Model hollow turbine lamina makes core carapace unifinication method
- source:GERHOLD CNC Machining
5mm amount class, because this is making the structure that is about to complete much measure on the technology (the appearance of blade and little flow path texture) , this posed enormous challenge to production technology. At present the main workmanship of turbine lamina is fusible pattern cast. Its technological process basically includes model the design of core mould and make, the design of mould of suppress core, wax-pattern and make, assemble note oar of candle, besmear to make housing, dry model housing, dewax, agglomeration, pouring metal, take off the link such as stiletto of core, laser. This craft produces turbine lamina respect to have figuration precision in large quantities of quantities the advantage such as stability of tall, dimension, but the inadequacy that still has the following sides: Product development cycle long, cost is high; Process is complex, control difficulty is great, go against a product change; Realize dimensional stagger hard the production of hollow lamina; Model figuration of core carapace departure, when assembling, easy generation locates error, blade easy perforation, n is low. To make the cooling channel that has dimensional crisscross characteristic, academy of material of aviation of Russia complete Russia put forward model core enchases a technology, its characteristic is double deck wall, the stoma on foliaceous body is formed completely by assorted pottery and porcelain core. But model core enchases a technology to be put in a lot of difficulty, need to develop the is used at making fine small-sized core pattern with numerous amount for example; In setting assorted process, allow not easily to locate truly, combine difficulty to wait greatly. To implement sudoriferous and cooling technology, the company developed American Allison to cast cooling Lamilloy technology, lamilloy layer board on sheet metal quarter corrode gives Konghe passageway, solder sheet metal together next, the layer that forms efficient refrigeration board alloy. American GE company is used make a single crystal first hollow and the blade frame that carries cooling channel, fill up with the filler that can keep clear of next cooling passageway, enrage photograph deposit with electron beam physics then (the method of EB-PVD) forms exterior layer, will fill up the agent gets rid of finally, formed the sudoriferous and cooling lamina of wall of hollow, double deck. This kind of production method is in deposit exterior layer, loose be as high as 7% , this asks to had been not solved before the title; In addition, the material of hollow lamina framework and the deposit heat that express facing material expand abhorrent, easy bring about blade to rupture. As shape quickly the application that the technology casts a domain in nicety develops, can use shape quickly made prototype replaces candle model, in its apparently besmear hangs fireproof material, next roast, make casting case gets after aerification of archetypal material ablation, be used at metallic spare parts burn note figuration. Shape quickly the technology also is used at shaping directly casting mould of pottery and porcelain. For example: The material of powder of pottery and porcelain that DTM company developed Bao Fushu fat uses choice laser agglomeration (SLS) craft figuration and classics aftertreatment, made the pottery and porcelain that with Yu Rong the model casts case. The craft course of German Generis company is will arenaceous bead after levelling, use much passageway shower nozzle to spray equably to bed first colophony, next by activator of eject of method of outline of basis of a shower nozzle, the meeting after activator encounters colophony produces glue couplet reaction, make casting mould layer upon layer solidify accumulation figuration. Foundation of American Soligen company is three-dimensional print (3DP) what the principle develops is direct model housing foundry technology is modelling material with powder of pottery and porcelain, binder chooses silicon collosol. This kind of technology need not any moulds, clamping apparatus, can shape quickly the casting mould of pottery and porcelain of complex form; But, those who use quality of the precision of casting mould dimension that this kind of technology shapes, surface and casting mould is medium high-powered not tall, cannot satisfy the requirement that blade casts. Fusible pattern of lamina of union of Xi'an traffic university is cast technology, fast shape technology, gel notes modular technology, offerred foundry technology of casting mould of pottery and porcelain of type of whole of hollow turbine lamina. Casting mould of integral type pottery and porcelain is to point to model core carapace uses same data, at the same time figuration, need not combine assemble. These are made for complex and hollow lamina explored new technique. Be based on smooth solidify (SL) unifinication of