Shaft connection mechanism

Abstract

A shaft connection mechanism is desired which reliably transmits power of a rotating shaft to a main shaft and is less susceptible to displacement of the main shaft in the axial direction. The shaft connection mechanism includes: a main shaft having a shaft hole portion; a connecting member having an inner hole portion; the rotating shaft can be inserted into the shaft hole part and the inner hole part; a first rolling body; the main shaft is provided with a first inner groove part, the connecting component is provided with a second inner groove part, the rotating shaft is provided with a first outer groove part and a second outer groove part, the main shaft and the connecting component are connected in the axial direction, and the rotating shaft is inserted into the shaft hole part and the inner hole part. The first rolling body is disposed between the second outer groove portion of the rotating shaft and the second inner groove portion of the main shaft, and the second rolling body is disposed between the first outer groove portion of the rotating shaft and the first inner groove portion of the connecting member, so that the rotating shaft and the main shaft can move freely in the axial direction. And the power of the rotating shaft is transmitted to the rotating shaft through the first rolling body and the second rolling body.

Description

Technical Field

[0001] This disclosure relates to a shaft connection mechanism. Background Technology

[0002] Previously, a mechanism has been proposed in which the rotating shaft of a rotary motor is connected to the spindle of a tool-holding spindle unit in a machine tool to transmit the power of the rotary motor to the spindle (see, for example, Patent Documents 1 and 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 5-269605

[0006] Patent Document 2: Japanese Patent Application Publication No. 2007-168023 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] When the rotary motor and the spindle unit are configured independently, the connector is used as a component to concentrically connect the rotary shaft of the rotary motor to the spindle unit's spindle. However, if a connector is used to connect the rotary shaft and the spindle, the axial dimensions of the rotary shaft and the spindle become longer, thus lowering the critical speed (the speed at which vibration occurs due to resonance). As a result, an upper limit on the speed is imposed in the rotary motor. Furthermore, if the axial dimensions of the rotary shaft and the spindle become longer, it may also adversely affect the rotational characteristics.

[0009] On the other hand, the axial dimensions of the rotating shaft and the spindle can be shortened by changing the joint structure. However, during workpiece machining, if the spindle is displaced axially due to heat, the rotating shaft of the rotary motor may be pushed axially by the displaced spindle, potentially leading to premature damage to the rotary motor. Furthermore, considering the spindle's axial displacement due to heat, a gap can be pre-set between the spindle and the rotating shaft. However, if a gap is set between the spindle and the rotating shaft, it is difficult to reliably transmit the power from the rotating shaft to the spindle.

[0010] Therefore, a shaft connection mechanism is desired that reliably transmits the power of the rotating shaft to the main shaft and is not easily affected by the axial displacement of the main shaft.

[0011] Solution for solving the problem

[0012] The shaft connection mechanism disclosed herein comprises: a main shaft having a hollow shaft hole portion along the axial direction; a connecting member having a hollow inner hole portion along the axial direction and being axially connected to the main shaft; a rotating shaft having an external shape that can be inserted into the shaft hole portion of the main shaft and the inner hole portion of the connecting member when the main shaft and the connecting member are axially connected; a first rolling element disposed between the main shaft and the rotating shaft; and a second rolling element disposed between the connecting member and the rotating shaft. The main shaft has a first inner groove portion on the inner circumferential surface of the shaft hole portion that can engage with the first rolling element, and the connecting member has a second inner groove portion on the inner circumferential surface of the inner hole portion that can engage with the second rolling element. The rotating shaft has a first outer groove on its outer circumferential surface that engages with the first rolling element and a second outer groove that engages with the second rolling element. With the main shaft and the connecting member axially connected and the rotating shaft inserted into the shaft hole of the main shaft and the inner hole of the connecting member, the first rolling element is disposed between the second outer groove of the rotating shaft and the second inner groove of the main shaft, and the second rolling element is disposed between the first outer groove of the rotating shaft and the first inner groove of the connecting member. Thus, the rotating shaft and the main shaft can move freely in the axial direction, and the power of the rotating shaft is transmitted to the rotating shaft via the first and second rolling elements. Attached Figure Description

[0013] Figure 1 This is a configuration diagram of the motor 10 and the spindle unit 20 connected by the shaft connection mechanism of the first embodiment.

[0014] Figure 2A yes Figure 1 A magnified view of a portion of the image.

[0015] Figure 2B yes Figure 2A The s1-s1 cross-sectional view.

[0016] Figure 3 This is an exploded perspective view of the shaft connection mechanism of the first embodiment.

[0017] Figure 4 This is a plan view of the rotation axis 11 from the X2 side.

[0018] Figure 5 This is a plan view of the main axis 21 from the X2 side.

[0019] Figure 6A This is a plan view of the connecting member 30 from the X2 side.

[0020] Figure 6B This is a plan view of the connecting member 30 from the X1 side.

[0021] Figure 7 This is a perspective view of the shaft connection mechanism according to the first embodiment.

[0022] Figure 8 This diagram illustrates the direction in which the main shaft 21 and the connecting component 30 are pushed.

[0023] Figure 9 This is a perspective view of the shaft connection mechanism according to the second embodiment.

[0024] Figure 10 This is a perspective view of the shaft connection mechanism according to the third embodiment.

[0025] Figure 11 This is a perspective view of the shaft connection mechanism according to the fourth embodiment.

[0026] Figure 12A This is a conceptual cross-sectional view showing the configuration of the shaft connection mechanism in the fifth embodiment.

[0027] Figure 12B This is a conceptual cross-sectional view showing the configuration of the shaft connection mechanism in the fifth embodiment.

[0028] Figure 13A This is a conceptual cross-sectional view showing a different configuration from the shaft connection mechanism in the fifth embodiment.

