JP6175922B2 - Spindle device - Google Patents

Description

  The present invention relates to a spindle device used in a machine tool.

  For example, Patent Document 1 discloses a spindle device that supports a spindle by a plurality of ball bearings and aerostatic bearings. In this spindle device, in order to more effectively suppress chatter vibration during processing, the aerostatic bearing is disposed on the tip side (tool side) of the spindle relative to the ball bearing.

JP 2004-106091 A

  However, in order to more effectively suppress chatter vibration, when a damping additional bearing using a liquid is used, a fluid having a high viscosity is used, so that the shear resistance of the fluid increases. The fluid is repeatedly sheared by the rotation of the main shaft, so that the fluid generates heat. As a result, thermal displacement of the spindle occurs, affecting the machining accuracy.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a main shaft device that can suppress vibration of the main shaft while suppressing heat generation of the fluid of the damping additional bearing.

(Claim 1) A main spindle device according to the present means is arranged inside a housing, inside the housing, holds a tool, is driven to rotate, and supports the main spindle to be rotatable with respect to the housing. A damping supply bearing that suppresses vibration of the bearing and the main shaft, and is a damping supply portion that is a circumferential annular gap between the inner peripheral surface of the housing and the outer peripheral surface of the main shaft, and a fluid supply that supplies fluid to the attenuation addition portion e Bei a drain for discharging the fluid from the road and attenuation adding unit, a damping additional bearing suppressing damping effect of the vibration of the spindle increases as the flow rate of the fluid is increased to be supplied to the attenuation adding unit, the fluid supply passage A fluid supply device that can adjust the flow rate of the fluid and a control device that periodically varies the flow rate of the fluid supplied by the fluid supply device.

  According to this means, the control device can reduce the flow rate of the fluid while exhibiting the damping effect by the damping additional bearing by periodically changing the flow rate of the fluid supplied by the fluid supply device. If the fluid flow rate decreases, the fluid pressure decreases. Thereby, since the shear resistance of a fluid becomes small, the heat_generation | fever of a fluid can be suppressed. Furthermore, if the flow rate of the fluid is reduced, the area of the flow path such as the drain can be reduced, so that the damping additional bearing can be reduced in size.

(Claim 2) Preferably, the control device increases the flow rate of the fluid supplied by the fluid supply device in accordance with an increase in the rotational speed of the main shaft.

That is, the control device performs control so that the flow rate of the fluid is increased as the rotational speed of the main shaft increases. Thereby, the fluid is discharged from the damping additional bearing in a short time. Therefore, even if the rotation speed of the main shaft is increased and the fluid is repeatedly sheared to increase the heat generation of the fluid, the fluid is discharged from the damping additional bearing in a short time, so that the heat generation of the fluid is suppressed. Is done.

(Claim 3) Further, the spindle device further includes a resistance detection sensor for detecting a cutting resistance during machining by the tool, and the control device responds to an increase in the cutting resistance detected by the resistance detection sensor. Increases the flow rate of the fluid supplied.

That is, the control device controls to increase the flow rate of the fluid when the cutting resistance during processing by the tool increases. When the cutting resistance during machining by the tool increases, there is a possibility that a large vibration is generated in the main shaft. Therefore, before the large vibration is generated, the amount of the fluid in the predetermined time is changed, and the damping effect by the damping additional bearing is enhanced, so that the large vibration can be prevented from occurring in the main shaft.

(Claim 4) Further, the fluid supply device further includes a valve having a valve body that opens or closes the fluid flow path, and the control device uses the valve to open and close the fluid flow path. By repeating the above and supplying the fluid intermittently every predetermined time, the flow rate of the fluid is periodically changed, and when the flow rate of the fluid is increased, the amount of the fluid within the predetermined time is increased.

