1. 1895, Germany overtone made the world's first DC drill. The shell is made of cast iron, and 4 mm holes can be drilled in the steel plate. Then a three-phase power frequency (50Hz) electric drill appeared, but the motor speed failed to exceed 3000r/min. In 19 14, electric tools driven by single-phase series motor appeared, and the motor speed reached more than 10000r/min.
Second, in 1927, an intermediate frequency electric tool with power supply frequency of 150 ~ 200 Hz appeared. It has the advantages of high speed of single-phase series motor and simple and reliable structure of three-phase power frequency motor, but its use is limited because it needs intermediate frequency current to supply power.
3. According to the statistics of "Analysis Report on Production and Marketing Demand Forecast and Transformation and Upgrading of China Power Tool Industry", power tools are mainly divided into metal cutting power tools, grinding power tools, assembling power tools and railway power tools. Common electric tools include electric drill, electric grinder, electric wrench and electric screwdriver, electric hammer and impact electric drill, concrete vibrator and planer.
4. In order to consolidate the market occupied in 20 12 and further cultivate and explore new markets, we will focus on the following aspects in the future: further improve product quality and accelerate the development of new products. In particular, we should focus on accelerating the development of battery-powered electric tools and electronically controlled electric tools, and constantly improve the level and product quality of electric tools.
Five, the production line of electric tools generally adopts flexible speed-increasing chain conveyor line, which cooperates with tooling board and various station appliances to complete the assembly process. The detection line adopts live closed plate chain conveyor line and special detection instruments and equipment to complete the aging detection process. The detection line contacts with the charged copper bars laid in the wire body through the copper conductive wheels on the chain plates, so that each chain plate is charged, and the workpiece is connected with the multi-purpose socket arranged on the chain plates, so as to carry out charging and aging detection along with the movement of the wire body.
6. Matters needing attention in purchasing power tools: First of all, power tools are hand-held or mobile mechanized tools driven by motors or electromagnets and driven by transmission mechanisms. Power tools have the characteristics of convenient carrying, simple operation and diverse functions, which can greatly reduce labor intensity, improve work efficiency and realize manual operation mechanization, so they are widely used in buildings, house decoration, automobiles, machinery, electric power, bridges, gardens and other fields, and have entered a large number of families.