CN115728244A - An online detection method and device for metal additive manufacturing - Google Patents

Abstract

The invention relates to the technical field of metal additive manufacturing, in particular to a metal additive manufacturing online detection method and device. The method comprises the following steps: printing layer by layer through a material increase process, and testing the material increase material by using a laser ultrasonic technology to obtain ultrasonic data when the preset thickness is printed; wherein the additive material comprises all layers obtained by an additive process; printing layer by layer through a material increase process, and measuring the surface temperature of the material increase material by using an infrared temperature measurement technology every time when a preset thickness is printed to obtain temperature data; determining microstructure distribution data, defect data and residual stress data of the additive material according to the ultrasonic data; and obtaining residual stress correction data according to the temperature data, the microstructure distribution data and the defect data. The invention provides an online detection method and device for metal additive manufacturing, which can simultaneously realize online in-situ detection of residual stress, microstructure and internal defects of a metal additive part and provide data support for optimization and control of a metal additive manufacturing process.

Description

An online detection method and device for metal additive manufacturing

technical field

The invention relates to the technical field of metal additive manufacturing, in particular to an online detection method and device for metal additive manufacturing.

Background technique

Metal additive manufacturing is based on digital models, using high-energy beam heat sources, such as high-power density laser beams, electric arcs, electron beams and other media to melt metal powder or wire, and realize bottom-up and layer-by-layer stacking. The advanced manufacturing technology of parts entities has the characteristics of complex forming structure, high forming precision and excellent forming performance. It is one of the most promising manufacturing technologies for complex precision metal parts or large-size main load-bearing metal components in one-time integral forming.

In the process of metal additive manufacturing, the non-equilibrium physical and thermophysical processes of materials produced by the long-term cyclic process of high-power laser beams are very complicated, and complex processes will occur between laser heat sources, metal powders, solid substrates, and liquid metals in the molten pool. The interaction of the moving metal pool under the conditions of laser supernormal metallurgy, ultra-high temperature gradient and rapid solidification, etc., makes the processing process in an extremely complex environment, and the internal or surface of the formed part is prone to residual stress and various Such typical defects reduce the forming accuracy and mechanical properties of metal additive parts. In the process of metal additive manufacturing, due to its special printing process, the residual stress of metal additive manufacturing parts is relatively complicated. Since additive manufacturing is a layer-by-layer process, each layer needs to undergo rapid heating and cooling. , In the process of heating and solidification, due to factors such as thermal expansion and contraction, tensile stress and compressive stress will be generated, so there will be residual stress fields of different sizes and uneven distribution in the sample, making detection difficult.

Therefore, in view of the above deficiencies, there is an urgent need for a method and device capable of simultaneously realizing online in-situ detection of residual stress, microstructure and internal defects.

Contents of the invention

The embodiment of the present invention provides an online detection method and device for metal additive manufacturing, which can realize the online in-situ detection of residual stress, microstructure and internal defects of metal additive manufacturing parts at the same time, and provide a method for optimizing and controlling the metal additive manufacturing process Provide data support.

In the first aspect, an embodiment of the present invention provides a method for online detection of metal additive manufacturing, including:

The layer-by-layer printing is carried out through the additive process, and the laser ultrasonic technology is used to test the additive material for each printing preset thickness to obtain ultrasonic data; wherein, the additive material includes all layers obtained by the additive process;

Print layer by layer through the additive process, and use infrared temperature measurement technology to measure the temperature of the additive material for each printing preset thickness to obtain temperature data;

determining microstructure distribution data, defect data and residual stress data of the additive material according to the ultrasonic data;

The residual stress correction data is obtained according to the temperature data, microstructure distribution data and defect data.

