JP2000233289A - Aluminum alloy welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding method of an aluminum alloy capable of increasing a processing energy while maintaining a stable welding process, deepening a penetration amount of a welded portion and stably obtaining a high joint strength. I will provide a. When a plurality of high-energy beams, for example, laser beams B1 and B2 are applied to a workpiece P1 and P2 for welding, the distance w between the beams is set to 1.5 times the beam diameter d.
Weld in the range of 2 to 2.6 times. When the number of beams is three or more, welding is performed with the relationship between the distance w between the closest beams and the beam diameter d set in the above range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for welding an aluminum alloy using a high energy beam such as a laser beam or an electron beam, and more particularly, to welding of an aluminum plate, an extruded material, or an aluminum casting. The present invention relates to a method for welding an aluminum alloy that can stably maintain a welding process even when the processing energy is increased and can obtain a weld bead having a deep penetration.

[0002]

2. Description of the Related Art For example, when an aluminum alloy is used as a structural member of an automobile, when a high energy beam such as a laser beam or an electron beam is applied as a welding energy source in manufacturing or assembling these members, MIG welding is performed. It is possible to perform welding at a higher speed as compared with TIG welding or TIG welding, and it is possible to expect an effect that a welding time can be shortened and thermal distortion can be reduced.

However, aluminum alloys have a higher thermal conductivity and reflectivity than steel materials and the like. Therefore, if the processing energy is not increased during welding, a deep penetration cannot be obtained, and sufficient joint strength can be obtained. It is difficult.

[0004] However, if the machining energy is simply increased, the amount of penetration increases, but the welding process becomes unstable, spatters are generated, and pores remain in the weld bead. However, it has been a problem in welding aluminum alloys by such a high-energy beam to solve such problems.

[0005] For example, Japanese Unexamined Patent Publication No. 10-137965 discloses a method and an apparatus for welding using a plurality of beams, but these are apparatuses for making a plurality of beams at a processing point. No method has been considered for stabilizing the welding process, because it is a method of simultaneously performing a plurality of processes by using a plurality of beams.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional aluminum alloy welding technique using a high-energy beam, and can increase the processing energy while maintaining a stable welding process. It is an object of the present invention to provide a method for welding an aluminum alloy in which the amount of penetration of a weld portion is deepened and a high joint strength can be stably obtained.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted various studies on irradiation conditions of a high energy beam for the purpose of solving the above problems, and as a result, split the high energy beam into two or more. At the same time, it has been found that by maintaining the distance between the beams in a predetermined range, mutual interference of the beams can be prevented, the welding process can be stabilized, and the penetration amount can be increased by the synergistic action of the beams.

The present invention is based on such knowledge, and the method for welding an aluminum alloy according to claim 1 of the present invention welds the aluminum alloy by irradiating the aluminum alloy with a plurality of high energy beams. At this time, when the distance at the processing point between the closest beams of the plurality of high energy beams is w, and the beam diameters at the processing points of the two beams are d, the ratio w / d
Is set in the range of 1.5 to 2.6, and such a configuration in a method of welding an aluminum alloy is used as means for solving the above-described conventional problem.

In an embodiment of the welding method for an aluminum alloy according to the present invention, when the two beams are arranged in parallel in a direction substantially parallel to the welding progress direction, the distance between the beams w and the beam diameter d are determined. When the ratio w / d is in the range of 1.5 to 2.3, and the two beams are arranged in parallel in a direction substantially orthogonal to the welding progress direction, the ratio w / d is set to 1.5.
In the method of welding an aluminum alloy according to claim 3, the power density of each of the high energy beams is set to 200 or less.
A configuration to 00W / mm ² or more, according to a structure high-energy beam is a laser beam in the welding method of an aluminum alloy according to claim 4, the laser beam in the welding method of an aluminum alloy according to claim 5 is Y
It is characterized in that it is configured to be an AG laser beam.

