JP6330307B2 - Spindle device - Google Patents

Description

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

  For example, in the spindle device of a machine tool described in Patent Documents 1 to 4, the spindle is rotatably supported by a fluid bearing in addition to the rolling bearing.

JP 2000-280102 A JP 2004-106091 A JP 2002-5164 A JP 2011-235404 A

  By the way, chatter vibration due to machining can be effectively suppressed by using a damping additional bearing using a fluid. A highly viscous fluid is used for the damping additional bearing. In general, a hydrostatic bearing uses a fluid having a lower viscosity than that of a damping additional bearing because it is necessary to ensure stable rigidity (correlated with a spring constant). That is, in the damping additional bearing, the shear resistance of the fluid due to the rotation of the main shaft is greater than that of the hydrostatic bearing. The fluid is repeatedly sheared by the rotation of the main shaft, so that the fluid generates heat. The heat generated by the fluid causes thermal displacement of the spindle, which affects machining accuracy.

  The present invention has been made in view of such circumstances, 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 fluid of the damping additional bearing.

(Claim 1) A main spindle device according to the present means suppresses vibration of the main spindle by holding a tool and rotating the main spindle, a bearing that rotatably supports the main spindle, and a fluid. A damping additional bearing, a fluid supply device for supplying the fluid to the damping additional bearing and adjusting the flow rate of the fluid, a first temperature sensor for detecting the temperature of the fluid discharged from the damping additional bearing, A second temperature sensor for detecting a temperature of the fluid supplied from the fluid supply device to the damping additional bearing; an exhaust temperature detected by the first temperature sensor; and a supply temperature detected by the second temperature sensor. And a control device that adjusts the flow rate of the fluid supplied by the fluid supply device based on the difference .

  Here, in the damping additional bearing, since the viscosity of the fluid is high, the temperature of the fluid rises from the supply temperature as the main shaft rotates. The damping coefficient decreases as the temperature of the fluid in the damping additional bearing increases. Further, the rate of increase in the temperature of the fluid is higher as the spindle rotation speed is higher. On the other hand, the rate of increase in the temperature of the fluid is lower as the spindle rotation speed is lower. Further, as the flow rate of the fluid passing through the damping additional bearing increases, the temperature of the fluid in the damping additional bearing acts so as to approach the supply temperature. That is, the greater the flow rate of the fluid supplied to the damping additional bearing, the higher the effect of lowering the temperature of the fluid in the damping additional bearing.

  Therefore, in the spindle device according to this means, the flow rate of the fluid supplied to the damping additional bearing is adjusted based on the temperature of the fluid discharged from the damping additional bearing (discharge temperature). The discharge temperature is approximately equal to the temperature of the fluid in the damping additional bearing. Therefore, the higher the discharge temperature, the lower the fluid temperature in the damping additional bearing by increasing the supply flow rate. As a result, even if the rotational speed of the main shaft changes, the temperature of the fluid in the damping additional bearing can be stabilized within a certain range. In other words, the damping effect within a certain range can be exhibited regardless of the rotation speed of the main shaft, so that vibration can be reliably suppressed.

A preferred embodiment of the spindle device according to this means will be described below .

  Here, the damping effect of the damping additional bearing is affected not only by the discharge temperature but also by the supply temperature. Therefore, as described above, by adjusting the flow rate Q of the fluid based on the difference between the discharge temperature and the supply temperature, the damping effect within a certain range can be exhibited, so that vibration can be reliably suppressed.

(Claim 2 ) Further, the control device may increase the flow rate of the fluid when the discharge temperature or the difference exceeds a first temperature threshold. Thereby, even if the rotational speed of the main shaft changes, the damping effect in the damping additional bearing can be stabilized within a certain range.

(Claim 3 ) Further, the control device, when the discharge temperature or the difference exceeds the first temperature threshold, and falls below a second temperature threshold smaller than the first temperature threshold, The flow rate may be decreased. Once the supply flow rate is increased, the timing for decreasing the supply flow rate is defined. Thereby, supply flow volume can be made into an appropriate quantity.

(Claim 4 ) Further, the fluid supply device may supply the fluid maintained at a constant temperature to the damping additional bearing. In this case, the change in the discharge temperature corresponds to the change in the attenuation coefficient. Therefore, it is possible to reliably adjust the attenuation coefficient by changing the supply flow rate based on the discharge temperature.

