JP5541689B2 - Monitoring method and dynamic balance measuring device in balance test - Google Patents

Description

  The present invention relates to a monitoring method and a dynamic balance measuring device in a balance test for detecting an unbalance force when a tire is rotated.

Conventionally, a tire dynamic balance test has been performed in the final process of a tire production line. In an actual balance test, there is a load synchronized with the rotation of the tire even when the tire is not attached, and correct balance measurement of only the tire cannot be performed without correction, and therefore various means for correcting the detected load are taken.
Load fluctuations caused by these mechanical factors include unbalance due to eccentricity of the rotating shaft and uneven rotation friction of the rotating shaft, etc. Disturbances (hereinafter sometimes referred to as mechanical loads) become balance calculation errors.

In the dynamic balance measuring device of the type integrated with the upper and lower rims, mechanical load data indicating the influence of the machine other than the tire unbalance can be collected by performing the operation in the tire non-mounted state. And the balance calculation result of a tire is computable by taking the difference of the said mechanical load data from the actual test data rotated at the time of tire mounting.
On the other hand, in the vertical rim split type dynamic balance measuring device, it is necessary to take the mechanical load data as a state in which the upper and lower rims do not move relative to each other by attaching the tire and pressing the upper and lower rims with the tire's expansion force. Therefore, two times of data in which the tire mounting phase with respect to the rim is set to 0 deg and 180 deg are taken, and these data are summed to cancel the tire unbalanced force to obtain the mechanical load.

  Patent Document 1 proposes a structure in which the upper and lower divided rims are rotated integrally with the conventional method without attaching a tire so that accurate measurement can be performed without receiving a tire mounting error or the like.

Japanese Patent No. 3429346

  In an actual dynamic balance measuring device, the mechanical load may change due to a change in temperature, a change in belt tension, or the like during repeated measurement regardless of the type of rim structure. In this case, the reference data for correction changes, and a correct balance calculation result cannot be obtained. During actual operation in which mass-produced tires are measured one after another, there is a problem in that imbalance is different depending on the tires, so that a change in mechanical load is not noticed and wrong dynamic balance measurement is performed.

  In view of the above problems, the present invention provides a monitoring method and a dynamic balance measuring device in a balance test that can prevent erroneous dynamic balance measurement by monitoring a load generated when a tire is rotated. The purpose is to do.

In order to achieve the above-described object, the present invention takes the following technical means. That is, in a balance test that measures the dynamic balance of a tire using a dynamic balance measuring device that measures the load generated when the tire is rotated, the load is decomposed into frequency components, and higher-order components in the frequency components are analyzed. This is in that a disturbance that affects the dynamic balance is detected based on the component.
The higher-order component is a second-order or higher-order component. Further, the disturbance is caused by a change in mechanical characteristics of the dynamic balance measuring device.

  Another means of the present invention is based on a tire rotating shaft that rotatably supports a tire, a load measuring device that measures a load generated when the tire is rotated, and a load measured by the load measuring device. In the dynamic balance measuring apparatus including a calculation control unit that calculates a dynamic balance, the calculation control unit includes a frequency analysis unit that decomposes the load into frequency components, and a frequency component decomposed by the frequency analysis unit. And a disturbance detection unit that detects a disturbance that affects the dynamic balance based on the higher-order component.

It is preferable that the disturbance detection unit detects the disturbance when a change in a second-order or higher-order component is a predetermined value or more.
The most preferable form of the monitoring method in the balance test according to the present invention is the balance test in which the dynamic balance of the tire is measured using a dynamic balance measuring device that measures the load generated when the tire is rotated. The load may be decomposed into frequency components, and it may be determined that a disturbance affecting the dynamic balance has occurred when the amplitude of a higher-order component in the frequency component changes by a predetermined value or more.
Preferably, the predetermined value is 20%.
The most preferable embodiment of the dynamic balance measuring device according to the present invention includes a tire rotating shaft that rotatably supports a tire, a load measuring device that measures a load generated when the tire is rotated, and the load measuring device. In the dynamic balance measuring device comprising a calculation control unit that calculates a dynamic balance based on the load measured in step (b), the calculation control unit includes a frequency analysis unit that decomposes the load into frequency components, and a frequency analysis unit And a disturbance detection unit that determines that a disturbance affecting the dynamic balance has occurred when the amplitude of a higher-order component in the decomposed frequency component changes by a predetermined value or more.
Preferably, the disturbance detection unit may determine that a disturbance has occurred when a change in a second-order or higher-order component has changed by 20% or more.

