1. Iimpawu ze-EDM zezinto zegrafiti.
1.1. Isantya somatshini wokukhupha itshaja.
I-Graphite yinto engeyoyesinyithi enendawo yokunyibilika ephezulu kakhulu ye-3,650 ° C, ngelixa ubhedu lunendawo yokunyibilika ye-1,083 ° C, ngoko ke i-electrode ye-graphite inokumelana neemeko zokuseta umbane ezinkulu.
Xa indawo yokukhupha kunye nobukhulu be-electrode bukhulu, iingenelo zokulungisa izinto zegrafiti ngendlela esebenza kakuhle zibonakala ngakumbi.
Ubushushu begrafiti buyi-1/3 yobhedu, kwaye ubushushu obuveliswa ngexesha lenkqubo yokukhupha bungasetyenziswa ukususa izinto zesinyithi ngempumelelo. Ke ngoko, ukusebenza kakuhle kwegrafiti kuphezulu kunoko kwe-electrode yobhedu ekucutshungulweni okuphakathi nokucolekileyo.
Ngokweemava okucubungula, isantya sokucubungula ukukhupha i-graphite electrode sikhawuleza ngokuphindwe kayi-1.5 ~ 2 kuneso se-copper electrode phantsi kweemeko ezifanelekileyo zokusetyenziswa.
1.2. Ukusetyenziswa kwe-electrode.
I-electrode yegrafiti inophawu olunokumelana neemeko zangoku eziphezulu, ukongeza, phantsi kwemeko yokuseta okufanelekileyo kwe-roughing, kubandakanya izinto zokusebenza zentsimbi yekhabhoni eziveliswa ngexesha lokususwa komatshini kumxholo kunye nolwelo olusebenzayo ekuqhekekeni kwamasuntswana ekhabhoni kubushushu obuphezulu, isiphumo se-polarity, phantsi kwesenzo sokususwa okuncinci kumxholo, amasuntswana ekhabhoni aya kunamathela kumphezulu we-electrode ukwenza umaleko okhuselayo, aqinisekise ukuba i-electrode yegrafiti ilahlekelwa kancinci kumatshini onzima, okanye nokuba "yinkunkuma engenazo".
Eyona lahleko iphambili ye-electrode kwi-EDM ivela kwi-rough machining. Nangona izinga lokulahleka liphezulu kwiimeko zokuseta zokugqiba, ilahleko iyonke ikwaphantsi ngenxa yesibonelelo esincinci se-machining esigcinelwe iindawo.
Ngokubanzi, ukulahleka kwe-electrode ye-graphite kuncinci kunokwe-electrode yobhedu kwi-rough machining ye-large current kwaye kungaphezulu kancinci kunokwe-electrode yobhedu kwi-finishing machining. Ukulahleka kwe-electrode ye-graphite electrode kuyafana.
1.3. Umgangatho womphezulu.
Ububanzi bezinto zegrafiti buchaphazela ngokuthe ngqo uburhabaxa bomphezulu we-EDM. Okukhona ububanzi buncinci, kokukhona uburhabaxa bomphezulu bunokufunyanwa buphantsi.
Kwiminyaka embalwa eyadlulayo kusetyenziswa izinto zegrafiti ezi-5 microns ububanzi be-particle phi, umphezulu ongcono kakhulu unokufikelela kuphela kwi-VDI18 edm (Ra0.8 microns), kule mihla ububanzi begrafini bezixhobo zegrafini bukwazile ukufikelela ngaphakathi kwe-3 microns ye-phi, umphezulu ongcono kakhulu unokufikelela kwi-VDI12 edm ezinzileyo (Ra0.4 mu m) okanye kwinqanaba elinobungcali ngakumbi, kodwa i-graphite electrode iyakwazi ukufikelela kwi-mirror edm.
Izinto zobhedu azinamandla okuxhathisa kwaye zincinci, kwaye zinokucutshungulwa ngokuzinzileyo phantsi kweemeko ezinzima. Uburhabaxa bomphezulu bunokuba ngaphantsi kweRa0.1 m, kwaye bunokucutshungulwa ngesipili.
Ngoko ke, ukuba i-discharge machining ilandela umphezulu ocolekileyo kakhulu, kungcono ukusebenzisa izinto zobhedu njenge-electrode, eyona nzuzo iphambili ye-copper electrode kune-graphite electrode.
