JP4652208B2 - Machine tool and transmission - Google Patents

Description

  The present invention relates to a machine tool and a transmission.

For example, in a machine tool equipped with a spindle that rotates a tool such as a machining center, the maximum rotation speed of the spindle is determined by the structure of the main bearing that holds the spindle rotatably and the lubrication method. For example, a speed increasing device is used to rotate the tool at the rotational speed.
As the speed increasing device, for example, a device that holds a tool and can be attached to and detached from the main shaft, and increases the rotational speed of the tool by increasing the rotational force of the main shaft by a gear mechanism such as a planetary gear mechanism is known. ing.
For example, in a machining center, when it is desired to temporarily increase the rotational speed of the tool beyond the maximum rotational speed of the main spindle, the speed increasing device as described above is applied to the main spindle by an automatic tool changer in the same manner as a normal tool. The tool is rotated at a high rotational speed.

By the way, when the tool is increased from the rotational speed of the main shaft by the speed increasing device using the gear mechanism as described above, if the tool is rotated at an ultra high speed of several tens of thousands to several hundred thousand, the heat generation of the speed increasing device increases. , May affect the processing accuracy. In addition, at ultra high speed rotation of several tens of thousands to several hundred thousand rotations, noise from the speed increasing device also increases. Furthermore, since the speed increasing device requires the reliability which can endure rotation of tens of thousands to hundreds of thousands of rotations, for example, there is a disadvantage that the manufacturing cost is relatively increased.
As another speed increasing method, there is a case where a high frequency motor is used as a motor for driving the main shaft, a driving current is supplied from a control device specially prepared for the high frequency motor, and the main shaft is rotated at a high speed. However, this method has the disadvantage that it is difficult to change the tool in the same way as a normal tool, and the equipment cost is relatively high.

  An object of the present invention is to provide a machine tool and a transmission that can change gears while suppressing heat generation and manufacturing costs.

  A transmission according to a first aspect of the present invention includes a main shaft, a transmission mounted on the main shaft, and a work unit held and rotated by the transmission, and the transmission includes the main shaft. A synchronous generator that generates electric power by rotation, an induction motor that is rotationally driven by the electric power generated by the generator, a rotary shaft that is connected to an output shaft of the electric motor and on which the work unit is mounted, the generator, An electric motor and a case for holding the rotating shaft, and the generator, the electric motor, and the rotating shaft are sequentially arranged along the longitudinal direction of the main shaft, and the input shaft of the generator and the electric motor An output shaft is coaxially arranged in the longitudinal direction of the main shaft.

  Preferably, the transmission device further includes a mounting portion that is mounted on the main shaft and connected to the input shaft of the generator, and the mounting portion, the generator, the electric motor, and the rotating shaft are longer than the main shaft. Arranged along the direction.

  Preferably, the case includes a first case member that rotatably holds the mounting portion, a second case member that rotatably holds the generator and the electric motor, and the rotation shaft that is rotatable. And a fastening means for connecting the first case member, the second case member, and the third case member.

  Preferably, the transmission increases the rotational speed of the work unit relative to the rotational speed of the main shaft.

  Preferably, the transmission is detachably attached to the main shaft.

  Preferably, the apparatus further includes an automatic work unit exchanging device that attaches and detaches the transmission that holds the work unit to and from the main shaft in the same manner as a normal work unit.

  Preferably, the apparatus further includes a non-rotating portion that pivotally supports the main shaft and does not rotate by rotation of the main shaft, and the case is inserted into a hole provided in the non-rotating portion to restrict the rotation of the case. When the transmission is mounted on the main shaft by the automatic work unit replacement device, the rotation restriction member is inserted into the hole.

  Preferably, the generator supplies a voltage having a frequency corresponding to the rotation speed of the main shaft to the electric motor, and the electric motor rotates at a rotation speed corresponding to the frequency.

  Preferably, the generator is a three-phase synchronous generator, and the motor is a three-phase induction motor.

  Preferably, a transmission gear ratio between the rotation speed of the main shaft and the rotation speed of the work unit is determined based on the number of poles of the three-phase synchronous generator and the three-phase induction motor.

