JP7559751B2 - Method for measuring axial clearance of double row rolling bearing and method for manufacturing double row rolling bearing - Google Patents

Description

The present disclosure relates to a method for measuring an axial clearance of a double row rolling bearing and a method for manufacturing a double row rolling bearing.

As a device for supporting the wheels of an automobile on a suspension system, for example, a hub unit 1 made of a double row rolling bearing as shown in FIG. 11 is used. The flange 2a of the outer ring 2 is attached to the suspension system (not shown) of the automobile to constitute the fixed side member of the bearing. A spindle portion 3a of a hub axle 3 constituting the movable side member of the bearing is inserted into the radially inner side of the outer ring 2. The spindle portion 3a is rotatably held inside the outer ring 2 via a plurality of rolling elements 4e forming an annular row on the vehicle outer side (left side in FIG. 11) and a plurality of rolling elements 4f forming an annular row on the vehicle inner side (right side in FIG. 11). The portion of the spindle portion 3a facing the rolling elements 4f on the vehicle inner side is formed as a cylindrical portion 3b having a smaller diameter than the other portions. An inner ring 5 is fitted to the outer peripheral surface of the cylindrical portion 3b and fixed to the cylindrical portion 3b.

The rolling element 4e on the vehicle outer side is held by a cage 6e so as to be freely rollable between a first outer ring raceway 2e formed on the inner peripheral surface of the outer ring 2 and a first inner ring raceway 3e formed on the outer peripheral surface of the spindle portion 3a. The rolling element 4f on the vehicle inner side is held by a cage 6f so as to be freely rollable between a second outer ring raceway 2f formed on the inner peripheral surface of the outer ring 2 and a second inner ring raceway 5f formed on the outer peripheral surface of the inner ring 5. A flange 3d is formed on the outer periphery of the end of the hub axle 3 on the vehicle outer side, and a plurality of bolts 7 are fixed to the periphery of this flange 3d. The wheel (not shown) of the wheel is fixed to the hub axle 3 by the bolt 7 and a nut (not shown) and rotates together with the hub axle 3.
The above-mentioned hub unit 1 is disclosed in Japanese Patent Application Laid-Open No. 2003-233999 and Japanese Patent Application Laid-Open No. 2003-233999.

Japanese Patent Application Publication No. 10-185717 JP 2000-9562 A

The present disclosure relates to a method for measuring an axial clearance of a double row rolling bearing including a hub shaft, an inner ring fitted onto an outer periphery of one axial end of the hub shaft, an outer ring provided coaxially with the hub shaft and radially outward of the hub shaft and the inner ring, and rolling elements provided in two rows along the axial direction in an annular space between the hub shaft and the inner ring, and the outer ring,
The inner ring is provisionally press-fitted onto the hub shaft with the outer ring attached via the rolling elements in a position in which the axis of the hub shaft faces up and down;
With the inner ring provisionally press-fitted onto the hub axle, the outer ring is raised upward to bring the rolling elements on the inner ring side of the two rows of rolling elements into contact with a raceway surface for the rolling elements on the inner ring side;
a distance R1 between an axial end face of the outer ring and an axial end face of the inner ring is measured with the rolling elements and the raceway surface in contact with each other;
Return the outer ring that was lifted upward to its original position,
The inner ring is press-fitted onto the hub shaft until the inner ring and the hub shaft butt against each other;
With the inner ring fully press-fitted onto the hub axle, a distance R2 between an end face of the outer ring in the axial direction and an end face of the inner ring in the axial direction is measured;
The axial clearance is calculated from the difference between the distance R2 and the distance R1.

The present disclosure provides a method for assembling a double row rolling bearing including a hub axle, an inner ring fitted onto the outer periphery of one axial end of the hub axle, an outer ring disposed coaxially with the hub axle and radially outward of the hub axle and the inner ring, and rolling elements disposed in two rows along the axial direction in an annular space between the hub axle and the inner ring, and the outer ring, comprising:
a manufacturing method for a hub shaft having the rolling elements and the outer ring assembled thereto, the method comprising: press-fitting the inner ring onto an outer periphery of one axial end of the hub shaft,
a temporary press-fitting step of temporarily press-fitting the inner ring onto the hub axle with the outer ring attached via the rolling elements in a position in which the axis of the hub axle faces up and down;
a first measuring step of lifting the outer ring upward with the inner ring provisionally press-fitted onto the hub axle by the provisional press-fit step, bringing the rolling elements on the inner ring side of the two rows of rolling elements into contact with raceway surfaces for the rolling elements on the inner ring side, measuring a distance R1 between an end face in the axial direction of the outer ring and an end face in the axial direction of the inner ring while the rolling elements and the raceway surfaces are in contact, and returning the outer ring that was lifted upward to its original position;
a final press-fitting step of final press-fitting the inner ring onto the hub shaft until the inner ring and the hub shaft butt against each other;
and a second measurement process for measuring a distance R2 between the axial end face of the outer ring and the axial end face of the inner ring while the inner ring is fully press-fitted onto the hub shaft by the full press-fit process, and determining the axial clearance from the difference between distance R2 and distance R1.

1A to 1C are cross-sectional explanatory views showing the procedure of one embodiment of a gap measurement method. 1A to 1C are cross-sectional explanatory views showing the procedure of one embodiment of a gap measurement method. 1A to 1C are cross-sectional explanatory views showing the procedure of one embodiment of a gap measurement method. 1A to 1C are cross-sectional explanatory views showing the procedure of one embodiment of a gap measurement method. 5 is a cross-sectional explanatory view showing the procedure of a modified example of the gap measurement method according to the embodiment shown in FIGS. 1 to 4. 5 is a cross-sectional explanatory view showing the procedure of a modified example of the gap measurement method according to the embodiment shown in FIGS. 1 to 4. 1 is a flowchart showing the steps of an embodiment of a manufacturing method. 1 is a flowchart showing the steps of an embodiment of a manufacturing method. 1A to 1C are cross-sectional explanatory views showing a procedure of one embodiment of a manufacturing method. 1A to 1C are cross-sectional explanatory views showing a procedure of one embodiment of a manufacturing method. 1 is a cross-sectional explanatory view showing the structure of an example of a double row rolling bearing to which the gap measurement method can be applied. FIG. FIG. 13 is a cross-sectional explanatory diagram showing the procedure of gap measurement method A. FIG. 13 is a cross-sectional explanatory diagram showing the procedure of gap measurement method A. FIG. 13 is a cross-sectional explanatory diagram showing the procedure of gap measurement method A. FIG. 13 is a cross-sectional explanatory diagram showing the procedure of gap measurement method A. FIG. 13 is a cross-sectional explanatory diagram showing the procedure of gap measurement method B. FIG. 13 is a cross-sectional explanatory diagram showing the procedure of gap measurement method B. FIG. 13 is a cross-sectional explanatory diagram showing the procedure of gap measurement method B. FIG. 13 is a cross-sectional explanatory diagram showing the procedure of gap measurement method B.

