Distributed ultrasonic stress measuring instrument in-situ calibration device and calibration method thereof

Abstract

The invention discloses a distributed ultrasonic stress measuring instrument in-situ calibration device and a calibration method thereof, and relates to the technical field of ultrasonic nondestructive testing, and the device is characterized in that phase control arrays are located on the surface of a detected workpiece and symmetrically arranged on the two sides of a calibrated probe; the phased array comprises a plurality of phased array wafers; each phased array wafer is connected with the signal generating device and the signal receiving device; the signal generation device determines emission delay time according to the focus point position of the calibrated probe and the distance between each phased array wafer and the focus point position, and emits ultrasonic waves; each phased array wafer emits ultrasonic sub-beams, receives echo signals and sends the echo signals to the receiving device; and the receiving device determines a first stress detection value of the detected workpiece according to the echo signal and a stress time delay curve of the detected workpiece, and corrects a second stress detection value determined by the calibrated probe. According to the invention, the probe working in the field environment can be calibrated under the condition that the probe of the ultrasonic stress measuring instrument is not disassembled.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic nondestructive testing, and in particular to an in-situ calibration device and a calibration method for a distributed ultrasonic stress measuring instrument. Background Art

[0002] Mechanical processing such as extrusion, cutting, hammering and other processes, as well as hot processing welding, cutting and other processes, inevitably cause residual stress and uneven residual stress distribution. Appropriate residual compressive stress can improve the fatigue strength, corrosion resistance and service life of components; while inappropriate residual stress will reduce fatigue strength, cause stress corrosion, and then lead to accidents such as deformation and cracking. Therefore, in the fields of aerospace, ship weapons, railway construction, petrochemicals, containers and pipelines, stress detection is required to ensure the safety and reliability of major instruments and equipment. Ultrasonic waves have the advantages of strong sound wave penetration, high detection sensitivity, strong adaptability, and flexible and convenient use. It is currently a commonly used stress detection method. Its principle is to use the characteristics of ultrasonic waves propagating in materials to indirectly measure stress. The instrument used is an ultrasonic stress measuring instrument, including a host computer and an ultrasonic stress measurement probe.

[0003] In order to make the measurement results more accurate, calibration is an essential step. For ultrasonic stress measuring instruments, the commonly used calibration methods are: absolute calibration method of tension and compression testing machine, C-ring stress calibration method and shot peening stress test block calibration method. These methods all require the use of standard test blocks, coupling the ultrasonic stress measurement probe to the standard test block, and calibrating the measurement results of the probe. These calibration methods are suitable for the calibration of portable ultrasonic stress measuring instruments used under laboratory conditions. In actual applications, the working environment of ultrasonic stress measuring instruments is affected by many factors, and there are hundreds of stress monitoring points in the field distributed ultrasonic stress measuring instruments. The number of ultrasonic stress measurement probes used is large, and the probes are fixed at the monitoring points. Disassembly is time-consuming and labor-intensive. The instruments and equipment will also be limited during on-site calibration, and the calibration method under laboratory conditions is no longer applicable.

[0004] At present, most of the calibration objects are portable high-precision ultrasonic stress measuring instruments under laboratory conditions, and there is little research on the in-situ calibration of distributed ultrasonic stress measuring instruments used in the field. The probe of the on-site distributed ultrasonic stress measuring instrument is affected by the working environment, etc., and there are problems such as inaccurate measurement results. The probe needs to be calibrated in situ regularly. Summary of the invention

[0005] The object of the present invention is to provide an in-situ calibration device and a calibration method for a distributed ultrasonic stress measuring instrument, so as to scientifically and reasonably calibrate the probe working in a field environment without disassembling the probe of the ultrasonic stress measuring instrument.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] An in-situ calibration device for a distributed ultrasonic stress measuring instrument, the in-situ calibration device comprising a signal generating device, a phased array and a signal receiving device;

[0008] The phased array is located on the surface of the workpiece to be inspected and is symmetrically arranged on both sides of the calibrated probe; the phased array includes a plurality of phased array chips; each of the phased array chips is connected to the signal generating device and the signal receiving device;

[0009] The signal generating device determines the emission delay time of the excitation signal of each phased array chip according to the focal point position of the calibrated probe on the detected workpiece and the distance between each phased array chip and the focal point position, and emits ultrasonic waves to the corresponding phased array chip according to the emission delay time;

[0010] Each of the phased array chips emits an ultrasonic sub-beam to the surface of the inspected workpiece under the excitation of the corresponding ultrasonic wave and receives an echo signal, and sends the echo signal to the receiving device;

[0011] The receiving device determines a first stress detection value of the detected workpiece according to the echo signal and a calibrated stress delay curve of the detected workpiece, and corrects a second stress detection value determined by the calibrated probe according to the first stress detection value.

