Komatsu Corporation

Kabushiki Kaisha Komatsu Seisakusho

Hidetoshi Sasaki

Tatsushi Itoh

Toshio Tanaka

Nobuyoshi Masumoto

Satoru Nishimura

Youjirou Ohbatake

A boom body comprises a boom front member, a boom intermediate member and a boom rear member. An arm-connection bracket is jointed to the boom front member and a vehicle body-mounting bracket is jointed to the boom rear member, thereby forming a boom. With this structure, a cross section of the boom body is less prone to be deformed and therefore, the plate thickness can be reduced, the rigidity of the boom body can be increased without mounting a cross section restraint material and the cross section of the boom is not deformed. Therefore, it is possible to reduce the boom in weight.

Method for making a boom of an excavator

An arm body of a working machine has a hollow and triangular cross-section. A bucket-connection bracket is jointed to one longitudinal end of an arm body, and an arm cylinder bracket is jointed to another longitudinal end of the arm body, thereby forming an arm. With the triangular cross-sectional structure, the arm body is less prone to deformation under the stress of a load. The improved triangular cross-sectional structure permits the plate thickness of the arm body to be reduced, and the rigidity of the arm body to be increased without mounting a cross-section restraint material in the arm body. The cross-section of the boom will not deform even though the plate thickness is reduced. Therefore, it is possible to reduce the weight of the boom and still prevent deformation of the boom under heavy load. A method of producing an arm body is efficient and simplified since a single sheet of metal may be formed into a triangular shape, with a single welded seem being formed at the seem between abutting edges of the metal material. The various corners of the triangular cross-section may be arc shaped or flat as is desired.

Structure for working unit for bucket excavators and method for manufacturing the same

A boom body ( ) comprises a boom front member ( ), a boom intermediate member ( ) and a boom rear member ( ). An arm-connection bracket ( ) is jointed to the boom front member ( ) and a vehicle body-mounting bracket ( ) is jointed to the boom rear member ( ), thereby forming a boom. With this structure, a cross section of the boom body ( ) is less prone to be deformed and therefore, the plate thickness can be reduced, the rigidity of the boom body ( ) can be increased without mounting a cross section restraint material and the cross section of the boom is not deformed. Therefore, it is possible to reduce the boom in weight.

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Kawasaki, Japan

Hidetoshi Sasaki