Use asymmetrical span tooth eliminates flutter

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  • source:BAGANZ CNC Machining
Flutter is the long-standing issue with a kind of high price in milling treatment. The influence of flutter can damage to enough greatly cutting tool, cause workpiece to discard as useless, damage even machine tool. More of flooey is, because be put in the risk that produces flutter, when may making the machine tool operates personnel to machine parameter in the choice too conservative, make machine tool ability cannot make the best use of everything. Normally, the process capability of the machine tool was used only 1/2 or a few. Flutter is a kind of self excited vibration, this kind of vibration is to show the energy that stabilizes an input from main shaft electric machinery passes some kind of mechanism by translate into vibration. The main mechanism of flutter of machine tool generation is " the make a present of of positive and negative of oscillatory wave magnifies " . By nature, treatment system (include cutting tool and work) dynamic tigidity is insufficient. When tooth cutting workpiece, can cause vibration, oscillatory tooth can form ripple in workpiece surface. When next tooth and moire surface are contacted, surface wave grain can bring about the ply that cut bits to produce change, the ply of change that cut bits can cause cutting force change again, cutting force of change can cause vibration. A kind of means that eliminates flutter mechanism is, the test machines dynamic character of the system, use these to check result plan cipher out to stabilize cutting area to pursue, stabilize condition of cutting of the choice inside interval in its. This kind of strategy that controls limits beforehand is relied on adjust cutting tool vibration and moire surface mutual be identical, when around ripple when mutual be identical, the ply that cut bits produces change no longer, vibration also stopped. When photograph adjacent tooth between a several as it happens of oscillatory wave for 1, 2 or when random is integral, can appear on stability sinusoid graph stable interval. Strategy of this kind of treatment needs to know to stabilize rate, stable rate carries inside range of permission main shaft rotate speed, have the tooth that distributings equably, control main shaft rotate speed accurately. Another kind replaces strategy is to pass change tooth span to restrain " the make a present of of positive and negative of oscillatory wave magnifies " mechanism. If tooth is had asymmetrical (inhomogenous) span, so, the moire face that the before one tooth of every tooth cutting keeps has different weaveform, restrained vibration thereby. Compare with the cutting tool look that has tooth of span of divide into equal parts, the cutting tool that tooth span differs can realize stabler axial cutting depth normally. However, want to achieve such result, need undertakes estimation carefully. Because feed is constant, the change of tooth span can bring about every tine feed to differ. This is meant normally, only a tooth can bear to cut bits negative charge entirely, and the tooth of the others fails however full load cutting. For this, must reduce cutting tool every turn effective feed, and, must pass cut axial deep increase each tine to just be balanced, make of feed reduce match to it. For example, the 4 blade that let us inspect tooth to distributing equably establish milling cutter and the stablest axial to cut deep amount (10mm) . Tooth presses 90 ° all cloth, arrange azimuth to be mixed for 0 ° , 90 ° , 180 ° respectively 270 ° . If allow the bear that cut bits (every tine feed) for 0.

2mm, criterion every transfer knife quantity to will be 0.

8mm/rev. If have the position of a tooth only among them,changed 10 ° , the azimuth of these tooth will be mixed in 0 ° , 100 ° , 190 ° 280 ° . Accordingly, the span of tooth is 100 ° respectively (the biggest span) , 90 ° , 90 ° and 80 ° (the smallest span) . The every tine feed that is in to maintain the biggest span does not exceed permission limiting value, the will biggest span regards control as span. Must go up in the foundation of feed of tooth of span of divide into equal parts, according to span of divide into equal parts and the biggest span than (90 ° are in this exemple / 100 ° ) scale, reduce feed. Such, the each span is corresponding bear cutting bits between each tooth is respectively 0.

2mm, 0.

18mm, 0.

18mm and 0.

16mm. And every turn feed is 0.

72mm/rev. To this cutting tool character, permission stable axial cuts the late rate that increases a quantity to must be more than 100/90, this is meant, 11.

1mm as it happens is the critical value that metallic purify leads. Generally speaking, when restraining make a present of of oscillatory wave positive and negative to magnify with this kind of method, to make differ span cutting tool has applied value, must allow axial to cut compare the biggest span greatly / of span of divide into equal parts than increasing one times. Same, rotate speed of change main shaft also can restrain the make a present of of positive and negative of oscillatory wave to magnify, but, when main shaft roll exceeds circuit, tooth span also is changed effectively. However, because feed is changeless, accordingly, the biggest span still can control feed. In implementation metallic purify leads before any raising, the axial that the change of main shaft rotate speed must allow to stabilize is cut compare the biggest span greatly / of span of divide into equal parts than increasing one times. CNC Milling