Spindle device, grinding device, and cutting device

Abstract

The present invention provides a spindle device, a grinding device, and a cutting device that allow for a larger bearing size to be housed in the bearing case, thereby achieving a longer bearing lifespan and improving the rigidity of the rotating shaft. [Solution] The device comprises a rotating shaft on which an object can be mounted at its tip, a housing that rotatably supports the rotating shaft via bearings at the front and rear ends, a bearing case housed within the housing and housing the rear end bearing, a preloading means for applying preload to the rear end bearing, a guide member comprising balls and a cage, disposed between the outer circumference of the bearing case and the inner circumference of the housing, and a drive motor provided within the housing between the front end bearing and the rear end bearing for driving the rotating shaft. The cage of the guide member is provided with an open section that is discontinuous in the circumferential direction, and a notch is provided on the outer circumference of the bearing case at the same phase as the open section, with the open section and the notch serving as wiring space for the motor.

Description

Technical Field

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

Background Art

[0002] Conventionally, in a device that rotates a tool for machining, a spindle device in which a tool is detachably attached to a rotatable main shaft is known. The spindle device is a machine tool that performs cutting, grinding, etc., and rotates a tool such as an end mill, a grinding wheel, or a dresser used for machining a workpiece, or clamps and rotates the workpiece. Further, there is a spindle device of a motor built-in type (Patent Document 1) in which an electric motor (motor) is built in the spindle device.

[0003] A tool for machining a workpiece such as an end mill, a grinding wheel, or a dresser is attached to the rotating shaft of this type of spindle device. The rotating shaft is disposed in a housing that is rotatably supported via a bearing (ball bearing), and preload is applied to the bearing by a preloading means. By the way, there is an internal clearance in a general ball bearing. If the internal clearance of the ball bearing is large, when the rotating shaft is rotated at high speed, the vibration of the rotating shaft becomes large, resulting in a decrease in machining quality. As one of the countermeasures, preload may be applied as described above to reduce the internal clearance of the ball bearing. One of the methods of applying preload is a 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 with respect to the housing. In order to make it movable, a ball guide composed of, for example, a plurality of balls and a retainer for aligning the balls at a constant interval may be provided between the outer peripheral surface of the bearing case and the inner peripheral surface of the housing. Thereby, the movement in the axial direction is made smooth.

[0004] By the way, the spindle device in Patent Document 1, as shown in Figure 7, comprises a motor unit 52, a rotating shaft 50 driven and rotated by the motor unit 52, a tool chuck (not shown) provided at the axial front end of the rotating shaft 50 for detachably holding an end mill (not shown) as a rotating tool, a front housing (not shown) provided adjacent to the tool chuck (not shown) side of the motor unit 52 and rotatably supporting the axial front side of the rotating shaft 50 via a ball bearing (not shown), and the axial direction of the rotating shaft 50 The motor has a housing 51 provided adjacent to the end of the motor section 52 facing the rear, a bearing case 54 provided on the inner circumferential surface of the housing 51 via a ball slide 53, ball bearings 60 and 61 provided on the inner circumferential surface of the bearing case 54 to rotatably support the rotating shaft 50, a flange section 58 fastened with bolts 57 to the rear end of the bearing case 54 facing the axial rear side of the rotating shaft 50, and a preloading means 62 attached to the flange section 58 to apply preload to the bearings 60 and 61. Here, "axial direction" in this specification refers to the direction in which the axis of the rotating shaft extends, and "circumferential direction" as described later refers to the circumferential direction around the axis of the rotating shaft. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2015-20254 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Incidentally, in the built-in spindle device described in Patent Document 1, the motor is housed inside the housing. As a result, the stator (fixed element) of the motor has wiring for power supply, and this wiring must be routed to the outside of the spindle device, passing near the bearing case. However, in order to allow the bearing case to move in the axial direction of the rotating shaft, space is needed to provide ball guides (ball slides) and to avoid the wiring of the stator. For this reason, the size of the ball bearing that can be housed in the bearing case must be reduced in diameter. The smaller the size of the ball bearing, the greater the surface pressure on the raceway surface of the ball bearing under the same preload, which shortens the lifespan of the ball bearing. To extend the lifespan, reducing the preload is an effective measure, but reducing the preload can increase the vibration of the rotating shaft when it is rotated at high speed, potentially negatively affecting the machining quality. For this reason, 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 lifespan, and also improve the rigidity of the rotating shaft. [Means for solving the problem]

[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 inside the rear end side of the housing and housing the bearing on the rear end side, and a preloading means for applying preload to the bearing housed in the bearing case, The spindle device comprises 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, a guide member disposed between the outer circumference of the bearing case and the inner circumference of the housing to allow axial movement of the bearing case, and a drive motor provided in the housing between the front end bearing and the rear end bearing to drive 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 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 circumference 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 form a space for wiring the motor wiring. Here, the mounted objects refer to various processing tools (for example, grinding wheels and cutting tools), and in this spindle device, these processing tools are used to perform processing (polishing, cutting, etc.) on the workpiece.