According to another aspect of the present invention, a plurality of laser beams are formed by transmitting laser beams oscillated from a plurality of laser oscillators through a plurality of optical fibers. In the aluminum alloy welding method according to claim 7, the laser beam oscillated from one laser oscillator and transmitted through one optical fiber is transmitted by a prism optical system provided in the welding head. A plurality of laser beams are formed by branching, and as an embodiment, in the welding method according to claim 8, the aluminum alloy is an alloy containing a low boiling element such as magnesium or zinc.
Is characterized in that the welded joint is a lap welded joint and the plate thickness on the side irradiated with the high energy beam is in the range of 0.6 mm to 3.0 mm. Such a configuration in the above welding method is used as means for solving the above-mentioned conventional problems.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for welding an aluminum alloy according to the present invention employs a method of irradiating a high energy beam such as a laser beam or an electron beam to an aluminum alloy, as shown in FIG. The two beams B1 and B2 are irradiated, and both beams B1 and B2
The distance w between B2 is maintained in a predetermined range, that is, 1.5 to 2.6 times the diameter d of the beam spots S1 and S2 of the two beams B1 and B2 at the processing point as shown in FIG. By doing so, both the stabilization of the welding process and the increase in the amount of penetration are achieved, and the two beams B1,
When the ratio w / d of the distance w between B2 and the beam diameter d is less than 1.5, the positional relationship between the beams is relatively narrowed, which is close to the phenomenon when single beam welding with a large power density is performed. As a result, it becomes difficult to discharge the shielding gas trapped in the molten metal part, the metal gas evaporated in the molten metal vigorously activates, remains as a hole in the welding bead, or disturbs the surface of the welding bead. As a result, the strength of the weld decreases. On the other hand, when the ratio w / d exceeds 2.6, the positional relationship between the beams is relatively widened and the influence of each beam is weakened, so that a sufficient amount of penetration cannot be obtained. The strength of the weld will be reduced.

The direction in which the beams are arranged is not particularly limited, but as described in claim 2, the two beams B1, B2 are arranged in parallel or substantially parallel to the welding progress direction. (See FIG. 2A), the ratio w / d of the distance w between beams and the beam diameter d is set to 1.5 to
2.3, and when both beams B1 and B2 are parallel to each other in a direction perpendicular or substantially perpendicular to the welding progress direction (see FIG. 2B), the distance w between the beams and the beam Welding with the ratio w / d of the diameter d in the range of 1.5 to 2.6 is desirable from the viewpoint of increasing the amount of penetration and more reliably improving the strength of the welded portion.

The welding method according to the present invention is applicable not only to the case where the number of high energy beams is two, but also to the case where the number of beams is three or four or more as shown in FIGS. , Where the closest beams B1 and B1 of these beams are
By setting the positional relationship (w / d) between the two in the above range, the same function and effect can be obtained.

The power density of the high energy beam in the welding method according to the present invention is desirably set to 20000 W / mm ² or more. That is, the power density of each of the high energy beams applied to the workpiece is 20,000 W / mm.
If the ratio is less than ² , there is a tendency that a deep penetration cannot be stably obtained. In this case, it is not always necessary to make the power densities of a plurality of beams equal.

In the method for welding an aluminum alloy according to the present invention, since there is no attenuation or spread in the atmosphere and light can be condensed at an arbitrary position by a simple optical system,
As described in claim 4, it is desirable to use a laser beam as the high energy beam, and furthermore, the power consumption is small, the device can be downsized, and the optical fiber can be used and the handling is easy. As described in claim 4, it is desirable to apply a YAG laser.

When a laser beam, especially a YAG laser, is used as the high energy beam, for example, as shown in FIG. 4A, a laser beam B1 oscillated from a plurality of laser oscillators (two in the figure). , B2 are transmitted to the welding head 3 via a plurality of optical fibers 2a and 2b, respectively.
By condensing the beam spots S1 and S2 on the processing point using the optical system including the focusing lens 5, a plurality of laser beams B1 and B2 can be irradiated to the workpiece. Further, as shown in FIG. 4B, a laser beam B oscillated from one laser oscillator
Is transmitted to the welding head 3 via one optical fiber 2,
After forming a parallel beam by the collimation lens 4 in the welding head 3, the beam B is split by the semicircular prism lens 6, and further focused on the processing point by the focusing lens 5 as beam spots S 1 and S 2. Thereby, a plurality of laser beams B1 and B2 can be irradiated to the workpiece. In this case, the distance w between beams can be controlled by moving the position of the prism lens 6 closer to or away from the focusing lens 5.

According to the method for welding an aluminum alloy according to the present invention, an aluminum alloy containing an element having a lower boiling point than aluminum, such as magnesium or zinc, as an additional element, ,
Alloy number 5000 series specified in JIS or 70
When applied to a 00-based alloy or the like, the characteristics can be more effectively utilized. That is, in high-energy beam welding of a material containing such a low-boiling element, these gases evaporated in the molten metal not only make the welding process unstable, but also remain as pores in the weld bead and have a high strength. In the conventional single-beam welding, it is extremely difficult to obtain a deep penetration amount by applying high energy because of the lowering. However, by applying the welding method according to the present invention, such welding is performed. The welding process can be stably maintained even in an aluminum alloy containing a low-boiling element, and a weld bead having a deep penetration amount can be obtained.