  A machine tool according to a second aspect of the present invention includes a main shaft, a transmission mounted on the main shaft, and a work unit that is held and rotated by the transmission, and the transmission includes the main shaft. A DC generator that generates electric power by rotation; a DC motor that is rotationally driven by the electric power generated by the generator; a rotary shaft that is connected to an output shaft of the electric motor and on which the work unit is mounted; the generator; An electric motor and a case for holding the rotating shaft, and the generator, the electric motor, and the rotating shaft are sequentially arranged along the longitudinal direction of the main shaft, and the input shaft of the generator and the electric motor An output shaft is coaxially arranged in the longitudinal direction of the main shaft.

  A transmission according to a third aspect of the present invention is a transmission that is mounted on a main spindle of a machine tool, and is driven to rotate by a synchronous generator that generates electric power by rotation of the main spindle and electric power generated by the synchronous generator. An induction motor, a rotary shaft connected to the output shaft of the motor and mounted with a work unit, and a case for holding the generator, the motor, and the rotary shaft, the generator, the motor The rotating shaft is arranged in order along the longitudinal direction of the main shaft, and the input shaft of the generator and the output shaft of the electric motor are coaxially arranged in the longitudinal direction of the main shaft.

  Preferably, the apparatus further includes a mounting portion mounted on the main shaft and connected to the input shaft of the generator, and the mounting portion, the generator, the electric motor, and the rotating shaft are arranged along a longitudinal direction of the main shaft. Has been.

  Preferably, the case includes a first case member that rotatably holds the mounting portion, a second case member that rotatably holds the generator and the electric motor, and the rotation shaft that is rotatable. And a fastening means for connecting the first case member, the second case member, and the third case member.

  Preferably, the mounting portion is detachable from the main shaft.

  Preferably, the generator supplies a voltage having a frequency corresponding to the rotation speed of the main shaft to the electric motor, and the electric motor rotates at a rotation speed corresponding to the frequency.

  Preferably, the generator is a three-phase synchronous generator, and the motor is a three-phase induction motor.

  Preferably, a transmission gear ratio between the rotation speed of the main shaft and the rotation speed of the work unit is determined based on the number of poles of the three-phase synchronous generator and the three-phase induction motor.

  A transmission according to a fourth aspect of the present invention includes a synchronous generator that generates electric power by rotation of a first rotating shaft, an induction motor that is rotationally driven by electric power generated by the synchronous generator, and an output shaft of the electric motor. A second rotating shaft coupled to which the work unit is mounted, and a case for holding the generator, the electric motor, and the second rotating shaft, the generator, the electric motor, and the second rotating shaft. The rotating shaft is sequentially arranged along the longitudinal direction of the first rotating shaft, and the input shaft of the generator and the output shaft of the electric motor are coaxially arranged in the longitudinal direction of the first rotating shaft. ing.

  A transmission according to a fifth aspect of the present invention is a transmission that is mounted on a main shaft of a machine tool, and is rotationally driven by a DC generator that generates electric power by rotation of the main shaft and electric power generated by the DC generator. A DC motor, a rotating shaft connected to an output shaft of the motor, to which a work unit is mounted, and a case for holding the generator, the motor, and the rotating shaft, the generator, the motor The rotating shaft is arranged in order along the longitudinal direction of the main shaft, and the input shaft of the generator and the output shaft of the electric motor are coaxially arranged in the longitudinal direction of the main shaft.

  A transmission according to a sixth aspect of the present invention includes a direct current generator that generates electric power by rotation of a first rotary shaft, a direct current motor that is rotationally driven by electric power generated by the direct current generator, and an output shaft of the electric motor. A second rotating shaft coupled to which the tool is mounted; and a case for holding the generator, the electric motor, and the second rotating shaft, the generator, the electric motor, and the second rotation. The shaft is sequentially arranged along the longitudinal direction of the first rotating shaft, and the input shaft of the generator and the output shaft of the electric motor are coaxially arranged in the longitudinal direction of the first rotating shaft. Yes.

