Spindle device

Abstract

To provide a spindle device which can increase a water proof property by preventing an entry of liquid from outside.SOLUTION: A spindle device includes: a housing 2; a rolling bearing 21 rotationally supporting a rotational shaft 3 with respect to the housing 2; a first outer ring spacer 41 which is provided on a front side in an axial direction of a rolling bearing 21 exposed to a liquid atmosphere, and positions an outer ring of the rolling bearing 21 in an axial direction with respect to the housing 2; a first inner ring spacer 45 which is provided on an inner side in a radial direction of a the first outer rig spacer 41 and positions an inner ring of the rolling bearing 21 in an axial direction with respect to the rotational shaft 3; grease reservoir recesses 42, 46 provided on an inner peripheral face 41c of the first outer ring spacer 41 and an outer peripheral face 45c of the first inner rig spacer 45 which are adjacent to face to each other; a surface treatment layer 50 applied on the surfaces of the first outer ring spacer 41 and the first inner ring spacer 45 and having a water repellent / oil repellent effect; and a grease 60 filled in the grease reservoir recesses 42, 46.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a spindle device, and more particularly to an improvement in a spindle device that prevents liquid from entering from the outside and improves waterproofing. [Background technology]

[0002] The rotating shaft of the spindle in a machine tool's main spindle unit rotates at high speeds while cutting and grinding. It is necessary to spray a large amount of liquid forcefully onto the machining area for lubrication purposes (for example, to improve cutting characteristics (sharpness), reduce wear on the tool cutting edge, and extend tool life) and cooling purposes (for example, to improve machining accuracy by suppressing temperature rise in the tool and workpiece, to prevent welding due to heat generated in the machining area, to improve machining efficiency, and to prevent deterioration of the surface quality and quality of the workpiece due to heat (sparks, etc.)).

[0003] As a result, since the machining area is close to the spindle, a large amount of liquid also gets on the front of the spindle. If this liquid gets inside the bearing, it can cause problems with lubrication and seizure, so waterproofing is important.

[0004] Therefore, conventionally, grease-filled lubrication, grease replenishment lubrication, oil and air lubrication, oil mist lubrication, etc. have been used for spindle devices. In particular, with grease-filled lubrication and grease replenishment lubrication, compared to oil and air lubrication and oil mist lubrication, the internal pressure is lower because no air is pumped into the spindle, and waterproof performance is inferior, so waterproof performance is important.In contrast, with oil and air lubrication and oil mist lubrication, air is pumped inside, so the internal pressure of the spindle becomes greater than the external pressure (atmospheric pressure), creating an air flow from inside the spindle to the outside, making it difficult for liquids from outside to enter.

[0005] For example, in a conventional spindle device 101, as shown in FIG. 10, the rotating shaft 103 is rotatably supported relative to the housing 102 by a front bearing device 120 arranged axially forward of the rotating shaft 103 and a rear bearing device (not shown) arranged axially rearward of the rotating shaft 103. The front bearing device 120 includes four rolling bearings 121 arranged back to back with an outer ring spacer 123 and an inner ring spacer 125 sandwiched therebetween.

[0006] The outer rings of these four rolling bearings 121 are fixed to the housing 102 by the front cover 113, and the inner rings are fixed to the rotating shaft 103 with a predetermined preload applied by nuts 127. An inner ring spacer 115 fitted onto the rotating shaft 103 is interposed between the rotating shaft 103 and the inner rings.

[0007] Cover 111 is placed in front of rotating shaft 103, and the gap between inner ring spacer 115 attached to rotating shaft 103 and front cover 113 inside it is made into a labyrinth structure to prevent the intrusion of liquids from outside. However, if a large amount of liquid is sprayed onto the front surface of the spindle, the liquid may pass through the labyrinth and enter the inside of the bearing, possibly causing damage to the bearing.

[0008] Therefore, Patent Document 1 describes a bearing waterproofing mechanism that forms a labyrinth gap between a housing and a member attached to the rotating shaft, and waterproofs the surfaces of both members that form the labyrinth gap by providing a water-repellent coating, thereby extending the life of the bearing portion. Patent document 2 also describes a waterproof structure for the output shaft, which provides a grease reservoir at the output shaft contact point of the rubber seal that contacts the rotating sliding part of the output shaft, thereby reducing the impact of component precision on the seal of the sliding part. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-327764 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-187076 Summary of the Invention [Problem to be solved by the invention]

[0010] However, with the conventional waterproof structures described above, it is difficult to adequately prevent liquid from penetrating into the bearing when a large amount of liquid is sprayed onto it, such as in the spindle device of a machine tool, and further improvements in waterproofing are desired.

[0011] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a spindle device that can prevent liquid from entering from the outside and improve waterproofing. [Means for solving the problem]

[0012] The above object of the present invention is achieved by the following configuration (1). (1) Housing; a rolling bearing that rotatably supports a rotary shaft relative to the housing; a first outer ring spacer that is disposed axially forward of the rolling bearing that is exposed to a liquid atmosphere and that positions an outer ring of the rolling bearing relative to the housing in the axial direction; a first inner ring spacer arranged radially inward of the first outer ring spacer to position the inner ring of the rolling bearing in the axial direction with respect to the rotating shaft; a grease reservoir recess provided on at least one of an inner peripheral surface of the first outer ring spacer and an outer peripheral surface of the first inner ring spacer, which are closely opposed to each other; a surface treatment layer having water and oil repellency applied to the surface of each of the first outer ring spacer and the first inner ring spacer; Grease filled in the grease reservoir recess; A spindle device comprising: [Effects of the Invention]

