High current arc-welding method

Abstract

To provide a high current arc welding method which can reduce the number of welding passes and can improve welding property.SOLUTION: A high current arc welding method performs arc welding of a second base metal 20 provided with a bevel 23 on an end part 21 onto a surface 11 of a first base metal 10 under high electric current. Therein, an angle of the bevel 23 is larger than 45° and is 70° or less and a wire target position P2 is made to be the position entering to the inner part than a bevel bottom P1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a high-current arc welding method.

Background Art

[0002] Arc welding is widely used in various industrial fields. In the construction field, for example, it is applied in the production of building H-beams. The output current in arc welding is often set in the range of about 300 A to 350 A.

[0003] By the way, in the "Welding Groove Standard" of the "Steel Structure Work" in the Architectural Construction Standard Specification JASS6 of the Architectural Institute of Japan, a groove angle of 45 degrees is described. Therefore, for example, in the production of the above-mentioned building H-beams, when a groove is provided at the end of the web and partial penetration welding is performed by bringing the end of the web into contact with the wide surface of the flange, the groove angle is generally set to 45 degrees. Furthermore, the wire aiming position is generally set at the bottom of the groove, and arc welding is performed. Thus, since the groove angle is 45 degrees and the wire aiming position is set at the bottom of the groove, in terms of design, the groove depth and the effective throat thickness generally have the same value.

[0004] In the above-mentioned conventional arc welding, multi-layer buildup welding often occurs, and a problem is the reduction in weldability (welding efficiency) due to an increase in the number of welding passes. Therefore, an arc welding method capable of reducing the number of welding passes and improving weldability is desired.

[0005] Here, Patent Document 1 proposes an arc welding method. This arc welding method is an arc welding method in which a welding torch supporting a consumable electrode is moved in the welding line direction while oscillating in the groove width direction to automatically perform welding along the welding line. The oscillation pattern of the welding torch is preset according to the groove shape of the welded joint, and after presetting a reference value of the oscillation width with respect to the time average value of the welding current detected when the welding torch oscillates along the left and right groove surfaces of the welded joint, welding is started. The welding current detected when the welding torch oscillates along the left and right groove surfaces of the welded joint is detected on each of the left and right groove surfaces, and after obtaining the time average value of the welding current on each of the left and right groove surfaces by dividing the time integral value of the detected welding current by the oscillation time, the time average value of the welding current obtained is added to each other on the left and right, and the time average value reference difference is obtained by comparing the added value with the reference value of the oscillation width, and the oscillation width setting value of the welding torch is changed and controlled according to the time average value reference difference.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] According to the arc welding method described in Patent Document 1, it is said that high-quality automation of arc welding can be achieved, but it is not certain whether the above-mentioned problems, that is, the number of welding passes can be reduced and the weldability can be improved.

[0008] The present invention has been made in view of the above problems, and an object thereof is to provide a high-current arc welding method capable of reducing the number of welding passes and improving weldability.

Means for Solving the Problems

[0009] To achieve the above object, one aspect of the high-current arc welding method according to the present invention is A high-current arc welding method for arc welding a second base material having a groove at its end to the surface of a first base material under a high current, wherein the angle of the groove is greater than 45 degrees and not more than 70 degrees, and the wire aiming position is set at a position inside the root rather than at the bottom of the groove.

[0010] According to this aspect, in a method of arc welding a second base material having a groove at its end to the surface of a first base material under a high current, the groove angle (the angle of the groove from the surface of the first base material) is made greater than 45 degrees to make the depth of the groove shallower, and the wire aiming position is set inside the root (the contact portion between the surface of the first base material and the end of the second base material). By performing arc welding under a high current, the base material can be effectively melted in addition to the wire. Since the groove is shallow, the amount of molten metal can be reduced, and the welding time can be shortened.

[0011] Here, the lower limit value of making the groove angle "greater than 45 degrees" means making the groove angle larger than the conventional general 45 degrees. On the other hand, the upper limit value of "70 degrees" is defined because if the groove angle becomes larger than 70 degrees and the groove depth becomes even shallower, the groove processing range will become too wide, which is not preferable.