[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 mounted 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. [Effects of the Invention]

[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 (prolongs 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. [Brief explanation of the drawing]

[0015] [Figure 1] This is a cross-sectional view of a spindle device using the sealing device according to the present invention. [Figure 2] This is a cross-sectional perspective view of the main part of the spindle device. [Figure 3] This is a simplified diagram showing the relationship between the open portion of the cage and the notch portion of the bearing case. [Figure 4] This is a perspective view of the bearing case. [Figure 5] This is a simplified diagram showing the spindle device in use. [Figure 6] This is a cross-sectional perspective view of a key part showing a comparative example of a spindle device. [Figure 7] It is a cross-sectional view of a main part of a conventional spindle device.

Embodiments for Carrying out the Invention

[0016] Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 5. FIG. 1 is a cross-sectional view of a spindle device according to the present invention, and FIG. 2 is a cross-sectional perspective view thereof. In FIG. 1, hatching is omitted.

[0017] The spindle device includes 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 driving motor 6 installed inside the housing 5. Each of the bearings 2 and 3 includes inner rings 2a1, 2b1, 3a1, 3b1, outer rings 2a2, 2b2, 3a2, 3b2, and balls 2a3, 2b3, 3a3, 3b3 interposed between the inner and outer rings, and is an angular bearing. An object to be mounted is detachably mounted on the tip of the rotating shaft 1. Here, the object to be mounted is various processing tools (for example, grinding wheels, cutting tools, etc.), and in this spindle device, processing (such as grinding and cutting) is performed on the workpiece with these processing tools. The bearings include a front-end bearing 2 on the front-end side of the rotating shaft 1 and a rear-end bearing 3 on the rear-end side of the rotating shaft 1, and a driving 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 includes a cylindrical housing body 5a and a rear lid member 5c that closes the rear-end opening of the housing body 5a, and the front-end opening of the housing body 5a is closed by a front lid member 5b. The housing body 5a includes 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 side.

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

[0020] Further, the fourth member 14 is composed of a ring body 14a and a short cylindrical portion 14b protruding from the inner diameter end of the ring body 14a toward the tip side. The rear end portion of the fourth member 14 is fitted into a notch portion 13a2 provided on the front end surface of the disk portion 13a of the third member 13. In this case, a bulging portion 13b1 protruding outward in the outer diameter direction is provided at the tip end portion of the cylindrical portion 13b of the third member 13, and the tip end portion of the short cylindrical portion 14b of the fourth member 14 is externally fitted to the bulging portion 13b1. The fifth member 15 is composed of a ring body having a circumferential notch portion 15a on the front end surface. The rear lid member 5c is composed of a disk body having a concave portion 5c1 on the front end surface, and the outer peripheral surface 5c2 of the remaining portion 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 portion 15a of the fifth member 15.

[0021] By the way, the outer peripheral surface of the rear lid 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 disk 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 smaller than the outer diameter surface of the first member 11 and the like. Here, the same diameter includes the range within the dimensional tolerance. Note that in this case, it is not limited to the same diameter.

[0022] The bearings 2(2A) and 2(2B) at the front end are fitted externally to the mounting portion 1a at the front end 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 freely 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 severance of the motor wiring 30 at the notched ends a and b of the opening 26a, and furthermore, the strength of the retainer 26 may decrease.

[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 supplied 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 approximately 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 extends the rolling life of the bearing 3 (increases the lifespan of the bearing), and also allows for a larger 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] Incidentally, 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 the rotating shaft, 3 is the bearing at the rear of the device that rotatably supports the rotating shaft 1, 5 is the 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 the motor wiring, 20 is the 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 size of the bearing case 20 can be increased 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 machining 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 machining tool and the workpiece support table 47 face each other. In addition, a workpiece support device (shoe) 49 is erected from the main body (fixed part) 48 of the machining equipment. 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 object 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. [Explanation of Symbols]

[0043] 1. Axis of rotation 5 Housing 6. Drive motor 20 Bearing Case 23 Notch 25 Guide member 26 Cage 26a Open area 27 Ball 28 Notch 30 Motor Wiring P Preloading means S1 Wiring space

Claims

1. A rotating shaft to which an object can be attached at the tip, A housing that rotatably supports the rotating shaft via bearings provided on the front end, which is the tip side of the rotating shaft, and on the rear end, A bearing case is housed inside the rear end of the housing and houses the bearing at the rear end, A preloading means for applying preload to the bearing housed in the bearing case, The bearing case comprises 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 member disposed between the outer circumference of the bearing case and the inner circumference of the housing to allow axial movement of the bearing case, The housing includes a drive motor provided between the front end bearing and the rear end bearing for driving the rotating shaft, In a spindle device in which 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 of the drive motor is routed 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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