Additive Technology: hauj lwm, txhais, thiab daim ntawv thov nta kev. Additive technologies nyob rau hauv kev lag luam

3D-printing tshuab tau nkag tau rau hauv 1986, thaum lub tuam txhab 3D Systems tsim thawj tshwj xeeb tshuab luam ntawv - stereolithography tshuab, uas yog dav siv nyob rau hauv tus tiv thaiv kev lag luam. Tus thawj cov cav tov twb kim heev thiab cov kev xaiv ntawm cov khoom rau lub creation ntawm cov qauv yog tsawg. Lub ceev ceev txoj kev loj hlob ntawm peb-dimensional printing pib nrog txoj kev loj hlob ntawm kev tsim technology (CAD), kev laij leb thiab simulation (CAE) thiab machining (CAM). Thiab niaj hnub no nws yog ib qhov nyuaj rau nrhiav ib thaj tsam ntawm ntau lawm, uas yuav tsis tau siv 3D-printers: lawv yuav ua tau qhov chaw ntawm aircraft, spacecraft, submarines, cov cuab yeej, prostheses thiab kev cog hniav, hniav nyiaj hniav kub thiab lwm tus neeg. Lub zeem muag yog cuab kev - additive technology nyob rau hauv lub nyob ze yav tom ntej yuav tsum yog ib feem technology engineering .

Cov kev lub teb chaws ntawm lub ntiaj teb no yog kev koom tes nyob rau hauv lub 3D-sib xeem khiav. Piv txwv li, nyob rau hauv 2012 nyob rau hauv Yangstoune, Ohio, qhib lub National Innovation lub koom haum additive raug NAMII - tus thawj chaw ntawm additive technologies ntawm kaum tsib nyob rau hauv lub tebchaws United States. Tshuab park lub koom haum twb muaj 10 ntawm additive machines, peb cov uas yog lub feem ntau tshaj cov cav tov los mus tsim hlau qhov chaw.

Terminology thiab cais

Lub essence ntawm additive technology yog muab ntaub ntawv los mus tsim cov ntaub ntawv cov khoom los ntawm 3D qauv txheej los ntawm txheej. Qhov no yog sib txawv ntawm cov pa rho raug hom kev kawm implying machining - tshem cov ntaub ntawv uas los ntawm lub workpiece.

Additive technology yog txwv kom muab zais:

• los ntawm cov ntaub ntawv siv (ua kua, particulate, polymeric, hlau hmoov);
• los ntawm lub xub ntiag ntawm lub laser;
• los ntawm cov qauv ntawm cov kho cov txheej siv (thermal nyhuv, irradiation nrog ultraviolet los yog pom lub teeb, lub phau ntawv muaj pes tsawg leeg);
• los ntawm cov qauv ntawm cov tsim ntawm txheej.

Muaj ob txoj kev ntawm txoj kev ua ib txheej. Tus thawj yog hais tias cov thawj platform yog poured rau hauv lub hmoov khoom, nws yog partitioned los yog cov menyuam riam los ua ib tug txawm txheej ntawm kev kawm thickness ntawm cov khoom siv. Nws tshwm sim xim laser hmoov ua los lwm txoj kev hmoov raws ntawm compound (melting los yog gluing) raws li qhov tam sim no seem ntawm CAD-qauv. Siv cov kev faib dav hlau yog unchanged, thiab ib co ntawm cov hmoov tshua lawm. Qhov no yog hu ua xim synthesis raws li xim laser sintering, Yog hais tias ib tug compound ntawm lub cuab tam yog ib tug laser. Qhov thib ob hom muaj nyob rau hauv qhov ncaj deposition ntawm cov khoom nyob rau hauv lub summing point zog.

Lub koom haum ASTM, uas muaj kev lag luam qauv, cais lub 3D-additive technology rau hauv 7 pawg.

