An indirect measurement method for steel pipe concentricity

Abstract

The present invention discloses an indirect method for measuring the concentricity of a steel pipe, comprising the following steps: fixing the steel pipe to be tested and rotating it; installing a transmission-type optical fiber assembly and adjusting its position; moving the transmission-type optical fiber assembly to calculate the concentricity of the steel pipe at different positions on the steel pipe to be tested; and selecting the maximum concentricity as the coaxiality error result for the steel pipe to be tested. This method can replace manual quality testing of seamless steel pipes, saving manpower and improving testing efficiency and accuracy.

Description

Technical Field

[0001] The present invention relates to the field of steel pipe detection, and in particular to a method for indirectly measuring the concentricity of a steel pipe. Background Art

[0002] As a typical cross-section steel material, seamless steel pipe is widely used in mechanical components such as oil drill pipe and drive shafts. With the gradual advancement of industrial upgrading, the demand for the quality of seamless steel pipe supply is becoming increasingly higher. Currently, most steel pipe manufacturers still use handheld equipment to test seamless steel pipe quality, which makes it difficult to ensure inspection efficiency, cost, and ultimate accuracy.

[0003] In actual production applications, for some larger production and processing manufacturers, using employees' handheld devices to conduct quality inspections on each steel pipe one by one consumes more human resources and has low work efficiency. Moreover, the accuracy of manual inspections is difficult to be effectively guaranteed, thus affecting the quality of seamless steel pipe products. Summary of the Invention

[0004] The purpose of the present invention is to provide an indirect measurement method for the concentricity of a steel pipe. The present invention can replace manual inspection of the quality of seamless steel pipes, saving manpower and improving the efficiency and accuracy of inspection.

[0005] The technical solution of the present invention is a method for indirectly measuring the concentricity of a steel pipe, comprising the following steps:

[0006] S1: Fix the steel pipe to be tested and rotate it;

[0007] S2: Install the transmission area optical fiber group and adjust the position of the transmission area optical fiber group;

[0008] S3: Move the optical fiber group in the transmission area to calculate the concentricity of the steel pipe at different positions;

[0009] S4: Select the maximum concentricity of the steel pipe as the coaxiality error result of the steel pipe to be tested.

[0010] In the aforementioned indirect measurement method for the concentricity of a steel pipe, adjusting the position of the optical fiber group in the transmission region includes:

[0011] The transmitting optical fiber and the receiving optical fiber of the transmission area optical fiber group are respectively located at the front and rear sides of the steel pipe;

[0012] The optical fiber group in the transmission area is partially blocked by the steel pipe.

[0013] In the aforementioned indirect measurement method for steel pipe concentricity, the calculation of the steel pipe concentricity at different positions of the steel pipe to be measured includes:

[0014] The optical fiber group in the transmission area is moved to the top, middle and bottom of the steel pipe, the light flux is amplified by the optical fiber amplifier, and the light flux timing signal is recorded by the acquisition device. Then, the concentricity of the steel pipe at the top, middle and bottom of the steel pipe is calculated respectively.

[0015] In the aforementioned indirect measurement method for steel pipe concentricity, the calculation method of the steel pipe concentricity includes:

[0016] Calculate the Fourier transform of the luminous flux time series signal and set the low-frequency component of the luminous flux time series signal to zero;

[0017] Calculate the energy sparseness ratio of the Fourier transform of the light flux time series signal;

[0018] The concentricity of the steel pipe is indirectly calculated based on the energy dilution ratio.

[0019] In the aforementioned indirect measurement method for the concentricity of steel pipes, the calculation formula for the Fourier transform of the light flux time series signal is:

[0020]

[0021] Where X is the frequency domain component after Fourier transform, abs(·) is the absolute value calculation symbol, N is the number of points of the time domain discrete signal, m is the number of the frequency domain signal, p is the threshold of the low-frequency component, x(n) is the obtained luminous flux time series signal, and n is the index number of the time domain discrete signal.

