JPH08109359A - Method for bonding metallic plate - Google Patents

Abstract

PURPOSE: To provide a method for bonding a metallic plate by which appearance, rigidity and vibration damping properties can greatly be improved while maintaining the conventional productivity in assembling a structure made of a metal. CONSTITUTION: An electrically conductive structural adhesive 3 having a volume resistivity within the range of 10<0> to 10<10> Ω.cm and a thickness within the range of 5 to 200μm is formed in a space 3a between bonding parts of two metallic units 2 which are adherends and an electric current at a value within the range of 20 to 80% based on that required for welding of the mutual metallic units of the adherends is passed through the bonding parts to cure the structural adhesive by generation of heat in the metallic units by electric conduction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adhering a metal plate to a metal structure such as iron or aluminum, and is particularly used for assembling steel plate structures such as steel furniture and vehicles. The present invention relates to a method for adhering a metal plate capable of improving rigidity and vibration damping property.

[0002]

2. Description of the Related Art Conventionally, as a method of joining metal plates of a metal structure in the assembly of a metal structure in a steel plate structure, for example, a steel furniture, a vehicle, etc. 3 and FIG. 4, spot welding is performed. However, when this spot welding is performed, the welded portion 4 of the metal plate 2 to be joined by the welding current is heated and melted, and the welding force 4 is concentratedly applied to the melted welded portion 4. Therefore, as shown in FIG. The metal plate 2 in the welded portion 4 is deformed due to
(Referred to as "spot dent") 5 occurs. Incidentally, the meshed portion in FIGS. 3 and 4 is the welded portion 4. As described above, the spot welding has a problem in that, because the spot dents 5 are generated on the surface of the metal plate, the external appearance of, for example, steel furniture and vehicles is adversely affected. There are usually about 8 spot dents per 1 m.

Therefore, there is a method of using a structural adhesive as described below. Weld Bond Method First, the structural adhesive will be described. The structural adhesive is an adhesive that is generally used for adhesive bonding of structural parts, and is defined by JIS (Japanese Industrial Standard) K-6800 as "a reliable adhesive that can withstand a large load for a long period of time". Is. Such a structural adhesive does not have stress concentration because spot bonding is spot welding as opposed to surface bonding, and there is no destruction or deformation or cracking of the surface of the assembly. It has features.

Since the structural adhesive used in this method is a heat-curing reactive type, it is necessary to hold the adherend until the adhesive strength is exhibited. If not held, the adherend moves, Dropout occurs. Therefore, spot welding is performed as a method of fixing (hereinafter referred to as “temporary fixing”) until the initial strength of the adhesive is developed. In this method, the structural adhesive is used to improve the rigidity at the joint of the metal structure, and the spot welding is used as a temporary fixing, so there is no spot dent. It cannot be done but can be reduced. In this method, the number of spot dents is usually about 4 points per 1 m.

All-adhesion construction method This construction method is a construction method in which spot welding is not performed and a metal structure is joined only with a structural adhesive, and spot dents do not occur. In this method, it is necessary to fix members that have no problem in appearance until the strength of the structural adhesive is developed. As this fixing method, a method of secondary temporary fixing or a structural adhesive is used. A method of curing the agent in a short time is required. The following methods have been devised as the above-mentioned temporary fixing methods, but each has the following drawbacks. (I)
A high-frequency induction heating device is used to quickly cure the structural adhesive. However, this method requires strict fixing and holding of the adherend, and the equipment cost is also very high. (Ii) Use a cyano-based instant adhesive or the like (two adhesives combined type). However, this method has low peel strength, impact resistance,
Poor heat resistance. In reality, the final proposal for the temporary fixing method has not yet been completed.

The present invention has been made to solve the above-mentioned problems, and can improve the conventional productivity in assembling a metal structure, and can greatly improve the appearance, rigidity, and vibration damping property. It is an object of the present invention to provide a method for adhering a metal plate.

