JP2010066189A - Method for measuring preload of double-row rolling bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method for measuring a preload that can obviate the need of checking a relationship between a physical amount to be measured and a preload beforehand, and can be applied to a completed product. <P>SOLUTION: In the method for measuring a preload, while measuring the rotational torque of a hub unit for supporting a wheel, a radial load F<SB>1</SB>applied to the hub unit for supporting the wheel is gradually increased. At the moment when a phenomenon in which the magnitude of the rotational torque is abruptly lowered occurs, a value of a load rate ε at that moment in relation to a ball row of which the number of balls 3 existing in a load zone is considered to be reduced is determined to be 1. In addition to this , a radial load F<SB>r</SB>applied to the ball row at that moment is obtained. A preload is obtained on the basis of the determined load rate ε=1, the radial load F<SB>r</SB>and a specification relating to the ball row. Accordingly, it is not necessary to check the relationship beforehand so that cost for measuring the preload can be suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is used to confirm whether or not an appropriate preload is applied to a double row rolling bearing device to which a preload is applied.

  The wheels of the automobile are rotatably supported by the suspension device by a wheel support hub unit, which is a kind of double row rolling bearing device. FIG. 4 shows a conventional wheel supporting hub unit for a driven wheel as a first example. The wheel support hub unit includes an outer ring 1 that is an outer ring member, a hub 2 that is an inner ring member, and a plurality of balls 3 and 3 each of which is a rolling element. Of these, the outer ring 1 is formed with a stationary flange 4 on the outer peripheral surface for coupling and fixing to a knuckle constituting the suspension device, and first and second outer ring raceways 5a and 5b on the inner peripheral surface, respectively. Yes.

  The hub 2 is formed by combining a hub body 6 and an inner ring 7. Of these, the outer end of the hub body 6 in the axial direction is the outer end in the axial direction (“outer” in the axial direction means the outer side in the width direction of the vehicle when assembled to the automobile, and the left side in FIG. ”Refers to the center in the width direction of the vehicle, and is the right side of FIG. 4. This is the same throughout the present specification.) The rotation side flange 8 for supporting the wheel is located closer to the first portion in the middle in the axial direction. The inner ring raceway 9a is also formed with a small-diameter step portion 10 having an outer diameter smaller than that of the portion where the first inner ring raceway 9a is formed at the inner end portion in the axial direction. The inner ring 7 is externally fitted to the small-diameter step portion 10 by press-fitting (with an interference fit). A second inner ring raceway 9 b is formed on the outer peripheral surface of such an inner ring 7.

  The balls 3 and 3 are arranged in a plurality between the first and second outer ring raceways 5a and 5b and the first and second inner ring raceways 9a and 9b. It is provided so that it can roll freely. In this state, the inner ring 7 is present at the proximal end portion of the small-diameter step portion 10 by the caulking portion 11 formed by plastically deforming the axially inner end portion of the hub body 6 radially outward. It is suppressed toward the step surface 12. In this state, a predetermined preload is applied to the balls 3 and 3 in each row together with the contact angles α and α of the rear combination type. Further, both end openings of the space in which the balls 3 and 3 are installed are closed by seal rings 13a and 13b, respectively. In the case of a hub unit for supporting a wheel of an automobile that is heavy, tapered rollers may be used in place of the balls 3 and 3 described above.

  Next, FIG. 5 shows a driven wheel as a second example of a conventionally known wheel supporting hub unit. In the case of this example, unlike the case of the first example described above, an inner ring member provided on the inner diameter side of the hub 2a is provided with a rotation side flange 8 for supporting and fixing the wheel to the hub 2a which is an outer ring member. A stationary side flange 4 for coupling and fixing to a knuckle constituting a suspension device is formed on each shaft member 14. The structure and operation of other parts are basically the same as in the case of the first example described above, although there are differences such as the inner ring 7 and the caulking part 11 being arranged on the outer end side in the axial direction. Equivalent parts are denoted by the same reference numerals, and redundant description is omitted.

