Spindle device, grinding device, and cutting device

Abstract

The present invention comprises: a rotary shaft, to the tip end of which an object to be mounted can be mounted; a housing which rotatably supports the rotary shaft via a bearing; a bearing case which is provided inside the housing and which accommodates a rear end side bearing; a preloading means which preloads the rear end side bearing; a guide member which is provided with a ball and a retainer and which is provided between an outer peripheral part of the bearing case and an inner peripheral part of the housing; and a driving motor which is provided inside the housing between a front end side bearing and the rear end side bearing. The bearing case can be moved by the preloading means in the axial direction of the rotary shaft via the guide member. Motor wiring of the driving motor is led to the outside via the outer diameter side of the bearing case. Open parts that are discontinuous in the circumferential direction are provided to the retainer of the guide member. Cutouts are provided to the outer peripheral part of the bearing case at the same phase positions as the open parts. The open parts and the cutouts form wiring spaces for the motor wiring.

Description

Spindle device, grinding device, and cutting device

[0001] The present invention relates to a spindle device, and more particularly to a motor-built-in spindle device, grinding device, and cutting device.

[0002] Conventionally, in machines that perform machining by rotating a tool, a spindle device is known in which a tool is attached to a rotatable spindle in an interchangeable manner. A spindle device is a machine tool that performs cutting and grinding, and it rotates tools such as end mills, grinding wheels, or dressers used to machine a workpiece, or it clamps and rotates the workpiece. In addition, there is a motor-built-in type spindle device (Patent Document 1) in which an electric motor is built into the spindle device.

[0003] Tools for machining workpieces, such as end mills, grinding wheels, and dressers, are mounted on the rotating shaft of this type of spindle device. The rotating shaft is housed in a housing that rotatably supports it via bearings (ball bearings), and preload is applied to the bearings by a preloading mechanism. However, general ball bearings have internal clearance. If the internal clearance of the ball bearing is large, the vibration of the rotating shaft increases when it is rotated at high speed, which reduces the machining quality. One way to address this is to apply preload to reduce the internal clearance of the ball bearing, as described above. One method of applying preload is the constant-pressure preloading method. In the constant-pressure preloading method, the ball bearing is housed in a bearing case, and the bearing case is provided so as to be movable in the axial direction of the rotating shaft relative to the housing. To enable this movement, a ball guide, consisting of multiple balls and a cage for aligning the balls at a constant interval, may be provided between the outer surface of the bearing case and the inner surface of the housing. This ensures smooth movement in the axial direction.

[0004] Incidentally, as shown in FIG. 7, the spindle device in Patent Document 1 includes a motor unit 52, a rotating shaft 50 that is driven by the motor unit 52 and rotates, and an end mill (not shown) as a rotating tool that is provided at the front end in the axial direction of the rotating shaft 50 and is detachably held. A tool chuck (not shown), a front housing (not shown) provided adjacent to the tool chuck (not shown) side of the motor unit 52 and rotatably supporting the front side in the axial direction of the rotating shaft 50 via a ball bearing (not shown), and a housing 51 provided adjacent to the end of the motor unit 52 facing the rear side in the axial direction of the rotating shaft 50, a bearing case 54 provided on the inner peripheral surface of the housing 51 via a ball slide 53, ball bearings 60 and 61 provided on the inner peripheral surface of the bearing case 54 for rotatably supporting the rotating shaft 50, and a flange portion 58 fastened with a bolt 57 to the rear end portion facing the rear side in the axial direction of the rotating shaft 50 in the bearing case 54, and a preloading means 62 attached to the flange portion 58 for applying preload to the bearings 60 and 61. Here, the "axial direction" in this specification is the direction in which the axis of the rotating shaft extends, and the "circumferential direction" described later is the circumferential direction around the axis of the rotating shaft.

