JPH05285669A - Method for joining plate materials - Google Patents

Abstract

PURPOSE:To firmly join plate materials by forming beforehand projecting parts at the position to be joined on one sheet between the two plates to be joined, applying an adhesive on at least one sheet of the joining surface, piling the two sheets and executing projection welding. CONSTITUTION:Plural projecting parts 4 are formed on the surface of the plate 1 to be joined and the adhesive 5 is applied on the joining surface of at least one sheet between the two plates 1, 2. Two sheets of the plates 1, 2 are piled and clamped by flat electrodes 6, 7 in a welder, and is energized after pressurizing by the welded. By pressurizing preceding the energization, the projecting parts break the film of the adhesive and are smoothly energized, and at the time of welding, the projecting parts are melted and crushed to promote spreading of the adhesive.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention utilizes projection welding instead of spot welding normally used in weld bond welding, and can be used with an adhesive containing no conductive material, for example. The present invention relates to a method for joining and fixing plate materials (hereinafter, simply referred to as joining).

[0002]

2. Description of the Related Art Conventionally, as an applied technology of spot welding,
There is known so-called weld bond welding, in which an adhesive is applied in advance to the welded portions of the joined plates and spot welding is performed. Research on this weld bond welding technology has already been made by academic societies, and it has also been put to practical use in the automotive industry.

[0003]

However, the technical data relating to the weld bond welding obtained in the past is as follows.
It is predominantly applied in aeronautical engineering, and it was speculated that its use in designing, for example, in the production of automobile bodies would be problematic. Therefore, the weld bond welding and the spot welding were compared by experiments with respect to strength and other items. In particular, we examined how much the weld bond weld's bond contributes to the overall bond strength, and found that the bond around the spot weld of the welded plate makes little contribution to the overall weld strength. Was done. The cause of this is that the adhesive burns during spot welding and a considerable amount of gas is generated by it, and the adhesive layer becomes extremely thin due to the concentrated pressurization by the electrodes, and the adhesive strength around the spot weld is extremely high. This is because it will decrease. In addition, the thickness of the adhesive portion changed greatly from the spot-welded portion to the outside, that is, the sheet separation (plate lapping) was large. Also, the indentation of the plate surface due to the electrode, that is, indentation (the indentation due to the electrode on the weld surface)
However, the surface of this plate could not be used as an outer surface in practice.

The adhesive has a diameter of 0.
A mixture of aluminum of about 1 mm and a diameter of 0.
Comparing with the one mixed with iron of about 01 mm, in the adhesive mixed with iron, there is a range of the electrode pressing force that cannot energize, and the kind of the conductive material mixed in the adhesive is different in the weld bond welding. It was clarified that the conductivity at the initial stage of energization is significantly affected and the proper welding range is affected. Furthermore,
Among these conductive adhesives, even if the thickness of the plate to be joined and the shape of the electrode tip change, the influence on the proper welding range is large, and this is a problem regarding the elimination of the adhesive directly under the electrode. Became a relief.

[Means for Solving the Problems]

In the present invention, as a result of intensive studies on the above problems, it was found that most of the above problems can be solved by using projection welding instead of spot welding in weld bond welding, and the present invention has been accomplished.

The above object of the present invention is solved by the following method. That is, a protrusion protruding toward the other joined plate is formed on the surface of the welded portion of one of the joined plates, and after applying an adhesive to at least one of the joined plates, the joined plates are overlaid on each other. In addition, a method of joining plate members is used, in which pressure is applied between electrodes by welding between welded portions provided with the protrusions. It is also adopted to use an adhesive containing no conductive material as the adhesive.

[0007]