(Claim 5 ) The second temperature threshold value may be set to a value equal to or higher than the temperature of the fluid supplied from the fluid supply device to the damping additional bearing. Since the discharge temperature does not fall below the supply temperature, it is possible to prevent the supply flow rate from becoming too low by setting the second temperature threshold to a value equal to or higher than the supply temperature.

(Claim 6) The spindle device according to this means suppresses vibration of the spindle by holding a tool and rotating the spindle, a bearing that rotatably supports the spindle, and a fluid. A damping additional bearing, a fluid supply device for supplying the fluid to the damping additional bearing and adjusting the flow rate of the fluid, a first temperature sensor for detecting the temperature of the fluid discharged from the damping additional bearing, a second temperature sensor for detecting the temperature of the fluid supplied to the damping additional bearing from the fluid supply apparatus, the supply temperature detected by the first temperature wherein the second temperature sensor and contact discharge temperature detected by the sensor And a controller that increases the flow rate of the fluid supplied by the fluid supply device when the attenuation coefficient equivalent value is less than a first coefficient threshold value.
Here, in the damping additional bearing, since the viscosity of the fluid is high, the temperature of the fluid rises from the supply temperature as the main shaft rotates. The damping coefficient decreases as the temperature of the fluid in the damping additional bearing increases. Further, the rate of increase in the temperature of the fluid is higher as the spindle rotation speed is higher. On the other hand, the rate of increase in the temperature of the fluid is lower as the spindle rotation speed is lower. Further, as the flow rate of the fluid passing through the damping additional bearing increases, the temperature of the fluid in the damping additional bearing acts so as to approach the supply temperature. That is, the greater the flow rate of the fluid supplied to the damping additional bearing, the higher the effect of lowering the temperature of the fluid in the damping additional bearing.
Therefore, in the spindle device according to this means, the flow rate of the fluid supplied to the damping additional bearing based on the temperature of the fluid discharged from the damping additional bearing (discharge temperature) and the supply temperature detected by the second temperature sensor. Increase. The discharge temperature is approximately equal to the temperature of the fluid in the damping additional bearing. Therefore, the higher the discharge temperature, the lower the fluid temperature in the damping additional bearing by increasing the supply flow rate. As a result, even if the rotational speed of the main shaft changes, the temperature of the fluid in the damping additional bearing can be stabilized within a certain range. In other words, the damping effect within a certain range can be exhibited regardless of the rotation speed of the main shaft, so that vibration can be reliably suppressed.

  Here, the damping coefficient in the damping additional bearing can be calculated from the supply temperature and discharge temperature of the fluid. In other words, by increasing the fluid flow rate when the damping coefficient equivalent value is below the first coefficient threshold value, the damping effect can be reliably stabilized within a certain range even if the rotational speed of the main shaft changes.

A preferred embodiment of the spindle device according to this means will be described below.
(Claim 7 ) Further, the control device, when the attenuation coefficient equivalent value falls below the first coefficient threshold value, and the attenuation coefficient equivalent value exceeds a second coefficient threshold value greater than the first coefficient threshold value. In addition, the flow rate of the fluid may be decreased. Once the supply flow rate is increased, the timing for decreasing the supply flow rate is defined. Thereby, supply flow volume can be made into an appropriate quantity.

(Claim 8 ) Further, the control device may set the flow rate supplied by the fluid supply device to be equal to or lower than a preset upper limit value. If a large amount of fluid is not supplied, other measures must be taken if the temperature of the fluid in the damping additional bearing does not decrease. Therefore, it is preferable to set an upper limit value and adjust the flow rate in a range equal to or lower than the upper limit value.

(Claim 9 ) Further, the control device may set the flow rate supplied by the fluid supply device to a predetermined lower limit value or more. If the supply flow rate is set to zero when the fluid temperature does not rise, then the fluid temperature rises. In this case, the supply flow rate increases from the zero state. However, when the flow rate increases from zero, the attenuation effect is less stable than when the flow rate increases from a non-zero state. Therefore, it is preferable to set a lower limit value of the supply flow rate and adjust the flow rate in a range equal to or higher than the lower limit value.

