The CNC Machining method that is based on feature of model of aviation structural member is optimized discuss

Means of knife of advance and retreat. Groovy antrum treatment basically uses linear, broken line and helix means of 3 kinds of feed, retreat a knife to basically be used retreat a knife with circular arc point-blank 2 kinds of means. In choosing feed way, angle leaving a sword is influence cutting smooth stability (the change effect that gets cutting force and its way is bigger) the main factor that reachs treatment efficiency, the cutting when instantly knife angle is lesser is smooth but cutting efficiency is low, efficiency of the cutting when point of view leaving a sword is older rises, but cutting force increases, cutting position becomes poor. Below Production Module platform, use different point of view leaving a sword to undertake emulation to cutting force, if the graph is shown 1 times, because feed cutting process is medium,component of force of direction of X, Y suffers the effect of knife contrail azimuth, reflective workpiece gets power metabolic trend is not remarkable, because this experiment is analysed,basically be opposite in the process axial component of force (graph 1 in FZ) undertakes an analysis. Its emulate a condition to be: φ 20mm establishs milling cutter (cutting tool helix angle is 30 ° ) cutting material is aluminium alloy material 7050; Rotate speed 20000r/min, issue knife speed 2000mm/min, orbit area is diameter of 2 times cutting tool. The graph is shown 1 times, feed of 50% discount line and knife of snail screw off undertake cutting force contrast is analysed, angle leaving a sword is when 10 ° less than force of helix feed cutting relatively broken line feed is small (contrast undertakes with axial component of force in the graph, join forces case is similar) , and at present the control system such as Xi Menzi supports helix interpolation, treatment process is successive, did not suffer force mutation, relatively broken line feed is more stable. Undertook emulation to perpendicular feed in experimental process, below same condition FZ of its axial component of force is 292N, be more than other far 2 kinds of means. Comparative means of afore-mentioned a few kinds of feed are knowable, the feed way that cuts angle certainly compares perpendicular feed means to want to the influence of cutting tool load to the influence of cutting tool load a lot of smaller. Below condition of same point of view leaving a sword, load of axial of the milling cutter when helix feed is the smallest, machining the sensitive to axial load spare parts such as Bao Bi so, should feed of first choice helix; Close to what interior has enough space taking a knife housing, means of feed of first choice helix; Long to narrow space can choose broken line feed; And can be in when groovy antrum is mouth chamfer antrum the spare parts is exterior feed, or the spare parts already got feed aperture case beforehand, can choose perpendicular feed, its efficiency is taller. Basically make sure when retreating a knife cutting tool is gently leave workpiece to produce knife trace with preventing to already machining the surface, the influence machines exterior quality. B.

