JP6525127B2 - Laser welding apparatus and laser welding method - Google Patents

Description

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

  In the above-described laser welding using a laser beam, the laser beam is blocked by a high concentration of fume (metal vapor) or spatter (metal droplet) generated at the laser beam irradiated portion of the workpiece to reach the workpiece. The amount of energy may fluctuate. As a result, when the amount of energy to reach the object to be welded is small, the keyhole generated in the laser light irradiated portion of the object to be welded is blocked while leaving fumes inside and remains as porosity (air bubbles) Resulting in.

Heretofore, as a means for preventing the occurrence of porosity, a laser welding apparatus for performing laser welding under reduced pressure has been devised (see, for example, Patent Document 1).
The laser welding apparatus includes a chamber which is a pressure reducing container, and the chamber is configured by combining a shield gas cylinder to which a shield gas is supplied and an optical system with a long focus.

Patent No. 5234471 gazette

  In the above-described laser welding apparatus, although the generation of porosity can be suppressed to a certain extent by welding in the chamber which is a pressure reducing container, the apparatus configuration is necessary because it is necessary to combine the shield gas cylinder and the long focus optical system with the chamber. Is complicated, and solving the problem is a conventional problem.

  The present invention has been made to solve the conventional problems as described above, and a laser welding apparatus and a laser welding method capable of preventing the occurrence of porosity after realizing simplification of the apparatus configuration. It is intended to be provided.

Here, the size of the keyhole in laser welding is usually 3 mm or less. The present inventors have found that a simple apparatus configuration for forming a negative pressure environment locally, focusing on the fact that the occurrence of porosity can be suppressed to a low level by decompressing even a portion having a diameter of about 3 mm at most. It came to
That is, a first aspect of the present invention is a laser welding apparatus including a laser head for irradiating a laser beam, wherein the fixed cylinder through which the laser beam attached to the laser head passes, and the laser beam A moving cylindrical body surrounding a portion irradiated with the laser beam of the object to be welded and avoiding the movement of the movable cylindrical body fitted in the hollow portion of the fixed cylindrical body along the laser light, and the direction of the object to be welded to the moving cylindrical body A negative pressure environment generating mechanism for generating a negative pressure environment in the laser beam irradiated portion of the object to be welded is disposed in the movable cylinder, and the negative pressure environment generating mechanism A nozzle (preferably a Laval nozzle) for injecting an inert gas such as nitrogen gas or argon gas in a direction crossing the laser beam emitted from the laser head, and the nozzle and the nozzle with the laser beam facing each other Are al injected comprises a diffuser for diffusing by introducing an inert gas across the laser beam, the nozzle and the diffuser of the negative pressure environment generating mechanism, located in the welded object side of the moving cylinder It is set as the structure fixed to the edge part .

The first reference embodiment of the present invention, the laser beam irradiated portion of the nozzle and the object to be welded together and the nozzle and the diffuser connecting the diffuser of the avoiding the laser beam vacuum environment generating mechanism It is set as the structure provided with the surrounding shielding body.

In addition, the second reference embodiment of the present invention, comprises a container for accommodating the object to be welded to cover the laser beam emitted from the laser head, the nozzle and the said the vessel a negative pressure environment generating mechanism The diffuser is fixed.

On the other hand, in the laser welding method according to the present invention, the fixed cylinder through which the laser beam attached to the laser head passes, and the fixed cylinder that surrounds the portion of the object to be welded that is irradiated with the laser beam while avoiding the laser beam. A laser welding apparatus comprising: a movable cylindrical body movably fitted along the laser beam in the hollow portion of the lower surface; and an elastic body which constantly applies a force in the direction of the object to be welded to the movable cylindrical body , when performing welding by irradiating the laser light to the welding subject from said laser head, across the laser beam emitted from the laser head at the end located at the welded object side of the moving cylinder in the nozzle and the diffuser is facing, with the force toward the welded object direction by the elastic body is brought into contact with the moving cylindrical body that is constantly applied to the welded object, before being emitted from the laser head By the inert gas across the laser beam is diffused and introduced into the diffuser while injecting the inert gas from the nozzle in a direction transverse to the laser beam, a negative pressure in the laser beam irradiated portion of said object to be welded The welding is performed by irradiating the workpiece with the laser beam while generating an environment.

