How to machine spare parts of titanium alloy aviation

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The design of new-style plane used foreword more composite material, also employed more titanium alloy at the same time. When assembling a plane, compare with aluminium alloy photograph, the compatibility of titanium alloy and composite material is better. Accordingly, 787 dream plane used Boeing the composite material of 50% (press weight plan) , also employed the titanium alloy of 15% at the same time. With the Boeing previously 777 photographs are compared, the titanium alloy of 787 uses Boeing the quantity increases considerably. Obtain enough titanium alloy data, in order to satisfy the requirement of new generation plane, it is a kind of difficult challenge. As the addition of demand, the price of titanium metal rises ceaselessly, new titanium alloy productivity also is being formed ceaselessly. But, up to now, the cutting of titanium alloy spare parts machines a problem have not very good solve. Although do not have a person to be able to provide exact data, but current titanium alloy process capability is satisfied unlikelily it seems that the demand that in a steady stream turns all sorts of new-style planes to the market ceaselessly, the scale that these planes use titanium alloy data is general taller. Anyhow, aviation industry supplies catenary to must try hard to improve titanium alloy process capability. Job shops of market demand demand with rapidder rate, treatment is compared before spare partses of more titanium alloy aviation. Boeing research and technical group (BR&T) it is to study what how machine titanium alloy to lead one of army group groups. The researcher of this group developed the technology of alloy of all sorts of efficient treatment titanium, make over its the component supplier of Boeing company next. The large structural member of the plane is formed by a lot of sunken antrum normally, the treatment of structural member basically is treatment sunken antrum, include milling all sorts of sidewall and costal region board. Use at new-style plane (like Boeing 787) this kind of sunken antrum is particularly deep, because spare parts of aluminium alloy of a few deep sunken antrum already was replaced by place of titanium alloy spare parts. Accordingly, the sunken antrum treatment of titanium alloy spare parts has bigger challenge sex. When machining aluminium alloy, to the sunken antrum of specific figure, the likelihood does not need to have rough machining and precision work respectively. Aviation industry manufacturer had mastered the skill that cuts aluminium alloy of deep accurate cutting with relatively stable radial, can use very big cut deep amount, efficient treatment gives sidewall or costal region board. But the treatment of titanium alloy differs completely however. When sunken antrum of milling titanium alloy, very slow cutting rate is meant, for effective purify much work material, still need to have rough machining and precision work respectively. Its are as a result, spare parts of alloy of efficient treatment titanium includes a series of discontinuous treatment measure, and every working procedure needs those who differ to use, the processing technique that passes test and verify. BR&T and tool supplier had developed processing technique of alloy of a few titanium. Application makes clear as a result, spare parts of aircraft of alloy of efficient treatment titanium does not need the machine tool of new-style machine tool and even specific type certainly. And, do not need very high finished cost certainly. These processing technique can apply alone, but if its compositive arrive one case, can form craft of a kind of disparate titanium alloy milling, it can shorten not only handling time, and still can save finished cost significantly. Finish machining sidewall is mixed much blade establishs the 1 standard of 8 ∶ of costal region board milling cutter is the cutting tool with the mainest spare parts of aircraft of alloy of efficient milling titanium. The researcher explanation of BR&T says, this group is certain " 1 criterion of 8 ∶ " , it is one of basic the golden rule that decide how to use much blade to establish milling cutter. In finish machining, much blade establishs milling cutter to be able to achieve very high metallic purify rate. To titanium alloy spare parts, ask rough machining and pace of finish machining cent undertake. The treatment of aluminium alloy spare parts differs with this. When milling aluminium alloy, the cutting rate that allows to use can achieve very high metallic purify rate with the bear that cut bits, even if much blade establishs milling cutter to apply to finish machining. But when machining titanium alloy, the rate of the biggest cutting that uses actually wants with the bear that cut bits low much. Accordingly, to achieve enough high metallic purify rate, must use a few otherer treatment is politic, if use,cut greatly deep undertake rough machining. When finish machining, as a result of the sidewall after rough machining or costal region board already became quite thin, so that must reduce cutting force, because this may be used no longer,cut greatly deep. Raising the strategy with finish machining exclusive and feasible productivity is to raise feed rate. Use those who have blade of enough much cutting to establish milling cutter to be able to accomplish this, because this kind of cutting tool is OK,lead through a few addition that cut bits negative charge and obtain very tall metal purify. Blade of how many cutting is more appropriate? The answer is: Had jumped over more more. Now, a lot of tool manufacturer can offer 10 blade to establish milling cutter. A diameter 25.

