Welding equipment

Abstract

To provide a welding apparatus that suppresses the occurrence of burn-through of molten metal. [Solution] The welding apparatus of the present disclosure comprises an arc welding unit 20 for performing arc welding, a moving mechanism for moving the arc welding unit 20, and a control unit that controls the execution of arc welding and the movement by the moving mechanism. The control unit performs arc welding for a predetermined first time, stops arc welding for a predetermined second time to cool the welding area 55 by arc welding, moves the arc welding unit 20, and performs arc welding again after the second time has elapsed.

Description

Technical Field

[0001] The present disclosure relates to a welding apparatus, and particularly to a welding apparatus for arc welding.

Background Art

[0002] Patent Document 1 discloses an arc welding method capable of efficiently welding to form a welded joint excellent in seismic resistance and fatigue resistance even when a top-bottom inversion operation is impossible.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In arc welding, when forming a weld bead of a required length, linear weld beads were formed by continuously performing arc welding from the start position to the end position of the weld bead. In this case, before the molten pool formed by arc discharge cooled and solidified, a molten pool due to subsequent arc discharge could be formed adjacent to it, forming a large molten pool, and there was a possibility of molten metal dripping from this large molten pool. The present disclosure solves such problems and provides a welding apparatus that suppresses the occurrence of dripping of molten metal.

Means for Solving the Problems

[0005] The welding apparatus of this disclosure comprises an arc welding unit for performing arc welding, a moving mechanism for moving the arc welding unit, and a control unit for controlling the execution of the arc welding and the movement by the moving mechanism, wherein the control unit performs the arc welding for a predetermined first time, stops the arc welding for a predetermined second time to cool the welded area, moves the arc welding unit, and performs the arc welding again after the second time has elapsed. This configuration suppresses the occurrence of molten metal meltdown.

[0006] The ratio of the second time to the first time may be 0.2 to 2.0. With this configuration, the molten pool cools and solidifies while the arc welding is stopped, forming a scale-like weld bead, and the time required to form the desired weld bead length can also be shortened. [Effects of the Invention]

[0007] This disclosure provides a welding apparatus that suppresses the occurrence of burn-through of molten metal. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of the welding apparatus according to Embodiment 1. [Figure 2] This is an explanatory diagram of Phase 1 of a welding method using a welding apparatus according to the present disclosure. [Figure 3] This is an explanatory diagram of Phase 2 of a welding method using a welding apparatus according to the present disclosure. [Figure 4] This is an explanatory diagram showing a weld bead formed by the welding method using the welding apparatus of this disclosure. [Figure 5] This is an explanatory diagram for overlap welding, specifically for cases where the welding torch is pointed downwards. [Figure 6] This is an explanatory diagram for butt welding. [Figure 7] This is an explanatory diagram for overlap welding, specifically for cases where the welding torch is pointed upwards. [Figure 8]This flowchart shows the calculation process performed by the calculation unit. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to Figures 1 to 8. Figure 1 is a schematic diagram of the welding apparatus of Embodiment 1. Figure 2 is an explanatory diagram of Phase 1 of the welding method using the welding apparatus of the present disclosure. Figure 3 is an explanatory diagram of Phase 2 of the welding method using the welding apparatus of the present disclosure. Figure 4 is an explanatory diagram showing a weld bead formed by the welding method using the welding apparatus of the present disclosure. Figure 5 is an explanatory diagram of overlap welding with the welding torch pointed downwards. Figure 6 is an explanatory diagram of butt welding. Figure 7 is an explanatory diagram of overlap welding with the welding torch pointed upwards. Figure 8 is a flowchart of the calculation process performed by the calculation unit.

[0010] Embodiment 1 As shown in Figure 1, the welding apparatus 1 comprises a robot 10, a wire feeding unit 12, a welding torch 20, a power supply unit 30, and a control device 60.

[0011] Robot 10 is an articulated robot having six rotation axes. A wire feeding unit 12 is attached to the robot arm 11 that makes up robot 10. A welding torch 20 is attached to the tip of robot 10. Robot 10 moves the welding torch 20 by controlling the rotation direction and rotation speed of the six rotation axes. Robot 10 is an example of a "movement mechanism for moving an arc welding unit" as disclosed herein.

