| 摘要 |
PROBLEM TO BE SOLVED: To reduce the weight of a joint leg and obtain a sufficient welding length for a joint surface which joints the joint legs to avoid stress concentrating caused by a work load and improve rigidity. SOLUTION: A fore-and-aft pair of right-and-left joint legs 61, 71 jointed to a center frame 30 and a side frame 7 for coupling are provided. The joint legs 61, 71 include body portions 62, 72 formed in a sleeve state and a state so as to be widened by a curved surface toward both opening edges, center joint portions 63, 73 which are provided at either opening edge of the body portions 62, 72 and jointed with the center frame 30, and side joint portions 64, 74 which are provided at the other opening edge of the body portions 62, 72 and jointed with the side frame 7. The center joint portions 63, 73 are protruded upward from an upper surface and formed so as to be long in the vertical direction, and the side joint portions 64, 74 are formed along the side frame 7 so as to be long in the fore-and-aft direction. COPYRIGHT: (C)2008,JPO&INPIT
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