JPS62212077A - Resistance welding method - Google Patents

Abstract

PURPOSE:To improve the quality of a joining part by surely performing a welding, by electrifying the two electrodes having a different contact area with their press contact from the above of the welding material overlapped on a fixed material to be welded. CONSTITUTION:Two electrodes 1, 2 having different cross sections are arranged in above V form at the upper part of a base 3. The metal plate of the material 4 to be welded is placed on the base 3 and the metal wire of the welding material 5 is overlapped thereon. These electrodes 1, 2 are electrified with pressure by moving for the welding material 5 from the upper part of the welding material 5. The welding can be performed in short time because the electrode part having small sectional area becomes in a molten state quickly, when a pressure electrification is performed in this way. Consequently, a good diffusion welding can be performed surely.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for spot welding two metals together by resistance welding.

[Prior Art] Conventionally, a resistance welding method has been used to spot weld metal plates, metal wires, or metal wires and metal plates. In this method, the metal to be welded, that is, the material to be welded and the material to be welded, are placed one on top of the other, and they are sandwiched between round rod-shaped electrodes and then pressurized and energized to heat the metal with Joule heat, melting it and forming dots. This is a method of press-fitting. In particular, when the metal to be welded cannot be sandwiched between the electrodes from both sides, two electrodes 8°8 are placed side by side at a predetermined distance as shown in Fig. 5, and the fixed workpiece 4 and the A method is used in which the welding material 5 is sandwiched between the electrodes 8, 8, and the welding material 5 is pressurized by the electrodes 8, 8 and energized to make the welding material 5 press-welded.

[Problems to be Solved by the Invention] In this method, when the distance between the two electrodes 8.8 becomes smaller, the current that flows directly from the two electrodes 8.8 to the welding material 5 increases, and the welding material 4 The current flowing through the contact surface between the welding material 5 and the welding material 5 is reduced, and the contact portion between the welding material 4 and the welding material 5 is not melted, and the portion of the welding material 5 between the electrodes 8 and 8 becomes high temperature. The problem was that the parts became red hot and became brittle or discolored, making it impossible to weld reliably.

Therefore, this method has a problem in that particularly small parts cannot be welded.

Therefore, the purpose of the present invention is to solve the above-mentioned problems and provide a method that can reliably weld small parts etc. with an apparatus having a simple structure. In order to solve this problem, the present invention arranges two electrodes in parallel at a predetermined interval, sandwiches the welding material between the fixed workpiece and the two electrodes, applies pressure, and energizes the welding material. In this method, the contact area of the electrode that contacts the welding material is made different between the two Ti electrodes in a method of spot welding a material to be welded and a material to be welded.

[Function] According to the method of the present invention, the welding material to be welded is placed on a fixed workpiece, and the welding material is sandwiched between two electrodes having different contact areas and the workpiece. When the current is applied between the electrodes, the current flows from one Ti electrode through the welding material to the welded material, and then flows through the welding material to the other electrode, and the current flows only from one electrode to the welding material. The current flows through the electrode to the other electrode. The first flow flowing into the welded material generates Joule heat due to the contact resistance between the welded material and the welded material, which causes the temperature of the contact area between the welded material and the welded material to rise rapidly and locally. reaches a molten state. The latter current flowing only through the welding material generates Joule heat due to contact resistance between the welding material and the electrode. At this time, since the contact areas with the welding material are different between the two electrodes, heat is locally concentrated in the electrode with a smaller contact area, while heat is radiated in the electrode with a larger contact area. is carried out well, and if two electrodes are pressed with the same force, the electrode with a smaller contact area will be pressed against the welding material with a greater pressure. Therefore, the welding material is sufficiently melted and pressurized in the vicinity of the electrode where the contact area is small, and when the current is turned off, the welding material and the welded material are reliably pressed together at that part.

By making the contact area with the welding material different between the two electrodes, an imbalance occurs in the heat distribution near the two 7F1 poles, resulting in different melting and pressurizing conditions.
Even when the distance between the electrodes is reduced, the welding material between the electrodes will not become red hot and become brittle or discolored, resulting in incomplete welding, and high-quality welding can be achieved.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, two electrodes 1 and 2 with different cross-sectional areas are arranged side by side in a substantially V-shape above a table 3, and a metal plate, which is a material to be welded 4, is placed on the table 3. A state in which a metal wire, which is a welding material 5, is superimposed on it is shown. Two electrodes1.
Electrode 2 has a rectangular cross section, and electrode 1 has a shorter cross-sectional dimension than electrode 2 in the lateral direction, and has a smaller cross-sectional area. Further, these cross sections are formed parallel to the upper surface of the table 3. These electrodes 1 and 2 are configured to be movable relative to the welding material 5 from above the welding material 5, and apply pressure to the welding material 5 with a constant force, and pass the welding material through these electrodes 1 and 2. 5 and the material to be welded 4 can be energized.

