JP2006167823A - Spindle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle device, machining with high accuracy by restraining vibration of a spindle. <P>SOLUTION: A discharge port of a supply passage 101a is connected to a peripheral groove 101c in a main housing 101A, and a discharge port of a supply passage 101b is connected to a peripheral groove 101d in a sub-housing 101B, so that even if the section of the main housing 101A, the sub-housing 101B or the spindle 102 is not a complete round, the peripheral grooves 101c, 101d serve as a temporary storage area where the air supplied from the supply passages 101a, 101b is substantially uniform in pressure over the whole periphery, thereby restraining a sudden change in pressure regardless of the positional relationship between static pressure clearance and the discharge port due to rotation. Thus, a change in pressure applied to the outer peripheral surface of the spindle 102 is held down to restrain run-out and vibration. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a spindle device, and more particularly to a spindle device suitable for use in a machine tool capable of high-precision machining.

  Conventionally, in this type of spindle device, the rotation of the main shaft is supported by a rolling bearing represented by a ball bearing or a roller bearing, or a static pressure bearing using a static pressure of a working fluid represented by oil or air. It was common.

  Here, in the spindle device using the rolling bearing, since the ball or roller rolls between the inner and outer rings, there is no particular problem at low speed rotation, but vibration and frictional heat are generated at high speed rotation. Problems such as spindle run-out and heat generation occurred. In addition, it is necessary to lubricate the rolling surfaces of the inner and outer rings, which increases the running cost and takes time and effort for maintenance.

On the other hand, since the hydrostatic bearing supports the shaft by the hydrostatic pressure of the fluid, the spindle device using the hydrostatic bearing (see Patent Document 1) has an advantage that high rotational accuracy can be expected as compared with the one using the rolling bearing. Therefore, the hydrostatic bearing is suitable for use in a processing machine that processes the transfer optical surface of the optical element molding die that molds the optical surface of the optical element.
Japanese Unexamined Patent Publication No. 7-19236

  However, in the case of a spindle device using a hydrostatic bearing, there are the following problems when the shape accuracy of the main shaft or the housing covering it is poor. That is, when the outer shape of the main shaft or the inner shape of the housing is not a perfect circle, or when the main shaft or the housing is warped, the clearance between the main shaft and the housing (referred to as a static pressure clearance) becomes uneven in the circumferential direction. In the hydrostatic bearing, for example, the supporting force of the main shaft is obtained by sending fluid into the hydrostatic skimmer from an external fluid supply source via a supply passage provided in the housing. When facing the discharge port of the supply passage, the fluid pressure locally increases. Conversely, when a region having a large static pressure gap faces the discharge port of the supply passage, the fluid pressure locally decreases. That is, as the main shaft rotates, a pressure change locally occurs on the outer periphery of the main shaft, thereby causing vibration and vibration on the main shaft. If the vibration or vibration occurs, the workpiece or tool attached to the vibration is vibrated, and high-precision machining becomes difficult.

Further, in a grindstone spindle used for grinding or a tool spindle used for fly cutting, the rotation speed of the spindle usually exceeds 10,000 min ⁻¹ . Therefore, in such a high-speed rotation specification, the mass of the spindle is made as small as possible. This is important in order to reduce the size and cost of a processing machine to which the spindle device is attached by synergistic effects by miniaturizing the drive motor to reduce power consumption and heat generation. However, when the spindle is reduced in size by reducing the mass of the spindle, the spindle unit using the hydrostatic bearing reduces the area of the hydrostatic bearing, and the rigidity suddenly decreases. Vibrations and vibrations are generated. In such a case, high-precision processing becomes difficult.

  The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a spindle apparatus that can perform high-precision machining while suppressing vibration of the main shaft.

The spindle apparatus according to claim 1, wherein the spindle apparatus includes a main shaft that is driven and rotated by a driving unit, a housing that is disposed around the main shaft, and a hydrostatic bearing that rotatably supports the main shaft.
The housing has a supply passage for supplying a fluid supplied from a fluid supply source between the main shaft and the housing, and the hydrostatic bearing is supplied with the fluid, so that the fluid is supplied to the housing. Supporting the main shaft,
A recess connected to the supply passage is provided in at least one of the outer peripheral surface of the main shaft and the inner peripheral surface of the housing, and the opening cross-sectional area of the recess is larger than the minimum cross-sectional area of the supply passage. To do.

