Ultrasonic detection method for quality of threaded brazed joint

Abstract

The invention belongs to the field of nondestructive testing, and relates to an ultrasonic testing method for the quality of a threaded brazed joint. According to the method, firstly, a comparison sample piece is installed to adjust the centering degree, detection sensitivity and detection parameters are adjusted through an ultrasonic transmitter-receiver, finally, a thread brazing assembly is installed to adjust the centering degree, and scanning imaging is conducted. According to the method, unwelded outer-layer parts of the threaded brazing assembly are used as comparison sample pieces; the probe is a water immersion focusing probe, the frequency ranges from 10 MHz to 25 MHz, the focal length ranges from 25 mm to 50 mm, the bandwidth of an ultrasonic transceiver is not lower than 25 MHz, an auxiliary centering device is adopted, and the probe is suitable for accurate centering of small-diameter rotary structures such as a thread brazing assembly and is particularly suitable for the thread brazing assembly which is of a hollow structure and is formed by brazing after internal and external threads with trapezoidal threads are screwed together.

Description

Technical Field

[0001] The invention belongs to the field of nondestructive testing and relates to an ultrasonic testing method for the quality of a threaded brazing joint. Background Art

[0002] The threaded brazing structure can realize the rigid connection between pipes and meet the sealing of the gas or liquid transported in the pipe. It is widely used in aerospace, nuclear power and other fields. In order to monitor the welding quality of the threaded brazing structure joint, it is necessary to implement high-sensitivity ultrasonic testing on the weld area.

[0003] Threaded brazing components are hollow structures. Generally speaking, the diameter of threaded brazing components, the pitch of the threads, and the thickness of the outer wall are all small (the outer wall thickness is 1.5 mm). Therefore, the ultrasonic detection system is required to have sufficient accuracy. On the one hand, it is necessary to ensure that the center of rotation during the rotation process coincides with the geometric center of the threaded brazing component as much as possible. On the other hand, the resolution of the probe should be high enough to effectively distinguish the inner teeth, outer teeth, and outer wall. Most of the disk ring ultrasonic detection systems used in existing technical detection are difficult to meet these requirements. In addition, the sensitivity adjustment using standard test blocks or comparison test blocks in existing ultrasonic detection is not applicable to the special structure of threaded brazing components. It is necessary to establish sensitivity adjustment, system calibration, scanning imaging and other methods suitable for ultrasonic detection of threaded brazing joints to meet the needs of controlling brazing quality. Summary of the invention

[0004] The purpose of the present invention is to provide an ultrasonic detection method for the quality of threaded brazing joints, which on the one hand responds to the requirements for system accuracy and ultrasonic detection resolution during the detection process, and on the other hand provides sensitivity adjustment, system calibration and scanning imaging methods suitable for the special structure of threaded brazing components to meet the needs of high-sensitivity ultrasonic detection of the quality of threaded brazing joints.

[0005] To solve this technical problem, the technical solution of the present invention is:

[0006] Provided is an ultrasonic testing method for the quality of a threaded brazed joint, the specific steps are as follows:

[0007] Step 1: Install the probe and connect the detection system

[0008] Fix the probe 5 on the probe operating device 7 of the detection system so that the incident direction of the probe is perpendicular to the axis of the turntable 2, and electrically connect the probe 5 to the ultrasonic transmitter and receiver 6 through a cable;

[0009] Step 2: Install the comparison sample and adjust the centering

[0010] Fix the auxiliary centering device 3 on the turntable 2 of the detection system and clamp it, fix the comparison sample on the auxiliary centering device 3 and clamp it, operate the turntable to make the comparison sample rotate with the turntable 2, observe the interface wave position, and fine-tune the claws of the auxiliary centering device 3 so that the interface wave position changes within 0.1mm when the comparison sample rotates one circle;

[0011] Step 3: Adjust the detection sensitivity

[0012] Set the ultrasonic transmitter and receiver 6 to work in the pulse reflection mode and match the frequency of the probe 5, turn on the dual-channel acquisition function, channel one monitors the reflected signal of the external teeth of the thread, adjust the gain of channel one so that its amplitude reaches 80%, and obtain the external tooth detection sensitivity S1; channel two monitors the reflected signal of the internal teeth of the thread, adjust the gain of channel two so that its amplitude reaches 80%, and obtain the internal tooth detection sensitivity S2; in this step, the amplitude of the reflected signal can be adjusted by adjusting the channel gain.