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 a flowchart of the flow volume adjustment process performed with the control apparatus shown in FIG. In the spindle apparatus shown in FIG. 1, when the rotational speed of the spindle is changed as shown in (a) and the fluid supply flow rate is not adjusted as shown in (b), the fluid is discharged from the damping additional bearing. The temperature is shown in (c), and the attenuation coefficient equivalent value is shown in (d). When the flow rate adjustment process shown in FIG. 3 is executed when the rotational speed of the main shaft is changed as shown in FIG. 3A, the supply flow rate to the damping additional bearing is shown in FIG. The discharge temperature of the fluid is shown in (c), and the damping coefficient equivalent value is shown in (d). It is sectional drawing of the axial direction of the main axis | shaft apparatus in 2nd embodiment of this invention. It is a flowchart of the flow volume adjustment process performed with the control apparatus in 3rd embodiment of this invention. It is a flowchart of the attenuation coefficient calculation process performed with the control apparatus in 4th embodiment of this invention.

Hereinafter, a first embodiment in which the spindle device 1 of the present invention is embodied will be described with reference to the drawings.
<First embodiment>
(1. Configuration of spindle device)
As shown in FIG. 1, the spindle device 1 includes a housing 10, a spindle 20, a motor 30, a plurality of rolling bearings 41 to 44, a damping additional bearing 50, a fluid supply device 60, a first temperature sensor 71, and a control device 80. I have.

  The housing 10 is formed in a hollow cylindrical shape, and holds the main shaft 20 therein. The main shaft 20 is rotationally driven by a motor 30, and a tool 21 is held on the tip end side (left side in FIG. 1) of the main shaft 20. 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.

  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 (for example, oil) is supplied. The damping additional bearing 50 mainly exhibits a damping effect and is different from a bearing for securing support rigidity like a hydrostatic bearing. That is, in the spindle device 1, the rolling bearings 41 to 44 function as a part for ensuring the supporting rigidity, whereas the damping additional bearing 50 functions as a part for improving the damping performance.

  The damping additional bearing 50 is provided closer to the tool 21 than the rolling bearings 41 to 44. Therefore, the damping additional bearing 50 effectively suppresses the vibration of the tool 21 generated by machining. 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 an annular gap in the circumferential direction with the outer circumferential surface of the main shaft 20 among the inner circumferential surface of the damping addition bearing 50. In addition, you may make it the intermittent addition part 51 form an intermittent recess in the circumferential direction. By supplying the fluid to the damping adding portion 51, a damping effect for suppressing the vibration of the main shaft 20 is exhibited.

  A fluid supply device 60 is connected to one end of the fluid supply path 52. 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 formed in the circumferential direction of the inner peripheral surface of the damping additional bearing 50.

  The drain 53 is formed by an annular groove over the entire circumference in the circumferential direction of the inner peripheral surface of the damping additional bearing 50, and from the drain annular groove 53 a and the outlet 52 a provided closer to the tool 21 than the outlet 52 a of the fluid supply path 52. Is also provided with a drain annular groove 53 b provided on the opposite side of the tool 21. The fluid is introduced from the damping addition portion 51 into the drain 53 through the drain annular grooves 53 a and 53 b, and the fluid is led to a tank (not shown) that stores the fluid through the drain 53.

  The air supply annular groove 54 is formed by an annular concave groove over the entire circumference in the circumferential direction of the inner peripheral surface of the damping additional bearing 50, and the air annular groove 54a and the drain disposed closer to the tool 21 than the drain annular groove 53a. It is comprised by the air annular groove 54b arrange | positioned on the opposite side of the tool 21 rather than the annular groove 53b. 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. The fluid supply device 60 includes a pump that sucks and discharges fluid from a tank, and a flow rate adjusting valve that adjusts a flow rate of supplying fluid discharged from the pump to the damping additional bearing 50 side. The flow rate adjustment by the fluid supply device 60 is performed by adjusting the flow rate by the flow rate adjustment valve. The flow rate supplied from the fluid supply device 60 to the damping additional bearing 50 can also be adjusted by adjusting the discharge pressure by the pump.

  The 1st temperature sensor 71 is arrange | positioned in the position close | similar to the drain annular grooves 53a and 53b among the flow paths connected to a tank from the drain annular grooves 53a and 53b. The first temperature sensor 71 detects the temperature Tout (discharge temperature) of the fluid discharged from the attenuation adding unit 51.

  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 adjusts the flow rate Q of the fluid that the fluid supply device 60 supplies to the damping additional bearing 50 based on the discharge temperature Tout detected by the first temperature sensor 71. Specifically, the control device 80 sets a value of the flow rate Q based on the discharge temperature Tout, and transmits the value to the fluid supply device 60 as a control signal.

