Background technology
The basic principle of selective laser melting (SLM) molding technology (Selective laser melting, SLM) is to make 3 d part based on layering manufacture, the mode that is layering.Its technological process is as follows: (1) first carries out hierarchy slicing to the three-dimensional CAD model of part, obtains the profile information of every layer of part; (2) control system is planned technique and scanning pattern; (3) dust feeder powder feeding, power spreading device is laid the powder that one deck and slice thickness are equally thick in moulding cylinder; (4) laser is according to control system instruction melting powder optionally; (5) height of a bed thickness of moulding cylinder piston decline; (6) repeat (3)~(5), until complete the manufacture of part.SLM technology is directly without mould near-net-shape, to have the part of the features such as labyrinth, materials with high melting point or difficult-to-machine material compared with the advantage of classical production process, and institute's forming part dimensional accuracy is high and mechanical property is excellent.
About SLM equipment and process, have at present some patents both at home and abroad, according to device structure and process, can be divided into two kinds: a kind of: cover galvanometer+1,1 laser instrument+1 moulding cylinder, typical example is as United States Patent (USP) " PROCESS AND DEVICE FOR PRODUCING ASHAPED BODY BY SELECTIVE the LASERMELTING " (patent No.: US7047098).This SLM equipment only contains a set of galvanometer and a station, at the piston of moulding cylinder, decline and give/spread powder during, laser is idle, namely " leaves unused ".This equipment is the major product of current SLM, and each company is only slightly different on powder feeding structure and power spreading device.This type of SLM equipment is limited to field sweep scope and the required precision of galvanometer system, and processing breadth is generally no more than 250mm * 250mm, cannot moulding large-scale part, and the utilization rate of laser and the deposition efficiency of equipment are all lower.
Another kind is: (N is integer to N platform laser instrument+N cover galvanometer+1 moulding cylinder, N>1), as the domestic patent documentation (publication number: CN102266942A) of " directly manufacturing the precinct laser fusion rapid molding equipment of large parts ".The main feature of this class device is to adopt one or several and even tens of laser instruments, every corresponding a set of galvanometer of laser instrument, and all galvanometer system splicings, realize the shaping of large format.This apparatus and method, can prepare large-scale part, also can manufacture the small size part of a plurality of same material simultaneously.This kind equipment, owing to having adopted multi-station laser, so deposition efficiency can increase substantially.While making at the same time a plurality of small size part, also owing to having reduced the clear powder time, thereby deposition efficiency improves more.But this kind equipment is still single station, at the piston of moulding cylinder, decline and send/spread powder in the period, laser is still " leaving unused ", so the utilization rate of laser instrument is still not high, usefulness does not obtain maximum performance.
Laser instrument is a critical component that price is high in SLM equipment, is the chief component of device fabrication cost.In process of production, the running cost of laser instrument and depreciation cost are all the important component parts of SLM forming part manufacturing cost.For single station, at moulding cylinder inner carrier, decline or send/spread powder in the time, laser instrument must be " leaving unused ", causes the waste of resource.If particularly adopt high power laser light, in multilayer, after repeatedly continuous sweep is shaped, because powder bed accumulation of heat is large, easily cause bath temperature too high, the setting rate of part is reduced.For this reason, must cooling a period of time, after being cooled down, molten bath carries out again the scanning of lower a time, and make " leaving unused " time of laser instrument longer.Therefore,, in SLM forming process, the laser instrument that moulding cylinder piston declines, send/spread powder time and molten bath to cause cool time time of " leaving unused " is considerable.
Utility model content
The utility model provides efficient multistation laser selective melting former, and object is to improve the utilization rate of laser instrument and the deposition efficiency of SLM equipment.
A kind of precinct laser fusion rapid molding equipment that the utility model provides, is characterized in that, this device comprises control system, laser instrument, light-conducting system and station, and laser instrument is one or more, at least two stations of every laser instrument correspondence;
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 comprised of at least a set of galvanometer system; Servicing unit is used for realizing the required preheating of SLM moulding or/and gas purification circulation;
Control system is connected with laser instrument, laser formation module, scanning system and the servicing unit signal of telecommunication respectively, to control the motion of laser formation module, scanning system and servicing unit and the output state of described laser device laser;
The laser being sent by laser instrument arrives respectively the scanning system of each corresponding station after light-conducting system, by corresponding laser formation module, powder is carried out to laser fusion again, each station hocket powder feeding, paving powder, scanning and lifting, realize the non-stop run of laser instrument, to improve the utilization rate of laser.
As the improvement of technique scheme, described laser formation module includes optical window, powder feeding mechanism, power spreading device, moulding cylinder, recovery cylinder, substrate and piston; Optical window is positioned at the top of moulding cylinder, and lifting piston is installed in moulding cylinder, and substrate level is arranged on piston, and powder feeding mechanism is arranged on a side of moulding cylinder top, and power spreading device is positioned at a side of moulding cylinder, reclaims the opposite side that cylinder is positioned at moulding cylinder.Laser beam after scanning system focuses on arrives the powder bed surface of moulding cylinder via optical window, the upper surface of moulding cylinder casing wall is the benchmark of paving powder, and power spreading device can be in the upper surface motion of moulding cylinder, and to take the upper surface of moulding cylinder be benchmark paving powder.Substrate is the growth substrate of forming part; Before paving powder, first decline under control system the is controlled height of a slice thickness of piston, then powder feeding mechanism powder feeding, power spreading device paving powder, unnecessary powder reclaims by reclaiming cylinder.
