JP2015217496A - Main spindle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a main spindle that can reduce machining error of a workpiece caused by anisotropy of rigidity of a machine tool or of the workpiece.SOLUTION: A main spindle device 5 is provided in which, a first X-direction adjusting part 81, a first Y-direction adjusting part 82, a second X-direction adjusting part 83 and a second Y-direction adjusting part 84 of a numerical control device 8 control a first X-direction adjusting valve 61, a first Y-direction adjusting valve 62, a second X-direction adjusting valve 63 and a second Y-direction adjusting valve 64 respectively to thereby change rigidity of a machine tool 1 or of a workpiece W through a damping addition bearing 50. This allows the numerical value control device 8 to reduce amounts of deviation of an actual machining position relative to an ideal machining position in the workpiece W caused by anisotropy of the rigidity to thereby improve machining accuracy of the workpiece W.

Description

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

  For example, Patent Document 1 discloses a main shaft device that includes a rolling bearing that supports a main shaft and a damping additional bearing that has a damping coefficient larger than that of the rolling bearing and suppresses vibration of the main shaft. In Patent Document 2, a plurality of oil discharge openings are provided in the circumferential direction of the cylindrical inner peripheral surface of the housing that supports the main shaft, and the pressure and amount of oil supplied to each oil discharge opening are controlled to control the main shaft. A spindle device for suppressing vibration is disclosed.

JP 2014-637 A JP 2011-235404 A

  In general, the rigidity of the machine tool component including the spindle device, the support rigidity between the machine tool components, and the rigidity of the workpiece processed by the machine tool are determined in a plane perpendicular to the rotation axis of the spindle. Each has anisotropy. That is, the machine tool component itself and the workpiece itself have rigidity anisotropy depending on the shape, material, etc., and the machine tool components differ in rigidity due to misalignment of the components. Has a direction.

  In machining a workpiece, due to the rigidity anisotropy, the deviation amount of the actual machining position from the ideal machining position on the workpiece in the plane perpendicular to the rotation axis of the spindle is the machining load direction, that is, the spindle axis. When it differs according to the direction of the total load combined at the time of machining on a plane perpendicular to the rotation axis, there is a problem that the machining accuracy of the workpiece is deteriorated. The ideal machining position on the workpiece is an actual machining position when there is no rigidity anisotropy.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a spindle device that can reduce a machining error of a workpiece caused by anisotropy of rigidity of a machine tool or a workpiece.

  (Claim 1) A spindle device according to the present means is a spindle device of a machine tool comprising: a spindle that is driven to rotate by holding a rotary tool; and a bearing that rotatably supports the spindle. Is provided on the rotary tool side, and three or more pockets are provided at intervals in the circumferential direction on the inner circumference of the cylinder, and fluid is supplied to the pockets to add damping to the main shaft. A damping additional bearing for rotatably supporting the shaft, an adjusting means for adjusting at least one of a pressure and an amount of the fluid supplied to each pocket to change a damping force and a supporting force with respect to the main shaft, and the machine tool Or, due to the rigidity anisotropy of the workpiece, the deviation of the actual machining position with respect to the ideal machining position of the workpiece varies depending on the machining load direction. And a control means for controlling said adjusting means Te.

  The control means can change the rigidity of the machine tool or the workpiece through the damping additional bearing by controlling the adjusting means. Therefore, the control means can reduce the deviation amount of the actual machining position with respect to the ideal machining position in the workpiece due to the rigidity anisotropy, and can improve the machining accuracy of the workpiece.

(Claim 2) Further, the control means causes a deviation of an actual machining position with respect to an ideal machining position in the workpiece due to anisotropy of rigidity of at least one of the machine tool components. When the amount varies depending on the machining load direction, the adjusting means may be controlled according to the machining load direction.
Thereby, the control means can reduce the amount of misalignment even if the structure itself has rigidity anisotropy due to the shape and material of the structure of the machine tool, and can improve the processing accuracy of the workpiece.

