JP6805710B2 - Laser welding equipment and laser welding method - Google Patents

Description

The present invention relates to a laser welding apparatus and a laser welding method using a laser beam.

In laser welding using the above-mentioned laser beam, for example, when flat plates are butt welded to each other, metal vapor such as metal fume or laser plume or spatter (metal droplets) is applied to the laser beam irradiated portion of the flat plate to be welded. ) Occurs. When the metal vapor or spatter adheres to the optical system of the laser head that irradiates the laser beam, the laser beam is blocked and the laser irradiation to the workpiece becomes unstable.

Conventionally, a laser welding device that performs laser welding in a negative pressure environment has been proposed as a laser welding device that takes measures to prevent metal vapor and spatter generated in the laser beam irradiated portion from adhering to the optical system of the laser head. (See, for example, Patent Document 1).

This laser welding apparatus has a configuration in which a negative pressure generator that creates a negative pressure environment in the laser beam irradiation portion of the workpiece is arranged below the laser head. This negative pressure generator includes a nozzle arranged along a direction crossing the laser beam emitted from the laser head, and a diffuser arranged so as to face the nozzle with the laser beam interposed therebetween.

The negative pressure generator of this laser welding device introduces an inert gas such as nitrogen gas or argon gas injected from the nozzle into the diffuser and diffuses it (inert gas is accelerated and flowed between the nozzle and the diffuser). This creates a negative pressure environment in the laser beam irradiated portion of the work piece. As a result, metal vapor and spatter generated in the laser beam irradiated portion of the work piece can be sucked into the diffuser.

Therefore, in this laser welding apparatus, it is possible to suppress metal vapor and spatter generated in the laser beam irradiation portion from adhering to the optical system of the laser head.

Japanese Unexamined Patent Publication No. 2015-231629

In the above-mentioned laser welding apparatus, in the case of laser welding using a large output laser beam of about 20 kW, the nozzle and diffuser of the negative pressure generator are arranged according to the optical path width of the laser beam that increases as the laser output increases. It is necessary to increase the interval.

At this time, in order to create a negative pressure environment for sucking metal vapor and spatter in the laser beam irradiated portion of the work piece, it is necessary to increase the gas flow rate between the nozzle and the diffuser.

However, even if the gas flow rate between the nozzle and the diffuser is increased in this way, as long as the distance between the nozzle and the diffuser is wide, metal vapor and spatter generated in the laser beam irradiated portion of the work piece are not a little, and the optical system of the laser head There is a problem that it reaches the laser, and solving this problem has become a conventional issue.

The present invention has been made to solve the above-mentioned conventional problems, and regardless of the magnitude of the laser output, metal vapor or spatter generated in the laser beam irradiated portion of the welded object is applied to the optical system of the laser head. It is an object of the present invention to provide a laser welding apparatus and a laser welding method capable of suppressing arrival and adhesion to a small extent.

The first aspect of the present invention is a laser head that irradiates a laser beam toward an object to be welded, a nozzle that is arranged along a direction that crosses the laser optical path of the laser beam that is emitted from the laser head, and the like. In a laser welding apparatus including a negative pressure generator including a diffuser into which gas injected from the nozzle is introduced, which is arranged so as to face each other across the laser optical path and across the laser optical path, the negative pressure generator. Are arranged side by side at least two, and the laser is arranged in a field where gas flow paths located between the nozzle and the diffuser of the negative pressure generator arranged side by side face the object to be welded from the laser head. It is configured to be in contact with or overlap on the optical path and to cover the entire cross section of the laser optical path with the gas flow path .

Further , the second aspect of the present invention is configured to include a control unit for individually adjusting the gas injection amount of the nozzle in the negative pressure generator.

Furthermore, a third aspect of the present invention has a structure which includes a cover disposed to surround the laser beam irradiated portion of said object to be welded.

Furthermore, the fourth aspect of the present invention is such that the cover is filled with an inert gas.

