Manufacturing method of hub unit bearing

Abstract

To provide a manufacturing method of a hub unit bearing which can accurately measure a size of a negative clearance and strictly control the size of the negative clearance.SOLUTION: A hub unit bearing 10 includes: a ball bearing part in which rolling elements forming one of double rows are balls; and a conical roller bearing part in which rolling elements forming the other row are conical rollers. A manufacturing method of the hub unit bearing 10 includes: a step in which a measuring jig 60 corresponding to an inner ring 37 and conical rollers 52 is assembled to a hub ring 31 to measure an axial clearance S between the inner ring 37 and the measuring jig 60 in a state where the hub ring 31, an outer ring 20, and balls 42 are assembled; and a step in which the inner ring 37 is fixedly fitted in a small diameter step part 34 of the hub ring 31 by using an assembly 55 having the inner ring 37, the conical rollers 52, and a retainer 51 so that a space between the small diameter step part 34 of the hub ring 31 and the inner ring 37 is formed into a desired negative clearance based on the measured axial clearance S.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a hub unit bearing. [Background technology]

[0002] Conventionally, a known hub unit bearing that rotatably supports an automobile wheel relative to a suspension system has a structure known as the third generation, in which an inner ring raceway is formed directly on the outer peripheral surface of a hub wheel, and in which one row of double rows of rolling elements is made up of balls and the other row is made up of tapered rollers, thereby improving moment rigidity and lifespan (see, for example, Patent Documents 1 and 2).

[0003] In this way, in a hub unit bearing (hereinafter also referred to as a "hybrid hub unit bearing") that combines a ball bearing section in which the rolling elements are balls and a tapered roller bearing section in which the rolling elements are tapered rollers, the axial rigidity of the tapered roller bearing section is much higher than that of the ball bearing section. In addition, in a hub unit bearing, a preload is applied to the bearing from the standpoint of bearing life, rigidity, fretting (false brinelling), etc., and the bearing axial clearance is made a negative clearance, but on the ball bearing section side, which has low axial rigidity, the deformation of the raceway surface and rolling elements associated with this negative clearance is biased, and unless the variation in the dimensions (dimensions related to assembly height) that contribute to the negative clearance on the tapered roller bearing section side is narrowed, the preload (axial load due to the negative clearance) applied to the ball bearing section becomes excessive, shortening the life, or problems such as reduced rigidity due to insufficient preload are likely to occur.

[0004] On the other hand, in a tapered roller bearing, the tapered rollers cannot move axially on the raceway surface, so it is difficult to measure the positive or negative clearance between the two bearings (the starting torque serves as a substitute characteristic, but in the case of a double row bearing, it is the sum of the starting torque of both rows) until the tapered rollers are aligned by moving them spirally into the aligned position through several run-in rotations (the heads of all the tapered rollers are in contact with the large rib surface and the central axes of the tapered rollers are not inclined circumferentially relative to the central axis of the bearing).In a ball bearing, the balls can move axially to a certain extent on the raceway surface, so less run-in rotation is required.

[0005] Patent Document 3 discloses a method of measuring the negative clearance of a double-row tapered roller bearing, in which an assembly of an inner ring, tapered rollers and retainer, the so-called cone, is temporarily pressed into the hub ring until a positive clearance remains, and after measuring the positive clearance, it is pressed into the normal position (the position where the front end face of the inner ring and the hub ring step surface abut), the amount of displacement at this time is determined, and the negative clearance is measured from the positive clearance value and the amount of displacement due to the press-fit. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2003-232343 A [Patent Document 2] JP 2007-290530 A [Patent Document 3] JP 2006-342877 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the measurement method described in Patent Document 3, the positive gap cannot be measured correctly unless both rows of raceway surfaces are rotated for each. Also, when re-press-fitting in the preload range, the alignment position of the tapered rollers changes depending on the preload value, so it is necessary to press-fit while rotating the outer ring and the inner ring relative to each other. Furthermore, the movement of the alignment position of the tapered rollers causes an error, and there is a problem that the measurement error is large considering the troublesome work.

