Background technology
The general principle of selective laser melting (SLM) molding technology (Selectivelasermelting, SLM) is baseMake 3 d part in layering manufacture, the mode that is layering. Its technological process is as follows: (1) firstThe three-dimensional CAD model of part is carried out to hierarchy slicing, obtain the profile information of every layer of part; (2) controlSystem processed is planned technique and scanning pattern; (3) dust feeder powder feeding, power spreading device is in mouldingLay the powder that one deck and slice thickness are equally thick in cylinder; (4) laser is selected according to control system instructionProperty ground melting powder; (5) height of a bed thickness of moulding cylinder piston decline; (6) repeat (3)~(5),Until complete the manufacture of part. SLM technology is compared with the advantage of classical production process can be directly without mouldNear-net-shape has the part of the features such as labyrinth, materials with high melting point or difficult-to-machine material, institute's mouldingParts size precision is high and mechanical property is excellent.
About SLM equipment and process, have at present some patents both at home and abroad, according to equipment configurationCan be divided into two kinds with process: Yi Zhongshi: cover galvanometer+1,1 laser instrument+1 moulding cylinder, allusion quotationThe example of type is as United States Patent (USP) " PROCESSANDDEVICEFORPRODUCINGASHAPEDBODYBYSELECTIVELASERMELTING " (patent No.:US7047098). This SLM equipment only contains a set of galvanometer and a station, in the work of moulding cylinderPlug decline and give/spread powder during, laser is idle, namely " leaves unused ". This equipment isThe major product of current SLM, each company is only slightly different on powder feeding structure and power spreading device. This type ofSLM equipment is limited to field sweep scope and the required precision of galvanometer system, and processing breadth is generally no more than250mm × 250mm, cannot moulding large-scale part, the utilization rate of laser and the deposition efficiency of equipmentAll lower.
Another kind is: and N platform laser instrument+N cover galvanometer+1 moulding cylinder (N is integer, N > 1), as stateIt is (open that interior patent documentation " is directly manufactured the precinct laser fusion rapid molding equipment of large parts "Number: CN102266942A). The main feature of this class device is to adopt one or several and even tens ofLaser instrument, the corresponding a set of galvanometer of every laser instrument, all galvanometer system splicing, realizes large formatBe shaped. This apparatus and method, can prepare large-scale part, also can manufacture multiple of the same race simultaneouslyThe small size part of material. This class equipment, owing to having adopted multi-station laser, therefore deposition efficiency canTo increase substantially. While making at the same time multiple small size part, also owing to having reduced the clear powder time,Thereby deposition efficiency improves more. But such equipment is still single station, in the work of moulding cylinderPlug declines and send/spread in the powder period, and laser is still " leaving unused ", and therefore the utilization rate of laser instrument is complied withSo not high, usefulness does not obtain maximum performance.
Laser instrument is a critical component that price is high in SLM equipment, is the master of device fabrication costWant part. In process of production, the running cost of laser instrument and depreciation cost are all SLM forming partsThe important component part of manufacturing cost. For single station, moulding cylinder inner carrier decline orSend/spread in the powder time, laser instrument must be " leaving unused ", causes the waste of resource. If particularlyAdopt high power laser light, multilayer, repeatedly continuous sweep be shaped after, due to powder bed accumulation of heatGreatly, easily cause bath temperature too high, the setting rate of part is reduced. For this reason, must be coolingA period of time, after being cooled down, molten bath carries out again the scanning of lower a time, make " the spare time of laser instrumentPut " time is longer. Therefore,, in SLM forming process, moulding cylinder piston declines, send/spread the powder timeAnd the laser instrument that causes cool time of molten bath time of " leaving unused " is considerable.
Summary of the invention
The invention provides efficient a kind of precinct laser fusion rapid molding equipment, object is to improve and swashsThe deposition efficiency of the utilization rate of light device and SLM equipment.
A kind of precinct laser fusion rapid molding equipment provided by the invention, is characterized in that this equipmentComprise control system, laser instrument, light-conducting system and station, laser instrument is one or more, and every is swashedAt least two stations of light device correspondence;
Control system is for controlling the motion of each station inner assembly and the output shape of described laser device laserState.
Each station all comprises a set of laser formation module and corresponding scanning system and servicing unit thereof.
Laser formation module is the forming cavity in SLM device, and scanning system is by least a set of galvanometer systemComposition; Servicing unit is used for realizing the required preheating of SLM moulding or/and gas purification circulation.
