硬质合金刀具切削钛合金Ti6Al4V界面摩擦特性研究

Friction Characteristic of Interface in Machining Ti6Al4V with Carbide Tools

钛合金Ti6Al4V具有高的比强度、良好的机械性能和抗蚀性,但因其化学活性大、导热系数低,切削时刀具磨损严重。为选择合理切削参数以减少刀具磨损,研究钛合金在不同切削条件下刀-屑/工界面的摩擦特性。结果表明,在切削速度较低时,刀具磨损表面紧密接触区附有大量黏结物,而在切削速度较高时,会产生不稳定粘结物,且刀具与工件材料接触面发生扩散,不稳定黏结物的脱落造成刀具微崩刃,加速刀具的磨损;采用合理的切削速度时,黏附在刀具表面的工件材料会发生氧化反应,生成的氧化物具有一定边界润滑作用,使黏结磨损与氧化磨损达到平衡,因此能减弱刀具-工件间接触时的高温黏结,降低刀具的磨损。

Titanium alloys Ti6A14V have superior properties, such as excellent strength-to-weight ratio, high corrosion resistance and good mechanical properties. However, due to its high chemical reaction and low thermal conductivity, tool wears seriously during cutting.In order to choose resonable cutting parameters so as to reduce tool wear, the friction charac- teristic of tool-chip/workpiece interface in machining TirA14V with carbide tools were studied under different cutting speeds.The results show that, at rather low cutting speed, there are lots of adhesion materials in the close contact area in wear surface.At quite high cutting speed ,the adhesion materials become unstable and diffusion occurs in the tool-work- piece interface.The peeling off of unstable adhesion material leads to tool micro-chipping and accelerates tool wear.When employing optimum cutting speed ,the oxidation reaction occurs in tool-workpiece interface.The oxides generated in the cut- ting process acts as a boundary lubrication layer, which makes the chemical wear and adhesive wear to reach equilibrium, therefore, the high-temperature adhesion is inhibited and tool wear is reduced.