Rau shafts, dov thiab forging yog ob txoj kev tsim khoom.Ob hom yob qhov sib txawv ntawm cov txheej txheem tsim khoom, cov yam ntxwv ntawm cov khoom siv, cov khoom siv kho tshuab, thiab cov kev siv dav dav.1. Cov txheej txheem ntau lawm: Rolled ncej: Lub dov ncej yog tsim los ntawm tsis tu ncua nias ib ...
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