JPH11192562A - Electromagnetic welding of metal sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To instantaneously execute the similar welding as conventional spot welding or seam welding without using an electrode and to weld an object to be welded incapable of welding or extremely difficult for welding by a conventional method. SOLUTION: An upper plate 5 and a lower plate 6 which are arranged in a facing state are provided in a conductive state, one wind coil A such as a plane shape having a concentration part 7, wherein a concentrated current is made to flow into both or either of the upper plate 5 and the lower plate 6 is provided, is used, and meal sheets which are superposed between or outside the upper plate 5 and the lower plate 6 of the one wind coil A are disposed. The current is made to flow into the one wind coil A, and an eddy current is generated in the superposed metal sheets to weld them by utilizing the law of electromagnetic induction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to welding of a thin metal plate, and uses a substantially one-turn coil of a flat plate or the like, and instantaneously electromagnetically welds an aluminum thin plate or a copper thin plate without using electrodes. On how to do it.

[0002]

2. Description of the Related Art As a joining method of a thin metal plate, a method called spot welding, in which current and pressure are concentrated and resistance welding is performed by sandwiching a tip between appropriately formed electrodes as shown in FIG. 10, is generally used. in use. The main components of the welding machine are a power supply 1, a switch 2, and an electrode 3. When the electrodes 3 are placed above and below the stacked metal sheets 4 and pressurized, the switch 2 is closed, and current is concentrated through the electrodes 3, the metal sheet portions near the electrodes are heated by Joule heat generated by the electric resistance of the metal sheet material. Melt and join. Generally, welding is performed by applying a relatively large current for a short time. In addition, although it is the same as spot welding in principle, a method called a seam welding method in which a rotating electrode is used as an electrode and current is applied while applying pressure and rotating the rotating electrode is also used.

[0003]

In the conventional spot welding method shown in FIG. 10, when the plate is made of aluminum or the like, the melting temperature is low, but the thermal conductivity and the electrical conductivity are high, so that the welding is more difficult. It is necessary to pass current. Further, at the time of welding, there is a disadvantage that aluminum is easily welded to the tip of the electrode. For this reason, the feature of spot welding that the welding time is short and suitable for mass production is impaired.

[0004] There is also a method of welding by passing an electric current to a metal plate without using an electrode. A method of using a solenoid coil or a spiral coil and applying an eddy current to a metal plate and heating by utilizing the law of electromagnetic induction is considered. However, it is difficult to perform local welding, and it has not been practically used as a local welding method. This is because if the windings of the solenoid coil or the spiral coil are made thinner and smaller in size and local welding is performed, a large current flows and the coil is damaged.

The present invention solves the above-mentioned drawbacks of the conventional method, and uses a strong coil without using an electrode and instantaneously performs welding similar to conventional spot welding or seam welding. The challenge is to make it possible.

[0006]

SUMMARY OF THE INVENTION The present invention uses a single-turn coil, such as a rigid flat plate made of a conductor such as steel or copper alloy, and instantaneously applies a large current consisting of a discharge current to the one-turn coil. It is intended to flow. That is, first, in the present invention, the upper plate and the lower plate arranged in the facing state are provided in a conductive state,
Using a flat coil provided with a concentrated portion where current flows in a concentrated manner on both or one of the upper plate and the lower plate, and a thin metal plate disposed between the upper plate and the lower plate of the flat coil. Is disposed, a current is caused to flow through the plate-shaped coil, and by utilizing the law of electromagnetic induction, an eddy current is generated in the superposed metal sheet and the superposed metal sheet is welded. The present invention relates to an electromagnetic welding method for metal sheets.

More specifically, according to the present invention, the concentrating portion is formed such that a current flowing through the upper plate and the lower plate is concentrated at a substantially central portion of each of the upper plate and the lower plate so that a current flowing through the upper plate and the lower plate flows. The concentrated portions provided on the upper plate and the lower plate are provided at opposing positions, and the magnetic flux generated at the concentrated portion intersects the superposed thin metal plate disposed between the upper plate and the lower plate. The method according to claim 1, wherein an eddy current is generated in the metal sheet.

[0008] The present invention is characterized in that the shape of the upper plate or the lower plate of the flat coil is changed, and different kinds of thin metal plates arranged and superposed between the upper plate and the lower plate are welded. The present invention relates to an electromagnetic welding method for a metal sheet according to any one of claims 1 and 2.

