Maziko a luso la kuwotcherera
Kuwelda ndi kulumikiza zitsulo za kapangidwe kofanana kapena kofanana mothandizidwa ndi kutentha, ndi kapena popanda kuwonjezera chitsulo chomwecho kapena chofanana. Pogwiritsa ntchito kuwelda, mbali zimamangirizidwa mosasiyanitsidwa moti zimapanga umodzi umodzi. Kuwelda kwabwino kumafuna kulumikizana kwapamtima, komwe kumatheka kokha ngati pa malo a kuwelding zinthu zazikulu zimathanso kusungunuka (dera la uvara).
Kuwotcherera kwa arc yamagetsi
Kwa zomangamanga zachitsulo, choyamba chimaganiziridwa kuwotcherera kwa arc yamagetsi, komwe kutentha kofunikira kumapezeka ndi arc yamagetsi ya lawi. Arc yamoto imapangidwa pakati pa chidutswa choyambira ndi chotchedwa elekitirodi, chomwe chimasungunuka ndipo chimapereka zinthu zowonjezera. Kusankha koyenera kwa zinthu zowonjezera (elekitirodi) kumakhudza kwambiri makhalidwe a cholumikizira chowotcherera. Ma elekitirodi amasankhidwa malinga ndi mphamvu zachizolowezi za zinthu zoyambira zomwe zikuwotchereredwa. Kusankha ma elekitirodi, kudziwa mikhalidwe ya kuwotcherera kumafuna chidziwitso cha akatswiri, chifukwa chake adapanga bungwe la “mainjiniya apadera a njira ya kuwotcherera” ophunzitsidwa mwapadera, omwe ntchito yawo, mwa zina, ndi kuyang’anira ntchito za kuwotcherera ndi kubwereza nthawi zonse ma certification a owotcherera.
Kuwotcherera ndi kudula ndi gasi
Pa kuwotcherera ndi gasi, kutentha kofunikira kumapangidwa ndi kuyaka kwa gasi, motero zinthu zoyambira ndi zowonjezera zimasungunuka. Chofunika kwambiri ndi kudula. Chida chodulira chili, kuphatikiza pa chubu cha kutentha, lomwe limagwira ntchito mofanana ndi pa kuwotcherera, ndi chubu lina lodulira la oxygen. Chitsulo chomwe chatenthedwa ndi lawi lotentha chimabowola ndipo chimawombedwa ndi mtsinje wa oxygen. Kudula kumapereka ma surface osalala ndi olondola omwe akwanira pa zolinga zambiri za zomangamanga zachitsulo popanda kukonza kwina.
Kuwotchereka
Poyesa ma weld joint, tiyenera kuganizira kuti pa ndondomeko ya kuwotcherera kapangidwe ka filler material, komanso ka material yoyambira, kangasinthe kwambiri. Kufunika kwakukulu kulinso ndi kusintha kwa kapangidwe - pakati pa seam yosungunuka ndi material yoyambira yosasintha pali, malinga ndi mmene kutentha kwakhudzira, dera la kapangidwe kosiyanasiyana ndipo chifukwa chake la makhalidwe osiyanasiyana. Pafupi ndi seam pali dera limene material yoyambira inayeyuka (zone ya fusion) ndipo kumeneko kumachitika kulumikizana pakati pa zone ya kuwotcherera ndi material yoyambira. Dera lozungulira la material limatenthedwanso kwambiri, ngakhale kumeneko malo osungunuka sanakwanitsidwenso. M’dela ili la kutenthedwa kwambiri pamachitika kusintha kwakukulu kwa kapangidwe, motero nthawi zambiri limakhala lofunika kwambiri pa makhalidwe a weld joint yonse.
Cracking of the weld means the appearance of cracks in the weld, which arise immediately after welding while the temperature is still high, or perhaps only during cooling in the blue heat range (at about 300°C). Cracking is to a high degree a property of electrodes; it occurs almost only with coated electrodes, which are precisely important for steel structures. For cracks to occur, two conditions must be met, namely high stresses caused by the welding process or other external influences, as well as an increase in the rigidity of the material.
Kupatula kusintha kwa metaluriji mu kapangidwe ndi dongosolo la zinthu, njira zakuthupi zofunika kwambiri ndi zomwe zikugwirizana ndi kuchuluka kwakukulu kwa kutentha komwe kumaperekedwa ku zinthu pa kuwotcherera ndi kutentha kwakukulu komwe kumafikidwa. Kutenthetsa sikuchitika mofanana, koma m’madera ochepa okha. Kukula kwa kutentha komwe kumagwirizana ndi kutenthetsa kumalephereka ndi kupanikizika kwamkati kwa gawo lotenthedwa kuchokera ku zinthu zosatenthedwa. Kuphatikiza apo pamabwera kupanikizika kwakunja, chifukwa mbali zimayenera kukhomereredwa mwamphamvu pa kuwotcherera, choncho pakutenthetsa pamakhala kukanikizika kwa pulasitiki. Pa kuziziritsa, msoko ndi malo ozungulira ake amafupikitsidwa kwambiri (kufupikitsa). Pa kuziziritsa, chifukwa cha kutambasulidwa koletsedwa, zovuta zokakamizidwa ziyenera kuwoneka (zovuta za kufupikitsa). Kutenthetsa koyambirira kwa mbali zomwe zikuwotcheredwa mpaka 200 oC mpaka 300 oC kungachedwetse kuziziritsa kwambiri. Chifukwa cha kuchepetsa mphamvu ya kuuma, kapangidwe kabwino kwambiri ka dongosolo kamapezeka, kuuma kumakhala kochepa.
