Positioning and welding assembly tool for pi-shaped beam of crane

The invention discloses a positioning and welding assembly tool for a pi-shaped beam of a crane, which comprises two support legs which parallelly extend along an upward direction and a downward direction and a portal support which is formed by a top beam bridged between the two support legs, wherein the top beam extends along a left direction and a right direction, the portal support is provided with a rib plate lifting mechanism for applying an upward lift force to a rib plate of the pi-shaped beam and a web plate pressing mechanism for applying a downward press force to two web plates arranged at two sides of the pi-shaped beam, the rib plate lifting mechanism comprises a lifting device connected onto the rib plate of the pi-shaped beam and a power lifting system for supplying power to the lifting device, and the web plate pressing mechanism comprises a downward pressing device compacted on the web plates and a power compacting system for supplying power to the downward pressing device. The positioning and