[0005] Japanese Patent Application Laid-Open No. 2015-20254

[0006] Incidentally, in the built-in type spindle device described in Patent Document 1, since the motor is built inside the housing, the stator (stator) of the components constituting the motor has wiring for power supply, and the wiring must be drawn out to the outside of the spindle device through the vicinity of the bearing case. However, in order to make the bearing case movable in the axial direction of the rotating shaft, a space for providing a ball guide (ball slide) and a space for avoiding the wiring of the stator are required. For this reason, the size of the ball bearing that can be housed in the bearing case has to be reduced. The smaller the size of the ball bearing, the greater the surface pressure applied to the raceway surface of the ball bearing under the same preloading load, and there is a problem that the life of the ball bearing is shortened. To extend the life, a measure to reduce the preloading load is effective, but when the preloading load is reduced, the vibration of the rotating shaft becomes large when the rotating shaft is rotated at high speed, which may have an adverse effect on the machining quality. Therefore, it is desirable that the size of the ball bearing housed in the bearing case be as large as possible.

[0007] Therefore, the present invention provides a spindle device, a grinding device, and a cutting device that can increase the size of the bearing housed in the bearing case, thereby achieving a longer bearing life and improving the rigidity of the rotating shaft.

[0008] The spindle device of the present invention comprises a rotating shaft on which an object can be mounted at its tip, a housing that rotatably supports the rotating shaft via bearings provided on the front end side, which is the tip side of the rotating shaft, and the rear end side of the rotating shaft, a bearing case housed in the rear end side of the housing and housing the bearing on the rear end side, a preloading means for applying preload to the bearing housed in the bearing case, a retainer made of an annular shape and a plurality of balls arranged in the retainer so as to be able to roll along the circumference at a predetermined pitch, and a guide disposed between the outer circumference of the bearing case and the inner circumference of the housing that allows axial movement of the bearing case The spindle device comprises a member and a drive motor provided within the housing between the front end bearing and the rear end bearing to drive the rotating shaft, wherein the bearing case is movable in the axial direction of the rotating shaft via the guide member by the preloading means, and the motor wiring for the motor for driving is led out to the outside via the outer diameter side of the bearing case, wherein the retainer of the guide member is provided with an open portion that is discontinuous in the circumferential direction, and a notch is provided on the outer circumference of the bearing case at the same phase position as the open portion, and the open portion and the notch become a space for wiring the motor wiring. Here, the mounted object is various processing tools (for example, grinding wheels and cutting tools, etc.), and in this spindle device, processing (grinding, cutting, etc.) is performed on the workpiece using these processing tools.

[0009] The open section and the notch section can form a space for routing motor wiring, allowing the motor wiring to pass through the inner diameter side of the retainer. This makes it possible to enlarge the bearing case without increasing the size of the housing.

[0010] Preferably, the retainer of the guide member is an annular shape fitted onto the bearing case, and a plurality of balls are arranged to roll freely in the retainer at a predetermined pitch along the circumference, allowing the bearing case to move in the axial direction by the rolling of the balls. This configuration ensures stable and reliable axial sliding of the bearing case. Moreover, as a guide member, it contributes to compactness and prevents an increase in the diameter of the housing.

[0011] The housing has a cover member provided at the axial end, and the cover member has an external outlet for the motor wiring of the drive motor, and the motor wiring can be routed to the outside through the wiring space and the external outlet. By configuring it in this way, the motor wiring can be effectively routed to the outside without increasing the size of the housing.

[0012] The grinding apparatus according to the present invention is a grinding apparatus equipped with the spindle device, wherein the mounting object attached to the tip of the rotating shaft is a grinding wheel. In this grinding apparatus, the size of the bearing case can be increased without increasing the size of the housing.

[0013] The cutting apparatus according to the present invention is a cutting apparatus equipped with the spindle device, wherein the mounted object attached to the tip of the rotating shaft is a cutting tool. In this cutting apparatus, the size of the bearing case can be increased without increasing the size of the housing.

[0014] This invention allows for an increase in the size of the bearing case without increasing the size of the housing. This extends the rolling life of the bearing (increases the lifespan of the bearing), and also allows for an increase in the diameter of the rotating shaft, thereby improving the rigidity of the rotating shaft.