[0012] As shown in Figure 1, the wire feeding unit 12 has a feeding roller 13 that feeds the welding wire 15, which is a consumable electrode, to the welding torch 20, and a feeding motor 14 that rotates the feeding roller 13. The wire feeding unit 12 supplies the welding wire 15 to the welding torch 20 at a predetermined speed by rotating the feeding roller 13 with the feeding motor 14. As the welding wire 15, solid wire or flux-cored wire made of low-carbon steel or high-tensile steel can be used.

[0013] As shown in Figure 1, the welding torch 20 has a contact tip 20A and a gas nozzle 20B. The contact tip 20A is made of a metal material such as copper and has a cylindrical shape. A welding wire 15 is inserted inside the contact tip 20A. When a welding current and welding voltage are applied to the contact tip 20A from the power supply 30, an arc discharge is generated between the tip of the welding wire 15 and the workpiece 50, and the welding wire 15 and the workpiece 50 melt to form a molten pool. In this way, arc welding is performed by the welding torch 20. The gas nozzle 20B has a cylindrical shape and surrounds the contact tip 20A. The gas nozzle 20B supplies a shielding gas such as argon to the welding area from a gas cylinder (not shown). The welding torch 20 is an example of a "welding area for arc welding" in this disclosure.

[0014] As shown in Figure 1, the power supply unit 30 is connected to the contact tip 20A of the welding torch 20 and the workpiece 50 via a power supply cable, and outputs the welding current and welding voltage.

[0015] As shown in Figure 1, the control device 60 includes a setting unit 61, a memory 62, a calculation unit 63, and a communication interface circuit 64. When performing arc welding with the welding device 1, the operator inputs teaching data such as welding conditions into the setting unit 61. The input teaching data (teaching information) is stored in the memory 62.

[0016] The control device 60 executes arithmetic processing in the arithmetic unit 63 based on the teaching information read from the memory 62. Based on the arithmetic result in the arithmetic unit 63, the control device 60 outputs a command signal to the robot 10 and the power supply device 30 via the communication interface circuit 64. The robot 10 that receives the command signal controls the rotation direction and rotation speed of the six rotating shafts to move the welding torch 20. Further, the power supply device 30 that receives the command signal outputs a welding current and a welding voltage to the contact tip 20A and the weldment 50, or terminates the output. Further, the control device 60 controls the feeding motor 14 so that the necessary feeding amount of the welding wire 15 is fed to the welding torch 20. The control device 60 is an example of the "control unit that controls the execution of arc welding and the movement by the movement mechanism" of the present disclosure.

[0017] Next, with reference to FIGS. 2 to 4, a welding method using the welding device of the present disclosure will be described. FIGS. 2 to 4 are explanatory diagrams of a case where the welding method using the welding device of the present disclosure is applied to overlay welding. Note that the welding method using the welding device of the present disclosure can also be applied to welding other than overlay welding.

[0018] First, the first weldment 51 and the second weldment 52 are overlapped, and the welding torch 20 is disposed at the edge 51A of the first weldment 51. In FIGS. 2 to 4, the first weldment 51 is disposed on the front side of the drawing with respect to the second weldment 52 (the edge 52A of the second weldment is indicated by a dashed line).

[0019] Thereafter, a welding current and a welding voltage are applied from the power supply device 30 to the contact tip 20A of the welding torch 20. Then, as shown in FIG. 2, an arc discharge occurs between the tip of the welding wire 15 and the first weldment 51 and the second weldment 52, and a molten pool is formed at the welding location 55 between the edge 51A of the first weldment 51 and the surface 52B of the second weldment 52. In this way, arc welding is performed on the first weldment 51 and the second weldment 52.

[0020] After the welding current is applied to the contact tip 20A and a predetermined welding time has elapsed, the application of the welding current to the contact tip 20A is stopped. The process from starting arc welding on the first workpiece 51 and the second workpiece 52 until the arc welding is stopped is defined as Phase 1.

[0021] While arc welding to the first workpiece 51 and the second workpiece 52 is stopped, the molten pool formed at the welding point 55 cools and solidifies, forming a weld bead. Also, as shown in Figure 3, while the molten pool at the welding point 55 cools and solidifies and the weld bead is formed, the welding torch 20 is moved a predetermined distance D along the edge 51A of the first workpiece 51.

