- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Deriving spectral information upon the laser welding process employing a hyperspectral imaging technique
摘要： In this paper we present results from process observations of deep penetration laser welding using a hyperspectral imaging (HSI) technique. For monitoring different types of laser-based material processing, we developed an appropriate high-speed camera-based HSI system. This system enables us to derive spectra of the deep penetration welding process with high time resolution. These spectra can be used for temperature determination or to extract spectral characteristics, both of which can help to further investigate process dynamics and properties of the vapor. The presented results contain particularly HSI-derived spectral information of the evolving vapor plume that is related to corresponding high-speed images and spectra acquired with a conventional VIS-spectrometer.
关键词： laser-based material processing,deep penetration laser welding,process monitoring,hyperspectral imaging
更新于2025-09-12 10:27:22
-
Optical in-process height measurement system for process control of laser metal-wire deposition
摘要： We propose an in-process height measurement system for a weld bead and feedback control system for wire-feeding speed for high-quality laser deposition. Metal additive manufacturing, especially laser metal-wire deposition, is effective for complex shape fabrication and repair processing. However, we must control the gap between a weld bead and a feed wire in an optimal range for high-quality deposition. Conventionally, the Z-stage pitch for multi-layer deposition must be precisely adjusted by each deposition shape. In this paper, we design an in-process height measurement system that is integrated in a laser processing head, which measures the weld bead height by a line section method. We decreased the influence of the intense thermal radiation generated from a melt pool by inserting the band-pass filter of the line beam’s wavelength in the imaging system and optimizing its line laser power. Consequently, our system can measure the weld bead height near the melt pool, which is 4 mm in front of it. Next we show that our proposed system can measure the weld bead height during wire-laser metal deposition with 50-μm accuracy by comparing its value to the true value. Finally, we achieved a cylinder shape deposition of 50-mm height, regardless of the Z-stage pitch and the cylinder diameter of the multi-layer deposition, by controlling the wire-feeding speed based on the measured weld bead height.
关键词： Laser Metal Deposition,Light Section Method,Optical Sensing,Height Measurement,Process Monitoring,Additive Manufacturing
更新于2025-09-12 10:27:22
-
Vision based beam offset detection in laser stake welding of T-joints using a neural network
摘要： This paper presents an experimental study where a vision camera integrates coaxially into a laser beam welding tool to monitor beam deviations (beam offset) in laser stake welding of T-joints. The aim is to obtain an early detection of deviations from the joint centreline in this type of welding where the joint is not visible from the top side. A polynomial surface fitting method is applied to extract features that can describe the behaviour of the melt pool. A nonlinear autoregressive with exogenous inputs neural network model is trained to relate eight image features to the laser beam offset. The performance of the presented model is evaluated off-line by different welding samples. The results show that the proposed method can be used to guide post weld inspection and has the potential for on-line adaptive control.
关键词： T-joint,process monitoring,laser beam welding,neural network,vision camera
更新于2025-09-12 10:27:22
-
Beam offset detection in laser stake welding of tee joints based on photodetector sensing
摘要： This paper presents an experimental study where a photodetector is used in a laser beam welding tool to monitor beam deviations (beam offsets) in stake welding of tee joints. The aim is to obtain an early detection of deviations from the joint centerline in this type of welding where the joint is not visible from the top side. The photodetector used is a GaP diode sensitive in the spectral range 150-550 nm corresponding to the spectral emissions form the plasma plume during keyhole welding. The photodetector signal has been evaluated by change point detection methods with respect to their detection performance. Both an off-line and an on-line method have been evaluated. The off-line method can be used to guide post weld inspection and the on-line method has the potential to enable on-line adaptive position control and/or the possibility to stop the process for repair. The results shows that the proposed method can be used as a go/no go system and to guide post weld inspection.
