JPH0236937A - Sandwich type resin composition metal plate and its resistance welding - Google Patents

Abstract

PURPOSE:To enable good welding to be easily performed by a same resistance welding method as that for an ordinary metal plate without causing abnormal heating by a method wherein an electrode of a specific electrode tip diameter is used as a spot electrode, and a welding current is supplied at a specific executive value under a constant electrode pressing force. CONSTITUTION:An electrode equivalent to that of 3.0 to 7.0 mmphi in electrode tip diameter is used as a spot electrode. Welding is performed under welding conditions of 150 to 400kg in electrode pressing force and 6000 to 15000 A in welding current. An abnormal phenomenon occurs for a period to 60m sec in initial resistance welding. At a welding point wherein no abnormality occurs for this period, normal welding can be performed even for further longer resistance welding time. When a resistance value between electrodes at initial resistance welding is 300muOMEGA or under, no abnormal phenomenon occures. Since the resistance between the electrodes for 10 to 60m sec in initial resistance welding is 50muOMEGA or over in resistance welding of a cold rolled steel sheet with no resin layer, this value is a lower limit.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a resin composite metal plate in which a resin layer is arranged between two metal plates (hereinafter referred to as the skin), and a method for resistance welding the same. In particular, the present invention relates to a technique for imparting good welding properties to resin composite metal plates.

(Prior Art) There are many examples of the use of resin composite metal plates for the purpose of vibration and soundproofing of metal plate structures. Also these in general! Processing and welding of RI structures are performed in the same steps as when using ordinary metal plates.

On the other hand, since the resin used in these resin composite metal plates has extremely high electrical resistance, the electrical resistance between the skin steel plates also increases, making it difficult to stably flow a sufficient welding current during resistance welding.

An example of the prior art will be explained with reference to FIG. A resin composite metal plate 1 and a normal metal plate 2 are spot welded using electrodes 3 and 4.
When welding by applying pressure, the resin layer 5 of the resin composite metal plate 1
Because of the high resistance value of the welding current, it is only possible to directly flow the welding current between the electrodes 3.4 via path A. Therefore, prior to welding, the resin composite metal plate 1 and the metal plate 2 are connected using a conductive member 6, and a current is first passed through path B. This current is applied to electrode 3
The epidermis directly below generates heat, and this heat softens the resin layer 5. Since pressure is applied directly below the electrode, the softened resin is discharged from directly below the electrode. When the high-resistance resin is discharged from directly below the electrode, the current that was flowing to path B flows to 1.8 A, and welding begins.

In such a conventional method, it is necessary to connect the vicinity of the welded part with a conductive member prior to welding, and furthermore, it takes a long time to start welding, reducing workability.

(Problem to be solved by the invention) Conventionally, resin composite metal plates can be welded using the same means and conditions as reverse-electrometal metal plates, in order to eliminate the special work required and the reduction in productivity. A resin composite metal plate was requested.

In order to achieve this purpose, there is a method of mixing conductor grains such as metal grains into a resin layer with high electrical resistance to give it conductivity.
For example, it has already been proposed in Japanese Patent Application Laid-Open No. 50-79920, but it is not possible to achieve sufficient effects simply by having electrical conductivity.

The welding result is greatly influenced by the electrical resistance value of the resin layer during the welding process. vJ1 with metal particles mixed into the resin layer
In spot welding of fat composite metal plates, the resistance value decreases due to pressure applied with an electrode prior to applying welding current. However, if the resistance value of the resin layer is high, it is difficult to uniformly reduce the resistance value of the part pressurized by the electrode, and there are parts of the pressurized part where the resistance value has decreased and parts where the resistance value has not decreased. There may be places where it remains high. As a result, the welding current that should normally flow throughout the pressurized portion concentrates on a portion with a low resistance value, causing abnormal heat generation in this portion. This abnormal heat generation may cause the surface metal to melt and adhere to the electrode, or in extreme cases, the molten skin metal may scatter due to the abnormal heat generation.

The present invention provides a resin composite metal plate that can be easily welded successfully using the same resistance welding method as that used for ordinary metal plates that cause such abnormal heat generation.

(Means for Solving the Problems) The present invention provides a sandwich-type resin composite metal plate in which conductive particles are mixed in a resin layer, and has an electrode tip diameter of 3.0 to 7. Using a material equivalent to O1 nmφ, with an electrode pressure of 150 to 400 kg and a welding current of eooo to 15,000 A being supplied at the actual value, the interelectrode resistance during the initial 10 to 60 n sec of energization is 50 to 300.
A sandwich-type resin composite metal plate characterized by μΩ and a resistance welding method characterized by using the same.

(Function) The inventors found that the above-mentioned abnormal phenomenon occurs concentratedly at the initial stage of welding current application as shown in Fig. It was found that there is a close relationship with interresistance.