In the present invention, when the first rotating shaft is rotated, the generator generates power. Electric power generated by the generator is supplied to an electric motor, and a working unit such as a tool is driven by the electric motor. The rotation speed of the work unit is changed with respect to the rotation speed of the first rotation shaft according to the characteristics of the generator and the motor.
As described above, in the present invention, since the mechanical transmission element such as a gear mechanism is not used and the rotation speed of the work unit with respect to the first rotation shaft is changed, heat generation is reduced and the cost can be reduced. Become.
For example, when a three-phase synchronous generator is used as the generator, the frequency of the induced voltage generated by the three-phase synchronous generator due to the rotation of the first rotary shaft is proportional to the rotational speed of the first rotary shaft. On the other hand, when a three-phase induction motor is used as the motor, the rotation speed of the three-phase induction motor is substantially proportional to the frequency of the supplied voltage. For this reason, by using a three-phase synchronous generator as the generator and a three-phase induction motor as the motor, the gear ratio of the rotation speed of the work unit to the rotation speed of the main shaft can be easily controlled.
Furthermore, by appropriately selecting the number of poles of the three-phase synchronous generator and the three-phase synchronous generator, it is possible to arbitrarily set the speed increasing ratio or the speed reducing ratio of the rotational speed of the tool with respect to the rotational speed of the main shaft.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a machining center as an example of a machine tool to which the present invention is applied.
In FIG. 1, the machining center 1 includes a cross rail 37 supported at both ends by a shaft of a portal column 38 so as to be movable. A saddle 44 is supported on the cross rail 37 so as to be movable. A ram 45 is provided to be movable in the vertical direction (Z-axis direction).

A screw portion (not shown) is formed in the saddle 44 through the cross rail 37 in the horizontal direction, and a feed shaft 41 having a screw portion formed on the outer periphery thereof is screwed to the saddle 44.
A servo motor 19 is connected to one end of the feed shaft 41, and the feed shaft 41 is rotationally driven by the servo motor 19.
By the rotational drive of the feed shaft 41, the saddle 44 can move in the Y-axis direction, whereby the ram 45 is moved and positioned in the Y-axis direction.

Further, the saddle 44 is formed with a thread portion (not shown) in the vertical direction, and a feed shaft 42 having a thread portion formed on the outer periphery thereof is screwed into the saddle 44. A servo motor 20 is connected to the end of the feed shaft 42.
The feed shaft 42 is rotationally driven by the servo motor 20, whereby the ram 45 movably provided on the saddle 44 is moved and positioned in the Z-axis direction.

A main shaft motor 31 is built in the ram 45, and the main shaft motor 31 rotationally drives a main shaft (first rotation shaft) 46 that is rotatably held by the ram 45.
A tool T such as an end mill is attached to the tip of the main shaft 46, and the tool T is driven by the rotation of the main shaft 46.
A table 35 is provided below the ram 45 so as to be movable in the X-axis direction. A screw portion (not shown) is formed on the table 35, and a feed shaft (not shown) provided along the X-axis direction is screwed to the table 35, and the servo motor 18 is connected to the feed shaft (not shown). Yes.
The table 35 is moved and positioned in the X-axis direction by the rotational drive of the servo motor 18.

  The two portal columns 38 are respectively formed with screw portions (not shown), and the cross rail 37 is moved up and down by rotationally driving a feed shaft 32a screwed to the gate column 38 by a cross rail lifting motor 32. .

An automatic tool changer (ATC) 39 automatically changes various tools T with respect to the main shaft 46.
The automatic tool changer 39 stores, for example, various tools T held by a tool holder in a magazine (not shown), and stores the tool T mounted on the main shaft 46 in a magazine by a tool change arm (not shown). A simple tool T is mounted on the spindle 46 by a tool changing arm.

The NC device 51 performs drive control of the servo motors 18, 19, 20, the cross rail lifting / lowering motor 32, and the spindle motor 31.
Specifically, the NC device 51 performs position and speed control between the tool T and the workpiece by the servo motors 18, 19, and 20 in accordance with a workpiece machining procedure defined in advance by the NC program. The NC device 51 controls the rotational speed of the main shaft 46 by decoding the rotational speed of the main shaft 31 defined by, for example, the S code in the NC program.
Further, the NC device 51 executes automatic exchange of various tools T by decoding the operation of exchanging the tool T defined by the M code in the NC program, for example.

