Arc crater treatment method and welding system

Abstract

The invention provides a crater processing method and a welding system capable of more reliably processing a crater formed in a welding terminal part to be flat independent of shape and size. A crater treatment method using an arc welding robot includes: a first step of welding from a welding end position to a welding retreat position after returning a predetermined distance along a weld bead formed by welding after welding to the welding end position by an operating welding torch; a second step in which the welding torch is operated from the welding retreat position toward the welding end position and welding is performed along the weld bead; and a third step in which the arc is extinguished at the welding terminal part and then re-arcing is performed.

Description

TECHNICAL FIELD

[0001] The present application relates to a crater processing method and a welding system. BACKGROUND

[0002] In a general welding operation, when the arc is extinguished immediately at the terminal of the welding, a concave portion called a crater is formed at the terminal of the weld. Therefore, the welder performs crater processing to make the welding terminal portion flat.

[0003] In Patent Literature 1, a control method of a welding robot is described, in which, in an industrial robot that performs a welding operation using control software including a command to perform arc opening processing at an arc start point, a command to perform processing to move a robot main body to an arc closing point, and a command to perform arc closing processing at the arc closing point, a command to perform crater processing based on a current value, a voltage value, and a setting time stored in advance is set, the command to perform the crater processing is called at the arc closing point, and the crater processing is performed using the command to perform the crater processing.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent No. 2592228

[0007] In Patent Literature 1, the welding robot performs crater processing in which the arc is opened again (re-ignition) at the arc closing point of the welding terminal portion, the arc opening state is maintained for a predetermined time set, and the arc is closed at the time point at which the set time has elapsed, thereby making the crater formed at the welding terminal portion flat. However, there is a problem that such processing can not be sufficient to process the crater depending on the shape and size of the crater. SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] The present application was made in view of the above-described circumstances, and an object thereof is to provide a crater processing method and a welding system capable of processing a crater formed at a welding terminal portion to be flat.

[0010] SOLUTION TO PROBLEM

[0011] The above-described object of the present application is achieved by the following structure.

[0012] (1) A crater processing method using an arc welding robot, in which,

[0013] The crater processing method includes:

[0014] the first step, after the welding torch is operated to weld to the welding end position, the welding is performed from the welding end position to a welding retreat position retreated by a predetermined distance along a bead formed by the welding;

[0015] the second step, the welding torch is operated from the welding retreat position to the welding end position and the welding is performed along the bead; and

[0016] the third step, after the arc is extinguished at the welding terminal portion, the arc is re-ignited.

[0017] (2) A welding system capable of performing the crater processing method of (1), wherein

[0018] the welding system has:

[0019] a storage section that stores a welding condition;

[0020] the welding torch;

[0021] a welding robot that operates a welding position welded by the welding torch;

[0022] a welding power source; and

[0023] a control section that controls the welding robot and the welding power source.

[0024] Effects of the Invention

[0025] According to the present invention, the crater formed at the welding terminal portion can be more reliably processed flat regardless of the shape and size. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram showing a structure example of the welding system of the present embodiment.

[0027] Figure 2 (A) of is a model diagram showing a bead and a crater. Figure 2 (B) of is a diagram showing an outline of a crater processing method.

[0028] Figure 3 is a flowchart showing crater processing control.

[0029] Figure 4 is a model diagram showing a bias function.

[0030] EXPLANATION OF REFERENCE NUMERALS

[0031] 11 bead

[0032] 11A crater

[0033] 50 welding system

[0034] 100 welding wire

[0035] 110 welding robot

[0036] 111 welding torch

[0037] 120 control device

[0038] 140 welding power source

[0039] 150 controller

[0040] 200 workpiece

[0041] X1 welding retreat position

[0042] X2 welding end position

[0043] X3 welding terminal portion DETAILED DESCRIPTION

[0044] Hereinafter, an embodiment of the welding method and the welding system of the present application will be described in detail based on the drawings. Note that this embodiment is an example of a case where a welding robot is used, and the welding method and the welding system of the present application are not limited to the structure of this embodiment. For example, an automatic welding device using a trolley can be used, and a small welding robot of a mobile type can be used. In this embodiment, for example, a gas metal arc welding method using a pulse waveform can be used. Also, in this embodiment, a gas metal arc welding method to which the welding method of the present application is applied is described, but the welding method of the present application can be equally applied to an additive manufacturing method using gas metal arc welding.

