WO2021248588A1 - Real-time monitoring device for laser near-net shape manufacturing, and manufacturing apparatus and method - Google Patents

Abstract

Disclosed are a real-time monitoring device for laser near-net shape manufacturing, and a manufacturing apparatus and method. In the design of the monitoring device, an annular monitoring motion platform (200) and a 360° rotary machining table (15), which are coaxially arranged, are provided; a molten pool morphology monitoring portion and a workpiece three-dimensional profile monitoring portion are arranged beside a laser machining head (7) and maintain a synchronous motion therewith; a laser ultrasonic monitoring portion, a molten pool temperature distribution monitoring portion, a stress-strain monitoring portion (100) and a laser-induced breakdown spectroscopy monitoring portion (300) are carried on the annular monitoring motion platform (200); and a CT defect monitoring portion is carried beside the annular monitoring motion platform (200). The components cooperate with each other to achieve omnidirectional, real-time and online monitoring of parameters of a workpiece in a laser near-net shape manufacturing process. The monitoring device has the advantages of simple structure, convenient operation, high applicability, etc.

Description

Real-time monitoring device, forming equipment and method for laser near-net forming 【Technical Field】

The present invention belongs to the technical field of laser near net shaping, and more specifically, relates to a real-time monitoring device, forming equipment and method for laser near net shaping.

【Background technique】

As a new type of production process, laser near-net forming technology combines new technologies such as numerical control, computer, and laser, and realizes the manufacture of three-dimensional metal parts through the method of cladding metal powder particles layer by layer by laser. Compared with traditional processing methods, it has the advantages of fewer processing procedures, shorter cycle, more types of materials, and the ability to process parts with complex shapes. It is widely used in industrial manufacturing, biomedical, aerospace and other fields.

Due to the processing characteristics of laser near-net forming process layer by layer laser cladding and rapid melting and solidification of metal powder particles, the workpiece is prone to defects such as layer separation, three-dimensional contour deformation, non-fusion, holes and cracks, which seriously affect the performance and working life of the product , Especially in the manufacturing process of large components, the accumulation of small defects will eventually lead to product processing failure. Therefore, in the process of processing, it is necessary to conduct real-time online non-destructive monitoring of each processing step, especially to monitor the parameters that directly affect the quality and performance of the workpiece, such as the temperature distribution of the molten pool, the change of the molten pool shape, and the three-dimensional contour of the processing part Deformation, stress field distribution of the workpiece and internal defects, etc.

At present, there is no device in this field that can simultaneously realize the online real-time monitoring of the above-mentioned multiple parameters of laser near-net-shaping. Therefore, research and design are needed in this field to obtain a real-time monitoring device suitable for laser near-net-shaping. , In order to realize the real-time online measurement of multiple parameters in the laser near-net-shaping process to guide the subsequent laser near-net-shaping.

[Summary of the invention]

In view of the above defects or improvement needs of the prior art, the present invention provides a real-time monitoring device, forming equipment and method for laser near-net forming, which monitors key components such as a circular motion platform and a 360° rotating processing table. And the design of the specific assembly relationship of multiple monitoring parts can realize the all-round real-time measurement of multiple parameters of the laser near-net-shaped workpiece. It has the advantages of simple structure, convenient operation, and strong applicability.

In order to achieve the above objective, according to one aspect of the present invention, a real-time monitoring device for laser near-net forming is proposed, which includes a laser ultrasonic monitoring part, a molten pool shape monitoring part, a molten pool temperature distribution monitoring part, and a three-dimensional contour of a workpiece. Monitoring department, stress and strain monitoring department, laser-induced breakdown spectroscopy monitoring department, CT defect monitoring department, circular monitoring motion platform and 360°rotating processing table, including:

The laser ultrasonic monitoring unit, the molten pool temperature distribution monitoring unit, the stress and strain monitoring unit, and the laser induced breakdown spectrum monitoring unit are installed on the annular monitoring motion platform and face the workpiece to be monitored; the molten pool shape monitoring unit and The workpiece three-dimensional contour monitoring part is installed on the side of the laser processing head used to perform laser near-net shaping, and keeps synchronous movement with the laser processing head; the CT defect monitoring part is installed on the side of the ring-shaped monitoring movement platform for realizing Monitoring of internal defects of the workpiece; the ring-shaped monitoring movement platform is arranged outside and coaxially with the 360° rotating processing table, and the 360° rotating processing table is used to drive the workpiece to be tested to rotate 360° to ensure Each monitoring department monitors the workpiece in 360°, and then realizes the online real-time measurement of multiple parameters of the laser near-net shape.

As a further preference, the circular monitoring motion platform includes a circular motion track and a lifting device. When the workpiece forms a height of each layer, the lifting device correspondingly raises the circular motion track by one level, so that the circular monitoring motion platform is Each monitoring department always monitors the part of the workpiece to be monitored.

As a further preference, the laser ultrasonic monitoring part includes an excitation laser and a detection laser, wherein the excitation laser is used to inject a pulsed laser beam on the surface of the workpiece to be detected to generate an ultrasonic signal, and the ultrasonic wave is in contact with the near surface of the workpiece. The defects interact and are reflected back to the surface of the workpiece and are received by the detection laser.

As a further preference, the molten pool shape monitoring unit is preferably a near visible hyperspectral camera; the molten pool temperature distribution monitoring unit is preferably an ultra-high-speed photoelectric thermometer; the workpiece three-dimensional contour monitoring unit is preferably a high-speed industrial camera .

As a further preference, the stress and strain monitoring part includes a bottom strain measurement mechanism and a side strain measurement mechanism, wherein the bottom strain measurement mechanism includes a strain signal analyzer and a strain measurement sensor array connected to each other, and the strain signal analyzer Installed at the bottom of the 360° rotating processing table, the strain measurement sensor array is embedded in the substrate for placing the workpiece to measure the strain at the bottom of the workpiece; the side strain measurement mechanism is an industrial camera, which is installed on A beam splitter is arranged on the ring-shaped monitoring movement platform and between the workpiece; preferably, the strain measurement sensor array has a temperature compensation function.

