Based on the characteristics of Laser Metal Deposition Shaping (LMDS) technology, the related data processing algorithm was investigated in detail. This paper provides a kind of layered processing ...algorithm for STL file based on the limited topological information. At first, the triangle facets intersected with certain layered plane in the STL file were found out in disordered state, and then were read into the memory; secondly, the topological information was built to the found triangle facets; next, the intersecting lines between the layered plane and the triangle facets were figured out, so the contour lines on the layered plane were generated according to the founded topological sorting. Over and over, this process was finished until all layered contours were worked out. This algorithm could process the large STL files, save the memory expense, and improve the computing speed.
Precise measurement of two-neutrino double beta decay (DBD) half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay. We report the measurement of DBD ...half-life of
Xe using the PandaX-4T dual-phase Time Projection Chamber (TPC) with 3.7-tonne natural xenon and the first 94.9-day physics data release. The background model in the fiducial volume is well constrained in situ by events in the outer active region. With a
Xe exposure of 15.5 kg-year, we establish the half-life as 2.27 ± 0.03(
) ± 0.10(
) × 10
years. This is the first DBD half-life measurement with natural xenon and demonstrates the physics capability of a large-scale liquid xenon TPC in the field of rare event searches.
In the oilfield development, the packer is one of important downhole tool in oilfield drilling technology, and sealing effect of the sliding sleeve fracturing ball system directly affect the packer's ...sealing performance. Using UG software to establish 3D sliding sleeve fracturing ball and base model. Based on Ansys workbench simulation platform, finite element analysis was carried out on the sliding sleeve fracturing ball, distribution pattern in different materials, and sealing effect. Fracturing experiments were done to verify the accuracy of the simulation analysis and ensure the sliding sleeve fracturing system reliability in practical work.
In order to learn gas flow state in the vacuum high pressure gas quenching furnace, this paper simulates and tests the gas flow under the no-loaded and cold state. Hot wire anemometer is used to ...measure the speeds of some feature points, on the one hand to provide boundary conditions for the numerical simulation, and on the other hand to compare with the numerical simulation results. FLUENT software is used to simulate the gas flow of nozzle-type vacuum high-pressure gas quenching furnace. The results show that at the center of the furnace appears high-pressure low-speed zone in which is resulted by the gas collision there, and the vortex also appears in the area around the furnace. The results mean that the cooling rate of works will be slow there. Different exit velocities of five nozzles cause the uneven flow distribution, which will affect the cooling uniformity of works. The comparison between the simulation results and the measured results shows that the error is within 10%. It means that numerical simulation method to predict gas flow is feasible and the results are reliable in high pressure gas quenching furnace.
Coaxial powder delivery nozzle plays an important role in metal part direct and rapid prototyping technology and the reasonable structure can ensure uniform and stable flow of metal powder. Gas-solid ...two-phase flow theory is considered to simulate outside flow field of carrying gas-type coaxial powder delivery nozzle. The physical and mathematical models are erected. FLUENT software is used to simulate the velocity distribution of gas and solid particle, the volume fraction distribution of particle and the focusing properties. The simulative results indicate that both the structure of coaxial powder delivery nozzle and inlet velocity affect the convergence of powder. When the metal powder is only driven by the carrying gas without the shield gas flow, the powder appears focusing and the focus is 8mm far from the nozzle exit, but the volume fraction at the focus is only 2.6 percent, which shows the convergence of powder is not good and the usage rate is not high. In the optimized structure the simulative results show that the powder flow is affected by the flow of shield gas. When the velocity of shield gas is 6m/s, the powder shows good convergence and the volume fraction of powder at the focus reaches 3.3 percent. The higher the velocity of shield gas is, the more uniformly the powder flows, but the volume fraction at the focus is slightly lower. It is obvious that the numerical simulation will benefit for coaxial nozzle designing and performance improving.
