Box-shaped structure for work machine

Abstract

A boom includes a body and a base end bracket. The body includes a straight section and a wide section. When viewed from above, a width of the straight section is substantially constant. When viewed from above, a width of the wide section increases toward the base end bracket. The straight section and the wide section are smoothly continuous to each other.

1 . A box-shaped structure for a work machine, comprising:
 a body extending in a longitudinal direction; and   a bracket connected to one end of the body,   the body including a straight section and a wide section, the straight section having a substantially constant width when viewed from above, and the wide section being connected to the bracket and having a width that increases toward the bracket when viewed from above, and   the straight section and the wide section being smoothly continuous to each other.   
     
     
         2 . The box-shaped structure for a work machine according to  claim 1 , wherein
 the body is formed of a top plate, a bottom plate, a first side plate and a second side plate;   the bracket includes a first abutment surface that abuts against the first side plate and a second abutment surface that abuts against the second side plate; and   each of the first abutment surface and the second abutment surface is angled with respect to the longitudinal direction of the body.   
     
     
         3 . The box-shaped structure for a work machine according to  claim 1 , wherein
 the body has a center boss centrally located in the longitudinal direction;   the bracket has an end boss;   the straight section is smoothly continuous to the wide section at a predetermined position between the center boss and the end boss; and   a ratio of a first interval between a center axis of the center boss and the predetermined position to a second interval between a center axis of the end boss and the predetermined position is from 1:1 to 4:1.   
     
     
         4 . A method of manufacturing a box-shaped structure for a work machine, comprising:
 placing a first side plate and a second side plate on a bottom plate;   pushing one end portion of the first side plate and one end portion of the second side plate outward using a lining;   sandwiching and fixing a bracket between the one end portion of the first side plate and the one end portion of the second side plate; and   fixing a top plate on top of the first side plate and the second side plate.   
     
     
         5 . The box-shaped structure for a work machine according to  claim 2 , wherein
 the body has a center boss centrally located in the longitudinal direction;   the bracket has an end boss;   the straight section is smoothly continuous to the wide section at a predetermined position between the center boss and the end boss; and   a ratio of a first interval between a center axis of the center boss and the predetermined position to a second interval between a center axis of the end boss and the predetermined position is from 1:1 to 4:1.