Rong Guo Hou

The Effect of High Pressure Abrasive Water Jet Cutting Parameters on Cutting Performance of Granite

The effect of cutting parameters such as water pressure, nozzle traverse speed and standoff distance on the granite cutting performance as characterized by kerf width, kerf taper, and striation drag angle are researched with a series of experiments using garnetabrasive and ultra high pressure abrasive water jet numerical control machine tool. The relationship between system pressure and abrasive mass flow rate is also studied. The research results show that the abrasive mass flow rate is only proportional to water pressure and the effect of other cutting parameters is not significant. It is found that an increase in water pressure is associated with an increased kerf width and a decreased kerf taper. The kerf width decreases with the enhancement of nozzle traverse speed, and resulting in a significant increase in kerf taper as the nozzle traverse speed increases. The kerf width increases with the enhancement of standoff distance, and hence it causes a significant increase in kerf taper at the standoff distance domain from 3mm to 4mm and then a little decrease in kerf taper at the standoff distance increasing from 4mm to 5mm. The striation drag angle decreases with an increase in water pressure and a decrease in nozzle traverse speed.

An Experimental Study on Milling Al2O3 Ceramics with Abrasive Waterjet

The machining performance of Al2O3 ceramics is studied by abrasive waterjet (AWJ) milling experiment. The machined surface characteristics and the effect of process parameters on machined surface quality are analyzed. The results showed that the nozzle traverse speed and traverse feed have a strong effect on the machined surface quality. The effect of process parameters on material volume removal rate and the milling depth is also researched. The results indicated that the material volume removal rate and the milling depth would be increased at the milling conditions of higher water pressure and bigger standoff distance. However, the milling depth will decrease at the milling conditions of higher traverse speed and higher traverse feed, and the material volume removal rate has a complex variation.

Simulation of Velocity Field of Two-Phase Flow for Gas and Liquid in the Abrasive Water Jet Nozzle

Simulation on velocity field of gas-liquid flow in the abrasive water jet nozzle was studied by the computed fluid dynamics (CFD) software, The complex velocity field of the flow in the abrasive water jet nozzle can be obtained by means of simulation. The study on the effect of the nozzle inner cone angle on the velocity field shows that the cone angle affects the whirlpool’s intension and position of the whirlpool in the nozzle of abrasive water jet (AWJ), and it also affects velocity ‘s magnitude and distribution of the velocity on the cone surface.

Numerical Simulation and Experimental Investigation of the Gas-Liquid-Solid Three-Phase Flow Outside of the Abrasive Water Jet Nozzle

Simulation of the gas-liquid-solid three-phase flow field of outside the abrasive water jet(AWJ) nozzle is studied by the computed fluid dynamic software- FLUENT, and the velocity field of the three-phase flow is obtained, the velocity value of the flow between the nozzle and work-pieces is also obtained. Serial experiments have been done to verify the simulation method. In the experiments, the impact force signal of the AWJ outside the nozzle is collected by the piezoelectricity ergometer, then it is filtered by the vibration signal and dynamic signal software. The testing values are transformed to the velocity values, which will be compared with the simulation values. The comparison result indicates that the value of the simulation is changing similarly with the experiment value, and both value is almost the same, which proves that the simulation method is successful, the simulation model and the boundary conditions are right.

Theoretical Analysis on the Machining Mechanism in Ultrasonic Vibration Abrasive Waterjet

As a unique machining way, Abrasive Waterjet Machining (AWJ) is one of the fastest developing new non-traditional machining methods and has a wide range of machinable materials. In this paper, the machining mechanism in AWJ is theoretically analyzed by impact dynamic mechanics method. There is stagnancy layer between waterjet and workpiece surface. It is found that the stagnancy layer and low energy abrasive particle are the main factors, which weaken machining capability and effective utilizing ratio of energy of AWJ machining. Ultrasonic Vibration Abrasive Waterjet Machining, a new machining method, is put forward and the influence of ultrasonic vibration on machining mechanism of AWJ machining is discussed.

