Rolling bearing device

Abstract

The present invention provides a rolling bearing device that improves the space efficiency of the cooling mechanism and also improves cooling efficiency by allowing cooling oil to be supplied closer to the bearing. [Solution] The rolling bearing device 10 is provided with a cooling passage in the housing 12 for cooling the rolling bearing. Multiple V-shaped holes 73 are formed in the circumferential direction in the cylindrical portion 13A of the housing 12 that fits the outer ring 51 of the rolling bearing, so as to form a circulation path 71 that communicates in a zigzag pattern along the circumferential direction.

Description

Technical Field

[0001] The present invention relates to a rolling bearing device applicable to a spindle device, a lathe, a circular table, etc. of a machine tool, and particularly to a rolling bearing device provided with a cooling mechanism for cooling a rolling bearing.

Background Art

[0002] In a rolling bearing device, particularly a rolling bearing device that is operated at high speed, typified by the spindle device of a machine tool, heat generation is mainly caused by the rolling friction of the bearing, and problems such as changes in the performance of the bearing due to thermal expansion of each part and deterioration of lubricity due to an increase in the temperature of the lubricating oil are regarded as problems caused by heat. As a solution, generally, a cooling device that circulates a fluid cooled by a chiller or the like is used, and a bearing cooling mechanism in which the circulation path is provided near the bearing to perform cooling is known.

[0003] As shown in FIG. 6, a general bearing cooling mechanism forms an outer peripheral groove 103 such as a circumferential groove or a spiral groove on the outer peripheral surface 102a of a housing 102 that fits inside the outer ring 101 of a rolling bearing 100, and further provides a cover 104 so as to surround the outer periphery thereof. Then, a cooling path 105 is formed by the outer peripheral groove 103 and the cover 104, and the rolling bearing 100 is cooled by supplying and circulating a fluid from a fluid supply path 106 formed in the housing 102 to the cooling path 105.

[0004] Further, Patent Document 1 discloses a bearing support device in which a plurality of grooves are provided on the outer periphery of a hollow shaft that contacts the inner ring of a bearing, and fluid supply holes and discharge holes are communicated between the outer ring and the inner ring of the bearing and the plurality of grooves, and fluid is directly supplied from a casing to the bearing to cool the bearing.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] However, in the cooling passage 105 shown in Figure 6, the housing 102 requires a certain thickness to meet the original strength requirements. On the other hand, the thickness of the portion where the outer peripheral groove 103 is formed contributes almost nothing to the strength, so the outer diameter of the housing 102 is the sum of the thickness required to ensure the necessary strength and the thickness of the portion where the outer peripheral groove 103 is formed. Furthermore, because a cover 104 is provided on its outer periphery, the radial dimension of the machine body becomes even larger. In addition, since the cover 104 also needs to ensure airtightness in the axial direction, a seal 107 such as an O-ring is required, and space must be secured for that as well, resulting in a problem of reduced space efficiency of the cooling mechanism.

[0007] Furthermore, due to the thickness of the housing 102, the distance between the outer ring 101 and the outer groove 103 increases, which reduces the cooling efficiency. As a result, it becomes necessary to supply cooling oil that has been cooled excessively in order to meet the required amount of cooling heat. In addition, in recent years, due to advancements in condition monitoring technology, there has been an increase in cases where sensors are installed near rolling bearings. However, in the typical cooling passage 105 shown in Figure 6, it is difficult to secure a path for the sensor to access the rolling bearing 100, which may make sensor installation difficult.

