JP7483555B2 - Method for inspecting preload on wheel bearing device - Google Patents

Description

The present invention relates to a method for preload inspection of wheel bearing devices.

Conventionally, wheel bearing devices that support the wheels rotatably in the suspension of automobiles and the like are known. In such wheel bearing devices, a preload is applied between the rolling elements and races that make up the bearing device.

Applying a preload to a bearing device can increase the rigidity of the bearing device and suppress vibration and noise. However, applying an excessive preload can lead to an increase in rotational torque and a shortened lifespan, so it is important to check whether an appropriate preload is being applied to the bearing device.

As a method for checking the preload applied to a bearing device, for example, as disclosed in Patent Document 1, a preload measurement method is known in which a rolling bearing having rolling elements arranged in double rows is used to measure the preload applied to the bearing by measuring the preload gap in the axial direction.

When determining the preload applied to a bearing from the preload gap, for example in a wheel bearing device in which the hub wheel is crimped to the inner ring to form the inner member, the amount of compression of the inner ring when the hub wheel is crimped can be converted into the amount of preload gap reduction, and the preload applied to the bearing device can be determined by combining the amount of preload gap reduction with the preload gap before crimping.

Japanese Patent Application Laid-Open No. 10-185717

However, in a bearing device in which the hub ring is crimped to the inner ring, if an abnormality such as deformation of the inner ring raceway occurs during the crimping process, it becomes difficult to accurately determine the amount of preload gap reduction from the amount of pressing in of the inner ring, and there is a risk that the reliability of the measured value of the preload applied to the bearing device will decrease.

Therefore, the present invention provides a preload inspection method for wheel bearing devices that can inspect the preload applied to the wheel bearing devices with a higher degree of reliability.

That is, the first invention is a preload inspection method for a wheel bearing device comprising an outer member having a double-row outer raceway surface on its inner circumference, a hub wheel having a small diameter step portion extending axially on its outer circumference, and an inner ring press-fitted into the small diameter step portion of the hub wheel, an inner member having a double-row inner raceway surface facing the double-row outer raceway surface, and double-row rolling elements accommodated in a rollable manner between both raceway surfaces of the outer member and the inner member, the method comprising the steps of: a press-fitting step of press-fitting the inner ring into the small diameter step portion of the hub wheel in the axial direction to a position where the inner ring abuts against the hub wheel; a first bearing preload value calculation step of calculating a first bearing preload value of the wheel bearing device based on an axial negative gap between both raceway surfaces and the rolling elements after the press-fitting step; and a second bearing preload value calculation step of calculating a second bearing preload value of the wheel bearing device when the inner member and the outer member are rotated relative to each other after the press-fitting step. The preload inspection method for a wheel bearing device includes a post-press-fit rotational torque measurement process for measuring the post-press-fit rotational torque of the wheel bearing device when the inner member and the outer member are rotated relatively after the press-fit rotational torque measurement process, a crimping rotational torque measurement process for measuring the post-press-fit rotational torque of the wheel bearing device when the inner member and the outer member are rotated relatively after the crimping process, a second bearing preload value calculation process for calculating a second bearing preload value by adding the preload change amount between the press-fitting process and the crimping process, which is calculated based on the differential torque between the press-fitting rotational torque and the crimping rotational torque, to the first bearing preload value, and a determination process for determining whether the preload applied to the wheel bearing device is appropriate based on whether the second bearing preload value is within a reference value range.

The effects of the present invention are as follows:

In other words, according to the first invention, the preload applied to the wheel bearing device can be inspected with a higher degree of reliability.

