Experimental Research On Cutting Life Of Endless Diamond Wire Saw

Nd-doped yttrium aluminum garnet(Nd:Y3Al5O12,YAG)was widely used in the fields of industry,medical treatment,military and scientific research,which has the characteristics of high gain,low threshold,low loss and high mechanical strength,etc.The first process of YAG crystal processing is usually sawing,which costs more than 40% of the production cost,and the accuracy of sawing also affects the efficiency,quality and cost of subsequent processing steps.Fixed endless electroplated diamond wire saw cutting was often used for high-precision sawing of precious hard and brittle materials due to its high sawing accuracy and no commutation veins.At present,due to the limitations of process conditions such as electroplating and welding,the life-time of consolidated endless-plated diamond wire saws is short.Therefore,extending the lifetime of the wire saw has important practical production significance for reducing the processing cost of the precious material YAG crystal.The main factor affecting the lifetime of the wire saw is the shedding of the consolidated diamond abrasive grains,which mainly affected by the alternating stress of the abrasive grains during the sawing process.In this paper,the fracture mechanism of brittle materials was analyzed,then the single abrasive sawing model was established with finite element software to study the influence of cutting parameters on sawing force.Finally,a group of orthogonal experiments were designed to summarize the influence of cutting parameters on the lifetime of wire saw.Based on the fracture of brittle solids,the material removal model of wire sawing process is established.A mathematical model of the electroplated diamond wire saw describing the size of the diamond top angle,protruding height,and plating position were established,these model trial simulation results have high similarity with real wire saws.Based on the principle of constant cutting volume and a mathematical model of the average cutting depth of a single diamond,we have established a mechanical model of a single diamond.The test results show that the sawing force of a single diamond is proportional to the feed rate of the wire saw and inversely proportional to the cutting speed of the wire saw.The material Knoop hardness,the position of single diamond,the geometric angle of the abrasive,and the distribution density on the wire saw affect sawing force.According to the mechanical model,we selected the feed rate and sawing speed as the key research objects.The constitutive behaviors of YAG crystal was established by using ABAQUS finite element simulation software,and the process of sawing brittle materials was analyzed by two-dimensional and three-dimensional finite element simulation.Three-dimensional simulation found that the sawing force of a single diamond abrasive rapidly with the increase of the sawing speed of the wire,and then tended to decrease steadily.The maximum sawing force of a single diamond abrasive increased with the increase of the cutting depth.The two-dimensional simulation found that the depth of the sub-surface damage of the processed surface was deeper at the beginning of the low speed,and then it became shallower quickly and then gradually deepened.We designed an experiment to saw YAG crystals using a endless electroplated diamond wire sawing machine,and analyzed and classified the common failure forms of electroplated diamond wire saws.A set of orthogonal experiments was used to analyze the test results using the range method.The results showed that the higher the sawing speed,the longer the lifetime of the wire;the sawing speed had the greatest effect on the lifetime and the feed rate had a certain effect on the lifetime.Finally,the BP neural network method was used to train the life prediction model of the wire saw,and the accuracy of the network model was verified by the prediction data experiments.Through the study of this subject,we explored the main factors limiting the life of diamond wire saws,which has important guiding significance for improving the production and processing technology to extend its life and reduce production costs in the future.