JPH09239556A - Electric resistance welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric resistance welding method capable of performing even the welding between materials difficult to weld in which presence of an oxide film can not be neglected with the prescribed power, and obtaining the welding strength with excellent reliability by performing the correct feedback control of the power to be fed to the weld zone. SOLUTION: In an electric resistance welding method in which a first metal 1 and a second metal 2 are brought into contact with each other, the first and second metals are energized while they are pressed by two welding electrodes 3, 4 from each side, and the first and second metals are welded, the voltage between the first and second metals is measured by bringing separate voltage sensing electrodes 9, 10 from the welding electrodes into contact with at least one of the first and second metals, and the welding is performed by feeding the prescribed power based on the measured voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric resistance welding method in which two metal materials are brought into contact with each other and are energized to be welded by Joule heat due to contact resistance. For more information,
The present invention relates to an electric resistance welding method in which a voltage between two metal materials is sensed and a constant electric power is supplied to perform welding with constant strength.

[0002]

2. Description of the Related Art In electric resistance welding, two metal materials to be welded are brought into contact with each other, and an electric current is passed through them to melt the metal at the contact portion by Joule heat due to the electric resistance of the contact portion and the flowing electric current. Glue two metal materials. In order to keep the welding strength of the adhesive portion constant, a constant power feedback welding method is also adopted in which the voltage and current between the electrodes are measured and the power source is adjusted so as to obtain a constant Joule heat. A principle diagram of this electric resistance welding method is shown in FIG.

In FIG. 6, reference numerals 1 and 2 are first and second metal materials to be welded, and 3 and 4 are first and second metal materials for flowing an electric current between the two metal materials 1 and 2, respectively. Welding electrodes 5 and 6 are wirings having low resistance for connecting the electrodes 3 and 4 to the power source, respectively. Further, 7 and 8 are sense lines for sensing the voltage between the electrodes 3 and 4.

With this structure, the two metal materials 1 and 2 are pressed into contact with each other by the electrodes 3 and 4 to pass a current. Here, assuming that the contact resistance of the welded portion A is R ₃ , the current flowing between the electrodes 5 and 6 is I, and the time of flowing the current is t seconds, J = 0.24I ² between the two metal materials 1 and ^2. Joule heat of R ₃ t (joule) is generated, and a part of the welded portion A is melted and adhered. This welded part A
The contact resistance R ₃ depends on the pressure contact force between the electrodes 3 and 4, and in the feedback control constant power welding method, the voltage between the electrodes 3 and 4 is sensed by the sense lines 7 and 8 and is constant at the welded portion A. The electric power applied between the electrodes 3 and 4 is adjusted so that the electric power is consumed.

In the conventional constant power welding method, both electrodes 3,
Measure the sense voltage by touching 4 to the sense lines 7 and 8.
However, there is a contact resistance between the first electrode 3 and the first metal material 1.
Anti-R ₁Between the second electrode 4 and the second metal material 2
Contact resistance R_FiveIs present, and it is also present on metal materials 1 and 2.
Each resistance R_TwoAnd R_FourExists. Electrodes 3 and 4 are
It is generally made of copper and has good thermal conductivity as well as electrical conductivity.
In addition, since the heat capacity is large, the electrodes 3, 4 and the metal material 1,
Even if Joule heat is generated at each contact part with 2
There is no contact. However, due to the pressure contact force of the electrodes 3 and 4,
That resistance value R₁, R_FiveDifferent, welding electrodes 3, 4
When the sense voltage is measured at the part, the electrodes 3, 4 and the metal material 1,
Applied to weld A including voltage drop due to contact resistance with 2
It is not possible to accurately grasp the amount of power supplied.

[0006]

Generally, the contact resistance is greatly affected by the pressure contact force, the dirt of the metal material, the surface condition of the oxide film, and the like, and the variation becomes large. Also,
When a large current is applied as in the case of welding, a large voltage drop occurs even with a small resistance, and the voltage drop also changes greatly due to variations in contact resistance. Therefore, in the conventional constant-power electric resistance welding method of measuring the sense voltage at the electrode portion as described above, accurate feedback control may not be performed, and it may not be possible to supply power accurately to the welded portion. is there. Therefore, it is difficult to stably maintain a strong welding strength in electric resistance welding between metal materials in which welding strength is subtly changed by supply power such as welding of tantalum and copper or welding of filament.

The present invention solves such a problem, accurately feedback-controls the electric power supplied to the welded portion, and welds with a constant electric power even in the welding between difficult-to-weld materials in which the existence of an oxide film cannot be ignored. It is an object of the present invention to provide an electric resistance welding method capable of obtaining highly reliable welding strength.

