Preload bearing device and preload adjustment method

Abstract

The present invention provides a preload bearing device that can suppress changes (increases) in preload due to temperature rise caused by heat generation during operation (rotation). [Solution] The preload bearing device 10 comprises a first angular contact bearing unit 16, a second angular contact bearing unit 18, and a preload application mechanism 20. The preload application mechanism 20 applies preload by elastically pressing the first outer ring 172 of the first angular contact bearing unit 16 and the second outer ring 192 of the second angular contact bearing unit 18 in the axial direction. The first preload application unit 52 is positioned between the first outer ring 172 and the second outer ring 192. The second preload application unit 54 is positioned between the second outer ring 192 and the second wall portion 42b, and presses the second outer ring 192 toward the first outer ring 172 and the first wall portion 42a.

Description

Technical Field

[0006] , , , ,

[0001] The present invention relates to a preload bearing device and a preload adjustment method.

Background Art

[0002] Conventionally, a preload bearing device used in a state where a constant pressure preload is applied to a plurality of angular bearings is disclosed, for example, in Japanese Patent Application Laid-Open No. 2007-113777.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described conventional technology, an elastic member for applying a preload is disposed between the inner ring tightening nut and the inner ring. By adjusting the tightening degree of the inner ring tightening nut, the preload on the angular bearing can be adjusted. However, since the preload change is too sensitive to the position change of the inner ring tightening nut, there is a problem that preload adjustment is difficult. Further, there is a problem that the preload changes (increases) due to the temperature rise caused by heat generation during operation (rotation), and the preload cannot be kept constant.

[0005] An object of the present invention is to solve the above-described problems.

Means for Solving the Problems

[0006] A first aspect of the present disclosure is a preloaded bearing device comprising: a rotating shaft; a housing surrounding the rotating shaft; a first angular contact bearing unit disposed between the rotating shaft and the housing; a second angular contact bearing unit disposed between the rotating shaft and the housing, spaced axially apart from the first angular contact bearing unit; and a preloading mechanism that elastically presses a first outer ring, which is the outer ring of the first angular contact bearing unit, and a second outer ring, which is the outer ring of the second angular contact bearing unit, in the axial direction to apply preload, wherein the first outer ring and the second outer ring are housed in an outer ring housing provided in the housing, and the outer ring housing in the axial direction The preload bearing device comprises a first wall portion, which is one side wall of the outer ring housing portion, and a second wall portion, which is the other side wall of the outer ring housing portion in the axial direction, with the first outer ring positioned between the first wall portion and the second outer ring, and the second outer ring positioned between the first outer ring and the second wall portion, and the preload application mechanism comprising a first preload application portion positioned between the first outer ring and the second outer ring, which presses the first outer ring toward the first wall portion and the second outer ring toward the second wall portion, and a second preload application portion positioned between the second outer ring and the second wall portion, which presses the second outer ring toward the first outer ring and the first wall portion.

[0007] A second aspect of this disclosure is a preload adjustment method for a preload bearing device according to the first aspect, comprising: a parameter measurement step of performing a rotation test of the preload bearing device and measuring parameters for preload adjustment; and a dimension adjustment step of performing preload adjustment by adjusting the dimensions of a specific part of the housing based on the parameters. [Effects of the Invention]

[0008] According to this disclosure, the preload adjustment after assembly of the preload bearing device can be performed with high precision. [Brief explanation of the drawing]

[0009] [Figure 1]Figure 1 is a cross-sectional view of a spindle device equipped with a preload bearing device according to an embodiment of this disclosure. [Figure 2] Figure 2 is a flowchart of the preload adjustment method. [Figure 3] Figure 3 is a conceptual diagram of the preload bearing device shown in Figure 1. [Figure 4] Figure 4 is a conceptual diagram of a preload bearing device according to a reference example. [Modes for carrying out the invention]

[0010] As shown in Figure 1, the preload bearing device 10 is provided in the spindle device 100. The spindle device 100 is part of a machine tool and is a rotary drive unit that rotates a tool. The tool is, for example, a drill or a grinding wheel. The spindle device 100 comprises a rotating shaft 12, a housing 14, a motor 15, a first angular contact bearing unit 16, a second angular contact bearing unit 18, and a preload application mechanism 20.