[0012] Optionally, the signal generating device includes a signal generator and a first controller connected to the signal generator;

[0013] The first controller is used to determine the emission delay time of the excitation signal of each phased array chip according to the focus point position of the calibrated probe and the distance between each phased array chip and the focus point position, and generate an emission control signal according to the emission delay time;

[0014] The signal generator is connected to each of the phased array chips; the signal generator transmits ultrasonic waves to the corresponding phased array chips according to the transmission control signal.

[0015] Optionally, the first controller includes a first computer and a delay counter connected to the first computer;

[0016] The first computer is used to determine the emission delay time of the excitation signal of each phased array chip according to the focus point position of the calibrated probe and the distance between each phased array chip and the focus point position;

[0017] The delay counter is connected to the signal generator; the delay counter is used to generate a transmission control signal according to the transmission delay time.

[0018] Optionally, the signal receiving device includes an oscilloscope and a second controller connected to the oscilloscope;

[0019] The oscilloscope is used to receive the echo signal and send it to the second controller;

[0020] The second controller is used to determine a first stress detection value of the detected workpiece according to the echo signal and a calibrated stress delay curve of the detected workpiece, and to correct a second stress detection value determined by the calibrated probe according to the first stress detection value.

[0021] Optionally, the second controller includes a signal receiving and storing circuit and a second computer connected to the signal receiving and storing circuit;

[0022] The signal receiving and storing circuit is used to collect and store the echo signal, and when the echo signal is an analog signal, perform A / D conversion on the echo signal;

[0023] The second computer is used to determine a first stress detection value of the detected workpiece according to the echo signal and a calibrated stress delay curve of the detected workpiece, and to correct a second stress detection value determined by the calibrated probe according to the first stress detection value.

[0024] Optionally, the width of each phased array chip is 2 mm.

[0025] Optionally, the phased array includes a first phased array and a second phased array having the same structure;

[0026] The first phased array and the second phased array are symmetrically arranged on both sides of the calibrated probe; the first phased array and the second phased array each include a plurality of the phased array chips.

[0027] Optionally, each of the phased array wafers is coupled to the surface of the inspected workpiece via a coupling agent.

[0028] A calibration method for an in-situ calibration device of a distributed ultrasonic stress measuring instrument is applied to the in-situ calibration device of the distributed ultrasonic stress measuring instrument, and the calibration method comprises:

[0029] Determining the emission delay time of the excitation signal of each phased array chip according to the focus point position of the calibrated probe on the detected workpiece and the distance between each phased array chip and the focus point position;

[0030] Acquire the echo signals of each of the phased array chips under the transmission delay time, and synthesize the echo signals to obtain a synthesized echo signal;

[0031] Determine the propagation time of the synthetic echo signal, and according to the propagation time, find the corresponding stress value from the stress delay curve calibrated by the detected workpiece as the first stress detection value;

[0032] The second stress detection value determined by the calibrated probe is corrected according to the first stress detection value.

[0033] Optionally, synthesizing the echo signals to obtain a synthesized echo signal specifically includes:

[0034] According to the transmission delay time of each of the echo signals, one of the echo signals is used as a reference signal, and the other echo signals are shifted so that the time of each of the echo signals after the shift is aligned;

[0035] The time-aligned echo signals are linearly superimposed, and an average value calculation is performed on the superimposed echo signals to obtain a synthetic echo signal.

