Shaft coupling mechanism

Abstract

There is a need for a shaft coupling mechanism that allows for shorter axial dimensions of a main shaft and a rotating shaft of a rotary electric machine, said shafts coupled by a coupling.　This shaft coupling mechanism comprises: a main shaft provided with a hollow shaft hole section along an axial direction; a rotating shaft with an outer shape such that the shaft can be inserted into the shaft hole section of the main shaft; a tubular member installed between the shaft hole section and the rotating shaft, which overlap in the axial direction as a result of the rotating shaft being inserted into the shaft hole section; and a coupling that constricts the main shaft in the radial direction. The rotating shaft and the main shaft are coupled by inserting a portion of the rotating shaft into the shaft hole section of the main shaft, thus installing the tubular member in the area of overlap between the shaft hole section and the rotating shaft in the axial direction, and radially constricting the main shaft by means of the coupling at the position where the main shaft, the rotating shaft, and the tubular member overlap in the radial direction.

Description

Shaft connection mechanism

[0001] The present disclosure relates to a shaft coupling mechanism.

[0002] Conventionally, in machine tools, mechanisms have been proposed that connect the rotating shaft of a rotating electric machine to the spindle of a spindle unit that grips a tool, and transmit the power of the rotating electric machine to the spindle (see, for example, Patent Documents 1 and 2).

[0003] Japanese Patent Laid-Open No. 5-269605 Japanese Patent Laid-Open No. 2007-168023

[0004] When the rotating electric machine and the spindle unit are arranged separately, a joint is used as a member for concentrically connecting the rotating shaft of the rotating electric machine and the spindle of the spindle unit. However, when the rotating shaft and the spindle are connected with a joint, the axial dimension of the rotating shaft and the spindle increases, and the dangerous rotation speed (the rotation speed at which vibration occurs due to resonance) decreases. As a result, the upper limit of the rotation speed of the rotating electric machine is restricted. Furthermore, if the axial dimension of the rotating shaft and the spindle increases, it is thought that the rotation characteristics may also be adversely affected.

[0005] Therefore, there is a demand for a shaft coupling mechanism that can more reliably couple the rotating shaft and the main shaft and can further shorten the axial dimension of the rotating shaft and the main shaft coupled by a joint.

[0006] The shaft coupling mechanism according to the present disclosure comprises a main shaft having a hollow shaft hole portion along the axial direction, a rotating shaft having an outer shape that can be inserted into the shaft hole portion of the main shaft, a tubular member that is attached between the rotating shaft and the shaft hole portion, which overlap in the axial direction when the rotating shaft is inserted into the shaft hole portion, and a joint that radially tightens the main shaft, wherein a portion of the rotating shaft is inserted into the shaft hole portion of the main shaft, the tubular member is attached to the area where the shaft hole portion and the rotating shaft overlap in the axial direction, and the main shaft is radially tightened by the joint at a position where the main shaft, the rotating shaft, and the tubular member overlap in the radial direction, thereby coupling the rotating shaft and the main shaft.

