Nigute nahitamo moteri ndende ya moteri?

Sobanukirwa n'icyo "Torque Nkuru" isobanura

Umwanya uhagaze neza hamwe na dinamike

Iyo abantu bavuze moteri ya "torque ndende", bakunze kuvuga agaciro ka torque kuri datasheet. Gufata itara ni moteri ntarengwa moteri ishobora kwihanganira guhagarara idatakaje intambwe, ubusanzwe igaragara muri N · m (metero ya Newton) cyangwa oz · in. Moteri isanzwe ya NEMA 23 itanga 1.0-3.0 N · m ifata torque, mugihe hejuru - torque NEMA 34 moderi irashobora kurenga 8-12 N · m. Ariko, porogaramu nyayo ni gake ikora ihagaze. Moteri imaze gutangira kuzunguruka, itara ryaboneka ritangira kugabanuka; iyi ni dinamike ya torque, igomba gusuzumwa kumuvuduko ukenewe.

Kuri moteri runaka, urashobora kubona 3 N · m ifashe torque 0 rpm ariko 2 N · m gusa kuri 300 rpm na 1 N · m kuri 800 rpm. Guhitamo moderi ya "high torque" gusa ufashe torque irashobora kuganisha kubisubizo bitagabanijwe cyangwa binini. Buri gihe gereranya torque kumuvuduko wawe wimikorere uhereye kumuvuduko - umurongo wa torque.

Kurura - muri torque, gukuramo - gusohora umuriro, no guhagarara

Umuyoboro wa dinamike urashobora gucika mugukurura - muri no gukurura - gusohora umuriro. Kurura - muri torque nigipimo ntarengwa cyumutwaro aho moteri ishobora gutangirira, guhagarara, cyangwa guhindukira icyarimwe nta gutakaza intambwe. Kurura - hanze ya torque nini ntarengwa yumutwaro ushobora gutwarwa kumuvuduko runaka, ukeka ko moteri imaze gukora kuri uwo muvuduko. Kubikorwa byizewe, umutwaro wumuriro ugomba kuguma munsi gukurura - muri torque mugihe cyo kwihuta no munsi gukurura - gusohora umuriro mugihe cyihuta.

Kurugero, niba moteri ifite gukurura - gusohora umuriro wa 1.2 N · m kuri 600 rpm ariko umutwaro usabwa ni 1.0 N · m, marike yo guhagarara ni gusa (1.2 - 1.0) / 1.2 ≈ 17%. Inganda zikora inganda zisaba byibuze 30-50% margin kugirango habeho impinduka ziterwa no guterana, kuzamuka kwubushyuhe, no kwambara. Mugihe ugereranije ingero ziva mubitanga byinshi cyangwa muruganda, shimangira gukurura byuzuye - muri / gukurura - gusohora umurongo wa torque, ntabwo ari kimwe gusa gifata umurongo wa torque.

Gutomora ibyifuzo bisabwa mbere yo gutoranya moteri

Kugaragaza umuvuduko, umutwaro, ninshingano zinzira

Mbere yo kuvugana nuwabikoze cyangwa gushakisha kataloge, sobanura ibintu bitatu byingenzi: umuvuduko ukenewe, urumuri rusabwa kuri uwo muvuduko, hamwe ninshingano zakazi. Umuvuduko mubisanzwe ugaragara muri rpm cyangwa intambwe kumasegonda. Kurugero, icyiciro cya sisitemu isaba 200 mm / s hamwe na 8 mm ya pine ikenera rpm 1500 (kuko 200 mm / s / 8 mm / rev = 25 rev / s ≈ 1500 rpm). Niba umutwaro uringaniye ari 200 N hamwe nubukanishi ni 0.8, icyifuzo cya torque ni:

• Torque = (Imbaraga × Kuyobora) / (2π × Gukora neza) = (200 N × 0.008 m) / (6.283 × 0.8) ≈ 0.51 N · m

Niba uburyo bukora amasaha 16 kumunsi kuri uyu muvuduko n'umuvuduko, urwego rwinshingano ni rwinshi kandi ibitekerezo byubushyuhe birakomera.