[0008] The present invention has been made in view of the aforementioned problems, and its objective is to provide a rolling bearing device that can improve the space efficiency of the cooling mechanism and improve cooling efficiency by supplying cooling oil closer to the bearing. [Means for solving the problem]

[0009] Therefore, the above objective of the present invention is achieved by the following configuration [1] relating to a rolling bearing device. [1] comprising a housing, a rotating shaft disposed inside the housing, and a rolling bearing that rotatably supports the rotating shaft relative to the housing, The rolling bearing device is provided with a cooling passage for cooling the rolling bearing in the housing, A rolling bearing device in which a plurality of V-shaped holes are formed in the circumferential direction in the cylindrical portion of the housing that fits the outer ring of the rolling bearing, so as to form a circulating path that communicates in a zigzag pattern along the circumferential direction. [Effects of the Invention]

[0010] According to the rolling bearing device of the present invention, a plurality of V-shaped holes arranged in the circumferential direction are formed in the cylindrical portion of the housing to constitute a circulating path that communicates in a zigzag pattern along the circumferential direction. This improves the space efficiency of the cooling mechanism without significantly reducing the strength of the housing, and also improves cooling efficiency by allowing cooling oil to be supplied closer to the bearing. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view of a spindle assembly of a machine tool to which a rolling bearing device according to one embodiment of the present invention is applied. [Figure 2A] Figure 2A is a side view of the housing shown in Figure 1. [Figure 2B] Figure 2B is a cross-sectional view of AA in Figure 2A. [Figure 2C] Figure 2C is a cross-sectional view of BB in Figure 2A. [Figure 3] Figure 3 is a side view of the housing showing the positions of the axial hole and the V-shaped hole. [Figure 4] Figure 4 is a side view of a modified example of the housing according to the present invention. [Figure 5] Figure 5 is a cross-sectional view of a housing corresponding to Figure 2C, which relates to another modification of the present invention. [Figure 6] Figure 6 is a cross-sectional view of a machine tool spindle unit to which a conventional rolling bearing cooling mechanism is applied. [Modes for carrying out the invention]

[0012] FIG. 1 is a cross-sectional view of a spindle device of a machine tool to which a rolling bearing device according to an embodiment of the present invention is applied. As shown in FIG. 1, in a spindle device 10 of a motor-built-in type machine tool, a rotating shaft 11 is rotatably supported by a housing H by two rows of front bearings (rolling bearings) 50 arranged on the tool side (left side in FIG. 1) and two rows of rear bearings (rolling bearings) 60 arranged on the opposite tool side (right side in FIG. 1). The housing H is mainly composed of a front housing 12, a rear housing 14, and a rear cover 15 in order from the tool side, and is fastened and fixed by bolts (not shown).

[0013] Each of the front bearings 50 is an angular ball bearing having an outer ring 51, an inner ring 52, balls 53 as rolling elements arranged with a contact angle, and a cage (not shown), and each of the rear bearings 60 is an angular ball bearing having an outer ring 61, an inner ring 62, balls 63 as rolling elements arranged with a contact angle, and a cage (not shown). The front bearings 50 and the rear bearings 60 are arranged so as to cooperate with each other to form a back-to-back combination.

[0014] The outer ring 51 of the front bearing 50 is fitted into a cylindrical portion 13A in front of the front housing 12 and is axially positioned and fixed to the front housing 12 via an outer ring spacer 54 by a front outer ring retainer 16 screwed and fixed to a female screw (not shown) formed in the cylindrical portion 13A.

[0015] The inner ring 52 of the front bearing 50 is fitted onto the rotating shaft 11 and is axially positioned and fixed to the rotating shaft 11 via an inner ring spacer 55 by a nut 17 fastened to the rotating shaft 11.

[0016] The outer ring 61 of the rear bearing 60 is fitted into a sleeve 18 that is axially slidable and fitted into the rear housing 14, and is axially positioned and fixed to the sleeve 18 via an outer ring spacer 64 by an outer ring retainer 19 integrally fixed to the sleeve 18 with bolts (not shown).

[0017] The inner ring 62 of the rear bearing 60 is externally fitted onto the rotary shaft 11, and is axially positioned and fixed to the rotary shaft 11 via the inner ring spacer 65 and the detected portion 67 of the speed sensor by a nut 21 fastened to the rotary shaft 11.