[0008] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a manufacturing method for a hub unit bearing that enables the size of the bearing axial gap to be measured with high accuracy and the size of the negative gap to be strictly controlled. [Means for solving the problem]

[0009] Therefore, the above object of the present invention is achieved by the following configuration [1] relating to a manufacturing method of a hub unit bearing. [1] An outer ring having first and second outer ring raceways on an inner circumferential surface thereof; a hub having at least a flange for supporting and fixing a wheel on its outer peripheral surface, a first inner ring raceway facing the first outer ring raceway, and a small diameter step, and an inner ring that is fitted onto the outer peripheral surface of the small diameter step with its outboard end face abutting against a step surface of the small diameter step and fixed to the hub, and that has a second inner ring raceway facing the second outer ring raceway on its outer peripheral surface; a plurality of rolling elements provided in double rows between the first and second outer ring raceways and the first and second inner ring raceways so as to be rollable; A manufacturing method of a hub unit bearing comprising: The hub unit bearing includes a ball bearing portion in which the rolling elements constituting one of the double rows are balls, and a tapered roller bearing portion in which the rolling elements constituting the other row are tapered rollers, a step of assembling a measuring jig corresponding to the other of the hub ring and the inner ring, and the tapered rollers to the hub ring and one of the inner ring, in a state in which the hub ring and one of the inner ring, the outer ring, and the balls constituting an inner ring raceway on the ball bearing portion side are assembled, and measuring an axial clearance between the one of the hub ring and the inner ring and the measuring jig; a step of fitting and fixing the inner ring to the small diameter step of the hub ring using an assembly including the inner ring, the rolling elements that roll on the second outer ring raceway and the second inner ring raceway, and a retainer that holds the rolling elements, so that a desired negative clearance is obtained between the small diameter step of the hub ring and the inner ring based on the measured axial clearance; A method for manufacturing a hub unit bearing comprising: Effect of the Invention

[0010] According to the method for manufacturing a hub unit bearing of the present invention, it is possible to measure the size of the bearing axial direction gap with high accuracy, and also to strictly control the size of the negative gap. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of a hybrid hub unit bearing according to a first embodiment of the present invention. [Diagram 2] 4 is a cross-sectional view showing a method for measuring an axial gap between a measuring jig and a hub wheel by using the measuring jig according to the first embodiment. FIG. [Diagram 3] FIG. 1 is a cross-sectional view showing a method for measuring the axial distance of a so-called cone, which is an assembly of an inner ring, a tapered roller, and a cage, using a master cup. [Figure 4] 10 is a cross-sectional view showing a method for measuring an axial gap between a measuring jig and a hub wheel by using a measuring jig according to a first modified example of the first embodiment. FIG. [Diagram 5] 10 is a cross-sectional view showing a method for measuring an axial gap between a measuring jig and a hub wheel by using a measuring jig according to a second modified example of the first embodiment. FIG. [Figure 6] FIG. 6 is a cross-sectional view of a hybrid hub unit bearing according to a second embodiment of the present invention. [Figure 7] FIG. 11 is a cross-sectional view showing a method for measuring an axial gap between a measuring jig and an inner ring by using the measuring jig according to the second embodiment. [Figure 8] FIG. 11 is a cross-sectional view showing a method for measuring the axial distance of an assembly of an inner ring, a tapered roller and a cage using a master cup. [Figure 9] FIG. 11 is a cross-sectional view showing a method for measuring an axial gap between a measuring jig and an inner ring by using a measuring jig according to a first modified example of the second embodiment. [Figure 10] FIG. 11 is a cross-sectional view showing a method for measuring an axial gap between a measuring jig and an inner ring by using a measuring jig according to a second modified example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, each embodiment of a manufacturing method for a hub unit bearing according to the present invention will be described in detail with reference to the drawings.

[0013] (First embodiment) The manufacturing method for hub unit bearing 10 of this embodiment is to manufacture a hub unit bearing 10 having a desired negative clearance by replacing a cone 55 (hereinafter, one assembly may be simply referred to as cone 55) which is one assembly of inner ring 37, tapered rollers (rolling elements) 52 and cage 51 on the tapered roller bearing section 50 side (inboard side) with a measuring jig 60, measuring the axial clearance (negative clearance) between the outer ring 20, hub ring 31 and balls (rolling elements) 42 on the ball bearing section 40 side (outboard side) which will be the product, and the other assembly 70, which is the outer ring 20, hub ring 31 and balls (rolling elements) 42, and selecting a cone 55 which corresponds to the measured axial clearance, or by machining the outboard side end face 38 of the inner ring 37 to correspond to the measured axial clearance, and fitting it to the other assembly 70.