[0015] This is a cross-sectional view of a spindle device using the sealing device according to the present invention. This is a cross-sectional perspective view of the main part of the spindle device. This is a simplified diagram showing the relationship between the open part of the cage and the notch part of the bearing case. This is a perspective view of the bearing case. This is a simplified diagram showing the spindle device in use. This is a cross-sectional perspective view of the main part showing a comparative example of the spindle device. This is a cross-sectional view of the main part of a conventional spindle device.

[0016] Embodiments of the present invention will be described below with reference to Figures 1 to 5. Figure 1 is a cross-sectional view of the spindle device according to the present invention, and Figure 2 is a cross-sectional perspective view thereof. Note that hatching has been omitted in Figure 1.

[0017] The spindle device comprises a rotating shaft 1 and a housing 5 that rotatably supports the rotating shaft 1 via a pair of bearings 2 and 3. The rotating shaft 1 is rotationally driven by a drive motor 6 housed in the housing 5. Each of the bearings 2 and 3 comprises inner rings 2a1, 2b1, 3a1, and 3b1, outer rings 2a2, 2b2, 3a2, and 3b2, and balls 2a3, 2b3, 3a3, and 3b3 interposed between the inner and outer rings, and is an angular contact bearing. An object is mounted on the tip of the rotating shaft 1. Here, the object is various processing tools (for example, grinding wheels and cutting tools, etc.), and in this spindle device, processing (grinding, cutting, etc.) is performed on the object to be processed using these processing tools. The bearings consist of a front end bearing 2 on the tip side of the rotating shaft 1 and a rear end bearing 3 on the rotating shaft 1, and the drive motor 6 is provided between the front end bearing 2 and the rear end bearing 3 of the rotating shaft 1.

[0018] The housing 5 comprises a cylindrical housing body 5a and a rear cover member 5c that closes the rear end opening of the housing body 5a, while the front end opening of the housing body 5a is closed by a front cover member 5b. The housing body 5a also comprises a first member 11, a second member 12, a third member 13, a fourth member 14, and a fifth member 15 from the rear end.

[0019] The first member 11 has a cylindrical main body 11a and a bulging portion 11b that protrudes inward toward the tip side of the inner diameter surface of the main body 11a. The second member 12 is made of a cylindrical body, and its rear end is fitted into a circumferential notch 11a1 formed on the tip surface of the main body 11a of the first member 11. The third member 13 has a disc portion 13a and a cylindrical portion 13b that extends from the inner diameter end of the disc portion 13a toward the tip side. A circumferential notch 13a1 is provided on the outer diameter side of the rear end surface of the disc portion 13a, and the tip of the second member 12 is fitted into the notch 13a1.

[0020] Furthermore, the fourth member 14 consists of a ring body 14a and a short cylindrical portion 14b that protrudes from the inner diameter end of the ring body 14a toward the tip, and the rear end of the fourth member 14 is fitted into a notch 13a2 provided on the tip surface of the disc portion 13a of the third member 13. In this case, a bulge 13b1 that protrudes toward the outer diameter is provided on the tip of the cylindrical portion 13b of the third member 13, and the tip of the short cylindrical portion 14b of the fourth member 14 is fitted onto this bulge 13b1. The fifth member 15 consists of a ring body having a circumferential notch 15a on its tip surface. Furthermore, the rear lid member 5c consists of a disc body having a recess 5c1 on its front end surface, and the remaining outer peripheral surface 5c2 of the front end surface is joined to the rear end surface of the first member 11. The front lid member 5b is fitted into the circumferential notch 15a of the fifth member 15.

[0021] Incidentally, the outer circumferential surface of the rear cover member 5c, the outer diameter surface of the first member 11, the outer diameter surface of the second member 12, the outer diameter surface of the disc portion 13a of the third member 13, and the outer diameter surface of the ring body 14a of the fourth member 14 are of the same diameter, and the outer diameter surface of the short cylindrical portion 14b of the fourth member 14 and the outer diameter surface of the fifth member 15 are of the same diameter but smaller than the outer diameter surfaces of the first member 11, etc. Here, "same diameter" includes the range that falls within the dimensional tolerance. However, in this case, it is not limited to the same diameter.