Second, according to the present invention, an upper plate and a lower plate which are arranged to face each other are provided in a conductive state, and a concentrated portion in which a current flows in one of the upper plate and the lower plate is provided. A flat-plate coil is used, and a thin metal plate is arranged outside the upper plate or the lower plate provided with the concentrated portion of the coil, and a current is applied to the flat-plate coil. The present invention relates to a method for electromagnetically welding thin metal sheets, wherein an eddy current is generated in the stacked thin metal sheets and the stacked thin metal sheets are welded.

More specifically, according to the present invention, the current flowing through the upper plate or the lower plate is concentrated on one of the upper plate or the lower plate of the flat coil and the current flowing through the upper plate or the lower plate is concentrated. A concentrated portion is formed, and a magnetic flux generated in the concentrated portion intersects the superposed thin metal plate disposed outside the upper plate or the lower plate provided with the concentrated portion to generate an eddy current in the thin metal plate. According to a fourth aspect of the present invention, there is provided a method for electromagnetically welding thin metal sheets. In each of the above methods, a metal sheet having a low melting point and a high electrical conductivity may be interposed on the joining surface of the metal sheet.

Thirdly, the present invention relates to a flat one-turn coil provided with a concentrated portion through which a current flows in a concentrated manner, and a U-shape formed by forming a long narrow conductive plate into a U-shape. One-turn coil,
Alternatively, a single-turn coil having a flat plate shape having a narrow conductor portion and a wide conductor portion, and a current input portion and an output portion provided at both ends of the coil so that a discharge current flows through the coil. The present invention relates to an electromagnetic welding apparatus characterized in that a discharge power supply is electrically connected to a power source via a switch.

In the above-mentioned electromagnetic welding apparatus, the converging portion in which the current of the flat one-turn coil flows in a concentrated manner can be formed by a narrow circular conductor plate. Further, the U-shaped one-turn coil can be formed by a flat plate-shaped collective wire in which conductive wires having a circular cross section are arranged horizontally long. In addition, a plurality of U-shaped single-turn coils can be arranged in parallel or crosswise. A magnetic flux shielding plate may be provided on a part of each coil.

Further, the above-described method of the present invention can be applied to a method of peeling a welded thin plate. That is, the fourth
Further, the present invention provides a welded product obtained by interposing a low-melting-point, high-conductivity metal thin plate between at least two thin plates and welding the flat plate-shaped single-turn coil upper plate of the apparatus according to claim 7. Between a lower plate, or a U-shaped one-turn coil in which a long narrow conductor plate is formed in a U-shape, between an upper plate and a lower plate of the coil, or one turn of a single plate provided vertically. Arranged between the upper and lower coils, the current gradually flows through the coil, suddenly cuts off, and utilizes the law of electromagnetic induction to generate an eddy current in the arranged welded article, and the joint portion is heated by Joule heat. The present invention relates to a method for peeling a welded product made of a thin plate, wherein the welding is performed by heating and melting and an electromagnetic force by a high-density magnetic flux acts in a direction to separate the portion.

The method of the present invention is suitable for welding metal sheets such as aluminum sheets and copper sheets. In addition, it is possible to weld materials that are difficult to perform resistance welding, such as welding between thin metal materials such as metal-laminated on an insulating material or a thin metal plate with the same,
In addition, in the past welding methods like low melting metal sheets,
Because it melts too much, even for thin plates that were difficult to weld, in the method of the present invention, if the state of magnetic flux and eddy current is controlled,
It can be welded instantaneously without excessive melting. In addition, a long seam-like joint can be instantaneously welded in accordance with the shape of the current concentration part.

In the case of using a solid flat single-turn coil,
When a current suddenly flows through the flat coil, a high-density magnetic flux (magnetic flux density B) is rapidly generated in a portion (current concentrated portion) of the upper plate and the lower plate of the coil where the current flows in a concentrated manner. If a superposed thin metal plate (conductivity k) is placed between the upper plate and the lower plate, the generated magnetic flux intersects the thin metal plate. As a result, an eddy current (current density i) flows through the thin plate, and an electromagnetic force (i ×
B) works. Since Joule heat (i ² / k) is generated in the portion where the eddy current flows, this portion is heated to the softening temperature or melting point in a short time and cooled in a short time. If the magnitude of the current, the rate of change of the magnetic flux over time, the magnitude of the electromagnetic force, the condition of the joint surface, etc. are appropriate, the thin plate is welded. This phenomenon is caused by a U-shaped single-turn coil in which a strong, narrow, long conductor plate is formed in a U-shape, or a flat plate, which has a strong, narrow, long conductor portion and a wide, conductor portion. The same applies to the case where a single-turn coil having a shape of one plate is used.

