Crater treatment method and welding system

Abstract

To provide a crater-processing method and a weld system capable of more surely and flatly processing craters formed on a weld trailer regardless of the shape and the size.SOLUTION: The method includes a first step of operating a weld gun to weld to a weld end position and then to weld to a weld retreat position along a weld bead formed by the weld, a second step of operating the weld gun from the weld retreat position toward the weld end position to weld along the weld bead, and a third step of extinguishing an arc and then re-arcing in a weld trailer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a crater treatment method and a welding system. [Background technology]

[0002] In normal welding, if the arc is extinguished immediately at the end of the weld, a depression called a crater will be formed at the end of the weld bead. For this reason, welders perform crater treatment to flatten the end of the weld.

[0003] Patent Document 1 describes a control method for an industrial robot that performs welding operations using control software including a command to execute arc-on processing at the arc start point, a command to execute processing to move the robot body to the arc-off point, and a command to execute arc-off processing at the arc-off point. The control method sets a command to execute crater processing based on a current value, voltage value, and set time for crater processing that are stored in advance, calls a command to execute crater processing at the arc-off point, and executes crater processing based on the command to execute crater processing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2592228 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, a welding robot performs crater treatment by turning the arc on again (re-arcing) at the arc-off point of the weld end, maintaining the arc-on state for a set predetermined time, and then turning the arc off when the set time has elapsed, thereby flattening the crater formed at the weld end. However, there is a problem in that this treatment alone may not be sufficient to treat the crater depending on its shape and size.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a crater treatment method and welding system that can flatten a crater formed at the end of a weld. [Means for solving the problem]

[0007] The above object of the present invention can be achieved by the following configuration. (1) A crater treatment method using an arc welding robot, comprising: a first step of operating a welding torch to weld to a welding end position, and then welding along the weld bead formed by welding to a welding retreat position that is retreated a predetermined distance from the welding end position; a second step of operating the welding torch from the welding retract position toward the welding end position to weld along the weld bead; and a third step of extinguishing the arc at the end of the weld and then re-arcing. Crater treatment method. (2) A welding system capable of carrying out the crater treatment method described in (1), a memory unit that stores welding conditions; the welding torch; a welding robot that controls a welding position by the welding torch; a welding power source; a control unit that controls the welding robot and the welding power source, Welding system. [Effects of the Invention]

[0008] According to the present invention, craters formed at the end of a weld can be more reliably flattened regardless of their shape or size. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of a welding system according to this embodiment. [Figure 2]Figure 2(A) is a model diagram showing a weld bead and a crater, and Figure 2(B) is a diagram showing an outline of a crater treatment method. [Figure 3] FIG. 3 is a flow diagram showing the crater treatment control. [Figure 4] FIG. 4 is a model diagram showing the offset function. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of a welding method and welding system according to the present invention will be described in detail with reference to the drawings. Note that this embodiment is an example of a case where a welding robot is used, and the welding method and welding system according to the present invention are not limited to the configuration of this embodiment. For example, an automatic welding device using a cart may be used, or a portable small welding robot may be used. Furthermore, this embodiment may use, for example, a gas metal arc welding method using a pulse waveform. Furthermore, in this embodiment, a gas metal arc welding method to which the welding method according to the present invention is applied will be described, but the welding method according to the present invention can also be applied to an additive manufacturing method that applies gas metal arc welding.

[0011] <Welding system overview> 1 is a schematic diagram showing an example of the configuration of a welding system according to this embodiment. Welding system 50 includes welding robot 110, control device 120, a feeder that feeds welding wire 100, welding power source 140, and controller 150.

[0012] Welding power source 140 is connected to welding robot 110 via a positive power cable so that current can be applied to welding wire 100, which is a consumable electrode, and is connected to workpiece (hereinafter also referred to as "base material") 200 via a negative power cable. This connection is for welding with reverse polarity; to weld with positive polarity, the polarity of welding power source 140 can be reversed.

[0013] Furthermore, welding power source 140 and a feeder for feeding welding wire 100 are connected by a signal line, so that the feed speed of the welding wire can be controlled.

[0014] The welding robot 110 is equipped with a welding torch 111 as an end effector. The welding torch 111 has a contact tip. When current is passed through the contact tip, the welding wire 100 generates an arc from its tip, and the generated heat welds the workpiece 200, which is the welding target.

[0015] The welding torch 111 includes a shielding gas nozzle that ejects shielding gas. The shielding gas is supplied from a shielding gas supply device. Examples of the shielding gas that can be used include carbon dioxide, nitrogen, argon, and mixtures of these.