Kodwa i-electrode yobhedu phantsi kwemeko yokuseta okukhulu kwangoku, umphezulu we-electrode kulula ukuba ube rhabaxa, ubonakala uqhekekile, kwaye izixhobo zegrafiti aziyi kuba nale ngxaki, imfuneko yoburhabaxa bomphezulu we-VDI26 (Ra2.0 microns) malunga nokucubungula isikhunta, ukusebenzisa i-electrode yegrafiti kungenziwa ukusuka ekucutshungulweni okurhabaxa ukuya kokucolekileyo, kuyaqondakala isiphumo somphezulu esifanayo, iziphene zomphezulu.
Ukongeza, ngenxa yesakhiwo esahlukileyo se-graphite kunye ne-copper, i-surface discharge corrosion point ye-graphite electrode iqhelekile kuneye-copper electrode. Ke ngoko, xa kucutshungulwa uburhabaxa obufanayo be-VDI20 okanye ngaphezulu, uburhabaxa bomphezulu we-workpiece obucutshungulwa yi-graphite electrode bucacile ngakumbi, kwaye esi siphumo somphezulu weenkozo singcono kunesiphumo somphezulu wokukhupha we-copper electrode.
1.4. Ukuchaneka komatshini.
I-coefficient yokwandiswa kobushushu bezinto zegrafiti incinci, i-coefficient yokwandiswa kobushushu bezinto zebrafiti iphindwe kane kuneyezinto zegrafiti, ngoko ke ekucutshungulweni kokukhupha, i-graphite electrode ayichaphazeleki lula kune-copper electrode, enokufumana ukuchaneka kokucubungula okuzinzileyo nokuthembekileyo.
Ingakumbi xa kucutshungulwa imbambo enzulu nemxinwa, ubushushu obuphezulu bendawo benza i-electrode yobhedu igobe lula, kodwa i-electrode ye-graphite ayigobi.
Kwi-electrode yobhedu enomlinganiselo omkhulu wobunzulu-ububanzi, ixabiso elithile lokwandiswa kobushushu kufuneka lihlawulwe ukuze kulungiswe ubungakanani ngexesha lokuseta i-machining, ngelixa i-electrode ye-graphite ingadingeki.
1.5. Ubunzima be-electrode.
Izinto zegrafiti azixinene kangako kunezobhedu, kwaye ubunzima be-electrode yegrafiti yomthamo ofanayo yi-1/5 kuphela yobunzima be-electrode yobhedu.
Kuyabonakala ukuba ukusetyenziswa kwegrafiti kulungele kakhulu i-electrode enomthamo omkhulu, nto leyo enciphisa kakhulu umthwalo we-spindle yesixhobo somatshini se-EDM. I-electrode ayizukubangela ingxaki ekubambeni ngenxa yobunzima bayo obukhulu, kwaye iya kuvelisa ukuphambuka kokuguquguquka ekuqhubekeni, njl. Kuyabonakala ukuba kubaluleke kakhulu ukusebenzisa i-graphite electrode ekuqhubekeni kokubumba okukhulu.
1.6. Ubunzima bokwenziwa kwee-electrode.
Ukusebenza kakuhle kwezixhobo zegrafiti. Ukumelana nokusika yi-1/4 kuphela kunokobhedu. Phantsi kweemeko ezifanelekileyo zokucubungula, ukusebenza kakuhle kwe-electrode yegrafiti yokusila kuphindwe ka-2-3 kunokobhedu.
I-electrode yegrafiti kulula ukuyicoca i-Angle, kwaye ingasetyenziselwa ukucubungula umsebenzi omele ugqitywe zii-electrode ezininzi ube yi-electrode enye.
Ulwakhiwo olulodwa lwamasuntswana ezinto zegrafiti luthintela ii-burrs ukuba zingenzeki emva kokusila nokwenziwa kwe-electrode, nto leyo enokuhlangabezana ngqo neemfuno zokusetyenziswa xa ii-burrs zingasuswa lula kwimodeli enzima, ngaloo ndlela isusa inkqubo yokupolisha ngesandla i-electrode kwaye iphephe utshintsho lwemilo kunye nempazamo yobukhulu obubangelwa kukupolisha.