[0045] <Summary of welding system>

[0046] Figure 1 is a summary view showing a structure example of the welding system of this embodiment. The welding system 50 is provided with a welding robot 110, a control device 120, a feeding device that feeds a welding wire 100, a welding power source 140, and a controller 150.

[0047] The welding power source 140 is connected to the welding robot 110 via a positive power cable in a manner that enables the welding wire 100 as a consumable electrode to be energized, and is connected to a workpiece (hereinafter, also referred to as "base material".) 200 via a negative power cable. This connection is in a case where welding is performed in reverse polarity, and in a case where welding is performed in positive polarity, the welding power source 140 can be reversed in polarity.

[0048] In addition, the welding power source 140 and the feeding device for feeding the welding wire 100 are connected respectively using signal lines, and the feeding speed of the welding wire can be controlled.

[0049] The welding robot 110 is equipped with a welding torch 111 as an end effector. The welding torch 111 has a conductive tip. The welding wire 100 generates an electric arc from its tip by energizing the conductive tip, and uses its heat to weld the workpiece 200, which is the object of welding.

[0050] The welding torch 111 is equipped with a shielding gas nozzle that serves as a mechanism for ejecting shielding gas. The shielding gas is supplied from a shielding gas supply device. Shielding gases can be, for example, carbon dioxide, nitrogen, argon, or mixtures thereof.

[0051] The welding wire 100 used in this embodiment is not particularly limited; for example, a solid welding wire without flux and a flux-cored welding wire can be used. Furthermore, the material of the welding wire 100 is not particularly limited; for example, it can be mild steel, stainless steel, aluminum, or titanium. Also, the diameter of the welding wire 100 is not particularly limited. In this embodiment, it is preferable to set the upper limit of the diameter to 1.6 mm and the lower limit to 0.8 mm.

[0052] In addition, the specific structure of the workpiece 200 is not particularly limited in this embodiment, and the construction conditions such as joint shape, welding posture, and bevel shape are not particularly limited.

[0053] The control device 120 primarily controls the movements of the welding robot 110. The control device 120 includes: a storage unit that stores pre-set teaching data for the welding robot 110, including its movement mode, welding start position, welding end position X2, welding retreat position X1 (described later), position of the welding end part X3 for re-initiating the arc, welding conditions, oscillation motion, and the structure of the workpiece 200 to be welded; and a control unit that instructs the welding robot 110 to perform its movements based on this data. Furthermore, the control device 120, according to the teaching data, assigns welding conditions such as welding current, welding voltage, and feed rate to the welding power source 140 during the welding operation.

[0054] The control unit may be configured using, for example, a CPU or GPU. The storage unit may be configured using, for example, volatile or non-volatile storage devices such as HDD, ROM, or RAM. The control device 120 performs various processes by reading and executing various programs and soldering conditions stored in the storage unit.

[0055] It should be noted that, as Figure 1 As shown, the welding system 50 of this embodiment is configured such that the control device 120 is independent of the welding power source 140, but it may also be configured such that the control device 120 is included in the welding power source 140.

[0056] The control device 120 executes the crater processing method of filling the crater 11A formed at the welding terminal portion X3 which is the terminal portion of the welding bead 11, by the crater processing control described later.

[0057] Note that the control device 120 inputs or holds the crater processing conditions for executing the crater processing method as the teaching data stored in the storage section. The crater processing conditions are specifically the number of times of the forward and backward swing, the amplitude of the forward and backward swing, the current at the time of executing the crater processing, and the voltage. In the crater processing of the present embodiment, the forward and backward swing is performed, and after the arc is extinguished at the welding terminal portion X3, the re-ignition of the arc is performed. As the crater processing conditions, the time from the arc extinguishment to the re-ignition of the arc, the voltage, the current, the moving distance, the moving direction, the moving speed, and the like after the re-ignition of the arc are also included.