[0029] Figure 13B This is a conceptual cross-sectional view showing a different configuration from the shaft connection mechanism in the fifth embodiment. Detailed Implementation

[0030] The following describes an embodiment of the shaft connection mechanism of this disclosure. The accompanying drawings are schematic diagrams, and the shapes, proportions, and dimensional ratios of the parts have been altered or exaggerated from the actual object for ease of understanding.

[0031] exist Figure 1 The coordinate system contains mutually orthogonal coordinates X, Y, and Z. In this coordinate system, the direction parallel to the central axis OA of the rotation axis 11 of the motor 10 and the main axis 21 of the main spindle unit 20 is designated as the X direction (hereinafter also referred to as "axial X"). In the axial X, the direction in which the main spindle unit 20 is located is designated as X1, and the direction in which the motor 10 is located is designated as X2.

[0032] Furthermore, one of the directions orthogonal to the X-axis is designated as the Y-direction, and the other as the Z-direction. The Y-direction and the Z-direction are orthogonal when viewed from the X-axis. In the Y-direction, one direction is designated as Y1, and the other as Y2. In the Z-direction, one direction is designated as Z1, and the other as Z2. Additionally, the circumferential direction centered on the central axis OA of the rotation axis 11, the main shaft 21, and the connecting member 30 is designated as the R-direction (hereinafter also referred to as "circumferential direction" or "circumferential R"). In this specification, the "~direction" is also appropriately referred to as "~side".

[0033] (First Embodiment)

[0034] Figure 1 This is a configuration diagram of the motor 10 and the spindle unit 20 connected by the shaft connection mechanism of the first embodiment. Figure 1 In the middle, the shape of the connecting structural component 30 is simplified. Figure 2A yes Figure 1 A magnified view of a portion of the image. Figure 2B yes Figure 2A The s1-s1 cross-sectional view. Figure 2B The illustrations of the first rolling element 41 and the second rolling element 42 are omitted in the text. Figure 3 This is an exploded perspective view of the shaft connection mechanism according to the first embodiment. Figure 3 In the figure, only the portions of the rotating shaft 11 and the main shaft 21 that are exposed from the motor 10 and the main shaft unit 20 are shown (the same applies to other related figures). Figure 4 This is a plan view of the rotation axis 11 from the X2 side. Figure 5 This is a plan view of the main axis 21 from the X2 side. Figure 6A This is a plan view of the connecting member 30 from the X2 side. Figure 6B This is a plan view of the connecting member 30 from the X1 side.

[0035] The shaft connection mechanism of the first embodiment is as follows: Figure 1 and Figure 2A As shown, a mechanism is used to connect the rotating shaft 11 of the motor 10 to the spindle 21 of the spindle unit 20 via a connecting member 30, a first rolling element 41, and a second rolling element 42, thereby transmitting the power of the motor 10 from the rotating shaft 11 to the spindle 21. Although the motor 10 in the first embodiment (and other embodiments) is a rotary motor used, for example, as a power source for a machine tool, its application is not limited to machine tools.

[0036] exist Figure 1In the electric motor 10 shown, the rotating shaft 11 is a shaft member that supports a rotor (not shown) disposed inside it. The rotor rotates by magnetic interaction with a rotating magnetic field, which is formed by a stator (not shown) disposed in the housing 12. The rotation of the rotor generates power (rotational force) in the rotating shaft 11. The rotating shaft 11 is inserted through the 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 along the axial direction X. The bearings are components that rotatably support the rotating shaft 11 and are fixed inside the housing 12. The housing 12 holds the rotating shaft 11 in place by means of the bearings. The rotating shaft 11 is rotatably held about the axial direction X by means of the housing 12, the bearings, etc.

[0037] (Rotation axis)

[0038] like Figure 3 As shown, the rotating shaft 11 has a shaft hole 22 (described later) for inserting into the main shaft 21 and an inner hole 31 (described later) for inserting into the connecting member 30. The rotating shaft 11 only needs to have an "outline" in the portion exposed from the motor 10 that allows insertion into the shaft hole 22 of the main shaft 21 and the inner hole 31 of the connecting member 30. The following description of the outline of the rotating shaft 11 refers to the portion of the rotating shaft 11 exposed from the motor 10.

[0039] like Figure 4 As shown, the rotating shaft 11 is approximately circular when viewed from the axial direction X, and a first outer groove 13 and a second outer groove 14 are provided on its outer circumferential surface. In the following description, the first outer groove 13 and the second outer groove 14 are also referred to as "outer grooves" unless otherwise distinguished.

[0040] The first outer groove 13 is a groove that can engage with the first rolling element 41 (described later), and is configured to extend along the axial direction X (see reference). Figure 3 The cross-sectional shape of the first outer groove 13 is approximately half the cross-sectional shape of the first rolling element 41 (approximately semi-circular arc). The cross-sectional shape of the first outer groove 13 can be any combination of curved surfaces or straight lines, and is not limited to the approximately semi-circular arc shape of this embodiment, as long as it ensures power transmission to the rotating shaft 11 or the main shaft 21 when the first rolling element 41 moves in the circumferential direction R. Figure 4 As shown, the first outer groove 13 is positioned in the Z1 and Z2 directions respectively, with the central axis OA sandwiched in the middle. The number of the first outer groove 13 is not limited to 4. Although it is desirable for the first outer groove 13 to be equally distributed with respect to the central axis OA, it can be point-symmetric with respect to the central axis OA, or line-symmetric with respect to the straight line intersecting the central axis OA.

[0041] The second outer groove 14 is a groove that can engage with the second rolling element 42 (described later), and is configured to extend along the axial direction X (see reference). Figure 3 The cross-sectional shape of the second outer groove 14 is approximately half the cross-sectional shape of the second rolling element 42 (approximately semi-circular). The cross-sectional shape of the second outer groove 14, like the cross-sectional shape of the first outer groove 13, is not limited to an approximately semi-circular shape. Figure 4 As shown, the second outer groove 14 is positioned in the Y1 and Y2 directions respectively, with the central axis OA sandwiched in the middle. The first outer groove 13 and the second outer groove 14 are arranged at equal intervals (90° intervals in this example) with the central axis OA as the center when viewed from the X-axis of the rotating shaft 11.

