JP7386118B2 - Welding method and welding equipment - Google Patents

Description

The present invention relates to a welding method and a welding device.

Japanese Unexamined Patent Publication No. 2011-5499 (Patent Document 1) discloses a method for butt laser welding of an aluminum member and a copper member.

In this laser welding method, when welding aluminum and copper using a CO2 laser, YAG laser, or fiber laser, the laser beam is irradiated so that the irradiation area on aluminum is larger than the irradiation area on copper. Moreover, a welding method is described in which, as the center position of the laser beam irradiation area, the center position of the beam outer diameter D is moved toward the aluminum member side by an offset amount d (d<D) from the abutting portion of the base materials.

Japanese Patent Application Publication No. 2011-5499

In Japanese Patent Application Laid-Open No. 2011-5499, copper members have a higher melting point than aluminum members, but because they have a high light reflectance and are difficult to melt by laser beams, welding is performed by bringing the copper closer to the aluminum member and transferring heat from the aluminum. It is proposed that.

In recent years, the output of blue semiconductor lasers has improved, and their application to metal welding is being considered. However, since the laser beam characteristics of a blue semiconductor laser are different from those of a YAG laser or the like, further consideration is required for laser welding using a blue semiconductor laser.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a welding method that can successfully weld dissimilar metals such as an aluminum member and a copper member using a blue semiconductor laser. An object of the present invention is to provide a method and a welding device.

The welding method of the present disclosure includes a step of placing an aluminum member and a copper member abutting each other, and a step of irradiating a laser beam around the abutting portion of the aluminum member and the copper member to perform welding. The laser light is a trapezoidal beam obtained by shaping a Gaussian beam emitted from a laser head that outputs blue semiconductor laser light using a diffractive optical element. In the welding step, the laser beam is irradiated so that the entire irradiation spot of the laser beam is included on the aluminum member side from the butt boundary line between the aluminum member and the copper member.

By adjusting the position of the irradiation spot in this way, it is possible to prevent the copper member from melting down and forming a hole when butt welding a copper member and an aluminum member using a blue semiconductor laser.

Preferably, in the welding step, the laser beam is irradiated such that the center of the irradiation spot is offset toward the aluminum member by more than half of the effective diameter of the laser beam from the abutting boundary between the aluminum member and the copper member.

By determining the position of the irradiation spot in this manner, a good weld bead is formed when a copper member and an aluminum member are butt welded using a blue semiconductor laser.

The welding device of the present disclosure includes a laser head that outputs a laser beam, a head position adjustment unit that adjusts the position of the laser head, a detection unit that detects a butt boundary line between an aluminum member and a copper member, and a detection unit that detects and a control device that controls the head position adjustment section based on the matching boundary line. The laser light is a blue semiconductor laser light. The control device controls the head position adjustment unit so that the laser beam is irradiated so that the entire irradiation spot of the laser beam is included on the aluminum member side from the abutting boundary line between the aluminum member and the copper member. The laser head emits a Gaussian beam. The welding device further includes a diffractive optical element that shapes the Gaussian beam emitted from the laser head into a trapezoidal beam and irradiates the aluminum member with the trapezoidal beam.

By adjusting the position of the irradiation spot in this way, it is possible to prevent the copper member from melting down and forming a hole when butt welding a copper member and an aluminum member using a blue semiconductor laser. Furthermore, since the trapezoidal beam is irradiated onto the aluminum member, it is possible to uniformly heat the aluminum member, and it is possible to suppress the aluminum member from melting down before welding with the copper member due to heat transfer occurs.

Preferably, the control device controls the head position adjustment unit so that the center of the irradiation spot is offset toward the aluminum member by more than half of the effective diameter of the laser beam from the abutting boundary between the aluminum member and the copper member.

By determining the position of the irradiation spot in this manner, a good weld bead is formed when a copper member and an aluminum member are butt welded using a blue semiconductor laser.

According to the welding method of the present disclosure, by adjusting the position of the irradiation spot to be removed from the copper member, when butt welding a copper member and an aluminum member using a blue semiconductor laser, the copper member melts through. This can prevent holes from forming.