In a possible design, before determining the microstructure distribution data, defect data and residual stress data of the additive material according to the ultrasonic data, it includes:

A calibration test block is prepared through the additive process;

Using the calibration test block to measure the sound velocity-stress mapping relationship;

The determining the microstructure distribution data, defect data and residual stress data of the additive material according to the ultrasonic data includes:

determining the residual stress data according to the sound velocity-stress mapping relationship and the sound velocity of the ultrasonic data;

The microstructure distribution data and defect data of the additive material are determined according to the ultrasonic data.

In a possible design, the determining the microstructure distribution data and defect data of the additive material according to the ultrasonic data includes:

Obtaining a two-dimensional ultrasonic image according to the Rayleigh wave amplitude reconstruction of the ultrasonic data;

Determining the position information of the defect of the additive material according to the two-dimensional ultrasonic image to obtain the defect data;

Determining the microstructure distribution of the additive material according to the two-dimensional ultrasonic image to obtain the microstructure distribution data.

In a possible design, after the calibration test block is prepared by the additive process, and before the residual stress correction data is obtained according to the temperature data, microstructure distribution data, and defect data, it also includes:

Using the calibration test block to measure the sound velocity-microstructure distribution mapping relationship;

Using the calibration test block to measure the sound velocity-temperature mapping relationship;

The obtaining residual stress correction data according to the temperature data, microstructure distribution data, and defect data includes:

Obtaining a first sound velocity correction coefficient according to the temperature data and the sound velocity-temperature mapping relationship;

Obtaining a second sound velocity correction coefficient according to the microscopic data and the sound velocity-microstructure distribution mapping relationship;

Correct the ultrasonic data according to the first sound velocity correction coefficient, the second sound velocity correction coefficient and defect data to obtain ultrasonic sound velocity correction data; combine the ultrasonic sound velocity correction data and the sound velocity-stress mapping relationship to obtain the residual Stress Correction Data.

In a possible design, the sound velocity-stress mapping relationship measured by the calibration test block includes:

A unidirectional tensile test is used to generate tensile stresses of different sizes in the calibration test block, and ultrasonic waves are applied to the calibration test block at the same time to measure the sound velocity of Rayleigh waves under different tensile stresses, and to establish according to the tensile stress and sound velocity The sound velocity-stress mapping relationship.

In a possible design, the sound velocity-microstructure distribution mapping relationship measured by using the calibration test block includes:

Apply ultrasonic waves to the calibration test block, obtain the Rayleigh wave amplitude and Rayleigh wave sound velocity with a mapping relationship in different areas of the calibration test block, and perform two-dimensional imaging according to the difference in the Rayleigh wave amplitude in different areas , to obtain the microstructure distribution, and combine the microstructure with the Rayleigh wave sound velocity to obtain the sound velocity-microstructure distribution mapping relationship.

In a possible design, the sound velocity-temperature mapping relationship measured by the calibration test block includes:

The calibration test block is subjected to continuous heating treatment, and ultrasonic waves are applied to the calibration test block at the same time, the Rayleigh wave sound velocity of the calibration test block at different temperatures is monitored in real time, and the sound velocity-temperature mapping relationship is established.

In a possible design, the layer-by-layer printing is carried out through the additive process, and the laser ultrasonic technology is used to test the additive material for each printing preset thickness to obtain ultrasonic data, including:

Layer-by-layer printing is performed through the additive process, and the additive material is polished for each printing preset thickness, and then the additive material is tested by laser ultrasonic technology to obtain ultrasonic data.

In a possible design, the calibration test block is a zero stress test block obtained by stress relief annealing.

In the second aspect, the embodiment of the present invention also provides an online detection device for metal additive manufacturing, which is used to implement the method described in any one of the above-mentioned first aspects, and the device includes:

Additive unit, detection unit and mobile platform;

The additive unit includes a laser emitting assembly and a working chamber, the laser emitting assembly is used to provide laser beams, the working chamber includes a molding cylinder, a powder feeding cylinder and a powder recovery cylinder, and the powder feeding cylinder is used for the The molding cylinder provides powder, the molding cylinder is used to shape the powder under the action of the laser, and the powder recovery cylinder is used to recover excess powder;

The detection unit includes a detection chamber and an infrared temperature measuring device and a laser ultrasonic detection device arranged in the detection chamber. The infrared temperature measurement device is used to measure the temperature of the additive product, and the laser ultrasonic detection device is used for emitting and receiving laser light to measure the ultrasonic data of the additive product;

The mobile platform is used to carry the additive product and move between the forming cylinder and the inspection chamber.