The 10 blade of 4mm establish milling cutter to be mixed with the exterior cutting speed of 122m/min 0.

When the bear cutting bits that 076mm/ ages undertakes machining, its feed rate can achieve 1168mm/min. BR&T can be led with speed of this kind of cutting and feed, realize the treatment of groovy essence mill of titanium alloy. Sometimes, they still use 20 blade to establish milling cutter to undertake machining, establishing milling cutter to have a test to a kind of 45 blade. The defect of cutting tool of these much blade finish machining is the function that discharge bits not beautiful, because dimensional stricture is caused between cutting blade,this basically is. To remedy this one flaw, the bear that cut bits must maintain commonly in 0.

076mm/ tine, for the space discharging bits with enough put apart, diameter 25.

The radial of the 10 blade milling cutter of 4mm is cut deep must not exceed 0.

89 - 1.

27mm. Cut as to axial deep, be the problem that 1 criterion of 8 ∶ should solve. Because this criterion is the basis is machined costal region board is as final as its of dimension be close to degree to cut deep amount certainly, accordingly, it is in when deciding sunken tune of milling titanium alloy substantially, the distinction between rough machining and finish machining feed. (1) the definition of 1 criterion of 8 ∶ 1 criterion of 8 ∶ can state for: The biggest axial is cut do not answer greatly the sidewall that is more than adjacent cutting place or costal region board 8 times of odd ply. For example: The requirement machines the sidewall ply of a sunken antrum 1.

27mm. Rough machining obligate enough large mural large surplus, after passing rough machining namely, still have 3.

The mural large size of 18mm. When sidewall machines this ply, feed of milling of place of sidewall of in the vicinity of can be used most greatly the axial of 8 times cuts mural large size to be measured greatly -- namely 25.

4mm. (Boeing company shows, 25.

4mm also is corresponding at in front the biggest axial of mentioned 122m/min cutting rate cuts deep amount. ) along mill of sidewall feed essence, reach final wall large size next 1.

27mm. These feed deepness also can be less than 8 times of odd wall large size. Below this kind of circumstance, the biggest cut deeply 10.

16mm (1.

Of 27mm 8 times) . Use the account of this one fold, it is to avoid to be out of shape the treatment error that cause. BR&T defines a kind of the golden rule that chooses cutting deepness through the experiment, this criterion can unite the sidewall that applies to Boeing aircraft component to may ask and costal region board the whole dimension scope of height and ply. For example, use at checking 8 ∶ the test specimen of two costal region board of 1 criterion effectiveness, among them thicker costal region board ply is achieved 6.

35mm, because this can think, any ply error that measure on workpiece are caused by cutting tool deterioration of ropes. Accordingly, this test specimen was offerred to solve cutting tool metabolic to be affected alone fiducial. Compare to it, according to 8 ∶ 1 criterion, with 6.

The axial of 35mm is cut deep (fold is 8.

35 ∶ 1) milling ply is 0.

The thin costal region of 76mm board when, of cutting tool and workpiece be out of shape cause ply error possibly. But measure a result to make clear, its machine dimension to be not constant stability. Thin to this costal region board for, its total ply deviation is less than itself of cutting tool of prep only by to be out of shape actually the standard deviation that create. The researcher explanation of BR&T says, 8 ∶ should be used when milling titanium alloy of 1 cut deep, because titanium is,be a kind agglutinant very old metal stuff. If will same standard applies at milling aluminium alloy, its fold should be 4 ∶ 1. (2) mean greatly with be down sunken antrum of mill of feed way spirit to be cut with limitation of this kind of means for many times, mill of essence of life is deep when the sidewall of sunken antrum, must use what increase by degrees continuously for many times feed means. This and the means of treatment of sunken antrum wall that use normally have very big different. Normally the circumstance falls, this kind of treatment is finished through taking a knife last time in the full depth of sunken antrum. Sometimes, means of this kind of treatment is thought not only efficiency is taller, and be helpful for improving quality of sunken antrum surface, can eliminate the feed knife mark that forms each between feed because of it. Company of Dan Bo news thinks, these two kinds of views are incorrect. Generally speaking, walk along a knife greatly to undertake milling asks to use very small feed to lead with be being cut completely (25 - 75mm/min) , corresponding metallic purify rate is about 2.

