Laser shapes quickly (Laser RapidPrototyping, LRP) the technology is a when will nearly 20 years make a technology major breakthrough. This technology is a kind of new-style and integrated production technology that involves much door subject, its are right the consequence of manufacturing industry but with 20 centuries the photograph of numerical control machine tool of 559 time is compared. Metallic spare parts made a technology represent the newest development way of RP technology quickly. Abroad considers to also mature relatively to the theory of RM and craft, and in the facility that in last few years already much home company rolls out commercialization. And the research that home basically is pair of foundation craft, main research unit includes northwest industry university, Beijing aerospace university, Huanali university of work college, Hua Zhongke ability [university of aerospace of 5] , Nanjing, Tsinghua university. The dominant position with RM the largest technology is its do not need a mould or the tool is machined, acquire the functional part of demand directly. Although be made quickly (RapidManufacturing, RM) the technology is in sex of freedom of material choice, design, and the respect such as control of cost of research and development has very large competition dominant position, but just appear on home market as a result of RM technology and crucial technology is immature, had been not accepted generally by the market. Current, what can make accurate metal part truly is fast shape the technology has electorate laser to fuse only with electorate laser agglomeration. Electorate laser agglomeration (Selective Laser Sintering, SLS) shape the method shapes when metallic spare parts, the metallic powder that uses colophony or Fu of bag of material of low melting point more serves as raw material [8] , through laser scanning makes colophony fuses metallic powder solid writtens guarantee together, metal of low melting point of ooze of defatted, dip is passed after shape (wait like bronze) will rise send density. SLS technology shapes process of metallic spare parts is complex and below spare parts intensity and precision majority circumstance still short of requirement. And electorate laser is fused (Selective Laser Melting, SLM) the technology is what provide innovation one kind extremely is fast shape technology, can one pace treatment goes out have metallurgy to be united in wedlock, opposite density is adjacent 100% , have the metallic spare parts of complex structure, tall dimension precision. Metallic spare parts makes technical metal spare parts make a system can divide quickly quickly it is 3 kinds: (1) use laser illuminate beforehand the metal with good spread out is pulverous, namely metallic spare parts shapes after ending, will be enclothed by powder completely. At present this is planted method in the market, place of courtyard of each scientific research is used most, include alternative laser agglomeration (agglomeration of laser of SLS) , direct metal shapes (Direct Metal LaserSintering, DMLS) , electorate laser fused, Laser Cusing. (2) the powder that nozzle of use laser illuminate carries flows, laser and carry powder to work at the same time, also call laser to shape completely (Laser EngineeredNet Shaping, LENS) [13] . This method is used in home at present more, like northwest industry university [the laser that 14] studies is stereo shape, Beijing aerospace university [15] uses this method to shape large titanium alloy. (3) use electron beam to fuse (ElectronBeam Melting, EBM) beforehand the metal with good spread out is pulverous. This method and the 1st kind of principle are similar, just use heat source to differ, it is high power laser and electron beam respectively. Already appeared in Sweden the equipment development that university of Tsinghua of home of commercial EBM equipment had earlier stage and technology research. Because type of equipment of the RM on the market is at present various, this task basically shapes to the first kind the system undertakes summing up, basically incorporate SLM/DMLS and SLS technology namely. Electron beam is fused shape the technology is in principle and shape in the process as similar as 2 kinds of afore-mentioned technologies, also undertook the part explains. SLM/DMLS of 1 SLM/DMLS technology shapes process principle and SLS are basic and identical. DMLS technology uses material to be the mixture that different metal comprises more, each composition is compensated each other in agglomeration process, be helpful for assuring to make precision. What belong to pulverous material for bail is fast and fused, SLM technology needs laser of high power density, facula focusing arrives to M of a few μ M of hundreds of μ . SLM technology is current most the laser power that often uses the fiber-optic laser with admirable mode of beam of light is in 50W above, power density amounts to above of 5 × 106 W/cm2. Abroad studies worker sums up discovery, influence SLM shapes the influencing factor of the effect is achieved 130 many, and among them 13 elements have decision effect. the influence according to oneself experience SLM shapes the element cent of quality is 6 kinds big, include: Material (sex of composition form appearance, particle size distribution, fluidity, content) , laser and smooth route system (diameter of laser mode, wavelengh, power, facula) , scanning feature (method of