Papers by Keyword: Abrasive Jet

Abstract: In recent years, with the deepening of China's reform and opening up policy, the rapid development of the national economy and urban high-rise buildings and underground engineering increasing, many kinds of malignant fire have become increasingly complex and frequent. In the event of a fire, it may cause great loss of life, serious injuries and state property. In the absence of the necessary rescue equipment, fire brigade and emergency departments in fire and explosion engineering, engineering rescue and various natural disasters will delay the rescue, even can do nothing to rescue. This proves the forcible entry tools play a significant role in fire fighting and rescue. Therefore, the fire brigade and rescue departments should equip with efficient forcible entry tools for rescue as soon as possible.

Abstract: Abrasive jet technology is widely used with the advantages of environmental protection, with better energy concentration and processing quality, free from any tool passivation, heat affected zone, spark, or any changing in physical or chemical properties of workpiece. Due to the fact that jet characteristics are the main reasons which influence processing quality, numerical analysis is used as the major method of researching currently. The existing research of jet characteristics of abrasive jet by numerical simulation methods is discussed in the paper, including jet fluidizing and mixing process simulation, jet formation process simulation and jet erosion workpiece simulation. Finally the key problems of the simulation on the jet characteristic are given.

Abstract: Abrasive waterjet (AWJ) micro-machining is a precision processing technology with some distinct advantages. To understand the machining process, the erosion mechanism is presented and discussed when micro-particle impacting on a quartz crystal specimen. It is found that three types of impressions are formed which are craters, micro-dents and scratches. Small-scale craters including crashed zones and radial cracks are associated with plastic flow and subsurface micro-cracks that decrease the material strength, but cause little material removal, while large-scale craters including conchoidal fractures caused by the propagation of lateral cracks dominate the volume change of the specimen. Micro-dents are produced by the impact of particles possessing small kinetic energies, and scratches are generated by particle sliding or rolling over the target surface and make a negligible contribution to material removal. The crater volume generated by the impact of individual particle is then discussed with respect to particle impacting velocity and impact angle. It shows that an increase in particle impact angle or particle velocity increases the crater volume due to the increased conchoidal fractures during the impact process.

Abstract: This paper puts forward a kind of new technology for metal matrix difficult-to-machine materials based on compound energy field. The new technology combine electrochemical jet machining and abrasive jet machining technology, which obtain the high quality of processing surface and greatly improve processing efficiency. Aiming at the new technology, the experimental device of compound machining is established, a large number of process experiments are carried out. The different process parameters are studied for the influence of the machining efficiency, including the machining gap, voltage and jet pressure. The experimental results show that the compound machining can be applied to machining or polishing complex shape parts of metal matrix structure difficult-to-machine materials, so it has widely application prospects.

Abstract: The pretreatment of the tube wall's surface needs to be done before coating and plating. The cleaning and derusting play an important role in the pretreatment. This paper designs the cleaning and derusting system of the steel tube inwall by premixed abrasive jet technique. The system consists of the generating device of premixed abrasive jet, the abrasive retrieval device and working mechanism. The test of clean and derust were carried on steel tube inwall by the system. In the test, the large inner diameter of pipe fittings adopted the oblique type nozzle, the small ones adopted the conic abrasive jet nozzle. The test shows that the designed system can achieve the purpose of cleaning and derusting on steel tube inwall. The appropriate working parameters: the working pressure is 12MPa, the rate of water flow is 30L/min, the abrasive weight consistency is 30%.

Abstract: In this paper, it introduces the work principle of abrasive waterjet polishing (AWJP) and analyzes the jet distance to the influence of the AWJP under a certain pressure, with a numerical simulation and analysis to the jet distance based on jet mechanics and fluid dynamics. By establishing the physical models of the different jet distance of the AWJP and adopting the Realizable k-ε model and the SIMPLEC algorithm, it gains the jet flow field of the AWJP with different jet distance models and the distribution of turbulence intensity and pressure and velocity on the workpiece surface. The numerical simulation results of the different jet distance were analyzed and compared, according to the AWJP to the characteristic requirement of the jet. By doing the polishing experiment with a abrasive waterjet cutting machine, it verifies that the best polishing distance range of AWJP is from 10 times to 13 times of the nozzle diameter, which provides the theoretical basis for the process research of the AWPJ in the future.

Abstract: In order to change surface morphology and contact angle of part, abrasive jet method is discussed in the paper. Glass, steel and titanium are used to study its surface morphology by the processing of abrasive to jet the surface. In addition, the extent of its impact of processing method is studied with different abrasive size. Experiment method and environment are also introduced, and experiment shows that contact angle of glass changes from 14.9° to 93.8° (Titanium and steel also have different degrees of diversification). According to experiment of the method, abrasive jet methods affects contact angle, and it has the value of further research.

Abstract: Based on the modeling and experiments concerning the surface roughness in abrasive jet finishing with grinding wheel as restraint, the effect of abrasive size, abrasive fluid concentration, machining cycles, wheel velocity and carrier fluid on machined surface quality was investigated. Surface grinder M7120 was employed in a jet machining experiment conducted with W18Cr4V and 40Cr materials, profilometer TALYSURF was used to measure the micro geometrical parameters after machining, and SEM was used to observe surface micro-morphology. Experimental results show that with W7 Al2O3 powder at the mass fraction of 10% and antirust lubricating liquid being adopted in jet machining for 20 to 30 cycles, not only high surface shape precision can be kept or obtained, but also defect-free machined surface with the roughness of Ra0.15～1.6µm can be obtained with high efficiency. Experimental observation and experimental results proved that the experimental results agree well with a mechanism-based machining model.

Abstract: This study introduces an Abrasive Jet Polishing (AJP) technique using wax-coated abrasive SiC particle to improve the polishing quality of mold surface. The experimental results showed that the surface roughness of EDM machined mold cavity improved by 82% (from 4.23 μmRa to 0.76μmRa) within 90 minutes. Moreover, the parting surface roughness improved by 94.7% (from 1.14μmRa to 0.06μmRa). We show that employing the abrasive jet polishing technique with wax-coated SiC particles, not only the mold surface roughness got a good improvement, but also significantly shorten the polishing time.

Abstract: Most existing models for abrasive jet machining (AJM) are based on erosion models for either ductile or brittle materials. This classification imposes some limitations, because most materials are neither absolutely ductile nor absolutely brittle, but lay within the continuous spectrum between those two idealizations. This work reports recent progress in the modeling of erosion processes for real materials, and discusses the implications of a new model in estimating the performance of AJM. The new model is more capable in explaining the effects of jet velocity, abrasive particle size, and various material properties on the efficiency of the cutting process.