FIG. 1 is a diagram showing the configuration of a welding device according to the present embodiment. FIG. 3 is a cross-sectional view for explaining the irradiation position of a laser beam. FIG. 3 is a top view for explaining the position of a laser beam. FIG. 2 is a diagram showing the relationship between laser wavelength and absorption rate for aluminum and copper. FIG. 7 is a diagram for explaining irradiation positions in a study example. FIG. 3 is a diagram for explaining an example of welding in which a problem occurs. FIG. 7 is a diagram for explaining laser beam irradiation in Embodiment 2. FIG. FIG. 3 is a schematic diagram showing the positional relationship between the joining position of an aluminum member and a copper member and beam energy in the case of a trapezoidal beam. FIG. 3 is a schematic diagram showing the positional relationship between the joining position of an aluminum member and a copper member and beam energy in the case of a Gaussian beam.

Embodiments of the present invention will be described in detail below with reference to the drawings. Although a plurality of embodiments will be described below, it has been planned from the beginning of the application to appropriately combine the configurations described in each embodiment. In addition, the same reference numerals are attached to the same or corresponding parts in the drawings, and the description thereof will not be repeated.

[Embodiment 1]
FIG. 1 is a diagram showing the configuration of a welding apparatus according to the present embodiment. Referring to FIG. 1, the welding apparatus includes a position detection section 12, a laser head 14, a head position adjustment section 13, and a control device 11.

The position detection unit 12 detects the butt boundary line 4 between the aluminum member 2 and the copper member 3. The head position adjustment section 13 adjusts the position or irradiation angle of the laser head 14. For example, the position detection unit 12 is a device that detects the butt boundary line 4 for the laser beam 1 to follow. The control device 11 controls the head position adjustment section 13 to adjust the position of the laser beam, and also controls the laser head 14 so that welding is performed along the butt boundary line 4 detected by the position detection section 12. to irradiate the laser beam 1. For example, the head position adjustment unit 13 is a device that is mounted on a welding cart or the like and aligns the position of the laser head 14 along the butt boundary line 4 in conjunction with the movement of the welding part. Note that the head position adjustment section 13 may include a manipulator.

FIG. 2 is a cross-sectional view for explaining the irradiation position of the laser beam. FIG. 3 is a top view for explaining the position of the laser beam. FIG. 2 shows a cross section taken along line II-II in FIG.

Laser light 1 is a blue semiconductor laser light. The control device 11 adjusts the head position so that the laser beam 1 is irradiated so that the entire irradiation spot 10 of the laser beam 1 is included on the aluminum member 2 side from the butt boundary line 4 of the aluminum member 2 and the copper member 3. control section 13.

By adjusting the position of the irradiation spot 10 in this way, when the copper member 3 and the aluminum member 2 are butt welded using the blue semiconductor laser, the copper member 3 melts down and holes are formed, as will be explained later. You can prevent it from drying out.

The control device 11 adjusts the head position so that the center of the irradiation spot 10 is offset from the butt boundary line 4 of the aluminum member 2 and copper member 3 toward the aluminum member by more than D/2, which is half of the effective diameter D of the laser beam. control section 13.

By determining the position of the irradiation spot 10 in this way, a good weld bead is formed when the copper member 3 and the aluminum member 2 are butt-welded using the blue semiconductor laser.

The reason for determining the irradiation position as described above will be explained below. FIG. 4 is a diagram showing the relationship between laser wavelength and absorption rate for aluminum and copper. In FIG. 4, the horizontal axis shows the laser wavelength (μm), and the vertical axis shows the absorption rate (%).

In the case of butt laser welding the aluminum member 2 and the copper member 3, it has been proposed to use a CO2 laser (wavelength 10.6 μm), a YAG laser (wavelength 1064 nm), or a fiber laser (wavelength 1064 nm). A welding method using a laser (wavelength: 455 nm) is not known.

In this embodiment, an irradiation method for butt laser welding of an aluminum member 2 and a copper member 3 using a blue laser is proposed.

