Machine tool spindle unit

Abstract

The present disclosure relates to a spindle unit for a machine tool including a spindle and a rotor disposed on the outer periphery of the spindle. The spindle unit includes a detachable ring that is detachable from the spindle and fastens to one axial end of the rotor. The detachable ring has a liquid holding portion that is in contact with the spindle and can hold liquid, and an injection hole for injecting liquid into the liquid holding portion. The spindle is provided with a fastening portion that fastens to the other axial end of the rotor.

Description

Technical Field

[0001] This disclosure relates to a spindle device of a machine tool.

Background Art

[0002] A machine tool includes a spindle device that supports a tool. The spindle device includes a spindle provided with a rotor. The spindle and the rotor are fastened via, for example, a shrink ring (trade name) described in International Publication No. 2009 / 013912.

Summary of the Invention

[0003] In the spindle device, when the rotor vibrates excessively, it affects the machining accuracy.

[0004] An aspect of this disclosure is a spindle device of a machine tool including a spindle and a rotor disposed on the outer periphery of the spindle, the spindle device including a detachable ring that is detachable from the spindle and fastened to one axial end of the rotor by a first bolt, a fastening portion being provided on the spindle and fastened to the other axial end of the rotor by a second bolt, the detachable ring having a liquid holding portion capable of holding a liquid in contact with the spindle and an injection hole for injecting the liquid into the liquid holding portion.

Brief Description of the Drawings

[0005] [Figure 1] FIG. 1 is a cross-sectional side view of a main part of a spindle device according to a first embodiment. [Figure 2] FIG. 2 is a schematic front view of a detachable ring when viewed from the axial direction of the spindle. [Figure 3] FIG. 3 is a schematic cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional side view of a main part of a spindle device showing a state where a liquid holding portion formed in a detachable ring is filled with a liquid. [Figure 5] FIG. 5 is a cross-sectional side view of a main part along the axial direction of a spindle device according to a second embodiment. [Figure 6]Figure 6 is a side cross-sectional view of the main part of the spindle device according to the third embodiment. [Figure 7] Figure 7 is a side cross-sectional view of the main part of the spindle device according to the fourth embodiment. [Figure 8] Figure 8 is a side cross-sectional view of the main part of the spindle device according to the fifth embodiment. [Figure 9] Figure 9 is a side cross-sectional view of the main part of the spindle device according to the sixth embodiment. [Figure 10] Figure 10 is a schematic perspective view of the rotor constituting the spindle device according to the sixth embodiment. [Figure 11] Figure 11 is a side cross-sectional view of the main part of the spindle device according to the seventh embodiment. [Figure 12] Figure 12 is a schematic front view of the detachable ring in a modified example, viewed from the axial direction of the main spindle. [Modes for carrying out the invention]

[0006] When fastening the rotor of an SPM motor to the spindle with a spring ring, a wedge portion must be provided in the sleeve that makes up the rotor, and this wedge portion must be sandwiched between the spindle and the spring ring. Therefore, the shape of the sleeve is complex. Furthermore, if the surface roughness of the wedge portion is excessively large, it becomes difficult to sandwich the wedge portion between the spindle and the spring ring. Consequently, the surface roughness of the rotor, including the wedge portion, must be reduced. In this case, the cost of obtaining the sleeve increases significantly.

[0007] Furthermore, since the wedge portion is sandwiched between the main spindle and the spring ring, there is a concern that the wedge portion or the spring ring may deform. For this reason, there are limitations on increasing the fastening force of the rotor to the main spindle via the spring ring. There are also limitations on the number of times the rotor can be fastened to the main spindle via the spring ring and released from the main spindle.

[0008] Regardless of whether a spindle ring is used, if the fastening force of the rotor to the spindle is insufficient, the rotor will vibrate. When a workpiece is machined with such a spindle device, the machining accuracy decreases. To improve the machining accuracy of machine tools, it is desirable to suppress rotor vibration.

[0009] (First embodiment) Figure 1 is a side cross-sectional view of the main part of the spindle device 10A according to the first embodiment. This spindle device 10A constitutes a machine tool.

[0010] The spindle unit 10A comprises a spindle 12 and a rotor 14. The spindle 12 extends along the left-right direction in Figure 1. That is, the axial direction of the spindle 12 is the left-right direction in Figure 1.

[0011] In the first embodiment, the rotor 14 constitutes an SPM motor. Hereinafter, this rotor 14 will be referred to as the SPM-type rotor 30. The SPM-type rotor 30 has a sleeve 36, a permanent magnet 38, and a cylindrical cover 40. The sleeve 36 is a cylindrical body with a certain thickness. The permanent magnet 38 is held in the sleeve 36 by being sandwiched between the outer circumferential surface of the sleeve 36 and the inner circumferential surface of the cylindrical cover 40. A small clearance 16 is formed between the outer circumferential surface of the main shaft 12 and the inner circumferential surface of the rotor-side insertion hole 33 in the sleeve 36.