(Claim 3) Further, the control means has a deviation amount of an actual machining position with respect to an ideal machining position in the workpiece due to anisotropy of a support rigidity between components of the machine tool. When it differs according to, it is good to control the said adjustment means according to the said process load direction.
As a result, the control means can reduce the amount of positional deviation even if there is rigidity anisotropy between the components due to misalignment between the components of the machine tool, and can improve the machining accuracy of the workpiece.

(Claim 4) Further, the control means is configured so that the amount of deviation according to the machining load direction is applied to the machine tool or the workpiece when the load is actually applied to the machine tool or the workpiece. It may be obtained and stored in advance by measuring the amount of displacement or by analyzing the amount of displacement of the machine tool or the workpiece when a load is applied to the model of the machine tool or the workpiece. .
Thereby, the control means can easily execute the control reflecting the accurate amount of positional deviation.

(Claim 5) Moreover, the said control means is good to obtain | require and memorize | store the said deviation | shift amount according to the said process load direction previously by a process result.
Thereby, the control means can easily execute the control reflecting the deviation amount in accordance with the actual machining.

(Claim 6) Further, the control means may process the workpiece by controlling the adjusting means so that a cross section of the workpiece orthogonal to the rotation axis of the main shaft is elliptical.
Thereby, the control means can process an elliptical hole or the like which is difficult to process with high accuracy.

1 is a schematic view of a machine tool to which a spindle device of an embodiment of the present invention is attached. It is sectional drawing of the axial direction of the main axis | shaft apparatus of FIG. FIG. 3 is a cross-sectional view of the damping additional bearing of the spindle device of FIG. 2 viewed from the axial direction and a block diagram of the numerical control device. It is a flowchart for demonstrating operation | movement of the numerical control apparatus of FIG. 3 in the case of processing a perfect circle hole. It is a flowchart for demonstrating operation | movement of the numerical control apparatus of FIG. 3 in the case of processing an elliptical hole. It is the figure which looked at the amount of position shift of the actual processing position with respect to the ideal processing position in the work piece resulting from the rigidity anisotropy of the machine tool from the axial direction of the work piece. It is the figure which looked at the processing state of the perfect hole used as the reference | standard of the elliptical hole when processing an elliptical hole in a workpiece from the axial direction of the workpiece. It is the figure which looked at the to-be-processed object from the axial direction in order to demonstrate the processing method when processing an elliptical hole from the perfect circular hole used as a reference | standard. It is the figure which looked at the processing state of the elliptical hole processed into a workpiece from the axial direction of the workpiece. It is a figure which shows the relationship of the processing amount with respect to the phase of a perfect circle hole when machining an elliptical hole from a perfect circle hole.

(Schematic configuration of machine tool)
Hereinafter, a machine tool to which a spindle device of an embodiment of the present invention is attached will be described with reference to the drawings. As a machine tool, a three-axis machining center will be described as an example. That is, the machine tool is a machine tool having three rectilinear axes (X, Y, Z axes) orthogonal to each other as drive axes. In FIG. 3, the right direction in the drawing is referred to as the X + direction, the left direction in the drawing is referred to as the X− direction, the upward direction in the drawing is referred to as the Y + direction, and the downward direction in the drawing is referred to as the Y− direction.

As shown in FIG. 1, the machine tool 1 includes a bed 2, a column 3, a saddle 4, a spindle device 5, a table 6, a numerical control device 8, and the like.
The bed 2 is installed on the floor, and has a pair of rails 11 extending on the top surface in the X-axis direction (horizontal direction) and a pair of rails extending in the Z-axis direction (horizontal direction) orthogonal to the X-axis direction. 12 is provided.

The column 3 is engaged with a pair of rails 11 so as to be movable in the X-axis direction with respect to the bed 2 by an unillustrated X-axis motor. A pair of rails 13 extending in the X-axis direction and the Y-axis direction (vertical direction) orthogonal to the Z-axis direction are provided on the front side surface of the column 3.
The saddle 4 is engaged with a pair of rails 13 so as to be movable in the Y-axis direction with respect to the column 3 by an unillustrated Y-axis motor.