In the laser welding apparatus and the 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 velocity 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 be made to the atmosphere.
Then, as the laser used in the laser welding apparatus and laser welding method according to the present invention, there may be mentioned a YAG laser or CO ₂ laser or a fiber laser or disk laser, not limited to these.

  In the laser welding apparatus according to the present invention, for example, when welding objects to be welded together, the nozzle of the negative pressure environment generating mechanism and the diffuser of the negative pressure environment generating mechanism opposed to each other with the laser beam irradiated from the laser head The inert gas is ejected at a high speed in the direction crossing the laser light, and the inert gas crossing the laser light is introduced into the diffuser and diffused.

  Next, welding is started in this state, and the negative pressure environment generating mechanism is moved along the butt portion together with the laser head while irradiating the butt portion between the workpieces with laser light.

  During this time, a keyhole is formed in the object to be welded due to melting and evaporation of the object to be welded due to the laser beam irradiation from the laser head, and fumes are ejected from the inside, but high speed is generated between the nozzle and diffuser of the negative pressure environment generation mechanism Since the laser beam irradiated part between the objects to be welded has a negative pressure by flowing the inert gas, the fumes ejected from the keyhole are attracted to the diffuser, and at this time, spatters are ejected together with the fumes. Although there is, it is also sucked into the diffuser.

  As described above, in the laser welding apparatus according to the present invention, the fumes and the spatters that cause the fluctuation of the energy amount of the laser light are attracted and removed by the diffuser of the negative pressure environment generation mechanism without blocking the laser light. Since the generation of the porosity can be suppressed to a low level while simplifying the structure of the apparatus, and spatter that bounces irregularly from the key hole can be removed, the concern that the laser head is damaged can be wiped out.

  Under the present circumstances, if a nozzle and a diffuser are connected with a shield and it is made to surround the laser beam irradiation part of a to-be-welded object, negative pressure environment can be efficiently formed in a laser beam irradiation part.

  Further, the end portion of the cylindrical body which surrounds the laser beam irradiated portion of the object to be welded avoiding the laser beam and is movable along the laser beam is subjected to the object to be welded by the force in the direction of the object from the elastic body. When the light-emitting portion of the object to be welded is in a state of being substantially isolated from the surroundings, the negative pressure environment can be more efficiently formed by the portion irradiated with the laser beam.

  Furthermore, after the object to be welded is accommodated in a container covering the laser beam emitted from the laser head and laser welding is performed, a negative pressure environment is formed in the portion irradiated with the laser beam of the object to be welded. The negative pressure environment is well and reliably maintained.

  The laser welding apparatus according to the present invention has a very excellent effect of being able to prevent the occurrence of porosity while realizing simplification of the apparatus configuration.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which illustrates roughly the laser welding apparatus which concerns on one reference form of this invention. It is a section explanatory view (a) showing a negative pressure environment generating mechanism in the laser welding apparatus of FIG. 1 and a section explanatory view (b) based on the A-A line position of FIG. 2 (a). It is an expanded section explanatory view showing the negative pressure environment generating mechanism of the laser welding device concerning one embodiment of the present invention. It is an expanded section explanatory view showing the negative pressure environment generating mechanism of the laser welding device concerning other reference forms of the present invention.

Hereinafter, embodiments of the present invention will be described based on the drawings.
Figures 1 and 2 show a laser welding device according to one reference embodiment of the present invention, this reference embodiment, the case of using the laser welding apparatus according to the present invention steel sheet (object to be welded) to the butt joint between the Is shown.

As schematically shown in FIG. 1, this laser welding apparatus 1 is focused by a laser oscillator 2 and an optical system 3 having a built-in laser light L supplied from the laser oscillator 2 so that the steel plates W and W are butted. The laser head 4 for irradiating the portion Wa, the optical fiber 5 for guiding the laser light L from the laser oscillator 2 to the laser head 4, and the laser head 4 are moved along the butt portion Wa of the steel plates W, W to a drive unit 6 for vehicle distance, welding speed, laser power and comprises a control unit 7 for controlling the spot diameter, in this reference embodiment, the focal LA steel plate W of the laser beam L, the surface of the butt portion Wa of W It is set to be located at the top.

