High speed cutting machines craft analysis

Treatment of high speed cutting is current one of the most advanced process instrumentation. The angle analysis that machines craft from high speed machines the fabricating characteristics of material light metal, steel, cast-ironly, hard, in can be being machined actually thereby reasonably dosage of formulate procedure, cutting and cutting tool parameter. Processing technique of foreword high speed is to point to use super- hard data cutting tool and grind, the production equipment of the high accuracy that uses can reliable ground to realize high speed to move, tall automation and Gao Rou sex, raise material to excise precision of rate, treatment and the advanced processing technique that process quality with raising cutting speed to achieve. Mix as numerical control machine tool, machining center flexible production system makes medium application in machinery, the auxiliary man-hour of machining shortens greatly. This makes cutting man-hour is occupied went the body of total man-hour, accordingly, raise cutting speed and feed rate only, just raising productivity respect to appear likely new leap and breakthrough. This makes high speed processing technique is able to develop quickly. High speed cutting is different when workpiece material, uses cutting cutting tool, technique and cutting parameter all have very big different, mastering characteristic of craft of high speed cutting is one of technology of application of high speed cutting important segment. 1.

Light metal of high speed cutting is aluminous it is plane and the main material of all sorts of spacecraft component, also be the commonly used metal of machine and appearance component. Its opposite density is very light, through the aluminium alloy material of proper processing, its intensity can be as high as 540 MPa. In recent years the aluminium alloy application in car and machinery of other motive force also is added gradually much. Aluminum-magnesium alloy uses cast mostly, the biggest advantage of these light alloy cuts character easily in Yu Jigu some. Main show is in the advantage that machines light alloy: ① cutting force and cutting power are little, compare cutting steel about small 70% ; ② cuts bits not short, curly, implement the automation that discharge bits easily in high speed treatment consequently; ③ cutting tool wears away small, be in with the cutting tool such as diamond of coating hard alloy, much brilliant very tall cut fast next cutting are light alloy material, can reach very tall cutting tool life; Quality of ④ treatment surface is high, use only a few below the cutting fluid, case that fighting cutting approximately, need not repass any treatment or handiwork are abrade, the spare parts can get very high surface quality; ⑤ can use very high cutting rate and feed speed to undertake machining, cutting speed can be as high as 1000m/min-7500m ／ Min, high speed treatment makes the heat in metal cutting of 95% above is cut bits is taken away quickly, workpiece can hold room temperature position, heat is out of shape small, treatment precision is tall. Because be in the process of high speed cutting of light metal,put in bigger concussion load, get together the life performance that brilliant diamond and cubic nitrogen turn boracic cutting tool is bad. High-speed steel also does not agree with treatment light metal. When cutting speed achieves 1000m/min, can use cutting tool of K hard alloy; When cutting speed achieves 2000m/min, should use cermet cutting tool; When be machined with taller cutting speed, especially when the material of silicon aluminium alloy of cutting low melting point, want to use cutting tool of diamond film hard alloy, even PCD cutting tool; When milling aluminum-magnesium alloy, can use cutting tool of K10 hard alloy. The impact of radius of edge round horn to scintilla of cutting temperature and particle is very big, the edge radius of PCD cutting tool or hard alloy cutting tool must the level that accurate blade grinds accept rice class. 2.

Steel of high speed milling in recent years, high speed treatment begins to use Yu Gang and cast-iron precision work, machine the part with complex form especially, high speed cutting can improve productivity greatly. The main problem of steel of high speed milling is cutting tool wears away. The purpose that optimizes cutting parameter is led to raise a metal to excise not just, and pay attention to more at reducing cutting force, precision of the exterior quality that improves work, dimension and appearance precision and reduce cutting tool to wear away. When rolled steel of high speed milling, cutting tool uses sharper cutting blade and bigger hind horn, can reduce the cutting tool when cutting so wear away, improve the service life of cutting tool. When feed rate increases, the horn after cutting tool wants to reduce; The feed speed influence to the horn before cutting tool is comparative and minor. Below high speed, before the horn before horn does not compare 0 ° reduces cutting force morely; Although the horn before losing can make bit has taller cutting stability, but increased cutting force and crescent moon to wear away depression. Will tell commonly, as cutting speed rise, cutting tool life is reduced. Lift further when cutting speed, the slippage rate of the area goes to surface contact of the knife before making cut bits and cutting tool high when the heat-resisting capacity that exceeds cutting tool material, can cause crescent moon to wear away depression. When high speed milling, axial feed is smaller to influence of cutting tool tatty, and the impact of radial feed is bigger, cutting tool life is reduced along with the addition of cutting face. When undertaking cutting with radial feed, the red rigid that because the high temperature of high speed generation exceeds cutting tool material,often meets and create cutting tool be no longer in force. When radial feed is slower, the time of blame contact area of cutting tool compares osculatory area time to grow, of short time calorific and OK will make up for by longer refrigeration. Accordingly, look from whole, radial feed speed should a bit a bit slower, the 5% ～ that suggest the value of feed is equal to cutting tool diameter 10% . The wears away to also be machined the mechanical function such as data strength influence of the cutting tool when high speed cutting. The tensile strength of workpiece material increases, criterion cutting tool life is reduced, want to reduce the feed of every tine so. In side of data of cutting tool of high speed cutting, the life of cermet cutting tool is longer than hard alloy, but also apply to only small cut mix greatly the cutting of small feed. The effect when use CBN cutting tool processes oil hard data is good, hard data of oil of blame of treatment of use CBN cutting tool is wasteful, not big to improving the dominant position of cutting tool life, cermet cutting tool also is such. Of cutting tool of Nextpage film hard alloy wear away character and use cutting tool base material have very big concern. The PVD film cutting tool of TiN matrix has best wear-resisting property, life of its cutting tool compares those who do not have film cutting tool to be able to raise 50% ～ 250% . 3.