[0036] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0037] The present invention discloses an in-situ calibration device and a calibration method for a distributed ultrasonic stress measuring instrument. The phased array is arranged on the surface of a detected workpiece and symmetrically arranged on both sides of a calibrated probe; and the phased array includes a plurality of phased array chips; each of the phased array chips is connected to a signal generating device and a signal receiving device; wherein the signal generating device determines the emission delay time of the excitation signal of each phased array chip according to the focal point position of the calibrated probe on the detected workpiece and the distance between each phased array chip and the focal point position, and emits ultrasonic waves to the corresponding phased array chips according to the emission delay time; each phased array chip emits ultrasonic sub-beams to the surface of the detected workpiece under the excitation of the corresponding ultrasonic wave and receives echo signals, and sends the echo signals to the receiving device; the receiving device determines a first stress detection value of the detected workpiece according to the echo signals and a calibrated stress delay curve of the detected workpiece, and corrects a second stress detection value determined by the calibrated probe according to the first stress detection value. The present invention excites each array element phased array chip according to a certain delay rule, and the emitted ultrasonic sub-beams are superimposed and synthesized in the detected workpiece to form a focal point, and the synthesized sound beam has directionality, so that the synthesized sound beam covers the measurement area of ​​the calibrated ultrasonic stress measurement probe, thereby obtaining the residual stress value of the same measurement area without disassembling the calibrated ultrasonic stress measurement probe, and realizing the in-situ calibration of the distributed ultrasonic stress measuring instrument by comparing the residual stress value measurement results of the two. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0039] Figure 1 It is a schematic structural diagram of an in-situ calibration device of a distributed ultrasonic stress measuring instrument based on an ultrasonic phased array according to an embodiment of the present invention;

[0040] Figure 2 This is a calibration principle diagram of an in-situ calibration device for a distributed ultrasonic stress measuring instrument based on an ultrasonic phased array according to an embodiment of the present invention;

[0041] Figure 3 This is a calibration flow chart of an in-situ calibration device for a distributed ultrasonic stress measuring instrument based on an ultrasonic phased array according to an embodiment of the present invention;

[0042] Figure 4It is a schematic diagram of an in-situ calibration method of a distributed ultrasonic stress measuring instrument based on an ultrasonic phased array according to an embodiment of the present invention;

[0043] Figure 5 This is an excitation signal waveform diagram of an embodiment of an in-situ calibration method of a distributed ultrasonic stress measuring instrument based on an ultrasonic phased array of the present invention;

[0044] Figure 6 This is a waveform diagram of the echo signal of each element of the phased array in an embodiment of the in-situ calibration method of a distributed ultrasonic stress measuring instrument based on an ultrasonic phased array of the present invention;

[0045] Figure 7 This is a synthetic waveform diagram of the echo signal of an embodiment of the in-situ calibration method of a distributed ultrasonic stress measuring instrument based on an ultrasonic phased array of the present invention.

[0046] Explanation of symbols:

[0047] 1-first phased array chip, 2-second phased array chip, 3-third phased array chip, 4-fourth phased array chip, 5-fifth phased array chip, 6-sixth phased array chip, 7-seventh phased array chip, 8-eighth phased array chip, 9-detected workpiece, 10-phased array chip, 11-phased array chip connecting line, 12-calibrated probe, 13-digital oscilloscope, 14-signal receiving storage circuit, 15-signal generator, 16-delay counter 16, 17-computer, 18-phased array chip sound field, 19-calibrated ultrasonic stress measurement probe sound field. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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 creative work are within the scope of protection of the present invention.

[0049] The object of the present invention is to provide an in-situ calibration device and a calibration method for a distributed ultrasonic stress measuring instrument, so as to scientifically and reasonably calibrate the probe working in a field environment without disassembling the probe of the ultrasonic stress measuring instrument.

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Example 1

[0052] The invention provides an in-situ calibration device for a distributed ultrasonic stress measuring instrument. The in-situ calibration device comprises a signal generating device, a phased array and a signal receiving device.

[0053] The phased array is located on the surface of the workpiece 9 to be inspected and is symmetrically arranged on both sides of the calibrated probe 12; the phased array includes a plurality of phased array chips 10; each of the phased array chips 10 is connected to the signal generating device and the signal receiving device.

[0054] The signal generating device determines the transmission delay time of the excitation signal of each phased array chip 10 according to the focal point position of the calibrated probe 12 on the inspected workpiece 9 and the distance between each phased array chip 10 and the focal point position, and transmits ultrasonic waves to the corresponding phased array chip 10 according to the transmission delay time.

[0055] Each of the phased array chips 10 emits an ultrasonic sub-beam to the surface of the inspected workpiece 9 under the excitation of the corresponding ultrasonic wave and receives an echo signal, and sends the echo signal to the receiving device.

