The Experiment Research On The Micro-Holes Finishing Base On Fluid Magnetic Abrasive

Hole is a common machining feature. It is widely used in many fields, such as the automobile, medical devices, aerospace, fluid control and so on. The surface’s roughness of hole has an important impact on the performance including working life, reliability, stability of the entire product. With the increasing sophistication and miniaturization of mechanical products, modern industrial production has increasingly high quality requirements on the surface’s quality of transport holes. But precision finishing holes (cross-hole, profiled hole, shoulder hole) has been a difficult for machinery industry. Based on this reason,"the fluid magnetic abrasive finishing of hole technology" was researched by us. The feature of fluid magnetic abrasive change in magnetic field and superiority of extrusion grinding was used to realize the finishing of hole. In the pressure, came from power, fluid magnetic abrasive flew through the hole and changed form a flexible grinding layer with the surface of hole in the magnetic field. In the process, the abrasive particles impacted and scratched the surface of the hole. This technique can make the Ra roughness improved1-3accuracy level (The Ra roughness can reduce from1.3μ m to0.4μ m after twenty minutes’ processing). And this finishing do not cause surface and subsurface defects, controllable, have high quality and cleanliness. So fluid magnetic abrasive finishing can be used for the precision finishing of tenuous hole, shoulder hole and some complex surface. With all these advantages, fluid magnetic abrasive surface finishing technology owns many advantages in finishing process.In this paper, some issues have been investigated on the basis of microscopic scale, such as the preparation techniques of abrasive, mechanism of fluid magnetic abrasive finishing process and the equipment. The method adopted throughout the present studies is a combination of theoretical analysis, experimental investigation and numerical calculation. Adopting the method of theoretical analysis and experimental test, we systematically researched the mechanism of magnetic abrasive finishing machining, cutting model of abrasive grain, macro material removal efficiency, the influence of various factors on the machining efficiency and a series of important issues from a macro and micro angle. The main research is as follow:1) Research on the liquid magnetic abrasive’s stability. The preparation methods and preparation process of liquid magnetic abrasive has been studied and a liquid magnetic abrasive which suits hole finishing machining was developed. For the defect of poor stability, this article discussed how the polyacrylic acid, nanometer silicon dioxide and PH affect the stability of the liquid magnetic abrasive.2) Research on the mechanism of liquid magnetic abrasive. The magnetorheological mechanism of liquid magnetic abrasive was analyzed with the guidance of dipole moment theory of magnetic particle, then the material removal mechanism of holes machining by the liquid magnetic abrasive was expounded from a microscopic view.3) The expressions of material removal rate by Liquid magnetic abrasive. The model of double circle radius was used as the cutting model of abrasive particles, through the mechanics analysis of single abrasive grain, the material removal rate of mathematical expression was derived and the effect of various factors on the machining efficiency was discussed.4) Experiment device design. Based on the hydraulic system, a set of extrusion experimental device was designed with the guidance of holes machining mechanism. For the defects of low wear resistance and impermeability, some methods were taken to improve the wear resistance and impermeability of the loading cylinder. In order to solve the problem fundamentally, a set of hydraulic diaphragm extrusion system was designed.5) The experiment and analysis. Experimental research on the quality of the final surface roughness of finishing hole influenced by the factors of specimen material, processing time, impressed current intensity, abrasive particle size, inlet pressure. Experiment analyzed the influence of each factor through the mathematical expressions.6) Through a set of orthogonal experiment, we discussed the primary and secondary effects of the processing time, inlet pressure, current intensity on the processing, and the best pieces of3mm hole processing technology was preliminarily determined.In this paper, the finishing mechanism, the preparation technique of fluid magnetic abrasive, the single abrasive particle cutting model has been deeply studied. Furthermore, many effects to the finishing surface quality, such as finishing time, magnetic field intensity, abrasive particle size and so on was analyzed. At last, from theory and experiment the paper verified that fluid magnetic abrasive finishing hole is feasible. The research result has a certain guidance and reference significance to hole finishing.