1 is a side cross-sectional view showing a wheel support bearing device to which a preload inspection method is applied; FIG. 1 is a diagram showing a flow of a preload inspection method. 4 is a side cross-sectional view showing the wheel bearing device in a state in which the inner ring is temporarily press-fitted into a small diameter stepped portion of the hub wheel. FIG. 4 is a side cross-sectional view showing the wheel bearing device in a state in which the inner ring is press-fitted into a small diameter stepped portion of the hub wheel. FIG. FIG. 11 is a diagram showing the relationship between time and torque when a hub wheel and an outer wheel are rotated relatively. 11 is a diagram showing the relationship between the rotation speed and torque when the hub wheel and the outer wheel are rotated relatively to each other. FIG. 4 is a side cross-sectional view showing the wheel bearing device in a state in which a small diameter stepped portion of a hub wheel is crimped to an inner ring. FIG. FIG. 4 is a diagram showing the relationship between bearing preload and rotational torque. 11 is a side cross-sectional view showing the mounting of an inner seal member to an inner end portion of an outer ring after a post-crimping rotational torque measuring process. FIG.

[Wheel bearing device]
Hereinafter, a wheel support bearing device 1 which is a first embodiment of a wheel support bearing device to which a preload inspection method according to the present invention is applied will be described with reference to FIG.

The wheel bearing device 1 shown in FIG. 1 supports a wheel rotatably in a suspension system of a vehicle such as an automobile. The wheel bearing device 1 has a configuration called the third generation, and includes an outer ring 2 as an outer member, a hub wheel 3 and an inner ring 4 as inner members, two rolling rows of inner ball rows 5 and outer ball rows 6, and an inner seal member 9 and an outer seal member 10. Here, the inner side refers to the vehicle body side of the wheel bearing device 1 when it is attached to the vehicle body, and the outer side refers to the wheel side of the wheel bearing device 1 when it is attached to the vehicle body. The axial direction refers to the direction along the rotation axis of the wheel bearing device 1.

The inner end of the outer ring 2 is formed with an inner opening 2a into which the inner seal member 9 can be fitted. The outer end of the outer ring 2 is formed with an outer opening 2b into which the outer seal member 10 can be fitted. The inner peripheral surface of the outer ring 2 is formed with an inner outer raceway surface 2c and an outer outer raceway surface 2d. The outer peripheral surface of the outer ring 2 is integrally formed with a vehicle body mounting flange 2e for mounting the outer ring 2 to a vehicle body member. The vehicle body mounting flange 2e is provided with a bolt hole 2g into which a fastening member (here, a bolt) is inserted to fasten the vehicle body member to the outer ring 2.

The inner end of the hub wheel 3 has a small diameter step 3a formed on the outer circumferential surface, which is smaller in diameter than the outer end. A shoulder 3e is formed on the outer end of the small diameter step 3a of the hub wheel 3. A wheel mounting flange 3b for mounting a wheel is integrally formed on the outer end of the hub wheel 3. The wheel mounting flange 3b has a bolt hole 3f into which a hub bolt is pressed to fasten the hub wheel 3 to a wheel or brake component.

The hub wheel 3 has an outer inner raceway surface 3c that faces the outer outer raceway surface 2d of the outer ring 2. A lip sliding surface 3d is formed on the base side of the wheel mounting flange 3b of the hub wheel 3, against which the outer seal member 10 slides. The outer seal member 10 fits into the outer opening end of the annular space formed by the outer ring 2 and the hub wheel 3. The hub wheel 3 has an outer end surface 3g at the end on the outer side of the wheel mounting flange 3b.

The inner ring 4 is provided on the small diameter step 3a of the hub ring 3. The inner ring 4 is fixed to the small diameter step 3a of the hub ring 3 by press fitting and crimping. The inner ring 4 applies preload to the inner ball row 5 and outer ball row 6, which are the rolling rows. The inner ring 4 has an inner end face 4b at its inner end, and an outer end face 4c at its outer end. At the inner end of the hub ring 3, a crimped portion 3h is formed by crimping the inner end face 4b of the inner ring 4.

The inner raceway 4a is formed on the outer peripheral surface of the inner ring 4. In other words, the inner raceway 4a is formed by the inner ring 4 on the inner side of the hub ring 3. The inner raceway 4a of the inner ring 4 faces the outer raceway 2c on the inner side of the outer ring 2.

The inner ball row 5 and outer ball row 6, which are rolling rows, are formed by a plurality of balls 7, which are rolling elements, held by a cage 8. The inner ball row 5 is rollably sandwiched between the inner raceway surface 4a of the inner ring 4 and the outer raceway surface 2c on the inner side of the outer ring 2. The outer ball row 6 is rollably sandwiched between the inner raceway surface 3c of the hub ring 3 and the outer raceway surface 2d on the outer side of the outer ring 2.

