Tire balance measurement device, evaluation method of tire balance measurement device, calibration method of tire balance measurement device, and calibration program of tire balance measurement device

A tire balance measurement device includes a rotation drive portion, an eccentric force measurement unit, a calculation unit, and an evaluation unit. The eccentric force measurement unit measures an eccentric force generated in a main shaft. The calculation unit calculates an eccentric amount of the main shaft based on the eccentric force measured by the eccentric force measurement unit. The evaluation unit evaluates the eccentric amount of the main shaft based on a correlation between the eccentric force measured by the eccentric force measurement unit when the main shaft is rotated at a predetermined rotation speed, and the rotation speed.

RELATED APPLICATIONS

The present application is a National Phase of International Application Number PCT/JP2016/074631 filed Aug. 24, 2016.

TECHNICAL FIELD

The present invention relates to a tire balance measurement device, an evaluation method of a tire balance measurement device, a calibration method of a tire balance measurement device, and a calibration program of a tire balance measurement device.

BACKGROUND ART

In a manufacturing process of a tire, various inspections are performed on a manufactured tire for quality control. As one of the inspections, a dynamic balance when the tire is rotated (hereinafter, referred to as a dynamic balance) is measured.

A tire balance measurement device which inspects the dynamic balance of a tire includes a lower rim and an upper rim which interposes a tire therebetween, a main shaft which is integrally provided with the lower rim, a rotation drive mechanism which rotationally drives the main shaft, and an eccentric amount detection sensor which detects an eccentric amount generated in the main shaft. The tire balance measurement device rotates the main shaft by the rotation drive mechanism in a state where the tire interposed between the lower rim and the upper rim is filled with air. The tire interposed between the lower rim and the upper rim integrally rotates with the main shaft by the rotation of the main shaft. The tire balance measurement device detects the eccentric amount generated in the main shaft when the tire is rotated, and thereby, measures the dynamic balance (unbalance amount) of the tire.

In the tire balance measurement device, in order to secure measurement accuracy, it is necessary to calibrate a balance of the lower rim, the upper rim, and the main shaft. PTL 1 discloses a calibration method of a tire balance measurement device using a sinker whose weight is known. In this method, in each of a case where the sinker is mounted on only the lower rim, a case where the sinker is mounted on only the upper rim, a case where the sinker is mounted on the lower rim and the upper rim, and a case where the sinker is not mounted, the lower rim, the upper rim, and the main shaft are rotated and an eccentric force of the main shaft is detected. The tire balance measurement device is calibrated from a measurement result of the eccentric force when the sinkers whose weights are known are mounted and the lower rim, the upper rim, and the main shaft are rotated.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, as disclosed in PTL 1, in order to perform the calibration of the tire balance measurement device using the sinker, it is necessary to stop manufacturing of a tire and attach and detach the sinker with respect to the lower rim or the upper rim, which requires time and effort. Accordingly, if the calibration of the tire balance measurement device is performed periodically, production efficiency of a manufacturing process of a tire decreases.

An object of the present invention is to provide a tire balance measurement device, an evaluation method of a tire balance measurement device, a calibration method of a tire balance measurement device, and a calibration program of a tire balance measurement device capable of easily performing calibration of the tire balance measurement device periodically, preventing a decrease in production efficiency of a manufacturing process of a tire, and performing a quality control with higher accuracy.

Solution to Problem

According to a first aspect of the present invention, there is provided a tire balance measurement device including: a rotation drive portion; an eccentric force measurement unit; a calculation unit; and an evaluation unit. The rotation drive portion rotates a main shaft which supports at least one of a pair of rims which can interpose a tire therebetween. The eccentric force measurement unit measures an eccentric force generated in the main shaft when the main shaft which supports at least one of the pair of rims is rotated. The calculation unit calculates an eccentric amount of the main shaft based on the eccentric amount measured by the eccentric force measurement unit. The evaluation unit evaluates the eccentric amount of the main shaft based on a correlation between the eccentric amount calculated by the calculation unit based on the eccentric force measured when the main shaft is rotated at a predetermined rotation speed by the rotation drive portion, and the rotation speed.

According to this configuration, if the tire is rotated along with the main shaft by the rotation drive portion in a state where the tire is interposed between the pair of rims and the eccentric force of the main shaft is measured by the eccentric force measurement unit, it is possible to obtain an unbalance amount of the tire by the calculation unit.

