JP5644402B2 - Outside diameter measuring method and outside diameter measuring device - Google Patents

Description

  The present invention relates to an outer diameter measuring method and an outer diameter measuring apparatus.

  In the manufacture of a steel product having a cylindrical or cylindrical shape such as a steel bar or steel pipe, the cross-sectional shape is required to be constant over the entire length of the product. For this reason, the machining process for steel bars and steel pipes has many stages of rolling and straightening processes, and it is very important to measure the cross-sectional shape over the entire length of the product with high accuracy during and after these machining processes. It has become.

  On the other hand, in order to measure the shape of a cylindrical object to be measured (hereinafter referred to as a cylindrical object to be measured without distinguishing these shapes since only the outer shape is handled), a cross section of the cylindrical object to be measured is used. The work of aligning the temporary center position of the sensor and the center position of the measuring device (so-called centering work) is indispensable for high-precision measurement.

  As a technique for this, a technique for calculating the center of the cross section of the cylindrical object to be measured by rotating a sensor arranged on the outer periphery of the cylindrical object to be measured in the circumferential direction and measuring the displacement in the radial direction (for example, a patent) A technique is known in which a large number of sensors are arranged in the circumferential direction instead of rotating the sensors (see, for example, Patent Document 2).

JP-A-7-183107 JP 2002-98514 A

  However, if a method of rotating the sensor in the circumferential direction (or rotating the cylindrical object to be measured) is applied during the machining process, the cylindrical object to be measured is stopped after the axial conveyance of the cylindrical object to be measured is stopped. The center position of the cross section of the cylindrical object to be measured must be approximately calculated by spiral scanning in which axial conveyance and circumferential rotation coexist. As a result, there has been a problem that the efficiency of the machining process is lowered due to the stoppage or the speed reduction of the conveyance, or the measurement accuracy is lowered by scanning the sensor spirally. Moreover, even if the center position in a certain cross section is calculated due to the swing of the columnar object being measured, the center position cannot be used over the entire length of the columnar object. Even if a method of arranging a large number of sensors in the circumferential direction instead of rotating the sensors is used, there are problems such as a large dimensional constraint placing a large number of high-precision sensors on the same plane. is there.

  For this reason, a measurement method that does not require alignment work is desired as a method for measuring the cross-sectional shape with high accuracy without stopping the conveyance of the cylindrical object to be measured even during measurement during the machining process. Yes.

  The present invention has been made in view of the above, and provides a method and an apparatus capable of measuring the outer diameter of a columnar object to be measured with high accuracy without performing a centering operation.

  In order to solve the above-described problems and achieve the object, an outer diameter measuring method according to the present invention includes first, second, and third displacement sensors on a plane to which a circumferential cross section of a cylindrical measurement object belongs. Is an outer diameter measuring method using an outer diameter measuring device in which a radial displacement of a reference cylindrical object whose radius is known is determined by the first, second and third displacement sensors, respectively. A first measurement step for measuring, a first storage step for storing the measurement values measured in the first measurement step as first, second, and third measurement values, respectively, and the radius are unknown A second measurement step of measuring a radial displacement of the cylindrical measurement object as fourth, fifth, and sixth measurement values by the first, second, and third displacement sensors, respectively; The first stored in the first storage step Calculation for calculating the radius of the cylindrical measured object from the second and third measured values, the fourth, fifth and sixth measured values and the radius of the reference cylindrical measured object And a step.

  In order to solve the above-described problems and achieve the object, an outer diameter measuring apparatus according to the present invention includes first, second, and third arranged on a plane to which a circumferential cross section of a cylindrical object to be measured belongs. First, second, and third measurement values obtained by measuring the displacement in the radial direction of the displacement sensor and the reference cylindrical object to be measured whose radius is known by the first, second, and third displacement sensors, respectively. The first, second, and third storage means for storing data and the displacement in the radial direction of the cylindrical object to be measured whose radius is unknown are measured by the first, second, and third displacement sensors, respectively. Fourth, fifth, and sixth storage means for storing fourth, fifth, and sixth measurement values, the first, second, and third measurement values, and the fourth, fifth And the sixth measured value and the radius of the reference cylindrical measured object, the cylindrical measured object Characterized in that it comprises calculating means for calculating the radius, a.

  The outer diameter measuring method and the outer diameter measuring apparatus according to the present invention have an effect that the outer diameter of the cylindrical measurement object can be measured with high accuracy without performing a centering operation.