The melting points of aluminum and copper are 660°C and 1084.5°C, respectively. In general, in order to heat a copper member with a high melting point to a large extent, it is conceivable to irradiate a laser spot close to the copper. However, in the case of a conventional laser beam, such as a fiber laser, the wavelength of the fiber laser is 1064 nm, so the heat absorption rates of aluminum and copper are 18% and 5%, respectively, as shown in FIG. Therefore, even if a copper member is irradiated with a laser, the heat generation efficiency is low, and a high output laser is required. Therefore, in Patent Document 1, the irradiation area on the aluminum member is set to be larger than the irradiation area on the copper member. is irradiated with laser light, and the center position of the beam outer diameter D of the laser light beam is shifted by an offset amount d (d<D) from the abutting portion of the base materials to the aluminum member side.

When butt welding is performed using a blue laser as the laser beam, the heat absorption rates of aluminum and copper are 18% and 45% at the wavelength of the blue laser of 455 nm.

The absorption rate of copper in FIG. 4 was 10% or less in the case of a fiber laser (approximately 1 μm). In fiber lasers and blue lasers, the magnitude relationship between the absorption rates of copper and aluminum is reversed.

FIG. 5 is a diagram for explaining the irradiation position in the study example. FIG. 6 is a diagram for explaining a welding example in which a problem occurs. Consider the case where an aluminum member and a copper member are irradiated with blue laser energy as shown in FIG. In this case, the heat absorption rate of copper is greater than that of aluminum compared to conventional wavelengths. Therefore, excessive melting occurs in the copper portion of the joint due to laser irradiation. Then, as shown in FIG. 6, there is a possibility that after the aluminum has been melted, the welded portion will melt through and create a hole due to the heating in the copper region and the erosion caused by the melting of the aluminum before joining.

Therefore, as shown in FIGS. 2 and 3, in the welding method shown in this embodiment, after the aluminum member 2 and the copper member 3 are placed in abutted state, the entire irradiation spot 10 of the laser beam 1 is Laser light 1 is irradiated from a butt boundary line 4 between aluminum member 2 and copper member 3 so as to be included on the aluminum member 2 side. Laser light 1 is a blue semiconductor laser.

By adjusting the position of the irradiation spot 10 in this way, when the copper member 3 and the aluminum member 2 are butt welded using the blue semiconductor laser, it is possible to prevent the copper member 3 from melting down and forming a hole. I can do it.

The laser beam 1 is irradiated so that the center of the irradiation spot 10 is offset toward the aluminum member 2 by more than half (2/D) of the effective diameter D of the laser beam 1 from the butt boundary line 4 of the aluminum member 2 and copper member 3. be done.

Here, the aluminum member 2 having a low melting point melts. The heat of melting aluminum is transferred to the copper member 3, and the temperature of the copper member 3 increases due to the heat transfer from the molten aluminum. Then, when the temperature rise of the copper member 3 reaches the melting point, the copper member 3 sequentially melts starting from the abutting portion. When aluminum melts, the melting point of copper is reached at the junction due to thermal energy transferred from the molten aluminum, and the copper member 3 is melted.

As a result of the above, the copper member is melted by heat transfer from the molten aluminum. Then, the molten aluminum and copper form a keyhole (molten pool) centered on the laser beam irradiation area. After the keyhole is formed, if the laser is moved, a bead is formed by rapid cooling.

By determining the position of the irradiation spot 10 in this way, a good weld bead is formed when the copper member 3 and the aluminum member 2 are butt-welded using the blue semiconductor laser.

As described above, this embodiment is characterized in that in laser welding using a blue laser, the effective diameter of the laser beam is irradiated only on the aluminum member at the boundary between the aluminum member and the copper member.

For example, the effective diameter can be 1/e ² width. The 1/e ² width defines the effective diameter up to a portion that is 1/e ² =0.135 times the maximum value. Note that as other effective diameters, half-power beam width (HPBW), D4σ width, knife edge width, D86 width, etc. may be adopted.