As a further preference, the laser-induced breakdown spectrum monitoring unit includes a detector and a spectrograph that are connected to each other, and the detector is used to detect and acquire the plasma light emitted from the surface of the workpiece, and transmit the plasma light to the spectrograph. In order to realize the detection of the element composition and content of the material prepared by the workpiece.

As a further preference, the CT defect monitoring unit includes an X-ray source and an X-ray detector. The X-ray source and the X-ray detector are located on both sides of the workpiece. The X-ray source is used to emit X-rays. After penetrating the workpiece, it is received by the X-ray detector.

As a further preference, the laser ultrasonic monitoring section uses ultrasonic waves with a wavelength of 0.4mm to 0.5mm for detection, and the molten pool shape monitoring section and the molten pool temperature distribution monitoring section use infrared light with a wavelength of 780nm to 950nm for detection, and the workpiece is three-dimensional The profile monitoring section and the stress-strain monitoring section use visible light with a wavelength of 446mm～464mm for detection, the laser induced breakdown spectroscopy monitoring section uses a laser with a wavelength of 530nm～540nm for detection, and the CT defect monitoring section uses a wavelength of 10 ^-3 nm～10nm. X-ray detection; preferably, narrow band-pass filter design is performed on the molten pool shape monitoring part, the molten pool temperature distribution monitoring part, the workpiece three-dimensional contour monitoring part, and the stress and strain monitoring part.

According to a second aspect of the present invention, there is provided a laser near-net shape forming device with real-time monitoring function. The forming device includes a laser processing device, a control device, and the real-time monitoring device, wherein the laser processing device uses For performing laser near-net shaping, the real-time monitoring device is used for real-time monitoring of the workpiece during the laser near-net shaping process, and the monitored data is fed back to the control device, which is based on the dynamics of the monitoring data fed back by the real-time monitoring device Adjust the laser near-net-shaping process parameters, and control the action of the laser processing device based on the dynamically adjusted parameters, so as to achieve the preparation of high-quality laser near-net-shaping workpieces.

According to the third aspect of the present invention, a laser near-net-shaping method with real-time monitoring function is provided, which includes the following steps:

1) The laser processing device is used to print the single-layer cladding layer of the workpiece to be formed. During the printing process, the bottom strain measuring mechanism of the molten pool shape monitoring unit, the molten pool temperature distribution monitoring unit, and the stress and strain monitoring unit work in real time to achieve Real-time monitoring of the dynamic profile of the molten pool, the temperature distribution of the molten pool and the strain at the bottom of the workpiece;

2) After the single-layer cladding layer is printed, the laser processing device returns to the preset origin and pauses, the workpiece three-dimensional contour monitoring department, laser ultrasonic monitoring department, CT defect monitoring department, laser induced breakdown spectroscopy monitoring department, and stress-strain monitoring department The side strain measuring mechanism of the slab starts to work synchronously or time-sharing to realize the real-time monitoring of the three-dimensional contour of the workpiece, the near surface defect of the workpiece, the internal defect of the workpiece, the element composition and content of the workpiece preparation material, and the side strain of the workpiece. 360°rotating during the inspection process The processing table drives the workpiece to rotate 360° to ensure that each monitoring department scans the workpiece in all directions, realizing the purpose of all-round real-time online monitoring;

3) Each monitoring department feeds back the monitored data to the control device, which dynamically adjusts the process parameters of the laser near-net forming based on the monitoring data fed back by the real-time monitoring device, and the dynamically adjusted process parameters are used as the next layer of cladding layer Printing process;

4) Repeat steps 1) to 3) to achieve the laser near-net shape of the desired workpiece.

Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention mainly have the following technical advantages:

1. The present invention has designed a real-time monitoring device suitable for laser near-net-shaping, which can realize multiple parameters in the laser near-net-shaping process (such as workpiece near-surface defects, molten pool dynamic profile contour, molten pool On-line real-time measurement of temperature distribution, three-dimensional contour morphology of the workpiece, strain on the bottom and side of the workpiece, element composition of the workpiece, and internal defects of the workpiece). The use of these parameter data can guide the subsequent laser near-net forming, thereby improving the laser near-net forming of the workpiece the quality of.

2. The present invention can install multiple real-time online monitoring devices by building a ring-shaped monitoring movement platform. When a layer is processed, the monitoring device installed on it can be driven to increase the height of a printing layer, ensuring that the monitoring device can accurately focus on The monitoring point, through the construction of a 360° rotating processing table equipped with a circular monitoring motion platform, drives the workpiece to rotate 360°, ensuring that the workpiece can be scanned in all directions, and realizing the purpose of all-round real-time online monitoring of the contour of the workpiece At the same time, by designing the molten pool shape monitoring part and the workpiece three-dimensional contour monitoring part to keep synchronized movement with the laser processing head, it can ensure the all-round and accurate scanning and monitoring of the molten pool shape and the three-dimensional contour of the workpiece.

3. The present invention uses laser ultrasonic detection technology to monitor the near-surface hole and crack defects of the workpiece. It uses the mechanism of laser acting on the surface of the workpiece to excite ultrasonic waves. Ultrasound is transmitted and diffused from the interior of the workpiece, and ultrasonic signals at different distances from the excitation point are extracted and analyzed. In this way, the position and morphological distribution of defects in the workpiece can be judged. This method can perform non-destructive real-time online non-destructive inspection of the interior of the workpiece while ensuring the detection accuracy.

4. In the process of monitoring the shape and temperature of the molten pool, the present invention uses a near-visible hyperspectral camera that operates synchronously with the laser head for shape measurement, and an ultra-high-speed photoelectric thermometer for temperature measurement. The measurement accuracy of the molten pool profile can be achieved. Up to 0.001mm, the temperature measurement accuracy can be as large as ±5℃, which can effectively eliminate the influence of environmental noise and quickly and accurately determine the molten pool area.