High-pressure gas quenching is the heat treatment technology which quenches the works by use of high-pressure and high-speed flow gas. FLUENT software is used to simulate the process of gas-solid ...coupling flow and heat transfer in the nozzle-type vacuum high-pressure gas quenching furnace. The hot wire anemometer is used to measure the inlet velocities of nozzles, which provides the boundary conditions for computer simulation. By the computer simulation, the gas flow fields, work temperature fields and work cooling curves are attained. The results show that the big eddy current occurs at the corner of the furnace and the cooling rate of the work is slow there. Contrasting the simulating result of work cooling rate at the center of furnace with the actual measured one by the thermocouple, we find when work is cooled to the temperature of 430K, the simulating result is faster than the actual one about 50 seconds. The simulating results basically correspond with the actual trend of the gas quenching.
Defects or deficiencies in the repairing surface during the High Power Laser Cladding will be caused by the impertinent process, unstable equipment performance, cladding powder and other factors. ...Among the factors that the liquidity of powder in the pool can influence the surface topography directly; In addition, the existence of Oxygen (O) will lead to the formation of pores. Analysis through the experiments shows that: the addition of Aluminium (Al) additives will increase the liquidity of the powder pool effectively during the cladding process, simultaneously, Al 2 O 3 , generating from the combination of Al and O, will restrain pores and protect the surface of the cladding layer without reducing the hardness.
The fabrication of metal parts is the backbone of the modern manufacturing industry. Laser forming is the combination of five common technologies: lasers, rapid prototyping (RP), computer-aided ...design (CAD), computer-aided manufacturing (CAM), and powder metallurgy. The resulting process creates part by focusing an industrial laser beam on the surface of processing workpiece to create a molten pool of metal. A small stream of powdered alloy is then injected into the molten pool to build up the part gradually. By moving the laser beam back and forth and tracing out a pattern determined by a CAD, the solid metal part is fabricated line by line, one layer at a time. By this method, a material having a very fine microstructure due to rapid solidification process can be produced. In the present work, a type of direct laser deposition process, called Laser Metal Deposition Shaping (LMDS), has been employed and developed to fabricate metal parts. The LMDS apparatus consists of four primary components: energy supply system, motion control system, powder delivery system, and computer control system. These components have their specified functions, but work in association with each other.
Studying how and how much the factors affect on the cooling rate of workpieces is very significant to improve the ability of vacuum high pressure gas quenching furnace. From changing the structure ...and technology of nozzle-type vacuum high pressure gas quenching furnace, by a large number of computer simulation, this paper discusses some factors affecting the cooling rate. By changing the number and distance of nozzles on each wind pipe, we can better control the cooling rate and uniformity of workpieces. From the perspective of improved process, the number, shape, size and placement of the workpieces have certain effects on cooling rate, in which the placement of the workpiece is very significant and significant. The simulation results for the further development of new high-pressure gas quenching vacuum device provide a theoretical basis.
The fabrication of metal parts is the backbone of the modern manufacturing industry. Laser forming is the combination of five common technologies: lasers, rapid prototyping (RP), computer-aided ...design (CAD), computer-aided manufacturing (CAM), and powder metallurgy. The resulting process creates part by focusing an industrial laser beam on the surface of processing workpiece to create a molten pool of metal. A small stream of powdered alloy is then injected into the molten pool to build up the part gradually. By moving the laser beam back and forth and tracing out a pattern determined by a CAD, the solid metal part is fabricated line by line, one layer at a time. In the present work, a type of direct laser deposition process, called laser metal deposition shaping (LMDS), has been employed and developed to fabricate metal parts. Through the comprehensive experiments, it is found that this process is affected by many factors. Besides the processing parameters, scanning pattern is the one that strongly influences the quality and precision of as-fabricated parts. In comparison with the forming effects of different scanning patterns, the most suitable one can be selected to carry out this laser forming process. Finally, with the suitable scanning patterns, the high performance of the formed alloys is confirmed after the above studies.
