JP3118823B2 - Resistance welding method for resin composite type metal plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a resin composite type metal plate obtained by laminating a resin between a plurality of metal plates such as a vibration damping steel plate and a lightweight laminated steel plate. The present invention relates to a method for resistance welding to a metal member.

(Prior Art) For example, in recent years, a resin composite type metal plate 1 in which a viscoelastic resin 2 is sandwiched between two metal plates 1a and 1b as shown in FIG.
It is increasingly used as a material for reducing the weight or damping of automobiles and home electric appliances. However, in this resin composite type metal plate, since the intermediate resin layer is an insulating material, resistance welding to another metal member, for example, when spot welding, electrically connects the metal plates sandwiching the intermediate resin layer. Requires means.

Conventionally, as a means, there is provided a method of providing an auxiliary energizing circuit 4 at an end of a resin composite type metal plate 1 and another metal plate 3 which are superimposed as shown in FIG. There is a method in which a conductive material 5 such as a metal powder (for example, zinc, aluminum, or copper) is dispersed in the resin 2 to impart conductivity to the resin.

In the method of providing the auxiliary energizing circuit 4 and performing resistance welding, the resin composite metal plate 1 and the other metal plate 3
Shunt current 6 flows, and the shunt current 6 causes Joule heating of the metal plates 1a and 1b constituting the resin composite metal plate 1,
The resin 2 immediately below the welding electrode 7 softens, and the metal plates 1a and 1b come into contact with each other, leading to the main current. In the case of a resin composite type metal plate in which a conductive material is dispersed, a welding current flows through the conductive material 5, and the heat generated causes the resin 2 to soften, and the metal plates 1a, 1a
b Electric contact between each other, leading to main energization.

(Problems to be Solved by the Invention) In the resistance welding of the resin composite type metal plate, the above-described method is employed. However, in the resin composite type metal plate, since an intermediate resin is an electrically insulating material, The contact resistance between the metal plates sandwiching the intermediate resin layer is higher than in the case of resistance welding between normal metal plates. In the case where the conductive material is dispersed in the intermediate resin, the contact resistance is low, but still higher than that of a normal metal plate.

When the contact resistance is high, the amount of heat generated in the resin layer increases when the welding current is applied, and when the welding current is increased for the purpose of stabilizing the strength of the welded portion, the resin composite type metal plate is formed between the metal plates. Dust is generated and resin around the weld is gasified. As a result, when blistering occurs near the weld or when resistance welding is performed near the plate end face, the fourth
As shown in the drawing, there is a case in which gas or gas generated from the end face of the plate is blown out to form an opening 8 in the end face. The blisters near the welded portion not only impair the appearance of the resin composite metal plate, but also reduce the strength of the welded portion. In addition, water and other corrosive substances in the environment penetrate from the opening at the end face, thereby impairing the corrosion resistance of the resin composite metal plate. In FIG. 4,
Reference numeral 9 denotes a molten nugget.

The blisters and openings described above occur even at low welding current values. In ordinary resistance welding of a metal plate, dust is blown out from the counterpart material, or a welding current value at which the welding current is deposited on the metal plate is the upper limit of the appropriate welding current range. On the other hand, in resistance welding of a resin composite metal plate, a welding current value that provides a required weld strength, for example, in spot welding, The appropriate welding current range is a range higher than the welding current value at which a nugget of the above diameter is formed and lower than the welding current value at which the blisters and openings are formed, but the welding current value at which the blisters and openings are formed is Dust blows out from the mating material in resistance welding of a normal metal plate, or is lower than a welding current value at which a welding electrode welds to the metal plate. For this reason, resistance welding of a resin composite metal plate has a narrower appropriate welding current range than resistance welding of a normal metal plate, and it is difficult to control welding conditions.

An object of the present invention is to solve such a problem. That is, an object of the present invention is to provide a resistance welding method for a resin composite metal plate having a wide appropriate welding current range, in which no blisters or openings are generated even when welding is performed at a high welding current value.

(Means for Solving the Problems) In resistance welding of a resin composite type metal plate, an intermediate resin immediately below a welding electrode is removed in advance, and metal plates constituting the resin composite type metal plate, or between the metal plate and the intermediate resin are removed. If heat generation in the intermediate resin layer is suppressed by bringing the conductive resin into contact with the conductive material and reducing the contact resistance at that portion, the formation of blisters and openings can be prevented. Therefore, the present inventors have conducted various studies on a method of eliminating the intermediate resin immediately below the welding electrode in advance. As a result, it has been found that when a current having a low current value is applied for a short time in a state where the joint is pressurized with the welding electrode in the initial stage of resistance welding, the intermediate resin is softened and eliminated without gasification.

Here, the gist of the present invention is that "in a method of resistance-welding a resin composite type metal plate obtained by laminating a resin between a plurality of metal plates to another metal member, in a state where the joint is pressed with a welding electrode, A resin composite type metal sheet characterized in that, after an initial current satisfying the following equation (1) is applied for an energizing time satisfying the following equation (2) without using a short circuit, a main welding current is applied. Resistance welding method ".

0.6I ₂ ≦ I ₁ ≦ 0.8I ₂ (1) t ₁ ≧ (1/6) t (2) where I ₁ : initial current (A) I ₂ : main welding current (A T ₁ : Energizing time of initial current (seconds) t: Plate thickness of resin composite metal plate (mm) The main welding current is a welding current that can obtain a required weld strength, for example, in spot welding. It means a current having a current value higher than a welding current value at which a nugget having the above diameter is formed.