5. The present invention measures the bottom surface strain of the processed part through the strain measurement sensor array installed in the substrate, and records the speckle distribution of the laser spot on the side of the sample through an industrial camera, so as to realize the measurement of the side strain of the processed part. The hardware combination uses optical measurement and electrical measurement to realize the omni-directional strain measurement of the workpiece. In addition, the stress can be reversed based on the measured stress combined with the existing finite element calculation hybrid method to achieve efficient real-time non-contact And non-destructive stress testing.

6. The present invention uses laser-induced breakdown spectroscopy non-destructive online detection to perform qualitative and quantitative analysis and detection of elemental composition of processed parts, and uses the peeling phenomenon caused by the action of pulsed laser on the processed parts to induce plasma light radiation around the molten metal pool. Perform detection and spectral analysis to provide environmental cleanliness support for controlling the quality of additive manufacturing components.

7. The CT defect monitoring part of the present invention transmits X-rays through the X-ray source through the workpiece and is received by the X-ray detector, and transmits the information to the computer control system to obtain internal defects and geometric contour images of the workpiece. Intuitively detect the type, location and size of the internal defects of the processed parts. Due to the large volume of the CT defect detection device, the present invention installs it on the side of the annular monitoring platform to reduce the load-bearing pressure of the annular monitoring platform and improve the stability of the device.

8. Since the monitoring device of the present invention contains multiple monitoring components, there will be a certain amount of interference between each other. In order to prevent the different monitoring components from interfering with each other when working, and avoid the interference of light and vibration between the detection methods, the present invention The detection methods and detection wavelengths of each monitoring department have been researched and designed. The specific laser ultrasonic monitoring department uses ultrasonic waves with a wavelength of 0.4mm～0.5mm for detection, and the molten pool shape monitoring department and the molten pool temperature distribution monitoring department use a wavelength of 780nm ～950nm infrared light is used for detection, workpiece 3D contour monitoring part and stress strain monitoring part use visible light with wavelength of 446mm～464mm for detection, laser induced breakdown spectroscopy monitoring part uses laser with wavelength of 530nm～540nm for detection, CT defect monitoring The part uses X-rays with a wavelength of 10-3nm～10nm for detection; through the above design, interference between monitoring components can be effectively avoided.

9. The present invention also proposes a laser near-net-shaping device and method equipped with the real-time monitoring device of the present invention, which can dynamically adjust the laser near-net-shaping process based on the data monitored by the real-time monitoring device in real time, thereby realizing laser Close-loop control of the near-net-shape forming process, thereby improving the quality and performance of the processed parts as a whole.

10. In the present invention, during the printing process, the molten pool shape monitoring unit, the molten pool temperature distribution monitoring unit, and the bottom strain measuring mechanism work in real time. After the printing is completed, the workpiece three-dimensional contour monitoring unit, the laser ultrasonic monitoring unit, and the CT defect monitoring unit , The laser-induced breakdown spectroscopy monitoring unit and the side strain measuring mechanism start to work synchronously or step by step, so as to realize the time delay measurement, avoid the interference between the components and avoid the influence of the molten pool on the detection results, thereby improving the detection Accuracy.

11. In addition, the present invention also implements a narrow band-pass filter design for the molten pool shape monitoring part, the molten pool temperature distribution monitoring part, the workpiece three-dimensional contour monitoring part and the stress strain monitoring part to eliminate the interference of the laser heat source and improve the monitoring accuracy.

【Explanation of the drawings】

FIG. 1 is a schematic structural diagram of a laser near-net-shaping device with real-time monitoring function provided by an embodiment of the present invention;

2 is a schematic diagram of the assembly structure between the annular monitoring movement platform and each monitoring part provided by an embodiment of the present invention;

3 is a schematic structural diagram of a stress and strain monitoring part provided by an embodiment of the present invention;

Fig. 4 is a schematic structural diagram of a laser induced breakdown spectroscopy monitoring unit provided by an embodiment of the present invention.

In all the drawings, the same reference numerals are used to denote the same elements or structures, in which:

1-computer control system, 2-manipulator control cabinet, 3-fiber coupler, 4-axial robot, 5-manipulator, 6-transmission fiber, 7-laser processing head, 8-powder feeding device, 9-protection Gas supply device, 10-detection laser, 11-ultra-high-speed photoelectric thermometer, 12-worktable, 13-substrate, 14-strain measurement sensor array, 15-360°rotating processing table, 16-workpiece, 17-high speed Industrial camera, 18-approximately visible hyperspectral camera, 19-excitation laser, 20-fixed frame, 21-X-ray source, 22-X-ray detector, 100-stress and strain monitoring department, 200-circular monitoring motion platform, 300 -Laser-induced breakdown spectrum monitoring department, 101-strain signal analyzer, 102-spectroscope, 103-industrial camera, 201-circular motion track, 202-lifting device, 301-plasma light, 302-detector, 303-spectrum Camera, 304-fiber cable, 305-plasma.

【detailed description】

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

As shown in Figure 1, the embodiment of the present invention provides a real-time monitoring device for laser near-net forming, which includes a laser ultrasonic monitoring unit, a molten pool shape monitoring unit, a molten pool temperature distribution monitoring unit, and a workpiece three-dimensional contour monitoring unit , Stress and strain monitoring department, laser-induced breakdown spectroscopy monitoring department 300, CT defect monitoring department, circular monitoring movement platform 200 and 360°rotating processing table 15.

