JPH0452081A - Projection welding method and its electrode - Google Patents

Abstract

PURPOSE:To obviate positional deviation at the time of welding a metallic plate to a metallic wire which are elements to be welded and to improve positioning accuracy by forming crossing positioning grooves to satisfy specified conditions on the welding side end face of one electrode of welding electrodes. CONSTITUTION:The positioning grooves 23 to orthogonally cross groove parts A and B are formed on one end face of the upper electrode 10 and the groove part A and the groove part B position a projection 2 and a Ni wire 3, respectively. The groove part A and the groove part B have a width W1 capable of fitting the projection 2 and a width W2 capable of fitting the Ni wire 3, respectively and the relation among a depth d1 of the groove part A and a depth d2 of the groove part B of the positioning grooves 23, a height (h) of the projection 2 and a diameter phil of the Ni wire 3 is set so as to satisfy the conditions of d1<d2, phil<d2<phil+(h). After setting as mentioned above is carried out, a welding current is applied between the projection 2 and the Ni wire 3 by the electrodes 10 and 11 and the projection 2 and the Ni wire 3 are subjected to resistance welding together.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a projection welding method for joining a metal plate such as a plate-shaped terminal and a metal wire such as a Ni wire, and an electrode used therefor. Regarding.

[Prior art] Conventional electronic devices include 1, for example, Japanese Patent Application Laid-Open No. 57-131031.
As disclosed in the publication, an electronic circuit is housed in a synthetic resin molded case, and terminals (metallic There is one in which the electronic circuit is electrically connected to the electronic circuit via a metal wire such as a Ni wire.

When joining such metal plates and metal wires, electric resistance welding is used to improve the reliability of the connection, but recently, in order to concentrate the welding current and pressure, Projections are formed on the surface of the metal plate on the welding side, and a metal wire is brought into cross-contact with the projections to perform projection welding.

In addition, the conventional electric resistance welding method includes JP-A-63-201
As disclosed in Publication No. 86, when wires are arranged vertically and horizontally in a lattice pattern and resistance welding is performed by pressurizing the intersections of these wires, both welding electrodes must be aligned in advance to face each other. One in which intersecting positioning grooves are formed on each surface has been proposed.

[Problem to be solved by the invention]

By the way, when projection welding a metal plate and a metal wire as in the former of the above conventional techniques, the metal wire may be misaligned with respect to the protrusion on the metal plate side, or the metal wire may not be directed in the desired direction. May be welded.

Further, the metal wire may tilt in the vertical direction using the protrusion as a fulcrum. When this slope becomes larger than a certain level,
If the metal wire comes into contact with the surface of the terminal as well as the protrusion on the metal plate side where it will be joined, and projection welding is performed in this state,
The welding current shunts, causing problems in welding.

In the latter case, grooves for positioning wire rods into which intersecting wire rods (workpieces to be welded) are fitted are formed on the end faces of both welding electrodes. However, although this prior art is good for positioning wires together, no structural consideration is given to positioning when welding a metal plate and a metal wire.

The present invention has been made in view of the above points, and its purpose is to satisfy at least one of positioning accuracy and prevention of welding current shunt when projection welding a metal plate and a metal wire. The aim is to ensure welding strength and improve productivity.

[Means to solve the problem]

The present invention proposes the following basic problem solving means.

One of them (referred to as the first problem solving means) is that when welding a metal plate and a metal wire, a protrusion is formed on the surface of the metal plate, and the protrusion and the metal wire are brought into cross contact. In the welding method in which the metal plate/metal wire is held under pressure by a pair of electrodes and electric current is applied to perform electric resistance welding, a groove is formed on the welding side end face of one of the electrodes facing the protrusion and the metal wire. A positioning groove is formed in which A and B intersect, and groove part A is @W that can fit into the protrusion.
1. The groove B has a width W2 that can fit the metal wire, and the relationship among the depth d2 of the groove B of the positioning groove, the height h of the protrusion, and the diameter Φl of the metal wire is ΦR(d2 <
Electric resistance welding is performed through the welding electrode while the protrusion and metal wire are fitted into the grooves A and H provided in one of the electrodes by setting the condition of Φl+h to be satisfied.

Another method (second problem solving means) is that when welding a metal plate and a metal wire, a protrusion is formed on the surface of the metal plate, and the protrusion and the metal wire are brought into cross contact. In the welding method in which the metal plate/metal wire is held under pressure by a pair of welding electrodes and electric current is applied to perform electric resistance welding, an insulating layer covering the surface of the metal plate is formed in advance on the surface of the metal plate, It is proposed that this insulating layer prevents the welding current from being shunted when the metal wire during welding comes into contact with a part other than the welded part of the metal plate, thereby performing projection welding.