FIG. 1 is a diagram for explaining the arrangement of a cylindrical object to be measured and a transmitted light displacement sensor in the three-point method. FIG. 2 is a diagram for explaining measured values of the transmitted light displacement sensor. FIG. 3 is a diagram for explaining measurement in a state in which the center of the cylindrical measurement object does not coincide with the center of the measurement system. FIG. 4 is a schematic diagram showing the configuration of the outer diameter measuring apparatus according to the embodiment of the present invention. FIG. 5 is a flowchart showing the procedure of the outer diameter measuring method according to the embodiment of the present invention. FIG. 6 is a diagram showing a measurement example by the outer diameter measurement method according to the embodiment of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

[Measurement principle]
First, before describing the embodiment of the present invention, the measurement principle of the present invention will be described. In the following description, since the radius when the cross-sectional shape of the object to be measured is assumed to be a cylinder or a cylinder is calculated, this value is referred to as an equivalent radius, which is referred to as a radius for the sake of simplicity.

  FIG. 1 is a diagram showing the arrangement of a transmitted light type displacement sensor and a cylindrical object to be measured for measuring the outer diameter of a cylindrical object to be measured by a three-point method using a transmitted light type displacement sensor. FIG. 2 is a diagram for explaining measurement values measured by the transmitted light displacement sensor in FIG. In FIG. 2, only the first displacement sensor 1 is illustrated and described for the sake of simplicity, but the same description holds for the second displacement sensor 2 and the third displacement sensor 3.

As shown in FIG. 1, in the three-point method using a transmitted light type displacement sensor, the first displacement sensor 1 and the second displacement sensor arranged on the plane to which the circumferential cross section of the cylindrical object A belongs. 2 and the third displacement sensor 3 are used. The first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 include light projecting units 11, 21, 31 and light receiving units 12, 22, 32, respectively.
They are arranged so as to measure the displacement of the cylindrical object A in the radial directions of predetermined angles θ ₁ , θ ₂ , and θ ₃ from the direction of the reference radius (the x-axis direction in FIG. 1).

As shown in FIG. 2, the first displacement sensor 1, which is a transmitted light type displacement sensor, includes a light projecting unit 11 and a light receiving unit 12, and images parallel light 13 emitted from the light projecting unit 11 inside the light receiving unit 12. The element 14 is configured to detect. At this time, when the cylindrical measurement object A blocks a part of the parallel light 13, the image sensor 14 in the light receiving unit 12 detects the size s ₁ of the shadow 15 caused by the cylindrical measurement object A. Thus, the displacement in the radial direction of the cylindrical object A is measured.

Therefore, when the size s ₁ of the shadow 15 detected by the image sensor 14 is the measurement value s ₁ of the first displacement sensor 1, the radius R of the cylindrical object A is parallel light from the center O of the measurement system. R = s ₁ + o ₁ can be expressed using an offset amount o ₁ that is a distance to 13.

と表される。ただし、ｏ_１，ｏ_２，ｏ_３は、各変位センサ１，２，３のオフセット量である。 Similarly, since the description using FIG. 2 also applies to the second displacement sensor 2 and the third displacement sensor 3, the radius R of the cylindrical object A, the first displacement sensor 1, and the second displacement sensor. 2 and the respective measured values s ₁ , s ₂ , s _{3 of} the third displacement sensor 3 are:

It is expressed. However, o ₁ , o ₂ , and o ₃ are offset amounts of the displacement sensors 1, ₂ , and ₃ .

As described above, in the three-point method, if the offset amounts o ₁ , o ₂ , and o ₃ are measured in advance, the radius R of the cylindrical object A can be measured using [Equation 1]. . However, in order to satisfy the above-described [Expression 1], it is premised that the center O ′ of the columnar object A is coincident with the center O of the measurement system. It is difficult to match the center O ′ of the cylindrical object A during conveyance with the center O of the measurement system.

