Work implement of hydraulic excavator and method of manufacturing work implement of hydraulic excavator

Abstract

The number of steps required for a welding operation of a work implement of a hydraulic excavator is reduced while the welding quality is improved. A boom includes a top plate, a left side plate joined to the top plate, and a boom foot bracket. The boom foot bracket includes an extending portion. The extending portion includes a portion that faces a side surface of the top plate.

1 . A work implement of a hydraulic excavator, the work implement comprising:
 a first plate material;   a second plate material joined to the first plate material;   a third plate material joined to the first plate material and facing the second plate material at a distance from the second plate material; and   a fourth plate material joined to the second plate material and the third plate material and facing the first plate material at a distance from the first plate material,   the first plate material, the second plate material, the third plate material, and the fourth plate material being joined to one another to form a box-shaped structure body,   the work implement further comprising   a first attachment member joined to each of the first plate material, the second plate material, the third plate material, and the fourth plate material at an end of the box-shaped structure body in a longitudinal direction of the box-shaped structure body,   the first attachment member including an extending portion that extends in the longitudinal direction of the box-shaped structure body,   the extending portion including a portion that faces a side surface of the first plate material.   
     
     
         2 . The work implement of a hydraulic excavator according to  claim 1 , wherein a cutout portion is provided in a portion of the first plate material that faces the extending portion. 
     
     
         3 . The work implement of a hydraulic excavator according to  claim 2 , wherein
 the first plate material includes
 a first surface that forms an outer surface of the box-shaped structure body, and 
 a first back surface on an opposite side of the first surface, 
   a portion of the first attachment member that faces the first back surface is provided with a groove preparation surface that forms a groove together with the first back surface, and   a portion of the side surface that includes the cutout portion in the first plate material and a bottom portion of the groove are continuous with each other when seen from a direction perpendicular to the first surface.   
     
     
         4 . The work implement of a hydraulic excavator according to  claim 2 , wherein the cutout portion is formed in the longitudinal direction of the box-shaped structure body so as to extend from an end of the first plate material beyond a leading end of the extending portion in the longitudinal direction. 
     
     
         5 . The work implement of a hydraulic excavator according to  claim 1 , wherein the extending portion has a bank shape formed such that a protrusion height decreases toward a leading end of the extending portion in the longitudinal direction. 
     
     
         6 . The work implement of a hydraulic excavator according to  claim 1 , wherein the first attachment member is a cast product. 
     
     
         7 . A method of manufacturing a work implement of a hydraulic excavator, the work implement including:
 a first plate material;   a second plate material joined to the first plate material;   a third plate material joined to the first plate material and facing the second plate material at a distance from the second plate material; and   a fourth plate material joined to the second plate material and the third plate material and facing the first plate material at a distance from the first plate material,   the first plate material, the second plate material, the third plate material, and the fourth plate material being joined to one another to form a box-shaped structure body,   the work implement further including   a first attachment member joined to each of the first plate material, the second plate material, the third plate material, and the fourth plate material at an end of the box-shaped structure body in a longitudinal direction of the box-shaped structure body,   the first attachment member including an extending portion that extends in the longitudinal direction of the box-shaped structure body,   the extending portion including a portion that faces a side surface of the first plate material,   the method comprising:   forming a recess portion as a partial recess in a surface of the first attachment member, the recess portion being located between the extending portion and the side surface of the first plate material that faces the extending portion; and   filling up the recess portion by welding.