[Effect]

Effects of the first problem solving means... In this problem solving means,
Groove A of the positioning groove formed on the welding side end face of one of the welding electrodes when performing projection welding.
and groove B are widths W1 and W2 corresponding to protrusions and metal wires.
By making the depth d2 of the groove B on the side into which the metal wire is fitted satisfy the relationship ΦR<d2 with respect to the diameter Φl of the metal wire, this The corresponding grooves A and B can be fitted from one side without any problem. In other words, only the positioning groove (intersecting groove) of one electrode restricts the positions of both the protrusion and the metal wire, allowing proper positioning.

By the way, if the above relationship is not satisfied, for example, if the depth of each groove intersecting the electrode is smaller than the diameter ΦΩ of the wire as in the above-mentioned Japanese Patent Application Laid-open No. 63-20186, only the intersecting grooves of one electrode , it is not possible to fit (align) both the three-dimensionally intersecting protrusion and the metal wire.

Furthermore, in this problem solving means, the depth d2 of the positioning groove part B corresponding to the metal wire among the intersecting grooves is made smaller than the sum of the height h of the protrusion and the diameter Φl of the metal wire (d2<Φu+
h) This grooved electrode does not come into contact with the surface of the metal plate other than the protrusion. Further, due to the above-mentioned dimensional relationship, the upper part of the inner wall of the groove B comes into contact with the metal wire, thereby regulating the inclination of the metal wire. Therefore.

To prevent a metal wire from coming into contact with the surface of a metal plate (a surface other than a projection) during welding, and to prevent a situation where welding current is shunted during projection welding.

Effect of the second problem-solving means...According to the present problem-solving means, since an insulating layer is formed on the welding side surface of the metal plate,
Even if the metal wire tilts and contacts the metal plate during projection welding, the presence of the insulating layer prevents the welding current from splitting.

Even when such an insulating layer is formed on the surface of a protrusion that is a welded part, projection welding can be performed without any problem.

The reason for this is (a) the welding current is a large current (for example, about 100%
(approximately 0A) and (b) Moreover, since projection welding is performed by applying pressure, the contact pressure between the protrusion and the metal wire is strong, and this contact resistance causes damage to the surface of the metal plate other than the part to be welded and the insulation layer of the metal wire. Since it is sufficiently smaller than the contact resistance via
This is because dielectric breakdown occurs between the protrusion and the metal wire, allowing a concentrated welding current to flow.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

Fig. 1 is an explanatory diagram of projection welding according to the first embodiment of the present invention, Fig. 2 is an explanatory diagram of a part thereof, and Fig. 3 is an explanatory diagram showing the structure of one of the welding electrodes. Prior to these descriptions, a specific example of an electronic device to be subjected to projection welding will be described with reference to FIG. 5, and an apparatus for performing projection welding will be described with reference to FIG. 6.

FIG. 5 is a plan view showing a power switching module used for automobile ignition control as an electronic device, in which an electronic circuit 4 including a power transistor is built into a synthetic resin molded case 5.

Further, a plate-shaped metal terminal (for example, a copper plate) 1 is disposed inside the case 5 and supported by being partially buried in the case 5, and the terminal 1 and the electronic circuit 4 are electrically connected via the Ni wire 3. Connected.

The terminal 1 and the Ni wire 3 are joined by projection welding, with a protrusion 2 orthogonal to the Ni wire 3 provided on the terminal 1 side by press working.

As shown in FIG. 6, the projection welding device includes a welding machine main body 6, a welding head 7, and a pair of upper and lower holders 8.
, 9 etc.

The upper electrode 10 and the lower electrode 11 are supported by respective holders 8 and 9 and are arranged to face each other.

Among these, the upper electrode 10 is movable in the vertical direction via a lifting mechanism built into the holder 8 and the welding machine main body 6. Reference numeral 12 is a mechanism for adjusting the pressing force when the electrodes 10 and 11 pressurize and clamp the member to be welded.

13 is a welding cable, 14 is a jumper cable, 15 is a welding transformer, and 16 is a control unit that performs operations necessary for welding, current control, etc.

In this embodiment, projection welding is performed by pressing and clamping the plate terminal 1 of the electronic device and the Ni wire 3 using the electrodes 10.11, and the welding is performed as follows.

3(a) and (b) show the welding side of the upper electrode 10 (
The side surface of one end surface (pressure clamping side) is shown at a different angle, and FIG. 3(c) shows a bottom view thereof.

As is clear from these figures, a positioning groove 23 in which grooves A and B intersect at right angles is formed on one end surface of the upper electrode 1°, groove A is used for positioning the protrusion 2, and groove B is used for positioning the Ni wire 3. Perform positioning against.

