JP2006263824A - Spindle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle device suitable for avoiding the influence of thermal deformation to perform high-accuracy machining. <P>SOLUTION: When the temperature of a housing H rises, a first support member HL1 near the tip of a spindle S to which a work and a tool are fitted hardly deforms, and only a second support member HL2 bends. In such a case, the housing H is deformed so that the central part does not bend back upward in the center, but the right end displaces to the right. That is, the fitting surface of the spindle S to which the work or the tool are fitted is not inclined, and the position in the axial direction is not displaced to perform high-accuracy machining by the spindle device SD. Further, even when the housing H is increased in diameter due to thermal deformation, it is vertically increased in diameter around the fixed points P1, P2 so that the horizontal position of a main shaft X is not changed and the positions of the work and the tool fitted to the tip of the spindle S are also unchanged to perform high-accuracy machining. <P>COPYRIGHT: (C)2007,JPO&INPIT

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.

  For example, a transfer optical surface of a molding die of an optical component mounted on an optical pickup device or the like requires high-precision processing of a complicated and fine shape corresponding to a diffractive structure in addition to an aspheric shape. . On the other hand, there is also a demand for efficient processing of one molding die.

  Here, in order to improve the processing efficiency of the molding die, the rotational speed of the spindle of the spindle device that holds and rotates the mold material (called a workpiece) or a tool during processing can be increased using a powerful motor. What is necessary is just to increase. However, for example, in a built-in motor type spindle device, if the motor is made strong, there is a problem that the temperature of the housing increases via the spindle main shaft and the housing is deformed.

On the other hand, Patent Document 1 discloses a technique in which a cooling passage is provided in a casing and a cooling medium is supplied thereto to suppress twisting of the casing.
JP 2001-62670 A

  If the technique of patent document 1 is used, the thermal expansion in the housing of a spindle apparatus can be suppressed to some extent. However, it is difficult to cool the housing to exactly the same temperature as room temperature, and processing must be performed with a certain temperature difference left. However, depending on the support mode of the housing, the position of the spindle head in the rotational axis direction changes due to thermal deformation that occurs in the housing, or the housing bends and the amount of clearance of the hydrostatic bearing that supports the spindle spindle changes in the circumferential direction. , There is a risk of reducing the rotation accuracy.

  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 suitable for solving the problem of thermal deformation and performing quick and highly accurate processing.

  The spindle device according to claim 1, wherein the first support member and the second support member that support the housing with respect to a floor surface are in an axial direction of the housing. The axial rigidity of the second support member on the side far from the workpiece or tool attachment surface of the main shaft is arranged in the axial direction of the first support member on the side close to the attachment surface. It is characterized by being lower.

  The effects of the present invention will be described with reference to the drawings. 1 and 2 are views showing a support state of the spindle device according to the comparative example, and FIG. 3 is a view showing a support state of the spindle device according to the present invention. 1 to 4, the deformation is exaggerated from the actual one.

  First, in the spindle device SD ′ shown in FIG. 1, the housing H that rotatably supports the main shaft S has a first support member HL1 and a second support member HL2 that are bolted to the surface of the surface plate G that is the floor surface. Is supported by. More specifically, the lowermost end portion of the housing H is supported in a state of being in contact with the upper ends of the first support member HL1 and the second support member HL2 that are arranged apart in the axial direction. The first support member HL1 and the second support member HL2 have the same rigidity.

  Here, it is assumed that the temperature of the housing H is increased by rotationally driving the main shaft S. In this case, since the surface plate G remains at room temperature, the distance between the lower ends of the first support member HL1 and the second support member HL2 is not changed, whereas the housing H is increased in length due to thermal expansion. Transforms into However, since the upper ends of the first support member HL1 and the second support member HL2 are fixed to the housing H, the upper ends of the first support member HL1 and the second support member HL2 are deformed so as to be separated from each other as shown in FIG. Accordingly, the housing H is deformed so that the center warps upward. Then, the left end surface (workpiece or tool mounting surface, also simply referred to as a mounting surface) of the spindle S is inclined downward and moves forward, and when the workpiece or tool is mounted here, the displacement occurs, and the spindle device There is a problem that high-precision machining cannot be performed using SD ′.