On the other hand, in the fifth aspect of the present invention, when the laser head irradiates the object to be welded with the laser beam to perform welding, the nozzle and the diffuser facing each other across the laser optical path of the laser beam emitted from the laser head are provided. At least two negative pressure generators are arranged side by side, and the gas flow paths located between the nozzle and the diffuser of the two side-by-side negative pressure generators are arranged from the laser head to the object to be welded. superimposed contact to by the laser beam path in the field Rutotomoni covers the entire cross section of the laser beam path by the gas flow and through the gas flow channel is ejected from each nozzle of the vacuum generator gas face Is introduced into each diffuser of the negative pressure generator, and welding is performed while creating a negative pressure environment in the laser beam irradiation portion of the object to be welded.

In the laser welding apparatus according to the present invention, regardless of the magnitude of the laser output, it is possible to suppress metal vapor and spatter generated in the laser beam irradiated portion of the workpiece from reaching the optical system of the laser head and adhering to the optical system. It has a very good effect.

It is sectional drawing which shows typically the laser welding apparatus which concerns on one Embodiment of this invention. It is a partially enlarged cross-sectional explanatory view based on the position of AA line of FIG. It is a partially enlarged plane explanatory view which shows the overlapping state of the gas flow path of the negative pressure generator in the laser welding apparatus of FIG. It is a partially enlarged plane explanatory view (a), (b) which shows the other overlapping state of the gas flow path of the negative pressure generator in the laser welding apparatus of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 show a laser welding apparatus according to an embodiment of the present invention, and in this embodiment, a case where the laser welding apparatus according to the present invention is used for butt welding between a pair of flat plates is shown. There is.

As shown in FIG. 1, the laser welding apparatus 1 includes a laser oscillator 2, a laser head 4 connected to the laser oscillator 2 via an optical fiber 3, a drive mechanism 5 for moving the laser head 4, and a welding speed. It is provided with a control unit 6 that controls the laser output, the spot diameter of the laser beam, and the like.

The laser head 4 includes a lens 4a which is an optical system, and the laser light supplied from the laser oscillator 2 is focused on a conical laser optical path L and is between a pair of flat plates (welded objects) W and W. Irradiate the groove Wa. Further, the drive mechanism 5 includes a rail 5a arranged along the groove Wa and a slider 5b, and the slider 5b is mounted on the laser head 4 and moves on the rail 5a by the output of a motor (not shown). Move in the direction of the thick black arrow.

Further, the laser welding apparatus 1 is a negative pressure environment generating unit 10 that creates a negative pressure environment near the groove Wa, which is a laser beam irradiation portion of the pair of flat plates W, W, that is, near the focal point LA of the laser optical path L. Is equipped with.

The negative pressure environment generating unit 10 contains a covering cylinder 11 mounted on the lower part of the laser head 4, a negative pressure generator 20 arranged below the covering cylinder 11, and an inert gas such as nitrogen gas or argon gas. It includes a filled gas cylinder 12 for generating negative pressure.

The covering cylinder 11 covers the laser optical path L leading to the negative pressure generator 20, and a protective glass 11a constituting an optical system is built in the upper end portion of the covering cylinder 11 together with the lens 4a of the laser head 4. There is.

The negative pressure generator 20 includes a nozzle 21 arranged along a direction crossing the laser optical path L of the laser light emitted from the laser head 4, and a diffuser arranged so as to face the nozzle 21 and the laser optical path L. 22 is provided.

The negative pressure generator 20 injects an inert gas supplied from the negative pressure generating gas cylinder 12 as shown by a white arrow from the nozzle 21, and is injected from the nozzle 21 to be inactive across the laser light path L. By introducing the gas into the diffuser 22 and diffusing it as shown by the white arrow, and allowing the inert gas to flow between the nozzle 21 and the diffuser 22 at an accelerated speed, a negative pressure environment is provided near the focal point LA of the laser light path L. Causes.

