JP7058063B2 - Welding equipment - Google Patents

Description

The present invention relates to a welding device or the like for welding a material to be welded.

When a plurality of plate materials and the like are stacked and joined, they may be joined by spot welding. Spot welding is a type of resistance welding method that uses resistance heat generation to join metals. In spot welding, the welded material is pressurized by the electrodes in a state where the welded materials are overlapped with each other, an electric current is further applied from the electrodes, and the welded portion is heated by resistance heat generation to locally melt the welded material. , The welded material is joined by metallurgy. In spot welding, the melt-solidified portion is called a "nugget", and the welded object is joined in the nugget.

The welding device used for spot welding includes a pair of facing electrodes, a gun that holds the electrodes, and a cooling device that cools the electrodes by circulating cooling water through the electrodes. The electrodes are configured to be relatively movable in a direction in which the distance between the electrodes is changed so that the object to be welded is sandwiched between the pair of electrodes and pressure can be applied. Further, the electrode has a configuration in which an arbitrary current can be applied to the welding target to be pressure-welded. Then, in order to cool the electrode to which an electric current is being applied, the cooling device circulates cooling water through the electrode to cool the electrode. Here, when a current is applied, the electrode becomes hot due to the current flowing through the electrode itself. Therefore, the electrode eventually melts and softens, and the shape of the tip of the electrode is deformed in combination with pressurizing the welding target. In order to suppress this, when an electric current was applied to the electrodes, the electrodes were cooled by a cooling device at the same time.

In this way, in conventional spot welding, a plurality of overlapping materials to be welded are sandwiched between electrodes and pressurized, and an electric current is passed between the electrodes while cooling the electrodes to melt the materials to be welded. It is to be joined.

Japanese Unexamined Patent Publication No. 2013-202683

However, the conventional spot welding has a problem that welding defects occur when welding a welding target having a high plate thickness ratio.

Here, the plate thickness ratio indicates the ratio of the total thickness of the total welded material (hereinafter, also referred to as the total plate thickness) to the thickness of the outermost welded material (hereinafter, also referred to as the re-outer plate thickness). It is a value obtained by dividing the total plate thickness by the re-outer plate thickness. That is, "the plate thickness ratio is high" means that the thickness of the outermost material to be welded is thinner than the total thickness of the welded objects to be welded.

In spot welding, the nugget grows from near the center between the electrodes. Therefore, if the plate thickness ratio to be welded is high, it becomes difficult for the nugget to reach the outermost material to be welded. In particular, cooling the electrodes reduces the heat generated by the weld and inhibits the growth of the nugget. Therefore, in spot welding where the nugget does not grow sufficiently due to cooling the electrodes, the nugget reaches the outermost material to be welded when welding the target to be welded with a thin outermost material to be welded. In some cases, welding defects may occur when welding a welding target having a high plate thickness ratio.

In order to solve the above problems, the welding apparatus of the present invention aims to perform welding with high accuracy even when welding a welding target having a high plate thickness ratio.

As a result of diligent studies by the present inventors in order to achieve the above object, it has been found that by controlling the cooling of the electrodes used for welding, the growth of the nugget formed on the welding target during welding can be controlled. .. Specifically, from the viewpoint of suppressing the deformation of the electrode, it is desirable to sufficiently cool the electrode during welding. However, it has been found that if the electrode is excessively cooled during welding, the temperature of the electrode becomes too low and the growth of the nugget becomes insufficient, which may cause welding failure. Through repeated and diligent studies, the present inventors have found that the growth direction of the nugget can be controlled by controlling the cooling of the electrodes.

The welding apparatus of the present invention provided based on such knowledge has a plurality of electrodes that pressurize the welding object and apply an electric current to the welding object, a driving device that drives the electrodes, and a current to the electrodes. It has a power supply device to be applied, a cooling device capable of cooling the electrodes, and a control device for controlling the operation of the drive device, the power supply device, and the cooling device. By controlling the cooling of the electrodes, it is possible to control the growth direction of the nugget formed on the welding target.