(2. Explanation of damping effect by damping additional bearing)
The attenuation effect exhibited by the attenuation adding unit 51 will be described. In order for the damping addition part 51 to exhibit a high damping effect, the fluid supplied to the damping addition bearing 50 is higher in viscosity than a general hydrostatic bearing. The fluid in the attenuation adding portion 51 exists between the inner peripheral surface of the attenuation adding portion 51 and the outer peripheral surface of the main shaft 20. That is, as the main shaft 20 rotates, the fluid generates heat by being sheared. In particular, since the viscosity is high, the calorific value is increased.

  That is, as the main shaft 20 rotates, the temperature T of the fluid in the attenuation adding unit 51 increases from the supply temperature Tin. As the temperature T of the fluid in the attenuation adding unit 51 is higher, the attenuation coefficient by the attenuation adding unit 51 becomes lower, and the attenuation effect becomes smaller. As described above, the attenuation effect of the attenuation adding unit 51 changes according to the fluid temperature T in the attenuation adding unit 51.

  Moreover, the rate of increase of the temperature T of the fluid is higher as the rotational speed of the main shaft 20 is higher. On the other hand, the lower the rotational speed of the main shaft 20, the lower the increase rate of the fluid temperature T. Therefore, when the fluid supply temperature Tin and the fluid supply flow rate Q are constant, the damping effect of the damping adding portion 51 becomes smaller as the rotational speed of the main shaft 20 is higher.

  Further, as the flow rate of the fluid passing through the attenuation adding unit 51 increases, the temperature T of the fluid in the attenuation adding unit 51 acts so as to approach the supply temperature Tin. That is, as the flow rate Q of the fluid supplied to the attenuation adding unit 51 is increased, the effect of lowering the temperature T of the fluid in the attenuation adding unit 51 becomes higher.

  Accordingly, when the fluid temperature T in the damping addition unit 51 rises due to an increase in the rotational speed of the main shaft 20, if the flow rate Q of the fluid supplied to the damping addition unit 51 is increased, a certain range of damping effect is obtained. Can be demonstrated.

(3. Flow rate adjustment processing by the control device)
The flow rate adjustment processing by the control device 80 will be described with reference to FIG. The control device 80 adjusts the flow rate Q based on the discharge temperature Tout detected by the first temperature sensor 71. At this time, the control device 80 adjusts the supply flow rate Q within a range of preset lower limit value Qmin and upper limit value Qmax.

  When the current flow rate Q is equal to the lower limit value Qmin (S1: Y) and the discharge temperature Tout is equal to or lower than the first temperature threshold Tht1 (S2: N), the control device 80 maintains the current flow rate Q. On the other hand, when the discharge temperature Tout is higher than the first temperature threshold Tht1 (S2: Y), the control device 80 increases the flow rate Q (S3).

  Further, when the current flow rate Q is larger than the lower limit value Qmin and smaller than the upper limit value Qmax (S1: N, S4: Y), and the discharge temperature Tout is higher than the first temperature threshold value Tht1 (S5: Y). The control device 80 increases the flow rate Q (S6). On the other hand, when the discharge temperature Tout is equal to or lower than the first temperature threshold Tht1 (S5: N) and the discharge temperature Tout is lower than the second temperature threshold Tht2 (S7: Y), the control device 80 sets the flow rate Q to Decrease (S8). In addition, when the discharge temperature Tout is equal to or lower than the first temperature threshold Tht1 (S5: N) and is equal to or higher than the second temperature threshold Tht2 (S7: N), the control device 80 maintains the current flow rate Q. . Here, the second temperature threshold value Tht2 is a value smaller than the first temperature threshold value Tht1.

  When the current flow rate Q is equal to the upper limit value Qmax (S4: N) and the discharge temperature Tout is higher than the first temperature threshold Tht1 (S9: Y), the rotation of the main shaft 20 is stopped (S10). On the other hand, when the discharge temperature Tout is equal to or lower than the first temperature threshold Tht1 (S9: N) and the discharge temperature Tout is lower than the second temperature threshold Tht2 (S11: Y), the control device 80 sets the flow rate Q to Decrease (S12). Further, when the discharge temperature Tout is equal to or lower than the first temperature threshold Tht1 (S9: N) and is equal to or higher than the second temperature threshold Tht2 (S11: N), the control device 80 maintains the current flow rate Q. .

