The efficient CNC Machining of structural member of titanium alloy aviation

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Rise as what people asks to modern plane performance, titanium alloy compares intensity with its tall, mechanical performance is good the application that can wait for a characteristic by force to go up in modern plane with corrosion resistance is wider and wider also, it is especially in high-powered battleplan, the proportion that aluminium alloy place holds already was as high as 40% . The graph is shown 1 times is an U.S. Army the cobra opportunity for combat that from 20 centuries 70 time design arrives the circumstance of change of main material scale of opportunity for combat of present bird of prey. Increase what hold proportion as place of titanium alloy aboard ceaselessly, the effect that the CNC Machining efficiency of structural member of titanium alloy aviation creates a company to aviation is bigger and bigger also. Titanium alloy belongs to difficult treatment material, its are relative to cutting sex 0.

15 ~ 0.

25, 10% what machine efficiency to be aluminium alloy only, because the low treatment efficiency of structural member of aviation of this titanium alloy is serious,restricted the batch of modern plane to produce. If the efficient treatment that how realizes structural member of titanium alloy aviation became aviation to make manufacturer of equipment of enterprise, numerical control and tool manufacturer pay close attention to jointly, inscribe. Cutting of 1 titanium alloy machines   of characteristic of craft of structural member of titanium alloy aviation function titanium is one of metals with the richest contain on the earth, arrange in the metal the 3rd, as more mechanical than having as other metal photograph function good, corrosion resistance can be strong and proportion is small wait for a characteristic. But in be being machined actually, the cutting processability of titanium alloy can be very poor, main show is in the following respects: (Force of 1) big cutting. Strength of titanium alloy data is high, the cutting power that produces when cutting is 2 times of medium carbon steel, big cutting mechanical responsiveness sends cutting point to produce many heat in metal cutting; (Rate of 2) heat conduction is low. Titanium alloy emissivity has the 1/4 of iron, aluminous 1/16 only respectively, many heat in metal cutting is centered in cutting area, bring about cutting temperature to be as high as 700 ℃ ; (Stress of 3) point of a knife is great. The plasticity of titanium alloy is low, machine generation cut bits to bend extremely easily, bring about cut bits and before the osculatory length of knife face is short, have the 1/2 ~ 2/3 of 45# steel only, accordingly pressure of area of the unit on cutting blade increases, cause concentration of stress of place of point of a knife; (4) attrition muscularity. Compare as a result of the coefficient of friction between titanium alloy material and cutting tool material on one hand big, measure small, Qu Jiang to compare as a result of the stretch model of titanium alloy on the other hand big, before causing, hind the attrition aggravate of knife face; (5) chemistry is lively the gender is tall. Titanium element falls in high cutting temperature, very easy as chemical as the aeriform happening such as the hydrogen in air, oxygen, nitrogen reaction, form exterior hard layer, quicken cutting tool to wear away. At the same time titanium element has chemical reaction easily also with cutting tool material, create cutting tool material diffuse, make cutting tool wears away serious. Alloy of titanium of characteristic of craft of structural member of aviation of 2 titanium alloy basically applies at the crucial component of high temperature area, casing of the airframe after if lie between thermal conductivity fan housing, tail,the cover is mixed paragraph wait. It is contented concealed body, macrobian life and structure as modern plane light quantify the function that waits for a respect to ask, structural member of titanium alloy aviation is applied in great quantities in aircraft design. Aviation structural member is a plane is main bear force component, spare parts appearance involves the complex and academic external form such as appearance of airframe appearance, wing appearance and area of alar body confluence, and undertake covering closing with many spare partses, the structure is accordingly complex, treatment difficulty is great; Material purify amount is large, material purify rate is in 50% above, partial part is achieved even 90% ; Feature of antrum of Bao Bi, deep chamfer is occupied 80% , for typical weak rigid structure, machine condition pole to be not stabilized; The spare parts assembles the amount such as harmonious face, nodical aperture much, demand of spare parts production precision is high (see a picture 2) . The cutting processability because of structural member of aviation of this titanium alloy can be very poor, treatment efficiency is extremely low. Current situation