[0016] The welding wire 100 used in this embodiment is not particularly limited, and for example, either a solid wire containing no flux or a flux-cored wire may be used. The material of the welding wire 100 is also not particularly limited, and the material may be, for example, mild steel, stainless steel, aluminum, or titanium. Furthermore, the diameter of the welding wire 100 is also not particularly limited. In this embodiment, the upper limit of the diameter is preferably 1.6 mm, and the lower limit is preferably 0.8 mm.

[0017] In addition, in this embodiment, the specific configuration of the workpiece 200 is not particularly limited, and the working conditions such as the joint shape, welding position, and groove shape are also not particularly limited.

[0018] Control device 120 mainly controls the operation of welding robot 110. Control device 120 has a memory unit that stores teaching data that predefines the operation pattern of welding robot 110, the welding start position, the welding end position X2, the welding retraction position X1 (described later), the position of weld end point X3 where re-arcing is performed, the welding conditions, the weaving operation, the configuration of workpiece 200 to be welded, etc., and a control unit that instructs welding robot 110 on these data to control the operation of welding robot 110. Control device 120 also provides welding conditions such as the welding current, welding voltage, and feed speed to welding power source 140 during welding operation in accordance with the teaching data. The control unit is configured using, for example, a CPU, a GPU, etc. The storage unit is configured using, for example, a volatile or non-volatile storage device such as a HDD, a ROM, or a RAM. The control device 120 realizes various processes by reading and executing various programs and welding conditions stored in the storage unit. As shown in FIG. 1, welding system 50 of the present embodiment is configured such that control device 120 is independent from welding power source 140, but welding power source 140 may be configured to include control device 120 therein.

[0019] Control device 120 executes a crater treatment method for filling crater 11A formed at weld end portion X3, which is the end portion of weld bead 11, by crater treatment control, which will be described later. The control device 120 receives or holds crater treatment conditions for executing the crater treatment method as teaching data stored in a memory unit. The crater treatment conditions are, specifically, the number of back-and-forth weavings, the amplitude of the back-and-forth weavings, and the current and voltage when performing the crater treatment. In the crater treatment of this embodiment, back-and-forth weaving is performed, the arc is extinguished at the weld end X3, and then re-arcing is performed. Further crater treatment conditions include the time from arc extinguishing to re-arcing, the voltage after re-arcing, the moving distance, the moving direction, the moving speed, etc.

[0020] Controller 150 is connected to control device 120, and creates or displays programs for operating welding robot 110, inputs teaching data, and provides the programs to control device 120. Controller 150 also has a function for manually operating welding robot 110. Note that the connection between controller 150 and control device 120 is not limited to wired or wireless.

[0021] In response to a command from control device 120, welding power source 140 supplies a current to welding wire 100, thereby generating an arc between welding wire 100 and workpiece 200. In response to a command from control device 120, welding power source 140 also outputs a signal to the feeder to control the speed at which welding wire 100 is fed.

[0022] Next, a crater treatment method executed by the crater treatment control by the control device 120 will be described with reference to Figures 2 to 4. Figure 2(A) is a model diagram showing a weld bead and a crater. Figure 2(B) is a diagram showing an overview of the crater treatment method. Figure 3 is a flow diagram showing crater treatment control. Figure 4 is a model diagram showing the offset function. As shown in FIGS. 2(B) and 3, the crater treatment method involves performing back-and-forth weaving after welding to a welding end position X2 is completed by a welding robot 110. This back-and-forth weaving includes a first step of welding from the welding end position X2 to a welding retreat position X1; a second step of welding along the weld bead 11 from the welding retreat position X1 toward the welding end position X2; and a third step of extinguishing the arc at the weld end point X3 after the first and second steps are completed and then re-arcing. Before proceeding to the third step, each of the first and second steps can be performed one or more times. When the first step is performed two or more times, the first and second steps do not have to be performed the same number of times; the first step can be performed one less than the second step. That is, the weld end point X3 can be the welding retreat position X1 of the first step or the welding end position X2 of the second step. Furthermore, the welding end position X2 and the welding retreat position X1 can be positioned differently during the repetition of the first and second steps.

[0023] According to the above-described crater treatment method, the crater 11A, which is a recess formed at the weld end X3 when the arc is turned off (extinguished) at the weld end X3, can be more reliably treated to be flat. According to the welding system 50, the above-described crater treatment method can be automatically performed by the crater treatment control performed by the control device 120. Each step will be described below.