  Next, FIG. 6 shows a drive wheel for a third example of a conventionally known wheel support hub unit. In the case of this example, a spline hole 15 for engaging a spline shaft as a drive shaft is provided at the center of the hub body 6a constituting the hub 2b. The structure and operation of the other parts are the same as in the case of the first example shown in FIG.

  By the way, in the case of each wheel supporting hub unit as described above, if the preload (preload gap) applied to the balls 3 and 3 in each row is not within an appropriate value, the life of each wheel supporting hub unit is shortened. Or the dynamic torque (rotational resistance) of each of the wheel supporting hub units increases, leading to problems such as a decrease in the running performance of the automobile. For this reason, strict management is required for the preload.

On the other hand, various preload measurement methods have been conventionally proposed in order to perform such management. For example, Patent Document 1 describes a method of measuring a resonance frequency of a bearing device and obtaining a preload based on the resonance frequency. Patent Document 2 describes a method of measuring the amplitude of vibration transmitted between the inner and outer rings and obtaining a preload based on this amplitude. Patent Document 3 describes a method of measuring an axial relative displacement between inner and outer rings caused by applying an axial load to the bearing device, and obtaining a preload based on the axial relative displacement. However, in the case of the conventional methods described in these Patent Documents 1 to 3, for each type of bearing device, the relationship between the physical quantity to be measured (resonance frequency, amplitude of vibration, axial relative displacement) and preload, It is necessary to check in advance using a reference bearing device (master) that has been accurately adjusted for preload by some method (for example, knowing preload by starting torque), and preparation work for preload measurement is cumbersome and costly. . Patent Document 4 describes a conventional method called a temporary press-fitting difference width method, and Patent Document 5 describes a conventional method called a set height method. However, in the case of the conventional methods described in these Patent Documents 4 to 5, it cannot be applied to the finished product of the bearing device, and it is necessary to measure the axial gap and the dimension between members during the assembly of the bearing. There is a problem of lowering the productivity of the bearing.
In addition, there exist the following nonpatent literatures 1-2 as another well-known literature relevant to this invention.

Japanese Patent No. 3551033 JP-A-2-159536 US Pat. No. 5,763772 Japanese Patent No. 2866282 Japanese Patent No. 3174759 “Technical Report”, NSK Ltd., 2004 edition (1991 first edition), p. 96,102,110-112,170 Okamoto Junzo, "Dynamic load capacity of rolling bearings and roller bearings-Detailed explanation of LUNDBERG PALMGREN theory-", Shobunsha Co., Ltd., March 1990, p. 61-62

  The preload measuring method of the double row rolling bearing device according to the present invention realizes a method that can be applied to a finished product without considering the relationship between the physical quantity to be measured and the preload in advance in view of the circumstances as described above. Invented as much as possible.

The double-row rolling bearing device to be subjected to the preload measuring method of the present invention includes an outer ring member having a double-row outer ring raceway on an inner peripheral surface, an inner ring member having a double-row inner ring raceway on an outer peripheral surface, and both outer ring raceways. And a plurality of rolling elements such as balls, tapered rollers, and the like, which are provided so as to be capable of rolling in a state where a preload is applied.
The preload measuring method of the present invention for such a double-row rolling bearing device starts to apply a radial load to the double-row rolling bearing device, and gradually increases the radial load while increasing the radial load. Measuring device torque {starting torque (rotational resistance when starting relative rotation of the outer ring member and inner ring member) or rotational torque (rotational resistance when the outer ring member and inner ring member are rotating relative to each other)} This operation is performed at least until the phenomenon that the measured torque suddenly drops occurs. Of the pair of rolling element rows constituting the double row rolling bearing device, the number of rolling elements (rolling elements that support the load) existing in the load zone at the moment when the phenomenon of a sudden drop in the torque occurs. The value of the instantaneous load factor ε for one of the rolling element rows considered to have decreased is determined to be 1 (ε = 1). At the same time, the radial load F _r applied to any one of the rolling element rows is obtained at the moment when the phenomenon that the torque suddenly drops occurs. Thereafter, the determined load factor ε = 1, the obtained radial load F _r, and the specifications relating to any one of the rolling element rows {the diameter of each rolling element, the number of each rolling element, the contact of each rolling element The preload is calculated based on the angle, the radius R of the raceway (the radius of curvature of the race with respect to the virtual plane including the central axis of the double row rolling bearing device, the elastic modulus of the material constituting each member, etc.). .
That is, as described below, it is well known that the relationship between the axial load (= preload), radial load, and load factor for rolling bearings is determined by Lundberg and Palmrgen. Is used to calculate the preload.