  In contrast, in the spindle device SD according to the aspect of the present invention shown in FIG. 3, the first support member HL1 in which the lowermost end portion of the housing H is spaced apart in the axial direction, as in the comparative example, and The second support member HL2 is supported in a state of being in contact with the upper ends of the second support members HL2, but the second support member HL2 far from the work or tool mounting surface has, for example, a parallel elastic spring PRG in the axial direction thereof. The rigidity is lower than the rigidity in the axial direction of the first support member HL1. Otherwise, the spindle device SD has the same configuration as that of the comparative example shown in FIG.

  When the temperature of the housing H rises by rotationally driving the spindle S, the first support member HL1 close to the left end face (attachment surface) of the spindle S to which the workpiece or tool is attached is hardly deformed, However, in this case, the housing H is deformed so that the right end of the housing H is displaced rightward in the drawing (the position from the dotted line to the solid line). . In other words, since the attachment surface of the spindle S to which the workpiece or tool is attached is not inclined and the position in the axial direction is not displaced, high-precision machining can be performed by the spindle device SD.

  According to a second aspect of the present invention, in the spindle device according to the first aspect, the rigidity of the second support member in the axial direction is not more than ½ of the rigidity of the first support member in the axial direction. Therefore, the deformation of the first support member can be suppressed by ensuring a large deflection of the second support member in accordance with the deformation of the housing. If the rigidity of the second support member in the axial direction is equal to or less than ½ of the rigidity of the first support member in the axial direction, the deformation of the housing is easily absorbed by the second support member. For example, the axial displacement of the mounting surface of the main shaft can be reduced to about 1/3 or less compared to the case where the rigidity is equal, which is more suitable for performing highly accurate machining.

  According to a third aspect of the present invention, the spindle device according to the first or second aspect is characterized in that the second support member has an elastic spring.

  When an elastic spring is used to reduce the rigidity of the second support member in the axial direction, the rigidity is reduced only in the axial direction, and the rigidity can be maintained high in the direction orthogonal to this and other directions. The original purpose of supporting the housing is not impaired. Further, if the rigidity is lowered, there is a possibility that vibration accompanying the rotation may occur, but such a problem can be avoided. In particular, among elastic springs that reduce the rigidity in the rotation axis direction, using a parallel elastic spring with a structure in which a plurality of pillars are arranged can increase the rigidity in directions other than the rotation axis direction, such as vibration with high-speed rotation. Can be effectively suppressed.

  According to a fourth aspect of the present invention, in the spindle device according to any one of the first to third aspects of the present invention, the housing may be configured such that the floor is at least one of the first support member and the second support member. The height from the surface is supported at a position equal to the axis of the main shaft. Here, the position where the height from the floor surface is substantially equal to the height of the axis of the main shaft includes a position having a difference of about ± 10 mm in the height direction.

  FIG. 4 is a diagram showing a support state of the spindle device SD according to another aspect of the present invention. The spindle device SD has the same configuration as that shown in FIG. 3 except for the support mode of the first support member HL1 and the second support member HL2. For example, in the spindle device SD shown in FIG. 3, since the lowermost end portion of the housing H is supported by the upper end portions of the first support member HL1 and the second support member HL2, the diameter of the housing H increases due to thermal deformation. There is a possibility that the axis line X of the main spindle S is displaced upward by the amount of the one-dot chain line and the diameter of the workpiece or the tool attached to the tip thereof is also displaced upward.

  Therefore, in the present invention, as shown in FIG. 4, the housing H is formed from the surface plate G against both the first support member HL <b> 1 and the second support member HL <b> 2 (effective in at least one of them). Is supported at a position where the height is equal to the axis X of the main shaft S. More specifically, the upper portions of the first support member HL1 and the second support member HL2 have a bifurcated shape or a pair of columnar structures so that the housing H is sandwiched therebetween, and the fixing points P1, P2 overlaps with the axis X when viewed from the horizontal direction shown in FIG. The second support member HL2 includes a parallel elastic spring PRG, for example.