[0007] 1 is a configuration diagram of an electric motor 10 and a spindle unit 20 connected by a shaft coupling mechanism of the first embodiment. FIG. 2 is a conceptual diagram showing the relationship between the inner diameter and outer diameter of a rotating shaft 11, a spindle 21, and a collet 30. FIG. 3 is a conceptual diagram showing a state in which a portion of the rotating shaft 11 is inserted into a shaft hole portion 22 of the spindle 21. FIG. 4 is a perspective view of the collet 30. FIG. 5 is a perspective view of a joint 40. FIG. 6 is a view of the joint 40 as viewed from the axial direction X. FIG. 7 is a diagram explaining a procedure for connecting the rotating shaft 11 of an electric motor 1 to the spindle 21 of a spindle unit 20 by the shaft coupling mechanism of the first embodiment. FIG. 8 is a diagram explaining a procedure for connecting the rotating shaft 11 of an electric motor 1 to the spindle 21 of a spindle unit 20 by the shaft coupling mechanism of the first embodiment. FIG. 9 is a diagram explaining a procedure for connecting the rotating shaft 11 of an electric motor 1 to the spindle 21 of a spindle unit 20 by the shaft coupling mechanism of the first embodiment. FIG. 10 is a diagram explaining a procedure for connecting the rotating shaft 11 of an electric motor 1 to the spindle 21 of a spindle unit 20 by the shaft coupling mechanism of the first embodiment. FIG. 10 is a perspective view showing the configuration of a collet 30A of a second embodiment. FIG. 11 is a perspective view showing the configuration of a collet 30B of a third embodiment. FIG. 12 is a perspective view showing the configuration of a collet 30C of a fourth embodiment. FIG. 13 is a perspective view showing the configuration of a collet 30D of a fifth embodiment. FIG. 14 is a configuration diagram of an electric motor 10 and a spindle unit 20 connected by a shaft connecting mechanism including a collet 30D of a fifth embodiment. FIG. 15 is a configuration diagram of a shaft connecting mechanism equipped with a joint 50 of a sixth embodiment.

[0008] Hereinafter, an embodiment of a shaft coupling mechanism according to the present disclosure will be described. The drawings attached to this specification are all schematic diagrams, and the shape, scale, aspect ratio, and the like of each part have been modified or exaggerated from the actual product in consideration of ease of understanding, etc.

[0009] FIG. 1 and other figures illustrate a coordinate system of X and Y perpendicular to each other. In this coordinate system, the direction parallel to the central axis OA of the electric motor 10 and the spindle 21 is the X direction (hereinafter also referred to as the "axial direction X"), the radial direction perpendicular to the axial direction X is the Y direction (hereinafter also referred to as the "radial direction Y"), and the circumferential direction is the R direction (hereinafter also referred to as the "circumferential direction R"). In the axial direction X shown in FIG. 1, the direction in which the spindle unit 20 is disposed is designated as X1, and the direction in which the electric motor 10 is disposed is designated as X2. In addition, in this specification, "direction" may also be referred to as "side" as appropriate.

[0010] (First embodiment) Fig. 1 is a configuration diagram of an electric motor 10 and a spindle unit 20 connected by a shaft connection mechanism of the first embodiment. Fig. 2 is a conceptual diagram showing the relationship between the inner diameter and outer diameter of a rotating shaft 11, a spindle 21, and a collet 30. Fig. 3 is a conceptual diagram showing a state in which a portion of the rotating shaft 11 is inserted into a shaft hole portion 22 of the spindle 21. Fig. 4 is a perspective view of the collet 30. Fig. 5 is a perspective view of a joint 40. Fig. 6 is a view of the joint 40 as viewed from the axial direction X. Note that Fig. 1 shows a cross-sectional view of the portion where the rotating shaft 11 and the spindle 21 are connected.

[0011] The shaft coupling mechanism of the first embodiment is a mechanism that couples the rotating shaft 11 of the electric motor 10 to the spindle 21 of the spindle unit 20, thereby transmitting the power of the electric motor 10 to the spindle 21. The electric motor 10 of the first embodiment (and other embodiments) is a rotating electric machine used as a power source for a machine tool, for example, but its use is not limited to machine tools.

[0012] In the electric motor 10 shown in Fig. 1, the rotating shaft 11 is a shaft member that supports a rotor (not shown) provided inside. The rotating shaft 11 is inserted so as to pass through the axial center of the rotor and is fixed coaxially with the rotor. A pair of bearings (not shown) are provided on both sides of the rotating shaft 11 in the axial direction X. The bearings are members that rotatably support the rotating shaft 11 and are fixed inside the housing 12.

[0013] The housing 12 is a member that holds the rotating shaft 11 via bearings. The rotating shaft 11 is held by the housing 12, bearings, etc. so as to be rotatable about the axial direction X. The rotating shaft 11 has an outer diameter D1 that allows it to be inserted into the shaft hole 22 of the main shaft 21 (see FIG. 2).

