A Study On Brazing Technique Of Producing Diamond Drills In Continuous Furnace

Due to the features of high bonding strength,high grain protrusion,large swarf clearance space and so on,advantages of brazed diamond tools has been proved by many recent researches and practical applications: higher machining efficiency,longer tool lifetime,higher grain utilization ratio,etc.At present,it is almost impossible for most company to produce brazed diamond tools in large quantities,while social demand for mass production of brazed diamond tools is increasing.Thus,it is urgent and necessary to improve the production efficiency of brazed diamond tools.In this paper,brazed diamond drills were token as the study object.To meet the market demand mentioned above,utilization of continuous belt furnace production line for mass production of brazed diamond tools was proposed.Based on a large amount of analysis on vacuum brazing technology at home and broad,much in-depth research work was carried out to analyze impact mechanism of influencing factors,mainly referred to heating technique,including temperatures in each district and the belt speed,the protective atmosphere.These furnace brazing experiments were carried out in a Suqian hot-treatment company.To simplify experiments' variables,the belt speed was set 200mm/min,for we were told that for similar workpieces with small sizes,good heating performances were obtained under the speed.Then according to physical characteristics of brazing filler metal and diamond,the brazing temperature range was determined and 7 groups of experiments were designed in this range.Two temperature curves were detected with the sensor fixed in the central point of brazing area in two certain experiments randomly selected from the experiments.The influence of brazing process parameters on the brazing quality was learned from the microstructure in the brazing area and machining tests of samples.Results showed the optimal brazing parameters as follow: temperatures for each district are,1080?,when belt speed is 110mm/min.Combination of experiments and numerical simulations was introduced to the analysis of the brazing process in belt furnace in this paper.According to the heat transfer of furnace brazing process,some simplifications were made,then the feasibility of the numerical simulation turned possible,3D transient thermal analysis model was finally built.Then the model was analyzed in the software ANSYS,a temperature curve of the same positon with that in the experiment above was obtained from simulation.Some modifications kept being made until the temperature curve from simulation nearly coincided with that detected by thermocouple.In this way,the model set up in this paper could be utilized to predict the temperature curve.At last,the model under the optimal parameters gained from experiments was analyzed and a temperature curve was acquired.Based on the temperature curve,more efficient brazing process parameters(higher belt speeds,higher district temperatures)can be obtained through repeated simulations.Moreover,through comparisons between vacuum brazing and belt furnace brazing,influence of the new brazing technique on microstructure and machining performance was discussed in this paper.