JPH0825046B2 - Laser welding method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laser welding method of abutting two plate materials and moving them while irradiating laser light along the abutting line while welding them.

[Prior art]

The energy density of the laser light, that is, the energy of the laser light is distributed symmetrically with respect to the optical axis within the diameter of the laser light, as shown in FIG. Therefore, as shown in FIG. 5, when two plate materials 1 and 2 are butted and the butted line 3 is irradiated with the laser beam 4, uniform energy is distributed to both sides of the butted line 3.

There is no problem if the two plate materials 1 and 2 have the same thickness, but
As shown in the figure, when the plate thickness is different, or when the plate thickness difference partially occurs due to the plate thickness variation,
Since the energy for melting the thick plate side (plate material 1) is relatively insufficient, it does not melt sufficiently compared to the thin plate side (plate material 2),
As shown in FIG. 6, the shape of the welded portion 6 has a step 5 with an acute angle.

[Problems to be solved by the invention]

However, in the shape of the welded portion having the sharp step 5, there is a problem of die scuffing in that the portion of the sharp step 5 is galled by a press molding die (not shown) during the post-press molding. Further, when a force is applied to the product obtained by press molding, stress concentration is remarkable due to the lack of relative energy, resulting in a problem that strength is reduced.

It is an object of the present invention to provide a laser welding method that provides a smooth welded portion shape without sharp-angled steps, and solves the problem of mold galling and the problem of strength reduction due to stress concentration.

[Means and Actions for Solving Problems]

According to the present invention, the surfaces of one of the two plate members having different plate thicknesses are abutted to each other while being displaced from each other, and are welded by moving along the abutting line while irradiating the laser beam from the surface side of the one side. In the laser welding method,
The energy of the laser beam applied to the thick plate material is made larger than the energy of the small plate material so that the corners formed at the abutting portions of the large plate material and the small plate material Welding the two plates while melting, especially by tilting the condenser lens that receives the laser beam to focus and irradiate the welded part, the energy of the laser that is applied to the side of the plate with the large plate thickness is reduced. It is characterized in that it is made larger than the plate material side.

As a result, when two plates with different plate thicknesses are butt-matched with their surfaces displaced from each other, and laser light is irradiated along this butt line for welding, the relative energy shortage due to the plate-thickness difference Is eliminated, and both plate materials are sufficiently melted to enable welding without sharply angled steps.

Example of Invention

FIG. 1 shows a partially cutaway perspective view of an apparatus for carrying out the welding method of the present invention. A condenser lens 7 is held by a lens holder 8 in the laser irradiation part of the laser irradiation device.
The condenser lens 7 is held by a rotation shaft 9 so as to be inclined with respect to the optical axis of the laser light 4. This rotating shaft 9
Is aligned with the center of the lens so that the height at which the light is focused does not change even if the condenser lens 7 is tilted. Incidentally, when the condenser lens 7 is tilted, the focal position actually moves in a plane due to the aberration of the lens, but since the amount of movement is a minute amount, the deviation from the butt line can be ignored, and there is almost no problem. A plate thickness difference detecting means 10 is provided outside the lens holder 8. The plate thickness difference detecting means 10 detects the plate thickness difference by irradiating the abutting portions of the plate materials 1 and 2. The detection signal of the plate thickness difference is sent to the driving means 11. The drive means 11 is composed of a control unit 12 which directly receives the detection signal and a lens rotation motor 13 which receives the control signal from the control unit 12 and drives the lens rotation motor 13. Upon receiving the plate thickness difference detection signal, the control unit 12 rotates the lens rotation motor 13 by an amount stored in advance according to the detection signal. The rotation of the lens rotation motor 13 causes the gears 14 and 15 to rotate the condenser lens 7 so that the condenser lens 7 has a predetermined inclination with respect to the optical axis. This inclination is set so that the energy of the laser beam 4 with which the plate material 1 having a large plate thickness is irradiated is made larger than the energy of the plate material 2 having a small plate thickness so that both plate materials 1 and 2 can be melted equally. . That is, depending on the difference in plate thickness, the condenser lens 7
The inclination angle of is also large and small, and as shown in FIG. 2, the energy density distribution is set so as to match the plate thickness difference between the plate materials 1 and 2. The inclination direction of the condenser lens 7 and the energy density distribution naturally correlate with each other, and the condenser lens is tilted by rotating it counterclockwise with the rotation axis 9 as the origin and by rotating it clockwise. In some cases, the energy density distribution has a left-right inverse relationship. Similarly, when the condenser lens is tilted in either direction, the energy density distributions in the front and rear sides of the focus position are in a left-right inverted relationship. When the condenser lens 7 is tilted counterclockwise and the plate material is irradiated behind the focus position, the left side has high energy, so the left side may be a thick plate and the right side may be a thin plate.