[0058] The controller 150 is connected to the control device 120, and performs the program making or display for making the welding robot 110 act, the input of the teaching data, and the like, and imparts to the control device 120. In addition, the controller 150 also has a function of performing the manual operation of the welding robot 110. Note that the connection of the controller 150 to the control device 120 is not limited to the kind of wired or wireless.

[0059] The welding power source 140 supplies the current to the welding wire 100 according to the instruction from the control device 120, and thereby generates the arc between the welding wire 100 and the workpiece 200. In addition, the welding power source 140 outputs the signal for controlling the speed of feeding the welding wire 100 to the feeding device according to the instruction from the control device 120.

[0060] Next, the crater processing method executed by the crater processing control by the control device 120 will be described based on Figures 2-4 Figure 2 (A) of FIG. 1 is a model diagram showing the welding bead and the crater. Figure 2 (B) of FIG. 1 is a diagram showing the outline of the crater processing method. Figure 3 FIG. 2 is a flowchart showing the crater processing control. Figure 4 FIG. 3 is a model diagram showing the offset function.

[0061] As shown in (B) of FIG. 1 and (B) of FIG. 2, the crater processing method is executed by the crater processing control by the control device 120. Figure 2 Figure 3 ​​As shown, the crater processing method performs a fore-and-aft swing after the welding robot 110 completes welding to the welding end position X2. This fore-and-aft swing has a first process of welding from the welding end position X2 to the welding retreat position XI, a second process of welding along the weld bead 11 from the welding retreat position XI toward the welding end position X2, and a third process of performing a re-arc after the arc is extinguished at the welding terminal portion X3 when the first process and the second process are completed. The first process and the second process can be performed one or more times each before proceeding to the third process. In the case where the first process is performed two or more times, the number of times of the first process and the second process can not be the same number of times, and the first process can be one less than the second process. That is, the welding terminal portion X3 sometimes becomes the welding retreat position XI of the first process, and sometimes becomes the welding end position X2 of the second process. In addition, the welding end position X2 and the welding retreat position XI can be different positions during the first process and the second process are repeated.

[0062] According to the above-described crater processing method, the crater 11A, which is a recess formed at the welding terminal portion X3 when the arc is turned off (extinguished) at the welding terminal portion X3, can be more reliably processed flat.

[0063] According to the welding system 50, the above-described crater processing method can be automatically performed by the crater processing control by the control device 120. Hereinafter, each process will be described.

[0064] The first process detects that the welding robot 110 has welded to the welding end position X2 based on the teaching data stored in the control device 120. Thereafter, the operation of the welding robot 110 is controlled to perform a welding operation along the weld bead 11 from the welding end position X2 until the welding retreat position XI after a predetermined distance L has been returned (see (B) of FIG. 6). Figure 2

[0065] The second process controls the operation of the welding robot 110 to perform welding from the welding retreat position XI on the weld bead 11 to the welding end position X2 (see (B) of FIG. 6). Figure 2

[0066] That is, by the first process and the second process, the welding robot 110 performs a fore-and-aft swing that reciprocates between the welding end position X2 and the welding retreat position XI while welding is performed. These first process and the second process are performed a predetermined number of times.

[0067] The welding robot 110 can also be configured to perform a left-and-right swing that also reciprocates in the width direction of the weld bead 11 at the same time as the fore-and-aft swing.

[0068] ​​After the first process and the second process are performed for a prescribed number of times, the third process is advanced. The third process performs a re-ignition after the welding torch 111 is extinguished at the welding terminal portion X3 and a prescribed waiting time is elapsed. The conditions for the re-ignition are set to prescribed welding conditions (current, voltage) that are set in advance. After the re-ignition, the welding torch is preferably operated at a prescribed distance and a prescribed speed. In addition, a prescribed time can be elapsed after the re-ignition. The moving direction of the prescribed distance is preferably opposite to the welding direction of the last process among the first process and the second process. After the re-ignition, the arc is closed after a prescribed welding is performed, and the welding is ended.

