JP7760413B2 - Laser-arc hybrid welding equipment - Google Patents

Description

The present invention relates to a laser-arc hybrid welding device.

Patent Publication No. 2021-49562 (Patent Document 1) is a prior art document disclosing a laser-arc hybrid welding device. The laser-arc hybrid welding device described in Patent Document 1 includes a laser torch and a welding torch. The laser torch is configured to irradiate a laser toward the joint. The welding torch is configured to generate an arc between the joint and the laser torch. The joint is welded by heat input from the laser irradiation and arc welding, ensuring the joint strength of the joint.

Japanese Patent Application Laid-Open No. 2021-49562

In consumable electrode arc welding, welding is performed by appropriately changing the polarity ratio of the positive and negative electrodes. In the laser-arc hybrid welding device described in Patent Document 1, increasing the polarity ratio of the negative electrode in arc welding increases the amount of melted welding wire, thereby improving welding workability. On the other hand, increasing the polarity ratio of the negative electrode decreases the polarity ratio of the positive electrode, which may result in insufficient removal of the surface coating from the joint.

The present invention has been made to solve the above problems, and aims to provide a laser-arc hybrid welding device that can remove the surface coating of the parts to be joined while improving welding workability.

The laser-arc hybrid welding device according to the present invention comprises a laser torch and a welding torch. The laser torch irradiates the parts to be welded with a laser to remove the surface coating of the parts to be welded. The welding torch generates an arc between itself and the parts to be welded, welding the parts to be welded. The welding torch is configured to be able to change the polarity ratio between the positive electrode polarity and the negative electrode polarity. After the laser torch irradiates the parts to be welded with a laser, the polarity ratio of the negative electrode polarity on the welding torch is 50% or more, and the parts to be welded are welded.

In this case, while laser irradiation ensures the removal of the surface coating on the joint, by setting the electrode negative polarity ratio in arc welding to 50% or more, the amount of melted welding wire can be increased, thereby improving the welding workability.

In one embodiment of the present invention, the laser output of the laser torch increases as the polarity ratio of the electrode negative polarity increases.

In this case, the surface coating removal effect, which decreases as the polarity ratio of the electrode positive polarity decreases, can be ensured by increasing the laser output.

In one embodiment of the present invention, the width of the laser irradiation area in a direction perpendicular to the welding direction increases as the polarity ratio of the electrode negative polarity increases.

This increases the width of the surface coating removed by laser irradiation, suppressing humping during arc welding.

In one embodiment of the present invention, the width of the laser irradiation area in a direction perpendicular to the welding direction is between one and two times the leg length of the part to be welded.

In this case, by irradiating the laser with an appropriate width, it is possible to ensure that the laser irradiation removes the surface coating.

In one embodiment of the present invention, the welding torch welds the parts to be joined with a polarity ratio of negative electrode polarity of 70% or more. The welding by the welding torch is short-circuit welding.

In this case, spatter can be suppressed by short-circuit welding while ensuring sufficient surface coating removal and welding workability.

This invention makes it possible to remove the surface coating from the parts to be joined while improving welding workability.

1 is a schematic diagram showing the configuration of a laser-arc hybrid welding device according to an embodiment of the present invention. 1 is a top view showing a state in which a base material is being welded by a laser-arc hybrid welding apparatus according to an embodiment of the present invention; FIG. 1 is a cross-sectional view showing a laser irradiation range and an arc welding range of a base material in a laser-arc hybrid welding apparatus according to an embodiment of the present invention. FIG. 1 is a cross-sectional view showing a joining state of base materials welded by a laser-arc hybrid welding device according to an embodiment of the present invention. FIG. 1 is a graph showing the relationship between the polarity ratio of electrode negative polarity in arc welding and laser output in a laser-arc hybrid welding device according to an embodiment of the present invention.

A laser-arc hybrid welding device according to one embodiment of the present invention will be described below with reference to the drawings. In the following description of the embodiment, the same or equivalent parts in the drawings will be designated by the same reference numerals, and their description will not be repeated.

In the drawings, the direction of welding progress is designated as the DR1 direction, and the direction perpendicular to the welding progress direction and parallel to the base material surface is designated as the DR2 direction.

