JPH0219754B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for joining resin-laminated steel plates by butt arc welding. In recent years, measures to reduce noise from many noise-generating machines, such as transportation machines and metal processing machines, have become a major issue. Such countermeasures should be taken from both the structure and constituent materials of the noise generator, and resin-laminated steel sheets, generally called vibration-damping laminated steel sheets, are an advantageous material from the latter point of view. A vibration-damping laminated steel plate is a composite steel plate in which a viscoelastic resin material is sandwiched between two steel plates.The strength of the material is provided by the steel plate, and the sound damping effect is provided by the intermediate viscoelastic material. It should be done in The sound reduction effect of vibration damping laminated steel plates is mainly related to the absorption of solid sound when the structure itself using the plate is the sound source, and is the most effective noise countermeasure. Moreover, the viscoelastic material that makes up the vibration-damping laminated steel plate is a very thin layer compared to the constituent steel plates, and can generally be treated in the same way as a normal steel plate, so this laminated steel plate can be applied to a wide range of fields. It is something. However, even though the viscoelastic layer of the damping laminated steel plate is very thin, its physical properties are very different from those of the steel plate, so some care is required when processing it. That is, since a viscoelastic body is normally an electrical insulator, when performing resistance spot welding in assembling a structure, a special method such as the film control method specified in the Japanese Welding Association standard WES7301 must be used. Furthermore, it is known from Japanese Patent Application Laid-Open No. 133000/1983 that there are problems with the state of the end surface during cutting depending on the application. As in these examples, there may be cases where conventional techniques cannot be used due to processing technology. There are many uses for vibration-damping laminated steel sheets, but continuous welding is often essential, such as in oil pans among automobile parts. An oil pan is a part located directly below the cylinder of an automobile engine to store engine oil.Since the oil pan receives vibrations from above, it generates a lot of noise, so vibration-damping laminated steel plates are used to reduce noise. Extremely effective. However, when joining members during assembly, airtightness and high strength are required of the joining joint. For this reason, when conventional steel plates were used, arc welding was used. The type of welded joint in this case is generally a butt joint or a lap fillet joint. However, when vibration-damping laminated steel plates are used as members, continuous arc welding becomes extremely difficult. This is because viscoelastic materials are generally organic substances and are electrical insulators, and at high temperatures such as those used in arc welding, gases mainly composed of _CO2 are generated due to evaporation and thermal decomposition. This is because it is difficult to continue the arc phenomenon. In order to solve the above-mentioned arc welding problems, the present inventor discovered that applying welding heat directly to the end face of a laminated steel plate is effective for stable arc generation. I devised a method as shown. That is, a metal plate 3 is interposed between the laminate members 1 and 2 as a joint, and the members 1 and 2 and the metal plate 3 are overlapped and fillet welded 4, respectively. Although this method enabled stable welding, it had the following practical drawbacks. This is because two welding beats are required instead of one when a normal metal plate is used, increasing the number of man-hours and welding costs. Therefore, in the present invention, a method has been studied that allows welding with one beat. That is, the purpose of the present invention is to reduce the thickness of the constituent steel plates.
Less than 2.3mm, the thickness of the intermediate resin material is 0.05~0.6
The object of the present invention is to provide a butt arc welding method in which resin-laminated steel plates in the range of The objective is to present the conditions under which butt welding can be performed. In addition, in the resin-laminated steel sheet that is the object of the present invention, if the thickness of the resin material is less than 0.05 mm, vibration damping performance etc. cannot be maintained, and if the thickness exceeds 0.6 mm, there will be problems with bending work, weldability, etc. This is because it is rarely used for practical purposes. By the way, a method of welding between laminated members using a single bead is disclosed in the above-mentioned patent application filed in 1983.
The following two points stated in No. 110217 give important suggestions. That is, firstly, the fact that butt welding of laminate members having a gap of a certain value was possible, and secondly, in the joining relationship shown in FIG. In that case, it is possible that it could be welded with a single beat as a backing butt joint. If the former is applied directly, depending on the size of the gap, it is expected that the weld metal will burn through.
To prevent this, a backing plate is required. This results in the second method. Therefore, in order to explore the conditions for implementing butt welding in the present invention, the following butt welding with backing was tested and the results shown in Table 1 were obtained. Here, the test material used was a vibration-damping laminated steel plate with a viscoelastic resin of 0.15 mm thick between two mild steel plates of equal thickness, the welding method was consumable electrode gas shielded arc welding, and the shielding gas was
A mixed gas of Ar and CO ₂ containing 20% CO ₂ and a welding wire diameter of 0.9 mm were used.

