The birth of electric tools in the world began with the electric drill products - in 1895, Germany developed the world's first direct current electric drill, which weighs 14 kilograms and is made of cast iron. It can only drill 4 mm holes in steel plates. Then three-phase power frequency (50Hz) electric drill appeared, but the motor speed failed to exceed 3000r/min.
In 1914, an electric drill driven by a single-phase series-excitation motor appeared, and the speed of the motor was over 10,000 r/min.
In 1927, a medium frequency drill with power supply frequencies of 150-200 Hz appeared. It not only has the advantages of high speed of single-phase series motor, but also has the advantages of simple structure and reliability of three-phase power frequency motor. However, its use is limited because of the need for medium frequency current to supply power.
In the 1960s, a battery electric drill without power supply wire was developed, using nickel-cadmium batteries as power supply. By the mid and late 1970s, because of lower battery prices and shorter charging time, this drill was widely used in Europe, America and Japan.
The electric drill used cast iron as its shell at first, and then aluminum alloy as its shell. In the 1960s, thermoplastic engineering plastics were applied to electric drills, and double insulation of electric drills was realized.
In the 1960s, electronic speed-regulating electric drills appeared. This kind of electric drill uses thyristor and other components to form an electronic circuit to adjust the rotational speed according to the different depth of switching button being pulled in, so that different rotational speeds can be selected according to the different objects being processed (such as different materials, diameter of drilling holes, etc.).