[0013] Step 4: Install the threaded brazing assembly and adjust the centering

[0014] Remove the comparison sample, fix the threaded brazing assembly 4 on the auxiliary centering device 3 and clamp it, operate the turntable to make the threaded brazing assembly 4 rotate with the turntable 2, observe the interface wave position, and fine-tune the claws of the auxiliary centering device 3 so that the interface wave position changes within 0.1 mm when the threaded brazing assembly 4 rotates one circle;

[0015] Step 5: Scanning and imaging

[0016] The turntable 2 is set to rotate at a constant speed at the speed required for detection. The probe 5 steps along the axial direction for each rotation. The two-dimensional images of the internal teeth and external teeth of the threaded brazing component 4 are generated by using the collected ultrasonic signals and position signals with the external tooth detection sensitivity S1 and the internal tooth detection sensitivity S2 to complete the detection.

[0017] Step 5: The ultrasonic signal is collected by the ultrasonic transmitter and receiver 6; the position signal is obtained by the position encoder in the detection system.

[0018] The probe 5 described in step 1 is a water immersion focusing probe with a frequency of 10-25 MHz and a focal length of 25-50 mm. The probe of this frequency is suitable for threaded brazing components with an outer wall thickness of 1.5 mm, and can effectively distinguish between inner teeth, outer teeth and outer wall.

[0019] The detection system is a disk ring ultrasonic water immersion detection system, comprising: an ultrasonic transmitter and receiver 6, a water tank 1, a probe 5, a probe operating device 7, a turntable 2, an auxiliary centering device 3, a control computer and software, etc. The control computer is used to adjust the angle and position of the probe, and the rotation of the turntable 2. The position encoder is in the probe operating device.

[0020] The detection system further comprises a bracket 8 at the bottom, which is used to support the placement of the water tank.

[0021] The bandwidth of the ultrasonic transmitter and receiver 6 is not less than 25 MHz, and has a dual-channel simultaneous signal acquisition function.

[0022] The auxiliary centering device 3 is a three-jaw self-centering structure, which can clamp the comparison sample or threaded brazing assembly to be inspected, and can fine-tune the position of the clamping jaws to correct the offset between the center of the part and the center of rotation.

[0023] The comparison sample is an outer layer part of the threaded brazing assembly 4 that has not been welded.

[0024] The thread brazing assembly 4 is a hollow structure, which is formed by screwing together and brazing the internal and external threads with trapezoidal threads. The detection method is particularly suitable for internal and external thread brazing assemblies with dimensions of: the distance between the external thread teeth and the external surface is 1.5-2.5 mm, and the distance between the internal thread teeth and the external surface is 3-5 mm.

[0025] The beneficial effects of the present invention are:

[0026] (1) The auxiliary centering device is used, which is suitable for the precise centering of small-diameter rotating structures such as hollow threaded brazing components;

[0027] (2) It uses an ultrasonic signal transmitter and receiver with dual-channel simultaneous signal acquisition function, which can simultaneously detect the welding quality of the external and internal teeth of the thread;

[0028] (3) The unwelded outer parts of the threaded brazing assembly are used as comparison samples and used for sensitivity adjustment and system calibration. They can fully represent the actual structural characteristics of the inspected parts and are easy to obtain. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions implemented in the present invention, the following is a brief explanation of the drawings required to be used in the examples of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a schematic diagram of the principle of ultrasonic testing method for the quality of threaded brazed joints;

[0031] Among them, 1-water tank, 2-turntable, 3-auxiliary centering device, 4-thread brazing assembly, 5-probe, 6-ultrasonic transmitter and receiver, 7-probe operating device, 8-bracket. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] The features of various aspects of the embodiments of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to fully understand the present invention. However, it is obvious to those skilled in the art that the present invention can also be implemented without these specific details. The following description of the embodiments is only for a better understanding of the present invention by illustrating examples of the present invention. The present invention is not limited to any specific settings and methods provided below, but covers all product structures, any improvements, replacements, etc. of the methods covered without departing from the spirit of the present invention. In the various drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity of the present invention.