Compared with the prior art, the present invention has at least the following beneficial effects:

In this embodiment, laser ultrasonic technology can perform non-contact non-destructive testing, has the advantages of long distance, wide frequency band, and high resolution, and can implement non-contact in-situ testing under high temperature conditions. Laser ultrasonic testing and temperature testing are performed on the additive material every time the preset thickness is printed, and multiple temperature data and multiple ultrasonic data are obtained. The ultrasonic data is processed to obtain the microstructure distribution data, defect data and residual stress data of the additive material. Temperature factors, microstructure factors and defect factors will affect the accuracy of residual stress data. Therefore, the obtained ultrasonic sound velocity data is corrected according to microstructure distribution data, defect data and temperature data to obtain more accurate residual stress correction data.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are For some embodiments of the present invention, those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a flow chart of an online detection method for metal additive manufacturing provided by an embodiment of the present invention;

Fig. 2 is a front view structural schematic diagram of an online detection device for metal additive manufacturing provided by an embodiment of the present invention;

Fig. 3 is a top view structural schematic diagram of an online detection device for metal additive manufacturing provided by an embodiment of the present invention;

Fig. 4 is a schematic diagram of the optical path of a laser ultrasonic online detection system provided by an embodiment of the present invention;

Fig. 5 is a waveform feature of a laser ultrasonic signal under a thermoelastic mechanism provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions 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 It is a part of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the protection of the present invention. scope.

In the description of the embodiments of the present invention, unless otherwise specified and limited, the terms "first" and "second" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance; unless otherwise specified Or to explain, the term "plurality" refers to two or more; the terms "connection", "fixation" and so on should be understood in a broad sense, for example, "connection" can be a fixed connection or a detachable connection, or Connected integrally, or electrically; either directly or indirectly through an intermediary. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the description of this specification, it should be understood that the orientation words such as "up" and "down" described in the embodiments of the present invention are described from the angles shown in the drawings, and should not be interpreted as a description of the embodiments of the present invention. limited. Furthermore, in this context, it also needs to be understood that when it is mentioned that an element is connected "on" or "under" another element, it can not only be directly connected "on" or "under" another element, but can also To be indirectly connected "on" or "under" another element through an intervening element.

An embodiment of the present invention provides a method for online detection of metal additive manufacturing, including:

Layer-by-layer printing is carried out through the additive process, and the laser ultrasonic technology is used to test the additive material for each printing preset thickness to obtain ultrasonic data; wherein, the additive material includes all layers obtained by the additive process;

Print layer by layer through the additive process, and use infrared temperature measurement technology to measure the temperature of the additive material for each printing preset thickness to obtain temperature data;

Determine the microstructure distribution data, defect data and residual stress data of the additive material according to the ultrasonic data;

The residual stress correction data is obtained according to the temperature data, microstructure distribution data and defect data.

In this embodiment, laser ultrasonic technology can be used for non-destructive testing, which has the advantages of long distance, wide frequency band, and high resolution, and can implement non-contact in-situ testing under high temperature conditions. Laser ultrasonic testing and temperature testing are performed on the additive material every time the preset thickness is printed, and multiple temperature data and multiple ultrasonic data are obtained. The ultrasonic data is processed to obtain the microstructure distribution data, defect data and residual stress data of the additive material. Temperature factors, microstructure factors and defect factors will affect the accuracy of residual stress data. Therefore, the obtained ultrasonic sound velocity data is corrected according to microstructure distribution data, defect data and temperature data to obtain more accurate residual stress correction data.