[0056] The receiving device determines the first stress detection value of the detected workpiece 9 according to the echo signal and the calibrated stress delay curve of the detected workpiece 9, and corrects the second stress detection value determined by the calibrated probe 12 according to the first stress detection value. The first stress detection value is obtained by detection using a phased array wafer; the second stress detection value is obtained by detection by the calibrated probe.

[0057] As a specific implementation, the signal generating device includes a signal generator 15 and a first controller connected to the signal generator 15; the first controller is used to determine the transmission delay time of the excitation signal of each phased array chip 10 according to the focal point position of the calibrated probe 12 and the distance between each phased array chip 10 and the focal point position, and generate a transmission control signal according to the transmission delay time; the signal generator 15 is connected to each phased array chip 10; the signal generator 15 transmits ultrasonic waves to the corresponding phased array chip 10 according to the transmission control signal.

[0058] Among them, the first controller includes a first computer and a delay counter 16 connected to the first computer; the first computer is used to determine the emission delay time of the excitation signal of each phased array chip 10 according to the focus point position of the calibrated probe 12 and the distance between each phased array chip 10 and the focus point position; the delay counter 16 is connected to the signal generator 15; the delay counter 16 is used to generate an emission control signal according to the emission delay time.

[0059] As a specific implementation method, the signal receiving device includes an oscilloscope and a second controller connected to the oscilloscope; the oscilloscope is used to receive the echo signal and send it to the second controller; the second controller is used to determine the first stress detection value of the inspected workpiece 9 based on the echo signal and the calibrated stress delay curve of the inspected workpiece 9, and correct the second stress detection value determined by the calibrated probe 12 based on the first stress detection value.

[0060] Among them, the second controller includes a signal receiving and storage circuit 14 and a second computer connected to the signal receiving and storage circuit 14; the signal receiving and storage circuit 14 is used to collect and store the echo signal, and when the echo signal is an analog signal, the echo signal is A / D converted; the second computer is used to determine the first stress detection value of the inspected workpiece 9 according to the echo signal and the calibrated stress delay curve of the inspected workpiece 9, and correct the second stress detection value determined by the calibrated probe 12 according to the first stress detection value.

[0061] As a specific implementation, the phased array includes a first phased array and a second phased array with the same structure; the first phased array and the second phased array are symmetrically arranged on both sides of the calibrated probe 12; the first phased array and the second phased array each include a plurality of phased array chips 10. The width of each phased array chip 10 is 2 mm. Each phased array chip 10 is coupled to the surface of the workpiece 9 to be inspected by a coupling agent.

[0062] In practical applications, such as Figure 1 As shown, the signal generator 15 is connected to the delay counter 16 and the phased array self-transmitting and self-receiving probe respectively; wherein the phased array self-transmitting and self-receiving probe is a phased array; the phased array self-transmitting and self-receiving probe is connected to the digital oscilloscope 13; the digital oscilloscope 13 is connected to the signal receiving storage circuit 14; the delay counter 16 and the signal receiving storage circuit 14 are connected to the computer 17. In the present invention, the oscilloscope is preferably a digital oscilloscope 13; the first computer and the second computer can be two independent computers or the same computer 17. The connection relationship of the components is: the signal generator 15 is connected to the delay counter 16 and the phased array respectively; the phased array is connected to the digital oscilloscope 13; the digital oscilloscope 13 is connected to the signal receiving storage circuit 14; the delay counter 16 and the signal receiving storage circuit 14 are connected to the computer 17; the phased array wafer 10 is evenly distributed at equal intervals on both sides of the probe of the ultrasonic stress measuring instrument to be calibrated, and is coupled to the surface of the workpiece 9 to be detected through a coupling agent. The probe of the ultrasonic stress measuring instrument to be calibrated is also the calibrated probe 12 in the present invention.

[0063] The phased array self-transmitting and self-receiving probe (i.e., phased array) selects the number of array elements of the phased array chip 10 according to actual needs, that is, the number of phased array chips 10. The phased array self-transmitting and self-receiving probe includes multiple phased array chips 10 and phased array chip connecting lines 11, and the multiple phased array chips 10 are evenly distributed on both sides of the ultrasonic stress measuring instrument probe to be calibrated with equal spacing.

[0064] The accuracy of the delay counter 16 reaches 1ms level. The signal generator 15 can emit an excitation signal after being externally triggered, and each channel signal is independently excited. The signal generator 15 is connected to the delay counter 16 and the phased array self-transmitting and self-receiving probe respectively, and the delay time of each channel signal is controlled by the delay counter 16. The number of channels of the signal generator 15 is consistent with the number of phased array chips 10, and one channel of the signal generator 15 is connected to one phased array chip 10.