An eddy current is generated in the work to be welded to heat and melt the joint by Joule heat, and at the same time, a large current sufficient to cause the electromagnetic force due to the high-density magnetic flux to act in a direction to press the part is applied. As a discharge power supply for flowing through the coil, for example, a capacitor power supply may be used to close the discharge gap switch to allow current to flow. Specifically, a capacitor power supply 50 to 200 μF, a voltage 5 to 15 μF
It is preferable to charge the battery to kV, close the discharge gap switch, discharge the coil, discharge a current having a peak value of 10 kA or more, a rise time up to this current value within 10 μs, and a current flowing time of 100 μs or less. If a large current suddenly flows and then suddenly cuts off halfway, the flow of the eddy current will change suddenly, and as a result, the electromagnetic force will no longer act as pressure. And decrease.

As a conductor plate constituting a strong coil, steel is desirable in terms of strength and durability, and a copper alloy or the like having high conductivity and strength is suitable. The conductor plate may be reinforced with an insulating material or the like. The width of the portion where the current is concentrated differs depending on the cross-sectional shape, conductivity, current value, type and thickness of the thin plate to be welded, etc. It is preferably about 10 to 10 mm. Further, the thickness of the conductor plate is practically preferably about 2 to 5 mm. The conductor plate may be used insulated, or may be fixed and insulated using a fastener or the like with an insulating sheet interposed between the conductor plate and the thin metal plate.

If the width and number of the portions where the current is concentrated are changed between the upper plate and the lower plate, and the magnitudes of the currents flowing therethrough are respectively changed, the eddy currents flowing through the different types of metal thin plates are also different. This is suitable for welding metal sheets having different melting points (for example, aluminum and copper). If a larger current is applied to the concentrated portion on the metal plate side having a higher melting point, both metals having different melting points can be welded in the same molten state. If the thickness is increased without changing the width of the conductor plate, the density of the magnetic flux effective for welding among the magnetic fluxes generated in the conductor plate when a large current flows is reduced. The thicknesses of the upper and lower conductor plates may be changed according to the difference in melting point of the dissimilar metal sheets, and the dissimilar metal sheets may be sandwiched, and the dissimilar metal sheets may be welded in the same softened state.

In the method of the present invention, a low-melting-point, high-conductivity metal sheet can be interposed on the joint surface of the workpiece.
An ultra-thin metal sheet with a high conductivity and a low melting point is sandwiched between two thin sheets of the same kind of metal or alloy, and these three layers are placed inside or outside the coil. And a discharge current is passed through the coil. At this time, an eddy current flows easily, and the pure metal sheet having a low melting point is melted.
Two metal or alloy sheets can be welded.

When peeling the welded thin plate, specifically,
The welded metal sheets are sandwiched and arranged between the coils as in the embodiment of the welding method of the present invention. However, the distance between the conductor plates is slightly increased. First, a large current having a peak value of 10 kA or more is passed through the coil slowly over about 100 times as long as the time of welding (on the order of μs). At this time, almost no eddy current flows. Next, the large current was set to 10 μs
Cut off sharply within. At this time, an eddy current flows through the metal or alloy sheet sandwiching the pure metal sheet. When a large current is interrupted, the current and the magnetic flux decrease, so that the eddy current flows in a direction opposite to that at the time of welding, and the pure metal sheet welded between the metal sheets melts. The electromagnetic force acting simultaneously acts in a direction to separate the metal or alloy thin plates. As a result, the welded metal or alloy sheet is peeled from the joint.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a coil and the arrangement of a coil and an object to be welded when implementing the present invention will be described below based on specific examples. 1st Embodiment FIG. 1 is an example of a flat-plate one-turn coil A, (a) is a side view, and (b) is a plan view of an upper plate or a lower plate. According to the method of the first embodiment, the discharge current can be effectively used in reciprocation between the upper plate and the lower plate. Therefore, the method of the second embodiment mainly uses either the upper plate or the lower plate. Energy efficient.