According to such a configuration, by controlling the cooling of the electrodes by the cooling device by the control device, it is possible to provide a welding device capable of controlling the growth direction of the nugget formed on the welding target.

As a result of further diligent studies by the present inventors, it has been found that the growth direction of the nugget can be arbitrarily controlled by individually controlling the cooling of each electrode sandwiching the welding target. Specifically, for example, in the case of welding using a pair of electrodes, if cooling control is performed so that one electrode has a lower temperature than the other, the temperature is higher than that of the cold electrode side. We found that nuggets tend to grow on the side of the electrodes.

Based on this finding, the control device may be capable of individually controlling the cooling of at least one of the electrodes.

According to this configuration, the growth direction of the nugget can be controlled by controlling the cooling of the electrodes. Therefore, according to the above-mentioned configuration, even when welding is performed on a welding target that is difficult to weld, for example, when welding a welding target having a high plate thickness ratio, sufficient joining is performed with high accuracy. Is possible.

Further, in the welding device, the control device sets the cooling device so as to stop cooling while the current is applied to the electrodes, provided that the plate thickness ratio of the welding target is equal to or higher than a predetermined value. You may control it.

In this way, when the plate thickness ratio to be welded is high, by stopping the cooling of the electrodes, it is possible to suppress the temperature of the electrodes from dropping too much, and the nugget grows more reliably on the outermost material to be welded. This can be promoted, and even when welding a welding target having a high plate thickness ratio, sufficient joining can be performed.

Further, in the welding device, the cooling device may cool the electrode by circulating cooling water through the electrode.

In this way, by cooling the electrodes by circulating the cooling water, the degree of cooling can be adjusted by the flow amount of the cooling water, and the cooling can be easily controlled.

Further, the welding device may further include a temperature measuring device for measuring the temperature of the electrode, and the control device may control the operation of the cooling device according to the electrode temperature.

In this way, by controlling the cooling of the electrode according to the temperature of the electrode, it is possible to reduce the cooling of the electrode only when the temperature of the electrode is lowered and the growth of the nugget is inhibited. Therefore, it is possible to suppress cooling as necessary to promote the growth of the nugget, and it is possible to perform sufficient bonding even when welding a welding target having a high plate thickness ratio while suppressing deformation of the electrodes as much as possible. It will be possible.

As described above, even when welding a welding target having a high plate thickness ratio, welding can be performed with high accuracy.

The figure which illustrates the schematic structure of the welding apparatus of this invention. A cross-sectional view illustrating a configuration example of an electrode in the welding apparatus of the present invention. Diagram illustrating nugget growth in welded objects The figure explaining the cooling process in the welding apparatus of this invention.

First, a configuration example of the welding apparatus of the present invention will be described with reference to FIG.

FIG. 1 is a diagram illustrating a schematic configuration of a welding apparatus of the present invention.

As illustrated in FIG. 1, the welding apparatus 1 of the present invention includes an electrode 4, a gun 6 holding the electrode 4, a robot 8 including the electrode 4 and the gun 6, and a transformer 10 for applying an electric current to the electrode 4. A timer 12 for controlling the current applied to the transformer 10, a cooling device 14 for cooling the electrodes 4, and a control device 16 for controlling the operations of the timer 12, the cooling device 14, and the robot 8 are provided. Since such a welding device 1 includes a transformer 10 and a gun 6, it is also referred to as a tragun.

In the welding device 1, a gun 6 provided with a pair of electrodes 4 is provided so that the welding target 18 can be pressed while being sandwiched and a current can be circulated through the welding target 18. The welding target 18 is a stack of a plurality of materials to be welded. In the welding target 18, adjacent materials to be welded are joined by welding.