In the wheel bearing device 1, a double-row angular ball bearing is formed by the outer ring 2, the hub ring 3, the inner ring 4, the inner ball row 5, and the outer ball row 6. The wheel bearing device 1 may also be formed by a double-row tapered roller bearing.

[Preload inspection method]
Next, a preload inspection method for the wheel support bearing device 1 will be described. As shown in Fig. 2, the preload inspection method in this embodiment is performed during the assembly of the wheel support bearing device 1. Specifically, the preload inspection method includes a temporary press-fitting step (S01), a press-fitting step (S02), a first bearing preload value calculation step (S03), a running-in step (S04), a post-press-fit rotational torque measurement step (S05), a crimping step (S06), a post-crimping rotational torque measurement step (S07), a second bearing preload value calculation step (S08), a determination step (S09), and an inner seal member mounting step (S10). Each step of the preload inspection method will be described below.

(Temporary press-fit process)
As shown in Figure 3, the hub wheel 3 is placed on the support base 11 with its axial direction vertical and its outer end face 3g positioned downward. The outer end face 3g of the hub wheel 3 is in contact with the support base 11. The outer ring 2 is rotatably mounted on the hub wheel 3 placed on the support base 11 via an inner ball row 5 and an outer ball row 6. An outer seal member 10 is fitted into the outer end of the outer ring 2. Grease is filled between the hub wheel 3 and the outer ring 2.

In the temporary press-fitting step (S01), the inner ring 4 is first temporarily pressed into the small diameter step 3a of the hub wheel 3 placed on the support stand 11. The temporary press-fitting of the inner ring 4 is performed by pressing the inner ring 4 into the small diameter step 3a from above and stopping the press-fitting before the outer end face 4c of the inner ring 4 abuts against the shoulder 3e of the hub wheel 3. Here, the press-fitting of the inner ring 4 is performed under a predetermined pressure using a pressing device such as a hydraulic cylinder or an air cylinder. When the temporary press-fitting of the inner ring 4 is completed, there is an axial positive gap G0 between the raceway surface (e.g., the outer raceway surface 2c and the inner raceway surface 4a) and the rolling element. This axial positive gap G0 can be measured, for example, from the axial movement amount of the outer ring 2.

In the temporary press-fitting step (S01), the axial positive gap G0 between the raceway surfaces (e.g., the outer raceway surface 2c and the inner raceway surface 4a) and the rolling elements, and the axial dimension H0 between the outer end face 3g of the hub ring 3 and the inner end face 4b of the inner ring 4 after the inner ring 4 is temporarily pressed in are measured. The axial dimension H0 can be measured using a measuring device 12 such as a dial gauge.

(Press-fitting process)
The press-fitting step (S02) is carried out after the temporary press-fitting step (S01). As shown in FIG. 4, in the press-fitting step (S02), the inner ring 4 is press-fitted into the small diameter step 3a until the outer end face 4c of the inner ring 4 abuts against the shoulder 3e of the hub wheel 3. After the inner ring 4 has been pressed into the small diameter step 3a, the axial dimension H1 between the outer end face 3g of the hub wheel 3 and the inner end face 4b of the inner ring 4 after the inner ring 4 has been pressed is measured. In addition, the value obtained by subtracting the axial dimension H1 from the axial dimension H0 is subtracted from the positive axial clearance G0 between the raceway surface and the rolling elements measured in the temporary press-fitting step (S01) to obtain the negative axial clearance G1 between the raceway surface and the rolling elements after the inner ring 4 has been pressed (G1=G0-(H0-H1).