In addition, if the main shaft which supports at least one of the pair of rims is rotated by the rotation drive portion in a state where the tire is not interposed between the pair of rims and the eccentric force of the main shaft is measured by the eccentric force measurement unit, it is possible to obtain the eccentric amount of the main shaft itself by the calculation unit. For example, in a case where the eccentric amount of the main shaft itself is changed due to some reasons including a change of temperatures or the like, if the main shaft is rotated at the same rotation speed before and after the change of the eccentric amounts occurs, it is possible to easily ascertain the change. Accordingly, in the evaluation unit, by evaluating the eccentric amount of the main shaft based on the correlation between the eccentric amount calculated by the calculation unit when the main shaft is rotated at the predetermined rotation speed by the rotation drive portion and the rotation speed, it is possible to ascertain whether or not the change of the eccentric amounts of the main shaft is generated.

In this way, it is possible to ascertain the change of the eccentric amounts of the main shaft without mounting a sinker on the main shaft. Accordingly, it is possible to easily check the eccentric amount of the main shaft in a short time.

According to a second aspect of the present invention, the tire balance measurement device of the first aspect may further include a correction unit which corrects Calculation Expression used in a calculation by the calculation unit based on an evaluation result of the eccentric amount by the evaluation unit.

Accordingly, in a case where the eccentric amount of the main shaft is changed, it is possible to calibrate the tire balance measurement device by correcting Calculation Expression which is used in the calculation by the calculation unit using the correction unit.

According to a third aspect of the present invention, the evaluation unit of the first or second aspect may evaluate the eccentric amount of the main shaft based on a correlation between the eccentric amount calculated by the calculation unit based on the eccentric force measured when the main shaft is rotated at each rotation speed by rotating the main shaft at a plurality of rotation speeds different from each other, and the rotation speed.

If the rotation speed of the main shaft increases, a centrifugal force generated in the main shaft increases, and the eccentric amount generated due to unbalance of the main shaft also increases. Accordingly, if the main shaft is rotated at the plurality of rotation speeds different from each other and the eccentric force is measured at each of the rotation speeds, it is possible to evaluate the change of the eccentric amounts of the main shaft with higher accuracy.

According to a fourth aspect of the present invention, there is provided an evaluation method of a tire balance measurement device, in which the tire balance measurement device includes a pair of rims which interposes a tire therebetween and a rotation drive portion which rotates the pair of rims. The tire balance measurement device further includes an eccentric force measurement unit and a calculation unit. The eccentric force measurement unit measures an eccentric force generated in a main shaft when the main shaft which supports at least one of the pair of rims is rotated. The calculation unit calculates an eccentric amount of the main shaft based on the eccentric amount measured by the eccentric force measurement unit. The evaluation method of a tire balance measurement device includes a step of evaluating the eccentric amount of the main shaft based on a correlation between the eccentric amount calculated by the calculation unit based on the eccentric force measured when the main shaft is rotated at a predetermined rotation speed by the rotation drive portion, and the rotation speed.

By using the evaluation method of a tire balance measurement device, it is possible to ascertain the change of the eccentric amounts of the main shaft itself of the tire balance measurement device without mounting a sinker on the main shaft. Accordingly, it is possible to easily check the eccentric amount of the main shaft in a short time.

According to a fifth aspect of the present invention, there is provided a calibration method of a tire balance measurement device, in which the tire balance measurement device includes a pair of rims which interposes a tire therebetween and a rotation drive portion which rotates the pair of rims. The tire balance measurement device further includes an eccentric force measurement unit and a calculation unit. The eccentric force measurement unit measures an eccentric force generated in a main shaft when the main shaft which supports at least one of the pair of rims is rotated. The calculation unit calculates an eccentric amount of the main shaft based on the eccentric amount measured by the eccentric force measurement unit. The calibration method of a tire balance measurement device includes a step of evaluating the eccentric amount of the main shaft based on a correlation between the eccentric amount calculated by the calculation unit based on the eccentric force measured when the main shaft is rotated at a predetermined rotation speed by the rotation drive portion, and the rotation speed. The calibration method of a tire balance measurement device further includes a step of correcting Calculation Expression used in a calculation by the calculation unit based on an evaluation result of the eccentric amount by the step of evaluating the eccentric amount of the main shaft.