  According to such a configuration, even when the diameter of the housing H is increased due to thermal deformation (dashed line), the diameter is increased in the vertical direction around the fixed points P1 and P2. As a result, since the displacement of the position of the workpiece or tool attached to the left end surface (attachment surface) of the spindle S can also be suppressed, highly accurate machining can be performed.

  According to a fifth aspect of the present invention, in the spindle device according to the fourth aspect, the housing is supported so as to be rotatable relative to at least one of the first support member and the second support member. Therefore, it is preferable that the housing is restrained from being restrained during deformation.

  A 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 main shaft is rotatably supported by a hydrostatic bearing with respect to the housing. However, the main shaft may be supported by a rolling bearing or a sliding bearing with respect to the housing.

  ADVANTAGE OF THE INVENTION According to this invention, the spindle apparatus suitable for solving the problem of a thermal deformation and performing a quick and highly accurate process can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. The motor built-in type spindle apparatus according to the embodiment of the present invention can be used in the two-axis turning precision machine shown in FIG. In FIG. 5, an X-axis table 2 driven in the X-axis direction by a control device (not shown) is disposed 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 motor built-in spindle device according to the embodiment of the present invention can be used in the turning precision machine shown in FIG. In FIG. 6, an X-axis table 12 driven in the X-axis direction and a Z-axis table 14 driven in the Z-axis direction are attached on the 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 motor built-in type spindle apparatus according to the embodiment of the present invention is used for an ultra-precision machining machine having a three-axis movable stage and a rotating mechanism for rotating a diamond tool, as shown in FIG. Can do. In FIG. 7, an X-axis table 22 driven in the X-axis direction and a Z-axis table 24 driven in the Z-axis direction are mounted on a 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 motor built-in spindle device according to the embodiment of the present invention can be used in the milling machine shown in FIG. In FIG. 8, 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. A tool blade tip is attached to the end surface of the spindle of the spindle device SD incorporated in the arm 45 so that the tool blade edge is positioned, for example, 15 mm away from the rotation center in the radial direction, and fixed to the workpiece M fixed on the Z-axis stage 44. On the other hand, cutting is performed in the Y-axis direction, and the diamond tool 43 is sent in the X-axis direction to perform cutting.

  FIG. 9 is a cross-sectional view of the motor built-in spindle device according to the present embodiment. The spindle device SD of FIG. 9 can be incorporated into the milling machine of FIG. 8, for example, but is not limited thereto, and it goes without saying that it can be incorporated into the machining machine of FIGS. Absent.

  In FIG. 9, a cylindrical main shaft S is fitted in a hollow cylindrical housing H. Both clearances are about 10 μm. The main shaft S has a flange 102a near the left end in FIG. 9, and a through hole 102b in the center. The housing H 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 source. The other end of the supply passage 101a opens on the inner peripheral surface of the main housing 101A so as to face the outer peripheral surface of the main shaft S 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 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. In the present embodiment, the entire inner peripheral surface of the main housing 101A is filled with static pressure and functions as a radial static pressure bearing. 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 + that is an external fluid source. The other end of the supply passage 101b opens on the inner peripheral surface of the sub-housing 101B so as to face the outer peripheral surface of the main shaft S in two rows side by side in the axial direction and at equal intervals of 120 degrees in the circumferential direction (there are 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 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. In the present embodiment, the entire inner peripheral surface of the sub-housing 101B is filled with static pressure and functions as a radial hydrostatic bearing.

  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 S to the outer periphery.