Among them, the laser ultrasonic monitoring part is used to monitor defects such as near-surface holes and cracks of the workpiece, the molten pool shape monitoring part is used to monitor the dynamic profile contour of the molten pool, and the molten pool temperature distribution monitoring part is used to monitor the temperature distribution of the molten pool. The workpiece three-dimensional contour monitoring department is used to monitor the three-dimensional contour of the workpiece, the stress-strain monitoring department is used to monitor the stress field distribution of the workpiece, and the laser-induced breakdown spectroscopy monitoring department is used to realize the qualitative and quantitative detection of the element composition of the workpiece preparation material. The CT defect monitoring department is used to monitor the internal defects of the workpiece. Specifically, laser ultrasonic monitoring acts on the defects in the near surface of the print, and detects the approximate location, type and size of the defect by analyzing the ultrasonic signal. CT defect monitoring uses X-rays to penetrate the print and receives it by the X-ray detector. The processing can restore the image inside the print, and the defects can be seen more intuitively and clearly.

Specifically, the laser ultrasonic monitoring unit, the molten pool temperature distribution monitoring unit, the stress-strain monitoring unit, and the laser-induced breakdown spectrum monitoring unit are installed on the ring-shaped monitoring movement platform 200 and face the workpiece to be monitored; the molten pool shape monitoring unit and the workpiece three-dimensional The contour monitoring unit is installed on the side of the laser processing head used to perform laser near-net shaping, and keeps moving synchronously with the laser processing head; the CT defect monitoring unit is located on the side of the ring-shaped monitoring movement platform 200 to realize internal defects of the workpiece Monitoring. The annular monitoring motion platform 200 is arranged outside the 360° rotating processing table 15 and coaxially arranged with the 360° rotating processing table. The 360° rotating processing table 15 is used to drive the workpiece to rotate 360° to ensure that each monitoring unit Perform 360-degree monitoring of the workpiece, and then realize the multi-parameter online real-time monitoring of laser near-net forming.

As shown in Figure 2, the circular monitoring motion platform 200 includes a circular motion track 201 and a lifting device 202. The circular motion track 201 is arranged outside the 360° rotating processing table 15 and coaxially arranged with the 360° rotating processing table. The circular motion track 201 is centered on the workpiece and can move up and down through the lifting device. A laser ultrasonic monitoring part, a molten pool temperature distribution monitoring part, a stress-strain monitoring part 100 and a laser-induced breakdown spectroscopy monitoring part are installed on the circular motion track 201. When the workpiece 16 is processed by layer-by-layer cladding, the lifting device 202 lifts the circular motion track 201 by one layer of powder spreading height for each layer of processing height, and the designed 360° rotating worktable 15 drives the workpiece 16 to rotate. It can be scanned and monitored in all directions. Through the action of the lifting device 202, the monitoring parts placed on the circular motion track 201 are always focused on the part being processed, so as to achieve the purpose of real-time online monitoring. The 360° rotating processing table is powered by an electric motor. Its function is to drive the substrate and the workpiece on it to rotate around the center together, so that the monitoring device installed around can monitor the workpiece on the substrate in all directions without dead angles to achieve The purpose of real-time monitoring of processed parts.

Since there are many monitoring fields involved, including laser ultrasonic monitoring of processed samples, temperature distribution monitoring of molten pool, stress and strain monitoring, laser induced breakdown spectroscopy, etc., a layer of metal powder will rise after each layer of processed parts is processed. The height of the particles, in order to solve the problem of the installation and positioning of the monitoring device, the present invention designs the above-mentioned annular monitoring motion platform and a 360° rotating processing table to realize the assembly of the monitoring devices and the rotation of the workpiece, and realize the comprehensive real-time monitoring Features.

1 and 2, the laser ultrasonic monitoring unit includes an excitation laser 19 and a detection laser 10, the detection laser is installed on the circular motion track 201, and the excitation laser 19 is installed on the detection laser 10. Among them, the excitation laser 19 incidents the pulsed laser beam on the surface of the workpiece to be inspected, causing the workpiece 16 to locally produce rapid thermal expansion. The excited ultrasonic wave propagates inside the workpiece and interacts with the defects inside the workpiece, and is finally reflected back to the surface of the workpiece for detection. The laser 10 receives the ultrasonic signal reflected on the surface of the workpiece after the interaction, and transmits it to the computer control system for processing. It has the characteristics of high resolution, wide frequency band, high energy and non-contact, which is higher than traditional monitoring methods. Detection accuracy. By detecting the ultrasonic signal obtained by the laser 10, it is possible to analyze whether there are defects (such as cracks, holes, non-fusion, stress concentration), types and locations on the near surface of the workpiece, and adjust the laser scanning strategy and processing parameters based on the analysis results. The specific analysis method can be carried out by the existing conventional method, which will not be repeated here.

Specifically, the molten pool shape monitoring unit is preferably close to the visible hyperspectral camera 18, which is installed on the side of the laser processing head 7 through a fixing frame 20, and moves synchronously with the laser processing head. By adjusting its angle, it can be ensured that it is in line with the laser processing. The head scanning position is consistent, real-time monitoring of the dynamic characteristics and contours of the metal molten pool. The near-visible hyperspectral camera can eliminate the influence of environmental noise, quickly and accurately determine the molten pool area, and the obtained image information is transmitted to the computer control system 1 for analysis, and the computer control system 1 controls the single-channel scanning based on the obtained information Parameters such as height, laser power and energy density can be used to improve processing quality in real time.

Further, the temperature distribution monitoring part of the molten pool is preferably an ultra-high-speed photoelectric thermometer 11, which is installed on the circular motion track 201 for real-time monitoring of the temperature distribution around the metal molten pool, and judges whether the temperature distribution gradient of the molten pool is If the temperature distribution gradient is too large, it can be fed back to the computer control system to adjust processing parameters, such as laser power, scanning distance, laser spot radius, and scanning speed, so as to improve the temperature distribution.