It is sectional drawing of the axial direction of the main axis | shaft apparatus in 1st embodiment of this invention. FIG. 2 is an enlarged axial sectional view of the damping additional bearing shown in FIG. 1. It is sectional drawing of the axial direction of the valve | bulb in the fluid supply apparatus shown in FIG. 1, and represents the state by which the electromagnetic coil is not energized. It is sectional drawing of the axial direction of the valve | bulb in the fluid supply apparatus shown in FIG. 1, and represents the state by which the electromagnetic coil is energized. It is a time chart about the control which the control apparatus shown in FIG. It is a time chart which shows the operation | movement of the main shaft apparatus in 1st embodiment, an upper stage represents the electric current value supplied to an electromagnetic coil, the flow volume of the fluid supplied to a damping addition bearing, and a lower stage represents the damping coefficient of a damping addition bearing. Yes. It is a time chart showing the 1st modification of the control signal which the control device transmits when changing the flow rate of the fluid in the first embodiment and the second embodiment within the cycle, and the upper stage is the control signal and the damping additional bearing. The lower part represents the damping coefficient of the damping additional bearing. It is a time chart showing the 2nd modification of the control signal which the control device transmits when changing the flow rate of the fluid in the first embodiment and the second embodiment within the cycle, and the upper stage is the control signal and the damping additional bearing. The lower part represents the damping coefficient of the damping additional bearing. It is a time chart showing the 3rd modification of the control signal which the control device in the first embodiment and the second embodiment transmits.

  Hereinafter, a first embodiment in which the spindle device 1 of the present invention is embodied will be described with reference to the drawings. The configuration of the spindle device 1 will be described with reference to FIG. As shown in FIG. 1, the main shaft device 1 includes a housing 10, a main shaft 20, a motor 30, a plurality of rolling bearings 41 to 44, a damping additional bearing 50, a fluid supply device 60, and a control device 80.

  The housing 10 is formed in a hollow cylindrical shape, and holds the main shaft 20 therein. The main shaft 20 holds the tool 21 and is rotationally driven. Specifically, the main shaft 20 holds the tool 21 on the tip side (left side in FIG. 1) and is rotationally driven by the motor 30. The motor 30 is disposed in a cylinder of the housing 10 and includes a stator 31 fixed to the housing 10 and a rotor 32 fixed to the main shaft 20. Further, the motor 30 includes a rotation speed sensor (not shown) that detects the rotation speed R of the main shaft 20. In the present embodiment, the rotation speed sensor is, for example, a magnetic encoder.

  The rolling bearings 41 to 44 support the main shaft 20 rotatably with respect to the housing 10. As the rolling bearings 41 to 43, for example, ball bearings are applied, and the rolling bearings 41 to 43 are arranged closer to the tool 21 than the motor 30. On the other hand, the rolling bearing 44 is, for example, a roller bearing and is disposed on the opposite side (rear end side) of the tool 21 from the motor 30. That is, the rolling bearings 41 to 44 are arranged so as to sandwich the motor 30 in the center in the axial direction.

  The damping additional bearing 50 suppresses the vibration of the main shaft 20 when a fluid is supplied. The damping additional bearing 50 is provided closer to the tool 21 than the rolling bearings 41 to 44. As shown in FIG. 2, the damping additional bearing 50 includes a damping adding portion 51, a fluid supply path 52, a drain 53, an air supply annular groove 54, and an air supply path 55. In FIG. 2, an arrow indicated by a solid line indicates a direction in which the fluid flows, and an arrow indicated by a dashed line indicates the direction in which the air flows.

  The damping addition portion 51 is formed by a circumferential annular gap between the inner peripheral surface of the damping addition bearing 50 and the outer peripheral surface of the main shaft 20. By supplying the fluid to the damping adding portion 51, a damping effect for suppressing the vibration of the main shaft 20 is exhibited. The attenuation effect changes according to the flow rate Q of the fluid supplied to the attenuation adding unit 51. Specifically, the damping effect increases as the fluid flow rate Q increases, and the damping effect decreases as the flow rate Q decreases. The damping coefficient C representing the magnitude of the damping effect is determined by the flow path resistance such as the size of the gap, the fluid characteristics such as viscosity, the fluid flow rate Q, and the like. In this embodiment, the fluid is, for example, oil.