of treatment of structural member of aviation of 3 titanium alloy is in at present respect of CNC Machining of structural member of titanium alloy aviation, conventional treatment method uses machine tool of low speed big torque, high-speed steel and hard alloy cutting tool, low rotate speed to cut deep means treatment greatly, rate of its metal purify is 30 ~ 60cm3/min generally, highest do not exceed 200cm3/min; And the treatment to aluminium alloy, current, use high speed generally to machine plan, metallic purify rate can achieve 500 ~ 2000cm3/min generally, highest can achieve 6000 Cm3/min. Because this and aluminium alloy photograph are compared, the treatment efficiency of titanium alloy is the 1/20 ~ 1/10 of aluminium alloy only, treatment efficiency is very low. As a large number of titanium alloy application in plane structural member, the treatment efficiency problem of titanium alloy spare parts will become the bottleneck that restricts development of new generation opportunity for combat, production. Nextpage   pursues the 3 metabolic curves that lead for aluminium alloy and purify of titanium alloy metal, the metabolic case that the metallic purify of individual main shaft leads 1970 ~ between 2005 showed in the graph. Because aluminium alloy is the main material of aviation structural member all the time, the treatment efficiency of aluminium alloy gets all the time of aviation manufacturing industry take seriously, after a large number of application that process a machine tool in aluminium alloy high speed especially, the treatment efficiency of aluminium alloy got substantially rise, the metallic purify rate that to 2005 aluminium alloy machines was achieved 9 1970.

5 times; However titanium alloy processing technique is in almost place footfall, the metallic purify rate that to 2005 titanium alloy machines is only 1 1970.

5 times. Apply in great quantities in titanium alloy accordingly today, the efficient treatment of structural member of titanium alloy aviation is sure to make the central point that new technology grows. Titanium alloy is efficient because structural member of titanium alloy aviation is efficient,machine equipment the demand of CNC Machining is very pressing, manufacturer of a lot of machine tool of aviation numerical control had changed the key of product research and development to titanium alloy efficient treatment by aluminium alloy treatment, among them most typical is German DST company. DST company had begun the research of facilities of efficient to titanium alloy treatment 2005, development went machining center of horizontal of alloy of ECOFORCE series titanium, predict to put in the market 2010, the metallic purify rate of this machining center achieved 600cm3/min, 3 ~ rose on existing foundation 6 times. At the same time the company such as FOREST-LINE, INGERSOLL and MCM is aimed at titanium alloy efficient treatment also developed corresponding new product. To satisfy the efficient treatment of titanium alloy structural member, new-style titanium alloy machines equipment to present a following development trends: (1) big torque. Because titanium alloy intensity is high, power of the cutting in bringing about treatment is very great, a of titanium alloy machine tool marked characteristic is main shaft torque is mixed the torque that place part is big. On the ECOFORCE machine tool of DST, main shaft torque achieved 1100N · M, a, C places horny torque to be 8000N · M. (The application of 2) report main shaft. The electric main shaft of high-power, big torque already began to apply at titanium alloy treatment. The electric main shaft that the POWERMILL horizontal machining center that INGERSOLL company rolls out configured torque of power 106kW, main shaft to be 928N · M is used at titanium alloy treatment, if pursue,4 are shown. (3) horizontal machining center applies at titanium alloy treatment. Horizontal machining center discharges bits to go to the lavatory, be helpful for improving treatment efficiency and treatment quality, exchangeable workbench realizes multitask easily machine and establish flexible product line, raise utilization rate of equipment and installations. Because this horizontal treatment is titanium alloy structural member the important way of efficient treatment. At present efficient treatment machine tool all employed most new-style titanium alloy the configuration that horizontal machines. At present the workbench bizygomatic breadth of horizontal machining center is spent most greatly 2000mm, because this kinds of equipment is unwell,with Yu Chao large titanium alloy structural member is machined. (Inside 4) high pressure cold. The heat in metal cutting in titanium alloy treatment is centered in point of a knife, cause cutting tool easily to wear away or damage, the Leng Ke inside high pressure takes away heat in metal cutting with reaching cooling fluid as far as possible cutting area, at the same time high pressure still is contained drossy with the function that cuts bits to discharge. Refrigeration of main