[0007]

According to the present invention, the volume resistivity is 10 ⁰ to 10 10 between the bonded portions of two metal bodies which are bonded bodies.
20% to 80% of the electric current value necessary for welding the above-mentioned metal bodies of the adherend is provided by providing a conductive structural adhesive in the range of ¹⁰ Ω · cm and the thickness of 5 μm to 200 μm. A current value in the range is applied between the bonded portions of the two metal bodies, and the structural adhesive is cured by heat generation of the metal body caused by the energization.

[0008]

EXAMPLES In order to solve the above problems, the inventors of the present invention cured an adhesive that exhibits sufficient adhesive strength after curing in a short time without causing deformation such as welding dents in a metal member. Various examinations were made on the method of making. As a result, it has been focused on that the metal plate generates heat by simultaneously applying pressure and electricity to the metal plate by a welding machine conventionally used for welding a metal plate, and the energization condition of the welding machine is considered. It has been found that by applying conductivity to the adhesive and adjusting the conductivity thereof, it is possible to cure only the adhesive in a short time without causing deformation of the adherend metal plate itself. Completed the invention. As will be described later in detail, the heating means for curing the adhesive is not limited to the above-mentioned welding machine, and pressurization is not an essential condition.

An embodiment of the metal plate bonding method of the present invention will be described below with reference to the drawings. The bonding method of this embodiment is carried out by the device configuration shown in FIG.
That is, the two metal plates 2 as the adherends are provided so as to face each other so as to sandwich the adhesive portion 3a therebetween, and a structural adhesive 3 to be described later is provided in a range including the adhesive portion 3a in each metal plate 2. Are arranged with intervening. Of the front surface 2a of each metal plate 2 on the side opposite to the back surface on which the structural adhesive 3 is provided in each metal plate 2, each part 2b of each metal plate 2 corresponding to the above-mentioned adhesive portion 3a is provided in the present embodiment. Welder electrode 1 in the example
Are arranged in contact with the portions 2b, respectively. Then, in the same manner as in the conventional welding process, by passing an electric current through these electrodes 1, the respective metal plates 2 including the respective portions 2b are
Heats up. At this time, welding is not performed between the metal plates 2. That is, the current passed through each electrode 1 is a value at which the metal plates 2 are not welded to each other, and the value will be described in detail later.

Next, the structural adhesive 3 will be described. The structural adhesive 3 used in this example is the structural adhesive described above, and may be either a one-component type or a two-component type. Further, it may be either a room temperature curable type or a heat curable type, as long as the curing of the adhesive is promoted by heating and sufficient adhesive strength is exhibited.

Further, in the structural adhesive 3 in this embodiment, as described above, it is necessary to energize the two metal plates 2 via the structural adhesive 3 to heat the metal plate 2. The structural adhesive 3 needs to have electrical conductivity. Therefore, the structural adhesive 3 has a volume resistivity of about 10 ⁰ to 10 ¹⁰ Ω · cm. Further, when the volume resistivity is large, the current flowing between the electrodes 1 for passing a current through the metal plate 2 is small, and the resistance heating amount generated on the metal plate 2 as the adherend is small. The thermal energy required for curing the structural adhesive 3 cannot be secured, and sufficient adhesive strength cannot be obtained. The volume resistivity is preferably 10 ² to 10 ⁹ Ω · cm.

As a method of imparting conductivity to the structural adhesive 3 as described above, in this embodiment, a conductive material is mixed into the structural adhesive 3 and, as a result, the structural adhesive 3 is reduced in volume resistivity. It has a value of about 10 ⁰ to 10 ¹⁰ Ω · cm. In this embodiment, for example, copper having a particle diameter of 6 μm or carbon black having a particle diameter of 0.3 μm is used as the conductive material. Other conductive materials that can be used include gold powder, silver powder, nickel powder, aluminum powder, graphite, carbon fiber, and silver-plated fine particles. In addition, each particle diameter mentioned above is an average particle diameter.