The welding according to the present invention is carried out as follows. First, a protrusion is formed in advance on the surface of one plate to be bonded toward the other plate to be bonded, and an arbitrary adhesive is applied to the surface of any plate to be bonded. Then, the plates to be joined are overlapped with each other, and a flat electrode is pressed between the joined parts to energize them. A concentrated load is applied to the tip of the protrusion due to the pressure applied by the flat electrode, and the protrusion is crushed, but the adhesive applied to the tip of the protrusion previously applied is removed. As a result, the adhesive at the tip of the protrusion does not exist and the surface is exposed, so that the current flow is smooth and welding begins between the other plate to be joined. Therefore, the welding according to the present invention is not affected by the type of adhesive or the physical properties of the conductive material or the like mixed therein. The pressurization by the flat electrode is also intended to remove the adhesive from the tip portions of the protrusions and to promote the spreading of the adhesive applied to the joined plates which are superposed on each other around the joint. As the pressing and energization by the flat electrode progresses, the protrusion is almost crushed, and at the same time, the other plate to be joined is welded, and the adhesive that has spread between the plates to be joined is bonded by the subsequent curing treatment. To form a part. As described above, the present invention utilizes projection welding to simultaneously apply pressure and current to the bonded parts of the plates to be bonded by the flat electrode, and remove the adhesive from the projection tips by pressurization to ensure good current flow. None,
Further, when pressure is applied and electricity is applied, the tip of the protrusion is melted and welded to the other plate to be joined, and further the extension of the adhesive between the plates to be joined is promoted around the joint. As a result, even when various adhesives are applied, there is no non-energizable area at the joint, and it is possible to use adhesives that do not contain conductive substances, for example, and the degree of freedom in adhesive development is great. Become. Further, since the indentation by the electrode is small and the spread state of the adhesive is constant, the thickness of the adhesive can be made uniform and the sheet separation is small. Furthermore, according to this method, the amount of gas generated around the joint is small, and the strength of the adhesive around the joint contributes to the overall welding strength.

[0008]

The details of the present invention will be described with reference to the embodiments shown in the drawings. FIG. 1 is a principle view showing a method of joining plate materials according to the present invention. A is a plate material joining apparatus according to the present invention. Reference numerals 1 and 2 shown in FIG. 1 denote plates to be joined. A portion to be pressed and energized by the electrodes with respect to the plates to be joined 1 and 2 before being welded is a joining portion 3. A plurality of protrusions 4 and 4 are formed on the surface of one plate to be bonded 1 between the bonding parts 3 so as to project toward the other plate to be bonded 2. An adhesive agent 5 is applied to the bonded plates 2. The plates 1 and 2 to be bonded having the above-mentioned configuration are superposed on each other,
The electrodes 6 and 7 pressurize and conduct electricity between the joints 3 provided with the protrusions 4 and 4. The materials of the plates 1 and 2 to be joined include mild steel plates of any plate thickness, high-tensile steel plates, corrosion-resistant coated steel plates,
Alternatively, an aluminum alloy material or the like is used. The protrusions 4 and 4 are provided in advance on the plate 1 to be joined by punch press equipment. Although a one-component thermosetting epoxy adhesive is used as the adhesive 5, the type of the adhesive 5 is not restricted by the joining method according to the present invention. Further, the adhesive 5 may be applied to the bonded plate 1 provided with the protrusions 4 and 4. It is preferable to use flat electrodes for the electrodes 6 and 7. In the welding of the plates 1 and 2 to be joined by resistance heat as in the present invention, a transformer having a large winding ratio is used as the transformer 8 in order to use a power source of low voltage and large current. As the pressure device, a conventionally used spot welding pressure device is used (not shown).

The welding by the joining method of the present invention as described above is performed as follows. First, the projections 4 are previously formed on the surface of the one plate 1 to be bonded toward the other plate 2 to be bonded.
4 is formed, and an optional adhesive 5 is applied to the bonded plate 2. Then, the plates 1 and 2 to be bonded are overlapped with each other, and the flat electrodes 6 and 7 pressurize the space between the bonded parts 3 and energize them. A concentrated load is applied to the tips of the projections 4 and 4 due to the pressure applied by the pressure device, and the projections 4 and 4 are crushed, but the tip portions of the projections 4 and 4 applied in advance before that are to be joined. Remove the adhesive 5 on the plate 2. As a result, no adhesive is present at the tips of the projections 4 and 4, the surface is exposed, the current is made smooth, and welding is started between the other plate 2 to be joined. Even if the adhesive 4 is applied to the bonded plate 1 provided with the protrusions 4 and 4, the bonded plates 1 and 2 are overlapped and pressed, so that the adhesive 5 is eliminated by the protrusions 4 and 4. Therefore, the energization is not disturbed at all. That is, the welding according to the present invention is not affected by the kind of the adhesive or the physical properties of the conductive material mixed therein, so that the adhesive can be freely designed. The pressure applied by the flat electrodes 6 and 7 is to remove the adhesive 5 from the tips of the protrusions 4 and 4 and to spread the adhesive applied to the bonded plates 1 and 2 that are overlapped around the bonding part 3. It also aims to promote. As the pressurization and energization by the flat electrodes 6 and 7 proceed, the protrusions 4 and 4 are almost crushed, and at the same time, they are welded to the other plate 2 to be joined. Further, the adhesive 5 that has been expanded by performing a curing treatment later forms an adhesive portion.