[0011] The rotating shaft 12 is the main shaft of the spindle device 100. The rotating shaft 12 rotates around the axis Ax. Hereinafter, for the spindle device 100 and its various components, one side of the rotating shaft 12 in the axial direction (X direction) (X1 direction side) will be referred to as the "tip side" or "tip portion," and the other side in the axial direction (X2 direction side) will be referred to as the "base end side" or "base end portion." A tool (not shown) is attached to the tip of the rotating shaft 12.

[0012] The housing 14 is a cylindrical body that surrounds the rotating shaft 12. The housing 14 extends in the axial direction. The housing 14 has a housing body 22, an end plate 24, and a cover member 26. The housing body 22 has a motor housing section 28 and a bearing housing section 30. The motor housing section 28 surrounds the motor 15. The bearing housing section 30 surrounds the first angular contact bearing unit 16 and the second angular contact bearing unit 18.

[0013] The end plate 24 is fixed to the base end of the housing body 22 by fastening components (bolts, etc.) not shown. The end plate 24 is an annular member. Multiple bearings 32 are arranged between the inner circumference of the end plate 24 and the rotating shaft 12. Only one bearing 32 may be arranged. The cover member 26 is fixed to the front end of the housing body 22 by fastening components (bolts, etc.) not shown. The cover member 26 is an annular member.

[0014] The motor 15 is a rotating electric machine for rotating the rotating shaft 12. The motor 15 has a rotor 34 and a stator 36. The rotor 34 is fixed to the rotating shaft 12. The stator 36 is fixed to the housing 14. Specifically, the stator 36 is fixed to the motor housing portion 28 of the housing body 22.

[0015] The first angular contact bearing unit 16 has a plurality of first angular contact bearings 17 arranged in the axial direction. In this embodiment, there are two first angular contact bearings 17. An annular first spacer 38 is positioned between the two first angular contact bearings 17. The first spacer 38 has an inner spacer 38a and an outer spacer 38b. In other embodiments, the number of first angular contact bearings 17 may be one or three or more.

[0016] Each first angular contact bearing 17 has a first inner ring 170, a first outer ring 172, and a first ball 174. The first outer ring 172 of each first angular contact bearing 17 is axially slidable relative to the housing body 22. In each first angular contact bearing 17, the line of action L1 of the force connecting the contact point between the first inner ring 170 and the first ball 174 and the contact point between the first outer ring 172 and the first ball 174 (hereinafter referred to as "first line of action L1") is inclined with respect to the radial direction.

[0017] The first acting line L1 is inclined with respect to the radial direction such that the outer diameter side approaches the second angular bearing unit 18. An inner spacer 38a of the first spacer 38 is disposed between the two first inner rings 170. An outer spacer 38b of the first spacer 38 is disposed between the two first outer rings 172. The outer spacer 38b is axially slidable with respect to the housing body 22.

[0018] The second angular bearing unit 18 has a plurality of second angular bearings 19 arranged axially. In the present embodiment, the number of the second angular bearings 19 is two. An annular second spacer 40 is disposed between the two second angular bearings 19. The second spacer 40 has an inner spacer 40a and an outer spacer 40b. In other aspects, the number of the second angular bearings 19 may be one or three or more.

[0019] Each second angular bearing 19 has a second inner ring 190, a second outer ring 192, and second balls 194. The second outer ring 192 of each second angular bearing 19 is axially slidable with respect to the housing body 22. In each second angular bearing 19, a force acting line L2 (hereinafter referred to as "second acting line L2") connecting the contact point between the second inner ring 190 and the second balls 194 and the contact point between the second outer ring 192 and the second balls 194 is inclined with respect to the radial direction.

[0020] The second acting line L2 is inclined with respect to the radial direction such that the outer diameter side approaches the first angular bearing unit 16. The inner spacer 40a of the second spacer 40 is disposed between the two second inner rings 190. The outer spacer 40b of the second spacer 40 is disposed between the two second outer rings 192. The outer spacer 40b is axially slidable with respect to the housing body 22.