[0014] In addition, throughout this specification and the claims, "outside" in the axial direction refers to the left side in Fig. 1, which is the outer side in the width direction of the vehicle body when assembled to the automobile, and is also referred to as the "outboard side." Conversely, the right side in Fig. 1, which is the center side in the width direction of the vehicle body, is referred to as "inside" in the axial direction, and is also referred to as the "inboard side."

[0015] First, with reference to FIG. 1, the hybrid hub unit bearing of this embodiment will be briefly described. As shown in Fig. 1, the hybrid hub unit bearing 10 of this embodiment is for a driven wheel, and mainly comprises an outer ring 20, a hub 30, and a plurality of balls 42 on the outboard side and a plurality of tapered rollers 52 on the inboard side that are housed between the outer ring 20 and the hub 30 so as to be able to roll freely. That is, the hybrid hub unit bearing 10 comprises a ball bearing portion 40 having balls 42 that constitute one row on the outboard side, and a tapered roller bearing portion 50 having tapered rollers 52 that constitute the other row on the inboard side, among the double row of rolling elements.

[0016] The outer ring 20 is provided with a stationary flange 21, which is coupled to a knuckle of a suspension device, at the axially middle portion of the outer peripheral surface. On the inner peripheral surface of the outer ring 20, a first outer ring raceway 22 of a ball bearing portion 40 is formed with an arcuate cross section on the outboard side, and a second outer ring raceway 23 of a tapered roller bearing portion 50 is formed with a conical surface shape on the inboard side.

[0017] The hub 30 is composed of a hub ring 31 and an inner ring 37. The hub ring 31 is provided with a circular rotating flange 32 that extends outward from a portion that protrudes axially outward from the axially outer opening of the outer ring 20 and supports and fixes wheels (drive wheels) and rotating members for braking such as disc rotors. The hub ring 31 is disposed coaxially with the outer ring 20 on the inner diameter side of the outer ring 20, and on the outer peripheral surface of the hub ring 31, a first inner ring raceway 33 of a ball bearing portion 40 is formed in an arc-shaped cross section at the axially middle portion, and a small diameter step portion 34 is formed at the axially inner end portion.

[0018] The inner ring 37 is press-fitted onto the outer peripheral surface of the small diameter step 34 of the hub ring 31 with an interference, with its outboard end face 38 abutting against the step surface 34a of the small diameter step 34, and is fixed to the hub ring 31 by being sandwiched between a crimped portion 36 bent radially outward from the axial inner end of the hub ring 31 and the step surface 34a. On the outer peripheral surface of the inner ring 37, a second inner ring raceway 35 of the tapered roller bearing portion 50 is formed in the shape of a cone surface.

[0019] Therefore, the plurality of balls 42 are arranged between the first outer ring raceway 22 of the outer ring 20 and the second inner ring raceway 33 of the hub ring 31, while being rotatably held by the cage 41. Also, the plurality of tapered rollers 52 are arranged between the first outer ring raceway 23 of the outer ring 20 and the second inner ring raceway 35 of the inner ring 37, with their tails 53 facing outward, while being rotatably held by the cage 51.

[0020] On the outboard side of the ball bearing portion 40, a seal member 12 is arranged between the axially outer end of the outer ring 20 and the axially middle part of the hub ring 31. Also, on the inboard side of the tapered roller bearing portion 50, a seal member 13 is arranged between the axially inner end of the outer ring 20 and the axially inner end of the inner ring 37. This closes both axial sides of the internal space 16 in which the multiple balls 42 and tapered rollers 52 are provided.

[0021] FIG. 2 is an explanatory diagram showing a method of using a dedicated measuring jig 60 to measure the axial gap S between the step surface 34a of the small diameter step portion 34 of the hub wheel 31 when the hub wheel 31, outer ring 20 and multiple balls 42 are assembled and the outboard side end face 61 of the measuring jig 60.