この様な場合、負荷率εの値は１以上（ε≧１）になる。 Next, the principle of the preload measuring method of the double row rolling bearing device of the present invention as described above will be described in detail with reference to FIGS.
First, as shown in FIGS. 7A, 7B, and 7C, a single row rolling bearing with a contact angle α, that is, an outer ring 20 having an outer ring raceway 19 on an inner peripheral surface, and an inner ring raceway 21 on an outer peripheral surface. A single-row rolling bearing provided with an inner ring 22 having a plurality of rolling elements 23 and 23 provided between the outer ring raceway 19 and the inner ring raceway 21 so as to be capable of rolling with a contact angle α. Consider the case where the radial load F _r and the axial load F _a act on (the example shown is a single-row angular ball bearing, but it may be a single-row tapered roller bearing or the like). Width of the load zone of the single row rolling bearing is changed by the ratio of these radial load F _r and axial load F _a. The size of such a load sphere is, for example, p. As described in 110, it is represented by a load factor ε. Specifically, as shown in FIGS. 7B and 7C, when the load zone exists only in a part in the circumferential direction, the load factor ε is the diameter D of the inner ring raceway 21 and the projected length of the load zone. It is represented by the ratio (εD / D = ε) to the depth εD. In such a case, the value of the load factor ε is 1 or less (ε ≦ 1). On the other hand, when the load zone exists over the entire circumference, the load factor ε depends on the total elastic displacement amount (displacement amount in the contact angle α direction) δ _{max of the} rolling element 23 that receives the maximum load and the rolling force that receives the minimum load. Using the total elastic displacement amount (displacement amount in the contact angle α direction) δ _{min of the} moving body 23, it is expressed by the following equation (* 1).

In such a case, the value of the load factor ε is 1 or more (ε ≧ 1).

On the other hand, FIG. 8 shows the relationship between the torque (starting torque or rotational torque) of the single row rolling bearing and the radial load F _r acting on the single row rolling bearing. As shown in FIG. 8, the torque repeats the behavior that it gradually drops by a certain amount after increasing gently in a certain section as the radial load F _r increases. The phenomenon in which the torque suddenly drops as described above is caused by a decrease in the number of rolling elements 23 existing in the load zone in the process in which the load zone decreases as the radial load F _r increases. For example, the preload is imparted {(the epsilon = ∞) of axial load F _a is acting} the single row rolling bearing, beginning to load the radial load F _r, gradually the radial load F _r Increasing (decreasing ε) causes a phenomenon in which the torque suddenly drops along the way. At the moment when such a phenomenon first occurs, the load area is present throughout the entire circumference. Is the moment when the value of the load factor ε falls below 1 (ε = 1).

ここで、
δ_max：最大荷重を受ける転動体２３の全弾性変位量（接触角α方向の変位量）
δ_r：外輪２０と内輪２２とのラジアル相対変位量（δ_r＝δ_max・cosα）
δ_a：外輪２０と内輪２２とのアキシアル相対変位量（δ_a＝δ_max・sinα）
α：転動体２３の接触角
△_r：ラジアル隙間
である。尚、本来、上記接触角αは、上記単列転がり軸受に作用するラジアル荷重Ｆ_rやアキシアル荷重Ｆ_aの大きさによって若干変化する。但し、ここでは単純化の為に、上記接触角αは一定とする。 When the single row rolling bearing is a ball bearing, the load factor ε is described in p. As described in Equation (4) at 112, the following relationship (★ 2) is established.

here,
δ _max : Total elastic displacement amount of the rolling element 23 receiving the maximum load (displacement amount in the contact angle α direction)
δ _r : radial relative displacement amount between outer ring 20 and inner ring 22 (δ _r = δ _max · cos α)
δ _a : Axial relative displacement between outer ring 20 and inner ring 22 (δ _a = δ _max · sin α)
α: Contact angle of the rolling element 23 Δ _r : Radial gap. Note that the contact angle α originally varies slightly depending on the magnitude of the radial load F _r and the axial load F _a acting on the single row rolling bearing. However, here, the contact angle α is constant for simplification.