  According to the present invention, it is possible to prevent erroneous measurement of dynamic balance by monitoring the load generated when the tire is rotated.

It is the schematic which shows the structure of a dynamic balance measuring device. It is explanatory drawing explaining how to obtain | require dynamic balance. It is the figure which showed the flow of the balance test in a dynamic balance measuring device. It is a relationship figure of the frequency when a load is subjected to frequency analysis, and the load. FIG. 6 is a relationship diagram between a frequency and a load change when a tire imbalance changes. FIG. 6 is a relationship diagram between frequency and load change when the unbalance is constant.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The dynamic balance measuring device 1 of the present invention includes a tire rotation shaft 3 to which a tire 2 on which dynamic balance measurement is performed is attached, and a housing 4 that rotatably supports the tire rotation shaft 3. Further, the dynamic balance measuring device 1 includes a rotational driving device 6 that applies a driving force to the tire rotating shaft 3, a driving belt 7 that transmits the driving force of the rotational driving device 6 to the tire rotating shaft 3, and a dynamic balance of the tire 2. Load measuring devices 8a and 8b.

  As shown in FIG. 1, the tire rotation shaft 3 is supported by a cylindrical housing 4 that is arranged such that the axis is directed in the vertical direction and is open vertically. The tire rotation shaft 3 protrudes upward from the upper end of the housing 4. A tire rim is provided on the upper end side of the tire rotation shaft 3, and the tire 2 to be tested is mounted on the tire rim. The tire rotation shaft 3 protrudes downward from the lower end of the housing 4, and a pulley (driven pulley) 10 that receives a rotational driving force is attached to the lower protrusion side of the tire rotation shaft 3, and a rotation measuring instrument 11. Is attached.

The housing 4 is supported by the base frame 9, and a bearing (bearing) and the like that rotatably supports the tire rotation shaft 3 are disposed inside the housing 4.
The rotation drive device 6 includes a motor 21 having a drive shaft arranged in parallel to the tire rotation shaft 3 and a drive pulley 12 attached to the tip of the drive shaft.
The motor 21 is fixed to the base frame 9. A drive belt 7 is wound around a drive pulley 12 provided in the motor 21, and this drive belt 7 is also wound around a driven pulley 10 provided on the tire rotation shaft 3 described above. Therefore, when the motor 21 is operated and the drive pulley 12 attached to the tip of the drive shaft rotates, the driven pulley also rotates through the drive belt 7 and the tire rotation shaft 3 is rotationally driven.

The dynamic balance measuring device 1 measures the dynamic balance of the tire 2 and includes several measuring means for that purpose.
As one of the measuring means, the dynamic balance measuring device 1 includes a rotation measuring device 11 that detects the number of rotations of the tire rotation shaft 3 (that is, the number of rotations of the tire 2 to be measured).
The rotation measuring device 11 includes an encoder 13 and a reference angle detector 14, detects rotation of the tire rotation shaft 3, generates a pulse signal in accordance with the detection timing, and also generates a predetermined angle that becomes a reference angle. This unit emits a pulse signal for each rotation angle. The rotation measuring instrument 11 is arranged at the lower end of the tire rotation shaft 3.