archetypal structure of hollow lamina inside and outside makes methodological smooth solidify fast figuration (Stereolitho-graphy, SL) the technology is current in fast figuration technology, the method with figuration highest precision. The specific flow of workmanship of unifinication of structure of hollow lamina inside and outside. Specific include: (1) in the case that blade adds exterior of control base substrate on the foundation of three-dimensional model, cold gating system and hot gating system, cold gating system is used at perfusion of makings of oar of pottery and porcelain, hot gating system is used at pouring high temperature alloy. (2) use SL technology to shape afore-mentioned colophony are archetypal. (3) in expecting the oar of pottery and porcelain that has matched to fill enters colophony, shape. (4) undertake body drying of pottery and porcelain, defatted, agglomeration. (5) burn concentrate a metal. (6) hull, take off core. Cast photograph comparing with traditional fusible pattern, this kind of new technology has the following characteristic: (1) can shape aleatoric and complex, the blade lumen that has dimensional crisscross feature. As a result of model core is to use colophony prototype to shape, is not to use traditional metallic pattern to come despotic, make model core need not suffer metallic mould restrict and shape arbitrarily. (2) casting mould of integral type pottery and porcelain, model core carapace uses same data, shape at the same time, need not combine assemble. In can avoiding conventional technology so as a result of pottery and porcelain core and model housing heat expands the difference of rate and the pottery and porcelain that bring about core suffers force to rupture, be out of shape or slant the blemish such as core, avoid at the same time by assemble brought error to reach slant core and perforative phenomenon. (3) by smooth solidify fast forming machine shapes directly colophony mould will replace, need not design make model core compression mould and wax-pattern mould. So OK and rapid development, simplify craft, reduce cost, do not accept restriction of mould, clamping apparatus, change easily. (4) model core carapace figuration, need not besmear for many times hang, decreased to make housing time already so, won't because of pouring when craze of facing of the lukewarm appoint of generation carapace follows come away back a layer. (5) can shape directly gas film opening, shape opening of abnormity gas film. Such but craft of stiletto of leave out laser, and the abnormity hole that cannot make laser stiletto. 1 colophony mould and design of its machining complex use of research of Nextpage experiment smooth solidify technology notes a model to shape for gel offer a bag to contain mould of colophony of prototype of gas turbine lamina, prototype of gas turbine lamina is the most important part in colophony mould, its interior design has complex cooling channel. Prototype of gas turbine lamina can serve as already model the model that housing makes, can regard figuration of pottery and porcelain core as the mould again. Colophony model carapace and combination of prototype of gas turbine lamina form mould antrum, on colophony model carapace design know how things stand and feel confident of handling them fixes system of infuse of makings of oar of type pottery and porcelain, in the cooling channel that makings of oar of pottery and porcelain can carry this system to make the same score quietly infuse mould antrum and interior of gas turbine lamina. Prototype of metallic gating system is used at preparation pottery and porcelain gating system, guide fluid of high temperature metal thereby in casting mould of smoothly infuse pottery and porcelain. The makings of oar of pottery and porcelain of preparation of makings of oar of pottery and porcelain of 2 low viscosity, low shrinkage is the production foundation of casting mould of integral type pottery and porcelain. On one hand, makings of oar of pottery and porcelain should have lesser viscosity and good liquidity, in order to make sure oar makings fills mixed pattern cavity, especially petty and in-house cooling passageway, the viscosity that oar of general requirement pottery and porcelain expects is not more than 1Pas; On the other hand, satisfy blade to assure the integral performance of casting mould of pottery and porcelain the requirement of foundry technology of directional and caky, single crystal, in assure figuration craft sex while, should choose proper base material, mineralizer and granuality to deserve to compare. This research chose chroma to serve as dispersive agent for the polypropylene acerbity natrium of 18% , decided optimal add a capacity (=2 of quality mark ω .
5% ～ 3% , it is reference with powdery makings) , reduced viscosity of makings of oar of pottery and porcelain through grain grading technology, raised solid appearance content, decided reasonable ball rubs time (2h ～ 3h) , preparation low viscosity (0.
