JPH05277749A - Spot welding method and electrode - Google Patents

Abstract

PURPOSE:To form a satisfactory nugget and to obtain a welded product without the rough surface by applying a current to only the position to be welded of base metals and pressurizing the position to be welded in an insulated state electrically from the surface and rear to perform welding. CONSTITUTION:A substrate 3 to form an upper electrode 1 and a lower electrode 2 is composed of a rectangular metallic block body and a round bar-shaped handle 4 is provided projectingly thereon. A pressurization part 5 to pressurize the position to be welded of materials to be welded is provided on the central part in the longitudinal direction of the opposite side to this projecting surface and power feed parts 6 and 6 are provided on both sides thereof. The pressurization part 5 is formed of insulating material and integrally embedded in the central part of the substrate 3 by selecting heat resistant and wear resistant material with high hardness. The power feed parts 6 form a part of the metallic block body and are formed of electrically conductive material being used usually. Consequently, high resistance heat is generated only on the part where the base metals are brought into contact with each other and the satisfactory nugget is formed. Further, durability of the electrodes is improved, the number of uses thereof is increased and the working rate of welding equipment is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot welding method in which base materials are sandwiched between a pair of rod-shaped electrodes, and spot welding is performed within a range sandwiched by electrodes by applying electricity and pressure, and a method therefor. Regarding the electrodes used.

[0002]

2. Description of the Related Art When metal rods such as aluminum are fixed in a cross shape to form, for example, a net, the intersections of the metal rods are generally spot-welded. In spot welding, a metal rod intersecting with upper and lower electrode rods is pressed from above and below, and at the same time, electric current is applied through both upper and lower electrode rods to perform welding by electric resistance heat.

[0003]

By the way, it is required that the electrode rod has excellent heat resistance and wear resistance and also has good electrical conductivity. In recent years, a material excellent in heat resistance and an excellent electrical conductivity have been demanded. What is molded with an alloy with the above materials is used, and even in electrode rods using such metal materials,
When the metal rod is melted and solidified adheres to the pressure contact surface (pickup) and repeated welding is performed, the portion of the electrode rod that directly contacts the welded material is worn in a groove shape, shortening the life of the electrode rod faster. However, when the welding is further continued, the surface of the welded metal rod is scratched and the surface of the metal rod is roughened, resulting in a great loss of value of the product.

The present invention is to solve the above problems, and an object thereof is to provide a spot welding method and an electrode therefor, which reduce wear and prevent rough skin and have excellent durability.

[0005]

Means for Solving the Problems According to the means for solving the problems of the present invention, it is possible to energize only a position to be welded of a pair of superposed base materials, and to keep the other in an insulating state, and It is characterized in that the base material is energized and the positions to be welded are electrically pressed from the front and back in an insulated state to perform welding.

Further, the electrode according to the present invention is composed of an upper electrode element and a lower electrode element, both of which have a pressing portion for maintaining an electrically insulating state in the central portion, and a power feeding portion around the pressing portion. Is provided. In addition, it is preferable to provide a clamp portion for pressing each base material to the corresponding power feeding portion on the upper electrode element and the lower electrode element.

[0007]

EXAMPLES The present invention will be described in detail with reference to a welding electrode having a metal round bar as a base material. As shown in FIGS. 1 to 4, it is composed of an upper electrode element 1 and a lower electrode element 2. ,
Since the upper and lower parts have the same structure, only one of them will be described.

The base body 3 forming the upper electrode element 1 and the lower electrode element 2 is made of a rectangular metal block body, and a round bar-shaped handle portion 4 is provided in a protruding manner. A pressurizing portion 5 for pressing a position to be welded on a material to be welded is provided at a central portion in a longitudinal direction on a side surface opposite to a protruding surface of the handle portion 4 of the base body 3, and power feeding portions 6 and 6 are provided on both sides thereof. It is a thing.

The pressurizing portion 5 is an electrically insulating material, and a material having a high hardness excellent in heat resistance and abrasion resistance is selected and integrally embedded in the central portion of the base body 3. As the material, the entire pressurizing part is formed of ceramics, or the surface of the cemented carbide is covered with a non-conductor.

Further, the power feeding portion 6 is formed as a part of the metal block body, and the material thereof is made of a conventional expensive special material in terms of heat resistance and abrasion resistance, giving priority to good conductivity. It does not need to be formed, and is formed of a commonly used conductive material.

Further, the block body may be formed in a state in which a material suitable for the power feeding portions 6 and 6 and the pressure portion 5 is implanted.

Further, if the material to be welded is a round bar, a V or U-shaped groove 7 is formed on the surface of the base body 3 that abuts on the material to be welded, extending over both the left and right feeding portions 6, 6 and the pressing portion 5. It is provided.

Clamping portions 8, 8 are provided on both sides of the pressing portion 5 and on both sides orthogonal to the longitudinal direction of the base body 3 so that the material to be welded can surely contact the left and right power feeding portions 6, 6. The clamp part 8 is provided as shown in FIG.
A pressing member 10 made of an insulating material having a high hardness such as ceramics is urged in a protruding direction by a spring 11 on a case 9 forming the clamp portion 8. still,
The pressing member 10 and the spring 11 have both insulation and elasticity, and the pressing member 10 and the spring 11 may be integrally formed of, for example, rubber.