[0065] The relatively independent phased array chip 10 of the phased array self-transmitting and self-receiving probe is a piezoelectric chip array element, and each array element chip can be excited individually, and the excitation delay is controlled externally. The width of each array element chip of the phased array chip 10 is 2mm, and the spacing between each array element chip can be adjusted according to the size of the ultrasonic stress measurement probe to be calibrated. The number of array elements used in the phased array self-transmitting and self-receiving probe can be appropriately selected according to the size of the ultrasonic stress measurement probe to be calibrated and the size of the workpiece 9 to be tested.

[0066] The signal receiving storage circuit 14 can perform the A / D conversion function, collect and store the echo signal received by the phased array self-transmitting and self-receiving probe. The computer 17 can calculate the signal excitation delay time of the phased array chip 10 and input it into the delay counter 16. In addition, the computer 17 can complete the delay correction of the echo signal received by the phased array chip 10 and superimpose and synthesize the echo signal.

[0067] The present invention determines the position of the focal point according to the size of the calibrated ultrasonic stress measurement probe and the thickness of the detected workpiece 9. The focal area is directly below the calibrated ultrasonic stress measurement probe, and the focal depth is half the height of the detected workpiece 9. Each array element phased array chip 10 is excited according to a certain delay rule, and the emitted ultrasonic sub-beams are superimposed and synthesized in the detected workpiece 9 to form a focal point, and the synthesized sound beam has directionality, so that the synthesized sound beam covers the measurement area of ​​the calibrated ultrasonic stress measurement probe. Without disassembling the calibrated ultrasonic stress measurement probe, the residual stress value of the same measurement area is obtained, and the in-situ calibration of the distributed ultrasonic stress measuring instrument is realized by comparing the residual stress value measurement results of the two.

[0068] Example 2

[0069] On the basis of Example 1, the present invention further provides a calibration method for an in-situ calibration device of a distributed ultrasonic stress measuring instrument, which is applied to the in-situ calibration device of a distributed ultrasonic stress measuring instrument described in Example 1. The calibration method comprises:

[0070] Step S1: determining the emission delay time of the excitation signal of each phased array chip according to the focus point position of the calibrated probe on the detected workpiece and the distance between each phased array chip and the focus point position.

[0071] Step S2: Acquire the echo signals of each of the phased array chips under the transmission delay time, and synthesize the echo signals to obtain a synthesized echo signal.

[0072] The step of synthesizing the echo signals to obtain a synthesized echo signal specifically includes:

[0073] Step S21: according to the transmission delay time of each echo signal, one of the echo signals is used as a reference signal, and the other echo signals are shifted so that the time of each echo signal after the shift is aligned.

[0074] Step S22: linearly superimpose the time-aligned echo signals, and perform an average calculation on the superimposed echo signals to obtain a synthesized echo signal.

[0075] Step S3: determining the propagation time of the synthetic echo signal, and searching for a corresponding stress value as a first stress detection value from the calibrated stress delay curve of the detected workpiece according to the propagation time.

[0076] Step S4: Correcting the second stress detection value determined by the calibrated probe according to the first stress detection value.

[0077] like Figure 2 As shown, in Figure 2 The phased array chip acoustic field 18 corresponding to the phased array chip and the calibrated ultrasonic stress measurement probe acoustic field 19 corresponding to the calibrated ultrasonic stress measurement probe are shown. The calibration method provided by the present invention is based on the deflection and focusing principles of the phased array. The phased array element chips are relatively independent of each other and can be excited individually. Different rules are used to excite all or part of the elements. The ultrasonic sub-beams emitted by each element are superimposed to synthesize a deflected, focused and directive sound beam.

[0078] like Figure 3 As shown, the implementation process of the calibration method provided by the present invention in practical application specifically includes:

[0079] The first step: the ultrasonic stress measurement probe to be calibrated is fixed on the surface of the workpiece 9 to be tested, and the phased array wafer 10 of the phased array self-transmitting and self-receiving probe is coupled to the two sides of the ultrasonic stress measurement probe to be calibrated at equal intervals.