The details of the electrode 4 and the gun 6 will be described later, but the outline is as follows. That is, the gun 6 holds a pair of electrodes 4 and allows the electrodes 4 to move in a direction in which the electrodes 4 approach or separate from each other. The electrode 4 pressurizes the welding target 18 and passes a predetermined current through the welding target 18 to heat and melt the welding target 18 between the electrodes to weld the welding target 18. The amount of current applied to the electrode 4 can be determined according to the thickness of the welding target 18, the thickness of each material to be welded, the required welding strength, and the like, and is adjusted by the transformer 10.

The transformer 10 converts the current applied via the timer 12 into a predetermined current value, and then applies the converted current to the electrode 4. For example, a current of several A at 400 V applied via the timer 12 is converted into a current of 15000 A at 3 to 5 V and applied to the electrode 4. The timer 12 controls the timing of applying a current to the electrode 4 via the transformer 10. The transformer 10 is controlled by the control device 16, and the control device 16 can also control the transformer 10 via the timer 12.

The cooling device 14 is a device for cooling the electrode 4, and cools the electrode 4 when a current is applied from the electrode 4 to the welding target 18. During welding, an electric current flows through the electrode 4, so that the electrode is heated and softened. At this time, since the electrode 4 pressurizes the welding target 18, the softened electrode 4 receives the force from the welding target 18. Therefore, the tip of the electrode 4 is deformed or damaged by repeated welding. The shape of the tip of the electrode 4 affects the current density of the current applied to the welding target 18 and the pressing force on the welding target 18 depending on the area in contact with the welding target 18. Since the current density and the pressing force affect the welding accuracy, the welding device 1 usually adjusts the tip shape by periodically scraping the tip of the electrode 4 in order to keep the tip shape of the electrode 4 within a certain range. Or the electrode 4 itself was replaced. Further, in order to suppress the deformation of the electrode 4, the electrode 4 is cooled during welding. Cooling can be performed, for example, by circulating cooling water through the electrode 4. In the following description, a cooling device 14 using cooling water will be described as an example, but the configuration of the cooling device 14 is arbitrary as long as the electrode 4 can be cooled.

The robot 8 includes an electrode 4, a gun 6, and a robot arm 20. The robot 8 has a configuration in which the gun 6 can be moved to an arbitrary position within a predetermined range by the robot arm 20, and the gun 6 is moved to a predetermined welding position. Further, as described above, the gun 6 moves the electrode 4.

The control device 16 controls the operation of the robot 8 and at the same time controls the operation of the timer 12. Further, the control device 16 controls the operation of the cooling device 14. As described above, in the conventional welding apparatus, when welding is performed by applying a current from the electrode 4 to the welding target 18, the electrode 4 is constantly cooled. When the welding target 18 has a high plate thickness ratio, the welding apparatus 1 of the present invention can stop or reduce the supply of cooling water that cools the electrode 4 while applying an electric current. For example, when the plate thickness ratio of the welding target 18 is 4 or more, the information is input to the control device 16 by the operator, and the control device 16 stops the supply of the cooling water when the current is applied to the electrode 4. The cooling device 14 is controlled in such a manner. The condition for stopping or reducing the supply of cooling water is not limited to the case where the welding target 18 has a high plate thickness ratio, but instead of the high plate thickness ratio or the high plate thickness ratio. In addition to this, other conditions such as the re-outer plate thickness being thinner than a predetermined thickness may be provided, and the condition may be that the growth of these nuggets is insufficient. In the control device 16 and the like, electric power is applied from a lower voltage power source different from the power source used for applying the current to the electrode 4.

Although a detailed description will be described later, the growth of the nugget inside the welding target 18 tends to be hindered by cooling the electrode 4 and lowering the temperature of the electrode 4. When the plate thickness ratio of the welding target 18 is high, the thickness of the outermost material to be welded (re-outer plate thickness) is thin, so that the nugget may not reach the outermost material to be welded even if it grows. Therefore, the outermost material to be welded may not be joined, resulting in poor welding. On the other hand, although a detailed description will be described later, in the welding apparatus 1 of the present invention, in order to stop the cooling water while the current is applied from the electrode 4, the heating of the electrode 4 is continued, and the electrode 4 is The temperature is higher than when it is cooled. Therefore, the growth of the nugget is promoted, and the nugget reaches the outermost material to be welded. As a result, even when the plate thickness ratio of the welding target 18 is high, welding can be performed with high certainty, and welding can be performed with high accuracy.

