At the end of 19, in order to grind the gear shaper cutter, the United States built a large plane grinding wheel gear grinder. At the beginning of the 20th century, with the development of automobile industry, Germany developed a conical grinding wheel gear grinding machine, and the United States used a formed grinding wheel to grind automobile gears. 19 14 years, in order to improve the gear accuracy, Switzerland made a dish-shaped grinding wheel gear grinder, and adopted measures such as compensation for grinding wheel wear. In the late 1930s, Switzerland developed a worm grinding wheel gear grinding machine, which improved the efficiency.