Kufuneka kuqatshelwe ukuba, kuba i-graphite iqokelela uthuli, i-grafiti yokusila iya kuvelisa uthuli oluninzi, ngoko ke umatshini wokusila kufuneka ube nesixhobo sokutywina nokuqokelela uthuli.
Ukuba kuyimfuneko ukusebenzisa i-edM ukucubungula i-graphite electrode, ukusebenza kwayo kokucubungula akulunganga njengezinto zobhedu, isantya sokusika sihamba kancinci nge-40% kunesethusi.
1.7. Ukufakelwa nokusetyenziswa kwe-electrode.
Izinto zegrafiti zinophawu oluhle lokubopha. Zingasetyenziselwa ukubopha igrafiti kunye nesixokelelwano ngokusila i-electrode kunye nokukhupha, nto leyo enokonga inkqubo yokulungisa umngxuma wesikrufu kwizinto ze-electrode kwaye yonge ixesha lokusebenza.
Izinto zegrafiti zibuthathaka, ingakumbi i-electrode encinci, emxinwa nende, elula ukuphuka xa isetyenziswa ngaphandle, kodwa inokwazi ukubona kwangoko ukuba i-electrode yonakele.
Ukuba yi-electrode yobhedu, iya kugoba kuphela kwaye ingaphuki, nto leyo eyingozi kakhulu kwaye kunzima ukuyifumana kwinkqubo yokusetyenziswa, kwaye iya kukhokelela ngokulula kwisiqwenga sesixhobo somsebenzi.
1.8. Ixabiso.
Izinto zobhedu zizinto ezingavuselelekiyo, ixabiso liya kubiza kakhulu, ngelixa ixabiso lezinto zegrafiti lihlala lizinzile.
Amaxabiso ezinto zobhedu anyuke kwiminyaka yakutshanje, abavelisi abakhulu begrafiti abaphucula inkqubo yokuvelisa igrafiti bafumana inzuzo yokukhuphisana, ngoku, phantsi komthamo ofanayo, ixabiso lezinto zobhedu zegrafiti kunye nexabiso lezinto zobhedu ze-electrode liphezulu kakhulu, kodwa igrafiti inokufezekisa ukucutshungulwa okusebenzayo, kunokusebenzisa i-electrode yobhedu ukonga inani elikhulu leeyure zokusebenza, okulingana nokunciphisa iindleko zemveliso ngokuthe ngqo.
Ngamafutshane, phakathi kweempawu ze-8 edM ze-graphite electrode, iingenelo zayo zicacile: ukusebenza kakuhle kwe-milling electrode kunye nokucubungula ukukhupha kubhetele kakhulu kunokwe-copper electrode; i-electrode enkulu inobunzima obuncinci, uzinzo oluhle, i-electrode encinci ayilula ukuyiguqula, kwaye ubume bomphezulu bungcono kune-copper electrode.
Ingxaki yezinto ezisebenzisa igrafiti kukuba ayifanelekanga ukucutshungulwa kokukhupha umphezulu ocolekileyo phantsi kwe-VDI12 (Ra0.4 m), kwaye ukusebenza kakuhle kokusebenzisa i-edM ukwenza i-electrode kuphantsi.
Nangona kunjalo, ngokwembono esebenzayo, esinye sezizathu ezibalulekileyo ezichaphazela ukukhuthazwa ngokufanelekileyo kwezixhobo zegrafiti eTshayina kukuba kufuneka umatshini okhethekileyo wokucubungula igrafiti kwii-electrode zokugaya, nto leyo ebeka phambili iimfuno ezintsha zezixhobo zokucubungula amashishini okubumba, amanye amashishini amancinci asenokungabi nale meko.
Ngokubanzi, iingenelo zee-electrode ze-graphite zigubungela uninzi lweziganeko zokucubungula i-edM, kwaye zifanele ukuthandwa nokusetyenziswa, kunye neenzuzo ezinkulu zexesha elide. Ukunqongophala kokucubungula umphezulu omncinci kunokulungiswa kukusetyenziswa kwee-electrode zobhedu.
2.Ukukhethwa kwezinto ze-graphite electrode ze-EDM
Kwizinto zegrafiti, kukho ikakhulu ezi mpawu zine zilandelayo ezichaza ngokuthe ngqo ukusebenza kwezinto:
1) Ububanzi obuphakathi bezinto ezisetyenzisiweyo
Ububanzi obuqhelekileyo bezinto ezisetyenzisiweyo buchaphazela ngokuthe ngqo imeko yokukhupha izinto.