3, the stress and strain monitoring part includes a bottom strain measurement mechanism and a side strain measurement mechanism, wherein the bottom strain measurement mechanism includes a strain signal analyzer 101 and a strain measurement sensor array 14 connected to each other, and the strain signal analyzer 101 is installed at 360° At the bottom of the rotating processing table, electrical signals are transmitted through cable connections. There is a certain area at the bottom of the print, and the strain measurement sensor array 14 is designed for array distribution to measure the strain of each part, making the measurement of the strain at the bottom of the print more accurate. The strain measurement sensor array 14 is embedded in the substrate 13 to measure the strain at the bottom of the workpiece. The side strain measuring mechanism is preferably an industrial camera 103, which is installed on the circular motion track 201, and a beam splitter 102 is arranged between it and the workpiece.

In the initial stage of the processing of the workpiece, the metal powder particles are directly spread on the substrate 13 for laser processing. The strain monitoring of the workpiece is sensed by the strain measurement sensor array 14 pre-installed inside the substrate 13, and the array distribution optimization design of the sensor is used to obtain the substrate. The strain field distribution. Since the substrate needs to be preheated when printing the bottom layer, and the temperature increase will affect the measurement effect of the sensor, the strain measurement sensor array 14 is designed with a temperature compensation function to eliminate the effect of temperature increase. The signal measured by the strain measurement sensor array 14 is transmitted to the strain signal analyzer 101 for processing, combined with the finite element calculation method for stress inversion, to achieve non-destructive measurement of the stress at the bottom of the workpiece, and how to achieve the stress inversion is an existing technology. I won't repeat them here. In the middle and later stages of processing, the industrial camera 103 installed on the circular motion track 201 measures the side strain of the workpiece. Specifically, a laser beam is used to irradiate the side of the workpiece to generate speckles. The industrial camera obtains the speckle image through a 360° rotating The processing table drives the workpiece to rotate, and measures the side strain of the workpiece in all directions. Then, the strain is calculated according to the image obtained by the industrial camera through the conventional digital correlation analysis method, and the strain data and the finite element calculation method are combined to perform stress inversion to realize the stress on the side surface of the workpiece without damage The measurement, specifically how to achieve stress inversion, is an existing technology, and will not be repeated here.

Specifically, the workpiece three-dimensional contour monitoring part is preferably a high-speed industrial camera 17, which is installed beside the laser processing head and moves synchronously with the laser processing head. Specifically, the fixed frame 20 is installed beside the laser processing head 7 to ensure the synchronous movement of the robot arm during processing, real-time scanning of the outer contour of the processed part to obtain the workpiece image, and accurate edge contour extraction through the workpiece image, which is consistent with the designed workpiece The ideal contour size is compared, the warpage defect of the processing plane and the surface contour size error are identified and analyzed, and the analysis data is transmitted to the computer control system 1 to adjust the scanning trajectory.

4, the laser induced breakdown spectrum monitoring unit 300 includes a detector 302 and a spectrograph 303 connected to each other. The detector 302 and the spectrograph 303 are connected by an optical fiber cable 304, and the spectrograph 303 is installed on the circular motion track 201. superior. During detection, a pulsed laser is applied to the surface of the workpiece 16 to produce a peeling phenomenon, and a plasma 305 with a short life but high brightness is generated on the surface of the material. The plasma 305 expands outward at supersonic speed and cools rapidly. During this time , The atoms and ions in the excited state transition from the high-energy state to the low-energy state, and emit plasma light 301 with a specific wavelength. The plasma light is detected by the high-sensitivity detector 302, and the information is transmitted to the Spectrograph 303, spectrograph 303 can analyze what kind of element exists in the sample through the information obtained, and can perform further qualitative and quantitative analysis of the spectrum, realize the detection of element composition and content in the processing process, and then can carry out the material The identification, classification, qualitative and quantitative analysis can be directly carried out for material analysis without pretreatment of samples. It has the advantages of fast measurement speed, non-contact measurement, and simultaneous analysis of multiple elements. The specific analysis method can be carried out by the existing conventional method, which will not be repeated here.

Continuing to refer to Fig. 1, the CT defect monitoring unit includes an X-ray source 21 and an X-ray detector 22. X-rays emitted from the X-ray source 21 penetrate the workpiece and are received by the X-ray detector 22. The X-ray detector 22 will receive information Transfer to the computer system to obtain the internal defects and geometric contour images of the workpiece, and visually detect the type, location and size of the internal defects of the workpiece. Specifically, according to the different attenuation coefficients of each volume element in each transmission direction, computer information processing and image reconstruction technology are combined to obtain internal defects and geometric contour images of the workpiece, the feedback information is compared with the setting information, and the error is found to be fed back to the laser The processing device is regulated in real time. Due to the large volume of the CT defect monitoring device, it is installed beside the circular monitoring movement platform 200. Specifically, the X-ray source 21 and the X-ray detector 22 are arranged on the working table 12 and located on both sides of the circular movement track 201. After the current layer processing and various monitoring are completed, the workpiece 16 on the substrate is rotated by the 360° rotating worktable 15 so that the CT defect monitoring department can perform an all-round three-dimensional scanning analysis of the workpiece.

The present invention also provides a laser near-net-shaping device with real-time monitoring function, which includes a laser processing device, a control device and the real-time monitoring device, wherein the laser processing device is used for performing laser near-net-shaping, and the real-time monitoring device is used for During the laser near net forming process, various parameters of the workpiece to be formed are monitored in real time, and the monitoring data is fed back to the control device. The control device dynamically adjusts the laser near net forming process parameters based on the monitoring data fed back by the real-time monitoring device. Use the feedback monitoring data to determine whether there are processing defects, defect types and defect locations, and adjust and optimize the laser processing parameters in time based on the defect types and defect locations, and then use the adjusted and optimized laser processing parameters to achieve the control of the laser processing device, even if the laser The processing device performs laser near-net shaping with the adjusted laser processing parameters, thereby controlling the defect error of each processing step within an acceptable range, thereby preparing high-quality defect-free workpieces. How to adjust the laser processing parameters based on the defect type and defect position is a conventional technique in this field and will not be repeated here.