  In addition, load measuring devices 8a and 8b are provided as measuring means. The load measuring devices 8a and 8b are units for detecting an unbalanced load of the tire 2 transmitted from the tire rotating shaft 3 to the housing 4, and are configured by, for example, a load cell. The load measuring devices 8a and 8b are provided between the housing 4 and the base frame. The load measuring devices 8a and 8b are configured so that the load in the direction perpendicular to the straight line connecting the rotation shaft of the drive pulley 12 and the rotation shaft of the driven pulley 10 is prevented so that the tension of the drive belt 7 does not act directly in the load detection direction. It is intended to measure only.

Outputs (measurement results) from the rotation measuring instrument 11 and the load measuring instruments 8a and 8b are transmitted to the arithmetic control unit 15 provided in the dynamic balance measuring apparatus 1. The arithmetic control unit 15 calculates the unbalance and dynamic characteristics of the tire 2 from the input measurement result, and simultaneously controls the motor 21 and the like.
In such a dynamic balance measuring apparatus 1, in order to perform a balance test, first, the motor 21 is driven and the tire rotation shaft 3 is rotationally driven via the drive belt 7. And the dynamic balance of the tire 2 is measurable by measuring the load which generate | occur | produces when rotating the tire 2 with the two load measuring devices 8a and 8b.

  For example, as shown in FIG. 2, the balance load on the upper surface side of the tire 2 is B1, the balance load on the lower surface side of the tire 2 is B2, and the measurement load of one load measuring device 8a (side closer to the tire 2) is F1, When the measurement load F2 of the other load measuring device 8b is used, the force balance is expressed by equation (1), and the moment balance is expressed by equation (2). From Equation (1) and Equation (2), the balance load on the upper surface side is as shown in Equation (3), and the balance load on the lower surface side is as shown in Equation (4), thereby obtaining the dynamic balance. it can. In addition, as shown to Formula (1) and Formula (2), a measurement load can be calculated | required with the complex number which has an amplitude and a phase from the frequency analysis of data.

  As described above, in the dynamic balance measuring device 1, the dynamic balance can be measured by measuring the loads (F1, F2) generated when the tire 2 is rotated by the load measuring devices 8a, 8b. Here, for example, when the measurement is repeated, the mechanical load changes due to mechanical factors such as a change in tension of the drive belt 7 and frictional unevenness of the tire rotating shaft 3. Thus, if the mechanical load changes during the balance test, the correct balance test measurement result may not be obtained. If a balance test is successively performed on the tire 2 that is mass-produced, an incorrect dynamic balance may be measured without noticing a change in the mechanical load.

In the present invention, when a change in mechanical load due to such a mechanical factor occurs, the balance test (dynamic balance) is adversely affected. Therefore, a disturbance caused by a change in mechanical characteristics of the dynamic balance measuring device 1 is immediately detected. To do. This will be described in detail below.
The arithmetic control unit 15 includes a frequency analysis unit 16 and a disturbance detection unit 17. The frequency analysis unit 16 decomposes the loads (F1, F2) measured by the load measuring devices 8a, 8b into frequency components by fast Fourier transform, and is composed of a computer program or the like.

  The disturbance detection unit 17 detects a disturbance that affects the test based on higher-order components in the frequency components decomposed by the frequency analysis unit 16, and is configured by a computer program or the like. Specifically, when the load (F1, F2) during the balance test is broken down into frequency components, the disturbance detection unit 17 changes the second-order or higher-order components in the frequency components. Sequential monitoring is performed, and it is detected that a disturbance affecting the balance test has occurred when the change in the second-order or higher-order component exceeds a predetermined value.

