and a ratio, between a number of poles of the AC generator and a number of poles of the AC motor;
• further comprising a non-rotating portion, fixing the first rotatable portion and not being rotated by the rotation of the first rotatable portion,
• wherein the case comprises a rotation locking member, inserted into a hole formed in the non-rotating portion and constraining the rotation of the case, and
• wherein when the speed changing apparatus is connected to the first rotatable portion, the rotation locking member is inserted into the hole.

A rotation speed changing apparatus comprising:

• an AC generator having an input shaft connectable to a first rotatable portion and rotatable in response to a rotation of the first rotatable portion, said AC generator generating AC electric power when the input shaft is rotated;
• an AC motor having an output shaft that is rotated when the AC motor receives the AC electric power generated by the AC generator;
• and
• a case, accommodating and holding the AC generator and the AC motor, the AC generator and the AC motor being arranged in the case along a center axis and a longitudinal direction of the first rotatable portion,
• wherein a rotation speed of the output shaft of the AC motor is based on a rotation speed of the input shaft of the AC generator and a ratio, between a number of poles of the AC generator and a number of poles of the AC motor;
• wherein the AC generator comprises an AC synchronous generator, and
• the AC motor comprises an induction motor;
• the case further comprising:
• a first case member rotatably holding the first rotatable portion,
• a second case member, connected to the first case member, rotatable with the first rotatable portion and holding the generator and the motor,
• a third case member, connected to the second case member, and accommodating the output shaft of the motor, and
• a means for clamping and joining the first case member, the second case member and the third case member.

A rotation speed changing apparatus comprising:

• an AC generator having an input shaft connectable to a first rotatable portion and rotatable in response to a rotation of the first rotatable portion, said AC generator generating AC electric power when the input shaft is rotated;
• an AC motor having an output shaft that is rotated when the AC motor receives the AC electric power generated by the AC generator;
• and
• a case, accommodating and holding the AC generator and the AC motor, the AC generator and the AC motor being arranged in the case along a center axis and a longitudinal direction of the first rotatable portion,
• wherein a rotation speed of the output shaft of the AC motor is based on a rotation speed of the input shaft of the AC generator and a ratio, between a number of poles of the AC generator and a number of poles of the AC motor;
• the case further comprising:
• a first case member rotatably holding the first rotatable portion,
• a second case member, connected to the first case member, rotatable with the first rotatable portion and holding the generator and the motor,
• a third case member, connected to the second case member, and accommodating the output shaft of the motor, and
• a means for clamping and joining the first case member, the second case member and the third case member.