[0013] According to the spindle device of the present invention, it is possible to prevent the intrusion of liquid from the outside and improve waterproofing. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a vertical cross-sectional view of a spindle device according to a first embodiment of the present invention. [Figure 2] 2 is an enlarged cross-sectional view of a front bearing device disposed axially forward of the spindle device shown in FIG. [Figure 3] 3 is an enlarged cross-sectional view of a main part of the front bearing device shown in FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a main part of a front bearing device in a spindle device according to a second embodiment of the present invention. [Figure 5] FIG. 5 is an enlarged cross-sectional view of a main part of a front bearing device in a spindle device according to a third embodiment of the present invention. [Figure 6] FIG. 6 is an enlarged cross-sectional view of a main part of a front bearing device in a spindle device according to a fourth embodiment of the present invention. [Figure 7] FIG. 7 is an enlarged cross-sectional view of a main part of a front bearing device in a spindle device according to a fifth embodiment of the present invention. [Figure 8] FIG. 8 is an enlarged cross-sectional view of a main part of a front bearing device in a spindle device according to a sixth embodiment of the present invention. [Figure 9] FIG. 9 is an enlarged cross-sectional view of a main part of a front bearing device in a spindle device according to a seventh embodiment of the present invention. [Figure 10] FIG. 10 is an enlarged cross-sectional view of a front bearing device in a conventional spindle device. DETAILED DESCRIPTION OF THE INVENTION

[0015] The spindle devices according to each embodiment of the present invention will be described in detail below with reference to the drawings. Note that the spindle devices of each embodiment will be described as being applied to a spindle device for a machine tool spindle, but it goes without saying that they can also be applied to a spindle device for a high-speed motor, or a spindle device for a rotating machine that rotates at high speed, such as a centrifuge or turbo refrigerator.

[0016] (First embodiment) FIG. 1 is a vertical cross-sectional view of a spindle device 1 according to a first embodiment of the present invention. As shown in FIG. 1, in the spindle device 1 according to the first embodiment, the rotating shaft 3 is rotatably supported relative to the housing 2 by a front bearing device 20 arranged axially forward of the rotating shaft 3 and a rear bearing device 30 arranged axially rearward of the rotating shaft 3.

[0017] The rotary shaft 3 is configured in a hollow cylindrical shape, and a draw bar 5 is provided inside the cylinder, which is biased by a disc spring 4 and is slidable inside the cylinder. A chuck portion 6 is provided at the tip of the draw bar 5 to hold and release a tool attached to the rotary shaft 3.

[0018] The front bearing device 20 has four rolling bearings 21 assembled back-to-back with an outer ring spacer 23 and an inner ring spacer 25 sandwiched between them, and the rear bearing device 30 has one rolling bearing 31. Of course, the number and combination form of the multiple rolling bearings 21 to be assembled are not limited to this.

[0019] The rear bearing device 30 is a bearing device that includes a rolling bearing 31, which is a cylindrical roller bearing that rotatably supports the rotating shaft 3 relative to the housing 2, an outer ring holder 17, which is an outer ring positioning member that is fitted inside the housing 2 and positions the outer ring of the rolling bearing 31 in the axial direction, and an inner ring holder 19, which is an inner ring positioning member that is fitted outside the rotating shaft 3 and positions the inner ring of the rolling bearing 31 in the axial direction.

[0020] Fig. 2 is an enlarged cross-sectional view of a front bearing device 20 arranged axially forward of the spindle device 1 shown in Fig. 1. Fig. 3 is an enlarged cross-sectional view of a main part of the front bearing device 20 shown in Fig. 2. As shown in Figure 2, the front bearing device 20 according to this first embodiment is a bearing device comprising a housing 2 and rolling bearings 21, which are four angular ball bearings arranged back to back to support the rotating shaft 3 rotatably relative to the housing 2.

[0021] The front bearing device 20 is disposed axially forward (left side in FIG. 2 ) of the rolling bearing 21, which is exposed to a liquid atmosphere, and comprises a first outer ring spacer 41 that axially positions the outer ring of the rolling bearing 21 relative to the housing 2, a second outer ring spacer 13 interposed between the outer ring of the rolling bearing 21 and the first outer ring spacer 41, and an outer ring holder 31. A cover 11 that covers the front bearing device 20 and fixes the outer ring holder 31 to the housing 2 is attached to the front side of the housing 2.

[0022] The cylindrical first outer ring spacer 41 fitted inside the housing 2 has its outer surface liquid-tightly sealed to the housing 2 by an O-ring 51 arranged on the inner surface of the housing 2.

[0023] A discharge port 14 that penetrates radially is formed in a cylindrical second outer ring spacer 13 that is fitted into the housing 2. When the second outer ring spacer 13 is fitted into the housing 2, it is assembled so that the discharge port 14 communicates with a lubricant discharge port 35 that is provided vertically below the housing 2.

[0024] A discharge port 33 that penetrates radially is formed in outer ring retainer 31, which is fixed to the open end of housing 2. When outer ring retainer 31 is fixed to housing 2, it is assembled so that discharge port 33 is positioned vertically downward.