An embodiment of the present invention will be described below based on data obtained by experiments. The plates to be bonded used in the experiment were SPCC mild steel plates having a plate thickness of 0.8 mm and 1.6 mm and having an oil surface and an acetone degreased surface, and a plate thickness of 0.8.
There are two types of galvannealed steel sheets with an oil surface of mm. As the electrode, a DR type tip diameter of 6.0 mm was used for weld bond welding and spot welding, and a flat type chromium copper alloy having a tip diameter of 16 mm was used for the present invention. As the adhesive, a one-part thermosetting epoxy adhesive containing an iron-based conductive metal having an average diameter of 0.01 mm was used, and the curing condition was maintained at 170 ° C. for 20 minutes. When the plate thickness T is 0.8 mm, the projection D has a diameter D of 3.
2 mm, 5.0 mm, and 7.0 mm, with a diameter D of 5.0 mm and 7.0 mm when the plate thickness T is 1.6 mm,
Three types of 10.0 mm were examined. The height H of the protrusion is 0.1 to 0.5 m in the application range of the thickness of the adhesive applied.
On the assumption that the thickness is set to m, it is set to 0.4 mm regardless of the plate thickness T and the diameter D. Under these conditions, the welding method of the plate materials according to the present invention and the welding methods of weld bond welding and spot welding were compared. As the experimental data, SPCC mild steel sheet is disclosed.

From the growth process of the nugget diameter of the present invention, a nugget diameter d (plate thickness 0.8 mm, which is five times the square root of the plate thickness T).
4.5 mm and 6.3 mm for 1.6 mm respectively)
When the plate thickness is 0.8 mm, the diameter D of the protrusion is 5.0 mm, and when the plate thickness is 1.6 mm, D is 7.
It was determined that 0 mm was the optimum, and it was decided to use this D later. The welding lobes (curves showing the proper welding range) of welding and weld bond welding according to the present invention are shown in FIG. FIG. 2A shows the weld bond welding, and FIG. 2B shows the present invention. The vertical axis shows the electrode pressure (kN) and the horizontal axis shows the welding current (kA). In the figure, the range where the circle exists is the nugget generation possible area, and the circle is the scattering occurrence area. Comparing the appropriate welding ranges shown in the tables of FIG. 2 (the range from the minimum welding current value at which a nugget diameter of four times or more the square root of the plate thickness T is obtained to the scattering occurrence limit current value), the present invention is compared. 4 of square root of plate thickness T
The minimum welding current value that can obtain a double nugget diameter is 5.
The electrode pressure was 0.6 (kN) at 0 (kA), whereas the welding current value for weld bond welding was 6.
At 0 (kA), the electrode pressure is 1.6 (kN). From this result, it is understood that the present invention is capable of producing a good nugget with a low current and a low electrode pressure, and is superior to the conventional weld bond welding. The experimental conditions of the welding lobe shown in FIG. 2 are as follows: the thickness of the bonded plate is 0.8 mm, the squeeze time is 40 times, the energization time is 10 cycles, the hold time is 30 cycles, and the initial adhesive thickness is 0.15 mm. The temperature is 22 ° C and the humidity is 70%.

FIG. 3 compares the indentation of the present invention with the weld bond welding. This is the dented portion after the electrode bites into the surfaces of the plates to be joined due to the pressing force, and the magnitude of this indentation is also one of the decisions that determine the quality of the welded state. The vertical axis represents the indentation depth (mm) from the plate to be welded before welding, and the horizontal axis represents the distance (mm) from the center of the nugget.
The indentation of the present invention is shown by a solid line and that of weld bond welding is shown by a dotted line. From this result, it was found that the smoothness of the joint of the present invention was extremely good as compared with the conventional weld bond welding. Further, according to the present invention, since the indentation is small, the electrode itself is less likely to be welded to the plates to be joined, so that the electrode life is extended. In the indentation experiment shown in FIG. 3, the thickness of the plate to be joined is 0.8 mm, the collision speed of the upper electrode to the plate to be joined is 0.13 (meter / sec), and the electrode pressure is 2.0 kN.
In other cases, the other conditions are the same as those in FIG.