Take knife kind. To taking the analysis of knife means, the uniformity that basically considers mental allowance reachs the height that machines efficiency. Current, in aviation structural member groovy antrum is machined in, use most is annulus cut and cut all right add 1 quoit to cut (cleared travel cuts remain) 2 kinds of means taking a knife. To analyse the efficiency of two kinds of means taking a knife well and truly, the characteristic parameter such as decelerate is added in mature machine tool handling time was developed to emulate software on the foundation, to take groovy antrum cent islands is mixed do not take islands 2 kinds of typical situations undertake emulation an analysis. If the watch is shown 1 times,Nextpage emulates a result, to having islands chamfer antrum, the efficiency of 2 kinds of means comparatives roughly, but use when groovy pitch is bigger cut the means efficiency that increases 1 quoit to cut all right taller, use directly in space opening open cut means to machine efficiency all right taller; To taking islands chamfer pitch, when groovy antrum structure is lesser, cut all right add annulus to cut means efficiency taller, but when groovy antrum dimension increases, 2 person difference is progressively and narrow. Accordingly, below better in spare parts tigidity case, use cut all right add annulus to cut means overall efficiency taller. (2) muscle machines an analysis. The treatment of muscle points to muscle reach an edge the treatment of end face, the position that shares cutting basically is round corner of cutting tool floor, its cutting condition is similar to Duan Xi. And the cent that carry mill goes against mill, asymmetry to arrange mill for symmetrical mill, asymmetry means of 3 kinds of milling, place choosing means is unreasonable can make machine vibration to increase, produce phenomenon of tine of cutting tool collapse even, bring quality hidden trouble to the product. Emulate compare pattern of 3 kinds of milling, the design goes out " one " glyph muscle, muscle width is 3mm, length is 200mm, muscle highest height is 40mm, design flat-roofed muscle and muscle of 3 kinds of when take proper point of view inclined tops, all go against mill, asymmetry to arrange mill by symmetrical mill, asymmetry treatment of 3 kinds of means, use Production Module platform to undertake emulation (emulation condition ibid narrates consistent) , emulation result is shown 2 times like the graph. Be analysed according to afore-mentioned emulation and test and verify of combinative cutting experiment is knowable, treatment muscle ought to be in very muscle tigidity undertakes below better case, avoid to use symmetrical milling means; Flat-roofed thin muscle treatment should use asymmetry to go against mill as far as possible; In muscle supporting to machine a process with music in inclined top, preferential choose asymmetry to arrange mill, when muscle should choose to fall oneself when gradient is bigger up milling. (3) outline machines an analysis. Outline feature uses means of side mill storied to undertake machining commonly, it is Bao Bi more as a result of aviation structural member, because of this feed process must appropriate consideration, force of the cutting in contacting a process causes vibration easily greatly too and leave exterior grain. If the graph is shown 3 times, commonly used to outline treatment circular arc feed undertakes emulation an analysis knowable, radius of feed circular arc is smaller, change of the curvature in contacting a process is bigger, cutting power is greater, bigger to influence of quality of surface of spare parts sidewall, but circular arc radius crosses congress to bring about cutter track diameter to grow too, choose normally (0.

3 ～ 0.

5) × D (D is cutting tool diameter) circular arc radius. A few kinds of typical difficult treatment child it is important that treatment technique discusses the feature to be decreased to satisfy a plane beg, aviation structural member uses thin wall structure in great quantities, rate of purify of the material in machining a process is very high (exceed 90%) normally, for part of typical weak tigidity, complex structure. Afore-mentioned characteristics of aviation structural member make its CNC Machining relatively difficult: Corner radius normally lesser, long way of use cutting tool of finish machining place is older, cutting condition is poor; Thin wall place arises easily in machining a process be out of shape reach flutter, dimension precision and exterior quality are hard to assure. What the difficult treatment place such as corner, Bao Bi serves as model of aviation structural member to machine a feature is accessary and characteristic, must get more thorough research, find out reasonable solution, in order to improve the treatment quality of typical treatment feature and efficiency. Craft of 1 corner treatment is optimized (1) corner machines an analysis. In treatment of aviation structural member, inevitably meeting encounters the treatment of corner area, when if be in turning point,using linear contrail, the cutting arc length of milling cutter produced mutation, and every tine is average milling force and cutting arc length are relevant. Accordingly, average milling force also produced mutation in turning point. Right now, milling cutter center is located in the position of acme of trochoid pointed horn, the milling force of instantaneous from the biggest drop to the smallest, but the instant falls again to the average milling force before corner milling. In machining a process actually, to avoid the mutation of feed direction, use circular arc to transfer in turning point normally the means that machines trochoid undertakes machining. Change of arc length of milling cutter cutting should be less than the means that pointed horn machines, the change of force of average mill cutting also alleviates a lot of. Accordingly, through changing trochoid to be able to alleviate greatly corner is in the milling force impact to cutting tool and workpiece. Pass afore-mentioned analysises knowable, the contrail taking a knife that changes turning point can improve the cutting position that corner machines effectively. From this domestic and international scholar did a large number of theory and experimental research, sum up and excogitate a few effective treatment methods, common corner treatment strategy leans knife way somewhat, leave surplus to cut a way all right, refine round part way, Chan Yuan method of treatment of annulus treatment method, double cirque, these corner treatment optimized a method to improve the quality that corner machines and efficiency on certain level, but when cutting tool long way is older (exceed 5 ∶ commonly 1) , afore-mentioned methods cannot from go up at all the quality that solves corner treatment and efficiency problem. (2) the treatment inserting mill of corner. Insert mill (Plungemilling) calls Z axis milling again, direction of main shaft of edge of the cutting tool in machining a process does feed exercise, the cutting blade that uses bottom undertakes getting, mill combines cutting. Because insert mill treatment to become radial,feed is axial feed, reduced the radial cutting force of cutting tool substantially thereby, what can hold cutting force bulk is stable, reduce what the workpiece in treatment reachs cutting tool to be out of shape thereby, avoid the generation of cutting flutter, have important sense to corner and deep antrum treatment. Current, partial aviation makes an enterprise had introduced the technique that insert mill, the treatment inserting mill of corner has before spare parts finish machining, on one hand from go up at all solve corner to machine difficult problem, still can improve efficiency of finish machining of aviation structural member greatly on the other hand. It is easy in machining a process that craft of treatment of 2 thin walls optimizes thin wall place generation is out of shape reach flutter, treatment quality is hard to assure, domestic and international scholar is reached according to structure of different spare parts be out of shape the element offerred a variety of technique, the parallel double main shaft that like Japanese cliff ministry the person such as foreign Yo puts forward machines a method, the person such as Japanese HarukiOBARA put forward alloy of low melting point to assist cutting program, j.

