1. Principle of sheet metal repair machine: The sheet metal repair machine has two contacts, one is directly clamped on the car body, and the other is to pull up the point to be repaired. The principle estimation is to use adjustable voltage to short-circuit the contact between the car body and the point to be repaired, stick them together, and then pull out the concave part by hand.

2. Multifunctional sheet metal repair machine. The current adjusting knob on one side of the machine has four gears, namely 0, strong, b and weak. When in use, it is adjusted according to the thickness of body steel plate required for sheet metal repair. The thicker the steel plate, the stronger the current. The time adjustment of one side is selected according to the thickness and depression degree of the car body steel plate. If the steel plate in the concave part of the car body is thick and the concave degree is serious, it will take a long time, and vice versa.