| 摘要 |
PROBLEM TO BE SOLVED: To provide a connecting structure for double core members, which can have the double core members connected together through simple works to improve productivity, and solidly builds up the double core members with high accuracy. SOLUTION: An external frame body 2 is constructed by connecting a horizontal core member 10 having connecting claws 13, and a horizontal core member 20 having, on both edges thereof, engaging grooves 25 having the connecting claws engaged therewith, connecting surfaces 24 engaged with side surfaces of the respective connecting claws 13, and welding windows 27. The method of producing the horizontal core member 20 is comprised of the steps of extruding a pipe main body 21 having concave projections 29 and concave grooves 23 on both side surfaces, and inserting a cutting tool from one of the edges into the pipe main body 21 in a manner cutting out the edge of the concave projection 29, whereby the engaging grooves 25, the connecting surfaces 24, and the welding windows 27 are simultaneously formed and produced.
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