(Operation) Hereinafter, the present invention will be described in detail.

In the resistance welding method of the present invention, in a state where the resin composite type metal plate is overlapped with another metal member and the joint thereof is pressed by the welding electrode, the main welding current I ₂ is applied before the main welding current I _{2 is applied.} passing a lower initial current I _1. This is because the resin is softened and eliminated without gasifying the intermediate resin immediately below the welding electrode. For this purpose, the initial current I ₁ will satisfy the above expression (1), shall be and energization time that satisfies the above expression (2).

If the initial current I ₁ is lower than 0.6 times the main welding current I ₂ ,
The intermediate resin immediately below the welding electrode is not gasified, but is insufficiently softened so that the intermediate resin is not effectively removed by the pressing force of the welding electrode. If the initial current I ₁ exceeds 0.8 times the main welding current I ₂ , the intermediate resin gasifies while the initial current I ₁ is being supplied, causing blistering near the welded portion or when the welding is near the plate end face. An opening is formed in the end face. Also, if shorter than the time that current supply time t ₁ of the initial current I ₁ is equivalent to 1/6 of the thickness t of the resin composite-type metal sheet (s), the intermediate resin is not effectively eliminated.

Initial current intermediate resin of the welding electrodes just below that is softened without Ruru gasified by I ₁ is eliminated around the pressurization of the welding electrode. Although the resistance welding has been carried out welding while pressurizing the material to be joined by welding electrodes, the initial current softened resin by I ₁ in order to efficiently remove the pressure of the electrode plate of the resin composite-type metal sheet It is better to determine according to the thickness. For example, when the plate thickness is 0.8 mm, the pressing force is preferably set to about 150 to 250 kgf.

By eliminating the intermediate resin at the joint, the metal plates constituting the resin composite type metal plate or the metal plate when the resin composite type metal plate is obtained by dispersing a conductive material in resin. Since the conductive material comes into contact with the conductive material, the contact resistance is locally reduced directly below the welding electrode. When the contact resistance is to be energized this welding current I ₂ When lowered, the heat generated in the intermediate resin layer is suppressed, compared with the conventional resistance welding method for energizing a main welding current I ₂ from the beginning, during energization of the welding current The current value at which the blister is formed and the current value at which the opening is formed at the end face are increased, and the appropriate welding current range is expanded.

 Next, the effects of the present invention will be described with reference to examples.

(Example) AS is placed between two steel plates having a thickness of 0.4 mm or 0.8 mm respectively.
A resin composite metal plate obtained by laminating a polyolefin resin containing 3 vol% of Ni powder of TM 200 mesh or less at a thickness of 0.05 mm and a steel plate (counterpart material) having a thickness of 0.8 mm or 1.6 mm were prepared.

These resin-composite-type metal plates and a steel plate were overlapped, and direct spot welding was performed at a position 20 mm from the end of the resin-composite-type metal plate to the plate center. Direct spot welding
Performed under the welding conditions shown in Table 1 using a chrome copper alloy dome-shaped electrode as the welding electrode, Welding current value when a nugget diameter of the size is obtained and welding current value when blistering occurs in the resin composite metal plate around the welded portion or welding when dust or gas blows out from the plate end surface to form an opening The current value was examined to determine an appropriate welding current range. The results are also shown in Table 1.

From Table 1, it can be seen that No. 1 to No. 5 of the present invention, which were spot-welded by the method of the present invention in which the main welding current was applied after the initial energization, were No. 12 and N which were spot-welded without initial energization.
It can be seen that the proper welding current range is expanded as compared with the conventional example of o.13. However, even if spot welding is performed by the method of applying the main welding current after the initial application as in the comparative examples of No. 6 to No. 11, the current value or the application time of the initial application from the range specified in the present invention. If not, the proper welding current range is not expanded.

(Effects of the Invention) According to the method of the present invention, blisters and openings are less likely to occur even with a higher welding current than in the conventional method, and an appropriate welding current range in resistance welding of a resin composite metal plate is expanded. Is easy.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing an example of a resin composite type metal plate, FIG. 2 is an explanatory view of resistance welding of the resin composite type metal plate using an auxiliary energizing circuit, and FIG. FIG. 4 is an explanatory view of resistance welding of a resin composite metal plate in which a conductive material is dispersed in FIG. 4, FIG. 4 is a view illustrating a state in which an opening is formed on an end face,
It is. 1: resin composite type metal plate, 1a: metal plate, 2b: metal plate, 2: resin layer, 3: other metal plate, 4: auxiliary circuit, 5: conductive material, 6: shunt current, 7: welding electrode , 8: Opening.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yoshikuni Kajimoto 2 Nissan Motor Co., Ltd., Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture (56) References JP-A-63-264279 (JP, A) JP-A-1- 127182 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B23K 11/16 320

Claims (1)

(57) [Claims] 1. A method for resistance welding a resin composite type metal plate obtained by laminating a resin between a plurality of metal plates to another metal member, wherein an external short circuit is formed while the joint is pressed by a welding electrode. A method of resistance welding a resin composite metal plate, comprising: applying an initial current that satisfies the following expression (1) for an energizing time that satisfies the following expression (2) without using the same; . 0.6I ₂ ≦ I ₁ ≦ 0.8I ₂ (1) t ₁ ≧ (1/6) t (2) where I ₁ : initial current (A) I ₂ : main welding current (A ) T ₁ : Initial current conduction time (seconds) t: Thickness of resin composite metal plate (mm)