[0022] Arc welding to the first workpiece 51 and the second workpiece 52 is stopped, and after a predetermined stop time has elapsed, a welding current is applied to the contact tip 20A to restart arc welding. The process from stopping arc welding to the first workpiece 51 and the second workpiece 52 to restarting arc welding is defined as Phase 2.

[0023] After the completion of Phase 2, Phases 1 and 2 are repeated to form a scale-like weld bead as shown in Figure 4. In this way, the welding method using the welding apparatus of the present disclosure forms a scale-like weld bead by repeatedly alternating between performing arc welding (Phase 1) and stopping arc welding (Phase 2).

[0024] Here, it is preferable that the time of Phase 1, i.e., the welding time T1 of arc welding, and the time of Phase 2, i.e., the stopping time T2 of arc welding, be in a predetermined ratio. More specifically, the ratio of stopping time T2 to welding time T1 (T2 / T1) is preferably between 0.2 and 2.0. By setting the ratio within this range, the molten pool cools and solidifies during the stopping of arc welding, forming a scale-like weld bead, and the time required to form the required weld bead length can also be shortened. If the ratio (T2 / T1) is less than 0.2, the stopping time T2 is short relative to the welding time T1, so the molten pool may not cool or solidify during the stopping of arc welding, and a scale-like weld bead may not be formed. Also, if the ratio (T2 / T1) exceeds 2.0, the stopping time T2 becomes long relative to the welding time T1, so it may take a long time to form the required weld bead length.

[0025] Furthermore, the ratio (T2 / T1) can be changed within the range of 0.2 to 2.0 depending on the welding conditions. For example, the ratio (T2 / T1) can be changed depending on how easily burn-through occurs in the molten metal forming the molten pool. Specifically, if burn-through of the molten metal is unlikely to occur, the ratio (T2 / T1) can be reduced. That is, the stop time T2 relative to the welding time T1 can be shortened. On the other hand, if burn-through of the molten metal is likely to occur, the ratio (T2 / T1) should be increased. That is, the stop time T2 relative to the welding time T1 can be lengthened.

[0026] One case in which molten metal burn-through is less likely to occur is, for example, in overlap welding of a first workpiece 51 and a second workpiece 52, as shown in Figure 5, when welding is performed with the welding torch 20 facing downwards. In other words, this is when the workpieces are in the direction of gravity (Z direction in Figure 5) of the molten pool formed by the arc discharge. Another case is when, in butt welding of a first workpiece 51 and a second workpiece 52, as shown in Figure 6, the distance G between the edge 51A of the first workpiece 51 and the edge 52A of the second workpiece 52 is small.

[0027] One example of a situation where molten metal is likely to burn through is when welding with the welding torch 20 facing upwards, as shown in Figure 7, in an overlap welding of a first workpiece 51 and a second workpiece 52. In other words, this occurs when there is no workpiece in the direction of gravity (Z direction in Figure 7) of the molten pool formed by the arc discharge. Another example is when the distance G between the edge 51A of the first workpiece 51 and the edge 52A of the second workpiece 52 is large, as shown in Figure 6, in a butt welding of a first workpiece 51 and a second workpiece 52.

[0028] The welding time T1, which is a predetermined time, is preferably, for example, 0.01 to 2.0 seconds. If the welding time T1 is shorter than 0.01 seconds, the welding wire 15 may not melt and a molten pool may not be formed. Also, if the welding time T1 is longer than 2.0 seconds, it may take too long to form the required weld bead length. The welding time T1 is an example of the "predetermined first time" in this disclosure.

[0029] The welding time T1 can be changed within the range of 0.01 to 2.0 seconds depending on the welding conditions. For example, if the thickness of the material to be welded 50 is thick, or if the material to be welded 50 is difficult to melt, it is preferable to relatively increase the welding time T1.