Next, a case of actually welding by the method of the present invention will be described. The plate thickness difference detection means emits light to the abutting portion of the plate materials 1 and 2 to detect the plate thickness difference between the plate materials 1 and 2, and the detection signal is sent to the control unit 12, and the calculated control signal is sent to the lens rotation motor. Sent to 13. The rotation of the motor 13 tilts the focusing lens 7 by a set angle corresponding to the plate thickness difference. Due to the inclination of the condenser lens 7, the energy of the laser beam 4 applied to the plate material 1 having a large plate thickness becomes larger than the energy of the plate material 2 having a small plate thickness, and the abutting portions of both plate materials 1 and 2 are equal and sufficient. Melted and welded. FIG. 3 shows a weld 6 welded by the method of the present invention. There is no sharp step 5 (Fig. 6) as in the prior art.

〔The invention's effect〕

According to the present invention, the energy of the laser beam irradiated to the plate material having a large plate thickness is larger than the energy of the plate material having a small plate thickness, and in particular, the laser beam irradiated to the plate material side having the large plate thickness by tilting the condenser lens. Since the energy is made larger than that on the plate material side having a small plate thickness, the relative energy shortage due to the plate thickness difference is eliminated, and both plate materials are equally melted and sufficiently welded. Therefore, since there is no sharp step difference as in the prior art, the problem of mold galling does not occur at the time of press forming in the post processing. Further, since both plate materials are equally melted and welded, stress concentration does not occur and strength does not decrease. Furthermore, effective use of laser light energy can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway perspective view of an apparatus for carrying out the welding method of the present invention, FIG. 2 is an energy density distribution map corresponding to the difference in plate thickness, and FIG. FIG. 4 is a side view showing a welded portion welded by the method of the invention, FIG. 4 is an energy density distribution diagram in which the condenser lens is not tilted, FIG. 5 is a perspective view showing a conventional welding method, and FIG. It is a side view which shows the welding part welded by the method. 1, 2 ... Plate material, 3 ... Butt line, 4 ... Laser light, 7 ... Condensing lens, 10 ... Plate thickness difference detecting means, 11 ... Driving means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Higashi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd. (56) Reference JP-A-56-114592 (JP, A)

Claims (2)

[Claims] 1. Welding is performed by butting two plate members having different plate thicknesses with their surfaces displaced from each other and irradiating a laser beam from the surface side of the one side along the butt line while welding them. In the laser welding method to
The energy of the laser beam applied to the thick plate material is made larger than the energy of the small plate material so that the corners formed at the abutting portions of the large plate material and the small plate material A laser welding method characterized by welding the two plate materials while melting. 2. Welding is performed by butting two plate members having different plate thicknesses with their surfaces displaced from each other and irradiating with laser light from the surface side of the one side along the butt line. In the laser welding method to
A laser welding method characterized by tilting a condenser lens which receives a laser beam and concentrates and irradiates it on a welding portion so that the energy of a laser radiated to a plate material side having a large plate thickness is made larger than that of a plate material side having a small plate thickness.