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CN-116652208-B - Real-time regulation and control laser additive manufacturing alloy method based on online ultrasonic monitoring

CN116652208BCN 116652208 BCN116652208 BCN 116652208BCN-116652208-B

Abstract

The invention discloses a method for manufacturing alloy by regulating and controlling laser additive in real time based on online ultrasonic monitoring, which adopts an ultrasonic sensor to track the back wall reflection of a laser forming sample in real time in the laser additive manufacturing process, by processing ultrasonic signal data, the generation of cracks and pores in the laser forming process can be accurately reflected, and laser forming process parameters are adjusted in real time according to feedback data, so that the laser additive manufacturing alloy sample without the cracks and the pores is finally obtained. The method for monitoring and regulating the alloy forming quality in real time in the laser additive manufacturing process is provided, and the laser forming quality of the formed alloy is remarkably improved.

Inventors

  • XI LIXIA
  • GU DONGDONG
  • HOU JIAXING
  • TANG KAI
  • SHI KEYU

Assignees

  • 南京航空航天大学

Dates

Publication Date
20260505
Application Date
20230601

Claims (7)

  1. 1. A method for manufacturing alloy by regulating and controlling laser additive in real time based on online ultrasonic monitoring is characterized in that a laser additive manufacturing system is used for monitoring the forming quality of an alloy sample in the laser forming process in real time; The laser additive manufacturing system comprises laser powder bed fusion forming equipment and an ultrasonic monitoring system, wherein the ultrasonic monitoring system comprises an ultrasonic sensor (1), a sensor bracket (4), a pulse transmitting receiver (2) and a data collecting and processing device (3), the laser powder bed fusion forming equipment comprises a forming substrate (7) and a computer control system, an alloy sample (8) planned to be formed is placed above the forming substrate (7), the ultrasonic sensor (1) is installed below the forming substrate (7) through the sensor bracket (4), a plurality of sensor fixing cavities are formed in the sensor bracket (4), and the ultrasonic sensor (1) can be correspondingly placed below the alloy sample (8); The pulse transmitting and receiving device (2) is respectively connected with the ultrasonic sensor (1) and the data collecting and processing device (3) and is used for controlling the ultrasonic sensor (1) to transmit sound signals to the alloy sample (8), collecting reflected sound signals higher than the amplitude threshold value and transmitting the reflected sound signals higher than the amplitude threshold value to the data collecting and processing device (3); The data collecting and processing device (3) is connected with the computer control system and is used for processing the reflected sound signals higher than the amplitude threshold, and if the metallurgical defects are detected, the computer control system is regulated and controlled in real time to regulate and control the laser forming process parameters so as to eliminate the metallurgical defects in the subsequent forming process; the method comprises the following steps: Step 1, establishing a three-dimensional entity geometric model of a target part by using computer software aided design, carrying out layering slicing treatment on the three-dimensional model by using MATERIALISE MAGICS software, planning a laser scanning path, and dispersing the three-dimensional entity into two-dimensional data; step 2, the two-dimensional data are led into a computer control system of laser powder bed fusion forming equipment, alloy powder is melted and solidified layer by layer, the forming quality of an alloy sample is monitored in real time through an ultrasonic monitoring system in the laser forming process, and according to reflected sound signal data, if the formation of metallurgical defects including cracks and pores is detected, laser forming process parameters are adjusted in real time to eliminate the metallurgical defects, and finally a compact three-dimensional alloy solid part without crack pores is prepared; step 2.1, obtaining acoustic signal characteristics in the reflected acoustic signal above an amplitude threshold, wherein the acoustic signal characteristics comprise rise time, peak amplitude, duration, kurtosis, counted number, energy and frequency; step 2.2, carrying out cluster analysis on the acoustic signal characteristics by adopting a k-means clustering algorithm to obtain a plurality of cluster clusters; Step 2.3, performing principal component analysis on a plurality of clustering clusters to obtain defect types of acoustic emission sources corresponding to each clustering cluster, wherein the defect types comprise cracks and pores; And 2.4, if the formation of metallurgical defects including cracks and pores is detected, adjusting the laser forming process parameters in real time to eliminate the metallurgical defects.
  2. 2. The method of on-line ultrasonic monitoring based on-line regulated laser additive manufacturing of alloys according to claim 1, characterized in that in step 2.1 the peak amplitude in the acoustic signal characteristics is obtained by real-time measurement by data collection and processing means (3), rise time, duration, kurtosis, number of counts, energy and frequency are calculated from reflected acoustic signals above an amplitude threshold.
  3. 3. The method for manufacturing the alloy by the real-time regulation laser additive based on the online ultrasonic monitoring, which is characterized by comprising the following steps of initializing each cluster center Ci, wherein 1≤i≤k, k represents the number of clusters, k≤2, calculating Euclidean distance between vectors composed of acoustic signal characteristics and the cluster centers Ci, then distributing each input vector to the nearest cluster, recalculating the position of the cluster center according to the nearest mean value, repeating the steps until the position of the cluster center does not change, calculating the maximum average contour width at the moment, and repeating the steps for all clusters, wherein the average contour width is the maximum when the final k is 2, so that the optimal cluster number is 2, acoustic events in the same cluster are similar to each other, and acoustic events in different clusters are different.
  4. 4. The method for manufacturing the alloy by the real-time regulation and control laser additive based on the online ultrasonic monitoring according to claim 3, wherein the step 2.3 comprises the steps of adopting principal component analysis to perform dimension reduction, wherein 7 features in acoustic emission events are components of n input mode vectors Zj, j=1, 2, and n, obtaining an n×7 feature matrix Z, wherein n is the number of acoustic emission events; Different defect types can be identified after the cluster obtained after the cluster analysis is subjected to principal component analysis, the defect types of the acoustic emission source comprise pores and cracks, acoustic emission signals generated by the pores are short in decay time and small in amplitude, acoustic emission signals generated by the cracks are short in duration and large in amplitude, and acoustic emission event energy generated by the pores is higher than acoustic emission event energy generated by the cracks.
  5. 5. The method for manufacturing alloy by real-time controlled laser additive based on-line ultrasonic monitoring according to claim 4, wherein if the crack is detected in step 2.4, the laser forming process parameters are adjusted in real time to eliminate metallurgical defects, including reducing the laser scanning speed to eliminate the crack.
  6. 6. The method for manufacturing alloy by real-time controlled laser additive based on-line ultrasonic monitoring according to claim 4, wherein if voids are detected in step 2.4, the laser forming process parameters are adjusted in real time to eliminate metallurgical defects, including increasing laser power and decreasing laser scanning speed to eliminate voids.
  7. 7. The method for manufacturing alloy by real-time regulation and control laser additive based on-line ultrasonic monitoring according to claim 6 is characterized in that the transmitting and receiving bandwidths of the ultrasonic sensor (1) are 100-1000 kHz.

