CBN磨粒Cu-Sn-Ti合金的预连接及电阻焊工艺

Pre-bonding and resistance welding process of CBN grits with Cu-Sn-Ti alloy

  • 摘要: 利用Cu-Sn-Ti合金预连接CBN磨粒,并将其用电阻焊焊接在基体上,为有序排布CBN工具磨粒的精确固定和工具使用后损毁磨粒焊植修复做先期探索。通过差示扫描量热法对Cu-Sn-Ti合金热分析;使用扫描电镜分析预连接及电阻焊后磨粒的微观形貌;用拉曼光谱仪分析电阻焊试样及钎焊试样磨粒的应力;通过磨削试验研究电阻焊CBN磨粒的磨削性能。研究表明,在950 ℃保温120 s的预连接工艺下,CBN与Cu-Sn-Ti合金产生化学冶金结合。电阻焊后预连接层与基体预熔涂层熔合,焊缝未见裂纹、气孔、未熔合等缺陷,CBN磨粒仍然棱角分明。在距表面600 μm处,钎焊CBN磨粒所受压应力σ=0.43 GPa,电阻焊CBN磨粒压应力为0.69 GPa,较大的压应力使电阻焊CBN磨粒受到更强的把持力。磨削试验显示,电阻焊CBN磨粒的稳定性及磨削效率优于钎焊CBN磨粒。创新点: 该项研究能够克服其他方法焊植磨粒时,磨粒容易窜动的缺陷,对CBN工具的制造及修复再制造有特殊意义。

     

    Abstract: CBN grits were pre-bonded using Cu-Sn-Ti alloy and then they were welded on the substrate by resistance welding, which was a preliminary exploration for the precise fixation of CBN grits on CBN tools with orderly arranged grits and for the replacing of damaged grits of used CBN tools. Thermal analysis of Cu-Sn-Ti alloy was completed by differential scanning calorimetry. Scanning electron microscope was used to observe the micromorphology of the grits pre-bonded and those welded by resistance welding. Raman spectrometer was used to analyze their stress. The grinding performance of CBN grits welded by resistance welding was studied by grinding test. CBN and Cu-Sn-Ti alloy could combine chemically at 950 ℃ for 120 s. After resistance welding, the pre-bonded layer was fused with the pre-melted coating of the matrix. No defects such as cracks, pores and non-fusion were found in the weld, and CBN grits was still angular. At 600 μm from the surface, the compressive stress of brazed CBN grit was 0.43 GPa, and that of CBN grit welded by resistance welding was 0.69 GPa. The larger compressive stress made the holding force of Cu-Sn-Ti alloy towards CBN grits welded by resistance welding stronger. The grinding tests indicated that the stability and the grinding efficiency of CBN grits welded by resistance welding were better than that of brazed CBN.Highlights: The research could overcome the defect that the grits were easy to move when they were welded by other methods, and it had the special significance for manufacturing and repairing of CBN tools.

     

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