[0022] In the aforementioned indirect measurement method for steel pipe concentricity, the calculation formula for the energy dilution ratio is:

[0023]

[0024] Where SM is the signal sparsity ratio, N is the length of the time domain signal, is the average value of the time domain signal, X is the frequency domain component after Fourier transform, Y is the frequency domain component after Fourier transform of the reference rod luminous flux time series signal, and i is the index number of the frequency domain component after Fourier transform.

[0025] In the aforementioned indirect measurement method for steel pipe concentricity, the calculation formula for the steel pipe concentricity is:

[0026] C = kSM + b;

[0027] Among them, C is the concentricity of the steel pipe, SM is the signal sparse ratio, and k and b are two preset concentricity adjustment coefficients.

[0028] In the aforementioned indirect measurement method for steel pipe concentricity, the calculation formula for the coaxiality error result is:

[0029] C C=max[C1,C2,C3];

[0030] Among them, C C is the coaxiality error of the seamless steel pipe, and C1, C2, and C3 are the concentricity of the seamless steel pipe at the top, middle, and bottom, respectively.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] In the present invention, the steel pipe to be tested is fixed and rotated at a certain speed, and then a transmission area optical fiber group is set to emit optical fiber to the steel pipe. Then, the position of the transmission area optical fiber group is moved and the light flux timing signal is collected. The concentricity of the steel pipe at different positions is calculated according to the light flux timing signal, and finally the largest steel pipe concentricity is selected as the coaxiality error result of the steel pipe to be tested. The above method can replace manual labor to realize the quality inspection of the steel pipe. The quality of the seamless steel pipe can be detected by the change of the light flux, which saves manpower and has higher detection efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flow chart of the indirect measurement method of the present invention;

[0034] Figure 2 Schematic diagram of the reference signal of the luminous flux timing signal in the present invention;

[0035] Figure 3 is a schematic diagram of a luminous flux timing signal obtained in Example 1 of the present invention;

[0036] Figure 4 Schematic diagram of Fourier transform for obtaining a luminous flux timing signal in Example 1 of the present invention;

[0037] Figure 5 is a schematic diagram of a luminous flux timing signal obtained in Example 2 of the present invention;

[0038] Figure 6 Schematic diagram of Fourier transform for obtaining luminous flux timing signal in embodiment 2 of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the accompanying drawings and examples, but they are not intended to limit the present invention.

[0040] Example 1: A method for indirect measurement of steel pipe concentricity, as shown in the attached Figure 1 As shown, the following steps are included:

[0041] S1: Fix the steel pipe to be tested and rotate it. The rotation speed can be adjusted as needed.

[0042] S2: Installing the transmission area optical fiber assembly and adjusting the position of the transmission area optical fiber assembly. Adjusting the position of the transmission area optical fiber assembly includes: positioning the transmitting optical fiber and the receiving optical fiber of the transmission area optical fiber assembly at the front and rear sides of the steel pipe, respectively; and partially shielding the transmission area optical fiber assembly by the steel pipe. Preferably, approximately half of the transmission area optical fiber assembly is shielded by the steel pipe.

[0043] S3: Move the optical fiber group in the transmission area to calculate the concentricity of the steel pipe at different positions of the steel pipe to be tested. Calculating the concentricity of the steel pipe at different positions of the steel pipe to be tested includes: moving the optical fiber group in the transmission area to the top, middle and bottom of the steel pipe, amplifying the light flux through the optical fiber amplifier, and recording the light flux time series signal through the acquisition device, and then calculating the concentricity of the steel pipe at the top, middle and bottom of the steel pipe respectively. In this embodiment, the sampling frequency of the signal is 10800Hz, and the sampled light flux time series signal is as shown in the attached figure. Figure 3 As shown;

[0044] The calculation method of the steel pipe concentricity includes:

[0045] Calculate the Fourier transform of the luminous flux time series signal and set the low-frequency component of the luminous flux time series signal to zero, as shown in the attached figure. Figure 4 As shown, the calculation formula of the Fourier transform of the luminous flux time series signal is:

[0046]

[0047] Wherein, X is the frequency domain component after Fourier transformation, abs(·) is the absolute value calculation symbol, N is the number of points of the time domain discrete signal, m is the number of the frequency domain signal, p is the threshold of the low-frequency component. In this embodiment, the threshold of the low-frequency component is 10, x(n) is the acquired luminous flux time series signal, and n is the index number of the time domain discrete signal;