[0012] Also, performing arc welding with the wire aiming position at a position inside the root rather than at the bottom of the groove is a novel method compared to the conventional general method of performing arc welding with the wire aiming position aligned with the bottom of the groove. Combining this method with arc welding under a high current naturally results in a novel method. Here, in the high-current arc welding method, an arc output current higher than the conventional general current value of about 300 A to 350 A is applied.

[0013] The arc welding method of this aspect includes various forms such as submerged arc welding, gas shielded arc welding (CO2 arc welding, MAG (Metal Active Gas Welding) arc welding, MIG (Metal Inert Gas) arc welding, TIG (Tungsten Inert Gas) arc welding), etc.

[0014] Moreover, another aspect of the high-current arc welding method according to the present invention is With respect to the thickness t of the second base material, the groove depth d is t 1 / 2 or more and less than 2×t 1 / 2 It is characterized in that it is in the range.

[0015] According to this aspect, with respect to the thickness t of the second base material, the groove depth d is t 1 / 2 or more and less than 2×t 1 / 2 By setting it in the range, the groove depth can be made shallower than that of a conventional general welding method. For example, in the "Welding Groove Standard" in the "Steel Structure Work" of the Architectural Institute of Japan's Architectural Construction Standard Specification JASS6, with respect to the thickness t of the second base material, the groove depth d is 2×t 1 / 2 Since the arc welding is performed with the bottom of the groove with a deep groove depth as the wire aiming position, there is room for improvement in weldability. However, according to this aspect, while making the groove depth shallower, the wire aiming position is set inside the root, and by performing arc welding under a high current, the weldability is significantly improved.

[0016] Moreover, another aspect of the high-current arc welding method according to the present invention is It is characterized in that welding is performed with the effective throat thickness as 2d.

[0017] According to this aspect, although the groove depth is shallower than that of a conventional general arc welding method, by setting the wire aiming position at a position inside the root rather than the bottom of the groove and performing arc welding under a high current, the base material can be effectively melted even inside the root, and the effective throat thickness in design can be made 2d.

[0018] Another aspect of the high-current arc welding method according to the present invention is that the thickness t of the second base material is 16 mm or more and 40 mm or less.

[0019] According to this aspect, by applying a steel plate with a thickness of 16 mm or more and 40 mm or less, which is generally applied as the second base material, from thin plates to thick plates, various arc weldings using general steel plates can be realized. Here, as an example of the object manufactured by arc welding, there can be mentioned built-up H-beams in which the second base material is a web and the first base material is a flange.

[0020] Another aspect of the high-current arc welding method according to the present invention is that the high current is 350 A or more.

[0021] According to this aspect, by performing arc welding under a high current of 350 A or more, even when the wire aiming position is set inside the root, the base material can be effectively melted in addition to the wire. Here, as the output current of the arc, it is possible to set up to about 1000 A, but a range of about 350 A to 500 A is a preferable range from the viewpoints of the performance and cost of a semi-automatic welding machine.

[0022] Another aspect of the high-current arc welding method according to the present invention is that the arc welding is gas shielded arc welding.

[0023] According to this aspect, by applying gas shielded arc welding, an oxidizing shielding gas such as CO2·Ar + CO2 mixed gas (in the case of MIG welding of Al alloy, an inert gas such as Ar·He + Ar mixed gas) is sent around the arc to block the molten part from the atmosphere, while continuously supplying the wire with a motor-driven roller or the like and welding while keeping the arc length constant, the molten metal and the arc can be protected from the atmosphere and the arc can be stably maintained, leading to an improvement in weldability.

[0024] Another aspect of the high-current arc welding method according to the present invention is that The arc welding is characterized in that it is robot welding using a gas shielded arc welding machine.