By using the calibration method of a tire balance measurement device, in a case where the eccentric amount of the main shaft of the tire balance measurement device is changed, it is possible to calibrate the tire balance measurement device by correcting Calculation Expression which is used in the calculation by the calculation unit using the correction unit.

According to a sixth aspect of the present invention, there is provided a calibration program of a tire balance measurement device, in which the tire balance measurement device includes a pair of rims which interposes a tire therebetween, and a rotation drive portion which rotates the pair of rims. The tire balance measurement device further includes an eccentric force measurement unit and a calculation unit. The eccentric force measurement unit measures an eccentric force generated in a main shaft when the main shaft which supports at least one of the pair of rims is rotated. The calculation unit calculates an eccentric amount of the main shaft based on the eccentric amount measured by the eccentric force measurement unit. The calibration program of the tire balance measurement device includes processing of evaluating the eccentric amount of the main shaft based on a correlation between the eccentric amount calculated by the calculation unit based on the eccentric force measured when the main shaft is rotated at a predetermined rotation speed by the rotation drive portion, and the rotation speed. The calibration program of the tire balance measurement device further includes processing of correcting Calculation Expression used in a calculation by the calculation unit based on an evaluation result of the eccentric amount by the processing of evaluating the eccentric amount of the main shaft.

Since the calibration program of the tire balance measurement device is introduced to the tire balance measurement device, in a case where the eccentric amount of the main shaft of the tire balance measurement device is changed, it is possible to calibrate the tire balance measurement device by correcting Calculation Expression which is used in the calculation by the calculation unit using the correction unit.

Advantageous Effects of Invention

According to the above-described tire balance measurement device, evaluation method of a tire balance measurement device, calibration method of a tire balance measurement device, and calibration program of the tire balance measurement device, the tire balance measurement device is easily calibrated, a decrease in the production efficiency of the manufacturing process of the tire is prevented, and it is possible to perform quality control with higher accuracy.

DESCRIPTION OF EMBODIMENTS

FIG. 1is an elevation view showing schematic configuration of a tire balance measurement device in an embodiment of the present invention.FIG. 2is a flat sectional view showing a load cell which detects an eccentric force of a main shaft of the tire balance measurement device in the embodiment of the present invention.

As shown inFIG. 1, a tire balance measurement device1includes a device main body10and a control unit20.

The device main body10includes a base11, a main shaft12, a lower rim13, an upper rim14, a shaft15, and load cells (eccentric force measurement units)16L and16H.

The base11is installed on a floor surface.

The main shaft12extends in a vertical direction and is supported to the base11via a main shaft support member19. The main shaft support member19is attached to the base11via attachment members19h. The main shaft support member19is formed in a cylindrical shape and the main shaft12is rotatably supported inside the main shaft support member19.

The main shaft12is rotationally driven around a center axis thereof by a rotation drive portion17such as a motor provided in the base11. An upper end portion12aof the main shaft12protrudes vertically upward from an upper surface11aof the base11.

The lower rim13is integrally fixed to the upper end portion12aof the main shaft12and rotates along with the main shaft12. A rim contact surface13f, which comes into close contact with the inner peripheral portion of the tire T from below, is formed on the lower rim13.

The upper rim14is disposed so as to face the lower rim13with a gap therebetween vertically. A rim contact surface14f, which comes into close contact with the inner peripheral portion of the tire T from above, is formed on the upper rim14.

The shaft15extending downward is integrally provided on the upper rim14. A lower end portion15bof the shaft15is inserted into an insertion hole12hformed in the main shaft12and is provided to be lifted and lowered in a vertical direction with respect to the main shaft12. A held portion14pfor holding the upper rim14and the shaft15is provided on the upper rim14. The held portion14pcan be held by a chuck member18of a lifting/lowering device (not shown), and the upper rim14and the shaft15are lifted and lowered vertically by the lifting/lowering device (not shown). Accordingly, the upper rim14can move close to or away from the lower rim13.