  More specifically, as shown in FIG. 4, when the loads (F1, F2) are decomposed by the frequency analysis unit 16, the frequency components of the load are not only 1 times the tire rotation frequency but also 2 times, 3 times. Double ... n times higher order components appear. Here, in the higher-order component of the second order or higher, it is considered that another mechanical characteristic different from the tire 2 rotation speed appears. If there is no change in load (load amplitude) in the second and higher order components, it is considered that the mechanical load does not vary due to mechanical factors. On the other hand, when the load amplitude is changed, it is considered that the mechanical load is changed due to a mechanical factor. Therefore, in the disturbance detection unit 17, when the load amplitude is changed by 20% or more in the second order or higher order component. In addition, it is detected that a disturbance has occurred. For example, the change in the load amplitude of the secondary component is obtained by Equation (5), and it is detected that a disturbance has occurred when the change in the load amplitude satisfies Equation (5).

In equation (5), the load amplitude of the secondary component of the tire rotational frequency at normal time is F0 ₂ , the load amplitude of the secondary component of the tire rotational frequency after mechanical load change is F1 _2, and the secondary component of the tire rotational frequency. The load amplitude evaluation criteria (threshold value for detecting a disturbance, for example, 20%) is B.
When the disturbance detection unit 17 detects a disturbance, the arithmetic control unit 15 outputs a command to the motor 21 to stop the motor 21, that is, automatically stop the dynamic balance measuring device 1.

FIG. 3 shows the flow of the balance test in the dynamic balance measuring apparatus 1. The processing by the calculation control unit 15 will be described together with the description of the balance test.
First, the tire 2 is mounted on the tire rotation shaft 3 (rim), the tire rotation shaft 3 is rotated, and the detection signals of the load measuring devices 8a and 8b (load cells) are acquired (load data is taken into the arithmetic control unit 15). (S1).

The frequency analysis unit 16 of the calculation control unit 15 performs frequency analysis and fast Fourier transform on the load using the acquired load data (S2).
The disturbance detection unit 17 of the arithmetic control unit 15 performs frequency analysis to determine whether or not the variation amount (change amount) of the load amplitude is less than 20% in the second or higher order component as described above (S3). ).

If the change amount of the load amplitude is less than 20% (S3, yes), the load data is corrected using the mechanical load stored in advance in the arithmetic control unit 15 (S4).
And as mentioned above, dynamic balance is calculated | required using Formula (3) or Formula (4) (S5). It should be noted that necessary functions such as the equations (3) and (4) for obtaining the dynamic balance are stored in the arithmetic control unit 15, and the dynamic balance is calculated by the arithmetic control unit 15.

  On the other hand, if the change amount of the load amplitude is 20% or more (S3, No), a change in mechanical characteristics and a mechanical abnormality occur, and as a result, it is considered that a disturbance has occurred. It stops automatically (S6). And it is investigated whether abnormality has generate | occur | produced in the mechanical elements (For example, a bearing, the drive belt 7, the motor 21, the tire rotating shaft 3, etc.) in the dynamic balance measuring device 1 (S7).

  When it is recognized that there is an abnormality (S7, there is an abnormality), machine maintenance and adjustment of the target part are performed (S8). If no abnormality is recognized (S7, no abnormality), the mechanical load is reset. In resetting the mechanical load, after the tire 2 is removed from the tire rotation shaft 3 (rim), the tire rotation shaft 3 is rotated in a state where the tire 2 is not mounted, and the load measuring devices 8a and 8b are used to load data. Then, the frequency is analyzed and the load amplitude value serving as a reference is stored in the arithmetic control unit 15 (S9).

Thereafter, the tire 2 is remounted on the tire rotation shaft 3 and the balance test is resumed (S10).
FIG. 5 shows the load amplitude when the balance test is performed on the tire 1 and the tire 2 having different dynamic balances, that is, when only the dynamic balance (only unbalance) is changed depending on the type of the tire.
As shown in FIG. 5, first, when the dynamic balance differs depending on the tire characteristics, the primary component of the tire rotation frequency changes in the load amplitude. Thus, when the balance test of two tires is performed, if the mechanical characteristics do not change through both tests (no disturbance), no change appears in the nth-order component of the tire rotation frequency in the load amplitude. .