In addition to the volume resistivity of the structural adhesive 3, the adhesive strength of the metal plate 2 largely depends on the film thickness of the structural adhesive 3 in the adhesive portion 3a sandwiched between the metal plates 2. It Therefore, when the structural adhesive 3 is applied and provided on the back surface of the metal plate 2, sufficient pressure is applied to the metal plate 2 so that the metal plate 2 itself is not deformed before heating, or the adhesive 3 is spread or necessary. In order to maintain the above film thickness, a spacer (filler) having a size corresponding to the film thickness, for example, a particle size, may be mixed in advance in the structural adhesive 3. As the spacer, for example, calcium carbonate or an inorganic powder of pigment is used.

As a specific film thickness, the thickness of the structural adhesive 3 is 5 to 200 μm when pressed. This is because when the film thickness is less than 5 μm, welding between the metal plates 2 occurs, and when it exceeds 200 μm, the adhesive strength between the metal plates 2 decreases.
The film thickness is preferably 5 to 90 μm, particularly preferably 50 μm.

Next, in the electrode 1, since the area where the structural adhesive 3 is hardened is spread by energizing the widest possible area of the adhesive portion 3a as uniformly as possible, the contact portion 1a contacting the metal plate 2 is smooth. It should have a shape that allows uniform pressure application. Specifically, the electrode 1 has, for example, a cylindrical shape and has a diameter of 5 to 1 at the contact portion 1a.
It is 5 mm, particularly preferably 8 mm. It should be noted that the energization area of the electrode 1 becomes wider, so that it is necessary to prolong the energization time or increase the current value within a range where welding does not occur.

Specific values of the energization time and the current value in this embodiment are shown below. The energization time is 0.01 to
It is 1 minute, preferably 3 to 10 seconds. The current value is an element that needs to be changed depending on the thickness and material of the metal plate 2 in order to achieve the desired adhesive strength, but the current required to satisfactorily weld the metal plate in that thickness and material. It is preferably in the range of 20 to 80% of the value. This is 2
This is because at a current value of less than 0%, the metal plate 2 does not generate enough heat to cure the structural adhesive 3, and at a current value of more than 80%, the metal plates 2 are welded to each other. When the metal plate 2 is adhered under the above-mentioned conditions such as the current value, the portion where the structural adhesive 3 is cured and the metal plate 2 is adhered is shown as a mesh in FIG. The bonded area has a larger bonding area of the metal plate 2 than in the case of spot welding.

As a first embodiment which is a more concrete example of this embodiment, referring to the table below, the metal plate when the film thickness, energization time, current value, etc. of the structural adhesive 3 are changed An experimental example in which the adhesive strength of 2 is measured will be described. In these experimental examples, the above-described spot welding machine was used to heat the metal plate 2. Table 1 shows the shear strength and the presence / absence of welding dents when the energization time and the current value are fixed at 6 seconds and 4000 A, and the thickness of the structural adhesive 3 when the metal plate 2 is pressed is changed. Indicated. Further, in these experimental examples, the structural adhesive VIII shown in Table 2 was used as the structural adhesive 3, and the SPCC-SD 0.8 mm thickness was used as the metal plate 2. Usually, the conditions for performing spot welding on this plate are a pressing force of 300 Kg / cm ² , a current value of 7700 A, and 20 cycles.
Conductive heating was performed at 4000% of 4000A. The curing conditions of the structural adhesive used in this experimental example were 170 ° C. and 20 minutes.

[0018]

[Table 1]

Table 2 shows various conditions for the adhesives I to III used as comparative examples for comparison with the adhesives used in the experimental examples.

[0020]

[Table 2]

Table 3 shows the bonding strength, the quality of the appearance, and the time required to generate a predetermined strength when the kind of the structural adhesive 3, the kind and the addition amount of the conductive material are changed.
Incidentally, the structural adhesive 3 is divided into adhesives IV to VIII, and the experimental examples V to IX are numbered correspondingly when the respective adhesives are used. In Table 3, in each of the experimental examples, SPCC-SD 0.8 mm thickness was used as the metal plate 2, and the current value to be passed through the electrode 1 was about 52% of the above 7700A 4000.
The thickness of the adhesive is 5 when the metal plate 2 is pressed.
0 μm.