  The principle of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view in the direction perpendicular to the axis showing an example of a spindle apparatus according to the present invention. In FIG. 1, the housing H that covers the main shaft S is provided with supply passages P extending radially inward from the outer periphery thereof at three equal intervals in the circumferential direction. The supply passage P is connected to a positive pressure pump P that is an external fluid supply source, and receives pressurized air from the supply passage P through a pipe. On the inner peripheral surface of the housing H, recesses CV connected to the supply passages P are formed. The recess CV faces the outer peripheral surface of the main shaft S. The opening cross-sectional area of the recess CV (referring to the area of the open region) is larger than the minimum cross-sectional area of the supply passage P.

  Here, it is assumed that the outer peripheral surface of the main shaft S is not a perfect circle. Then, as is apparent from FIG. 1 that exaggerates the non-circular cross-sectional state, the static pressure clearance between the main shaft S and the housing H changes in the circumferential direction. In this case, if the concave portion CV is not provided, the fluid pressure locally increases when a region where the static pressure gap is small faces the discharge port of the supply passage P (the upper supply passage in FIG. 1). When the region where the static pressure gap is large is opposed to the discharge port of the supply passage P (left and right supply passages in FIG. 1), the fluid pressure locally decreases.

  On the other hand, according to the present invention, since the inner end of the supply passage P is connected to the recess CV, when the region where the static pressure clearance is small faces the supply passage P (the upper supply passage in FIG. 1), the recess The air supplied from the supply passage P becomes a temporary accumulation region of substantially uniform pressure over the entire circumference, and the pressure suddenly fluctuates regardless of the positional relationship between the static pressure gap and the discharge port accompanying rotation. It can suppress, the pressure fluctuation given to the outer peripheral surface of the main spindle S can be suppressed, and the shake and vibration can be suppressed.

  Here, the hydrostatic bearing is supported in a non-contact state by supplying a pressurized fluid to a gap defined between the surface of the main shaft and the surface of the housing facing the main shaft. Say what you do. In addition, the “concave portion connected to the supply passage” means that when the concave portion is formed in the housing, the concave portion is directly connected to the supply passage, and the concave portion is formed in the main shaft. , Which is directly connected to the supply passage through a gap between the housing and the main shaft.

  In addition, as a fluid used in the present invention (including the following invention), any medium that can generate a static pressure can be used regardless of liquid or gas. Air is more preferable because it can be used at low cost. The supply passage may be provided on the main shaft side. Further, it is possible to rotate the housing side and fix the main shaft.

  According to a second aspect of the present invention, the spindle device according to the first aspect is characterized in that the recess is formed on an inner peripheral surface of the housing. When the concave portion is formed on the inner peripheral surface of the housing, a relative position with respect to the supply passage provided in the housing can be appropriately set.

  According to a third aspect of the present invention, in the spindle device according to the second aspect, a plurality of shallow grooves extending in the axial direction are formed on the outer peripheral surface of the main shaft side by side in the circumferential direction. And

  FIG. 2 is a schematic partial sectional perspective view showing an example of the spindle device of the present invention. In FIG. 2, three supply passages P are formed in two rows at equal intervals in the circumferential direction on the inner peripheral surface of the housing H (only two are shown), and the inner ends of the supply passages P arranged in the circumferential direction are It is connected to a recess CV which is a circumferential groove. A plurality of shallow grooves G extending in the axial direction are formed on the outer peripheral surface of the main shaft S at equal intervals in the circumferential direction. The shallow groove G partially overlaps with the supply passage when viewed in the radial direction. More specifically, the shallow groove G is formed such that both ends thereof are positioned outward in the axial direction with respect to the supply passages P arranged in at least two rows.

  If the bearing clearance between the main shaft S and the housing H is small, the static pressure is uneven in the region close to and far from the supply passage P in the axial direction, and it may be difficult to obtain sufficient support rigidity. On the other hand, when the bearing clearance is increased, the nonuniformity of the static pressure is eliminated, but the static pressure itself is lowered and sufficient support rigidity cannot be obtained. On the other hand, according to the present invention, the fluid flowing out from the supply passage P can be uniformly distributed via the shallow groove G extending in the axial direction, thereby increasing the static pressure in the region far from the supply passage P. Thus, the support rigidity can be increased. Further, when the shallow grooves G are formed on the outer peripheral surface of the main shaft S at equal intervals in the circumferential direction, the static pressure clearance in the region facing the discharge port of the supply passage P periodically changes as the main shaft S rotates. However, since the concave portion CV is provided as described above, it is possible to suppress fluctuations in pressure applied to the outer peripheral surface of the main shaft S and to suppress the vibration and vibration.

  According to a fourth aspect of the present invention, in the spindle device according to the third aspect, the shallow groove has a herringbone shape.