[0018] A coil spring (not shown) is disposed between the rear housing 14 and the outer ring retainer 19, and the spring force of this coil spring presses the outer ring retainer 19 rearward together with the sleeve 18. Thereby, preload is applied to the front bearing 50 and the rear bearing 60.

[0019] The rotary shaft 11 is formed hollow, and on the tool side of the rotary shaft 11, a tool mounting hole 11a for mounting a tool (not shown) such as a cutting tool is provided. Instead of the tool mounting hole 11a, a drawbar (not shown) may be slidably inserted into the interior of the rotary shaft 11. The drawbar includes a collet portion (not shown) for fixing a tool holder, and is also urged in the direction opposite to the tool side by the force of a disc spring disposed inside the rotary shaft 11.

[0020] A motor 30 including a rotor 31 rotatably integrated with the rotary shaft 11 and a stator 32 disposed around the rotor 31 is disposed substantially at the axial center between the front bearing 50 and the rear bearing 60 of the rotary shaft 11. The stator 32 is fixed to the front housing 12 by fitting a cooling jacket 33 shrink-fitted to the stator 32 into a cylindrical portion 13B behind the front housing 12 constituting the housing H.

[0021] The motor 30 generates a rotational force on the rotor 31 by supplying power to the stator 32 via an electric wire to rotate the rotary shaft 11. The motor 30 is housed in a motor chamber 34 which is a space surrounded by the front housing 12, the rear housing 14, and the sleeve 18 around the rotary shaft 11.

[0022] The rear cover 15 is disposed behind the rotary shaft 11, and forms a rear space 45 together with the rear housing 14 and the sleeve 18.

[0023] Next, the cooling mechanism for cooling the front bearing 50 will be described in detail with reference to Figures 2A to 3.

[0024] As shown in Figures 2A to 2C, the interior of the cylindrical portion 13A of the front housing 12 includes six axial holes 72 spaced 60° apart in the circumferential direction and having openings 72a at the axial end faces 12a of the cylindrical portion 13A, and six V-shaped holes 73 whose respective ends are connected to adjacent axial holes 72 and which are formed in planes parallel to the central axis CL1 of the front housing 12 and arranged in the circumferential direction. As shown in Figure 2C, the V-shaped holes 73 are formed by merging two inclined holes that are inclined with respect to the central axis CL1 of the front housing 12 at a confluence point 74.

[0025] Then, the opening 72a of the axial hole 72 is closed by the front outer ring retainer 16 which is attached to the axial end face 12a of the cylindrical portion 13A of the front housing 12. As a result, a circulating path 71 is formed inside the cylindrical portion 13A of the front housing 12, communicating in a zigzag pattern along the circumferential direction.

[0026] Furthermore, in the circulation path 71, as shown in Figure 3, the polygon formed by connecting the centerlines CL of the multiple V-shaped holes 73, that is, the polygon formed by connecting the centers O of the six axial holes 72, is formed to be a regular hexagon when viewed from the axial direction.

[0027] Although the opening angle of each V-shaped hole 73 can be set arbitrarily, setting them to the same angle results in a more uniform cooling effect on the front bearing 50 from the circumferential direction.

[0028] The V-shaped holes 73 are machined from the openings 72a of each axial hole 72 that open to the axial end face 12a after the axial holes 72 have been formed. This makes it easier to machine the inclined V-shaped holes 73. Note that the diameter of the axial holes 72 is larger than the diameter of the V-shaped holes 73.

[0029] A seal groove 72b is formed around each axial hole 72, into which a sealing member 80 such as an O-ring is fitted. The sealing member 80 seals the space between the axial end face 12a of the cylindrical portion 13A and the axial end face of the front outer ring retainer 16.