(First bearing preload value calculation process)
After the press-fitting step (S02), a first bearing preload value calculation step (S03) is performed. In the first bearing preload value calculation step (S03), a first bearing preload value P1 applied to the bearing after the press-fitting step is calculated based on the negative axial clearance G1 determined in the press-fitting step (S02). The first bearing preload value P1 is calculated by determining in advance the relationship between the negative axial clearance G1 and the bearing preload value in the wheel bearing device 1 by experiment or the like, and fitting the negative axial clearance G1 determined in the press-fitting step (S02) to this relationship. Note that this relationship between the negative axial clearance and the bearing preload value can be determined for each specification of the wheel bearing device 1.

(Run-in process)
The first bearing preload value calculation step (S03) is followed by a running-in step (S04). In the running-in step (S04), the hub ring 3 into which the inner ring 4 is press-fitted and the outer ring 2 are rotated relative to each other to allow the grease filled between the hub ring 3 and the outer ring 2 to run into the balls 7 of the inner ball row 5 and the outer ball row 6. In the running-in step (S04), the outer ring 2 may be fixed and the hub ring 2 may be rotated, or the outer ring 2 may be fixed and the hub ring 3 may be rotated.

By carrying out the break-in process (S04), the resistance generated between the grease and the balls 7 can be made constant when the hub wheel 3 and the outer ring 2 are rotated relative to each other. This makes it possible to suppress the occurrence of variations in the measured rotational torque when the rotational torque of the wheel bearing device 1 is measured in the later post-press-fit rotational torque measurement process (S05) and post-swage rotational torque measurement process (S07). Note that in the break-in process (S04), it is preferable to rotate the hub wheel 3 and the outer ring 2 relatively 30 or more times in order to suppress variations in the rotational torque.

(Rotational torque measurement process after press fitting)
After the running-in step (S04), a post-press-fit rotation torque measuring step (S05) is performed. In the post-press-fit rotation torque measuring step (S05), the post-press-fit rotation torque Ta is measured by a torque measuring device 13 when the hub wheel 3, in which the inner ring 4 is press-fitted into the small diameter step 3a, and the outer ring 2 are rotated relative to each other. The post-press-fit rotation torque Ta is a rotation torque measured after the press-fit step (S02) and before the crimping step (S06). In the post-press-fit rotation torque measuring step (S05), the outer ring 2 may be fixed and the hub wheel 3 may be rotated, or the outer ring 2 may be rotated and the hub wheel 3 may be fixed.

When the hub wheel 3 is rotated, the revolution speed of the balls 7 in the inner ball row 5 and the outer ball row 6 is slower than when the outer ring 2 is rotated, and the variation in the rotational torque value measured when the rotational speed of the hub wheel 3 changes is smaller, so it is preferable to rotate the hub wheel 3 in the rotational torque measurement process. Note that when rotating the hub wheel 3, the hub wheel 3 can be rotated by rotating the support base 11 on which the hub wheel 3 is placed.

In addition, in the post-press-fit rotational torque measurement process (S05), the rotational torque is measured, not the starting torque of the bearing. As shown in FIG. 5, the starting torque is the peak value of the initial torque when the bearing starts to rotate, but it decreases over time and changes significantly over time. Therefore, it is poorly repeatable. In contrast, the rotational torque is the torque after the bearing starts to rotate, and shows a constant value with almost no change over time. Therefore, in the post-press-fit rotational torque measurement process (S05), by measuring the post-press-fit rotational torque Ta, which is the rotational torque, it is possible to measure the torque value of the bearing with high accuracy.

As shown in Figure 6, the rotational torque of the bearing when the hub wheel 3 and the outer ring 2 are rotated relative to each other increases as the rotational speed of the hub wheel 3 or the outer ring 2 increases in a range above a certain value, but when the rotational speed of the hub wheel 3 or the outer ring 2 is very small, it decreases as the rotational speed increases and then starts to increase. In other words, there is a region where the rotational torque of the bearing goes from decreasing to increasing as the rotational speed increases, and in that region, the degree of fluctuation in the rotational torque relative to changes in the rotational speed is small.

In the post-press-fit rotational torque measurement process (S05), the hub wheel 3 or outer ring 2 is rotated at a constant rotational speed so that there is no variation in the measured rotational torque. The rotational speed of the hub wheel 3 or outer ring 2 is set in the range of rotational speeds N1 to N2 in the region where the rotational torque changes from decreasing to increasing. This makes it possible to reduce fluctuations in the rotational torque even if the rotational speed changes during measurement of the post-press-fit rotational torque Ta.