The number of electrodes 4 is not limited to a pair, and three or more electrodes 4 may be used as long as the welding target 18 is sandwiched and a current can be passed through the welding target 18.

Further, in the above description, the amount of current applied to the electrode 4 is adjusted by the transformer 10, but if a predetermined current can be applied to the electrode 4, the current can be applied from a device other than the transformer 10. Further, if a predetermined current can be directly applied to the electrode 4 from the outside, the transformer 10 or the like is unnecessary.

Further, in FIG. 1, the timer 12 related to the application of the current to the electrode 4 and the control device 16 and the like are illustrated as a configuration in which electric power is applied from another power source, but electric power is applied from a common power source. Alternatively, each device may receive electric power from another power source as needed.

Further, the electrodes 4 and the gun 6 are driven by the robot 8 functioning as a driving device in response to the instruction of the control device 16. For example, the operation of the electrodes 4 approaching and separating from each other is driven by the gun 6, and the movement of the gun 6 is performed by the robot arm 20.

Further, the timer 12 and the transformer 10 function as a power supply device for applying a current to the electrode 4. The power supply device may have other configurations as long as a predetermined amount of current can be applied to the electrode 4.

The configurations of the electrodes and the gun will be described in more detail with reference to FIGS. 1 and 2.

FIG. 2 is a cross-sectional view illustrating a configuration example of an electrode in the welding apparatus of the present invention, and schematically shows the structure of a main part inside the electrode and the gun.

As described above, the gun 6 includes a pair of electrodes 4. Specifically, the gun 6 has a configuration in which two tip portions are separated from each other and face each other. An electrode 4 is held at each of the two tips. The gun 6 has a configuration in which the electrodes 4 can be projected and immersed so that the electrodes 4 are close to and separated from each other and the welding target 18 arranged between the electrodes 4 can be pressurized. Further, the gun 6 is provided with a power supply line 22 inside. The power line 22 is connected to the electrode 4 and the transformer 10, and the current applied from the transformer 10 is circulated through the electrode 4. Further, the gun 6 is provided with a cooling water pipe 24 inside. The cooling water pipe 24 is connected to the electrode 4 and the cooling device 14, and is configured to circulate cooling water from the cooling device 14 to each electrode 4. The cooling water pipe 24 has a double tubular structure, and a water supply pipe 26 is inserted therein. In the cooling water pipe 24, the cooling water supplied from the cooling device 14 passes through the water supply pipe 26 and is discharged inside the electrode 4. The electrode 4 is cooled by the discharged cooling water, and the cooling water is circulated to the cooling device 14 through the inside of the cooling water pipe 24 around the water supply pipe 26. Further, the gun 6 can be freely moved in the three-dimensional direction by the robot arm 20, and is moved according to the working position.

Each electrode 4 is made of a conductive metal such as copper. The electrode 4 is connected to the power supply line 22, and a current is applied from the transformer 10 via the power supply line 22. When a current is applied between the pair of electrodes 4, a current flows through the welding target 18 sandwiched between the electrodes 4. The electrode 4 is heated by the flowing current. At the same time, the welding target 18 is heated by the flowing current, and the material to be welded is melt-bonded together with the heat transmitted from the electrode 4. Each electrode 4 has a hollow structure inside, and a cooling water pipe 24 is inserted into the electrode 4. The cooling water introduced from the water supply pipe 26 flows into the hollow structure inside the electrode 4 and cools the electrode 4. The cooling water that has cooled the electrode 4 flows into the cooling water pipe 24 around the water supply pipe 26 and is circulated to the cooling device 14. When welding is performed, the pair of electrodes 4 project in a direction close to each other to sandwich the welding target 18 and pressurize the welding target 18. In this state, a current is passed through the electrode 4 to pass a current through the welding target 18, the electrode 4 and the welding target 18 are heated, a nugget is formed on the welding target 18, and the material to be welded is joined. Normally, when an electric current is applied to the electrode 4, cooling water is circulated from the cooling device 14 to the electrode 4 to cool the electrode 4. In the welding apparatus 1 of the present invention, when the plate thickness ratio of the welding target 18 is a certain value or more, it is possible to stop the flow of cooling water to the electrode 4 while the current is being applied to the electrode 4. .. By stopping the cooling of the electrode 4, the electrode 4 is heated, the growth of the nugget is promoted, and even when the plate thickness ratio of the welding target 18 is high, the welded material can be reliably joined. Will be.