In this embodiment, the groove A has a width W1 that can fit into the projection 2, the groove B has a width W2 that can fit the Ni wire 3, and the depth dl of the groove A and the depth of the groove B of the positioning groove 23. d2. The relationship between the height h of the protrusion 2 and the diameter Φl of the Ni wire 3 is expressed as d
The setting is made to satisfy the following conditions: 1<d2, Φfind2×Φn+h.

dl and d2 may be d1≧d2.

Next, projection welding in this embodiment will be explained with reference to FIGS. 1 and 2.

When welding is to be performed, the terminals 1 are assembled in advance into a molded case 5 of a power switching device, as shown in FIG. 1, and the upper and lower sides of the case 5 are left open.

The case 5 is set at the welding work position, the protrusion 2 of the terminal 1, which is the element to be welded, and the Ni wire 3 are crossed, and in this state, the electrodes 10° 11 are introduced from the upper and lower openings of the case 5.

The protrusion 2 is placed in the groove A of the electrode 10, and the Ni is placed in the groove B of the electrode 10.
The wire 3 is fitted, and in this state, the upper electrode 10 is lowered, and the protrusion 2 and the Ni wire 3 are held under pressure by the electrodes 10.11. In this pressurized clamping state, the depth d2 of the groove B is as described above.

Since it is smaller than the sum of the diameter Φρ of the Ni wire 3 and the height h of the terminal 2, the groove B is supported by the upper surface of the Ni wire 3 and is in a floating state, so that the electrode 10 does not come into contact with the surface of the terminal 2. There isn't.

Furthermore, since the Ni wire 3 is regulated by the inner wall of the groove B, vertical inclination is suppressed. By suppressing this inclination, the Ni wire 3 is kept at an angle (10
(within 30 degrees).

After the above settings, a welding current is passed between the protrusion 2 and the Ni wire 3 using the electrodes 10 and 11, and the protrusion 2 and the Ni wire 3 are resistance welded.6 Figure 4 shows the terminal 1.
(Protrusion 2) and the Ni wire 3 are welded together. After this welding, the electronic circuit 4 is built into the mold case 5 as shown in FIG. The pad 22 is connected.

According to this embodiment, the relative positional relationship between the terminal 1 (protrusion 2) and the Ni wire 3 can be determined with high precision by the grooves A and B formed in the upper electrode 1o. Here, groove part A,
By arbitrarily setting the crossing angle of B, the crossing angle of the Ni wire 3 and the terminal 1 can be set arbitrarily.

In addition, since the Ni wire 3 is prevented from coming into contact with any part of the terminal 1 other than the protrusion 2 due to the inclination regulation, the welding current is not divided, and the welding strength is increased by concentrating the welding current. .

As described above, it is possible to improve the product quality of this type of electronic device, and also to increase the yield and productivity. Note that there is no problem even if the intersecting groove 23 consisting of the grooves A and B is provided on the lower electrode 11 side in addition to the upper electrode 10.

Next, a second embodiment of the present invention will be described with reference to FIGS. 7 to 9.

FIG. 7 is an explanatory diagram showing the welding work state of the second embodiment;
The figure is a top view, and FIG. 9 is an explanatory view showing the state after welding. In these figures, the same reference numerals as in the previously described embodiments indicate the same or common elements.

First, an example of a product (electronic device) to be welded will be described with reference to FIG.

A welding pad 22 is placed inside the synthetic resin molded case 5.
A thick film circuit board 21 with a thick film circuit board 21 is incorporated, and the plate terminal 1 disposed in the mold case 5 and the welding pad 22 are electrically connected via the Ni wire 3.

When joining the protrusion 22 of the plate terminal 1 and the Ni wire 3, the entire surface of the plate terminal 1 as shown in FIG. 7 (the surface 1a of the terminal 1 and the surface of the protrusion 2 as shown in FIG. 2a) is forcibly oxidized to form an oxide insulating layer of several micrometers on the terminal surface.

In this embodiment, when the protrusion 2 and the Ni wire 3 are crossed and projection welding is performed using the electrode 10.11, the N1 wire 3 is tilted and the protrusion 2 (the welding Even if a part P other than the welded part comes into contact with the terminal 1, the presence of the oxide insulating layer 20 on the surface of the terminal 1 can prevent the welding current from being shunted.

Further, in this case, even if the oxide insulating layer 20 is also formed on the surface 2a of the protrusion 2, which is the welding part, the contact pressure between the protrusion 2 and the Ni wire 3 is extremely large compared to the contact part P (the contact resistance is small). In addition, since the large current during welding is approximately 1000 A, dielectric breakdown occurs in the welded portion between the protrusion 2 and the Ni wire 3, and a welding current flows, allowing projection welding to be performed without any trouble.

According to this embodiment, branching of the welding current can be prevented and proper welding can be performed using concentrated welding current, thereby improving product productivity.