<Problems to be Solved by the Present Disclosure>
In the hub unit 1 configured as described above, the dimensions of each component are adjusted so that an appropriate preload is applied between the rolling element 4e and its first outer ring raceway 2e and first inner ring raceway 3e, and between the rolling element 4f and its second outer ring raceway 2f and second inner ring raceway 5f. If the preload is smaller than the appropriate value, the bearing rigidity will be insufficient, and if it is significantly smaller, there is a risk that the hub axle 3 will vibrate and generate noise. Conversely, if the preload is larger than the appropriate value, there is a risk that the power performance and fuel efficiency of the automobile will decrease due to increased rotational resistance. Therefore, in order to prevent such problems from occurring, it is necessary to check whether the desired appropriate preload is applied in the bearing manufacturing process.

Therefore, it has been proposed to take advantage of the fact that there is a certain relationship between the preload applied to a bearing and the axial clearance, and to measure the axial clearance of the bearing and confirm whether or not an appropriate preload has been applied based on this axial clearance.

Two types of gap measurement methods have been proposed so far as methods for measuring the axial clearance of double-row rolling bearings: gap measurement method A (see, for example, Patent Document 1) and gap measurement method B (see, for example, Patent Document 2).

(1) Gap measurement method A
Gap measurement method A includes a process of provisionally press-fitting the inner ring onto the hub axle, a process of measuring the positive gap in the provisionally press-fit state, and a process of fully press-fitting the inner ring onto the hub axle and measuring the amount of movement of the inner ring.
First, as shown in FIG. 12, the outer ring 2 and rolling elements 4e, 4f are assembled to the hub axle 3, which is placed on the base 10 so that its axis faces the up-down direction and the flange 3d is located downward. The inner ring 5 is press-fitted into the outer periphery of the cylindrical portion 3b of the hub axle 3 using a jig 30 arranged above the hub unit 1. The press-fitting at this time is a press-fitting (temporary press-fitting) to the extent that the rolling elements 4e, 4f do not come into contact with the corresponding raceways (to the extent that the rolling elements 4e, 4f are not preloaded). In FIG. 12 and the figures referred to in the following description, a double row rolling bearing (hub unit) having the configuration shown in FIG. 11 is used to explain the method of measuring the axial clearance. Therefore, in FIG. 12 and the figures referred to in the following description, the same reference symbols are used for the same members or elements as those of the double row rolling bearing shown in FIG. 11, and their explanations are omitted for simplicity.

Next, as shown in FIG. 13, the hub unit 1 with the inner ring 5 provisionally press-fitted onto the hub axle 3 is transported onto a base 11 that can move up and down. After that, the clamp 12 disposed below the flange 2a of the outer ring 2 is raised to lift the outer ring 2 (see the white arrow in FIG. 13). At this time, the clearance between the rolling element 4f on the vehicle inner side and the second outer ring raceway 2f and the second inner ring raceway 5f is zero (zero touch). In this state, the positional relationship between the outer ring 2 and the inner ring 5 is measured. Specifically, the distance C1 between the end face 2a1 on the vehicle inner side of the flange 2a of the outer ring 2 and the end face 5a on the vehicle inner side of the inner ring 5 is measured. This measurement is performed using an instrument such as a digital indicator. A cylindrical jig 31 for measuring the position of the outer ring 2 is disposed radially outside the jig 30.

Next, as shown in Fig. 14, with the clamp 12 raised, the base 11 is moved upward to raise the hub axle 3 upward (see the hollow arrow in Fig. 14). At this time, the clearance between the rolling element 4e on the vehicle outer side and the first outer ring raceway 2e and the first inner ring raceway 3e is zero (zero touch). In this state, the positional relationship between the outer ring 2 and the inner ring 5 is measured. Specifically, the distance C2 between the end face 2a1 on the vehicle inner side of the flange 2a of the outer ring 2 and the end face 5a on the vehicle inner side of the inner ring 5 is measured. The amount of backlash (positive clearance) in the axial direction of the outer ring 2 is obtained by measuring the distances C1 and C2 and calculating the difference between them (C2-C1).

Next, the hub unit 1 is transported onto a separate pedestal 13 different from the pedestal 11. Thereafter, as shown in Fig. 15, the inner ring 5 is press-fitted (main press-fit) into the hub axle 3 using a jig 32 disposed above the hub unit 1 until the inner ring 5 and the hub axle 3 butt against each other, and in this state the amount of movement of the inner ring 5 relative to the hub axle 3 is measured. Specifically, the amount of movement M is measured, which is the difference between the distance m1 between the vehicle inner end face 3b1 of the hub axle 3 and the vehicle inner end face 5a of the inner ring 5 (see Fig. 14) at the time of temporary press-fitting and the distance m2 between the vehicle inner end face 3b1 of the hub axle 3 and the vehicle inner end face 5a of the inner ring 5 after the main press-fitting.
The axial clearance is calculated as (C2-C1)-M.

(2) Gap measurement method B
In clearance measurement method B, a negative clearance value is calculated from the amount of sinking of the outer ring relative to the hub axle.
First, as shown in Figure 16, the outer ring 2 and rolling elements 4e, 4f are assembled to the hub axle 3, which is placed on the base 14 with its axis facing up and down and the flange 3d positioned downward. The inner ring 5 is provisionally press-fitted onto the outer periphery of the cylindrical portion 3b of the hub axle 3 using a jig 33 disposed above the hub unit 1. In this state, the positional relationship between the outer ring 2 and the hub axle 3 is measured. Specifically, as shown in Figure 17, the distance S1 between the vehicle inner side end face 2b of the outer ring 2 and the vehicle inner side end face 3b1 of the cylindrical portion 3b of the hub axle 3 is measured. This measurement is also performed using an instrument such as a digital indicator, as described above.

Next, as shown in FIG. 18, the inner ring 5 is press-fitted (main press-fit) into the hub axle 3 using a jig 33 until the inner ring 5 and the hub axle 3 butt against each other. After that, the downward load applied by the jig 33 for the main press-fit is released, and the inner ring 5 is placed in a state where no load is applied. By releasing the load, the inner ring 5 is placed in a state where it is not elastically deformed. In this state, the positional relationship between the outer ring 2 and the hub axle 3 is measured. Specifically, as shown in FIG. 19, the distance S2 between the end face 2b on the vehicle inner side of the outer ring 2 and the end face 3b1 on the vehicle inner side of the cylindrical portion 3b of the hub axle 3 is measured. Note that, in some cases, the downward load applied by the jig 33 is not released as described above during the measurement.