[0021] The first outer ring 172 and the second outer ring 192 are accommodated in an outer ring accommodating portion 42 provided in the housing 14. The lid member 26 closes one side of the outer ring accommodating portion 42. Between a first wall portion 42a which is a wall on one side (X1 direction side) of the outer ring accommodating portion 42 in the axial direction and a second wall portion 42b which is a wall on the other side (X2 direction side) of the outer ring accommodating portion 42 in the axial direction, the first outer ring 172 and the second outer ring 192 are arranged. The first wall portion 42a constitutes a part of the lid member 26.

[0022] The lid member 26 is provided with a protrusion 27 protruding toward the first outer ring 172. The protrusion 27 abuts on the first outer ring 172 on the tip side in the first angular bearing unit 16 and presses the first outer ring 172 in the axial direction. The protrusion 27 is annular and extends in the circumferential direction of the housing 14. The housing main body 22 has a surrounding wall portion 44 extending axially from the second wall portion 42b and surrounding the first outer ring 172 and the second outer ring 192. The first outer ring 172 is arranged between the first wall portion 42a and the second outer ring 192. The second outer ring 192 is arranged between the first outer ring 172 and the second wall portion 42b.

[0023] An annular central spacer 46 is arranged between the first inner ring 170 and the second inner ring 190 adjacent to each other in the axial direction. The first angular bearing unit 16 and the second angular bearing unit 18 are arranged between an annular convex portion 48 provided on the outer peripheral portion of the rotating shaft 12 and a fastening nut 50 attached to the rotating shaft 12. The annular convex portion 48 abuts on the second outer ring 192 of the second angular bearing 19 on the base end side in the second angular bearing unit 18.

[0024] The fastening nut 50 abuts on the first inner ring 170 of the first angular bearing 17 on the tip side in the first angular bearing unit 16. The fastening nut 50 is arranged inside the lid member 26. The two first inner rings 170 of the first angular bearing unit 16 and the two second inner rings 190 of the second angular bearing unit 18 are axially positioned and fixed by being axially tightened by the fastening nut 50.

[0025] The preload application mechanism 20 applies preload by elastically pressing the first outer ring 172 of the first angular contact bearing unit 16 and the second outer ring 192 of the second angular contact bearing unit 18 in the axial direction. The preload application mechanism 20 has a first preload application section 52 and a second preload application section 54.

[0026] The first preloading unit 52 is positioned between the first outer ring 172 and the second outer ring 192, which are adjacent to each other in the axial direction. The first preloading unit 52 presses the first outer ring 172 toward the first wall portion 42a and the second outer ring 192 toward the second wall portion 42b. The first preloading unit 52 is slidable in the axial direction relative to the housing body 22.

[0027] The first preloading unit 52 includes a first pressing member 56, a second pressing member 58, a piston 60, and an elastic member 62. The first pressing member 56 presses against the first outer ring 172. The first pressing member 56 is formed in an annular shape surrounding the rotating shaft 12. The first pressing member 56 has a first contact projection 57 that protrudes toward the first outer ring 172. The first contact projection 57 is an annular shape that extends in the circumferential direction. Multiple first contact projections 57 may be provided spaced apart from each other in the circumferential direction.

[0028] The second pressing member 58 presses against the second outer ring 192. The second pressing member 58 is formed in an annular shape surrounding the rotating shaft 12. The second pressing member 58 has a second contact projection 59 that protrudes toward the second outer ring 192. The second contact projection 59 is an annular shape that extends in the circumferential direction. Multiple second contact projections 59 may be provided at intervals from each other in the circumferential direction. The second pressing member 58 has a housing groove 64. Multiple housing grooves 64 are provided. Multiple housing grooves 64 are provided at intervals from each other along the circumferential direction of the housing 14.

[0029] The piston 60 is positioned between the first pressing member 56 and the second pressing member 58. The piston 60 is in contact with the first pressing member 56. A portion of the piston 60 is housed in the housing groove 64 of the second pressing member 58. Multiple pistons 60 are provided. The multiple pistons 60 are spaced apart from each other along the circumferential direction of the housing 14.