The interelectrode resistance here is calculated by measuring the welding interelectrode voltage (V) and welding current (I) during spot welding, and dividing the former by the latter when the time change of ■ is O (di/dt・0). Defined by value (V/I).

FIG. 2 shows the results of an investigation into the relationship between the current application time and the occurrence of abnormal phenomena during spot welding of a resin composite metal plate in which the aforementioned metal powder and the like were mixed into the resin layer. However, as a spot electrode, use one with an electrode tip diameter equivalent to 3.0 to 7.0 mmφ, an electrode pressing force of 150 to 400 kg, and a welding current of 6.
Please investigate within the welding conditions of 000~15000A. According to this, the occurrence of the abnormal phenomenon occurs at the initial stage of reverse charging, at 60 E sec.
At welding points where no abnormality occurs during this period, piezoelectric welding can be performed even with a longer energization time.

Figure 3 shows the initial stage 1 of 3ffi electricity, which appears to be an abnormal phenomenon or occurs concentratedly.
The relationship between the inter-electrode resistance and the rate of occurrence of abnormal phenomena from 0 to 60 seconds is shown. However, use a spot electrode with an electrode tip diameter of 3.0 to 7.0 mφ, electrode pressure of 150 to 400 kg, '/11 contact current of 6000 to 1
The investigation was conducted under welding conditions of 5000A. This result shows that normal spot welding without any abnormal phenomenon is possible if the interelectrode resistance value at the initial stage of energization is 300 μΩ or less. On the other hand, in resistance welding of cold-rolled steel sheets without a resin layer, the interelectrode resistance at the initial energization period of 10 to 60 ISec is 50 μΩ or more, so this value should be taken as the lower limit.

(Example) In spot welding, a resin composite metal plate with different interelectrode resistance values and a regular metal plate were stacked and spot welded, and the maximum resistance value and the occurrence of welding abnormality during the initial energization period of 10 to 60 nSec were observed. I looked at the situation.

Combination of metal plates: Lap welding of resin composite metal plates (plate thickness 0.81 skin steel plate f$ 0.4rnr+) and mild steel plates (plate thickness 0.81'1lI11>-) Method: Resistance welding ( Spot welding) Electrode tip diameter: 4.5mlφ Welding current = 8 to 8 Pressure = 200 to q Total energization time + 200m sec Even with the results shown in Table 1 of Table 1 Judgment Results 2, the inter-electrode resistance was 50 to 300μ
In the case of Ω (good welding was possible at all welding points without any abnormal phenomena occurring.On the other hand, the interelectrode resistance was 350 μΩ
In the above cases, it is recognized that an abnormal phenomenon has occurred, and the higher the resistance between the electrodes, the higher the occurrence rate of the abnormal phenomenon. Further, the period during which this abnormal phenomenon occurs is concentrated between 10 and 60 nSec from the start of energization.

(Effect of the invention) Initial energization time in spot welding: 10 to 60 msec,
A resin composite metal plate with an interelectrode resistance of 300μΩ or less,
It is possible to weld in the same way as ordinary metal plates, and the excellent performance of this resin composite metal plate can be easily applied to metal plates.
! II4 It is possible to use it as a relic.

[Brief explanation of the drawing]

Figure 1 is a schematic side view explaining the conventional welding method for resin composite metal plates, Figure 2 is a graph showing the relationship between energization time and welding abnormality occurrence rate, and Figure 3 is a graph showing the relationship between electrode resistance value and welding abnormality occurrence rate. It is a graph showing the relationship. 1...Resin composite metal plate with high resistance value of resin layer, 2...
・Normal metal plates, 3 and 4... Spot welding electrodes, 5
... Resin layer, 8... Conductive member, A and B... Current path agent Patent attorney Masanobu Akisawa 1 person

Claims (2)

[Claims] (1) In a sandwich-type resin composite metal plate in which conductor particles are mixed in a resin layer, a spot electrode with an electrode tip diameter equivalent to 3.0 to 7.0 mmφ is used, and an electrode pressing force of 150 to 400 kg is used. and the actual value of welding current is 60
With 00 to 15000A supplied, the initial energization time is 10 to 6.
A sandwich-type resin composite metal plate having an inter-electrode resistance of 50 to 300 μΩ for 0 msec. (2) In a spot welding method for a sandwich-type resin composite metal plate in which conductive particles are mixed in a resin layer, a spot electrode with an electrode tip diameter equivalent to 3.0 to 7.0 mmφ is used, and an electrode pressing force of 150 mm is used. When the welding current is supplied at an actual value of 6,000 to 15,000 A under ~400 kg, the interelectrode resistance during the initial 10 to 60 msec of energization is 50 to 50.
A method of resistance welding a sandwich-type resin composite metal plate, characterized in that a sandwich-type resin composite metal plate having a resistance of 300 μΩ is used.