[0025] Furthermore, the front bearing device 20 includes a first inner ring spacer 45 that is arranged radially inward of the first outer ring spacer 41 and that positions the inner ring of the rolling bearing 21 in the axial direction relative to the rotating shaft 3, and a second inner ring spacer 15 that is interposed between the inner ring of the rolling bearing 21 and the first inner ring spacer 45. The front bearing device 20 also includes a nut 27 that is fixed to the rotating shaft 3 with a predetermined preload applied to the inner ring of the bearing between it and the shoulder 3a of the rotating shaft 3.

[0026] The cylindrical first inner ring spacer 45 that is fitted onto the rotating shaft 3 has its inner surface liquid-tightly sealed against the rotating shaft 3 by an O-ring 53 arranged on the outer surface of the rotating shaft 3.

[0027] 3, when arranged axially forward of the rolling bearing 21, the inner circumferential surface 41c of the first outer ring spacer 41 and the outer circumferential surface 45c of the first inner ring spacer 45, which are closely opposed to each other, have a cylindrical shape extending axially forward. Furthermore, the inner circumferential surface 41c of the first outer ring spacer 41 and the outer circumferential surface 45c of the first inner ring spacer 45 are respectively provided with grease reservoir recesses 42, 46. The grease reservoir recesses 42, 46 are circumferential grooves with rectangular cross sections, and are each filled with grease 60.

[0028] Furthermore, a surface treatment layer 50 (shown by cross-hatching in FIG. 3) having water- and oil-repellent properties is applied to the surfaces of the first outer ring spacer 41 and the first inner ring spacer 45. The surface treatment layer 50 is applied to the surfaces of the first outer ring spacer 41 and the first inner ring spacer 45 by coating them with, for example, a fluororesin or silicone resin, or by coating them with an oil-repellent agent made of a fluorine-based compound.

[0029] It is desirable that the surface treatment layer 50 be applied to at least the front and rear end faces (both axial end faces) 41a, 41b and inner peripheral surface 41c of the first outer ring spacer 41, and the front and rear end faces 45a, 45b and outer peripheral surface 45c of the first inner ring spacer 45. For example, it is possible to omit the surface treatment layer 50 applied to the outer peripheral surface of the first outer ring spacer 41 that is liquid-tight sealed to the housing 2 by the O-ring 51, or the inner peripheral surface of the first inner ring spacer 45 that is liquid-tight sealed to the rotating shaft 3 by the O-ring 53.

[0030] The second inner ring spacer 15 fitted onto the rotating shaft 3 is formed with an L-shaped cross section, with a flange portion 16 protruding radially outward from the rear end of the outer peripheral surface. Thus, the flange portion 16 of the second inner ring spacer 15 covers the annular space between the inner ring and outer ring of the rolling bearing 21 in the first row from the axial front of the four rolling bearings 21 exposed to the liquid atmosphere, and can prevent liquid from entering the inside of the bearing.

[0031] As described above, according to the spindle device 1 of the first embodiment, the surface treatment layer 50 having water- and oil-repellent properties is applied to the surfaces of the first outer ring spacer 41 and the first inner ring spacer 45, which are arranged axially forward of the rolling bearing 21 that is exposed to a liquid atmosphere. 3, water droplets 65 that come into contact with the front end face (front axial end face) 45a of the first inner ring spacer 45 fly liquids such as grinding fluid radially outward due to centrifugal force, thereby improving waterproofing. In addition, the lotus effect of the surface having the minute irregularities and surface treatment layer 50 turns water into droplets, making it difficult for water droplets 65 to penetrate into the radial gap between the first outer ring spacer 41 and the first inner ring spacer 45.

[0032] Furthermore, the water- and oil-repellent effects improve the dischargeability of liquid that is thrown axially forward of the rolling bearing 21 by the centrifugal force of the first inner ring spacer 45 from the discharge port 33 of the outer ring holder 31. In addition, the water- and oil-repellent effects also improve the dischargeability of moisture that passes through the radial gap between the first outer ring spacer 41 and the first inner ring spacer 45 from the discharge port 14 and lubricant discharge port 35 of the second outer ring spacer 13.

[0033] Furthermore, according to the spindle device 1 of the first embodiment, grease reservoir recesses 42, 46 are provided on the inner peripheral surface 41c of the first outer ring spacer 41 and the outer peripheral surface 45c of the first inner ring spacer 45, respectively, and are filled with grease 60. Therefore, when the first inner ring spacer 45 rotates, only the grease 60 at the contacting portions is expelled, forming a minute gap between the grease 60 filled in the grease reservoir recesses 42, 46. Therefore, the bank (embankment) formed by the grease 60 makes it difficult for water droplets 65 that have entered the radial gap between the first outer ring spacer 41 and the first inner ring spacer 45 to penetrate inside. Furthermore, if the filled grease 60 is water-repellent, the waterproof effect is further improved.

[0034] Therefore, the spindle device 1 of the first embodiment can prevent liquid from entering from the outside and improve waterproofing. As a result, it is possible to prevent a large amount of liquid splashed on the front surface of the spindle from entering the inside of the rolling bearing 21, thereby preventing problems such as poor lubrication of the bearing or seizure.

[0035] (Second embodiment) 4 is an enlarged cross-sectional view of a main part of a front bearing device 20A in a spindle unit 1 according to a second embodiment of the present invention. Note that the front bearing device 20A according to this second embodiment has the same basic configuration as the front bearing device 20 according to the first embodiment, and therefore the same or corresponding parts are denoted by the same reference numerals, and description thereof will be omitted or simplified.

