Experimental Study On Grinding Performance Of High-density Nomex Honeycomb

Nomex honeycomb composite material is composed of tough aramid fiber and hard brittle phenolic resin.As an ideal weight loss filling material,Nomex honeycomb has the advantages of low density,high specific strength and specific stiffness,high temperature resistance and good insulation performance.The sandwich structure made of Nomex honeycomb is widely used in aviation,aerospace,high-speed train,weapon and other fields.High-density Nomex honeycomb has better mechanical properties such as compressive strength,shear strength and modulus.In addition to the material characteristics of Nomex honeycomb,it also has high brittleness due to large content of phenolic resin.Due to the need for multiple dipping and curing during the preparation process,high-density Nomex honeycomb is difficult to perform secondary processing after curing.In order to meet the processing requirements of high-density Nomex honeycomb,this paper proposes the processing of high-density Nomex honeycomb by diamond grinding wheel according to the material characteristics of high-density Nomex honeycomb,and analyzes the material removal behavior under different grinding directions.On the basis of the grinding test,six typical characteristics of high-density Nomex honeycomb in the grinding process are summarized,which are double-layered aramid paper widening,aramid paper adhesion,aramid fiber drawing,phenolic resin exfoliation,phenolic resin hole and phenolic resin scratch.Combining the effect of high-density aramid paper honeycomb grinding morphology on the mechanical properties of honeycomb and the bond strength between honeycomb and skin,the defects of processing morphology are proposed,which are double-layered aramid paper widening,unseparated chips and fiber drawing.The evaluation method of high-density aramid paper honeycomb grinding quality is proposed by three parameters,such as the width of doublelayered aramid paper,the width of unseparated chips and the length of fiber drawing,providing a reference for quality evaluation for the grinding of high-density Nomex honeycomb.The high-density Nomex honeycomb end face grinding and circumferential grinding tests were carried out by single factor test method.Grinding morphology and grinding force by influenced by spindle speed,feed rate,depth of cut and grinding direction were studied.The test results show that different processing methods and process parameters have great influence on grinding morphology and grinding force of high-density Nomex honeycomb.In terms of grinding morphology,when grinding wheel is fed by end face along L-direction of honeycomb cell,increasing spindle speed can obtain a good grinding profile,while increasing feed rate results in the increase of aramid fiber drawing.Increasing depth of cut will help to suppress widening of double-layered aramid paper,but will increase the unseparated chips.In circumferential grinding,when the grinding wheel feds along L direction and spindle speed and cutting depth are increased,and a good machining profile can be obtained under the given cutting conditions.When grinding wheel is fed in W direction.the grinding morphology is worse.In terms of grinding force,when the grinding wheel is fed by end face along L-direction of honeycomb cell,both tangential force and normal force decrease with the increase of spindle speed,while increase with the increase of feed rate and depth of cut.When grinding wheel is fed by circumferential face in W direction of honeycomb cell,the tangential force and the normal force decrease with the increase of spindle speed,and increase with the increase of the cutting depth.Under the same cutting conditions,the grinding feed direction has little effect on the tangential force,and the normal force of the grinding feed in the W direction is smaller than that of L direction when the grinding depth is 0.1 mm and 0.5 mm.