[0012] The SPM type rotor 30 has a first end 32a as one end in the axial direction, a second end 32b as the other end in the axial direction, and a rotor-side insertion hole 33 through which the spindle 12 passes. The first end 32a of the sleeve 36 is provided with a first screw hole 42a, and the second end 32b of the sleeve 36 is provided with a second screw hole 42b. The first screw hole 42a extends from the first end 32a toward the second end 32b along the axial direction of the spindle 12. The second screw hole 42b extends from the second end 32b toward the first end 32a along the axial direction of the spindle 12.

[0013] The spindle unit 10A further includes a detachable ring 50 as shown in Figures 2 and 3. The detachable ring 50 has a first end face 52a and a second end face 52b, which are substantially circular in shape. That is, in the first embodiment, the detachable ring 50 has a substantially cylindrical shape. The second end face 52b is the end face of the detachable ring 50 that faces the first end 32a of the SPM type rotor 30. The first end face 52a is the back surface of the second end face 52b. The second end face 52b abuts against the end face of the first end 32a of the sleeve 36.

[0014] A ring-side insertion hole 54 is formed at the diametrical center of the detachable ring 50. The spindle 12 passes through the ring-side insertion hole 54. The detachable ring 50 is attached to the spindle 12, for example, by shrink fitting.

[0015] In the detachable ring 50, first bolt insertion holes 56 are formed on the outer circumference of the ring-side insertion hole 54. In the illustrated example, there are eight first bolt insertion holes 56. When the detachable ring 50 is mounted on the main shaft 12, the first bolt insertion holes 56 overlap with the first screw holes 42a of the SPM type rotor 30. In the first embodiment, a first bolt 26 is passed through the first bolt insertion holes 56. The first bolt 26 is screwed into the first screw holes 42a of the sleeve 36.

[0016] In the detachable ring 50, a balance correction section 58 is provided on the outer circumference of the first bolt insertion hole 56. In the illustrated example, the balance correction section 58 consists of 16 balance correction holes 60. Balance correction members 70 are detachably inserted into the balance correction holes 60. The weight increases at the location where the balance correction member 70 is inserted into the balance correction hole 60. This makes it possible to adjust the weight balance of the SPM type rotor 30. In the illustrated example, the balance correction member 70 is a bolt.

[0017] Inside the detachable ring 50, a liquid holding portion 64 is formed. The liquid holding portion 64 is an inner chamber formed by a concave space 66 that recesses outward in the diameter direction starting from the ring-side insertion hole 54 and the main shaft 12. Specifically, as the main shaft 12 is inserted into the ring-side insertion hole 54, the opening facing the main shaft 12 in the concave space 66 is blocked by the main shaft 12. Thereby, a liquid holding portion 64 surrounded by the outer peripheral surface of the main shaft 12 and the inner surface of the concave space 66 is formed.

[0018] An injection hole 68 is formed in the first end surface 52a of the detachable ring 50 (see FIGS. 3 and 4). The injection hole 68 communicates with the liquid holding portion 64. Therefore, it is possible to inject a liquid L (see FIG. 4) into the liquid holding portion 64 through the injection hole 68. A typical example of the liquid L is oil.

[0019] The main shaft 12 has a fastening portion 20. The fastening portion 20 is, for example, a flange portion 22 provided on the main shaft 12. The flange portion 22 has a first end surface 23a and a second end surface 23b. The first end surface 23a is the end surface of the flange portion 22 that faces the second end portion 32b of the SPM type rotor 30. The second end surface 23b is the back surface of the first end surface 23a. The first end surface 23a abuts against the end surface of the second end portion 32b of the sleeve 36.

[0020] A second bolt insertion hole 24 is formed in the flange portion 22. The second bolt insertion hole 24 extends along the axial direction of the main shaft 12 from the second end surface 23b to the first end surface 23a. When the sleeve 36 is fastened to the flange portion 22, when viewed from the axial direction, the second screw hole 42b overlaps with the second bolt insertion hole 24. In the first embodiment, the second bolt 28 is inserted into the second bolt insertion hole 24 from the second end surface 23b. The second bolt 28 is screwed into the second screw hole 42b of the SPM type rotor 30.

[0021] The spindle assembly 10A is manufactured as follows. First, the spindle 12 is passed through the rotor-side insertion hole 33 of the SPM-type rotor 30. Next, the second bolt 28 is inserted from the second end face 23b of the flange portion 22 into the second bolt insertion hole 24. The second bolt 28 is screwed into the second threaded hole 42b of the SPM-type rotor 30. In this way, the flange portion 22 and the SPM-type rotor 30 are fastened together via the second bolt 28.

[0022] Next, in this state, the detachable ring 50 is attached to the spindle 12, for example, by shrink fitting. Specifically, the detachable ring 50 is heated, causing thermal expansion. In this state, the spindle 12 is passed through the ring-side insertion hole 54. The SPM type rotor 30 (sleeve 36) is sandwiched between the first end face 23a of the flange portion 22 and the second end face 52b of the detachable ring 50, and then the detachable ring 50 is cooled. As a result, the detachable ring 50 contracts, and the inner diameter of the ring-side insertion hole 54 approximately matches the outer diameter of the spindle 12. For this reason, it is difficult for an operator to remove the detachable ring 50 from the spindle 12 by hand.