[0036] As shown in Figure 4, the front bearing device 20A according to the second embodiment comprises a first outer ring spacer 41 that is arranged axially forward (to the left in Figure 4) of the rolling bearing 21 that is exposed to a liquid atmosphere and that positions the outer ring of the rolling bearing 21 axially relative to the housing 2, a second outer ring spacer 13 that is interposed between the outer ring of the rolling bearing 21 and the first outer ring spacer 41, and an outer ring holder 31.

[0037] The front bearing device 20A also includes a first inner ring spacer 45 that is arranged radially inward of the first outer ring spacer 41 and positions the inner ring of the rolling bearing 21 axially relative to the rotating shaft 3, and a second inner ring spacer 15A that is interposed between the inner ring of the rolling bearing 21 and the first inner ring spacer 45.

[0038] The surfaces of the first outer ring spacer 41 and the first inner ring spacer 45 are coated with a surface treatment layer 50 (shown by cross-hatching in FIG. 4) that has water-repellent and oil-repellent properties. Therefore, the centrifugal force of the water droplets 65 that come into contact with the front end surface 45a of the first inner ring spacer 45 causes liquid such as grinding fluid to fly outward in the radial direction, thereby improving waterproofing.

[0039] Furthermore, the second inner ring spacer 15A fitted onto the rotating shaft 3 is formed with an L-shaped cross section, with a flange portion 16 protruding radially outward from the rear end of the outer peripheral surface, and the surface (inner peripheral surface) of the second inner ring spacer 15A is also treated with a surface treatment layer 50 having water- and oil-repellent properties. Therefore, the flange portion 16 of the second inner ring spacer 15A, which is treated with the surface treatment layer 50, covers the annular space between the inner ring and outer ring of the rolling bearing 21 in the first row from the axial front of the four rolling bearings 21 that are exposed to the liquid atmosphere, and since a water- and oil-repellent effect is obtained in multiple stages, it is possible to further suppress the intrusion of liquid into the interior of the bearing.

[0040] Therefore, according to the spindle device 1 equipped with the front bearing device 20A according to the second embodiment, in addition to the same effects as those of the spindle device 1 of the first embodiment, it is possible to further improve waterproofing.

[0041] (Third embodiment) 5 is an enlarged cross-sectional view of a main part of a front bearing device 20B in a spindle unit 1 according to a third embodiment of the present invention. Note that the front bearing device 20B according to this third embodiment has the same basic configuration as the front bearing device 20 according to the first embodiment, and therefore the same or corresponding parts are denoted by the same reference numerals, and description thereof will be omitted or simplified.

[0042] As shown in Figure 5, the front bearing device 20B according to the third embodiment comprises a first outer ring spacer 41 that is arranged axially forward (to the left in Figure 5) of the rolling bearing 21 that is exposed to a liquid atmosphere and that positions the outer ring of the rolling bearing 21 axially relative to the housing 2, a second outer ring spacer 13 that is interposed between the outer ring of the rolling bearing 21 and the first outer ring spacer 41, and an outer ring holder 31.

[0043] The front bearing device 20B also includes a first inner ring spacer 45B that is arranged radially inward of the first outer ring spacer 41 and positions the inner ring of the rolling bearing 21 axially relative to the rotating shaft 3, and a second inner ring spacer 15 that is interposed between the inner ring of the rolling bearing 21 and the first inner ring spacer 45B.

[0044] 5, when arranged axially forward of the rolling bearing 21, the inner peripheral surface 41c of the first outer ring spacer 41 and the outer peripheral surface 45c of the first inner ring spacer 45B, which are closely opposed to each other, have a cylindrical shape extending axially forward. Furthermore, the inner peripheral surface 41c of the non-rotating side first outer ring spacer 41 is provided with a grease reservoir recess 42 to be filled with grease 60, but the outer peripheral surface 45c of the rotating side first inner ring spacer 45B is not provided with a grease reservoir recess 46.

[0045] A surface treatment layer 50 (shown by cross-hatching in FIG. 5) having water-repellent and oil-repellent properties is applied to the surfaces of the first outer ring spacer 41 and the first inner ring spacer 45B. Therefore, water droplets 65 that come into contact with the front end surface 45a of the first inner ring spacer 45B splash liquid such as grinding fluid radially outward due to centrifugal force, thereby improving waterproofing.

[0046] Furthermore, as the first inner ring spacer 45B rotates, only the grease 60 at the contact area is expelled, forming a minute gap between the grease 60 filled in the grease reservoir recess 42 and the outer peripheral surface 45c of the first inner ring spacer 45B. Thus, the bank (embankment) formed by the grease 60 makes it difficult for water droplets 65 that have entered the radial gap between the first outer ring spacer 41 and the first inner ring spacer 45B to enter the interior of the bearing.

[0047] Therefore, according to the spindle device 1 equipped with the front bearing device 20B of this third embodiment, even if the grease reservoir recess 42 is provided only on the inner surface 41c of the first outer ring spacer 41, it is possible to obtain the same effects as those of the spindle device 1 of the first embodiment described above.

[0048] (Fourth embodiment) 6 is an enlarged cross-sectional view of a main part of a front bearing device 20C in a spindle unit 1 according to a fourth embodiment of the present invention. Note that the front bearing device 20C according to the fourth embodiment has the same basic configuration as the front bearing device 20 according to the first embodiment, and therefore the same or corresponding parts are denoted by the same reference numerals, and description thereof will be omitted or simplified.