  That is, when the discharge temperature Tout exceeds the first temperature threshold Tht1 (S2, S5), the flow rate Q is increased (S3, S6). However, even when the discharge temperature Tout exceeds the first temperature threshold Tht1, if the flow rate Q is the upper limit value Qmax (S9), the rotation of the spindle 20 is stopped instead of increasing the flow rate Q. (S10). If the discharge temperature Tout falls below the second temperature threshold Tht2 after the discharge temperature Tout exceeds the first temperature threshold Tht1 (S7, S11), the flow rate Q is decreased (S8, S12).

(4. Comparison of damping effect)
Next, as described above, the damping effect is compared between the case where the flow rate Q is adjusted by the control device 80 and the case where the flow rate Q is not adjusted. For ease of explanation, the case where the flow rate Q is kept constant without being adjusted will be described with reference to FIG. 4, and then the case where the flow rate Q is adjusted will be described with reference to FIG.

  As shown in FIG. 4A, a case where the rotational speed of the main shaft 20 is changed from zero → N1 → N3 → N4 → zero will be described as an example. Here, the relationship is N1> N2> N3> zero. At this time, as shown in FIG. 4B, the flow rate Q supplied to the damping additional bearing 50 is kept at the lower limit value Qmin.

  Prior to time T1, since the fluid does not generate heat in the attenuation adding unit 51, the discharge temperature Tout becomes equal to the supply temperature Tin. When the rotational speed of the main shaft 20 increases to N1 at time T1, the fluid in the attenuation adding portion 51 generates heat, and thus the discharge temperature Tout increases as shown in FIG. When the rotational speed of the main shaft 20 decreases from N1 to N3 at time T2, the discharge temperature Tout decreases. Subsequently, when the rotational speed of the main shaft 20 increases from N3 to N2 at time T3, the discharge temperature Tout increases again. When the rotational speed of the main shaft 20 becomes zero at time T4, the discharge temperature Tout becomes equal to the supply temperature Tin again.

  When the discharge temperature Tout changes as described above, the attenuation coefficient equivalent value Ca changes as shown in FIG. Here, the attenuation coefficient equivalent value Ca is a value corresponding to an actual attenuation coefficient and obtained by calculation. The attenuation coefficient equivalent value Ca is calculated from the pressure distribution in the attenuation adding unit 51 and the viscosity of the fluid in the attenuation adding unit 51. The viscosity of the fluid in the attenuation adding unit 51 is calculated by the supply temperature Tin and the discharge temperature Tout.

  As shown in FIG. 4D, the attenuation coefficient equivalent value Ca shows a behavior in which the discharge temperature Tout is inverted because the supply temperature Tin is constant. That is, the attenuation coefficient equivalent value Ca decreases at time T1, increases at time T2, decreases again at time T3, and increases at time T4.

  As described above, when the flow rate Q supplied to the attenuation adding unit 51 is constant, when the rotation speed of the main shaft 20 changes, the attenuation coefficient equivalent value Ca changes. That is, when the rotational speed of the main shaft 20 changes, the attenuation effect changes.

  Next, a case where the above-described processing is performed by the control device 80 will be described with reference to FIG. FIG. 5A is the same as FIG. Immediately after time T1 in FIG. 5C, the discharge temperature Tout exceeds the first temperature threshold Tht1, so that the flow rate Q increases as shown in FIG. 5B. Immediately after the increase in the flow rate Q, the discharge temperature Tout once decreases, but again exceeds the first temperature threshold Tht1. Therefore, the flow rate Q further increases. Immediately thereafter, the flow rate Q is further increased and reaches the upper limit value Qmax. Thereafter, since the discharge temperature Tout is equal to or lower than the first temperature threshold Tht1 and equal to or higher than the second temperature threshold Tht2 until time T2, the flow rate Q maintains the upper limit value Qmax.

  Subsequently, immediately after time T2, the discharge temperature Tout becomes lower than the second temperature threshold Tht2 as the rotational speed of the main shaft 20 decreases. Then, the flow rate Q decreases by one step. Immediately after the decrease in the flow rate Q, the discharge temperature Tout once increases, but again falls below the second temperature threshold Tht2. Therefore, the flow rate Q further decreases. Thereafter, until the time T3, the discharge temperature Tout is equal to or lower than the first temperature threshold Tht1 and equal to or higher than the second temperature threshold Tht2, so the flow rate Q is maintained.