As shown inFIGS. 1 and 2, the load cells16L and16H are provided so as to be in contact with the outer peripheral surface19rof the main shaft support member19inside the base11. The load cells16L and16H detect an eccentric force (a force in a radial direction orthogonal to the center axis of the main shaft12) generated in the main shaft12via the main shaft support member19. The load cells16L and16H are disposed at two locations positioned with a gap therebetween in the vertical direction in the base11.

FIG. 3is a block diagram showing a configuration of a control unit of the tire balance measurement device in the embodiment of the present invention.

As shown inFIG. 3, the control unit20includes a rotation control unit21, a calculation unit22, an evaluation unit23, a calibration unit (correction unit)24, and a storage unit25.

The rotation control unit21controls the operation of the rotation drive portion17and adjusts the rotation speed of the main shaft12.

The calculation unit22calculates an eccentric amount based on signals of eccentric forces detected by the load cells16L and16H. In the present embodiment, the calculation unit22can calculate an unbalance amount of the tire T held between the lower rim13and the upper rim14and the eccentric amount of the main shaft12.

The evaluation unit23evaluates an unbalance amount of the tire T and an eccentric amount of the main shaft12based on the unbalance amount and the eccentric amount of the main shaft12calculated by the calculation unit22.

In a case where the eccentric amount of the main shaft12in the evaluation unit23deviates from a predetermined reference, the calibration unit24performs calibration processing described in detail later.

The storage unit25stores the unbalance amount or the eccentric amount calculated by the calculation unit22, an evaluation result in the evaluation unit23, or the like.

(Measurement Processing of Unbalance Amount of Tire T)

FIG. 4is a flowchart showing a flow of measurement processing of the unbalance amount of the tire in the tire balance measurement device of the embodiment of the present invention.

The tire balance measurement device1measures the unbalance amount of the tire T in a state where the tire T is interposed between the lower rim13and the upper rim14.

For this purpose, as shown inFIG. 4, first, the tire T is mounted on the tire balance measurement device1(Step S101). Here, an inner peripheral edge portion t1(refer toFIG. 1) on the lower surface side of the tire T is set on the lower rim13in a state where the upper rim14is lifted by the lifting/lowering device so as to be separated from the lower rim13. Next, the upper rim14is lowered by the lifting/lowering device to come into close contact with an inner peripheral edge portion t2(refer toFIG. 1) on the upper surface side of the tire T. Next, the tire T is filled with air by an air filling mechanism (not shown) included in the lower rim13.

In this way, after the tire T is interposed between the lower rim13and the upper rim14so as to be held, the main shaft12is rotated around the center axis at a predetermined rotation speed by controlling the rotation drive portion17using the rotation control unit21(Step S102).

Accordingly, the tire T integrally rotates with the main shaft12, the lower rim13, the shaft15, and the lower rim13.

The load cells16L and16H detect an eccentric force generated in the main shaft12during the rotation of the tire T (Step S103). An output signal of the eccentric force detected by each of the load cells16L and16H is transmitted to the calculation unit22of the control unit20.

The calculation unit22calculates the unbalance amount of the tire T based on the output signal transmitted from the load cells16L and16H (Step S104).

The evaluation unit23determines whether or not the unbalance amount of the tire T calculated by the calculation unit22is within a predetermined reference range (Step S105). The tire T of which the unbalance amount is within the reference range can be determined as a good item, and the tire T of which the unbalance amount is out of the reference range can be determined as a defective item.

In this way, after the calculation and the evaluation of the unbalance amount with respect to the tire T end, air is released from the tire T. Thereafter, the upper rim14is lifted so as to be separated from the lower rim13, and the tire T is removed from the upper rim14(Step S106).

(Measurement Processing of Eccentric Amount of Main Shaft)

FIG. 5is a flowchart showing a flow of measurement processing of the eccentric amount of the main shaft in the tire balance measurement device of the embodiment of the present invention.

The tire balance measurement device1can measure the eccentric amount of the main shaft12in a state where the tire T is not mounted. In order to measure the eccentric amount of the main shaft12, first, the upper rim14is lowered by the lifting/lowering device and is combined with the lower rim13in a state of being facing the lower rim13.

Next, as shown inFIG. 5, the main shaft12is rotated around the center axis at a predetermined first rotation speed r1by controlling the rotation drive portion17using the rotation control unit21(Step S201). Accordingly, the main shaft12rotates at the first rotation speed r1.