Kuyesa zinthu ndi ntchito za kuwotcherera
Zonse: Popeza khalidwe la ntchito za kuwotcherera limadalira zinthu zambiri, ndipo osati chomaliza pa luso ndi kudalirika kwa wogwira ntchito wophunzitsidwa, nkofunika kuyang’anira mosamala ndi kuyesa ntchito zonse za kuwotcherera. Pa mayeso akutchulidwa amene amafuna kudziwa kuthekera kwa kuwotcherera kwa zinthu ndi maelekitirodi, kuyerekezera mikhalidwe ya kuwotcherera ndi njira za kuwotcherera pa nkhani ina yopatsidwa, mayeso a zitsanzo ndi zina zotero.
Chith. 1 - Kuyesa kupindika kwa msoko wozunguliridwa
Chiyeso chopinda pa msoko wotsekemeredwa: Ichi ndi chiyeso chopinda cha mtanda wosavuta wa gawo la makona anayi (sl. 1), pamene poyambira pamtunda wautali pa ulusi wokokedwa, womwe wakonzedwa mu mawonekedwe a theka la bwalo, umasokedwanso ndi gawo limodzi ndipo pa kutentha kwa chipinda. Msoko umachepetsa kwambiri kuthekera kosintha mawonekedwe, moti mayesowo nthawi zambiri amasweka mwamphamvu kwambiri komanso mwadzidzidzi. Ngodya yopindika pa mbale zoonda imakhala yayikulu, ndipo imachepa pamene makulidwe a mbale akukula.
Notch toughness: In the bending test of the weld, cracks mostly first appear in the weld, so that brittle fracture occurs. The base material must be able to absorb the load that arises suddenly during brittle bursting of the weld. It should be required that the crack in the weld zone does not spread rapidly through the base material, but that the crack may advance only slowly. The base material must be sufficiently tough to absorb this sudden load, and this ability must remain sufficiently present even at low temperatures. Notch toughness, as well as other mechanical properties, depend greatly on the temperature at which the test is carried out. At low temperatures, for example below 0 °C, it can fall to a fraction of the value at 20 °C. The position of this sudden drop is important for assessing a material. For welded steel structures, material with good aging resistance is required today, that is, high notch impact strength in cold drawn specimens.
Chith. 2 - Kupunduka pa malo a zovuta za notch
Kulimba: Zochitika za kulimba m’dera la kuwotcherera ndi zofunika kwambiri. N’zofunika kudziwa kuwonjezeka kwa kulimba, chifukwa kutalikira pa kusweka kumachepa mofulumira pamene kulimba kukuchulukira (chith. 3), pamene mphamvu yokokera σB imakwera pafupifupi mogwirizana ndi kulimba kwa Brinell HB. Kwa zitsulo zomangira, pafupifupi σB = 0,36*HB. Chitsanzo chimodzi cha kulimba kwa msoko waukulu wa ngodya pa I-beam chikuwonetsedwa pa chith. 4. M’dera losintha muli kusiyana kwakukulu kwa kulimba pa mtunda wochepa kwambiri. Njira ya kulimba imadalira kapangidwe kamene kapangidwa. Mzere wa σ-ε-l umasinthanso mofanana ndi kulimba monga momwe umachitira pa mkhalidwe wa ma stress pa notch (chith. 2).
Chith. 3 - Kuuma kwa Brinell ndi kutalika kwa kutambasuka
Chith. 4 - Kuuma m’dera la msoko pa khosi la I-chonyamulira chowotcheredwa
Kuyesedwa kopanda kuwononga kwa ma weld omalizidwa
Kuyang’ana ndi rayi – Pakuyang’ana zinthu zopyapyala, chithunzi cha X-ray chingapangidwe chiwonekere pa chinsalu chimodzi. M’malo mwa ma X-ray angagwiritsidwe ntchito ma gamma kuchokera ku zinthu za radioaktivu. Chithunzi cha X-ray chimalola kuzindikira ubwino wa weld. Zotayidwa zomwe zili mkati kapena ma pore, komanso zolakwika pakumangirirana ndi ming’alu, zingathe kuzindikiridwa motere ndipo, ngati kuli kofunika, kuchotsedwa.
Kudutsa kwa maginito – Amapanga munda wa maginito m’gawo la chitsulo chomwe chikufufuzidwa, ndipo tchipisi tomwe tayikidwa timakonzedwa motsatira mundawo. Kuchokera ku zolakwika zilizonse m’munda wa maginito kungadziwike ming’alu. Njirayi ndi yogwira bwino kwambiri makamaka pa kupeza ming’alu yapamwamba, koma imakhala yopanda chidwi kwambiri pa zophatikizika za slag ndi mabowo, komanso pa ming’alu yomwe ili mkati mwa mbale zokhuthala.
Kuyezetsa ndi ultrasound – Mafunde a mawu aafupi kwambiri amawunikira osati pa pamalo a malire okha, komanso pa malo ogawanira mkati monga pa ming’alu kapena malo odulirana.