[0048] The energy sparse ratio of the Fourier transform of the luminous flux time series signal is calculated. The calculation formula of the energy sparse ratio is:

[0049]

[0050] Where SM is the signal sparsity ratio, N is the length of the time domain signal, is the average value of the time domain signal, X is the frequency domain component after Fourier transformation, Y is the frequency domain component after Fourier transformation of the reference rod luminous flux time series signal, i is the index number of the frequency domain component after Fourier transformation, and the reference signal of the luminous flux time series signal is as shown in the attached figure. Figure 2 As shown;

[0051] The concentricity of the steel pipe is indirectly calculated based on the energy dilution ratio. The calculation formula of the concentricity of the steel pipe is:

[0052] C = kSM + b;

[0053] Wherein, C is the concentricity of the steel pipe, SM is the signal rarefaction ratio, k and b are two preset concentricity adjustment coefficients, respectively. In this embodiment, k = 0.001, b = 0.01, and the signal rarefaction ratios at the three measurement positions are 0.3932, 0.5061, and 0.7856, respectively. The corresponding steel pipe concentricities are 0.0104, 0.0105, and 0.0108, respectively.

[0054] S4: Select the maximum concentricity of the steel pipe as the coaxiality error result of the steel pipe to be tested. The calculation formula of the coaxiality error result is:

[0055] C C =max[C1,C2,C3];

[0056] Among them, C C is the coaxiality error of the seamless steel pipe, C1, C2, and C3 are the concentricity of the top, middle, and bottom of the seamless steel pipe, respectively. In this embodiment, the final coaxiality error result of the steel pipe to be tested is 0.0108.

[0057] Example 2: A method for indirect measurement of steel pipe concentricity, as shown in the attached Figure 1 As shown, the following steps are included:

[0058] S1: Fix the steel pipe to be tested and rotate it. The rotation speed can be adjusted as needed.

[0059] S2: Installing the transmission area optical fiber assembly and adjusting the position of the transmission area optical fiber assembly. Adjusting the position of the transmission area optical fiber assembly includes: positioning the transmitting optical fiber and the receiving optical fiber of the transmission area optical fiber assembly at the front and rear sides of the steel pipe, respectively; and partially shielding the transmission area optical fiber assembly by the steel pipe. Preferably, approximately half of the transmission area optical fiber assembly is shielded by the steel pipe.

[0060] S3: Move the optical fiber group in the transmission area to calculate the concentricity of the steel pipe at different positions of the steel pipe to be tested. Calculating the concentricity of the steel pipe at different positions of the steel pipe to be tested includes: moving the optical fiber group in the transmission area to the top, middle and bottom of the steel pipe, amplifying the light flux through the optical fiber amplifier, and recording the light flux time series signal through the acquisition device, and then calculating the concentricity of the steel pipe at the top, middle and bottom of the steel pipe respectively. In this embodiment, the sampling frequency of the signal is 10800Hz, and the sampled light flux time series signal is as shown in the attached figure. Figure 5 As shown;

[0061] The calculation method of the steel pipe concentricity includes:

[0062] Calculate the Fourier transform of the luminous flux time series signal and set the low-frequency component of the luminous flux time series signal to zero, as shown in the attached figure. Figure 6As shown, the calculation formula of the Fourier transform of the luminous flux time series signal is:

[0063]

[0064] Wherein, X is the frequency domain component after Fourier transformation, abs(·) is the absolute value calculation symbol, N is the number of points of the time domain discrete signal, m is the number of the frequency domain signal, p is the threshold of the low-frequency component. In this embodiment, the threshold of the low-frequency component is 10, x(n) is the acquired luminous flux time series signal, and n is the index number of the time domain discrete signal;

[0065] The energy sparse ratio of the Fourier transform of the luminous flux time series signal is calculated. The calculation formula of the energy sparse ratio is:

[0066]