In the post-press-fit rotational torque measurement process (S05), the rotational torque is measured in a state where dynamic frictional forces are generated between the inner members 3, 4 and the outer member 2. Specifically, the rotational torque is measured in a state where dynamic frictional forces are generated between the inner members 3, 4 and the rolling elements 7, between the hub wheel 3 and the outer seal member 10, and between the outer ring 2 and the rolling elements 7 and the outer seal member 10. Generally, the dynamic friction coefficient is smaller than the static friction coefficient, and the variation is small, so the rotational torque can be measured with high accuracy.

The rotation speed N1, which is the lower limit of the rotation speed range, is preferably set to 10 rpm, at which the rotation torque can be measured while kinetic friction is occurring. The rotation speed N2, which is the upper limit of the rotation speed range, is preferably set to 60 rpm, at which the stirring resistance of the grease filled between the hub wheel 3 and the outer ring 2 is minimized. In this embodiment, the rotation speed of the hub wheel 3 or the outer ring 2 is set to 10 rpm to 30 rpm, within the range of 10 rpm to 60 rpm, at which the fluctuation in rotation torque with respect to changes in rotation speed is minimized. This makes it possible to measure the rotation torque with high accuracy.

In this way, in the post-press-fit rotational torque measurement process (S05), by rotating the hub wheel 3 or outer ring 2 at a low rotational speed range of N1 to N2, where the degree of variation in rotational torque relative to changes in rotational speed is small, even if the rotational speed of the hub wheel 3 or outer ring 2 changes, the variation in rotational torque can be minimized, making it possible to measure the rotational torque with high accuracy.

In addition, in the post-press-fit rotational torque measurement process (S05), the rotational torque of the wheel bearing device 1 is measured with the outer seal member 10 fitted into the outer opening end of the annular space formed by the outer ring 2 and the hub wheel 3. Here, the outer seal member 10 is located axially opposite the small diameter step 3a of the hub wheel 3 that is crimped to fix the inner ring 4. Therefore, even if an abnormality occurs in the inner ring raceway surface 4a, etc., in the crimping process (S06) described next, the seal torque of the outer seal member 10 is unlikely to be affected, and the rotational torque of the wheel bearing device 1 is unlikely to change.

(Crimping process)
After the post-press-fit rotational torque measuring step (S05), a crimping step (S06) is performed. In the crimping step (S06), a crimping process is performed to crimp the inner end of the small diameter step 3a of the hub wheel 3 to the inner end face 4b of the inner ring 4. The crimping process can be performed by, for example, swing crimping. After the crimping process is performed, a negative axial gap is generated between the inner ring 4 and the hub wheel 3.

(Post-swaging rotation torque measurement process)
After the crimping step (S06), a post-crimping rotational torque measuring step (S07) is performed. In the post-crimping rotational torque measuring step (S07), the rotational torque is measured in a state where a dynamic frictional force is generated between the inner members 3, 4 and the outer member 2, as in the post-press-fitting rotational torque measuring step. In the post-crimping rotational torque measuring step (S07), the post-crimping rotational torque Tb is measured by the torque measuring device 13 when the hub wheel 3, in which the small diameter step portion 3a is crimped to the inner wheel 4, and the outer wheel 2 are rotated relative to each other. The post-crimping rotational torque Tb is a rotational torque measured after the crimping step (S06) and before the inner seal member mounting step (S10). In the post-crimping rotational torque measuring step (S07), the outer wheel 2 may be fixed and the hub wheel 3 may be rotated, or the outer wheel 2 may be fixed and the hub wheel 3 may be rotated.

However, as in the case of the post-press-fit rotational torque measurement process (S05), it is preferable to rotate the hub wheel 3, as this reduces the variation in the rotational torque value measured when the rotational speed of the hub wheel 3 changes. Also, as in the case of the post-press-fit rotational torque measurement process (S05), in the post-swage rotational torque measurement process (S07), the rotational torque is measured instead of the starting torque of the bearing, and the post-swage rotational torque Tb is measured while rotating the hub wheel 3 or the outer ring 2 at a constant rotational speed between the low rotational speeds N1 and N2, making it possible to measure the rotational torque with high accuracy.