The laser being sent by laser instrument arrives respectively the scanning of each corresponding station after light-conducting systemSystem, then by corresponding laser formation module, powder is carried out to laser fusion, each station hocketsPowder feeding, paving powder, scanning and lifting, realize the non-stop run of laser instrument, to improve the utilization of laserRate.
As the improvement of technique scheme, described laser formation module includes optical window, powder feedingMechanism, power spreading device, moulding cylinder, recovery cylinder, substrate and piston; Optical window is positioned at moulding cylinderTop, is provided with lifting piston in moulding cylinder, substrate level is arranged on piston, and powder feeding mechanism is installedA side above moulding cylinder, power spreading device is positioned at a side of moulding cylinder, reclaims cylinder and is positioned at moulding cylinderOpposite side. Laser beam after scanning system focuses on arrives the powder bed table of moulding cylinder via optical windowFace, the upper surface of moulding cylinder casing wall is the benchmark of paving powder, power spreading device can be at the upper surface of moulding cylinderMotion, and taking the upper surface of moulding cylinder as benchmark paving powder. Substrate is the growth substrate of forming part; ?Before paving powder, first decline under the control system control height of a slice thickness of piston, then powder feeding machineStructure powder feeding, power spreading device paving powder, unnecessary powder reclaims by reclaiming cylinder.
The present invention proposes the thinking of a multistation SLM equipment, that is: adopt the SLM of multistationLathe, shares a lasing light emitter, decline or give at the moulding cylinder piston of a station/while spreading powder,Laser is processed processing at other station, thereby the utilization rate of laser instrument is increased substantially, largeThe large manufacturing cost that reduces forming part. This multistation is shaped not only can solve in forming process and swashs" leaving unused " problem of light device, when can also carrying out the even multiple different materials part of multiple partsPreparation, this will improve the deposition efficiency of SLM greatly, reduces the manufacturing cost of forming part, suitable especiallyClosing the complicated hardware of small lot, many kinds produces.
Compare with method with existing SLM equipment, the present invention has following characteristics:
(1) the present invention adopt 1 or several laser instruments mate multiple stations, according to use feelingsCondition, the station number of a laser instrument coupling is greater than 1, i.e. a laser instrument coupling multistation;
(2) the corresponding galvanometer of each station can be a set of can be also many covers;
(3) adopt the present invention, can make laser instrument always in use state, at a stationMoulding cylinder decline and send/spread in the powder time, laser instrument no longer " leaves unused ", but carries out at other stationScanning, therefore the utilization rate of laser improves greatly, can be even full-time;
(4) the present invention can increase interlayer trace interval by increasing station, is adopting Gao GongRate and do not reduce under the condition of laser instrument utilization rate and reduce the thermal accumlation in forming part process, avoidsThe generation of various related defects.
Detailed description of the invention
Existing SLM equipment is all single station, and its production procedure mainly comprises powder feeding, paving powder, swashsDegradation operation under optical scanning and moulding cylinder piston, these operations successively repetitive cycling until whole part is completeBecome. During this period, laser instrument only uses in laser scanning link, all leaves unused At All Other Times. AndDifference of the present invention, laser instrument is all the time in scanning mode. For a certain station, its production procedureStill powder feeding, paving powder, laser scanning and moulding cylinder piston under degradation operation repetitive cycling successively untilWhole part completes. But between several stations, there is certain hour difference in each production procedure.Taking four stations as example, at a time, the powder feeding of A station, B station paving powder, the laser scanning of C station,D station moulding cylinder piston declines. In the next moment, A station paving powder, the laser scanning of B station,C station moulding cylinder piston declines, the powder feeding of D station. So one after the other, until the part of four stationsAll moulding is complete. Therefore laser will be all the time in use state---scanning. Laser by several stations in turnUse, therefore the utilization rate of laser instrument is very high, or even full-time. Another of this invention is excellentGesture is, when laser beam is in several station mixed sweep, makes the powder bed of each station cooling if having time,Can, because of adopting high power laser light scan frequency too high and overheated, not cause metallurgical imperfection.
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described further. Need explanation at this, be used for helping to understand the present invention for the explanation of these embodiments, but do not form thisBright restriction. In addition involved technology spy in each embodiment of described the present invention,Do not levy as long as do not form each other conflict and just can mutually combine.
The present invention, by the manufacturing procedure of the each station of control system control, makes the light beam timesharing of laser instrumentAct on different stations, make laser instrument in running order all the time, until the part of all stations addsWork completes.
Equipment building process of the present invention is by conventional part material to be processed, size, structure etc.Judgement carrys out choose relevant parameter, and then estimates and design best equipment assembled scheme.