It should be noted that while the laser ultrasonic technology is used to detect the additive parts, the infrared temperature measurement technology can be used to measure the temperature of the additive material. The preset thickness can be one layer or multiple layers.

In some embodiments of the present invention, before determining the microstructure distribution data, defect data and residual stress data of the additive material according to the ultrasonic data, it includes:

The calibration test block is made by additive process;

Using the calibration test block to measure the sound velocity-stress mapping relationship;

Determine the microstructure distribution data, defect data and residual stress data of the additive material based on the ultrasonic data, including:

Determine the residual stress data according to the sound velocity-stress mapping relationship and the sound velocity of the ultrasonic data;

Determine the microstructure distribution data and defect data of the additive material according to the ultrasonic data.

In this embodiment, in order to obtain residual stress data from the measured ultrasonic data, it is necessary to establish a sound velocity-stress mapping relationship in advance. Specifically, a calibration test block is prepared by using the same additive process as the additive material preparation process. Since the additive process is the same, the obtained material is the same, and the sound velocity-stress mapping relationship between the two is also the same. By testing the calibration test block, the sound velocity-stress mapping relationship between the sound velocity and the stress is obtained, and the obtained sound velocity-stress mapping relationship is directly applied to the laser ultrasonic test of the additive material, and the obtained ultrasonic data is brought into the sound velocity-stress mapping In the relationship, the residual stress data of the additive material can be obtained.

In some embodiments of the present invention, the microstructure distribution data and defect data of the additive material are determined according to the ultrasonic data, including:

A two-dimensional ultrasound image is obtained by reconstructing the Rayleigh wave amplitude of the ultrasound data;

Determine the position information of the additive material defect according to the two-dimensional ultrasonic image, and obtain the defect data;

The microstructure distribution of the additive material is determined according to the two-dimensional ultrasonic image, and the microstructure distribution data is obtained.

In this embodiment, the ultrasonic data includes the amplitude and sound velocity of the Rayleigh wave, and the two-dimensional ultrasonic image is reconstructed according to the difference of the amplitude. When there is an obvious discontinuous distribution area in the two-dimensional ultrasonic image, the area is Defect position, recording the defect position to obtain the defect position. The microstructure distribution of the additive material is determined according to the two-dimensional ultrasonic image, and the microstructure distribution data is obtained.

In some embodiments of the present invention, after the calibration test block is prepared by the additive process, before the residual stress correction data is obtained according to the temperature data, microstructure distribution data, and defect data, it also includes:

Using the calibration test block to measure the sound velocity-microstructure distribution mapping relationship;

Using the calibration test block to measure the sound velocity-temperature mapping relationship;

Obtain residual stress correction data based on temperature data, microstructure distribution data, and defect data, including:

Obtaining a first sound velocity correction coefficient according to the temperature data and the sound velocity-temperature mapping relationship;

Obtaining the second sound velocity correction coefficient according to the microscopic data and the sound velocity-microstructure distribution mapping relationship;

The ultrasonic data is corrected according to the first sound velocity correction coefficient, the second sound velocity correction coefficient and defect data to obtain the ultrasonic sound velocity correction data; combined with the ultrasonic sound velocity correction data and the sound velocity-stress mapping relationship, the residual stress correction data is obtained.

In this embodiment, in order to correct the residual stress data, it is necessary to eliminate the influence of temperature, microstructure and defect location factors on the residual stress. Also use the calibration test block to obtain the sound velocity-temperature mapping relationship and the sound velocity-microstructure distribution mapping relationship through the test in advance, and substitute the measured temperature data and microstructure distribution data of the additive material into the sound velocity-temperature mapping relationship and sound velocity-microstructure distribution data respectively. According to the distribution mapping relationship, the influence of temperature on sound velocity and the influence of microstructure distribution on sound velocity are obtained, that is, the first sound velocity correction coefficient and the second sound velocity correction coefficient, and the ultrasonic data is corrected according to the first sound velocity correction coefficient and the second sound velocity correction coefficient, Eliminate the influence of temperature and microstructure distribution on the sound velocity to obtain more accurate ultrasonic sound velocity correction data, and use the ultrasonic sound velocity correction data combined with the sound velocity-stress mapping relationship to obtain more accurate residual stress data. Furthermore, when processing data, the ultrasonic data of the defect position is eliminated according to the defect data, so as to further improve the reliability of residual stress measurement.