The spindle device 5 is provided on the saddle 4 so as to protrude in the Z-axis direction. The spindle device 5 supports the spindle 20 (see FIG. 2) so as to be rotatable around an axis by a built-in spindle motor 30 (see FIG. 2). The rotary tool 7 is held at the tip of the main shaft 20 and rotates as the main shaft 20 rotates. The rotary tool 7 moves in the X-axis direction and the Y-axis direction with respect to the bed 2 as the column 3 and the saddle 4 move. The rotating tool 7 is, for example, a ball end mill, an end mill, a drill, or a tap.
The table 6 is engaged with a pair of rails 12 so as to be movable in the Z-axis direction with respect to the bed 2 by a Z-axis motor (not shown). A workpiece W is fixed to the upper surface of the table 6 by a clamping device (not shown).

  The numerical control device 8 drives and controls the spindle motor 30 to rotate the rotary tool 7 based on the numerical control data, and drives and controls the axis motors of the column 3, the saddle 4 and the table 6. The rotary tool 7 is relatively moved with respect to the actuator, and the pump 72 (see FIG. 2) of the fluid supply device 70 is driven and controlled, and the first X-direction adjusting valve 61, the first Y-direction adjusting valve 62, and the second X-direction. The workpiece W is processed by adjusting and controlling the adjustment valve 63 and the second Y-direction adjustment valve 64 (see FIGS. 2 and 3). Each adjustment valve 61-64 is equivalent to the "adjustment means" of this invention. The adjustment control of each of the adjustment valves 61 to 64 will be described later.

(Schematic configuration of spindle device)
A schematic configuration of the above spindle device 5 will be described with reference to the drawings.
As shown in FIGS. 2 and 3, the spindle device 5 includes a housing 10, a spindle 20, a spindle motor 30, a plurality of rolling bearings 41 to 44, a damping additional bearing 50, and a first X-direction adjusting valve 61. The first Y-direction adjusting valve 62, the second X-direction adjusting valve 63, the second Y-direction adjusting valve 64, the fluid supply device 70, and the like.

  The housing 10 is formed in a hollow cylindrical shape, and holds the main shaft 20 therein. The main shaft 20 holds the rotary tool 7 on the tip side (left side in FIG. 2) and is driven to rotate by a main shaft motor 30. The main shaft 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 rotatably support the main shaft 20 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 rotary tool 7 than the spindle motor 30. On the other hand, the rolling bearing 44 is a roller bearing, for example, and is arranged on the opposite side (rear end side) of the rotary tool 7 from the spindle motor 30. That is, the rolling bearings 41 to 44 are arranged so as to sandwich the spindle motor 30 at the center in the axial direction.

  The damping additional bearing 50 is a hydrostatic bearing made of a fluid such as oil, for example, and is disposed further on the rotating tool 7 side than the rolling bearing 41 located on the most rotating tool 7 side. The damping additional bearing 50 is a plurality of pockets for generating static pressure at regular intervals in the circumferential direction on the cylindrical inner periphery 50a, in this example, four first Xs arranged in a cross shape in the X and Y directions. A direction pocket 51, a first Y direction pocket 52, a second X direction pocket 53, and a second Y direction pocket 54 are provided.

  That is, the first X-direction pocket 51 is disposed on the X-direction side with respect to the main shaft 20, the first Y-direction pocket 52 is disposed on the Y-direction side with respect to the main shaft 20, and the second X-direction pocket 53 is The second Y-direction pocket 54 is disposed on the Y + direction side with respect to the main shaft 20. The damping additional bearing 50 rotatably supports the main shaft 20 while applying damping to the main shaft 20 by supplying fluid to the pockets 51 to 54.

  The first X-direction adjusting valve 61, the first Y-direction adjusting valve 62, the second X-direction adjusting valve 63, and the second Y-direction adjusting valve 64 are a first X-direction pocket 51, a first Y-direction pocket 52, and a second X-direction. Connected to the direction pocket 53 and the second Y-direction pocket 54, respectively. Each of the adjustment valves 61 to 64 is a valve capable of adjusting the pressure and amount of the fluid supplied to each of the pockets 51 to 54, and changes the damping force and the support force with respect to the main shaft 20 (in the “adjustment means” of the present invention). Equivalent to).