[0069] The position coordinates at the welding end position X2, the prescribed distance L (the moving amount of the fore-and-aft swing) from the welding end position X2 to the welding retreat position Xl, the position coordinates of the welding terminal portion X3, the number of times of performing the fore-and-aft swing (the number of times of each of the first process and the second process), the width and speed of the left-and-right swing, and the welding current, the welding voltage, the welding speed, and the like at the time of the crater treatment are stored in the storage section of the control device 120 as the teaching data for performing the welding crater treatment method. Also, the waiting time from the extinguishing to the re-ignition in the third process and the current, the voltage, the moving distance after the re-ignition, the moving speed, the power-on time, and the like at the time of the re-ignition are stored in the storage section.

[0070] By setting the above-mentioned teaching data in advance according to the size of the crater 11A formed at the welding terminal portion X3, the crater 11A can be treated to be flat regardless of the size of the crater 11A formed at the welding terminal portion X3.

[0071] As the specific conditions at the time of performing the crater treatment method, it is preferable that the welding current at the time of the fore-and-aft swing is 150 to 250 A, the moving amount of the fore-and-aft swing is 3 to 20 mm, the number of times of the fore-and-aft swing is 1 to 5, the waiting time for the re-ignition is 0.5 to 3.0 seconds, the welding current at the time of the re-ignition is 100 to 200 A, and the moving distance after the re-ignition is 5 to 25 mm.

[0072] The teaching data required for the execution of the crater treatment method can also be configured to automatically calculate the size of the crater 11A and the information required for the treatment of the crater 11A according to the shape data of the welding object such as the groove and the welding conditions.

[0073] In addition, it can be configured such that a detection sensor that detects the size of the molten pool in the welding work is provided to the welding robot 110, and the control device 120 automatically sets the teaching data at the time of performing the above-mentioned crater treatment method based on the size of the molten pool detected by the detection sensor.

[0074] In addition, the movement amount of the fore-and-aft swing based on the first process and the second process can also be changed according to the number of times of the fore-and-aft swing. Specifically, it can also be configured that the more the fore-and-aft swing is repeated, the more the movement amount of the fore-and-aft swing is gradually reduced.

[0075] According to this configuration, it is possible to process the crater 11A to be more flat, and it is possible to more efficiently perform the crater processing method.

[0076] As shown in Figure 4 , the control device 120 can also be configured to have a movement function of offsetting the coordinates of the welding torch 111 (the front end of the welding wire 100) at least to the side of the vertical plate from the center of the width direction of the weld 11 (to the Figure 4 Sy direction) when the fore-and-aft swing is performed by the first process and the second process, in the case where the crater processing is performed on the weld 11 formed by the fillet welding using the above-described crater processing control.

[0077] It can also be configured that the direction in which the welding torch 111 (the welding wire 100) is offset is adjusted in the height direction (Z direction) of the weld 11 in addition to the leg length direction (Y direction) of the weld 11. This configuration can be referred to Figure 4 .

[0078] According to the movement function, it is possible to prevent the occurrence of a portion in which the welding metal is not melted to the workpiece 200 at the terminal portion (hereinafter, referred to as an overlap) due to the molten metal falling down under the action of gravity in the case where the crater processing control is performed on the weld 11 formed by the fillet welding.

[0079] The direction and the distance (Sz, Sy) offset from the center of the weld 11 are input in advance to the storage section of the control device 120 when the movement function is performed. It can also be configured that this information is automatically calculated according to the size of the weld 11 or the like.

[0080] Note that the present application is not limited to the above-described embodiments, and the present application also intends to include the range of claims, by combining the structures of the embodiments with each other, by changing them based on the description and well-known technologies by those skilled in the art, and by applying them.

[0081] As described above, the following matters are disclosed in the present specification.

[0082] (1) A crater processing method using an electric arc welding robot, in which,

[0083] The crater processing method includes:

[0084] a first process of welding from a welding end position to which the welding torch is operated to weld to a welding retreat position retreated by a predetermined distance after the welding, along a weld formed by the welding after the welding is performed to the welding end position;

[0085] a second process of operating the welding torch in a direction from the welding retreat position to the welding end position and welding along the bead; and

[0086] a third process of performing arc striking again after arc extinction at the welding terminal portion.

