Qhov no yog qhov profile tooj dag pas nrig. Feem ntau cov pas nrig tooj dag peb yuav yog cylindrical, yog tias peb xav ua cov square, peb yuav tsum mus dhau txheej txheem forging. Tab sis qhov no yog cov duab thaum peb yuav nws. Peb feem ntau siv nws los ua cov dej tooj dag, thiab peb tsuas yog yuav tsum tau ua tiav xws li drilling qhov ntawm tus pas nrig tooj dag.