[0080] Specifically, according to the size of the ultrasonic stress measurement probe to be calibrated and the size of the workpiece 9 to be tested, the number of array elements of the phased array wafer 10 to be used is selected, and the spacing between the array element wafers is determined. After completion, the phased array element wafers are coupled to the surface of the workpiece 9 to be tested. According to the size of the ultrasonic stress measurement probe to be calibrated and the thickness of the workpiece 9 to be tested, the position of the focus point is determined, the focus area is directly below the calibrated ultrasonic stress measurement probe, and the focus depth is half of the height of the workpiece 9 to be tested.

[0081] Step 2: During the in-situ calibration process, the principle of phased array deflection and focusing is used. Without disassembling the probe of the ultrasonic stress measuring instrument to be calibrated, ultrasonic waves are emitted from both sides of the probe of the ultrasonic stress measuring instrument to the inside of the workpiece 9 to be tested. The phased array chip 10 of each array element is excited according to a certain delay rule to emit ultrasonic sub-beams. Each sub-beam is superimposed and synthesized in the workpiece 9 to form a focal point. The synthesized sound beam has directionality, so that the synthesized sound beam covers the measurement area of ​​the ultrasonic stress measuring probe to be calibrated, and the echo signal of the area under the standard ultrasonic probe (phased array) is obtained.

[0082] Specifically, according to the determined positions of each array element chip and the focal point of the phased array self-transmitting and self-receiving probe, the delay time of the transmission signal of each array element chip is calculated, and the excitation timing of each array element is that the array elements at the two ends are excited first, and the delay is gradually increased toward the middle array element. The array element chips at the two ends are farthest from the focal point and have the largest sound path, so they generate the excitation signal first and transmit the ultrasonic sub-beam. The delay time calculated by the computer 17 is input into the delay counter 16.

[0083] The excitation waveforms of each array transducer are consistent, but there is a time difference V0 (t-dt). The time difference dt can be calculated by selecting the position of the focal point to obtain the sound path difference dL of each array transducer to the focal point. The calculation formula is as follows:

[0084] Time difference dt = sound path difference dL / medium sound velocity c;

[0085] like Figure 4As shown, the number of array elements used in this calibration is 8, namely, the first phased array chip 1, the second phased array chip 2, the third phased array chip 3, the fourth phased array chip 4, the fifth phased array chip 5, the sixth phased array chip 6, the seventh phased array chip 7 and the eighth phased array chip 8, wherein the first phased array chip 1, the third phased array chip 3, the fifth phased array chip 5 and the seventh phased array chip 7 are arranged on one side of the calibrated probe 12 as the first phased array, and the first phased array chip 1, the third phased array chip 3, the fifth phased array chip 5 and the seventh phased array chip 7 are arranged in sequence from near to far from the calibrated probe 12; the second phased array chip 2, the fourth phased array chip 4, the sixth phased array chip 6 and the eighth phased array chip 8 are arranged on the other side of the calibrated probe 12 as the second phased array, and the second phased array chip 2, the fourth phased array chip 4, the sixth phased array chip 6 and the eighth phased array chip 8 are arranged in sequence from near to far from the calibrated probe 12. The frequency of the sound waves emitted by each array element is 2.5MHz, and the expression of the emitted signal is:

[0086]

[0087] According to the delay focusing calculation formula of the phased array, since the seventh phased array chip 7 and the eighth phased array chip 8 at both ends have the longest acoustic path for transmitting signals, the excitation signal is given first. The other array elements calculate the time difference based on the propagation acoustic path difference between each array element and the seventh phased array chip 7 and the eighth phased array chip 8 at both ends to obtain the delay time of each array element. The calculation process is as follows:

[0088] The transmission signal delay time of the fifth phased array chip 5 and the sixth phased array chip 6 is:

[0089]

[0090] The transmission signal delay time of the third phased array chip 3 and the fourth phased array chip 4 is:

[0091]

[0092] The delay time of the transmission signal between the first phased array chip 1 and the second phased array chip 2 is:

[0093]

[0094] Where, cl is the propagation speed of the longitudinal wave in the workpiece being measured, and the waveform of the excitation signal is as follows: Figure 5As shown. The seventh phased array chip 7 and the eighth phased array chip 8 first transmit the signal V0(t). Secondly, the fifth phased array chip 5 and the sixth phased array chip 6 transmit signals, the signal delay time is td1, and the transmitted signal is V0(t-td1). Then the third phased array chip 3 and the fourth phased array chip 4 transmit signals, the signal delay time is td2, and the transmitted signal is V0(t-td2). Finally, the first phased array chip 1 and the second phased array chip 2 transmit signals, the signal delay time is td3, and the transmitted signal is V0(t-td3). That is, the waveform of the transmitted signal of each array element remains unchanged, but there is a certain delay.