  The fluid supply device 70 includes a storage tank 71, a pump 72 connected to the storage tank 71, and the like. The storage tank 71 stores a fluid to be supplied to the pockets 51 to 54. The pump 72 is connected to the regulating valves 61 to 64 and supplies a fluid from the storage tank 71 to the regulating valves 61 to 64.

(Schematic configuration of numerical controller)
A schematic configuration of the numerical controller 8 will be described with reference to the drawings.
As illustrated in FIG. 3, the numerical control device 8 includes a first X direction adjustment unit 81, a first Y direction adjustment unit 82, a second X direction adjustment unit 83, a second Y direction adjustment unit 84, and a storage. Unit 85, a processing control unit 86, and the like. Each adjustment part 81-84 is corresponded to the "control means" of this invention.

  Here, as described in the background art, generally, the components (for example, the column 3 and the bed 2) of the machine tool 1 including the spindle device 5 itself and the components (for example, the spindle 20) of the machine tool 1 are included. The workpiece W itself machined by the machine tool 1 has rigidity anisotropy in a plane perpendicular to the rotation axis of the main shaft 20. In the processing of the workpiece W, due to the rigidity anisotropy, the deviation amount of the actual machining position with respect to the ideal machining position in the workpiece W on the plane perpendicular to the rotation axis of the main shaft 20 (hereinafter, When the “positional displacement amount” is simply different depending on the machining load direction, there is a problem that the machining accuracy of the workpiece W is deteriorated.

  Therefore, in the spindle device 5 of the present embodiment, each stiffness is changed in a direction to improve the machining accuracy of the workpiece W, that is, the positional deviation amount corresponding to the machining load direction is canceled by canceling the rigidity anisotropy. To improve the processing accuracy of the workpiece W, the damping additional bearing 50 having the first X-direction pocket 51, the first Y-direction pocket 52, the second X-direction pocket 53, and the second Y-direction pocket 54, The first X-direction adjusting valve 61, the first Y-direction adjusting valve 62, the second X-direction adjusting valve 63, the second Y-direction adjusting valve 64, and the adjusting valves 61 to 64 that supply fluid to the pockets 51 to 54 are provided. A first X-direction adjusting unit 81, a first Y-direction adjusting unit 82, a second X-direction adjusting unit 83, and a second Y-direction adjusting unit 84 that perform adjustment control are provided.

  The storage unit 85 includes a displacement amount corresponding to the machining load direction due to the rigidity anisotropy of the component itself of the machine tool 1, and the pressures of the adjustment valves 61 to 64 for reducing the displacement amount. The amount of misalignment corresponding to the machining load direction caused by the rigidity anisotropy between the components of the table and the machine tool 1, and the pressure of each adjustment valve 61 to 64 for reducing the amount of misalignment Table, the amount of displacement according to the processing load direction due to the rigidity anisotropy of the workpiece W itself, and the pressure and amount of each adjustment valve 61 to 64 for reducing the amount of displacement And other numerical control data including machining data necessary for machining the workpiece W are stored.

  The amount of displacement according to the machining load direction is determined by actually measuring the amount of displacement of the machine tool 1 or the workpiece W when a load is actually applied to the machine tool 1 or the workpiece W, or the machine tool 1 or It is obtained in advance by analyzing the amount of displacement of the machine tool 1 or the workpiece W when a load is applied to the model of the workpiece W. Thereby, the numerical control device 8 can easily execute the control reflecting the positional deviation amount according to the accurate machining load direction. Further, the amount of displacement according to the machining load direction is obtained in advance by measuring the machining result, that is, the dimensional accuracy of the workpiece W after the trial machining. As a result, the numerical control device 8 can easily execute control that reflects the amount of displacement according to the machining load direction in accordance with actual machining. For example, the displacement amount is actually measured by a known hammering method or a method using a load cell. The amount of displacement is analyzed by, for example, a known finite element structure analysis method. The pressure and amount of each of the regulating valves 61 to 64 for reducing the amount of displacement are obtained in advance by experiments.