Positive electrode polarity refers to a polarity state in which the welding torch side of the current path supplied from the welding power source is the anode and the base metal side is the cathode. Negative electrode polarity refers to a polarity state in which the base metal side of the current path supplied from the welding power source is the anode and the welding torch side is the cathode. The above-mentioned positive electrode polarity is sometimes referred to as EP polarity, and negative electrode polarity is sometimes referred to as EN polarity. Furthermore, the polarity ratio of positive electrode polarity to the total polarity time of positive electrode polarity and negative electrode polarity is sometimes referred to as EP ratio, and the polarity ratio of negative electrode polarity is sometimes referred to as EN ratio.

Figure 1 is a schematic diagram showing the configuration of a laser-arc hybrid welding device according to one embodiment of the present invention.

As shown in FIG. 1, a laser-arc hybrid welding device 1 according to one embodiment of the present invention includes a welding torch 10, a welding power supply 30, a laser torch 40, and a laser oscillator 60.

The laser-arc hybrid welding device 1 is used to join metals. The laser-arc hybrid welding device 1 joins two base materials 2 to be joined at the joint 3 using a lap fillet weld joint, a flare weld joint, or the like.

The base material 2 is preferably made of, for example, aluminum or magnesium, or an alloy thereof. It is preferable that the melting point of the surface coating, such as an oxide coating, formed on the surface of the base material 2 is higher than the melting point of the base material 2 itself, and that there is a large temperature difference between the melting points of the base material and the surface coating. The base material 2 may also be made of iron or titanium, or an alloy thereof.

The welding torch 10 and welding power supply 30 are devices used to perform arc welding. The welding torch 10 supplies a welding wire 20 and a shielding gas (not shown) toward the base material 2. The welding torch 10 generates an arc 25 between itself and the workpiece 3 to weld the workpiece 3. Specifically, the welding torch 10 receives a welding current from the welding power supply 30, generates an arc 25 between the tip of the welding wire 20 and the base material 2, and supplies a shielding gas such as argon gas or carbon dioxide toward the base material 2 to weld the workpiece 3.

The welding power supply 30 generates a welding voltage and welding current for arc welding and outputs the generated welding voltage and welding current to the welding torch 10. The welding power supply 30 also controls the feed speed of the welding wire 20 in the welding torch 10.

The welding torch 10 can weld the base material 2 using the welding conditions of positive electrode polarity (EP polarity) and negative electrode polarity (EN polarity).

In EP polarity arc welding, the base material 2 becomes the cathode of the welding current, and cathode spots that are the origin of electron emission concentrate on the base material 2, removing the surface coating of the base material 2. For this reason, EP polarity arc welding is suitable for welding materials that form oxide coatings with melting points that are relatively higher than the melting point of the base material 2 itself.

In EN polarity arc welding, the welding torch 10 acts as the cathode of the welding current, concentrating cathode spots on the welding wire 20 and increasing the amount of melting of the welding wire 20. Therefore, EN polarity arc welding is suitable for welding thin plates because it prevents excessive melting of the base material. Furthermore, in EN polarity arc welding, when there is a gap between one side of the base material and the other side, the welding wire 20 fills the gap, improving the gap tolerance for filling the gap during welding. In other words, EN polarity arc welding has a high welding workability.

The welding torch 10 is configured to change the polarity ratio (EP ratio and EN ratio) of the positive electrode polarity and the negative electrode polarity. The EP ratio and EN ratio can be set as desired using inverter control. When performing AC arc welding, welding is performed by alternating between EP polarity and EN polarity at a polarity ratio set as desired using inverter control.

When the EN ratio is increased, the EP ratio decreases as the EN ratio increases, which reduces the effectiveness of removing the surface coating and may result in arc welding being performed without the surface coating being removed. In this case, humping is more likely to occur during arc welding, which may make arc welding difficult. For this reason, when arc welding base materials such as aluminum or magnesium, it is desirable to maintain the EP ratio at a certain level or above in order to remove the surface coating, which has a higher melting point than the base material. When arc welding base materials such as aluminum or magnesium, welding is performed with an EN ratio of 20% to 30%, for example.

The laser torch 40 irradiates the welded portion 3 with a laser 50, removing the surface coating of the welded portion 3. The laser torch 40 and laser oscillator 60 are devices used to perform welding using the laser 50. The laser torch 40 receives a supply of laser light from the laser oscillator 60, and removes the surface coating of the welded portion 3 by irradiating the welded portion 3 of the base material 2 with the laser 50.

In this embodiment, the method of irradiating the laser 50 onto the parts to be joined 3 is not limited. For example, the laser 50 may be irradiated onto the parts to be joined 3 by diffracting and focusing the laser 50 using a diffractive optical element, by driving a mirror with a motor inside the laser torch 40 to scan the laser 50, or by defocusing the laser 50.