Here, if the distance between the nozzle 21 and the diffuser 22 in the negative pressure generator 20 is set to be narrow, a good negative pressure environment is formed near the focal point LA of the laser optical path L. However, for example, in the case of laser welding using a large output laser beam of about 20 kW, if the distance between the nozzle 21 and the diffuser 22 is set wide according to the path width of the laser optical path L that increases as the laser output increases, Although it becomes easier to observe the welding condition, the decompression effect in the vicinity of the focal point LA of the laser optical path L is reduced, and it cannot be said that the environment is a good negative pressure environment.

Therefore, in this embodiment, as shown in FIG. 2, negative pressure is suppressed in order to suppress a decrease in the decompression effect when welding is performed by a high-power laser beam (when the distance between the nozzle 21 and the diffuser 22 is set wide). Four generators 20 are arranged along the laser optical path L. Each nozzle 21 and each diffuser 22 in these four negative pressure generators 20 are fixed to blocks 23 and 24, respectively. Then, as shown in FIG. 3, the four gas flow paths F1 to F4 located between each nozzle 21 and each diffuser 22 in these four negative pressure generators 20 are between the laser head 4 and the flat plates W and W. It covers the entire cross section of the laser optical path L in the field of view facing the groove Wa (planar field of view in this embodiment). In FIG. 1, all four gas flow paths F1 to F4 are indicated by thin arrows.

More specifically, the gas flow path F1 of the negative pressure generator 20 located closest to the laser head 4 and the negative pressure generators located on the flat plates W and W side of the gas flow path F1 of the negative pressure generator 20. The gas flow paths F3 and F4 of 20 overlap each other on the laser optical path L in the field of view facing the groove Wa between the flat plates W and W from the laser head 4.

Further, the gas flow path F2 of the negative pressure generator 20 located closer to the laser head 4 and the gas flow of the negative pressure generator 20 located closer to the flat plates W and W than the gas flow path F2 of the negative pressure generator 20. The paths F4 overlap each other on the laser optical path L in a field of view facing the groove Wa between the laser head 4 and the flat plates W and W.

That is, the gas flow paths F1 to F4 of the negative pressure generators 20 arranged side by side along the laser optical path L of the laser light are mutually arranged in a field of view facing the groove Wa between the laser head 4 and the flat plates W and W. It overlaps and covers the entire cross section of the laser optical path L so as to generate a negative pressure environment over a wide range in the vicinity of the focal length LA of the laser optical path L.

In addition, in this embodiment, a valve module 25 is installed between the negative pressure generating gas cylinder 12 and the four negative pressure generators 20. The valve module 25 changes the amount of gas supplied from the negative pressure generating gas cylinders 12 to the four negative pressure generators 20 according to a command from the control unit 6, and causes each nozzle 21 in the four negative pressure generators 20. The gas injection amount is adjusted individually.

Further, the negative pressure environment generating unit 10 includes a cover 13 arranged below the negative pressure generator 20. The cover 13 covers the focal point LA, which is a laser beam irradiation portion of the pair of flat plates W and W, and maintains the negative pressure environment generated by the four negative pressure generators 20. A tapered cylinder 13a covering the laser beam L passing through the negative pressure generator 20 is mounted on the inside of the cover 13 via the base block 13b.

In this embodiment, the negative pressure environment generating unit 10 includes a shield gas cylinder 14 filled with an inert gas such as nitrogen gas or argon gas, like the gas cylinder 12 for generating negative pressure. From the shield gas cylinder 14, as shown by the solid arrow in FIG. 1, the inert gas is supplied into the cover 13, whereby the inert atmosphere in the cover 13 in the negative pressure environment is created. It is designed to be kept.

It should be noted that the number of negative pressure generators 20 may be two or more, and the number is not limited to four in this embodiment.
Further, the nozzle 21 and the diffuser 22 of the negative pressure generator 20 in this embodiment are not limited to those having the shape shown in the drawing, and the gas injection hole of the nozzle 21 may have an elliptical shape or a plurality of negative pressures. The diameters of the nozzle and the diffuser may be different for each generator.