Umwanya uhagaze neza, gukemura, hamwe nintambwe

Moteri ya Stepper ntabwo yatoranijwe gusa kuri torque ahubwo ihagaze neza. Moteri isanzwe ya Hybrid intambwe ifite inguni ya 1.8 ° (intambwe 200 kuri revolution). Hamwe na microsteps 10 kuri buri ntambwe yuzuye, ubona microsteps 2000 kuri revolution, cyangwa 0.18 ° kuri microstep. Kuri 5 mm ya screw, bivuze kuri 5 mm / 2000 ≈ 2.5 µm kuri microstep.

Niba sisitemu yawe isaba ± 10 µm umwanya uhagaze neza, ntugomba gutekereza gusa kuri microstep nominal gusa ariko nanone ugomba gusubiza inyuma imashini, umushoferi udafite umurongo, hamwe na torque ripple. Umuvuduko mwinshi wa torque ukunda kugira inductance yo hejuru, ishobora kongera gato intambwe idahwitse kumuvuduko mwinshi; ubu bucuruzi - hanze bugomba gusuzumwa hakiri kare.

Intambwe ya Moteri Ingano, Ikadiri, na Torque Isano

Ingano yikadiri hamwe na torque isanzwe

Ingano yimiterere isanzwe isobanurwa na NEMA cyangwa ibipimo bisa. Ingano isanzwe kubisabwa murwego rwo hejuru harimo:

• NEMA 17 (42 mm): bisanzwe bifata umuriro wa 0.4–0.8 N · m
• NEMA 23 (57 mm): bisanzwe bifata torque 1.0–3.0 N · m
• NEMA 24 (60 mm): isanzwe ifata torque 2.0–4.0 N · m
• NEMA 34 (86 mm): isanzwe ifata umuriro 4.0–12.0 N · m

Amakadiri manini yemerera ibice birebire hamwe na diameter nini ya rotor, byongera umuriro. Nyamara, kugenzura ikadiri byongera inertia nigiciro, kandi birashobora gusaba umushoferi ukomeye nimbaraga zitanga amashanyarazi. Mu mishinga ya OEM no gutanga amasoko menshi, kuringaniza ingano yikigereranyo hamwe na torque ibarwa neza ikenewe ni imwe munzira nyamukuru zo kuzamura ibiciro.

Shyira uburebure, ingano ya rotor, na diameter ya shaft

Muburyo bwatanzwe, uzabona kenshi verisiyo ngufi, iringaniye, na ndende ya stack verisiyo. Kongera uburebure bwa stack muri rusange byongera rotor ingano na torque hafi ugereranije, nubwo nayo izamura inertia. Kurugero, moteri ngufi - stack NEMA 23 irashobora kugira 1.0 N · m ifata torque na 70 g · cm² inertia, mugihe verisiyo ndende - stack murwego rumwe irashobora gutanga 2,4 N · m ifata torque na 160 g · cm² inertia.

Diameter ya shaft, akenshi mm 6,35 mm (1/4) kuri NEMA 23 na 12-14 mm kuri NEMA 34, byerekana muburyo butaziguye imbaraga za moteri. Niba porogaramu yawe isaba impinga ya torque iri hejuru ya 150% yizina cyangwa kenshi ihindagurika, ibiti binini hamwe nigitereko gikomeye bihinduka ingingo zingenzi zo guhitamo, cyane cyane iyo ukorana nuruganda kumurongo wihariye -

Ingaruka yubwoko bwa moteri yintambwe kuri Torque

Imashini ihoraho hamwe na moteri ya Hybrid intambwe

Imashini zihoraho (PM) moteri yintambwe isanzwe ifite inguni nini (7.5 °, 15 °) hamwe nubushyuhe buke. Nibyoroshye kandi bidahenze, ariko ntibikunze gutoranywa kubisabwa murwego rwo hejuru. Moteri ya Hybrid intambwe ihuza ibiranga PM nubwoko butandukanye bwo kwanga, mubisanzwe hamwe na 1.8 ° cyangwa 0.9 ° inguni. Moteri zitanga urumuri rwinshi, imikorere myiza yingirakamaro, hamwe na torque ihamye kuri buri ntambwe.

Kuri sisitemu nyinshi zo murwego rwo hejuru, sisitemu ya Hybrid irahitamo. Moteri ndende - torque Hybrid NEMA 34 irashobora gutanga 8-12 N · m yo gufata torque mubipaki ugereranije. Mugihe ukorana nuwabikoze, genzura niba moteri ari igishushanyo mbonera gisanzwe cyangwa variant yihariye ifite rotor nziza hamwe na stator geometrie ya torque.