  A motor 104, which is a driving means, is provided adjacent to the main housing 101A. The motor 104 is attached to the main shaft S so that the motor case 104a constituting a part of the housing and the different polarities alternate in the circumferential direction (N pole, S pole, N pole, S pole,...). 4-pole 2-row (aligned in the axial direction) magnets 104b, 104b, two pairs of coils 104c, 104c disposed radially outside the magnets 104b, 104b and in the motor case 104a, and coils 104c, It consists of cores 104d and 104d wound around 104c. By supplying electric power to the coils 104c and 104c from the outside, the main shaft S can be rotationally driven in a known manner. The motor case 104a is provided with a hole 104e through which cooling water passes, and the temperature rise of the motor case 104a due to heat generation of the coils 104c and 104c is suppressed by the cooling water passing therethrough.

  In FIG. 9, the magnet 104b in the left row is skewed and tilted by + θ degrees with respect to the axis, and the magnet 104b in the right row in FIG. 9 is also skewed but tilted by −θ degrees with respect to the axis. It has been. Further, the phase arrangement of the two rows of magnets 104b and 104b is shifted from each other by ½ pitch in the circumferential direction.

  At the right end of the main shaft S, a reduced diameter cylindrical portion 102d is formed coaxially. 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 thereby determine the rotation angle of the main shaft S.

  The tip of the reduced diameter cylindrical portion 102d is inserted into the suction case 106. The suction case 106 is attached to the housing H, and a circular tube porous static pressure pad 106a is disposed at an 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 S so that air in the through hole 102b is sucked by the negative pressure pump P− connected to the discharge port 106b. It has become.

The left end of the main shaft S is a flat surface (also referred to as an attachment surface) 102h, and a bolt hole 102g is provided, so that 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 mounting surface of the holder HD is pressed against the mounting surface 102h of the main shaft S, the air in the through hole 102b is sucked through the suction case 106 and becomes negative pressure. The holder HD is fixed with respect to the main shaft S by the differential pressure from the atmospheric pressure. The holder HD is centered while rotating the spindle S at this stage. After centering the holder HD, the holder HD is fixed to the main shaft S by screwing the bolt BT into the bolt hole 102g. If the holder HD is fixed to the main shaft S using the bolt BT, even if the main shaft S is rotationally driven at a high speed of, for example, 10,000 min ⁻¹ or more, it will not drop off or be displaced due to centrifugal force or the like.

  When the spindle device SD of FIG. 9 is operated in a state where it is incorporated in the milling machine of FIG. 9, the main pressure pump P + is connected to the supply passages 101a and 101b through the discharge ports A, B, C, E, and F. Since the main shaft S is supported in a non-contact state with respect to the main housing 101A and the sub housing 101B by the air supplied into the housing 101A and the sub housing 101B, the main shaft S can receive a radial load received from the tool T. it can.

  Further, the flange 102a of the main shaft S is moved from the positive pressure pump P + into the main housing 101A and the sub housing 101B through the discharge ports D and G of the supply passages 101a and 101b, so that the main housing 101A and the sub housing 101B. Therefore, it is possible to receive a load in the thrust direction received from the tool T. That is, the hydrostatic bearing for thrust is constituted by the both side surfaces of the flange 102a and the end surfaces of the main housing 101A and the sub-housing 101B facing the flange 102a.

  When the motor 104 is driven in such a state, the spindle S rotates. According to the present embodiment, the motor case 104a has the two pairs of coils 104c and 104c disposed so as to face the two rows of magnets 104b and 104b, respectively. Although the main shaft S can be rotationally driven with the same level of torque as a whole, the magnets 104b and 104b serving as heating elements are dispersedly arranged, so that the main shaft S has a locally high temperature. The part which becomes becomes is avoided. Further, since the areas of the magnets 104b and 104b provided on the main shaft S are increased, even if heat is generated in the magnets 104b and 104b, a higher cooling effect can be obtained as compared with the case where the magnets are arranged in one row. . In addition, the cooling water supplied to the hole 104e of the motor case 104a can suppress an increase in the temperature of the motor case 104a due to heat generated by the coils 104c and 104c.