[0030] The predetermined stopping time T2 is preferably, for example, 0.01 to 4.0 seconds. If the stopping time T2 is shorter than 0.01 seconds, the molten pool will not cool or solidify, and a scale-like weld bead may not be formed. Also, if the stopping time T2 is longer than 4.0 seconds, it may take too long to form the required weld bead length. The stopping time T2 is an example of the "second predetermined time for cooling the welded area by arc welding" as described in this disclosure.

[0031] The distance D over which the welding torch 20 is moved during Phase 2 can be changed depending on the welding conditions. For example, if you want to increase the strength of the weld, you can relatively shorten the distance D.

[0032] Next, the calculation process performed by the calculation unit 63 of the control device 60 will be explained using the flowchart in Figure 8. Before the calculation process is executed, the operator inputs teaching data regarding welding conditions into the setting unit 61 of the control device 60. The teaching data includes the welding time T1 for arc welding, the stopping time T2 for arc welding, the distance D to move the welding torch 20, and the required weld bead length L. Once the input of the teaching data into the setting unit 61 is complete and the workpiece 50 is placed in the predetermined location, the calculation process is started in the calculation unit 63.

[0033] Step 1 (hereinafter abbreviated as "S1"; the same applies to the other steps) is performed, specifically, arc welding is carried out. A welding current and welding voltage are applied from the power supply unit 30 to the contact tip 20A of the welding torch 20, causing an arc discharge to occur between the welding wire 15 and the workpiece 50, and forming a molten pool at the welding site.

[0034] In S2, it is determined whether a predetermined welding time T1 has elapsed since the start of arc welding. If the welding time T1 has not elapsed, arc welding continues. If the welding time T1 has elapsed, the process proceeds to S3 and arc welding is stopped. That is, the application of welding current, etc., from the power supply unit 30 to the contact tip 20A is stopped.

[0035] Next, in S4, the welding torch 20 is moved a predetermined distance D.

[0036] Next, in S5, it is determined whether a predetermined stop time T2 has elapsed since the arc welding was stopped. If the stop time T2 has not elapsed, the stop of arc welding is continued. If the stop time T2 has elapsed, proceed to S6.

[0037] In S6, it is determined whether the total travel distance of the welding torch 20 has reached the required weld bead length L. If it has not, the process returns to S1 and arc welding is performed again. If it has reached the required length, arc welding is terminated.

[0038] In conventional arc welding methods, when forming a weld bead of the required length, arc welding was performed continuously from the start to the end of the weld bead to form a linear weld bead. In this case, before the molten pool formed by the arc discharge cooled and solidified, a molten pool formed next to it by a subsequent arc discharge would form, creating a larger molten pool. There was a possibility that molten metal would melt down from this larger molten pool.

[0039] In particular, in overlap welding as shown in Figure 7, when welding with the welding torch pointed upwards, or in butt welding as shown in Figure 6, when the distance between the two workpieces is large, there was a possibility of molten metal dripping out of the molten pool.

[0040] In the welding method using the welding apparatus of this disclosure, arc welding (Phase 1) and stopping the arc welding (Phase 2) are repeatedly performed alternately to form a scale-like weld bead. That is, after the molten pool is formed by arc discharge, the arc welding is stopped to cool and solidify the molten pool, and then the arc welding is performed again. With the welding method using the welding apparatus of this disclosure, a large molten pool is not formed, so the occurrence of burn-through of molten metal can be suppressed.

[0041] Furthermore, by setting the ratio of the stopping time T2 to the welding time T1 (T2 / T1) to 0.2 to 2.0, the molten pool cools and solidifies during the stopping of arc welding, forming a scale-like weld bead, and the time required to form the required weld bead length can also be shortened.

[0042] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from its spirit. [Explanation of symbols]

[0043] 10. Robots 15. Welding wire 20..Welding torch 30...Power supply device 50...Material to be welded 60... Control device

Claims

1. The arc welding area where arc welding is performed, A moving mechanism for moving the aforementioned arc welding section, The system comprises a control unit that controls the execution of the arc welding and the movement by the moving mechanism, The control unit, Perform the arc welding for a predetermined first time, The arc welding is stopped for a predetermined second time to allow the welded area to cool down, Move the arc welding area and perform the arc welding again after the second time period has elapsed. Welding equipment.

2. The ratio of the second time to the first time is between 0.2 and 2.

0. The welding apparatus according to claim 1.

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