The interference examination of integral impeller CNC Machining and knife amend

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Summary: Develop software of impeller CNC MachiningCAD/CAM independently to come true, put forward interference to examine reach a knife correction algorithm. The opposite place that knows cutting tool of beyond the mark analyse and impeller curved surface affects, interference cent is 3 sort model. In the light of different interference the type offerred corresponding examination and long square way. Give out finally emulation example with test and verify this algorithmic effectiveness. 1 foreword impeller is the crucial part of turbine machinery, its CNC Machining is the focus of research all the time. Because at present home returns what did not mature quite and the CAD/CAM system with strong adaptability, accordingly, the software that great majority produces the manufacturer of impeller to return support to be imported from abroad will finish its are much coordinate CNC Machining. Entrance software not only the price is high, want to spend much foreign currency, and software is the moving module that close, its difficulty and the technical data of a few crucial questions are obtained very hard, accordingly, cannot undertake revise and be developinged according to actual condition, serious obstacle the development of new product. In recent years the rapid development as industry of aviation of mechanical, spaceflight, to raising impeller kind the machines quality and precision respect requirement of the spare parts heals increase is impending, the CAD/CAM software with own development is imperative, the research that had this side for this a lot of researcher works, but the institute that examines this decisive issue to the interference in CNC Machining sees the data is very little. The doctor's degree paper that work of Beijing aerospace college learns Wu Ming " impeller, lamina kind design of spare parts geometry and CNC Machining " use disperse triangle piece the method undertook interfering an analysis, computational amount is larger, and research is not comprehensive, did not make an analysis to the interference between photograph adjacent lamina and cutting tool. In the CNC Machining process of integral impeller, the working space of cutting tool gets the rigid limitation of impeller structure, freer than treatment curved surface wants interference appearance many complex. The article is aimed at the characteristic of integral impeller, on the foundation that interferes a type in the analysis, put forward an interference that applies to much coordinate CNC Machining to check a method. Impeller of whole of 2 interference type is to show hub and lamina are on matrix of a semifinished product. When machining impeller blades curved surface, besides cutting tool and be machined outside interference happening between blade, because the space between photograph adjacent lamina is lesser, cutting tool produces interference extremely easily with photograph adjacent lamina. In be machined actually, blade curved surface is to use the way that coordinate chooses to give out, computational knife when need to have curved surface disperse changes processing. Because use milling cutter of ball head taper commonly, accordingly, can become curved surface disperse bit of kind. Every information of the dot will give out with structural form, the arrow of unit appearance law that the coordinate that includes permutation serial number, feature, place nods, the kind that expresses with individual catenary between the dot gives out. The interference that article place discusses is to point to gnaw cut interference, namely cutting tool cuts the share that should retain on curved surface. In machining blade with milling cutter, the cuts plane to go up position that contacts cutting tool park bit of place curved surface serves as the initiative position of cutting tool. If the graph is shown 1 times,machine the circumstance of integral impeller for milling cutter. The angle that concerns from the relative position between cutting tool and each lamina curved surface considers, can be interference cent 3 sort model: The first kind carries the interference between on the head for milling cutter and oneself lamina leaf: The 2nd kind carries the interference between on the head for milling cutter and leaf of photograph adjacent lamina: The 3rd kind is vicinity nods the interference between all round milling cutter and region of the work area that be added. If passed the interference of these 3 kinds of types to check, need not need the dot of pair of whole lamina curved surface undertakes interfering test and verify, reduce computational amount greatly thereby. 1.

Hub 2.

Blade 3.