The axial clearance is calculated by (S2-S1) x Ca, where Ca is a predetermined constant. The value of Ca is theoretically 2 because the rolling elements are arranged in two rows. However, if the size or specifications of the rolling elements differ between the vehicle inner side and the vehicle outer side, or if the rigidity differs between the vehicle inner side end and the vehicle outer side end of the outer ring 2 that constitutes the raceway surface of the rolling elements, the value of Ca may be other than 2. The value of Ca is determined arbitrarily for each double row rolling bearing specification in correlation with manual measurement.

(3) Issues with Gap Measurement Methods A and B With gap measurement method A, it is necessary to position the hub unit in three positions according to the process of provisionally pressing in the inner ring, measuring the positive gap, and then performing the final press-in. This poses the issue that the measurement device becomes larger, which increases costs and requires a large facility space.
In contrast, with gap measurement method B, measurements can be made at one position, i.e., on the same axis. However, when S1<S2, i.e., when the gap is positive, the outer ring 2 does not move, so the positive gap value cannot be measured, and all gaps are determined to be zero. For this reason, with gap measurement method B, if it is necessary to measure the positive gap value, a separate positive gap measuring device is required.
In recent years, there has been a demand to reduce the rotational torque of rolling bearings in order to improve fuel efficiency, etc. In response to this demand, it is conceivable to shift the axial clearance to the positive side. Unlike clearance measurement method A, clearance measurement method B allows measurement at one position, but as mentioned above, it is not possible to measure the positive clearance value.

Therefore, an object of the present disclosure is to provide an axial clearance measurement method for a double row rolling bearing, which is capable of measuring positive and negative clearances in a single position, and a manufacturing method for a double row rolling bearing.

<Effects of the present disclosure>
According to the present disclosure, positive and negative gaps can be measured in one position.

<Overview of the embodiment of the present disclosure>
Below, an overview of the embodiments of the present disclosure will be listed and described.

The axial clearance measurement method for a double row rolling bearing according to the present disclosure (hereinafter also simply referred to as the "gap measurement method") is as follows:
(1) A method for measuring an axial clearance of a double row rolling bearing including a hub shaft, an inner ring fitted onto an outer periphery of one axial end of the hub shaft, an outer ring provided coaxially with the hub shaft and radially outward of the hub shaft and the inner ring, and rolling elements provided in two rows along the axial direction in an annular space between the hub shaft and the inner ring, the method comprising the steps of:
The inner ring is provisionally press-fitted onto the hub shaft with the outer ring attached via the rolling elements in a position in which the axis of the hub shaft faces up and down;
With the inner ring provisionally press-fitted onto the hub axle, the outer ring is raised upward to bring the rolling elements on the inner ring side of the two rows of rolling elements into contact with a raceway surface for the rolling elements on the inner ring side;
a distance R1 between an axial end face of the outer ring and an axial end face of the inner ring is measured with the rolling elements and the raceway surface in contact with each other;
Return the outer ring that was lifted upward to its original position,
The inner ring is press-fitted onto the hub shaft until the inner ring and the hub shaft butt against each other;
With the inner ring fully press-fitted onto the hub axle, a distance R2 between an end face of the outer ring in the axial direction and an end face of the inner ring in the axial direction is measured;
The axial clearance is calculated from the difference between the distance R2 and the distance R1.

In this disclosure, "downward" refers to the direction in which gravity acts, and "upward" refers to the opposite direction to downward. When one axial direction of a double row rolling bearing faces upward and the other axial direction of the double row rolling bearing faces downward, the direction along the center line of the double row rolling bearing (bearing center line) is the "up-down direction." In this disclosure, not only is it acceptable for the bearing center line to be perfectly aligned with the vertical direction, but it is also acceptable for the bearing center line to be inclined toward the vertical direction.

In the above-mentioned clearance measurement method, the axial clearance is obtained by measuring the distances R1 and R2 between the axial end face of the outer ring and the axial end face of the inner ring when the inner ring is provisionally and fully press-fitted onto the hub axle. The provisional press-fitting, the fully press-fitting, and the measurement of the distances R1 and R2 can be performed in a state where the double row rolling bearing is disposed in the same position in the axial clearance measurement device, i.e., in one position. This allows the measurement device to be made compact, reducing equipment costs and reducing the equipment space. In addition, both the positive clearance and the negative clearance can be measured from the difference between the distances R2 and R1.

(2) In the clearance measurement method of (1) above, when the difference is a positive value, (R2-R1) is taken as the axial clearance, and when the difference is zero or a negative value, Cb is taken as a predetermined constant and the axial clearance can be taken as (R2-R1) x Cb. In this case, the positive clearance and the negative clearance can be measured based on the difference (R2-R1) between the distance R2 and the distance R1.

(3) In the clearance measurement method of (2) above, the constant Cb can be set to 2. On the premise that the clearance of the rolling element on the vehicle inner side and the clearance of the rolling element on the vehicle outer side are the same size, the axial clearance can be obtained by doubling the value of (R2-R1).

(4) The method of measuring the gap in (1) includes measuring a distance L1 between an axial end face of the outer ring and an axial end face of the hub spindle in a state in which the inner ring is temporarily press-fitted onto the hub spindle; and
measuring a distance L2 between an axial end face of the outer ring and an axial end face of the hub spindle in a state in which the inner ring is fully press-fitted onto the hub spindle,
When the difference is a positive value, (R2-R1) is defined as the axial clearance,
When the difference is zero or a negative value, the sum of (R2-R1) and (L2-L1) can be taken as the axial clearance.
In this case, it is possible to measure the deformation of the outer rolling element. When the difference is zero or a negative value, the negative clearance can be measured more accurately than when the deformation of the inner rolling element is multiplied by the constant Cb to obtain the axial clearance of the bearing.

(5) The clearance measurement method of (1) includes measuring a distance P1 between an axial end face of the inner ring and an axial end face of the hub spindle in a state in which the inner ring is temporarily press-fitted onto the hub spindle; and
measuring a distance P2 between an axial end face of the inner ring and an axial end face of the hub spindle in a state in which the inner ring is fully press-fitted onto the hub spindle,
When the difference is a positive value, (R2-R1) is defined as the axial clearance,
When the difference is zero or a negative value, the distance Q1 between the axial end face of the outer ring and the axial end face of the hub shaft at the time of temporary press-fitting can be determined based on P1 and R1, and the distance Q2 between the axial end face of the outer ring and the axial end face of the hub shaft at the time of full press-fitting can be determined based on P2 and R2, and the sum of (R2-R1) and (Q2-Q1) can be determined as the axial clearance.
In this case, it is possible to measure the deformation of the outer rolling element. When the difference is zero or a negative value, the negative clearance can be measured more accurately than when the deformation of the inner rolling element is multiplied by the constant Cb to obtain the axial clearance of the bearing.