[0049] As shown in Figure 6, the front bearing device 20C according to the fourth embodiment comprises a first outer ring spacer 41C that is arranged axially forward (to the left in Figure 6) of the rolling bearing 21 that is exposed to a liquid atmosphere and that positions the outer ring of the rolling bearing 21 axially relative to the housing 2, a second outer ring spacer 13 that is interposed between the outer ring of the rolling bearing 21 and the first outer ring spacer 41C, and an outer ring holder 31.

[0050] Furthermore, the front bearing device 20C includes a first inner ring spacer 45C arranged radially inward of the first outer ring spacer 41C to position the inner ring of the rolling bearing 21 axially relative to the rotating shaft 3, and a second inner ring spacer 15 interposed between the inner ring of the rolling bearing 21 and the first inner ring spacer 45C.

[0051] 6, when arranged axially forward of the rolling bearing 21, the inner peripheral surface 41c of the first outer ring spacer 41C and the outer peripheral surface 45c of the first inner ring spacer 45C, which are closely opposed to each other, have a tapered shape that widens in diameter toward the axial front. Furthermore, the inner peripheral surface 41c of the first outer ring spacer 41C and the outer peripheral surface 45c of the first inner ring spacer 45C are each provided with grease reservoir recesses 42, 46 that are filled with grease 60.

[0052] Moreover, a surface treatment layer 50 (shown by cross-hatching in FIG. 6) having water-repellent and oil-repellent properties is applied to the surfaces of the first outer ring spacer 41C and the first inner ring spacer 45C. Therefore, water droplets 65 that come into contact with the front end surface 45a of the first inner ring spacer 45C splash liquid such as grinding fluid radially outward due to centrifugal force, thereby improving waterproofing.

[0053] As described above, in the spindle unit 1 equipped with the front bearing device 20C according to the fourth embodiment, the inner peripheral surface 41c of the first outer ring spacer 41C and the outer peripheral surface 45c of the first inner ring spacer 45C have a tapered shape that widens in diameter toward the axial front. Therefore, water droplets 65 that have entered the radial gap between the first outer ring spacer 41C and the first inner ring spacer 45C are discharged axially forward of the first outer ring spacer 41C along the tapered inner and outer peripheral surfaces 41c and 45c due to the centrifugal force of the first inner ring spacer 45C.

[0054] Therefore, according to the spindle device 1 equipped with the front bearing device 20C according to the fourth embodiment, in addition to the same effects as those of the spindle device 1 of the first embodiment, it is possible to further improve waterproofing.

[0055] (Fifth embodiment) 7 is an enlarged cross-sectional view of a main part of a front bearing device 20D in a spindle device 1 according to a fifth embodiment of the present invention. Note that the front bearing device 20D according to the fifth embodiment has the same basic configuration as the front bearing device 20 according to the first embodiment, and therefore the same or corresponding parts are denoted by the same reference numerals, and description thereof will be omitted or simplified.

[0056] As shown in Figure 7, the front bearing device 20D of this fifth embodiment comprises a first outer ring spacer 41D that is arranged axially forward (left side in Figure 7) of the rolling bearing 21 that is exposed to a liquid atmosphere and that positions the outer ring of the rolling bearing 21 axially relative to the housing 2, a second outer ring spacer 13D that is interposed between the outer ring of the rolling bearing 21 and the first outer ring spacer 41D, and an outer ring holder 31.

[0057] Furthermore, the front bearing device 20D is equipped with a first inner ring spacer 45D that is arranged radially inward of the first outer ring spacer 41D and positions the inner ring of the rolling bearing 21 axially relative to the rotating shaft 3, and a second inner ring spacer 15 that is interposed between the inner ring of the rolling bearing 21 and the first inner ring spacer 45D.

[0058] 7, when arranged axially forward of the rolling bearing 21, the inner peripheral surface 41c of the first outer ring spacer 41D and the outer peripheral surface 45c of the first inner ring spacer 45D, which are closely opposed to each other, have a cylindrical shape extending axially forward. Furthermore, the inner peripheral surface 41c of the first outer ring spacer 41D and the outer peripheral surface 45c of the first inner ring spacer 45D are each provided with grease reservoir recesses 42, 46 each formed of a pair (plurality of) circumferential grooves arranged along the axial direction of the rotating shaft 3, and each is filled with grease 60.

[0059] Furthermore, the first outer ring spacer 41D is provided with a circumferential discharge groove 47 with a V-shaped cross section that is provided on the inner peripheral surface 41c between the pair of grease reservoir recesses 42, and a discharge hole 48 that connects the circumferential discharge groove 47 with the rear end face 41b of the first outer ring spacer 41D. Also, the cylindrical second outer ring spacer 13D that is fitted into the housing 2 is formed with a communication hole 17 that connects the discharge port 14 with the discharge hole 48 of the first outer ring spacer 41D.

[0060] A surface treatment layer 50 (shown by cross-hatching in FIG. 7) having water-repellent and oil-repellent properties is applied to the surfaces of the first outer ring spacer 41D and the first inner ring spacer 45D. Therefore, water droplets 65 that come into contact with the front end surface 45a of the first inner ring spacer 45D splash liquid such as grinding fluid radially outward due to centrifugal force, thereby improving waterproofing.