[0067] Where SM is the signal sparsity ratio, N is the length of the time domain signal, is the average value of the time domain signal, X is the frequency domain component after Fourier transformation, Y is the frequency domain component after Fourier transformation of the reference rod luminous flux time series signal, i is the index number of the frequency domain component after Fourier transformation, and the reference signal of the luminous flux time series signal is as shown in the attached figure. Figure 2 As shown;

[0068] The concentricity of the steel pipe is indirectly calculated based on the energy dilution ratio. The calculation formula of the concentricity of the steel pipe is:

[0069] C = kSM + b;

[0070] Wherein, C is the concentricity of the steel pipe, SM is the signal rarefaction ratio, k and b are two preset concentricity adjustment coefficients, respectively. In this embodiment, k = 0.001, b = 0.01, and the signal rarefaction ratios at the three measurement positions are 2.1050, 1.8001, and 1.5620, respectively. The corresponding steel pipe concentricities are 0.0120, 0.0118, and 0.0115, respectively.

[0071] S4: Select the maximum concentricity of the steel pipe as the coaxiality error result of the steel pipe to be tested. The calculation formula of the coaxiality error result is:

[0072] C C =max[C1,C2,C3];

[0073] Among them, C C is the coaxiality error of the seamless steel pipe, C1, C2, and C3 are the concentricity of the top, middle, and bottom of the seamless steel pipe, respectively. In this embodiment, the final coaxiality error result of the steel pipe to be tested is 0.0120.

Claims

1. A method for indirect measurement of steel pipe concentricity, characterized by: The following steps are involved: S1: Fix the steel pipe to be tested and rotate it; S2: Install the transmission area optical fiber group and adjust the position of the transmission area optical fiber group; S3: Move the optical fiber group in the transmission area to calculate the concentricity of the steel pipe at different positions; S4: Select the maximum concentricity of the steel pipe as the concentricity error result of the steel pipe to be tested; Calculation of the concentricity of the steel pipe at different positions of the steel pipe to be tested includes: Move the optical fiber group in the transmission area to the top, middle and bottom of the steel pipe, amplify the light flux through the optical fiber amplifier, and record the light flux time series signal through the acquisition device. Then, calculate the concentricity of the steel pipe at the top, middle and bottom respectively. The calculation method of the steel pipe concentricity includes: Calculate the Fourier transform of the luminous flux time series signal and set the low-frequency component of the luminous flux time series signal to zero; Calculate the energy sparseness ratio of the Fourier transform of the light flux time series signal; Indirect calculation of steel pipe concentricity based on energy dilution ratio; The calculation formula of the energy sparse ratio is: ； Among them, SM is the signal sparsity ratio, N is the length of the time domain signal, is the average value of the time domain signal, X is the frequency domain component after Fourier transform, Y is the frequency domain component after Fourier transform of the reference rod luminous flux time series signal, and i is the index number of the frequency domain component after Fourier transform.

2. The indirect measurement method for steel pipe concentricity according to claim 1, characterized in that: Adjusting the position of the optical fiber group in the transmission area includes: The transmitting optical fiber and the receiving optical fiber of the transmission area optical fiber group are respectively located at the front and rear sides of the steel pipe; The optical fiber group in the transmission area is partially blocked by the steel pipe.

3. The indirect measurement method for steel pipe concentricity according to claim 1, characterized in that: The calculation formula of the Fourier transform of the luminous flux time series signal is: ； Among them, X is the frequency domain component after Fourier transform, is the absolute value calculation symbol, N is the number of points of the time domain discrete signal, m is the number of the frequency domain signal, p is the threshold of the low-frequency component, is the acquired luminous flux timing signal, and n is the index number of the time domain discrete signal.

4. The indirect measurement method for steel pipe concentricity according to claim 1, characterized in that: The calculation formula of the steel pipe concentricity is: ； in, C is the concentricity of the steel pipe, SM is the signal sparsity ratio, k 、 b They are two preset concentricity adjustment coefficients.

5. The indirect measurement method for steel pipe concentricity according to claim 1, characterized in that: The calculation formula of the concentricity error result is: ； in, is the concentricity error of the seamless steel pipe, They are the concentricity of the seamless steel pipe at the top, middle and bottom respectively.

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