In this case, it is preferable to set the rotation speed N1 to 10 rpm and the rotation speed N2 to 60 rpm, as in the case of the post-press-fit rotation torque measurement step (S05). In this embodiment, the rotation speed of the hub wheel 3 or the outer ring 2 is set to be 10 rpm to 30 rpm, within the range of 10 rpm to 60 rpm, at which the fluctuation in rotation torque with respect to the change in rotation speed is the smallest. As a result, even if the rotation speed changes during measurement of the post-swage rotation torque Tb, the fluctuation in the post-swage rotation torque Tb can be reduced, and the rotation torque can be measured stably.

In addition, between the crimping step (S06) and the post-crimping rotational torque measurement step (S07), a step similar to the break-in step (S04) can be carried out, that is, a break-in step in which the grease filled between the hub wheel 3 and the outer ring 2 is allowed to break in to the balls 7 of the inner ball row 5 and the outer ball row 6. This makes it possible to keep constant the resistance that occurs between the grease and the balls 7 when the hub wheel 3 and the outer ring 2 are rotated relative to one another, and makes it possible to further suppress the occurrence of variations in the measured post-crimping rotational torque Tb when the post-crimping rotational torque Tb of the wheel bearing device 1 is measured in the post-crimping rotational torque measurement step (S07).

However, if the break-in process (S04) is performed so that the grease and the ball 7 are sufficiently familiar with each other and the resistance generated between the grease and the ball 7 is constant, the break-in process between the crimping process (S06) and the post-crimping rotational torque measurement process (S07) can be omitted.

(Second bearing preload value calculation process)
A second bearing preload value calculation step (S08) is carried out after the post-crimping rotational torque measurement step (S07). In the second bearing preload value calculation step (S08), a differential torque ΔT (Tb-Ta=ΔT) between the post-press-fit rotational torque Ta and the post-crimping rotational torque Tb is calculated. In addition, a preload change amount ΔP between after the press-fitting step and after the crimping process is obtained based on the differential torque ΔT. Furthermore, a second bearing preload value P2 is calculated by adding the preload change amount ΔP to the first bearing preload value P1 calculated in the first bearing preload value calculation step (S03).

In this case, the differential torque ΔT is the rotational torque increased by the crimping process performed in the crimping process (S06). The preload change amount ΔP is the preload increased by the crimping process performed in the crimping process (S06). As shown in FIG. 8, the preload change amount ΔP is calculated by finding in advance the relationship between the bearing preload of the wheel bearing device 1 and the rotational torque of the bearing through experiments or the like, and applying the differential torque ΔT to this relationship. Note that this relationship between the bearing preload and the rotational torque of the bearing can be found for each specification of the wheel bearing device 1.

(Determination step)
The second bearing preload value calculation step (S08) is followed by a determination step (S09). In the determination step (S09), the appropriateness of the preload applied to the wheel support bearing device 1 is determined based on whether or not the second bearing preload value P2 is within a predetermined reference value range. In the determination step (S09), if the second bearing preload value P2 is within the predetermined reference value range, it is determined that the preload applied to the wheel support bearing device 1 is appropriate, and if the second bearing preload value P2 is not within the predetermined reference value range, it is determined that the preload applied to the wheel support bearing device 1 is inappropriate.

In the second bearing preload value calculation process (S08), the preload change amount ΔP due to the crimping process is calculated using the post-press-fit rotational torque Ta and the post-crimping rotational torque Tb, which are the rotational torques before and after the crimping process, and then the second bearing preload value P2 is calculated.