[0008]

In the electric resistance welding method according to the present invention, a first metal material and a second metal material are brought into contact with each other, and the first and second metal materials are welded to each other from both sides. An electric resistance welding method for welding the first and second metal materials while energizing while pressing them with a welding electrode, wherein a voltage sensing electrode different from the welding electrode is used for the first and second metals. By contacting at least one of the materials, the voltage between the first and second metal materials is measured, and welding is performed while supplying constant power based on the measured voltage.

The first metal material is a small material that is crushed near the welding electrode at the welded portion, and the voltage for contacting the welding electrode and the second metal material with which the first metal material is pressed It is possible to supply the above-mentioned constant power based on the measured voltage between the electrode for sensing, and in the case of a small metal material, the power of the contact portion with the electrode is also used to melt and bond the entire metal material, It is preferable because the voltage at the contact portion with can be controlled.

The voltage between the two welding electrodes is measured, and if the measured voltage is higher than the measured voltage using the voltage sensing electrode by a predetermined value or more, the constant voltage is supplied to the measured voltage by the welding electrode. In order to prevent excessive electric power from being applied to the first and second metal materials, it is often necessary for the metal materials to be welded even if the voltage measured by the voltage sensing electrode is abnormal. It is preferable because electric power is not applied too much to cause defects.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an electric resistance welding method of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory view for explaining the electric resistance welding method of the present invention, in which (a) is a case of welding two large metal materials such as a plate or a bar, and (b)
FIG. 4 is an explanatory diagram in the case where one metal material is a thin material such as a wire and the other metal material is welded to a large metal material such as a plate material or a bar material.

In FIG. 1 (a), 1 to 8 show the same parts as in FIG. 6, 9 and 10 directly contact the first metal material 1 and the second metal material 2, respectively, and both metal materials 1, It is a voltage sensing electrode for sensing the voltage between the two. The first and second welding electrodes 3 and 4 are in pressure contact with the metal materials 1 and 2 at a pressure F by a spring or the like (not shown). The voltage sensing electrodes 9 and 10 are also pressed against the metal materials 1 and 2 with a force F ₀ smaller than the pressure contact force F of the welding electrode.
This force F ₀ is applied to the voltage sensing electrodes 9 and 10 and the metal materials 1 and 2.
Since it only needs to be pressed against each other, it requires very little force.

In the structure shown in FIG. 1 (a), the contact resistance R ₁ between the first electrode 3 and the first metal material 1 makes contact between the first and second metal materials 1 and 2. A resistance R ₃ exists and a contact resistance R ₅ exists between the second electrode 4 and the second metal material 2. A large current is passed between the welding electrodes 3 and 4 to melt the contact portion of the metal material, so that a voltage drop occurs at each contact portion. However, in the present invention,
Separately from the welding electrodes 3 and 4, voltage sensing electrodes 9 and 10
Are contacted with the metal materials 1 and 2, respectively, so that the contact resistances R ₁ and R ₅ between the welding electrodes 3 and 4 and the metal materials 1 and 2 are excluded, and only the voltage between the metal materials 1 and 2 Can be measured accurately. That is, the voltage sensing electrodes 9, 1
0 and the metal materials 1 and 2 have contact resistances R ₆ and R, respectively.
₇ exists, but since the voltage sensing electrodes 9 and 10 are connected to a high input impedance and almost no current flows, no voltage drop occurs, and the metal material 1 and the metal material 1, The voltage between the two can be measured accurately. As a result, the voltage measured by the voltage sensing electrodes 9 and 10 indicates the voltage V ₃ generated by the contact resistance R ₃ between the metal materials 1 and 2, and by feeding back the voltage V ₃ to the welding portion A, Power can be supplied.

FIG. 1 (b) shows the voltage when the first metal material is made of a small material such as a thin wire and the second metal material 2 is made of a large material such as the same plate or bar as in (a). It is a figure explaining how to sense. In the case of (b), the sensing electrode 10 contacts only the other second metal material 2 and the electrode for measuring the potential of the first metal material 1 also serves as the first welding electrode 3. Is. That is,
When one of the first metal materials 1 to be welded is a thin material such as a wire, it is entirely crushed and welded from the upper surface during welding. Therefore, the first welding electrode 3 and the first welding electrode 3
Joule heat generation due to contact resistance R ₁ between the metal material 1 is also used to heat the weld. Therefore, it is preferable to set the sense voltage including the contact resistance R ₁ between the first welding electrode 3 and the first metal material 1 because the electric power applied for welding can be made constant. That is, in the example shown in (b), the voltage V ₃ between both metal materials 1 and 2
Therefore, the sum V ₁ + V ₃ of the voltage V ₁ between the welding electrode 3 and the first metal material 1 is measured.

1 (a) and 1 (b), the resistances of both metal materials 1 and 2 are not shown, but they exist depending on the material. However, the contact resistance is very small compared to the contact resistance of the contact portion, and since it is constant, it does not affect the variation in welding, and it is sufficient to subtract that portion, so it is omitted here.