Continuing to refer to Fig. 1, the laser processing device includes a laser processing head 7, an optical fiber coupler 3, a powder feeding device 8, a protective gas supply device 9, a working table 12, a substrate 13, and a control component. Among them, the substrate 13 and the ring-shaped monitoring movement platform 200 It is arranged above the worktable 12, the base plate 13 is rotated by an electric motor, the electric motor is installed in the worktable 12, the laser processing head 7 is connected to the optical fiber coupler 3 through the transmission fiber 6, and the control assembly includes a robot arm control cabinet 2 connected in sequence , The axial robot 4 and the mechanical arm 5, the mechanical arm control cabinet 2 is connected with the computer control system 1, and the mechanical arm 5 is connected with the laser processing head 7. When forming, input the designed workpiece structure information into the computer control system 1, and obtain the processing trajectory of each layer through the slicing software and transmit it to the robotic arm control cabinet 2, thereby controlling the axial robot 4 and the robotic arm 5 in six degrees of freedom in space The movement track in the direction drives the laser processing head 7 mounted on the mechanical arm 5 to move. The optical fiber coupler 3 transmits the optical signal to the laser processing head 7 through the transmission fiber 6 and focuses the light on the predetermined workpiece 16 through the focusing lens. , The substrate 13 is set on the 360° rotating processing table 15. The substrate 13 is preheated before processing to improve stress concentration and other problems. The powder feeding device 8 transfers the metal powder particles to a certain flow rate at a set rate and movement trajectory. The protective gas supply device 9 provides an oxygen-free environment in the processing area to prevent the material from oxidizing during processing. The laser emitted by the laser processing head 7 quickly melts the solid metal powder particles sent by the powder feeding device 8, and the molten pool is rapidly solidified. The layer cladding finally forms the designed workpiece shape. During the forming process, the 360° rotating processing table 15 drives the substrate and the workpiece 16 on it to rotate, and the designed monitoring parts are used to monitor the workpiece in 360° without dead angles.

Specifically, the control device in the present invention is a computer control system 1, which is used to monitor the laser processing device, the laser ultrasonic monitoring unit, the molten pool shape monitoring unit, the molten pool temperature distribution monitoring unit, the workpiece three-dimensional contour monitoring unit, the stress and strain monitoring unit, Laser-induced breakdown spectroscopy monitoring department, CT defect monitoring department, ring monitoring motion platform and 360° rotating processing table are controlled, and the acquired molten pool image information, temperature distribution information, three-dimensional shape information of the workpiece, and the material composition of the processed part are qualitatively controlled. Quantitative information, workpiece near-surface defect analysis and detection information, workpiece internal defect analysis and detection information, workpiece stress analysis and detection information, etc. are processed and analyzed to determine whether there are processing defects, and determine the defect type and defect location, and adjust and optimize the laser processing parameters in time. The quality of the processing parts in progress is improved. If there is a large defect information that cannot be improved, the control device stops all processing parts and gives an alarm to prevent further processing from damaging the machine.

The specific working process of the laser near net shaping equipment is as follows:

1) First, control the laser processing device to complete the single-layer material melting to form the printed cladding layer. This is the detection object. During the printing process, the molten pool shape monitoring unit, the molten pool temperature distribution monitoring unit and the bottom strain measuring mechanism work in real time to Realize real-time monitoring of the dynamic profile of the molten pool, the temperature distribution of the molten pool, and the strain at the bottom of the workpiece;

2) After the single-layer cladding layer is printed, the laser processing device returns to the preset origin, pauses, and waits for the work of other detection departments. In order to avoid the interference of light and vibration between the detection methods, the workpiece three-dimensional contour monitoring department, laser ultrasonic monitoring department, The CT defect monitoring department, the laser-induced breakdown spectrum monitoring department, and the side strain measuring mechanism work at the wrong time in the sequence, of course, they can also work at the same time. During the inspection process, the 360°rotating processing table 15 drives the workpiece to rotate to realize the full range of the workpiece Real-time online monitoring;

3) Data to be monitored by each monitoring department (including workpiece near-surface hole crack defect data, molten pool dynamic topography profile data, molten pool temperature distribution data, workpiece three-dimensional contour topography data, workpiece stress field distribution data, workpiece preparation material elements The composition and content data, the internal defect data of the workpiece, etc.) are fed back to the control device. The control device dynamically adjusts the laser near-net forming process parameters based on the monitoring data fed back by the real-time monitoring device, such as adjusting the laser power, scanning speed, scanning distance, The laser spot radius and powder feeding flow rate, etc., dynamically adjusted process parameters are used as the printing process of the next layer of cladding layer;

4) Repeat steps 1) to 3) to achieve the laser near-net shape of the desired workpiece, that is, after completing the processing and inspection of the current layer, enter the "processing-inspection-feedback optimization-processing" cycle of the next layer to And so on, until the laser near-net shape of the entire workpiece is completed.

Among them, the bottom strain measurement mechanism of the molten pool shape monitoring part, the molten pool temperature distribution monitoring part and the stress and strain monitoring part are measured in real time during the printing process. The lateral strain measurement mechanism of the cross-spectrum monitoring part and the stress-strain monitoring part performs measurement after the cladding layer is printed, so as to realize the time-delayed measurement to avoid interference between monitoring methods and effectively avoid the molten pool to the detection results The impact of this to improve the accuracy of detection.