[0022] The bearings 2(2A) and 2(2B) at the tip are fitted externally to the mounting portion 1a at the tip of the rotating shaft 1 and internally to the third member 13, while the bearings 3(3A) and 3(3B) at the rear end are fitted externally to the mounting portion 1b at the rear end of the rotating shaft 1 and internally to the bearing case 20. The bearing case 20 is internally to the first member 11 of the housing body 5a of the housing 5.

[0023] Incidentally, a guide member 25 is interposed between the bearing case 20 and the first member 11 of the housing 5. The guide member 25 consists of a cage 26 made of an annular shape having an open portion 26a in part, and a plurality of balls 27 arranged on the cage 26 so as to be able to roll along the circumference at a predetermined pitch, and the axial movement of the bearing case 20 is permitted by the rolling of the balls 27. When the central angle of the open portion 26a in the free state (the angle made by the notched ends a and b) is θ, θ is set to be 10° or more and less than 90°. If θ is less than 10°, the open portion 26a is too small, making it difficult or impossible for the motor wiring 30 to pass through. Conversely, if θ exceeds 90°, the opening 26a becomes too large, causing the motor wiring 30 to move (shift) within the opening 36a, which may result in damage or cutting of the motor wiring 30 at the notched ends a and b of the opening 26a. Furthermore, this could also reduce the strength of the retainer 26.

[0024] As shown in Figure 1, a preloading means P is positioned between the bearing case 20 and the first member 11 of the housing body 5a to apply preload to the bearings 3, 3. In this case, the preloading means P is made of an elastic material such as a coil spring, and preload is applied to the rear bearings 3(3A) and 3(3B). The front bearings 2(2A) and 2(2B) are preloaded by bolt tightening. Furthermore, as shown in Figure 4, a notch 23 is provided on the outer circumferential surface of the bearing case 20, with a bottom surface 23a that is a concave arc surface.

[0025] The drive motor 6 comprises a rotor 6a fitted onto the axial intermediate portion of the rotating shaft 1, and a stator 6b loosely fitted onto the rotor 6a, with wiring (motor wiring) 30 being discharged from the stator 6b. A cooling jacket 31 is provided on the outer diameter side of the stator 6b. The cooling jacket 31 is cooled by circulating refrigerant.

[0026] Furthermore, as shown in Figure 3, the open portion 26a and the notch portion 23 of the retainer 26 are arranged in the same phase. The open portion 26a and the notch portion 23 constitute the wiring space S1 for the motor wiring 60 of the drive motor 6. In addition, a notch portion 28 is provided in the first member 11 of the housing body 5a. The notch portion 28 is also arranged in the same phase as the open portion 26a and the notch portion 23. Therefore, the notch portion 28 also constitutes the wiring space S2 for the motor wiring 60. Thus, a wiring passage S with a circular cross-section can be formed in the wiring spaces S1 and S2. The bottom surface 28a of the notch portion 28 on the housing 5 side is also a concave curved surface, and the radius of curvature of this concave curved surface is about the same as the radius of curvature of the bottom surface 23a of the notch portion 23.

[0027] Furthermore, the rear cover member 5c of the housing 5 is provided with an external outlet 32 ​​consisting of a through hole, through which the motor wiring 30 is sent to the outside of the housing 5, and the discharged motor wiring 30 is connected to a power supply (not shown). This external outlet 32 ​​is also in the same phase as the wiring passage S consisting of wiring spaces S1 and S2.

[0028] By attaching a processing tool (for example, a grinding wheel or cutting tool) to the tip of the rotating shaft 1 of the spindle device, a turning machine or cutting machine is constructed.

[0029] According to the spindle device of the present invention, the open portion 26a and the notch portion 23 can constitute a wiring space S1 for the motor wiring 30, and the motor wiring 30 can be passed through the inner diameter side of the retainer 26, thereby allowing the bearing case 20 to be enlarged without increasing the size of the housing 5. Furthermore, if the motor wiring 30 can be sent out of the housing 5 via the external outlet 32 ​​using only the wiring space S1, the wiring space S2 on the housing side, which consists of the notch portion 28, can be omitted.