In this way, when the preload is calculated using the rotational torque before and after the crimping process, if an abnormality such as deformation of the inner ring raceway surface occurs during the crimping process, the increase in the rotational torque before and after the crimping process will be large, and the calculated second bearing preload value P2 will fall outside the range of the specified reference value. Therefore, by judging the calculated second bearing preload value P2 in the judgment step (S09), it is possible to detect the occurrence of an abnormality in the wheel support bearing device 1 after the crimping process, and the reliability of the measured value of the preload applied to the wheel support bearing device 1 can be increased. This makes it possible to inspect the preload applied to the wheel support bearing device 1 with a higher reliability.

The post-press-fit rotational torque Ta and post-crimp rotational torque Tb used in calculating the second bearing preload value P2 are values measured for the same wheel bearing device 1 before and after crimping. Therefore, the torque difference ΔT between the post-press-fit rotational torque Ta and the post-crimp rotational torque Tb does not include individual variations in the wheel bearing device 1, such as the lip tightening margin of the outer seal member 10 or the amount of grease filled between the hub wheel 3 and the outer ring 2, and only the increase in rotational torque due to crimping is extracted. This makes it possible to accurately calculate the second bearing preload value P2 from the torque difference ΔT, and to accurately determine whether the preload applied to the wheel bearing device 1 is appropriate in the determination step (S09).

The reference value used in determining whether the preload is appropriate in the determination step (S09) is set taking into consideration the variation in rotational torque that occurs when performing the crimping process to crimp the small diameter step portion 3a to the inner ring 4.

In other words, there may be variation between the post-press-fit rotational torque Ta and the post-crimping rotational torque Tb due to the movement of the grease position between the hub wheel 3 and the outer ring 2 before and after the crimping process, and due to changes in the way the outer seal member 10 contacts the hub wheel 3 and the outer ring 2. In addition, there may be variation due to repeated measurements of the rotational torque between the post-press-fit rotational torque Ta measured before the crimping process and the post-crimping rotational torque Tb measured after the crimping process.

Therefore, in this embodiment, taking these variations into account, the range of the reference value is set to a narrower range than when the variations are not taken into account. This allows the preload applied to the wheel bearing device 1 to be accurately determined in the determination step (S09), making it possible to prevent erroneous determinations from occurring.

(Inner seal member installation process)
After the determination step (S09), an inner seal member fitting step (S10) is performed. By performing the inner seal member fitting step (S10), the assembly process of the wheel bearing device 1 is completed. The inner seal member fitting step (S10) can also be performed before the determination step (S09) or before the second bearing preload value calculation step (S08) as long as it is performed after the post-swaging rotational torque measurement step (S07). As shown in FIG. 9, in the inner seal member fitting step (S10), the inner seal member 9 is fitted into the inner opening 2a of the outer ring 2, thereby fitting the inner seal member 9 between the inner end of the outer ring 2 and the inner end of the inner ring 4.

If the inner seal member 9 is attached before the crimping step (S06), the sliding resistance between the outer ring 2 and the inner ring 4 of the inner seal member 9 changes depending on the degree of crimping of the hub wheel 3 in the crimping step (S06). Also, if the inner seal member 9 is attached after the crimping step (S06) but before the post-crimping rotational torque measurement step (S07), the sliding resistance between the outer ring 2 and the inner ring 4 of the inner seal member 9 changes depending on the attachment state of the inner seal member 9.

Therefore, if the inner seal member 9 is attached before the crimping step (S06) or the post-crimping rotational torque measurement step (S07), it may affect the variability of the post-crimping rotational torque Tb measured in the post-crimping rotational torque measurement step (S07). Similarly, if the inner seal member 9 is attached before the post-press-fitting rotational torque measurement step (S05), the attachment state of the inner seal member 9 may affect the variability of the post-press-fitting rotational torque Ta measured in the post-press-fitting rotational torque measurement step (S05).

However, in this embodiment, the inner seal member attachment process (S10) is performed after the post-crimping rotational torque measurement process (S07). Therefore, when measuring the post-press-fit rotational torque Ta and the post-crimping rotational torque Tb of the wheel bearing device 1 in the post-press-fit rotational torque measurement process (S05) and the post-crimping rotational torque measurement process (S07), there is no variation in the rotational torque due to the influence of the inner seal member 9, and it is possible to measure the rotational torque of the wheel bearing device 1 with high accuracy.