ここで、
ｃ：Herlzの弾性定数（接触変形定数）
Ｑ_max：最大転動体荷重（接触角α方向の荷重）
Ｄ_w：転動体２３の直径
である。尚、上記ヘルツの弾性定数ｃは、例えば非特許文献２のｐ．６１−６２に記載されている様に、接触物体の縦弾性係数及びポアソン比と、接触物体の曲率の和（玉軸受の場合には、玉の直径、軌道の溝Ｒ半径、軌道の直径から求まる。円すいころ軸受の場合には、円すいころの直径、軌道の直径から求まる。）とから求まる。 Regarding the displacement amount δ _max in the above equation (★ 2), p. As described in Equation (6) at 112, the following relationship (★ 3) is established.

here,
c: Herlz elastic constant (contact deformation constant)
Q _max : Maximum rolling element load (contact angle α direction load)
D _w is the diameter of the rolling element 23. The Hertz elastic constant c is, for example, p. 61-62, the sum of the longitudinal elastic modulus and Poisson's ratio of the contact object and the curvature of the contact object (in the case of a ball bearing, the diameter of the ball, the radius R of the raceway, the diameter of the raceway) In the case of tapered roller bearings, it is obtained from the diameter of the tapered roller and the diameter of the raceway.)

ここで、
Ｆ_r：ラジアル荷重
Ｊ_r：ラジアル積分
Ｚ：転動体２３の個数
である。尚、上記ラジアル積分Ｊ_rの値は、上記負荷率εの値が決まれば、一義的に決まる（非特許文献１のｐ．１１１の表１参照）。例えば、この負荷率εの値が１（ε＝１）の場合に、上記ラジアル積分Ｊ_rの値は、０．２５４６（玉軸受の場合）、０．２５２３（円すいころ軸受の場合）となる。 Further, regarding the maximum rolling element load Q _max in the above formula (* 3), p. As described in Equation (7) at 112, the following relationship (★ 4) is established.

here,
F _r : radial load J _r : radial integral Z: the number of rolling elements 23. The value of the radial integral J _r is determined if the value of the load factor epsilon, uniquely determined (see Table 1 p.111 of Non-Patent Document 1). For example, when the value of the load factor ε is 1 (ε = 1), the radial integral J _r is 0.2546 (in the case of a ball bearing) and 0.2523 (in the case of a tapered roller bearing). .

ここで、
ｒ_e：外輪軌道１９の溝Ｒ半径
ｒ_i：内輪軌道２１の溝Ｒ半径
Ｄ_w：転動体２３の直径
である。 Further, the case the single row rolling bearing is a ball bearing, axial clearance △ _a of the single row rolling bearing, the non-patent document 1 p. 96 as (4) {or, regarding the double row ball bearing, p. 102, the same formula as (6) is described}, and the following formula (* 5) is used.

here,
r _e : groove R radius of the outer ring raceway r _i : groove R radius of the inner ring raceway D _w : diameter of the rolling element 23.

ここで、
Ｊ_a：アキシアル積分
Ｚ：転動体２３の個数
Ｑ_max：最大転動体荷重（接触角α方向の荷重）
α：転動体２３の接触角
である。尚、上記アキシアル積分Ｊ_aの値も、上記負荷率εの値が決まれば、一義的に決まる（非特許文献１のｐ．１１１の表１参照）。例えば、この負荷率εの値が１（ε＝１）の場合に、上記アキシアル積分Ｊ_aの値は、０．４２４４（玉軸受の場合）、０．４８１７（円すいころ軸受の場合）となる。 Moreover, the axial load F _a of the single-row rolling bearing, the non-patent document 1 p. As described in equation (3) in 110, the following equation (★ 6) is obtained.