[0030] The elastic member 62 (hereinafter referred to as the "first elastic member 62") is positioned between the first pressing member 56 and the second pressing member 58. The first elastic member 62 is positioned between the piston 60 and the second pressing member 58. The first elastic member 62 presses the piston 60 toward the first pressing member 56. The first elastic member 62 is housed in the housing groove 64. The first elastic member 62 is, for example, a coil spring. The first elastic member 62 may be composed of a plurality of disc springs arranged in the axial direction. A plurality of first elastic members 62 are provided. The plurality of first elastic members 62 are provided spaced apart from each other along the circumferential direction.

[0031] The receiving groove 64 may also be provided in the first pressing member 56. In this case, the piston 60 abuts against the second pressing member 58, and the first elastic member 62 is positioned between the first pressing member 56 and the piston 60.

[0032] The second preloading section 54 is positioned between the adjacent second outer ring 192 and the second wall portion 42b. The second preloading section 54 presses the second outer ring 192 toward the first outer ring 172 and the first wall portion 42a. The second preloading section 54 includes an annular pressing member 66 and an elastic member 68. The annular pressing member 66 is formed in an annular shape surrounding the rotating shaft 12. The annular pressing member 66 presses the second outer ring 192. The annular pressing member 66 is axially slidable relative to the housing body 22. The annular pressing member 66 has a pressing projection 67 that protrudes toward the second outer ring 192. The pressing projection 67 is annular and extends in the circumferential direction. Multiple pressing projections 67 may be provided spaced apart from each other in the circumferential direction.

[0033] The elastic member 68 (hereinafter referred to as the "second elastic member 68") presses the annular pressing member 66 toward the second outer ring 192. The second elastic member 68 is housed in a spring arrangement groove 70 provided in the second wall portion 42b of the housing body 22. The spring arrangement groove 70 may be provided in a member other than the housing body 22. Multiple second elastic members 68 are provided. Multiple second elastic members 68 are provided at intervals from each other along the circumferential direction. Therefore, multiple spring arrangement grooves 70 are provided at intervals from each other along the circumferential direction.

[0034] The second elastic member 68 is, for example, a coil spring. The second elastic member 68 may be composed of a plurality of disc springs arranged in the axial direction. The spring constant of the second elastic member 68 of the second preloading unit 54 is smaller than the spring constant of the first elastic member 62 of the first preloading unit 52. That is, the spring constant of the second preloading unit 54 is smaller than the spring constant of the first preloading unit 52. The spring constant of the second elastic member 68 is, for example, 30% to 70% of the spring constant of the first elastic member 62. Alternatively, the spring constant of the second elastic member 68 is, for example, 40% to 60% of the spring constant of the first elastic member 62.

[0035] Next, the method for adjusting the preload of the preload bearing device 10 will be described.

[0036] As shown in Figure 2, the preload adjustment method includes a parameter measurement step S1 and a dimensional adjustment step S2. In the parameter measurement step S1, after assembling the preload bearing device 10 (spindle device 100), a rotation test of the preload bearing device 10 is performed to measure the parameters for preload adjustment. In the parameter measurement step S1, the preload bearing device 10 to be measured is in a provisional assembly state. When assembling the preload bearing device 10, it is assembled so that there is a specified amount of pressure against the first outer ring 172. The specified amount of pressure is an initial value for adjustment and is the initial protrusion length of the projection 27 of the cover member 26. Basically, it is good practice to set the initial protrusion length of the projection 27 with the expectation that the protrusion length will be adjusted by grinding down the projection 27. The parameters include at least the temperature of the first angular contact bearing unit 16 or the second angular contact bearing unit 18. The parameters also include the rigidity of the preload bearing device 10.

[0037] In the dimensional adjustment process S2, preload adjustment is performed by adjusting the dimensions of specific parts of the housing 14 based on the parameters obtained by measurement. Specifically, in the dimensional adjustment process S2, preload adjustment is performed by adjusting (increasing or decreasing) the protruding length of the projection 27, which is a specific part.

[0038] In the dimensional adjustment process S2, the preload is calculated based on the temperature measured by the rotation test. In this case, the preload can be calculated (obtained) by referring to a pre-prepared correspondence table (reference table) showing the relationship between temperature and preload. Then, the displacement is adjusted based on the obtained preload. Specifically, after removing the lid member 26 from the housing body 22, the protruding length of the projection 27 is adjusted. In this case, the amount of displacement adjustment can be calculated (obtained) by referring to a pre-prepared correspondence table (reference table) showing the relationship between preload and displacement. The larger the displacement, the lower the preload (details will be described later). Therefore, reducing the displacement increases the preload. The displacement can be reduced by shaving (shortening) the projection 27.