As shown in Figure 1, the one of precinct laser fusion rapid molding equipment involved in the present invention is concreteEmbodiment comprises control system 1, laser instrument 2, light-conducting system 3 and at least two stations 4, eachStation comprises a set of laser formation module 5 and corresponding scanning system 6 and servicing unit 7 thereof. Auxiliary dressPut 7 for realizing a kind of or several of SLM moulding required such as preheating, gas purification, circulation etc.Plant function.
Control system 1 contains and station 4 some motion control cards one to one, motion control clampingReceive the motion of each station 4 inner assemblies of signal controlling and the output state of each laser device laser. Laser instrument 2Can be one or many, can be identical or different kind and model.
As shown in Figure 2, scanning system 6 is made up of galvanometer system 8, and a set of scanning system 6 is passableBeing made up of a set of galvanometer system, can be also that number cover galvanometer system is assemblied to form, and laser instrument 2 sendsLaser after light-conducting system 3, arrive the laser entrance of each galvanometer in scanning system 6, control system 1Control every bundle Laser Time Sharing and enter on different station corresponding with it galvanometer system 8.
Light-conducting system 3 can be optical fiber group, the reflection light-conducting system that also can be formed by optical mirror slip,Or even both combinations, or any one can import laser the optical texture of station.
Whole equipment must comprise at least two stations 4, and each station is going of conventional SLM equipmentExcept the part after laser instrument and light-conducting system, each station comprises laser formation module 5 and scanning systemSystem 6, laser formation module 5 is corresponding one by one with scanning system 6.
As shown in Figure 3, laser formation module 5 is the forming cavity in conventional SLM device, conventionally bagDraw together optical window 9, powder feeding mechanism 10, power spreading device 11, moulding cylinder 12, reclaim cylinder 13, substrate14 and piston 15. If contain preheating device in servicing unit 7, preheating device is arranged on moulding cylinder12 bottom or around.
The laser that laser instrument 2 sends arrives scanning system 6 after light-conducting system 3, through scanning systemAfter 6 focusing, warp arrives the moulding cylinder that is confined to die cavity 12 with atmosphere protection function by optical window 9Powder bed surface, the upper surface of moulding cylinder 12 casing walls is the benchmark of paving powder, power spreading device 11 can beThe upper surface motion of moulding cylinder, and taking the upper surface of moulding cylinder 12 as benchmark paving powder. In moulding cylinder 12Have a piston that can accurately move up and down 15, substrate 14 levels are arranged on piston 15, substrate 14It is the growth substrate of forming part. Before paving powder, piston 15 first declines one under control system controlThe height of slice thickness, then powder feeding mechanism 10 powder feedings, power spreading device 11 spreads powder. In this process,Unnecessary powder reclaims by reclaiming cylinder 13. Should be noted that, above-mentioned laser formation module 5 is passableIt is the structure of any one forming cavity in existing SLM equipment.
The laser of should making rational planning for before precinct laser fusion rapid molding involved in the present invention is equipped in and establishesThe structure of the quantity of device 2, station 4 and light-conducting system 3, laser formation module 5, scanning system 6.Taking into full account under the size and efficiency of conventional forming part, reducing as far as possible the quantity of laser instrument 2;And reduce as far as possible station 4 or shake under the prerequisite of the production efficiency of and requirement the highest in laser utilization rateThe quantity of mirror system 8, optimum organization module, avoids occurring that various device quantity do not mate and some dressPut the too idle situation of appearance. Work in precinct laser fusion rapid molding equipment involved in the present inventionThe structure of quantity, the laser formation module of position and with the selection of the integrated mode of laser instrument can be according toFollowing steps:
(1) material, size and the structure of clearly conventional part to be processed, according to material category in techniqueIn parameter library, select rational machined parameters, select the forming cavity of laser formation module according to accessory sizeThe size of body, according to the volume ratio of design of part estimation part and molding space.
(2) calculate the ratio A of non-laser scanning time and laser scanning time. Being set as die cavity is that the length of side is aSquare, adopting unidirectional paving powder and paving powder speed is V, the forming cavity length of side that paving powder stroke is twice;Laser scanning speed is υ, and distance between centers of tracks is d, and the volume ratio of part and molding space is η, single scanningThe processing breadth of system specialization is S. Paving powder time TPFWith laser scanning time TSMAvailable formula respectively(1), (2) estimation.
If piston fall time be t1, the powder feeding time is t2, when non-laser scanning time and laser scanningBetween ratio A can be estimated by formula (3).