  Each adjustment part 81-84 reads and analyzes numerical control data from the memory | storage part 85, drives and controls the pump 72 of the fluid supply apparatus 70, adjusts and controls each adjustment valve 61-64, respectively, and each pocket 51-54. The pressure or amount of the fluid to be supplied to is set to cancel the rigidity anisotropy and reduce the amount of misalignment according to the machining load direction. Since the damping additional bearing 50 is disposed on the rotating tool 7 side further than the rolling bearing 41 positioned closest to the rotating tool 7 side, the adjusting units 81 to 84 adjust and control the adjusting valves 61 to 64, respectively. By setting the pressure or amount of the fluid supplied to each of the pockets 51 to 54, the offset and inclination of the main shaft 20 can be canceled.

  The machining control unit 86 reads and analyzes numerical control data from the storage unit 85, drives and controls the spindle motor 30 to rotate the rotary tool 7, and drives and controls the axis motors of the column 3, the saddle 4 and the table 6. Then, the rotary tool 7 is moved relative to the workpiece W to process the workpiece W.

(Machine tool machining operations)
First, the operation in the case of machining a perfect hole with the machine tool 1 described above will be described. For example, as shown in FIG. 5, when a hole Ha having a perfectly circular cross section perpendicular to the rotation axis of the main shaft 20 is trial-processed, the rigidity of the column 3 itself among the components of the machine tool 1 is anisotropic. In addition, it is assumed that the center point C of the perfect hole Ha is displaced from the rotation center 20a of the main shaft 20 by Δxw in the X + direction and Δyw in the Y + direction.

  First, the numerical controller 8 cancels the rigidity anisotropy of the column 3 itself among the components of the machine tool 1 (step S1 in FIG. 4A). Specifically, the first and second X-direction adjusting units 81 and 83 include the positional deviation amount corresponding to the machining load direction caused by the rigidity anisotropy of the column 3 itself stored in the storage unit 85, and With reference to a table of pressures and amounts of the adjustment valves 61 to 64 for reducing the displacement amount, the first X-direction adjustment valve 61 is adjusted and controlled to reduce the displacement amount Δxw in the X + direction. While reducing the pressure and amount of the first X-direction pocket 51, the second X-direction adjusting valve 63 is adjusted and controlled to increase the pressure and amount of the second X-direction pocket 53.

  Further, the first and second Y-direction adjusting units 82 adjust and control the first Y-direction adjusting valve 62 to reduce the pressure and amount of the first Y-direction pocket 52 in order to reduce the displacement amount Δyw in the Y + direction. At the same time, the second Y-direction adjusting valve 64 is adjusted and controlled to increase the pressure and amount of the second Y-direction pocket 54. Thereby, the numerical controller 8 can cancel the rigidity anisotropy of the column 3 itself.

  Then, the numerical control device 8 processes a perfect hole Ha on the workpiece W (step S2 in FIG. 4A). Specifically, the machining control unit 86 drives and controls the spindle motor 30 to rotate the rotary tool 7 and machine the column 3, the saddle 4 and the table to machine the perfect hole Ha into the workpiece W. The rotary tool 7 is moved relative to the workpiece W by driving and controlling the motors 6. Then, the numerical controller 8 continues the processing until the processing of the perfect hole Ha is completed (Steps S3 and S2 in FIG. 4A), and when the processing of the perfect hole Ha is completed, all the processes are finished. In this case, since the rigidity anisotropy of the column 3 itself has been canceled, the numerical controller 8 can make the center point C of the perfectly circular hole Ha substantially coincide with the rotation center 20a of the main shaft 20, A perfectly circular hole Ha can be machined with high accuracy.

  Next, an operation in the case of machining an elliptical hole with the machine tool 1 in which the rigidity anisotropy of the column 3 itself is canceled will be described. For example, as shown in FIG. 8, a case where an elliptical hole H3 having a cross section perpendicular to the rotation axis of the main shaft 20 having a major axis a and a minor axis b is machined into a workpiece W will be described with reference to the drawings.

