JPH06246459A - Resistance welding method - Google Patents

Abstract

PURPOSE:To provide a weld zone excellent in corrosion resistance by arranging a shield cap in the circumference of the weld zone, supplying the inert gas to the surface of the part to be welded through the shield cap, and energizing thereto. CONSTITUTION:A shield cap 3a is arranged so as to surround a spot electrode 1a, and the inert gas 4 is supplied through this shield cap 3a. On the other hand, a shield cap 3b is arranged so as to surround a spot electrode 1b, and the inert gas 4 is supplied through this shield cap 3b. Works 5a, 5b to be welded are inserted between the spot electrodes 1a, 1b, and energized to form the weld zone 6. This constitution provides the weld zone excellent in corrosion resistance in the resistance welding of stainless steel plates or composite steel plate structure where the skin plates are of stainless steel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance welding method for a stainless steel sheet, particularly a multi-layer steel sheet having a stainless steel sheet as a skin.

[0002]

2. Description of the Related Art Stainless steel sheets are widely used in the fields of automobiles, building materials, home appliances, etc. because of their excellent corrosion resistance. On the other hand, a multi-layered steel sheet having a stainless steel sheet as a skin is also excellent in corrosion resistance, and is excellent in workability and cost, and is expected to be developed in the above fields.

When these materials are used in the above fields, resistance welding (spot welding, seam welding) is often used in the assembly stage, but after welding, a discolored portion is generated on the surface of the resistance welding portion and a corrosion resistance test is conducted. Then red rust from this part,
There is a drawback that pitting corrosion occurs.

Therefore, at present, corrosion resistance is ensured by applying a coating process after welding on the surface of the resistance welding portion.

[0005]

However, in the above-mentioned method, it is necessary to coat the entire surface of the resistance welding portion.
Post-welding It is impossible to apply paint treatment to the surface of the weld inside the product. Further, the coating process during the product assembly requires a new coating process on the resistance welding assembly line, which is practically impossible in terms of cost.

The present invention has been made in view of the above problems, and in resistance welding of a stainless steel plate and a multi-layered steel plate having a stainless steel plate as a skin, a welding method capable of ensuring good corrosion resistance without applying a coating process after welding. I will provide a.

[0007]

That is, the inventors of the present invention conducted various experiments to solve the above problems, and as a result, resistance welding (spot welding, seam welding), It is possible to suppress the generation of discolored parts on the surface of the resistance welding part by energizing it while supplying an inert gas to the surface, and to prevent the occurrence of red rust and pitting corrosion from this part even if a corrosion resistance test is performed. Found that the same level of corrosion resistance as the base metal can be secured.

The present invention has been made based on the above findings, and its gist is a method for resistance welding (spot welding, seam welding) of a stainless steel plate and a multi-layer steel plate having a stainless steel plate as a skin. A resistance of a stainless steel plate and a multi-layered steel plate having a stainless steel skin as a skin, characterized in that a shield cap is arranged around the welded part, and current is supplied to the surface of the welded part through the shield cap while supplying an inert gas. It is a welding method. The present invention will be described below with reference to the drawings.

First, FIG. 1 shows a schematic structure when the present invention is applied to spot welding. The spot electrode 1a is fixed to an electrode holder 2a which is a power feeding section. A shield cap 3a is arranged so as to surround the spot electrode 1a, and an inert gas 4 is supplied through the shield cap 3a. On the other hand, the spot electrode 1b is fixed to the electrode holder 2b which is a power feeding portion. A shield cap 3b is arranged so as to surround the spot electrode 1b, and the inert gas 4 is supplied through the shield cap 3b. In this case, a shield cap that is concentric with the spot electrode is used, but there is also a mode in which an inert gas is supplied to the surface of the workpiece from an oblique direction with respect to the spot electrode. Spot electrode 1 in the device configuration of FIG.
When the objects to be welded 5a and 5b are inserted between a and 1b and a current is applied, a welded portion 6 is formed. If there is no inert gas 4,
Discolored portions that are concentric with the spot electrodes 1a and 1b are formed on the spot electrodes 1a and 1b sides of the workpieces 5a and 5b. However, when the surfaces of the objects to be welded 5a and 5b are covered with the inert gas 4, the generation of the discolored portion is not confirmed even if the welded portion 6 is formed.