Description

Real-time regulation and control laser additive manufacturing alloy method based on online ultrasonic monitoring Technical Field The invention belongs to the field of laser additive manufacturing equipment and process innovation, and relates to a method for manufacturing alloy by regulating and controlling laser additive in real time based on online ultrasonic monitoring. Background The laser additive manufacturing is to take metal powder or wire as a raw material, melt the raw material by high-power laser, solidify layer by layer to form and finally stack into uniform and compact three-dimensional solid parts, has the advantages of high forming speed, no structural limitation, high material utilization and the like, and is widely applied to the fields of aerospace, national defense, military, medical health and the like. As most of the light beams used in the laser additive manufacturing are Gaussian light beams, the laser additive manufacturing has the characteristics of small spot diameter and high energy, but has the characteristics of high focal point moving speed, uneven energy distribution and the like, the problems of overhigh local temperature, large temperature gradient of a molten pool and the like can be caused in the forming process, the heat stress concentration and uneven liquid-phase spreading are easy to form, the formation of metallurgical defects such as heat cracks and pores in the solidification process is caused, and the quality and the performance of formed parts are finally influenced. Disclosure of Invention Aiming at the defects of the existing alloy laser forming technology, the invention provides the method for manufacturing the alloy by regulating and controlling the laser additive in real time based on online ultrasonic monitoring, so as to eliminate hot cracks and pores, form compact alloy samples without crack pores and improve the forming quality and performance of the alloy manufactured by the laser additive. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: and (3) using a laser additive manufacturing system to monitor the forming quality of an alloy sample in the laser forming process in real time, and if metallurgical defects including cracks and pores are detected, adjusting laser forming process parameters in real time to eliminate the metallurgical defects, so as to finally prepare the compact three-dimensional alloy solid part without the metallurgical defects. Further, the laser additive manufacturing system comprises a laser powder bed fusion forming device and an ultrasonic monitoring system, wherein the ultrasonic monitoring system comprises an ultrasonic sensor, a pulse emitting receiver and a data collecting and processing device, the laser powder bed fusion forming device comprises a forming substrate and a computer control system, the ultrasonic sensor is arranged below the forming substrate, and an alloy sample planned to be formed is placed above the forming substrate; The pulse transmitting and receiving device is respectively connected with the ultrasonic sensor and the data collecting and processing device and is used for controlling the ultrasonic sensor to transmit sound signals to the alloy sample, collecting reflected sound signals higher than the amplitude threshold value and transmitting the reflected sound signals higher than the amplitude threshold value to the data collecting and processing device; The data collection and processing device is connected with the computer control system and is used for processing the reflected sound signals higher than the amplitude threshold, and if the metallurgical defects are detected, the computer control system is regulated and controlled in real time to regulate and control the laser forming process parameters so as to eliminate the metallurgical defects in the subsequent forming process. Further, the method specifically comprises the following steps: Step 1, establishing a three-dimensional entity geometric model of a target part by using computer software aided design, carrying out layering slicing treatment on the three-dimensional model by using MATERIALISE MAGICS software, planning a laser scanning path, and dispersing the three-dimensional entity into two-dimensional data; And 2, introducing the two-dimensional data into a computer control system of laser powder bed fusion forming equipment, melting and solidifying alloy powder layer by layer, monitoring the forming quality of an alloy sample in real time through an ultrasonic monitoring system in the laser forming process, and adjusting laser forming process parameters in real time to eliminate metallurgical defects if the formation of metallurgical defects including cracks and pores is detected according to reflected sound signal data, so as to finally prepare the compact and crack-free three-dimensional alloy solid part. Further, step 2 includes: step 2.1, obtaining acoustic signal characteristics i