  The laser welding apparatus 1 further includes a negative pressure environment generating mechanism 10 that generates a negative pressure environment in the vicinity of the laser light irradiated portions of the steel plates W, W, that is, the focal point LA of the laser light L.

  As shown in FIG. 2A, the negative pressure environment generation mechanism 10 ejects an inert gas G such as nitrogen gas or argon gas at high speed in a direction crossing the laser light L emitted from the laser head 4. There is a nozzle (preferably a Laval nozzle) 11 and a diffuser 12 for opposingly introducing the nozzle 11 with the laser beam L and injecting it from the nozzle 11 to introduce and diffuse the inert gas G across the laser beam L. The nozzle 11 and the diffuser 12 are both attached to the laser head 4 by a support 13.

  In this case, as shown in FIG. 2B, the negative pressure environment generating mechanism 10 is provided with shields 14 and 14 for connecting the nozzle 11 and the diffuser 12 while avoiding the laser beam L. This shield 14 , 14 together with the nozzle 11 and the diffuser 12 surround the focal point LA of the laser light L.

  When the steel plates W, W are butt-joined by the laser welding apparatus 1, the nozzle 11 of the negative pressure environment generating mechanism 10 and the nozzle 11 of the diffuser 12 are opposed to each other with the laser beam L emitted from the laser head 4 interposed therebetween. Then, the inert gas G is ejected at high speed in the direction crossing the laser light L, and the inert gas G which has crossed the laser light L is introduced into the diffuser 12 and diffused.

  Next, welding is started in this state, and while the laser light L is irradiated to the butt portion Wa of the steel plates W, W, the negative pressure environment generating mechanism 10 is joined with the steel plates W by the drive portion 6 together with the laser head 4 Move along Wa.

  During this time, the keyhole K is formed in the steel plate W by melting and evaporation of the steel plate W by the irradiation of the laser light L from the laser head 4 and fume (a bundle of arrows in FIG. 2A) is ejected from the inside. By flowing the inert gas G at high speed between the nozzle 11 and the diffuser 12 of the negative pressure environment generation mechanism 10, the laser light irradiated portion between the steel plates W and W, that is, the vicinity of the focal point LA of the laser light L becomes negative pressure. Therefore, the fumes ejected from the keyhole K are drawn into the diffuser 12, and at this time, spatter may be ejected together with the fumes, but this is also drawn into the diffuser 12.

As described above, in the laser welding device 1, fumes and spatters generated in the keyhole K are attracted and removed by the diffuser 12 of the negative pressure environment generation mechanism 10 without blocking the laser light L, that is, the laser light L Since the fumes and spatters, which are the causes of fluctuations in the amount of energy, are removed, the occurrence of porosity can be suppressed to a low level by simplifying the apparatus configuration.
In addition, since spatters that bounce irregularly from the keyhole K can be removed as described above, the concern of damaging the laser head 4 can also be wiped out.

  Furthermore, in the laser welding apparatus 1, the nozzle 11 and the diffuser 12 are connected by the shields 14 and 14 so as to surround the vicinity of the focal point LA of the laser light L. It will be possible to form an environment.

Figure 3 shows the laser welding apparatus according to an embodiment of the present invention, this embodiment shows a case of using a laser welding device according to the present invention steel sheet (object to be welded) to the butt joint between the ing.

  As partially shown in FIG. 3, the laser welding apparatus 1A avoids the laser light L in the fixed cylindrical body 23 attached to the laser head 4 and the hollow portion 23a of the fixed cylindrical body 23 through which the laser light L passes. The movable cylinder (cylinder) 24 fitted and movable along the laser beam L, and the compression coil spring (elastic body) 25 fitted in the small diameter end 24 a of the movable cylinder 24 The compression coil spring 25 always applies a force in the direction of the steel plate W to the movable cylindrical body 24.

  In this case, the nozzle 11 and the diffuser 12 of the negative pressure environment generating mechanism 10 are disposed at the end of the laser light irradiation portion, that is, the end portion surrounding the focus LA of the laser light L on the steel plate W, W side of the movable cylinder 24. It is fixed.