5mm3/min. Compare to it, with 1, the feed of 168mm/min is led, by 8 ∶ of 1 cut deep for many times feed undertakes milling, the metallic excision that can achieve 50mm3/min is led. Although this represented treatment efficiency to raise 20 times, but still be the beginning that improves productivity merely. Supportless sidewall is mixed costal region board connects regular meeting to produce vibration when full depth walks along Dao Xi to cut, because this needs to take a knife through repeating (" float " take a knife) , the rudimental surplus that will keep clear of to fail because of workpiece vibration displacement to excise. As a result of this reason, this kind of vibration often can bring about ply dimension to be controlled hard, and, the Zhen Wen that for purify treatment surface leaves (it and mark of hurtless feed knife is normally different) , must increase handiwork to write grinding work order. 1 treatment means can raise 8 ∶ not only rate of sunken antrum milling, and can avoid these additional process. But, vibration remains a kind of menace. To be in from semifinished product vibration is reduced as far as possible in the treatment course that milling gives sunken speech gradually, should from sidewall or the two side of costal region board are alternant and successive feed milling. Cutting with bigger axial deep after undertaking thick mill takes a knife, cut with lesser axial then deep undertake mill of essence of life takes a knife. In treatment, the odd part of costal region board was not excised material from beginning to end prop up, the workpiece material as these area according to graphic representation order by ordinal excision, costal region board is formed gradually. In fact, this kind of treatment method that has thick mill and mill of essence of life alternately is OK utmost ground is costal region board to offer prop up, in order to reduce vibration. Means of figuration of this kind of costal region board is meant, in each successive cut, cutting tool need not contact costal region board again, because cutting tool has dropped the next cut to sunken antrum. (3) 45 blade establish milling cutter to improve the productivity of sunken antrum of mill of essence of life further, BR&T is having a test all the time, dug is in establish milling cutter circumferential go up to arrange blade of how many cutting likely. A kind of 45 blade establish milling cutter diameter for 50.

8mm, to enhance the cost effectiveness that cutting tool makes, should establish milling cutter to use hollow cutter hub, use an amount in order to reduce hard alloy material. This kind of 45 blade establish milling cutter to be able to be in feed of 120m/min of exterior cutting speed, every tine 0.

When 076mm, use be more than 2, the feed of 540mm/min is led. Nevertheless, still put in a few difficult problem that remain to solve. In this kind the bear that cut bits falls, bigger cutting tool diameter makes diameter jumps the level that error change quantity increases to be accepted hard. How does Boeing firm researcher still make in the experiment design of this kind of cutting tool is provided more practical, so that can apply its at production in. This cutting tool was represented when alloy of finish machining titanium, much cutting blade (45 blade) the treatment speed standard that establishs milling cutter to may be achieved at present. Material of fast purify sunken speech 1 criterion of 8 ∶ is about how be being used much blade establishs milling cutter sunken antrum of alloy of titanium of fast essence mill. And does the thick mill treatment of titanium alloy sunken antrum need what to issue consider? If aircraft component is,become, so, be in OK applying 1 treatment method undertakes 8 ∶ before mill of essence of life, must have thick mill to semifinished product above all, the much work material of place of purify sunken antrum. Full company of coke of gram of hill spy dimension has tool supplier a research group that devotes oneself to treatment of aviation component cutting. This group is being developed hard and evaluate the processing technique of component of structure of plane of alloy of titanium of a few efficient cutting. The researcher of this company expresses, when thick mill is machined, for the workpiece material of sunken antrum of purify titanium alloy, basically have kind of 3 kinds of optional treatment: ① getting is cut and figuration milling; ② is cut with increasing by degrees deep undertake brae milling; ③ getting is cut and insert mill. Generally speaking, in method of these 3 kinds of treatment, efficiency of treatment of the first kind of method is highest, and other two kinds of square law can machine appearance to compare complex sunken speech. (1) get cut and figuration milling machines a method this kind is: Drill the initiative hole that cuts a big diameter in sunken antrum place above all. Keep clear of to facilitate cut bits, the Kong Ying that gets this as far as possible a few bigger, do not be less than at least use at thick mill sunken antrum 1 of the milling cutter diameter of others.