[0023] Next, the first bolt 26, which has passed through the first bolt insertion hole 56 of the detachable ring 50, is screwed into the first threaded hole 42a of the sleeve 36. This fastens the SPM type rotor 30 to the flange portion 22 and the detachable ring 50, respectively.

[0024] As can be understood from the above, in the first embodiment, the spindle device 10A with the above configuration can be manufactured without performing fastening that assumes deformation of the wedge portion, etc. Therefore, deformation of each component such as the detachable ring 50 is avoided. Furthermore, the above operation can be performed regardless of the shape and surface roughness of the sleeve 36. For this reason, it is not necessary to specify the shape and surface roughness of the sleeve 36.

[0025] The spindle unit 10A is installed in the machine tool. Subsequently, the spindle unit 10A is test-driven. If imbalances such as eccentric rotation are observed during the test drive, the balance correction member 70 is inserted into the designated balance correction hole 60. This allows the weight balance of the SPM type rotor 30 to be balanced. If no weight imbalance of the SPM type rotor 30 is observed during the test drive, it is not necessary to insert the balance correction member 70 into the balance correction hole 60.

[0026] The spindle 12 holds a machining tool (not shown). When machining is performed on a workpiece (not shown), the spindle 12, the SPM-type rotor 30, and the machining tool rotate as a single unit. The machining tool performs a predetermined machining operation on the workpiece, such as drilling.

[0027] In the first embodiment, the SPM-type rotor 30 is sandwiched between the flange portion 22 and the attachment ring 50 and tightened with the first bolt 26 and the second bolt 28. Therefore, the first bolt 26 and the second bolt 28 are less likely to loosen. Moreover, in this spindle device 10A, the weight balance of the SPM-type rotor 30 is adjusted as described above. Therefore, the SPM-type rotor 30 is more likely to maintain a stable position. This suppresses vibrations in the SPM-type rotor 30. With the spindle device 10A in which vibrations of the SPM-type rotor 30 are suppressed, machining accuracy is improved.

[0028] When removing the SPM-type rotor 30 from the spindle 12 for maintenance work, first, as shown in Figure 4, the first bolt 26 is loosened and released from the first screw hole 42a and the first bolt insertion hole 56. Next, liquid L (oil, etc.) is injected into the liquid holding part 64 through the injection hole 68. As the liquid holding part 64 is filled with liquid L and the hydraulic pressure LP rises, pressure is applied to the detachable ring 50 from the liquid L in the liquid holding part 64 in the diametrical direction relative to the spindle 12, and pressure in the axial direction. When the hydraulic pressure LP becomes greater than the frictional force FF between the outer surface of the spindle 12 and the inner surface of the ring-side insertion hole 54, the detachable ring 50 is pushed by the liquid L and detached from the spindle 12. As a result, the SPM-type rotor 30 is released from the constraint of the detachable ring 50.

[0029] Next, the second bolt 28 is loosened and released from the second screw hole 42b and the second bolt insertion hole 24. This releases the SPM type rotor 30 from the constraint of the flange portion 22. Alternatively, the second bolt 28 may be loosened and released from the second screw hole 42b and the second bolt insertion hole 24 before the liquid L is injected into the liquid holding portion 64.

[0030] In this way, even when the SPM-type rotor 30 is released from fastening by the main shaft 12, deformation of each component such as the attachment ring 50 or sleeve 36 is avoided. Therefore, the attachment ring 50, sleeve 36, and cylindrical cover 40 can be reused repeatedly even after maintenance work.

[0031] Note that the rotor is not limited to the SPM type rotor 30. In other words, a rotor that constitutes a motor other than an SPM motor may be used as the rotor 14.

[0032] The effects of the first embodiment can be summarized as follows:

[0033] When the spindle 12 and the SPM-type rotor 30 rotate together, vibration of the SPM-type rotor 30 is suppressed. As a result, machining accuracy for the workpiece is improved.

[0034] The balance correction member 70 allows for balancing the weight of the SPM-type rotor 30. As a result, vibration of the SPM-type rotor 30 is further suppressed. Therefore, machining accuracy for the workpiece is further improved.

[0035] The detachable ring 50 can be attached to and detached from the main spindle 12 without deforming the detachable ring 50, the main spindle 12, the flange portion 22, and the SPM-type rotor 30. Therefore, the detachable ring 50, the main spindle 12, the flange portion 22, and the SPM-type rotor 30 can be used repeatedly.

[0036] The SPM type rotor 30 can be attached to and detached from the spindle 12 regardless of the shape and surface roughness of the sleeve 36. Therefore, there are no restrictions on the shape and surface roughness of the sleeve 36.

[0037] (Second embodiment) In the second embodiment described below, explanations that overlap with those of the first embodiment are omitted. Furthermore, in the figures used in the second embodiment below, components identical to those described in the first embodiment are denoted by the same reference numerals.