  One end of the fluid supply path 52 is connected to the fluid supply device 60. The fluid supplied from the fluid supply device 60 is led out from the lead-out port 52 a to the attenuation adding unit 51 through the fluid supply path 52. One or more outlets 52 a are arranged in the circumferential direction of the inner peripheral surface of the damping additional bearing 50.

  The drain 53 is formed by a concave portion provided annularly in the circumferential direction of the inner peripheral surface of the damping additional bearing 50, and an annular groove 53 a and a lead-out port 52 a disposed closer to the tool 21 than the lead-out port 52 a of the fluid supply path 52. An annular groove 53b disposed on the opposite side of the tool 21 is provided. The fluid is introduced from the damping addition portion 51 into the drain 53 through the annular grooves 53 a and 53 b, and the fluid is led out to the tank (not shown) that stores the fluid through the drain 53.

  The air supply annular groove 54 is formed by a recess provided annularly in the circumferential direction of the inner peripheral surface of the damping additional bearing 50, and includes an air annular groove 54 a and an annular groove 53 b disposed closer to the tool 21 than the annular groove 53 a. Is also formed by an air annular groove 54 b disposed on the opposite side of the tool 21. The air supply annular groove 54 guides the air supplied from an air pump (not shown) through the air supply path 55 to the attenuation adding portion 51. The derived air constitutes an air seal that prevents the fluid from being discharged from the damping addition portion 51 to the tool 21 side or the bearings 41 to 44 side.

  The fluid supply device 60 supplies fluid to the damping additional bearing 50 so that the flow rate Q of the fluid can be adjusted. As shown in FIG. 3A, the fluid supply device 60 includes a valve 70 and a pump (not shown).

  The valve 70 includes a body 71, a valve body 72, a spring 73 that biases the valve body 72 on the right side of FIG. The body 71 is formed in a hollow cylindrical shape, and holds the valve body 72 therein so as to be slidable in the axial direction. The body 71 has a flow path 71a through which fluid is supplied from the tank by a pump, a flow path 71b through which fluid is discharged from the body 71 to the tank, and a fluid supply path 52 for supplying fluid from the body 71 to the damping additional bearing 50. The flow path 71c connected to is provided.

  The valve body 72 is formed as a shaft-like member, and opens or closes the fluid flow paths 71b and 71c. The valve body 72 has a land 72a that opens or closes the flow path 71b, a land 72b that opens or closes the flow path 71c, and both sides of the lands 72a and 72b have a smaller outer shape than the lands 72a and 72b. A shaft portion 72c is provided.

  The solenoid part 74 operates the valve body 72, and is comprised by the proportional solenoid in this embodiment. The solenoid unit 74 includes an electromagnetic coil 74a that generates a magnetic force when energized and a plunger 74b that is slidably held in the axial direction of the valve 70. The plunger 74 b is a magnetic metal shaft-like member, and the end surface 74 ba of the plunger 74 b comes into contact with the end surface 72 d of the valve body 72 by the biasing force of the spring 73.

  Here, the valve 70 shown in FIG. 3A represents a state where the electromagnetic coil 74a is not energized. In this case, since the valve body 72 and the plunger 74b are urged to the right side of FIG. 3A by the spring 73, the end surface 74bb of the plunger 74b comes into contact with the end surface 71d of the body 71, and the position X of the valve body 72 is changed to FIG. It is fixed at the first position X1 shown. At this time, since the land 72a opens the flow path 71b and the land 72b closes the flow path 71c, the flow path 71a and the flow path 71b communicate with each other.

  In addition, the valve 70 shown in FIG. 3B is in a state where the electromagnetic coil 74a is energized. In this case, the plunger 74b moves to the left in FIG. 3B against the biasing force of the spring 73 by the magnetic attraction force generated by the magnetic force generated by the electromagnetic coil 74a. As a result, the valve body 72 also moves, and the position X of the valve body 72 is fixed at a position where the magnetic attractive force of the electromagnetic coil 74a and the biasing force of the spring 73 are balanced. At this time, since the land 72a closes the flow path 71b and the land 72b opens the flow path 71c, the flow path 71a and the flow path 71c communicate with each other.

