Screwdrivers don't have a round head, because a round head has no torque at all. The word is to guarantee torque, and the cross allows the force to be distributed more evenly. According to the power source, there are manual screwdrivers and electric screwdrivers; according to the batch head or the cutter head, there are a flat head and a cross (phillips).
Lub taub hau ntawm lub siab - zoo ntswj ntsia hlau yog ua los ntawm lub caij nplooj ntoos hlav steel nrog ib tug kuj siab hardness. Ib tug zoo screwdriver yuav tsum nyuaj tab sis tsis nkig, thiab tawv thiab tawv. Thaum qhib lub taub hau ntawm lub taub hau taub hau thiab nplawm, koj tuaj yeem ntaus lub hau ntswj nrog rauj kom lub qhov zawj ntawm cov ntsia hlau sib sib zog nqus, kom cov ntsia hlau tuaj yeem unscrewed yooj yim. Txhob khoov. Feem ntau, nws cia siab tias qhov nyuaj ntawm lub taub hau ntsia hlau yog siab dua HRC60, thiab nws tsis yooj yim rau xeb.