The main components of the welding machine are a discharge power source 1, a switch 2, an upper plate 5, and a lower plate 6. The upper plate 5 and the lower plate 6 are connected at one end to form a coil A. In an actual case, the coil A is covered with an insulating sheet, and is fixed from above and below using a fastener.
The upper plate 5 and the lower plate 6 are provided with a portion (a current concentration portion 7) in which the width of the plate is reduced and current is concentrated and flows near the center of the plate. The thin metal plates 4 to be welded are superposed and placed between the coil upper plate 5 and the lower plate 6 as shown in FIG. When the switch 2 is closed, a large current flows to the insulated coil A in a short time. At locations other than the portion 7 where the current is concentrated (including the power source 1, the switch 2, and the connection portion), if the current is made to flow as wide as possible to make the current easier to flow, welding can be performed efficiently with less power source energy.

The current concentrating portions 7 of the upper plate 5 and the lower plate 6
The welding area can be changed by changing the size and the shape of the steel and controlling the range in which the magnetic flux is generated. In addition, the current concentrating portions 7 need not be located near the center of the plate, and may be separately separated at two or more locations.

FIG. 2 shows an example of a flat, single-turn coil A in which the size of the current concentrating portion 7 in FIG. 1 is changed and the length of the current concentrating portion 7 is increased. (B) is a side view, and (c) is a plan view of a lower plate. The stacked metal sheets are placed between the current concentrating portions 7 of the coil upper plate 5 and the lower plate 6.

FIG. 3 is a plan view of a single-turn coil A in which the shape of the current concentrating portion 7 in FIG.
(A) is a plan view of an upper plate, (b) is a side view, and (c) is a plan view of a lower plate. As the coil A, a circular shape is used in which the upper and lower narrow and long current concentrating portions connected to the wide portions on both sides are branched into two in the middle and then merged. If a large current is applied to the coil A by sandwiching the superposed portion of the thin metal plate between the upper plate and the lower plate of the coil A, a welded portion can be formed in a substantially circular shape at the branched portion. If welding is incomplete near the branch point of the current, coil A should be moved about 9
The lap welding may be performed by rotating the coil A by 0 ° and supplying a large current to the coil A again. Can be welded closed in a circular shape. Alternatively, the coil A can be placed on one side of a thin metal plate, closed in a circular shape, and welded.

Second Embodiment FIGS. 4A and 4B show an example of a flat one-turn coil A in which the shape of the lower plate of FIG. 1 is changed, wherein FIG. 4A is a side view, and FIG. FIG. Similarly, FIG. 5 shows an example of a flat-plate one-turn coil A in which the shape of the lower plate in FIG. 2 is changed, (a) is a plan view of the upper plate, (b) is a side view, and (c). Is a plan view of the lower plate. The upper plate 5 of the coil A is the same as in FIGS. 1 and 2 of the first embodiment. A hole 9 is formed near the center of the lower plate 6 so that current does not flow to the center. An insulating sheet is provided around the coil A. The metal sheets 4 to be welded are stacked on each other as shown in FIG.
Placed outside. If the coil A and the metal thin plate 4 are fixed with a clamp or the like, the switch 2 is closed, and a large current is applied to the coil A in a short time, a high-density magnetic flux (magnetic flux density B) around the portion 7 where the current is concentrated. Occurs rapidly. This magnetic flux crosses the metal sheet 4 (conductivity k). As a result, the metal sheet 4 is heated to the softening melting point and welded. A hole 9 is formed in the lower plate 6 of the coil so as not to hinder the generation of high-density magnetic flux, which is effective. The method according to the second embodiment is suitable when the upper plate and the lower plate cannot be installed on both sides of the thin metal plate.

Third Embodiment FIG. 6 shows a U-shaped single-turn coil C in which a narrow conductor plate is formed in a U-shape by changing the shape of a current concentrating portion and a metal thin plate. (A) is a perspective view, (b)
Is a plan view, and (c) is a sectional view perpendicular to the direction of current.
When the cross section perpendicular to the current of the conductor plate constituting the current concentrating part is a horizontally long rectangle, the inductance of the coil C is reduced,
Large currents flow easily. Since the flat-shaped collective conductor is flexible, it is convenient when used when the thin metal plate itself is bent gently. In addition, a flat plate-shaped collective conductor can be bent gently to form a weld along the curve. The thin metal plates 4 to be welded are placed between the upper and lower conductor plates 11 in an overlapping manner. Coil C and metal sheet 4
When the switch 2 is closed and a large current is applied to the coil C in a short time, a high-density magnetic flux is rapidly generated, and this magnetic flux is generated as shown in FIG. Intersect with As a result, the metal sheet 4 is heated to the softening melting point and welded. This single-turn coil C is made of a weldable material such as a thin metal plate and a plastics sheet, a low-melting metal thin plate, a material laminated on an insulating material, a conductive plastic sheet having a low melting temperature, and a metal. It is also suitable for welding metal sheets that are impossible or very difficult to weld by conventional methods such as sheet metal.