Okukhona isuntswana eliqhelekileyo lezinto zegrafiti lincinci, kokukhona ukukhupha kufana ngakumbi, kokukhona imeko yokukhupha izinzile, kokukhona umgangatho womphezulu ungcono, kwaye kokukhona ukulahleka kuncinci.
Okukhona ubukhulu obuqhelekileyo besuntswana bukhulu, kokukhona izinga lokususwa elingcono linokufunyanwa kwi-rough machining, kodwa isiphumo somphezulu wokugqiba asilunganga kwaye ilahleko ye-electrode inkulu.
2) Amandla okugoba kwezinto
Amandla okugobeka kwezinto abonisa ngqo amandla azo, nto leyo ebonisa ukuqina kwesakhiwo sangaphakathi sazo.
Izinto ezinamandla aphezulu zisebenza kakuhle kakhulu ekuchaseni ukukhutshwa. Kwi-electrode echanekileyo kakhulu, izinto ezinamandla kufuneka zikhethwe kangangoko kunokwenzeka.
3) Ukuqina konxweme lwento
I-Graphite ilukhuni kunezixhobo zesinyithi, kwaye ukulahleka kwesixhobo sokusika kukhulu kunokulahleka kwesinyithi sokusika.
Kwangaxeshanye, ubunzima obuphezulu bezinto zegrafiti kulawulo lokulahleka kokukhupha bungcono.
4) Ukumelana okungokwemvelo kwezinto
Izinga lokukhupha izinto zegrafiti ezinokumelana okuphezulu okungaphakathi liya kuba lincinci kunelo linokumelana okuphantsi.
Okukhona i-resistivity yendalo iphezulu, kokukhona ilahleko ye-electrode incinci, kodwa kokukhona i-resistivity yendalo iphezulu, ukuzinza kokukhupha kuya kuchaphazeleka.
Okwangoku, kukho iintlobo ezahlukeneyo zegrafiti ezifumanekayo kubathengisi begrafiti abaphambili kwihlabathi liphela.
Ngokubanzi ngokwemida yesuntswana ephakathi yezinto zegrafiti eziza kuhlelwa, ububanzi besuntswana obuyi-≤ 4 m buchazwa njengegrafiti entle, amasuntswana akwi-5 ~ 10 m achazwa njengegrafiti ephakathi, amasuntswana akwi-10 m ngasentla achazwa njengegrafiti erhabaxa.
Okukhona ububanzi besuntswana buncinci, kokukhona izinto zibiza kakhulu, kokukhona izinto zegrafiti ezifanelekileyo zinokukhethwa ngokweemfuno kunye neendleko ze-EDM.
3. Ukwenziwa kwe-graphite electrode
I-electrode yegrafiti yenziwa kakhulu ngokusila.
Ngokwembono yetekhnoloji yokucubungula, i-graphite kunye ne-copper zizinto ezimbini ezahlukeneyo, kwaye iimpawu zazo zokusika ezahlukeneyo kufuneka ziqwalaselwe kakuhle.
Ukuba i-graphite electrode icutshungulwa yinkqubo ye-copper electrode, iingxaki ziya kwenzeka ngokungenakuphepheka, njengokuqhekeka rhoqo kwephepha, okufuna ukusetyenziswa kwezixhobo zokusika ezifanelekileyo kunye neeparamitha zokusika.
Umatshini we-graphite electrode udlula ubhedu, xa kujongwa ngokwezoqoqosho, ukhetho lwesixhobo se-carbide lolona lunoqoqosho, ixabiso lesixhobo sokugquma idayimani (esibizwa ngokuba yi-graphite knife) libiza kakhulu, kodwa isixhobo sokugquma idayimani sisebenza ixesha elide, ukuchaneka okuphezulu kokucutshungulwa, inzuzo yezoqoqosho iyonke ilungile.
Ubungakanani be-Angle engaphambili yesixhobo buchaphazela nobomi baso benkonzo, i-Angle engaphambili yesixhobo iya kuba phezulu nge-50% kune-Angle engaphambili ye-15° yobomi benkonzo yesixhobo, ukuzinza kokusika nako kungcono, kodwa okukhona i-Angle inkulu, kokukhona umphezulu womatshini ungcono, ukusetyenziswa kwe-Angle engaphambili yesixhobo kunokufezekisa umphezulu womatshini ongcono.
