Arc welding method and method for inspecting welding strength of joined body welded by arc welding method

Abstract

This arc welding method is an arc welding method in which at least a portion of a workpiece formed by overlapping a plurality of non-ferrous metal plates is melted and joined. Furthermore, the workpiece has, at the welding site, a machining hole which penetrates through the non-ferrous metal plate on the arc irradiation side, reaches the non-ferrous metal plate on the farthest side from the arc welder, and is a non-through hole in which a portion of the non-ferrous metal plate on the farthest side is recessed, and an arc is irradiated from the opening side of the machining hole. And welding by melting the workpiece on the side opposite to the opening side to the back surface of the non-ferrous metal plate on the farthest side without using a back pad jig, thereby providing an arc welding method in which welding can be performed without using a back pad jig, and even if the space on the back surface side of the workpiece is limited, the welding can be performed without using a back pad jig. And welding can also be carried out.

Description

Technical Field

[0001] The present invention relates to an arc welding method and a method for inspecting the welding strength of a joined body welded by the arc welding method. More specifically, the present invention relates to an arc welding method for joining non-ferrous metal plates to each other and a method for inspecting the welding strength of a joined body welded by the arc welding method. Background Art

[0002] There is known an arc spot welding method as follows: when joining a plurality of plates by welding, a processing hole is formed in the plate on the arc welding machine side of the workpiece formed by overlapping the plates, and joining is performed by wire feed type arc spot welding.

[0003] Patent Document 1 describes the following: in the case of performing arc spot welding by melting the inner wall of the processing hole formed in the above-mentioned plate, the melting depth of the lower plate becomes deeper and burn-through occurs. Therefore, a back-up tool (Japanese: 裏当て器具) is brought into contact with the lower plate.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Laid-Open No. 06-039542 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in an actual production site, there are cases where the shape of the workpiece and the space on the back side of the workpiece are limited, and it is mostly impossible to use a back-up tool.

[0009] The present invention has been made in view of the problems of such prior art, and an object thereof is to provide an arc welding method that can perform arc spot welding without a back-up jig even when the space on the back side of the workpiece is limited.

[0010] Means for Solving the Problems

[0011] The inventors of the present invention repeatedly conducted in-depth research to achieve the above object, and as a result, found the following means and completed the present invention: a processing hole is formed that not only penetrates the plate on the arc welding machine side but also reaches the plate farthest from the arc welding machine, thereby achieving the above object.

[0012] That is, the arc welding method of the present invention is an arc welding method for joining by at least partially melting a workpiece formed by overlapping a plurality of non-ferrous metal plates.

[0013] Furthermore, the feature is that the workpiece has a processed hole at the welding position, and the processed hole is a non-through hole that penetrates the non-ferrous metal plate on the arc irradiation side and reaches the non-ferrous metal plate on the side farthest from the arc welding machine, and causes a part of the non-ferrous metal plate on the farthest side to be recessed, and the arc is irradiated from the opening side of the processed hole, and welding is performed by melting to the back side of the non-ferrous metal plate on the farthest side on the side of the workpiece opposite to the opening side without using a backing jig.

[0014] Furthermore, the welding strength inspection method of the present invention is a method of inspecting the welding strength of a joined body welded by arc welding.

[0015] Furthermore, the welding strength is estimated from the diameter of the molten zone formed on the back surface of the non-ferrous metal plate at the farthest side.

[0016] Effects of the Invention

[0017] According to the present invention, by forming a processing hole that is formed not only on the plate on the arc welding machine side but also reaches the plate farthest from the arc welding machine, it is possible to provide the following arc welding method: welding can be performed without using a backing device, and welding can be performed even when the space on the back side of the workpiece is limited. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a cross-sectional view of the main parts for explaining the arc welding method of the present invention.

[0019] Figure 2 This is a cross-sectional view of a main part of a joined body welded by the arc welding method of the present invention.

[0020] Figure 3 This is a graph showing the relationship between the plate thickness of the processed hole forming portion of the non-ferrous metal plate on the side farthest from the arc welding machine and the presence or absence of burn-through at the joint portion when the processed hole diameter is 4 mm.

[0021] Figure 4 This is a graph showing the relationship between the plate thickness of the processed hole forming portion of the non-ferrous metal plate on the side farthest from the arc welding machine and the presence or absence of burn-through at the joint portion when the processed hole diameter is 8 mm.

[0022] Figure 5 This is a graph showing the relationship between the processed hole diameter and the strength of the fusion zone formed in the bonded body.

[0023] Figure 6 This is a graph showing the relationship between the tensile strength of a joint body and the diameter of a molten zone that appears on the back surface of the non-ferrous metal plate on the side farthest from the arc welder. DETAILED DESCRIPTION

[0024] The arc welding method of the present invention will be described in detail.

[0025] The arc welding method of the present invention is a welding method for joining a plurality of overlapping non-ferrous metal plates to each other by melting at least a portion of the workpiece using an arc.

