| CPC B21D 53/88 (2013.01) [B23K 11/0046 (2013.01); B23K 37/003 (2013.01)] | 18 Claims |

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3. A method for producing a frame structure having a hollow member that is curved along a length of the hollow member and has a long shape, the method comprising: welding a plurality of connecting members to the hollow member along a longitudinal direction of the hollow member; introducing, after the welding, a cooling medium into an inside of the hollow member through an end of the hollow member and repeatedly conducting the welding and the introducing for the plurality of connecting members, wherein the introducing of the cooling medium inside the hollow member is performed after the welding of each connecting member, and the cooling medium is not introduced inside the hollow member during the welding of each connecting member, and wherein the cooling medium is introduced so that the cooling medium touches a bent portion at a weld of the connecting member.
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