[0042] The shape of the rotating shaft 11 can also be, for example, having a keyway, a flat portion, or a tapered portion in one part. Furthermore, for example, it can be configured such that the outer groove portion of the rotating shaft 11 is formed as a cylindrical member, and the cylindrical member can be detachably fitted into the interior of this member. Thus, the rotating shaft 11 is not limited to any particular embodiment as long as it can be inserted into the shaft hole 22 of the main shaft 21 and the inner hole 31 of the connecting member 30 and has an outer groove portion.

[0043] (Main axis)

[0044] Spindle unit 20 (reference) Figure 1 This is a machine that rotatably holds the spindle 21. The spindle 21 is the part that, on the side opposite to the motor 10 (X1 side), allows the tool holder (not shown) holding the tool to rotate or remain in a fixed state. Figure 3 As shown, the spindle 21 has a hollow shaft hole portion 22 extending along the axial direction X. The shaft hole portion 22 is a through hole for the insertion of the rotating shaft 11. In this embodiment, although the shaft hole portion 22 is a through hole that extends through the entire length of the spindle 21, it is not limited to this. It may be a closed bottom hole on the X1 side of the spindle 21, or it may be configured with steps inside.

[0045] The shaft hole portion 22 has an inner diameter into which the rotating shaft 11 can be inserted. The inner diameter of the shaft hole portion 22 is set to a degree that allows for an appropriate clearance between the shaft hole portion 22 and the rotating shaft 11 when the rotating shaft 11 is inserted.

[0046] like Figure 5 As shown, the spindle 21 has a first inner groove 23 and a second inner groove 24 on the inner circumferential surface of the shaft hole 22. In the following description, the first inner groove 23 and the second inner groove 24 are also referred to as "inner grooves" unless otherwise distinguished.

[0047] The first inner groove 23 is a groove that engages with the first rolling element 41, and is configured to extend along the axial direction X (see reference). Figure 3The cross-sectional shape of the first inner groove 23 is approximately half (approximately semi-circular) of the cross-sectional shape of the first rolling element 41. The cross-sectional shape of the first inner groove 23, like the cross-sectional shape of the first outer groove 13, is not limited to an approximately semi-circular shape. Figure 5 As shown, the first inner groove 23 is provided on the Z1 side and the Z2 side respectively, with the central axis OA sandwiched in the middle.

[0048] The second inner groove 24 is configured to extend along the axial direction X (see reference). Figure 3 The cross-sectional shape of the second inner groove 24 is approximately half (approximately semi-circular) of the cross-sectional shape of the second rolling element 42. The cross-sectional shape of the second inner groove 24, like that of the first inner groove 23, is not limited to a semi-circular shape. Figure 5 As shown, the second inner groove 24 is respectively provided on the Y1 side and Y2 side, with the central axis OA sandwiched in the middle. The configuration of the second inner groove 24 relative to the central axis OA can be any configuration that is in the same phase as the configuration of the second outer groove 14 provided on the rotation shaft 11 around the central axis OA.

[0049] The first inner groove portion 23 and the second inner groove portion 24 are arranged at equal intervals (90° intervals in this example) with the central axis OA as the center when viewed from the X-axis of the main shaft 21. The arrangement of the first inner groove portion 23 and the second inner groove portion 24 when viewed from the X-axis is not limited to the above arrangement, just like the outer groove portion provided on the rotation shaft 11.

[0050] like Figure 3 As shown, the spindle 21 has a spindle recess 25 and a spindle protrusion 26. The spindle recess 25 is a recess that engages with the connecting protrusion 35 (described later) of the connecting member 30 in the axial direction X. Figure 5 As shown, the spindle recess 25 is respectively provided on the Y1 side and Y2 side, clamping the central axis OA in the middle. The spindle protrusion 26 is a protrusion that fits into the connecting recess 36 (described later) of the connecting member 30 in the axial direction X. Figure 5 As shown, the spindle protrusion 26 is positioned on the Z1 side and the Z2 side respectively, with the central axis OA sandwiched in the middle.

[0051] like Figure 5 As shown, the spindle protrusion 26 has a threaded hole 27. An internal thread is formed on the inner circumferential surface of the threaded hole 27, which can engage with the first set of bolts (first push member / phase adjustment part) 28. For example... Figure 5 As shown, the screw holes 27 are respectively provided on the Z1 side and Z2 side when viewed from the X-axis of the spindle 21. Furthermore, the screw holes 27 clamp the central axis OA in the middle and open in mutually parallel directions.

[0052] The first set of bolts 28 are components used to apply preload to the first rolling element 41 disposed between the main shaft 21 and the rotating shaft 11. The outer circumferential surface of the first set of bolts 28 has an external thread that engages with the internal thread of the threaded hole 27. With the main shaft 21 and the connecting member 30 already engaged, if the first set of bolts 28 are engaged with the internal thread of the threaded hole 27 and rotated in the tightening direction (e.g., clockwise), the bolt tip will protrude from the main shaft protrusion 26 and be pushed against the connecting protrusion 35 of the connecting member 30 (described later).

[0053] When the bolt tip is pushed against the connecting protrusion 35 of the connecting member 30, the connecting member 30 is pushed in the circumferential direction R in a direction spaced apart from the main shaft 21, and the positional relationship between the connecting member 30 and the main shaft 21 changes. Therefore, for the first rolling element 41 disposed between the main shaft 21 and the rotating shaft 11, a preload is applied in a counterclockwise direction (second direction) when viewed from the X2 side. The amount of preload applied to the first rolling element 41 can be adjusted by the amount by which the bolt tip of the first set of bolts 28 protrudes from the main shaft protrusion 26. That is, by adjusting the circumferential positional relationship (phase) between the connecting member 30 and the main shaft 21 using the first set of bolts 28, the amount of preload applied to the first rolling element 41 can be adjusted.