[0022] 2, the measuring jig 60 is formed in a generally cylindrical shape with an inner circumferential surface that fits snugly around the small diameter step 34 of the hub ring 31. That is, the measuring jig 60 is fitted onto the outer circumferential surface of the small diameter step 34 of the hub ring 31 and includes an inner ring equivalent portion 63 having a shape similar to that of the inner ring 37, and a tapered roller equivalent portion 64 that is an abutment portion that abuts against the second outer ring raceway 23 of the outer ring 20. The tapered roller equivalent portion 64 is made up of at least three protruding portions that protrude from the inner ring equivalent portion 63 to the outer diameter side, and the three protruding portions in this embodiment are formed circumferentially spaced apart at intervals of, for example, 120°.

[0023] The inner ring equivalent part 63 has a flow passage 65 penetrating therethrough in the axial direction, and an outlet 65a is formed in the outboard end face 61 of the inner ring equivalent part 63, which opens toward the step surface 34a of the small diameter step part 34 and discharges compressed air into the axial gap between the hub wheel 31 and the measuring jig 60. The flow passage 65 is connected to an externally arranged compressed air supply source 71 via a pressure gauge 72, a flow meter (not shown), and a throttle 73. Incidentally, a sliding bearing such as a bush may be fitted onto the inner peripheral surface of the portion equivalent to the inner ring 63 .

[0024] An O-ring groove 66 into which an O-ring 14 is fitted is formed on the inner peripheral surface of the inner ring equivalent portion 63. The O-ring 14 seals the gap between the small diameter step portion 34 of the hub wheel 31 and the through hole 62 of the measurement jig 60, thereby preventing leakage of compressed air, which will be described later, from the gap.

[0025] As shown in Figure 2, when the hub ring 31, outer ring 20 and multiple balls 42 are assembled, the measuring jig 60 is fitted into the small diameter step portion 34 of the hub ring 31, and the three convex portions which are the tapered roller equivalent portions 64 are abutted against the outer ring raceway 23 of the outer ring 20, and lightly pushed towards the outboard side (to the left in the figure) to eliminate axial play of the ball bearing portion 40 and axial play between the outer ring raceway 23 and the tapered roller equivalent portions 64.

[0026] Then, compressed air at a constant pressure supplied from compressed air supply source 71 is discharged from outlet 65a into axial gap S between step surface 34a of small diameter step portion 34 and outboard end face 61. The axial gap S between outboard end face 61 (corresponding to outboard end face 38 of inner ring 37 in FIG. 1) of measuring jig 60 and step surface 34a of small diameter step portion 34 is measured from the back pressure and flow rate of the compressed air at this time. Note that the back pressure and flow rate of the supplied compressed air are proportional to the size of the axial gap S, so the axial gap S can be easily measured by measuring the back pressure and flow rate of the compressed air.

[0027] In addition, the O-ring 14 provided on the inner surface of the through hole 62 seals the gap between the small diameter step 34 of the hub wheel 31 and the through hole 62 of the measurement jig 60, preventing compressed air from leaking from the gap. This eliminates the effects of compressed air back pressure and flow rate on gap measurement, improving measurement accuracy.

[0028] In addition, the measurement of the axial clearance S is performed by abutting the three convex portions, which are the tapered roller equivalent portions 64, against the outer ring raceway 23 instead of the tapered rollers 52, so that no running-in rotation is required to stabilize the position of the tapered rollers 52, improving work efficiency.

[0029] The axial clearance S is measured by measuring the size of the axial clearance S using the above-mentioned measuring method.

[0030] Next, based on the axial clearance S measured by the above-mentioned measuring method, a cone 55 that will provide the desired negative clearance is selected from a plurality of previously prepared cones, or the outboard end face 38 of the inner ring 37, which has been provided with a processing allowance in advance so as to provide the desired negative clearance, is machined or pressed (a difference width is cut), and the outboard end face 38 of the inner ring 37 is abutted against the step surface 34a of the small diameter step 34, and fitted and fixed to the small diameter step 34. In this way, the negative clearance between the hub wheel 31 (step surface 34a of the small diameter step 34) and the inner ring 37 (outboard end face 38) can be strictly controlled, and a hub unit bearing 10 having the desired negative clearance can be manufactured.