3 or 1.

4 times. Next, will thick milling cutter extends Kong Zhong, but the deepness that extends should be less than hole depth -- the put apart of bottom finish machining that should be sequel about the surplus of 5mm. Milling cutter from outward milling begins in bore beforehand, give sunken antrum depth through successive treatment taking a knife. Nextpage is versed in to titanium alloy the thick mill of a sunken antrum is machined, this kind of material purify rate that machines means is top. Nevertheless, it asks the appearance of sunken antrum is simpler, change a knife to allowing why to need when treatment, the successive of certain part need of sunken perhaps antrum is statified the profile of treatment or feature, do not suit to use method of this kind of treatment. This method still asks craft stability is good, namely sunken pitch should be lower, of cutting tool 4 times what extend length to should not exceed its diameter more dangerous. If be machined sunken antrum is deeper, when perhaps bringing about craft tigidity to be not worth because of other reason, the option is other one of way of two kinds of treatment are possible the effect is better. (2) means of this kind of treatment does not need brae milling and interpolation milling beforehand bore. It needs to use a kind of cutting tool only. This kind of milling cutter walks along means to cut workpiece material with slope, and a material of sunken antrum of interpolation milling purify, next slope goes cut a material. Because cut deep lesser, because this machines a method this kind,suit the machine tool with poorer tigidity most (be like certain the machine tool of 40 taper) . This treatment method can give milling with Yu Dajin, but the milling cutter that uses circular bit is OK bigger cutting parameter undertakes brae milling. To be being brought about because of outline appearance everywhere the sunken antrum with different deepness, method of this kind of treatment is cut than afore-mentioned getting and efficiency of method of treatment of profile modeling milling is taller. (3) auger cut and insert mill method of this kind of treatment can solve a lot of treatment difficult problem. Like the first kind of method, also need to get above all beforehand aperture. Nevertheless, after this machine tool is to undertaking getting cutting operating all the time substantially -- insert milling cutter with or insert auger. To any machining center, z axis has best tigidity normally, accordingly, use this method, can be on the machine tool with poorer tigidity sunken antrum of treatment titanium alloy. Extend length to achieve the deep sunken antrum of above of 4 times diameter to machine to asking cutting tool is dangerous, this kind of method also suits very much. Of course, this kind of method also has a drawback, when inserting mill along sunken antrum contour line namely, take a knife each between hand in fold place can leave profile needle to nod, must give through separate process purify. (4) corner problem methods of afore-mentioned before two kinds of treatment -- get cut and figuration milling, and brae and interpolation milling -- the problem that faces corner jointly. Use right angle to turn to means to come the corner inside treatment, can increase radial to cut greatly deep, may bring about cutting tool to wear away odds of aggravate, damaged increases, or undesirable flutter grain produces in corner office -- the unpredictability that prep let alone still can increase craft, make its realize the automation treatment that unmanned value defends hard. Accordingly, the treatment program that the expert recommends Shanteweikekeleman is not had almost completely need corner. Specifically, milling cutter is not parallel walks along knife milling at sunken antrum wall, however with circular knife course outward milling, till till sunken antrum wall must use linear knife really,course adds man-hour. Use the knife course with circular arc constant radius to be able to make the bear that cut bits and radial are cut deep the biggest change, because be in the each place of course of this kind of corkscrewed yarn knife, action keeps stable from beginning to end at the cutting bear on cutting tool. When milling cutter reachs sunken antrum wall, to get used to the change with knife course sharper direction, the likelihood needs to change feed to lead -- but even if herein, course of milling cutter knife also should use the big diameter circular arc of the corner inside can complete escape. So, the rough machining surplus that is in remain in corner should how Where is purify? The expert suggests to use a kind to call " horn of the Qing Dynasty that chase a layer " treatment method -- the workpiece material that remain handles in corner after 3 kinds of sunken antrum are being narrated to machine one of methods before it also can be used at purify. (5) clear part of layer of contend of the Qing Dynasty that chase a layer is method of a kind of semifinishing machining, it is to use milling cutter of a small diameter, pass course of a series of shorter and shorter circular arc knife, be down mill to give smaller and smaller corner radius, chase the workpiece material of a cleared corner office. Each paragraphs of circular arc is cut on behalf of radial deep very small take a knife. This kind small cut walk along a knife greatly to be able to be used lead relative to taller feed. Nevertheless, be close to corner more and more as milling cutter, radial is cut deep increase gradually, accordingly, feed rate also should be reduced accordingly. Final, give treatment to compare cutting tool radius slightly big corner radius. As a result of " horn of the Qing Dynasty that chase a layer " just be opposite the semifinishing machining of corner, because this returns need,use insert mill and scrape method to have follow-up precision work to corner (see next red-letter days) . Chase a clear part to machine a method to apply to corner of milling right angle not only, and also suit to machine acute angle corner. Just be when corner of milling acute angle, for the additional surplus that cleared rough machining leaves, need undertakes more second chase a layer to take a knife. (6) bottom treatment is when material of sunken speech of purify titanium alloy, the serious problem that still has consideration of a need is the treatment of sunken antrum bottom. With sunken antrum parietal treatment differs, OK and direct milling reachs sunken antrum floor its are final dimension. Although bottom of mill of essence of life needs purify more surplus, but the one part that a lot of job shops still are used to regarding its as finish machining. Treatment expert thinks, when spare parts of aviation of milling titanium alloy, in obligate of sunken antrum bottom 5 - 6.