[0087] According to the present structure, the crater formed at the welding terminal can be more reliably processed flat.

[0088] (2) The crater processing method according to (1), wherein

[0089] The first process and the second process are each performed a prescribed number of times before proceeding to the third process.

[0090] According to the present structure, even in the case where the shape of the crater is large, the crater can be processed flat.

[0091] (3) The crater processing method according to (2), wherein

[0092] The prescribed distance is gradually reduced as the first process and the second process are repeatedly performed.

[0093] According to the present structure, the crater processing can be performed more efficiently.

[0094] (4) The crater processing method according to any one of (1) to (3), wherein

[0095] In the third process, after arc striking again, the welding torch is operated to weld at a prescribed movement distance and a prescribed speed.

[0096] According to the present structure, it is possible to prevent a crater recess from remaining at the terminal of the bead or to prevent the crater from being excessively piled up.

[0097] (5) The crater processing method according to any one of (1) to (4), wherein

[0098] The movement of the welding torch in the third process is opposite to the movement of the welding torch in the first process or the second process immediately preceding the third process.

[0099] According to the present structure, the crater at the terminal of the bead can be more reliably processed flat.

[0100] (6) The crater processing method according to any one of (1) to (5), wherein

[0101] The first process and the second process move the welding torch in a left-right width direction of the bead as well as along the bead.

[0102] According to the present structure, even in a case where the width direction of the groove is wide, the crater formed at the terminal of the weld bead can be efficiently processed.

[0103] (7) The crater processing method according to any one of (1) to (6), wherein

[0104] In the case of fillet welding, the welding position in the first process and the second process is offset upward from the center position of the weld bead.

[0105] According to the present structure, the generation of the overlap at the time of fillet welding can be efficiently prevented with a simple method.

[0106] (8) A welding system capable of executing the crater processing method according to any one of (1) to (7), wherein

[0107] The welding system has:

[0108] a storage section that stores a welding condition;

[0109] the welding torch;

[0110] a welding robot that operates a welding position welded by the welding torch;

[0111] a welding power source; and

[0112] a control section that controls the welding robot and the welding power source.

[0113] According to the present structure, along with the automation of the welding work by the welding robot, the crater processing at the terminal of the weld bead can also be automated. Therefore, the efficiency of the welding work can be improved, and the quality at the welding terminal portion can be maintained high.

Claims

1. A crater treatment method using an arc welding robot, wherein the crater treatment method includes: a first process of welding from a welding end position to a welding retreat position after a prescribed distance of retreat from the welding end position along a bead formed by welding after operating a welding torch to weld to the welding end position; a second process of operating the welding torch from the welding retreat position toward the welding end position and welding along the bead; and a third process of performing a re-ignition of an arc after extinguishing the arc at a welding terminal portion.

2. The crater treatment method according to claim 1, wherein the first process and the second process are each performed a prescribed number of times before proceeding to the third process.

3. The crater treatment method according to claim 2, wherein the prescribed distance is gradually reduced as the first process and the second process are repeatedly performed.

4. The crater treatment method according to claim 1, wherein in the third process, the welding torch is operated to weld at a prescribed movement distance and a prescribed speed after the re-ignition of the arc.

5. The crater treatment method according to claim 1, wherein the movement of the welding torch in the third process is in the opposite direction to the movement of the welding torch in the first process or the second process immediately preceding the third process.

6. The crater treatment method according to claim 1, wherein the first process and the second process move the welding torch in a widthwise direction of the bead as well as along the bead.

7. The crater treatment method according to claim 1, wherein in the case of a fillet weld, the welding position in the first process and the second process is offset upward from a center position of the bead.

8. A welding system capable of performing the crater treatment method according to any one of claims 1 to 7, wherein the welding system has: a storage section that stores welding conditions; the welding torch; a welding robot that operates a welding position to be welded by the welding torch; a welding power source; and a control section that controls the welding robot and the welding power source.

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