[0061] As described above, in the spindle unit 1 equipped with the front bearing device 20D according to the fifth embodiment, the first outer ring spacer 41D is provided with the circumferential discharge groove 47 provided in the inner peripheral surface 41c and the discharge hole 48 communicating with the circumferential discharge groove 47. In addition, the second outer ring spacer 13D is provided with the communication hole 17 communicating with the discharge port 14. Therefore, water droplets 65 that have entered the radial gap between the first outer ring spacer 41D and the first inner ring spacer 45D are discharged from the discharge circumferential groove 47, which has an expanded space, through the discharge hole 48 and the communication hole 17, to the discharge port 14. As a result, it is possible to make it difficult for water droplets 65 that have entered the radial gap between the first outer ring spacer 41D and the first inner ring spacer 45D to enter the rolling bearing 21 side.

[0062] Therefore, according to the spindle device 1 equipped with the front bearing device 20D according to the fifth embodiment, in addition to the same effects as those of the spindle device 1 of the first embodiment, it is possible to further improve waterproofing.

[0063] (Sixth embodiment) 8 is an enlarged cross-sectional view of a main part of a front bearing device 20E in a spindle device 1 according to a sixth embodiment of the present invention. Note that the front bearing device 20E according to the sixth embodiment has the same basic configuration as the front bearing device 20 according to the first embodiment, and therefore the same or corresponding parts are denoted by the same reference numerals, and description thereof will be omitted or simplified.

[0064] As shown in Figure 8, the front bearing device 20E of this sixth embodiment comprises a first outer ring spacer 41E that is arranged axially forward (to the left in Figure 8) of the rolling bearing 21 that is exposed to a liquid atmosphere and that positions the outer ring of the rolling bearing 21 axially relative to the housing 2, a second outer ring spacer 13 that is interposed between the outer ring of the rolling bearing 21 and the first outer ring spacer 41E, and an outer ring holder 31.

[0065] Furthermore, the front bearing device 20E is provided with a first inner ring spacer 45E that is arranged radially inward of the first outer ring spacer 41E and positions the inner ring of the rolling bearing 21 axially relative to the rotating shaft 3, and a second inner ring spacer 15 that is interposed between the inner ring of the rolling bearing 21 and the first inner ring spacer 45E.

[0066] 8, when arranged axially forward of the rolling bearing 21, the inner peripheral surface 41c of the first outer ring spacer 41E and the outer peripheral surface 45c of the first inner ring spacer 45E, which are closely opposed to each other, have a cylindrical shape extending axially forward. Furthermore, the inner peripheral surface 41c of the first outer ring spacer 41E and the outer peripheral surface 45c of the first inner ring spacer 45E are each provided with grease reservoir recesses 42, 46 each consisting of three circumferential grooves arranged along the axial direction of the rotating shaft 3, and each is filled with grease 60.

[0067] A surface treatment layer 50 (shown by cross-hatching in FIG. 8) having water-repellent and oil-repellent properties is applied to the surfaces of the first outer ring spacer 41E and the first inner ring spacer 45E. Therefore, water droplets 65 that come into contact with the front end surface 45a of the first inner ring spacer 45E splash liquid such as grinding fluid radially outward due to centrifugal force, thereby improving waterproofing.

[0068] As described above, in the spindle unit 1 equipped with the front bearing device 20E according to the sixth embodiment, the inner surface 41c of the first outer ring spacer 41E and the outer surface 45c of the first inner ring spacer 45E are each provided with a plurality of grease reservoir recesses 42, 46 (three circumferential grooves in this embodiment), each filled with grease 60. Therefore, as the first inner ring spacer 45E rotates, only the grease 60 at the contact portions is removed, forming minute gaps between the grease 60 filled in the multiple grease reservoir recesses 42, 46. Therefore, the multiple banks (embankments) formed by the grease 60 make it difficult for water droplets 65 that have entered the radial gap between the first outer ring spacer 41E and the first inner ring spacer 45E to penetrate inside.

[0069] Therefore, according to the spindle device 1 equipped with the front bearing device 20E according to the sixth embodiment, in addition to the same effects as those of the spindle device 1 of the first embodiment, waterproofing can be further improved.

[0070] (Seventh embodiment) 9 is an enlarged cross-sectional view of a main part of a front bearing device 20F in a spindle device 1 according to a seventh embodiment of the present invention. Note that the front bearing device 20F according to the seventh embodiment has the same basic configuration as the front bearing device 20 according to the first embodiment, and therefore the same or corresponding parts are denoted by the same reference numerals, and description thereof will be omitted or simplified.

[0071] As shown in Figure 9, the front bearing device 20F according to the seventh embodiment comprises a first outer ring spacer 41F that is arranged axially forward (to the left in Figure 9) of the rolling bearing 21 that is exposed to a liquid atmosphere and that positions the outer ring of the rolling bearing 21 axially relative to the housing 2F, a second outer ring spacer 13 that is interposed between the outer ring of the rolling bearing 21 and the first outer ring spacer 41F, and an outer ring holder 31.

[0072] Furthermore, the front bearing device 20F is provided with a first inner ring spacer 45 that is arranged radially inward of the first outer ring spacer 41F and positions the inner ring of the rolling bearing 21 axially relative to the rotating shaft 3, and a second inner ring spacer 15 that is interposed between the inner ring of the rolling bearing 21 and the first inner ring spacer 45.

[0073] 9, when arranged axially forward of the rolling bearing 21, the inner peripheral surface 41c of the first outer ring spacer 41F and the outer peripheral surface 45c of the first inner ring spacer 45, which are closely opposed to each other, have a cylindrical shape extending axially forward. Furthermore, the inner peripheral surface 41c of the first outer ring spacer 41F and the outer peripheral surface 45c of the first inner ring spacer 45 are each provided with grease reservoir recesses 42, 46 into which grease 60 is filled.