The manufacturing method of the double row rolling bearing of the present disclosure (hereinafter also simply referred to as the "manufacturing method") is as follows:
(6) To assemble a double row rolling bearing including a hub shaft, an inner ring fitted onto the outer periphery of one axial end of the hub shaft, an outer ring provided coaxially with the hub shaft and radially outward of the hub shaft and the inner ring, and rolling elements provided in two rows along the axial direction in an annular space between the hub shaft and the inner ring,
a manufacturing method for a hub shaft having the rolling elements and the outer ring assembled thereto, the method comprising: press-fitting the inner ring onto an outer periphery of one axial end of the hub shaft,
a temporary press-fitting step of temporarily press-fitting the inner ring onto the hub axle with the outer ring attached via the rolling elements in a position in which the axis of the hub axle faces up and down;
a first measuring step of lifting the outer ring upward with the inner ring provisionally press-fitted onto the hub axle by the provisional press-fit step, bringing the rolling elements on the inner ring side of the two rows of rolling elements into contact with raceway surfaces for the rolling elements on the inner ring side, measuring a distance R1 between an end face in the axial direction of the outer ring and an end face in the axial direction of the inner ring while the rolling elements and the raceway surfaces are in contact, and returning the outer ring that was lifted upward to its original position;
a final press-fitting step of final press-fitting the inner ring onto the hub shaft until the inner ring and the hub shaft butt against each other;
and a second measurement process for measuring a distance R2 between the axial end face of the outer ring and the axial end face of the inner ring while the inner ring is fully press-fitted onto the hub shaft by the full press-fit process, and determining the axial clearance from the difference between distance R2 and distance R1.

In the manufacturing method, the axial clearance is obtained by measuring the distances R1 and R2 between the axial end face of the outer ring and the axial end face of the inner ring when the inner ring is provisionally and fully press-fitted onto the hub axle. The provisional press-fitting step, the first measuring step, the full press-fitting step, and the second measuring step according to the present disclosure can be performed in a state where the double row rolling bearing is placed in the same position in the manufacturing equipment for the double row rolling bearing, i.e., in one position. This allows the manufacturing equipment to be made smaller, reducing equipment costs and reducing the equipment space. In addition, both the positive clearance and the negative clearance can be measured from the difference between the distance R2 and the distance R1.

(7) In the manufacturing method of (6), the preliminary press-fitting step, the first measurement step, the main press-fitting step, and the second measurement step are preferably performed with the hub axle mounted on the same pedestal. In this case, by mounting the hub axle on the pedestal, the positive gap and the negative gap can be measured in one position.

(8) The manufacturing method of (6) or (7) may further include a determination step of determining whether the axial clearance is an appropriate value based on a comparison between the axial clearance determined in the second measurement step and a reference value, and a confirmation step that is executed after the determination step determines that the axial clearance is not an appropriate value and includes at least one of a step of inspecting the double row rolling bearing and a step of discarding the double row rolling bearing. If it is determined that the axial clearance is not an appropriate value, the manufactured double row rolling bearing can be inspected or discarded, and the quality of the double row rolling bearing can be improved.

<Details of the embodiment of the present disclosure>
Hereinafter, an embodiment of the present disclosure will be described.
[Gap measurement method]
1 to 4 are cross-sectional explanatory views showing the procedure of a clearance measurement method according to one embodiment of the present invention. In this embodiment, the axial clearance is measured in a double row rolling bearing of the type shown in Fig. 11. That is, the axial clearance is measured in a double row rolling bearing including a hub axle 3, an inner ring 5 fitted to the outer periphery of one axial end of the hub axle 3, an outer ring 2 provided coaxially with the hub axle 3 on the radial outside of the hub axle 3 and the inner ring 5, and rolling elements 4e, 4f provided in two rows along the axial direction in the annular space between the hub axle 3, the inner ring 5, and the outer ring 2.

In this embodiment, in order to determine whether the preload applied to the bearing is appropriate, the preload gap is measured by utilizing the fact that there is a certain relationship between the preload and the preload gap. Here, the preload gap refers to a negative "gap" (negative gap) that is formed by the axial elastic deformation of the rolling elements of the bearing and each of the related members when the bearing changes from a state in which no preload is applied to a state in which a preload is applied. The state in which no preload is applied is called a positive gap state.

A hub unit 1 made up of a double row rolling bearing shown in FIG. 11 will be described.
The flange 2a of the outer ring 2 is attached to the suspension system (not shown) of the automobile, and constitutes the fixed member of the bearing. A spindle portion 3a of a hub axle 3, which constitutes the movable member of the bearing, is inserted into the radially inner side of the outer ring 2. The spindle portion 3a is rotatably held inside the outer ring 2 via a plurality of rolling elements 4e forming an annular row on the vehicle outer side (left side in FIG. 11) and a plurality of rolling elements 4f forming an annular row on the vehicle inner side (right side in FIG. 11). The portion of the spindle portion 3a facing the rolling elements 4f on the vehicle inner side is formed as a cylindrical portion 3b having a smaller diameter than the other portions. An inner ring 5 is fitted onto the outer peripheral surface of the cylindrical portion 3b and fixed to the cylindrical portion 3b.

The rolling element 4e on the vehicle outer side is held by a cage 6e so as to be able to roll freely between a first outer ring raceway 2e formed on the inner peripheral surface of the outer ring 2 and a first inner ring raceway 3e formed on the outer peripheral surface of the spindle portion 3a. The rolling element 4e is in angular contact with the outer ring raceway 2e and the inner ring raceway 3e.
The rolling element 4f on the vehicle inner side is held by a cage 6f so as to be able to roll freely between a second outer ring raceway 2f formed on the inner peripheral surface of the outer ring 2 and a second inner ring raceway 5f formed on the outer peripheral surface of the inner ring 5. The rolling element 4f is in angular contact with the outer ring raceway 2f and the inner ring raceway 5f.
By fixing the inner ring 5 to the cylindrical portion 3b, the rolling elements 4e, 4f and the outer ring 2 are in an assembled state and cannot fall off the hub axle 3.

A flange 3d is formed on the outer periphery of the end of the hub axle 3 on the vehicle outer side, and a plurality of bolts 7 are fixed to the periphery of this flange 3d. A wheel (not shown) of a vehicle wheel is fixed to the hub axle 3 by the bolts 7 and nuts (not shown) and rotates together with the hub axle 3. A seal 8 made of an elastic material is attached to the inner periphery of the end of the outer ring 2 on the vehicle outer side. The seal 8 comes into sliding contact with the rotating hub axle 3 to prevent foreign matter such as water and sand from entering the inside of the outer ring 2. Note that, depending on the hub unit, instead of press-fitting the bolts 7 into the holes 3f formed in the flange 3d, there is also a form in which a screw hole (not shown) is formed in the flange 3d, and the wheel is fixed to the hub axle 3 by the screw hole and the bolt.

The gap measurement method according to this embodiment includes a placement step S121, a temporary press-fit step S122, a first measurement step S123, a full press-fit step S124, and a second measurement step S125, which will be described later.

