Scanning system development and digital beam control method for electron beam selective melting

2015 ◽  
Vol 21 (3) ◽  
pp. 313-321 ◽  
Author(s):  
Chao Guo ◽  
Jing Zhang ◽  
Jun Zhang ◽  
Wenjun Ge ◽  
Bo Yao ◽  
...  
Keyword(s):  
Electron Beam ◽  
Large Deflection ◽  
Control Method ◽  
Three Dimensional ◽  
Beam Deflection ◽  
Scanning System ◽  
Content Type ◽  
Metal Parts ◽  
Digital Scanning ◽  
Electron Beam Selective Melting

Purpose – The purpose of this paper is to correct the beam deflection errors and beam defocus by using a digital scanning system. Electron beam selective melting (EBSM) is an additive manufacturing technology for metal parts. Beam deflection errors and beam defocus at large deflection angles would greatly influence the accuracy of the built parts. Design/methodology/approach – The 200 × 200 mm2 scanning area of the electron beam is discretized into 1001 × 1001 points arranged in array, based on which a digital scanning system is developed. To correct the deflection errors, the electron beam scans a 41 × 41 testing grid, and the corrective algorithm is based on the bilinear transformation from the grid points’ nominal coordinates to their measured coordinates. The beam defocus is corrected by a dynamic focusing method. A three-dimensional testing part is built with and without using the corrective algorithm, and their accuracies are quantitatively compared. Findings – The testing grid scanning result shows that the accuracy of the corrected beam deflection system is better than ± 0.2 mm and beam defocus at large deflection angles is eliminated visibly. The testing part built with using the corrective algorithm is of greater accuracy than the one built without using it. Originality/value – Benefiting from the digital beam control method, the model-to-part accuracy of the system is effectively improved. The digital scanning system is feasible in rapid manufacturing large and complex three-dimensional metal parts.

Development of low cost three-dimensional body scanner using depth perception camera

2017 ◽  
Vol 29 (6) ◽  
pp. 857-867 ◽  
Author(s):  
Miyeon Lee ◽  
Dong Il Yoo ◽  
Sungmin Kim
Keyword(s):  
Depth Perception ◽  
Computer Network ◽  
Low Cost ◽  
Three Dimensional ◽  
Easy Access ◽  
Scanning System ◽  
Content Type ◽  
3D Data ◽  
Model Alignment ◽  
Body Scanner

Purpose The purpose of this paper is to develop a relatively inexpensive and easily movable three-dimensional (3D) body scanner. Design/methodology/approach Multiple depth perception cameras and a turntable were used to form the hardware and a client-server computer network was used to control the hardware. Findings A portable and inexpensive yet quite accurate body scanner system has been developed. Research limitations/implications The turntable mechanism and semi-automatic model alignment caused some error. Practical implications This scanner is expected to facilitate the acquisition of 3D human body or garment data easily for various research projects. Social implications Many researchers might have an easy access to 3D data of large object such as body or whole garment. Originality/value Inexpensive yet expandable scanning system has been developed using readily available components.

Processing windows for Ti-6Al-4V fabricated by selective electron beam melting with improved beam focus and different scan line spacings

2019 ◽  
Vol 25 (4) ◽  
pp. 665-671 ◽  
Author(s):  
Christoph R. Pobel ◽  
Fuad Osmanlic ◽  
Matthias A. Lodes ◽  
Sebastian Wachter ◽  
Carolin Körner
Keyword(s):  
Electron Beam ◽  
Electron Beam Melting ◽  
High Energy ◽  
Beam Deflection ◽  
Content Type ◽  
Powder Bed ◽  
Manufacturing Method ◽  
High Speeds ◽  
Selective Electron Beam Melting ◽  
Scan Line

Purpose Selective electron beam melting (SEBM) is a highly versatile powder bed fusion additive manufacturing method. SEBM is characterized by high energy densities which can be applied with nearly inertia free beam deflection at high speeds (<8.000 m/s). This paper aims to determine processing maps for Ti-6Al-4V on an Arcam Q10 machine with LaB6 cathode design. Design/methodology/approach Scan line spacings of 100, 50 and 20 µm in a broad parameter range, focusing on high deflection and build speeds are investigated. Findings There are broad processing windows for dense parts without surface flaws for all scan line spacings which are defined by the total energy input and the area melting velocity. Originality/value The differences and limitations are discussed taking into account the beam properties at high beam energy and velocity as well as evaporation related loss of alloying components.