[0054] (including structural components)

[0055] The connecting component 30 is a part that is connected to the main shaft 21 in the axial direction X. The "connection" between the connecting component 30 and the main shaft 21 means that the connecting protrusion 35 (described later) of the connecting component 30 is engaged with the main shaft recess 25 of the main shaft 21 in the axial direction X, and the connecting recess 36 (described later) of the connecting component 30 is engaged with the main shaft protrusion 26 of the main shaft 21 in the axial direction X.

[0056] like Figure 3 As shown, the connecting member 30 has a hollow inner hole 31 along the axial direction X. The inner hole 31 is a through hole for the insertion of the rotating shaft 11. The inner hole 31 has an inner diameter for the insertion of the rotating shaft 11. The inner diameter of the inner hole 31 is set to a degree that allows for a suitable clearance between the inner hole 31 and the rotating shaft 11 when the rotating shaft 11 is inserted.

[0057] like Figure 6A As shown, the connecting member 30 has a first inner groove 33 and a second inner groove 34 on the inner peripheral surface of the inner hole 31.

[0058] The first inner groove 33 is configured to extend along the axial direction X (see reference). Figure 3 The cross-sectional shape of the first inner groove 33 is approximately half (approximately semi-circular) of the cross-sectional shape of the first rolling element 41. For example... Figure 6A As shown, the first inner groove 33 is provided on the Z1 side and the Z2 side respectively, with the central axis OA sandwiched in the middle.

[0059] The second inner groove 34 is a groove that engages with the second rolling element 42, and is configured to extend along the axial direction X (see reference). Figure 3 The cross-sectional shape of the second inner groove 34 is approximately half (approximately semi-circular) of the cross-sectional shape of the second rolling element 42. For example... Figure 6A As shown, the second inner groove 34 is provided on the Y1 side and the Y2 side respectively, with the central axis OA sandwiched in the middle.

[0060] The first inner groove portion 33 and the second inner groove portion 34 are arranged at equal intervals (90° intervals in this example) with the central axis OA as the center when viewed from the X-axis. The configuration of the first inner groove portion 33 and the second inner groove portion 34 when viewed from the X-axis is not limited to the above configuration, just like the first inner groove portion 23 and the second inner groove portion 24 of the main shaft 21.

[0061] With the connecting member 30 and the main shaft 21 already connected, if the rotating shaft 11 is inserted into the inner hole 31 of the connecting member 30 and the shaft hole 22 of the main shaft 21, as follows: Figure 2B As shown, two through holes 51 and 52 are formed along the outer periphery of the rotating shaft 11. The through hole 51 is a cylindrical opening for the insertion of the first rolling element 41. The through hole 51 is formed by the first inner groove portion 23 of the main shaft 21, the first inner groove portion 33 of the connecting member 30, and the first outer groove portion 13 of the rotating shaft 11. Each of the above portions is configured to form an inner diameter in the through hole 51 for the insertion of the first rolling element 41.

[0062] The through hole 52 is a cylindrical opening for the insertion of the second rolling element 42. The through hole 52 is formed by the second inner groove portion 24 of the main shaft 21, the second inner groove portion 34 of the connecting member 30, and the second outer groove portion 14 of the rotating shaft 11. Each of the above portions is configured to form an inner diameter in the through hole 52 for the insertion of the second rolling element 42.

[0063] like Figure 3 As shown, the connecting member 30 includes a connecting protrusion 35 and a connecting recess 36. The connecting protrusion 35 is a protrusion that engages with the spindle recess 25 of the spindle 21 in the axial direction X. Figure 6B As shown, the connecting protrusion 35 is positioned on the Y1 and Y2 sides respectively, sandwiching the central axis OA in the middle. The connecting recess 36 is a recess that engages with the main shaft protrusion 26 of the main shaft 21 in the axial direction X. Figure 6B As shown, the connecting recess 36 is provided on the Z1 side and the Z2 side respectively, with the central axis OA sandwiched in the middle.

[0064] like Figure 6BAs shown, the connecting protrusion 35 has a threaded hole 37. An internal thread is formed in the threaded hole 37, which can engage with the second set of bolts (second push member / phase adjustment part) 38. The threaded hole 37 is provided on the Y1 side and Y2 side respectively when viewed from the axial X-axis of the connecting member 30. Furthermore, the threaded hole 37 clamps the central axis OA in the middle and opens in mutually parallel directions.

[0065] The second set of bolts 38 are components used to apply preload to the second rolling element 42 disposed between the connecting member 30 and the rotating shaft 11. The outer circumferential surface of the second set of bolts 38 has an external thread that engages with the internal thread of the threaded hole 37. With the main shaft 21 and the connecting member 30 already engaged, if the second set of bolts 38 are engaged with the internal thread of the threaded hole 37 and rotated in the tightening direction, the bolt tip will protrude from the connecting protrusion 35 and be pushed against the main shaft protrusion 26 of the main shaft 21.

[0066] When the bolt tip is pushed against the spindle protrusion 26 of the spindle 21, the spindle 21 is pushed in the circumferential direction R in a direction spaced apart from the connecting member 30, and the positional relationship between the spindle 21 and the connecting member 30 changes. Therefore, for the second rolling element 42, which is positioned between the connecting member 30 and the rotating shaft 11, a preload is applied in a clockwise direction (first direction) when viewed from the X2 side. The amount of preload applied to the second rolling element 42 can be adjusted by the amount by which the bolt tip of the second set of bolts 38 protrudes from the connecting protrusion 35. That is, by adjusting the positional relationship (phase) between the spindle 21 and the connecting member 30 using the second set of bolts 38, the amount of preload applied to the second rolling element 42 can be adjusted.