The utility model proposes the thinking of a multistation SLM equipment, that is: adopt the SLM lathe of multistation, share a lasing light emitter, at the moulding cylinder piston of a station, decline or give/while spreading powder, laser is processed processing at other station, thereby the utilization rate of laser instrument is increased substantially, greatly reduce the manufacturing cost of forming part.This multistation is shaped not only can solve " leaving unused " problem of laser instrument in forming process, preparation when can also carry out even a plurality of different materials part of a plurality of parts, this will improve the deposition efficiency of SLM, reduce the manufacturing cost of forming part, the complicated hardware that is particularly suitable for small lot, many kinds is produced.
Compare with existing SLM equipment, the utlity model has following characteristics:
(1) 1 of adopting of the utility model or several laser instruments mate a plurality of stations, and according to service condition, 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 utility model, can so that laser instrument always in use state, the moulding cylinder at a station declines and send/spread powder in the time, laser instrument no longer " leaves unused ", but scan at other station, so the utilization rate of laser improves greatly, can be even full-time;
(4) the utility model can increase interlayer trace interval by increasing station, adopting high power and not reducing under the condition of laser instrument utilization rate and reduce the thermal accumlation in forming part process, avoids the generation of various related defects.
The specific embodiment
Existing SLM equipment is all single station, its production procedure mainly comprise powder feeding, paving powder, laser scanning and moulding cylinder piston under degradation operation, these operations successively repetitive cycling until whole part complete.During this period, laser instrument only uses in laser scanning link, all leaves unused At All Other Times.And the utility model is different, laser instrument is all the time in scanning mode.For a certain station, still powder feeding of its production procedure, paving powder, laser scanning and moulding cylinder piston under degradation operation repetitive cycling successively until whole part complete.But between several stations, there is certain hour difference in each production procedure.Take 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.At the next one constantly, A station spreads powder, the laser scanning of B station, and C station moulding cylinder piston declines, the powder feeding of D station.So one after the other, until the part of four stations all moulding is complete.Therefore laser will be all the time in use state---scanning.Laser is used in turn by several stations, so the utilization rate of laser instrument is very high, or even full-time.Another advantage of this invention 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 utility model is described further.At this, it should be noted that, for the explanation of these embodiments, be used for helping to understand the utility model, but do not form restriction of the present utility model.In addition,, in each embodiment of described the utility model, involved technical characterictic just can not combine mutually as long as do not form each other conflict.
The utility model is controlled the manufacturing procedure of each station by control system, make the light beam timesharing of laser instrument act on different stations, makes laser instrument in running order all the time, until the part of all stations machines.
Equipment building process of the present utility model is by the judgement of conventional part material to be processed, size, structure etc. is carried out to choose relevant parameter, and then estimates and design best device combination scheme.
As shown in Figure 1, a kind of specific embodiment of the precinct laser fusion rapid molding equipment that the utility model is related comprises control system 1, laser instrument 2, light-conducting system 3 and at least two stations 4, and each station comprises a set of laser formation module 5 and corresponding scanning system 6 and servicing unit 7 thereof.Servicing unit 7 is for realizing required one or more functions such as preheating, gas purification, circulation etc. of SLM moulding.
Control system 1 contains and station 4 some motion control cards one to one, and motion control card receives the motion of each station 4 inner assemblies of signal controlling and the output state of each laser device laser.Laser instrument 2 can be one or many, can be identical or different kind and model.
As shown in Figure 2, scanning system 6 is comprised of galvanometer system 8, a set of scanning system 6 can be comprised of a set of galvanometer system, also can be that number cover galvanometer system is assemblied to form, the laser that laser instrument 2 sends arrives the laser entrance of each galvanometer in scanning system 6 after light-conducting system 3, and control system 1 is controlled every bundle Laser Time Sharing and entered 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 the removal laser instrument of conventional SLM equipment and the part after light-conducting system, and each station comprises laser formation module 5 and scanning system 6, and 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, generally includes optical window 9, powder feeding mechanism 10, power spreading device 11, moulding cylinder 12, reclaims cylinder 13, substrate 14 and piston 15.If contain preheating device in servicing unit 7, preheating device is arranged on the bottom of moulding cylinder 12 or around.
The laser that laser instrument 2 sends arrives scanning system 6 after light-conducting system 3; through scanning system 6, focus on by arrived the powder bed surface of the moulding cylinder that is confined to die cavity 12 with atmosphere protection function by optical window 9; the upper surface of moulding cylinder 12 casing walls is the benchmark of paving powder; power spreading device 11 can be in the upper surface motion of moulding cylinder, and to take the upper surface of moulding cylinder 12 be benchmark paving powder.In moulding cylinder 12, have a piston that can accurately move up and down 15, substrate 14 levels are arranged on piston 15, and substrate 14 is growth substrate of forming part.Before paving powder, first decline under control system the is controlled height of a slice thickness of piston 15, then powder feeding mechanism 10 powder feedings, power spreading device 11 paving powder.In this process, unnecessary powder reclaims by reclaiming cylinder 13.Should be noted that, above-mentioned laser formation module 5 can be the structure of any one forming cavity in existing SLM equipment.