here,
J _a : Axial integration Z: Number of rolling elements 23 Q _max : Maximum rolling element load (load in the contact angle α direction)
α: Contact angle of the rolling element 23. Note that the value of the axial integral J _a is also uniquely determined if the value of the load factor ε is determined (see Table 1 on page 111 of Non-Patent Document 1). For example, if the value of the load factor epsilon is 1 (epsilon = 1), the value of the axial integral J _a is (in the case of ball bearings) 0.4244, and 0.4817 (in the case of tapered roller bearings) .

Thus, a the single row rolling bearing is a ball bearing, and, If this preload to the single row rolling bearing has been given (acting axial load F _a is), the radial load F in the single row rolling bearing _If the operation of measuring the torque of the single row rolling bearing is started at least until the phenomenon that the measured torque suddenly drops occurs while starting to load _r and gradually increasing the radial load F _r , this phenomenon will occur. The value of the load factor ε of the single row rolling bearing at the moment of occurrence can be determined as 1 (ε = 1). At the same time, if the radial load F _r at the moment when the phenomenon occurs is obtained, the above-described load factor ε = 1, the obtained radial load F _r, and the specifications of the single row rolling bearing, The preload (axial load F _a ) can be calculated. Specifically, the formulas (* 2) to (* 4), the calculation formula related to the radial relative displacement amount δ _r (δ _r = δ _max · cos α), and the calculation formula related to the axial relative displacement amount δ _a. Using (δ _a = δ _max · sin α), the radial gap Δ _r in the above equation (* 2) can be calculated. Further, by using the calculation result of the radial clearance △ _r, from the (★ 5) equation, corresponding to the preload gap of the single row rolling bearing, it is possible to calculate the axial clearance △ _a. Furthermore, by using the calculation result of the axial clearance △ _a, from the (★ 6) equation, corresponding to the preload can be calculated axial load F _a.
Even when the single-row rolling bearing is a tapered roller bearing, if the relational expressions corresponding to the above formulas (* 2) to (* 5) are prepared, the ball bearing described above can be used. The preload gap (axial gap Δ _a ) and preload (axial load F _a ) can be calculated by the same method as in the case.

Here, each of the pair of rolling element rows constituting the double row rolling bearing device to be subjected to the preload measuring method of the present invention can be regarded as a physical system equivalent to the single row rolling bearing as described above. . Accordingly, as described above, at least the work of measuring the torque of the double row rolling bearing device while starting to apply a radial load to the target double row rolling bearing device and gradually increasing the radial load is performed. If the measured torque is suddenly lowered until the phenomenon occurs, the number of rolling elements existing in the load zone of the pair of rolling element rows constituting the double row rolling bearing device decreases at the moment when the phenomenon occurs. The value of the load factor ε at the moment when the above phenomenon occurs with respect to any one of the rolling element rows considered to be 1 can be determined as 1 (ε = 1). At the same time, when the radial load F _r loaded on any one of the rolling element rows is obtained at the moment when this phenomenon occurs, the determined load factor ε = 1, the obtained radial load F _r , based on the specifications or about one rolling element row, in the same manner as the case of the single row rolling bearing described above approach, this one of the rolling element row of the preload gap (axial clearance △ _a) and preload (axial load F _a ) {= preload gap (axial gap Δ _a ) and preload (axial load F _a )} of the double row rolling bearing device can be calculated. In the double row rolling bearing device, the sum of the axial loads applied to the rolling elements of both rows is equal to each other. Therefore, if the preload clearance and preload of one row are obtained, the preload clearance and preload of the other row are also obtained.

When carrying out such a preload measuring method for a double row rolling bearing device of the present invention, the load position of the radial load on the double row rolling bearing device is just the center position between a pair of rolling element rows in the axial direction. Is preferable. This is because the radial load F _r applied to both the rolling element rows is ½ each of the radial load applied to the double row rolling bearing device, and the radial load applied to both the rolling element rows. This is because _Fr can be easily obtained.

