蜂窝状铝合金高速加工刀具粘附行为及其作用机理研究

Adhesion Behavior and Mechanisms in High Speed Machining of Cellular Aluminum Alloy

通过高速铣削试验方法对蜂窝状铝合金高速铣削刀具的粘附行为及粘附机理进行了研究。结果表明,由于初期铝屑粘附在刀具表面上,致使后期切削加工中的铝切屑与刀具表面的化学活性近似,使得铝屑进一步强化粘附在刀具表面,且由于高速加工中产生的高温和高压作用,使得粘附层材料发生变形。后续切屑划擦初期的粘附层,使粘附层出现变形和犁沟现象,加剧刀具与工件间的摩擦状态。同时,铝合金高速加工中高的塑性变形特征是发生粘附磨损的另一重要作用机制。此外,切屑表层材料受到剧烈剪切变形引起表面积增加,使切削形成的金属表面膜破裂,在与刀具表面紧密接触的近乎为真空环境下刀具不断切削新的表面,活性非常高,极易发生摩擦化学反应,较高摩擦化学反应形成的表面厚度达到临界值时将发生磨损,导致刀具粘附磨损加剧。

This paper analysis the adhesion behavior and adhesion mechanism in high speed milling honeycomb alumi- num alloy by experiment. Results show that the initial aluminum scraps adhesion make the tool surface approximation for the same metal with the workpiece, making aluminum scraps adhesion on tool surface intensified. Because of the high tem- perature and high pressure in high speed machining, deformation appear on the adhesive layer. Meanwhile, the initial ad- hesive layer is scratched by subsequent chip, the adhesion layer deformed and further aggravate friction happened between the tool and the chip or workpiece. Additionally, high plasticity characteristic is another important mechanism in the forma- tion of adhesive wear in high speed machining aluminum alloy. Meanwhile, the superficial area of the chip increase caused by severe shear deformation, which rupture the initial stages of cutting metal surface, new surface is cut in close contact with the tool surface near to vacuum conditions, and the atoms on the new surface layer outside keep an unsaturated bond stress state, the surface is quite lively, friction wear surface produced. When the friction chemical reaction reached a cer- tain critical value, tool adhesion wear appear.