FIG. 2 is a cross-sectional view showing the configuration of an embodiment of the tool transmission of the present invention.
The tool transmission 61 shown in FIG. 2 is mounted on the tip of the main shaft 46 to constitute the transmission means of the present invention.
The transmission 61 includes a mounting portion 62, a case 65 including case members 66, 67 and 68, a three-phase synchronous generator 70, and a three-phase induction motor 80.
Here, the mounting portion 62 corresponds to one specific example of the mounting portion of the present invention, the case 65 corresponds to one specific example of the case of the present invention, and the three-phase synchronous generator 70 is the power generation of the present invention. The three-phase induction motor 80 corresponds to one specific example of the electric motor of the present invention.

  The mounting portion 62 includes a gripping portion 62a to be gripped, a taper shank portion 62b to be mounted on the taper sleeve 46a formed at the tip portion of the main shaft 46, and a clamp formed at the tip portion of the taper shank portion 62b. A portion 62c and a shaft portion 62d that is rotatably held by the case member 66 are provided.

  The gripping portion 62a of the mounting portion 62 is moved from the magazine of the automatic tool changer 39 to the main shaft 46 by the tool changing arm of the automatic tool changer 39 and from the main shaft 46 to the magazine of the automatic tool changer 39. Grasped when transported.

  The taper shank portion 62 b of the mounting portion 62 is mounted on the taper sleeve 46 a of the main shaft 46 so that the central axis is concentric with the central axis of the main shaft 46.

  When the mounting portion 62 is mounted on the tapered sleeve 46 a of the main shaft 46, the clamp portion 62 c of the mounting portion 62 is clamped by a clamp mechanism (not shown) built in the main shaft 46. The clamping mechanism built in the main shaft 46 is a well-known technique and will not be described in detail.

  The shaft portion 62 d of the mounting portion 62 is rotatably held on the inner periphery of the case member 66 via a plurality of rolling bearings 72.

A three-phase synchronous generator 70 and a three-phase induction motor 80 are held on the inner periphery of the case member 67 via a holding member 73.
In the three-phase synchronous generator 70, the input shaft 71 is concentrically connected to the shaft portion 62d of the mounting portion 62, and the rotational force of the main shaft 46 is input to the three-phase synchronous generator 70 via the mounting portion 62. The

The three-phase induction motor 80 is supplied with three-phase alternating current generated by the three-phase synchronous generator 70 through three conductive cables (not shown). The three-phase induction motor 80 is driven by electric power supplied from the three-phase synchronous generator 70.
The output shaft 81 of the three-phase induction motor 80 is connected to a rotating shaft (second rotating shaft) 90 by a coupling 87.
The input shaft 71 and the output shaft 81 are provided coaxially (coaxially). The coaxial shape is a state of being arranged in order along the axial direction, in other words, a state of not being concentric, and includes a state of being arranged on the same axis.

The rotating shaft 90 is rotatably held on the inner periphery of the case member 68 via a plurality of rolling bearings 92.
The distal end side of the rotation shaft 90 is prevented from being detached from the case member 68 by a retaining member 94.
In addition, a tool mounting portion 95 on which the above-described tool is mounted is provided at the distal end portion of the rotating shaft 90. For example, a tool such as a drill is held in the tool mounting portion 95.

On the other hand, the case members 66, 67 and 68 are connected by fastening means such as bolts, for example, and these case members 66, 67 and 68 constitute a case 65.
An anti-rotation member 85 is provided on the outer periphery of the case member 66. The anti-rotation member 85 corresponds to a specific example of the rotation restricting member of the present invention.
When the mounting portion 62 is mounted on the taper sleeve 46a of the main shaft 46, the anti-rotation member 85 has a tip 85a in the fitting hole 47a formed in the non-rotating portion 47 such as the ram 45 on the main shaft 46 side. Inserted.
Thereby, the rotation of the case member 66, that is, the case 66 is restricted even if the main shaft 46 rotates.

Here, an example of the operation of the transmission 61 configured as described above will be described.
When the automatic tool changer 39 mounts the transmission 61 holding the tool on the tool mounting portion 95 to the main shaft 46 of the machining center 1, the transmission 61 is fitted to the non-rotating portion 47 at the tip end 85 a of the rotation preventing member 85. The hole 47a is fitted and inserted, and the rotation of the case 65 is restricted.

When the main shaft 46 is rotated at the rotational speed N ₀ from this state, the mounting portion 62 of the transmission 61 is rotated, and the rotational force of the main shaft 46 is transmitted to the three-phase synchronous generator 70.
Thereby, the three-phase synchronous generator 70 generates a three-phase alternating current.