scanning speed, scanning, layer span of thick, scanning beam) , outside ambient (oxygen content, humidity) , geometry is characteristic (prop up add, geometrical feature, space is put etc) , mechanical element (sex of level off of pulverous spread out, shape the stability of the crock of motion precision, orgnaization that spread pink) . Check SLM shapes index, basically be send interior of surface roughness of density, precision, surface, spare parts leftover stress, intensity and hardness 6, the part that other and special applying needs to ask to undertake relevant index detects according to the industry. SLM shapes the leading defect of the process has a ball to change, warpage, crackle. The biggest challenge that at present SLM technology place faces is: Shape efficiency, but repeatability, dependability (equipment stability) , this also is the biggest challenge that RM industry place faces. Agglomeration of 2 alternative laser shapes (SLS) SLS technology cent is spare parts of the direct metal that make and spare parts of the indirect metal that make 2 kinds. Spare parts of the direct metal that make uses the metallic powder of melting point of at least 2 kinds of above, carry benefit of composition of fused low melting point wet and stuff is expensive clearance of grain of powder of metal of melting point structure, rise structural material felt the means that agglomeration becomes metallic part. SLS makes a metal directly what still can pass laser frit to change metallic powder grain is outer, and the means that the interior of pulverous grain did not fuse, will pulverous grain is passed outer agglomeration felt is together. SLS makes metallic part secondhand is the metallic powder that uses material of high polymer polymer to lap Gao Rong is nodded, laser fuses polymer material obtains prototype with rising metallic powder felt means, pass fluid of metal of low melting point of roast, infiltration, heat to wait next static pressure wait for aftertreatment working procedure to rise make density. SLS shapes two kinds because the method of metallic spare parts is to use Gao Rong of felt of powder of low melting point to nod powder, make SLS is made mechanical performance is poor, especially outspread rate is very low, can apply at functional spare parts directly rarely make on. The key of SLS technology is the development of new-style material, the material range that applies to SLS technology is wide, efficiency of production of this technology itself is tall, shape the process is controlled easily. 3 electron beam are fused shape technology (EBM) the difference of EBM and SLM/DMLS system basically is heat source differs, shape principle essentially similar. EBM technology shapes room must be high vacuum, ability makes sure equipment works normally, this makes EBM technology overall and sophisticated degree rise. Because use electron beam to serve as heat source, metallic stuff does not have reflection almost to its, rise considerably with energy absorptivity more. Below vacuum environment, the wetability after material is fused also rises greatly, increased bath between, the metallurgy between layer and layer combines strength. But, EBM technology shapes to still put in following problems: (1) be taken away easily by air current in the powder in process of vacuum room bleed, cause systematic pollution; (2) fall in electron beam action, pulverous and easy break the ranks. Accordingly, EBM technology need goes to systematic warm-up 800 ℃ of ＞ , make powder is in shape indoor beforehand agglomeration solidify is together. The advantage is EBM shapes process efficiency is tall, the spare parts is out of shape small, shape the process does not need a metal to prop up, microcosmic organization is compact wait. Defect is tall warm-up temperature raises very tall requirement to systematic whole structure, need of the spare parts after treatment ends shapes in vacuum the refrigeration in the room is quite long period of time, reduced the manufacturing efficiency of the spare parts. Commercial RM equipment and function are worldwide inside, had had the RM equipment manufacturer of many maturity, include German EOS company (EOSING M270, DMLS technology) , German MCP company (Realizer series, SLM technology) , Concept Laser company (M Cusing series, laser Cusing technology) . The EBM equipment of Swedish Acram company also has important place. Current, in recent years almost all SLM/DMLS equipment use fiber-optic laser, because of fiber-optic laser almost admirable, photoelectricity changes quality of maintenance-free, beam of light efficiency is advanced the advantage makes its apply at RM advantage apparently. As the development of fiber-optic laser, the power of use fiber-optic laser has the tendency that increases gradually, arrive from initiative 50W current mainstream 200W. Notable is, the LaserCusing technology of Concept Laser company did not use Zhenjing to scan, and the system of numerical control of X /y axis of use blame mainstream, drive laser head basis through servo electric machinery the outline contrail of the spare parts moves in X /y direction, so its shape the restriction that spare parts limits need not accept Zhenjing sweep range, its are shaped spare parts efficiency and dimension precision can obtain SLM/DMLS technology same standard. Series of commercial facilities of 1 each company expresses the 1 energy that reachs correspondence for