[0014] It is sufficient that rotating shaft 11 has an "outer shape" that allows it to be inserted into shaft hole portion 22 of main shaft 21. In the present embodiment, the outer shape of rotating shaft 11 is circular when viewed in cross section in the radial direction Y of rotating shaft 11, but the outer shape of rotating shaft 11 may be an outer shape that has a key groove, a flat portion, a tapered portion, or the like, or an outer shape with a rectangular cross section. In this way, rotating shaft 11 is not limited to being circular, and may have any outer shape as long as it can be inserted into shaft hole portion 22 of main shaft 21.

[0015] The spindle unit 20 is a device that rotatably holds the spindle 21. The spindle 21 is a part that rotates or fixedly holds a tool holder (not shown) that grips a tool on the side opposite to the electric motor 10 (X1 side). The spindle 21 has a hollow shaft hole portion 22 that extends along the axial direction X. In this embodiment, the shaft hole portion 22 is a through hole that passes through the entire length of the spindle 21, but is not limited to this and may be a bottomed hole that is closed on the X1 side of the spindle 21.

[0016] Shaft hole portion 22 has an inner diameter d1 that is larger than outer diameter D1 of main shaft 21 (see FIG. 2 ). Therefore, as shown in FIG. 3 , when a portion of rotating shaft 11 is inserted into shaft hole portion 22, an annular gap s is formed between shaft hole portion 22 and main shaft 21.

[0017] 1, with a portion of the rotating shaft 11 inserted into the shaft hole 22, a collet 30 as a cylindrical member is attached to the gap s between the shaft hole 22 and the main shaft 21. In addition, with a portion of the rotating shaft 11 inserted into the shaft hole 22, a joint 40 is attached to the outside of the main shaft 21.

[0018] The collet 30 is a component that is mounted between the shaft hole 22 and the rotary shaft 11, which overlap in the axial direction X, with a portion of the rotary shaft 11 inserted into the shaft hole 22. By mounting the collet 30 between the shaft hole 22 and the rotary shaft 11, which overlap in the axial direction X, the shaft hole 22 of the spindle 21 and the rotary shaft 11 can be brought into close contact with each other with the collet 30 sandwiched between them. The outer diameter D2 and inner diameter d2 of the collet 30 shown in FIG. 2 can be set appropriately depending on the inner diameter d1 of the shaft hole 22 of the spindle 21 and the outer diameter D1 of the rotary shaft 11 to be combined. This increases the degree of freedom in the combination of the spindle 21 and the rotary shaft 11.

[0019] It is desirable that the length of the collet 30 in the axial direction X be the same as the length L (see Figure 3) of overlap between the axial hole portion 22 and the rotating shaft 11 in the axial direction X when a portion of the rotating shaft 11 is inserted into the axial hole portion 22.

[0020] As shown in Fig. 4, the collet 30 is formed in a cylindrical shape. The inner diameter d2 of the collet 30 is set to a dimension slightly larger than the outer diameter D1 (see Fig. 2) of the rotating shaft 11 so that the collet 30 can be fitted onto the rotating shaft 11. Furthermore, the outer diameter D2 of the collet 30 is set to a dimension slightly smaller than the inner diameter d1 (see Fig. 2) of the axial hole 22 (spindle 21) so that the collet 30 can be fitted into the axial hole 22.

[0021] Joint 40 is a component (fastener) for fastening main shaft 21 in radial direction Y. As shown in FIG. 5 , joint 40 is formed in a substantially cylindrical shape and has a slit 41 extending along axial direction X. As shown in FIG. 6 , joint 40 has a bolt hole 42 on one side of slit 41 and a threaded hole 43 on the other side. A bolt (e.g., a hexagon socket head cap screw) 44 is inserted into bolt hole 42. Threaded hole 43 has a female thread 43a formed therein that can be threadedly engaged with a male thread 44a formed on bolt 44. By inserting bolt 44 into bolt hole 42, threading the male thread 44a into the female thread 43a of threaded hole 43, and turning bolt 44 in the fastening direction, main shaft 21 (see FIG. 1 ) can be fastened in radial direction Y.