The frequency f of the three-phase alternating current generated by the three-phase synchronous generator 70 is given by the following equation (1), where the number of poles of the three-phase synchronous generator 70 is P ₁ and the rotational speed of the main shaft 46 is N ₀ [rpm]. Represented by

(Equation 1)
_{f = P 1 × N 0/} 120 [Hz] ... (1)

Therefore, when the main shaft 46 is rotated at the rotational speed N ₀ , the three-phase AC power having the frequency f expressed by the above equation (1) is supplied to the three-phase induction motor 80.

Here, if the number of poles of the three-phase induction motor 80 is P ₂ , the three-phase induction motor 80 rotates 2 / P _{2 in} one cycle of three-phase AC, so the synchronous speed N ₁ of the three-phase induction motor 80 is Is represented by the following equation (2).

(Equation 2)
N ₁ = 120 × f / P ₂ [rpm] (2)

Thus, the rotational speed _{N 1} of the tool with respect to the rotational speed _{N 0} of the spindle 46 is represented by the following formula (3).

(Equation 3)
N ₁ = N ₀ × P ₁ / P ₂ [rpm] (3)

As can be seen from the equation (3), the rotational speed N ₀ of the main shaft 46 is changed to the rotational speed N ₁ represented by the above expression (3).
(3) As shown by the equation, by setting the ratio of the number of poles P ₁ of the three-phase synchronous generator 70 and the pole number P ₂ of the three-phase induction motor 80 appropriately, the tool with respect to the rotational speed N ₀ of the spindle 46 it can be seen that setting the gear ratio of the rotational speed N ₁ arbitrarily.
That is, when it is desired to increase the rotational speed N ₀ of the main shaft 46, the pole number ratio P ₁ / P ₂ is made larger than 1, and when it is desired to decelerate, the pole number ratio P ₁ / P ₂ is made smaller than 1. as may be preselected number of poles P ₂ number of poles P ₁ and three-phase induction motor 80 of the three-phase synchronous generator 70.

Next, a method for driving a tool using the transmission 61 will be described.
For example, assuming that the maximum rotation speed Nmax of the main shaft 46 of the machining center 1 is 3000 rpm, the rotation speed of the main shaft 46 is sufficient in the range of the maximum rotation speed Nmax in machining a workpiece using a normal tool. There are many cases.
On the other hand, when the machining center 1 having a maximum rotation speed Nmax of the spindle 46 of 3000 rpm is used and, for example, an aluminum alloy material is used for the workpiece and it is desired to perform high-speed machining, the rotation speed of the tool is increased to 30000 rpm, for example. Sometimes you want to.
For such a case, the transmission 61 held by the tool mounting portion 95 is accommodated in advance in the magazine of the automatic tool changer 39 of the machining center 1. The transmission device 61 incorporates the three-phase synchronous generator 70 and the three-phase induction motor 80 having the pole number ratio P ₁ / P ₂ of 10 so that the speed increase ratio is 10.

The automatic tool changer 39 automatically mounts the transmission 61 on the main shaft 46 in the same manner as a normal tool.
The main shaft 46 is rotated by driving the main shaft motor 31. The rotation speed of the tool held by the transmission 61 is controlled by the rotation speed of the main shaft 46. That is, in the NC program downloaded to the NC device 51, the rotational speed of the tool held by the transmission device 61 is defined by designating the rotational speed of the main shaft 46 with an S code.
For example, when it is desired to rotate the tool held by the transmission 61 at 30000 rpm, the rotational speed of the main shaft 46 is designated as 3000 rpm by the S code in the NC program.

Rotation of the spindle 46 at 3000 rpm, the three-phase synchronous generator 70 generates three-phase alternating current having a frequency corresponding to the rotational speed and the number of poles P ₁ of the spindle 46.
The three-phase induction motor 80 is driven by the three-phase alternating current supplied from the three-phase synchronous generator 70, and the tool held in the transmission 61 rotates at a rotational speed of approximately 30000 rpm.
As a result, even if the machining center 1 in which the maximum rotation speed Nmax of the spindle is limited and an aluminum alloy material is used for the workpiece, high-speed machining can be performed.