[0024] The first step is to detect that welding robot 110 has welded up to welding end position X2 based on the teaching data stored in control device 120. Thereafter, the operation of welding robot 110 is controlled to perform welding work up to welding retreat position X1, which is a preset distance L back along weld bead 11 from welding end position X2 (see FIG. 2(B)).

[0025] In the second step, the operation of welding robot 110 is controlled to perform welding from welding retraction position X1 on weld bead 11 to welding end position X2 (see FIG. 2(B)). That is, in the first and second steps, the welding robot 110 performs forward and backward weaving, moving back and forth between the welding end position X2 and the welding retreat position X1 while welding. The first and second steps are performed a predetermined number of times. Welding robot 110 may be configured to move back and forth in the width direction of weld bead 11 simultaneously with back-and-forth weaving, thereby simultaneously performing left-and-right weaving.

[0026] After the first and second steps have been performed a predetermined number of times, the process proceeds to the third step. In the third step, the welding torch 111 is extinguished at the weld end X3, and after a predetermined waiting time has elapsed, re-arcing is performed. The conditions for re-arcing are predetermined welding conditions (current, voltage). After re-arcing, it is preferable that the welding torch is moved a predetermined distance and at a predetermined speed. It is also possible to weld for a predetermined time after re-arcing. The movement direction for this predetermined distance is preferably opposite to the welding direction of the last of the first and second steps. After re-arcing, the predetermined welding is performed, and then the arc is turned off, ending the welding.

[0027] The memory unit of control device 120 stores, as teaching data for executing the welding crater treatment method, the position coordinates of welding end position X2, a predetermined distance L (amount of movement of front and rear weaving) from welding end position X2 to welding retract position X1, the position coordinates of weld end point X3, the number of times front and rear weaving is performed (number of times for each of the first and second steps), the width and speed of left and right weaving, the welding current, welding voltage, welding speed during crater treatment, etc. Furthermore, this memory unit stores the waiting time from extinguishing to re-arcing in the third step, the current and voltage at re-arcing, the movement distance and movement speed after re-arcing, the current flow time, etc. By setting the above teaching data in advance according to the size of the crater 11A to be formed at the weld end portion X3, the crater 11A can be flattened regardless of the size of the crater 11A to be formed at the weld end portion X3.

[0028] Specific conditions for carrying out the crater treatment method are preferably a welding current during back and forth weaving of approximately 150 to 250 A, a movement distance during back and forth weaving of approximately 3 to 20 mm, a number of back and forth weavings of approximately 1 to 5, a waiting time for re-arcing of approximately 0.5 to 3.0 seconds, a welding current during re-arcing of approximately 100 to 200 A, and a movement distance after re-arcing of approximately 5 to 25 mm.

[0029] The teaching data required to execute the crater processing method may be configured to automatically calculate the size of the crater 11A and the information required to process the crater 11A from shape data of the welding object, such as the groove where the welding work will be performed, and welding conditions, etc. In addition, the welding robot 110 may be provided with a detection sensor that detects the size of the molten area during welding work, and the control device 120 may be configured to automatically set teaching data for executing the above-mentioned crater treatment method based on the size of the molten area detected by the detection sensor.

[0030] Furthermore, the amount of movement of the front and rear weaving in the first and second steps may be changed depending on the number of times the front and rear weaving is performed. Specifically, the amount of movement of the front and rear weaving may be gradually reduced as the front and rear weaving is repeated. According to this configuration, the crater 11A can be processed to be flatter, and the crater processing method can be executed more efficiently.

[0031] As shown in FIG. 4, when the control device 120 performs crater processing on the weld bead 11 formed by fillet welding using the above-described crater processing control, the control device 120 may be provided with a shift function that shifts the coordinates of the welding torch 111 (tip of the welding wire 100) at least toward the vertical plate side from the center of the width direction of the weld bead 11 (offset in the Sy direction in FIG. 4) when weaving back and forth in the first and second steps. The offset direction of welding torch 111 (welding wire 100) may be adjusted not only in the leg length direction (Y direction) of weld bead 11 but also in the height direction (Z direction) of weld bead 11. This configuration can be seen in FIG. 4. The shift function prevents the occurrence of a portion (hereinafter referred to as an overlap) at the end of the weld metal that is not melted to the workpiece 200 due to gravity sagging of the molten metal when crater processing control is performed on the weld bead 11 formed by fillet welding. When executing the shift function, the direction and distance (Sz, Sy) of the offset from the center of weld bead 11 are input in advance to the storage unit of control device 120. This information may be configured to be automatically calculated based on the size of weld bead 11, etc.