  FIG. 3 is a schematic partial sectional perspective view showing an example of the spindle device of the present invention. 3, three supply passages P are formed in two rows at equal intervals in the circumferential direction on the inner peripheral surface of the housing H (only two are shown), and the inner ends of the supply passages P arranged in the circumferential direction are: It is connected to a recess CV which is a circumferential groove. On the outer peripheral surface of the main shaft S, a plurality of herringbone-shaped shallow grooves (a part of a spiral groove, but a pair of twisted grooves in opposite directions) G are formed at equal intervals in the circumferential direction. . The shallow groove G is formed such that both ends thereof are positioned outward in the axial direction with respect to the supply passages P arranged in at least two rows.

  According to the present invention, in addition to the effects described above with reference to FIG. 2, in addition to the effects described above with reference to FIG. Thus, the support rigidity can be further increased. By the way, in order to obtain the dynamic pressure effect of the herringbone, the rotation of the spindle S is limited to one direction (see FIG. 3). For example, in a grindstone spindle used for grinding or a tool spindle used for fly cutting, Since there is a directionality, the rotation direction is usually determined, so that in these applications, there is no problem that the rotation direction is limited.

  According to a fifth aspect of the present invention, the spindle device according to the first aspect is characterized in that the recess is formed on an outer peripheral surface of the main shaft. By forming the concave portion on the outer peripheral surface of the main shaft, processing becomes easy.

  The spindle device according to a sixth aspect is characterized in that, in the invention according to any one of the first to fifth aspects, the concave portion is a circumferential groove extending in a circumferential direction. If the concave portion is a circumferential groove, continuous processing can be performed, so that processing becomes easier. Also, to suppress the static pressure fluctuation caused by the rotation of the main shaft, the fluid pressure is almost uniform around the circumference, and even if the static pressure gap fluctuates, the pressure fluctuation does not occur around the discharge port. Some are more advantageous.

  A spindle device according to a seventh aspect is the invention according to any one of the first to sixth aspects, wherein a plurality of the supply passages are provided apart in the axial direction, and the fluid supplied from the supply passage is adjacent to the supply passage. In this case, it flows out between the outer peripheral surface of the main shaft and the inner peripheral surface of the housing on the side opposite to the supply passage.

  Referring to FIG. 2, a part of the fluid supplied from the supply passages P arranged in the axial direction is directed between them, and when a fluid discharge path is provided between the supply passages P, the fluid flows from there. Since it leaks out, there exists a possibility that a static pressure may fall as it leaves | separates from the supply channel | path P. FIG. On the other hand, if a discharge path is not provided between the supply passages P arranged in the axial direction, the supplied fluid is separated from the outer peripheral surface of the main shaft on the side opposite to the supply passage adjacent to the supply passage as in the present invention. Since it only flows out to the outside through the space between the inner peripheral surface of the housing, the static pressure does not decrease between the supply passages P, and the support rigidity can be increased.

The spindle apparatus according to claim 8, wherein the spindle apparatus includes a main shaft that is driven and rotated by a driving unit, a housing that is disposed around the main shaft, and a hydrostatic bearing that rotatably supports the main shaft.
The housing has a supply passage for supplying a fluid supplied from a fluid supply source between the main shaft and the housing, and the hydrostatic bearing is supplied with the fluid, so that the fluid is supplied to the housing. Supporting the main shaft,
A recess connected to the supply passage is provided on at least one of the surface facing the axial direction of the main shaft and the surface facing the axial direction of the housing facing the axial direction. It is characterized by being larger than the minimum cross-sectional area of the passage.

  In the first aspect of the present invention, the present invention is applied to a radial hydrostatic bearing. However, a similar effect is obtained in the thrust hydrostatic bearing as in the eighth aspect of the present invention. It can also be obtained by applying to. More specifically, the end of the supply passage is connected to the recess, so that when the region where the static pressure clearance is small is opposed to the supply passage, the air supplied from the supply passage to the recess is all around. It becomes a temporary accumulation area of almost uniform pressure over a wide range, and it is possible to suppress sudden fluctuations in pressure regardless of the positional relationship between the static pressure gap and the discharge port due to rotation, so that the axial direction of the main shaft can be reduced. The fluctuation in pressure applied to the facing surface can be suppressed, and the vibration and vibration can be suppressed. The “surface facing the axial direction of the main shaft” is preferably a flange surface because a wide static pressure area can be secured.

  A spindle device according to a ninth aspect is characterized in that, in the invention according to the eighth aspect, the concave portion is formed on a surface of the housing facing the axial direction. When the concave portion is formed on a surface facing the axial direction of the housing, a relative position with respect to the supply passage provided in the housing can be appropriately set.