equipment of each company RM source, shape dimension parameter. Major production business has facility seriation is produced, the energy source with different configuration and shape spare parts dimension differs with satisfying the client's demand. SLM/DMLS technology asks powder fuses completely, demand of laser power density is high. Commercial RM equipment uses fiber-optic laser entirely almost, MCP company and EOS company already the fiber-optic laser application of 400W of research and development shapes with rising efficiency. Corresponding facilities of Nextpage2 each company shapes production function is expressed 2 it is each RM system use typical data, layer is thick reach shape main function index. The material sort that each equipment manufacturer chooses is similar, basically include steel of alloy of stainless steel, titanium, tool, cobaltic chromic alloy to wait, among them EOS company shapes place basically is own research and development with material. Thick general set is in the layer of each RM equipment left and right sides of 50 μ M. The layer is thick too thin, although can improve shaping quality, but reduce treatment efficiency, and when the layer thick increase, will make shape simple quantitative change is poor. The RM equipment that produces business each quite shapes quality discovery, in send precision of density, dimension and exterior surface roughness to wait for a respect, EOS, MCP and Concept Laser company reach same level, and Arcam company EBM shapes to go up in dimension precision and exterior surface roughness relatively a few poorer, because facula of electron beam focusing is compared,basically be big and cause. 3 application give an example is current SLM/DMLS shapes quickly the system basically applies in individuation of aerospace, car, medicine make, the domain such as small-sized Injection Mold Tooling and mold insert, still be aimed at small lot, individuation a few complex undertake machining. Use RM equipment is most still is a few research organizations and war industry unit. The largest dominant position of RM technology is his almost absoluteness on geometrical appearance. SLM/DMLS as laser beam machining at the beginning of the industry is arisen, equipment production business applies at which group course of study to had been not understood completely to laser technology, can one step by step dig potential application from inside conventional treatment industry. Professional personage seeks potential application inside travel of need of same RM technology. Abroad studies direction and progress abroad consider to include the following fields in the light of RM: Academic research of the foundation, shape technology research, application research, shape new material exploratory study. In addition, still include new applied domain exploration, if be made of spare parts of functional gradient material directly. Newest research makes clear, SLM/DMLS shapes a few kinds of specific data can be achieved close to of 100% send density. Include alloy of steel of 316L stainless steel, titanium and titanium alloy, tool, cobaltic chromium, copper alloy, aluminium alloy to wait into profile makings. Shape in the light of RM the research that the spare parts sends density is the problem of a core inside this domain, ask to send density to achieve above all close to 100% , achieve at least with cast a mechanical function that comparative. Additional, send density basis to need to be able to be controlled freely, achieve can accuse to send density or gradient to send density. The scanning strategy that EOS company and Arcam company use is to build go up in this theory foundation, spare parts most outside use low speed scanning a few layers, and interior uses high speed scanning, saved handling time greatly. Send density to raise a part, the research technique that researcher uses includes craft parameter to search [the method such as the 25] , physics character that uses remelting of special scanning strategy, surface and change data. Additional, scanning shapes the bath in the process splatters, the ball is changed and stick the element such as pink to bring about SLM/DMLS surface surface roughness taller, it is a when restrict this technology to apply extensively main factor. Although RM equipment manufacturer passes the method of the aftertreatment to be able to improve exterior quality greatly, but be aimed at surface of a few lumen complex, or the part is careful spare parts, the aftertreatment brings about the likelihood shape an attaint. SLM/DMLS shapes there are a few drawbacks in the process is its itself is inherent, if the existence of leftover thermal stress is mixed,shape when look out falls incidental cave in, stick the blemish such as broken bits. To leftover thermal stress, abroad is solved already basically, basically be to adopt special scanning method, make shape the quantity of heat in the process distributings even, perhaps eliminate thermal stress through follow-up heat treatment. Although SLM/DMLS technology alleges,can machine aleatoric and complex metal spare parts, do not have limitation to geometrical appearance, but the author is in shape actually the discovery in the process: The round hole at Z axis direction, square aperture produces a few thin walls, parallel easily the blemish such as cave in of hole of axis of thin wall attaint, Z. SLM/DMLS technology to a few elaborate structures (be like ＜ 0.