[0039] After adjusting the dimensions of the projection 27 to obtain the desired preload, the preload bearing device 10 (spindle device 100) is reassembled. Specifically, if the preload obtained based on temperature is less than the desired set value (set range), the projection 27 is shortened to achieve the set value. On the other hand, if the preload obtained based on temperature is greater than the desired set value, the projection 27 is lengthened to achieve the set value. Instead of lengthening the projection 27, an additional spacer may be placed.

[0040] If the temperature measured by the rotation test in parameter measurement step S1 is higher than the temperature reference value (temperature upper limit), a cover member 26 with an increased thrust (length of projection 27) is prepared, and the preload bearing device 10 is reassembled. When preparing the cover member 26 with an increased thrust, the cover member 26 may be machined to increase the thrust. Increasing the protruding length of the projection 27 reduces the preload, and therefore the temperature during rotation also decreases. If the axial rigidity of the preload bearing device 10 obtained in parameter measurement step S1 is lower than the reference value (rigidity lower limit), the preload is increased by reducing the thrust.

[0041] Figure 3 is a conceptual diagram of the preload bearing device 10. The first movable element 80 and the second movable element 82 are elements that can move axially relative to the housing 14 and the rotating shaft 12. The first movable element 80 represents the two first outer rings 172 of the first angular contact bearing unit 16, the outer spacer 38b, and the first pressing member 56 as a single element. The second movable element 82 represents the second pressing member 58, the two second outer rings 192 of the second angular contact bearing unit 18, the outer spacer 40b, and the annular pressing member 66 as a single element.

[0042] In Figure 3, the first ball 174 of the first angular contact bearing unit 16 and the second ball 194 of the second angular contact bearing unit 18 are represented as spring elements (first spring 84 and second spring 86). K1 is the spring constant of the first spring 84 (first ball 174). K2 is the spring constant of the second spring 86 (second ball 194). Ka is the spring constant of the first elastic member 62 of the first preload application unit 52. Kb is the spring constant of the second elastic member 68 of the second preload application unit 54. Note that K1 and K2 are much larger than Ka and Kb.

[0043] Figure 3 shows how the lengths of the first spring 84 and the second spring 86 change depending on the magnitude (length) of the compression allowance relative to the first movable element 80. As shown in the lower part of Figure 3, when the compression allowance (the axial relative displacement of the first movable element 80 relative to the housing 14) is increased, the first elastic member 62 of the first preload application section 52 and the second elastic member 68 of the second preload application section 54 contract in the axial direction. In this case, since Kb is smaller than Ka, the amount of contraction of the second elastic member 68 is greater than the amount of contraction of the first elastic member 62. On the other hand, the rotating shaft 12 and the housing 14 are displaced relative to each other in the axial direction. As a result of this contraction of the first elastic member 62 and the second elastic member 68 and the axial relative displacement between the rotating shaft 12 and the housing 14, the first spring 84 and the second spring 86 stretch. The stretching of the first spring 84 and the second spring 86 means a decrease in preload. From this, it can be seen that the preload decreases as the compression allowance increases. The extension amounts of the first spring 84 and the second spring 86 are far smaller than the increase in the compression allowance. Therefore, the change in preload is small in relation to the change in compression allowance. In other words, the change in preload is insensitive to the change in compression allowance. As a result, preload adjustment is easy, and precise preload adjustment can be performed after assembly.

[0044] On the other hand, Figure 4 is a conceptual diagram of a preload bearing device 10R relating to a comparative example. In the preload bearing device 10R, the preload can be adjusted because pushing the movable element 90 in the axial direction causes the movable element 90 to be displaced axially relative to the housing 14. However, since most of the displacement of the movable element 90 is absorbed as the compression of the elastic member 92, the extension amounts of the first spring 84 and the second spring 86 become large. For this reason, the change in preload is large in relation to the change in the amount of pressure applied to the movable element 90. In other words, the change in preload is sensitive to the change in the amount of pressure applied, making it difficult to adjust the preload accurately. Furthermore, since the movable element 90 must be located inside the housing 14, adjusting the preload requires disassembly and subsequent reassembly, or a suitable adjustment mechanism, making preload adjustment difficult.