[0026] The workpiece 2 formed by overlapping a plurality of non-ferrous metal plates is preliminarily provided with a processing hole 21 at the welding position. Figure 1 As shown, the processed hole is a non-through hole that penetrates the entire non-ferrous metal plate 3 (hereinafter sometimes referred to as the "front side plate") that is arranged at a position closer to the welding machine side than the non-ferrous metal plate 4 (hereinafter sometimes referred to as the "back plate") that is farthest from the arc welding machine 1, reaches the back plate 4, and causes a part of the back plate 4 to be recessed.

[0027] Furthermore, the welding torch is rotated to irradiate the arc while aiming at the inner circumference of the processing hole 21 from the opening side of the processing hole 21, so that the inner circumference of the processing hole 21 is melted together with the welding wire. At the same time, the bottom surface of the processing hole 21 is melted. Once it is melted to the back side of the back plate 4, the arc irradiation is stopped and solidification is performed, thereby joining the overlapping multiple non-ferrous metal plates to each other.

[0028] In addition, the number of the front side plates 3 is not limited to one, and a plurality of them may be stacked.

[0029] The arc welding method of the present invention forms a recessed processing hole in a part of the back plate, and the inner peripheral side of the processing hole is also formed in the back plate, and the back plate is also melted together with the surface side plate adjacent to the in-plane direction of the joint interface, so there is no need for a backing device.

[0030] That is to say, regardless of the bonding strength, when only the back plate is bonded to the adjacent surface side plate, the bonding interface needs to be melted. If the back plate is not concave but is flat, the back plate cannot be melted in the direction of the bonding interface as long as the bottom surface of the processed hole is not melted. Therefore, in order to bond the back plate to the adjacent surface side plate, the back plate must first be melted in the thickness direction. In contrast, as long as the back plate is partially concave, the back plate can immediately melt in the direction of the bonding interface. Therefore, even if the bottom surface of the back plate is not melted, the back plate can be bonded to the adjacent surface side plate.

[0031] In this way, the arc welding method of the present invention can melt the workpiece in the in-plane direction of the joining interface even if the workpiece formed by overlapping non-ferrous metal plates is not melted in the thickness direction. Therefore, the vicinity of the joining interface can be melted as early as possible and the back plate and the front side plate can be joined before the bottom surface of the processed hole is burned through.

[0032] Furthermore, by irradiating the arc, as the workpiece is melted toward the bonding interface, the workpiece is also melted in the thickness direction of the workpiece until the back side of the backing plate is melted, thereby Figure 2As shown, the molten portion is sufficiently expanded in the in-plane direction of the joint interface, and the processed hole is filled with molten metal from the welding wire, so that the joint strength can be ensured by the molten portion formed by their solidification.

[0033] Furthermore, since the vicinity of the joint interface can be melted at an early stage, the welding energy input to the workpiece can be reduced, and not only deformation of the workpiece can be suppressed, but also the amount of smoke and dust generated can be suppressed.

[0034] In addition, Figure 1 In the figure, the welding is performed by irradiating an arc from above the processed hole formed in the workpiece, but the workpiece can also be rotated 90 degrees so that the opening of the processed hole faces the side and the arc is irradiated from the side to perform welding.

[0035] The welding energy input to the workpiece depends not only on the material and thickness of the non-ferrous metal plate, but also on the depth and diameter of the processed hole, but the current is preferably 50 to 350A (amperes) and the power-on time is preferably 0.5 to 5 seconds.

[0036] If the welding energy input to the workpiece becomes too much, the molten metal will fall off and separate from the joint portion, and the volume of the molten portion formed by solidification of the molten metal will decrease, thereby reducing the joint strength.

[0037] The thickness of the recessed portion (the portion where the processed hole is formed) of the back plate is preferably thicker than 1 / 20 of the diameter of the processed hole.

[0038] The relationship between the thickness of the back plate at the hole formation location and the cross tensile strength (CTS) when a 4 mm diameter hole is formed in a 5000 series aluminum alloy plate is shown in FIG. Figure 3 In addition, the relationship between the thickness of the back plate at the processing hole forming portion and the cross tensile strength (CTS) when a processing hole with a diameter of 8 mm is formed is shown in Figure 4 middle.

[0039] from Figure 3 , 4 It is known that since the thickness of the recessed portion of the back plate is thicker than 1 / 20 of the diameter of the processed hole, it is possible to prevent the molten metal from burning through and prevent the volume of the molten portion from decreasing.

[0040] Furthermore, as long as the depth of the recess formed in the backing plate is 0.1 mm or more, the backing plate at the bonding interface can be melted in the direction of the bonding interface.

[0041] The processing hole is preferably cylindrical. The inner circumference of the processing hole formed in the back plate and the adjacent side plate is flush, and the back plate and the side plate can be melted at the joint interface between the back plate and the side plate, so it is easy to melt toward the joint interface.