  The numerical controller 8 processes a perfect hole H1 (see FIG. 6) serving as a reference for the elliptical hole H3 in the workpiece W (step S1 in FIG. 4B). Specifically, as shown in FIG. 6, the machining control unit 86 is configured to process a perfect hole H1 having a diameter c (<b) in a cross section perpendicular to the rotation axis of the main shaft 20 into the workpiece W. The spindle motor 30 is driven and controlled to rotate the rotary tool 7, and the axis motors of the column 3, saddle 4 and table 6 are driven and controlled to move the rotary tool 7 relative to the workpiece W. In this case, since the rigidity anisotropy of the column 3 itself is canceled, the perfect hole H1 can be processed with high accuracy.

  Next, the numerical controller 8 processes the elliptical hole H3 based on the perfect hole H1 (step S2 in FIG. 4B). Specifically, when the processing of the perfect hole H1 is completed, the processing control unit 86, as shown in FIG. 7, has a cross section perpendicular to the rotation axis of the main shaft 20 with a diameter b with respect to the perfect hole H1. In order to machine the round hole H2 into the workpiece W, the spindle motor 30 is driven and controlled to rotate the rotary tool 7, and the axis motors of the column 3, saddle 4 and table 6 are driven and controlled. The rotary tool 7 is moved relative to the workpiece W. At the same time, the first and second X-direction adjusting units 81 and 82 are elliptical in shape with a cross section orthogonal to the rotation axis of the main shaft 20 having a major axis a and a minor axis b when machining the perfect hole H2 by the machining control unit 86. In order to process the hole H3 into the workpiece W, the rigidity of the main shaft 20 is changed.

  That is, as shown in FIG. 7, the machining amount gradually increases as the machining point in the X direction when machining the perfect hole H1 moves from 0 degrees to 90 degrees in the perfect hole H1. The first X-direction adjusting unit 81 adjusts and controls the first X-direction adjusting valve 61 to gradually lower the pressure and amount of the first X-direction pocket 51, and the second X-direction adjusting unit 83 The X direction adjustment valve 63 is adjusted and controlled to gradually increase the pressure and amount of the second X direction pocket 53. As shown in FIG. 9, if the phase of the perfect hole H1 increases from (bc) / 2 to (ac) / 2 between 0 degrees and 90 degrees, the final processing amount is as shown in FIG. Therefore, the gradually increasing amount of processing may be changed, for example, like a similar curve G1 of the elliptical hole H3.

  Then, as shown in FIG. 7, the machining amount gradually decreases as the machining point in the X direction during machining of the perfect hole H1 moves from the phase 90 degrees of the perfect hole H1 to 180 degrees. The first X-direction adjusting unit 81 adjusts and controls the first X-direction adjusting valve 61 to gradually increase the pressure and amount of the first X-direction pocket 51, and the second X-direction adjusting unit 83 The pressure and amount of the second X-direction pocket 53 are gradually lowered by adjusting and controlling the X-direction adjusting valve 63. As shown in FIG. 9, if the phase of the perfect hole H1 is reduced from (ac) / 2 to (bc) / 2 between 90 degrees and 180 degrees as shown in FIG. Therefore, the amount of processing that gradually decreases may be changed like a curve G2 having a similar shape of the elliptical hole H3.

  Thereafter, the first and second X-direction adjusting parts 81 and 82 move the X-direction machining point from the phase 180 degrees of the perfect hole H1 to 270 degrees, and the phase 0 degree of the perfect hole H1 described above. The same control as when moving from 90 degrees to 90 degrees is performed, and as the machining point in the X direction moves from 270 degrees to 360 degrees (0 degrees) of the hole H1 in a perfect circle, the phase from 90 degrees to 180 degrees of the hole H1 described above. The same control is performed as when moving every time.

  Then, the numerical control device 8 continues the processing until the processing of the elliptical hole H3 is completed (steps S3 and S2 in FIG. 4B). As shown in FIG. The process ends. Specifically, the machining control unit 86, the first X-direction adjusting unit 81, and the second X-direction adjusting unit 83 continue the above-described machining control until the X-direction diameter reaches a and the Y-direction diameter reaches b. When the diameter in the X direction reaches a and the diameter in the Y direction reaches b, the machining control ends. As described above, an elliptical hole H3 having a major axis a and a minor axis b in the cross section perpendicular to the rotation axis of the main shaft 20 is processed in the workpiece W with high accuracy.

