Positioning device and welding machine

The invention discloses a positioning device and a welding machine, and relates to the technical field of welding equipment, the positioning device comprises a mounting substrate, the mounting substrate is provided with a through hole, and the through hole is provided with a first end, a second end, a third end and a fourth end; the first positioning piece is used for positioning one end of the guide rail body; the second positioning pieces are fixed on the mounting substrate and are arranged between the first end and the first positioning pieces; the first positioning part comprises a first limiting piece and a second limiting piece, the first limiting piece is fixed to the mounting base plate and close to the second end, and the second limiting piece is movably arranged on the mounting base plate and close to the fourth end; the second positioning part comprises a mounting base, a third limiting piece, a positioning component and a first elastic piece, the mounting base is fixed to the mounting base plate a