In the gap measurement method, a mounting step S121 is first performed. When the mounting step S121 begins, the hub axle 3 with the outer ring 2 attached is placed on the pedestal 20 with the axis of the hub axle 3 facing up and down and with the flange 3d of the hub axle 3 positioned downward. This completes the mounting step S121. Here, the temporary press-fit step S122, first measurement step S123, main press-fit step S124, and second measurement step S125, which will be described later, are performed with the hub axle 3 placed on the pedestal 20.

Next, the provisional press-fitting step S122 is performed. When the provisional press-fitting step S122 is started, as shown in FIG. 1, the inner ring 5 is shallowly press-fitted onto the outer periphery of the hub axle 3 placed on the pedestal 20 of the axial clearance measuring device so as to create a positive clearance (provisional press-fitting). The hub axle 3 is placed on the pedestal 20 so that the axis of the hub axle 3 faces the up-down direction and the flange 3d of the hub axle 3 is positioned downward. The outer ring 2 and rolling elements 4e, 4f are assembled to the hub axle 3. The inner ring 5 is press-fitted onto the outer periphery of the cylindrical portion 3b of the hub axle 3 with the outer ring 2 and rolling elements 4e, 4f assembled thereto. More specifically, the inner ring 5 is attached to a press-fitting jig 21 that is provided above the hub unit 1 so as to be capable of moving up and down. An end face 5a of the inner race 5 on the vehicle inner side (upper side in FIG. 1) is pressed downward using a press-fitting jig 21, thereby press-fitting the inner race 5 onto the outer periphery of the cylindrical portion 3b of the hub axle 3. This completes the temporary press-fitting step S122.

The press-fitting jig 21 is fixed to the lower end of a driving means (not shown) and is moved up and down by the driving means. The driving means has a structure capable of pressing the press-fitting jig 21 downward with the force required for pressing, and capable of adjusting the vertical position of the press-fitting jig 21 with a predetermined accuracy. For example, a hydraulic cylinder, a feed screw mechanism, or the like is used as the driving means. A cylindrical weight 22 is disposed on the radial outside of the press-fitting jig 21, and a downward load is applied to the outer ring 2 by the weight 22. The weight 22 is a member separate from the press-fitting jig 21. The inner ring 5 can also be press-fitted into the hub axle 3 by raising and lowering the base 20 on which the hub axle 3 is placed.

Next, the first measurement step S123 is performed. When the first measurement step S123 is started, as shown in FIG. 2, in the state of the provisional press-fit, the clamp 23 arranged below the flange 2a of the outer ring 2 is moved upward. As a result, the upper surface 23a of the clamp 23 is brought into contact with the lower surface 2a2 of the flange 2a. After the contact, the clamp 23 is further moved upward to bring the rolling element 4f on the inner ring 5 side (vehicle inner side) of the two rows of rolling elements into contact with the second outer ring raceway 2f formed on the inner peripheral surface of the outer ring 2 and the second inner ring raceway 5f formed on the outer peripheral surface of the inner ring 5, which are raceway surfaces for the rolling element 4f (see the white arrow in FIG. 2). Then, in the state in which the rolling element 4f is in contact with the second outer ring raceway 2f and the second inner ring raceway 5f, the distance R1 between the end surface 2b on the vehicle inner side of the outer ring 2 and the end surface 5a on the vehicle inner side of the inner ring 5 is measured.

In this state, the rolling element 4f on the vehicle inner side is not elastically deformed, and the gap between the rolling element 4f and the raceway surface for the rolling element 4f is zero (zero touch). On the other hand, the gap between the rolling element 4e on the vehicle outer side and the raceway surface for the rolling element 4e is a positive gap. As described above, the measurement of the distance R1 is performed using an instrument such as a digital indicator. In addition, the end face 2b and the end face 5a are axial end faces in this disclosure. Such an "axial end face" is a surface that can be a reference surface for measuring the axial distance between a certain member and another member. The "member" includes not only the entire part or element, but also a part of the part or element, such as the flange 2a of the outer ring 2 described later.

3, the clamp 23 is lowered to return the outer ring 2, which has been lifted upward, to its original position (see the outline arrow in FIG. 3). With the above, the first measurement step S123 is completed.

Next, the main press-fitting process S124 is executed. When the main press-fitting process S124 is started, as shown in FIG. 4, the inner ring 5 is press-fitted onto the outer periphery of the hub axle 3 until the inner ring 5 and the hub axle 3 butt against each other (main press-fitting). After that, the downward load applied by the press-fitting jig 21 for the main press-fitting is released, and the inner ring 5 is put into a state where no load is applied. By releasing the load, the inner ring 5 is put into a state where it is not elastically deformed. However, a downward load is applied to the outer ring 2 by a cylindrical weight 22 arranged on the radially outer side of the press-fitting jig 21. By applying such a downward load to the outer ring 2, it is possible to suppress the outer ring 2 from floating upward due to the lip reaction force of the seal 8 arranged on the vehicle outer side when measuring the distance R2 after the main press-fitting, which will be described later. This makes it possible to improve the measurement accuracy of the distance R2. With the above, the main press-fitting process S124 is completed.

Next, the second measurement step S125 is performed. When the second measurement step S125 is performed, the distance R2 between the end face 2b on the vehicle inner side of the outer ring 2 and the end face 5a on the vehicle inner side of the inner ring 5 is measured with no load applied to the inner ring 5 and with a downward load applied to the outer ring 2 by the weight 22. The measurement of the distance R2 is performed with the inner ring 5 fully press-fitted onto the hub axle 3 by the full press-fit step S124. Note that, when performing the measurement, it is not necessary to release the downward load applied by the press-fit jig 21 described above. Also, instead of applying a downward load by the weight 22, a spring (not shown) may be used to apply a downward load to the outer ring 2. Furthermore, depending on the specifications of the seal, the downward load application to the outer ring 2 may be omitted.

The axial clearance is obtained from the difference between the distance R2 and the distance R1 obtained as described above. Specifically, when the difference between the distance R2 and the distance R1, (R2-R1), is a positive value, (R2-R1) is taken as the axial clearance. At this time, the axial clearance is a positive clearance. On the other hand, when (R2-R1) is zero or a negative value, the axial clearance is taken as (R2-R1) x Cb, where Cb is a predetermined constant. At this time, the axial clearance is a zero clearance or a negative clearance. With the above, the second measurement step S125 is completed.

The hub unit 1 used in this embodiment has two rows of rolling elements, namely, the rolling elements 4f on the vehicle inner side and the rolling elements 4e on the vehicle outer side. Therefore, the value of the constant Cb is theoretically "2". However, when the size or specifications of the rolling elements differ between the vehicle inner side and the vehicle outer side, the rigidity differs between the end of the outer ring 2 on the vehicle inner side and the end of the outer ring 2 on the vehicle outer side, which constitute the raceway surface of the rolling elements. In consideration of such cases of different rigidity, the value of Cb may be determined by utilizing the correlation between the axial clearance measured manually and the difference (the difference between the distance R2 and the distance R1) obtained by the clearance measurement method according to this embodiment.