となり、ずれ量（ｐ，ｑ）を含んだ量となってしまう。しかも、このずれ量（ｐ，ｑ）は、円柱状被測定体Ａの搬送中に時々刻々と変化する量であり、一度このずれ量を測定したとしても、このずれ量を恒久的に使用することはできない。 As a result, when measuring the cylindrical object A during conveyance, as shown in FIG. 3, the column O is not aligned with the center O ′ of the cylindrical object A and the center O of the measurement system. The measurement object A is measured. That is, when the amount of deviation between the center O ′ of the cylindrical object to be measured A and the center O of the measurement system is represented by (p, q), the radius R of the cylindrical object to be measured A, the first displacement sensor 1, and the first. The relationship between the measured values s ₁ , s ₂ , and s ₃ of the second displacement sensor 2 and the third displacement sensor 3 is as follows:

Thus, the amount includes the shift amount (p, q). Moreover, this deviation amount (p, q) is an amount that changes every moment during the conveyance of the cylindrical object A, and even if this deviation amount is measured once, this deviation amount is used permanently. It is not possible.

  Therefore, in order to eliminate the influence of the shift amount (p, q) from [Equation 2], the following equation modification is considered.

を満たす（ｗ_１，ｗ_２)があれば、以下の〔式４〕のように、ずれ量（ｐ，ｑ）を消去することができることが解る。

First,

If there is (w ₁ , w ₂ ) that satisfies the condition, it is understood that the shift amount (p, q) can be erased as in the following [Equation 4].

Further, when [Equation 4] is arranged, the radius R of the columnar object A and the measured values s ₁ , s ₂ , s ₁ , s ₂ , the relationship between the s ₃ is as follows.

Here, the right side of [Formula 5] includes the offset amounts o ₁ , o ₂ , and o ₃ of the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3. However, these offset amounts o ₁ , o ₂ , and o ₃ can be erased by the measured values of the reference cylindrical object to be measured whose radius R ₀ is known by the following method.

First, measured values s ₁ , s ₂ , and s ₃ of the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 with respect to a reference cylindrical object to be measured whose radius R ₀ is already known. Get it. That is, the following equation is established with the radius R ₀ and the measured values s ₁ , s ₂ , and s _{3 of the} reference cylindrical object to be measured.

On the other hand, the cylindrical object to be measured A whose radius R is unknown is measured. When the measured values of the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 in this measurement are m ₁ , m ₂ , and m ₃ , the following equation is established.

Then, by taking the difference between [Expression 6] and [Expression 7], the offset amounts o ₁ , o ₂ , and o ₃ can be eliminated, and the following expression is obtained.

That is, it can be seen from [Equation 8] that if there is (w ₁ , w ₂ ) satisfying [Equation 3], a method of calculating the radius R of the cylindrical object A that has been unknown can be obtained.

というように、第１の変位センサ１、第２の変位センサ２、および第３の変位センサ３が測定する変位の半径方向の角度（θ₁,θ₂,θ₃）により一意に求めることができることが解る。なお、上記説明ではθ₁,θ₂,θ₃を図１におけるｘ軸を基準半径とした角度として説明したが、ｘ軸以外を基準半径としてθ₁,θ₂,θ₃を定めても、〔式９〕における（ｗ_１，ｗ_２)は不変である。 By the way, (w ₁ , w ₂ ) satisfying [Equation 3] is obtained by obtaining an inverse matrix of a coefficient matrix,

In this way, the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 can be uniquely determined by the radial angles (θ ₁ , θ ₂ , θ ₃ ) measured by the displacement. I understand what I can do. In the above description, θ ₁ , θ ₂ , and θ ₃ are described as angles with the x axis in FIG. 1 as the reference radius, but even if θ ₁ , θ ₂ , and θ ₃ are defined with reference radius other than the x axis, (W ₁ , w ₂ ) in [Formula 9] is unchanged.

  Therefore, regardless of how the reference radius is taken, [Equation 8] is uniquely determined by the angle of the displacement direction measured by the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3. It can be said that it is a function determined by.

Moreover, the measured values s ₁ , s ₂ and s ₃ for the reference cylindrical object to be measured, the radius R _{0 of the} reference cylindrical object to be measured, and the measured value m ₁ for the cylindrical object to be measured A in this function [Equation 8]. It was derived that the radius R of the cylindrical object A can be calculated by substituting m ₂ and m ₃ .

In the above measurement principle, an example of a transmitted light type displacement sensor is used as the displacement sensor. However, the displacement is not limited to the transmitted light type displacement sensor, and the shift amount (p, q) and the offset o ₁ as in [Expression 2]. , O ₂ , o ₃ can be appropriately applied.

[Outer diameter measuring device]
Next, the outer diameter measuring device 4 according to the embodiment of the present invention will be described.