Further, when the rotational torque is measured as the torque when the preload measuring method of the double row rolling bearing device of the present invention as described above is carried out, the double row rolling when measuring the rotational torque is performed. It is preferable that the rotational speed of the bearing device (the relative rotational speed between the outer ring member and the inner ring member) be sufficiently small. This is because if the rotational speed is increased too much, changes in preload due to temperature rise and changes in the agitation resistance of lubricating grease become so large that they cannot be ignored, making it impossible to perform appropriate preload measurement. Therefore, specifically, for example, with respect to the target double-row rolling bearing device, the relationship between the rotational speed and the rotational torque as illustrated in FIG. 9 is experimentally obtained, or, for example, non-patent literature P. It is theoretically obtained by the equation (10) described in 170. Then, the rotational speed of the double row rolling bearing device at the time of measuring the rotational torque is set to be equal to or lower than the rotational speed corresponding to the minimum value of the curve representing the relationship. Alternatively, without obtaining such a curve, the rotational speed of the double-row rolling bearing device at the time of measuring the rotational torque is simply suppressed sufficiently small (for example, 10 min ⁻¹ or less).

  In the case of the preload measuring method of the double row rolling bearing device of the present invention as described above, it is not necessary to examine in advance the relationship between the physical quantity (torque, radial load) to be measured and the preload (preload gap). For this reason, the cost of the preload measurement can be suppressed, and the present invention can be applied to a double row rolling bearing device in which the torque is changed by use over a long period of time (for example, due to raceway surface roughness or seal wear). Moreover, since it can implement with respect to the finished product of a double row rolling bearing apparatus, it can prevent that the productivity of this double row rolling bearing apparatus falls.

[First example of embodiment]
1 and 2 show a first example of an embodiment of the present invention. Note that the structure of the wheel support hub unit that is the subject of the preload measurement in this example is substantially the same as the structure of the wheel support hub unit shown in FIG. For this reason, the same reference numerals are assigned to the equivalent parts, and overlapping explanations are omitted or simplified, and the following description will focus on the preload measurement method that is a feature of this example. In the case of this example, in order to measure the preload applied to the balls 3 and 3 constituting the wheel support hub unit, first, as shown in FIG. Set to. This measuring device includes a rotation driving means (not shown), a static pressure pad 16, and a torque measuring device 17. Of these, the rotational drive means can rotate the hub 2 while preventing displacement of the hub 2 in the axial direction and radial direction. Further, the static pressure pad 16 has a portion in the circumferential direction of the outer peripheral surface of the outer ring 1 (cylindrical smooth surface with which a shoe is slidably contacted when the outer ring raceways 5a and 5b are ground) not interposed via a static pressure fluid. The radial load F ₁ can be freely applied to the wheel support hub unit by pressing against the contact. In particular, in the case of this example, the pressing position of the hydrostatic pad 16 against the outer peripheral surface of the outer ring 1 (the load position of the radial load F ₁ ) is just the center between a pair of ball rows in the axial direction. The position. Thus, these two ball rows, and the radial load F _r each the same size (= F _1/2) the manner can be loaded. The torque measuring device 17 can measure the tangential force of the outer ring 1 that tends to be rotated when the hub 2 rotates as the rotational torque of the wheel supporting hub unit.

When the wheel supporting hub unit is set in the measuring device as described above, the torque measuring device 17 then rotates the hub 2 at a constant rotational speed of 10 min ⁻¹ or less by the rotational driving means. Then, the rotational torque of the wheel supporting hub unit is measured. Then, while measuring the torque in this way, by the static pressure pad 16, with starts a radial load F ₁ in the wheel supporting hub unit, gradually increases the radial load F _1. As described above, when the radial load F ₁ is gradually increased, the rotational torque is gradually increased. However, when the radial load F ₁ becomes a certain magnitude, a phenomenon occurs in which the magnitude of the rotational torque suddenly drops as shown in FIG. In the case of this example, after this phenomenon occurs, the operation for measuring the rotational torque is immediately terminated.