FIGS. 7A and 7B show an example in which a plurality of U-shaped single-turn coils C made of the narrow and long conductor plate shown in FIG. 6 are arranged in parallel, FIG. 7A is a plan view, and FIG. Is a side view. Each coil C is connected in series or in parallel. These coils C constitute one coil as a whole. If a large current is applied to this coil, welding of a plurality of portions of the stacked metal thin plates 4 can be performed simultaneously. Further, the coils C may be arranged so as to cross each other. When the coils C are arranged so as to intersect with each other, in order to ensure the welding of the welded portions corresponding to the positions where the coil conductor plates intersect with each other, a thin portion is provided in the intersection of the conductor plates constituting the coil C in the direction in which current flows. It is good to provide many slits. With this configuration, it is possible to prevent an eddy current from flowing through the conductor plate itself in the portion where the conductor plates overlap. The single-turn coil C can be freely moved in a horizontal plane.

FIGS. 8A and 8B show a U-shaped single-turn coil C shown in FIGS. 6 and 7 in which a magnetic flux shielding plate is provided. FIG. 8A is a plan view, and FIG. 8B is a side view. The insulated thin magnetic flux shielding plate 13 is attached to a part of the inside of the narrow and long U-shaped conductor plate 11. The magnetic flux blocking plate 13 is made of a material having extremely high conductivity. When a large current flows through the coil C, the generated magnetic flux is blocked by the magnetic flux blocking plate and does not permeate inside the coil C.

When welding is performed using the coil C, a portion where the magnetic flux shielding plate 13 is present is not welded. Welding is performed only at places where there is no magnetic flux blocking plate 13. If the magnetic flux shielding plate 13 is welded with the coil C attached discretely, it can be welded long in a dotted line. Further, if the conductivity and the thickness of the magnetic flux blocking plate 13 are selected, the ratio of blocking the magnetic flux can be freely changed. In this case, the magnetic flux blocking plate 13 acts as a magnetic flux control plate 13 for controlling magnetic flux.

Further, the magnetic flux control plate 13 can be entirely attached to one of the upper and lower conductor plates. A dissimilar metal thin plate is sandwiched between such coils C. However, the conductivity and thickness of the magnetic flux control plate 13 are selected so that different kinds of metals are in the same softened state.
Install. As a result, the dissimilar metal thin plate can be easily welded without excessively melting the low melting point metal.

A plurality of magnetic flux shielding plates 13 may be arranged at a different height from the plurality of coils C shown in FIG. 7 so as to be freely movable in a horizontal plane. When a large current is applied to each coil C a plurality of times while freely moving the plurality of coils C and the plurality of magnetic flux blocking plates 13 and welding is repeated, welding of a complicated shape becomes possible.

Fourth Embodiment FIG. 9 is a plan view in which the upper plate and the lower plate of the flat coil are changed to a single flat plate, and the flat plate has a long narrow conductor portion and a wide conductor portion. It is an example of a single-turn coil D of a single plate,
(A) is a plan view and (b) is a side view. Current concentrator 7
Is extended, and a wide conductor 8 is provided in parallel with the current concentrating portion 7 interposed therebetween. The current concentrating portion 7 is formed integrally with the wide conductor 8 on the right end. A thin metal plate 4 is placed on the coil D, and the whole is fixed and welded from above and below using a fastener. Also, if a plastic sheet is placed on the coil D, a thin metal plate is placed on the sheet, and the sheet is pressed and fixed, and a large current is suddenly passed through the coil, no eddy current flows through the plastic sheet. It flows to the plastic sheet side surface of the metal sheet. As a result, the temperature of the joint surface of the two increases, reaches the softening melting point, and the two are welded by appropriately adjusting the pressure by the electromagnetic force.