Isantya sokusika kwimishini singalungiswa ngokwemilo ye-electrode, ngesiqhelo i-10m/min, efana ne-machining ye-aluminium okanye yeplastiki, isixhobo sokusika singafakwa ngqo kwi-workpiece kwimishini eqinileyo, kwaye isiganeko sokuwa kwe-Angle kunye nokuqhekeka kulula ukwenzeka kwimishini yokugqiba, kwaye indlela yokuhamba ngokukhawuleza ngemela elula idla ngokusetyenziswa.
I-electrode yegrafiti kwinkqubo yokusika iya kuvelisa uthuli oluninzi, ukuze kuthintelwe amasuntswana egrafiti aphefumlwayo ngumatshini wokuphotha kunye nezikrufu, kukho izisombululo ezimbini eziphambili okwangoku, enye kukusebenzisa umatshini okhethekileyo wokucubungula igrafiti, enye yindawo eqhelekileyo yokulungisa iziko, exhotyiswe ngesixhobo esikhethekileyo sokuqokelela uthuli.
Umatshini wokugaya okhethekileyo wegrafiti okhawulezayo okwimarike unamandla aphezulu okugaya kwaye unokugqibezela ngokulula ukwenziwa kwee-electrode ezintsonkothileyo ngobuchule obuphezulu kunye nomgangatho olungileyo womphezulu.
Ukuba i-EDM iyadingeka ukwenza i-electrode yegrafiti, kuyacetyiswa ukuba kusetyenziswe izinto zegrafiti ezincinci ezinobubanzi obuncinci.
Ukusebenza kakuhle kwe-graphite ekuchwethezeni akulunganga, okukhona ububanzi be-particle buncinci, kokukhona ukusebenza kakuhle kokusika kunokufumaneka, kwaye iingxaki ezingaqhelekanga ezifana nokuqhekeka kwentambo rhoqo kunye nomphetho womphezulu zinokuthintelwa.
4.EDM parameters ze-graphite electrode
Ukukhethwa kweeparamitha ze-EDM zegraphite kunye nobhedu kwahlukile kakhulu.
Iiparameter ze-EDM ziquka ikakhulu umsinga, ububanzi be-pulse, i-pulse gap kunye ne-polarity.
Oku kulandelayo kuchaza isiseko sokusetyenziswa okunengqiqo kwezi parameters ziphambili.
Uxinano lwangoku lwe-graphite electrode ngokubanzi yi-10~12 A/cm2, inkulu kakhulu kunolo lwe-copper electrode. Ke ngoko, ngaphakathi koluhlu lwangoku oluvunyelweyo kwindawo ehambelanayo, okukhona umbane ukhethwa mkhulu, kokukhona isantya sokucubungula ukukhupha i-graphite siya kuba sincinci, kokukhona ukulahleka kwe-electrode kuya kuba kuncinci, kodwa uburhabaxa bomphezulu buya kuba bukhulu.
Okukhona ububanzi be-pulse bukhulu, kokukhona ilahleko ye-electrode iphantsi.
Nangona kunjalo, ububanzi obukhulu be-pulse buya kwenza uzinzo lokucubungula lube lubi ngakumbi, kwaye isantya sokucubungula sicotha kwaye umphezulu urhabaxa.
Ukuqinisekisa ukulahleka kwe-electrode ephantsi ngexesha lokwenziwa kwe-rough machining, kusetyenziswa ububanzi be-pulse obukhulu, obunokuphumeza ngempumelelo ukwenziwa kwe-graphite electrode elahlekileyo xa ixabiso liphakathi kwe-100 kunye ne-300 US.
Ukuze ufumane umphezulu ocolekileyo kunye nesiphumo sokukhupha esizinzileyo, kufuneka kukhethwe ububanzi obuncinci be-pulse.
Ngokubanzi, ububanzi be-pulse ye-graphite electrode bungaphantsi nge-40% kunobo be-copper electrode
Isithuba se-pulse sichaphazela kakhulu isantya somatshini wokukhupha kunye nokuzinza komatshini. Okukhona ixabiso lilikhulu, kokukhona uzinzo lomatshini luya kuba ngcono, nto leyo eluncedo ekufumaneni ukufana okungcono komphezulu, kodwa isantya somatshini siya kuncitshiswa.