[0042] The diameter of the processing hole also depends on the required bonding strength, but is preferably larger than three times the thickness of the thinnest non-ferrous metal plate among the non-ferrous metal plates constituting the workpiece. When the diameter of the processing hole is smaller than three times the thickness of the thinnest non-ferrous metal plate among the non-ferrous metal plates constituting the workpiece, the processing hole volume is small, so even if the molten metal fills the processing hole, the heat it has is small. As a result, it is easy to dissipate heat to the surrounding parent material, making it difficult to melt toward the bonding interface, resulting in welding defects such as non-fusion.

[0043] When multiple plates are overlapped and welded, the welding strength is determined by the welding strength of the thinnest plate. Figure 5 As shown, the welding strength is correlated with the diameter of the processed hole.

[0044] For example, when the thickness of the thinnest plate material is 1 mm and the required strength as a product is 2.0 kN, by setting the processed hole to have a diameter of 4.5 mm or more, a strength of 2.5 kN or more can be ensured.

[0045] The above-mentioned arc welding method can be applied to welding of non-ferrous metal plates. Examples of the metal forming the non-ferrous metal plates include aluminum, magnesium, and titanium, as well as alloys containing these metals.

[0046] A method for inspecting the welding strength of a joined body welded by the arc welding method of the present invention described above will be described.

[0047] Generally speaking, the welding strength of the joint body is determined by the diameter of the joint interface 51 of the two plates of the fusion zone 5. Therefore, in order to know the welding strength of the joint body, it is necessary to measure the diameter of the joint interface 51 of the fusion zone 5. However, it is difficult to measure the diameter of the joint interface 51 of the fusion zone 4 from the outside.

[0048] The arc welding method of the present invention can form the processing hole 21 penetrating the joint interface 51 at the welding part as described above, and the edge of the joint interface 51 is exposed, so that the vicinity of the joint interface can be melted directly by means of the processing hole 21, and the vicinity of the joint interface can be melted even if the bottom surface of the processing hole 21 is not melted. Therefore, as long as the molten portion 5 is formed to the back surface 41 of the back plate 4, the diameter of the molten portion of the joint interface 51 is larger than the diameter 52 of the molten portion appearing on the back surface 41.

[0049] Therefore, the welding strength of the joint body welded by the arc welding method of the present invention can be estimated from the diameter 52 of the molten portion appearing on the back surface 41 of the back plate 4 .

[0050] exist Figure 6 4 shows the relationship between the diameter of the molten zone appearing on the back surface of the back plate and the tensile shear strength of the joint body welded by the arc welding method of the present invention.

[0051] from Figure 6 It is known that there is a correlation between the tensile strength of the joint and the diameter of the molten portion appearing on the back side of the back plate. For the joint welded using the arc welding method of the present invention, the welding strength of the joint can be estimated by measuring the diameter of the molten portion appearing on the back side of the back plate.

[0052] In this way, the weld strength inspection method of the bonded body only requires measuring the diameter of the molten portion that appears on the rear surface of the back sheet that can be visually recognized, and the weld strength of the bonded body can be easily estimated. Therefore, instead of performing a sample inspection, all bonded bodies can be inspected.

[0053] Description of Reference Numerals

[0054] 1. Arc welding machine; 2. Workpiece; 21. Processing hole; 22. Thickness of the back plate where the processing hole is formed; 3. Non-ferrous metal plate on the arc welding machine side (front side plate); 4. Non-ferrous metal plate on the side farthest from the arc welding machine (back plate); 41. Back side; 5. Melting part; 51. Joining interface; 52. Diameter of the melt portion appearing on the back side.

Claims

1. An arc welding method for joining a plurality of overlapping non-ferrous metal plates by melting at least parts of the workpieces, characterized in that: The workpiece has a machined hole at the welding position, The processed hole is a non-through hole that penetrates the non-ferrous metal plate on the arc irradiation side and reaches the non-ferrous metal plate on the side farthest from the arc welding machine, and is formed by partially recessing the non-ferrous metal plate on the farthest side. An arc is irradiated from the opening side of the processed hole, and welding is performed by melting the non-ferrous metal plate on the farthest side on the side opposite to the opening side of the workpiece without using a backing jig.

2. The arc welding method according to claim 1, characterized in that The processed hole is cylindrical.

3. The arc welding method according to claim 2, characterized in that: The thickness of the recessed portion of the non-ferrous metal plate on the farthest side is thicker than 1 / 20 of the diameter of the processed hole.

4. The arc welding method according to claim 3, characterized in that The diameter of the processed hole is larger than three times the thickness of the thinnest non-ferrous metal plate among the non-ferrous metal plates constituting the workpiece.

5. A welding strength inspection method for a joint body welded by the arc welding method according to any one of claims 1 to 4, wherein: The welding strength is estimated from the diameter of the molten zone that appears on the back surface of the non-ferrous metal plate on the farthest side.

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