[0030] Furthermore, as shown in Figure 2B, a fluid supply channel 81 extending across the front housing 12, rear housing 14, and rear cover 15 is connected to the confluence point 74 of the upper V-shaped hole 73. In addition, a fluid discharge channel 82 extending across the front housing 12, rear housing 14, and rear cover 15 is connected to the confluence point 74 of the lower V-shaped hole 73. Thus, the fluid supply channel 81, circulation path 71, and fluid discharge path 82 constitute a cooling path.

[0031] As described above, in the rolling bearing device, a circulation path 71 is provided in the cylindrical portion 13A of the front housing 12, including a plurality of V-shaped holes 73. Coolant is supplied from the fluid supply passage 81 to the circulation path 71 to cool the front bearing 50, and the coolant is discharged from the fluid discharge passage 82. Therefore, the circulation path 71 can be formed by the plurality of V-shaped holes 73 without significantly reducing the strength of the front housing 12, improving the space efficiency of the cooling mechanism.

[0032] Furthermore, since the circulation path 71 is arranged substantially uniformly in the radial direction near the front bearing 50, the front bearing 50 can be cooled efficiently and uniformly.

[0033] Furthermore, the axial hole 72 having an opening 72a in the axial end face 12a of the cylindrical portion 13A of the front housing 12 is closed by the front outer ring retainer 16, and the front outer ring retainer 16 is used as a sealing cover, so the space required to seal the circulation path 71 can be minimized, and the space efficiency of the cooling mechanism is improved.

[0034] Furthermore, a path for accessing a sensor (not shown) located in the front bearing 50 can be easily secured between the V-shaped holes 73 formed in the circumferential direction, making it easier to install the sensor.

[0035] Furthermore, the present invention is not limited to the embodiments described above, and can be modified, improved, and so on as appropriate. For example, in the above embodiment, the polygon formed by connecting the centerlines CL of the multiple V-shaped holes 73 when viewed from the axial direction is a regular hexagon, but the present invention is not limited to this, and it is preferable to use a regular polygon.

[0036] As shown in the modified example in Figure 4, the number of axial holes 72 and V-shaped holes 73 (12 in Figure 4) is increased, and the regular polygon formed by connecting the centerlines CL of the multiple V-shaped holes 73 is made into a regular dodecagon. As a result, the circulation path 71 becomes closer to a circle compared to the above embodiment, so that the circulation path 71 can be installed at a more uniform distance from the front bearing 50, enabling more uniform cooling.

[0037] Furthermore, the axial hole 72 and the V-shaped hole 73 may be formed at any radial position in the cylindrical portion 13A of the front housing 12, but from the viewpoint of cooling, it is preferable that they be in the vicinity of the front bearing 50.

[0038] Furthermore, in the above embodiment, the circulation path 71 is composed of a plurality of axial holes 72 and a plurality of V-shaped holes 73. However, if the ends of each V-shaped hole 73 are connected to each other and open to the axial end face 12a of the cylindrical portion 13A of the front housing 12, the circulation path 71 may be composed of a plurality of V-shaped holes 73 without providing a plurality of axial holes.

[0039] Furthermore, if the outer ring retainer cannot be attached to the axial end face 12a of the cylindrical portion 13A of the front housing 12, the opening 72a of the axial hole 72 may be closed by an annular closing member attached to the axial end face 12a of the cylindrical portion 13A of the front housing 12.

[0040] For example, as shown in Figure 5, a plug 90 may be installed in place of the sealing member 80 at the opening 72a of the axial hole 72. This allows the opening 72a of the axial hole 72 to be sealed by the front housing 12 and the plug 90 without the need for the sealing member 80 and the outer ring retainer 16. The plug 90 can be of any type, such as a drive-in type or a screw-type plug.

[0041] Furthermore, while the above embodiment described an example in which a rolling bearing device equipped with a cooling mechanism for cooling the rolling bearings is applied to the spindle of a machine tool, the present invention is not limited to this and may also be applied to lathes, rotary tables, and the like.