  FIG. 4 is a schematic diagram showing the configuration of the outer diameter measuring device 4 according to the embodiment of the present invention. As shown in FIG. 4, the outer diameter measuring device 4 according to the embodiment of the present invention includes a sensor unit 5, a storage unit 6, a calculation unit 7, a display unit 8, an input unit 9, and an A / D converter 16. 26, 36.

The sensor unit 5 includes a first displacement sensor 1, a second displacement sensor 2, and a third displacement sensor 3 inside, and the internal arrangement thereof is as described with reference to FIG. 1. That is, the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 include the light projecting units 11, 21, 31 and the light receiving units 12, 22, 32, respectively, and the direction of the reference radius They are arranged so as to measure the displacement of the cylindrical object to be measured A in the radial directions of predetermined angles θ ₁ , θ ₂ , and θ ₃ from (in the x-axis direction in FIG. 1).

  The first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 inside the sensor unit 5 are connected to the arithmetic unit 7 via the A / D converters 16, 26, and 36, respectively. It is connected. Further, the storage unit 6 is configured to store the measurement values of the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 input via the calculation unit 7.

The storage unit 6 stores the measured values of the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 based on the reference columnar measured object whose radius R ₀ is known and the radius R unknown. A certain columnar object to be measured can be stored independently. That is, the storage unit 6 stores the measured values s ₁ , s ₂ , s ₃ , m ₁ , m ₂ , measured by the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3, respectively. first storing the m _3, the second, third, and functions as a fourth, fifth, and sixth storage means. Note that these storage means do not need to be physically separated storage means, and may be realized by storing the measured values in the storage unit 6 as independent variables.

The calculation unit 7 calculates the measured values s ₁ , s ₂ , s ₃ , m ₁ , m ₂ , m ₃ measured by the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3. Thus, it is possible to perform reading and writing control to the storage unit 6. Further, the calculation unit 7 is formed in a cylindrical shape based on [Equation 8] from the measured values s ₁ , s ₂ , s ₃ , m ₁ , m ₂ , m ₃ and the known radius R ₀ stored in the storage unit 6. An operation for calculating the radius of the object to be measured is performed. For example, the calculation unit 7 can be configured by a calculation element such as a ROM or a PLD, or a program executed on the MPU.

  The display unit 8 is connected to the calculation unit 7 and displays the radius of the columnar object to be measured calculated by the calculation unit 7 and other information necessary for the operation of the outer diameter measuring device 4.

The input unit 9 can be configured by a general user interface such as a keyboard connected to the calculation unit 7, and is operated when the operator inputs a known radius _R0 of the reference cylindrical object to be measured. Further, in a configuration in which the operator can change the attachment positions of the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3, the angle (θ ₁ , θ ₂ , θ ₃ ) can also be used by the operator for input by the input unit 9. In the configuration in which the attachment positions of the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 are not changed, the attachment angle of each displacement sensor (or the cancel coefficient (w ₁₎ that is uniquely determined from now on). , W ₂ )) as a preset value may be stored in the storage unit 6 or the calculation unit 7.

  In the example of the outer diameter measuring device 4 described above, the case of three displacement sensors has been described. However, by disposing a plurality of displacement sensors at different angles in the circumferential direction, finer measurement is possible. Is natural.

[Outer diameter measurement method]
Next, an outer diameter measuring method for measuring the radius R of the cylindrical object A according to the above-described measurement principle will be described. In the following description, an outer diameter measuring method using the outer diameter measuring device 4 will be described, but the present invention is not limited to the configuration of the outer diameter measuring device 4.

  FIG. 5 is a flowchart showing the procedure of the outer diameter measuring method according to the embodiment of the present invention. As shown in FIG. 5, the outer diameter measuring method according to the embodiment of the present invention performs initial setting immediately after the start (step S1).

In the initial setting (step S1), the operator of the outer diameter measuring device 4 is an operation of inputting the known radius _R0 of the reference cylindrical object to be measured to the input unit 9. Furthermore, in the configuration in which the mounting angle of the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 can be changed, the direction of displacement measured by the displacement sensors 1, 2, 3 by the operator Can also be entered. Note that the initial setting can be omitted as appropriate by storing the initial setting value in the storage unit 6.