[0031] Next, a method for selecting the cone 55 corresponding to the measured axial clearance S will be described with reference to FIG.

[0032] As shown in Figure 3, the master cup 75 has an outer ring raceway equivalent surface 76 that has the same shape as the second outer ring raceway 23 of the tapered roller bearing portion 50, and a reference surface 77 whose positional relationship (dimension) with the outboard end face 61 of the measuring jig 60 is known, and is formed in an approximately cup shape into which the cone 55 can be inserted.

[0033] For example, when the tapered roller equivalent portion 64 of the measuring jig 60 is abutted against the outer ring raceway equivalent surface 76 of the master cup 75 and the measuring jig 60 and master cup 75 are combined, a distance is given between the reference surface 77 of the master cup 75 and the outboard end face 61 of the measuring jig 60.

[0034] Then, the inner ring width dimension C1 of the cone 55 to be assembled as a product is measured with a dial gauge 78 (see Figure 3(a)), and the tapered roller 52 is abutted against the outer ring raceway equivalent surface 76 of the master cup 75, and the distance C2 between the reference surface 77 and the inboard end face 39 of the inner ring 37 is measured with a dial gauge 78a (see Figure 3(b)).

[0035] Therefore, based on the measured axial clearance S between the step surface 34a of the small diameter step portion 34 and the outboard end face 61 of the measuring jig 60, a suitable cone 55 is selected from a number of known cones 55 and press-fitted into the small diameter step portion 34 so that the relationship between the inner ring width dimension C1, the distance C2 between the reference surface 77 and the inboard end face 39 of the inner ring 37, and the distance between the reference surface 77 and the outboard end face 61 of the measuring jig 60 provides the desired negative clearance.

[0036] When the cone 55 (inner ring 37) is press-fitted into the small diameter step portion 34, there is a risk that the axial gap S will change due to the press-fit. However, by measuring the inner diameter of the inner ring 37 and the outer diameter of the small diameter step portion 34, the amount of change in the axial gap S due to the press-fit can be calculated and corrected when selecting the cone 55. Similarly, when machining the outboard end face 38 of the inner ring 37 to correspond to the axial gap S, the change in the axial gap S due to press fitting can be taken into account as a correction amount.

[0037] As described above, the manufacturing method of a hub unit bearing of the present embodiment makes it possible to measure the size of the axial gap with high accuracy, and also makes it possible to strictly control the size of the negative gap and manufacture a hub unit bearing having the desired negative gap.

[0038] (First Modification of the First Embodiment) As shown in Fig. 4, measuring jig 60A of this modified example does not have tapered roller equivalent parts 64 (see Fig. 2), which are three protrusions, but instead has a plurality of tapered rollers 52 and a cage 51. And measuring jig 60A measures axial clearance S by bringing the plurality of tapered rollers 52 into contact with second outer ring raceway 23 of tapered roller bearing part 50.

[0039] Although measurement of the axial gap S using the measuring jig 60A of this modified example requires relative rotation of the measuring jig 60A and the outer ring 20 to align the tapered rollers 52 to the alignment position of the outer ring raceway 23, if the measurement is performed after applying the target preload, it is possible to prevent changes in the alignment position of the tapered rollers 52 due to the preload value, and it becomes possible to more reliably select the cone 55 or to machine the outboard end face 38 of the inner ring 37.

[0040] (Second Modification of the First Embodiment) As shown in FIG. 5, the measuring jig 60B of this modified example differs from the measuring jig 60A (see FIG. 4) of the first modified example of the first embodiment in that the compressed air outlet 65b of the measuring jig 60B has an annular groove 67 that opens toward the step surface 34a of the small diameter step portion 34.

[0041] By providing an annular groove 67 in the outlet 65b, the axial gap S between the outboard end face 61 of the measuring jig 60B and the step surface 34a of the hub wheel 31 can be measured on an average basis, enabling more reliable selection of the cone 55 or machining of the outboard end face 38 of the inner wheel 37.

[0042] The above-mentioned method of measuring the averaged axial gap S by providing the annular groove 67 in the outlet 65b can also be applied to the measuring jig 60 (see FIG. 2) of the first embodiment.