In some embodiments of the present invention, the sound velocity-stress mapping relationship is measured by using the calibration test block, including:

Using the unidirectional tensile test to generate different tensile stresses in the calibration test block, apply ultrasonic waves to the calibration test block at the same time, measure the sound velocity of Rayleigh waves under different tensile stresses, and establish the sound velocity-stress mapping according to the tensile stress and sound velocity relation.

In this embodiment, the mapping relationship between material stress and Rayleigh wave velocity is obtained by performing stress-relief annealing on the additively manufactured components to obtain a zero-stress calibration test block, and then using uniaxial tensile experiments to test the zero-stress test block Different sizes of tensile stress are generated in the process, and the Rayleigh wave sound velocity under each stress state is measured at the same time to obtain the change relationship between the sound velocity change and the stress value, and to obtain the acoustoelastic constant, so as to facilitate the calculation of the residual stress according to the Rayleigh wave sound velocity change size. The metal additive parts under the same process were used to prepare tensile samples and perform stress relief annealing, and then the metal additive parts were tested by laser ultrasonic in situ under the condition of uniaxial tension, and the relationship between stress and Rayleigh wave was established. The mapping relationship of wave velocity provides a basis for the subsequent evaluation of the residual stress of metal additive parts by Rayleigh wave velocity method.

In some embodiments of the present invention, the sound velocity-microstructure distribution mapping relationship is measured by using the calibration test block, including:

Ultrasonic waves are applied to the calibration test block, and the Rayleigh wave amplitude and Rayleigh wave sound velocity with a mapping relationship are obtained in different areas of the calibration test block. Two-dimensional imaging is performed according to the difference in Rayleigh wave amplitude in different areas to obtain the microstructure distribution. The microstructure is combined with the Rayleigh wave sound velocity to obtain the sound velocity-microstructure distribution mapping relationship.

In this embodiment, the Rayleigh wave amplitude attenuation method is used for the evaluation of the material microstructure, that is, the microstructure at a specific position is used as the standard, and two-dimensional imaging is performed according to the difference in Rayleigh wave amplitude in different regions, so as to give Microstructure distribution of metal additive parts. When evaluating microstructure distribution, in order to more clearly reflect the difference in microstructure, it is necessary to control the frequency of ultrasonic Rayleigh waves in the Rayleigh scattering region according to the grain size of the material, and at the same time appropriately increase the distance between the exciting laser and the receiving laser. The distance increases the cumulative attenuation effect of the microstructure on the ultrasonic amplitude. Before obtaining the microstructure distribution of metal additive parts, it is necessary to carry out stress relief annealing treatment on the test piece of the part. The transformation relationship of Rayleigh wave velocity, so as to correct the change of Rayleigh wave velocity caused by the microstructure when measuring the residual stress of metal additive parts, and improve the measurement accuracy of residual stress.

In some embodiments of the present invention, the sound velocity-temperature mapping relationship is measured by using a calibration test block, including:

The calibration test block is continuously heated, and ultrasonic waves are applied to the calibration test block at the same time, the Rayleigh wave sound velocity of the calibration test block at different temperatures is monitored in real time, and the sound velocity-temperature mapping relationship is established.

In this embodiment, the relationship between Rayleigh wave velocity and material surface temperature, that is, the sound velocity-temperature mapping relationship, is obtained by continuously heating the zero-stress metal additive test block and monitoring the change of Rayleigh wave velocity in real time.