[0067] The first rolling element 41 is a spherical component disposed between the first inner groove 23 of the main shaft 21 and the first outer groove 13 of the rotating shaft 11. The second rolling element 42 is a spherical component disposed between the second inner groove 34 of the connecting member 30 and the second outer groove 14 of the rotating shaft 11. In this embodiment, two of each of the first rolling element 41 and the second rolling element 42 are disposed. The first rolling element 41 and the second rolling element 42 are made of, for example, ceramic. In the following description, unless otherwise specified, the first rolling element 41 and the second rolling element 42 are also referred to as "rolling elements".

[0068] Next, the mechanism by which the rotating shaft 11 and the main shaft 21 are connected by the shaft connection mechanism of the first embodiment will be explained. Figure 7 This is a perspective view of the shaft connection mechanism according to the first embodiment. Figure 8 This diagram illustrates the direction in which the main shaft 21 and the connecting component 30 are pushed.

[0069] like Figure 7As shown, the connecting protrusion 35 of the connecting member 30 is engaged with the spindle recess 25 of the spindle 21 in the axial direction X, and the connecting recess 36 of the connecting member 30 is engaged with the spindle protrusion 26 of the spindle 21 in the axial direction X, thereby connecting the connecting member 30 to the spindle 21. The rotating shaft 11 is inserted into the inner hole 31 (see reference) that passes through in the axial direction X between the connected spindle 21 and the connecting member 30. Figure 6A ) and shaft hole portion 22 (refer to Figure 5 ).

[0070] The first rolling element 41 is from the through hole 51 (see reference) Figure 2B The second rolling element 42 is inserted from the through hole 52 (see reference). It is positioned where the main shaft 21, connecting member 30, and rotating shaft 11 overlap in the axial direction X. Figure 2B The first rolling element 41 is inserted and, like the first rolling element 41, is positioned where the connecting member 30 and the rotating shaft 11 overlap in the axial direction X. Each rolling element can be positioned appropriately, for example, by inserting an elongated rod-shaped tool (not shown) through one or both of the through holes. Furthermore, the outer and inner groove portions where the rolling elements are disposed are not limited to a shape that extends along the axial direction X, but can also be shaped with grooved ends, as described in the fifth embodiment below.

[0071] like Figure 7 As shown, with the rotating shaft 11 and the main shaft 21 connected by the connecting member 30, the first rolling element 41 and the second rolling element 42, the first set of bolts 28 and the second set of bolts 38 are rotated in the tightening direction, thereby applying preload to the first rolling element 41 and the second rolling element 42 respectively.

[0072] After rotating the first set of bolts 28 on the main shaft 21 in the tightening direction, as follows Figure 8 As shown, the two first rolling elements 41 that engage with the first inner groove 23 of the main shaft 21 are preloaded in a counterclockwise direction (second direction / arrow A) when viewed from the X2 side. Furthermore, after rotating the second set of bolts 38 of the connecting member 30 in the tightening direction, the two second rolling elements 42 that engage with the second inner groove 34 of the connecting member 30 are preloaded in a clockwise direction (first direction / arrow B) when viewed from the X2 side.

[0073] Thus, after rotating each set of bolts in the tightening direction, preload is applied to the two first rolling elements 41 in the axial direction X counterclockwise, and preload is applied to the two second rolling elements 42 in the clockwise direction. Therefore, since the same number of rolling elements are formed to apply preload in opposite directions in the axial direction X, the circumferential preload forces are balanced, suppressing wobble in the rotational direction of the main shaft 21 and the rotating shaft 11. Furthermore, with the first rolling elements 41 and 42 preloaded, since the main shaft 21 and the rotating shaft 11 are movably connected, even if the main shaft 21 is displaced in the axial direction X due to heat, the displacement of the main shaft 21 can still be absorbed by the change in the relative position of the main shaft 21 and the rotating shaft 11. Moreover, the same effect can be obtained when the rotating shaft 11 is displaced in the axial direction X due to heat.

[0074] Furthermore, since the first rolling element 41 and the second rolling element 42 are respectively located inside the through holes 51 and 52 and are freely movable in the axial direction X, even if the main shaft 21 is displaced in a manner extending in the axial direction X, the amount of extension in the axial direction X can be moved. This suppresses the undesirable situation where the rotating shaft 11 is pushed in the axial direction X due to the displaced main shaft 21. Then, even if the first rolling element 41 and the second rolling element 42 move in the axial direction X, the preload force applied to each rolling element remains unchanged, thus continuously suppressing the wobble in the rotational direction of the main shaft 21 and the rotating shaft 11. Therefore, according to the shaft connection mechanism of the first embodiment, the power of the rotating shaft 11 can be reliably transmitted to the main shaft 21, and it is not easily affected by the displacement of the main shaft 21 in the axial direction X.

[0075] The shaft connection mechanism of the first embodiment includes a first set of bolts 28 and a second set of bolts 38, which serve as a phase adjustment part for adjusting the circumferential phase of the main shaft 21 and the connecting member 30. Therefore, in the shaft connection mechanism of the first embodiment, the preload applied to the first rolling element 41 and the second rolling element 42 can be easily adjusted.

[0076] (Second Implementation)

[0077] The shaft connection mechanism of the second embodiment differs from that of the first embodiment in that the configuration of the first rolling element 41 and the second rolling element 42 is different. In the shaft connection mechanism of the second embodiment, the other configurations are the same as those of the first embodiment. Therefore, in Figure 9 In this embodiment, only the shaft connection mechanism is shown; the motor 10 and the main shaft unit 20 are omitted from the illustration. Furthermore, in the description and drawings of the second embodiment, the same reference numerals as in the first embodiment are used for components identical to those in the first embodiment, and repeated descriptions are omitted.