In the example shown in FIG. 1, the welding electrodes 3, 4 are used.
2A, an example of the fixed electrode 31 as shown in FIG. 2A is shown. However, the same applies when the rotating electrode 32 having the rotating body 32a at the tip as shown in FIG. 2B is used. Is. Alternatively, the two welding electrodes may be used in combination with the fixed electrode 31 and the rotating electrode 32. In FIG. 2, reference numeral 15 is a spring for pressing the welding electrode with a constant force F, and reference numeral 5 is a thick and low-resistance wiring connected to a power source (not shown) for flowing a current.

FIG. 3 is an explanatory view of one mode of the welding method of the present invention, and is a view showing a state in which the power source section 20 is connected to the welding head section shown in FIG. The welding head portion is the same as that shown in FIG. 1A, and the first and second welding electrodes 3, 4 are used.
Separately from the above, voltage sensing electrodes 9 and 10 are provided so as to contact the first and second metal materials 1 and 2, respectively. The same parts as those in FIG. 1A are designated by the same reference numerals and the description thereof will be omitted. In addition, 15 is pressure F, F which presses each electrode.
A spring for giving ₀ .

The power supply section 20 is a transformer 21 and a rectifier 22 for dropping a commercial AC power supply to a low voltage and a smoothing capacitor 2.
A DC power supply is constituted by 3, and a desired constant power can be supplied through the transistor 24. A current sensing resistor 25 for measuring current is connected in series to the wiring 5 that supplies current to the welding electrodes 3 and 4.
The measured current and the voltage sensed by the voltage sensing electrodes 9 and 10 are supplied to the multiplier 26. The power applied between the metal materials 1 and 2 is obtained by the multiplier 26, and is input to the comparator 27 together with the preset power P ₀ .
The result of the comparison by the comparator 27 is the transistor 21 described above.
The electric power that is input to the base of and is applied to the welding electrodes 3 and 4 is adjusted. As a result, a constant power is always supplied to the welded portion A without being affected by the reactive power generated between the welding electrodes 3 and 4 and the metal materials 1 and 2, and stable welding can be obtained.

In the example shown in FIG. 3, not only the voltage V _S obtained from the voltage sensing electrodes 9 and 10 but also the voltage V _Y obtained from the welding electrodes 3 and 4 are supplied to the multiplier 26. Wirings 16 and 17 are connected between the welding electrodes 3 and 4 and the multiplier 26. In the multiplier 26, the voltage V _S obtained from the voltage sensing electrodes 9 and 10 and the voltage V _Y obtained from the welding electrodes 3 and 4 are first compared, and when the difference between them is within a proper predetermined range, The voltage V _S is used, and when this difference is equal to or greater than a predetermined value, the voltage V _Y is used to obtain the product of the current obtained from the current sensing resistor 25. The voltage obtained from the welding electrodes 3 and 4 is for a so-called fail-safe mechanism. That is, if the voltage sensing electrodes 9 and 10 are separated from the metal materials 1 and 2, or if an accident such as a contact failure occurs, excessive power is prevented from being applied between the welding electrodes 3 and 4. Is. For example, by providing such a fail-safe mechanism, even if a contact failure occurs in the voltage sensing electrodes 9 and 10, welding failure does not occur.

FIG. 4 shows that one first metal material 1 has a diameter d of 0.2, for example, as in the welding of a tantalum wire and a copper frame in the production of a tantalum capacitor.
a second material made of a thin material such as a wire having a thickness of about mm, and a large material having a thickness t of about 1 mm.
FIG. 6 is an explanatory view of welding according to the present invention in the case of being much smaller than the metal material 2 of FIG.

The tantalum capacitor is manufactured as follows. First, a capacitor pellet, in which a tantalum wire to be one of the electrodes is inserted, is formed in a compact of about 1 mm square made of, for example, tantalum powder. Next, the wire portions of a large number of pellets are sequentially welded to a stainless plate or the like, and a large number of pellets are collectively sintered and subjected to chemical conversion treatment for forming an oxide film, re-chemical conversion treatment for forming a semiconductor layer, and the like. Then, each capacitor pellet is cut from a stainless plate and mounted on a frame made of copper or the like.
In this mount, the tantalum wire 42 of the capacitor pellet 40 and the first lead 44 of the frame are connected by electric resistance welding as shown in the side view of one capacitor pellet portion in FIG. This is performed by connecting the cathode portion 41 of the No. 1 and the second lead 45 with the solder fuse 43. The solder fuse 43 is connected by first forming a ball at one end of a solder wire for the solder fuse 43, bonding it to the cathode portion 41 of the capacitor pellet 40, then lifting the solder wire up to melt it and form a ball. The wire bonding method for connecting to the second lead 45 is used. Next, it is manufactured by molding with a resin, aging, etc., and separating the capacitor from the frame.