By the way, the phenomenon as shown in the measurement result of FIG. 2, that is, the phenomenon that the magnitude of the rotational torque suddenly drops, decreases the load area of the both ball arrays as the radial load F ₁ increases. This is because the number of balls 3 existing in the load zone of at least one of the ball rows is reduced in the process. In particular, in the case of this example, the above-mentioned two rows of balls, the specifications (the diameter D _w of each of the balls 3, 3, the pitch circle diameter PCD of each of the balls 3, 3, the number of these balls 3, 3 , contact angle alpha, the outer ring raceway 5a, the groove R the radius r _e of 5b, the inner ring raceway 9a, 9b groove R the radius r _i, etc.) are the same as each other, and radial load F _r also identical to each other (F, which is loaded It is _1/2). Therefore, in the case of this example, the phenomenon that the magnitude of the rotational torque suddenly drops is considered to be caused by the fact that the number of balls 3 existing in the load sphere of the both ball rows simultaneously decreases in both the ball rows. I can do things.

Therefore, in the case of this example, the value of the load factor ε at the moment when the phenomenon in which the magnitude of the rotational torque suddenly drops occurs with respect to either one of the above-described two rows (whichever is sufficient). Is determined to be 1 (ε = 1). At the same time, the measurement results of FIG. 2, obtaining the radial load F _r which has the loaded into one of the ball row at the moment when the phenomenon occurs (F _1/2). Then, based on the determined load factor ε = 1, the obtained radial load F _r, and the specifications relating to any one of the above-mentioned ball rows, a preload gap (= the other ball row) relating to any one of the ball rows. Preload gap) for Specifically, the (★ 2) formula ~ (★ 4) equation, as well as, the radial relative displacement [delta] _r about formulas _{(δ r = δ max · cosα} ) and the axial relative displacement amount [delta] _a related formula Using (δ _a = δ _max · sin α), the radial gap Δ _r in the above equation (★ 2) is calculated. Then, by using the calculation result of the radial clearance △ _r, from the (★ 5) formula, equivalent to the preload gap, calculates the axial clearance △ _a. Furthermore, by using the calculation result of the axial clearance △ _a, the (★ 6) from the equation, the one of the preload being applied to the balls 3, 3 constituting the ball row (= the other of the ball The axial load F _a corresponding to the preload applied to each ball 3, 3 constituting the row is calculated. Note that such calculation processing of the preload gap (axial gap Δ _a ) and preload (axial load F _a ) can be performed by a calculator (not shown).

In the case of the preload measuring method of the double row rolling bearing device of the present example as described above, it is necessary to examine in advance the relationship between the physical quantity to be measured (rotational torque, radial load F _r ) and the preload (preload gap). Absent. For this reason, the cost of preload measurement can be suppressed. Moreover, since it can implement with respect to the finished product of a double row rolling bearing apparatus, it can prevent that the productivity of this double row rolling bearing apparatus falls.

  In the first example described above, the pressing position of the static pressure pad 16 against the outer peripheral surface of the outer ring 1 is just the center position between a pair of ball rows in the axial direction. However, depending on the target wheel support bearing unit, the pressing position of the static pressure pad 16 against the outer circumferential surface of the outer ring is close to the ball array on the outer side in the axial direction in relation to the shape of the outer circumferential surface of the outer ring. There is a case where it must be. In this case, a larger radial load is applied to the ball train on the outer side in the axial direction than the ball train on the inner side in the axial direction. For this reason, at the moment when the phenomenon that the magnitude of the rotational torque suddenly drops first occurs, the number of balls 3 existing in the load zone is reduced not in the axially inner ball row but in the axially outer ball row. The subsequent preload calculation may be performed assuming that the value of the load factor ε is less than 1.