[0078] Figure 9This is a perspective view of the shaft connection mechanism according to the second embodiment. Figure 9 As shown, in the shaft connection mechanism of the second embodiment, two first rolling elements 41 and two second rolling elements 42 are each arranged along the axial direction X. Thus, by arranging multiple first rolling elements 41 and second rolling elements 42 along the axial direction X, the power of the rotating shaft 11 can be transmitted to the main shaft 21 more reliably. Furthermore, the number of first rolling elements 41 and second rolling elements 42 arranged along the axial direction X is not limited to two, and may also be three or more.

[0079] (Third implementation)

[0080] The shaft connection mechanism of the third embodiment differs from that of the first embodiment in the shapes of the first rolling element 41 and the second rolling element 42. In the shaft connection mechanism of the third embodiment, the other components are the same as those of the first embodiment. Therefore, in Figure 10 In this embodiment, only the shaft connection mechanism is shown; the motor 10 and the main shaft unit 20 are omitted from the illustration. Furthermore, in the description and drawings of the third embodiment, components identical to those in the first embodiment are given the same reference numerals, and repeated descriptions are omitted.

[0081] Figure 10 This is a perspective view of the shaft connection mechanism according to the third embodiment. Figure 10 As shown, in the shaft connection mechanism of the third embodiment, the first rolling element 41 and the second rolling element 42 are composed of cylindrical components. Furthermore, the outer groove of the rotating shaft 11, the main shaft 21, and the inner groove of the connecting member 30 are configured to be approximately half the cross-sectional shape (approximately rectangular) of each rolling element that is parallel to the rotation axis CA.

[0082] like Figure 10 As shown, even when the first rolling element 41 and the second rolling element 42 are cylindrical, the same effect as the shaft connection mechanism in the first embodiment can still be obtained. Furthermore, in the configuration of the third embodiment, the first rolling element 41 and the second rolling element 42 must be arranged such that the plane F perpendicular to each rotation axis CA is parallel to the central axis OA.

[0083] (Fourth implementation)

[0084] The shaft connection mechanism of the fourth embodiment differs from that of the first embodiment in the shapes of the first rolling element 41 and the second rolling element 42. In the shaft connection mechanism of the fourth embodiment, the other components are the same as those of the first embodiment. Therefore, in Figure 11 In this embodiment, only the shaft connection mechanism is shown; the motor 10 and the main shaft unit 20 are omitted from the illustration. Furthermore, in the description and drawings of the fourth embodiment, components identical to those in the first embodiment are given the same reference numerals, and repeated descriptions are omitted.

[0085] Figure 11 This is a perspective view of the shaft connection mechanism according to the fourth embodiment. Figure 11 As shown, in the shaft connection mechanism of the fourth embodiment, the first rolling element 41 and the second rolling element 42 are composed of barrel-shaped components. Furthermore, the outer groove of the rotating shaft 11, the main shaft 21, and the inner grooves of the connecting member 30 are each configured as approximately half the cross-sectional shape of the rolling element parallel to the rotation axis CA. Moreover, "barrel-shaped" refers to a shape in which one of the two opposing long sides of a rectangle or one of the two opposing sides of a square expands outward into an arc shape. In this embodiment, "barrel-shaped" is an example showing a shape in which the two opposing long sides of a rectangle expand outward into an arc shape.

[0086] like Figure 11 As shown, even in the shaft connection mechanism of the fourth embodiment where the first rolling element 41 and the second rolling element 42 are barrel-shaped, the same effect as the shaft connection mechanism of the first embodiment can still be obtained. Furthermore, in the configuration of the fourth embodiment, the first rolling element 41 and the second rolling element 42 must be arranged such that the plane F perpendicular to each rotation axis CA is parallel to the central axis OA.

[0087] (Fifth implementation)

[0088] The shaft connection mechanism of the fifth embodiment differs from that of the first embodiment in that its outer groove portion of the rotating shaft 11 and its inner groove portion of the main shaft 21 are configured differently. In the shaft connection mechanism of the fifth embodiment, other components are the same as in the first embodiment. Therefore, in the figures described below, only the main parts of the shaft connection mechanism are shown, and the illustrations of the motor 10 and the main shaft unit 20 are omitted. Furthermore, in the description and drawings of the fifth embodiment, the same reference numerals as in the first embodiment are used for components that are identical to those in the first embodiment, and repeated descriptions are omitted.

[0089] Figure 12A and Figure 12B This is a conceptual cross-sectional view showing the configuration of the shaft connection mechanism according to the fifth embodiment. Figure 12A and Figure 12B In this context, the axial direction X of the rotation axis 11 and the main shaft 21 is set to be parallel to the direction of gravity (for the purposes of later description). Figure 13A and Figure 13B It is the same.

[0090] exist Figure 12A and Figure 12B In the diagram, the connecting component 30 connected to the main spindle 21 is omitted (for the purposes of the following description). Figure 13A and Figure 13B(The same applies). Therefore, in the following description, "the state in which the rotating shaft 11 and the main shaft 21 are connected" means "the state in which the rotating shaft 11, the main shaft 21, and the connecting component 30 (not shown) are connected". Furthermore, in Figure 12A and Figure 12B In this description, the first outer groove 13 and the first inner groove 23, which are located on one radial side in the outer groove and inner groove of the rotating shaft 11 and the main shaft 21, will be used as examples (for the purposes of the following description). Figure 13A and Figure 13B It is the same.

[0091] like Figure 12A As shown, in the configuration of the fifth embodiment, the first outer groove portion 13 of the rotating shaft 11 has groove end portions 131 at both ends in the axial direction X. The groove end portions 131 are portions in the axial direction X of the first outer groove portion 13 that restrict the movement of the first rolling element 41 toward the X1 side and the X2 side.

[0092] Furthermore, in the configuration of the fifth embodiment, the first inner groove portion 23 of the main shaft 21 has a groove end portion 231 at its end on the X1 side in the axial direction. The groove end portion 231 is the portion of the first inner groove portion 23 that restricts the movement of the first rolling element 41 toward the X1 side in the axial direction.

