Frame structure of construction machine

摘要

A rotating frame (31) and a reinforcing rib (34) which stands upright on a bottom plate (32) of the rotating frame and extends in a front-rear direction are formed integrally with each other by casting. A tube insertion hole (34a) is formed in a base portion of the reinforcing rib (34) in a standing direction thereof such that the tube insertion hole (34a) extends through the base portion of the reinforcing rib in a thickness direction thereof. A communication hole (34b) which communicates with the tube insertion hole (34a) is formed in the bottom plate (32) of the rotating frame (31) such that the communication hole (34b) extends through the bottom plate of the rotating frame in a thickness direction thereof at a position corresponding to the tube insertion hole (34a).