Study On Surface Chemical Modification Preparation Process And Experiment Of Unconsolidated Magnetic Abrasive

As the abrasive tool of magnetic abrasive finishing technology,the property of magnetic abrasive directly affects the processing quality,efficiency and cost of parts.But because of the current preparation processes are difficult to preparing the high performance and low-cost of magnetic abrasive,so greatly restricting the industrial application of this technology.In recent years,many scholars have used mechanical mixing method to prepare unconsolidated magnetic abrasive,and the processing effects are very well.The unconsolidated magnetic abrasive has many advantages such as simple preparation process,low cost,the low rigidity magnetic brush formed under the action of magnetic field and the excellent ability to polish the complex surface.However,there have two aspects problems in the abrasive prepared by this method.On the one hand,the ferromagnetic powder,abrasive powder and the binder are difficult to be bonded together very well,so the abrasive grains are easy to fly apart during the processing and affecting the processing quality and efficiency of the workpiece.On the other hand,the ferromagnetic powder and the abrasive powder are easily agglomerated in the binder and are difficult to be dispersed evenly,which can make scratch and other side effects on the surface of the workpiece,thereby affecting the processing uniformity of the magnetic abrasive.According to the abrove problems of this processing,this paper put forward that the ferromagnetic powder and abrasive grain are surface chemical modified by coupling agent,to improve the compatibility and dispersion stability of them in the polyvinyl alcohol,and then the modified powder and polyvinyl alcohol are mechanically mixed to prepare the unconsolidated magnetic abrasive.In this paper,some process parameters in the process of coupling agent modification are studied by experiments,and some performance indexes of the prepared abrasive are analyzed and tested.The main contents of this paper are as follows:1.The principle of unconsolidated magnetic abrasive finishing plane and its material removal mechanism are analyzed.The composition and performance requirements of the unconsolidated magnetic abrasive are described.The classification and function of the lapping liquid are introduced.The force analysis of the single grinding particles is mainly carried out,and the results show that the normal pressure Fpn of the workpiece is related to the particle size ratio A of the ferromagnetic phase and the abrasive grain,and then the theoretical range of A is deduced.2.The preparation process of unconsolidated magnetic abrasive is made.The effects of the type,dosage,reaction temperature and reaction time on the modification effect are studied by single factor experiment with the activation index as the method of characterization.The results show that under the same experimental conditions,the modification effect of titanate coupling agent NDZ-101 on the reduced iron powder and white corundum is better.After being modified,the activation index of powder is high and its hydrophobicity is strong.Considering the modification effect and economy,the optimum dosage is 3%,the optimum reaction temperature is 70℃,and the reaction time is 40 min.3.The saturated magnetic induction intensity of the unconsolidated magnetic abrasive is measured by the magnetic circuit measuring device to evaluate the magnetic properties.The value of magnetic field strength H and current I are found when the magnetic induction intensity B is saturated.Then the threedimensional model of the existing magnetic circuit measuring device is established,and the unconsolidated magnetic abrasive is simplified as spherical.Then the magnetic induction intensity of the abrasive under different current values is simulated by Maxwell software.The results show that the measured results are basically identical with the simulation results,and the measurement accuracy is high.In addition,the SUS304 stainless steel plate as the workpiece to study the service life of unconsolidated magnetic abrasive,the results show that when the 304 stainless steel plates with the initial roughness Ra about 0.4μm are machined,the service life of magnetic abrasive is high,and it is about 36 min.4.The processing performance of unconsolidated magnetic abrasive is tested by machining plate workpieces.The effects of coupling agent type,diameter ratio of ferromagnetic powder and abrasive,the type and proportion of lapping liquid and the properties of materials on the surface roughness and surface morphology are investigated by the experiment.The results show that the unconsolidation magnetic abrasive has excellent processing performance,and after being machined,the surface quality of the workpieces is high and reaching the mirror effect.