Evaluation of body geometry and symmetry for adolescent idiopathic scoliosis with 3D body scanning system

2017 ◽  
Vol 21 (4) ◽  
pp. 276-292
Author(s):  
Lu Lu ◽  
Kit-Lun Yick ◽  
Sun Pui Ng ◽  
Joanne Yip ◽  
Chi Yung Tse
Keyword(s):  
Adolescent Idiopathic Scoliosis ◽  
Idiopathic Scoliosis ◽  
Three Dimensional ◽  
The Body ◽  
Scanning System ◽  
X Rays ◽  
Cross Sectional ◽  
Content Type ◽  
Body Scanning ◽  
The Cross

Purpose The purpose of this paper is to quantitatively assess the three-dimensional (3D) geometry and symmetry of the torso for spinal deformity and the use of orthotic bracewear by using non-invasive 3D body scanning technology. Design/methodology/approach In pursuing greater accuracy of body anthropometric measurements to improve the fit and design of apparel, 3D body scanning technology and image analysis provide many more advantages over the traditional manual methods that use contact measurements. To measure the changes in the torso geometry and profile symmetry of patients with adolescent idiopathic scoliosis, five individuals are recruited to undergo body scanning both with and without wearing a rigid brace during a period of six months. The cross-sectional areas and profiles of the reconstructed 3D torso models are examined to evaluate the level of body symmetry. Findings Significant changes in the cross-sectional profile are found amongst four of the patients over the different visits for measurements (p < 0.05), which are consistent with the X-rays results. The 3D body scanning system can reliably evaluate changes in the body geometry of patients with scoliosis. Nevertheless, improvements in the symmetry of the torso are found to be somewhat inconsistent among the patients and across different visits. Originality/value This pilot study demonstrates a practical and safe means to measure and analyse the torso geometry and symmetry so as to allow for more frequent evaluations, which would result in effective and optimal treatment of spinal deformation.

Benchmarking the complex geometric profiles, dimensional accuracy and surface analysis of printed parts

2019 ◽  
Vol 26 (2) ◽  
pp. 319-329 ◽  
Author(s):  
Paridhi Subbaian Kaliamoorthy ◽  
Rajkumar Subbiah ◽  
Joseph Bensingh ◽  
Abdul Kader ◽  
Sanjay Nayak
Keyword(s):  
Surface Roughness ◽  
Three Dimensional ◽  
Dimensional Accuracy ◽  
Measuring System ◽  
Experimental Result ◽  
Complex Geometries ◽  
Thin Wall ◽  
Content Type ◽  
Metal Parts ◽  
Cooling Channels

Purpose Additive manufacturing has paved a way for geometrical freedom and mass customization of new and innovative products. However, it has a few limitations in printing complex geometries and sizes. The purpose of this paper is three-dimensional printing of metal parts using selective laser melting (SLM) has several intricacies. Design/methodology/approach To test the capabilities of SLM, the complex geometries of varying sizes, orientations, shapes such as square and cylindrical features, thin wall structures and holes were checked for dimensional accuracy and surface roughness. Findings The outcome of the study represents the capabilities of SLM and provide insight for solving the technological issues and processing constraint in the manufacture of metal parts from aluminum alloy. The analysis has proven that there is significant accuracy in dimension for large features in comparison with smaller one. The dimensional reproducibility was determined with the aid of an optical measuring system and the range of errors were calculated. These results show that the dimensional accuracy of the features in the printed part was within acceptable tolerance limits. This paper also investigated the significant contributing factors influencing printing of two and three-dimensional surface roughness based on the result of surface profilometer and it was observed that the surface was smoothened with the presence of overhangs and supports. Originality/value The ability of SLM to fabricate conformer cooling channels to support mould fabrication was tested. From the experimental result, it was observed that the quality of printing of conformal cooling channels depended on the diameter of channels with larger distortions in the channel having smaller diameter. The innovative aspect of the work was the study of build orientation combined with the investigated material.