[0032] The present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0033] As described above, the present specification discloses the following: (1) A crater treatment method using an arc welding robot, comprising: a first step of operating a welding torch to weld to a welding end position, and then welding along the weld bead formed by welding to a welding retreat position that is retreated a predetermined distance from the welding end position; a second step of operating the welding torch from the welding retract position toward the welding end position to weld along the weld bead; and a third step of extinguishing the arc at the end of the weld and then re-arcing. Crater treatment method. According to this configuration, the crater formed at the end of the weld can be more reliably flattened.

[0034] (2) before proceeding to the third step, the first step and the second step are each performed a predetermined number of times; (1) A crater treatment method according to the present invention. According to this configuration, even if the crater is large, it can be flattened.

[0035] (3) gradually reducing the predetermined distance as the first step and the second step are repeated; (2) A crater treatment method according to the present invention. According to this configuration, the crater processing can be performed more efficiently.

[0036] (4) In the third step, after re-arcing, the welding torch is operated at a predetermined moving distance and a predetermined speed to perform welding. The crater treatment method according to any one of (1) to (3). This configuration can prevent a recessed portion of a crater from remaining at the end of the weld bead and prevent the crater from being overfilled.

[0037] (5) The movement of the welding torch in the third step is made in a direction opposite to the movement of the welding torch in the first step or the second step performed immediately before the third step. The crater treatment method according to any one of (1) to (4). According to this configuration, the crater at the end of the weld bead can be more reliably flattened.

[0038] (6) In the first step and the second step, when the welding torch is moved along the weld bead, the welding torch is also moved in a left-right width direction of the weld bead. The crater treatment method according to any one of (1) to (5). According to this configuration, even when the groove is wide in the width direction, it is possible to efficiently treat the crater formed at the end of the weld bead.

[0039] (7) In the case of fillet welding, the welding position in the first step and the second step is offset upward from the center position of the weld bead. The crater treatment method according to any one of (1) to (6). According to this configuration, the occurrence of overlap during fillet welding can be efficiently prevented in a simple manner.

[0040] (8) A welding system capable of performing the crater treatment method according to any one of (1) to (7), a memory unit that stores welding conditions; the welding torch; a welding robot that controls a welding position by the welding torch; a welding power source; a control unit that controls the welding robot and the welding power source, Welding system. According to this configuration, as welding work is automated using a welding robot, processing of craters formed at the end of the weld bead can also be automated, thereby improving the efficiency of welding work and maintaining high quality at the end of the weld. [Explanation of symbols]

[0041] 11 Weld bead 11A Crater 50 Welding System 100 welding wire 110 Welding Robot 111 Welding Torch 120 Control device 140 Welding power source 150 Controller 200 Work X1 Welding retract position X2 Welding end position X3 Weld End

Claims

1. A crater treatment method using an arc welding robot, comprising: a first step of operating a welding torch to weld to a welding end position, and then welding along the weld bead formed by welding to a welding retreat position that is retreated a predetermined distance from the welding end position; a second step of operating the welding torch from the welding retract position toward the welding end position to weld along the weld bead; and a third step of extinguishing the arc at the end of the weld and then re-arcing. Crater treatment method.

2. Before proceeding to the third step, the first step and the second step are each performed a predetermined number of times. The crater treatment method according to claim 1.

3. The predetermined distance is gradually reduced as the first step and the second step are repeated. The crater treatment method according to claim 2.

4. In the third step, after the re-arcing, the welding torch is operated at a predetermined moving distance and a predetermined speed to perform welding. The crater treatment method according to claim 1.

5. The movement of the welding torch in the third step is made in a direction opposite to the movement of the welding torch in the first step or the second step performed immediately before the third step. The crater treatment method according to claim 1.

6. In the first step and the second step, when the welding torch is moved along the weld bead, the welding torch is also moved in a left-right width direction of the weld bead. The crater treatment method according to claim 1.

7. In the case of fillet welding, the welding positions in the first step and the second step are offset upward from the center position of the weld bead. The crater treatment method according to claim 1.

8. A welding system capable of executing the crater treatment method according to any one of claims 1 to 7, a memory unit that stores welding conditions; the welding torch; a welding robot that controls a welding position by the welding torch; a welding power source; a control unit that controls the welding robot and the welding power source, Welding system.

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