【table】

[Table] The relationship between welding joints and welding torches is shown in Figures 2 and 3. In these figures, 1,
2 is a vibration damping laminated steel plate as a test material, 4 is a welding bead, 5 is a resin, 6 is a backing plate of the steel plate, 7 is a welding torch, 8 is a shield cup, g is a groove gap, θ
is the torch angle, and l is the distance between the torch and the base metal.
Moreover, the arrow points in the direction of welding progress. In the test results shown in Table 1, all welding failures were due to instability of the arc, making it difficult to maintain welding. These results revealed that backing welding is extremely dependent on welding conditions and is only possible under very special conditions. Next, we will observe welding phenomena in detail, examine the effects of the above welding conditions on welding, and consider the basic requirements for making actual welding possible. That is, as a result of observation, the main cause of welding defects is that the resin 5 near the welding bead 4 decomposes due to welding heat and generates gas, which is mixed into the shielding gas provided by the welding torch 7. The arc is maintained by the flow of current in the arc plasma, but the current flows to a position where it obtains a path that does less work, that is, a lower arc voltage, and an arc is generated there. It depends on the distance l between the electrode and the base material and the shielding gas composition. Therefore, if the decomposition gas of resin 5 mixes into the shielding gas near the arc generation point on the steel, and local fluctuations occur in the shielding gas composition, the fluctuations will occur due to the characteristics of the arc itself, and the arc generation point will become irregular. Movement or arc extinguishment may occur, resulting in instability of the arc. Therefore, in order to stabilize the arc, it is necessary to eliminate the decomposed gas near the arc generation point. Based on the above considerations, the reason why it is better for the torch angle θ to be smaller than 90 degrees (advance angle) as a condition for obtaining good welding is because the shield gas eliminates decomposed gas in the welding direction, that is, in front of the arc generation point. Therefore, the shorter the distance l between the torch and the base metal, the better the shielding gas flow rate is because the flow rate of the shielding gas near the arc generation point increases and promotes the removal of decomposed gas. It has become clear that the gap g is necessary to provide a passage for the removal of cracked gases. Among the conditions for obtaining stable welding, the torch angle, distance between the torch and the base metal, and the shielding gas flow rate must be determined as necessary to eliminate decomposed gas, but the interdependence of these three and the welding speed must be determined. However, it cannot be set to a specific value because it is related to welding current, plate thickness, operator skill, etc. However, it is considered that the torch angle should be at least at an angle smaller than 90 degrees and tilted backwards with respect to the direction of welding progress. On the other hand, the necessity of a groove gap is the most basic requirement for carrying out this welding in that it provides a drainage path for cracked gas. Based on the above principle, this welding can be applied to any of consumable electrode gas shielded arc welding, non-consumable gas shielded arc welding, and shielded arc welding, but since the groove gap requires arc generation within the gap. , the diameter of the welding wire or core wire of the welding rod must be greater than or equal to the diameter of the welding wire, and generally 0.8 mm or more. Furthermore, if the groove gap is 5 mm or more, welding efficiency will decrease, so it is desirable that the groove gap be 5 mm or less. It is also possible to use a steel plate for the backing and join it together with the laminated steel plate, or it is also possible to use a copper plate to ensure only the formation of the back beat.
In these cases, the backing is used to prevent burn-through, but if the groove gap is small and is within 1.5 times the total thickness of the laminated steel plate, burn-through will not occur and welding can be performed without using the backing. is possible, but it is necessary to prevent the gap from expanding due to thermal strain during welding. Therefore, if a steel plate that is shorter than the weld length is used as a backing and is tack welded intermittently so that the groove gap remains constant, the welding will be repeated with and without the backing, but the welding will continue. itself becomes possible. Next, Figure 4 shows the case where the above results are applied to a container such as an oil pan. Figure 4a shows the case with continuous lining, and Figure 4b shows the case with intermittent lining. It shows. In these figures, 1 and 2 are vibration damping laminated steel plates, 4 is a weld bead, and 6 is a backing plate. As a result of experiments, it was found that the above welding can be performed more stably than overlap welding, and it was confirmed that it can be applied to cases where the thickness of the constituent steel plates of laminated steel plates is 2.3 mm.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a lap fillet welded joint of resin-laminated steel plates, Fig. 2 is an explanatory diagram of an experimental example to find the conditions for butt welding by the method of the present invention, and Fig. 3
The figure is a central sectional view of FIG. 2, and FIG. 4 is an explanatory diagram showing application to an oil pan. 1, 2: Vibration-damping laminated steel plate, 6: Backing plate,
7: Welding torch.

Claims (1)

[Claims] 1 A thickness of 0.05 mm between two steel plates with a thickness of 2.3 mm or less
When joining laminated steel plates sandwiching a resin material of mm to 0.6 mm to each other by arc welding, a gap of 0.8 mm to 5 mm is provided between the laminated steel plates, and a backing plate is used to move the welding torch in the direction of welding progress. against 90
A method for joining resin laminate members, characterized in that the laminated steel plates are butt welded while the laminated steel plates are tilted backward at an angle smaller than 50° to eliminate gas generated by decomposition of the resin substance forward in the direction of welding progress.