[0034]

Embodiments are described below. Example 1 A case where welding was performed by actually supplying a current to the coil A in the form shown in FIG. 2 of the first embodiment will be described below. The power supply 1 uses a low-inductance power supply capacity C = 50 to 200 μF, a charging power of 0.5 to 3 kJ for a capacitor power supply, closes the switch 2, and turns the portion 7 where the current of the coil A concentrates in one turn of 5 mm. A discharge current was passed through the flat coil A. The size of the steel coil is 200 × 145 × 5mm
It is. The upper plate and the lower plate are brought into close contact with an insulating sheet interposed therebetween.
Both plates have a thickness of 2 mm, a narrow long portion shown in FIG. 2 having a width of 5 mm, and a length of 30 to 70 mm. Welding Al (A
1050) The flake has a total length of 50 mm, a width of 20 to 50 mm, and a thickness of 0.3 mm. Polish the tip of the Al flake, about 10 ~
20 mm was overlapped and welded. About 5mm in width and 20-5 in length
A 0 mm joint was formed. The bonding strength increases up to a certain level in proportion to the charging energy and increases to 3M at 1 kJ.
It was 6 MPa at Pa and 1.5 kJ. If the charging energy is excessive, excessive melting occurs and good bonding cannot be achieved.

Example 2 A case where welding is performed by actually applying a current to the coil A in the form shown in FIG. 4 of the second embodiment will be described below. A low-inductance capacitor power supply similar to that of the first embodiment was used as the power supply 1, the switch 2 was closed, and a discharge current was applied to the flat coil 1A having a width of 10 mm where the current of the coil A was concentrated. . The maximum value of the current flowing through the coil A is about 118 kA when the charging energy of the power supply is 0.5 kJ,
The magnetic flux density generated on the surface of the central portion 7 of the upper plate 5 is about 5
It was T. Further, the magnetic pressure corresponding to the electromagnetic force was estimated to be about 9 MPa when the metal thin plate 4 was a copper plate.

[0036]

The present invention can provide a method of electromagnetically welding a thin metal plate without using an electrode as in the conventional example, and has conventionally been a problem when spot welding a thin plate of aluminum or the like. Welding of the metal to be welded to the electrode can be almost completely prevented. Therefore, welding of a thin aluminum plate or the like, which has been relatively difficult due to the use of the electrodes, is also facilitated, and a large amount of welding can be performed in a short time. In addition, materials that cannot be welded by the conventional method, and thin plates that are difficult to weld because they melt too much, can be welded instantaneously by controlling the state of magnetic flux and eddy current in the method of the present invention. .

[Brief description of the drawings]

FIG. 1A is a side view of a flat coil A according to a first embodiment of the present invention, and FIG. 1B is a plan view of an upper plate or a lower plate.

FIGS. 2A and 2B are a side view and a plan view of a lower plate of a flat coil A in which a current concentrating portion in FIG. 1 is elongated.

3A is a plan view of an upper plate, FIG. 3B is a side view, and FIG. 3C is a plan view of a lower plate.

FIG. 4A is a side view of a flat coil A according to a second embodiment of the present invention, and FIG. 4B is a plan view of a lower plate.

5 (a) is a plan view of an upper plate, FIG. 5 (b) is a side view, and FIG.

FIG. 6A is a perspective view, FIG. 6B is a plan view, and FIG. 6C is a plan view of a single-turn coil C and a thin plate in which a narrow and long conductor plate according to a third embodiment of the present invention is formed in a U-shape. It is sectional drawing of a direction perpendicular | vertical to an electric current.

FIG. 7A shows a case where a plurality of single-turn coils C in FIG. 6 are used;
It is a top view, (b) side view.

8 (a) is a plan view and FIG. 8 (b) is a side view in the case where a magnetic flux blocking plate is provided in the single-turn coil C of FIG.

FIG. 9A is a plan view and FIG. 9B is a side view of a single-turn coil D having a long and narrow conductor portion and a wide conductor portion according to a fourth embodiment of the present invention.

FIG. 10 is a side view showing the concept of a conventional spot welding method.