When the rods are welded in an orthogonal state by using the above-mentioned welding electrode, the rod W1 is placed along the groove 7 of the lower electrode element 2 as shown in FIG. The material W2 is placed orthogonally on the pressing members 10, 10 of the left and right clamps 8, 8 and the groove 7 of the upper electrode element 1 faces the longitudinal direction of the bar material W2 on which the upper electrode element 1 is mounted. As shown in FIG. 5, the upper and lower bar members W1,
W2 is pressed against both side surfaces of the grooves 7, 7 by the pressing members 10, 10 made of an insulating material, respectively, and the intersecting portions of both the bar members W1, W2 are pressed by the upper and lower pressing portions 5, 5. Therefore,
By applying a high amperage current to each of the upper and lower electrode elements 1 and 2, the upper and lower power feeding portions 6 and 6 are energized, but the energized position is given from a portion other than the welded intersecting and overlapping portions. In addition, the contact state between the rods W1 and W2 of the power feeding unit 6 is such that both sides of the rod are linearly in contact with the side surfaces of the groove 7, and therefore the rod is supplied with power from a plurality of locations, so that resistance is generated. On the other hand, the crossing portion is pressed by the pressurizing portions 5 and 5 of the insulating material at the intersecting portion, so that contact electric resistance is generated there and heat is generated and the welding is performed.

Next, in the example shown in FIG. 6, the thin metal plate W3,
W4 is connected by spot welding, the insulating layer 12 is interposed between the overlapping portions, and a hole 13 is made in the insulating layer 12 at a position to be welded. Spot welding is performed by applying a current from around the portion corresponding to the hole 13 and pressing the portion of the hole 13 with an insulating material.

As shown in FIGS. 7 and 8, the electrode capable of realizing the welding method is composed of the upper and lower electrode elements 1a and 2a as in the above example, and is a metal block having a circular cross section and having a good current-carrying function. The handle portion 4 is formed by a base body 3a composed of a body, and is provided with a protrusion. A peripheral surface of the base body 3a opposite to the projecting surface of the handle portion 4 except for the central portion serves as a power feeding portion 6a, and an insulating pressurizing portion 5a made of a ceramic cylindrical body is provided at the central portion.
Is urged by an elastic body 14 such as a disc spring or a ring spring in a direction projecting from the surface of the power feeding portion 6a.

As another example, as shown in FIGS. 9 and 10, both upper and lower electrode elements 1b and 2b are formed of a base 3b made of a metal square block, and a ceramics is formed at the center of the facing surface. The insulating pressurizing portion 5b made of a cylindrical body is provided in a protruding manner, and the power feeding portions 6b, 6b made of a metallic cylindrical body having excellent electric conductivity are urged on both sides by springs 15 in a protruding direction. The rails 17 and 17 that are provided to engage the power feeding portion 6b with the cavity portion 16 in which the power feeding portion 6b is fitted in order to ensure the power supply to the power feeding portion 6b.
Is preferably provided. An adjusting means (not shown) may be connected to the pressing portion 5b so that the amount of protrusion of the pressing portion 5b can be adjusted depending on the plate thickness to be welded.

[0018]

According to the spot welding method of the present invention,
Power is supplied from around the positions where the base materials should be welded, and the positions to be welded are electrically insulated and pressed for welding, so the material of the electrode that supplies power is expensive to prevent pickup and shortening the life. It is not necessary to use a special alloy, and it is carried out by a normal conductive material with good current flow. Compared with the conventional welding method, there is almost no generation of electrical resistance in the power feed part, and there is There is no change. In addition, since the portion to be welded is simply pressed in an electrically insulated state to perform welding, a large resistance heat is generated only in the portion of the base material in contact with each other to form a good nugget. It is possible to provide a good welded product with no molten metal adhered to the part and no damage to the power feeding part of the base material, and no rough skin.

Further, the electrode for carrying out the above-mentioned welding method is constituted by providing an electrically insulating pressurizing portion in the central portion and providing a power feeding portion in the periphery thereof, and each portion can be formed of an appropriate material. Therefore, the cost can be reduced, and the durability can be further improved.
Therefore, the number of times the electrode is used is greatly increased, which improves the operating rate of the welding device.

[Brief description of drawings]

FIG. 1 is a perspective view showing an electrode for performing a spot welding method according to the present invention by an example adapted to a bar.

FIG. 2 is a plan view of a lower electrode element.

FIG. 3 is a cross-sectional view taken along the line AA of FIG.

4 is a cross-sectional view taken along the line BB of FIG.

FIG. 5 is a sectional view of the electrode showing a state during welding.

FIG. 6 is a perspective view showing a state in which thin plates are welded by a spot welding method according to the present invention.

7 is a front view showing an electrode suitable for welding the thin plates of FIG. 6. FIG.

FIG. 8 is a sectional view showing a welded state of the thin plates.

FIG. 9 is a cross-sectional view of essential parts showing an electrode according to another example of welding a thin plate by a spot welding method according to the present invention.

FIG. 10 is a sectional view showing a welded state of the thin plates.

[Explanation of symbols]

 1, 1a, 1b Upper electrode element 2, 2a, 2b Lower electrode element 3, 3a, 3b Base material 5, 5a, 5b Pressurizing section 6, 6a, 6b Power feeding section 7 Groove 8 Clamp section

Claims (3)

[Claims] 1. A position where welding is possible only between positions where a pair of base materials that have been overlapped are to be welded, and after the other parts are kept in an insulating state, current is applied to both base materials from a position other than the position where welding is to be performed. Spot welding method characterized by welding by pressing from the front and back in an electrically insulated state. 2. A pressurizing section (5) comprising an upper electrode element (1, 1a, 1b) and a lower electrode element (2, 2a, 2b), both electrode elements having an electrically insulating state at the center. , 5a, 5
b), and a power feeding unit (6, 6a, 6) around the pressurizing unit.
An electrode for spot welding, which is provided with b). 3. The upper electrode element (1) and the lower electrode element (2) are provided with a clamp part (8) for pressing each base material against a corresponding power supply part (6). Spot welding electrodes.