Next, using FIGS. 1 to 3, the joining method performed by the welding apparatus 1 of the present embodiment while explaining the relationship between the formation of the nugget and the joining of the material to be welded described above based on a general theory. Will be described in detail.

FIG. 3 is a diagram illustrating the growth of the nugget in the welded object.

In FIG. 3A, the thinner material 28 to be welded in the outermost part of the welding target 18 is sufficiently thick, and the plate thickness ratio of the welding target 18 = Ta / ta is sufficiently low. In this case, good welding is possible even with a conventional welding device. That is, even if the electrode 4 is continuously cooled while the current is applied to the electrode 4, the nugget 30 can reach the material to be welded 28, and the welding target 18 is sufficiently welded.

In FIG. 3B, it is assumed that the thinner material 32 to be welded in the outermost part of the welding target 18 is thin, and the plate thickness ratio of the welding target 18 = Tb / tb is equal to or higher than a predetermined value. For example, it is assumed that the plate thickness ratio is 4 or more. In this case, in the conventional welding apparatus, the nugget 34 does not reach the welded material 32, the welded material 32 is not joined, and the welding target 18 becomes a welding defect. This is because the electrode 4 continues to be cooled while the electric current is applied to the electrode 4, so that the growth of the nugget 34 is hindered and the nugget 34 does not reach the material 32 to be welded.

Here, the nugget 30 in FIG. 3A and the nugget 34 in FIG. 3B are substantially the same because they are welded by the same welding device. The nuggets 30 and 34 are formed near the center of the welding target 18 in the plate thickness direction and grow in a certain range in the direction of the electrode 4. Therefore, when the plate thickness ratio is low and the outermost material to be welded 28 is sufficiently thick, the nugget 30 reaches the material to be welded 28 and the welding target 18 is satisfactorily welded. On the contrary, when the plate thickness ratio is high and the outermost material 32 to be welded is thin, the nugget 34 does not reach the material 32 to be welded, and the welding target 18 becomes poorly welded.

Generally, in order to increase the welding strength, the current density of the current flowing through the welding target 18 becomes a problem. Specifically, the welding strength and the welding range are determined by the amount of current flowing, the time during which the current flows, the shape of the tip of the electrode 4, the pressure applied by the electrode 4 to pressurize the welding target 18, and the like. In addition to this, the growth of the nuggets 30, 34 is also affected by the temperature of the electrode 4. For example, in a conventional welding device, when an electric current is applied to the electrode 4, the electrode 4 is cooled in order to suppress deformation of the tip shape of the electrode 4. Therefore, the heating of the electrode 4 is suppressed during welding, the heat transferred from the electrode 4 to the welding target 18 is limited, the temperature of the region of the welding target 18 in contact with the electrode 4 does not rise, and the heating of the welding target 18 is limited. Become a target. As a result, the temperature of the welding target 18 does not rise in the welding target 18 as compared with the case where the electrode 4 is not cooled, and the growth of the nuggets 30 and 34 is also limited.

In consideration of the above, in the welding apparatus 1 of the present invention, the flow of cooling water to the electrode 4 is stopped while the current is applied to the electrode 4, so that the electrode 4 is not cooled. As a result, the temperature of the electrode 4 during welding becomes higher than that of the conventional welding apparatus, the heat transferred to the welding target 18 increases, and the temperature of the welding target 18 becomes higher. Therefore, as shown in FIG. 3C, the nugget 36 that grows on the welding target 18 expands.