[Description of Signs] 1 Discharge power supply 2 Switch 4 Thin plate 5 Upper plate of flat coil 6 Lower plate of flat coil 7 Current concentrating part 8 Wide conductor part 9 Hole 13 Magnetic flux blocking plate A Flat single-turn coil C -Shaped single-turn coil D Single-plate single-turn coil

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05B 6/10 381 H05B 6/10 381 6/36 6/36 D

Claims (12)

[Claims] An upper plate and a lower plate arranged in a facing state are provided in a conductive state, and a plate-shaped coil provided with a concentrated portion in which a current flows in a concentrated manner in one or both of the upper plate and the lower plate is used. ,
Between the upper plate and the lower plate of the flat coil, a superposed thin metal plate is disposed, an electric current is applied to the flat coil, and the metal is superposed using the law of electromagnetic induction. An electromagnetic welding method for a metal sheet, wherein an eddy current is generated in the sheet and the stacked metal sheet is welded. 2. A concentrating portion in which a current flowing through the upper plate and the lower plate flows in a concentrated manner at a substantially central portion of each of the upper plate and the lower plate, and the upper plate and the lower plate are formed. The magnetic flux generated in the concentrated portion intersects with the superposed thin metal plate disposed between the upper plate and the lower plate to generate an eddy current in the thin metal plate. The electromagnetic welding method for a thin metal plate according to claim 1, wherein the electromagnetic welding is performed. 3. The method according to claim 1, wherein a shape of an upper plate or a lower plate of the flat coil is changed, and different kinds of thin metal plates disposed between the upper plate and the lower plate are welded. 3. The electromagnetic welding method for a metal sheet according to any one of claims 1 and 2. 4. An upper plate and a lower plate arranged in opposition are provided in a conductive state, and a plate-shaped coil provided with a concentrated portion through which current flows in one of the upper plate and the lower plate is used. Outside the upper plate or the lower plate provided with the concentrated portion of the coil, a superposed thin metal plate is disposed, an electric current is applied to the plate-shaped coil, and the superposed thin plate is utilized by using the law of electromagnetic induction. An electromagnetic welding method for a metal sheet, wherein an eddy current is generated in the metal sheet thus formed and the stacked metal sheets are welded. 5. A concentrated portion in which a current flowing through the upper plate or the lower plate flows in a concentrated manner at a substantially central portion of one of the upper plate and the lower plate of the flat coil, and the concentrated portion is formed. The magnetic flux generated in the concentrated portion intersects with the superposed thin metal plate disposed outside the upper plate or the lower plate provided with the portion to generate an eddy current in the thin metal plate. The method for electromagnetically welding metal sheets according to claim 4. 6. The electromagnetic welding method for a metal sheet according to claim 1, wherein a metal sheet having a low melting point and a high electrical conductivity is interposed on the joining surface of the metal sheet. 7. A flat-plate single-turn coil provided with a concentrated portion through which a current flows in a concentrated manner, a U-shaped single-turn coil formed by forming a long narrow conductive plate into a U-shape, or a narrow single-turn coil. A single coil of a flat plate having a long conductor and a wide conductor,
An electromagnetic welding apparatus characterized in that a discharge power supply is electrically connected via switches to current input portions and output portions provided at both ends of the coil so that a discharge current flows through the coil. 8. The electromagnetic welding apparatus according to claim 7, wherein the converging portion in which the current of the flat-plate one-turn coil flows in a concentrated manner is formed of a narrow circular conductor plate. 9. The electromagnetic welding device according to claim 7, wherein the U-shaped one-turn coil is formed by a flat plate-shaped collective wire in which conductive wires having a circular cross section are arranged horizontally long. 10. The electromagnetic welding apparatus according to claim 7, wherein a plurality of U-shaped single-turn coils are arranged in parallel or crossed. 11. The electromagnetic welding apparatus according to claim 7, wherein a magnetic flux shielding plate is provided on a part of the coil. 12. A welded product obtained by interposing a low-melting-point, high-conductivity metal thin plate between at least two thin plates and welding the upper plate and the lower plate of a flat-shaped single-turn coil of the apparatus according to claim 7. A single-turn coil provided between the upper and lower plates of a U-shaped single-turn coil formed by forming a long and narrow conductor plate in a U-shape, or above or below Between the upper and lower parts of the coil, gradually cut off the current by flowing the current through the coil, and use the law of electromagnetic induction to generate an eddy current in the placed welded article and heat the joint by Joule heat. A method for peeling off a welded product made of a thin plate, characterized in that an electromagnetic force due to a high-density magnetic flux acts in a direction separating the portion while melting.