[0022] 5 may be the same as the outer diameter D3 (see FIG. 2) of the main shaft 21. When the joint 40 is fitted onto the main shaft 21, a gap is formed between the bolt hole 42 and the screw hole 43 (corresponding to the slit 41).

[0023] Next, a procedure for connecting the rotating shaft 11 of the electric motor 1 and the spindle 21 of the spindle unit 20 by the shaft connecting mechanism of the first embodiment will be described. Figures 7A to 7D are diagrams for explaining the procedure for connecting the rotating shaft 11 of the electric motor 1 and the spindle 21 of the spindle unit 20 by the shaft connecting mechanism of the first embodiment.

[0024] First, as shown in Fig. 7A, collet 30 is fitted onto rotating shaft 11 of electric motor 1, and joint 40 is fitted onto main shaft 21 of main shaft unit 20. Note that Fig. 7A shows a state in which joint 40 fitted onto main shaft 21 has been moved to the X1 side of main shaft 21, but the subsequent work may be performed in a state in which joint 40 fitted onto main shaft 21 has been moved to the tip side (X2 side) of main shaft 21.

[0025] 7B, the spindle unit 20 is moved to the X2 side, and the spindle 21 (shaft hole portion 22) is inserted onto the rotating shaft 11 of the electric motor 1. As a result, the rotating shaft 11 is inserted into the spindle 21. The length by which the rotating shaft 11 is inserted into the spindle 21 is assumed to be set in advance.

[0026] Next, as shown in FIG. 7C , the collet 30 fitted onto the rotary shaft 11 is moved toward the main shaft 21 (X1 side) and attached to the gap where the rotary shaft 11 and the main shaft 21 overlap in the axial direction X.

[0027] Next, as shown in Figure 7D, the joint 40 fitted onto the main shaft 21 is moved radially toward the X2 side to a position where the main shaft 21, the rotating shaft 11, and the collet 30 overlap. Then, the bolts 44 (see Figure 6) of the joint 40 are turned in the fastening direction to tighten the main shaft 21 radially. This allows the rotating shaft 11 and the main shaft 21 to be connected by the joint 40 via the collet 30.

[0028] According to the shaft coupling mechanism of the first embodiment, when coupling the main shaft 21 and the rotating shaft 11, a portion of the rotating shaft 11 is inserted into the shaft hole 22 of the main shaft 21 so that the shaft hole 22 and the rotating shaft 11 overlap in the axial direction X. This allows the dimension of the main shaft 21 and the rotating shaft 11 in the axial direction X to be shorter than in a mechanism that couples the ends of the respective shafts by butting them together. This allows the dangerous rotation speed to be higher than in the above mechanism in which the dimension of the main shaft 21 and the rotating shaft 11 in the axial direction X is longer, thereby suppressing the problem of restrictions on the upper limit of the rotation speed. Furthermore, the main shaft 21 is tightened in the radial direction Y by the joint 40 at a position where the main shaft 21, the rotating shaft 11, and the collet 30 overlap in the radial direction Y, allowing for a more reliable coupling of the rotating shaft 11 and the main shaft 21.

[0029] Second Embodiment The shaft coupling mechanism of the second embodiment differs from the first embodiment in that the collet 30A is provided with a slit 31. The other configurations of the shaft coupling mechanism of the second embodiment are the same as those of the first embodiment. Therefore, in the second embodiment, only the collet 30A is illustrated, and the electric motor 10 and spindle unit 20 including the shaft coupling mechanism are not illustrated.

[0030] Figure 8 is a perspective view showing the configuration of the collet 30A of the second embodiment. As shown in Figure 8, the collet 30A of the second embodiment has multiple slits 31 on its side. The slits 31 are open on one side and closed on the other side in the axial direction X. In other words, the slits 31 extend from one end to the other end in the axial direction X, but do not reach the other end.