Igishushanyo mbonera, imikorere ya bipolar, hamwe nibisohoka

Iboneza ryahinduwe bigira ingaruka zikomeye kumurongo-umuvuduko. Imikorere ya Bipolar ikoresha umuyaga wuzuye kandi mubisanzwe itanga umuriro wa 30-40% kuruta gukora unipolar ikora kumurongo umwe, kuko umuringa ukoreshwa neza. Abashoferi benshi bigezweho hamwe na porogaramu bakoresha bipolar igenzura kubwiyi mpamvu.

Kurwanya ibishishwa hamwe na inductance bigena moteri yamashanyarazi ahoraho. Hasi - inductance ihindagurika, urugero 2 mH aho kuba 8 mH, irashobora gusubiza byihuse, kugumana umuriro mwinshi kumuvuduko, kandi ikora neza kurwego rwo hejuru. Ariko, ibi mubisanzwe bisaba amanota yo hejuru (urugero, 4.2 A aho kuba 2.0 A). Gukorana mu buryo butaziguye n’uruganda cyangwa utanga ibicuruzwa byinshi byemerera gukora ibipimo byuzuzanya - kurwanya, inductance, igipimo cyagenwe - kugirango ugabanye urumuri rwihuta rwihuta rwibisabwa.

Umuvuduko, Ibiriho, na Driver Guhitamo Torque

Ikigereranyo cyubu, gutwara ibiyobora, hamwe no gukoresha torque

Intambwe ya moteri yintambwe yerekana icyiciro cyateganijwe, nka 2.8 A cyangwa 5.0 A. Uyu muyoboro usanzwe usobanurwa kugirango ugere ku cyerekezo gifatika ku izamuka ry’ubushyuhe bwihariye (urugero, 80 ° C hejuru y’ibidukikije). Gukoresha bike cyane bigabanya umuriro uboneka hafi ugereranije. Kurugero, gutwara moteri 3.0 Yapimwe kuri 1.5 A mubisanzwe itanga hafi 50-60% yumuriro.

Kugirango umenye imbaraga zuzuye, umushoferi wawe agomba gutanga byibuze icyerekezo cyagenwe hamwe nubuyobozi bukwiye. Umushoferi ufite amanota 3.5 Impinga ntishobora gukomeza 3.5 RMS kuri buri cyiciro, bigira ingaruka kumutwe wumutwe. Buri gihe wemeze RMS nibisobanuro bya mpinga mugihe ugereranije abashoferi. Muri OEM hamwe n’imishinga myinshi, ibizamini bya moteri - ibinyabiziga bigerageza ku ruganda birasabwa cyane kugenzura ibyasohotse neza.

Amashanyarazi yumuriro kandi muremure - umuvuduko mwinshi

Intambwe yindobanure irwanya impinduka zubu. Ku muvuduko mwinshi, ikigezweho gifite igihe gito cyo kuzamuka muri buri ntambwe, igabanya umuriro. Gukoresha bisi ya voltage irashobora kunoza cyane - umuvuduko mwinshi watsinze ingaruka zinductive. Kurugero, moteri imwe ya NEMA 23 itwarwa kuri 24 V irashobora gutanga 0.5 N · m kuri 1000 rpm, mugihe kuri 48 V irashobora kugumana 0,9 N · m kumuvuduko umwe - hafi 80%.

Amategeko ngengamikorere ni ugukoresha voltage yo gutanga inshuro 10-20 kurenza igipimo cya moteri ya moteri ya moteri (nkuko ubarwa uhereye kuri moteri yagereranijwe no guhangana), mugihe ugumye mumipaka yabashoferi. Niba moteri ifite 2.1 resistance irwanya icyiciro na 2.0 Ikigereranyo cyagenwe, voltage yicyiciro ni 4.2 V. A 48 V itanga ihuye ninshuro zigera kuri 11.4 agaciro kayo, mubisanzwe birakwiriye. Guhuza moteri, umushoferi, hamwe nogutanga amashanyarazi binyuze muruganda rumwe byoroshya ibyo gukora.