FIG. 4 compares sheet separation between the present invention and weld bond welding. This sheet separation represents a gap between the joined plates around the opposite joints after welding, and the adhered state of the joined plates around the joint is observed by this. The vertical axis represents the sheet separation (mm), and the horizontal axis represents the distance (mm) from the center of the nugget. The sheet separation of the present invention is shown by □, and the weld bond welding is shown by ◯. From this result, in the present invention, the value of the sheet separation hardly changes even at the position away from the center of the nugget, whereas in the weld bond welding, the value of the sheet separation increases as the distance from the center of the nugget increases. From this result, the adhesive portion is formed around the joint portion of the present invention so that the adhered state is constant, and the adhesive strength of the adhesive including the periphery of the joint portion contributes to the strength of the entire welding. Although not shown in the figure, it was observed from the above experiment that the amount of gas generated due to the burning of the adhesive during welding was smaller in the present invention than in the weld bond welding. The experimental conditions for the sheet separation shown in FIG. 4 are the same as those in FIG.

FIG. 5 compares the results of the static test under tensile shear load of the present invention and weld bond welding and spot welding. The vertical axis represents the load (kN), and the horizontal axis represents the grip distance (mm). From these results, it was found that the present invention has a static strength that is about 10% lower than that of weld bond welding. This decrease in static strength is due to the tensile load acting on the joint edges in this test method, and it has been found that the present invention is greater in the case of pure tensile shear load, and in any case When setting the strength of the part, it does not affect the welding strength as a whole. In the static test experiment shown in FIG. 5, the initial adhesive diameter was 7.0 mm in the present invention and 13.0 mm in the weld bond welding so that the nugget diameter was 4.5 mm and the adhesive portion diameters were both 22.0 mm. did. The initial adhesive was applied in a disk shape having the above diameter.

FIG. 6 compares the results of fatigue time strength under tensile shear loading for weld bond welding and spot welding of the present invention. Load range (k
N), and the horizontal axis represents the number of repetitions (N). The present invention is indicated by □, weld bond welding is indicated by ◯, and spot welding is indicated by Δ. From these results, the fatigue time strengths of the present invention and weld bond welding were almost the same. However, this is the result when the diameter of the bonded portion is almost the same between the weld bond welding and the present invention as in the case of FIG. 5, and when the same amount of adhesive is applied, the present invention is more adhesive. Is much larger than in weld bond welding, the diameter of the bonded portion is large, and as a result, the fatigue time strength is greater in the present invention. As the experimental conditions for fatigue time strength shown in FIG. 6, the bonded portion diameter was 22.0 mm, the stress ratio was 0.05 mm, and the repetition rate was 40 Hz.

[0016]

The effect of claim 1 of the present invention is to use the projection welding instead of the spot welding as in the conventional weld bond welding to apply pressure and current to the joints of the plates to be joined by the flat electrode. At the same time, the adhesive applied to the tips of the protrusions by pressure is removed to achieve good current flow, and the current is applied while pressure is applied, so the tip of the protrusion melts and welds to the other plate to be joined. In addition, it also promotes the extension and adhesion of the plates to be joined around the joint with the adhesive. As a result, even if various adhesives are applied, there is no non-energizable region at the joint. In addition, since the indentation by the electrode becomes small and the extension state of the adhesive is constant, the thickness of the adhesive can be made uniform, and when an equal amount of the adhesive is used, various strengths are improved. The strength of the adhesion portion around the joint portion of the projection welding has a remarkable effect of contributing to the overall welding strength.

According to the second aspect of the invention, an adhesive containing no conductive substance can be used, and the degree of freedom in developing the adhesive is increased, which is a remarkable effect.

[Brief description of drawings]

FIG. 1 is a simplified explanatory diagram showing the principle of the present invention.

FIG. 2 is a diagram showing experimental results of welding lobes in the present invention and a conventional example.

FIG. 3 is a diagram showing experimental results of indentation in the present invention and a conventional example.

FIG. 4 is a diagram showing an experiment result of sheet separation in the present invention and a conventional example.

FIG. 5 is a diagram showing experimental results of static strength under a tensile shear load of the present invention and a conventional example.

FIG. 6 is a diagram showing experimental results of fatigue time strength under tensile shear load of the present invention and a conventional example.

[Explanation of symbols]

 A Plate joining device 1 Joined plate 2 Joined plate 3 Joined portion 4 Protrusion 5 Adhesive 6 Electrode 7 Electrode 8 Transformer

Claims (2)

[Claims] 1. A welded surface of one of the plates to be joined,
While forming a protrusion protruding toward the other plate to be joined, after applying an adhesive to at least one of the plates to be joined, the plates to be joined are overlapped with each other, and an electrode is provided between the welded portions provided with the protrusions. A method for joining plate materials, which is characterized in that pressurization and energization are performed. 2. The method for joining plate materials according to claim 1, wherein an adhesive containing no conductive material is used as the adhesive.