In FIG. 3C, similarly to FIG. 3B, it is assumed that the outermost material 32 to be welded to the welding target 18 is thin, and the plate thickness ratio of the welding target 18 = Tb / tb is equal to or higher than a predetermined value. When the welding device 1 of the present invention is used, the flow of cooling water to the electrode 4 is stopped while the current is applied to the electrode 4 so that the electrode 4 is not cooled. Therefore, the temperature of the electrode 4 rises sufficiently during welding, and the temperature of the welding target 18 in the vicinity of the region in contact with the electrode 4 also rises sufficiently. As a result, the nugget 36 can grow sufficiently in the direction of the electrode 4, and the nugget 36 reaches the material to be welded 32. Therefore, even when the plate thickness ratio of the welding target 18 is high, the welded material 32 can be reliably joined.

Next, the timing of application of current and cooling in the welding apparatus 1 of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 4 is a diagram illustrating a cooling process in the welding apparatus of the present invention.

In FIG. 4, the horizontal axis represents the energization time in the welding process as a cycle, and the vertical axis represents the amount of current applied to the electrode 4 and the amount of cooling water circulated for cooling the electrode 4.

First, as shown by the solid line in FIG. 4, cooling water is circulated through the electrode 4 in order to suppress the deformation of the electrode 4.

Next, when an electric current is applied to the electrode 4, the flow of cooling water is stopped to stop the cooling of the electrode 4. Then, a predetermined amount of current is applied to the electrode 4. By applying an electric current, an electric current flows through the welding target 18, the welding target 18 is gradually melted, the nugget 36 grows, and the welding of the welding target 18 proceeds. At this time, since the cooling of the electrode 4 is stopped as described above, the temperature of the electrode 4 is maintained above a certain level. As a result, the amount of heat transferred from the electrode 4 to the welding target 18 increases to promote the temperature rise of the welding target 18, and the temperature of the electrode 4 itself is maintained, so that the welding target 18 in the vicinity of the region in contact with the electrode 4 It also prevents the temperature from dropping. As a result, the growth of the nugget 36 is promoted in the welding target 18, the nugget 36 can easily reach the outermost material 32 to be welded, and the accuracy of good welding is improved.

Next, when a current is applied for a predetermined time, the application of the current to the electrode 4 is stopped.

Finally, the flow of the cooling water to the electrode 4 is restarted, and the cooling of the electrode 4 is restarted. In this way, by stopping the cooling of the electrode 4 only while the current is applied to the electrode 4 and cooling the electrode 4 during the other period, it is possible to prevent the electrode 4 from becoming unnecessarily high temperature. .. Therefore, it is possible to suppress the softening of the electrode 4 and prevent the tip shape of the electrode 4 from being deformed.

As described above, in the welding apparatus 1 of the present invention, the cooling process is controlled, the cooling of the electrode 4 is stopped only while the current is applied to the electrode 4, and the electrode 4 is cooled before and after that. As a result, the temperature of the electrode 4 and the welding target 18 can be maintained while the current is applied to the electrode 4, so that the material 32 to be welded is reliably joined even when the plate thickness ratio of the welding target 18 is high. It is possible to improve the welding accuracy. At the same time, the electrode 4 can be cooled sufficiently during the other period, so that the deformation of the tip shape of the electrode 4 can be suppressed.

In FIG. 4, a current is applied to the electrode 4 at once up to a predetermined current amount, the applied current amount is held for a certain period of time, and then the current amount is reduced at once. The current application process is not limited to this, and the current amount is increased and decreased in a plurality of stages so that the current amount is maintained after being applied to a predetermined current amount and then the current amount is further increased. Is also good. For example, it is possible to perform three-stage energization that increases or decreases the amount of current to be maintained in three stages, or seven-stage energization that increases or decreases the amount of current to be maintained in seven stages.