Should make rational planning for before the establishing structure of the quantity of laser instrument 2, station 4 and light-conducting system 3, laser formation module 5, scanning system 6 of the related precinct laser fusion rapid molding equipment of the utility model.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 under the prerequisite of and the production efficiency that requires the highest in laser utilization rate, reducing as far as possible the quantity of station 4 or galvanometer system 8, optimum organization module, avoids occurring that various device quantity is not mated and too idle situation appears in some device.The quantity of station in the related precinct laser fusion rapid molding equipment of the utility model, the structure of laser formation module and with the selection of the integrated mode of laser instrument can be according to following steps:
(1) material, size and the structure of clearly conventional part to be processed, according to material category, in technological parameter storehouse, select rational machined parameters, according to accessory size, select the size of the molding cavity of laser formation module, 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 the square of a, and 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, and the processing breadth that single scanning system limits is S.Paving powder time T
pFwith laser scanning time T
sMavailable formula (1), (2) estimation respectively.
If piston fall time be t
1, the powder feeding time is t
2, the non-laser scanning time can be estimated by formula (3) with the ratio A of laser scanning time.
For guaranteeing making full use of of laser instrument, the laser scanning total time of all stations should surpass the paving powder time of twice, so the quantity of station should be [2A+1].At single station, have that the situation of a plurality of galvanometer systems is next need to suitably improve according to the structure of part the volume ratio η of part and molding space, the laser scanning time estimation error causing with the high volume ratio reducing because of regional area.For processing breadth, for foursquare precinct laser fusion rapid molding equipment, also can not estimate according to corresponding computation schema.For fear of laser, in process, cause amount of localized heat to concentrate and produce as manufacturing deficiencies such as pore, distortion, and the heat accumulation producing causes stress to concentrate reduction rapid solidification effect and reduces mechanical property, also can 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 can adopt laser instrument band multi-channel optical fibre, also can adopt hard light path or spectroscope to realize.If the scanning system layout of each station is identical, should avoid the galvanometer system of same laser instrument correspondence in different station in similar position as far as possible, can in the small lot batch manufacture of part, by making rational planning for of control system, increase the utilization rate of laser instrument like this.
In the process of precinct laser fusion rapid molding equipment, the optimization of the optimization of each station process sequence and each laser instrument leaded light output order is in the utility model, to improve one of important feature of laser instrument effective rate of utilization.In each station forming process, mainly comprise powder feeding, paving powder, laser scanning and four operations of piston decline, 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 1 unified 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 the next operation of this station after finishing.
(4) a certain station galvanometer system completes after laser scanning operation, and its corresponding laser instrument switches to the light-conducting system in other station, carries out laser scanning operation, without waiting for all scanning system end-of-jobs of current station.
(5) the laser scanning operation of each station can be carried out simultaneously, but has at least the laser scanning operation of a station to stagger the time, to guarantee 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 is numbered and with N, is represented, N station used the galvanometer system of L platform laser instrument Output of laser to be expressed as (N, L).
When N station completes, send, spread after powder operation, the all galvanometer systems of this station send request signal to control system, galvanometer system (N, 1), (N, 2) ... (N, L) ... wait control system response, in equipment, the request signal of all galvanometer systems distributes according to request time and is arranged in affiliated laser instrument separately and treats in response stack.
Control system is treated putting in order of request signal in response stack according to L platform laser instrument, adopts the selection strategy of first in first out to make response to the request signal of each station galvanometer system, and controls the galvanometer system that sends this request signal and complete laser scanning operation.L platform laser instrument sends request signal after completing current task, and control system is distributed to it by the laser scanning operation of the next request signal in storehouse.
Galvanometer system (N, L) to control system, send request signal immediately after executing laser scanning operation, request signal is assigned in the paving powder signal set of each station of N, when this set is collected after the request signal of all galvanometer systems on N station, control system is controlled this station and is sent, spreads powder operation and complete.
If the paving powder signal set of all stations is all collected and complete and currently do not carried out without paving powder operation, control system is adjusted stacking order, preferentially spreads the laser scanning operation that station that in powder signal set, signal is maximum remains waiting galvanometer system.
Control system constantly receives request signal and is delivered to each laser instrument and treats response stack and each station paving powder signal set, and according to the feedback signal Dui Ge executing agency of laser instrument and station, sends instruction and complete laser scanning operation and send, spread powder operation.
The utility model is not only confined to the above-mentioned specific embodiment; persons skilled in the art are according to the disclosed content of the utility model; can adopt other multiple specific embodiment to implement the utility model; therefore; every employing project organization of the present utility model and thinking; do some simple designs that change or change, all fall into the scope of the utility model protection.