The load cells16L and16H detect the eccentric forces FL and FH generated in the main shaft12during the rotation thereof (Step S202). The output signals of the eccentric forces FL and FH detected by the load cells16L and16H are transmitted to the calculation units22of the control unit20.

Next, the main shaft12is rotated around the center axis at a second rotation speed r2different from the first rotation speed r1by controlling the rotation drive portion17using the rotation control unit21(Step S203). Accordingly, the main shaft12rotates at the second rotation speed r2.

The load cells16L and16H detect the eccentric forces FL and FH generated in the main shaft12during the rotation thereof (Step S204). The output signals of the eccentric forces FL and FH detected by the load cells16L and16H are transmitted to the calculation units22of the control unit20.

The calculation unit22calculates the eccentric amount of the main shaft12based on the output signals transmitted from the load cells16L and16H (Step S205).

Here, the method of calculating the unbalance amount of the tire T or the eccentric amount of the main shaft12by the calculation unit22based on the eccentric forces FL, FH, FL, and FH detected by the load cells16L and16H is not limited at all and can appropriately use a known calculation method.

For example, the calculation unit22obtains the unbalance amount (or the eccentric amount) P from the eccentric forces FL and FH detected by the load cells16L and16H when the tire T or the main shaft12is rotated, using Calculation Expression (1).

Next, an operation method of the above-described tire balance measurement device1will be described.

FIG. 6is a flowchart showing a flow of the operation method in the tire balance measurement device of the embodiment of the present invention.

As shown inFIG. 6, after installation, the tire balance measurement device1measures an initial value of the eccentric amount of the main shaft12(Step S1). For this purpose, the measurement processing (Steps S201to S205) of the eccentric amount of the main shaft12is performed. In this case, the eccentric amount P1calculated from the eccentric forces FL and FH when the main shaft12is rotated at the first rotation speed r1and the eccentric amount P2calculated from the eccentric forces FL and FH when the main shaft12is rotated at the second rotation speed r2are measured as initial values P1and P2.

The initial values P1and P2of the eccentric amount of the main shaft12measured in Step S1are stored in the storage unit25of the control unit20(Step S2).

Thereafter, the tire balance measurement device1measures the unbalance amount of the tire T which is sequentially transported from a manufacturing process (vulcanization process) of the tire to the tire balance measurement device1(Step S3). For this purpose, the measurement processing (Steps S101to S106) of the unbalance amount of the tire T is performed.

In order to calibrate the tire balance measurement device1periodically, the control unit20determines whether or not the measurement process of the unbalance amount of the tire T is performed a predetermined and specified number of times (Step S4). In a case where the number of performances of the measurement process does not reach the specified number of times, the measurement process with respect to the unbalance amount of the tire T of Step S3is repeated.

In a case where the number of performances of the measurement process reaches the specified number of times, the measurement of the eccentric amount of the main shaft12is performed (Step S5). In order to perform the measurement of the eccentric amount of the main shaft12in Step S5, the measurement processing (Step S201to S205) of the eccentric amount of the main shaft12is performed.

In this case, a measurement value P1′ of eccentric amounts obtained from eccentric forces FL′ and FH′ when the main shaft12is rotated at the first rotation speed r1and a measurement value P2′ of the eccentric amount obtained from eccentric forces FL′ and FH′ when the main shaft12is rotated at the second rotation speed r2are stored in the storage unit25.

Next, the evaluation unit23of the control unit20compares the measurement values P1′ and P2′ of the eccentric amount of the main shaft12with the initial values P1and P2of the eccentric amount of the main shaft12stored in the storage unit25in Step S2, based on the measurement result of the eccentric amount of the main shaft12measured in Step S5(Step S6).

Here, in order to compare the eccentric amounts of the main shaft12, specifically, it is performed as follows.

FIG. 7is a view showing a correlation between a variation of a rotation speed and a variation of the eccentric amount of the main shaft used for calibrating the tire balance measurement device in the embodiment of the present invention.

As shown inFIG. 7, for example, in the above-described Step S2, a relational expression P=k×r which indicates the correlation between the rotation speed r and the eccentric amount P of the main shaft12is determined from the initial value P1of the eccentric amount when the main shaft12is rotated at the first rotation speed r1and the initial value P2of the eccentric amount when the main shaft12is rotated at the second rotation speed r2.