[0025] According to this aspect, by applying robot welding using a gas shielded arc welding machine, high-current arc welding with higher precision and efficiency can be realized compared to general semi-automatic welding. Here, the welding robot has at least a manipulator having a welding torch at its tip, a controller that executes operation control of the manipulator, and a programming pendant that stores a series of welding operations in the manipulator, and a series of operations will be taught by teaching.

Effect of the Invention

[0026] As can be understood from the above description, according to the high-current arc welding method of the present invention, the number of welding passes can be reduced and the weldability can be improved.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0028] Hereinafter, a high-current arc welding method according to an embodiment will be described with reference to the accompanying drawings. In the present specification and drawings, substantially the same components may be denoted by the same reference numerals to omit redundant descriptions.

[0029] [High-Current Arc Welding Method According to Embodiment] Referring to FIGS. 1 and 2, an example of a high-current arc welding method according to an embodiment will be described. Here, FIG. 1 is an explanatory diagram of an example of the high-current arc welding method according to the embodiment, and FIG. 2 is a diagram showing a state in which a first base material and a second base material are welded and joined by the high-current arc welding method according to the embodiment.

[0030] Hereinafter, a method of high-current arc welding a steel second base material 20 having a groove 23 at an end portion 21 to the surface 11 of a steel first base material 10 will be described.

[0031] The thickness t1 of the second base material 20 is smaller than the thickness t2 of the first base material 10. For example, the first base material 10 and the second base material 20 are respectively the flange and the web of built-up H-shaped steel. Since they are members for manufacturing general built-up H-shaped steel, the thickness t1 of the second base material 20 corresponding to the web is 16 mm or more and 40 mm or less, and the thickness t2 of the first base material 10 corresponding to the flange is set in a range similar to or larger than the thickness t1.

[0032] Here, in addition to built-up H-shaped steel, when a reinforcing rib is welded to the end portion of a steel plate-shaped core material of a buckling-restrained brace to form a cross-sectional cruciform end structure, an example of a form in which the second base material is the reinforcing rib and the first base material is the core material can be cited.

[0033] A pair of grooves 23 are provided at the left and right corner portions of the end portion 21 of the second base material 20, and high-current arc welding is sequentially performed on both grooves 23 in a posture where the end face 22 of the second base material 20 is in contact with the surface 11 of the first base material 10.

[0034] As shown in FIG. 1, at the time of arc welding, the first base material 10 is mounted on a processing table S having a tapered surface at an angle θ. Here, the angle θ of the tapered surface of the processing table S is set to about 60 degrees to 70 degrees.

[0035] Thus, when the first base material 10 is placed at a placement angle of about 60 to 70 degrees during high-current arc welding, in downward partial penetration welding, generation of hot cracks due to a narrow bead width can be suppressed, and furthermore, undercut that may occur on the first base material 10 side can be suppressed.

[0036] The welding torch T is provided at the tip of a manipulator that constitutes a welding robot using a gas shielded arc welding machine (not shown), and the welding wire W is automatically fed out in the X direction from the welding torch T.

[0037] Furthermore, the arc welding shown in the figure is gas shielded arc welding such as carbon dioxide gas shielded arc welding. Therefore, the arc welding method in the illustrated example is a high-current arc welding method that is robot welding using a gas shielded arc welding machine.

[0038] The groove angle φ (angle from the surface 11 of the first base material 10) of the groove 23 provided at the end 21 of the second base material 20 is set in a range greater than 45 degrees and equal to or less than 70 degrees, and is set to, for example, 60 degrees.

[0039] Furthermore, with respect to the thickness t1 of the second base material 20, the groove depth d is t 1 / 2 above 2×t 1 / 2 and is set in a range less than.

[0040] In the "Welding Groove Standard" in the "Steel Structure Work" of the Architectural Institute of Japan's Architectural Construction Standard Specification JASS6, the conventional general groove angle is 45 degrees in accordance with the 45 degrees described as the groove angle. In the same "Welding Groove Standard", with respect to the thickness t1 of the second base material, the groove depth d is 2×t1 1 / 2 However, in the arc welding method shown in the figure, by setting the groove angle to be larger than 45 degrees, the groove depth d is made shallower. Specifically, it is t 1 / 2 above 2×t 1 / 2 and is in a range less than.