The surplus of 35mm is a kind of right way. Larger surplus is helpful for supporting action to arriving since very thin bottom, reduce the vibration of the generation in excising workpiece material process. To ensure the stability of cutting, should use from beforehand the helix knife course that bore center expands to outer shroud shape, sunken antrum floor treatment reachs finish machining deepness. Such, have the surplus that has not excise always by what excise surplus providing the function that prop up -- outward all the time treatment arrives to offer the position that support by the sidewall of photograph adjacent, subsequently, will use aforementioned probably 1 criterion of 8 ∶ undertakes to sidewall itself mill of essence of life is machined. The finish machining of corner -- although,insert mill He Qinggen " horn of the Qing Dynasty that chase a layer " treatment but the major work of corner of effective purify sunken antrum material, but how the efficient finish machining of the corner inside implementation, achieve good appearance bright and clean spend and dimension precision, also must give serious consideration. If use the milling cutter with identical sidewall of as sunken as finish machining antrum to have precision work to corner directly, the likelihood satisfies afore-mentioned requirements very hard. When sunken antrum of alloy of titanium of mill of essence of life, must regard corner treatment a completely substantive process, undertake before sidewall of mill of essence of life normally. Because,this is, cut with very small radial deep once the milling cutter that undertakes cutting enters corner office, accumulate with the interface of workpiece (penetration of a cutting tool is measured) can increase significantly, in this one area, although cutting tool is done not have,damage, also may produce flutter and bending. Want alone, surely corner of sunken antrum of alloy of titanium of mill of essence of life, can use method of two kinds of treatment, one kind is slow fast side mill, another kind is to insert mill. These two kinds of methods should use the milling cutter that old long way compares possibly, because this milling cutter cannot is more than inside the formulary radius of corner. Machining a method to these two kinds (the long way that uses milling cutter is compared the biggest achieve 5.

5) after undertaking assessment, boeing company research and technical group (BR&T) decided the corner that inserts mill and union of side mill photograph machines craft finally. The corner that insert mill has the congenital advantage with stabler treatment. Cutting experiment also proved this. Compare with side mill photograph, insert mill to be able to reduce cutting tool bending, marked improvement machines the surface bright and clean degree, in the meantime, can shorten considerably treatment cycle time. Nevertheless, use the part that inserts mill to also its are not worth alone. Keep clear of to be in from corner enough much workpiece material, for the space taking a knife with sufficient put apart of cutting tool of sidewall finish machining, boeing engineer is recommended use a kind to call " insert mill He Qinggen " treatment method, after inserting mill corner namely, through side mill cleared vicinity inserts the redundant workpiece material of mill area. Fall than not be more than the circumstance of 4 in the long way of cutting tool, insert mill and side mill to be able to be used same milling cutter. If grow diameter comparing to be more than 4, can use two kinds of very similar milling cutter respectively only. Should insert milling cutter to insert sunken antrum in when milling, incidental flutter. To overcome this one weakness, the engineer of BR&T is inserting milling cutter to be on each cutting blade preparation a width is about 0.