Tlusty, s.

The person such as Smith put forward to make full use of the cutting treatment program of tigidity of spare parts whole. Undertake thorough analysis to machine a process to Bao Bi, design " day " work of Bao Bi construction regards glyph aluminium alloy as experimental object, workpiece grows 360mm, wide 250mm, tall 30mm, everywhere the wall is large all be 1mm. Use traditional pattern to undertake machining above all, in rough machining process periphery and bottom all stay have 3mm surplus, the predestined relationship in finish machining process flank produces apparent Zhen Wen, although reduce cutting,parameter also cannot avoid completely. Nextpage is machining an experiment what use mill of platform trap door on AEROSTAR machine tool, undertake to milling cutter of hard alloy of φ 20mm whole hammer attacks a test, get below the circumstance that takes no account of workpiece tigidity flutter stabilizes region curve, if pursue,4 are shown. Again according to workpiece finite yuan of emulation result, the position with choice workpiece the weakest tigidity (each muscle reach an edge stand by intermediate coping) undertake hammer attacks a test, obtain its kinetic character, with " machine tool - cutting tool " if the flutter stability region that union of kinetic characteristic photograph gets losing rigid circumstance falls pursues show 5 times (consideration workpiece trends is characteristic) , with the graph 4 contrast, stable region takes a cost very low, very incidental flutter. Change original treatment method, the basis is based on " machine tool - cutting tool " stable region curve and cutting force emulate flutter of calculative of systematic trends character to be optimized as a result choose more efficient cutting parameter (cut wide Ae=20mm; Cut deep Ap=4mm; Feed speed F=10000mm/min; N=21000r/min of main shaft rotate speed) hind, use " the layer is first " means treatment. When using this method to be able to make sure cutting tool machines Bao Bi every time, all be opposite root ministry of Bao Bi undertakes machining, can regard cutting tool to be stimulated to the root place buy of workpiece only brace up, form right now " machine tool - cutting tool - workpiece " the place of workpiece bureau place that the system can inspect cutting tool basically to contact is rigid system, realize the efficient treatment that does not have flutter thereby, treatment surface quality gets clear improvement. Be based on afore-mentioned principles, the treatment method that maintains tigidity of milling course machining complex still can popularize other a few means, as usual sees " mill of a flight of stairs " , " wrong layer mill " wait, the essence of these methods depends on making in machining a process, be machined area has enough tigidity, in order to avoid treatment flutter and metabolic generation. The project uses the research that content narrates before test and verify is passed, normative the treatment technique of typical feature, put forward corner, Bao Bi to wait for solution of CNC Machining of difficult treatment place, union wove into flying company actual condition standard, produce actually in order to coach, the typical aviation such as the connect that chooses subcontract project, wainscot narrated research content to undertake applied test and verify before structural member is right. Craft of spare parts of 1 connect deep antrum optimizes contact kind the spare parts is join main bear the join of force component, distributing on the spare parts have assemble datum plane and nodical aperture to wait, configuration demand of complex, precision is high, among them narrow treatment of structure of groovy deep antrum is very difficult. Be like a typical Boeing 787 metals joint, dimension of part semifinished product is 140mm of × of 450mm × 160mm, groovy antrum is deeper, because of cutting tool tigidity is not worth and generation vibration brings about a spare parts to machine breakdown constantly, bring serious quality hidden trouble to the product. (1) technique is optimized. Antrum of chamfer of this spare parts makes an appointment with 100mm greatly, corner radius 7mm, long way of place use cutting tool compares more than 7 ∶ 1, for structure of model deep antrum. Grow diameter comparing to be more than when cutting tool 4 when, the cutting position of cutting tool drops quickly, to improve cutting position, in the project actual in take the kind that reduces cutting parameter normally, but this kind of means not only reduce a spare parts to machine efficiency significantly, and the corner treatment quality of the spare parts still cannot get assuring effectively. Improve original technique, undertake to corner before finish machining mill is machined inserting, the corner surplus after the course inserts mill is very small, when finish machining cut deep can raise 4 times more greatly than relying on to cut means treatment, avoided broach appearance. (2) optimize a result. Boeing spare parts of 787 metals joint in all 12, machine a spare parts in all since formal put into production more than 200, malfunction among them spare parts 17, fault rate is as high as 8% ; Optimize through craft, put into production more than 100, breakdown spare parts only 1, fault rate is reduced to 1% less than, at the same time treatment efficiency rises 23% . 2 wainscot kind the spare parts optimizes wainscot integratedly kind the spare parts is long, wide directional structure size is larger, ply direction size is lesser, for part of typical thin wall construction, extremely easy generation is out of shape in treatment. The sky that is like a model wainscot of plane annulus cabin, dimension of part semifinished product is × 60mm of 2800mm × 1200mm, wainscot and muscle the smallest part only 1.

