JPH1038555A - Method and device for measuring outer diameter and shape of steel pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously evaluate absolute radius and circularity by a method wherein a non-contact type distance sensor and an angle detecting device are fitted to a hollow cylinder, and a circumferential direction position of the hollow cylinder is measured while the radial distance between a substance to be measured and the distance sensor in the circumferential direction is measured, while eccentricity of the substance to be measured is corrected. SOLUTION: A primary standard having a diameter close to a steel pipe to be measured is set inside a cylinder of a rotary hollow roller with high precision, and the position of a non-contact distance sensor 2 is adjusted by sensor position moving means 7 and height adjustment mechanism 15, and thereafter, measurement instrument signals from a CPU are transmitted to a servo motor 6. The servo motor 6 rotates a high precision rotary hollow roller, and the non-contact distance sensor 2 on a rotary table 12 rotates around the reference primary standard, and a distance to an outer circumference of the reference primary standard is measured. Data are transmitted to the CPU together with a rotation angle measured by a rotary encoder via a slip ring to calculate a distance from a rotation center of the sensor. Next, an actual to-be-measured substance 1 is set to acquire the absolute radius.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring an outer diameter of a steel pipe, which measures an object to be measured such as a steel pipe in a wide range with an absolute radius using a sensor having a short measuring distance.

[0002]

2. Description of the Related Art A conventional method for measuring the outer diameter of a pipe such as a metal pipe is based on a diameter method, for example, using a caliper, a micrometer, or a light cutting method.
Shapes having the same outer diameter but different radii, that is, shapes such as equal diameter strain circles cannot be detected. This method is disclosed in, for example, Japanese Utility Model Publication No.
Although there is a method of measuring the diameter of a bar material over the entire circumference as disclosed in Japanese Patent No. 19253, an accurate contour shape cannot be grasped. In these methods, only the symmetric type can accurately grasp the shape, and is not suitable for accurate shape measurement.

FIG. 1B shows an example in which the third-order equal-diameter strain circle having the same outer diameter shown in FIG. 1C is measured by a diameter method. As described above, when the measurement is performed by the conventional diameter method, a measurement result as if the actual shape is a perfect circle may be obtained although the actual shape is not a perfect circle.

In the case of measurement by the radius method, if a sensor having a short measurement distance is used, the maximum radius of the object to be measured can be reduced.
It only displays the difference between the minimum radii as roundness,
There is a problem that the radius value itself cannot be measured. On the other hand, when a non-contact measurement using a laser distance sensor, a magnetic gap sensor, or the like is performed on a sensor having a long measurement distance, there is a problem in that high-resolution shape measurement cannot be performed because the resolution is low.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus for measuring the outer diameter of a steel pipe, which makes it possible to simultaneously evaluate the absolute radius and the roundness.

[0006]

SUMMARY OF THE INVENTION The present invention is as follows. (1) When measuring the outer diameter shape of a steel pipe, a non-contact type distance sensor and an angle detection device are attached to a hollow cylinder larger than the outer diameter of an object to be measured, and the circle of the hollow cylinder is detected by the angle detection. While measuring the circumferential position, the eccentricity of the measured object is corrected while measuring the radial distance between the measured object and the distance sensor in the circumferential direction, and the absolute value of each position of the measured object in the circumferential direction is measured. A method for measuring the outer diameter shape of a steel pipe, comprising calculating a radius. (2) A ring-shaped rotary that has a radial position adjustment table and a height adjustment table for a non-contact distance measurement sensor in a hollow cylinder that rotates with a high-precision bearing larger than the object to be measured, and is directly attached to the hollow cylinder. The angle detection by the encoder and the distance information from the measurement sensor synchronized with the angle are transmitted via a slip ring to an electric signal, and the CPU
The outer diameter shape measuring device for steel pipes that calculates the absolute radius by performing arithmetic processing according to.

That is, according to the present invention, the distance between the center of the reference prototype and the non-contact distance sensor is measured in advance by using a reference prototype having a diameter close to a steel pipe for measuring the outer diameter shape, and then, The reference prototype is removed, and a steel pipe whose shape is to be measured is mounted after the reference prototype, the distance between the non-contact distance sensor and the steel pipe is measured, and the radius of the steel pipe is measured from the measurement result.

