JP4650510B2 - Prediction method of abnormal noise by fretting - Google Patents

Description

  The present invention predicts the presence or absence and occurrence location of fretting phenomena that occur when relative fine movement is repeated between two contacting surfaces, and predicts the occurrence of abnormal noise due to fretting. It relates to the prediction method.

Conventionally, in order to evaluate fretting, a pressing piece that presses a test piece in a horizontal direction perpendicular to the axis thereof and an actuator that axially displaces the test piece supported by the pressing piece so as to be able to slide in the axial direction. An equipped fretting fatigue test apparatus is used (Patent Document 1).
JP-A-8-219964

  Evaluation by the fretting fatigue test equipment has a limitation on the shape of the test piece and also requires a long test period, and instead of this, it is desired to predict fretting. The situation was that it was considered impossible and there was no choice but to test.

  For example, in a hub unit used in a vehicle, since the ground contact load applied to the tire changes, it is a condition that fretting is likely to occur between the hub unit and a member in contact with the hub unit. A method is desired.

  Moreover, it is even more difficult to predict abnormal noise (stick slip) due to fretting on a desk, and it has not been considered at all to predict the occurrence of this abnormal noise.

  The object of the present invention is to predict the occurrence location of fretting, and therefore, when the specifications of the shape, thickness, material, etc. of the target member are changed, the quality of the fretting resistance of each specification can be determined. In addition, an object of the present invention is to provide a method for predicting the occurrence of abnormal noise by fretting, which can also predict the amount of fretting and thereby determine whether or not abnormal noise has occurred due to fretting.

  The method for predicting the occurrence of abnormal noise due to fretting according to the present invention is a method for predicting the occurrence of abnormal noise due to fretting that occurs on the contact surface between two members whose contact conditions fluctuate. The distribution is derived by analysis, the effective contact surface is identified from this contact surface pressure fluctuation distribution, the average surface pressure and the slip amount in the effective contact surface are derived by analysis, and using these, the effective work amount = the effective contact area X average surface pressure x slip amount x friction coefficient is obtained, and abnormal noise generation due to fretting is predicted from the effective work amount.

  Fretting occurs in the contact surfaces of two members that are in contact with each other, where the contact state changes, that is, where the contact state changes, that is, where the contact state always moves away from the contact surface. Does not occur. Focusing on this point, the surface pressure distribution at the location where the contact state changes under the use condition is defined as the effective contact surface pressure distribution, and fretting is predicted as follows.

1. Using an appropriate analysis method (for example, finite element method = theoretical analysis such as FEM analysis or experimental analysis), the load condition is changed and the contact surface pressure distribution of the target member is obtained for a plurality of load conditions.

2. The effective contact surface pressure distribution is obtained by excluding locations that are always apart and locations that are always in contact for all load conditions.

  When the effective contact surface pressure distribution obtained as described above is compared with the actual fretting for the member where fretting has occurred, the fretting is in good agreement. The effectiveness of preventive measures can be evaluated, leading to shortened product development time and improved design quality.

  In the above fretting prediction, the contact surface pressure fluctuation distribution due to contact condition fluctuation is derived by analysis, the effective contact surface is identified from the contact surface pressure fluctuation distribution, and the average surface pressure and slip amount in the effective contact surface are analyzed. Using these, the effective work amount = effective contact area × average contact pressure × slip amount × friction coefficient is obtained. When the effective work amount is relatively large, fretting is likely to occur and the effective work amount is relative. If it is small, it is possible to predict that fretting is unlikely to occur, and this enables prediction with higher accuracy.

  The fretting occurrence prediction method can be applied to a method for predicting the occurrence of abnormal noise due to fretting occurring on the contact surface between two members whose contact conditions fluctuate. In this case, the “effective work amount” is obtained. Is preferred.

  The effective work amount is a value obtained by integrating the work amount of the frictional force in all the load directions within the effective contact region, and the time until the occurrence of abnormal noise obtained from the test results and this effective work amount have a high correlation. Have. In addition, since the time until abnormal noise generation correlates with the load repetition number until abnormal noise generation, the effective work amount has a high correlation with the load repetition number.

  In the above method for predicting the occurrence of abnormal noise due to fretting, the analysis method is not limited to FEM. However, when the target member has a three-dimensional shape, contact is made by FEM analysis in that the condition can be easily changed. It is more preferable to obtain the surface pressure.

