The birth of the world's electric tools started from the electric drill products. In 1895, Germany developed a direct current electric drill in the world. The weight of this electric drill was 14 kilograms, the shell was made of cast iron, and only 4 mm holes could be drilled in the steel plate. Then came the three-phase power frequency (50Hz) drill, but the motor speed failed to break 3000r/min.
In 1914, the electric drill driven by single-phase series motor appeared, and the motor speed reached more than 10000r/min.
In 1927, IF electric drill with power supply frequency of 150 ~ 200Hz 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 it needs to use if current for power supply.
In the 1960s, there was a battery drill with no power cord, which was powered by nickel-cadmium batteries. By the mid to late 1970s, this kind of electric drill was widely used in Europe, the United States and Japan due to the lower battery price and shorter charging time.
At first, the drill was made of cast iron, but later it was made of aluminum alloy. In the 1960s, thermoplastic engineering plastics were applied to electric drill and realized the double insulation of electric drill.
The 60 s also appeared the electronic speed control drill. This kind of electric drill using thyristor and other components of the electronic circuit, to switch the snap button is snapped into the depth of different to adjust the speed, so that the drill in use can be processed according to the different objects (such as different materials, drilling diameter size, etc.), choose different speed.
The principle of
The working principle of electric drill is that the motor rotor of electromagnetic rotary or electromagnetic reciprocating small capacity motor does magnetic field cutting work operation, through the transmission mechanism to drive the operating device, drive the gear to increase the power of the drill, so that the drill scrapes the surface of the object, better penetration of the object.