  Subsequently, immediately after time T3, the discharge temperature Tout becomes higher than the first temperature threshold Tht1 as the rotational speed of the main shaft 20 increases. Then, the flow rate Q increases by one step. Thereafter, until the time T4, the discharge temperature Tout is equal to or lower than the first temperature threshold Tht1 and equal to or higher than the second temperature threshold Tht2, so the flow rate Q is maintained.

  Subsequently, immediately after time T4, the rotational speed of the main shaft 20 becomes zero, so that the discharge temperature Tout becomes lower than the second temperature threshold Tht2. Then, the flow rate Q decreases by one step, and the discharge temperature Tout is lower than the second temperature threshold Tht2 even after that, so the flow rate Q becomes the lower limit value Qmin.

  By increasing the flow rate Q to be supplied as the discharge temperature Tout is higher, the temperature T of the fluid in the attenuation adding unit 51 can be lowered. Then, as shown in FIG. 5C, assuming that the rotation speed of the main shaft 20 has changed, the discharge temperature Tout is stabilized within a certain range. Therefore, the temperature T of the fluid in the attenuation adding unit 51 can be stabilized within a certain range. In other words, the damping effect within a certain range can be exhibited regardless of the rotational speed of the main shaft 20, so that vibration can be reliably suppressed.

  In particular, as described above, when the discharge temperature Tout exceeds the first temperature threshold value Tht1, the above-described effect can be obtained easily and reliably by increasing the fluid flow rate Q. Here, the fluid supply device 60 supplies the fluid maintained at a constant temperature Tin to the damping additional bearing 50. Therefore, even when the flow rate Q is adjusted using the discharge temperature Tout, the attenuation coefficient can be reliably adjusted within a certain range.

  In addition, after the discharge temperature Tout exceeds the first temperature threshold Tht1, the fluid flow rate Q is decreased when it falls below the second temperature threshold Tht2. That is, the timing for reducing the supply flow rate Q is defined. Thereby, the flow volume Q to supply can be made into an appropriate quantity.

  Further, the control device 80 sets the flow rate Q supplied by the fluid supply device 60 to be equal to or lower than a preset upper limit value Qmax. If a large amount of fluid is not supplied, it is necessary to take other means if the temperature T of the fluid in the damping additional bearing 50 does not decrease. In the present embodiment, the main shaft 20 is stopped in the above case.

  Further, the control device 80 sets the flow rate Q supplied by the fluid supply device 60 to be equal to or higher than a preset lower limit value Qmin. If the supply flow rate Q is set to zero when the fluid temperature T does not rise, then the fluid temperature T rises thereafter. In this case, the supply flow rate Q increases from a zero state. However, when the flow rate Q increases from zero, the damping effect is less stable than when the flow rate Q increases from a non-zero state. Therefore, by setting the lower limit value Qmin of the supply flow rate Q, the damping effect can be stabilized.

  The second temperature threshold Tht2 is set to a value equal to or higher than the temperature Tin of the fluid supplied from the fluid supply device 60 to the damping additional bearing 50. Since the discharge temperature Tout does not fall below the supply temperature Tin, the supply flow rate Q can be prevented from becoming too low by setting the second temperature threshold Tht2 to a value equal to or higher than the supply temperature Tin.

<Second embodiment>
In the above embodiment, the flow rate Q is increased when the discharge temperature Tout is higher than the first temperature threshold Tht1, and the flow rate Q is decreased when the discharge temperature Tout is lower than the second temperature threshold Tht2. In addition, the discharge temperature Tout can be replaced with a difference ΔT between the discharge temperature Tout and the supply temperature Tin. In this case, the first temperature threshold value Tht1 and the second temperature threshold value Tht2 are replaced with values corresponding to the difference ΔT between the discharge temperature Tout and the supply temperature Tin.

  In this case, the spindle device 1 according to the second embodiment detects the temperature Tin (supply temperature) of the fluid that the fluid supply device 60 supplies to the damping additional bearing 50 with respect to the spindle device 1 according to the first embodiment. A temperature sensor 72 is provided. In FIG. 6, the same components as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Accordingly, a difference ΔT between the discharge temperature Tout detected by the first temperature sensor 71 and the supply temperature Tin detected by the second temperature sensor 72 is calculated, and the difference Δ and the first temperature threshold Tht1 or the second temperature threshold are calculated. The flow rate Q is adjusted by comparing with Tht2. Thereby, there exists an effect similar to 1st embodiment.

