Welding-wire-straightening apparatus

A welding-wire-straightening apparatus for straightening bend of a welding wire, comprising two roller groups each including a plurality of straightening rollers, the welding wire being passed through the two roller groups,

• wherein the plurality of straightening rollers included in each of the roller groups are arranged with a predetermined arrangement interval L in a passing direction of the welding wire so as to be opposed across a straightening path along which the welding wire is passed,
• the two roller groups are arranged so that opposing directions across the straightening path are different,
• in each of the roller groups, the plurality of straightening rollers are such that a first roller, a second roller, . . . , nth roller are sequentially disposed in the passing direction of the welding wire, bending deformation in opposite directions is alternately applied to the welding wire by these n rollers (n is an integer greater than or equal to 4) to straighten curl,
• let t (mm) be a diameter of the welding wire,
• let δin (mm) be an entrance roller engaging amount caused by the first roller, the second roller and the third roller,
• let 2Lin (mm) be an interaxial distance between the first roller and the third roller,
• let gin (mm) be an entrance chord length which is a chord length of an overlapping portion of the second roller with the welding wire under an assumption that the welding wire is linearly arranged to come into contact with the first roller and the third roller,
• let δout (mm) be an exit roller engaging amount caused by the (n−2)th roller, the (n−1)th roller and the nth roller,
• let 2Lout (mm) be an interaxial distance between the nth roller and the (n−2)th roller,
• let gout (mm) be an exit chord length which is a chord length of an overlapping portion of the (n−1)th roller with the welding wire under an assumption that the welding wire is linearly arranged to come into contact with the (n−2)th roller and the nth roller, then
• the n straightening rollers are positioned so that an entrance wire deformation parameter Cin calculated by a mathematical expression Cin=Lin/[{(δin+t)/gin}2] is 1150 to 1500, and an exit wire deformation parameter Cout calculated by a mathematical expression Cout=Lout/[{(Sout+t)/gout}2] is 4300 to 49000, and
• the n straightening rollers are positioned so that a welding-wire-feed resistance parameter F calculated by a mathematical expression F=(Lin/Cin+Lout/Cout)×n is less than 0.037.