Moreover, in the above-described Step S5, a relational expression P′=k′×r which indicates the correlation between the rotation speed r and the eccentric amount P′ of the main shaft12is determined from the measurement value P1′ of the eccentric amounts obtained from the eccentric forces FL′ and FH′ when the main shaft12is rotated at the first rotation speed r1and the measurement value P2′ of the eccentric amounts obtained from the eccentric forces FL′ and FH′ when the main shaft12is rotated at the second rotation speed r2.

The evaluation unit23compares the coefficient k and the coefficient k′ with each other by the relational expression P based on the initial values P1and P2stored in Step S2and the relational expression P′ based on the measurement values P1′ and P2′ measured in Step S5(Step S7). If a difference (or magnification) of the coefficient k′ with respect to the coefficient k is within a predetermined range, the step is returned to Step S3, and the measurement with respect to the unbalance amount of the tire T is continued.

In Step S7, in a case where the difference (or magnification) of the coefficient k′ with respect to the coefficient k is out of the predetermined range, calibration processing is performed (Step S8).

For this purpose, a correction coefficient k″ is obtained by “k″=k/k′” such that the current coefficient k′ based on the measurement values P1′ and P2′ measured by Step S5becomes the coefficient k based on the initial values P1and P2stored in Step S2.

The corrected correction coefficient k″(=k/k′) is stored in the storage unit25. Thereafter, in a case where the measurement of the unbalance amount of the tire T is performed, the unbalance amount P of the tire T is calculated from the eccentric forces FL and FH detected by the load cells16L and16H by correcting Calculation Expression (1) using the correction coefficient k″(=k/k′).

The series of processing as described above is repeatedly performed until the measurement of the unbalance amount of the tire T in the tire balance measurement device1ends (Step S9).

In addition, the measurement processing and the storing processing of the initial value of the eccentric amount of the main shaft12in Steps S1and S2may be performed only when the tire balance measurement device1is installed, and thereafter, when the tire balance measurement device1is activated and the measurement of the unbalance amount of the tire T starts, the correction value stored in Step S9may be used. Of course, each time the tire balance measurement device1is activated, the measurement processing and the storing processing of the initial value of the eccentric amount of the main shaft12in Steps S1and S2may be performed.

According to the tire balance measurement device1and the evaluation method of the tire balance measurement device1of the above-described embodiment, if the main shaft12is rotated by the rotation drive portion17in a state where the tire T is not interposed between the pair of lower rim13and upper rim14and the eccentric force F of the main shaft12is measured by the load cells16L and16H, it is possible to obtain the eccentric amount of the main shaft12itself by the calculation unit22. For example, in a case where the eccentric amount of the main shaft12itself is changed due to some reasons including a change of temperatures or the like, if the main shaft12is rotated at the same rotation speed before and after the change of the eccentric amounts occurs, it is possible to easily ascertain the change.

Accordingly, in the evaluation unit23, by evaluating the eccentric amount of the main shaft12based on the correlation between the eccentric amount calculated from the eccentric force F measured by the load cells16L and16H when the main shaft12is rotated at predetermined rotation speeds r1and r2by the rotation drive portion17and the rotation speeds r1and r2, it is possible to ascertain whether or not the change of the eccentric amounts of the main shaft12is generated.

In this way, it is possible to ascertain the change of the eccentric amounts of the main shaft12itself without mounting a sinker on the main shaft12. Accordingly, it is possible to check the eccentric amount of the main shaft12easily and in a short time.

Moreover, in a case where the eccentric amount of the main shaft12is changed, it is possible to calibrate the tire balance measurement device1by correcting Calculation Expression (1) which is used in the calculation by the calculation unit22using the calibration unit24.

In this way, it is possible to check and calibrate the eccentric amount of the main shaft12in a short time even while measuring and evaluating the unbalance amount of the tire T continuously. As a result, the calibration of the tire balance measurement device1is easily performed, and it is possible to prevent production efficiency of the manufacturing process of the tire T from decreasing. In addition, since the check of the eccentric amount of the main shaft12can be easily performed in a short time, it is possible to check the eccentric amount of the main shaft12more frequently than the related art, and it is possible to perform quality control with higher accuracy.