[0043] Second embodiment As shown in FIG. 6, the hybrid hub unit bearing 10A of this embodiment differs from that of the first embodiment in that a ball bearing portion 40 having balls 42 as rolling elements is provided on the inboard side, and a tapered roller bearing portion 50 having tapered rollers 52 as rolling elements is provided on the outboard side.

[0044] For this reason, on the inner peripheral surface of the outer ring 20, the first outer ring raceway 22 on the outboard side is formed into a conical surface, and the second outer ring raceway 23 on the inboard side is formed into an arc-shaped cross section. Also, the first inner ring raceway 33 formed on the outer peripheral surface of the hub ring 31 is formed into a conical surface, and the second inner ring raceway 35 formed on the outer peripheral surface of the inner ring 37 is formed into an arc-shaped cross section.

[0045] 7, a measuring jig 80 used in manufacturing the hybrid hub unit bearing 10 of this embodiment includes a hub ring equivalent portion 81 having a small diameter step equivalent portion 82 into which the inner peripheral surface of the inner ring 37 fits and having a shape similar to that of the hub ring 31, and a tapered roller equivalent portion 83 which is an abutment portion that abuts against the second outer ring raceway 23 of the outer ring 20. The tapered roller equivalent portion 83 is made up of at least three protrusions that protrude outward from the hub ring equivalent portion 81, and the three protrusions in this embodiment are formed circumferentially spaced apart at intervals of, for example, 120°.

[0046] Then, using a dedicated measuring jig 80, with the inner ring 37, outer ring 20 and multiple balls 42 assembled, the small diameter step equivalent portion 82 is fitted onto the inner surface of the inner ring 37, and the step surface 82a of the small diameter step equivalent portion 82 is opposed to the outboard end face 38 of the inner ring 37, and the axial clearance S is measured by measuring the flow rate and back pressure when compressed air is discharged from the outlet 85a through the flow path 85, as described in the first embodiment.

[0047] In addition, in a double row bearing, the result is the same whether the negative clearance is adjusted on the ball bearing 40 side or on the tapered roller bearing portion 50 side. Furthermore, the hub ring 31 is manufactured by integral grinding using a forming grindstone from the seal sliding surface on the outboard side to the small diameter step portion 34 on the inboard side, and all the hub rings 31 have the same dimensions, so it is difficult to select a hub ring 31 to fit with the inner ring 37. It is also difficult to machine the step surface 34a of the small diameter step portion 34. For this reason, it is preferable to adjust the negative clearance by selecting a component on the ball bearing 40 side that is easy to selectively fit in accordance with the measured axial clearance S. Specifically, the negative clearance is adjusted by selecting a gauge for the balls 42 or by machining the outboard side end face 38 of the inner ring (differential width cut).

[0048] When selecting components for the ball bearing 40, a master cup 75A shown in Figure 8 is used in which the outer ring raceway equivalent surface 76 of the master cup 75 described in Figure 3 has been modified to have an arc-shaped cross section, and a suitable assembly is selected from a number of known assemblies of inner ring 37, balls 42, and retainer 41 for the ball bearing 40 so as to provide the desired negative clearance, and is press-fitted into the small diameter step portion 34 in the same manner as in the first embodiment.

[0049] (First modified example of the second embodiment) As shown in Fig. 9, measuring jig 80A of this modified example does not have tapered roller equivalent parts 83 (see Fig. 7) which are three convex parts, but instead has a plurality of tapered rollers 52 and a cage 51. Then, measuring jig 80A is brought into contact with first outer ring raceway 22 on the tapered roller bearing part 50 side via the plurality of tapered rollers 52 to measure axial clearance S.

[0050] Although measurement of the axial gap S using the measuring jig 80A of this modified example requires relative rotation of the measuring jig 80A and the outer ring 20 to align the tapered rollers 52 to the alignment position of the outer ring raceway 22, if the measurement is performed after applying the target preload, the change in the alignment position of the tapered rollers 52 due to the preload value can be canceled, making it possible to more reliably select the assembly of the inner ring 37, balls 42 and cage 41, or to machine the outboard end face 38 of the inner ring 37.