shaft center is a kind of older technique, but cold inside the main shaft on facilities of treatment of efficient titanium alloy have higher demand to pressure, achieve the high pressure of 6MPa above generally, some equipment achieved the pressure of 12MPa even. Titanium alloy is efficient one of crucial technologies that technology of cutting tool of treatment cutting tool is CNC Machining, also be the bottleneck of a technology that restricts difficult treatment material to machine efficiency. As the progress of cutting tool technology, structure of cutting tool material and cutting tool is improved ceaselessly, cutting tool sort is increasing, how logical choice cutting tool and cutting parameter become the core place that improves CNC Machining efficiency. Because the cutting processability of titanium alloy is poorer, speed of cutting of conventional treatment means does not exceed 60m/min commonly. To improve the rough machining efficiency of titanium alloy, the rough machining of titanium alloy basically is will obtain the biggest metal purify to lead with cutting the way of deep, low rotate speed, low feed greatly; Finish machining uses cutting tool of PVD coating hard alloy to undertake small cut wide, big cut deep high speed milling (cutting speed exceeds 170m/min) achieve tall cutting efficiency. Because cutting tool of treatment of this titanium alloy is main around if where,avoid when puissant cutting brace up quiver, reduce cutting force and reduce the respect such as cutting temperature to undertake improvement. Specific improve measure to be as follows: (Cutting tool of 1) puissant milling applies extensively. The cutter hub tigidity of puissant milling cutting tool is good, the firm link of bit and cutter hub, cutting tool diameter is big, the possibility in avoiding cutting effectively arises brace up quiver, type of main cutting tool is the corn milling cutter that is used at opening mill of groove, side. (Cold knife appears what provide in great quantities inside 2) high pressure. Cooling fluid of cutting tool interior arrives through high-pressured eject cutting area, the point of a knife that nods to cutting directly undertakes cooling, the temperature that reduces cutting blade and cutting tool wear away, at the same time high-pressured liquid was broken into pieces cut bits and take the platoon that cut bits in time. Use this kinds of cutting tool to be able to achieve higher cutting rate, improve treatment efficiency; Improve cutting tool life, reduce cutting tool cost and treatment time-out time; Broke bits and platoon bits effect goodly to improve a spare parts to machine quality. (3) exceeds close tine cutting tool, if pursue,5 are shown. The cutting tool that has blade of 10 above cutting leaving on cutting tool of integral hard alloy is titanium alloy the new technology of efficient treatment. The quantity of every tine cutting when this kinds of cutting tool reduces treatment through increasing tooth amount achieves the goal that reduces edge cutting force thereby, its principle and the principle that high speed machines are similar. Structural member of aviation of alloy of Nextpage   titanium is efficient when face of mill of 1 titanium alloy machines processing technique   to undertake to titanium alloy spare parts mill face is machined, use small the milling way that cuts deep, big feed wins efficient treatment. The principle of big feed milling is provide tool cutting edge angle through reducing a knife, make cutting tool still can maintain the very small ply that cut bits below very tall feed, in order to reduce the cutting force when Gao Jin gives, implementation obtains very big feed below low cutting speed, increase an unit to cut the metallic excision rate that leaves greatly. Below the same ply that cut bits, the feed of big feed milling cutter is close to common cylinder to establish 6 times of milling cutter, raised metallic excision rate greatly. At the same time because section of its cutting force is vertical when cutting of this kinds of cutting tool up, tangential force is lesser, the power that consume is lesser also, because this this treatment method is right the power of the machine tool and rigid demand are not high, application is very wide. In rough machining process, make sure edge stabilizes cutting continuously as far as possible, cutting tool contrail ought to eliminate pointed role as far as possible, ought to add round part appropriately in turning, make treatment process more smooth, 15% what radius of general circle horn is not less than cutting tool diameter. Antrum of chamfer of treatment of antrum of chamfer of 2 titanium alloy is a of structural member of titanium alloy aviation main feature, material purify rate is high, workload is big, because treatment of this chamfer antrum is spare parts of implementation titanium alloy the key of efficient treatment (see a picture 6) . The puissant cutting that cuts deep, low rotate speed, low feed greatly leads the effective method that is titanium alloy rough machining with obtaining