The technological process of hollow coil is as follows: firstly, the movable skeleton of the coil is selected according to the required size, and the height is padded with hard paper. Let off steam. Winding according to the required data, reaching the required number of turns, and completing the thread end. Then remove the skeleton, check the size, dry it after it is qualified (rewinding it after it is unqualified), and paint it to dry it. It's done.