[0093] like Figure 12A As shown, with the rotating shaft 11 and the main shaft 21 connected, the axial X1 side end (groove end 231) of the first inner groove portion 23 is configured to be located further on the X1 side than the axial X1 side end of the rotating shaft 11. For the axial X2 side of the first inner groove portion 23, the groove shape is set to extend to the end.

[0094] In the above configuration, when a tool such as a slender rod is used, or when the first rolling element 41, which has been inserted between the first outer groove 13 and the first inner groove 23, is moved to its end on the axial X1 side by its own weight, such as... Figure 12A As shown, the first rolling element 41 abuts against the groove end 131 on the X1 side of the first outer groove portion 13 (rotation shaft 11), restricting movement from that position to the X1 side. Therefore, with the rotation shaft 11 and the main shaft 21 connected, the position of the first rolling element 41 can be fixed at the end on the X1 side.

[0095] With the first rolling element 41 fixed at its end on the X1 side, if the rotating shaft 11 and the main shaft 21 are displaced in an axial direction X due to heat, as follows: Figure 12B As shown, the rotating shaft 11 will displace in the direction of arrow a1 (axial direction X1). In addition, the main shaft 21 will displace in the direction of arrow a2 (axial direction X2).

[0096] When the rotating shaft 11 and the main shaft 21 are displaced in the axial direction X, extending in opposite directions, a force acts on the first rolling element 41, causing it to move relative to the main shaft 21 towards the axial direction X1. Thus, as... Figure 12B As shown, the first rolling element 41 will rotate in the direction of arrow a3 (clockwise). At this time, since the outer peripheral surface of the first rolling element 41 will not abut against the edge of the groove end 131 in the rotation direction, the rotation is not restricted.

[0097] Therefore, even if the rotating shaft 11 and the main shaft 21 are displaced in the axial direction X due to heat, this displacement can be absorbed by the rotation of the first rolling element 41. This suppresses the undesirable situation where the rotating shaft 11 is pushed in the axial direction X due to heat displacement of the rotating shaft 11 and the main shaft 21. The same effect can be achieved even if only the main shaft 21 is displaced in the axial direction X1 due to heat displacement.

[0098] Figure 13A and Figure 13B This is a conceptual cross-sectional view showing a different configuration from the shaft connection mechanism of the fifth embodiment. For example... Figure 13A As shown, in other configurations, the first outer groove portion 13 of the rotating shaft 11 has a groove end portion 131 at its end on the X2 side of the axial direction. For the X1 side of the first outer groove portion 13, the groove shape is provided to the end. Furthermore, the first inner groove portion 23 of the main shaft 21 has a groove end portion 231 at its end on the X1 side of the axial direction.

[0099] like Figure 13A As shown, the groove end 231 on the X1 side of the first inner groove portion 23, when the rotating shaft 11 and the main shaft 21 are connected, is configured to be located on the X2 side further than the end on the X1 side of the axial direction of the rotating shaft 11. For the X2 side of the axial direction of the first inner groove portion 23, the groove shape is set to extend to the end.

[0100] In the above configuration, if the rotating shaft 11 and the main shaft 21 are displaced in an axial direction X due to thermal effects, such as Figure 13B As shown, the rotating shaft 11 will displace in the direction of arrow a1 (axial direction X1). In addition, the main shaft 21 will displace in the direction of arrow a2 (axial direction X2).

[0101] When the rotating shaft 11 and the main shaft 21 are displaced in the axial direction X, extending in opposite directions, a force acts on the first rolling element 41, causing it to move relative to the main shaft 21 towards the axial direction X1. Thus, as... Figure 13AAs shown, the first rolling element 41 is intended to rotate in the direction of arrow a3 (clockwise). However, in other configurations, the rotation is restricted because the outer peripheral surface of the first rolling element 41 abuts against the edge of the groove end 231 in the rotational direction.

[0102] Therefore, when the rotating shaft 11 and the main shaft 21 are displaced in the axial direction X due to heat, it becomes impossible to absorb this displacement by the rotation of the first rolling element 41. Consequently, it becomes difficult to suppress the displacement of the rotating shaft 11 and the main shaft 21 due to heat, resulting in an undesirable situation where the rotating shaft 11 is pushed in the axial direction X. The same applies when only the main shaft 21 is displaced in the conventional axial direction X1 due to heat.

[0103] Therefore, if based on Figure 12A The shaft connection mechanism of the fifth embodiment shown can reliably transmit the power of the rotating shaft 11 to the main shaft 21, and suppress the undesirable situation where the rotating shaft 11 is pushed in the axial direction X due to displacement of the rotating shaft 11 and the main shaft 21 caused by heat. In addition, according to the shaft connection mechanism of the fifth embodiment, the first rolling element 41 can be fixed at a predetermined position in the axial direction X while the rotating shaft 11 and the main shaft 21 are connected.

[0104] (Deformation method)

[0105] While the embodiments of this disclosure have been described above, this disclosure is not limited to the foregoing embodiments. Various additions, substitutions, modifications, and partial deletions may be made to these embodiments without departing from the spirit of this disclosure, or without departing from the intent of this disclosure derived from the content described in the claims and their equivalents. Furthermore, these embodiments may also be combined and implemented. For example, in the above embodiments, the order of each action or each process is shown as an example and is not limited to the stated order. Moreover, in the following description, unless specifically distinguished, embodiments 1 to 4 are also referred to as "implementations".

[0106] In the implementation method, although as Figure 2B As shown, the configuration with two through holes 51 and 52 respectively provided along the outer periphery of the rotating shaft 11 will be described, but it is not limited to this. Alternatively, three or more through holes 51 and 52 may be provided along the outer periphery of the rotating shaft 11. Furthermore, since in this case, it is also assumed that the preload force in the circumferential direction will be balanced, it is desirable to set the number of through holes 51 and 52 to be the same.