As described above, according to the present embodiment, the three-phase synchronous generator 70 and the three-phase induction motor 80 are incorporated in the transmission 61 that is unitized in the same manner as a normal tool, and is generated by the three-phase synchronous generator 70. By driving the three-phase induction motor 80 with the generated electric power, the rotational speed of the tool with respect to the main shaft 46 is increased, so even if the main shaft 46 is rotated at a high speed, heat generation does not increase as in the gear device, and the machining accuracy is reduced. Is suppressed.
In the present embodiment, since the speed is changed using the three-phase synchronous generator 70 and the three-phase induction motor 80, the cost can be reduced as compared with the case where a transmission mechanism such as a gear device is used.

Further, according to the present embodiment, the transmission 61 that increases the rotational speed of the main shaft 46 can be freely attached to and detached from the main shaft 46 and can be replaced by the automatic tool changer 39 in the same manner as a normal tool. Therefore, it is possible to immediately respond to the request to rotate the tool at a high speed while processing the tool within the range of the normal rotation speed.
Further, according to the present embodiment, since the tool is driven by the electric power generated by the rotation of the main shaft 46, it is not necessary to supply a driving current from the outside, and as a result, connection for power supply is not necessary.

Furthermore, in this embodiment, since the three-phase synchronous generator 70 is used as the generator and the three-phase induction motor 80 is used as the motor, the rotational speed of the tool held by the transmission 61 is set to the rotational speed of the main shaft 46. Can be easily controlled. That is, the three-phase synchronous generator 70 generates a voltage having a frequency that is exactly proportional to the rotational speed of the main shaft 46, and the three-phase induction motor 80 drives the tool at a rotational speed proportional to this frequency. The rotational speed of the tool can be easily and accurately controlled by the rotational speed and the pole ratio between the three-phase synchronous generator 70 and the three-phase induction motor 80.
Further, since the three-phase induction motor 80 does not require a position detection element for detecting the rotational position of the rotor, no wiring is required from the NC device 51 to the transmission device 61, and the transmission device 61 is completely independent. And can be handled just like a normal tool.

In addition, this invention is not limited to embodiment mentioned above.
In the embodiment described above, the case of applying the aluminum alloy material to high-speed machining has been described. However, the present invention can be applied to any machining that needs to increase the rotational speed of the main shaft 46.
In the above-described embodiment, the case where the rotational speed of the main shaft 46 is increased has been described. However, the present invention can also be applied to the case where the rotational speed of the main shaft 46 is decelerated. In this case, a torque larger than that of the main shaft 46 can be applied to the tool.

In the above-described embodiment, the case where the three-phase synchronous generator 70 is used as the generator and the three-phase induction motor 80 is used as the motor has been described. For example, the main shaft 46 can be combined by a combination of a DC generator and a DC motor. It is also possible to employ a configuration that changes the rotational speed. That is, since the rotational speed of the DC motor is determined by the voltage and load supplied from the DC generator, it is difficult to directly control the rotational speed of the tool from the rotational speed of the main shaft 46. By measuring the output characteristics and load characteristics of the DC generator, the rotational speed of the main shaft 46 can be changed at a constant speed increase ratio or speed reduction ratio by a combination of the DC power generator and the DC motor. It is also possible to use other types of generators and motors.
In the above-described embodiment, the electric motor is directly driven by the electric power generated by the generator. However, for example, the electric power generated by the generator is supplied to the electric motor so that the rotational speed of the electric motor is variable-speed controlled. It is also possible to adopt a configuration in which a transmission circuit is provided with a control circuit for controlling

1 is a configuration diagram of a machining center as an example of a machine tool to which the present invention is applied. It is sectional drawing which shows one Embodiment of the transmission of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Machining center 31 ... Main shaft motor 39 ... Automatic tool changer 46 ... Main shaft 51 ... NC device 61 ... Transmission device 62 ... Mounting part 65 ... Case 66, 67, 68 ... Case member 70 ... Three-phase synchronous generator 71 ... Input shaft 80 ... Three-phase induction motor 81 ... Output shaft 95 ... Tool mounting part

Claims (7)