675Pas) , Gao Guxiang (=55% of bulk mark υ ) makings of oar of pottery and porcelain. The composition that oar of pottery and porcelain expects affects his not only sex of craft of base substrate figuration, firing quality, and the room temperature performance that affects casting mould of pottery and porcelain directly and high temperature capability. Task group chose high pure quality of work powder of corundum of frit of 2 kinds of report makes base material (D50 is 25µm and 5µm respectively) , magnesian with yttria small pink serves as mineralizer. Magnesian, yttria rises to reduce the firing temperature, effect such as agglomeration of stimulative pottery and porcelain, magnesian still can restrain grain to grow, refine grain; They are formed with base material respectively high temperature resistant in all crystal (magnalium pointed spar and yttric aluminous garnet) , improve high temperature capability of casting mould of pottery and porcelain. The sample of base substrate of pottery and porcelain that dry method studies casting mould of pottery and porcelain of 3 whole type to be lapped by colophony prototype, only two end do not close, the area of watch of base substrate of pottery and porcelain of as immediate as air effect is small, use convection dry, efficiency is inferior. In comparative air (35 ℃ ) fall with vacuum environment (10Pa ～ 100Pa) sample of base substrate of pottery and porcelain is dry dehydrate rate, the result makes clear: Vacuum is dry 4.
After 5h, base substrate of pottery and porcelain was lost 82.
The moisture of 88% , and air is dry base substrate of pottery and porcelain dehydrates only 7.
85% . Because dry process reduced vacuum,this is all round air is right the pressure of base substrate of pottery and porcelain, moisture can compare easy ground migratory to base substrate surface, in the meantime, vacuum is dry the boiling point that dropped water, accelerated evaporate speed. Studied the effect with dry microwave, microwave is dry much steam produces inside short time cannot seasonable eduction, make base substrate of pottery and porcelain produces dissilient sex crackle easily; In the meantime, exorbitant temperature can make colophony prototype produces heat to be out of shape, affect base substrate precision and figure. But vacuum is dry as dry as convection same, to Shui Jitao porcelain oar expects (the =55% that be like υ ) the dry shrinkage with larger presence, accordingly, because systole gets the craze problem that be restricted and produces,still did not solve base substrate. Make sure to reduce dry shrinkage the slightness that is lapped by colophony mould core is fully dry, this research uses freeze-dry technology in process of preparation of casting mould of pottery and porcelain, preliminary formulate freeze-dry craft. Concrete step is: Preexistence - 45 ℃ freeze stock beforehand, make the moisture in base substrate forms ice crystal quickly, next vacuumize gives base substrate supply heat energy (be in base substrate control from beginning to end fluid photograph in all brilliant is nodded (- 3.
8 ℃ ) the following - 2 ℃ ～ - 5 ℃ ) , make base substrate puts direct sublimate on the ice mediumly. Because the moisture in base substrate of casting mould of pottery and porcelain is direct by solid state sublimate, fine without wool active force (dry and contractive driving force) , eliminated dry systole basically thereby (υ =55% , shrinkage is only 0.
2% ～ 0.
3% ) , can maintain the structure with original base substrate and pattern. Intensity of casting mould of the pottery and porcelain in 4 roast process needs to heat up disengagement to remove SL prototype and among them organic matter not only in process of roast of base substrate of casting mould of metabolic rule pottery and porcelain, and want casting mould of agglomeration pottery and porcelain, the made room temperature bending strength with be had particular. The curve of change of room temperature bending strength of base substrate of casting mould of the pottery and porcelain below different roast temperature. At first, as a result of polypropylene acyl amine three-dimensional and meshy the existence of organic matter, base substrate of casting mould of pottery and porcelain has the room temperature bending strength of treatment to achieve 12MPa, but lift as temperature, polypropylene acyl amine heats up solution ceaselessly, what intensity can follow temperature is elevatory and reduce quickly, bending strength of room temperature of base substrate of casting mould of the pottery and porcelain when 300 ℃ drops 1.