As described above, in the clearance measurement method according to the present embodiment, the axial clearance is obtained by measuring the distances R1 and R2 between the end face 2b on the vehicle inner side of the outer ring 2 and the end face 5a on the vehicle inner side of the inner ring 5 in each of the states in which the inner ring 5 is provisionally and fully press-fitted onto the outer periphery of the cylindrical portion 3b of the hub axle 3. The provisional press-fitting and full press-fitting of the inner ring 5 into the hub axle 3, and the measurement of the distances R1 and R2 can be performed with the hub unit 1 disposed in the same position in the axial clearance measurement device. That is, in the conventional clearance measurement method A, it is necessary to move the hub unit 1 for measuring the positive clearance after the provisional press-fitting, and further move the hub unit 1 for measuring the full press-fitting after the positive clearance measurement. In the conventional clearance measurement method A, it is necessary to dispose the hub unit 1 in three positions. However, in the present embodiment, the clearance measurement can be performed in one position. Therefore, the measurement device can be made smaller, reducing the equipment cost and reducing the equipment space. In addition, both the positive clearance and the negative clearance can be measured from the difference between the distance R2 and the distance R1.

Furthermore, in the clearance measurement method according to this embodiment, when the difference between the distance R2 and the distance R1 is a positive value, (R2-R1) is taken as the axial clearance, and when the difference is zero or a negative value, Cb is taken as a predetermined constant and the axial clearance is taken as (R2-R1) x Cb. In this way, both the positive and negative clearances of the hub unit 1 can be measured based on the difference between the distance R2 and the distance R1.

Furthermore, in the clearance measurement method according to this embodiment, in order to find the axial clearance when the difference between distance R2 and distance R1 is zero or negative, the constant Cb by which this difference is multiplied can be set to 2. On the premise that the clearance of the rolling element on the vehicle inner side and the clearance of the rolling element on the vehicle outer side are the same size, the axial clearance of hub unit 1 can be found by doubling the value of this difference.

[Modification of the gap measurement method]
The embodiments disclosed above are illustrative in all respects and are not restrictive. For example, in the above-described embodiment, when the difference between the distance R2 and the distance R1 is zero or negative, the difference (R2-R1) is multiplied by a predetermined constant Cb to obtain the axial clearance of the hub unit 1. However, the axial clearance of the hub unit 1 can also be obtained by other methods. In the above-described embodiment, the deformation amount of the rolling element on the vehicle inner side is actually measured, and the deformation amount of the rolling element on the vehicle outer side is estimated based on this actual measurement value to obtain the axial clearance of the hub unit 1. In contrast, the deformation amount of the rolling element on the vehicle outer side is measured, and the measurement accuracy of the negative clearance can be improved by adding the deformation amount of the rolling element on the vehicle inner side to the deformation amount of the rolling element on the vehicle inner side.

Specifically, in the above-described embodiment, the distances L1 and L2 between the axial end face of the outer ring 2 and the axial end face of the hub axle 3 are measured after the provisional press-fit and after the full press-fit, respectively. When the difference between the above-described distances R2 and R1 is zero or a negative value, the sum of (R2-R1) and (L2-L1) is taken as the axial clearance. This allows the axial clearance (negative clearance) of the hub unit 1 to be measured more accurately. The distance L1 is, for example, the distance between the vehicle inner end face 2b of the outer ring 2 and the vehicle inner end face 3b1 of the cylindrical portion 3b of the hub axle 3, as shown in FIG. 5 showing the provisional press-fit state. Similarly, the distance L2 is, for example, the distance between the vehicle inner end face 2b of the outer ring 2 and the vehicle inner end face 3b1 of the cylindrical portion 3b of the hub axle 3, as shown in FIG. 6 showing the full press-fit state.

Alternatively, the axial positional relationship between the inner ring 5 and the hub axle 3 may be measured, and the axial positional relationship between the outer ring 2 and the hub axle 3 (the vertical direction in FIGS. 5 and 6) may be indirectly determined using the measured value and a separately measured axial positional relationship between the inner ring 5 and the outer ring 2. Specifically, in the above-described embodiment, the distance P1 between the axial end face 5a of the inner ring 5 and the axial end face 3b1 of the hub axle 3 is measured with the inner ring 5 provisionally press-fitted into the hub axle 3 (see FIG. 5). In addition to this measurement, the distance P2 between the axial end face 5a of the inner ring 5 and the axial end face 3b1 of the hub axle 3 is measured with the inner ring 5 fully press-fitted into the hub axle 3 (see FIG. 6). Then, when the difference (R2-R1) is zero or a negative value, the distance Q1 between the axial end face 2b of the outer ring 2 and the axial end face 3b1 of the hub axle 3 at the time of provisional press-fitting is indirectly determined based on P1 and R1. At the same time, the distance Q2 between the axial end face 2b of the outer ring 2 and the axial end face 3b1 of the hub shaft 3 during full press-fitting is indirectly determined based on P2 and R2. The sum of (R2-R1) and (Q2-Q1) is then determined as the axial clearance.

[Production method]
FIG. 7 is a flow chart showing the procedure of a manufacturing method according to one embodiment of the present invention. In this embodiment, a double row rolling bearing of the type shown in FIG. 11 is manufactured. That is, the double row rolling bearing includes a hub axle 3, an inner ring 5 fitted to the outer periphery of one axial end of the hub axle 3, an outer ring 2 provided coaxially with the hub axle 3 on the radial outside of the hub axle 3 and the inner ring 5, and rolling elements 4e, 4f provided in two rows along the axial direction in an annular space between the hub axle 3, the inner ring 5, and the outer ring 2. In the manufacturing method according to one embodiment of the present invention, in order to assemble this double row rolling bearing, the inner ring 5 is press-fitted into the outer periphery of one axial end of the hub axle 3 to which the rolling elements 4e, 4f and the outer ring 2 are assembled. The manufacturing method includes at least a provisional press-fitting step, a first measuring step, a main press-fitting step, and a second measuring step. In the manufacturing method of this embodiment, a preload gap is measured to determine whether the preload applied to the bearing is appropriate, similar to the above-mentioned gap measuring method. A specific example of the manufacturing method will be described below.

When the manufacturing method according to this embodiment is started, a preparation step S11 is first performed. The preparation step S11 is a step of preparing a hub axle 3 to which the outer ring 2 and two rows of rolling elements 4e, 4f are assembled. The preparation step S11 includes a forming step (e.g., an annealing step, a coating step, a cold forging step, a turning step, a heat treatment step, and a polishing step) of forming each member (e.g., the outer ring 2, the hub axle 3, the rolling elements 4e, 4f, and the inner ring 5) that constitutes the hub unit 1, and an assembly step that is performed after the forming step and that assembles the outer ring 2 and the two rows of rolling elements 4e, 4f to the hub axle 3.