Parametric study and surface morphology analysis of electron beam selective melting

2018 ◽  
Vol 24 (9) ◽  
pp. 1586-1598 ◽  
Author(s):  
Ya Qian ◽  
Wentao Yan ◽  
Feng Lin
Keyword(s):  
Electron Beam ◽  
Energy Density ◽  
Flow Instability ◽  
Processing Parameters ◽  
Velocity Change ◽  
Content Type ◽  
Melting Pool ◽  
Scan Speed ◽  
Surface Morphologies ◽  
Electron Beam Selective Melting

Purpose This paper aims to study the effect of processing parameters and the fundamental mechanism of surface morphologies during electron beam selective melting. Design/methodology/approach From the powder-scale level, first, the discrete element method is used to obtain the powder bed distribution that is comparable with the practical condition; then, the finite volume method is used to simulate the particle melting and flowing process. A physically reliable energy distribution of the electron beam is applied and the volume of fluid method is coupled to capture the free boundary flow. Twelve sets of parameters grouped into three categories are examined, focusing on the effect of scan speed, input powder and energy density. Findings According to the results, both melting pool width and depth have a positive relation with the energy density, whereas the melting pool length is insensitive to the scan velocity change. The balling effect is attributed to either an insufficient energy input or the flow instability; the hump effect originates from the mismatch between electron beam moving and the fluid flow. The scan speed is a key parameter closely related to melting pool size and surface morphologies. Originality/value Through a number of case studies, this paper gives a comprehensive insight of the parameter effects and mechanisms of different surface morphologies, which helps to better control the manufacturing quality of electron beam selective melting.

Three-Dimensional Electron-Beam Deflection and Missed Joint in Welding Dissimilar Metals

1997 ◽  
Vol 119 (4) ◽  
pp. 832-839 ◽  
Author(s):  
P. S. Wei ◽  
F. K. Chung
Keyword(s):  
Electron Beam ◽  
Electrical Contact ◽  
Three Dimensional ◽  
Electron Gun ◽  
Beam Deflection ◽  
Beam Power ◽  
Dissimilar Metals ◽  
Electrical Contact Resistance ◽  
Paraboloid Of Revolution

Three-dimensional deflection of the electron beam resulting in a missed joint due to thermoelectric magnetism generated while welding dissimilar metals is systematically investigated. The incident energy rate distribution is assumed to be Gaussian and the deep and narrow welding cavity induced is idealized as a paraboloid of revolution. With a three-dimensional analytical solution for the temperature and by solving Maxwell’s electromagnetic equations, thermoelectric currents, magnetic flux densities, and deflections of the beam are found. The predictions agree with available experimental data. The results find that missed joints can be reduced by increasing the dimensionless accelerating voltage-to-Seebeck e.m.f. parameter, Peclet number, and effective electrical contact resistance parameter, and decreasing dimensionless beam power, magnetic permeabilities, and electrical conductivity ratio between metals 1 and 2. Tilting workpieces and shifting the electron gun from the joint line are also feasible. A three-dimensional analysis is required for a successful determination of beam deflection.

Stabilization and circuit implementation of a novel chemical oscillating chaotic system

Circuit World ◽  
2019 ◽  
Vol 45 (2) ◽  
pp. 93-106
Author(s):  
Li Xiong ◽  
Wanjun Yin ◽  
Xinguo Zhang
Keyword(s):  
Chaotic System ◽  
Control Method ◽  
Three Dimensional ◽  
Chaotic Attractors ◽  
The Novel ◽  
Content Type ◽  
Initial Values ◽  
Parameters Selection ◽  
Chaotic Circuits ◽  
Simulation Results

Purpose This paper is aimed at investigating a novel chemical oscillating chaotic system with different attractors at fixed parameters. The typical dynamical behavior of the new chemical oscillating system is discussed, and it is found that the state selection is dependent on initial values. Then, the stabilization problem of the chemical oscillating attractors is investigated analytically and numerically. Subsequently, the novel electronic circuit of the proposed chemical oscillating chaotic system are constructed, and the influences of the changes of circuit parameters on chemical oscillating chaotic attractors are investigated. Design/methodology/approach The different attractors of the novel chemical oscillating chaotic system are investigated by changing the initial values under fixed parameters. Moreover, the active control and adaptive control methods are presented to make the chemical oscillating chaotic systems asymptotically stable at the origin based on the Lyapunov stability theory. The influences on chemical oscillating chaotic attractors are also verified by changing the circuit parameters. Findings It is found that the active control method is easier to be realized by using physical components because of its less control signal and lower cost. It is also confirmed that the adaptive control method enjoys strong anti-interference ability because of its large number of selected controllers. What can be seen from the simulation results is that the chaotic circuits are extremely dependent on circuit parameters selection. Comparisons between MATLAB simulations and Multisim simulation results show that they are consistent with each other and demonstrate that changing attractors of the chemical oscillating chaotic system exist. It is conformed that circuit parameters selection can be effective to control and realize chaotic circuits. Originality/value The different attractors of the novel chemical oscillating chaotic system are investigated by changing the initial values under fixed parameters. The characteristic of the chemical oscillating attractor is that the basin of attraction of the three-dimensional attractor is located in the first quadrant of the eight quadrants of the three-dimensional space, and the ranges of the three variables are positive. This is because the concentrations of the three chemical substances are all positive.