  According to a tenth aspect of the present invention, in the spindle device according to the ninth aspect, a plurality of shallow grooves extending in the radial direction are formed side by side in the circumferential direction on the surface of the main shaft facing the axial direction. It is characterized by being.

  According to the present invention, the fluid flowing out from the supply passage can be evenly distributed through the shallow groove extending in the radial direction, thereby increasing the static pressure in a region far from the supply passage, thereby supporting rigidity. Can be increased. Further, when the shallow grooves are formed at equal intervals in the circumferential direction on the surface of the main shaft facing the axial direction, the static pressure gap in the region facing the discharge port of the supply passage periodically changes. Since the concave portion is provided as described above, the fluctuation in pressure applied to the outer peripheral surface of the main shaft can be suppressed, and the vibration and vibration can be suppressed.

  According to an eleventh aspect of the present invention, in the invention according to the tenth aspect, the shallow groove has a herringbone shape.

  According to the present invention, in addition to the above-described effects, in addition to the rotation of the main shaft, by providing dynamic pressure between the supply passages arranged in the axial direction by the herringbone-shaped shallow grooves, the support rigidity is further increased. Can be increased.

  According to a twelfth aspect of the present invention, in the invention according to the eighth aspect, the concave portion is formed on a surface facing the axial direction of the main shaft.

  According to a thirteenth aspect of the present invention, in the invention according to any one of the eighth to twelfth aspects, the concave portion is a circumferential groove extending in the circumferential direction. If the concave portion is a circumferential groove, continuous processing can be performed, so that processing becomes easier. Also, to suppress the static pressure fluctuation caused by the rotation of the main shaft, the fluid pressure is almost uniform around the circumference, and even if the static pressure gap fluctuates, the pressure fluctuation does not occur around the discharge port. Some are more advantageous.

  A spindle device according to a fourteenth aspect is the invention according to any one of the eighth to thirteenth aspects, wherein a plurality of discharge ports of the supply passage are provided radially apart on a surface facing the axial direction. The fluid supplied from the discharge port flows out to the outside through the space between the main shaft and the housing facing the axial direction on the side opposite to the adjacent supply passage.

  Unless a discharge path is provided between the supply passages arranged in the axial direction, the supplied fluid faces the axial direction of the main shaft and the housing on the opposite side to the adjacent supply passage as in the present invention. Since it only flows out between the surfaces to the outside, the static pressure does not decrease between the supply passages, and the support rigidity can be increased.

  ADVANTAGE OF THE INVENTION According to this invention, the spindle apparatus which can suppress a vibration of a main axis | shaft and can perform a highly accurate process can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. The spindle device according to the embodiment of the present invention can be used in the two-axis turning precision machine shown in FIG. In FIG. 4, an X-axis table 2 driven in the X-axis direction by a control device (not shown) is arranged on the surface plate 1. A diamond tool 3 is mounted on the X-axis table 2 via a tool mounting portion 7. A Z-axis table 4 driven in the Z-axis direction by a control device (not shown) is disposed on the surface plate 1. On the Z-axis table 4, a drive control mechanism 6 and a spindle device SD controlled by the drive control mechanism 6 are provided. For example, the spindle M of the spindle device SD can be attached with a workpiece M of a molding die for optical elements. Using such a biaxial turning precision processing machine, the transfer optical surface of the optical element molding die can be cut with high accuracy.

  Furthermore, the spindle device according to the embodiment of the present invention can be used in the turning precision processing machine shown in FIG. In FIG. 5, an X-axis table 12 driven in the X-axis direction and a Z-axis table 14 driven in the Z-axis direction are mounted on a surface plate 11. On the X-axis table 12, a turning axis (B axis) 18 capable of turning the tool 13 is attached. On the turning axis 18, a tool mounting portion 17 is attached. A drive control mechanism 16 and a spindle device SD controlled by the drive control mechanism 16 are provided on the Z-axis table 14. For example, the spindle M of the spindle device SD can be attached with a workpiece M of a molding die for optical elements. Using such a turning precision processing machine, the transfer optical surface of the optical element molding die can be cut with high accuracy.

  Furthermore, the spindle device according to the embodiment of the present invention can be used in an ultraprecision machine having a movable stage having three orthogonal axes and a rotating mechanism for rotating a diamond tool, as shown in FIG. In FIG. 6, an X-axis table 22 driven in the X-axis direction and a Z-axis table 24 driven in the Z-axis direction are attached on the surface plate 21. A Y-axis stage 26 that is driven in the Y-axis direction is mounted on the X-axis table 22, and a spindle mechanism SD is disposed on the Y-axis stage 26, and the main axis of the rotating unit 27 that rotates the diamond tool 23. It is connected to. The rotation axis is parallel to the Z axis. A workpiece M is fixed on the Z-axis table 24.

