本发明为塑料膜拉伸生产线双层轨道双链条的链铗系统,每一侧有上下2层相同的轨道和上下2根相同的链条,铗体固定连接的纵向截面为“E”形的支承座,上(下)轨道位于上(下)支承板和中支承板之间,上(下)支承板上(下)方固定上(下)层链条的2个链节。中支承板上(下)方固定1个上(下)中内轴承和1个 The invention is a chain double-track chain system of a plastic film stretching production line, wherein each side has two tracks of the same upper and lower layers and two identical chains above and below, and the longitudinal section of the fixed connection is an “E” shape , The upper (lower) track is located between the upper (lower) support plate and the middle support plate, and the two lower chains of the upper (lower) chain are fixed on the lower support plate. In the support plate (lower) side of the fixed 1 (under) in the bearing and a