Abstract: Entry of molten lead into the space between the electrode plates from the gap between welding jig 12 and electrode plate lead 6 is prevented by a construction of pouring nozzle 17 in which the flow speed and temperature of the molten lead when molten lead is poured into the recess of the welding jig 12 are lowered. Also, admixture of oxide and/or scum is eliminated by discharging the molten lead from the bottom of reservoir 36. Furthermore, reliable joining of strap 2, electrode plate leads 6 and pillar electrode 4 is achieved by prioritising melting of electrode plate leads 6, pillar electrode 4 and the vicinity thereof by plasma welding.

Abstract: A number of strap-forming metal molds 12 corresponding to the number of steps are arranged on a circumferential track and are fed to the devices of the respective steps A.about.F together with electrode plate groups 10. Position A is an electrode plate group 10 introduction position; position B is a flux coating position in which electrode plate leads 6 are coated with flux; position C is an auxiliary heating position in which a mold 8 is heated to the temperature of the molten lead; position D is a molten lead pouring position in which molten lead is poured into a mold 8; position E is a strap-forming position in which electrode plate leads 6 are inserted into the molten lead, fused and cooled and the molten lead is solidified; position F is a discharge position in which a completed electrode plate assembly is discharged. Heating of a mold 8 is commenced by inductive heating from position F and is continued to position E.

Abstract: The invention provides a method for making a thin strap in a stable molten state in producing a plate group for a lead acid storage battery by integrally welding lugs of a plurality of plates of the same polarity by cast-on-strap process. According to the method, the strap is formed in the following manner. A molten lead is fed in a strap forming tool surrounded by an induction heating coil; control of the temperature of the molten lead and preheating of the tips of the plate lugs are carried out by the induction heating coil; the tips of the lugs is dipped in the molten lead and kept at a given temperature; and, thereafter, the mold is forcedly cooled to solidify the molten lead.