Note that when 1/e ² width is adopted, the energy distribution of the laser beam is a Gaussian distribution, so energy of about 1/e ² (about 13%) of the peak intensity is irradiated even outside the effective range of the beam. Therefore, the copper member is irradiated with a component slightly outside the effective range of the laser beam.

After the aluminum member is melted, the copper member is eroded, and although the copper member does not melt due to the influence of the Gaussian beam, the aluminum is more likely to erode into the copper due to heat absorption by the laser beam. ing. Thereby, the aluminum member and the copper member can be efficiently joined.

[Embodiment 2]
FIG. 7 is a diagram for explaining laser beam irradiation in the second embodiment. The welding device in the second embodiment includes a diffraction grating 21 in addition to the configuration of the welding device shown in FIG. When the laser beam 1 having a Gaussian distribution passes through the diffraction grating 21, it is shaped into a trapezoid (top hat). The trapezoidal shaped beam irradiates the aluminum member 2.

Since the irradiation beam changes from a Gaussian beam to a trapezoidal beam due to the diffraction grating 21, heat absorption into the copper member 3 can be made smaller than that of a Gaussian beam, and the spread of erosion from the aluminum member 2 to the copper member 3 can be reduced. Can be reduced.

A trapezoidal beam and a Gaussian beam are compared and shown using FIGS. 8 and 9. FIG. 8 is a schematic diagram showing the positional relationship between the joining position of the aluminum member and the copper member and the beam energy in the case of a trapezoidal beam. FIG. 9 is a schematic diagram showing the positional relationship between the joining position of the aluminum member and the copper member and the beam energy in the case of a Gaussian beam.

It can be seen that the energy spread to the copper member is smaller in the trapezoidal beam shown in FIG. 8 than in the Gaussian beam shown in FIG. 9. Therefore, in the case of a Gaussian beam, precise control of the irradiation offset is required to minimize copper melting, but with a trapezoidal beam, there is less risk of melting due to heat absorption of the copper, so the irradiation offset can be controlled. Control becomes easier. Since the amount of shift from the boundary portion to the aluminum member 2 can be made larger than 1/2 of the effective diameter D, the setting becomes easy.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the description of the embodiments described above, and it is intended that all changes within the meaning and range equivalent to the claims are included.

Reference Signs List 1 laser beam, 2 aluminum member, 3 copper member, 4 boundary line, 10 irradiation spot, 11 control device, 12 position detection section, 13 head position adjustment section, 14 laser head, 21 diffraction grating.

Claims (4)

placing the aluminum member and the copper member against each other;
irradiating a laser beam around the abutting portion of the aluminum member and the copper member to weld;
The laser light is a trapezoidal beam obtained by shaping a Gaussian beam emitted from a laser head that outputs blue semiconductor laser light by a diffractive optical element,
In the welding step, the laser beam is irradiated so that the entire irradiation spot of the laser beam is included on the aluminum member side from the butt boundary line of the aluminum member and the copper member. In the welding step, the laser beam is irradiated such that the center of the irradiation spot is offset toward the aluminum member by more than half the effective diameter of the laser beam from the butt boundary line between the aluminum member and the copper member. , The welding method according to claim 1. a laser head that outputs laser light;
a head position adjustment section that adjusts the position of the laser head;
a control device that controls the head position adjustment section with reference to the butt boundary line between the aluminum member and the copper member;
The laser light is a blue semiconductor laser light,
The control device controls the head position adjustment unit so that the laser beam is irradiated so that the entire irradiation spot of the laser beam is included on the aluminum member side from the butt boundary line between the aluminum member and the copper member. configured to control
The laser head emits a Gaussian beam,
The welding apparatus further includes a diffractive optical element that shapes the Gaussian beam emitted from the laser head into a trapezoidal beam and irradiates the aluminum member with the trapezoidal beam. The control device controls the head position adjustment unit so that the center of the irradiation spot is offset toward the aluminum member by more than half the effective diameter of the laser beam from the butt boundary line between the aluminum member and the copper member. , The welding device according to claim 3.

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