In some embodiments of the present invention, layer-by-layer printing is performed through the additive process, and the laser ultrasonic technology is used to test the additive material for each preset thickness of printing to obtain ultrasonic data, including:

Layer-by-layer printing is performed through the additive process, and the additive material is polished for each printing preset thickness, and then the additive material is tested by laser ultrasonic technology to obtain ultrasonic data.

In this embodiment, every time a layer with a preset thickness is printed, before performing laser ultrasonic testing, the surface of the newly obtained layer is polished to reduce the scattering of sound waves. It can be laser polishing, and the scanning speed and scanning distance are adjusted according to the laser energy and spot diameter, so that the surface roughness is below 0.1 μm.

In some embodiments of the present invention, the calibration test block is a zero stress test block obtained by stress relief annealing.

In this embodiment, the stress-relieving annealing treatment can eliminate the influence of material stress on the Rayleigh wave velocity, and at the same time, the transformation relationship between the microstructure and the Rayleigh wave velocity in the stress-free state can be obtained, so that when measuring the residual metal additive parts During stress, the Rayleigh wave velocity change caused by the microstructure is corrected to improve the measurement accuracy of residual stress.

The embodiment of the present invention also provides an online detection device for metal additive manufacturing, which is used to implement any of the above methods, and the device includes:

Additive unit, detection unit and mobile platform;

The additive unit includes a laser emitting component and a working chamber. The laser emitting component is used to provide laser beams. The working chamber includes a forming cylinder, a powder feeding cylinder and a powder recovery cylinder. The powder feeding cylinder is used to provide powder for the forming cylinder, and the forming cylinder is used to The powder is shaped by the action of the laser, and the powder recovery cylinder is used to recover the excess powder;

The detection unit includes a detection chamber and an infrared temperature measuring device and a laser ultrasonic detection device arranged in the detection chamber. Ultrasonic data of the workpiece;

The mobile platform is used to carry the additive parts and move between the forming cylinder and the inspection chamber.

Taking metal powder bed molten metal additive manufacturing of TC4 titanium alloy parts as an example, the content and specific implementation of the present invention are described in detail. As shown in Figure 2, the laser power is 0.5kW, the laser scanning speed is 600mm/min, the feed rate is 10.5g/min, the spot diameter is 2.0mm, and the coverage rate is 60%. First, prepare a metal additive product with a thickness L on the substrate of the forming cylinder. The relationship between the thickness L of the product, the number of scanning layers N, and the thickness d of a single layer scanning is L=N*d. After the preparation is completed The surface of the workpiece is laser polished by using the additive manufacturing laser. Laser polishing is carried out in a multi-pass (at least 4 passes) scanning mode, and the scanning direction between each two passes is 90° different. The scanning speed and scanning distance are adjusted according to the laser energy and spot diameter, so that the surface roughness is 0.1 μm, and determine the optimal polishing process parameters. In the last pass, the laser energy is reduced, and the polished surface is impacted under thermoelastic conditions, so as to eliminate the additional residual stress introduced by the polishing process as much as possible.

As shown in Figure 3, after the surface polishing of the workpiece is completed, it is quickly transferred to the detection cylinder for residual stress testing, as well as the characterization of the microstructure and typical defects. First, the infrared thermal imaging camera completes the measurement of the temperature field on the surface of the workpiece through the detection window. After that, the laser emission and the receiving laser are triggered synchronously, and an ultrasonic signal is generated on the surface of the workpiece in the form of thermoelastic excitation, and the laser ultrasonic signal is received by the dual-wave hybrid interference method. Signal. In this process, in order to improve the signal-to-noise ratio of the ultrasonic signal, a cylindrical mirror is used to shape the point laser source into a line laser source. Both the emitting laser and the receiving laser are perpendicular to the surface of the workpiece. The requirements of rate and scanning efficiency are adjusted. After the signal acquisition at a certain position is completed, the three-axis mobile platform drives the workpiece to move in a stepwise scanning manner in the x-y plane to realize the acquisition of two-dimensional ultrasonic data. During this process, the coordinates of the ultrasonic signal collection location and the temperature data of the detection area at the collection moment are saved synchronously. After the ultrasonic signal is collected on the surface of the workpiece, it is transferred back to its original position in the forming cylinder, and the subsequent additive manufacturing process is continued. The thickness of each addition is controlled within the wave field range of the ultrasonic Rayleigh wave until the overall thickness of the workpiece reaches the specified thickness. During the entire manufacturing and testing process, the workpiece is always in a protective gas atmosphere to avoid surface oxidation of the workpiece.