  In particular, since the two rows of magnets 104b and 104b are shifted in the circumferential direction from one another in the circumferential direction, the torque variation is substantially the same as that of the 8-pole magnet arrangement although the 4-pole magnet arrangement is used. be able to. As a result, while reducing the diameter of the spindle S and realizing high-speed rotation, torque unevenness is greatly suppressed, rotation accuracy is improved, and high machining accuracy can be obtained. In addition, since the two rows of magnets 104b and 104b have skew directions opposite to each other (+ θ degrees, −θ degrees), the diameter of the spindle S can be reduced while suppressing the thrust component force acting on the spindle S. While realizing high-speed rotation, torque unevenness is greatly suppressed, rotation accuracy is improved, and high machining accuracy can be obtained.

  Further, even if the main shaft S is heated by heat transfer from the motor 104 or the like at the time of rotational driving, it is cooled by the cooling water supplied to the cooling jacket 101f, and the thermal expansion is suppressed. Further, even when the rotating main shaft S 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 S is not a perfect circle, the circumferential grooves 101c and 101d serve as a temporary accumulation region of substantially uniform pressure for the air supplied from the supply passages 101a and 101b over the entire circumference. Regardless of the positional relationship between the pressure gap and the discharge port, the fluctuation in pressure applied to the outer peripheral surface of the main shaft S can be suppressed, and the vibration can be suppressed.

  The air supplied from the supply passage 101a passes between the main shaft S and the main housing 101A and flows out from the gap between the motors 104 to the outside. Further, the air supplied from the supply passage 101b passes between the main shaft S 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 S and the inner peripheral surfaces of the housings 101A and 101B, so that the static pressure can be increased and the support rigidity can be increased. Further, if the high temperature limit due to heat generation is the same, the present invention can use a rotor shaft having a larger diameter and a larger static pressure area than conventional ones, so that rigidity can be increased and rotation accuracy can be further improved.

  In the present embodiment, as shown in FIG. 4, the height of the housing H from the surface plate G, which is the floor surface, with respect to both the first support member HL1 and the second support member HL2, The main shaft S is supported at a position equal to the axis X. More specifically, the upper portions of the first support member HL1 and the second support member HL2 are formed in a bifurcated shape or a pair of pillar structures so as to sandwich the housing H, and the fixing points P1 and P2 are It is made to overlap with the axis X as seen from the horizontal direction shown in FIG. The second support member HL2 includes a parallel elastic spring PRG, for example.

  According to the present embodiment, when the temperature of the housing H rises by driving the spindle S to rotate, the first support member HL1 close to the tip (attachment surface) of the spindle S to which the workpiece or tool is attached is Only the second support member HL2 bends with almost no deformation, but in this case, the housing H is deformed so that the right end in FIG. Become. That is, the attachment surface of the spindle S to which the workpiece or tool is attached is not inclined, and the position in the axial direction is not displaced, so that the spindle device SD can perform highly accurate machining. Further, even when the housing H is expanded in diameter by thermal deformation (dashed line), the horizontal position of the main shaft X does not change and is attached to the tip of the main shaft S because the diameter increases in the vertical direction around the fixed points P1 and P2. Since the position of the workpiece and the tool that has been made does not change, high-precision machining can be performed.

  The first support member HL1 and the second support member HL2 and the housing H may be fixed by fastening with bolts. For example, a cylindrical recess and a cylindrical recess with the normal line from the fixing points P1 and P2 as axes. Since the relative rotation of the first support member HL1 and the second support member HL2 and the housing H is allowed around the axis, the deformation of the housing H can be further suppressed.

Here, a spindle device having a spindle outer diameter of 40 mm and a flange outer diameter of 80 mm was fixedly supported at one point and attached to a surface plate. Since the surface plate is made of cast iron and has a very large volume compared to the spindle device, the heat capacity is extremely large, and the temperature rise due to the drive heat generation of the spindle device hardly occurs in a rotation time of about several tens of minutes. The housing of the spindle device is made of stainless steel SUS440. When the spindle device was rotated at 35000 min ⁻¹ , the housing temperature rose from room temperature by 23 ° C. At this time, the total length of the housing was increased by about 72 μm due to thermal expansion, and the diameter was increased by 18 μm. In addition, it was confirmed that the spindle device was not fixed enough to vibrate because it was supported at one point.