[0034] like Figure 1 As shown, the detection system of the present invention includes: a water tank 1, a turntable 2, an auxiliary centering device 3, a threaded brazing assembly 4, a probe 5, an ultrasonic transmitter and receiver 6, a probe operating device 7, a bracket 8, and also includes a control computer and software. The control computer is used to adjust the angle and position of the probe, as well as the rotation of the turntable 2. The position encoder is in the probe operating device 7. The bracket 8 is located under the water tank 1 for support. The bandwidth of the ultrasonic transmitter and receiver 6 is not less than 25MHz, and has a dual-channel simultaneous signal acquisition function.

[0035] The auxiliary centering device 3 is a three-jaw self-centering structure, which can clamp the comparison sample or threaded brazing assembly to be inspected, and can fine-tune the position of the clamping jaws to correct the offset between the center of the part and the center of rotation.

[0036] The thread brazing assembly 4 is a hollow structure, which is formed by screwing together internal and external threads with trapezoidal threads and then brazing them.

[0037] Combination Figure 1 Schematic diagram, the detection method of the present invention is described below in conjunction with a specific thread brazing assembly:

[0038] The dimensions of the thread brazing assembly 4 are: outer diameter: 25 mm, material: 321 steel; the assembly is performed by screwing the threads together, and ultrasonic waves are used to detect the brazing seam at the screwing of the threads.

[0039] The detection steps are as follows:

[0040] Step 1: Install the probe and connect the detection system

[0041] Fix the probe on the probe operating device of the detection system and ensure that the incident direction of the probe is perpendicular to the axis of the turntable.

[0042] Electrically connect the probe to the ultrasound transmitter and receiver through a cable to ensure a stable connection.

[0043] Step 2: Install the comparison sample and adjust the centering

[0044] Fix the auxiliary centering device on the turntable of the detection system and clamp it.

[0045] Fix the comparison sample on the auxiliary alignment device and clamp it.

[0046] The turntable is operated to rotate the comparison sample to observe the interface wave position. The comparison sample is an outer layer part of the unwelded thread brazing assembly 4.

[0047] Fine-tune the jaws of the auxiliary centering device until the interface wave position changes within 0.1mm when the comparison sample rotates one circle, ensuring the centering accuracy.

[0048] Step 3: Adjust detection sensitivity

[0049] Set the ultrasonic transmitter and receiver to operate in pulse reflection mode and match the probe frequency.

[0050] Turn on the dual-channel acquisition function, channel 1 monitors the reflection signal of the external teeth of the thread, and channel 2 monitors the reflection signal of the internal teeth of the thread.

[0051] Adjust the gain of channel 1 to 80% and record the external tooth detection sensitivity S1.

[0052] Adjust the gain of channel 2 to 80% and record the internal tooth detection sensitivity S2.

[0053] As needed, adjust the probe frequency to 10 MHz, pulse width to 300 ns, scanning speed to 10 rpm, and sampling interval to 0.1 mm.

[0054] Step 4: Install the threaded brazing assembly and adjust the alignment

[0055] Remove the comparison sample, fix the threaded brazing assembly on the auxiliary alignment device and clamp it.

[0056] Operate the turntable to rotate the threaded brazing assembly and observe the interface wave position.

[0057] Fine-tune the jaws of the auxiliary centering device until the interface wave position changes within 0.1 mm when the threaded brazing assembly rotates one circle.

[0058] Step 5: Scanning and imaging

[0059] Set the turntable to rotate at a constant speed as required for the test.

[0060] With each revolution, the probe steps along the axial direction, and the collected ultrasonic signals and position signals are used to generate a two-dimensional image of the threaded brazing component.

[0061] The external tooth detection sensitivity S1 and the internal tooth detection sensitivity S2 are used to complete the detection of the internal teeth and external teeth of the threaded brazing assembly.