[0022]

[Table 3]

As described above, by using, for example, an existing welding machine as a means for hardening the structural adhesive 3,
Even if a heating furnace is used, it takes several minutes to several tens of minutes to cure the heat-curing structural adhesive, and the structural adhesive is cured in a few seconds to a few tens of seconds without using the heating furnace. You can Therefore, the time for assembling the metal structure can be shortened. In addition, by adjusting the energizing current value, only the structural adhesive is hardened without causing welding on the metal plate 2, so that welding dents do not occur and the metal plate 2 in the bonded portion is not affected. It has a good appearance and can exhibit the strength required for joining metal plates.
In the above description, the welding machine is used as the heat generating means for the metal plate 2, but the welding machine is not limited to the welding machine, and any device capable of passing a current of a predetermined value to the metal plate 2 may be used.

Further, by using the bonding method of this embodiment as a temporary fixing of the metal plate 2, only a part of the applied thermosetting adhesive is hardened in a short time, and after surface treatment and overcoating are applied. By hardening the entire structural adhesive 3 by baking the paint, it is possible to realize an all-adhesion method of joining all of the metal plates 2 with only the adhesive without welding (without welding marks). .

Further, since the structural adhesive 3 is interposed between the metal plates 2, the damping property of the bonded metal plates is improved.

In the above description, the structural adhesive 3 is applied to the metal plate 2 and the metal plates 2 are pressed together by the electrodes 1. However, for example, the structural adhesive is previously applied. Eg 6
In the case of a sheet-like material capable of holding a thickness of 0 μm and the sheet-like adhesive is interposed between the metal plates 2 to bond the metal plates 2, positive pressure is necessary. Absent. or,
Even when the above-mentioned sheet-shaped adhesive is used because the weight of the metal plate 2 is large, positive pressurization is not required, and it is sufficient if a predetermined current can flow.

[0027]

As described above in detail, according to the present invention, the volume resistivity between the bonded portions of the metal body is in the range of 10 ⁰ to 10 ¹⁰ Ω · cm, and the thickness is in the range of 5 μm to 200 μm. A conductive structural adhesive is provided, and a current value in the range of 20% to 80% of the current value required for welding the metal bodies is supplied between the bonded portions of the two metal bodies, Since the structural adhesive is cured by the heat generated by the metal body, the metal plates can be bonded to each other in a shorter time than in the conventional case, and the productivity of the metal structure can be improved. Further, by curing the structural adhesive under the above conditions, the metal plates are not welded to each other and welding dents do not occur. Therefore, the appearance of the metal plate can be favorably maintained. Further, by curing the structural adhesive under the above conditions, sufficient adhesive strength can be obtained, and
Since the adhesive agent is interposed between the metal plates, the vibration damping property can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an arrangement of metal plates, electrodes and the like for executing a metal plate bonding method of the present invention.

FIG. 2 is a diagram showing a state after executing the metal plate bonding method of the present invention.

FIG. 3 is a diagram showing a state in which spot welding is being performed.

FIG. 4 is a diagram showing a state after spot welding.

[Explanation of symbols]

1 ... Electrode, 2 ... Metal plate, 3 ... Structural adhesive, 3a ... Adhesive part, 4 ... Welded part, 5 ... Spot dent.

Claims (3)

[Claims] 1. A volume resistivity between the adhered portions (3a) of two metal bodies (2) as adherends is in the range of 10 ⁰ to 10 ¹⁰ Ω · cm and in a thickness range of 5 μm to 200 μm. A certain conductive structural adhesive (3) is provided, and a current value in the range of 20% to 80% of the current value required for welding the metal bodies of the adherends is applied to the two metal bodies. A method for adhering a metal plate, characterized in that an electric current is applied between the parts, and the structural adhesive is cured by heat generation of the metallic body due to the electric current. 2. The method for adhering a metal plate according to claim 1, wherein the energizing time is in the range of 0.01 seconds to 1 minute. 3. In the state in which the electricity is supplied, the two metal bodies are pressed so that the adhesive portion is pressed, and are provided between the adhesive portions of the two metal bodies in the pressurized state. The method for adhering a metal plate according to claim 1, wherein the structural adhesive is present in the thickness range of 5 μm to 200 μm.