[0045] Furthermore, under forces in the X2 direction less than the spring load (the force compressing the spring) of the second elastic member 68 in Figure 3, none of the components of the preload bearing device 10 move at all. Therefore, the rigidity of the preload bearing device 10 is equivalent to that of a typical constant-pressure preload structure (preload bearing device 10R in Figure 4). For this reason, there is no reduction in rigidity in the X2 direction due to the position and direction of the second elastic member 68 in the preload bearing device 10.

[0046] The preload bearing device 10 according to this embodiment, shown in Figure 1, provides the following effects.

[0047] The preload bearing device 10 includes not only a first preload application unit 52 positioned between the first angular contact bearing unit 16 and the second angular contact bearing unit 18, but also a second preload application unit 54 positioned axially outward from the first angular contact bearing unit 16 and the second angular contact bearing unit 18. This allows for accurate preload adjustment after assembly of the preload bearing device 10.

[0048] The spring constant of the second preload application unit 54 (second elastic member 68) is smaller than the spring constant of the first preload application unit 52 (first elastic member 62). With this configuration, more reliable and accurate preload adjustment can be achieved.

[0049] The first preload application unit 52 presses the first outer ring 172 with a first pressing member 56 and the second outer ring 192 with a second pressing member 58, with a piston 60 and a second elastic member positioned between the first pressing member 56 and the second pressing member 58. With this configuration, pressing force can be effectively applied to the first angular contact bearing unit 16 and the second angular contact bearing unit 18.

[0050] Each of the first pressing member 56 and the second pressing member 58 is formed in an annular shape, and multiple combinations of the piston 60 and the first elastic member 62 are arranged at intervals in the circumferential direction. With this configuration, the axial pressing force can be generated uniformly in the circumferential direction.

[0051] The second preload application unit 54 includes an annular pressing member 66 formed in an annular shape and a second elastic member 68 that presses the annular pressing member 66 toward the second outer ring 192. With this configuration, pressing force can be effectively applied to the second angular contact bearing unit 18.

[0052] The housing 14 has a cover member 26 that is connected to the housing body 22 and closes one side of the outer ring housing 42. The preload can be adjusted by adjusting the dimensions of the cover member 26. With this configuration, the preload can be easily adjusted in the preload adjustment process after temporary assembly by adjusting the dimensions of the cover member 26. In other words, the preload can be adjusted by disassembling and reassembling the preload bearing device 10 with minimal man-hours after assembly.

[0053] The cover member 26 is provided with a projection 27 that protrudes toward the first outer ring 172. By adjusting the protruding length of the projection 27, the preload applied to the first angular contact bearing unit 16 and the second angular contact bearing unit 18 can be adjusted. With this configuration, the preload can be easily adjusted by adjusting the dimensions of the projection 27.

[0054] The following additional information is disclosed regarding the above embodiments.

[0055] (Note 1) The preload bearing device (10) of the present disclosure comprises a rotating shaft (12), a housing (14) surrounding the rotating shaft, a first angular contact bearing unit (16) disposed between the rotating shaft and the housing, a second angular contact bearing unit (18) disposed between the rotating shaft and the housing, spaced axially apart from the first angular contact bearing unit, and a preload applying mechanism (20) that elastically presses the first outer ring (172), which is the outer ring of the first angular contact bearing unit, and the second outer ring (192), which is the outer ring of the second angular contact bearing unit, in the axial direction to apply preload, wherein the first outer ring and the second outer ring are housed in an outer ring housing portion (42) provided in the housing. The outer ring housing is arranged between a first wall portion (42a), which is one side wall of the outer ring housing in the axial direction, and a second wall portion (42b), which is the other side wall of the outer ring housing in the axial direction, with the first outer ring positioned between the first wall portion and the second outer ring, and the second outer ring positioned between the first outer ring and the second wall portion. The preloading portion is positioned between the first outer ring and the second outer ring and includes a first preloading portion (52) that presses the first outer ring toward the first wall portion and the second outer ring toward the second wall portion, and a second preloading portion (54) that is positioned between the second outer ring and the second wall portion and presses the second outer ring toward the first outer ring and the first wall portion. With this configuration, the preload bearing device is equipped not only with a first preload application unit positioned between the first and second angular contact bearing units, but also with a second preload application unit positioned axially outward from both the first and second angular contact bearing units. Therefore, preload adjustment after assembly can be performed with high precision.

