The invention discloses an automatic folding ladder supporting leg bending device which comprises a heating part and a bending part, the heating part can conduct dynamic heating, and the bending part is used for splitting stress. When the square tube is pushed to the heating mechanism, the square tube is pressed through the pressing device, the mounting plate is pushed to move through the telescopic air cylinder after being pressed until one end of the heating device abuts against the square tube, the heating device is started, the heating amplitude of the heating device on the right side of the square tube is larger than that on the left side of the square tube, then the mounting plate continues to be pushed, and under the action of the connecting rod mechanism, the square tube is heated. In addition, the lengths of the connecting rods are set differently, namely, the length of the second connecting rod is reduced, and the lengths of the third connecting rod and the fourth connecting rod are increased, so that the initial heating angle is consistent, and the
heating effect is improved. The same pushing form enables the swing amplitude of the heating device to be distinguished so as to adapt to the difference of core heating areas at the top and the bottom of the square
pipe, so that small gradient heating and key area key heating are realized, the
internal stress after
pipe bending is reduced, and wrinkles are avoided; besides, swing rods are arranged on the two sides, push-pull is conducted on the two sides of each swing device through a push-pull rod, double-side driving is conducted in the push-pull process,
axial force is borne by the swing rods, force in all directions is split, and the problem that local parts are prone to damage when swing is conducted through a single arm is effectively avoided.