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Introduction To Power Tools
- May 01, 2018 -

In 1895, the German overtone produced the world's first DC drill. The housing is made of cast iron and can drill 4mm holes in the steel plate. Then appeared three-phase power frequency (50Hz) drill, but the motor speed did not break through 3000r/min. In 1914, there appeared a single-phase series motor driven power tools, motor speed of up to 10000r/min. In 1927, there appeared a power supply frequency of 150~200hz, if power tool, which has the advantage of high speed of single-phase series motor, but also has the advantages of simple and reliable structure of three-phase frequency motor, but because of the use of medium-frequency current power supply, using limited.