Phantsi kwemeko yokuqinisekisa uzinzo lokucubungula, ukusebenza kakuhle kokucubungula kunokufumaneka ngokukhetha umsantsa omncinci we-pulse, kodwa xa imeko yokukhupha ingazinzanga, ukusebenza kakuhle kokucubungula kunokufumaneka ngokukhetha umsantsa omkhulu we-pulse.
Kwi-graphite electrode discharge machining, i-pulse gap kunye ne-pulse width zihlala zibekwe kwi-1:1, ngelixa kwi-copper electrode machining, i-pulse gap kunye ne-pulse width zihlala zibekwe kwi-1:3.
Phantsi kokulungiswa kwegrafiti okuzinzileyo, umlinganiselo wokufanisa phakathi kwesithuba sepulse kunye nobubanzi bepulse unokulungiswa ube yi-2:3.
Kwimeko yokususwa kwe-pulse encinci, kuyanceda ukwenza umaleko wokugquma kumphezulu we-electrode, nto leyo eluncedo ekunciphiseni ukulahleka kwe-electrode.
Ukukhethwa kwe-polarity ye-graphite electrode kwi-EDM ngokusisiseko kuyafana nokwe-copper electrode.
Ngokwempembelelo ye-polarity ye-EDM, i-positive polarity machining idla ngokusetyenziswa xa kusetyenzwa intsimbi yesinyithi, oko kukuthi, i-electrode iqhagamshelwe kwi-positive pole yombane, kwaye i-workpiece iqhagamshelwe kwi-negative pole yombane.
Ukusebenzisa ububanzi obukhulu bombane kunye nobubanzi be-pulse, ukukhetha i-positive polarity machining kunokufezekisa ilahleko ye-electrode ephantsi kakhulu. Ukuba i-polarity ayilunganga, ilahleko ye-electrode iya kuba nkulu kakhulu.
Kuphela xa umphezulu kufuneka ucutshungulwe kakuhle ngaphantsi kweVDI18 (Ra0.8 m) kwaye ububanzi bepulse buncinci kakhulu, ukucubungula i-polarity engalunganga kusetyenziswa ukufumana umgangatho ongcono womphezulu, kodwa ilahleko ye-electrode inkulu.
Ngoku izixhobo zomatshini ze-CNC edM zixhotyiswe ngemilinganiselo yokucoca i-graphite discharge.
Ukusetyenziswa kweeparamitha zombane kukrelekrele kwaye kungenziwa ngokuzenzekelayo yinkqubo yeengcali zesixhobo somatshini.
Ngokubanzi, umatshini unokumisela iiparameter zokucubungula ezilungiselelweyo ngokukhetha isibini sezinto, uhlobo lwesicelo, ixabiso loburhabaxa bomphezulu kunye nokufaka indawo yokucubungula, ubunzulu bokucubungula, ukulinganisa ubungakanani be-electrode, njl. Ngexesha lokucwangcisa.
Iseti ye-electrode ye-graphite yelayibrari yesixhobo somatshini se-edm ityebile kwiiparameter zokucutshungulwa, uhlobo lwezinto lunokukhetha kwi-graphite erhabaxa, i-graphite, i-graphite ihambelana neentlobo ngeentlobo zezinto zokusebenza, ukuze kwahlulwe uhlobo lwesicelo se-standard, dentic groove, sharp point, indawo enkulu, i-cavity enkulu, efana ne-fine, ikwabonelela ngelahleko ephantsi, umgangatho, ukusebenza okuphezulu, njl.njl. kwiintlobo ezininzi zokukhetha okuphambili kokucutshungulwa.
5. Isiphelo
Izinto ezintsha ze-graphite electrode zifanelekile ukwenziwa zidume kakhulu kwaye iingenelo zazo ziya kuqatshelwa kwaye zamkelwe kancinci kancinci ngumzi-mveliso wezinto zokubumba zasekhaya.
Ukukhethwa ngokuchanekileyo kwezinto ze-graphite electrode kunye nokuphuculwa kwamakhonkco ezobuchwepheshe anxulumeneyo kuya kuzisa ukusebenza kakuhle, umgangatho ophezulu kunye nexabiso eliphantsi kwiinkampani zokwenza izinto zokubumba.
Ixesha lokuthumela: Disemba-04-2020