[0062] Through the implementation of this scheme, the welding quality of the complex structure welds of threaded brazed parts can be effectively detected. This method has the advantages of high detection sensitivity, high efficiency and low cost. Through the implementation of this scheme, the evaluation of the welding quality of threaded brazed parts can be effectively guaranteed, and the service performance of the corresponding products can be guaranteed.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. An ultrasonic testing method for the quality of a threaded brazed joint, characterized in that: Here are the steps: Step 1: Install the probe and connect the detection system The probe (5) is fixed on the probe operating device (7) of the detection system so that the incident direction of the probe is perpendicular to the axis of the turntable (2), and the probe (5) is electrically connected to the ultrasonic transmitter and receiver (6) via a cable; Step 2: Install the comparison sample and adjust the centering The auxiliary centering device (3) is fixed on the turntable (2) of the detection system and clamped, the comparison sample is fixed on the auxiliary centering device (3) and clamped, the turntable is operated to make the comparison sample rotate with the turntable (2), the interface wave position is observed, and the clamping claw of the auxiliary centering device (3) is finely adjusted so that the interface wave position changes within 0.1 mm when the comparison sample rotates one circle; Step 3: Adjust the detection sensitivity The ultrasonic transmitter and receiver (6) are set to work in a pulse reflection mode and match the frequency of the probe (5), and the dual-channel acquisition function is turned on. Channel 1 monitors the reflection signal of the external teeth of the thread, and the gain of channel 1 is adjusted so that its amplitude reaches 80%, and the external tooth detection sensitivity S1 is obtained; channel 2 monitors the reflection signal of the internal teeth of the thread, and the gain of channel 2 is adjusted so that its amplitude reaches 80%, and the internal tooth detection sensitivity S2 is obtained; Step 4: Install the threaded brazing assembly and adjust the centering Remove the comparison sample, fix the threaded brazing assembly (4) on the auxiliary centering device (3) and clamp it, operate the turntable to make the threaded brazing assembly (4) rotate along with the turntable (2), observe the interface wave position, and fine-tune the clamping claws of the auxiliary centering device (3) so that the interface wave position changes within 0.1 mm when the threaded brazing assembly (4) rotates one circle; Step 5: Scanning and imaging The turntable (2) is set to rotate at a constant speed at a speed required for detection, and the probe (5) steps along the axial direction for each rotation, and a two-dimensional image of the internal teeth and external teeth of the threaded brazing component (4) is generated by using the collected ultrasonic signals and position signals with the external tooth detection sensitivity S1 and the internal tooth detection sensitivity S2 to complete the detection.

2. The ultrasonic detection method according to claim 1, characterized in that: The detection system is an ultrasonic water immersion detection system for disk ring parts, comprising: an ultrasonic transmitter and receiver (6), a water tank (1), a probe operating device (7), a probe (5), a turntable (2), an auxiliary centering device (3), a control computer and software; the control computer is used to adjust the angle and position of the probe, as well as the rotation of the turntable (2).

3. The ultrasonic detection method according to claim 1, characterized in that: The probe (5) described in step 1 is a water immersion focusing probe with a frequency of 10 to 25 MHz and a focal length of 25 to 50 mm.

4. The ultrasonic detection method according to claim 1, characterized in that: Step 5: The ultrasonic signal is collected by an ultrasonic transmitter and receiver (6); the position signal is obtained by a position encoder in the detection system.

5. The ultrasonic detection method according to claim 1, characterized in that: The bandwidth of the ultrasonic transmitter and receiver (6) is not less than 25 MHz, and has a dual-channel simultaneous signal acquisition function.

6. The ultrasonic detection method according to claim 1, characterized in that: The auxiliary centering device (3) is a three-claw self-centering structure, which can clamp the comparison sample or threaded brazing assembly to be inspected, and can fine-tune the position of the clamping claws to correct the offset between the center of the part and the center of rotation.

7. The ultrasonic detection method according to claim 1, characterized in that: The comparison sample is an outer layer part of an unwelded threaded brazing assembly (4).

8. The ultrasonic detection method according to claim 1, characterized in that: The thread brazing assembly (4) is a hollow structure, and is formed by screwing together internal and external threads with trapezoidal threads and then brazing them.

9. The ultrasonic detection method according to claim 1, characterized in that: It is particularly suitable for internal and external thread brazing components with dimensions of: the distance between the external thread teeth and the external surface is 1.5-2.5 mm, and the distance between the internal thread teeth and the external surface is 3-5 mm.

10. The ultrasonic detection method according to claim 1, characterized in that: The detection system also includes a bracket (8) located at the bottom.

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