<Third embodiment>
Next, the flow rate adjustment process executed by the control device 80 in the third embodiment will be described with reference to FIG.

  The control device 80 calculates an attenuation coefficient equivalent value Ca based on the discharge temperature Tout detected by the first temperature sensor 71. As described above, the attenuation coefficient equivalent value Ca is calculated based on the pressure distribution in the attenuation adding unit 51 and the viscosity of the fluid in the attenuation adding unit 51. The viscosity of the fluid in the attenuation adding unit 51 is calculated by the supply temperature Tin and the discharge temperature Tout. However, in the present embodiment, since the supply temperature Tin is maintained at a constant temperature, the attenuation coefficient equivalent value Ca can be calculated based on the discharge temperature Tout. Then, the control device 80 adjusts the flow rate Q based on the calculated attenuation coefficient equivalent value Ca.

  Here, the processing uses the first coefficient threshold value Thc1 and the second coefficient threshold value Thc2, and these Thc1 and Thc2 are shown in FIG. The second coefficient threshold Thc2 is larger than the first coefficient threshold Thc1.

  When the current flow rate Q is equal to the lower limit value Qmin (S21: Y) and the attenuation coefficient equivalent value Ca is greater than or equal to the first coefficient threshold value Thc1 (S22: N), the control device 80 maintains the current flow rate Q. . On the other hand, when the attenuation coefficient equivalent value Ca is smaller than the first coefficient threshold value Thc1 (S22: Y), the control device 80 increases the flow rate Q (S23).

  Further, when the current flow rate Q is larger than the lower limit value Qmin and smaller than the upper limit value Qmax (S21: N, S24: Y), and the attenuation coefficient equivalent value Ca is smaller than the first coefficient threshold value Thc1, (S25: Y), the control device 80 increases the flow rate Q (S26). On the other hand, if the attenuation coefficient equivalent value Ca is equal to or greater than the first coefficient threshold value Thc1 (S25: N) and the attenuation coefficient equivalent value Ca is greater than the second coefficient threshold value Thc2 (S27: Y), the control device 80 The flow rate Q is decreased (S28). When the attenuation coefficient equivalent value Ca is equal to or greater than the first coefficient threshold value Thc1 (S25: N) and further equal to or less than the second coefficient threshold value Thc2 (S27: N), the control device 80 sets the current flow rate Q to maintain.

  Further, when the current flow rate Q is equal to the upper limit value Qmax (S24: N) and the damping coefficient equivalent value Ca is smaller than the first coefficient threshold value Thc1 (S29: Y), the rotation of the spindle 20 is stopped (S30). . On the other hand, when the attenuation coefficient equivalent value Ca is equal to or greater than the first coefficient threshold value Thc1 (S29: N) and the attenuation coefficient equivalent value Ca is greater than the second coefficient threshold value Thc2 (S31: Y), the control device 80 The flow rate Q is decreased (S32). When the attenuation coefficient equivalent value Ca is equal to or greater than the first coefficient threshold Thc1 (S29: N) and further equal to or less than the second coefficient threshold Thc2 (S31: N), the control device 80 sets the current flow rate Q to maintain.

  That is, when the attenuation coefficient equivalent value Ca falls below the first coefficient threshold value Thc1 (S22, S25), the flow rate Q is increased (S23, S26). However, even when the damping coefficient equivalent value Ca is less than the first coefficient threshold value Thc1, if the flow rate Q is the upper limit value Qmax (S29), the rotation of the spindle 20 is not increased, but the flow rate Q is not increased. Stop (S30). If the attenuation coefficient equivalent value Ca exceeds the second coefficient threshold value Thc2 after the attenuation coefficient equivalent value Ca falls below the first coefficient threshold value Thc1 (S27, S31), the flow rate Q is decreased (S28, S31). S32).

  When the control device 80 performs the above processing, the behavior shown in FIG. That is, the same effect as the first embodiment is obtained.

<Fourth embodiment>
Next, the spindle device 1 in the fourth embodiment is the same as the spindle device 1 in the second embodiment shown in FIG. That is, the spindle device 1 includes a second temperature sensor 72 that detects the temperature Tin (supply temperature) of the fluid that the fluid supply device 60 supplies to the damping additional bearing 50 with respect to the spindle device 1 in the first embodiment.