[0056] (Note 2) In the preload bearing device described in Note 1, the spring constant of the second preload application unit may be smaller than the spring constant of the first preload application unit. With such a configuration, accurate preload adjustment can be performed more reliably.

[0057] (Note 3) In the preload bearing device described in Note 1 or 2, the first preload application unit may include a first pressing member (56) that presses the first outer ring, a second pressing member (58) that presses the second outer ring, a piston (60) disposed between the first pressing member and the second pressing member, and an elastic member (62) disposed between the first pressing member and the second pressing member that presses the piston toward the first pressing member or the second pressing member. With such a configuration, pressing force can be effectively applied to the first angular contact bearing unit and the second angular contact bearing unit.

[0058] (Note 4) In the preload bearing device described in Note 3, each of the first pressing member and the second pressing member is formed in an annular shape surrounding the rotating shaft, and each of the pistons and elastic members may be provided in multiples, with the multiple pistons spaced apart from each other along the circumferential direction of the housing, and the multiple elastic members spaced apart from each other along the circumferential direction. With such a configuration, the axial pressing force can be generated uniformly in the circumferential direction.

[0059] (Note 5) In the preload bearing device described in any one of Notes 1 to 4, the second preload application unit may include an annular pressing member (66) formed in an annular shape surrounding the rotating shaft and pressing against the second outer ring, and an elastic member (68) that presses the annular pressing member toward the second outer ring. With such a configuration, pressing force can be applied to the second angular contact bearing unit effectively.

[0060] (Note 6) In the preload bearing device described in any one of Notes 1 to 5, the housing comprises a housing body (22) having a second wall portion and a surrounding wall portion (44) extending axially from the second wall portion and surrounding the first outer ring and the second outer ring, and a lid member (26) connected to the housing body, having a first wall portion and closing one side of the outer ring housing portion, and the preload applied to the first angular contact bearing unit and the second angular contact bearing unit can be adjusted by adjusting the dimensions of the lid member. With this configuration, the preload can be easily adjusted in the preload adjustment process after temporary assembly by adjusting the dimensions of the lid member.

[0061] (Note 7) In the preload bearing device described in Note 6, the cover member may be provided with a projection (27) that protrudes toward the first outer ring. With this configuration, the preload can be easily adjusted by adjusting the dimensions of the projection.

[0062] (Note 8) The preload adjustment method of the present disclosure is a preload adjustment method for a preload bearing device described in Note 1, comprising: a parameter measurement step (S1) of performing a rotation test of the preload bearing device and measuring parameters for preload adjustment; and a dimension adjustment step (S2) of performing the preload adjustment by adjusting the dimensions of a specific part of the housing based on the parameters.

[0063] (Note 9) In the preload adjustment method described in Note 8, the housing comprises a housing body having a second wall portion and a surrounding wall portion extending axially from the second wall portion and surrounding the first outer ring and the second outer ring, and a lid member connected to the housing body, having the first wall portion and closing one side of the outer ring housing portion, wherein the lid member is provided with a projection that protrudes toward the first outer ring, and in the dimension adjustment step, the preload adjustment may be performed by adjusting the protruding length of the projection, which is the specific location.

[0064] (Note 10) In the preload adjustment method described in Note 8, the parameter may be the temperature of the first angular contact bearing unit or the second angular contact bearing unit, or the rigidity of the preload bearing device.

