| Compared with ordinary grinding discs,patterned grinding discs have active grinding areas and passive grinding areas.These two active areas allow the patterned grinding discs to perform intermittent grinding processes,thereby reducing the total contact time between the grinding disc and the workpiece,and the average grinding Cutting force and cutting zone temperature.In recent years,laser welding is considered to be the best heating method for brazing patterned diamond grinding discs because of its flexible operation,combined with numerical control technology to achieve selective heating,and small heat-affected zones.This thesis is oriented towards patterned grinding discs,exploring the process parameters,interface connection mechanism and performance evaluation of laser brazing diamond.The research focuses include: using four combinations of Ni-Cr-P/45#,Cu-Sn-Ti/45#,Ni-Cr-P/TC4 and Cu-Sn-Ti/TC4 as the solder and substrate,and studying the preheating The best process parameters of laser brazing diamond with the assistance;analysis of the micro morphology and interface products of the brazed diamond/brazed layer/substrate interface;design and preparation of laser brazed diamond spiral pattern grinding discs and linear pattern grinding discs,and pass the grinding test The grinding performance of 99 alumina ceramic workpiece was evaluated.The main conclusions are as follows:1.With the aid of preheating,the process parameters of Ni-Cr-P/45# and Cu-SnTi/45# combined laser brazing diamond: average power 120 W,negative defocusing distance 14 mm,scanning speed 0.4mm/s;The process parameters of Ni-Cr-P/TC4 and Cu-Sn-Ti/TC4 combined laser brazing diamond: average power 100 W,negative defocusing distance 14 mm,scanning speed 0.4mm/s.Under the above process parameters,the solder is completely melted,spreads uniformly,the diamond shape is intact,and the brazing effect is good.2.The analysis of the cutting edge height of laser brazed diamond abrasive grains shows that the cutting edge height of Cu-Sn-Ti/45# and Cu-Sn-Ti/TC4 composite abrasive grains is better,and there is no obvious dent in the cross section of the substrate;Ni-Cr-P/ The 45# and Ni-Cr-P/TC4 composite abrasive grains have poorer edge height,and the base section has obvious depressions.3.In laser brazing,the Cr element in the Ni-Cr-P/45# combination solder alloy is enriched towards the diamond interface,and it is speculated that Cr3C2 and other chromium-containing carbides will be generated.4.In the three kinds of combination laser brazing of Cu-Sn-Ti/45#,Ni-Cr-P/TC4 and Cu-Sn-Ti/TC4,the Ti element in the solder alloy is enriched towards the diamond interface.It is speculated that Ti and C The elements undergo chemical reactions to form Ti C compounds.During laser brazing,the matrix and the solder alloy are eutectic to strengthen the connection between the two.5.Comparing the grinding performance test of different combinations of abrasive grains shows that the Ni-Cr-P/45# combination laser brazing diamond pattern grinding disc has the fastest abrasive grain failure,mainly due to shedding;Cu-Sn-Ti/45#combination laser The main failure mode of the abrasive grains of the brazed diamond pattern grinding disc is macroscopic crushing and shedding;the main failure mode of the Ni-Cr-P/TC4 composite laser brazing diamond pattern grinding disc abrasive grains is grinding;the Cu-Sn-Ti/TC4 combined laser The main failure mode of the abrasive grains of brazed diamond pattern grinding disc is macroscopic fracture.The Cu-SnTi/TC4 combination has better grinding performance than the other three combinations.6.Comparing the grinding performance test of different pattern grinding discs shows that the failure of laser brazing linear pattern grinding disc abrasive grains is the fastest,mainly flattening;compared to laser brazing linear pattern grinding disc,laser brazing spiral pattern grinding disc surface The number of abrasive particles is larger,the grinding rate is lower,and the grinding performance is better. |
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