  Specifically, the land 72b is provided with a groove 72ba on the outer peripheral surface thereof, and the flow path 71a and the flow path 71c communicate with each other through the groove 72ba. Here, the position X of the valve body 72 and the shape of the groove 72ba are set so that the amount of movement of the valve body 72 is proportional to the opening area of the flow path 71c. Therefore, the flow rate Q of the fluid to the damping additional bearing 50 can be controlled by changing the position X of the valve body 72 and changing the opening area of the flow path 71c.

  Here, in order to change the position X of the valve body 72, the movement amount of the plunger 74b may be controlled. Here, the amount of movement of the plunger 74b is proportional to the magnetic force of the electromagnetic coil 74a. That is, in order to control the movement amount of the plunger 74b, the magnetic force of the electromagnetic coil 74a may be controlled. In order to control the magnetic force of the electromagnetic coil 74a, since the magnetic force and the current value I are proportional, the current value I supplied to the electromagnetic coil 74a may be controlled.

  Therefore, by controlling the current value I supplied to the electromagnetic coil 74a, the position X of the valve body 72 can be changed, and the opening area of the flow path 71c can be changed. Therefore, the flow rate Q of the fluid to the damping additional bearing 50 can be controlled by the current value I supplied to the electromagnetic coil 74a. The current value I and the flow rate Q are set to be proportional.

  The control device 80 includes a CPU unit that executes arithmetic processing, a storage unit such as a ROM or a RAM that stores programs, and an input / output unit that exchanges information.

  The control device 80 is electrically connected to the rotation speed sensor and the fluid supply device 60. The rotational speed R of the spindle 20 detected by the rotational speed sensor is transmitted to the control device 80 as a detection signal. The control device 80 sets the value of the fluid flow rate Q based on the detection signal from the rotation sensor, and transmits the value to the fluid supply device 60 as the control signal S. A control signal S corresponding to the rotation speed R detection signal is set in advance and stored in the storage unit. The control signal S is set so that the flow rate Q increases as the rotational speed R increases.

  In the present embodiment, as shown in FIG. 4, the control signal S is a signal in which a rectangular waveform formed from the level L and the time T is intermittently repeated with a period P. Here, the level L is set to be proportional to the current value I. Therefore, since the current value I can be changed by changing the level L, the flow rate Q can be controlled. Here, as described above, since the current value I and the flow rate Q are set to be proportional, the level L and the flow rate Q are proportional.

  Specifically, when the rotational speed R is the first rotational speed R1, the control signal S has a rectangular waveform with the level L as the first level L1 and the time T as the first time T1, and the period P. Is set as the first cycle P1, and a first control signal S1 is set which is intermittently repeated.

  For example, when the rotation speed R changes and becomes the second rotation speed R2 larger than the first rotation speed R1, the control signal S does not change the first time T1 and the first period P1. The second control signal S2 that intermittently repeats a waveform in which the level L is changed to a second level L2 (for example, 1.5 times larger than the first level L1) larger than the first level L1 is set. That is, the waveform level L is set to be changed based on the rotational speed R, and the flow rate Q is set to be controlled by changing the waveform level L.

  As described above, since the control signal S in which the rectangular waveform is intermittently repeated is transmitted to the fluid supply device 60, the control device 80 periodically varies the flow rate Q of the fluid supplied by the fluid supply device 60. Let In addition, since the flow rate Q is controlled by changing the level L of the waveform of the control signal S in accordance with the rotational speed R, the control device 80 causes the spindle 20 to change when the fluid flow rate Q is periodically changed. The amount QTs of the fluid at a predetermined time Ts is changed according to the number of rotations R. The predetermined time Ts is the time of the longest period P among the preset periods P. Since the period P set in the present embodiment is only the first period P1, the first predetermined time Ts1 in the present embodiment is the same as the time of the first period P1.

  Next, the operation of the spindle device 1 described above will be described along the time chart shown in FIG. The spindle device 1 performs workpiece cutting and the like according to a preset program stored in the control device 80. At this time, at the start of machining (time t1), the rotation speed R of the main shaft 20 is the first rotation speed R1, and the control device 80 transmits the first control signal S1 to the fluid supply device 60.