  The reference numeral 26 in FIG. 3 is a stopper pin, and by hooking the end portion of the stopper pin 26 penetrating the peripheral wall of the fixed cylindrical body 23 into the recess 24 b formed in the peripheral wall of the movable cylindrical body 24, the movable cylindrical body 24 Of the fixed cylindrical body 23 is restricted.

  Further, in the laser welding apparatus 1A, a pipe for supplying the inert gas G to the hollow portion of the movable cylindrical body 24 or a pipe for evacuating the hollow portion may be connected to the movable cylindrical body 24.

  When the steel plates W, W are butt-joined by the laser welding apparatus 1A, first, the laser head 4 is made to approach the steel plates W, W by the drive unit 6, and the force directed toward the steel plate W is always applied by the compression coil spring 25. The end on the steel plate W side of the moving cylinder 24 is brought into light contact with the steel plate W.

  Then, from the nozzle 11 of the negative pressure environment generation mechanism 10 disposed at the end of the movable cylindrical body 24 on the steel plate W side and the nozzle 11 of the diffuser 12, the inert gas G is traversed at high speed in the direction crossing the laser light L. At the same time as the previous embodiment, welding is started while introducing the inert gas G which has crossed the laser light L into the diffuser 12 while injecting the laser light L, and the laser light L is brought into contact with the steel sheet W The negative pressure environment generating mechanism 10 is moved along with the butted part Wa of the steel plates W, W together with the laser head 4.

  During this time, the keyhole K is formed in the steel plate W by melting and evaporation of the steel plate W by the irradiation of the laser light L from the laser head 4, and fumes (a bundle of arrows in FIG. 3) are ejected from the inside. By flowing the inert gas G at high speed between the nozzle 11 and the diffuser 12 of the generation mechanism 10, the laser light irradiated portion between the steel plates W and W, that is, the vicinity of the focal point LA of the laser light L has a negative pressure. The fumes ejected from the keyhole K are sucked into the diffuser 12, and at this time, spatter may be ejected together with the fumes, which is also sucked into the diffuser 12.

As described above, also in the laser welding apparatus 1A, fumes and spatters generated in the keyhole K are attracted and removed by the diffuser 12 of the negative pressure environment generating mechanism 10 without blocking the laser light L, that is, laser light Since fumes and spatters which cause the fluctuation of the amount of energy of L are removed, the occurrence of porosity can be suppressed to a low level by simplifying the device configuration.
In addition, since spatters that bounce irregularly from the keyhole K can be removed as described above, the concern of damaging the laser head 4 can also be wiped out.

  Furthermore, in this laser welding apparatus 1A, the end portion on the steel plate W side of the movable cylindrical body 24 is lightly brought into contact with the steel plate W by the force in the steel plate W direction from the compression coil spring 25 during welding. The vicinity of the focal point LA of the light L is substantially isolated from the surroundings, and hence the vicinity of the focal point LA of the laser light L can form a negative pressure environment more efficiently.

Figure 4 shows the laser welding apparatus according to another reference embodiment of the present invention, the in the reference embodiment, if the laser welding apparatus according to the present invention is used for butt joint between the steel shaft (welded object) It shows.

  As partially shown in FIG. 4, the laser welding apparatus 1B rotates the steel shaft Ws in the container 33, which covers the laser beam L emitted from the laser head 4 and accommodates the steel shaft Ws. In this embodiment, the focal point LA of the laser beam L is set to be located on the surface of the butted part of the steel axis Ws, and the nozzle 11 of the negative pressure environment generating mechanism 10 and the The diffuser 12 is fixed to the container 33 via the pipes 15 and 16 respectively.

Reference numeral 34 in FIG. 4 denotes an exhaust pipe.
In the laser welding apparatus 1B, the negative pressure environment in the vicinity of the focal point LA of the laser light L may be maintained by evacuating through the diffuser 12 of the negative pressure environment generating mechanism 10.

  When the steel shaft Ws is butt-joined by the laser welding apparatus 1B, the nozzle 11 of the negative pressure environment generating mechanism 10 and the nozzle 11 of the diffuser 12 face each other with the laser beam L emitted from the laser head 4 interposed therebetween. An inert gas indicated by an arrow is supplied to inject the inert gas at high speed in the direction crossing the laser light L, and the inert gas which has crossed the laser light L is introduced into the diffuser 12 and diffused.