1. Extruding khoom. Nyob rau hauv constructing point ntawm preheated extruder noj cov tshuaj txhuam cov khoom siv, ib tug sib tov ntawm phau ntawv thiab cov hlau hmoov. Ua crude qauv yog muab tso rau hauv ib lub cub tawg kom tshem tawm cov phau ntawv thiab sinter hmoov - nyob rau hauv tib txoj kev raws li nws tshwm sim nyob rau hauv cov tshuaj technologies. Qhov no additive technology yog DVR nyob rau hauv lub trademarks MJS (Multiphase dav hlau solidification, multiphase dav hlau solidification), FDM (fused Deposition Modeling, simulation los ntawm layerwise Fusing), FFF (fused ntsiabteeb Fabrication, ntau lawm txoj kev fusing filaments).
2. Txau khoom. Piv txwv li, nyob rau hauv Polyjet siv quav ciab los photopolymer technology rau multi-dav hlau taub hau yog thov kom muaj ib point siv. Qhov no additive technology tseem hu ua Multi jetting khoom.
3. Sprinkling phau ntawv. Cov no muaj xws dav hlau number case-dav hlau-txhaj technology nyob rau hauv kev tsim kho ntawm lub cheeb tsam tsis qauv ntaub ntawv, ib tug phau ntawv tus neeg saib xyuas (additive raug technology ExOne).
4. Tiabsis cov ntawm daim ntawv cov ntaub ntawv. Lub tsev cov ntaub ntawv uas yog ib tug polymer zaj duab xis, hlau ntawv ci, ntawv thiab lwm tus neeg. Nws yog siv, piv txwv li, nyob rau hauv ultrasonic technology additive Fabrisonic. Nyias hlau paib yog welded ua ke los ntawm ultrasound, tom qab uas tshaj hlau yog muab tshem tawm los ntawm milling. Additive technology yog siv nyob rau hauv ua ke nrog rho.
5. Photopolymerization da dej. Lub tshuab siv kua modeling cov ntaub ntawv - photopolymer cob. Ib qho piv txwv yog lub SLA-technology tuam txhab 3D Systems thiab DLP-technology Envisiontec lub tuam txhab, Cov teeb Procession.
6. Melting ntawm cov ntaub ntawv uas nyob rau hauv ib tug pre-tsim txheej. Siv nyob rau hauv lub SLS-technology, siv raws li ib qhov chaw ntawm lub zog laser los yog thermal lub taub hau (SHS lub tuam txhab Blueprinter).
7. Direct zog summing mus txog rau lub qhov chaw ntawm kev tsim kho. Cov ntaub ntawv thiab lub zog noj mus rau nws lub melting point nyob rau hauv kev tsim kho ib txhij. Lub cev yog siv raws li ib tug ua hauj lwm lub taub hau, txawm peem rau nrog ib tug system rau muab lub zog thiab cov ntaub ntawv. Zog los nyob rau hauv daim ntawv ntawm ib tug concentrated beam ntawm electrons (Sciaky) los yog laser beam (pom, Optomec,). Tej zaum lub taub hau mounted rau hauv lub "txhais tes" ntawm tus neeg hlau.

Qhov no kev faib yog ntau npaum li cas hais txog cov intricacies ntawm additive technologies tshaj yav dhau los sawv daws yuav.

Liaj teb ntawm daim ntawv thov

additive technology ua lag luam nyob rau hauv lub muaj zog ntawm txoj kev loj hlob ua ntej ntawm lwm yam industries. Nws nruab nrab txhua xyoo kev loj hlob kwv yees li ntawm 27%, raws li IDC lub tuam txhab kwv yees tias los ntawm 2019 yuav npaum li cas los 26,7 billion nyiaj piv rau 11 billion nyob rau hauv 2015

Txawm li cas los, lub AT ua lag luam twb tsis tau mus qhia cov untapped tej zaum nyob rau hauv qhuav ntawm neeg cov khoom. Mus txog 10% ntawm lub tuam txhab uas muag ntawm tus nqi ntawm zus tau tej cov khoom noj nyob rau hauv nws cov qauv. Thiab tuam txhab uas muag tau twb noj no kev ua lag luam ya. Tab sis cov seem 90% mus rau hauv ntau lawm, yog li tsim daim ntawv sau npe rau ceev ceev raug ntawm cov khoom yuav ua tau lub ntsiab coj ntawm txoj kev loj hlob ntawm qhov kev lag luam nyob rau hauv lub neej yav tom ntej.

Nyob rau hauv 2014, lub kev faib ua feem ntawm sai qauv technologies nyob rau hauv kev ua lag luam ntawm additive txawm hais tias tsis, nws tseem nyob siab tshaj plaws - 35%, lub feem ntawm ntau lawm loj hlob ceev thiab hu ib tug 31% sib qhia nyob rau hauv cov creation ntawm cov cuab yeej tseem tseem nyob rau ntawm lub 25%, tus so yog lees paub los ntawm kev tshawb fawb thiab kev kawm ntawv.