[0030] Thus, the present invention makes it possible to enlarge the bearing case 20 without increasing the size of the housing 5. This makes it possible to extend the rolling life of the bearing 3 (increase the lifespan of the bearing), and also to increase the shaft diameter of the rotating shaft 1, thereby improving the rigidity of the rotating shaft 1.

[0031] Preferably, the retainer 26 of the guide member 25 is an annular shape that is fitted onto the bearing case 20, and a plurality of balls 27 are arranged to roll freely in the retainer 26 at a predetermined pitch along the circumference, allowing axial movement of the bearing case 27 by the rolling of the balls 27. With this configuration, axial sliding of the bearing case 27 can be ensured stably and reliably.

[0032] The housing 5 has a cover member 5c provided at its axial end, and the cover member 5c has an external outlet 32 ​​for the motor wiring 30 of the drive motor 6. The motor wiring 30 can be routed to the outside via a wiring passage S (wiring spaces S1, S2) and the external outlet 32. This configuration allows the motor wiring 20 to be routed to the outside effectively without increasing the size of the housing 5.

[0033] By the way, Figure 6 shows a comparative example, in which case the retainer 26 of the guide member 25 is not provided with an open portion that is discontinuous in the circumferential direction, and the outer circumference of the bearing case 20 is not provided with a notch at the same phase position as the open portion. In Figure 6, 1 is a rotating shaft, 3 is a bearing at the rear of the device that rotatably supports the rotating shaft 1, 5 is a housing that rotatably supports the rotating shaft 1 via bearings 3 (3A) and 3 (3B), 6 is a drive motor equipped with a rotor 6a fitted onto the axial intermediate portion of the rotating shaft 1 and a stator 6b loosely fitted onto the rotor 6a, 30 is motor wiring, 20 is a bearing case, and 25 is a guide member (ball guide) equipped with balls 27 and a retainer 26.

[0034] In this case, as shown in Figure 6, the motor wiring 30 will pass on the outer diameter side of the guide member 25. That is, a passage 40 through which the motor wiring 30 is inserted is provided in the inner wall of the housing 5, and the motor wiring 30 will be routed to the outside of the housing 5 via this passage 40.

[0035] In a built-in type motor 6, as shown in Figure 6, where the drive motor is housed inside the housing 5, space is required to provide a guide member (ball guide) 25 and a passage 40 to avoid the wiring 30 of the stator 6b in order to allow the bearing case 20 to move in the axial direction of the rotating shaft 1. This necessitates reducing the diameter of the bearing 3 that can be housed in the bearing case 20. The smaller the size of the bearing 3, the greater the surface pressure on the raceway surface of the bearing 3 under the same preload, shortening the bearing's lifespan. Reducing the preload is an effective way to extend the lifespan, but reducing the preload can increase the vibration of the rotating shaft 1 when it is rotated at high speed, potentially negatively impacting machining quality.

[0036] In contrast, as in the present invention, the retainer 26 of the guide member 25 is provided with an open portion 26a that is discontinuous in the circumferential direction, and a notch 23 is provided on the outer circumference of the bearing case 20 at the same position as the open portion 26a. This makes it possible to enlarge the bearing case 20 without enlarging the housing 5. As a result, the rolling life of the bearing can be extended (the bearing has a longer lifespan), and the shaft diameter of the rotating shaft 1 can be increased, thereby improving the rigidity of the rotating shaft.

[0037] The grinding apparatus according to the present invention is a grinding apparatus equipped with the spindle device, wherein the mounting object attached to the tip of the rotating shaft 1 is a grinding wheel. In this grinding apparatus, the bearing case 20 can be enlarged without enlarging the housing 5.

[0038] The cutting apparatus according to the present invention is a cutting apparatus equipped with a spindle device, wherein the mounted object attached to the tip of the rotating shaft 1 is a cutting tool. In this cutting apparatus, the bearing case 20 can be enlarged without increasing the size of the housing 5.

[0039] Figure 5 shows an example of using the spindle device according to the present invention, in which a grinding wheel 45 is used as the machining tool, the spindle device 100 shown in the embodiment is used to rotate the grinding wheel 45, for example, the raceway ring (outer ring) 46 of a bearing having a raceway surface 46a on its inner circumferential surface is used as the workpiece W, and the spindle device shown in the embodiment (spindle device 101, which is different from spindle device 100) is used to rotate the workpiece W.