FIG. 2 shows a schematic structure when the present invention is applied to seam welding. The shield cap 13a is arranged so as to aim at the exit side of the seam electrode wheel 7a, and the inert gas 4 is supplied through this shield cap 13a.
On the other hand, the shield cap 13b is arranged so as to aim at the exit side of the seam electrode wheel 7b.
Inert gas 4 is supplied through. The welded portions 16 are continuously formed by inserting the objects to be welded 15a, 15b between the seam electrode wheels 7a, 7b and energizing them. When the inert gas 4 is not present, the object to be welded is 15a, 1
A discolored portion is formed on the seam electrode wheels 7a and 7b side of 5b. However, when the surfaces of the objects to be welded 15a and 15b are covered with the inert gas 4, the generation of the discolored portion is not confirmed even if the welded portion 16 is formed.

[0011]

【Example】

(1) Spot Welding The sample stainless steel multi-layer steel plate is a combination of 0.6 mm thick mild steel plates with SUS304 having a thickness of 0.1 mm. Spot welding was performed under the following welding conditions by stacking two sheets of the multilayer steel sheets.

Welding electrode: CF type 4.5 mmφ, electrode pressure: 200 kgf, welding current: 8 kA, energizing time: 10
Cycle, shield gas: Argon ... 30 l / min.

Corrosion tests were carried out on the spot welds obtained under the above welding conditions under the following conditions.

Artificial seawater spray for 4 hours, 60 ° C drying for 2 hours,
Moisture in 98% water vapor for 2 hours When a 10-cycle corrosion test was conducted under the above conditions, red rust and pitting corrosion occurred in the sample obtained without shield gas, but both red rust and pitting corrosion occurred in the sample obtained with shield gas. I didn't.

(2) Seam Welding The stainless steel multi-layer steel sheet tested is a combination of a mild steel sheet having a thickness of 0.6 mm and SUS430 having a thickness of 0.1 mm. Seam welding was performed under the following welding conditions by stacking two sheets of the multilayer steel sheets.

Welding electrode wheel: trapezoidal tip width of 4.5 mm, electrode pressing force: 400 kgf, welding current: 14 kA, energizing time: 3 cycles ON-2 cycles OFF, shielding gas: argon ... 50 l / min.

The seam welds obtained under the above welding conditions were subjected to a corrosion test under the following conditions.

Artificial seawater spraying for 4 hours, drying at 60 ° C. for 2 hours,
Moisture in 98% water vapor for 2 hours When a 10-cycle corrosion test was conducted under the above conditions, red rust and pitting corrosion occurred in the sample obtained without shield gas, but both red rust and pitting corrosion occurred in the sample obtained with shield gas. I didn't.

[0019]

As described above, according to the present invention, in a resistance welding (spot welding, sheath welding) method for a stainless steel plate and a multi-layer steel plate having a stainless steel plate as a skin, a shield cap is arranged around the welded portion, It is possible to obtain a weld with excellent corrosion resistance by energizing the surface to be welded with an inert gas supplied through the shield cap, and it is widely used for automobiles, building materials, home appliances, etc. Can be used.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment in which the present invention is applied to spot welding.

FIG. 2 is a schematic view of an example in which the present invention is applied to seam welding.

[Explanation of symbols]

 1a, 1b Spot electrode 2a, 2b Electrode holder 3a, 3b, 13a, 13b Shield cap 4 Shield gas 5a, 5b, 15a, 15b Work piece 6, 16 Welded part 7a, 7b Seam electrode wheel

Claims (2)

[Claims] 1. A spot welding method, which comprises arranging a shield cap around a spot electrode, and energizing the shield electrode in a state where an inert gas is supplied to the surface of an object to be welded through the shield cap. 2. A seam welding method characterized in that a shield cap is arranged around a seam electrode wheel, and current is supplied in a state where an inert gas is supplied to the surface of a welded part through the shield cap.