By nyiaj txiag sectors, lub AT-tech daim ntaub ntawv faib raws li nram no:

• 21% - tej khoom noj khoom thiab electronics;
• 20% - tsheb;
• 15% - tshuaj, xws li kev kho hniav;
• 12% - aeronautics thiab qhov chaw raug kev lag luam;
• 11% - zus tau tej cov txhais tau tias ntawm ntau lawm;
• 8% - tub rog cov khoom;
• 8% - tsim;
• 3% - siv.

Amateurs thiab cov tub txawg

AT-tech kev ua lag luam yog muab faib mus rau hauv pib xyaum ua thiab kev. Amateur ua lag luam muaj xws li 3D-printers thiab lawv cov txij nkawm, uas muaj xws li kev pab cuam, consumables, software, thiab yog tsim rau ib tug neeg enthusiasts, kev kawm ntawv thiab visualization ntawm cov tswv yim thiab pab txhawb kev sib txuas lus ntawm thawj zaug rau theem ntawm txoj kev loj hlob ntawm cov tshiab ua lag ua luam.

Kev 3D-printers yeej kim heev thiab yog haum rau ncua tu tub tu kiv. Lawv muaj ib tug loj cheeb tsam ntawm kev tsim kho, kev kawm ntawv, cov neeg, kev cia siab, kev khwv qauv ntaub ntawv. Cov cav tov yog cov ntau ntau nyuab thiab yuav tsum tau cov kev loj hlob ntawm kev txawj ua hauj lwm nrog cov pab kiag li lawm lawv tus kheej, nrog qauv ntaub ntawv thiab software. Feem ntau, cov neeg teb xov tooj ntawm lub tshuab ua ib tug kev kws nyob additive yees nrog ntau dua cov kev kawm ntawv.

Additive Technology nyob rau hauv 2015

Raws li daim ntawv Wohlers Daim ntawv qhia txog 2015, 1988 thiab 2014 79 602 kev lag luam ntawm 3D-printers tau ntsia thoob ntiaj teb. . Nyob rau tib lub sij hawm 38,1% ntawm cov pab kiag li lawm raug nqi ntau tshaj li 5 txhiab US dollars yog los ntawm lub teb chaws USA, 9.3% - rau Nyiajpoom Teb, 9.2% - mus rau Tuam Tshoj, thiab 8.7% - lub teb chaws Yelemees. So ntawm lub ntiaj teb no ua ntej ntawm cov thawj coj. Los ntawm 2007 mus 2014 lub xyoo volume ntawm kev muag khoom ntawm desktop printers ntau zog los ntawm 66 mus 139 584 units. Nyob rau hauv 2014, 91,6% ntawm kev muag khoom lees paub rau desktop 3D-printers, thiab 8.4% - kom muaj daim ntawv sau npe ntawm additive manufacturing, lub profit los ntawm uas, li cas los xij, lees paub rau 86,6% ntawm tag nrho cov, los yog 1.12 billion US dollars tsis lus. Duab machines contented 173,2 lab US dollars thiab 13,4%. Nyob rau hauv 2016, kev muag khoom yuav tsum tau loj hlob mus rau $ 7.3 billion, nyob rau hauv 2018 - 12.7 billion, nyob rau hauv 2020 kev ua lag luam yuav mus txog $ 21,2 billion.

Raws li Wohlers, FDM-technology prevails, thaj txog 300 hom thoob ntiaj teb, txhua txhua hnub ntxiv tshiab kho. Ib txhia ntawm lawv yog muag xwb zos, ces nws yog heev yooj yim, yog hais tias tsis yooj yim sua, mus nrhiav cov lus qhia txog tus xov tooj ntawm manufactured hom 3D-printers. Nrog cog qoob loo peb yuav hais tias lawv muaj pes tsawg rau lub lag luam tsub kom nrog txhua dua hnub. Muaj yog ib tug zoo muaj ntau haiv neeg nyob rau hauv qhov loj thiab cov technologies siv. Piv txwv li, lub Berlin lub tuam txhab ua tau ib lub loj loj BigRep FDM-tshuab luam ntawv hu ua BigRep ONE.2 ntawm ib tug nqi ntawm 36 txhiab. Euro, muaj peev xwm ntawm printing khoom mus rau 900 x 1055 x 1100 hli nrog ib tug daws teeb meem ntawm 100-1000 microns, nrog ob tug extruders thiab muaj peev xwm siv ntaub ntawv sib txawv.