  Furthermore, the spindle device according to the embodiment of the present invention can be used in the milling machine shown in FIG. In FIG. 7, an X-axis stage 42 that drives in the X-axis direction and a Z-axis stage 44 that drives in the Z-axis direction are mounted on a surface plate 41. A Y-axis stage 46 that drives in the Y-axis direction is mounted on the X-axis table 42, and a spindle device SD that rotates the diamond tool 43 is supported by the arm 45 on the Y-axis stage 46. Mounted on the end surface of the spindle of the spindle device SD incorporated in the arm 45 so that the tool edge comes to a position, for example, 15 mm away from the center of rotation in the radial direction, and fixed to the workpiece M fixed on the Z-axis stage 44. Then, cutting is performed in the Y-axis direction, and the diamond tool 43 is sent in the X-axis direction to perform cutting.

  FIG. 8 is a cross-sectional view of the spindle device of the present embodiment. The spindle device SD of FIG. 8 can be incorporated into, for example, the milling machine of FIG. 7, but is not limited thereto, and it goes without saying that the spindle apparatus SD can be incorporated into the machining machines of FIGS. Absent.

  In FIG. 8, a cylindrical main shaft 102 is fitted in a hollow cylindrical housing 101. Both clearances are about 10 μm. The main shaft 102 has a flange 102a near the left end in FIG. 8 and a through hole 102b in the center. The housing 101 includes a main housing 101A disposed on the right side with respect to the flange 102a, a sub housing 101B disposed on the left side with respect to the flange 102a, and the main housing 101A and the sub housing on the radially outer side of the flange 102a. The ring block 101C is formed by connecting 101C.

  The main housing 101A has a supply passage 101a having one end opened on the outer peripheral surface and connected to a positive pressure pump P + that is an external fluid supply source. The other end of the supply passage 101a opens on the inner peripheral surface of the main housing 101A so as to be opposed to the outer peripheral surface of the main shaft 102 in three rows aligned in the axial direction and at equal intervals of 120 degrees in the circumferential direction (there are (Referred to as discharge ports A, B, and C), and at the end face of the main housing 101A, facing the flange 102a, are opened at equal intervals of 120 degrees in the circumferential direction (referred to as discharge ports D). In each discharge port of the supply passage 101a, a throttle member 103 having a small hole (which defines the minimum cross-sectional area of the supply passage) is fitted. A circumferential groove (concave portion) 101c is formed on the inner peripheral surface of the main housing 101A so as to be connected to the discharge ports A, B, and C of the supply passage 101a. The main housing 101A has a cooling jacket 101f through which cooling water flows, but is not connected to the supply passage 101a.

  The sub housing 101B has a supply passage 101b having one end opened on the outer peripheral surface and connected to a positive pressure pump P + which is an external fluid supply source. The other end of the supply passage 101b opens on the inner peripheral surface of the sub-housing 101B so as to be opposed to the outer peripheral surface of the main shaft 102 in two rows aligned in the axial direction and at equal intervals of 120 degrees in the circumferential direction. Along with the discharge ports E and F), the end face of the sub-housing 101B is opposed to the flange 102a and is opened at equal intervals of 120 degrees in the circumferential direction (this is called the discharge port G). A throttle member 103 having a small hole is fitted in each discharge port of the supply passage 101b. A peripheral groove (concave portion) 101d is formed on the inner peripheral surface of the sub-housing 101B so as to be connected to the discharge ports E and F of the supply passage 101b.

  The ring housing 101C is provided with an exhaust port 101k that passes from the gap between the inner periphery of the ring housing 101 and the flange 102a of the main shaft 102 to the outer periphery.

  A motor 104, which is a driving means, is provided adjacent to the main housing 101A. The motor 104 includes a motor case 104a, a rotor 104b attached to the main shaft 102, and a coil 104c disposed radially outside the rotor 104b and disposed in the motor case 104a. Electric power is supplied to the coil 104c from the outside. By supplying, the main shaft 102 can be rotationally driven.

  A reduced diameter cylindrical portion 102 d is formed coaxially at the right end of the main shaft 102. The reduced diameter cylindrical portion 102d has an encoder plate 105b that rotates integrally with the outer periphery thereof. The encoder 105a can detect the rotation angle of the encoder plate 105b and obtain the rotation angle of the main shaft 102.