[0031] By providing multiple slits 31 on the side of the collet 30A, the deformation amount of the collet itself can be increased when the main shaft 21 is tightened in the radial direction Y by the joint 40, thereby increasing the clamping margin between the main shaft 21 (shaft hole portion 22) and the rotating shaft 11.

[0032] 8 shows an example in which six slits 31 are provided in the collet 30A, but the number of slits 31 may be one to five, or seven or more. When multiple slits 31 are provided in the collet 30A, it is desirable that the slits 31 be arranged at equal intervals along the circumferential direction R, but they may also be arranged irregularly or partially along the circumferential direction R. Furthermore, when multiple slits 31 are provided, the orientation of the open sides of the slits 31 may be staggered in the circumferential direction R as shown in FIG. 8, or may be in the same direction.

[0033] (Third Embodiment) The shaft coupling mechanism of the third embodiment differs from the first embodiment in that the collet 30B is provided with a hole 32. The other configurations of the shaft coupling mechanism of the third embodiment are the same as those of the first embodiment. Therefore, in the third embodiment, only the collet 30B is illustrated, and the electric motor 10 and spindle unit 20 including the shaft coupling mechanism are not illustrated.

[0034] 9 is a perspective view showing the configuration of a collet 30B according to the third embodiment. The collet 30B according to the third embodiment has a plurality of holes 32 penetrating in the radial direction Y. By providing a plurality of holes 32 in the collet 30B, the amount of deformation of the collet itself can be increased when the main shaft 21 is tightened in the radial direction Y by the joint 40, and therefore the interference between the main shaft 21 (shaft hole 22) and the rotating shaft 11 can be increased.

[0035] 9 shows an example in which elliptical holes 32 are provided in the collet 30B, but the shape of the holes 32 is not limited to elliptical and may be, for example, circular, rectangular, diamond-shaped, or any other shape. The shapes and sizes of the holes 32 in one collet 30B may be the same or different. Furthermore, the arrangement, number, etc. of the holes 32 provided in the collet 30B can be set as appropriate and are not limited to the example shown in the figure.

[0036] (Fourth Embodiment) The shaft coupling mechanism of the fourth embodiment differs from the first embodiment in that the collet 30C is divided. The other configurations of the shaft coupling mechanism of the fourth embodiment are the same as those of the first embodiment. Therefore, in the fourth embodiment, only the collet 30C is illustrated, and the electric motor 10 and spindle unit 20 including the shaft coupling mechanism are not illustrated.

[0037] Fig. 10 is a perspective view showing the configuration of a collet 30C according to the fourth embodiment. As shown in Fig. 10, the collet 30C according to the fourth embodiment is divided into two parts in the radial direction Y. That is, the collet 30C according to the fourth embodiment is composed of a first collet 33 and a second collet 34. By dividing the collet 30C into two parts in the radial direction Y, the tolerances of the rotating shaft 11 and the main shaft 21 (shaft hole portion 22) are absorbed when the spindle 21 is tightened in the radial direction Y by the joint 40, and the tightness of contact between the rotating shaft 11, the main shaft 21 (shaft hole portion 22), and the collet 30C can be further improved.

[0038] 10 shows a configuration in which the collet 30C is divided into two in the radial direction Y, the number of divisions of the collet 30C is not limited to two and may be three or more. Also, a slit that is open at both ends along the axial direction X may be formed on the side surface of the collet, so that the cross section is approximately C-shaped.

[0039] Fifth Embodiment The shaft coupling mechanism of the fifth embodiment differs from the first embodiment in that the collet 30D is provided with a flange 35. The other configurations of the shaft coupling mechanism of the fifth embodiment are the same as those of the first embodiment. Therefore, in the fifth embodiment, only the collet 30D is illustrated, and the electric motor 10 and spindle unit 20 including the shaft coupling mechanism are not illustrated.

[0040] Fig. 11 is a perspective view showing the configuration of a collet 30D according to the fifth embodiment. Fig. 12 is a configuration diagram of an electric motor 10 and a spindle unit 20 connected by a shaft connecting mechanism including the collet 30D according to the fifth embodiment.