Next, the first support member and the second support member having a center interval of 250 mm in the longitudinal direction in the axial direction were supported at two locations on the bottom surface of the housing, and this support member was fixed to the surface plate with bolts. The two support members are made of S45C and are extremely common steel materials. Similarly, when rotating at 35000 min ⁻¹ , it was confirmed by the capacitance sensor that the spindle spindle mounting surface advances about 30 μm as the housing temperature rises.

Further, of the first support member and the second support member, the second support member far from the mounting surface of the spindle main shaft is replaced with a support member formed by hollowing out by wire electric discharge machining to form four elastic springs. Similarly, when rotating at 35000 min ⁻¹ , the advancement of the spindle spindle mounting surface was greatly reduced to about 3.5 μm.

Further, the first support member and the second support member are fixed to the spindle device at the height of the rotation axis of the main shaft, and the second support member is parallel using four elastic springs as described above. Elastic spring support. Displacement was measured at two locations above and below the spindle spindle, and the rotation was performed at 35000 min ^-1 assuming that one half of the total was height fluctuation at the center of rotation. It was. When the same experiment was performed by changing the support member to a low linear expansion material having a linear expansion coefficient of 1, 3 × 10 ⁻⁶ , the height fluctuation of the spindle main shaft was +0.7 μm. Since the thermal conductivity varies depending on the material of the support member, the fluctuation in the height of the rotating shaft is not necessarily reduced by the ratio of the linear expansion coefficient. However, the present invention can reduce the fluctuation in height by several tenths compared to the beginning. It was found that it can be greatly reduced.

  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 type of motor that drives the spindle device does not matter. An AC servo motor with or without a core may be used, or an induction motor using a conductor instead of the magnet described above may be used. In particular, induction motors tend to generate heat because of loss due to sliding compared to AC servomotors, and the effects of the present invention are more remarkable.

It is a figure which shows the support state of the spindle apparatus by a comparative example. It is a figure which shows the support state of the spindle apparatus by a comparative example, and has shown the state after the deformation | transformation of a housing. It is a figure which shows the support state of the spindle apparatus by this invention, and has shown the state after the deformation | transformation of a housing. It is a figure which shows the support state of the spindle apparatus SD concerning another aspect 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.

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 101A Main housing 101B Sub housing 101C Ring Housing 101a Supply passage 101b Supply passage 101c Circumferential groove 101d Circumferential groove 101f Cooling jacket 102 Reduced diameter cylindrical portion 102a Flange 102b Through hole 102c Exhaust port 102d Reduced diameter cylindrical portion 103 Member 104 Motor 105 En Over da 106 suction case 106a hydrostatic pad 106b outlet P + positive pressure pump P- negative pressure pump H housing S spindle SD spindle device T tool

Claims (6)

In a spindle device having a housing and a main shaft,
A first support member and a second support member that support the housing with respect to the floor surface are arranged apart from each other in the axial direction of the housing, and are on the side far from the work surface of the main spindle or the tool mounting surface. The spindle device characterized in that the rigidity of the second support member in the axial direction is lower than the rigidity of the first support member on the side close to the mounting surface.   2. The spindle device according to claim 1, wherein the rigidity of the second support member in the axial direction is ½ or less of the rigidity of the first support member in the axial direction.   The spindle device according to claim 1, wherein the second support member includes an elastic spring.   The housing is supported with respect to at least one of the first support member and the second support member at a position where the height from the floor surface is substantially equal to the height of the axis of the main shaft. The spindle device according to any one of claims 1 to 3.   The spindle device according to claim 4, wherein the housing is supported so as to be rotatable relative to at least one of the first support member and the second support member. The spindle device according to claim 1, wherein the main shaft is rotatably supported by a hydrostatic bearing with respect to the housing.

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