As described above, the first X direction adjusting unit 81, the first Y direction adjusting unit 82, the second X direction adjusting unit 83, and the second Y direction adjusting unit 84 of the numerical controller 8 are the first X direction adjusting valve 61. The rigidity of the machine tool 1 or the workpiece W is changed via the damping additional bearing 50 by controlling the first Y direction adjusting valve 62, the second X direction adjusting valve 63, and the second Y direction adjusting valve 64, respectively. it can. Therefore, the numerical control device 8 can reduce the deviation amount of the actual machining position with respect to the ideal machining position in the workpiece W due to the rigidity anisotropy, and can improve the machining accuracy of the workpiece W.
In addition, in the above-mentioned embodiment, although the damping addition bearing 50 was set as the structure which has the four pockets 51-54, the same effect will be acquired if it is a damping addition bearing which has three or more pockets.

  DESCRIPTION OF SYMBOLS 1 ... Machine tool, 5 ... Main shaft apparatus, 7 ... Rotary tool, 8 ... Numerical control apparatus, 20 ... Main shaft, 41-44 ... Rolling bearing, 50 ... Damping addition bearing, 50a ... Cylindrical inner periphery, 51 ... First X direction Pocket, 52 ... first Y-direction pocket, 53 ... second X-direction pocket, 54 ... second Y-direction pocket, 61 ... first X-direction adjustment valve, 62 ... first Y-direction adjustment valve, 63 ... second X-direction Adjustment valve, 64 ... second Y direction adjustment valve, 70 ... fluid supply device, 81 ... first X direction adjustment unit, 82 ... first Y direction adjustment unit, 83 ... second X direction adjustment unit, 84 ... second Y Direction adjustment unit, 85 ... storage unit, 86 ... processing control unit.

Claims (6)

A spindle driven to rotate while holding a rotating tool;
A bearing that rotatably supports the main shaft;
In the spindle device of a machine tool equipped with
Three or more pockets are provided on the rotary tool side of the bearing and spaced circumferentially on the inner periphery of the cylinder, and fluid is supplied to the pockets to add damping to the main shaft. And a damping additional bearing that rotatably supports the main shaft,
Adjusting means for adjusting at least one of the pressure and the amount of the fluid supplied to each pocket to change the damping force and the supporting force with respect to the main shaft;
Due to the anisotropy of the rigidity of the machine tool or workpiece, if the amount of deviation of the actual machining position from the ideal machining position on the workpiece differs depending on the machining load direction, Control means for controlling the adjusting means;
A spindle device comprising:   The control means is configured so that a deviation amount of an actual machining position with respect to an ideal machining position in the workpiece depends on a machining load direction due to anisotropy of rigidity of at least one of the machine tool components. 2. The spindle device according to claim 1, wherein the adjusting unit is controlled in accordance with the machining load direction when the machining load directions differ.   When the amount of deviation of the actual machining position with respect to the ideal machining position in the workpiece differs depending on the machining load direction due to the anisotropy of the support rigidity between the components of the machine tool, 3. The spindle device according to claim 1, wherein the adjusting unit is controlled according to the machining load direction.   The control means measures the displacement amount according to the machining load direction by actually measuring the displacement amount of the machine tool or the workpiece when a load is actually applied to the machine tool or the workpiece. Or any one of claims 1 to 3 which is obtained and stored in advance by analyzing a displacement amount of the machine tool or the workpiece when a load is applied to a model of the machine tool or the workpiece. A spindle device according to claim 1.   The spindle device according to any one of claims 1 to 3, wherein the control unit obtains and stores the deviation amount according to the machining load direction in advance based on a machining result.   The said control means controls the said adjustment means, and processes the said workpiece so that the cross section of the said workpiece orthogonal to the rotating shaft line of the said main axis | shaft may become elliptical. The spindle device according to one item.

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