[0041] As shown in Fig. 11 , collet 30D of the fifth embodiment has a flange (abutment portion) 35 at the end on the X2 side in axial direction X. Flange 35 is a portion that determines the position at which collet 30D is attached to shaft hole 22 of spindle 21. By providing flange 35 on collet 30D, when collet 30D fitted onto rotating shaft 11 is moved toward spindle 21 as shown in Fig. 12 , collet 30D can be prevented from moving more than necessary toward spindle 21 (X1 side) from a predetermined position.

[0042] In this way, in the collet 30D of the fifth embodiment, when the collet 30D is attached to the main shaft 21, the collet 30D can be attached to an appropriate position relative to the main shaft 21 (shaft hole portion 22) by moving the collet 30D toward the main shaft 21 until the flange 35 abuts against the main shaft 21.

[0043] Sixth Embodiment FIG. 13 is a configuration diagram of a shaft coupling mechanism including a joint 50 of a sixth embodiment. As shown in FIG. 13 , the joint 50 of the sixth embodiment includes an outer tapered ring 51 and an inner tapered ring 52. The outer tapered ring 51 is a component disposed on the outer side of the joint 50 in the radial direction Y. The inner peripheral surface of the outer tapered ring 51 is provided with a tapered surface that linearly increases in diameter from the X1 end toward the X2 end. The inner tapered ring 52 is a component disposed on the inner side of the joint 50 in the radial direction Y. The outer peripheral surface of the inner tapered ring 52 is provided with a tapered surface that linearly increases in diameter from the X1 end toward the X2 end. The tapered surfaces of the outer tapered ring 51 and the inner tapered ring 52 are formed so that when the outer tapered ring 51 is fitted onto the inner tapered ring 52, as shown in FIG. 13 , the tapered surfaces of the outer tapered ring 51 and the inner tapered ring 52 fit together without any gaps.

[0044] 7A , for example, the coupling 50 can be fitted onto the main shaft 21 in a state in which the rotating shaft 11 of the electric motor 1 and the main shaft 21 of the main shaft unit 20 are spaced apart in the axial direction X. With the coupling 50 fitted onto the main shaft 21, the main shaft 21 is fitted onto the rotating shaft 11, and the collet 30 fitted onto the rotating shaft 11 is moved toward the main shaft 21 (X1 side) and installed in the gap where the rotating shaft 11 and the main shaft 21 overlap in the axial direction X. Next, the coupling 50 fitted onto the main shaft 21 is moved radially toward the X2 side to a position where the main shaft 21, the rotating shaft 11, and the collet 30 overlap.

[0045] 13 , when the outer tapered ring 51 is pressed in the X2 direction and the inner tapered ring 52 is pressed in the X1 direction, the inner tapered ring 52 is compressed in the direction of the central axis OA relative to the outer tapered ring 51, thereby tightening the main shaft 21 in the radial direction. This allows the rotating shaft 11 and the main shaft 21 to be connected by the joint 40 via the collet 30. Furthermore, with the joint 50 of this embodiment, there is no imbalance in weight in the circumferential direction, so that the generation of vibration can be suppressed and the power of the electric motor 10 can be transmitted to the main shaft 21 more efficiently.

[0046] When the main shaft 21 is tightened in the radial direction, the outer tapered ring 51 may be pressed in the X2 direction to fix the inner tapered ring 52 so as not to move in the axial direction X, or the stator and the inner tapered ring 52 may be pressed in the X1 direction X to prevent the outer tapered ring 51 from moving in the axial direction X. A member (not shown) that presses the inner tapered ring 52 and / or the outer tapered ring 51 in the axial direction X may have any configuration.

[0047] The inclination directions of the tapered surfaces of the outer tapered ring 51 and the inner tapered ring 52 may be reversed. That is, the inner peripheral surface of the outer tapered ring 51 may be provided with a tapered surface that linearly increases in diameter from the X1-side end toward the X2-side end, and the outer peripheral surface of the inner tapered ring 52 may be provided with a tapered surface that increases in diameter from the X2-side end toward the X1-side end.