Further, the cooling was stopped before the start of the application of the current to the electrode 4, and the cooling was restarted after the application of the current to the electrode 4 was stopped, but the cooling was stopped and restarted after the current of the current to the electrode 4 was stopped. It may be started and stopped at the same time as the application, or may be before or after at predetermined intervals.

Further, in the above description, the cooling of both of the pair of electrodes 4 is controlled, but only one of them may be controlled. For example, cooling may be stopped while applying a current to the electrode 4 only for the electrode 4 in contact with the thinner electrode to be welded 32, and cooling may be continued for the other electrode 4. As a result, at least on the electrode 4 side where cooling is stopped, the nugget 36
The nugget 36 reaches the thicker and thinner material 32 to be welded. Further, since the other electrode 4 continues to be cooled, the deformation of the tip shape of the electrode 4 is more reliably suppressed. Therefore, the material 32 to be welded can be reliably joined even when the plate thickness ratio of the welding target 18 is high while suppressing the deformation of the tip shape of the electrode 4.

Further, in the welding apparatus 1 of the present invention, a temperature measuring device for measuring the temperature of the electrode 4 may be further provided. The temperature of the electrode 4 is measured by the temperature measuring device, and the temperature information is transmitted to the control device 16. Then, when the plate thickness ratio of the welding target 18 is higher than a predetermined value, the control device 16 controls the cooling device 14 to stop the supply of the cooling water only when the temperature of the electrode 4 drops below a certain temperature. do. Further, when the temperature of the electrode 4 increases to a certain temperature abnormality, the cooling device 14 restarts the supply of the cooling water by the control device 16. In this way, the temperature change of the electrode 4 is monitored, and the cooling of the electrode 4 is controlled according to the temperature of the electrode 4. As a result, even when the plate thickness ratio of the welding target 18 is high, cooling is stopped as necessary, so that the material 32 to be welded can be joined more efficiently and reliably. At the same time, it is possible to suppress the promotion of heating of the electrode 4 more than necessary, and it is possible to more reliably suppress the deformation of the tip shape of the electrode 4.

In each of the above welding devices 1, a plate thickness measuring device for measuring the thickness of each material to be welded constituting the welding target 18 may be further provided. The thickness of each material to be welded is measured by a plate thickness measuring device, and the thickness of each is transmitted to the control device 16. The control device 16 calculates the plate thickness ratio from the received thickness of each material to be welded. Then, when the plate thickness ratio becomes a predetermined value or more, the control device 16 performs cooling control when applying a current to the electrode 4 as described above. As a result, the plate thickness ratio can be determined and cooling control can be automatically performed. Therefore, even when the plate thickness ratio of the welding target 18 is high, the operator can easily suppress the deformation of the tip shape of the electrode 4 without checking the plate thickness ratio and operating the welding device. The welded material 32 can be reliably joined.

1 Welding device 4 Electrode 6 Gun 8 Robot 10 Transformer 12 Timer 14 Cooling device 16 Control device 18 Welding target 20 Robot arm 22 Power line 24 Cooling water pipe 26 Water supply pipe 28 Welded material 30 Nugget 32 Welded material 34 Nugget 36 Nugget

Claims (1)

A plurality of electrodes that pressurize the welding target and apply an electric current to the welding target,
The drive device that drives the electrodes and
A power supply device that applies an electric current to the electrodes, and
A cooling device capable of cooling the electrodes and
It has a drive device, a power supply device, and a control device for controlling the operation of the cooling device.
By controlling the cooling of the electrode by the cooling device by the control device, the growth direction of the nugget formed on the welding target can be controlled.
On condition that the plate thickness ratio to be welded is equal to or higher than a predetermined value, the cooling of the electrode is stopped or reduced before the current is applied to the electrode or from the start of the current application, and the current to the electrode is reduced. A welding apparatus characterized in that the cooling of the electrode is stopped or reduced during the application of the electrode.

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