High speed milling is cast-iron when high speed milling is cast-iron, the circumstance of the horn after cutting tool and steel about the same. Turn silicon cutting tool to resembling nitrogen material of such brittleness cutting tool, the appearance that main factor is bit mixes tatty of influence cutting tool geometrical parameter. When high speed milling is cast-iron, must use round blade cutting tool, otherwise cutting tool can damage because of tall brittleness very quickly. The choice of cutting speed depends on cutting tool material. To hard alloy and cermet cutting tool, the mainest problem in high speed cutting is cutting tool wears away. Because cermet cutting tool has bit strength tall, density is low as good as chemical stability wait for an advantage, it is good that its durability should compare hard alloy, but when cutting speed exceeds 1000m/min, do not use this kind of cutting tool. To hard alloy and cermet cutting tool, cutting tool durability rises as the addition of feed speed. And nitrogen changes silicon cutting tool and CBN cutting tool to just agree with to undertake cutting below lower feed rate. Radial is cut deep one of crucial factors that are durability of influence cutting tool, as the accretion of cutting area area, cutting tool life is reduced. And axial cuts profound influence not quite, should cut be in greatly 1.

When changing inside limits of 5mm ～ 15mm, the wear extent of cutting tool is same almost. Also be affected by treatment hardware data the durability of cutting tool. The iron content of the material that be cut, very big to the durability influence of CBN cutting tool, when cutting GG40 cast-iron material, the durability of CBN cutting tool reached lowermost value. When use film, cutting tool life can raise 10 times ～ 20 times. When use CBN cutting tool, cutting speed can be as high as 4000m/min. Actually, only CBN and nitrogen change ability of silicon cutting tool to undertake cutting below so high rate, especially CBN cutting tool, attainable very long cutting tool life, but must use lesser feed. 4.

Material of difficult treatment of material of difficult treatment of high speed cutting includes alloy of special alloy steel, titanium, nickel alloy to wait, these material because intensity big, hardness is tall, impulse withstand, be made for nothing with Yu Hang mostly and dynamical branch. But these material in treatment are easy and sclerotic, cutting temperature is high, cutting tool wears away serious. In the cutting of these difficult treatment material, the typical form that brings about bit invalidation is cutting tool wears away, tatty trace can produce the passageway part between place of point of a knife and cutting tool and workpiece, form serious blade burr consequently. Of edge wear away the geometrical parameter that changed cutting tool, increased cutting power, make easily when alloy of cutting high strenth especially bit disintegrate. Bit crackle basically is caused by thermal stress, be in especially cutting is special when alloy, pectination crackle is apparent, next crackle continues abrade expands, form grind mark. Another characteristic of difficult treatment material is their adhesiveness, make cut bits to be stuck on edge, rise as cutting speed, the grow in quantity cutting bits of conglutinate, the accumulation cutting bits that burns heat cuts bit of part in what cutting tool cuts person work, form the tumour that accumulate bits. When cutting titanium alloy, quantity of heat increases the exothermic reaction of generation and oxygen. Should wear away take width to achieve 0.

When 3mm above, cause the inflammation that cut bits. In wear away below the circumstance of serious aggravate, intense hair heat energy exceeds the fused temperature of material. Although high speed treatment is medium,the temperature of workpiece did not rise apparently, but the temperature that cuts bits is greatly elevatory. In the test that in alloy, special to titanium alloy and heat-resisting 3 kinds of material such as nickel radical alloy have high speed is machined, the cutting tool when suitable mill wears away to want apparently big, the cutting tool that its reason is suitable mill cuts bits to add when leaving work thick, generation is larger pull stress, increased the possibility with broken razor blade consequently. The high strenth of these material and tall flexibility, especially meet an emergency is sclerotic, increased cutting load. The span of the horn before cutting tool is to be between 28 ° of 8 ° ～ , inside range of the role before this, the horn before increasing can reduce cutting force apparently, the cutting tool life when processing afore-mentioned all data can rise. Current part is when losing, the cutting stability of cutting tool rises, but life is reduced, because cutting bear is in to increase in edge,this is. After raising cutting rate, the power that cutting consumes is greater, cutting temperature is elevatory, quickened cutting tool to wear away. But tall cutting speed also shortened the osculatory time of cutting tool and workpiece, delivered the heat in metal cutting to workpiece to decrease, heat in metal cutting is main by cut bits rapidly to take away. In high speed cutting, cutting tool wear extent follows radial approach (or cut deep) the pattern that shows exponential curve rises, wear away aggravate, calorific quantity increases. Cut deep increase the ply that makes cut bits and length, the sky that reduces bit necessarily cuts time, cause the calorific amount on bit bigger. 5.

The last word improves productivity is mechanical all the time production domain pays close attention to very and do it indefatigable struggling main goal. High speed is machined (HSM) not only the manufacturing efficiency that twice improved a machine tool, and the treatment precision that improved a spare parts further and exterior quality, still can solve the treatment problem that certain and special material solves hard in groovy treatment. Accordingly. Exceed high speed to machined this one advanced processing technique to already also caused the height of group of industry of world each country and academia to take seriously. CNC Milling