Integral impeller (see a picture 1) the crucial part that is aviation engine, rise as what engine function asks, the appearance of integral impeller and structure are more and more complex, main feature is blade thin, screwy interval of big, lamina is small, this brought very great difficulty to the production of integral impeller. Graph treatment of milling of 5 coordinate numerical control has 1 whole impeller to wait for an advantage flexibly, efficiently, accurately, already became integral impeller to machine one of commonly used methods. Use center of 5 coordinate CNC Machining to make integral vane wheel, machining process designing is one of its key technologies. The main task that machines process designing is to decide the relative position of cutting tool and workpiece and opposite motion, generate contrail of CNC Machining cutting tool, with the motion of drive machining center, finish automatic cutting. Below the premise that makes sure integral impeller produces quality, efficiency is very main index. It is the cutting cent of integral impeller rough machining and finish machining commonly: The main task of rough machining is to be in as far as possible the purify inside short time as far as possible much material; In finish machining, want production to give the eligible product that accords with precision requirement already, ask cutting efficiency is tall again. The article from raise treatment efficiency to set out, the contrail of rough machining cutting tool that discussed to face the kind that insert mill respectively generates algorithm and the contrail of finish machining cutting tool that are based on bosomy form cutting tool to generate algorithm. Integral impeller inserts technology of process designing of mill rough machining the 1 treatment that insert mill inserts mill treatment, call Z axis milling the law again, it is to point to feed of direction of cutter shaft of cutting tool edge, the cutting blade that uses cutting tool end panel undertakes getting, mill combines cutting. With the treatment such as side mill means photograph is compared, the radial cutting force of cutting tool of the treatment that insert mill is reduced greatly, can reduce cutting tool vibration thereby. Use the treatment that insert mill, in other condition same situation falls, can increase cutting amount, improve treatment efficiency thereby. Current, UG, CATIA already had 3 axes to insert mill to machine process designing module, and to complex integral impeller, need 5 coordinate CNC Machining to come true. Integral impeller has a structure difference of complex, sex opening open, passageway is deep wait for a characteristic, need to undertake blade crankle is spent above all, passageway width and deepness the analysis that wait, in order to decide cutting tool parameter. Spend the impeller with big, poor sex opening open to crankle, cannot install clip to machine Xie Gen part partly from the Xie Jian of the passageway through, need holds clip for many times, from into exhaust edge bilateral the butt joint is machined [2] . Because area of the 2 rough machining that insert mill inserts mill to machine along cutting tool axial linear feed, accordingly its machine attrib border face to be straight grain face, and blade face is free curved surface commonly. To generate contrail of cutting tool of the treatment that insert mill, need to approach blade range with straight grain face above all. The space of cutter shaft is swept sweep past a face to be workpiece curved surface (straight grain face) slant buy side, considering take superabundant land, slant buy distance set is " cutting tool radius + mental allowance " . Blade slants the process seeking solution of face of sth resembling a net of bag of buy straight grain is as follows: (1) the lamina that seek solution slants the N+1 of buy side wait for C of U parameter line (Ui, v) (I=0, 1, ... , n) , if pursue 2 (A) be shown. (2) the straight generatrix of bag sth resembling a net of the parameter line such as computation. Straight generatrix of bag sth resembling a net begs solution to want to satisfy: Straight generatrix is including a side of subsidiary channels in the human body through which vital energy completely, namely the inside of flow path of adjacent of blade face posture, in order to assure mental allowance, avoid to had happened to cut interfere with cutting tool; Apex and Xie Gen mental allowance as far as possible even. Document uses principle of the smallest area to beg straight generatrix of the sth resembling a net that see a package, if pursue 2 (B) midpoint underlines place to show, rate of purify of material of this kind of method is old, but may make apex part mental allowance compares more of foliaceous root part, reduce the stiffness of the lamina when treatment. Another kind of method is to be based on the mental allowance such as Xie Jian and Xie Gen to beg straight generatrix of the sth resembling a net that see a package, if pursue 2 (B) medium solid line place is shown, the mental allowance of put apart of this kind of method is bigger. As to choose which kinds of method, the appearance that should look blade scale and calm. (3) serve as in order to wrap 2 end points of straight generatrix of