  The tip of the reduced diameter cylindrical portion 102d is inserted into the suction case 106. The suction case 106 is attached to a frame (not shown), and a circular tube porous static pressure pad 106a is disposed at the open end of the suction case 106 so as to face the reduced diameter cylindrical portion 102d. A supply passage 106c provided in the suction case 106 on the back side of the static pressure pad 106a is connected to a positive pressure pump P +, through which the outer peripheral surface of the reduced diameter cylindrical portion 102d and the inner peripheral surface of the static pressure pad 106a. Between the suction case 106 and the reduced diameter cylindrical portion 106d is avoided. The internal space of the suction case 106 communicates with the through hole 102b and the discharge port 106b of the main shaft 102 so that the air in the through hole 102b is sucked by the negative pressure pump P− connected to the discharge port 106b. It has become.

  Since the left end of the main shaft 102 is a flat surface and a bolt hole 102g is provided, the holder HD for holding the tool T can be attached using this. When the negative pressure pump P− is driven in a state where the attachment surface of the holder HD is pressed against the main shaft 102, the air in the through hole 102b is sucked through the suction case 106 and becomes negative pressure. The holder HD is fixed to the main shaft 102 by the differential pressure. At this stage, the holder HD is centered while rotating the main shaft 102. After centering the holder HD, the holder HD is fixed to the main shaft 102 by screwing the bolt BT into the bolt hole 102g. If the holder HD is fixed to the main shaft 102 using the bolt BT, even if the main shaft 102 is rotationally driven at a high speed, it does not fall off or shift due to centrifugal force or the like.

  When the spindle device SD of FIG. 8 is operated in the state of being incorporated in the milling machine of FIG. 7, the main pressure pump P + is connected to the supply passages 101a and 101b through the discharge ports A, B, C, E, and F. The main shaft 102 is supported in a non-contact state with respect to the main housing 101A and the sub-housing 101B by the air supplied to the inside of the housing 101A and the sub-housing 101B, so that it receives a radial load received from the tool T. it can. Further, the flange 102a of the main shaft 102 is made to be in the main housing 101A and the sub housing 101B by the air supplied from the positive pressure pump P + to the inside of the main housing 101A and the sub housing 101B through the discharge ports D and G of the supply passages 101a and 101b. Therefore, it is possible to receive a load in the thrust direction received from the tool T. When the motor 104 is driven in such a state, the main shaft 102 rotates. The main shaft 102 heated at the time of rotational driving is cooled by the cooling water supplied to the cooling jacket 101f, and its thermal expansion is suppressed. Further, even when the rotating main shaft 102 and the reduced diameter cylindrical portion 102d are eccentric, the reduced diameter cylindrical portion 102d and the suction case 106 are formed using the static pressure of the air discharged from the static pressure pad 106a. These gaps are maintained and are prevented from contacting each other.

  At this time, the discharge port of the supply passage 101a is connected to the circumferential groove 101c in the main housing 101A, and the discharge port of the supply passage 101b is connected to the circumferential groove 101d in the sub housing 101B. For example, the main housing 101A and the sub housing 101B Alternatively, even when the cross section of the main shaft 102 is not a perfect circle, the circumferential grooves 101c and 101d serve as a temporary accumulation region of almost uniform pressure for the air supplied from the supply passages 101a and 101b over the entire circumference, so that Regardless of the positional relationship between the pressure gap and the discharge port, it is possible to suppress rapid fluctuations in pressure, thereby suppressing pressure fluctuations applied to the outer peripheral surface of the main shaft 102 and suppressing vibrations and vibrations thereof.

  The air supplied from the supply passage 101a passes between the main shaft 102 and the main housing 101A, and flows out from the gap between the motors 104 to the outside. The air supplied from the supply passage 101b passes between the main shaft 102 and the sub housing 101B and flows out from the vicinity of the holder HD to the outside. Therefore, since no discharge path is provided between the discharge ports A, B, and C of the supply passage 101a arranged in the axial direction opened to the inner periphery and the discharge ports E and F of the supply passage 101b, the supplied fluid Only flows out between the outer peripheral surface of the main shaft 102 and the inner peripheral surfaces of the housings 101 </ b> A and 101 </ b> B, so that the static pressure does not decrease between the discharge ports and the support rigidity is increased. it can.

  FIG. 9 is a cross-sectional view showing a flange of a spindle device according to another embodiment. The present embodiment is different from the embodiment shown in FIG. 8 in that circumferential grooves (recesses) 101s and 101t arranged in the radial direction are provided on both surfaces of the flange of the main shaft 102 facing the axial direction. . Since the other points are the same as those in the above-described embodiment, the description thereof is omitted.