[0074] Furthermore, the first outer ring spacer 41F fitted into the housing 2F is formed with a grease supply port 43 that penetrates radially and communicates with the grease reservoir recess 42. When the first outer ring spacer 41F is fitted into the housing 2F, it is assembled so that the grease supply port 43 communicates with the lubricant supply port 37 provided vertically above the housing 2F.

[0075] The surfaces of the first outer ring spacer 41F and the first inner ring spacer 45 are coated with a surface treatment layer 50 (shown by cross-hatching in FIG. 9) that has water-repellent and oil-repellent properties. Therefore, the centrifugal force of the water droplets 65 that come into contact with the front end surface 45a of the first inner ring spacer 45 causes liquid such as grinding fluid to fly outward in the radial direction, thereby improving waterproofing.

[0076] As described above, in the spindle unit 1 equipped with the front bearing device 20D according to the seventh embodiment, the first outer ring spacer 41F has a grease supply port 43 that is radially penetrated and communicates with the grease reservoir recess 42, and additional grease 60 can be supplied to the grease reservoir recess 42. Therefore, between the grease 60 filled in the grease reservoir recesses 42, 46, respectively, only the grease 60 at the contacting portions is removed by the rotation of the first inner ring spacer 45, and a minute gap is continuously formed. Therefore, the bank (embankment) formed by the grease 60 makes it difficult for water droplets 65 that have entered the radial gap between the first outer ring spacer 41F and the first inner ring spacer 45 to enter the interior stably over a long period of time.

[0077] Therefore, according to the spindle device 1 equipped with the front bearing device 20F according to the seventh embodiment, the same effects as those of the spindle device 1 of the first embodiment can be stably obtained over a long period of time.

[0078] The present invention is not limited to the above-described embodiments, and can be appropriately modified, improved, etc. Furthermore, the material, shape, size, number, location, etc. of each component in the above-described embodiments are arbitrary and not limited as long as they can achieve the present invention.

[0079] Here, the features of the embodiments of the spindle device according to the present invention described above will be briefly summarized and listed below in [1] to [7]. [1] a housing (2); a rolling bearing (21) that rotatably supports the rotary shaft (3) relative to the housing (2); a first outer ring spacer (41, 41C, 41D, 41E, 41F) disposed in front of the rolling bearing (21) exposed to a liquid atmosphere and axially positioning an outer ring of the rolling bearing (21) with respect to the housing (2); a first inner ring spacer (45, 45B, 45C, 45D, 45E) disposed radially inward of the first outer ring spacer (41, 41C, 41D, 41E, 41F) and axially positions the inner ring of the rolling bearing (21) with respect to the rotating shaft (3); a grease reservoir recess (42, 46) provided on at least one of an inner peripheral surface (41c) of the first outer ring spacer (41, 41C, 41D, 41E, 41F) and an outer peripheral surface (45c) of the first inner ring spacer (45, 45B, 45C, 45D, 45E), which are closely opposed to each other; a surface treatment layer (50) having water and oil repellency applied to the surface of each of the first outer ring spacers (41, 41C, 41D, 41E, 41F) and the first inner ring spacers (45, 45B, 45C, 45D, 45E); grease (60) filled in the grease reservoir recesses (42, 46); A spindle device (1) characterized by comprising:

[0080] According to the configuration [1] above, water droplets (65) that come into contact with the front end surface (45a) of the first inner ring spacer (45, 45B, 45C, 45D, 45E) splash liquid such as grinding fluid radially outward due to centrifugal force, thereby improving waterproofing. In addition, the lotus effect of the surface having minute irregularities turns water into droplets, which makes it difficult for water droplets (65) to penetrate into the radial gap between the first outer ring spacer (41, 41C, 41D, 41E, 41F) and the first inner ring spacer (45, 45B, 45C, 45D, 45E). Furthermore, the rotation of the first inner ring spacers (45, 45B, 45C, 45D, 45E) removes only the grease (60) at the contact portions between the grease (60) filled in the grease reservoir recesses (42, 46), forming minute gaps. Thus, the banks (embankments) formed by the grease (60) make it difficult for water droplets (65) that have entered the radial gaps between the first outer ring spacers (41, 41C, 41D, 41E, 41F) and the first inner ring spacers (45, 45B, 45C, 45D, 45E) to penetrate inside.

[0081] [2] The inner peripheral surface (41c) of the first outer ring spacer (41C) and the outer peripheral surface (45c) of the first inner ring spacer (45C) have a tapered shape that expands in diameter toward the axial front. The spindle device (1) described in [1] above.

[0082] According to the configuration [2] above, water droplets (65) that have entered the radial gap between the first outer ring spacer (41C) and the first inner ring spacer (45C) are discharged axially forward of the first outer ring spacer (41C) along the tapered inner circumferential surface (41c) and outer circumferential surface (45c) by the centrifugal force of the first inner ring spacer (45C).

[0083] [3] The grease reservoir recesses (42, 46) are formed by a plurality of circumferential grooves arranged along the axial direction of the rotating shaft (3). The spindle device (1) described in [1] above.

[0084] According to the configuration [3], the rotation of the first inner ring spacer (45E) removes only the grease (60) at the contact portions between the grease (60) filled in the grease reservoir recesses (42, 46) formed by the plurality of circumferential grooves, forming minute gaps. Thus, the plurality of banks (embankments) formed by the grease (60) make it difficult for water droplets (65) that have entered the radial gap between the first outer ring spacer (41E) and the first inner ring spacer (45E) to penetrate inside.