[0041] Furthermore, in the conventional general arc welding method, the wire aiming position is set at the bottom of the groove, whereas in the illustrated arc welding method, the wire aiming position P2 is set at a position inside the root from the bottom of the groove P1 (a position in the middle of the end face 22). In FIG. 1, the length e is the length from the side face 24 of the second base material 20 to the wire aiming position P2.

[0042] Moreover, with respect to the range of about 300 A to 350 A of the output current in the conventional general arc welding method, in the illustrated arc welding method, it is set to 350 A or more, for example, 400 A or 500 A. By this, while increasing the groove angle φ to be greater than 45 degrees to make the groove depth shallower and setting the wire aiming position P2 inside the root, it is possible to effectively melt the end portion 21 of the second base material 20 in addition to the welding wire W (deep penetration can be obtained), reduce the amount of molten metal due to the shallowness of the groove, and shorten the welding time.

[0043] Here, if the groove angle is made greater than 70 degrees, although the groove depth becomes even shallower, the groove machining range spreads too much and is not preferable, so the upper limit value of the groove angle is defined as 70 degrees.

[0044] Also, in the state where the surface 11 of the first base material 10 and the end portion 21 of the second base material 20 shown in FIG. 2 are welded and joined, the effective throat thickness a of the welded portion 30 is in the range up to the wire aiming position e shown in FIG. 1, and it becomes possible to set the effective throat thickness in design to 2d (d is the groove depth).

[0045] Next, the groove shape, wire aiming position, and effective throat thickness for each steel material thickness of the second base material 20 applied in the illustrated high - current arc welding method are shown in Table 1 below. For comparison, the groove shape with a conventional groove angle of 45 degrees (described in "Welding Groove Standard") is shown in Table 2 below.

[0046]

Table 1

[0047]

Table 2

[0048] As is clear from comparing Table 1 and Table 2, by setting the tip angle from the conventional general 45 degrees to 60 degrees (in the range greater than 45 degrees and less than or equal to 70 degrees), the tip depth is halved. Furthermore, by performing high-current arc welding with the wire aiming position inside the root rather than at the tip bottom, the number of welding passes can be reduced and the weldability can be improved.

[0049] In addition, other embodiments in which other components are combined with the configurations and the like described in the above embodiments may be possible, and the present invention is not limited to the configurations shown here at all. In this regard, it can be changed without departing from the gist of the present invention and can be appropriately determined according to the application form.

Explanation of Reference Numerals

[0050] 10: First base material 11: Surface (wide surface) 20: Second base material 21: End 22: End face 23: Groove 24: Side face 30: Welded part T: Welding torch W: Welding wire P1: Groove bottom P2: Wire aiming position

Claims

1. A high-current arc welding method in which a second base material having a bevel at its end is arc-welded to the surface of a first base material under a high current, wherein the angle of the bevel is greater than 45 degrees and not more than 70 degrees, and the wire aiming position is set at a position inside the root rather than at the bottom of the bevel, characterized by a high-current arc welding method.

2. The high-current arc welding method according to claim 1, wherein the bevel depth d is t １／２ or more and less than 2×t １／２ with respect to the thickness t of the second base material.

3. The high-current arc welding method according to claim 2, characterized in that welding is performed with an effective penetration thickness of 2d.

4. The high-current arc welding method according to claim 1 or 2, characterized in that the thickness t of the second base material is 16 mm or more and 40 mm or less.

5. The high-current arc welding method according to claim 1 or 2, characterized in that the high current is 350 A or more.

6. The high-current arc welding method according to claim 1 or 2, characterized in that the arc welding is gas shielded arc welding.

7. The high-current arc welding method according to claim 5, characterized in that the arc welding is robot welding using a gas shielded arc welding machine.

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