When the method for welding an aluminum alloy according to the present invention is applied to, for example, lap welding, the thickness of the material to be welded is 0.6 m or less.
A range from m to 3.0 mm is preferred. That is, when the material to be welded has a thickness of less than 0.6 mm, it is possible to obtain stable welding and sufficient penetration by conventional single beam welding without applying the welding method of the present invention. In the case of a material to be welded having a thickness exceeding 0.0 mm, the penetration width of the weld bead at the boundary between the upper and lower plates must be 3.0 mm or more in order to obtain sufficient joint strength. In order to obtain such a welding width in an aluminum alloy having a high welding power, energy waste increases, and the merit of applying high energy beam welding to lap welding decreases.

[0019]

According to the method for welding an aluminum alloy according to the first aspect of the present invention, when irradiating a plurality of high energy beams to a material to be welded, the distance w between the closest beams at the processing point and the beam diameter d are determined. Of 1.5 to 2.
Since the welding is performed in the range of 6, the welding process can be stably maintained despite the high total processing energy, and the penetration amount of the welded portion is deepened to stably obtain high joint strength. This is an extremely excellent effect of being able to do so.

In the welding method according to the second aspect of the present invention, when the two beams closest to each other are arranged in parallel in a direction substantially parallel to the welding progress direction, the distance w between the beams and the beam diameter are determined. The ratio w / d of d is set in the range of 1.5 to 2.3, and when juxtaposed in a substantially orthogonal direction, welding is performed with the ratio w / d in the range of 1.5 to 2.6. By increasing the amount, the strength of the welded portion can be more reliably improved. Similarly, in the aluminum alloy welding method according to the third aspect, the power density of the high energy beam is set to 20000 W / mm ² or more. And a deep penetration amount can be stably obtained. In the method for welding an aluminum alloy according to claim 4, a laser beam is used as a high energy beam. Since the use, it can be easily focused on an arbitrary position by the optical system,
Further, in the welding method according to the fifth aspect, since a YAG laser beam is particularly used as the laser beam, it is possible to use a small apparatus with low power consumption and to use the optical fiber very easily because the optical fiber can be used. This is an excellent effect.

Further, in the method for welding an aluminum alloy according to claim 6, a plurality of laser beams are obtained by transmitting laser beams oscillated from a plurality of laser oscillators through a plurality of optical fibers, respectively. Therefore, the degree of freedom in adjusting power density, beam diameter, distance between beams, and the like can be increased, and in the welding method according to claim 7, a plurality of laser beams are oscillated from one laser oscillator. Since the beam is transmitted to the welding head via one optical fiber and split by the prism optical system in the welding head into a plurality of beams, the cost of the welding apparatus can be reduced. In the welding method related to No. 8, the aluminum alloy is an alloy containing low boiling elements such as magnesium and zinc. By utilizing the features of the welding method of the present invention, it is possible to apply high-energy beam welding to a material that was difficult to weld by the conventional method. When the method is applied to lap welding, the thickness of the side irradiated with the high energy beam is set in the range of 0.6 mm to 3.0 mm. And a more excellent effect that cost performance can be improved.

[0022]

EXAMPLES The present invention will be described below more specifically based on examples.

Aluminum alloy A51 having a thickness of 2.0 mm
82-O material (4.5% Mg-0.3% Mn) P1, P2
Are superposed and irradiated with two laser beams B1 and B2 from above as high energy beams to overlap and weld the aluminum alloys P1 and P2 to each other. The influence of the ratio w / d of the beam diameter d was investigated.

That is, FIG. 1A shows the welding situation, and as shown in FIG.
Laser beam B1 oscillated from two AG laser oscillators
, B2 are guided into the welding head 3 via the two optical fibers 2a, 2b, respectively, and are processed on the workpieces P1, P2 by the optical system (collimation lens 4, focusing lens 5) provided in the welding head 3. Welding was performed by condensing the spots as beam spots S1 and S2.

At this time, the laser output from the YAG laser oscillator is 2 kW (4 kW in total), and the beam diameter d is 0.3 mm (about 28,000).
W / mm ² ) and 0.35 mm (about 20800 W / mm
² ) Two levels were adopted. For welding speed, both beams B
When 1 and B2 are closest to each other (w = 0.36 mm)
And two superposed aluminum alloy materials P1 and P2
The welding speed to penetrate through was determined in advance, and the welding speed was fixed at 3.5 m / min.

