Technology And Experimental Research Of Paddle Liquid-particle Two-phase Flow Finishing

The subject is to study the two-phase finishing process. At present, theprocess uses a fluid phase, such as high pressure gas or liquid in a certain spacedoing compulsive circulation movement. As the fluid phase moves, the abrasiveparticles which are included in the fluid phase will also do compulsivecirculation movement on the surface of the workpiece, then the solid abrasiveparticles can scratch and roll the surface of the workpiece, finally the surface ofthe workpiece is finished. As the liquid-particle two-phase compulsivecircumfluence finishing process works, it needs special equipment to producehigh pressure fluid as a power source, and also to make use of drainage pipes, sothe whole process is very inconvenient. In this paper, proposing a new paddleliquid-particle two-phase finishing process to resolve the problems.The idea of this process in the paper comes from the theory mechanism ofmetal in two-phase liquid-particle fluid. There are many engineering applicationof two-phase liquid-particle fluid, such as pipeline transport, the turbines in thehydropower. Many researchers have paied efforts to prevent erosion of metalparts, they implement a lot of theoretical and experimental studies, such as the flow velocity of two-phase liquid-particle, the flow angle and the shape hardnessof the solid particle to reduce the erosion on the metal wall. Therefore, theprocess in this paper is to accelerate erosion-corrosion of the metal in two-phaseliquid-particle fluid, meanwhile referring to the principles of the mixer paddle inthe application of the production, then the new process uses a impeller which isrolling at a high speed driving the solid particles rolling close to the surface ofthe hole, then the solid particles scratch, grind the surface for finishing, when theprocess works, the impeller moves along the hole axis of the workpiece in orderto achieve a complete finishing.Firstly, this paper described the mechanism of the erosion-corrosion ofmetal wall by solid particle in the fluid, then it analyze the principle of theprocess, the mechanism of abrasive particle finishing the surface of theworkpiece and the form of exercise and stress condition of the solid particle.It simulates the flow field of working area by using the FLUENTsoftware,such as single flow field simulation of different parameters of differentblade number impeller,different impeller rotation speed and different workpiecehole diameter. By contrasting the total velocity, axial velocity, radial velocity,tangential velocity and the distribution of the pressure field, it comes theconclusion that three blades impeller is the most suitable; in a certain rotationrange, the higher rotation speed, the flow of the field gets more high motionspeed and the wall gets higher dynamic pressure; for a certain diameter impeller,its range of application is limited. When it simulates liquid-particle two-phase flow field, the results shows that abrasive particles which are near the impellermove intensely and the force on the wall is stronger.Finally it carried out some experiments with a Φ130mm45#steel pipe forresearching the effects of different impeller rotation speed, different abrasivematerials and particle size on the processing conditions, by comparison, in acertain rotation speed range, the higher impeller rotation speed, the higherprocessing efficiency, and it can obtain lower surface roughness Ra value; thesurface quality obtained by alumina abrasive material is better than that obtainedby silicon carbide abrasive particles. Surface machined by small size of abrasiveparticle can be better than the large size of abrasive particle.