JPS6199585A - Structure and method for joining aluminum plated steel plate - Google Patents

Abstract

PURPOSE:To join solidly with Al plated layer without melting Al plated steel plate each other by insertion Al-Si alloy between both Al plated steel plates and by electrifying with pressing by the electrode fitting the exothermic plate having large electric resistance in case of joining Al plated steel plates each other. CONSTITUTION:The foil, powder or paste like substance 3 of Al-Si alloy of <20% Si is interleaved between both steel plates 1, 2 and electrified with pressing by the electrodes 6, 7 fitting the exothermic plates 4, 5 having large electric resistance on its tip in case of joining by a resistance heating the steel plates 1, 2 having Al plated layers 1a, 2a at both sides. The Si in the Al-Si alloy causes an eutectic reaction with the plated Al by the high temp. heating due to the electrification and produces an eutectic melting state, by the freezing with colling of which the mutual steel plate are strongly joined.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to the joining of aluminum-plated steel plates, and in particular, to the joining of aluminum-plated steel plates, in particular, a method of forming an Al-Si eutectic molten phase on the joint surface by resistance heating without melting the steel plate portions. It relates to a structure or a method of joining.

[Background of the invention]

Conventionally, for joining aluminum plated steel sheets,
Spot g welding using a resistance welder is mainly used, but joining is extremely difficult and has the following drawbacks.

(1) Welding involves creating molten nuggets on the steel plate parts to join them, which requires high temperatures and can damage the aluminum plated parts.In order to maintain corrosion resistance, the plated parts of traps must be repainted. .

(2) Since high temperatures are required during welding, a eutectic reaction occurs between the aluminum plating and the copper electrode, requiring frequent repair of the electrode.

6) As with general spot bath welding, indentations and distortions due to melting of the steel plate cannot be avoided.

[Purpose of the invention]

An object of the present invention is to provide a joining structure and method for joining aluminum-plated steel plates, which provides strength greater than spot welding, does not damage the aluminum-plated parts, does not cause indentations or distortions, and has less wear on electrodes. In particular, [Summary of the Invention] The present invention focuses on the fact that the aluminum of an aluminized steel sheet and the steel sheet are strongly bonded, and the present invention is directed to a method of melting the steel sheets by strongly bonding the aluminum plating layers to each other. The aim is to achieve strong bonding through aluminum without causing any damage.

That is, the joint part GCSij of the aluminum plating layer
By applying flow pressure while contacting a hypereutectic Al-Si alloy foil with a high content and applying a resistance of 7JO4, eutectic melting occurs only on the surface, and the oxidation of the aluminum that covers the surface and hinders bonding is caused. In this case, the coating is destroyed and dispersed in the melt, and the aluminum plated surfaces are strongly wetted and pressure-bonded without flux. In this case, the current concentrates on the part that was melted first, causing unevenness and zero heat. To prevent this from occurring, it is even more effective to attach a heat generating plate with high electrical resistance to the tip of the electrode to ensure uniform heating. Further, it can also have the effect of preventing eutectic fusion of the copper electrode and the aluminum plating film at a temperature lower than the eutectic temperature of the heating plate tdAl-Si.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Figure 1 shows an example of joining aluminum steel plates in the simplest form, with an Al-di foil 6
T scissors, upper and lower electrodes 6, 7 with heating plates 4, 5 attached to the tips
This figure shows the state in which electrical heating is being performed. The Al-Si foil undergoes a eutectic reaction with the aluminum in contact with the Si in the Al-Si due to resistance heating by electricity and heat conduction from the heating plate, producing a eutectic molten phase, and through this, the steel plate is heated. They are joined together.

Al-Si foil is a hypereutectic Al-Si alloy with a Si content of 20% or more.The higher the Si content, the faster the eutectic reaction with aluminum progresses and the better the bonding properties. Depending on the situation, a Si content at the eutectic point can also be used for Q'1.

By attaching a heat generating plate to the tip of the electrode, it is possible to prevent the current from concentrating on the previously melted part, and the feature is that high heat can be obtained with a relatively low current. Without a hot plate, eutectic melting occurs between copper and aluminum at relatively low temperatures, which can shorten electrode life.

In the example shown in Fig. 1, a steel plate with a thickness of 0.8 m has a diameter of 8 mm on one side.
0P/rr? 5 aluminum plated
As a result of resistance welding by sandwiching 160 inch B-Sr thin foil with an area of 7 x m, the tensile shear strength was 71 under the conditions of a current value of 24 KA, a pressing force of 500 + 5, and a current conduction time of 30 Hz.
I was able to obtain 0Kp. This value greatly exceeds 4, which is the spot welding strength of 400 under A class conditions for resistance welding without plating, which is the easiest resistance welding.

The spot welding strength between aluminum plated steel plates of the same thickness is said to be 250Kp. Although the applied force of 1% current in this experimental value is large, by lowering the applied force, a bond of similar strength can be obtained with a lower current value. In this experiment, an electrode with a flat contact surface was used, but no indentation, strain, or damage to the aluminum plated portion was observed. Tool steel was used for the resistance plate.

As for the Al-Sr alloy sandwiched between the two, the same effect can be obtained by using a powder, a powder made into a paste, etc., instead of a foil.

〔Effect of the invention〕

According to the present invention, it is possible to join aluminum-plated steel sheets together, which has been extremely difficult in the past, with the same ease as spot welding, and with greater strength than spot welding, without damaging the joints of plated parts and without causing indentations or distortion. Since this is a joining structure or method that can be used without the need for aluminized steel sheets, the range of applications for aluminum-plated steel sheets can be greatly expanded, and the industrial effect is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part explaining one embodiment of the present invention. 1.2...Aluminium-plated steel plate, 1a, 2a...
・Aluminum plating, 3...Al-Si alloy,
4.5... Heat generating plate, 6,7... Upper and lower electrodes, 8...
Aj-S i eutectic phase. Yl Threshold 2 Illustration Procedure Amendment (Method) Amendment Sound I Rumor and 1 Protection Patent Applicant 1, Todo 51) Yukishiki t≧1 Hitachi
Manufacturer's cost and human compensation. Target A column for a brief description of the drawings in the specification.

Claims (1)

[Scope of Claims] 1. A joining structure for aluminum-plated steel sheets, characterized in that a eutectic phase of Si and Al is present at the joint between the aluminum-plated steel sheets. 2. A resistance welder is used to join aluminum-plated steel plates, an Al-Si alloy is sandwiched between the joints, the area is energized and pressurized with upper and lower electrodes, and Al-S is heated by resistance heating.
A method for joining aluminum-plated steel sheets, characterized in that the joining is performed by forming a eutectic melt phase with aluminum of the aluminum-plated steel sheets in contact with the i-alloy. 3. The method for joining aluminum-plated steel sheets according to claim 2, in which a heating plate with high electrical resistance is attached to the tip of the electrode, and heating by heat conduction from the heating plate is used in combination with resistance heating during electrical heating. 4. The method for joining aluminum-plated steel sheets according to claim 2, wherein the Al-Si alloy is in the form of foil, powder, or paste.