Further, in this embodiment, the gas flow paths F1 to F4 formed between the nozzle 21 and the diffuser 22 of the negative pressure generator 20 all have a substantially conical shape (truncated cone shape), but the present invention is limited to this. For example, the gas flow path may have a cylindrical shape.

In this way, when the gas flow path has a cylindrical shape, as shown in FIG. 4A, at least two lines are arranged before and after the laser light irradiation direction or at the same level in the laser light irradiation direction. It is desirable that the gas flow paths F5 and F6 overlap each other in the plane view, but these gas flow paths F5 and F6 do not necessarily have to overlap in the plane view, and as shown in FIG. 4 (b). , May just be in contact with each other.

In the laser welding apparatus and laser welding method according to the present invention, the "negative pressure environment" refers to an atmosphere with a pressure of 90 kPa or less, and the injection speed of the inert gas from the nozzle is a pressure of 90 kPa or less between the nozzle and the diffuser. It is the speed that can make the atmosphere.
Examples of the laser used in the laser welding apparatus and laser welding method according to the present invention include, but are not limited to, a YAG laser, a CO ₂ laser, a fiber laser, and a disk laser.
Further, laser welding by a laser welding device is not limited to butt welding.

Next, a procedure will be described in which the laser welding apparatus 1 is used to perform butt welding on the groove Wa between the pair of flat plates W and W to join the pair of flat plates W and W to each other.

First, from each nozzle 21 of the four negative pressure generators 20 of the negative pressure environment generating unit 10 facing each other across the laser optical path L of the laser light emitted from the laser head 4, the direction across the laser optical path L is not present. The active gas is injected at high speed, and the inert gas that has crossed the laser optical path L is introduced into each diffuser 22 of the four negative pressure generators 20.

Next, welding is started in this state, and while irradiating the groove Wa between the pair of flat plates W and W with laser light, the laser head 4 and the negative pressure environment generating portion 10 are driven along the groove Wa by the drive mechanism 5. Move together.

Due to the movement of the laser head 4 and the negative pressure environment generating unit 10, a weld bead B is formed in the groove Wa between the pair of flat plates W and W, and during this period, the laser with respect to the groove Wa between the pair of flat plates W and W is formed. By irradiating the laser beam from the head 4, metal steam P and spatter S are ejected from the pair of flat plates W and W.

At this time, the inert gas is accelerated and flows along the gas flow paths F1 to F4 between the nozzles 21 and the diffusers 22 of the four negative pressure generators 20 in the negative pressure environment generating unit 10. Therefore, the laser beam irradiation portion between the pair of flat plates W and W, that is, the vicinity of the focal point LA of the laser optical path L is a negative pressure environment.

In addition, the four gas flow paths F1 to F4 of the negative pressure generator 20 arranged side by side in the front and rear of the laser beam irradiation direction overlap each other in the field of view facing the groove Wa between the laser head 4 and the flat plates W and W. It covers the entire cross section of the laser optical path L without any gaps.

Therefore, most of the metal steam P and the spatter S generated by irradiating the groove Wa with the laser beam from the laser head 4 are inert gases flowing at high speed in the gas flow paths F1 to F4 of the four negative pressure generators 20. It will be sucked into one of the diffusers 22 on the.

As described above, in the laser welding apparatus 1 according to the above-described embodiment, the gas flow paths F1 to F4 of the negative pressure generators 20 arranged side by side in the front and rear of the laser beam irradiation direction are connected to the flat plate W from the laser head 4. , W overlap each other in the field of view facing the groove Wa.

As a result, for example, when using a large output laser beam of about 20 kW, even if the distance between each nozzle 21 and each diffuser 22 of the four negative pressure generators 20 is set wide (about 15 mm), the laser head Metal vapor P and spatter S generated in the groove Wa between the pair of flat plates W and W due to the irradiation of the laser beam from 4 reach the protective glass 11a, which is the optical system of the laser head 4, and are less likely to adhere. Will be done.

Therefore, it is possible to avoid that the laser beam is blocked and the laser irradiation to the groove Wa between the pair of flat plates W and W becomes unstable.
Since the distance between the nozzle 21 and the diffuser 22 of the negative pressure generator 20 can be set wide, it becomes easy to observe the welding state.