Cutting tool pursues 1 whole impeller machines a circumstance 3 interference examination and knife adjust 1) cutting tool and oneself lamina S(u can be used after the interference impeller curved surface between Xie Ding uses NURBS method disperse, v)={x(u, v) , y(u, v) , z(u, v)} will express, u ∈ (0, 1) , v ∈ (0, 1) . Accordingly, that parameter on-line that this kind of interference needs to judge leaf of blade curved surface to carry a corresponding V=0 on the head only nods the distance E between cutting tool axes each, if pursue,2 are shown. If be apart from the effective radius that is more than cutting tool, do not produce interference: If be apart from the effective radius that is less than cutting tool, produce interference. So called cutting tool has effect radius, those who point to is the cutting tool radius that is in relative to Yuxieding. In be apart from E to be type, a(x0, y0, z0) nods coordinate for the ball heart of cutting tool: B(x1, y1, z1) carries parameter on the head to nod coordinate for blade leaf: (Ax, ay, az) is the 3 coordinate heft of A of vector of unit cutter shaft. Cutting tool has effect radius to be R0= R0+ | AB | In Cosqtanb (2) type: R0 is radius of head of cutting tool ball: B is the half cone angle of cutting tool: Cosq=ABa/ | AB | . The interferes circumstance of this sort interference judgement between 2) cutting tool and top of leaf of photograph adjacent lamina and the first kind of judgement that interfere a circumstance are similar. The parameter curve that leaf of photograph adjacent lamina carries on the head can be passed will be machined the Xie Ding parameter of blade burns suitable hour hand or anticlockwise corner coming back spends α (α =360m, m is counted for blade) get. The interference between adjacent dot is theoretic all round 3) cutting tool and region of the work area that be added, the interference of this kind of type should detect the existence sex of taper seat of cutting tool place and the point of intersection that cutting tool covers the curved surface inside area, but such calculation are more complex, computational amount is larger also. For handy for the purpose of, use the following algorithm. If the graph is shown 2 times, make cutting tool cut plane, those who make it is cutting tool with the angle of cut between vector of cutting tool axes half cone angle, get two cut planar F1, F2, choose a planar F1 that contacts with blade face posture among them, beg what the disperse that this plane and cutting tool enclothe nods to have to distance D, judge the symbol of D, can judge cutting tool to whether produce interference with blade curved surface. Graph the 3rd kind of 2 interference detect the N1(A of unit law arrow that makes planar F1, b, c) can be passed circle A of cutter shaft vector (A × N) rotates (90 ° - β ) angle gets, namely N1= Cos(90 ° - B)a+ Sin(90 ° - the equation of F1 of B)n criterion plane is the random on curved surface of lamina of Ax+ By+ Cz= 1 (4) a bit (Xs, ys, zs) has to what cut plane to distance D but by type (5) gets D= Axs+ Bys+ Czs-1 to adopt computational form (the mark that 5) can get D. If D is the same as date, and be more than 0, did not produce interference: Be like D surprise bugle call, produce interference, d<0 is interference dot. To reduce computational amount further, before having afore-mentioned consideration, advanced travel is thick sentence. Thick sentenced purpose is to find out blade curved surface and cutting tool between cover area. In cover area inside, just produce interference likely. Because had passed the interference of the first kind of type to check, when we are being calculated, will enclothe area to be reduced further again. Mix cutting tool be machined blade curved surface is umbriferous go up at Xoz plane. Grow tectonic cutting tool for the edge with diameter of head of cutting tool ball include square, part with blade curved surface the biggest be worth tectonic lamina curved surface with value of the smallest X, Z include rectangle, if pursue,3 are shown. Concern through observing the relative position between square and rectangle, whether does the dot on curved surface of OK and affirmatory lamina need further examination. 4) knife adjust interfere through afore-mentioned methodological check fish, must undertake adjustment to cutting tool cutter shaft. To the 3rd kind interference undertakes elimination below. According to type (5) , can find out distance of the biggest interference to be Max | D | = Max | Axs+ Bys+ Czs- 1 | To remove interference, cutting tool should be in initiative cut dot of heart of cutting tool ball is circled to rotate inside plane Q angle, make cutter shaft more the blade curved surface that deviate is machined. Q horn is Q= Arcsin(max | D | / the D1 in D1) type nods the distance between for dot of the biggest interference and heart of cutting tool ball. The cutter shaft vector after such adjustment is the type on Anew=acosq ± Nsinq in, if Q horn is circled (roll of suitable hour hand of A × N) is taken " + " date, anticlockwise rotate take " - " date. The first kind of interference and the 3rd kind of adjustment of interference the method is same, should make cutter shaft more deviate curved surface. And if be the 2nd kind of interference, should make cutter shaft nears curved surface. After cutter shaft angle is adjusted, want to check interference afresh, until do not produce interference till. Graph the interference that afore-mentioned putting forward checks 4 interference emulation example law, already was used at us to develop " software of special impeller CAD/CAM " in the system. Graph 4 it is two emulation example. The knife in graph 4a it is to carry a sword computation gets, deep color expresses to interfere area. Graph 4b is the knife after using afore-mentioned algorithm to remove interference. CNC Milling