Machine tool, in particular for drilling

1. A machining tool comprising a drive shaft of a tool extending along an axis, a first motor connected to a coupling member which is in sliding connection with a first section of the shaft in order to drive the shaft in rotation about the axis and a second motor connected to a nut which is in helicoidal connection with a second section of the shaft in order to move axially the shaft along the axis, the first motor and the second motor being coaxial with one another and connected to a control unit connected to position sensors of rotors of the first motor and second motor, the control unit controlling the first motor and second motor so as to produce an axial displacement at constant speed of the drive shaft and to superpose onto this axial displacement axial oscillations having an amplitude and a frequency adapted for chip fragmentation, the control unit permitting a modification in real time of the amplitude and the frequency of the axial oscillations independently of the drive shaft rotation about the axis.

2. The machine as claimed in claim 1 , wherein the oscillations have a waveform which is sinusoidal, trapezoidal, saw-tooth-shaped, etc.

3. The machine as claimed in claim 1 , wherein the control unit determines the electrical parameters of the motors and determines the machining conditions from these parameters.

4. The machine as claimed in claim 1 , wherein the control unit determines the electrical parameters of the motors and deduces therefrom the effective position of the part to be machined.

5. The machine as claimed in claim 1 , wherein the control unit determines and compares the speeds of the motors to detect a fault in the machine or the cutting tool.

6. The machine as claimed in claim 1 , wherein since the tool has a shape which is at least partially helicoidal, the helicoidal connection and the tool have pitches in opposing directions, so as to reduce the time to implement a return cycle of the tool.

7. The machine as claimed in claim 1 , wherein the control unit modifies the oscillations as a function of the machining conditions determined in real time and continuously by measuring the angular and linear positions and the angular and linear speeds of the shaft: in the case of a discrepancy with predetermined machining reference values which are favorable to chip fragmentation, the control unit controls the motors to make an adjustment for the discrepancy.

8. The machine as claimed in claim 1 , for the machining of a part consisting of two different materials arranged in succession, wherein the control unit modifies the oscillations when the material changes, in order to continue with the chip fragmentation by changing the control parameters of the motors in order to adapt said parameters in an optimum manner to the machined material.

9. The machine as claimed in claim 1 , wherein a change is carried out by programming, taking into account the angular and linear positions of the shaft and the relative position of the two materials in the part to be machined.

10. The machine as claimed in claim 1 , wherein a change is carried out by detecting and processing motor currents to cause the change of control parameters, as a function of an increase or reduction in the motor currents representing an increase or reduction in the cutting force.

11. A machining tool comprising a drive shaft of a tool extending along an axis, a first motor connected to a coupling member which is in sliding connection with a first section of the shaft in order to drive the shaft in rotation about the axis and a second motor connected to a nut which is in helicoidal connection with a second section of the shaft in order to move axially the shaft along the axis, the first motor and the second motor being

coaxial with one another and connected to a control unit connected to position sensors of rotors of the first motor and second motor, the control unit being programmed to control the first motor and second motor so as to produce an axial displacement at constant speed of the drive shaft and to superpose onto this axial displacement axial oscillations having an amplitude and a frequency adapted for chip fragmentation, the control unit permitting a modification in real time of the amplitude and the frequency of the axial oscillations independently of the drive shaft rotation about the axis.

12. A machining tool comprising a drive shaft of a tool extending along an axis, a first motor connected to a coupling member which is in sliding connection with a first section of the shaft in order to drive the shaft in rotation about the axis and a second motor connected to a nut which is in helicoidal connection with a second section of the shaft in order to move axially the shaft along the axis, the first motor and the second motor being coaxial with one another and connected to a control unit connected to position sensors of rotors of the first motor and second motor, the control unit determining in real time and a synchronized manner an angular position and electrical parameters enabling the control unit to control the first motor and second motor so as to produce an axial displacement at constant speed of the drive shaft and to superpose onto this axial displacement axial oscillations having an amplitude and a frequency adapted for chip fragmentation, the control unit permitting a modification in real time of the amplitude and the frequency of the axial oscillations independently of the drive shaft rotation about the axis.

13. The machine tool according to claim 11 , wherein the control unit determines in real time and a synchronized manner an angular position and electrical parameters enabling the control unit to control the first motor and the second motor.