  At this time, the fluid supply device 60 supplies a current corresponding to the first control signal S1 to the electromagnetic coil 74a. That is, after supplying the first current value IL1 that is the current value I corresponding to the first level L1 for the first time T1, the current value I is set to zero in the first period P1.

  When a current is supplied to the electromagnetic coil 74a at the first current value IL1, the valve body 72 moves to the second position X2, as shown by a solid line in FIG. 3B. At this time, since the flow path 71b is closed and the flow path 71c is opened, the flow path 71a and the flow path 71c communicate with each other. Thereby, the fluid supplied from the tank through the flow path 71a by the pump is supplied to the damping additional bearing 50 through the flow path 71c with the flow rate Q at the first flow rate Q1. The attenuation coefficient C at this time is the first attenuation coefficient C1.

  When the first time T1 has elapsed (time t2), the current value I becomes zero, so that only the urging force of the spring 73 acts on the valve body 72, and the valve body 72 is the first shown in FIG. 3A. Move to position X1. At this time, since the flow path 71b is in an open state, the fluid is recovered into the tank via the flow path 71b. Further, since the flow path 71c is closed, the flow rate Q of the fluid supplied to the damping additional bearing 50 becomes zero.

  At this time, since the fluid is not supplied to the damping additional bearing 50, the fluid is not completely discharged from the drain 53. That is, immediately after the supply of the fluid is stopped, the fluid is discharged from the drain 53 by the pressure remaining in the fluid. However, when a certain amount of fluid is discharged and the pressure of the fluid drops to a certain pressure, the fluid is not discharged due to the influence of the pipe resistance or the like, and the fluid remains in the attenuation adding portion 51. Thereby, the damping additional bearing 50 exhibits a damping effect. The attenuation coefficient C at this time is a second attenuation coefficient C2 that is smaller than the first attenuation coefficient C1.

  Then, when the first period P1 has elapsed from the start of processing (time t3), a control signal of the first level L1 is transmitted to the fluid supply device 60. Therefore, while the first control signal S1 is transmitted to the fluid supply device 60, the above-described operation is repeated. That is, the first current value IL1 is intermittently supplied to the electromagnetic coil 74a, and the valve body 72 alternately moves between the second position X2 and the first position X1. Further, the period P varies in the first period P1 between the flow rate Q between the first flow rate Q1 and zero, and the attenuation coefficient C between the first attenuation coefficient C1 and the second attenuation coefficient C2. Therefore, when the flow rate Q of the fluid is periodically changed, the control device 80 controls the flow path to alternately repeat the open state and the closed state by operating the valve body 72. Since the first predetermined time Ts1 in the present embodiment is the same as the time of the first period P1, the fluid amount QTs1 at the first predetermined time Ts1 in the first control signal S1 is as shown in Expression (1). become.

[Equation 1]
QTs1 = Q1 × T1 (1)

  When the rotational speed R is changed to the second rotational speed R2, the second control signal S2 is transmitted to the fluid supply device 60 (time t4).

  At this time, the fluid supply device 60 supplies a current corresponding to the second control signal S2 to the electromagnetic coil 74a. That is, after supplying the second current value IL2, which is the current value I corresponding to the second level L2, for the first time T1, the current value I is set to zero in the first period P1.

  When a current is supplied to the electromagnetic coil 74a at the second current value IL2, as shown by a dotted line in FIG. 3B, the valve body 72 moves to the third position X3. At this time, since the flow path 71b is closed and the flow path 71c is opened, the flow path 71a and the flow path 71c communicate with each other. However, since the position of the groove 72ba with respect to the flow path 71c is different from that in the second position X2, the opening area of the flow path 71c is large. Thereby, the fluid supplied via the flow path 71a is supplied to the damping additional bearing 50 at the second flow rate Q2 larger than the first flow rate Q1. The attenuation coefficient C at this time is a third attenuation coefficient C3 that is larger than the first attenuation coefficient C1.