[0065] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the intent of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of symbols]

[0066] 10…Preloaded bearing device 12…Rotating shaft 14…Housing 16…First angular contact bearing unit 17…First angular contact bearing 18…Second angular contact bearing unit 19...Second angular contact bearing 20...Preload application mechanism 22…Housing body 26…Lid component 27…Protrusion 42…Outer ring housing 42a...First wall part 42b...Second wall part 44...Enclosing wall section 52...First pre-pressure application section 54...Second preload application section 172...First outer ring 192...Second outer ring

Claims

1. Rotating shaft and A housing surrounding the aforementioned rotating shaft, A first angular contact bearing unit is positioned between the rotating shaft and the housing, Between the rotating shaft and the housing, a second angular contact bearing unit is positioned axially apart from the first angular contact bearing unit, A preload application mechanism that elastically presses the first outer ring, which is the outer ring of the first angular contact bearing unit, and the second outer ring, which is the outer ring of the second angular contact bearing unit, in the axial direction to apply preload, A preload bearing device equipped with, The first outer ring and the second outer ring are housed in an outer ring housing provided in the housing. The first outer ring and the second outer ring are positioned between a first wall portion, which is one wall of the outer ring housing portion in the axial direction, and a second wall portion, which is the other wall of the outer ring housing portion in the axial direction. The first outer ring is positioned between the first wall portion and the second outer ring. The second outer ring is positioned between the first outer ring and the second wall portion. The preload application mechanism is, A first preloading unit is positioned between the first outer ring and the second outer ring, and presses the first outer ring toward the first wall and the second outer ring toward the second wall; A preload bearing device comprising: a second preload application unit disposed between the second outer ring and the second wall portion, which presses the second outer ring toward the first outer ring and the first wall portion.

2. In the preload bearing device according to claim 1, A preload bearing device in which the spring constant of the second preload-applying section is smaller than the spring constant of the first preload-applying section.

3. In the preload bearing device according to claim 1, The first preload application unit is, A first pressing member that presses against the first outer ring, A second pressing member that presses against the second outer ring, A piston positioned between the first pressing member and the second pressing member, A preload bearing device comprising: an elastic member disposed between the first pressing member and the second pressing member, which presses the piston toward the first pressing member or the second pressing member.

4. In the preload bearing device according to claim 3, Each of the first pressing member and the second pressing member is formed in an annular shape surrounding the rotating shaft, Each of the pistons and elastic members is provided in multiple quantities. The multiple pistons are arranged at intervals from each other along the circumferential direction of the housing. A preload bearing device in which a plurality of the aforementioned elastic members are provided spaced apart from one another along the circumferential direction.

5. In the preload bearing device according to claim 1, The second preload application unit is, An annular pressing member formed in a ring shape surrounding the rotating shaft and pressing against the second outer ring, A preload bearing device comprising an elastic member that presses the annular pressing member toward the second outer ring.

6. In the preload bearing device according to any one of claims 1 to 5, The aforementioned housing is A housing body having the second wall portion and a surrounding wall portion extending axially from the second wall portion and surrounding the first outer ring and the second outer ring, The housing body is connected to a lid member having the first wall portion and closing one side of the outer ring housing portion, A preload bearing device in which the preload applied to the first angular contact bearing unit and the second angular contact bearing unit can be adjusted by adjusting the dimensions of the cover member.

7. In the preload bearing device according to claim 6, A preload bearing device wherein the cover member is provided with a projection that protrudes toward the first outer ring.

8. A method for adjusting the preload of a preload bearing device according to claim 1, A parameter measurement step involves performing a rotational test on the aforementioned preload bearing device and measuring parameters for preload adjustment. A preload adjustment method comprising: a dimensional adjustment step of performing the preload adjustment by adjusting the dimensions of a specific part of the housing based on the aforementioned parameters.

9. In the preload adjustment method according to claim 8, The aforementioned housing is A housing body having the second wall portion and a surrounding wall portion extending axially from the second wall portion and surrounding the first outer ring and the second outer ring, The housing body is connected to a lid member having the first wall portion and closing one side of the outer ring housing portion, The lid member is provided with a projection that protrudes toward the first outer ring. A preload adjustment method comprising the dimensional adjustment step, in which the preload adjustment is performed by adjusting the protruding length of the projection, which is the specific location.

10. In the preload adjustment method according to claim 8, A preload adjustment method wherein the parameter is the temperature of the first angular contact bearing unit or the second angular contact bearing unit, or the rigidity of the preload bearing device.

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