Umuvuduko - Imirongo ya Torque no gusobanura imibare

Gusoma umuvuduko - ibishushanyo mbonera

Umuvuduko - torque umurongo nigishushanyo cyagaciro cyane mumashanyarazi ya datasheet. Umurongo utambitse werekana umuvuduko, akenshi muri rpm cyangwa pps, na vertical axis yerekana torque iboneka. Imirongo myinshi irashobora kugereranya amashanyarazi atandukanye cyangwa gutwara amashanyarazi. Intego yawe nukumenya torque iboneka kumuvuduko ukenewe wo kuyigereranya no kuyigereranya numubare wimitwaro wabazwe wongeyeho numutekano wumutekano.

Kurugero, tuvuge ko gusaba kwawe bisaba 0.8 N · m kuri 600 rpm. Urupapuro rwerekana 1.4 N · m kuri 600 rpm mugihe cyagenwe cyo gutwara. Impera ni (1.4 - 0.8) / 0.8 = 75%. Ibi mubisanzwe biremewe, ndetse urebye izamuka ryubushyuhe hamwe nibintu bito bitandukanye. Niba umurongo uguye munsi yumuriro wawe usabwa kumuvuduko wintego, ugomba guhitamo moteri nini, kongera ingufu, kugabanya umuvuduko, cyangwa kongera guhindura imashini.

Gusuzuma imipaka yubushyuhe no gutesha agaciro

Ibipimo bya torque bifata ubushyuhe ntarengwa bwo guhinduranya, ubusanzwe 80-100 ° C kuzamuka hejuru ya 40 ° C. Gukorera kumuyoboro mwinshi ahantu hafunzwe hatabayeho gukonjesha bihagije birashobora gutuma ubushyuhe burenga ako gaciro, biganisha ku kwangirika buhoro buhoro no kubaho igihe gito. Ababikora benshi batangaza agaciro ka torque kubushyuhe bwo hejuru bwibidukikije.

Nkumurongo ngenderwaho, kugabanuka kwa 20% mugice cyicyiciro gishobora gutuma igabanuka rya 15-25% mugutwara umuriro. Niba sisitemu yawe ikorera mubidukikije 50-60 ° C hamwe numuyaga muke, shyira mugaciro mbere yo kwishingikiriza mubyumba - amakuru yikizamini cyubushyuhe. Mugihe ukorana numufatanyabikorwa wuruganda, saba raporo yikizamini cyubushyuhe kubushyuhe butandukanye bwibidukikije hamwe ninshingano zinshingano kugirango wemeze igihe kirekire - igihe cyo kwizerwa.

Imizigo Yumukanishi, Inertia, na Torque Umutekano

Kubara itara kuva kumurongo no kuzunguruka

Guhindura ibisabwa bya mashini muri torque ni ngombwa. Kumurongo ugororotse utwarwa na screw, torque irashobora kubarwa ukoresheje:

• Torque (N · m) = (F × Isonga) / (2π × η)

aho F ari umurongo ugaragara (N), Isonga ni screw pitch (m / rev), na η ni imikorere (0.3–0.9 bitewe no guterana). Kubikoresho byumukandara:

• Torque (N · m) = (F × r) / η

aho r ni radiyo (m). Kuzenguruka inertia imizigo, torque isabwa kugirango yihute ni:

• Torque (N · m) = J × α

aho J ni inertia yose (kg · m²) na α ni kwihuta kwinguni (rad / s²). Kwirengagiza iyi misanzu idashidikanywaho no guterana amagambo ni impamvu rusange yo gutakaza intambwe muri sisitemu ya "high torque" igaragara ihagije ku mpapuro ariko ikananirwa mubikorwa.

Ikigereranyo cya Inertia nibikorwa byiza

Moteri ya Stepper ikora neza mugihe inertia yumutwaro itaba nini cyane kuruta rotor inertia. Ikigereranyo gisanzwe ni:

• Fungura inertia / Inertia ya Rotor ≤ 10: 1 (nibyiza 3-5: 1)

Dufate ko moteri ya rotor inertia ari 120 g · cm² (1.2 × 10⁻⁵ kg · m²). Hamwe na 5: 1, intego ya inertia yumutwaro ni 6 × 10⁻⁵ kg · m² cyangwa munsi yayo. Niba inertia yumutwaro ari 1 × 10⁻³ kg · m² (hafi inshuro 80 inertia ya rotor), sisitemu irashobora gusaba garebox (urugero 5: 1 cyangwa 10: 1) cyangwa moteri nini ya moteri. Ihuza rya inertia rirakomeye cyane muguhitamo moteri kubwinshi kugirango umusaruro wa OEM, aho buri ijanisha ryibintu byatakaye byegeranya mubice ibihumbi.

