Effect of rotary ultrasonic machining on surface residual stress of TiBw mesh titanium-based composites
In order to study the effect of rotary ultrasonic machining on the residual stress on the material surface under different cutting conditions,the TiB whiskers(TiBw)reticulated titanium matrix composites were selected as the experimental objects,and the surface residual stress of the machined materials was analyzed by rotary ultrasonic machining with nickel-based electroforming diamond grinding wheel.The results show that due to the network structure and excellent high temperature properties of titanium matrix composites,the residual stress caused by cutting heat and microscopic phase transformation is small,while the residual stress caused by abrasive mechanical action is larger.With the introduction of ultrasonic vibration,abrasive particles impact the workpiece surface at high frequency,which makes the residual stress on the workpiece surface of rotary ultrasonic machining greater than that of ordinary grinding.Under the machining parameters of spindle speed n=9 000 r/min,feed speed vf=8 mm/min and machining depth ap=25 μm,a residual compressive stress of-540 MPa exists on the surface of the rotary ultrasonically machined workpiece,and with the increase of spindle speed,the residual stress decreases significantly,and the influence layer depth of residual stress decreases gradually.The introduction of ultrasonic vibration increases the residual compressive stress on the workpiece surface and improves the fatigue resistance of materials.
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