subsidiary channels in the human body through which vital energy model value drop, turn over cipher out the control of same amount is apical. (4) with accumulate chord parameter law to beg a node vector, beg solution to give straight grain to wrap R = R(u of face of subsidiary channels in the human body through which vital energy then, v) . If the graph is shown 3 times, radial of impeller of edge of line of midday of impeller leaf the best of its kind a paragraph of safety is apart from outward translation, wind a week of impeller axes circumgyrate next, get circumgyrate face T, regard treatment as the end face of area; Slant radial of impeller of hub face edge outwards buy gets H, regard treatment as the underside of area. The dimensional area that the foliaceous basin of H of end face T, underside and lamina, leaf carries straight grain on the back to wrap place of Rp of face of subsidiary channels in the human body through which vital energy, Rb to decide, it is area of the rough machining that insert mill namely, if pursue,3 are shown. If the graph is shown 4 times,contrail of cutting tool of the 3 rough machining that insert mill is generated, foliaceous basin slants with what the leaf carries on the back of Rp of face of sth resembling a net of bag of buy straight grain, Rb and end face T intersect the line is C1 respectively (U) , C2 (U) with underside H intersect the line is C3 respectively (U) , C4 (U) . Consider pace of the treatment that insert mill long according to rudimental altimeter, solution gets C3 (U) all knives on boundary boundary line dot T3_i (I=1, 2, ... , n) . Cross T3 I to make perpendicular Yu Xie annulus the planar Pi of axial, pi hands in C1 respectively (U) at nodding T1_i, hand in C2 (U) at nodding T2_i, hand in C4 (U) at nodding T4_i. Join knife the straight bus bar that T1iT → 3 I and T2iT → 4 I make straight grain include range of subsidiary channels in the human body through which vital energy approximately, criterion 4 I of → of T1iT → 3 I, T2iT, it is Xie Penhe respectively the inserting that the leaf carries attrib border face on the back direction of milling cutter axis, namely vector of cutter shaft of attrib border face, if pursue,5 are shown. Nextpage is inside planar Ri, according to vector of cutter shaft of interface of edge of row spacing interpolation, get J I of → of MjiN of vector of flow path cutter shaft, the vector of all cutter shaft that comes out computation presses certain means join to rise, it is the contrail of cutting tool of the treatment that insert mill of a flow path namely. The contrail of cutting tool of the treatment that insert mill of all flow path can get through array. The finish machining of impeller of whole of technology of process designing of integral impeller finish machining, want to make sure contented precision asks already, want to improve treatment efficiency as far as possible again. Raise treatment efficiency to be able to come true through optimizing treatment contrail, there is a lot of in the research of this respect, some methods are based on wait for rudimental height criterion, avoid contrail of redundant cutting tool; Some from decrease transfer proceed with of length of cutting tool contrail; Some studies what arrange cutting tool contrail solely to generate, in order to assure higher feed rate. On the other hand, also can choose cutting tool parameter to improve treatment efficiency through actor. Among them, using bosomy form cutting tool is a kind of effective method. The rouses parameter of form knife geometry certainly certainly principle of parameter of geometry of knife of 1 beat form is: Curved surface of bosomy form knife and lamina is tangent when touching, put in an attitude at least, make bosomy form knife and curved surface of integral impeller blades do not produce local interference. If the graph is shown 6 times, body of beat of bosomy form knife is the largest rotate radius is R, the curvature radius that rouses form knife generatrix is Re, length of axial of edge of bosomy form knife is Le. Set bosomy form knife and curved surface of integral impeller blades to be cut in P dot touch, the unit magic art that Nc chooses in P for blade curved surface is measured to arrow. 2 when set blade curved surface to be in correspondence in P advocate the unit vector of curvature direction is E1 and E2, blade curved surface is nodded in P with R of form of arc length parameter (B, f) express, (E1, e2, nc) forming the local coordinate that cuts contact P part is. center of bosomy form knife Tc fixed position is in Nc of arrow of edge unit law, with P the dot is apart from those who be R to slant on buy point; Setting K1 and K2 is blade curved surface respectively 2 of E2 direction are mixed along E1 direction in P point point advocate curvature, inside the local coordinate department that manages in P, by differential geometry, the P dot office of rouse form knife face is local 2 rank it is NT = 0 approximately. 5 (Ke B2 + Kc F 2) , among them Ke=1/Re, kc=1/R, the curvature that is generatrix of bosomy form knife respectively and the biggest rotate the smallest radial curvature of radius correspondence. Be nodded to be in in P by treatment curved surface local 2 rank it is Ns = 0 approximately.