  In addition, the target member is not limited at all. However, as a preferable application example, the wheel and the wheel mounting flange of the hub unit to which the wheel is mounted, the wheel mounted on the flange, and the space between the wheel mounting flange and the wheel are preferable. It is mentioned that at least one of the brake rotors arranged in the above is a target member. At the wheel mounting part of the hub unit, the load change is large, the contact surface pressure is zero under certain load conditions, and the contact surface pressure is positive under other load conditions, which is likely to cause fretting. ing. Therefore, when used for a long time, there is a concern about generation of abnormal noise due to fretting. Therefore, by applying the abnormal sound generation prediction method by fretting to this portion, it becomes easy to design an appropriate hub unit and wheels.

  Also, since various bearings are used under conditions where the load changes like the hub unit, fretting is likely to occur. The fretting resistance can be improved and the occurrence of abnormal noise can be prevented.

  According to the method for predicting abnormal noise by fretting according to the present invention, the time until the occurrence of abnormal noise obtained from the test results and this effective work have a high correlation and can be used as a criterion for the occurrence of abnormal noise. .

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a hub unit as an example to which the method for predicting the occurrence of abnormal noise by fretting according to the present invention is applied. In the following description, the left and right refer to the left and right in FIG. The left side is the outside of the vehicle and the right side is the inside of the vehicle.

  The hub unit (1) includes a wheel side track member (4) to which a wheel (2) is attached, a vehicle body side track member (5) fixed to the vehicle body (3) side, and both track members (4) (5 ) Have two rows of rolling elements (6) arranged between them.

  The wheel-side track member (4) includes a hollow hub wheel (11) and an inner ring member (12) that is fitted to the outer diameter of the right end portion of the hub wheel (11). Near the left end of the hub wheel (11), a wheel mounting flange (13) is provided. An inner ring raceway (11a) is formed on the outer diameter portion of the hub wheel (11) between the wheel mounting flange (13) and the inner ring member (12), and the inner ring member (12) An inner ring raceway (12a) is formed in parallel with the raceway (11a). The wheel mounting flange (13) of the hub wheel (11) has a plurality of (5) bolts (14) to which the wheel (2) is mounted, and the brake rotor (15) of the disc brake device is attached here. It has been.

  The vehicle body side raceway member (5) has an outer ring (fixed ring) function of a bearing, a cylindrical part (16) in which two rows of outer ring raceways (16a) are formed on the inner peripheral surface, and a cylinder A flange portion (17) which is provided at a right end portion of the portion (16) and is attached to a suspension device (vehicle body) (3) with a bolt (not shown). The flange portion (17) is provided with a bolt insertion hole (not shown).

  The two rows of rolling elements (6) are respectively held between the raceways (11a), (12a) and (16a) of the raceway members (4) and (5) while being held by the cage (18). A seal device (19) is provided between the left end portion of the vehicle body side track member (5) and the hub wheel (11) and between the right end portion of the vehicle body side track member (5) and the right end portion of the inner ring member (12). (20) is provided.

  The hub unit (1) is of a type used on the drive wheel side of an automobile and is connected to a constant velocity joint (7). The constant velocity joint (7) includes a shaft portion (21) fitted and fixed in the hub wheel (11), a concave spherical outer ring (22) connected to the right end portion of the shaft portion (21), and An inner ring (23) fixed to a drive shaft (26) facing the outer ring (22) and attached to a differential device (not shown) and a ball (24) disposed between both wheels (22) (23) ) And a cage (25).

  The wheel mounting flange (13) of the hub wheel (11), the brake rotor (15) of the disc brake device, and the wheel (2) are connected by a common bolt (14). The load applied to the vehicle via the vehicle (not shown), and the force received by the coupling portion varies greatly between a portion close to the ground contact position and a portion far from the ground contact position. Therefore, fretting that occurs when relative fine movement is repeated between two contacting surfaces is likely to occur.

  FIG. 2 shows a result obtained by applying the fretting occurrence prediction method to the coupling portion of the hub unit. This result was obtained as follows.

1. The wheel mounting flange (13), brake rotor (15), wheel (2), and bolt (14) are each divided into elements and subjected to FEM analysis, and the contact surface between each member (13) (15) (2) Find the pressure. As load conditions, for example, when the ground load acts as a concentrated load on the central portion of the bolt (14), and when the ground load acts as a concentrated load on the intermediate portion between the bolt (14) and the bolt (14). Calculated for multiple load conditions.

2. The contact surface pressure at the location where the contact state changes when the direction of the load changes is defined as the effective contact surface pressure, and the effective contact surface pressure is obtained for each element to create a distribution diagram. According to the FEM analysis, the contact surface pressure (contact surface pressure at a plurality of positions) within a predetermined range in the member under a predetermined load condition can be easily obtained.