[0042] As described above, the following matters are disclosed in this specification: (1) comprising a housing, a rotating shaft disposed inside the housing, and a rolling bearing that rotatably supports the rotating shaft relative to the housing, The rolling bearing device is provided with a cooling passage for cooling the rolling bearing in the housing, A rolling bearing device in which a plurality of V-shaped holes are formed in the circumferential direction in the cylindrical portion of the housing that fits the outer ring of the rolling bearing, so as to form a circulating path that communicates in a zigzag pattern along the circumferential direction. This configuration improves the space efficiency of the cooling mechanism without significantly reducing the strength of the housing, and also improves cooling efficiency by allowing cooling oil to be supplied closer to the bearings.

[0043] (2) The cylindrical portion of the housing is further formed with a plurality of axial holes having openings on the axial end faces of the cylindrical portion, which connect the ends of adjacent V-shaped holes to each other. The opening of the axial hole is closed by an outer ring retainer attached to the axial end face of the cylindrical portion of the housing. (1) The rolling bearing device described in (1). This configuration allows for easy formation of circulation paths, improving the space efficiency of the cooling mechanism.

[0044] (3) A sealing member is provided around each of the axial holes to seal the space between the axial end face of the cylindrical portion and the axial end face of the outer ring retainer. (2) The rolling bearing device described in (2). This configuration allows for space-efficient sealing of the cooling mechanism.

[0045] (4) The centerlines of each V-shaped hole are formed in their respective planes parallel to the central axis of the housing. (1) The rolling bearing device described in (1). This configuration allows for easy machining of V-shaped holes and enables cooling of rolling bearings from nearly uniform positions in the radial direction.

[0046] (5) When viewed from the axial direction, the polygon formed by connecting the centerlines of the plurality of V-shaped holes is a regular polygon. (4) The rolling bearing device described in (4). This configuration allows for nearly uniform cooling of the rolling bearings.

[0047] (6) Used in the spindle of a machine tool, A rolling bearing device as described in any one of (1) to (5). This configuration allows for effective cooling of the rolling bearings in the spindle of a machine tool. [Explanation of Symbols]

[0048] 10. Spindle assembly (rolling bearing assembly) of machine tools 11 Rotation axis 12 Front housing (housing) 13A Cylindrical part 12a Axial end face 16. Front outer ring retainer (outer ring retainer) 50 Front bearing (rolling bearing) 51 Outer ring 71 Circulation pathways 72 Axial hole 73 V-shaped hole CL V-shaped hole centerline CL1 Housing Central Axis

Claims

1. The device comprises a housing, a rotating shaft disposed inside the housing, and a rolling bearing that rotatably supports the rotating shaft relative to the housing, The rolling bearing device is provided with a cooling passage for cooling the rolling bearing in the housing, A rolling bearing device in which a plurality of V-shaped holes are formed in the circumferential direction in the cylindrical portion of the housing that fits the outer ring of the rolling bearing, so as to form a circulating path that communicates in a zigzag pattern along the circumferential direction.

2. The cylindrical portion of the housing is further formed with a plurality of axial holes, each having an opening at the axial end face of the cylindrical portion, which connect the ends of adjacent V-shaped holes. The opening of the axial hole is closed by an outer ring retainer attached to the axial end face of the cylindrical portion of the housing. The rolling bearing device according to claim 1.

3. A sealing member is provided around each of the aforementioned axial holes to seal the space between the axial end face of the cylindrical portion and the axial end face of the outer ring retainer. The rolling bearing device according to claim 2.

4. The centerlines of each of the aforementioned V-shaped holes are formed in their respective planes parallel to the central axis of the housing. The rolling bearing device according to claim 1.

5. When viewed from the axial direction, the polygon formed by connecting the centerlines of the multiple V-shaped holes is a regular polygon. The rolling bearing device according to claim 4.

6. Used in the spindle mechanism of machine tools, A rolling bearing device according to any one of claims 1 to 5.

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