  And after the 1st time T1 passes (time t5), since the electric current value I becomes zero, the valve body 72 moves to the 1st position X1. At this time, since the flow path 71b is in an open state, the fluid is recovered into the tank via the flow path 71b. Further, since the flow path 71c is in a closed state, the flow rate Q supplied to the damping additional bearing 50 is zero.

  At this time, as described above, since the fluid remains in the damping addition portion 51, the damping addition bearing 50 exhibits a damping effect. The attenuation coefficient C at this time is a fourth attenuation coefficient C4 that is smaller than the first attenuation coefficient C1 and larger than the second attenuation coefficient C2.

  Then, when the first period P1 elapses after the rotation speed R is changed to the second rotation speed R2 (time t6), a signal of the second level L2 is transmitted to the fluid supply device 60. While the second control signal S2 is transmitted to the fluid supply device 60, the above-described operation is repeated. That is, the second current value IL2 is intermittently supplied to the electromagnetic coil 74a, and the valve body 72 is alternately moved between the third position X3 and the first position X1. Further, the period P is changed in the first period P1 between the flow rate Q between the second flow rate Q2 and zero, and the attenuation coefficient C between the third attenuation coefficient C3 and the fourth attenuation coefficient C4.

  In addition, since the first predetermined time Ts1 in the present embodiment is the same time as the first period P1, the fluid amount QTs2 at the first predetermined time Ts1 in the second control signal S2 is as shown in Expression (2). become.

[Equation 2]
QTs2 = Q2 × T1 (2)

  Here, since the second level L2 is 1.5 times the first level L1, the second flow rate Q2 is 1.5 times the first flow rate Q1. Therefore, the fluid quantity QTs2 is 1.5 times the fluid quantity QTs1. When the amount of fluid QTs increases, the fluid pressure increases, so that the fluid is discharged from the damping additional bearing 50 in a short time.

  According to the present embodiment, the control device 80 periodically reduces the fluid flow rate Q supplied by the fluid supply device 60, thereby reducing the fluid flow rate Q while exhibiting the damping effect of the damping additional bearing 50. can do. If the fluid flow rate Q decreases, the fluid pressure decreases. Thereby, since the shear resistance of a fluid becomes small, the heat_generation | fever of a fluid can be suppressed. Further, if the flow rate Q of the fluid is reduced, the area of the flow path of the drain 53 and the like can be reduced, so that the damping additional bearing 50 can be reduced in size.

  Further, when the rotational speed R of the main shaft 20 increases, the control device 80 performs control so as to increase the fluid amount QTs at the predetermined time Ts. Thereby, the fluid is discharged from the damping additional bearing 50 in a short time. Therefore, even if the rotational speed R of the main shaft 20 is increased and the fluid is repeatedly sheared to increase the heat generation of the fluid, the fluid is discharged from the damping additional bearing 50 in a short time. Heat generation is suppressed.

  In addition, when the flow rate Q of the fluid is periodically changed, the control device 80 operates the valve body 72 so as to alternately repeat the open state and the closed state of the flow path. Thereby, the control apparatus 80 should just change the position and period P etc. which the valve body 72 act | operates, when changing the quantity QTs of the fluid in predetermined time Ts. Therefore, it is possible to easily change the fluid amount QTs at the predetermined time Ts.

  Next, a second embodiment in the present invention will be described. The second embodiment is different from the first embodiment in that a resistance detection sensor that detects a cutting resistance F during machining by a tool is provided instead of the rotation speed sensor that detects the rotation speed R of the main shaft 20 of the first embodiment. In the first embodiment, when the control device 80 periodically varies the fluid flow rate Q, the fluid amount QTs in the predetermined time Ts is changed according to the rotational speed R of the main shaft 20. Instead, in the second embodiment, when the control device 80 periodically varies the fluid flow rate Q, the fluid amount QTs at the predetermined time Ts is changed according to the cutting resistance F.

  As the resistance detection sensor, for example, a load sensor, a displacement sensor, a power consumption detector of a drive motor for a feed shaft, a supply current sensor, and the like can be applied. That is, the cutting resistance F itself can be directly detected by the load sensor, or the cutting resistance F can be indirectly detected by a displacement sensor or the like.

