预烧结氮化硅陶瓷坯体加工缺陷抑制与精密成形研究

Chipping Defect Suppression in Precision Machining of Pre-sintered Silicon Nitride Ceramic Green Body

采用金刚石涂层刀具对预烧结氮化硅Si3N4陶瓷坯体进行干铣削加工,研究了切削参数对切削力的影响规律,探究了Si3N4陶瓷坯体加工表面崩边缺陷的形成机制与抑制方法,分析了金刚石涂层刀具的失效形式与磨损机理。试验结果表明:干铣削Si3N4陶瓷坯体时,进给方向的切削力随着进给速度的增加呈先下降后上升的趋势,在进给速度为50mm/min时,切削力取得最小值;陶瓷坯体断裂韧度较低是引起崩边缺陷的主要因素,通过降低进给速度能够抑制陶瓷坯体的崩边缺陷,由此确定最优的切削参数组合为主轴转速5000r/min,进给速度50mm/min,切削深度≤1.0mm;粉末状切屑形态降低了切屑与刀具前刀面之间的接触,因此金刚石涂层刀具的失效方式主要是后刀面磨损,磨损机制主要是塑性磨粒磨损。

The pre-sintered silicon nitride(Si_(3)N_(4)) ceramic green body is machined in dry milliing with a diamond-coated carbide tool.The influence of cutting parameters on the cutting forces is studied.The formation mechanism and suppression methods of the chipping defects on the machined surface are investigated.The failure mode and wear mechanism of diamond-coated tools are discussed.The results show that cutting force decreases first and then increases with the feed rate increasing, and the minimum force is obtained when the feed rate is 50 mm/min.The chipping defects is mainly related to the low fracture toughness of the ceramic green body.The chipping defects of the ceramic body can be suppressed by reducing the feed rate.Thus the optimal cutting parameters are obtained with spindle speed of 5000 r/min, feed rate of 50 mm/min, and cutting depth less than 1.0 mm.The interact area between the tool rake face and the chip is very small due to the powdered chips.The failure mode of diamond-coated tools is mainly flank wear, and the wear mechanism is plastic abrasive wear.