In advance, the distance between the center of the reference prototype and the non-contact distance sensor is such that incident light from the distance sensor receives reflected light from the reference prototype and the radius of the reference prototype is known. Can be measured from Therefore, a steel pipe is attached in place of the reference prototype without changing the position of the distance sensor, the reflected light from the outer surface of the steel pipe is measured from the distance sensor, and the distance sensor circulates around the steel pipe, whereby the steel pipe is rotated. Is to measure the outer diameter shape.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, in order to make it possible to measure an absolute radius using a sensor having a short measuring distance, a reference prototype close to the radius of an object to be measured is measured, the position of the sensor is read, and the rotation center is read. From the position.

In this case, the reference prototype is defined as a cylinder having a known average size close to a perfect circle. Using the difference between the measured value of the measured object from the reference position and the measured object, the absolute value can be calculated when the measured object is measured. In addition, the absolute radius can be measured.

Further, the influence of the deviation (eccentricity) from the center of rotation of the object to be measured can be determined more precisely by removing the eccentricity term shown below by numerical processing. As a result, the shape of the object to be measured can be measured in polar coordinates, and the absolute shape can be measured together with accurate shape display.

A specific calculation method will be described below. The calculation method uses a method of measuring the radius r and the angle θ. The method for calculating the absolute radius is such that, for a sensor having a narrow measurement range, if the reference position of the sensor can be measured, the absolute radius of the cylinder within the measurement range can be obtained. FIG. 2 shows a schematic diagram of the calculation. First, a reference prototype r ₀ having a known radius close to the above-mentioned perfect circular shape is measured, and a value at a relative position of the sensor is obtained. (Here, it is assumed that there is no eccentricity, but the eccentricity is removed by the following method.) Next, when the measured object is measured and the difference between the sensor origin and the reference prototype is a ₀ ′, these 0 absolute radius value r _m = r ₀ + a ₀ average of the object to be measured from the difference in the next section '+ a ₀ can be calculated.

The eccentric term can be solved by correcting the deviation between the rotation center of the object to be measured and the rotation center of the sensor. Hereinafter, a specific calculation method will be described. Assuming that the sensor is rotated with the object to be measured fixed, assuming an arbitrary angle θ, the primary term a ₁ sin θ + b ₁ cos which is an eccentric component
The shape (relative radius) can be extracted by subtracting θ (dotted line in FIG. 2). Here, if it is measured every angle 360 / m ° (m: number of measurement points), It is.

By combining the above, shape measurement can be performed by measurement using an absolute radius as shown in the following equation. Assuming that the shape is ε (θ), ε (θ) = r ₀ + a ₀ ′ + a ₀ + r (θ) − (a ₀ + a
₍₁ sin θ + b ₁ cos θ) However, when the amount of eccentricity is large, it is necessary to perform correction by correcting θ by eccentricity.

As described above, according to the present invention, it is possible to remove the shape due to the influence of the eccentric component of the pipe by using a sensor having a short measuring distance, and to perform measurement using a known reference prototype. A very wide range of absolute radii can be measured, and circular shape measurement can be performed accurately and at low cost.

If a measuring device is added with a measuring device and a position sensor in the radial direction of the length measuring sensor is added so that the movement from the measuring device can be accurately recognized, the measurement of the measuring standard device for each movement of the sensor is omitted. It is also possible.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a front view of the embodiment of the present invention, and FIG. 4 is a side sectional view of the embodiment. This device mainly includes a housing 13, a height adjustment table 8, a high-precision rotary hollow roller 3, a rotary table 12, and a non-contact distance measuring sensor 2.

The height adjusting table 8 is arranged on the housing 13, and the height from the housing 13 can be adjusted by a height adjusting mechanism 15. The high-precision rotary hollow roller 3 is installed on the height adjustment table 8 via a high-precision bearing, and the driving force from the servo motor 6 also arranged on the height adjustment table 8 is transmitted by a driving force transmission mechanism 16.
Is transmitted via The rotation angle of the high-precision rotating hollow roller 3 can be detected by a rotary encoder 4. A rotary table 12 is provided beside the high-precision rotary hollow roller 3, and rotates integrally with the high-precision rotary hollow roller 3. The non-contact distance measuring sensor 2 is arranged on the turntable 12 so as to be movable in the radial direction by the sensor position moving means 7. The non-contact distance measuring sensor 2 is in contact with the slip ring 5 by a contact penetrating the rotary table 12, and supplies an input / output voltage or the like. Outputs from the non-contact distance measuring sensor 2 and the rotary encoder 4 are transmitted to the CPU, respectively, to calculate the shape of the steel pipe.