[0051] (Second modified example of the second embodiment) As shown in FIG. 10, the measurement jig 80B of this modified example differs from the measurement jig 80A (see FIG. 9) of the first modified example of the second embodiment in that the compressed air outlet 85b of the measurement jig 80B has an annular groove 86 that opens toward the outboard end face 38 of the inner ring 37.

[0052] By providing an annular groove 86 in the outlet 85b, the axial gap S between the step surface equivalent portion 82a of the small diameter step equivalent portion 82 of the measuring jig 80B and the outboard end face 38 of the inner ring 37 can be measured on an average basis, making it possible to more reliably select the assembly of the inner ring 37, balls 42 and cage 41, or to machine the outboard end face 38 of the inner ring 37.

[0053] The above-mentioned method of measuring the averaged axial gap S by providing the annular groove 86 in the blowout port 85b can also be applied to the measuring jig 80 of the second embodiment (see FIG. 7).

[0054] As described above, according to the manufacturing method of the hub unit bearing of the present embodiment, it is possible to measure the size of the negative gap with high accuracy, and also to manufacture a hub unit bearing having the desired negative gap by strictly controlling the size of the negative gap.

[0055] The present invention is not limited to the above-described embodiment, and can be modified, improved, etc. as appropriate.

[0056] As described above, the present specification discloses the following: (1) an outer ring having first and second outer ring raceways on an inner circumferential surface thereof; a hub having at least a flange for supporting and fixing a wheel on its outer peripheral surface, a first inner ring raceway facing the first outer ring raceway, and a small diameter step, and an inner ring that is fitted onto the outer peripheral surface of the small diameter step with its outboard end face abutting against a step surface of the small diameter step and fixed to the hub, and that has a second inner ring raceway facing the second outer ring raceway on its outer peripheral surface; a plurality of rolling elements provided in double rows between the first and second outer ring raceways and the first and second inner ring raceways so as to be rollable; A manufacturing method of a hub unit bearing comprising: The hub unit bearing includes a ball bearing portion in which the rolling elements constituting one of the double rows are balls, and a tapered roller bearing portion in which the rolling elements constituting the other row are tapered rollers, a step of assembling a measuring jig corresponding to the other of the hub ring and the inner ring, and the tapered rollers to the hub ring and one of the inner ring, in a state in which the hub ring and one of the inner ring, the outer ring, and the balls constituting an inner ring raceway on the ball bearing portion side are assembled, and measuring an axial clearance between the one of the hub ring and the inner ring and the measuring jig; a step of fitting and fixing the inner ring to the small diameter step of the hub ring using an assembly including the inner ring, the rolling elements that roll on the second outer ring raceway and the second inner ring raceway, and a retainer that holds the rolling elements, so that a desired negative clearance is obtained between the small diameter step of the hub ring and the inner ring based on the measured axial clearance; A method for manufacturing a hub unit bearing comprising: According to this configuration, it is possible to measure the size of the axial gap with high accuracy, and the size of the negative gap can be strictly controlled.

[0057] (2) The step of fitting and fixing includes selectively selecting the assembly or machining an outboard end face of the inner ring of the assembly so as to obtain the desired negative clearance based on the measured axial clearance, and then fitting and fixing the inner ring of the assembly to the small diameter step portion of the hub wheel. A method for manufacturing the hub unit bearing described in (1). With this configuration, the size of the negative gap can be strictly controlled by selecting an assembly consisting of the inner ring, rolling elements and cage, or by machining the outboard end face of the inner ring, and fitting and fixing the inner ring to the small diameter step portion so as to achieve the desired negative gap based on the measured axial clearance.

[0058] (3) The measuring jig includes an inner ring equivalent portion that fits into an outer peripheral surface of the small diameter step portion of the hub ring, and an abutment portion that abuts against an outer ring raceway on the tapered roller bearing portion side of the outer ring, the inner ring equivalent portion is provided with a flow path having an outlet that discharges compressed air into the axial gap between the hub wheel and the measuring jig, and the axial gap is measured based on the flow rate or back pressure of the compressed air flowing out from the outlet. A method for manufacturing the hub unit bearing described in (1). According to this configuration, the axial clearance can be measured with high accuracy based on the flow rate or back pressure of the compressed air flowing out from the outlet.