Kev lag luam - rau

Lub chaw ua dav hlua kev lag luam yog investing ntau nyob rau hauv zus tau tej cov additive. Kev siv cov additive technologies yuav txo noj nqos tau cov ntaub ntawv siv rau zus tau tej cov chaw los ntawm 10 lub sij hawm. Nws yuav tsum hais tias GE Aviation tuam txhab yuav txhua xyoo luam tawm 40 txhiab. Injectors. Thiab Airbus los ntawm 2018 lub tuam txhab twb mus sau txog li 30 tons ntawm qhov chaw rau ib lub hli. Lub tuam txhab notes lub muaj kev nruam ntej nyob rau hauv cov yam ntxwv ntawm manufactured qhov chaw nyob rau hauv xws li ib tug txoj kev raws li muab piv rau tsoos. Nws muab tawm hais tias lub bracket, uas yog tsim los rau 2.3 tons load, nyob rau hauv qhov tseeb, mas loads mus txog rau 14 tons thaum uas txo nws hnyav los ntawm ib nrab. Nyob rau hauv tas li ntawd, lub tuam txhab luam tawm cov ntsiab lus ntawm txhuas ntawv thiab roj connectors. Lub Airbus aircraft muaj 60 txhiab. Tej daim, sau lub 3D-tshuab luam ntawv Stratasys Fortus tuam txhab. Lwm yam tuam txhab uas muag Aerospace kev lag luam kuj siv additive raug technology. Cov lawv: Tswb nyoob hoom qav taub, Bae Systems, Bombardier, Boeing, Embraer, Honeywell Aerospace, General Dynamics, Northrop Grumman, Lockheed Martin, Raytheon, Pratt & Whitney, Yob-Royce thiab SpaceX.

Cov additive technologies twb siv nyob rau hauv qhov siv thiab ua ntau yam neeg cov khoom. Tuam txhab materialize, muab cov kev pab ntxiv manufacturing, kev koom tes nrog Hoet Eyeware nyob rau hauv qhov siv thiab ua cov tsom iav qhov muag kho thiab looj tsom iav dub. 3D qauv yog muab ib tug ntau yam ntawm huab cov kev pab cuam. Tsuas yog lub tuam txhab 3D Warehouse thiab Sketchup muaj 2.7 million kuaj. Tsis txhob nyob twj ywm nyob rau hauv lub tog thiab lub zam kev lag luam. RS Sau siv ib tug system uas ntsuas lub siab ntawm lub qab xib taws, mus sau ib tug neeg insoles. Designers yuav xyaum nrog bikinis, nkawm khau thiab dresses.

sai qauv

Nyob rau hauv sai qauv to taub lub creation ntawm tsab khoom nyob rau hauv lub shortest tau lub sij hawm. Nws yog ib tug ntawm lub ntsiab daim ntawv sau npe ntawm additive raug technologies. Tsab - yog ib hom ntawm cov khoom yuav tsum tau rau optimize tus duab ntawm lub ib feem ntawm nws cov kev ntsuam xyuas ntawm ergonomics, los ua ke pov thawj tuition thiab cov correctness ntawm layout kev daws teeb meem. Uas yog vim li cas lub yuav txo tau ntawm raug qhov chaw lub neej muaj peev xwm txo tau txoj kev loj hlob lub sij hawm. Tsis tas li ntawd, lub tsab peev xwm ua tau ib tug qauv tsim rau aerodynamic thiab hydrodynamic xeem los yog pov thawj functionality Certificate ntawm tsev neeg thiab kev kho mob cov khoom. Muaj ntau prototypes tsim raws li kev tshawb thiab tsim qauv nrog lub nuances nyob rau hauv lub configuration, xim thiab coloring thiab thiaj li nyob. D. Rau sai qauv siv pheej yig 3D-printers.

ceev ceev lawm

Lub additive technology nyob rau hauv lub lag luam muaj zoo zeem muag. Me scale lawm ntawm cov khoom uas complex geometry thiab ntawm tej ntaub ntawv ntau nyob rau hauv lub shipbuilding, hwj chim engineering, reconstructive phais thiab kev kho hniav tshuaj, Aerospace kev lag luam. Direct sau qoob los ntawm cov hlau cov khoom yog kev mob siab los ntawm nyiaj txiag expediency, raws li qhov no hom ntawm ntau lawm yog tsawg kim. Nrog rau kev siv ntawm additive technologies ua hauj lwm lub cev turbines thiab shafts, kev cog hniav thiab prostheses, spare qhov chaw rau tsheb thiab aircraft.