Further, in the laser welding apparatus 1 according to the above-described embodiment, the gas flow paths F1 to F4 of the negative pressure generators 20 arranged side by side in front of and behind the laser beam irradiation direction form a gap in the entire cross section of the laser optical path L. Since it is completely covered, a negative pressure environment is generated over a wide range in the vicinity of the focal point LA of the laser optical path L.

Therefore, the metal vapor P and the spatter S generated in the groove Wa due to the irradiation of the laser beam from the laser head 4 are further suppressed from adhering to the protective glass 11a which is the optical system of the laser head 4.

Further, in the laser welding apparatus 1 according to the above-described embodiment, a valve module 25 that operates according to a command from the control unit 6 is installed between the negative pressure generating gas cylinder 12 and the four negative pressure generators 20. There is.

That is, by individually adjusting the gas injection amount of each nozzle 21 in the four negative pressure generators 20 by the valve module 25, the gas flow paths F1 to F4 covering the entire cross section of the laser optical path L cannot be used. The flow rate of the active gas can be changed, and it is possible to quickly respond to the case where the generation distribution of the metal steam P or the spatter S is biased.

Further, in the laser welding apparatus 1 according to the above-described embodiment, the cover 13 arranged below the negative pressure generator 20 covers the focal point LA, which is the laser beam irradiation portion of the pair of flat plates W, W. The negative pressure environment generated in the vicinity of the focal point LA can be maintained by the four negative pressure generators 20.

Furthermore, in the laser welding apparatus 1 according to the above-described embodiment, since the inert gas is supplied from the shield gas cylinder 14 into the cover 13, the inside of the cover 13 in the negative pressure environment is maintained in the inert atmosphere. As a result, it is possible to improve the welding quality.

The configuration of the laser welding apparatus and the laser welding method according to the present invention is not limited to the above-described embodiment.

1 Laser welding device 4 Laser head 4a lens (optical system)
6 Control unit 10 Negative pressure environment generator 20 Negative pressure generator 21 Nozzle 22 Diffuser F1 to F6 Gas flow path L Laser optical path LA Laser optical path focus W Flat plate (welded object)

Claims (5)

A laser head that irradiates a laser beam toward the work piece,
It is ejected from a nozzle arranged along a direction crossing the laser optical path of the laser beam emitted from the laser head, and a nozzle arranged facing the nozzle and the laser optical path across the laser optical path. In a laser welding apparatus equipped with a negative pressure generator consisting of a diffuser into which the gas is introduced.
At least two of the negative pressure generators are arranged side by side.
At least two gas flow paths located between the nozzle and the diffuser of the negative pressure generator arranged side by side are in contact with or overlap each other on the laser optical path in the field of view from the laser head to the work to be welded. A laser welding apparatus that covers the entire cross section of the laser optical path with the gas flow path . The laser welding apparatus according to claim 1, further comprising a control unit for individually adjusting the gas injection amount of the nozzle in the negative pressure generator. The laser welding apparatus according to claim 1 or 2 , further comprising a cover arranged so as to surround the laser beam irradiation portion of the object to be welded. The laser welding apparatus according to claim 3 , wherein the cover is filled with an inert gas. When welding is performed by irradiating the object to be welded with laser light from the laser head.
At least two negative pressure generators having a nozzle and a diffuser facing each other across the laser optical path of the laser light emitted from the laser head are arranged side by side, and the nozzle and the nozzle of the negative pressure generator arranged side by side. cover the entire cross section of the laser beam path of the gas flow path between respectively located between the diffuser said from the laser head in contact with or superimposed with the laser beam path in the field of view facing the weld object Rutotomoni, in the gas flow ,
The gas ejected from each nozzle of the negative pressure generator through the gas flow path is introduced into each diffuser of the negative pressure generator to create a negative pressure environment in the laser beam irradiated portion of the welded object. Laser welding method that performs welding while letting.

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