[0038] Figure 5 is a side cross-sectional view of the main part of the spindle device 10B along the axial direction according to the second embodiment. In this case, the nominal diameter D2 of the second bolt 29 is larger than the nominal diameter D1 of the first bolt 26. Therefore, the fastening force of the second bolt 29 is greater than the fastening force of the first bolt 26. Consequently, when the first end 32a of the SPM type rotor 30 is fastened to the detachable ring 50 via the first bolt 26, and the second end 32b of the SPM type rotor 30 is fastened to the flange portion 22 via the second bolt 29, the second bolt 29 fastened to the SPM type rotor 30 applies a tensile force toward the flange portion 22 to the SPM type rotor 30. That is, the second tensile force F2 that the second bolt 29 exerts on the SPM type rotor 30 toward the flange portion 22 is greater than the first tensile force F1 that the first bolt 26 exerts on the SPM type rotor 30 toward the detachable ring 50.

[0039] Even if the nominal diameter D1 of the first bolt 26 and the nominal diameter D2 of the second bolt 29 are the same, it is possible to make the fastening force of the second bolt 29 greater than that of the first bolt 26 by, for example, making the fastening torque of the second bolt 29 greater than that of the first bolt 26. In this case as well, the relationship F2 > F1 holds true.

[0040] In the second embodiment, the SPM-type rotor 30 is sandwiched between the flange portion 22 and the attachment ring 50, and the SPM-type rotor 30 is pulled toward the flange portion 22. Therefore, the first bolt 26 and the second bolt 29 are less likely to loosen. As a result, vibration of the SPM-type rotor 30 is further suppressed when the spindle 12 and the SPM-type rotor 30 rotate together. Consequently, machining accuracy for the workpiece is further improved.

[0041] Thus, according to the second embodiment, vibration of the SPM type rotor 30 is further suppressed, resulting in the effect of further improving the machining accuracy of the workpiece.

[0042] (Third embodiment) In the third embodiment described below, explanations that overlap with those of the first and second embodiments are omitted. Furthermore, in the figures used in the third embodiment below, components identical to those described in the first and second embodiments are denoted by the same reference numerals.

[0043] Figure 6 is a side cross-sectional view of the main part of the spindle device 10C according to the third embodiment. In this case, a through hole 43 is formed in the sleeve 36. The through hole 43 extends along the axial direction of the sleeve 36 from the second end 32b to the first end 32a of the SPM type rotor 30.

[0044] In the third embodiment, a long bolt 27 is used. The long bolt 27 serves as both the first bolt 26 and the second bolt 28. In other words, the first bolt 26 and the second bolt 28 are the same bolt (one long bolt 27). Although not specifically shown in the figures, a female thread may be formed on the inner surface of the through hole 43, and the long bolt 27 and the first bolt 26 may be screwed into this female thread. In this case, the long bolt 27 corresponds to the second bolt 28.

[0045] The first bolt insertion hole 56 provided in the detachable ring 50 also serves as the first threaded hole 42a. That is, a threaded portion is provided on the inner circumferential surface of the first bolt insertion hole 56. The long bolt 27 is passed through the second bolt insertion hole 24 formed in the flange portion 22, which is the fastening portion 20, and inserted through the through hole 43 into the first bolt insertion hole 56 of the detachable ring 50. The threaded portion of the long bolt 27 is screwed into the threaded portion formed on the inner circumferential surface of the first bolt insertion hole 56.

[0046] In the third embodiment, the SPM-type rotor 30 can be fastened to the main shaft 12 via the flange portion 22 by tightening the long bolt 27, and at the same time, the SPM-type rotor 30 can be fastened to the main shaft 12 via the detachable ring 50. Conversely, by loosening the long bolt 27, the fastening of the SPM-type rotor 30 via the flange portion 22 can be released, and at the same time, the fastening of the SPM-type rotor 30 via the detachable ring 50 can be released.

[0047] Alternatively, instead of screwing the long bolt 27 into the first bolt insertion hole 56 of the fastening ring 50, the threaded portion of the long bolt 27 may be extended from the first bolt insertion hole 56, and a nut may be screwed onto this extended threaded portion. In this case, the machining work of creating a threaded portion on the inner circumferential surface of the first bolt insertion hole 56 is unnecessary.

[0048] Thus, according to the third embodiment, fastening and detaching the SPM type rotor 30 to the main shaft 12 is easy.

[0049] In the third embodiment, as the long bolt 27 is tightened, the detachable ring 50 is pulled toward the flange portion 22. Therefore, as in the second embodiment, vibration of the SPM type rotor 30 is further suppressed.

[0050] (Fourth embodiment) In the fourth embodiment described below, explanations that overlap with those in the first to third embodiments are omitted. Furthermore, in the figures used in the fourth embodiment below, components identical to those described in the first to third embodiments are denoted by the same reference numerals.