The aperture of 3mm) shape difficulty is greater also. RM another main task is shape to how rising the research of efficiency. Produce a method at traditional pattern relatively, although RM technology shortened greatly product research and development is periodic, spare parts of OK and direct production function or Injection Mold Tooling, but the treatment layer thickness because of RM, although minor volume is individual,the spare parts needs possibly also to machine a few hours, and the individual part with large volume needs 20~30h more, even between a few climate, long treatment raised very strict requirement to the dependability of RM equipment. And if use RM technology to undertake batch produces a part, raise manufacturing efficiency to appear very important. Abroad had had preliminary research in the light of this task, main train of thought is quick change speed of laser power, scanning and change treatment layer are thick, OK also the use requirement of the spare parts of the basis uses special scanning strategy to wait. Specific means is as follows: (1) adding workpiece to send density to drop below not big case, raise scanning speed and treatment layer appropriately thick, raise laser power cost accordingly. (2) scanning of low speed of the outline outside using, the means that in-house and hypostatic high speed scans, also can improve manufacturing efficiency greatly. The unit that home studies to current situation home begins research in RM respect at present basically includes northwest industry university (laser shapes completely technology) , beijing aerospace university (laser accumulation shapes technology) , Tsinghua university (EBM technology) , college of industry of Hua Na grain (SLM technology) , university of Hua Zhongke ability (SLS/SLM technology) . Home starts in RM respect late, lag behind at European country 6~8 year, and the way of research is relatively single also, still basically center in the basic research of craft, theory and equipment. The RM that at present home still does not have commercialization shapes quickly equipment, research expenses originates mostly the country tackles key problem the project is aided financially, of various government sector aid financially. Huanali was versed in the university is on Dimetal-240 foundation 2007, understand joint development of limited company of laser science and technology with Guangzhou luck Dimetal-280 of prototype of production equipment of the 2nd SLM, the characteristic of new system includes the following 6 respects. (1) shape directly to satisfy spare parts of completely compact metal needs high accuracy, used have quality of tall beam of light (M2 ≤ 1.
1) , shortwave is long (1075nm) , the 200W of cost of tall stability, low maintenance is fiber-optic laser. (2) the system of Zhen Jingsao draw that provides high speed high accuracy and lens of θ of German entrance F- . Resolution of scanning Zhen Jing can amount to 12 μ Rad, repeat precision to be able to amount to 40 μ Rad, 7m/s of ＞ of speed of top fixed position. Stimulate beam of light to pass F- θ lens to be able to assume office to obtained power to distributing in working plane even diameter is facula of focusing of 30~50 μ M. (3) the system uses high accuracy the accurate laid with pulverous implementation of control of electric machinery of 6 axes servo. Shape the crock reachs those who spread powdery crock to rise fall precision can amount to ± 10µm. Be aimed at metallic spare parts technically still the characteristic of fast workmanship, designed the distinctive scraper that spread pink, this scraper that spread pink can be safeguarded automatically shape process stability undertakes. (4) oxidize mediumly in fused process in the light of metallic powder, use whole and protection of local inert gase, installed flue gas to filter device, protective gas includes argon gas and nitrogen, shape shape in the process the room is embedded oxygen capacity control is in 0.
1 ％ is the following. (5) place includes laser to shape with software method of scanning of process control software, SLM is generated with optimize software, Magics13.
Software of 0 data processing, among them laser shapes process control software and SLM scanning method are generated with optimizing software is own research and development, the craft characteristic that can shape in the light of metallic spare parts wins the best laser parameter, parameter that spread pink and scanning way. (6) equipment shapes directly tall compact and have shape higher the metallic spare parts of precision, require simple in season only arenaceous or polishing aftertreatment can be thrown use. Shape the spare parts is opposite density ≥ 97% , dimension precision ± 0.