In addition, although each of the above-mentioned embodiments illustrated the connection between the plate-shaped terminal 1 and the Ni wire 3, the present invention is not limited to this, and can also be applied to cases where various metal plates and metal wires are connected. It is possible. Further, instead of the oxidized insulating layer 20 that forcibly oxidizes the surface of the terminal 1 as in the second embodiment, an insulating film may be formed using an appropriate method such as sputtering or coating.

〔Effect of the invention〕

As described above, according to the present invention, in the first problem solving means, Φα and d2<Φ
By forming intersecting positioning grooves that satisfy the condition n+h, it is possible to eliminate positional deviation during welding between the metal plate and metal wire, which are elements to be welded, and improve positioning accuracy. It also prevents the metal wire from tilting and prevents the welding current from splitting, increasing welding strength. As a result, product yield (productivity) can be increased.

In the second problem-solving means, by forming an insulating layer on the surface of the metal plate that is the element to be welded, even if the metal wire comes into contact with the metal plate during projection welding, the welding current is prevented from being shunted,
Similarly to the above, welding strength and productivity can be improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the state of projection welding according to the first embodiment of the present invention, FIG. 2 is an explanatory diagram showing the main parts thereof, and FIG. An explanatory diagram showing the structure of the electrode, FIG. 4 is a plan view showing the terminal and Ni wire after welding, FIG. 5 is a plan view showing the assembled state of the electronic device, and FIG. 6 is projection welding. A schematic perspective view of the apparatus, FIG. 7 is a sectional view showing projection welding according to the second embodiment of the present invention, FIG. 8 is a plan view of FIG. 7, and FIG. 9 is a projection welding according to the second embodiment. FIG. 3 is a partially cross-sectional side view showing the state of the electronic device after completion. 1... Metal plate (plate-shaped terminal), 2... Protrusion, 3...
Metal wire (Ni wire), 4... Electronic circuit, 5... Mold case, 10.11... Welding electrode, 20...
Insulating layer, 23... positioning groove (cross groove), A, B...
・Groove. Agent Patent Attorney Akio Takahashi・-:・- (1 other person)''-1 Diagram wire) 2 Rudke 10.11...Welding electrode. Diagram Diagram Diagram Diagram Groove) Diagram (a) (b ) Figure

Claims (1)

[Claims] 1. When welding a metal plate and a metal wire, a protrusion is formed on the surface of the metal plate, the protrusion and the metal wire are brought into cross contact, and the metal plate/metal wire is welded. In a welding method in which electric resistance welding is performed by applying a current while being held under pressure by a pair of electrodes, grooves A and B are made to intersect on the welding side end surface of one of the electrodes that faces the protrusion and the metal wire. A positioning groove is formed, of which groove A has a width W that can fit into the protrusion.
1. The groove B has a width W2 that can fit the metal wire, and the relationship among the depth d2 of the groove B of the positioning groove, the height h of the protrusion, and the diameter Φl of the metal wire is Φl<d2. <
The method is characterized in that electric resistance welding is performed through the welding electrode while the protrusion and the metal wire are fitted into the grooves A and B provided in one of the electrodes, with the condition set to satisfy the condition Φl+h. Projection welding method. 2. A projection welding electrode that is a pair of electrodes used for resistance welding a metal wire and a metal plate, and performs electric resistance welding by bringing protrusions formed on the surface of the metal plate into cross contact with the metal wire, A positioning groove in which grooves A and B intersect is formed in the welding side end surface of at least one of the electrodes, of which groove A has a width W1 that can fit into the protrusion, and groove B has a width that can fit into the metal wire. and the relationship among the depth d2 of the groove B of the positioning groove, the height h of the protrusion, and the diameter Φl of the metal wire is Φl<d2.
An electrode for projection welding, characterized in that it is set to satisfy the condition of <Φl+h. 3. When welding a metal plate and a metal wire, a protrusion is formed on the surface of the metal plate, the protrusion and the metal wire are brought into cross contact, and the metal plate/metal wire is connected to a pair of electrodes for welding. In a welding method in which electrical resistance welding is performed by applying an electric current while clamping the metal plate under pressure, an insulating layer is formed on the surface of the metal plate in advance to cover the surface of the metal plate, and this insulating layer allows the metal wire during welding to adhere to the metal plate. A projection welding method characterized by preventing the welding current from being shunted when it comes into contact with a part other than the welded part. 4. A projection welding method according to claim 3, wherein the insulating layer is formed by forcibly oxidizing the surface of the metal plate. 5. Any one of the first claim, the third claim, and the fourth claim
In paragraph 1, the metal plate is a plate-shaped terminal disposed inside a molded case of an electronic device, the metal wire is made of Ni (nickel) wire, and when the resistance welding is performed, the upper and lower parts of the molded case are A projection welding method in which the welding electrode is introduced through an opening in the opening.