5MPa, the conference is subsequently smaller, appear low strength region (in 500 ℃ ～ it is only inside 900 ℃ limits 0.
1MPa ～ 0.
3MPa) , right now density of accumulation of itself of grain of only support pottery and porcelain keeps casting mould structure. Above considers to make clear: After 300 ℃ , SL colophony is archetypal already carbonization, can produce bigger expansibility to casting mould no longer. Accordingly, for surely roast gives SL colophony prototype, prevent model housing craze, in achieve 300 ℃ to should be adopted before slow heat craft (20 ℃ / 30 ℃ of H ～ / H) , had prevented large thermal stress generation, add 2% ～ through be in makings of oar of pottery and porcelain additionally the polyamide of 3% inferior (PI) will raise base substrate the bending strength when 300 ℃ , avoid casting mould craze. Join PI and mineralizer (magnesian, yttria small pink) the bending strength of room temperature of base substrate of pottery and porcelain after follows temperature change curve. PI is powder of colophony of sex of a kind of hot solid, when heating to be controlled to 100 ℃ , begin bate flow, the meeting after continueing to heat produces cross-linking solidify; Begin to decompose when 500 ℃ , 24h heats when 600 ℃ , weightlessness is 20 ％ only. Accordingly, can make sure casting mould of pottery and porcelain still has higher strength in 400 ℃ temperature (1.
6MPa) , and the intensity when 300 ℃ is 5.
3MPa. Nextpage is in low strength region, because do not have stuff stuff to prop up, interior of casting mould of pottery and porcelain core issues extremely easy cave in in self-prossessed action, because this should take corresponding craft step, make narrow of 0 strength region. The place before be like is narrated, join PI to be able to defer the ablation career of organic matter; Additional, through joining a few mineralizer small pink, the firing temperature of base substrate of pottery and porcelain of electric frit corundum can be dropped on certain level, also can reduce extent of low intensity temperature wide. In 900 ℃ left and right sides, bending strength of base substrate of pottery and porcelain begins to restore somewhat, achieved in 1050 ℃ 1.
2MPa, main reason is 900 ℃ ～ electric frit corundum is medium between 1200 ℃ petty grain begins confluence, generated MgAl2O4 of much brilliant photograph and 3Y2O35Al2O3 with union of magnesian, yttria, they distributing in big grain not between the grain of electric frit corundum of agglomeration, those who make is mutual a confluence with have certain, casting mould of pottery and porcelain has particular bending strength, assure the integral sex of casting mould of pottery and porcelain thereby. Through adopting fast agglomeration technology, with 420 ℃ / 540 ℃ of H ～ / the rate-of-rise of air temperature of H passes 500 ℃ ～ quickly region of 900 ℃ low strength, build agglomeration strength quickly, prevent collapse of in-house and complex pottery and porcelain core, it is the method of a kind of effective. Whole roast craft can divide into 2 phase: Slow before 300 ℃ roast is taken off except colophony mould, after 300 ℃ fast agglomeration, example of casting mould of pottery and porcelain, join of its interior core is in good condition. After component of material of casting mould of pottery and porcelain of type of whole of function of casting mould of pottery and porcelain of 5 whole type is affirmatory, its are firing craft sex and integral performance basically depend on agglomeration craft (burn time of temperature, heat preservation, rate-of-rise of air temperature eventually namely) , those who raise casting mould of integral type pottery and porcelain is firing leading is the base that establishs agglomeration craft. Should control strictly firing shrinkage, make be less than 1% , gain particular room temperature bending strength at the same time (be more than 10MPa commonly) , what stay in order to facilitate clear after ablation of manage SL prototype is cindery, make sure its have certain high temperature capability. Method of test of function of casting mould of pottery and porcelain consults HB5353 of aviation occupation standard.
1-2004. Firing shrinkage and room temperature bending strength as burn temperature change curve eventually, can discover, as firing temperature elevatory, firing shrinkage and room temperature bending strength also increase gradually. When firing temperature prep above when 1600 ℃ , firing shrinkage exceeded 1.
