Stretch bending device for automobile shank protection beam

The automobile shank protection beam stretch bending device comprises a platform, a plurality of clamping mechanisms are arranged on the platform, each clamping mechanism comprises a base, a first air cylinder, a second air cylinder and a pressing plate, the pressing plates and the first air cylinders are arranged on the two sides of the bases correspondingly, and limiting blocks are fixed to the end faces, facing the pressing plates, of the bases; a clamping groove is formed in the end face, facing the pressing plate, of the limiting block and penetrates through the left end, the right end and the top end of the limiting block, a lifting block is arranged above the clamping groove, the top end of the lifting block is fixedly connected with the output end of a second air cylinder, the second air cylinder is fixed to the base, and the top end of the pressing plate extends to form a bent part which is bent towards the base. A rotating block is hinged to the upper end of the end of the bent part, the lower end o