That is, when only the tire imbalance changes and the mechanical characteristics do not change, only the primary component of the load amplitude changes, but the secondary component does not change.
On the other hand, FIG. 6 shows the load amplitude when the dynamic balance (unbalance) of the tire remains constant in the balance test, for example, when the same tire is tested.

  As shown in FIG. 6, when the primary component and the secondary component of the tire rotation frequency change in the load amplitude as shown by the dotted line, although the dynamic balance does not change in the balance test (for example, the same tire). think of. Although the primary component of the tire rotation frequency has changed despite the fact that the dynamic balance has not changed, it seems that the dynamic balance of the tire has changed at first glance, but the change in the load amplitude of the secondary component Since the load amplitude of the secondary component is also changing, it is considered that the change of the load amplitude of the primary component is caused by a change in mechanical load (change in mechanical characteristics).

Here, as shown in FIGS. 5 and 6, the fluctuation of the primary component appears when the change of the dynamic balance and the change of the mechanical load occur, whereas the fluctuation of the secondary component shows the mechanical load. In particular, it can be said that the change in the mechanical load appears remarkably in the secondary component of the load amplitude.
Therefore, it is possible to grasp the change in the mechanical load by monitoring the secondary component in the tire balance test.

In this embodiment, the description has focused on the secondary component. Actually, however, the mechanical load is different from device to device, so that the mechanical load is significant first. It is desirable to identify the components that appear in, and follow the changes (select components that appear as large as possible to clarify the distinction from noise).
In addition, the mechanical load includes not only specific high-order components but also multiple components, and which component changes greatly depending on the device, so in order to improve accuracy, judge by the change of multiple components Is desirable.

  That is, by monitoring the change in the n (n> = 2) order component of the rotational frequency that is not affected by the dynamic balance of the tire 2, it is possible to immediately catch the deterioration of balance measurement accuracy due to a change in the mechanical load. By performing re-removal and machine maintenance, it is possible to correct a balance measurement error due to a change in the machine load, and it can be used as an index indicating the possibility of a simple mechanical device abnormality. As a result, an incorrect balance measurement result can be prevented. It is not necessary to add a large-scale device, and the change in the state of the machine can be grasped only by confirming the n-order component of the load with the current equipment.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Dynamic balance measuring device 2 Tire 3 Tire rotating shaft 4 Housing 6 Rotation drive device 7 Drive belt 8a Load measuring device 8b Load measuring device 10 Driven pulley 11 Rotation measuring device 12 Drive pulley 13 Encoder 14 Reference angle detector 15 Calculation control part 16 Frequency analysis unit 17 Disturbance detection unit

Claims (6)

In a balance test that measures the dynamic balance of the tire using a dynamic balance measuring device that measures the load generated when the tire is rotated,
The load is decomposed into frequency components, and it is determined that a disturbance affecting the dynamic balance has occurred when the amplitude of a higher-order component in the frequency components changes by a predetermined value or more. Monitoring method in balance test. The monitoring method in the balance test according to claim 1, wherein the predetermined value is 20% . The high-order component, the monitoring method in balance test according to claim 1 or 2, characterized in that a second or higher order components. The disturbance monitoring method in balance test according to any one of claims 1 to 3, wherein the is caused by a change in mechanical properties of the dynamic balance measuring apparatus. A tire rotating shaft that rotatably supports a tire, a load measuring device that measures a load generated when the tire is rotated, and an arithmetic control unit that calculates a dynamic balance based on the load measured by the load measuring device In a dynamic balance measuring device equipped with
The arithmetic control unit influences the dynamic balance when a frequency analysis unit that decomposes the load into frequency components and an amplitude of a higher-order component in the frequency component decomposed by the frequency analysis unit changes by a predetermined value or more. And a disturbance detection unit that determines that a disturbance has been generated . 6. The dynamic balance measuring apparatus according to claim 5 , wherein the disturbance detection unit determines that a disturbance has occurred when a change in a second-order or higher-order component has changed by 20% or more .

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