| 主权项 |
1. A boom structure, comprising:
an elongated body having a length, a first end and a second end, the first end configured to couple to a dipper at one end of the length and the second end configured to couple to a support structure at the other end of the length; a top member and a bottom member of the body; and a pair of side members of the body coupled to the top member and bottom member, each side member comprising: a first portion extending along the length of the elongated body and from the first end to the second end of the elongated body and forming an outer frame structure, the first portion including an outer surface, an inner surface, and defining a through opening disposed between the outer surface and the inner surface; and a second portion coupled to the top member and to the inner surface of the first portion and being substantially disposed within the outer frame structure, wherein the second portion extends along a substantial portion of the length of the elongated body and from a location adjacent to the top member to a location adjacent to the bottom member and the second portion includes an elongated top edge; and the top member and first portion welded together at exposed surfaces of the first portion and the top member, the bottom member and first portion welded together at exposed surfaces of the first portion and the bottom member; and a top edge of the second portion is welded to a bottom edge of the top member; and a bottom edge of the of the second portion is welded to a top edge of the bottom member; and the second portion is configured to provide a uniform and continuous and uninterrupted weld backup located at a joining interface disposed at the elongated top edge of the second portion and between the top member, the first portion, and the second portion, wherein the joining interface at the second portion forms the weld backup at the exposed surfaces of the first portion, the second portion and the top member, wherein the exposed surfaces at the joining interface include a surface of each of the top portion and the first portion and the elongated top edge of the second portion, such that the continuous and uninterrupted weld backup is made on the exposed surfaces of the top portion and the first portion, and the elongated top edge of the second portion; wherein the joining interface is continuous and uninterrupted along a substantial length of a surface of the top member and the continuous and uninterrupted weld backup extends along the substantial length of the top member such that the second portion is configured as a support structure between the top member and the pair of side members. |