The irradiation of the laser 50 may not only remove the surface coating of the base material 2, but may also melt the base material 2 in conjunction with the arc welding. In particular, when the EN ratio of arc welding in the laser-arc hybrid welding device 1 is increased, the welding wire 20 melts more easily than the base material 2, so the base material 2 can be melted by irradiating it with the laser 50, ensuring the amount of melted base material 2.

Figure 2 is a top view showing the state in which base materials are being welded by a laser-arc hybrid welding device according to an embodiment of the present invention. Figure 3 is a cross-sectional view showing the laser irradiation range and arc welding range on the base materials by a laser-arc hybrid welding device according to an embodiment of the present invention. Figure 4 is a cross-sectional view showing the joined state of base materials welded by a laser-arc hybrid welding device according to an embodiment of the present invention. Note that, for ease of understanding, the welding wire 20, arc 25, and laser 50 are not shown in Figure 2.

As shown in Figures 2 to 4, the base material 2 is composed of a first base material 4 and a second base material 5. A gap G is formed between the first base material 4 and the second base material 5. The first base material 4 and the second base material 5 are welded with an arc 25 and irradiated with a laser 50 along the welding direction (DR1 direction) to join the first base material 4 and the second base material 5 to each other at the joint 3.

The laser 50 is irradiated within the irradiation area 70. The irradiation area 70 of the laser 50 has a width W in a direction perpendicular to the welding direction (DR2 direction). The width W of the irradiation area 70 of the laser 50 in the direction perpendicular to the welding direction (DR2 direction) is between one and two times the leg length L of the welded portion 3. As the laser 50 is irradiated within the irradiation area 70 and travels in the DR1 direction, a laser mark 71 is formed behind the irradiation area 70.

After the laser 50 is irradiated onto the workpiece 3 by the laser torch 40, the workpiece 3 is welded with a negative electrode polarity ratio (EN ratio) of 50% or more in the welding torch 10. The arc 25 melts the first base material 4 and the second base material 5. This forms a molten pool 90 along the DR1 direction, and the workpiece 3 is welded.

The width W of the laser 50 irradiation area 70 in the direction perpendicular to the welding direction (DR2 direction) increases as the electrode negative polarity ratio (EN ratio) increases. By gradually increasing the width W of the laser 50 irradiation area 70 in conjunction with the EN ratio, the area of surface coating removal by laser 50 irradiation is widened, and even if the surface coating removal effect of arc welding decreases due to a decrease in the EP ratio, arc welding can be performed while suppressing the effects of the surface coating.

Figure 5 is a graph showing the relationship between the polarity ratio of the electrode negative polarity and the laser output for arc welding in a laser-arc hybrid welding device according to one embodiment of the present invention.

As shown in Figure 5, the output of the laser 50 of the laser torch 40 increases as the polarity ratio (EN ratio) of the electrode negative polarity increases. In this embodiment, the output of the laser 50 is, for example, 0.5 kW when the EN ratio is 50%. The output of the laser 50 increases in proportion to the EN ratio, and is, for example, 2.0 kW when the EN ratio is 100%. As a result, the removal effect of the surface coating of the base material 2 by the laser 50 becomes stronger as the EN ratio increases. Note that the required output of the laser 50 varies depending on the laser profile of the laser 50, the welding speed, the thickness of the base material, and the joint shape, and is therefore not limited to the output of the laser 50 shown in Figure 5.

Here, we will explain the test results of laser-arc hybrid welding performed on base material using the laser-arc hybrid welding device 1 of this embodiment.

The first and second base materials were each lap fillet joints made of aluminum alloy with a plate thickness of 2 mm. There was a gap of 1 mm between the first and second base materials. EN polarity arc welding was performed at a welding speed of 1 m/min, a welding current of 100 A, and a wire feed speed of 6 m/min. As a result, the base materials did not melt, resulting in humping.

Next, prior to the above arc welding, laser-arc hybrid welding was performed, in which a laser with an average output of 1.0 kW was irradiated. As a result, no humping occurred during welding, and the first and second base materials were satisfactorily joined at the joints. However, with EP polarity arc welding, the first and second base materials could not be joined to each other at the joints, and good welding results could not be obtained. This confirms that laser-arc hybrid welding under the conditions of this embodiment can satisfactorily join first and second aluminum alloy base materials with gaps.

