JPH0224192B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides continuous dot resistance welding.
The present invention relates to a method for suppressing the shunt of welding current to a previously welded nugget.

Generally, a front perspective view of the vicinity of an electrode subjected to resistance welding is shown in FIG. In the figure, 1 is the upper electrode, 1' is the lower electrode, 2 is the upper welded material, 2' is the lower welded material, 3 is the current flowing, and 4
indicates a weld nugget. Material to be welded 2,
2' is pressurized by the electrodes 1 and 1', and in this state, the welding current passes through the path of the current 3 to form a weld nugget 4 between the upper workpiece 2 and the lower workpiece 2'. The materials to be welded 2 and 2' are joined together.

By the way, in resistance welding, structures are usually assembled by continuous dots, and in this case, a front perspective view of the vicinity of the electrode is shown in FIG. In FIG. 2, the same reference numerals as in FIG. 1 indicate the same or corresponding parts. 3' is welding current, 3'' is shunt current, 4'
is a welded nugget.

In the case of continuous welding, the current 3 flowing through the electrode is divided into a welding current 3' that contributes to joining, and a shunt current 3'' that flows to the already welded nugget 4' and does not contribute to joining. If the values of 3 are the same, the diameter of the weld nugget 4 formed between the welded materials 2 and 2' will be smaller than the diameter of the already welded nugget 4', resulting in a disadvantage that the joint strength will be reduced. The diameter of this weld nugget 4 is increased,
In order to ensure the bonding strength, it is necessary to increase the current 3, which has the disadvantage of increasing welding costs.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional method, and in order to interrupt the current path between the welded nugget and the electrode, a part or the entire surface of the material to be welded is coated. A ferromagnetic material such as pure iron, sendust alloy, or permalloy alloy is arranged and fixed, thereby increasing the impedance of the electric circuit between the electrode and the welded nugget, suppressing shunt current, and obtaining a welded nugget with high strength. The present invention provides a method for suppressing shunt flow in resistance welding.

An embodiment of the present invention will be described below with reference to FIG. Figure 3 is a front perspective view of the vicinity of the electrode.
The same reference numerals as in FIG. 1 or 2 indicate the same or corresponding parts. Codes 5 and 5' are insulators, 6,
Reference numeral 6' denotes a rectangular pure iron plate which is disposed and fixed on the surfaces of the welded materials 2, 2' between the already welded nuggets 4' and the welding nuggets 4 via the insulators 5, 5'. The straight line connecting the welded nugget 4' and the electrodes 1, 1' coincides with the center line of the pure iron plate.

By arranging the pure iron plates 6, 6' as described above, when the peak time of the current 3 is short, that is, when the frequency of the current 3 is high, the shunt current 3'' and the pure iron plates 6, 6 Due to the mutual induction with As a result, the shunt current 3'' is hardly generated, and the diameter of the weld nugget 4 becomes almost the same as that of the already welded nugget 4', and there is no reduction in joint strength.

The closer the materials to be welded 2, 2' and the pure iron plates 6, 6' are, the higher the mutual inductance will be, and theoretically the effect of suppressing shunt flow will be greater. materials 2, 2' and pure iron plate 6,
It was confirmed that the effect of suppressing shunt current is greater when insulated from 6'. In addition, a rectangular pure iron plate 6,
Experiments have shown that unless the long side of 6' is at least twice the weld pitch and the short side is at least 1/3 and less than 1 times the weld pitch, a sufficient shunt flow suppression effect cannot be obtained. was confirmed.

In the above embodiment, pure iron plates 6, 6' are used to suppress the shunt, but other ferromagnetic materials such as sendust alloy plates or permalloy alloys may be used instead. Further, it is desirable to use a phase-controlled resistance welding machine with a short pulse height time or a capacitor type resistance welding machine with a short pulse height time for this welding.

As described above, in this invention, a ferromagnetic material such as a pure iron plate is placed and fixed on a part or the entire surface of the welded material so as to interrupt the current path between the already welded nugget and the electrode. A strong weld nugget can be obtained by suppressing the shunt to the weld nugget.

[Brief explanation of drawings]

Fig. 1 is a front perspective view to explain general resistance welding, Fig. 2 is a front perspective view of the vicinity of the electrode to explain conventional resistance welding using continuous dots, and Fig. 3 is a front perspective view to explain general resistance welding.
The figure is a front perspective view of the vicinity of an electrode showing an embodiment of the present invention. 1: Upper electrode, 1': Lower electrode, 2: Upper welded material, 2': Lower welded material, 3: Current supply, 3':
Welding current, 3″: shunt current, 4: welding nugget,
4': already welded nugget, 5: upper insulator, 5': lower insulator, 6: upper pure iron plate, 6': lower pure iron plate.

Claims (1)

[Claims] 1. In resistance welding that involves continuous welding, a ferromagnetic material such as pure iron, sendust alloy, or permalloy alloy is applied to the surface of the welded material so as to block the current path between the welded nugget and the electrode. A method for suppressing shunt current in resistance welding, which comprises arranging and fixing the electrode, and applying welding current to the electrode in this state. 2. The shape of the ferromagnetic material is 2. The long side is the welding pitch.
The ferromagnetic material shall be arranged so that the straight line connecting the already welded nugget and the electrode coincides with the central axis of the ferromagnetic material. A method for suppressing shunt flow in resistance welding according to claim 1, characterized in that: 3. The shunt suppression method for resistance welding according to claim 1 or 2, using a phase-controlled resistance welding machine with a short pulse height time or a capacitor type resistance welding machine with a short pulse height time as the welding machine. 4. Claim 1, characterized in that the ferromagnetic material is brought close to the material to be welded via an insulator,
The resistance welding flow dividing method according to item 2 or 3.