[Second Example of Embodiment]
FIG. 3 shows a second example of the embodiment of the present invention. In the case of this example, the way of applying the radial load F ₁ to the wheel supporting hub unit is different from that of the first example described above. That is, in the case of this example, a drum 18 having an L-shaped cross section and formed in an annular shape is fixedly coupled to the stationary flange 4 of the outer ring 1 by a coupling member such as a bolt (not shown). Then, a radial load F ₁ is applied to the wheel support hub unit by pressing a part of the outer peripheral surface (cylindrical smooth surface) of the drum 18 in the circumferential direction with the static pressure pad 16 in a non-contact manner. Yes. Also in this example, the pressing position of the static pressure pad 16 against the outer peripheral surface of the drum 18 (the load position of the radial load F ₁ ) is just the center position between a pair of ball rows in the axial direction. It is said. Thus, these two ball rows, and the radial load F _r each the same size (= F _1/2) the manner can be loaded. In the case of this example, the torque measuring device 17 measures the tangential force of the drum 18 that is rotated with the outer ring 1 as the hub 2 rotates as the rotational torque of the wheel supporting hub unit. In this example, since the outer peripheral surface of the drum 18 is the pressed surface of the static pressure pad 16, the pressing position of the static pressure pad is set regardless of the shape of the outer peripheral surface of the outer ring 1. The center position between the pair of ball rows in the axial direction can be easily set to the center position. Other configurations and operations are the same as those of the first example described above.

  The method for measuring the preload of the double row rolling bearing device of the present invention is not limited to the wheel supporting hub unit shown in FIGS. 1, 3, and 4. For example, the wheel supporting hub unit shown in FIGS. It can be implemented for various types of double-row rolling bearing devices that satisfy the requirements described in the claims, such as a double-row rolling bearing, a combined bearing, and the like that are preloaded and used.

Sectional drawing which shows the 1st example of embodiment of this invention. The diagram which shows the relationship between the radial load loaded on the hub unit for wheel support, and the rotational torque of this hub unit for wheel support. Sectional drawing which shows the 2nd example of embodiment of this invention. Sectional drawing which shows the 1st example of the hub unit for wheel support conventionally known. Sectional drawing which shows the 2nd example. Sectional drawing which shows the 3rd example. It is a figure for demonstrating the breadth of the load zone in case a radial load and an axial load act on the single row rolling bearing of contact angle (alpha), (A) is sectional drawing of the said single row rolling bearing, (B) is The figure which looked at the outer peripheral surface of the inner ring from the axial direction, (C) is the figure which looked at the inner ring from the radial direction. The diagram which shows the relationship between the radial load which acts on a single row rolling bearing, and the torque (starting torque or rotational torque) of this single row rolling bearing. The diagram which shows the relationship between the rotational speed of a rolling bearing, and rotational torque.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2, 2a, 2b Hub 3 Ball 4 Stationary side flange 5a, 5b Outer ring raceway 6, 6a Hub body 7 Inner ring 8 Rotation side flange 9a, 9b Inner ring raceway 10 Small diameter step portion 11 Caulking portion 12 Step surface 13a, 13b Seal ring 14 Shaft member 15 Spline hole 16 Static pressure pad 17 Torque measuring device 18 Drum 19 Outer ring raceway 20 Outer ring 21 Inner ring raceway 22 Inner ring 23 Rolling element

Claims (1)

Preload is applied between the outer ring member having a double row outer ring raceway on the inner peripheral surface, the inner ring member having a double row inner ring raceway on the outer peripheral surface, and between each of these outer ring raceways and both inner ring raceways. A method for measuring a preload of a double row rolling bearing device including a rolling element provided so as to be freely rollable in a state where the radial load is applied to the double row rolling bearing device and gradually starting to apply the radial load to the double row rolling bearing device. The torque of the double row rolling bearing device is measured at least until the phenomenon of a sudden drop in the measured torque occurs, and among the pair of rolling element rows constituting the double row rolling bearing device, Thus, the value of the load factor ε at the moment when the above phenomenon occurs is determined to be 1 with respect to any one of the rolling element rows considered to have decreased in the number of rolling elements existing in the load zone at the moment when this phenomenon occurs. With After determining the radial load F _r This behavior is the load in one of the rolling element row at the moment generated, the radial load F _r which load factor epsilon = 1 and obtained by these determined, whereas the one A preload measurement method for a double row rolling bearing device, characterized in that the preload is calculated based on specifications relating to the rolling element train of the first embodiment.

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