[0051] Figure 7 is a side cross-sectional view of the main part of the spindle device 10D according to the fourth embodiment. This spindle device 10D comprises a spindle 12 and an SPM type rotor 30.

[0052] In the fourth embodiment, the fastening portion 20 of the spindle unit 10D is the detachable ring 50 shown in Figures 2 and 3. That is, the spindle unit 10D is equipped with two detachable rings 50 as shown in Figures 2 and 3. Hereinafter, in order to easily distinguish between the two detachable rings 50, the detachable ring 50 facing the first end 32a of the SPM type rotor 30 will be referred to as the first detachable ring 50a. The second end face 52b of the first detachable ring 50a abuts against the end face of the first end 32a of the sleeve 36.

[0053] Furthermore, the detachable ring 50 facing the second end 32b of the SPM type rotor 30 is called the second detachable ring 50b. However, the bolt insertion hole of the second detachable ring 50b is called the "second bolt insertion hole 24" to easily distinguish it from the first bolt insertion hole 56 of the first detachable ring 50a, similar to the bolt insertion hole of the flange portion 22. The first end face 52a of the second detachable ring 50b abuts against the end face of the second end 32b of the sleeve 36.

[0054] The first detachable ring 50a and the second detachable ring 50b are attached to the spindle 12, for example, by shrink fitting.

[0055] The first detachable ring 50a has a ring-side insertion hole 54, a first bolt insertion hole 56, a balance correction portion 58, a recessed space 66 that becomes a liquid holding portion 64, and an injection hole 68 formed on the first end face 52a. The first bolt insertion hole 56 overlaps with the first screw hole 42a of the sleeve 36. The first bolt 26 is passed through the first bolt insertion hole 56. The first bolt 26 is screwed into the first screw hole 42a.

[0056] The second detachable ring 50b has a ring-side insertion hole 54, a second bolt insertion hole 24, a balance correction portion 58, a recessed space 66 that serves as a liquid holding portion 64, and an injection hole 68 formed on the second end face 52b. The second bolt insertion hole 24 overlaps with the second screw hole 42b of the sleeve 36. A second bolt 28 is passed through the second bolt insertion hole 24. The second bolt 28 is screwed into the second screw hole 42b.

[0057] With this configuration, it is not necessary to provide the main shaft 12 with a flange portion 22 or the like as a fastening portion 20. In other words, according to the fourth embodiment, the shape of the main shaft 12 can be simplified.

[0058] In the fourth embodiment, similar to the second embodiment, a second bolt 29 (see Figure 5) having a larger nominal diameter D2 than the first bolt 26 may be used. In this case, the fastening force of the first detachable ring 50a and the second detachable ring 50b to the spindle 12 may be appropriately changed according to the specifications required for the spindle device 10D.

[0059] (Fifth embodiment) In the fifth embodiment described below, explanations that overlap with those in the first to fourth embodiments are omitted. Furthermore, in the figures used in the fifth embodiment below, components identical to those described in the first to fourth embodiments are denoted by the same reference numerals.

[0060] Figure 8 is a side cross-sectional view of the main part of the spindle device 10E according to the fifth embodiment. In this case, the SPM type rotor 30 is sandwiched between the first detachable ring 50a and the second detachable ring 50b. A through hole 43 is formed in the sleeve 36. A long bolt 27, which serves as both the first bolt 26 and the second bolt 28, is passed through the through hole 43.

[0061] The inner circumferential surface of the first bolt insertion hole 56 provided in the first detachable ring 50a is provided with a threaded portion. That is, the first bolt insertion hole 56 also serves as the first threaded hole 42a. The long bolt 27 is passed through the second bolt insertion hole 24 formed in the second detachable ring 50b, through the through hole 43, and then inserted into the first bolt insertion hole 56 of the first detachable ring 50a. The threaded portion of the long bolt 27 is screwed into the threaded portion of the first bolt insertion hole 56.

[0062] In the fifth embodiment, tightening the long bolt 27 fastens the SPM-type rotor 30 to the main shaft 12 via the first detachable ring 50a, while simultaneously fastening the SPM-type rotor 30 to the main shaft 12 via the second detachable ring 50b. Conversely, loosening the long bolt 27 releases the fastening of the SPM-type rotor 30 by the first detachable ring 50a, while simultaneously releasing the fastening of the SPM-type rotor 30 by the second detachable ring 50b.

[0063] Instead of screwing the long bolt 27 into the first bolt insertion hole 56 of the first detachable ring 50a, the threaded portion of the long bolt 27 may be extended from the first bolt insertion hole 56, and a nut may be screwed onto this extended threaded portion. In this case, the machining work of creating a threaded portion in the first bolt insertion hole 56 becomes unnecessary. Also, the shapes of the first detachable ring 50a and the second detachable ring 50b will match. Therefore, it is not necessary to manufacture the first detachable ring 50a and the second detachable ring 50b separately. Furthermore, in this case, the long bolt 27 can be inserted from the first bolt insertion hole 56 of the first detachable ring 50a, and it can also be inserted from the second bolt insertion hole 24 of the second detachable ring 50b.