Next, the press-fitting step S12 is performed. The press-fitting step S12 is a step of press-fitting the inner ring 5 onto the outer periphery of one axial end of the hub axle 3 to which the outer ring 2 and the two rows of rolling elements 4e, 4f are attached. FIG. 8 is a flow chart showing the steps of the press-fitting step S12 (contents of the subroutine of the press-fitting step S12) among the steps of the manufacturing method according to one embodiment of the present invention. The press-fitting step S12 includes a placement step S121, a temporary press-fitting step S122, a first measurement step S123, a main press-fitting step S124, and a second measurement step S125. Each step S121 to S125 in the press-fitting step S12 is the same as each step S121 to S125 by the gap measuring device described in the above gap measuring method, and therefore a description thereof will be omitted here.

Refer to Fig. 7. Next, a determination step S13 is executed. The determination step S13 is a step of determining whether or not the axial clearance for the hub unit 1 is an appropriate value based on a comparison between the axial clearance determined in the second measurement step S125 and a reference value. In the determination step S13, a computer having a calculation unit and a storage unit is used. The storage unit stores a reference value indicating an appropriate axial clearance in advance. After the second measurement step S125 is executed, the axial clearance determined in the second measurement step S125 is newly stored in the storage unit.

When the determination step S13 is started, the calculation unit of the computer compares the axial clearance found in the second measurement step S125 with a reference value stored in the memory unit. For example, the difference or ratio between the reference value and the axial clearance found in the second measurement step S125 is calculated. Then, if the difference or ratio is greater than a predetermined threshold value, it is determined that the axial clearance of the hub unit 1 after the press-fitting step S12 is not an appropriate value. If the difference or ratio is equal to or less than a predetermined threshold value, it is determined that the axial clearance of the hub unit 1 after the press-fitting step S12 is an appropriate value. This ends the determination step S13.

Next, a post-process S14 or a confirmation process S15 is performed. The post-process S14 is a process that is performed after the determination process S13 has determined that the axial clearance of the hub unit 1 after the press-fit process S12 is an appropriate value. The post-process S14 includes at least one of a process of deforming a portion of the hub unit 1 and a process of attaching a member to a portion of the hub unit 1. An example of a process of deforming a portion of the hub unit 1 is a process of fixing the position of the inner ring 5 after the main press-fit. Specifically, for example, it is a crimping process. An example of a process of attaching a member to a portion of the hub unit 1 is a process of attaching a seal to at least one of the outer ring 2 and the hub 3 to seal the annular space between the outer ring 2 and the hub axle 3.

An example of the case where a crimping process is included will be described with reference to Figures 9 and 10. Figure 9 is a cross-sectional explanatory diagram showing the state of the hub unit 1 after the determination process S13 and before the crimping process is performed. The hub unit 1 according to this example differs from the above embodiment in that it has a hub axle 300 instead of the hub axle 3 of the above embodiment. Since the other points are common, a description of the common points will be omitted. The cylindrical portion 300b of the hub axle 300 is longer on one axial end side than the cylindrical portion 3b of the hub axle 3 (see Figure 1), and protrudes further toward the vehicle inner side than the end face 5a on the vehicle inner side of the inner ring 5.

9 differs from the press-fitting jig 20 of the above embodiment in that it has a recess 21b on the end face on the vehicle outer side. Since the other points are the same, a description of the common points will be omitted. The recess 21b has a shape that is more recessed than the shape of the cylindrical portion 300b that protrudes toward the vehicle inner side from the end face 5a. When the press-fitting jig 21a provisionally and fully presses in the inner ring 5, the end of the cylindrical portion 300b on the vehicle inner side does not come into contact with the recess 21b.

10 is a cross-sectional explanatory diagram showing the state of the hub unit 1 after the crimping process is performed. In the crimping process, a crimping jig is used, although not shown. The crimping jig has, for example, a portion having a smaller diameter than the inner circumference of the cylindrical portion 300b and a portion having a larger diameter than the inner circumference of the cylindrical portion 300b. The small diameter portion and the large diameter portion are arranged coaxially, and a surface (e.g., a conical surface) that expands in diameter from the small diameter portion to the large diameter portion without reducing in diameter is formed. When the crimping process is started, the small diameter portion of the crimping jig is inserted into the inner circumference of the cylindrical portion 300b, and the expanding surface (e.g., a conical surface) of the crimping jig oscillates while pressing against the cylindrical portion 300b.
As a result, the cylindrical portion 300b is plastically deformed starting from the reference point 300c, and expands radially outward as shown in Figure 10. The rocking of the crimping jig is then stopped, and the crimping jig is held pressed against the end face of the cylindrical portion 300b on the vehicle inner side for a predetermined period of time without rocking. This fixes the position of the inner ring 5 relative to the hub axle 300, and the crimping process is completed.

Please refer to Fig. 7. The confirmation process S15 is a process that is executed after it is determined in the determination process S13 that the axial gap in the hub unit 1 after the press-fitting process S12 is not an appropriate value. The confirmation process S15 includes at least one of a process of inspecting the hub unit 1 and a process of discarding the hub unit 1.

In the process of inspecting the hub unit 1, for example, the hub unit 1 is disassembled and the dimensions of each component, the hub axle 3, inner ring 5, outer ring 2, and rolling elements 4e and 4f, are measured to confirm the accuracy of each component, or the hub unit 1 is removed from the axial clearance measuring device and the axial clearance is measured using another method.
Based on these inspections, the cause of the axial clearance of the hub unit 1 not being at an appropriate value (cause of an abnormality) is determined, and inspections of the manufacturing line are performed as necessary.

In the step of discarding the hub units 1, the hub units 1 that are determined to have an axial clearance that is not an appropriate value are discarded. The hub units 1 may be discarded after the above inspection is performed.

As described above, according to the confirmation process S15, if it is determined that the axial clearance is not an appropriate value, the manufactured hub unit 1 can be inspected or discarded. This makes it possible to improve the quality of the hub units 1 that are put on the production line. Furthermore, since the post-process S14 is only performed on hub units 1 that are determined to have an appropriate axial clearance, the yield after the post-process S14 is improved, and the production efficiency of the production line can be improved.

In the manufacturing method of this embodiment, the axial clearance is obtained by measuring the distances R1 and R2 between the axial end face of the outer ring 2 and the axial end face of the inner ring 5 in each state in which the inner ring 5 is provisionally and fully press-fitted onto the hub axle 3. The provisional press-fitting step S122, the first measuring step S123, the full press-fitting step S124, and the second measuring step S125 according to this embodiment can be performed in a state in which the double row rolling bearing (hub unit 1) is placed in the same position (pedestal 20) in the manufacturing device for the double row rolling bearing, that is, in one position. This allows the manufacturing device to be made smaller, reducing equipment costs and reducing the equipment space. In addition, both the positive clearance and the negative clearance can be measured from the difference between the distance R2 and the distance R1.