[0095] The delay counter 16 triggers the signal generator 15 to generate an excitation signal in turn according to the calculated delay time, and excites each phased array chip 10 to emit an ultrasonic sub-beam into the workpiece 9 to be inspected through the phased array chip connection line 11. According to the Huygens principle, the ultrasonic sub-beams emitted by each piezoelectric chip array element are superimposed on each other in space to obtain a synthetic beam, which can produce the effect of beam deflection or beam focusing. Since the synthetic beam covers the measurement area of ​​the ultrasonic stress measurement probe to be calibrated, the echo signal of the area under the standard ultrasonic probe can be obtained.

[0096] Step 3: After obtaining the echo signal of the standard ultrasonic probe in the workpiece 9 to be tested, since the propagation paths of the sound waves emitted by each array element phased array chip 10 are different, the signal excitation time is also different, so it is necessary to delay and correct each echo signal before superimposing and synthesizing. By calculating the propagation time of the synthesized signal and comparing it with the calibrated stress-acoustic time difference curve of the workpiece 9 to be tested, the accurate measurement value of the residual stress in the workpiece 9 to be tested is obtained.

[0097] Specifically, after receiving the echo signal, the phased array chip 10 inputs it into the signal receiving storage circuit 14 through the phased array chip connection line 11. The signal receiving storage circuit 14 is connected to the computer 17 to input the echo signal into the computer 17. After obtaining the echo signal in the workpiece 9 under the standard ultrasonic probe, since the time when each element phased array chip 10 emits sound waves is different, it is necessary to perform delay correction on each echo signal, and then perform superposition synthesis to obtain a synthetic echo signal.

[0098] The echo signals of each array element obtained in the embodiment are as follows: Figure 6 As shown in the figure, 8 array elements receive 8 independent echo signals. According to the delay of the signal excitation of each array element, the signal is shifted (t+td), linearly superimposed after time alignment, and finally the superimposed signal is averaged to obtain the synthesized complete echo signal as shown in Figure 7 shown.

[0099] By calculating the propagation time of the synthetic echo signal and comparing it with the calibrated stress-delay curve of the inspected workpiece 9, an accurate measurement value of the residual stress in the inspected workpiece 9 is obtained. By comparing the stress measurement values ​​of the calibrated ultrasonic stress measurement probe and the standard phased array probe, the in-situ calibration of the distributed ultrasonic stress measuring instrument is completed.

[0100] The present invention transmits ultrasonic waves from both sides of the ultrasonic stress measuring probe to the workpiece 9 to be tested without disassembling the ultrasonic stress measuring probe to be tested. Each array element phased array chip 10 is excited according to a certain delay rule to transmit ultrasonic sub-beams. Each sub-beam is superimposed and synthesized in the workpiece 9 to form a focal point. The synthesized sound beam has directionality, so that the synthesized sound beam covers the measuring area of ​​the ultrasonic stress measuring probe to obtain the echo signal of the area under the standard ultrasonic probe.

[0101] In summary, the present invention obtains the residual stress value of the same measurement area without disassembling the calibrated ultrasonic stress measurement probe, and realizes the in-situ calibration of the distributed ultrasonic stress measuring instrument by comparing the residual stress value measurement results of the two. The in-situ calibration technology does not require disassembly, saves time and labor, and can improve the calibration efficiency of the distributed ultrasonic stress measurement probe.

[0102] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0103] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An in-situ calibration device for a distributed ultrasonic stress measuring instrument, characterized in that: The in-situ calibration device includes a signal generating device, a phased array and a signal receiving device; The phased array is located on the surface of the workpiece to be inspected and is symmetrically arranged on both sides of the calibrated probe; the phased array includes a plurality of phased array chips; each of the phased array chips is connected to the signal generating device and the signal receiving device; The signal generating device determines the emission delay time of the excitation signal of each phased array chip according to the focal point position of the calibrated probe on the detected workpiece and the distance between each phased array chip and the focal point position, and emits ultrasonic waves to the corresponding phased array chip according to the emission delay time; Each of the phased array chips emits an ultrasonic sub-beam to the surface of the inspected workpiece under the excitation of the corresponding ultrasonic wave and receives an echo signal, and sends the echo signal to the receiving device; The receiving device determines a first stress detection value of the detected workpiece according to the echo signal and a calibrated stress delay curve of the detected workpiece, and corrects a second stress detection value determined by the calibrated probe according to the first stress detection value.