[0048] (Modifications) Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. Furthermore, these embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these.

[0049] The collet 30 of the first embodiment may be divided into a plurality of collets in the axial direction X and used.

[0050] The slit 31 provided in the collet 30A of the second embodiment may be applied to the collets 30B to 30D of the third to fifth embodiments, and the hole 32 provided in the collet 30B of the third embodiment may be applied to the collet 30C of the fourth embodiment or the collet 30D of the fifth embodiment. Also, in the collet 30A of the second embodiment, the slit 31 may be formed in a spiral shape along the circumferential direction R.

[0051] The flange 35 of the fifth embodiment may be annular as shown in FIG. 11, or may be provided partially.

[0052] As is clear from the description of each embodiment, the "cylindrical member" (collet) in this disclosure is broadly interpreted and may have a slit 31 or a hole 32. Furthermore, the cylindrical member does not have to be integral (it may be separable) when not mounted between the rotating shaft 11 and the main shaft 21.

[0053] The following supplementary notes are further disclosed regarding the above embodiment. (Supplementary Note 1) A shaft coupling mechanism comprising: a main shaft (21) having a hollow shaft hole (22) along the axial direction; a rotating shaft (11) having an outer shape that can be inserted into the shaft hole of the main shaft; a tubular member (30) mounted between the shaft hole and the rotating shaft, which overlap in the axial direction when the rotating shaft is inserted into the shaft hole; and a joint (40) that radially tightens the main shaft, wherein a portion of the rotating shaft is inserted into the shaft hole of the main shaft, the tubular member is mounted in a region where the shaft hole and the rotating shaft overlap in the axial direction, and the main shaft is radially tightened by the joint at a position where the main shaft, the rotating shaft, and the tubular member overlap in the radial direction, thereby coupling the rotating shaft and the main shaft. (Supplementary Note 2) The tubular member (30A) has a slit (31) extending from one axial end to the other axial end. (Note 3) The cylindrical member (30B) has a hole (32) that penetrates in the radial direction. (Note 4) The cylindrical member (30C) is divided in the radial direction. (Note 5) The cylindrical member (30D) has an abutment portion (35) that determines the position at which the cylindrical member (30D) is attached to the axial hole portion of the spindle.

[0054] 10: electric motor (rotating electric machine), 11: rotating shaft, 20: spindle unit, 21: spindle, 22: shaft hole portion, 30, 30A, 30B, 30C, 30D: collet (cylindrical member), 31: slit, 32: hole portion, 35: flange (butting portion), 40, 50: joint

Claims

1. A shaft coupling mechanism comprising: a main shaft having a hollow shaft hole portion extending along the axial direction; a rotating shaft having an outer shape that can be inserted into the shaft hole portion of the main shaft; a tubular member that is fitted between the shaft hole portion and the rotating shaft, which overlap in the axial direction when the rotating shaft is inserted into the shaft hole portion; and a joint that radially tightens the main shaft, wherein a part of the rotating shaft is inserted into the shaft hole portion of the main shaft, the tubular member is fitted in a region where the shaft hole portion and the rotating shaft overlap in the axial direction, and the main shaft is radially tightened by the joint at a position where the main shaft, the rotating shaft, and the tubular member overlap in the radial direction, thereby coupling the rotating shaft and the main shaft.

2. The shaft coupling mechanism according to claim 1, wherein the cylindrical member has a slit extending from one end to the other end in the axial direction.

3. The shaft coupling mechanism according to claim 1 or 2, wherein the cylindrical member has a hole passing therethrough in the radial direction.

4. A shaft connecting mechanism as claimed in any one of claims 1 to 3, wherein the cylindrical member is divided in the radial direction.

5. A shaft coupling mechanism as set forth in any one of claims 1 to 4, wherein the cylindrical member has a stopper portion that determines the position at which it is attached to the shaft hole portion of the main shaft.

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