Speed controlled machine tool

Abstract

A tool, attachable to a spindle of a machine tool and capable of changing independently a rotational speed of a cutting tool from that of the spindle, provided with a cutting tool for machining a workpiece, an electric motor for driving the machining tool, a generator for generating electric power to drive the electric motor by the rotation of the spindle, a tool holding part for rotatably holding the cutting tool, a casing for holding the electric motor, the generator, the tool attachment part, and the tool holding part, and a locking part for preventing rotation of the casing by engagement with a non-rotating part of the machine tool.A tool includes an AC generator, an AC motor and a case holding the generator and motor such that the generator and the motor are arranged in the case along a center axis and a longitudinal direction of a rotatable portion of the generator. A rotation speed of an output shaft of the motor is based on a rotation speed of an input shaft of the generator and a ratio, between a number of poles of the generator and a number of poles of the motor.

1. 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; 
 a tool attachable to said spindle and provided with 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. 
 
     
     
       2. 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. 
 
     
     
       3. 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. 
 
     
     
       4. A tool as set forth in  claim 3 , wherein
 said generator is a three-phase synchronous generator; and 
 said inductor motor is a three-phase induction motor. 
 
     
     
       5. A tool as set forth in  claim 2 , further comprising:
 a tool attachment part attachable to said spindle for transmitting the rotation of said spindle to said generator; 
 a tool holding part for rotatably holding said machining tool; 
 a casing for holding said electric motor, said generator, said tool attachment part, and said tool holding part; and 
 a locking part for preventing rotation of said casing by engagement with a non-rotating part of said machine tool. 
 
     
     
       6. 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. 
 
 
     
     
       7. A tool as set forth in  claim 6 , wherein said control means comprises:
 a memory for storing a program for driving and controlling said machining tool; 
 a processor for performing said program; and 
 a driving circuit for supplying the electric power from said generator to said electric motor in response to a control signal from said processor. 
 
     
     
       8. 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. 
 
 
     
     
       9. 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. 
 
 
     
     
       10. A tool as set forth in  claim 6 , further comprising:
 data input means for inputting various data required for controlling said electric motor to said control means from outside. 
 
     
     
       11. 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. 
 
 
     
     
       12. 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 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. 
 
     
     
       13. 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. 
 
 
     
     
       14. A tool holder as set forth in  claim 11 , further comprising:
 a tool attachment part attachable to said spindle for transmitting the rotation of said spindle to said generator; 
 a tool holding part for rotatably holding said machining tool; 
 a casing for holding said electric motor, said generator, said tool attachment part, and said tool holding part; 
 a locking part for preventing rotation of said casing by engagement with a non-rotating part of said machine tool. 
 
     
     
       15. A machine tool as set forth in  claim 9 , further comprising an automatic tool changer for attaching said tool to said spindle and detaching said tool from said spindle. 
     
     
       16. 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.   
     
     
       17. 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.   
     
     
       18. 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.