Abstract: For laser frit Fu fast and flexible production metal spare parts (LRFM) , developed a kind of new-style coaxial nozzle sending pink, made the NiCrSiB alloy part of a few simple appearance, studied uniformity of the microcosmic organization of these metallic spare partses, composition, hardness profile and tensile strength. The precision that should raise laser frit Fu to make a part quickly must assure to make the stability of the process, have closed-loop control to the main influencing factor of whole production process consequently. Keyword: Laser is fast and flexible make; Metallic spare parts; Laser frit Fu; NiCrSiB shapes quickly the technology is a kind of exceedingly good advanced production method, it can use computer CAD model directly, decide a mould and need not be especially in a few hours the space model that makes a complex appearance or substance. Shape quickly at present the technology includes stereo photoetching (SLA) , cascade is made (agglomeration of LOM) , alternative laser (metal of SLS) , melt piles up (FDM) , three-dimensional presswork (particle of 3DP) , orbit is made (a variety of methods such as BPM) . But at present RP technology can produce a metalloid prototype only normally (like) of polymer, candle, paper or Bao Fu powder, although they have good appearance precision, but do not have mechanical intensity and mechanical property. The new-style and fast production technology that because this developed country all develops energetically,can make a part of metal of sex of function of complete density high strenth directly [1-8] , the laser that is based on laser frit Fu is fast and flexible production technology (LRFM) or direct metal deposit (DMD) is to shape quickly further progress of the technology, it shapes those who have quickly the new height that the technology advances metal and high temperature alloy, it is to shape quickly of fundamental and elite of technology of laser beam machining compositive. The primary consideration LRFM that laser makes quickly is one kind produces a method with the tradition (the part of purify no use) add type differently completely (add useful share) production technology. a bundle focusing of high power laser forms bath to workpiece surface, metallic powder is formed into bath by coaxial gush frit cladding, according to CAD given the course scans back and forth stimulate beam of light to be able to chase a line to pursue a line, chase a layer to chase a ground to make a metallic part hypostatic. As a result of the fast and caky feature of laser frit Fu, what make the metallic spare parts that go out have good quality and strength. LRFM is one kind is based on laser frit to make a technology integratedly what include laser, CAD, CAM, sensor and pulverous metallurgy of Fu. Laser frit Fu is technology of a kind of coating at first, plane of edge of path of laser frit Fu is transverse much talk is built receive can obtain high-powered exterior coating, to the space along perpendicular direction range of laser frit Fu many layer overlay can make a three-dimensional metal part. Laser frit Fu makes a technology as a kind, must consider the following factors: What the high quality coaxial that can achieve result of isotropy frit Fu sends laser of powdery nozzle; frit Fu is three-dimensional shape ability; production precision and its influence mechanism; makes influencing factor of the key in the process detect the development; of the software of CAD/CAM of special type of closed-loop control; of parameter of key of; production process moves to workbench. The development of new-style and coaxial nozzle the article developed a kind new-style muti_function coaxial nozzle sending pink (refer to cover photograph) , can satisfy the demand that laser creates quickly, this coaxial nozzle has the following characteristic: What go to the lavatory neatly is perpendicular assemble and unassemble the good refrigeration that the trends that functional; sheds to powder spends part of interior of functional; nozzle equably, the adjustment that assures to stabilize reliably working; for long to speak facula volume functional; suits focal length limits to reflex laser for 100-300mm; energy and rebound the recycle function of metallic powder. Test of laser production test uses RPC3000 fast axis to shed CO2 laser and numerical control workbench and pressing type pneumatic coaxial is narrated to send pink spray head before powder feeder is mixed. Frit Fu material is Ni25B nickel radical alloy, composition is expressed as follows, matrix is mild steel. Ni25B pulverous composition and result of performance list test and discuss 1.
LRPM makes spare parts of simple shape metal be based on the technology of laser frit Fu of new-style and coaxial nozzle, the method that uses the overlay that chase a layer is made gave a few simple appearance (like Bao Bi, cylinder) metallic spare parts (the 1) that be like a graph, is main craft parameter: ? ?kW of す β holding sb in respectful awe, facula diameter 4.
5mm, scanning speed 0.
1m/min, speed sending pink 11.
2g/min, aeriform discharge L/h. When making round pillar and only part of simple Bao Bijian, use the part that does not add craft of Fu of frit of special pilot laser to also can make an exterior quality and stability had comparatived. But, be like in production corner spare parts pentagonal when, appeared frit Fu caboodle spends incongruous circumstance high, this shows the technique that uses Fu of groovy laser frit merely and parameter are the quality that assures metallic spare parts hard. Laser frit Fu is made is one arrives to make a process of the face stage by stage to the line by the dot, the production of every spare parts finishs the overlay that involves a lot of frit cladding, consequently the craft of laser frit Fu especially the stability of craft is crucial, the crucial influencing factor that makes to frit Fu only if the stability that the element such as height of Fu of speed of Fu of bath temperature, frit, frit executes ability of real time closed-loop control to assure whole production process and the high accuracy of production spare parts. Graph the 1 simple metal wall that uses LRFM technology to make and Nextpage2 of canister shape spare parts.
The microcosmic organization of metallic spare parts used SEM to undertake an analysis to making the cross section of sample and vertical section micromechanism, if pursue,2 are shown. The microcosmic organization that stimulates optical production spare parts is a kind of very tiny model caky branch brilliant, the organization is very compact and flawless with apparent stomatic blemish (graph 2a) . Means goes against thermal current direction and grow with extension, the organization that builds deliver a child to grow an area (graph 2b) compares frit cladding itself (graph 2c) appreciably is bulky. The organization of cross section and vertical section case are similar. Graph the microcosmic organization of 2 laser production sample 3.
The composition analysis of production spare parts uses SEM line scanning to distributing to the composition of sample spare parts undertook an analysis. Graph 3a is Ni element edge the line among two overlap region and frit cladding distributings graph. Even if sectional line distributings,graph 3b is Ni element and sample of Cr element edge graph. Two graphs show each element distributings mediumly in the spare parts very even. Graph 3 elements distributing 4.
The hardness profile of spare parts of production metal of Fu of hardness profile frit also is quite even, if pursue,4 are shown. Graph 4 hardness profile 5.
Tensile strength experiment cut the frit Fu wall below to have tensile strength test to going up from substrate, the greatest tensile strength is 451MPa and 454MPa respectively, the metallic powder intensity of prep above demarcate. 6.
Discussion LRFM is a kind of production technology that is based on laser frit Fu, its shape ability suffers a lot of element effects with production precision, include craft parameter (like speed of diameter of laser power, facula, scanning, rate sending pink) , the geometrical appearance of frit Fu spare parts, multilayer the change that takes rate of Fu of received temperature feature, frit. These elements can affect the stability of frit Fu process, the geometrical figure that affects frit Fu part directly thereby, production quality and production precision. To assure the stability of frit Fu process, must be opposite main influencing factor, if make the temperature in the process accumulate the distance of the change of appearance of geometry of effect, bath and nozzle and frit Fu surface to wait, realize closed-loop control. What conclusion is based on laser frit Fu is fast and flexible the part of clean figuration metal that production technology can make a complete density, full strength. Of LRPM technology shape ability and the stability that production precision basically relies on process of laser frit Fu, ask to realize the closed-loop control of pair of critical process parameter thereby. CNC Milling