5mm, material purify rate is achieved 96% . Because this type spare parts finalizes the design earlier, cutting parameter and contrail taking a knife is unreasonable, all cannot satisfy actual production requirement on quality and efficiency, be badly in need of getting optimizing. (1) technique is optimized. Be aimed at the treatment problem of afore-mentioned existence, the treatment method that research conclusion narrates to just basically face wainscot from 3 before union undertakes optimizing. A.

Technology program is optimized. Optimize muscle to carry treatment means on the head: To muscle top means taking a knife undertakes optimizing choosing; Use the technology that insert mill: Area of deep to the part chamfer uses the treatment that insert mill; Precision aperture is used in great quantities get reamer; Elliptically appearance rough machining. B.

Cutting parameter is optimized. Combinative DynaCut kinetic test analyses system and SimuCut to emulate a system, use the Bao Bi that maintains tigidity of milling course machining complex to machine a method to optimize cutting parameter in the round. C.

Orbit is optimized. Through adjusting milling row spacing in order to simplify orbit amount, decrease carry knife frequency and optimize orbit to reduce a machine tool to add decelerate. (2) optimize a result. Those who pass parameter of technology program, cutting and treatment contrail is comprehensive optimize, use spot DNC system to dog machine of test and verify annulus left wainscot machines cabin whole process, machine tool cutting is smooth (dynamic balancing value is less than 1.

7) , power is stable (40% ～ 60% ) , torque is lesser (be less than 9N · M) , all programs press 100% treatment, unmanned labour to intervene. If the watch is shown 2 times, spare parts whole machines efficiency to get promoting considerably, benchwork burnish quantity decreases considerably, achieved those who anticipate to optimize the effect. Last word the article sets out from the characteristic of aviation structural member, union emulates the treatment method that reachs an experiment to analyse typical to the part feature to undertake optimizing discussing, undertook a project turn application, obtained favorable result. But the content numerous and complicated that institute of method of CNC Machining of aviation structural member involves is complex, still need to develop thorough research further in the respect such as fundamental theory and project application. CNC Milling CNC Machining