TRACK FRAME FOR CONSTRUCTION MACHINE

摘要

An outer curved portion (21A) with a recessed groove shape is provided over the entire circumference in a vertically intermediate portion of the outer peripheral surface of a circle member (18), and an inner curved portion (21B) with a recessed groove shape is provided over the entire circumference in a vertically intermediate portion of the inner peripheral surface of the circle member (18) to thereby make it possible to render small the plate thickness (t) of the hourglass-shaped thin-walled portion (21) located in the vertically intermediate portion relative to the plate thickness (T) of upper and lower thick-walled portions (19, 20) located on both vertical end sides of the circle member (18). Consequently, the overall weight of the circle member (18) can be reduced in comparison with a circle member of a prior art having a vertically uniform plate thickness. Additionally, when a vertical load is applied to the circle member (18), stress can be dispersed to the outer curved portion (21A) and the inner curved portion (21B) to thereby make it possible to minimize the occurrence of localized stress concentration in a joint portion between the circle member (18) and a top plate (15) of a center frame (14).