  The resistance detection sensor is electrically connected to the control device 80. The cutting resistance F detected by the resistance detection sensor is transmitted to the control device 80 as a detection signal. The control device 80 sets a value of the fluid flow rate Q based on the detection signal from the cutting resistance sensor, and transmits the value to the fluid supply device 60 as the control signal S. The value of the control signal S corresponding to the detection signal of the cutting force F is set in advance and stored in the storage unit. The value of the control signal S is set so that the flow rate Q increases as the cutting resistance F increases.

  Specifically, when the cutting resistance F is the first cutting resistance F1, the control device 80 transmits a first control signal S1. When the cutting force F is the second cutting force F2 that is greater than the first cutting force F1, the control device 80 transmits a second control signal S2. The operation of the spindle device 1 in the second embodiment is the same as the operation of the first embodiment described above.

  According to the present embodiment, the control device 80 performs control so as to increase the amount of fluid QTs at the predetermined time Ts when the cutting resistance F during processing by the tool increases. When the cutting resistance F during machining by the tool is increased, there is a possibility that a large vibration is generated in the main shaft 20. Therefore, before the large vibration is generated, the amount QTs of the fluid is changed, and the damping effect by the damping additional bearing 50 is enhanced, so that the main shaft 20 can be prevented from generating a large vibration.

  In the first embodiment and the second embodiment, when the control device 80 periodically changes the fluid flow rate Q, when the fluid amount QTs at the predetermined time Ts is changed, the control signal S is rectangular. Only the level L value of the shape waveform is changed. Instead, only the value of the time T of the rectangular waveform of the control signal S may be changed.

  Specifically, as shown in FIG. 6, when the rotational speed R of the main shaft 20 changes from the first rotational speed R1 to the second rotational speed R2, the control signal S changes from the first control signal S1 to the third control signal. Change to S3. The third control signal S3 has a rectangular waveform in which the level L is the first level L1 and the time T is a second time T2 (for example, 1.5 times the first time T1) longer than the first time T1. Is a control signal S that is intermittently repeated with the period P as the first period P1. Thus, while the third control signal S3 is transmitted to the fluid supply device 60, the first current value IL1 is intermittently supplied to the electromagnetic coil 74a, and the valve body 72 is in the second position X2 and the first position X1. Alternately move between and. Further, the flow rate Q is between the first flow rate Q1 and zero, the fifth damping coefficient C5 is smaller than the first damping coefficient C1, the fourth damping coefficient C4, and larger than the second damping coefficient C2. The period P is fluctuated in the first period P1.

  Further, the second predetermined time Ts2 in the present embodiment is the same time as the first period P1, since the period P is set only by the first period P1. Therefore, the fluid amount QTs3 at the second predetermined time Ts2 in the third control signal S3 is as shown in Expression (3).

[Equation 3]
QTs3 = Q1 × T2 (3)

  Here, since the second time T2 is 1.5 times the first time T1, the fluid quantity QTs3 is 1.5 times the fluid quantity QTs1. In the case of the present embodiment, when the amount of fluid QTs increases, the time for maintaining the pressure of the fluid becomes longer, so that the fluid is discharged from the damping additional bearing 50 in a short time.

  In the first embodiment and the second embodiment, when the control device 80 periodically changes the fluid flow rate Q, when the fluid amount QTs at the predetermined time Ts is changed, the control signal S is rectangular. Only the level L value of the shape waveform is changed. Instead of this, only the value of the period P of the control signal S may be changed.

  Specifically, as shown in FIG. 7, when the rotational speed R of the main shaft 20 changes from the first rotational speed R1 to the second rotational speed R2, the control signal S changes from the first control signal S1 to the fourth control signal. Change to S4. The fourth control signal S4 has a rectangular waveform in which the level L is the first level L1 and the time T is the first time T1, and the period P is shorter than the first period P1 (for example, the first period P2). The control signal S is intermittently repeated as a length of one half of P1). Thus, while the fourth control signal S4 is being transmitted to the fluid supply device 60, the first current value IL1 is intermittently supplied to the electromagnetic coil 74a, and the valve body 72 is in the second position X2 and the first position X1. Alternately move between and. Further, the flow rate Q is between the first flow rate Q1 and zero, and the damping coefficient C is the first damping coefficient C1, and the sixth damping coefficient C6 is smaller than the first damping coefficient C1 and larger than the fourth damping coefficient C4. The period P is fluctuated in the second period P2.