[Modification of the manufacturing method]
The embodiments disclosed above are illustrative in all respects and are not restrictive. For example, in the preparation step S11 according to the above embodiment, the hub axle 3 is prepared with the outer ring 2 and two rows of rolling elements 4e, 4f assembled thereto. Then, in the press-fit step S12, the inner ring 5 is press-fitted onto the outer periphery of one axial end of the hub axle 3 with the outer ring 2 and two rows of rolling elements 4e, 4f assembled thereto.
However, the preparation step and the press-fitting step of the present disclosure are not limited to this. In the preparation step, the outer ring 2 and the hub axle 3 with the row of rolling elements 4e assembled on the other axial end side may be prepared, and in the press-fitting step, the inner ring 5 with the row of rolling elements 4f may be press-fitted onto the outer periphery of one axial end of the hub axle 3 in this state. In this case, the row of rolling elements 4f is held by the inner ring 5 together with the cage 6f, and the inner ring 5 is press-fitted onto the hub axle 3 with the row of rolling elements 4f and the inner ring 5 integrated together.
In the above embodiment, a mounting step is performed in which the hub axle 3 is placed on the pedestal 20 with its axis facing up and down, and the outer ring 2 is placed on the rolling elements 4f with the rolling elements 4e, 4f provided on the hub axle 3. However, instead of this, the mounting step may involve placing the hub axle 3 on the pedestal 20 with its axis facing up and down, placing the rolling elements 4e, 4f on the hub axle 3, and then placing the outer ring 2 on the rolling elements 4f.

Even in the case of the above configuration, the axial clearance can be measured in one position. Therefore, the manufacturing equipment can be made compact, reducing the equipment cost and the equipment space. In addition, both the positive clearance and the negative clearance can be measured from the difference between the distance R2 and the distance R1.
In addition, at least a part of the above-mentioned embodiment and various modified examples may be arbitrarily combined with each other. In addition, the embodiment disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims.

REFERENCE SIGNS LIST 1: Hub unit 2: Outer ring 2a: Flange 2b: Vehicle inner end face 2e: First outer ring raceway 2f: Second outer ring raceway 3: Hub shaft 3a: Spindle portion 3b: Cylindrical portion 3d: Flange 3e: First inner ring raceway 3f: Hole 4e: Vehicle outer rolling element 4f: Vehicle inner rolling element 5: Inner ring 5a: Vehicle inner end face 5f: Second inner ring raceway 6e: Vehicle outer retainer 6f: Vehicle inner retainer 7: Bolt 8: Seal 20: Base 21: Press-fit jig 22: Weight 23: Clamp

Claims (5)

A method for measuring an axial clearance of a double row rolling bearing comprising: a hub shaft; an inner ring fitted onto an outer periphery of one axial end of the hub shaft; an outer ring provided coaxially with the hub shaft and radially outward of the hub shaft and the inner ring; and rolling elements provided in two rows along the axial direction in an annular space between the hub shaft and the inner ring, the method comprising:
The inner ring is provisionally press-fitted onto the hub shaft with the outer ring attached via the rolling elements in a position in which the axis of the hub shaft faces up and down;
With the inner ring provisionally press-fitted onto the hub axle, the outer ring is raised upward to bring the rolling elements on the inner ring side of the two rows of rolling elements into contact with a raceway surface for the rolling elements on the inner ring side;
a distance R1 between an axial end face of the outer ring and an axial end face of the inner ring is measured with the rolling elements and the raceway surface in contact with each other;
Return the outer ring that was lifted upward to its original position,
The inner ring is press-fitted onto the hub shaft until the inner ring and the hub shaft butt against each other;
With the inner ring fully press-fitted onto the hub axle, a distance R2 between an end face of the outer ring in the axial direction and an end face of the inner ring in the axial direction is measured;
The axial clearance is calculated from the difference between the distance R2 and the distance R1 (R2-R1) ,
When the difference is a positive value, (R2-R1) is defined as the axial clearance, and when the difference is zero or a negative value, C is a predetermined constant (C>0) , and the axial clearance is defined as (R2-R1) x C.
How to measure axial clearance in double row rolling bearings. The method for measuring the axial clearance of a double row rolling bearing according to claim 1, wherein the constant C is 2. In order to assemble a double row rolling bearing comprising a hub shaft, an inner ring fitted onto the outer periphery of one axial end of the hub shaft, an outer ring disposed coaxially with the hub shaft and radially outward of the hub shaft and the inner ring, and rolling elements disposed in two rows along the axial direction in an annular space between the hub shaft, the inner ring, and the outer ring,
a manufacturing method for a hub shaft having the rolling elements and the outer ring assembled thereto, the method comprising: press-fitting the inner ring onto an outer periphery of one axial end of the hub shaft,
a temporary press-fitting step of temporarily press-fitting the inner ring onto the hub axle with the outer ring attached via the rolling elements in a position in which the axis of the hub axle faces up and down;
a first measuring step of lifting the outer ring upward with the inner ring provisionally press-fitted onto the hub axle by the provisional press-fit step, bringing the rolling elements on the inner ring side of the two rows of rolling elements into contact with raceway surfaces for the rolling elements on the inner ring side, measuring a distance R1 between an end face in the axial direction of the outer ring and an end face in the axial direction of the inner ring while the rolling elements and the raceway surfaces are in contact, and returning the outer ring that was lifted upward to its original position;
a final press-fitting step of final press-fitting the inner ring onto the hub shaft until the inner ring and the hub shaft butt against each other;
a second measuring step of measuring a distance R2 between an end face of the outer ring in the axial direction and an end face of the inner ring in the axial direction with the inner ring fully press-fitted onto the hub shaft in the full press-fit step, and determining an axial clearance from the difference between the distance R2 and the distance R1 , that is, (R2-R1) ;
When the difference is a positive value, (R2-R1) is defined as the axial clearance, and when the difference is zero or a negative value, C is a predetermined constant (C>0) , and the axial clearance is defined as (R2-R1) x C.
A manufacturing method for double row rolling bearings. the provisional press-fitting step, the first measuring step, the main press-fitting step, and the second measuring step are performed in a state where the hub axle is placed on the same pedestal.
A method for manufacturing the double row rolling bearing according to claim 3. a determination step of determining whether or not the axial clearance is an appropriate value based on a comparison between the axial clearance obtained in the second measurement step and a reference value;
a confirmation step that is executed after the determination step has determined that the axial clearance is not an appropriate value, the confirmation step including at least one of a step of inspecting the double row rolling bearing and a step of discarding the double row rolling bearing;
The method for manufacturing a double row rolling bearing according to claim 3 or 4, further comprising:

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