5 (K1 B2 + K2 F 2) , the 1 K in type, 2 K parts to be in P point point for blade curved surface advocate curvature. The standard that sets H to be apart from blade curved surface to rouse face of form cutting tool to height, namely H = NT - NS=0.
5[(Ke-k1) B2+ (Kc-k2) F 2] . If rouse curved surface of form knife and lamina not to produce interference, need to satisfy pair of random (B, f) have H ≥ 0, ask namely Ke>k1, and Kc>k2. Interference differentiate algorithm is as follows: Become the disperse of blade curved surface of integral impeller above all enough much disperse nods {Pi} , i=1, 2, ... , n, undertook an analysis to random again, those who divide curved surface of separate out lamina is the biggest with {k1i} of the smallest curvature and {k2i} , set K1=max{k1i} and K2=max{k2i} , want K1 of Kc ≥ only and Kc>K2, the scarcely when the bosomy form knife that is geometrical parameter with this machines blade curved surface can generate local interference. The law of unripe set prescription of contrail of cutting tool of program of program of contact of knife of treatment of knife of 2 beat form is based on wait for parameter line to change the pace grows a way, set current knife contact to be P (Ti) , pass P of contact of below computation of bowstring cut law one knife by this bits (Ti+1) , make machining error δ is not more than treatment tolerance Ei between 2 o'clock. Set knife direction to add way for parameter, namely Ti+1>ti, make sure Ti+1 is in a relatively lesser initiative interval limits. Algorithmic description is as follows (refer to a graph 7) . (1) a few disperse that become parameter line disperse divide into equal parts nod P (Tj) , j=1, 2, ... , n, set current knife contact to be P (Ti) . (2) the position that the holiday places one knife contact is P (Ti+1) , computation the distance D between 2 o'clock, decide the midpoint T of line segment. (3) set T= (Ti+ti+1) / 2, get P is nodded on parameter line (T) , p is nodded on T of midpoint of computational line segment and parameter line (T) the distance between, machine the error δ that exists when curved surface namely. (4) if δ Ei, decide P of next knife contact (Ti+1) nod P for the record (U) . Knife of 3 beat form machines a knife after dot computation waits for knife contact and cutter shaft vector to decide, knife the geometrical concern that dot C can show 6 times according to the graph is begged conveniently piece. When vector of computational cutter shaft, as a result of photograph adjacent 2 knives contact is close to very much commonly, its interference environment is similar, cutter shaft vector is basic and identical perhaps change not quite, not was necessary to be calculated in position of every knife contact vector of its cutter shaft, will reduce treatment efficiency so. The place that studies in change of curved surface curvature acuteness place produces collision easily perhaps to interfere installed vector of a few crucial cutter shaft. Pass follow-up interference to check, vector of correction cutter shaft, again according to the knife coordinate calculation method can reach new knife digit is occupied. Calculate exemple basis afore-mentioned algorithm, process designing of the rough machining that insert mill and the module of finish machining process designing that are based on bosomy form cutting tool were developed on UG NX. The graph is shown 8 times for impeller of whole of engine of some model aviation contrail of cutting tool of the rough machining that insert mill reachs treatment to emulate a graph, the graph is shown 9 times wait for parameter for finish machining. Last word from raise treatment efficiency to set out, discussed face the rough machining that inserts mill and the technology of finish machining process designing that are based on bosomy form cutting tool, designed corresponding cutting tool contrail to generate algorithm, rough machining and module of software of finish machining process designing were developed 2 times on UG NX, gave out to calculate exemple, test and verify the rationality of article method. CNC Milling
CNC Machining