  In addition, the third predetermined time Ts3 in the present embodiment is the same time as the first cycle P1, since the cycle P is set to the longest time of the first cycle P1. Therefore, the fluid amount QTs4 at the third predetermined time Ts3 in the fourth control signal S4 is as shown in Expression (4).

[Equation 4]
QTs4 = Q1 × T1 × 2 (4)

  Therefore, the fluid quantity QTs4 is twice the fluid quantity QTs1. In the case of the present embodiment, when the amount of fluid QTs increases, the time for maintaining the pressure of the fluid becomes longer, so that the fluid is discharged from the damping additional bearing 50 in a short time.

  In the first embodiment and the second embodiment, the control signal S is a signal that intermittently repeats a rectangular waveform. Instead of this, as shown in FIG. 8, the signal of the control signal S may be a sine wave. Specifically, the control signal S when the rotational speed R is the first rotational speed R1 is a sine wave in which the upper limit of the level L is the first level L1, the lower limit is zero, and the period P is the first period P1. The fifth control signal S5 may be used.

  In the first embodiment and the second embodiment, the flow rate Q is adjusted by the valve 70. Instead, the flow rate Q may be adjusted by changing the pressure of the pump.

  In the first embodiment and the second embodiment, the valve 70 is provided in the fluid supply device 60. Instead of this, the main shaft device 1 may be provided with the valve 70 as a component different from the fluid supply device 60.

  DESCRIPTION OF SYMBOLS 10 ... Housing, 20 ... Main shaft, 21 ... Tool, 30 ... Motor, 50 ... Damping bearing, 60 ... Fluid supply device, 70 ... Valve, 72 ... Valve body, 80 ... Control device, F1 ... First cutting resistance, F2 ... second cutting resistance, Q1 ... first flow rate, Q2 ... second flow rate, R1 ... first rotation speed, R2 ... second rotation speed, S1 ... first control signal, S2 ... second control signal, S3 ... third Control signal, S4 ... fourth control signal, S5 ... fifth control signal, Ts1 ... first predetermined time, Ts2 ... second predetermined time, Ts3 ... third predetermined time.

Claims (4)

A housing;
A main shaft which is disposed inside the housing and holds a tool and is driven to rotate
A rolling bearing that rotatably supports the main shaft with respect to the housing;
A damping additional bearing that suppresses vibration of the main shaft , the damping additional portion being a circumferential annular gap between the inner peripheral surface of the housing and the outer peripheral surface of the main shaft, and a fluid that supplies fluid to the damping additional portion e Bei a drain for discharging the fluid from the supply path and the attenuation adding unit, the flow rate of the fluid supplied to the damping adding unit increases suppressing damping effect vibration of the main spindle with increasing attenuation added A bearing,
A fluid supply apparatus for supplying the fluid to the fluid supply path and enabling the flow rate of the fluid to be adjusted;
And a control device that periodically varies the flow rate of the fluid supplied by the fluid supply device. The spindle device according to claim 1, wherein the control device increases a flow rate of the fluid supplied by the fluid supply device in accordance with an increase in the number of rotations of the spindle. A resistance detection sensor for detecting a cutting resistance during processing by the tool;
3. The spindle device according to claim 1, wherein the control device increases a flow rate of the fluid supplied by the fluid supply device in accordance with an increase in the cutting resistance detected by the resistance detection sensor . The fluid supply device further includes a valve having a valve body that opens or closes the flow path of the fluid,
The control device periodically varies the flow rate of the fluid by repeatedly supplying the fluid every predetermined time by repeating the open state and the closed state of the fluid flow path by the valve. As well as
The spindle device according to any one of claims 1 to 3 , wherein when the flow rate of the fluid is increased, the amount of the fluid within the predetermined time is increased .

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