  In this case, as shown in FIG. 8, the control device 80 acquires the discharge temperature Tout detected by the first temperature sensor 71 and the supply temperature Tin detected by the second temperature sensor 72 (S41). Subsequently, the control device 80 calculates an attenuation coefficient equivalent value Ca based on the discharge temperature Tout and the supply temperature Tin (S42). Then, as described in the third embodiment, the control device 80 adjusts the supplied flow rate Q by using the calculated attenuation coefficient equivalent value Ca.

  When the supply temperature Tin changes, a value close to the actual attenuation coefficient can be obtained by calculating the attenuation coefficient equivalent value Ca using the detected supply temperature Tin. Since the flow rate Q is adjusted using the calculated attenuation coefficient equivalent value Ca, the attenuation coefficient can be stabilized more reliably. That is, a more stable attenuation effect can be obtained.

1: spindle device, 20: spindle, 21: tool, 41-44: rolling bearing, 50: damping addition bearing, 51: damping addition section, 52: fluid supply path, 53: drain, 60: fluid supply device, 71: First temperature sensor 72: Second temperature sensor 80: Control device Ca: Decay coefficient equivalent value Q: Supply flow rate Qmax: Upper limit value Qmin: Lower limit value Tin: Supply temperature Tout: Discharge temperature Tht1 : First temperature threshold value, Tht2: Second temperature threshold value, Thc1: First coefficient threshold value, Thc2: Second coefficient threshold value

Claims (9)

A spindle that holds the tool and is driven to rotate;
A bearing that rotatably supports the main shaft;
A damping additional bearing that suppresses vibration of the main shaft by being supplied with fluid;
A fluid supply device for supplying the fluid to the damping additional bearing and making the flow rate of the fluid adjustable;
A first temperature sensor for detecting the temperature of the fluid discharged from the damping additional bearing;
A second temperature sensor for detecting the temperature of the fluid supplied from the fluid supply device to the damping additional bearing;
A control device for adjusting the flow rate of the fluid supplied by the fluid supply device based on the difference between the discharge temperature detected by the first temperature sensor and the supply temperature detected by the second temperature sensor ;
A spindle device comprising: The spindle device according to claim 1, wherein the control device increases the flow rate of the fluid when the discharge temperature or the difference exceeds a first temperature threshold. The control device decreases the flow rate of the fluid when the discharge temperature or the difference falls below a second temperature threshold smaller than the first temperature threshold after the discharge temperature or the difference exceeds the first temperature threshold. 2. The spindle device according to 2 . The spindle device according to claim 2 or 3 , wherein the fluid supply device supplies the fluid maintained at a constant temperature to the damping additional bearing. 4. The spindle device according to claim 3 , wherein the second temperature threshold is set to a value equal to or higher than a temperature of a fluid supplied from the fluid supply device to the damping additional bearing. A spindle that holds the tool and is driven to rotate;
A bearing that rotatably supports the main shaft;
A damping additional bearing that suppresses vibration of the main shaft by being supplied with fluid;
A fluid supply device for supplying the fluid to the damping additional bearing and making the flow rate of the fluid adjustable;
A first temperature sensor for detecting the temperature of the fluid discharged from the damping additional bearing;
A second temperature sensor for detecting the temperature of the fluid supplied from the fluid supply device to the damping additional bearing ;
Wherein calculating an attenuation factor equivalent value based on the supply temperature detected by the first temperature wherein the second temperature sensor and contact discharge temperature detected by the sensor, when the attenuation coefficient corresponding value is below the first coefficient threshold A control device for increasing the flow rate of the fluid supplied by the fluid supply device ;
A spindle device comprising: When the damping coefficient equivalent value exceeds a second coefficient threshold value greater than the first coefficient threshold value after the damping coefficient equivalent value falls below the first coefficient threshold value, the control device controls the flow rate of the fluid. The spindle apparatus according to claim 6 , which is reduced. The spindle device according to any one of claims 1 to 7 , wherein the control device sets a flow rate supplied by the fluid supply device to a preset upper limit value or less. The spindle device according to any one of claims 1 to 8 , wherein the control device sets a flow rate supplied by the fluid supply device to a predetermined lower limit value or more.

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