Electric drill
 

Power tools in the world is born from the--1895 year of the drill began, Germany Fein company developed the world's first direct-current electric drill, drill 14 kg in weight, shell made of cast iron, can only be 4 mm drill holes in steel plate. 　　Followed by a three-phase power frequency (50Hz) electric drill, but failed to break through the 3000r/min motor speed.
In 1914, there were single-phased series motivated motor-driven electric drill, motor speed of more than 10000r/min. 　In 1927, there was a power supply frequency is 150~200Hz-if electric drill, it has the advantage of single phase series motor speed high, but also has the advantage of simple structure, reliable three-phase power frequency motor, but one with a medium-frequency power supply current, use of which is restricted.
 

　60 occurred with nickel-cadmium batteries as power supply-no power cord battery drill. 　　Late to mid 70, battery prices, drill edmcharging time is reduced, this drill in the US and Europe, Japan was widely used. Drill the first cast iron shell, then switched to aluminum alloy shell. 60, thermoplastic plastics application on the drill, and implement double insulation electric drill.