关键词： process monitoring,tee joint,photodetector,laser beam welding
更新于2025-09-12 10:27:22
-
Low power sensor node with photovoltaic power supply for radio-based process monitoring
摘要： This paper presents the idea of improving existing process monitoring systems for drilling, milling or threading by employing a novel communication technology as well as energy harvesting methods. An overview of the system including sensor node, energy supply and communication technology is given. The radio transmission methods are investigated in terms of power consumption in order to define requirements for the power supply. Fundamental measurements to characterize the behavior of different types of solar cells under artificial light are performed. Based on the results, two designs of sensor node prototypes are presented. The optical power supply and the energy harvesting system for the demonstrators are shown in detail.
关键词： optical power supply,process monitoring,24 GHz RFID,wireless sensor node,energy harvesting,RF communication
更新于2025-09-12 10:27:22
-
Advances in thermal laser separation: process monitoring in a kerf-free laser-based cutting technology to ensure high yield
摘要： Thermal Laser Separation (TLS) is an ablation free and therefore kerf free laser based cutting technology. This novel dicing technology is utilized to separate microelectronic devices on semiconductor wafers. In order to broaden the use of TLS method towards smaller chips and new materials on the one side and towards an advanced process monitoring on the other side, a novel contact-free measuring method for monitoring the TLS process has been developed. This new method is based on heating the semiconductor wafer with a near-infrared (NIR) laser and analyzing the subsequent temperature gradients induced by heat diffusion with contact-less temperature measurement. Thus, the TLS-crack can be detected due to its isolating effect to heat flux. The feasibility of the method is presented and the influence of parameters like sample size, distance to the TLS-crack and the laser setup in the measurements is reported.
关键词： kerf-free laser-cutting technology,cut detection,Laser dicing,Thermal Laser Separation,process monitoring
更新于2025-09-11 14:15:04
-
A cybermanufacturing and AI framework for laser powder bed fusion (LPBF) additive manufacturing process
摘要： In Laser Powder Bed Fusion (LPBF) along, more than 50 process parameters are known to affect print quality. The current state-of-the-art practice in process control only considers a small fraction of them – mainly on laser power and scanning speed affecting temperature gradient and geometry of a melting pool. This letter proposes a system-wide platform involving various machine learning principles and leveraging production data stored in the cloud. The proposed framework aims to identify process parameters that may affect print quality so that a viable process control strategy can be formulated.
关键词： Laser powder bed fusion,Metal 3D printing,Machine learning,Process monitoring
更新于2025-09-11 14:15:04
-
Pilot capability evaluation of a feedback electronic imaging system prototype for in-process monitoring in electron beam additive manufacturing
摘要： Electron beam additive manufacturing (EBAM) is an additive manufacturing (AM) technique increasingly used by many industrial sectors, including medical and aerospace industries. The application of this technology is still, however, challenged by many technical barriers. One of the major issues is the lack of process monitoring and control system to monitor process repeatability and component quality reproducibility. Various techniques, mainly involving infrared (IR) and optical cameras, have been employed in previous attempts to study the quality of the EBAM process. However, all attempts lack the flexibility to zoom-in and focus on multiple regions of the processing area. In this paper, a digital electronic imaging system prototype and a piece of macroscopic process quality analysis software are presented. The prototype aims to provide flexibility in magnifications and the selection of fields of view (FOV). The software aims to monitor the EBAM process on a layer-by-layer basis. Digital electronic images were generated by detecting both secondary electrons (SE) and backscattered electrons (BSE) originating from interactions between the machine electron beam and the processing area using specially designed hardware. Prototype capability experiments, software verification and demonstration were conducted at room temperature on the top layer of an EBAM test build. Digital images of different magnifications and FOVs were generated. The upper range of the magnification achieved in the experiments was 95 and the demonstration verified the potential ability of the software to be applied in process monitoring. It is believed that the prototype and software have significant potential to be used for in-process EBAM monitoring in many manufacturing sectors. This study is thought to be the necessary precursor for future work which will establish whether the concept is suited to working under in-process EBAM operating conditions.
关键词： In-process monitoring,Electron beam melting,Electronic imaging,Metallic materials,Additive manufacturing,Quality control,Backscattered electrons,Secondary electrons
更新于2025-09-10 09:29:36