  More specifically, the axial end surface of the main housing 101A is opposed to the surface facing the axial direction of the flange 102a, and is opened at an equal interval of 120 degrees in the circumferential direction and aligned in the radial direction (this) Are referred to as discharge ports D and H). In each discharge port of the supply passage 101a, a throttle member 103 having a small hole (which defines the minimum cross-sectional area of the supply passage) is fitted. Two rows of circumferential grooves 101s are formed on the end surface in the axial direction of the main housing 101A so as to be connected to the discharge ports D and H of the supply passage 101a.

  At the end surface in the axial direction of the sub-housing 101B, facing the surface facing the axial direction of the flange 102a, the openings are arranged at equal intervals of 120 degrees in the circumferential direction and aligned in the radial direction (this is the discharge ports G and I). Called). A throttle member 103 having a small hole is fitted in each discharge port of the supply passage 101b. Two rows of circumferential grooves 101t are formed on the surface of the auxiliary housing 101B facing the axial direction so as to be connected to the discharge ports G and I of the supply passage 101b.

  At this time, the discharge port of the supply passage 101a is connected to the circumferential groove 101s in the main housing 101A, and the discharge port of the supply passage 101b is connected to the circumferential groove 101t in the sub housing 101B. For example, the main housing 101A and the sub housing 101B Even if the end surface of the main shaft 102 or the flange 102a of the main shaft 102 is not flat, the circumferential grooves 101s and 101t serve as a temporary accumulation region of substantially uniform pressure for the air supplied from the supply passages 101a and 101b. Abrupt fluctuations in pressure can be suppressed regardless of the positional relationship between the associated static pressure gap and the discharge port, thereby suppressing fluctuations in pressure applied to the outer peripheral surface of the main shaft 102 and suppressing fluctuations and vibrations thereof.

  The air supplied from the supply passage 101a passes between the main shaft 102 and the main housing 101A, and the air that has escaped outward in the radial direction passes through the discharge port 101k of the ring housing 101C and goes out of the radial direction. Anything that has come off flows out to the outside through a discharge port 101m that obliquely penetrates the main housing 101A. The air supplied from the supply passage 101b passes between the main shaft 102 and the sub-housing 101B, and the air that has escaped outward in the radial direction passes through the discharge port 101k of the ring housing 101C. The one that has come off flows out to the outside through the discharge port 101n that obliquely penetrates the sub housing 101B. Therefore, since no discharge path is provided between the discharge ports D and H of the supply passage 101a and the discharge ports G and I of the supply passage 101b, the supplied fluid flows between the flange surface 102a of the main shaft 102 and the housing 101A. Since it only flows out to the outside through the end face of 101B, the static pressure does not decrease between the discharge ports, and the support rigidity can be increased.

  FIG. 10 is a perspective view of a main shaft according to a modification of the present embodiment. In the present embodiment, shallow grooves RG that extend from the radially inner side to the outer side of the discharge ports D, H, G, and I of the supply passages 101a and 101b are formed on both surfaces of the main shaft 102 viewed in the axial direction of the flange 102a. These are formed at equal intervals in the circumferential direction.

  According to this modification, the air flowing out from the supply passage 101a101b (see FIG. 9) can be uniformly distributed through the shallow groove RG extending in the radial direction, whereby the discharge ports D of the supply passages 101a and 101b, By increasing the static pressure in a region far from H, G, and I, the support rigidity can be increased. In addition, when shallow grooves RG are formed at equal intervals in the circumferential direction on the surface of the main shaft 102 facing the axial direction of the flange 102a, the static pressure clearance in the regions facing the discharge ports of the supply passages 101a and 101b changes periodically. However, since the circumferential grooves 101s and 101t are provided as described above, it is possible to suppress fluctuations in pressure applied to the flange 101a of the main shaft 101 and to suppress the vibration and vibration.

  FIG. 11 is a perspective view of a main shaft according to another modification of the present embodiment. In the present embodiment, a herringbone-shaped shallow groove extending across the discharge ports D, H, G, and I of the supply passages 101a and 101b on both surfaces of the main shaft 102 viewed in the axial direction of the flange 102a. A plurality of RHBs are formed at equal intervals in the circumferential direction.

  According to this modification, in addition to the effects described above, in addition to the rotation of the main shaft 102, dynamic pressure is applied between adjacent discharge ports of the supply passages 101a and 101b arranged in the axial direction by the herringbone-shaped shallow groove RHB. By giving, support rigidity can be raised more.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, the shallow groove shown in FIGS. 2 and 3 may be provided in the spindle device of FIG.