Next, the reference cylindrical object to be measured is set in the outer diameter measuring device 4, and the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 are the reference cylindrical object to be measured. Measurement is performed (step S2). The measurement here is not the measurement of the radius of the reference cylindrical object to be measured, but the measured values s ₁ , ₁ by the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3. It means obtaining s ₂ and s ₃ . Then, the calculation unit 7 of the outer diameter measuring device 4 stores the measured values s ₁ , s ₂ , and s ₃ obtained by the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 in the storage unit 6. (Step S3).

The measurement of the reference cylindrical object to be measured (step S2) and the storage of the measurement value (step S3) may be executed for each measurement of the cylindrical object to be measured A whose radius R is unknown. By saving the values s ₁ , s ₂ , and s ₃ in the storage unit 6 and using the measured values s ₁ , s ₂ , and s ₃ next time, the execution frequency can be appropriately omitted.

Next, the columnar object A to be measured is set in the outer diameter measuring device 4, and the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3 are formed in a columnar shape. The measurement object A is measured (step S4). Note that the measurement here is not the measurement of the radius of the columnar object A itself, but the measurement values m ₁ , m ₁ , the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3. It means obtaining m ₂ and m ₃ . Then, the calculation unit 7 stores the measured values m ₁ , m ₂ , and m ₃ of the cylindrical measurement object A by the first displacement sensor 1, the second displacement sensor 2, and the third displacement sensor 3. (Step S5).

Thereafter, the calculation unit 7 measures the measured values s ₁ , s ₂ , s ₃ for the reference cylindrical measurement object stored in the storage unit 6, the radius R _{0 of the} reference cylindrical measurement object, and the cylindrical measurement object. From the measured values m ₁ , m ₂ , and m ₃ for A, the radius R of the cylindrical object to be measured A is calculated (step S6). In this calculation, the calculation unit 7 can calculate the radius R of the cylindrical object A by using the above [Equation 8].

In the above embodiment, the arithmetic unit 7 measurements _{m 1,} m 2, and _{m 3} after storing in the storage unit 6, the stored measured values _{m 1,} m 2, _{m 3} with a cylindrical object to be measured A The method of calculating the radius R of the above has been described. However, an embodiment in which the calculation unit 7 calculates the radius R of the cylindrical object A by directly using the measurement values m ₁ , m ₂ , and m ₃ is also possible.

  Note that the radius R of the columnar object A measured by the outer diameter measuring method may be displayed on the display unit 8 of the outer diameter measuring device 4. When the radius R of the cylindrical object A is measured during the machining process, the value of the measured radius R of the cylindrical object A is fed back to the rolling process and the correction process to adjust the machining process. It is good also as a structure to utilize.

  As described above, in the outer diameter measuring method according to the embodiment of the present invention, the first, second, and third displacement sensors respectively measure the radial displacement of the reference cylindrical object to be measured whose radius is known. 1 measurement step, a first storage step for storing the measurement values measured in the first measurement step as first, second, and third measurement values, respectively, and a cylindrical measurement object having an unknown radius A second measurement step for measuring the radial displacement of the body by the first, second, and third displacement sensors, respectively, and the measurement values measured in the second measurement step, respectively, for the fourth, fifth, and A second storage step for storing as a sixth measurement value; first, second, and third measurement values; fourth, fifth, and sixth measurement values; and a reference cylindrical object to be measured Calculate the radius of the cylindrical object to be measured from the radius. A step, by including, without the alignment operation can be measured outside diameter of the cylindrical body to be measured with high accuracy. That is, the outer diameter measuring method according to the embodiment of the present invention does not need to be centered, so that even if the outer diameter is measured during the processing step, there is no obstacle to the processing step.

[Measurement example]
Finally, in order to demonstrate the effect of the present invention, a measurement example in which measurement is performed by the outer diameter measurement method according to the embodiment of the present invention will be described.

The table and graph shown in FIG. 6 are obtained by calibrating an outer diameter measuring device with a pin gauge having a radius of 10.00 mm and measuring a pin gauge having a radius of 15.00 mm as an object to be measured. The measurement conditions of this measurement example are that the object to be measured is fixed in a stationary state, the center of the measurement system of the outer diameter measuring device (O in the example of FIG. 3) and the center of the pin gauge that is the object of measurement (example of FIG. 3) Then, O ′) is moved in the range of ± 4 mm in the y-axis direction at intervals of 1 mm, and the radius of the object to be measured is measured twice. In addition, the mounting angles of the first displacement sensor, the second displacement sensor, and the third displacement sensor of the outer diameter measuring apparatus in this measurement are θ ₁ = 60 ° and θ ₂ = 180 °, respectively, with respect to the x axis. , Θ ₃ = 300 °.