A new variable stiffness actuator and its control method

2019 ◽  
Vol 46 (4) ◽  
pp. 553-560 ◽  
Author(s):  
Lei Zhang ◽  
Wendong Wang ◽  
Yikai Shi ◽  
Yang Chu ◽  
Xing Ming
Keyword(s):  
Control Method ◽  
Three Dimensional ◽  
Variable Stiffness ◽  
Magnetorheological Fluid ◽  
Human Robot Interaction ◽  
Crash Test ◽  
Three Dimensional Model ◽  
Content Type ◽  
Variable Stiffness Actuator

Purpose To achieve variable stiffness, this paper aims to design a flexible actuator with variable stiffness by using the magnetorheological effect of magnetorheological fluid. The variable stiffness actuator can well meet the safety requirements of human–robot interaction and be more adaptable to unknown or complex environments. The variable stiffness actuator designed in this study can realize the continuous and controllable change of stiffness compared with the existing actuator. Design/methodology/approach The principle of variable stiffness actuator is illustrated in detail; the three-dimensional model and mechanical model of the flexible actuator are provided. The magnetic field distribution of the actuator coil is analyzed, and the dynamic model of the actuator is provided. Findings Output torque test suggests that the magnetorheological fluid variable stiffness actuator (VSAMF) can output a stable torque which meets the designing requirements of the test; sinusoidal follow-up test shows that VSAMF can implement sinusoidal follow-up; variable stiffness test shows that VSAMF can achieve real-time variable stiffness adjustment; the crash test suggests that VSAMF can well protect machines when meeting obstacles. Originality/value In this paper, a new variable stiffness joint is proposed through changing the current to change the performance of the stiffness, and it can realize the continuous and controllable change of stiffness.

Four-point dynamic leveling method for drilling platform application

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Dongmin Li ◽  
Guofang Ma ◽  
Jia Li
Keyword(s):  
Coal Mine ◽  
Control Method ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Underground Coal Mine ◽  
Content Type ◽  
Displacement Sensors ◽  
Leveling Control ◽  
Combined Sensor ◽  
Support Rod

Purpose It is essential to level the drilling platform across which a drilling robot travels in a slant underground coal mine tunnel to ensure smooth operation of the drill rod. However, existing leveling methods do not provide dynamic performance under the drilling conditions of the underground coal mine. A four-point dynamic leveling algorithm is presented in this paper based on the platform attitude and support rod displacement (DLAAD). An experimental drilling robot demonstrates its dynamic leveling capability and ability to ensure smooth drill rod operations. Design/methodology/approach The attitude coordinate of the drilling robot is established according to its structure. A six-axis combined sensor is adopted to detect the platform attitude, thus revealing the three-axis Euler angles. The support rod displacement values are continuously detected by laser displacement sensors to obtain the displacement increment of each support rod as needed. The drilling robot is leveled according to the current support rod displacement and three-dimensional (3 D) attitude detected by the six-axis combined sensor dynamically. Findings Experimental results indicate that the DLAAD algorithm is correct and effectively levels the drilling platform dynamically. It can thus provide essential support in resolving drill rod sticking problems during actual underground coal mine drilling operations. Practical implications The DLAAD algorithm supports smooth drill rod operations in underground coal mines, which greatly enhances safety, reduces power consumption, and minimizes cost. The approach proposed here thus represents considerable benefits in terms of coal mine production and shows notable potential for application in similar fields. Originality/value The novel DLAAD algorithm and leveling control method are the key contributions of this work, they provide dynamical 3 D leveling and help to resolve drill rod sticking problems.

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