车削理论-基础.ppt

* But to gain something from a 90° entering angle, your radial D.O.C must be bigger than the nose radius. If the DOC is not at least the nose radius then benefit of using a 90° entering is diminished and will tend to increase radial cutting forces (Vibration). * With the high stock removal rate the chips are needed to be evacuated out from the hole needs to be increased not to damage the work piece. Boring upside down to keep chips away from cutting edge？？？ * 演示--车削刀片断屑对比（见附件1） * Internal operations are to greater extent very sensitive to the ratio between the overhang and the diameter. It is possible to effect those factors which strengthens the risk for vibrations. 短屑，功率大、振动大；月牙洼磨损严重； 长屑，排屑问题；振动小；不利于自动化生产； 螺旋屑最好。容易排出，对刃口压力适中，刃口不易断裂。 The hard breaking of chips, short chips, is power demanding and can increase the vibrations. Long chips can also cause problems for chip evacuation. Short chips can cause excessive crater wear and result in poor tool life and chip jamming. Short and spiral chips should be sought for internal turning. These are easy to transport and do not cause a lot of stress on the cutting edge during chip breaking. Long chips cause little vibration tendencies, but due to difficulty in evacuation of the hole can cause problems in automated production. * * * * Self Breaking Chip - the material and the curve of the chip causes the chip to break as it comes off the insert. Breaking against the Tool - the chip curves around until it makes contact with the clearance face of the insert of tool holder. This is considered acceptable but can lead to chip hammering. (Chip Hammering) - occurs when the chip that is being cut ( which is now harder than the material being cut) hits the clearance face of the insert damaging the clearance and resulting in insert breakage. Breaking on the Workpiece - the chip in this operation breaks after it makes contact with the workpiece. This type of chip breaking is not acceptable because it can cause damage to the surf