Amashanyarazi, Amashanyarazi, hamwe nubushuhe

Ingano ya kiyobora, uburebure bwa wiring, hamwe na voltage igabanuka

Umugozi muremure ukoreshwa hagati yumushoferi na moteri byongera imbaraga kandi birashobora kugabanya imbaraga zingirakamaro kuri moteri, kugabanya umuriro-cyane cyane kumuvuduko mwinshi. Umuvuduko wa voltage ni:

• Vdrop = I × Rcable

Niba icyiciro cyicyiciro ari 4.0 A hamwe nuruziga - ingendo ya kabili irwanya ni 0.5 Ω, igitonyanga ni 2.0 V. Hamwe na 24 V itanga, ibi bingana no gutakaza ingufu za 8.3%. Guhitamo imiyoboro minini cyangwa insinga ngufi bigabanya Rcable kandi igateza imbaraga za torque. Kinini - igipimo kinini cyangwa imishinga myinshi, kugena uburebure bwa kabili na gipima birashobora guhindura imikorere.

Ubushyuhe bwo gutandukana nibidukikije

Moteri ikomeza kubyara ubushyuhe buturuka ku gutakaza umuringa (I²R) no gutakaza ibyuma. Igikorwa kinini cyumuriro hejuru cyangwa hejuru yikigereranyo kigomba guhuzwa nubushyuhe buhagije. Igipimo rusange ni ugukomeza ubushyuhe bwa moteri munsi ya 80-90 ° C bipimirwa ahantu hashyushye. Mu bidukikije bya 25 ° C, ibi bivuze ko izamuka ryinshi ryemerwa rya 55-65 ° C.

Ubushyuhe bwo gushyushya, gushira mubyuma, abafana, cyangwa ikirere cyumuyaga ku gahato birashobora kongera ubushobozi bwumuriro mugihe runaka mugihe gikomeza ubushyuhe bwiza. Uruganda rwumwuga rushobora gutanga amashusho yumuriro cyangwa ibizamini mugihe cyo kwishyiriraho no gukonjesha, kwemeza ko ibisobanuro bya torque byujujwe nta bushyuhe bukabije.

Urusaku, Kunyeganyega, hamwe nubwiza bwimikorere na Torque

Microstepping, resonance, hamwe no kugenda neza

Nubwo torque ari ngombwa, ubwiza bwimikorere ntibushobora kwirengagizwa. Moteri ya Stepper yerekana resonans karemano, akenshi iri hagati ya 100-300 rpm kubisanzwe NEMA 17 cyangwa 23, bishobora gutera kunyeganyega, urusaku rwumvikana, no gutakaza intambwe. Abashoferi ba Microstepping-nka 8, 16, cyangwa 32 microsteps kuri buri ntambwe yuzuye - bigabanya umuvuduko wa torque hamwe na resonance ya mashini, bikavamo kuzunguruka neza no gukora neza.

Ariko, microstepping ntabwo yongerera muburyo bwo gukemura neza. Moteri iri kuri 1.0 N · m ifata torque ntishobora kubyara 0.01 N · m ifite umurongo ugaragara kuri buri microstep. Mubyukuri, byibuze byibuze bigenda byiyongera bishobora kuba hafi ya 5-10% yumuriro. Mugihe ugaragaza igisubizo cyuruganda, saba amakuru kumurongo wa resonance yumurongo, imikorere ya microstepping, hamwe ningamba zose zo kugabanya zubatswe mubushakashatsi bwa moteri.

Kuringaniza umuriro, urusaku, no gukoresha ingufu

Gukoresha moteri kumurongo ntarengwa wongera umuriro ariko nanone bizamura urusaku, kunyeganyega, no gukoresha ingufu. Muri porogaramu nyinshi, ikora kuri 60-80% yumurongo ugezweho no gukoresha microstepping itera uburinganire bwiza hagati yumuriro no koroha. Kurugero, moteri itanga 2.0 N · m kuri 3.0 A irashobora gutanga 1.5 N · m kuri 2.2 A, hamwe n urusaku ruke kandi nubushyuhe buringaniye.