2. The in-situ calibration device for a distributed ultrasonic stress measuring instrument according to claim 1, characterized in that: The signal generating device comprises a signal generator and a first controller connected to the signal generator; The first controller is used to determine the emission delay time of the excitation signal of each phased array chip according to the focus point position of the calibrated probe and the distance between each phased array chip and the focus point position, and generate an emission control signal according to the emission delay time; The signal generator is connected to each of the phased array chips; the signal generator transmits ultrasonic waves to the corresponding phased array chips according to the transmission control signal.

3. The in-situ calibration device for a distributed ultrasonic stress measuring instrument according to claim 2, characterized in that: The first controller includes a first computer and a delay counter connected to the first computer; The first computer is used to determine the emission delay time of the excitation signal of each phased array chip according to the focus point position of the calibrated probe and the distance between each phased array chip and the focus point position; The delay counter is connected to the signal generator; The delay counter is used to generate a transmission control signal according to the transmission delay time.

4. The in-situ calibration device for a distributed ultrasonic stress measuring instrument according to claim 1, characterized in that: The signal receiving device includes an oscilloscope and a second controller connected to the oscilloscope; The oscilloscope is used to receive the echo signal and send it to the second controller; The second controller is used to determine a first stress detection value of the detected workpiece according to the echo signal and a calibrated stress delay curve of the detected workpiece, and to correct a second stress detection value determined by the calibrated probe according to the first stress detection value.

5. The in-situ calibration device for a distributed ultrasonic stress measuring instrument according to claim 4, characterized in that: The second controller includes a signal receiving storage circuit and a second computer connected to the signal receiving storage circuit; The signal receiving and storing circuit is used to collect and store the echo signal, and when the echo signal is an analog signal, perform A / D conversion on the echo signal; The second computer is used to determine a first stress detection value of the detected workpiece according to the echo signal and a calibrated stress delay curve of the detected workpiece, and to correct a second stress detection value determined by the calibrated probe according to the first stress detection value.

6. The in-situ calibration device for a distributed ultrasonic stress measuring instrument according to claim 1, characterized in that: The width of each phased array chip is 2 mm.

7. The in-situ calibration device for a distributed ultrasonic stress measuring instrument according to claim 1, characterized in that: The phased array comprises a first phased array and a second phased array having the same structure; The first phased array and the second phased array are symmetrically arranged on both sides of the calibrated probe; the first phased array and the second phased array each include a plurality of the phased array chips.

8. The in-situ calibration device for a distributed ultrasonic stress measuring instrument according to claim 1, characterized in that: Each of the phased array wafers is coupled to the surface of the inspected workpiece via a coupling agent.

9. A calibration method for an in-situ calibration device of a distributed ultrasonic stress measuring instrument, characterized in that: The in-situ calibration device for a distributed ultrasonic stress measuring instrument according to any one of claims 1 to 8, wherein the calibration method comprises: Determining the emission delay time of the excitation signal of each phased array chip according to the focus point position of the calibrated probe on the detected workpiece and the distance between each phased array chip and the focus point position; Acquire the echo signals of each of the phased array chips under the transmission delay time, and synthesize the echo signals to obtain a synthesized echo signal; Determine the propagation time of the synthetic echo signal, and according to the propagation time, find the corresponding stress value from the stress delay curve calibrated by the detected workpiece as the first stress detection value; The second stress detection value determined by the calibrated probe is corrected according to the first stress detection value.

10. The calibration method of the in-situ calibration device of the distributed ultrasonic stress measuring instrument according to claim 9, characterized in that: The echo signals are synthesized to obtain a synthesized echo signal, which specifically includes: According to the transmission delay time of each of the echo signals, one of the echo signals is used as a reference signal, and the other echo signals are shifted so that the time of each of the echo signals after the shift is aligned; The time-aligned echo signals are linearly superimposed, and an average value calculation is performed on the superimposed echo signals to obtain a synthetic echo signal.

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