What is the working principle of wave soldering tin furnace?

The solid-state relay is used to control the tin furnace, and the temperature in the tin furnace is detected by the temperature detection line. Compared with the program, when the set temperature is reached, the program will send a signal to automatically turn off the solid-state relay. Solid-state relay is a switch controlled by 24V DC power supply. The heating pipe of tin furnace is divided into bottom heating and side heating. The two parts are separated, and the solid state relay is two-sided.