  As can be seen from FIG. 6, the measurement error between the true value and the measured value when the center of the object to be measured coincides with the reference position is as small as 0.2 μm, and the object to be measured is within a range of ± 4 mm from the reference position. Even when moved by, the variation of the measured value is within ± 2.5 μm. As described above, according to the outer diameter measuring method according to the present invention, it is possible to measure the outer diameter with high accuracy by a simple measuring method, and the outer diameter with high accuracy that is very little affected by the swing of the object to be measured. Measurement is possible. As shown in the result of the measurement example in FIG. 6, a slight non-linear error remains with respect to the sway of the object to be measured. However, a correction method using linear or polynomial regression generally used for measuring instrument calibration is used. By using it together, it is possible to remove this non-linear error and further improve the accuracy.

DESCRIPTION OF SYMBOLS 1 1st displacement sensor 2 2nd displacement sensor 3 3rd displacement sensor 4 Outer diameter measuring apparatus 5 Sensor unit 6 Memory | storage part 7 Calculation part 8 Display part 9 Input part 11 Light projection part 12 Light reception part 21 Light projection part 22 Light receiver 31 Emitter 32 Light receiver

Claims (3)

An outer diameter measuring method using an outer diameter measuring device in which first, second, and third displacement sensors are arranged on a plane to which a circumferential cross section of a cylindrical measurement object belongs,
A first measurement step of measuring a radial displacement of a reference cylindrical measurement object having a known radius by the first, second and third displacement sensors, respectively;
A first storage step for storing the measurement values measured in the first measurement step as first, second, and third measurement values, respectively;
A second displacement is measured by the first, second, and third displacement sensors as the fourth, fifth, and sixth measured values, respectively, of the cylindrical object to be measured whose radius is unknown. Measuring steps;
A second storage step for storing the fourth, fifth and sixth measurement values respectively measured in the second measurement step;
The function shown below determined by the angle of the displacement direction measured by the first, second, and third displacement sensors, and the radius stored in the first cylindrical measurement object and the first memory step stored in the first storage step. By substituting the first, second, and third measurement values and the fourth, fifth, and sixth measurement values stored in the second storage step, the radius of the cylindrical object to be measured A calculation step for calculating
The outer diameter measuring method characterized by including.

Here, s ₁ , s ₂ , and s ₃ are the first, second, and third measured values, respectively, and m ₁ , m ₂ , and m ₃ are the fourth, fifth, and sixth, respectively. , Θ ₁ , θ ₂ , θ ₃ are angles from a reference radius in the displacement direction measured by the first, second, and third displacement sensors, and R ₀ is the reference circle It is a radius of the columnar object to be measured, and w ₁ and w ₂ are values calculated in advance. The outer diameter measuring method according to claim 1 , wherein the displacement sensor is a transmitted light displacement sensor. A first displacement sensor, a second displacement sensor, and a third displacement sensor disposed on a plane to which a circumferential cross section of the cylindrical measurement object belongs;
The first, second, and third measured values obtained by measuring the radial displacement of the reference cylindrical object to be measured having a known radius by the first, second, and third displacement sensors, respectively, are stored. First, second and third storage means;
A fourth storage unit stores fourth, fifth, and sixth measurement values obtained by measuring the displacement in the radial direction of the cylindrical measurement object having an unknown radius by the first, second, and third displacement sensors, respectively. , Fifth and sixth storage means;
The radius of the reference cylindrical object to be measured and the first, second, and third memories are defined in the following functions determined by the angle of the displacement direction measured by the first, second, and third displacement sensors. The first, second and third measurements stored in the means and the fourth, fifth and sixth measurements stored in the fourth, fifth and sixth storage means Calculating means for calculating a radius of the cylindrical measurement object by substituting a value ;
An outer diameter measuring device comprising:

Here, s ₁ , s ₂ , and s ₃ are the first, second, and third measured values, respectively, and m ₁ , m ₂ , and m ₃ are the fourth, fifth, and sixth, respectively. , Θ ₁ , θ ₂ , θ ₃ are angles from a reference radius in the displacement direction measured by the first, second, and third displacement sensors, and R ₀ is the reference circle It is a radius of the columnar object to be measured, and w ₁ and w ₂ are values calculated in advance.

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