For ensureing the making full use of of laser instrument, should exceed twice the laser scanning total time of all stationsThe paving powder time, therefore the quantity of station should be [2A+1]. There are the feelings of multiple galvanometer systems at single stationThe next volume ratio η that need to suitably improve according to the structure of part part and molding space of condition, with reduce because ofThe laser scanning time estimation error that the high volume ratio of regional area causes. For processing breadth not for justSquare precinct laser fusion rapid molding equipment also can be estimated according to corresponding computation schema. ForAvoid laser in process, to cause amount of localized heat concentrate and produce as scarce in the processing such as pore, distortionFall into, and the heat accumulation producing causes stress to concentrate to weaken rapid solidification effect and reduce mechanical property, alsoCan suitably increase the quantity of station, increase the time interval of adjacent layer laser scanning.
(3) the individual station of reasonable Arrangement [2A+1], makes it not interfere with each other in operation, process.
(4) laser that all laser instruments send is along light-conducting system timesharing input [2A+1] individual station. This canTo adopt the method for laser instrument band multi-channel optical fibre, also can adopt hard light path or spectroscopical methodRealize. If the scanning system layout of each station is identical, should avoid same laser instrument correspondence to exist as far as possibleGalvanometer system in different station, like this can be in the small lot batch manufacture of part in similar positionIncrease the utilization rate of laser instrument by making rational planning for of control system.
The optimization of each station process sequence and each in the process of precinct laser fusion rapid molding equipmentThe optimization of laser instrument leaded light output order is the important method that improves laser instrument effective rate of utilization in the present inventionOne of. In each station forming process, mainly comprise that powder feeding, paving powder, laser scanning and piston decline fourOperation, and laser device laser leaded light order mainly refers to that each laser arrives the sequencing of each galvanometer system.In precinct laser fusion rapid molding equipment, each operation and laser leaded light order are by control system 1Unified planning, for avoiding occurring that operation confusion must abide by the principle:
(1) in the station under powder feeding, paving powder, piston decline operation, can not carry out laser scanning operation.
(2) station that first completes paving powder operation has the priority of carrying out laser scanning operation.
(3) the laser scanning operation of all galvanometer systems of a certain station can be carried out this station after finishingNext operation.
(4) a certain station galvanometer system completes after laser scanning operation, the laser instrument that it is correspondingSwitch to the light-conducting system in other station, carry out laser scanning operation, without waiting for current workThe all scanning system end-of-jobs in position.
(5) the laser scanning operation of each station can be carried out simultaneously, but has swashing of a station at leastOptical scanning operation is staggered the time, to ensure the high usage of laser.
The control flow of control system as shown in Figure 4. Be mainly:
Laser instrument numbering is represented with L, and station numbering represents with N, N station use theThe galvanometer system of L platform laser instrument Output of laser is expressed as (N, L).
Send, spread after powder operation when N station completes, all galvanometer systems of this station are to control systemSend request signal, galvanometer system (N, 1), (N, 2) ... (N, L) ... wait control system is rungShould, under in equipment, the request signal of all galvanometer systems distributes according to request time and is arranged in separatelyLaser instrument is treated in response stack.
Control system is treated putting in order of request signal in response stack according to L platform laser instrument, adoptsThe selection strategy of first in first out is made response to the request signal of each station galvanometer system, and controls and sendThe galvanometer system of this request signal completes laser scanning operation. L platform laser instrument completes after current taskSend request signal, control system is distributed the laser scanning operation of the next request signal in storehouseGive it.
Galvanometer system (N, L) sends request letter to control system after executing laser scanning operation immediatelyNumber, request signal is assigned in the paving powder signal set of the each station of N, when N is collected in this setOn individual station, after the request signal of all galvanometer systems, this station of control system control send, spreads powder operationComplete.
If all not collecting complete and current nothing paving powder operation, the paving powder signal set of all stations carrying out,Control system is adjusted stacking order, preferentially spreads the station residue that in powder signal set, signal is maximumThe laser scanning operation of waiting galvanometer system.
Control system constantly receives request signal and is delivered to each laser instrument and treats response stack and each station pavingPowder signal set, and according to the feedback signal of laser instrument and station, each executing agency is sent to instruction and completeLaser scanning operation and send, spread powder operation.
The present invention is not only confined to above-mentioned detailed description of the invention, and persons skilled in the art are according to thisBright disclosed content, can adopt other multiple detailed description of the invention to implement the present invention, therefore, everyAdopt project organization of the present invention and thinking, do some simple designs that change or change, all fall intoThe scope of protection of the invention.