It is a schematic sectional drawing of an axis orthogonal direction which shows an example of the spindle apparatus concerning this invention. It is a general | schematic fragmentary sectional perspective view which shows an example of the spindle apparatus of this invention. It is a general | schematic fragmentary sectional perspective view which shows an example of the spindle apparatus of this invention. It is a perspective view of a 2-axis turning precision processing machine. It is a perspective view of a turning precision processing machine. It is a perspective view of an ultraprecision machine having a movable stage with three orthogonal axes and a rotating mechanism for rotating a diamond tool. It is a perspective view of a milling machine. It is sectional drawing of the spindle apparatus of this Embodiment. It is sectional drawing of the spindle apparatus concerning another embodiment. It is a perspective view of the main axis concerning the modification of this Embodiment. It is a perspective view of the main axis concerning another modification of this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface plate 2 X-axis table 3 Diamond tool 4 Z-axis table 6 Drive control mechanism 7 Tool attachment part 11 Surface plate 12 X-axis table 13 Tool 14 Z-axis table 16 Drive control mechanism 17 Tool attachment part 18 Turning axis 21 Surface plate 22 X axis table 23 Diamond tool 24 Z axis table 26 Y axis stage 27 Rotating part 41 Surface plate 42 X axis stage 43 Diamond tool 44 Y axis stage 45 Arm 46 Y axis stage 47 Arm 47 Rotating mechanism 101 Housing 101A Main housing 101B Sub housing 101a Supply passage 101b Supply passage 101c Circumferential groove 101d Circumferential groove 101f Cooling jacket 102 Main shaft 102 Reduced diameter cylindrical portion 102a Flange 102b Through hole 102c Exhaust port 102d Reduced diameter cylindrical portion 103 Member 104 Motor 105 D Encoder 106 Suction case 106a Static pressure pad 106b Discharge port BT Bolt CV Concave G Shallow groove H Housing HD Holder M Material P + Positive pressure pump P- Negative pressure pump S Spindle SD Spindle device T Tool

Claims (14)

In a spindle apparatus having a main shaft driven and rotated by a driving means, a housing disposed around the main shaft, and a hydrostatic bearing that rotatably supports the main shaft.
The housing has a supply passage for supplying a fluid supplied from a fluid supply source between the main shaft and the housing, and the hydrostatic bearing is supplied with the fluid, so that the fluid is supplied to the housing. Supporting the main shaft,
A recess connected to the supply passage is provided in at least one of the outer peripheral surface of the main shaft and the inner peripheral surface of the housing, and the opening cross-sectional area of the recess is larger than the minimum cross-sectional area of the supply passage. Spindle device to do.   The spindle device according to claim 1, wherein the recess is formed on an inner peripheral surface of the housing.   The spindle device according to claim 2, wherein a plurality of shallow grooves extending in the axial direction are formed side by side in the circumferential direction on the outer peripheral surface of the main shaft.   The spindle apparatus according to claim 3, wherein the shallow groove has a herringbone shape.   The spindle device according to claim 1, wherein the recess is formed on an outer peripheral surface of the main shaft.   The spindle device according to claim 1, wherein the recess is a circumferential groove extending in a circumferential direction.   A plurality of discharge ports of the supply passage are provided apart from each other in the axial direction on the peripheral surface, and the fluid supplied from the discharge port is disposed on the outer peripheral surface of the main shaft and the housing on the opposite side to the adjacent supply passage. The spindle device according to any one of claims 1 to 6, wherein the spindle device flows out between the inner peripheral surface and the outside. In a spindle apparatus having a main shaft driven and rotated by a driving means, a housing disposed around the main shaft, and a hydrostatic bearing that rotatably supports the main shaft.
The housing has a supply passage for supplying a fluid supplied from a fluid supply source between the main shaft and the housing, and the hydrostatic bearing is supplied with the fluid, so that the fluid is supplied to the housing. Supporting the main shaft,
A recess connected to the supply passage is provided on at least one of the surface facing the axial direction of the main shaft and the surface facing the axial direction of the housing facing the axial direction. A spindle device characterized by being larger than the minimum cross-sectional area of the passage.   The spindle device according to claim 8, wherein the recess is formed on a surface facing the axial direction of the housing.   The spindle device according to claim 9, wherein a plurality of shallow grooves extending in the radial direction are formed side by side in a circumferential direction on a surface of the main shaft facing the axial direction.   The spindle device according to claim 10, wherein the shallow groove has a herringbone shape.   The spindle device according to claim 8, wherein the concave portion is formed on a surface facing the axial direction of the main shaft.   The spindle device according to claim 8, wherein the recess is a circumferential groove extending in a circumferential direction. A plurality of discharge ports of the supply passage are provided radially apart on the surface facing the axial direction, and the fluid supplied from the discharge port is the main shaft on the opposite side of the adjacent supply passage and the main shaft and the The spindle device according to claim 8, wherein the spindle device flows out to the outside through a plane facing the axial direction of the housing.

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