Cov kev loj hlob ntawm ceev ceev raug thiab contributed rau ib tug tseem ceeb nce nyob rau hauv lub xov tooj ntawm muaj hlau hmoov ntaub ntawv. Yog hais tias nyob rau hauv 2000 muaj 5-6 hom hmoov, tam sim no nws muaj ib tug ntau yam, ntau npaum li cas rau kaum ntawm kev los ntawm cov yam ntxwv steel rau zoo zoo nkauj tshooj thiab superalloys.

Pheej thiab additive technology nyob rau hauv mechanical engineering, qhov uas lawv muaj peev xwm yuav siv tau nyob rau hauv lub chaw ua khoom ntawm cov cuab yeej thiab cov cuab yeej rau series ntau lawm - inserts cov kev txhaj tshuaj molding tshuab, pwm, templates.

Ultimaker 2 - qhov zoo tshaj plaws 3D-tshuab luam ntawv nyob rau hauv 2016

Nyob rau hauv lub tswv yim ntawm CHIP magazine, uas ua los soj ntsuam thiab muab piv cov yam ntxwv ntawm tsev neeg ntawm 3D-printers, zoo tshaj plaws printers 2016 qauv Ultimaker 2 tuam txhab uas muag Ultimaker, Reniforce RF1000 lub tuam txhab Conrad thiab Replicator Desktop 3D tshuab luam ntawv lub tuam txhab MakerBot.

Ultimaker 2+ nyob rau hauv nws paub cov qauv siv simulation technology los ntawm fusing. 3D-tshuab luam ntawv txawv tsawg tshaj plaws txheej thickness ntawm 0,02 hli, ib tug me me lub sij hawm muab xam, uas tsis muaj nqi printing (2600 xuas ib 1 kg ntawm cov ntaub ntawv uas). Ntsiab Nta:

• qhov luaj li cas ntawm cov ua hauj lwm chamber - 223 x 223 x 305 hli;
• hnyav - 12.3 kg;
• lub taub hau loj - 0.25 / 0.4 / 0.6 / 0.8 hli;
• tuag kub - 180-260 ° C;
• kev daws teeb meem txheej - 150-60 / 200-20 / 400-20 / 600-20 microns;
• Sau Ceev - 8-24 hli ³ / s;
• precision XYZ - 12,5-12,55 microns;
• cov ntaub ntawv uas - PLA, ABS, CPE txoj kab uas hla 2,85 hli;
• Software - Cura;
• Txhawb kev hom ntaub ntawv - STL, OBJ, AMF;
• Fais fab kev noj - 221 W;
• nqi - 1895 euro, thiab yog lub hauv paus qauv 2495 euro ncua.

Raws li rau cov neeg xyuas, lub tshuab luam ntawv yog lub teeb rau nruab thiab siv. Qhuas siab daws teeb meem, nws tus kheej-kho txaj, ib tug loj ntau yam ntawm cov ntaub ntawv uas siv, cov siv ntawm qhib qhov software. Qhov tsis zoo muaj xws li lub tshuab luam ntawv qhib lub tshuab luam ntawv tsim, uas tej zaum yuav raug nyob rau hauv kub ntawm kub khoom.