During specific operation, the computer control system 1 controls the robotic arm control cabinet 2 and the fiber coupler 3, and then controls the movement trajectory of the laser processing head 7. The powder feeding device 8 provides metal powder particles, and the shielding gas supply device 9 provides shielding gas to avoid metal powder. The particles are oxidized in the process of melting, and a single layer of material is melted on the substrate 13 to form a printed cladding layer and use this as the inspection object; the high-speed industrial camera 17 monitors the deformation of the three-dimensional outline of the workpiece 16, which is close to the visible hyperspectral camera 18 The dynamic shape of the molten pool is monitored, and the laser processing head 7 moves synchronously; at the same time, the laser-induced breakdown spectroscopy monitoring unit 300, the side strain measuring mechanism, and the ultra-high-speed photoelectric thermometer 11, which are installed on the ring-shaped monitoring movement platform 200, The detection laser 10 and the excitation laser 19 perform qualitative and quantitative analysis and detection of material elements, stress field distribution detection, molten pool temperature distribution detection and internal defect detection on the workpiece 16 respectively, combined with the strain measurement sensor array 14 installed inside the substrate 13 to process the bottom of the workpiece The strain results are tested and analyzed, the measured strain results are compared with the finite element calculation results, and the stress distribution of the workpiece is inverted. By building a 360° rotating processing table 15 to drive the workpiece to rotate 360°, it is ensured that each monitoring device can scan the side of the workpiece in all directions, and achieve the purpose of all-round real-time online monitoring of the contour of the workpiece.

In order to integrate the normal operation of the seven different monitoring modules without interfering with each other and avoid the interference of light and vibration between the detection methods, in addition to the time-division measurement, the present invention also researches and designs the detection methods and detection wavelengths of each monitoring unit. In order to realize the unified regulation of sub-band stagger. Specifically, for the laser ultrasonic monitoring part, ultrasonic waves with a wavelength of 0.4mm～0.5mm (preferably 0.48mm) are used for detection, and for the molten pool shape monitoring part and the molten pool temperature distribution monitoring part, infrared light with a wavelength of 780nm～950nm is used. For detection, the three-dimensional contour monitoring part and the stress-strain monitoring part of the workpiece use visible light with a wavelength of 446mm ~ 464mm for detection, the laser induced breakdown spectroscopy monitoring part uses a laser with a wavelength of 530nm ~ 540nm (preferably 532nm) for detection, and CT defect monitoring The department uses X-rays with a wavelength of 10 ^-3 nm to 10 nm for detection.

In addition, narrow band-pass filtering is designed for the molten pool shape monitoring part, molten pool temperature distribution monitoring part, workpiece three-dimensional contour monitoring part, and stress and strain monitoring part. Specifically, in the molten pool shape monitoring part (that is, near the visible hyperspectral A filter is set between the camera 18) and the molten pool for decoupling, so as to retain the infrared monitoring light with the same wavelength as the detection light of the visible hyperspectral camera, and eliminate the light influence of the laser heat source. A filter is set between the molten pool temperature distribution monitoring part (i.e., the ultra-high-speed photoelectric thermometer 11) and the molten pool for decoupling, so as to retain the infrared monitoring light with the same wavelength as the ultra-high-speed photoelectric thermometer to eliminate the laser heat source. Light influence. Set a filter between the workpiece three-dimensional contour monitoring part (ie, high-speed industrial camera 17) and the workpiece to be tested for decoupling, so as to retain the visible light with the same wavelength as the detection light of the high-speed industrial camera, eliminate the light influence of the laser heat source, and reduce the single wavelength (460nm) blue light is used as the projection light source of high-speed industrial cameras. For the stress and strain monitoring part, a filter is provided between the industrial camera 103 and the beam splitter 102 for decoupling, so as to retain the visible light with the same wavelength as the detection light of the industrial camera 103 and eliminate the light influence of the laser heat source.

The real-time online non-destructive monitoring of near-net laser forming of the present invention includes near-surface defect detection of the workpiece, qualitative and quantitative detection of the material element composition of the workpiece, the external three-dimensional contour size error and deformation detection of the workpiece, the dynamic shape detection of the processing molten pool, and the processing molten pool Temperature distribution detection, workpiece stress field distribution detection. By installing multiple sets of monitoring devices on the periphery of the processed parts, real-time online monitoring is performed around the processing center, the data obtained from the monitoring is transmitted to the computer in real time for the quality and defect analysis of the processed parts, and the analysis results are fed back to the laser processing device in real time to perform the processing process Adjust, such as laser power, laser scanning speed, laser scanning distance, laser spot radius, single-layer cladding height, metal powder particle output, etc., so as to optimize the processing parameters of each layer and each step. The defect error of a processing step is controlled within an acceptable range. In addition, laser remelting technology can also be used to improve and eliminate processing defects. For serious errors that exceed the predetermined range, a stop signal and an alarm signal can be issued to the laser processing device to avoid material waste and damage caused by continuous processing. Device.

It is easy for those skilled in the art to understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present invention, All should be included in the protection scope of the present invention.

Claims (10)

1. A real-time monitoring device for laser near-net forming, which is characterized by comprising a laser ultrasonic monitoring part, a molten pool shape monitoring part, a molten pool temperature distribution monitoring part, a workpiece three-dimensional contour monitoring part, a stress and strain monitoring part (100), Laser-induced breakdown spectroscopy monitoring unit (300), CT defect monitoring unit, ring monitoring motion platform (200) and 360° rotating processing table (15), of which:

   The laser ultrasonic monitoring part, the molten pool temperature distribution monitoring part, the stress and strain monitoring part and the laser induced breakdown spectrum monitoring part are installed on the annular monitoring movement platform (200) and face the workpiece to be monitored; the molten pool shape The monitoring part and the workpiece three-dimensional contour monitoring part are installed on the side of the laser processing head used to perform laser near-net shaping, and keep synchronized movement with the laser processing head; the CT defect monitoring part is set on the ring monitoring movement platform (200) The side is used to monitor the internal defects of the workpiece; the ring-shaped monitoring motion platform (200) is arranged outside and coaxially with the 360° rotating processing table (15), and the 360° rotating processing table ( 15) It is used to drive the workpiece to be measured to rotate 360° to ensure that each monitoring department can monitor the workpiece in 360°, and then realize the multi-parameter online real-time measurement of the laser near-net shape.
2. The real-time monitoring device for laser near-net shaping according to claim 1, characterized in that the ring-shaped monitoring motion platform (200) includes a ring-shaped motion track (201) and a lifting device (202). When the height of the floor is reached, the lifting device (202) correspondingly raises the circular motion track (201) by one level, so that the monitoring parts on the circular monitoring motion platform (200) always monitor the part of the workpiece to be monitored.
3. The real-time monitoring device for laser near-net shaping according to claim 1, wherein the laser ultrasonic monitoring part includes an excitation laser (19) and a detection laser (10), wherein the excitation laser (19) The pulsed laser beam is used to incident the surface of the workpiece to be inspected to generate an ultrasonic signal, which interacts with the defect in the near surface of the workpiece, is reflected back to the surface of the workpiece, and is received by the detection laser (10).
4. The real-time monitoring device for laser near-net-shaping according to claim 1, wherein the molten pool shape monitoring part is preferably a near visible hyperspectral camera (18); the molten pool temperature distribution monitoring part is preferably It is an ultra-high-speed photoelectric thermometer (11); the three-dimensional contour monitoring part of the workpiece is preferably a high-speed industrial camera (17).
5. The real-time monitoring device for laser near net shaping according to claim 1, wherein the stress-strain monitoring part (100) comprises a bottom strain measuring mechanism and a side strain measuring mechanism, wherein the bottom strain measuring mechanism It includes a strain signal analyzer (101) and a strain measurement sensor array (14) connected to each other, the strain signal analyzer (101) is installed at the bottom of a 360° rotating processing table (15), and the strain measurement sensor array ( 14) It is embedded in the substrate for placing the workpiece to measure the strain at the bottom of the workpiece; the side strain measurement mechanism is an industrial camera (103), which is installed on the ring-shaped monitoring motion platform (200) and is connected to the workpiece A beam splitter (102) is arranged in between; preferably, the strain measurement sensor array (14) has a temperature compensation function.
6. The real-time monitoring device for laser near-net shaping according to claim 1, wherein the laser-induced breakdown spectroscopy monitoring part (300) comprises a detector (302) and a spectrograph (303) connected to each other The detector (302) is used to detect and acquire the plasma light emitted from the surface of the workpiece, and transmit the plasma light to the spectrograph (303), so as to realize the detection of the element composition and content of the material prepared by the workpiece.
7. The real-time monitoring device for laser near-net-shaping according to any one of claims 1-6, wherein the CT defect monitoring unit includes an X-ray source (21) and an X-ray detector (22), and The X-ray source (21) and the X-ray detector (22) are located on both sides of the workpiece. The X-ray source (21) is used to emit X-rays. After the X-ray penetrates the workpiece, the X-ray detector (22) )take over.
8. The real-time monitoring device for laser near-net-shaping according to any one of claims 1-7, wherein the laser ultrasonic monitoring unit uses ultrasonic waves with a wavelength of 0.4 mm to 0.5 mm for detection, and molten pool shape monitoring The temperature distribution monitoring part and the molten pool adopt infrared light with a wavelength of 780nm～950nm for detection, the workpiece three-dimensional profile monitoring part and the stress-strain monitoring part adopt visible light with a wavelength of 446mm～464mm for detection, and the laser-induced breakdown spectroscopy monitoring part adopts a wavelength. The detection is carried out with a laser of 530nm～540nm, and the CT defect monitoring department uses ^{X-rays with a wavelength of 10 -3} nm～10nm for detection; preferably, the molten pool shape monitoring unit, molten pool temperature distribution monitoring unit, and workpiece three-dimensional contour monitoring unit And the stress and strain monitoring department for narrow band pass filter design.
9. A laser near-net forming equipment with real-time monitoring function, characterized in that the forming equipment includes a laser processing device, a control device, and the real-time monitoring device according to any one of claims 1-8, wherein the laser processing The device is used to perform laser near-net shaping, the real-time monitoring device is used to monitor the workpiece in real time during the laser near-net shaping process, and feedback the monitored data to the control device, which is based on the monitoring feedback from the real-time monitoring device The data dynamically adjusts the laser near-net-shaping process parameters, and controls the action of the laser processing device based on the dynamically adjusted parameters, so as to realize the preparation of high-quality laser near-net-shaping workpieces.
10. A laser near-net shaping method with real-time monitoring function is characterized in that it comprises the following steps:

    1) The laser processing device is used to print the single-layer cladding layer of the workpiece to be formed. During the printing process, the bottom strain measuring mechanism of the molten pool shape monitoring unit, the molten pool temperature distribution monitoring unit, and the stress and strain monitoring unit work in real time to achieve Real-time monitoring of the dynamic profile of the molten pool, the temperature distribution of the molten pool and the strain at the bottom of the workpiece;

    2) After the single-layer cladding layer is printed, the laser processing device returns to the preset origin and pauses, the workpiece three-dimensional contour monitoring department, laser ultrasonic monitoring department, CT defect monitoring department, laser induced breakdown spectroscopy monitoring department, and stress-strain monitoring department The side strain measuring mechanism of the slab starts to work synchronously or time-sharing to realize the real-time monitoring of the three-dimensional contour of the workpiece, the near surface defect of the workpiece, the internal defect of the workpiece, the element composition and content of the workpiece preparation material, and the side strain of the workpiece. 360°rotating during the inspection process The processing table drives the workpiece to rotate 360° to ensure that each monitoring department scans the workpiece in all directions, realizing the purpose of all-round real-time online monitoring;

    3) Each monitoring department feeds back the monitored data to the control device, which dynamically adjusts the process parameters of the laser near-net forming based on the monitoring data fed back by the real-time monitoring device, and the dynamically adjusted process parameters are used as the next layer of cladding layer Printing process;

    4) Repeat steps 1) to 3) to achieve the laser near-net shape of the desired workpiece.

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