Guhindura ibintu bigezweho, aho bigabanuka mugihe gito - umutwaro cyangwa gufata igihe, birashobora kandi kugabanya ingufu zikoreshwa. Mugihe ushakisha moteri kumuyoboro mwinshi, wemeze niba umushoferi ashyigikira kugabanuka kwubu kandi niba moteri hamwe na moteri byerekanwe kumurongo wuzuye uteganijwe gukora.

Igiciro, Kwizerwa, hamwe nubucuruzi bushigikira ubucuruzi - Offs

Igiciro cyose cya nyirubwite, ntabwo igiciro cyibice gusa

moteri ndendes bikunze kwinjizwa mubikoresho bikomeye aho igihe cyo hasi gihenze cyane kuruta moteri ubwayo. Gusuzuma igiciro cyose cya nyirubwite harimo gushingira kumyaka yo kubaho, igipimo cyo gutsindwa, imbaraga zumuriro, hamwe no kubona inkunga ya tekiniki. Igiciro gito cyibicuruzwa bitangirwa isoko birashobora guhisha igipimo cyinshi gisakaye, imikorere ya torque idahuye, cyangwa gutinda kubitanga bihagarika umusaruro.

Mugihe ugereranije amahitamo yaturutse kurutonde rwabakora ibicuruzwa bitandukanye cyangwa urubuga rwinshi, ntusuzume gusa itara nigiciro, ahubwo usuzume ibipimo byikizamini, ibyemezo byubuziranenge, raporo zubugenzuzi, hamwe namasezerano ya garanti. Moteri ziteranijwe hamwe na stator zihoraho, hejuru ya magneti yo mu rwego rwo hejuru, hamwe na rotor yuzuye iringaniza bizatanga umurongo uhamye wa torque hamwe nubuzima burebure, kabone niyo byatwara 10-20% kuri buri gice.

Gukoresha prototyping, kugerageza icyiciro, no gufatanya nuruganda

Ukuri - kwemeza isi ni ngombwa. Mbere yo kwiyemeza gutondekanya runini, kora ibizamini bya prototype yigana umutwaro wawe nyawo, imiterere yihuta, nibidukikije. Gupima marque marike, kuzamuka kwubushyuhe, hamwe nigihe kirekire - igihe gihamye. Kubyinshi mubikorwa, tekereza kubitsinda byibuze 1-3% byibice byinjira kugirango urebe ko byujuje itara ryerekanwe kumuvuduko wingenzi.

Ubufatanye butaziguye nuruganda butuma optimizasiyo irenze kataloge ya cataloge: guhinduranya ibicuruzwa kugirango uhuze na voltage yawe itanga, uburebure bwihariye bwa shaft cyangwa inzira nyabagendwa, ibyuma byongerwaho imbaraga kumitwaro ya radiyo, cyangwa kodegisi ihuriweho kugirango ifunge - Ihinduka rirashobora kunoza cyane imikorere ya sisitemu no kwizerwa nta kongera ibiciro cyane, cyane cyane iyo bigabanijwe hejuru - ingano ya OEM cyangwa ibicuruzwa byinshi.

Maxtech Tanga ibisubizo

Maxtech yibanze ku guhuza ibiranga moteri kubisabwa bya mashini n'amashanyarazi. Ukurikije umuvuduko wawe wintego, umutwaro wumuriro, uruzinduko rwimikorere, hamwe nibidukikije, injeniyeri wa Maxtech abara igipimo cya inertia, agasaba ingano ya NEMA ikwiye, kandi agasobanura urwego rukwiye na voltage. Uruganda rushobora guhinduranya umuyaga kugirango uzamure hejuru - umuvuduko mwinshi, guhuza rotor inertia, no guhuza abashoferi bahujwe nibikoresho bitanga ingufu. Waba ukeneye urugero rwinshi cyangwa ibicuruzwa byinshi, Maxtech itanga umuvuduko wemewe - amakuru yumuriro, raporo yikizamini cyumuriro, hamwe nubufasha bwa porogaramu, ukemeza ko buri moteri yatoranijwe itanga moteri ihamye, yumuriro mwinshi hamwe no kuzamuka kwubushyuhe hamwe nubuzima bwa serivisi ndende.