In the manufacturing process of this capacitor, the tantalum wire of the capacitor pellet must be welded to the stainless plate or the copper frame. Particularly in the welding of tantalum wire and copper frame, since the capacitor pellets have undergone an oxidation treatment step, the welding conditions are difficult due to the presence of an oxide film. Moreover, as mentioned above, the solder fuse is connected to the cathode part side by the wire bonding method, but if the cathode part of the capacitor pellet is slanted or rotating, it is very difficult to bond the solder fuse and reliability is high. Is reduced. Therefore, it must be welded at a correct position with high mechanical strength. However, by using the welding method of the present invention, as will be described later, it is possible to accurately apply constant power corresponding to Joule heat of the entire wire that contributes to welding, so that the welding conditions can be controlled accurately. The welding can be performed with high reliability.

As shown in FIG. 4, when one first metal material 1 is much smaller in volume than the other second metal material 2, the smaller metal material 1 is crushed during welding. Overall welded. Therefore, Joule heat generated by the contact resistance R ₁ generated between the first welding electrode 3 and the first metal material 1 also contributes to welding. Therefore, it is desirable that the voltage sensing electrode that senses to apply a constant power does not contact the first metal material 1 but the first welding electrode 3. Therefore, the voltage sense line 7 is directly connected to the first welding electrode 3. That is, no voltage sensing electrode is provided on the first metal material 1 side.

On the other hand, the second metal material 2 side is the second metal material.
2 and the contact resistance R between the second welding electrode 4_FiveDue to
Excluded because the heat of hurle does not contribute to welding and becomes reactive power.
There is a need to. Therefore, the voltage sensing electrode 10 is
For the first welding on the first metal material 1 side by contacting with the metal material 2
The voltage between the electrode 3 and the second metal material 2 is the sense voltage V _S
Is supplied to a multiplier (not shown). in this way,
The metal material to be welded is very small,
If welded or crushed as a whole, the metal
It is necessary to obtain the sense voltage from the welding electrode, not the material.
You.

Also in the example shown in FIG. 4, in order to obtain the fail-safe voltage V _Y , wirings 16 and 17 for measuring the voltage between both welding electrodes 3 and 4 are connected to both electrodes 3 and 4, respectively. There is. In addition, in FIG.
The same reference numerals as those used in FIG. Further, in the example shown in FIG. 4, the welding electrodes 3, 4 are
Although a rotating electrode (which rotates in both directions as shown by an arrow in the figure) is used as, the same applies to the fixed electrode shown in FIG.

[0027]

According to the present invention, in the constant power electric resistance welding method of applying a constant electric power to the welding portion while sensing the voltage of the welding portion, only the voltage of the portion contributing to welding is sensed and the voltage is detected. Since a constant power is applied based on this, a constant power is always applied to the weld. As a result, constant electric power can always be applied to the welded part even with electric resistance welding that requires precise power control, such as welding of tantalum wire and copper plate and welding of filament, and it is extremely high quality. A reliable weld can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an electric resistance welding method of the present invention.

FIG. 2 is an explanatory diagram of types of tips of welding electrodes.

FIG. 3 is an explanatory diagram of an embodiment of an electric resistance welding method of the present invention.

FIG. 4 is an explanatory view of another embodiment of the electric resistance welding method of the present invention.

FIG. 5 is a side view illustrating a state where the capacitor pellets are mounted on the frame.

FIG. 6 is an explanatory diagram of a conventional electric welding method.

[Explanation of symbols]

 1 1st metal material 2 2nd metal material 3 1st welding electrode 4 2nd welding electrode 9, 10 Voltage sensing electrode

Claims (3)

[Claims] 1. A first metal material and a second metal material are brought into contact with each other, and the first and second metal materials are energized while pressure-welding from both sides with two welding electrodes, An electric resistance welding method for welding a second metal material, wherein the voltage sensing electrode different from the welding electrode is brought into contact with at least one of the first and second metal materials to provide the first and second metal materials. An electric resistance welding method in which the voltage between the second metal materials is measured and welding is performed while supplying constant power based on the measured voltage. 2. The first metal material is a small material that is crushed near the welding electrode at a welded portion, and the first metal material is brought into contact with the welding electrode and the second metal material that are in pressure contact with each other. The electric resistance welding method according to claim 1, wherein the constant power is supplied based on a measured voltage between the voltage sensing electrode. 3. The voltage between the two welding electrodes is measured, and when the measured voltage is larger than the measured voltage using the voltage sensing electrode by a predetermined value or more, the measured voltage by the welding electrode is set to the constant power. 3. The electric resistance welding method according to claim 1, wherein the electric resistance welding method is used as a voltage for supplying the electric power to prevent excessive power from being applied to the first and second metal materials.