[0064] Thus, according to the fifth embodiment, fastening and detaching the SPM type rotor 30 to the main shaft 12 is easy.

[0065] In the fifth embodiment, as the long bolt 27 is tightened, vibration of the SPM type rotor 30 is further suppressed, similar to the second to fourth embodiments.

[0066] (Sixth embodiment) In the sixth embodiment described below, explanations that overlap with those in the first to fifth embodiments are omitted. Furthermore, in the figures used in the sixth embodiment below, components identical to those described in the first to fifth embodiments are denoted by the same reference numerals.

[0067] Figure 9 is a side cross-sectional view of the main part of the spindle device 10F according to the sixth embodiment. This spindle device 10F comprises a spindle 12 and a rotor 14. In the sixth embodiment, the fastening portion 20 is a flange portion 22.

[0068] In the sixth embodiment, the rotor 14 constitutes an IPM motor. Hereinafter, this rotor 14 will be referred to as the IPM-type rotor 80. The IPM-type rotor 80 has a core 82 as shown in Figure 10. The core 82 is made of a substantially cylindrical magnetic material. The core 82 has a rotor-side insertion hole 33 that penetrates along the axial direction. Similar to the first embodiment, the main shaft 12 passes through the rotor-side insertion hole 33. The core 82 has a plurality of retaining holes 84 that extend along the axial direction. The plurality of retaining holes 84 surround the rotor-side insertion hole 33. A permanent magnet 38 is held in each of the plurality of retaining holes 84.

[0069] In the illustrated example, a through hole 43 is formed between two adjacent retaining holes 84 that intersect at approximately 90°. The through hole 43 extends along the axial direction of the core 82 from the second end 32b to the first end 32a of the IPM type rotor 80.

[0070] In the sixth embodiment, a long bolt 27 is used, which serves as both the first bolt 26 and the second bolt 28. The long bolt 27 is passed through the through hole 43.

[0071] The inner circumferential surface of the first bolt insertion hole 56 provided in the detachable ring 50 is provided with a threaded portion. That is, the first bolt insertion hole 56 also serves as the first threaded hole 42a. The long bolt 27 is passed through the second bolt insertion hole 24 formed in the flange portion 22, through the through hole 43, and then inserted into the first bolt insertion hole 56 of the first detachable ring 50a. The threaded portion of the long bolt 27 is screwed into the threaded portion of the first bolt insertion hole 56.

[0072] In the sixth embodiment, tightening the long bolt 27 fastens the IPM-type rotor 80 to the main shaft 12 via the detachable ring 50, while simultaneously fastening the IPM-type rotor 80 to the main shaft 12 via the flange portion 22. Conversely, loosening the long bolt 27 releases the fastening of the IPM-type rotor 80 via the detachable ring 50, while simultaneously releasing the fastening of the IPM-type rotor 80 via the flange portion 22.

[0073] Alternatively, instead of screwing the long bolt 27 into the first bolt insertion hole 56 of the fastening ring 50, the threaded portion of the long bolt 27 may be extended from the first bolt insertion hole 56, and a nut may be screwed onto this extended threaded portion. In this case, the machining work of creating a threaded portion in the first bolt insertion hole 56 is unnecessary.

[0074] Thus, according to the sixth embodiment, even in an IPM motor in which permanent magnets 38 are embedded inside the core 82, the IPM type rotor 80 can be fastened to the main shaft 12. Furthermore, with this configuration, fastening and detaching the rotor 14 to the main shaft 12 is easy.

[0075] In the sixth embodiment, as the long bolt 27 is tightened, the detachable ring 50 is pulled toward the flange portion 22. Therefore, for the same reasons as in the second to fifth embodiments, vibration of the IPM type rotor 80 is suppressed.

[0076] (Seventh Embodiment) In the seventh embodiment described below, explanations that overlap with those in the first to sixth embodiments are omitted. Furthermore, in the figures used in the seventh embodiment below, components identical to those described in the first to sixth embodiments are denoted by the same reference numerals.

[0077] Figure 11 is a side cross-sectional view of the main part of the spindle device 10G according to the seventh embodiment. In this case, the IPM type rotor 80 is sandwiched between the first detachable ring 50a and the second detachable ring 50b.

[0078] The inner circumferential surface of the first bolt insertion hole 56 provided in the first detachable ring 50a is provided with a threaded portion. That is, the first bolt insertion hole 56 also serves as the first threaded hole 42a. The long bolt 27 is passed through the second bolt insertion hole 24 formed in the second detachable ring 50b, through the through hole 43, and then inserted into the first bolt insertion hole 56 of the first detachable ring 50a. The threaded portion of the long bolt 27 is screwed into the threaded portion of the first bolt insertion hole 56.

[0079] In the seventh embodiment, tightening the long bolt 27 fastens the IPM-type rotor 80 to the main shaft 12 via the first detachable ring 50a, and at the same time fastens the IPM-type rotor 80 to the main shaft 12 via the second detachable ring 50b. Conversely, loosening the long bolt 27 releases the fastening of the IPM-type rotor 80 by the first detachable ring 50a, and at the same time releases the fastening of the IPM-type rotor 80 by the second detachable ring 50b.