  Fig. 2 shows the effective contact pressure distribution when the wheel mounting flange (13) is viewed from the wheel (2) side. In Fig. 2, the hatched portion (F) is the central portion of the bolt (14) (wheel mounting). In the flange (13), when a load (concentrated load of grounding load) is sequentially applied to the middle part of the bolt insertion hole (13a) and the middle part of the bolt (14) and bolt (14), the flange (13) is separated. (The contact surface pressure is zero) and the part that contacts (the contact surface pressure is positive), and other parts do not become zero even if the contact surface pressure fluctuates (for example, the bolt tightening part Neighboring (B)) or where the contact surface pressure is always zero (part (W) facing the recess of the wheel). The output of the effective contact surface pressure is displayed in color (not shown), and the magnitude of the contact surface pressure change can also be visually determined. This result almost coincides with the occurrence of fretting in the actual wheel mounting flange (13) when the test time is 100 hours.

  In addition, an analysis was performed on a model in which the thickness and shape of the wheel mounting flange (13) were changed. As a result, the effective contact surface pressure distribution changed, and this tendency was consistent with the tendency of fretting experimental results.

  Next, FEM analysis was performed with 20 radial load directions, and the load direction was sequentially changed as indicated by the arrows in FIG. 3, and not only the effective contact area but also the average surface pressure and the effective work amount. Asked. Here, effective work = nodal friction force in effective contact area × relative sliding amount integrated for all nodes under all load conditions, however, nodal friction force in effective contact area = effective contact surface pressure × effective contact area X Coefficient of friction. In FIG. 3, hatched portions are effective contact surfaces obtained by sequentially applying loads in the directions indicated by arrows (concentrated loads of grounding loads). It is hatched.

  For a plurality of models with different noise generation times due to fretting caused by repeated load changes, the test results and the analysis results are considered, and the effective contact area, the average surface pressure, and the effective work amount differ from each other. The relationship between the sound generation time and the effective contact area / average surface pressure was low, but the correlation between the effective work volume and the noise generation time was very high. .

  In other words, the effective work amount is the work amount caused by the frictional force between the wheel mounting flange (13) of the hub unit and the brake rotor (15) when the hub unit bearing makes one rotation, and includes the effective contact area, Information on effective contact surface pressure and relative slip is included. This effective work amount is in good agreement with the test result (abnormal noise generation time or the total number of rotations of the bearing until the occurrence of the abnormal noise), and it can be seen that it becomes a criterion for the generation of abnormal noise. Therefore, by changing the shape of the wheel mounting flange (13) and wheel (2) on the desk and performing the above analysis, the wheel mounting flange (13) and wheel (2) are better suited to improve the generation of abnormal noise. It is also possible to obtain the shape of

  In the above description, the hub unit is a target member. However, the noise generation prediction method according to the present invention can be applied to a rolling bearing other than the hub unit and various devices other than the rolling bearing.

It is a longitudinal cross-sectional view which shows the hub unit as an example to which the abnormal sound generation | occurrence | production prediction method by fretting by this invention is applied. It is a figure which shows an example of a fretting generation | occurrence | production prediction result. It is a longitudinal cross-sectional view which shows an example of the result of the abnormal sound generation | occurrence | production prediction method by fretting by this invention.

Explanation of symbols

(1) Hub unit
(2) Wheel
(11) Hub wheel
(13) Flange
(14) Bolt
(15) Brake rotor

Claims (3)

A method for predicting the occurrence of abnormal noise caused by fretting on the contact surface between two members whose contact conditions fluctuate, wherein the contact surface pressure fluctuation distribution accompanying the fluctuation of the contact conditions is derived by analysis, and this contact surface pressure fluctuation The effective contact surface is identified from the distribution, and the average surface pressure and slip amount in the effective contact surface are derived by analysis. Using these, the effective work amount = effective contact area × average surface pressure × slip amount × friction coefficient is obtained. A method of predicting the occurrence of abnormal noise by fretting, wherein the generation of abnormal noise by fretting is predicted from the effective work amount. The method for predicting the occurrence of abnormal noise by fretting according to claim 1, wherein an effective work amount is obtained by FEM analysis. A target member is at least one of a wheel and a wheel mounting flange of a hub unit to which the wheel is mounted, a wheel mounted on the flange, and a brake rotor disposed between the wheel mounting flange and the wheel. The method for predicting the occurrence of abnormal noise by fretting according to claim 1 or 2.

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