The CPU controls the servo motor 6. Furthermore, height adjustment mechanism 1
5 may be controlled by a CPU as a motor-driven mechanism. With such a structure, the height adjustment table 8 and the sensor position moving means 7 can be automatically set in position by feedback from the sensor.

A digital processing device 9 for the non-contact distance measuring sensor 2 and a digital processing device 9
A voltage stabilizer 10 for supplying power to the power supply is also provided.

A method for measuring the shape of a steel pipe using this apparatus will be described. First, a reference prototype whose diameter is close to the steel pipe to be measured is set inside the cylinder of the high-precision rotating hollow roller 3, and the position of the non-contact distance sensor 2 is adjusted by the sensor position moving means 7 and the height adjusting mechanism 15 as necessary. After adjusting,
A measurement command signal from the CPU is transmitted to the servo motor 6. The servo motor 6 rotates the high-precision rotary hollow roller 3, and the non-contact distance measuring sensor 2 on the rotary table 12 rotates around the reference prototype. The non-contact distance measuring sensor 2 measures the distance to the outer circumference of the reference prototype. The measured distance data is transmitted to the CPU via the slip ring 5 together with the rotation angle measured by the rotary encoder 4, and the distance from the rotation center of the sensor is calculated.
Next, if the object 1 such as a steel pipe to be actually measured is set and the distance L to the outer circumference of the steel pipe is measured, the dimensional shape based on the absolute radius can be grasped in accordance with the above-described calculation method.

With the apparatus and method described above, the outer diameter D = 75.
FIG. 4 shows a shape measurement result when a thin-walled electric resistance welded steel pipe having a thickness of t = 1.6 mm (t / D = 2.1%) having a thickness of 0 mm is formed with four divided rolls. 37.15mm radius for reference prototype
(Diameter: 74.3 mm) with a hole diameter of 37.13 mm.

FIG. 5 shows the upper part of the steel pipe and the right part shows the lower part of the steel pipe. The pipe dent due to the roll flange in the part between the rolls is caused by the displacement of the roll position,
In this way, it was possible to catch the shape defect (roll mark) of the pipe at the lower left.

[0024]

The method of the present invention makes it possible to measure the dimensions of pipes and their roundness on-line at low cost and with high accuracy in a fixed steel pipe line. This has an industrially beneficial effect in producing a steel pipe having a high hardness.

[Brief description of the drawings]

FIG. 1 is a comparison diagram between the conventional method and the method of the present invention.

FIG. 2 is an explanatory diagram of a shape extraction method by eccentricity correction and a comparison method to an absolute radius using a reference prototype.

FIG. 3 is a front view of the apparatus according to the embodiment of the present invention.

FIG. 4 is a side sectional view of an apparatus according to an embodiment of the present invention.

FIG. 5 is a table showing the results of measuring the shape of a steel pipe with the apparatus shown in FIGS. 3 and 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measurement object 2 Non-contact distance sensor 3 High precision rotating hollow cylindrical roller 4 Rotary encoder 5 Slip ring 6 Servo motor 7 Sensor position moving means 8 Height adjustment table 9 Digital processing device 10 Voltage stabilizer 12 Rotary table 13 Housing 15 Height Adjustment mechanism 16 Driving force transmission mechanism L Distance from sensor to outer circumference of steel pipe

Claims (2)

[Claims] When measuring the outer diameter shape of a steel pipe, a non-contact type distance sensor and an angle detecting device are attached to a hollow cylindrical body larger than the outer diameter of an object to be measured, and the hollow cylindrical body is detected by the angle detection. While measuring the circumferential position of the object, the eccentricity of the object to be measured is corrected while measuring the radial distance of the object to be measured and the distance sensor in the circumferential azimuth, and each position of the object to be measured in the circumferential direction is measured. A method for measuring an outer diameter shape of a steel pipe, wherein an absolute radius is calculated. 2. A ring-shaped cylinder having a radial position adjustment table and a height adjustment table of a non-contact distance measuring sensor mounted on a hollow cylinder rotating with a high-precision bearing larger than an object to be measured, and directly attached to the hollow cylinder. An outer diameter shape measuring device for a steel pipe, in which an angle is detected by a rotary encoder and distance information from a measurement sensor synchronized with the angle is transmitted as an electric signal via a slip ring, and an arithmetic process is performed by a CPU to calculate an absolute radius.