In a laser-arc hybrid welding device 1 according to one embodiment of the present invention, after the laser torch 40 irradiates the workpiece 3 with a laser 50, the workpiece 3 is welded with a negative electrode polarity ratio (EN ratio) of the welding torch 10 of 50% or more. This increases the amount of melted welding wire 20, thereby improving the welding workability while ensuring that the surface coating of the workpiece 3 is removed by irradiating the laser 50.

In a laser-arc hybrid welding device 1 according to one embodiment of the present invention, the output of the laser 50 of the laser torch 40 is increased as the electrode negative polarity ratio (EN ratio) increases, thereby ensuring the removal of surface coatings, which decreases as the electrode positive polarity ratio (EP ratio) decreases.

In a laser-arc hybrid welding device 1 according to one embodiment of the present invention, the width W of the laser 50 irradiation area in the direction perpendicular to the welding direction (DR2 direction) is increased as the electrode negative polarity ratio (EN ratio) increases, thereby removing a sufficient amount of the surface coating caused by the laser 50 irradiation and suppressing humping in the arc welding.

In a laser-arc hybrid welding device 1 according to one embodiment of the present invention, the width W of the irradiation area 70 of the laser 50 in the direction perpendicular to the welding direction (direction DR2) is between one and two times the leg length L of the welded portion 3. By irradiating the laser 50 with the appropriate width W, the removal of the surface coating by irradiation with the laser 50 can be ensured.

The following describes a laser-arc hybrid welding device according to a modified example of an embodiment of the present invention. Because the welding conditions for the welding torch of the laser-arc hybrid welding device according to this modified example differ from those of the laser-arc hybrid welding device 1 according to an embodiment of the present invention, a description of the configuration that is similar to that of the laser-arc hybrid welding device 1 according to an embodiment of the present invention will not be repeated.

A welding torch according to a modified embodiment of the present invention welds the parts to be joined with an electrode negative polarity ratio (EN ratio) of 70% or more. If the EN ratio exceeds 70%, cathode spots in the arc welding are generated at the tip and sides of the welding wire, making droplet formation unstable when the welding wire melts. If the arc welding is pulse welding, the pulse current cycle becomes unstable, which can make the welding unstable and result in spatter.

The welding performed by the welding torch in this modified example is short-circuit welding. By short-circuit welding, the molten droplets of the welding wire are brought into contact with the welding wire and the base material while welding, which prevents spatter from occurring during welding compared to pulse welding.

In a laser-arc hybrid welding device according to a modified embodiment of the present invention, the parts to be welded are welded with a negative electrode polarity ratio (EN ratio) of the welding torch of 70% or more, and the welding torch is short-circuited. This allows for the removal of surface coatings and ensures welding workability, while suppressing the generation of spatter through short-circuit welding.

The above-disclosed embodiments are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of this disclosure should not be interpreted solely in terms of the above-disclosed embodiments. Furthermore, all modifications within the scope and meaning equivalent to the claims are included. In the description of the above-disclosed embodiments, combinable configurations may be combined with each other.

1: Laser-arc hybrid welding device, 3: welding part, 10: welding torch, 25: arc, 40: laser torch, 50: laser, 70: irradiation area, L: leg length, W: width.

Claims (5)

a laser torch that irradiates a laser toward a portion to be joined and removes a surface coating of the portion to be joined;
a welding torch that generates an arc between the welding torch and the welding parts to weld the welding parts,
the welding torch is configured to be able to change the polarity ratio of the electrode positive polarity and the electrode negative polarity,
a laser-arc hybrid welding device that irradiates the laser torch with the laser and then welds the parts to be joined with the polarity ratio of the electrode negative polarity in the welding torch being 50% or more; The laser-arc hybrid welding device of claim 1, wherein the laser output of the laser torch increases as the polarity ratio of the electrode negative polarity increases. A laser-arc hybrid welding device as described in claim 1 or 2, wherein the width of the laser irradiation area in a direction perpendicular to the welding direction increases as the polarity ratio of the electrode negative polarity increases. The laser-arc hybrid welding device of claim 3, wherein the width of the laser irradiation area in a direction perpendicular to the welding direction is between one and two times the leg length of the welded part. the welding torch welds the joint portion with the polarity ratio of the electrode negative polarity being 70% or more,
5. The laser-arc hybrid welding device according to claim 1, wherein the welding torch performs short-circuit welding.