The arris of 1mm is taken. This arris belt and workpiece material produce clash, its action resembles area of a bearing same, can from go up at all the stability that increases cutting. But the productivity that because similar attrition action can reduce side mill,machines, because this is clear,root treatment need uses alone cutting tool. Actually, besides have the area that do not have arris beyond, use respectively it is OK to insert milling cutter and clear root milling cutter just the same. Only drawback is, these two kinds of milling cutter are very easy mutual and promiscuous, because the arris on edge is taken very see well not easily. Accordingly, the treatment that the workshop that undertakes inserting mill and clear root treatment may be willing to use blade to count different milling cutter to undertake differring respectively more -- just divide these two kinds of cutting tool for can easy area. Insert mill and clear root treatment to still have an advantage: It makes enlarge a size range of pipe bent clear -- compare to use inside corner radius gets much milling cutter to undertake sidewall finish machining vacates a space greatly -- become a possibility. Probably 45 blade establish aforementioned of no less than milling cutter had better make clear in that way, the milling cutter with bigger diameter can hold more cutting blade, can undertake with higher feed rate mill of essence of life is machined thereby. With this kind of means, in the workpiece material that corner office keeps clear of first before sidewall of sunken antrum of mill of essence of life, can improve the productivity of whole finish machining finally greatly. Consider whole finished cost and not be cutting tool cost only when machining spare parts of titanium alloy aircraft, besides should consider cutting tool way beyond, still need to consider another serious problem -- choice cutting tool is affected to machining socioeconomic. Boeing company research and technical group (BR&T) researcher expresses, the cutting tool with the cheapest price may be -- but also may not be -- the option plan of finished cost lowest. For example, because high-speed steel cutting tool has good anti-impact properties, often be used at the treatment of titanium alloy. The metallic purify rate of high-speed steel cutting tool achieves as optimal as typical hard alloy cutting tool purify to lead the level that comparative likely. Below this kind of circumstance, cheaper high-speed steel cutting tool can offer better treatment economy. However, a lot of job shops have latent capacity to raise the cutting rate of milling titanium alloy considerably on existing level. Job shops can pass the cutting tool with use property better (be like 10 blade or hard alloy establishs 20 blade milling cutter) , improve treatment beneficial result significantly. The general overhead expenses that because raise workpiece to machine speed to be able to drop share,goes up to every workpiece, because of this productivity rise to be able to offset very easily increasing cutting tool cost -- although this kind of cutting tool is quite costly. This is meant, come according to cutting tool price merely cutting tool of choose and buy, the likelihood can not achieve the goal that reduces cost. Although cutting tool is complete free, total finished cost is potential also taller, because the function of cutting tool itself is met,restrict those who machine function to rise. For example, mix with milling cutter of 6 blade high-speed steel 4 blade hard alloy milling cutter leads alloy of titanium of mill of essence of life with identical metallic purify when costal region board, every square of the high-speed steel cutting tool with lower price inch finished cost is inferior also (when finish machining, the area that uses treatment will measure finished cost relatively appropriate; When rough machining, the bulk that should use excision data will measure finished cost) . However, when with 10 blade hard alloy milling cutter undertakes machining, the circumstance has very big different, because metallic purify rate rises considerably, although cutting tool price is more expensive, but treatment totle drilling cost drops significantly instead. The likelihood is put in very big difference between the price of cutting tool and value. Accordingly, important is not to compare cutting tool cost, compare finished cost however, otherwise, job shops is met probably to save cutting tool cost wrong choice already slow machine means expensively again. To choose the treatment way with better cost effectiveness, when Boeing company is machining spare parts of titanium alloy aviation, the formula below in order to will compare rough machining (will measure with bulk purify rate) or finish machining (will measure with area purify rate) cost: Every are cubic (or square) inch in type of finished cost =(TC/TL+Rm/60+RLT/60TL)/MRR: T is the time that change a knife (minute) , TC is cutting tool cost (dollar) , TL is cutting tool life (minute) , rm is led for machine tool cost (dollar / hour) , RL is led for labor cost (dollar / hour) , MRR is led for metallic purify (cubic metre or square inch / minute) . CNC Milling