[0080] Instead of screwing the long bolt 27 into the first bolt insertion hole 56 of the first detachable ring 50a, the threaded portion of the long bolt 27 may be extended from the first bolt insertion hole 56, and a nut may be screwed onto this extended threaded portion. In this case, the machining work of creating a threaded portion in the first bolt insertion hole 56 becomes unnecessary. Also, the shapes of the first detachable ring 50a and the second detachable ring 50b will match. Therefore, it is not necessary to manufacture the first detachable ring 50a and the second detachable ring 50b separately. Furthermore, in this case, the long bolt 27 can be inserted from the first bolt insertion hole 56 of the first detachable ring 50a, and it can also be inserted from the second bolt insertion hole 24 of the second detachable ring 50b.

[0081] Thus, in the seventh embodiment as well, the IPM type rotor 80 can be easily fastened to and detached from the spindle 12 in the spindle device 10G equipped with an IPM motor.

[0082] In the seventh embodiment, as the long bolt 27 is tightened, vibration of the IPM type rotor 80 is suppressed, similar to the sixth embodiment.

[0083] (modified version) The first to seventh embodiments may be modified as follows. In the following modifications, explanations that overlap with the first to seventh embodiments will be omitted. Also, in the figures used in the following modifications, components identical to those described in the first to seventh embodiments will be denoted by the same reference numerals.

[0084] The first to seventh embodiments described above show configurations using a roughly cylindrical attachment ring 50. However, the attachment ring 50 may also be polygonal. Figure 12 shows an attachment ring 90 which is a square cylinder, a type of polygonal cylinder.

[0085] Figure 12 shows a square cylinder as an example of a polygonal cylindrical shape, but polygonal cylindrical shapes are not limited to square cylinders. Other examples of polygonal cylindrical shapes include hexagonal cylinders and octagonal cylinders.

[0086] In this embodiment using a polygonal cylindrical detachable ring 90, the same effects as those of the first to seventh embodiments described above can be obtained.

[0087] The first to seventh embodiments and their variations may be combined as appropriate, within the bounds of consistency.

[0088] As explained above, in the spindle units 10A to 10G, the rotor 14 can be fastened to the spindle 12 via the fastening portion 20 and the attachment / detachment ring 50. Therefore, when the spindle 12 and rotor 14 rotate together, vibration of the rotor 14 is suppressed. As a result, machining accuracy for the workpiece is improved.

[0089] Furthermore, the rotor 14 can be fastened to the spindle 12 regardless of whether it is an SPM type rotor 30 or an IPM type rotor 80. When the rotor 14 is an SPM type rotor 30, there are no restrictions on the shape and surface roughness of the sleeve 36. Hereinafter, an embodiment using a rotor 14 having permanent magnets 38, such as an SPM type rotor 30 or an IPM type rotor 80, has been described. However, the rotor 14 may be a rotor that does not include permanent magnets 38. An example of such a rotor is the rotor of an induction motor. It is clear that the present disclosure can be applied to this type of rotor as well. In other words, it is possible to fasten various rotors 14 to the spindle 12. In other words, with the above configuration, spindle devices 10A to 10G can be configured without being restricted by the type of motor.

[0090] Furthermore, the detachable ring 50 can be attached to and detached from the main shaft 12 without deforming the detachable ring 50, the main shaft 12, the fastening part 20, and the rotor 14. Therefore, the detachable ring 50, the main shaft 12, the fastening part 20, and the rotor 14 can be used repeatedly.

[0091] The following additional information is disclosed regarding the above embodiments.

[0092] (Note 1) This disclosure relates to a spindle unit (10A to 10G) for a machine tool, comprising a spindle (12) and a rotor (14) disposed on the outer circumference of the spindle, wherein the spindle is equipped with a detachable ring (50) that is detachably attached to the spindle and fastened to one axial end of the rotor by a first bolt (26), the spindle is provided with a fastening portion (20) that is fastened to the other axial end of the rotor by a second bolt (28), and the detachable ring has a liquid holding portion (64) capable of holding a liquid (L) in contact with the spindle, and an injection hole (68) for injecting the liquid into the liquid holding portion.

[0093] (Note 2) The spindle device of the machine tool described in Appendix 1, wherein the fastening portion is a second detachable ring (50b) separate from the detachable ring, and the second detachable ring may have a liquid holding portion capable of holding liquid in contact with the spindle, and an injection hole for injecting the liquid into the liquid holding portion.

[0094] (Note 3) In the spindle device of the machine tool described in Appendix 1 or 2, the first bolt and the second bolt may be separate components.

[0095] (Note 4) In the spindle device of the machine tool described in Appendix 3, the fastening force of the second bolt may be greater than that of the first bolt, and the second bolt fastened to the rotor may apply a tensile force toward the fastening portion to the rotor.