Moreover, in the evaluation unit23, if the main shaft12is rotated at the plurality of rotation speeds r1and r2different from each other and the eccentric force F is measured at each of the rotation speeds r1and r2, it is possible to evaluate the change of the eccentric amounts of the main shaft12with higher accuracy.

Moreover, since the above-described calibration method of the tire balance measurement device1and the above-described calibration program of the tire balance measurement device1are introduced to the tire balance measurement device1, it is possible to ascertain the change of the eccentric amounts of the main shaft12itself without mounting a sinker on the main shaft12. Accordingly, it is possible to easily check the eccentric amount of the main shaft12in a short time.

Moreover, in a case where the eccentric amount of the main shaft12is changed, it is possible to calibrate the tire balance measurement device1by correcting Calculation Expression (1) which is used in the calculation by the calculation unit22using the calibration unit24.

The present invention is not limited to the above-described embodiment, and design modifications can be applied to the present invention within a scope which does not depart from the gist of the present invention.

For example, in the above-described embodiment, when the eccentric amount of the main shaft12is measured, the main shaft12is rotated in the state where the upper rim14is lowered so as to face the lower rim13. However, the present invention is not limited to this. For example, only the main shaft12and the lower rim13may be integrally rotated with each other to measure the eccentric amount of the main shaft12.

In addition, in the above-described embodiment, when the number of measurements with respect to the unbalance amount of the tire T reaches the specified number of times, the eccentric amount of the main shaft12is measured. However, the eccentric amount of the main shaft12may be checked at any timing as long as the main shaft12is rotated and the eccentric force F can be detected. For example, the eccentric amount of the main shaft12may be measured when the measurement period of the unbalance amount of the tire T has reached a predetermined specified period.

In addition, in the above-described embodiment, the eccentric force F of the main shaft12on the lower rim13side is detected by the load cells16L and16H. However, the main shaft12may be provided on the upper rim14side to measure the eccentric force F by the main shaft12on the upper rim14side.

In the above-described embodiment, the tire balance measurement device1is calibrated by measuring the eccentric force F at the first rotation speed r1and the second rotation speed r2. However, the eccentric force F may be measured at three or more rotation speeds different from each other.

Moreover, the calibration of the tire balance measurement device1is realized by correcting Calculation Expression (1) used in the calculation of the unbalance amount in the calculation unit22. However, Calculation Expression or the correction contents are not limited at all.

When the initial value of the eccentric amount of the main shaft12is measured after the tire balance measurement device1is installed, the measurement processing (Step S201to S205) of the eccentric amount of the main shaft12is performed. However, the present invention is not limited to this. When the initial value of the eccentric amount of the main shaft12is measured after the tire balance measurement device1is installed, the initial value the eccentric amount of the main shaft12may be measured in a state where the tire T or the sinker is attached.

The structure of the tire balance measurement device is not limited at all and may have any other configuration. For example, the tire balance measurement device1is a vertical type configuration in which the lower rim13and the upper rim14vertically face each other and the main shaft12extends in the vertical direction. However, the present invention can be similarly applied to a horizontal type configuration in which a pair of rims faces to each other in a horizontal direction.

The evaluation method and the correction method of the tire balance measurement device1described in the above-described embodiment are realized by introducing a computer program to the control unit20of the tire balance measurement device1. Accordingly, the present invention can be configured as the calibration program of the tire balance measurement device1.

INDUSTRIAL APPLICABILITY

By evaluating the eccentric amount of the main shaft based on the correlation between the eccentric force measured when the main shaft is rotated at a predetermined rotation speed and the rotation speed, the tire balance measurement device is easily calibrated, a decrease in the production efficiency of the manufacturing process of the tire is prevented, and it is possible to perform quality control with higher accuracy.

REFERENCE SIGNS LIST

1: tire balance measurement device

10: device main body

11a: upper surface

12: main shaft

12a: upper end portion

13: lower rim

13f: rim contact surface

14f: rim contact surface

14p: held portion

15b: lower end portion

17: rotation drive portion

18: chuck member

19: main shaft support member

19h: attachment member

19r: outer peripheral surface

20: control unit

21: rotation control unit

22: calculation unit

23: evaluation unit

25: storage unit

t1, t2: inner peripheral edge portion