[0085] [4] A discharge circumferential groove (47) provided on the inner peripheral surface (41c) of the first outer ring spacer (41D); a discharge hole communicating the discharge circumferential groove (47) with a rear end surface of the first outer ring spacer; The spindle device according to [3] above, characterized by comprising:

[0086] According to the configuration [4] above, water droplets (65) that have entered the radial gap between the first outer ring spacer (41D) and the first inner ring spacer (45D) are discharged from the discharge circumferential groove (47) where the space is widened, through the discharge hole (48) and the communication hole (17). As a result, it is possible to make it difficult for the water droplets (65) that have entered the radial gap between the first outer ring spacer (41D) and the first inner ring spacer (45D) to enter the rolling bearing 21 side.

[0087] [5] A second outer ring spacer (13) having a radially penetrating discharge port (14) and interposed between the outer ring of the rolling bearing (21) and the first outer ring spacer (41); a second inner ring spacer (15A) having a flange portion (16) protruding radially inward from a rear end of an outer peripheral surface thereof, the second inner ring spacer (15A) being interposed between an inner ring of the rolling bearing (21) and the first inner ring spacer (45); a surface treatment layer (50) having water and oil repellency applied to the surface of the second inner ring spacer (15A); The spindle device (1) according to the above [1], characterized by comprising:

[0088] According to the configuration [5] above, the flange portion (16) of the second inner ring spacer (15A) to which the surface treatment layer (50) is applied covers the annular space between the inner ring and the outer ring of the rolling bearing (21) that is exposed to a liquid atmosphere, and a multi-stage water- and oil-repellent effect is obtained, thereby further suppressing the intrusion of liquid into the inside of the bearing.

[0089] [6] The grease reservoir recess (42) is provided only on the inner peripheral surface (41c) of the first outer ring spacer (41). The spindle device (1) described in [1] above.

[0090] According to the configuration [6] above, a minute gap is formed between the grease (60) filled in the grease reservoir recess (42) and the outer peripheral surface (45c) of the first inner ring spacer (45B) by the rotation of the first inner ring spacer (45B), as only the grease (60) at the contact portion is removed. Therefore, the bank (bank) formed by the grease (60) makes it difficult for water droplets (65) that have entered the radial gap between the first outer ring spacer (41) and the first inner ring spacer (45B) to enter the inside of the bearing.

[0091] [7] The first outer ring spacer (41F) has a grease supply port (43) that is radially penetrated and communicates with the grease reservoir recess (42), Additional grease (60) is supplied to the grease reservoir recess (42). The spindle device (1) described in [1] above.

[0092] According to the configuration [7], the grease (60) can be additionally supplied to the grease reservoir recess (42), and minute gaps are continuously formed between the grease (60) filled in the grease reservoir recesses (42, 46) by the rotation of the first inner ring spacer (45) as only the grease (60) at the contact portions is removed. Therefore, the bank (bank) formed by the grease (60) makes it difficult for water droplets (65) that have entered the radial gap between the first outer ring spacer (41F) and the first inner ring spacer (45) to enter the interior stably for a long period of time. [Explanation of symbols]

[0093] 1 Spindle device 2. Housing 3 Rotation Axis 21 Rolling bearings 41 First outer ring spacer 42 Grease reservoir recess 45 First inner ring spacer 46 Grease reservoir recess 50 Surface treatment layer 60 grease

Claims

1. Housing and a rolling bearing that rotatably supports a rotary shaft relative to the housing; a first outer ring spacer disposed in front of the rolling bearing exposed to a liquid atmosphere and axially positions an outer ring of the rolling bearing relative to the housing; a first inner ring spacer arranged radially inward of the first outer ring spacer to position the inner ring of the rolling bearing in the axial direction relative to the rotation shaft; a grease reservoir recess provided on at least one of an inner peripheral surface of the first outer ring spacer and an outer peripheral surface of the first inner ring spacer, which are closely opposed to each other; a surface treatment layer having water and oil repellency applied to the surface of each of the first outer ring spacer and the first inner ring spacer; Grease filled in the grease reservoir recess; A spindle device comprising:

2. an inner peripheral surface of the first outer ring spacer and an outer peripheral surface of the first inner ring spacer have a tapered shape that increases in diameter toward the axial front; The spindle device according to claim 1 .

3. The grease reservoir recess is formed by a plurality of circumferential grooves arranged along the axial direction of the rotating shaft. The spindle device according to claim 1 .

4. a circumferential groove for discharge provided on an inner peripheral surface of the first outer ring spacer; a discharge hole communicating the discharge circumferential groove with a rear end surface of the first outer ring spacer; 4. The spindle device according to claim 3, further comprising:

5. a second outer ring spacer having a discharge port penetrating in the radial direction and interposed between the outer ring of the rolling bearing and the first outer ring spacer; a second inner ring spacer having a flange portion protruding radially inward from a rear end of an outer peripheral surface thereof, the second inner ring spacer being interposed between the inner ring of the rolling bearing and the first inner ring spacer; a surface treatment layer having water and oil repellency applied to a surface of the second inner ring spacer; The spindle device according to claim 1, further comprising:

6. the grease reservoir recess is provided only on the inner circumferential surface of the first outer ring spacer, The spindle device according to claim 1 .

7. the first outer ring spacer has a grease supply port that is radially penetrated and communicates with the grease reservoir recess, Additional grease is supplied to the grease reservoir recess. The spindle device according to claim 1 .

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