[0040] In this case, the grinding wheel 45 of the processing tool is mounted on the rotating shaft 1 of one spindle device 100 located on the upper side, and the workpiece support table 47 is mounted on the rotating shaft 1 of the other spindle device 101 located on the lower side, so that the grinding wheel 45 of the processing tool and the workpiece support table 47 face each other. In addition, a workpiece support device (shoe) 49 is erected from the processing equipment body (fixed part) 48. This allows the workpiece W to be supported on the workpiece support table 47.

[0041] In such a device, the workpiece W is placed on the workpiece mounting table 47 of the rotating shaft 1 of the lower spindle device 101, and the upper spindle device 101 is lowered as shown by the arrow to adjust the grinding wheel 45 attached to the rotating shaft 1 of the upper spindle device 101 to the height of the workpiece W. The rotating shaft 1 of the upper spindle device 100 is rotated, and the rotating shaft 1 of the lower spindle device 101 is also rotated. As a result, the workpiece mounting table 47 rotates while the grinding wheel 45 rotates, making it possible to grind the raceway surface 46a of the outer ring 46, which is the workpiece W.

[0042] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified in various ways. The mounting device attached to the tip of the rotating shaft 1 may be an end mill, a grinding wheel, or a dresser. Also, of course, machining may be performed with a single spindle device instead of using two spindle devices as shown in the example of use in Figure 5.

[0043] There are motor-built-in spindle devices that have an electric motor (motor) built into them. Tools for machining workpieces, such as end mills, grinding wheels, and dressers, are mounted on the rotating shaft of the spindle device. The motor wiring of the drive motor is routed to the outside via the outer diameter side of the bearing case.

[0044] 1 Rotating shaft 5 Housing 6 Drive motor 20 Bearing case 23 Notch 25 Guide member 26 Retainer 26a Opening 27 Ball 28 Notch 30 Motor wiring P Preloading means S1 Wiring space

Claims

1. A spindle device comprising: a rotating shaft on which a load can be attached to its tip; a housing that rotatably supports the rotating shaft via bearings provided on the front end side, which is the tip side of the rotating shaft, and on the rear end side of the rotating shaft; a bearing case housed inside the rear end side of the housing and housing the rear end bearing; a preloading means for applying preload to the bearing housed in the bearing case; a guide member disposed between the outer circumference of the bearing case and the inner circumference of the housing, which comprises a retainer made of a front annular shape and a plurality of balls arranged in the retainer so as to be rotatable along the circumferential direction at a predetermined pitch, and which allows axial movement of the bearing case; and a drive motor provided inside the housing between the front end bearing and the rear end bearing for driving the rotating shaft, wherein the bearing case is capable of axial movement of the rotating shaft via the guide member by the preloading means, and the motor wiring of the drive motor is led out to the outside via the outer diameter side of the bearing case. A spindle device characterized in that the retainer of the guide member is provided with an open portion that is discontinuous in the circumferential direction, and a notch is provided on the outer circumference of the bearing case at a position in phase with the open portion, and the open portion and the notch form a space for wiring the motor wiring.

2. The spindle device according to claim 1, characterized in that the retainer of the guide member is fitted onto the bearing case and is made of an annular shape having an open portion in part, a plurality of balls are arranged to roll freely in the retainer at a predetermined pitch along the circumferential direction, and the rolling of the balls allows the bearing case to move in the axial direction.

3. The spindle device according to claim 1, characterized in that the housing has a cover member provided at the axial end, the cover member has an external outlet for the motor wiring of the drive motor, and the motor wiring is routed to the outside through the wiring space and the external outlet.

4. A grinding apparatus comprising a spindle device according to any one of claims 1 to 3, characterized in that the object mounted on the tip of the rotating shaft is a grinding wheel.

5. A cutting machine comprising a spindle device according to any one of claims 1 to 3, characterized in that the mounted object attached to the tip of the rotating shaft is a cutting tool.

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