2% , affected the integrality of casting mould of pottery and porcelain; When firing temperature under 1500 ℃ when, room temperature bending strength is less than 10MPa. Additional, considering mineralizer reaction temperature, decide 1550 ℃ are in the experiment burn temperature eventually, right now firing shrinkage is less than 1% , and room temperature bending strength is more than 10MPa. To satisfy directional and caky with single crystal pouring the high temperature that craft asks carapace and model core intensity, task group puts forward macerate yttric collosol and 2 agglomeration aggrandizement to handle technology, improve its high temperature capability. Not the bending strength that below vacuum 2 the macerate of aggrandizement processing, air, macerate below vacuum, macerate issue in 1550 ℃ and deflection are comparative. After 2 times macerate aggrandizement handles vacuum, high temperature bending strength by 1 original.
0MPa rises to 3.
2MPa, and high temperature deflection by 3 original.
0mm drops to 0.
8mm, achieved gas turbine lamina requirement of foundry technology of directional and caky, single crystal. Analyse discovery through X-ray, the opposite content that high temperature capability gets because through aggrandizement processing increased yttric aluminous garnet,improvement is (vacuum after 2 macerate by 6% ～ 9% raise 17% ～ 20% ) , and the opposite content that reduced alumina (by 77% ～ 82% reduce to 69% ～ 71% ) , yttric aluminous garnet forms aggrandizement network between the bulky grain alumina that did not melt, block up the vitreous photograph of low melting point flows, improved the high temperature capability of casting mould of pottery and porcelain thereby. Contain target of integral performance of casting mould of integral type pottery and porcelain, AC-1 is development of academy of Beijing aviation material model housing data function. Casting mould of porcelain of colophony model Xiang Tao and the method that cast of turbine lamina nicety changes can realize structure of inside and outside to shape at the same time, include the alveolus on blade body and hole of double deck wall. Can see, turbine lamina precision and exterior quality still remain to rise further. The wall scale that contains the cast of nicety of gas turbine lamina that becomes sectional to enrage velar opening is elliptical model, mural face is rectangular outside, this structure has better refrigeration to enrage velar refrigeration effect. Last word (1) it is a foundation with prototype of smooth solidify colophony, combinative gel notes modular figuration technology, be used at lamina of accurate figuration gas turbine model casting mould of pottery and porcelain of type of housing core whole produces a method, realized the fast changeover of prototype of laser solidify colophony to metallic lamina, overcame the weakness of workmanship of combined-type of casting mould of traditional pottery and porcelain, assure model core, model housing mutual the positional precision between, raised thin wall lamina to produce percent of pass; In the meantime, leave out model drawing of patterns of core base substrate, model core and wax-pattern profiling or model between core the technology segment such as combination, simplified complex lamina workmanship. (2) offerred technology of freeze-dry of base substrate of wet condition pottery and porcelain, won the measure of dry and contractive technology of nearly 0, avoided the generation of dry stress and crackle, announced its are immanent mechanism; The base substrate of pottery and porcelain that studied different stock is comprised is out of shape in the heat in agglomeration process the rule, the control that carries stock and reasonable agglomeration craft implementation are close 0 firing and contractive; Firing shrinkage is less than 0.
5% , prep above home already had data, assured the integrality of integral type casting mould. (3) studied heat of smooth solidify prototype expands quantity, thermal stress and warm up the rule between speed, formulate the sound technology that heat up solution, surely ablation colophony is archetypal, avoided craze of casting mould of pottery and porcelain. (4) to oar of pottery and porcelain makings recipe and agglomeration craft undertook optimizing, pass aggrandizement of 2 macerate yttric collosol, agglomeration the high temperature capability of casting mould, studied the underlying law between composition of appearance of micromechanism, substance and function of casting mould of pottery and porcelain. The test makes clear as a result, below the high temperature of 1550 ℃ , deflection can is less than 1.
0% . (5) made have the casting mould that opening of sectional gas film changes on complex and cooling structure and blade cliff face, make for new-style lamina provided new method. CNC Milling