[0096] (Note 5) In the spindle assembly of the machine tool described in Appendix 4, the nominal diameter (D2) of the second bolt may be larger than the nominal diameter (D1) of the first bolt.

[0097] (Note 6) In the spindle device of a machine tool described in Appendix 1 or 2, the rotor has a through hole (43), and the first bolt or the second bolt passed through the through hole fastens the detachable ring to the rotor, thereby fastening the fastening portion to the rotor by the first bolt or the second bolt.

[0098] (Note 7) In the spindle device of the machine tool described in Appendix 6, the rotor may have a core (82) in which a retaining hole (84) for holding a permanent magnet (38) is formed.

[0099] (Note 8) In the spindle device of the machine tool described in Appendix 6 or 7, the first bolt and the second bolt may be the same bolt (27), and the bolt may be passed through the through hole to fasten the detachable ring to the rotor.

[0100] (Note 9) In the spindle device of the machine tool described in Appendix 6, the through hole has a threaded portion on its inner surface, the first bolt and the second bolt are separate components, and the first bolt and the second bolt may be passed through the through hole and fastened to the threaded portion.

[0101] (Note 10) In the spindle device of a machine tool described in any one of the appendices 1 to 9, the detachable ring may have a balance correction section (58) on which a balance correction member (70) for adjusting the weight balance of the detachable ring is detachably provided.

[0102] (Note 11) In the spindle device of a machine tool described in any one of the appendices 1 to 10, the detachable ring may be a polygonal cylindrical body.

[0103] (Note 12) In the spindle device of a machine tool described in any one of the appendices 1 to 11, the detachable ring may be attached to the spindle by shrink fitting.

[0104] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the intent of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of symbols]

[0105] 10A~10G…Spindle device 12…Spindle 14...Rotor 16...Clearance 20... Fastening part 22... Flange part 24...Second bolt insertion hole 26...First bolt 27...Long bolt 28, 29...Second bolt 30...SPM type rotor 32a...First end 32b...Second end portion 33...Rotor side insertion hole 36...Sleeve 38...Permanent magnet 40...Cylindrical cover 42a...First screw hole 42b...Second screw hole 43...Through hole 50, 90... Detachable rings; 50a... First detachable ring 50b...Second detachable ring 54...Ring-side insertion hole 56…First bolt insertion hole 58…Balance correction section 60...Balance correction hole 64...Liquid holding part 66…Concave space 68…Injection hole 70...Balance correction component 80...IPM type rotor 82...Core 84...Retaining hole L…Liquid

Claims

1. A spindle device of a machine tool including a spindle and a rotor disposed on an outer periphery of the spindle, a detachable ring that is detachably attached to the main shaft and fastened to one end of the rotor in an axial direction by a first bolt; the main shaft is provided with a fastening portion that is fastened to the other end of the rotor in the axial direction by a second bolt, The detachable ring has a liquid holding portion that is in contact with the main shaft and is capable of holding a liquid. an injection hole for injecting the liquid into the liquid holding portion; The spindle device of a machine tool having the above structure.

2. 2. A spindle device of a machine tool according to claim 1, wherein the fastening portion is a second detachable ring separate from the detachable ring, the second detachable ring having a liquid holding portion capable of holding liquid in contact with the spindle, and an injection hole for injecting the liquid into the liquid holding portion.

3. 3. The spindle device of a machine tool according to claim 1, wherein the first bolt and the second bolt are separate members.

4. 4. A spindle device of a machine tool according to claim 3, wherein a fastening force of the second bolt is greater than a fastening force of the first bolt, and a tensile force is applied to the rotor toward the fastening portion by the second bolt fastened to the rotor.

5. 5. A spindle device for a machine tool according to claim 4, wherein the nominal diameter of the second bolt is larger than the nominal diameter of the first bolt.

6. 3. A spindle device of a machine tool according to claim 1 or 2, wherein the rotor has a through hole, and the first bolt or the second bolt passed through the through hole fastens the detachable ring to the rotor, thereby fastening the fastening portion to the rotor by the first bolt or the second bolt.

7. 7. A spindle device for a machine tool according to claim 6, wherein said rotor has a core having a retaining hole for retaining a permanent magnet.

8. 7. A spindle device of a machine tool according to claim 6, wherein the first bolt and the second bolt are the same bolt, and the bolt is passed through the through hole to fasten the detachable ring to the rotor.

9. 7. A spindle device of a machine tool according to claim 6, wherein the through hole has a threaded portion on an inner surface, the first bolt and the second bolt are separate members, and the first bolt and the second bolt are passed through the through hole and fastened to the threaded portion.

10. 3. A spindle device of a machine tool according to claim 1, wherein said detachable ring has a balance correction portion to which a balance correction member for adjusting a weight balance of said detachable ring is detachably provided.

11. 3. The spindle device of a machine tool according to claim 1, wherein the detachable ring is a polygonal cylinder.

12. 3. The spindle device of a machine tool according to claim 1, wherein the detachable ring is attached to the spindle by shrink fitting.

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