In this embodiment, the inner seal member attachment process (S10) is performed after the post-crimping rotational torque measurement process (S07), but the cap member attachment process can also be performed after the post-crimping rotational torque measurement process (S07). In this case, in the cap member attachment process, a cap member is fitted into the inner opening 2a of the outer ring 2 instead of the inner seal member 9, and the inner opening 2a is closed by the cap member.

In this embodiment, the wheel bearing device 1 for a driven wheel is described, but this preload inspection method can also be applied to a wheel bearing device for a driving wheel that has a hub wheel that is crimped.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, which are merely examples, and it goes without saying that the present invention can be embodied in various other forms without departing from the spirit of the present invention. The scope of the present invention is indicated by the claims, and further includes the equivalent meanings set forth in the claims, and all modifications within the scope of the claims.

REFERENCE SIGNS LIST 1 Wheel bearing device 2 Outer ring 2c (inner side) outer raceway surface 2d (outer side) outer raceway surface 3 Hub ring 3a Small diameter step portion 3c Inner raceway surface 4 Inner ring 4a Inner raceway surface 5 Inner side ball row 6 Outer side ball row 7 Ball 9 Inner side seal member P1 First bearing preload value P2 Second bearing preload value S02 Press-fitting process S03 First bearing preload value calculation process S04 Break-in process S05 Post-press-fit rotational torque measurement process S06 Crimping process S07 Post-crimping rotational torque measurement process S08 Second bearing preload value calculation process S09 Judgment process Ta Post-press-fit rotational torque Tb Post-crimping rotational torque ΔT Differential torque ΔP Preload change amount

Claims (4)

an outer member having a double row outer raceway surface on an inner periphery thereof;
an inner member including a hub ring having an axially extending small diameter step on an outer periphery thereof and an inner ring press-fitted into the small diameter step of the hub ring, the inner member having a double row inner raceway surface facing the double row outer raceway surfaces;
a double row of rolling elements rollably accommodated between the raceway surfaces of the outer member and the inner member;
A method for inspecting a preload of a wheel bearing device comprising:
a press-fitting step of press-fitting the inner ring into the small diameter step portion of the hub wheel in an axial direction to a position where the inner ring abuts against the hub wheel;
a first bearing preload value calculation step of calculating a first bearing preload value of the wheel bearing device based on the axial negative clearances between the two raceway surfaces and the rolling elements after the press-fitting step;
a post-press-fit rotational torque measuring step of measuring a post-press-fit rotational torque of the wheel bearing device when the inner member and the outer member are rotated relative to each other after the press-fitting step;
a crimping step of crimping an inner side end portion of the small diameter step portion to the inner ring after the post-press-fit rotational torque measuring step;
a post-crimping rotational torque measuring step of measuring a post-crimping rotational torque of the wheel bearing device when the inner member and the outer member are rotated relative to each other after the crimping step;
a second bearing preload value calculation step of calculating a second bearing preload value by adding a preload change amount between after the press-fitting step and after the swaging step, the change amount being calculated based on a torque difference between the post-press-fitting rotational torque and the post-swaging rotational torque, to the first bearing preload value;
a judgment process for judging the suitability of the preload applied to the wheel bearing device based on whether or not the second bearing preload value is within a range of reference values. The preload inspection method for wheel bearing devices according to claim 1, wherein the reference value is set taking into consideration the variation in rotational torque caused by tightening the small diameter step to the inner ring. The preload inspection method for a wheel bearing device according to claim 1 or 2, wherein in the post-press-fit rotational torque measurement process and the post-swage rotational torque measurement process, the inner member and the outer member are rotated relative to each other at a rotational speed of 10 rpm to 30 rpm, respectively, to measure the post-press-fit rotational torque and the post-swage rotational torque. Grease is filled between the hub wheel and the outer member,
4. The preload inspection method for a wheel bearing device according to claim 1, further comprising a running-in process, which is carried out at least between the pressing-in process and the post-press-in rotational torque measurement process, and which rotates the inner member and the outer member relatively to one another to make the grease familiar to the rolling elements.

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