FIG. 2 shows that after pressurizing the electrodes 1 and 2 against the welding material 5,
FIG. 3 is a diagram showing a current path when electricity is applied. 11 is a current used in conventional resistance welding, which flows from electrode 1 to welding material 5.
, passes through the welding material 4 and returns to the welding material 5 and flows to the electrode 2, or in the exact opposite direction. This current 11
Joule heat is generated due to the contact resistance between the welding material 5 and the welded material 4, and the contact portion is locally melted. 12 is a current that is effectively used in the resistance welding of the present invention, and it flows directly from the electrode 1 through the welding material 5 to the electrode 2, or it flows in the complete opposite direction, resulting in an ineffective shunt in conventional resistance welding. It is something.

If the resistance per unit length of the welding material 5 is 807 m, the part of the welding material 5 between the electrodes 1 and 2 will r
l-R-dt calories of heat is generated. Heat is also generated by the current I2 flowing through the contact resistance between the electric rod 1, which has a small cross section, and the welding material 5, and the contact resistance between the electrode 2, which has a large cross section, and the welding material 5. .

In the present invention, when the two electrodes 1.2 are pressed against the welding material 5, the area in contact with the surface of the welding material 5 is
Since this electrode 1 is smaller, the pressure applied to the welding material 5 is greater for this electrode 1. And these electrodes 1,
When current is applied to the welding material 5 and the material to be welded 4 through I2, as described above, the contact resistance between the electrode 1 and the welding material 5, the contact resistance between the electrode 2 and the welding material 5, and the electrode 1, Heat is generated due to the resistance of the welding material 5 between the electrodes 1 and 2, but since the electrode 1 has a small cross section, the pressure is large and the contact area is small, so the pressure and heat are locally concentrated, resulting in poor welding. While the welding material 5 is sufficiently melted, the welding material 5 is hardly melted in the electrode 2 having a large cross section. Therefore, as shown in FIG. 3, the vicinity of the contact surface of the welding material 5 in contact with the electrode 1 having a small cross-sectional area becomes depressed and molten. Furthermore, as the part of the welding material 5 near the electrode 1 having a small cross-sectional area is depressed, the resistance of that part increases, and as a result, the current I2 flowing directly from the electrode 1 through the welding material 5 to the electrode 2 increases. decreases, the amount of current 11 flowing from the electrode 1 through the welding material 5 to the welded material 4 increases, and Joule heat is generated. Then, the contact portion between the welding material 5 and the welded material, which is pressed by the electrode with a small cross-sectional area, is heated and melted. When the current is turned off in this state, both metals 4 and 5 are brought into pressure contact at the contact portion between the welding material 5 and the welded material 4, which are being pressed by the electrode 1.

According to this method, the above series of actions are performed in a very short time, so the molten metal does not combine with oxygen in the air to form an oxide film, and reliable diffusion welding can be performed on a clean surface. It will be done.

Next, the dimensions of the electrode 1゜2 for a good welding condition,
The relationship between the distance between the electrodes 1 and 2 and the dimensions of the welding material 5 will be explained using FIG. 4.

If Dl is the cross-sectional area of the welding material 5, D2 is the cross-sectional area of the electrode 1 having a small cross section, and D3 is the cross-sectional area of the electrode 2 having a large cross section, then if DI < D2 < D3, then A1 is the welding material 5, A2 is the lateral width of the cross section of electrode 1 with a small cross section, A3 is the distance between electrodes 1.2, A4 is the lateral width of the cross section of electrode 2 with a large cross section, then AI Good quality welding is achieved when <A2 <A3 <A4.

In addition, in this embodiment, an IJ having a rectangular cross section is used.
ffl is used, but electrodes having a circular or elliptical cross section may also be used.

[Effects of the Invention] According to the resistance welding method of the present invention, when the distance between two electrodes is small, reliable and high-quality welding can be performed using the electrode with a smaller contact area.

Therefore, by using the welding method of the present invention, ultra-small parts can be welded easily and reliably by simply changing the contact area of the electrodes.

[Brief explanation of drawings]

FIG. 1 is a front view showing the method of the present invention, FIG. 2 is an explanatory diagram explaining the flow of current in the method, FIG. 3 is a front view showing the molten state of metal when the method is used, and FIG. FIG. 4 is an explanatory diagram for explaining the optimum conditions of the method, and FIG. 5 is a front view showing the conventional resistance welding method. Explanation of symbols 1... Electric Fi 2... Electrode 3... Stand
4... Welding material 5... Material to be welded

Claims (1)

[Claims] 1. Two electrodes are arranged in parallel at a predetermined interval, and the welding material is sandwiched between the fixed workpiece and the two electrodes, and the welding material and the welding material are connected by applying pressure and electricity. In the spot welding method, the contact area of the electrode that contacts the welding material is 2
A resistance welding method characterized in that two electrodes are different.