This patent relates to a double-layer hollow
metal plate and its combined structure, particularly to a double-layer hollow
metal plate with inwardly welded openings and its combined structure, comprising a proximal
metal plate (1), multiple inwardly welded components (2), and a distal metal plate (3). The distance between the proximal metal plate (1) and the distal metal plate (3) is greater than 20 mm and less than 150 mm. The proximal metal plate (1) has multiple through holes (11). One end of each inwardly welded component (2) passes through a through hole (11) and is welded to the distal metal plate (3). The inwardly welded component (2) is also welded to the proximal metal plate (1). This patent transforms the disadvantages of small cavities into advantages. The method used is simple and practical. By opening holes in the proximal metal plate as positioning points for the connectors, the difficulty of matching or precisely fitting multiple connectors is reduced. The cost is low and the practicality is high.