[0059] (4) The measuring jig includes a hub ring equivalent portion having a small diameter step equivalent portion into which the inner peripheral surface of the inner ring is fitted, and an abutment portion that abuts against an outer ring raceway on the tapered roller bearing portion side of the outer ring, the hub wheel equivalent portion is provided with a flow path having an outlet that discharges compressed air into the axial gap between the inner ring and the measuring jig, and the axial gap is measured based on the flow rate or back pressure of the compressed air flowing out from the outlet. A method for manufacturing the hub unit bearing described in (1). According to this configuration, the axial clearance can be measured with high accuracy based on the flow rate or back pressure of the compressed air flowing out from the outlet. [Explanation of symbols]

[0060] 10 Hub unit bearing 20 Outer ring 22 First outer raceway 23 Second outer raceway 30 Hub 31 Hub wheel 32 Rotating flange 33 First inner raceway 34 Small diameter stepped section 34a Step surface 35 Second inner raceway 37 Inner Circle 38 Outboard end face 39 Inboard end face 40 Ball bearing section 42 Ball (rolling element) 50 Tapered roller bearing 52 Tapered roller (rolling element) 55 Cone (assembly) 60, 80 Measuring fixture 64 Tapered roller equivalent part (convex part) 65a Air outlet 66 Annular groove 70 Assembly S Axial clearance

Claims

1. an outer ring having first and second outer ring raceways on an inner circumferential surface thereof; a hub having at least a flange for supporting and fixing a wheel on its outer peripheral surface, a first inner ring raceway facing the first outer ring raceway, and a small diameter step, and an inner ring that is fitted onto the outer peripheral surface of the small diameter step with its outboard end face abutting against a step surface of the small diameter step and fixed to the hub, and that has a second inner ring raceway on its outer peripheral surface facing the second outer ring raceway; a plurality of rolling elements provided in double rows between the first and second outer ring raceways and the first and second inner ring raceways so as to be rollable; A manufacturing method of a hub unit bearing comprising: The hub unit bearing includes a ball bearing portion in which the rolling elements constituting one of the double rows are balls, and a tapered roller bearing portion in which the rolling elements constituting the other row are tapered rollers, a step of assembling a measuring jig corresponding to the other of the hub ring and the inner ring, and the tapered rollers to the hub ring and one of the inner ring, in a state in which the hub ring and one of the inner ring, the outer ring, and the balls constituting an inner ring raceway on the ball bearing portion side are assembled, and measuring an axial clearance between the one of the hub ring and the inner ring and the measuring jig; a step of fitting and fixing the inner ring to the small diameter step of the hub ring using an assembly including the inner ring, the rolling elements that roll on the second outer ring raceway and the second inner ring raceway, and a retainer that holds the rolling elements, so that a desired negative clearance is obtained between the small diameter step of the hub ring and the inner ring based on the measured axial clearance; A method for manufacturing a hub unit bearing comprising:

2. the step of fitting and fixing includes selectively selecting the assembly based on the measured axial clearance so as to obtain the desired negative clearance, or machining an outboard end face of the inner ring of the assembly, and then fitting and fixing the inner ring of the assembly to the small diameter step portion of the hub wheel. A method for manufacturing a hub unit bearing according to claim 1.

3. the measuring jig includes an inner ring equivalent portion that fits into an outer peripheral surface of a small diameter step portion of the hub wheel, and an abutment portion that abuts against an outer ring raceway on a side of the tapered roller bearing portion of the outer ring, the inner ring equivalent portion is provided with a flow path having an outlet that discharges compressed air into the axial gap between the hub wheel and the measuring jig, and the axial gap is measured based on the flow rate or back pressure of the compressed air flowing out from the outlet. A method for manufacturing a hub unit bearing according to claim 1.

4. the measuring jig comprises a hub ring equivalent portion having a small diameter step equivalent portion into which an inner peripheral surface of the inner ring is fitted, and an abutment portion that abuts against an outer ring raceway on a side of the tapered roller bearing portion of the outer ring, the hub wheel equivalent portion is provided with a flow path having an outlet that discharges compressed air into the axial gap between the inner ring and the measuring jig, and the axial gap is measured based on the flow rate or back pressure of the compressed air flowing out from the outlet. A method for manufacturing a hub unit bearing according to claim 1.

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