Simulation of Solid-Liquid Two-Phase Flow Inside and Outside the Abrasive Water Jet Nozzle

Simulation of the velocity field of solid-liquid flow inside and outside the abrasive water jet nozzle was studied by the computational fluid dynamics software(CFD). The velocity field of the flow in the abrasive water jet (AWJ) nozzle was obtained. The results indicate that the swirl is produced in the nozzle and the abrasives are all distributed along the inner surface of the nozzle. The velocity at the center of the outlet face is the highest, while it is smallest at the both edge. The dispersion of the flow is happened when it flows out of the nozzle, but the flow velocity away from the outlet at a distance of about 4 times of the outlet diameter changes little. The fillet diameter, the inner cone angle, the length of mixing tube of the nozzle greatly affect the field of two-phase flow. The velocity of outlet increases with an increase in the fillet diameter, the flow becomes ease when the cone angle decreases, the mixing tube hampers the two-phase flowing.

Study on Experiment Device of Abrasive Water Jet Micro-Turning

An abrasive water jet micro-turning experiment device is designed to solve the problem for micromachining the revolving parts. This device is composed of the machine body, hydraulic system, collection devices and control equipment etc. This paper emphasizes on the structure design of the moving parts of the abrasive water jet turning process, clamp, lathe bed, abrasive water jet injecting system and collection system. The turning spindle system and feed drive mechanism are designed, and the strength, stiffness and precision of the ball screw transmission mechanism are calculated and checked to meet the needs of the abrasive water jet micro-turning experiments.

The Measurement of the Velocity Outside the High Pressure Water Jet and Abrasive Water Jet Nozzle Based on the Energy Transfer Method

The energy transfer method is used to measure the flow velocity of the outside the high pressure water jet (WJ) and Abrasive water jet (AWJ) nozzle. The impact forces of the flow measured by the piezoelectricity ergometer will be transformed to the velocity value, the average velocity of the flow outside the nozzle will be obtained. The result indicates the velocity will reduce along the direction of the flow, and the velocity of the AWJ flow will reduced greatly than the WJ flow, which indicates that the length of the core part of the AWJ flow is shorter than the WJ Flow, the stand-off should be within the 0mm-15mm ranges to gain the most effective machining.

Effects of Electrical Discharge Energy on Machining Performance of Sintered NdFeB Magnet

Sintered NdFeB permanent magnet is widely used in many areas because of its excellent magnet property. In this study, the machining parameters of electrical discharge machining (EDM) are varied to study the effects of electrical discharge energy on material removal rate and surface roughness of NdFeB magnet. Moreover, the micro-cracks on the machined surface induced by EDM are also examined. The experimental results reveal that the MRR increases with the electrical discharge energy. The number of surface cracks on the machined surface increases with the enhancement of discharge energy Thus, using EDM process to machine sintered NdFeB magnet depends on setting the machining parameters to prevent surface crack.

Three-Dimensional Simulation of Liquid-Solid Two-Phase Flow Inside the Abrasive Water Jet Nozzle

Three dimensional simulation of the velocity field of solid-liquid two-phase flow inside the abrasive water jet nozzle was studied by the computational fluid dynamics software (CFD). The complicated velocity field and vectorgraph of the flow in the abrasive water jet nozzle was obtained. In the course of the simulation, the Syamlal-O’Brien model was used to decide the inter-phase drag exchange coefficient. The velocity vectorgraph simulation results indicate that the highest flow speed is occurred at the inlet of the mixing chamber and the flow speed is gradually decreased along the direction of the nozzle axis and got to the lowest speed at the outlet of the nozzle. And also the flow speed in the cross section of the mixing chamber is gradually reduced along the radial direction of the cross section and got to the lowest speed in the verge of the chamber. The comparison of simulation result for the velocity field of water and abrasive exhibits that the velocity of water in the mixing chamber is three or four times higher than that of abrasive.