The schematic diagram of the laser ultrasonic testing system is shown in Figure 4. The emitting laser adopts a pulse laser with a wavelength of 1064nm, a pulse repetition frequency of 100Hz, and continuously adjustable energy. The circular point laser source is focused into a line laser source through a cylindrical mirror. The pulsed laser is irradiated on the designated position of the sample to be tested through the dichroic mirror. At the same time, the detection laser adopts a continuous laser with a wavelength of 532nm, which is transmitted to the collimator through an optical fiber for beam collimation, and then divided into a reference beam and a detection beam by a polarization beam splitter. Wherein, the reference beam is reflected by the reflector to the surface of the photodetector, and the detection beam is reflected by the dichroic mirror and irradiates on the surface of the sample to be measured. After the detection beam is reflected by the surface of the sample, it is reflected to the photodetector according to the optical path in Figure 4, and has a stable interference with the reference beam. The laser interference pattern is converted into an analog voltage signal by the photodetector and stored in the oscilloscope. Part of the emitted laser light received by the photodetector is used as a synchronous trigger signal between the emitting laser and the detecting laser to complete the synchronization of ultrasonic excitation and reception. The continuous adjustment of the distance between the emitting laser and the receiving laser is realized by adjusting the angle of the reflector in the optical path of the emitting laser.

In order to realize the synchronization of the additive manufacturing process and the online quality monitoring process, and ensure the reliability of the monitoring results, the workflow of the equipment system as shown in Figure 1 is specially designed. Among them, the forming cylinder is mainly used to complete the preparation of metal additive parts and its surface polishing treatment. This process can minimize the decrease in preparation efficiency caused by surface polishing, and the polishing treatment can also help reduce metal additive manufacturing. The formation of various internal defects. The detection cylinder is mainly used to complete the surface temperature monitoring and laser ultrasonic detection of metal additive parts. Among them, the surface temperature monitoring will be carried out synchronously during the excitation and reception of ultrasonic signals.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (10)