Then, as shown in FIG. 2A, the two beams B1 and B2 are serial beams arranged substantially in parallel to the welding progress direction, and as shown in FIG. In the case of two parallel beams in which the two beams B1 and B2 were arranged in a direction substantially perpendicular to the welding progress direction, the relationship between the beam strength and the joint strength when the beam distance w was variously changed was examined.

FIG. 5 shows the result. When the ratio w / d between the beam distance w and the beam diameter d is small, the welding process becomes unstable, and the front side and the back side of the weld bead become instable. And appearance of holes in the weld bead were observed, resulting in a slightly lower joint strength.

On the other hand, when the ratio w / d is large, the penetration depth becomes shallow, especially when both beams B1 and B2 are arranged in the welding progress direction (serial beam). As a result, the joint strength was significantly reduced.
The appropriate range of w / d for securing the joint strength is that the beam diameter d is 0.3 mm or 0.35 mm. In each case, 1.5 to 2.3 for the serial beam and 1 for the parallel beam. 0.5 to 2.6.

[Brief description of the drawings]

FIG. 1A is a perspective view showing an example of a welding situation in a method for welding aluminum according to the present invention. FIG. 2B is an enlarged view illustrating a relationship between a beam distance and a beam diameter in FIG.

FIGS. 2A and 2B are schematic explanatory diagrams showing variations in the arrangement direction of both beams.

FIGS. 3A to 3E are schematic explanatory diagrams showing variations of the number of beams and examples of arrangement of respective beams.

FIG. 4 (a) is an explanatory view showing one example of a method of forming a plurality of beams in the method for welding aluminum according to the present invention. (A) It is explanatory drawing which shows the other example of the formation method of the multiple beam in the welding method of aluminum which concerns on this invention.

FIG. 5 shows the ratio (w //) of the distance between beams and the beam diameter on the joint strength in the method for welding aluminum according to the present invention.
It is a graph which shows the influence of d).

[Explanation of symbols]

 2, 2a, 2b Optical fiber 3 Welding head B, B1, B2 Laser beam (high energy beam) P1, P2 Material to be welded (aluminum alloy) w Distance between beams d Beam diameter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23K 26/06 B23K 26/06 G 26/08 26/08 K // B23K 103: 10 (72) Inventor Minoru Kasukawa F-term (reference) 4F066 AB04 BA11 BB01 CA11 CB10 4E068 BA01 BF00 CA01 CD02 CD04 CD09 CE08 DA14 DB04 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture

Claims (9)

[Claims] When irradiating an aluminum alloy by irradiating the aluminum alloy with a plurality of high energy beams, a distance at a processing point between the closest beams among the plurality of high energy beams is defined as w, Assuming that the beam diameter at the processing point is d, the ratio w of the two is
A method for welding an aluminum alloy, wherein / d is set in a range of 1.5 to 2.6. 2. When the two beams are arranged side by side in a direction substantially parallel to the welding progress direction, the ratio w / d of the distance w between the beams and the beam diameter d is in the range of 1.5 to 2.3, and the two beams are welded. When juxtaposed in a direction substantially perpendicular to the traveling direction, the ratio w /
2. The method according to claim 1, wherein d is in the range of 1.5 to 2.6. 3. The method for welding an aluminum alloy according to claim 1, wherein the power density of each of the high energy beams is 20,000 W / mm ² or more. 4. The method for welding aluminum alloy according to claim 1, wherein the high energy beam is a laser beam. 5. The method according to claim 4, wherein the laser beam is a YAG laser beam. 6. The method for welding an aluminum alloy according to claim 5, wherein a plurality of laser beams are formed by transmitting laser beams emitted from a plurality of laser oscillators through a plurality of optical fibers, respectively. . 7. A laser beam oscillated from one laser oscillator and transmitted via one optical fiber is split by a prism optical system provided in a welding head to form a plurality of laser beams. The method for welding an aluminum alloy according to claim 5, wherein 8. The method for welding an aluminum alloy according to claim 1, wherein the aluminum alloy is an alloy containing a low-boiling element such as magnesium or zinc. 9. The weld joint is a lap weld joint,
The plate thickness on the side irradiated with the high energy beam is 0.6mm ~
The method for welding an aluminum alloy according to any one of claims 1 to 8, wherein the distance is in a range of 3.0 mm.