  Next, welding is started in this state, and the steel shaft Ws is rotated by the drive unit 36 while irradiating the butt portion of the steel shaft Ws with the laser beam L.

  During this time, a keyhole (not shown in FIG. 4) is formed on the steel shaft Ws by melting and evaporation of the steel shaft Ws due to the irradiation of the laser light L from the laser head 4 and fumes are ejected from the inside. By flowing the inert gas at high speed between the nozzle 11 and the diffuser 12 of the environment generation mechanism 10, the laser light irradiated portion of the steel axis Ws, that is, the vicinity of the focal point LA of the laser light L has a negative pressure. The fumes ejected from the holes are drawn into the diffuser 12, and spatter may be ejected together with the fumes, which is also drawn into the diffuser 12.

As described above, also in the laser welding apparatus 1B, fumes and spatters generated in the keyhole are sucked and removed by the diffuser 12 of the negative pressure environment generating mechanism 10 without blocking the laser light L, that is, the laser light L Since the fumes and spatters, which are the causes of fluctuations in the amount of energy, are removed, the occurrence of porosity can be suppressed to a low level by simplifying the apparatus configuration.
In addition, since spatters that bounce irregularly from the keyhole K can be removed as described above, the concern of damaging the laser head 4 can also be wiped out.

  Furthermore, in the laser welding apparatus 1B, the steel shaft Ws is accommodated in the container 33 and laser welding is performed, and a negative pressure environment is formed in the vicinity of the focal point LA of the laser light L. A negative pressure environment will be maintained well and reliably.

  The configurations of the laser welding apparatus and the laser welding method according to the present invention are not limited to the embodiments described above, and various modifications can be made without departing from the scope of the invention.

1A les over laser welding apparatus 4 laser head 10 a negative pressure environment generating mechanism 11 nozzle 12 diffuser
23 fixed cylindrical member 24 moving cylinder
25 compression coil spring (elastic body )
G inert gas L laser beam W steel material (welding object)

Claims (2)

A laser welding apparatus comprising a laser head for irradiating a laser beam, comprising:
A fixed cylinder through which the laser beam attached to the laser head passes, a laser beam is avoided to surround the laser beam irradiated portion of the object to be welded, and the hollow portion of the fixed cylinder is along the laser beam A movable cylindrical body movably fitted, and an elastic body which constantly applies a force in the direction of the object to be welded to the movable cylindrical body,
A negative pressure environment generating mechanism that causes a negative pressure environment to be generated in the laser light irradiated portion of the object to be welded is disposed in the moving cylinder .
The negative pressure environment generating mechanism includes a nozzle for injecting an inert gas in a direction crossing the laser beam emitted from the laser head, and the nozzle with the laser beam sandwiched between the nozzle and sprayed from the nozzle to be opposed to the laser beam by introducing an inert gas across a comprises a diffuser for diffusing,
The said nozzle of the said negative pressure environment generation | occurrence | production mechanism and the said diffuser are the laser welding apparatuses currently fixed to the edge part located in the said to-be-welded object side of the said movable cylinder . A fixed cylinder through which a laser beam attached to a laser head passes, and the laser beam is avoided to surround the portion irradiated with the laser beam of the object to be welded and moved along the laser beam to the hollow portion of the fixed cylinder and capable mated moving cylinder body, using said laser welding apparatus having a resilient member for constantly applying a force toward the welded object direction to the moving cylinder, the said object to be welded from said laser head When welding by irradiating a laser beam,
It is facing the nozzle and the diffuser across the laser beam emitted from the laser head at the end located at the welded object side of the moving cylinder,
In a state where a force toward the welded object direction by the elastic body is brought into contact with the moving cylindrical body that is constantly applied to the welding subject, from the nozzle in a direction transverse to the laser beam emitted from the laser head the inert gas across the laser beam while injecting an inert gas that is diffused and introduced into the diffuser, the laser beam the while causing a negative pressure environment in the laser beam irradiated portion of the object to be welded The laser welding method which irradiates to the said to-be-welded object and welds.

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