The spindle,
A transmission mounted on the main shaft;
A work unit held and rotated by the transmission,
The transmission is
A mounting portion mounted on the main shaft;
A synchronous generator having an input shaft connected to the mounting portion and generating electric power by rotation of the main shaft;
An induction motor that is driven to rotate faster than the main shaft by the electric power generated by the generator;
A rotating shaft connected to the output shaft of the electric motor and mounted with the work unit;
A case for holding the generator, the electric motor and the rotating shaft;
Have
The mounting portion, the generator, the electric motor, and the rotating shaft are sequentially arranged along the longitudinal direction of the main shaft, and the input shaft of the generator and the output shaft of the electric motor are coaxial with the longitudinal direction of the main shaft. Arranged in a shape,
The case is
A first case member that rotatably holds the mounting portion;
A second case member that holds the generator and the motor in a non-rotatable manner via a holding member that contacts the outer periphery of the generator and the motor;
A third case member for rotatably holding the rotating shaft;
Fastening means for connecting the first case member, the second case member, and the third case member;
Machine tool with. The diameter of the electric motor is larger than the diameter of the generator
The machine tool according to claim 1. Machine tool the number of poles of the synchronous generator according to claim 1 or 2 larger than the number of poles of the induction motor. The generator is a three-phase synchronous generator;
The electric motor is a three-phase induction motor;
The gear ratio between the rotation speed of the main shaft and the rotation speed of the work unit is determined based on the number of poles of the three-phase synchronous generator and the three-phase induction motor. The machine tool described in 1. The spindle,
A transmission mounted on the main shaft;
A work unit held and rotated by the transmission,
The transmission is
A mounting portion mounted on the main shaft;
A DC generator having an input shaft coupled to the mounting portion and generating electric power by rotation of the main shaft;
A DC motor that is driven to rotate faster than the main shaft by the electric power generated by the generator;
A rotating shaft connected to the output shaft of the electric motor and mounted with the work unit;
A case for holding the generator, the electric motor and the rotating shaft;
Have
The mounting portion, the generator, the motor, and the rotating shaft are sequentially arranged along the longitudinal direction of the main shaft, and the input shaft of the generator and the output shaft of the motor are coaxial with the longitudinal direction of the main shaft. Arranged in a shape,
The case is
A first case member that rotatably holds the mounting portion;
A second case member that holds the generator and the motor in a non-rotatable manner via a holding member that contacts the outer periphery of the generator and the motor;
A third case member for rotatably holding the rotating shaft;
Fastening means for connecting the first case member, the second case member, and the third case member;
Machine tool with. A transmission mounted on a spindle of a machine tool,
A mounting portion mounted on the main shaft;
A synchronous generator having an input shaft connected to the mounting portion and generating electric power by rotation of the main shaft;
An induction motor that is driven to rotate faster than the main shaft by the electric power generated by the synchronous generator;
A rotating shaft connected to the output shaft of the electric motor and mounted with a work unit;
A case for holding the generator, the electric motor and the rotating shaft;
Have
The mounting portion, the generator, the motor, and the rotating shaft are sequentially arranged along the longitudinal direction of the main shaft, and the input shaft of the generator and the output shaft of the motor are coaxial with the longitudinal direction of the main shaft. Arranged in a shape,
The case is
A first case member that rotatably holds the mounting portion;
A second case member that holds the generator and the motor in a non-rotatable manner via a holding member that contacts the outer periphery of the generator and the motor;
A third case member for rotatably holding the rotating shaft;
Fastening means for connecting the first case member, the second case member, and the third case member;
A transmission having A transmission mounted on a spindle of a machine tool,
A mounting portion mounted on the main shaft;
A DC generator having an input shaft coupled to the mounting portion and generating electric power by rotation of the main shaft;
A DC motor that is driven to rotate faster than the main shaft by the electric power generated by the DC generator;
A rotating shaft connected to the output shaft of the electric motor and mounted with a work unit;
A case for holding the generator, the electric motor and the rotating shaft;
Have
The mounting portion, the generator, the motor, and the rotating shaft are sequentially arranged along the longitudinal direction of the main shaft, and the input shaft of the generator and the output shaft of the motor are coaxial with the longitudinal direction of the main shaft. Arranged in a shape,
The case is
A first case member that rotatably holds the mounting portion;
A second case member that holds the generator and the motor in a non-rotatable manner via a holding member that contacts the outer periphery of the generator and the motor;
A third case member for rotatably holding the rotating shaft;
Fastening means for connecting the first case member, the second case member, and the third case member;
A transmission having

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