Device for controlling stroke of jacking air cylinder

The invention relates to a device for controlling stroke of a jacking air cylinder. A jacking plate is mounted on a jacking assembly, and the jacking plate is positioned above a bottom plate; an up-pressing assembly capable of controlling the stroke of the jacking plate is mounted between the jacking assembly and the bottom plate; the jacking assembly is matched with the up-pressing assembly to move together; the motion stroke of the jacking plate is controlled by the up-pressing assembly, the jacking plate of the jacking assembly has two stroke sections, wherein the first stroke section is used for firstly moving the jacking plate to a working position for operating a product while the jacking air cylinder does not reach the maximal stroke; the lower bottom surface of the maximal end of an up-pressing wedge block of the up-pressing assembly abuts against rollers on jacking guide post connecting blocks, so that the stroke of the jacking plate is limited by the up-pressing assembly; and the second stroke section is used for enabling the lower bottom surface of the minimal end of the up-pressing wedge block to abut against the rollers on the jacking guide post connecting blocks, so that the jacking air cylinder reaches the maximal stroke, and the jacking plate rises to the maximal position, and therefore, next-step operation can be carried out on a product conveniently.