1mm/100mm. Index of function of prototype of current Dimetal-280 equipment approachs level of foreign commercial prototype basically, express the comparative data of congener equipment of the 3 technical index that are this equipment and abroad. Nextpage from the watch 3 can see, at present Dimetal-280 is in certain property side can have been compared with photograph of foreign congener product, shape for instance precision and send density to wait. Because foreign RM equipment shapes,control of room core condition has been compared, in material composition control respect also comparatives strict, overall systematic stability is excellent, this also is the target that tries hard next. The crucial part that SLM equipment place needs includes lens of focusing of fiber-optic laser, F-theta, high speed to scan Zhen Jing is an entrance. Dimetal-280 equipment shaped successfully early or late the metallic spare parts of all sorts of complex form, if the graph is shown 1 times, these spare partses have ≥ of 97% send density, mechanical function approachs casting forge level, after needing simple gush arenaceous aftertreatment only, can throw use. Graph 2 shape for SLM the microcosmic organization of spare parts of 316L stainless steel. Shape to SLM test specimen of 316L stainless steel undertakes drawing function test makes clear, 600MPa of tensile strength ＞ , outspread rate ＞ 15% , test specimen is microscopical hardness value is HV250~275. Microscopical hardness test pressure is 3N, pressure brings to bear on time is 15s. SLM technology applies a domain to whether choose RM to make, the measure that should consider a hardware (the bulk of the spare parts) as complex as appearance degree, and the quality requirement of the spare parts is the mainest factor. Among them the bulk of the spare parts and form are complex degree of immediate decision finished cost, and the quality of the spare parts asked to decide whether RM technology can satisfy real requirement. (1) spare parts dimension and complex degree: The part is smaller and complex, choose RM technology to will have larger dominant position. When the spare parts small and complex, RM shapes every time can achieve a few even hundreds of, the machine treatment that compares a tradition will have an advantage more. RM makes cost and size of spare parts bulk concern into direct proportion. (2) quality requirement: Quality of precision of the intensity that includes a part, dimension, surface. The biggest question that at present perhaps RM technology encounters is spare parts quality still cannot achieve a tradition quite completely to machine a method. Compare traditional method, RM technology is returned in the respect such as quality of dependability of dimension precision, material, surface relatively inferior. Accordingly, when spare parts intensity and exterior quality when the demand is very high, RM technology may be improper. RM technology basically applies in the rapid research and development of new idea product at present, machine cycle in order to shorten. The treatment that is used at batch product still has a story rarely, the batch production technology that EOS company reports to DMLS technology applies at coronal of tooth bridge tooth is relatively mature, shape tooth coronal can achieve 500. The difficulty that SLM popularizes in home and price of next equipment of SLM of working way abroad are in probably 500~700 10 thousand yuan, this does not include follow-up material to use cost to wait. Place of scientific research courtyard or the enterprise cannot bear so high cost commonly, SLM equipment needs professional personage operation, the knowledge with operation personnel thorough to its technology principle need also is a when restrict equipment application main factor. SLM equipment upholds charge relatively costly, include to protect gas, buy profile makings to wait from former firm. But tremendous vendibility, make home very much the research that college and scientific research orgnaization begin sortie SLM technology. But at present the development of domestic SLM technology and promotion still exist a few problems. Advocate if this technology system is compositive,spend tall, need is comprehensive data, optical, software, numerical control, mechanical wait for much class talented person joint research and development. Cycle of equipment research and development is long, technical difficulty is great, bring about equipment costly, and applied domain is returned relatively narrower. The stability of component of domestic form a complete set still is less than foreign level, still also can make the work with a few lesser dimension only at present. The theory that also lacks maturity on the research and development of material of form a complete set is propped up. Only research and development gives the high reliability and hi-tech index, SLM facility that has own intellectual property, have the craft line of form a complete set at the same time, ability is in our country bigger range popularizes this technology. Lab of laser beam machining of college of industry of Hua Na grain will innovate ceaselessly in SLM technology respect, continue to push SLM installation upgrade: (1) design and make the 3rd acting SLM shape equipment, have the seriation research and development of equipment according to market demand, make equipment compact, more human nature is changed. (2) turn Dimetal series equipment hard to the market. (3) the machinery that improves facility and control stability, perfect relevant software, develop a variety of material maturity technology, seek the market application of SLM technology continuously. CNC Milling