1. A method for online detection of metal additive manufacturing, characterized in that, comprising: The layer-by-layer printing is carried out through the additive process, and the laser ultrasonic technology is used to test the additive material for each printing preset thickness to obtain ultrasonic data; wherein, the additive material includes all layers obtained by the additive process; Print layer by layer through the additive process, and use infrared temperature measurement technology to measure the temperature of the additive material for each printing preset thickness to obtain temperature data; determining microstructure distribution data, defect data and residual stress data of the additive material according to the ultrasonic data; The residual stress correction data is obtained according to the temperature data, microstructure distribution data and defect data. 2. The method according to claim 1, wherein, before determining the microstructure distribution data, defect data and residual stress data of the additive material according to the ultrasonic data, the method comprises: A calibration test block is prepared by the additive process; Using the calibration test block to measure the sound velocity-stress mapping relationship; The determining the microstructure distribution data, defect data and residual stress data of the additive material according to the ultrasonic data includes: determining the residual stress data according to the sound velocity-stress mapping relationship and the sound velocity of the ultrasonic data; The microstructure distribution data and defect data of the additive material are determined according to the ultrasonic data. 3. The method according to claim 2, wherein the determining the microstructure distribution data and defect data of the additive material according to the ultrasonic data includes: Obtaining a two-dimensional ultrasonic image according to the Rayleigh wave amplitude reconstruction of the ultrasonic data; Determining the position information of the defect of the additive material according to the two-dimensional ultrasonic image to obtain the defect data; Determining the microstructure distribution of the additive material according to the two-dimensional ultrasonic image to obtain the microstructure distribution data. 4. The method according to claim 3, characterized in that, after the calibration test block is made by the additive process, the residual stress is obtained according to the temperature data, microstructure distribution data, and defect data. Before correcting the data, also include: Using the calibration test block to measure the sound velocity-microstructure distribution mapping relationship; Using the calibration test block to measure the sound velocity-temperature mapping relationship; The obtaining residual stress correction data according to the temperature data, microstructure distribution data, and defect data includes: Obtaining a first sound velocity correction coefficient according to the temperature data and the sound velocity-temperature mapping relationship; Obtaining a second sound velocity correction coefficient according to the microscopic data and the sound velocity-microstructure distribution mapping relationship; Correct the ultrasonic data according to the first sound velocity correction coefficient, the second sound velocity correction coefficient and defect data to obtain ultrasonic sound velocity correction data; combine the ultrasonic sound velocity correction data and the sound velocity-stress mapping relationship to obtain the residual Stress Correction Data. 5. The method according to claim 2, wherein said utilizing said calibration test block to measure the sound velocity-stress mapping relationship comprises: A unidirectional tensile test is used to generate tensile stresses of different sizes in the calibration test block, and ultrasonic waves are applied to the calibration test block at the same time to measure the sound velocity of Rayleigh waves under different tensile stresses, and to establish according to the tensile stress and sound velocity The sound velocity-stress mapping relationship. 6. method according to claim 4, is characterized in that, described utilizing described calibration test block to measure sound velocity-microstructure distribution mapping relationship, comprising: Apply ultrasonic waves to the calibration test block, obtain the Rayleigh wave amplitude and Rayleigh wave sound velocity with a mapping relationship in different areas of the calibration test block, and perform two-dimensional imaging according to the difference in the Rayleigh wave amplitude in different areas , to obtain the microstructure distribution, and combine the microstructure with the Rayleigh wave sound velocity to obtain the sound velocity-microstructure distribution mapping relationship. 7. method according to claim 4, is characterized in that, described utilizing described calibration test block to measure sound velocity-temperature mapping relationship, comprising: The calibration test block is subjected to continuous heating treatment, and ultrasonic waves are applied to the calibration test block at the same time, the Rayleigh wave sound velocity of the calibration test block at different temperatures is monitored in real time, and the sound velocity-temperature mapping relationship is established. 8. The method according to claim 1, wherein the layer-by-layer printing is carried out through the additive process, and the laser ultrasonic technology is used to test the additive material for each preset thickness of printing, and the ultrasonic data is obtained, including: Layer-by-layer printing is performed through the additive process, and the additive material is polished for each printing preset thickness, and then the additive material is tested by laser ultrasonic technology to obtain ultrasonic data. 9. The method according to claim 2, wherein the calibration test block is a zero-stress test block obtained by stress relief annealing. 10. An online detection device for metal additive manufacturing, characterized in that it is used to implement the method according to any one of claims 1-9, the device comprising: Additive unit, detection unit and mobile platform; The additive unit includes a laser emitting assembly and a working chamber, the laser emitting assembly is used to provide laser beams, the working chamber includes a molding cylinder, a powder feeding cylinder and a powder recovery cylinder, and the powder feeding cylinder is used for the The molding cylinder provides powder, the molding cylinder is used to shape the powder under the action of the laser, and the powder recovery cylinder is used to recover excess powder; The detection unit includes a detection chamber and an infrared temperature measuring device and a laser ultrasonic detection device arranged in the detection chamber. The infrared temperature measurement device is used to measure the temperature of the additive product, and the laser ultrasonic detection device is used for emitting and receiving laser light to measure the ultrasonic data of the additive product; The mobile platform is used to carry the additive product and move between the forming cylinder and the inspection chamber.

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