purify of the biggest metal. At present the puissant milling cutting tool of alloy of rough machining titanium the efficiency with corn milling cutter is highest and get be adoptioned extensively. For example when hill spy dimension overcomes grooving of corn milling cutter to experiment, the biggest cut can amount to 109mm greatly, the biggest cut wide can amount to 66mm, rate of its metal purify is as high as 409cm3/min. To the treatment technique of groovy antrum rough machining, adopt U to get first commonly beforehand bore, next surplus of purify of reoccupy corn milling cutter, can achieve very high metallic purify rate. Processing technique is 3 round horn reduce plane weight, the groovy antrum corner of plane structural member manages round part normally lesser, need undertakes machining with the milling cutter with lesser diameter. Because cutting is in to measure mutation in round horn, cause cutting strength change is very big. In cutting force choppy circumstance falls, cutting tool produces vibration easily, appear even collapse blade phenomenon, bring about cutting tool to wear away serious, treatment efficiency is low. Strategy of traditional round horn treatment is the problem that will avoid round horn to be in treatment vibration through refining the method of orbit, its defect is orbit overmuch, efficiency is lower, the treatment of round horn is occupied 30% even more finish machining time. Inserting mill is the optimal way that settles corner to machine efficiency problem. Inserting mill is the milling of is similar to bore a kind of axial that axial of cutting tool of a kind of edge undertakes method, because insert the direction taking a knife of mill along cutter shaft direction, its cutting power is so major will along cutter shaft direction, radial cutting force is very small, compare groovy milling vibration when inserting mill consequently small, and the efficiency that its take surplus of corner of knife means purify is tall. The cutting tool inserting mill that passes different diameter undertakes inserting mill to corner office, can excise major corner surplus, reoccupy establishs the remain that milling cutter produces to inserting mill to undertake keeping clear of, can improve treatment efficiency substantially. Technology of mill of 4 accurate side is in traditional cutting method, cutting speed is in basically 40 ~ 60m/min, the high speed milling of titanium alloy is in definition of its cutting speed 120m/min above. In moment of finish machining parietal, use the will achieve high speed cutting spasmodically end of milling, in order to improve quality of spare parts surface and treatment efficiency. Moment of finish machining lateral, because cut wide small, tooth every had turned the cutting time of a week is very short, namely cooling time is very long. Below cooling and sufficient condition, its cutting temperature can get be controllinged effectively, can raise cutting speed to improve treatment efficiency considerably consequently, if pursue 7, the graph is shown 8 times. The milling cutter of integral hard alloy that uses PVD coating or exceed the finish machining of high speed cutting that ages hard alloy milling cutter undertakes titanium alloy closely, can raise treatment efficiency and treatment precision considerably. 5 emulate optimize part of construction of plane of technical titanium alloy to machine a feature complex, when rough machining cutting surplus can change ceaselessly, if the surplus of corner place is choppy,wait. The NC program that current CAM software place weaves often can set fixed cutting parameter only, make the impact of didymous cutting tool, machine tool greatly to because cutting has been measured,avoid local program, normally the method is through reducing integral cutting parameter assures cutting tool life and spare parts quality, machine efficiency thereby very low. The emulation that is based on Vericut optimizes a technology to be able to solve this problem well. Through Vericut software setting cutting parameter optimizes a library, undertake emulation with software, undertake forecasting through emulating pair of actual mental allowance and cutting condition, to the cutting in the program according to mental allowance and cutting condition parameter undertakes optimizing. Prolonged cutting tool life already, assured spare parts quality, also rose to machine efficiency. The efficient CNC Machining of structural member of aviation of alloy of last word titanium is one of difficult problem that at present aviation manufacturing industry faces. The technology before 3 square appearance cannot satisfy cutting tool of numerical control equipment, treatment and technology program far the treatment demand of structural member of titanium alloy aviation, this is sure to make CNC Machining trade the research heat henceforth, the demand of the efficient CNC Machining of structural member of titanium alloy aviation also is the fountainhead that promotes development of numerical control technology. CNC Milling CNC Machining