LulzBot Mini 3D tshuab luam ntawv

Nyob rau hauv ib tug saib xyuas ntawm lub magazine PC Magazine Ultimaker 2 thiab Replicator Desktop 3D tshuab luam ntawv kuj nkag mus hauv lub to top peb, tiam sis ntawm no nyob rau hauv thawj qhov chaw yog lub tshuab luam ntawv LulzBot Mini 3D tshuab luam ntawv. Nws specifications yog raws li nram no:

• qhov luaj li cas ntawm cov ua hauj lwm chamber - 152 x 152 x 158 hli;
• Nyhav - 8,55 kg;
• tuag kub - 300 ° C;
• txheej thickness - 0.05-0.5 hli;
• Sau Ceev - 275 hli / s ntawm ib qhov siab ntawm 0,18 hli txheej;
• cov ntaub ntawv uas - PLA, ABS, lub duav, PVA, PETT, polyester, nylon, polycarbonate, PETG, PCTE, PC-ABS, thiab lwm leej lwm tus txoj kab uas hla ntawm 3 hli.
• Software - Cura, OctoPrint, BotQueue, Slic3r, Printrun, MatterControl thiab lwm yam.;
• Fais fab kev noj - 300 W;
• nqi - $ 1 250.

Sciaky EBAM 300

Ib tug ntawm qhov zoo tshaj plaws muaj cov cav tov additive raug yog EBAM 300 tuam txhab uas muag Sciaky. Electron nqaj phom ua rau cov hlau khaubncaws sab nraud povtseg ntawm ib tug ceev ntawm mus txog 9 kg ib teev.

• qhov luaj li cas ntawm cov ua hauj lwm chamber - 5791 x 1219 x 1219 hli;
• lub siab ntawm lub tshuab nqus tsev chamber - 1x10 ^-4 Torr;
• zog noj - mus txog rau 42 kW ntawm ib tug voltage ntawm 60 kV;
• technology - extrusion;
• cov ntaub ntawv uas - titanium thiab titanium alloys, tantalum, inconel, tungsten, niobium, stainless steel, aluminium, steel, tooj liab-npib tsib xee hlau (70/30 thiab 30/70);
• qhov ntau tshaj - 8605,2 litres;
• nqi - 250 txhiab US dollars ..

Additive technologies nyob rau hauv Russia

muaj-qib cov cav tov nyob rau hauv Russia tsis ua. Thaum tsuas yog tsim nyob rau hauv lub "Rosatom", lub laser chaw MSTU. Bauman University "STANKIN" Polytechnic University of St. Petersburg, lub Urals Federal University. "Voronezhselimmash", ua kev kawm thiab domestic 3D-printers "Alpha", yog tsim ib tug coj mus muag additive nroj tsuag.

Cov tib qhov teeb meem no nrog cov khoom siv. Tus thawj coj ntawm txoj kev loj hlob ntawm hmoov thiab hmoov formulations nyob rau hauv Russia yog VIAM. Lawv ua lub hmoov rau additive technologies yog siv nyob rau hauv lub restoration ntawm turbine hniav, los ntawm kev txiav txim ntawm lub Permian "aircraft xyaw». Progress yog thiab nyob rau All-Lavxias teb sab lub koom haum ntawm lub teeb alloys (log). Uas yog cov sib txawv engineering chaw thoob plaws hauv lub Lavxias teb sab Federation. "Rostec", Ural Ncau ceg ntawm Lavxias teb sab Academy ntawm Sciences, UFU ua lawv txoj kev loj hlob. Tab sis lawv tseem tsis tau mus ntsib txawm ib tug me me thov ntawm 20 tons ntawm hmoov ib xyoo.

Nyob rau hauv no hais txog, tsoom fwv qhia cov Ministry of Education, Ministry of Economic Development, Ministry ntawm kev lag luam, Ministry of Communications, Lavxias teb sab Academy ntawm Sciences, Fano, "Roscosmos", "Rosatom", "Rosstandart" txoj kev loj hlob hauv tsev mus nrhiav kom tau ib tug hauj lwm ua ke pab cuam txoj kev loj hlob thiab kev tshawb fawb. Rau nws yog npaj siab mus faib ntxiv nyiaj txiag nyiaj, raws li zoo raws li xav txog qhov tau ntawm co-txais nyob rau cov nuj nqis ntawm lub teb chaws Welfare Fund thiab lwm qhov chaw. Nws yog pom zoo kom pab txhawb cov tshiab ntau lawm technology, nyob rau hauv Vol. H. Ntxiv, MERS, "Rosnano" Fund "Skolkovo", lub export chaw ua hauj lwm "EXIAR", "Vnesheconombank". Tus tsoom fwv yog tseem tuaj los ntawm cov lag luam thiab Trade Ministry yuav npaj ib tug seem ntawm lub xeev qhov kev pab cuam rau txoj kev loj hlob thiab kev txhim kho uas muaj competitiveness.