Today, let's learn about the history of revolving doors. In Italy in the 1920s, several two wing doors were made. At that time, the two wing doors were designed to swing in two directions. Later, a Swedish revolving door manufacturer introduced a new two wing door. They added motors and booths to the original design. There were also three wing doors and four wing doors. The three wing revolving door is very common in airports and hotels. The smaller door is suitable for hand luggage, and the revolving door with a diameter of 4.2 ~ 5.4m is more convenient for luggage carts. The use efficiency of the four wing door is higher, and the traffic volume is greater. When a four wing revolving door with a diameter of 2m rotates at the speed of 10R / min, people can pass through 10x4x60 = 2400 (people) in two directions per hour at normal walking speed. Four wing revolving door is most widely used in office buildings, hotels and other places. The five wing door has not been developed so far, and there is still no market. Two special-purpose designs are proposed in the original patent: one is that the door body can move to the side; The other is "breaking through the door". These designs were popular before today's foldable doors became popular