[0107] The first rolling element 41 and the second rolling element 42 shown in the first, third, and fourth embodiments can also be used in combination. For example, in Figure 2BAlternatively, the following configuration can be adopted: the cross-sectional shape of the through hole 52 is set to quadrilateral, and the cylindrical second rolling element 42 (third embodiment) is inserted into the through hole 52. Thus, in the configuration that combines rolling elements of different shapes, it is also possible to further apply the configuration of arranging multiple rolling elements in the axial direction X, as in the second embodiment.

[0108] The following notes further disclose the above-described embodiments.

[0109] (Note 1)

[0110] A shaft connection mechanism comprising: a main shaft (21) having a hollow shaft hole (22) along the axial direction; a connecting member (30) having a hollow inner hole (31) along the axial direction and being axially connected to the main shaft; a rotating shaft (11) having an external shape that can be inserted into the shaft hole of the main shaft and the inner hole of the connecting member when the main shaft and the connecting member are axially connected; a first rolling element (41) disposed between the main shaft and the rotating shaft; and a second rolling element (42) disposed between the connecting member and the rotating shaft, wherein the main shaft has a first inner groove (23) on the inner circumferential surface of the shaft hole that can engage with the first rolling element, and the connecting member has a first inner groove (23) on the inner circumferential surface of the inner hole that can engage with the second rolling element. The rotating shaft has a first outer groove (13) that engages with the first rolling element and a second outer groove (14) that engages with the second rolling element on its outer peripheral surface. When the main shaft and the connecting member are axially connected and the rotating shaft is inserted into the shaft hole of the main shaft and the inner hole of the connecting member, the first rolling element is disposed between the second outer groove of the rotating shaft and the second inner groove of the main shaft, and the second rolling element is disposed between the first outer groove of the rotating shaft and the first inner groove of the connecting member. Thus, the rotating shaft and the main shaft can move freely in the axial direction, and the power of the rotating shaft is transmitted to the rotating shaft via the first rolling element and the second rolling element.

[0111] (Note 2)

[0112] The shaft connection mechanism includes a phase adjustment part, which can adjust the circumferential phase of the main shaft and the connecting member when the main shaft and the connecting member are axially connected and the rotating shaft is inserted into the shaft hole of the main shaft and the inner hole of the connecting member.

[0113] (Note 3)

[0114] The main shaft has a recess (25) that opens axially to the side of the connecting member, and the connecting member has a protrusion (35) that protrudes axially toward the main shaft. The phase adjustment part has a first pushing member (28) that pushes the first rolling element in a first direction when the recess of the main shaft and the protrusion of the connecting member are engaged axially, and a second pushing member (38) that pushes the second rolling element in a second direction opposite to the first direction.

[0115] (Note 4)

[0116] The first rolling element and the second rolling element are arranged in multiples along the axial direction.

[0117] (Note 5)

[0118] The first rolling element and the second rolling element are any one of spherical, cylindrical, or barrel-shaped.

[0119] Explanation of reference numerals in the attached figures

[0120] 10: Electric motor (rotary motor), 11: Rotary shaft, 13: First outer groove, 14: Second outer groove, 20: Main spindle unit, 21: Main spindle, 22: Shaft hole, 23: First inner groove, 24: Second inner groove, 25: Main spindle recess, 26: Main spindle protrusion, 28: First set of bolts (first push member / phase adjustment part), 30: Connecting component, 31: Inner hole, 33: First inner groove, 34: Second inner groove, 35: Connecting protrusion, 36: Connecting recess, 38: Second set of bolts (second push member / phase adjustment part).

Claims

1. A shaft connection mechanism, wherein, This shaft connection mechanism has the following features: The main shaft has a hollow shaft hole along its axial direction; A connecting component having a hollow inner hole along the axial direction and being axially connected to the main shaft; A rotating shaft having an external shape that allows it to be inserted into the shaft hole portion of the main shaft and the inner hole portion of the connecting member when the main shaft and the connecting member are axially connected. A first rolling element, disposed between the main shaft and the rotating shaft; and A second rolling element is disposed between the connecting member and the rotating shaft. The main shaft has a first inner groove on the inner circumferential surface of the shaft hole portion, which can engage with the first rolling element. The connecting member has a second inner groove on the inner circumferential surface of the inner hole portion, which can engage with the second rolling element. The rotating shaft has a first outer groove on its outer peripheral surface that can engage with the first rolling element and a second outer groove that can engage with the second rolling element. With the main shaft and the connecting member axially connected, and the rotating shaft inserted into the shaft hole of the main shaft and the inner hole of the connecting member, the first rolling element is disposed between the second outer groove of the rotating shaft and the second inner groove of the main shaft, and the second rolling element is disposed between the first outer groove of the rotating shaft and the first inner groove of the connecting member. Thus, the rotating shaft and the main shaft can move freely in the axial direction, and the power of the rotating shaft is transmitted to the rotating shaft via the first rolling element and the second rolling element.

2. The shaft connection mechanism according to claim 1, wherein, The shaft connection mechanism includes a phase adjustment part, which can adjust the circumferential phase of the main shaft and the connecting member when the main shaft and the connecting member are axially connected and the rotating shaft is inserted into the shaft hole of the main shaft and the inner hole of the connecting member.

3. The shaft connection mechanism according to claim 2, wherein, The spindle has a recess that opens axially on the side of the connecting member. The connecting member has a protrusion that protrudes axially toward the main shaft side. The phase adjustment unit includes a first pushing member that pushes the first rolling element in a first direction when the recess of the main shaft and the protrusion of the connecting member are axially engaged, and a second pushing member that pushes the second rolling element in a second direction opposite to the first direction.

4. The shaft connection mechanism according to any one of claims 1 to 3, wherein, The first rolling element and the second rolling element are arranged in multiples along the axial direction.

5. The shaft connection mechanism according to any one of claims 1 to 4, wherein, The first rolling element and the second rolling element are any one of spherical, cylindrical, or barrel-shaped.

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