JPH0451271B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a welding method that uses a high-energy beam and an arc in combination.

(Prior art) As a conventional technology of the combined welding method of TIG (Tungsten Inert Gas ARC) and laser, for example,
The method described in No. 49195 is mentioned. In this case, the part to be irradiated with the laser beam must be TIGed in advance.
The main idea is to increase the absorption rate and deepen penetration by melting the material, but this does not necessarily mean that various conditions such as the positional relationship between the laser and the TIG nozzle are properly determined. For example, if the distance between the laser nozzle and the TIG electrode is too large during composite welding, the composite results will deteriorate. Furthermore, if the flow rate of the gas blown from the side is too large, the composite effect similarly decreases, causing problems in the stability and reproducibility of deep penetration welding due to the composite effect.

(Problems to be Solved by the Invention) Such problems are attributable to the fact that the position and size of plasma generated during composite welding are not stable.
Therefore, the present invention provides a combined laser and TIG welding method that can stably achieve optimal plasma conditions and plasma by setting specific conditions such as the positional relationship between the laser nozzle and the TIG electrode and the flow rate of gas. The purpose is to

(Means for Solving the Problems) In view of the above problems, the present invention
When welding steel materials using TIG, the inner diameter D _I of the laser emission hole of the laser nozzle should be 4 mm or more and 8 mm or less, and the outer diameter D _O should be 15 mm or more, and the distance between the center of the laser nozzle and the tip of the TIG electrode 2 mm or more and 5 mm or less, or in addition to these conditions, the TIG shielding gas flow rate must be 5/min or more and 20
/min or less, the laser energy contributing to penetration is maximized under the given laser power, TIG power, and welding speed, and maximum penetration is obtained.

(effect) The present invention will be explained in detail below based on the drawings.

FIG. 1 is a schematic diagram of a nozzle section according to the invention. In the figure, the inner diameter of the laser nozzle is D _I , the outer diameter is D _O , the horizontal distance between the center of the laser nozzle and the tip of the TIG electrode is l , and the flow rate of the laser gas (center gas) is
Let f _C be the flow rate of TIG gas (side gas) and f _S be the TIG gas (side gas) flow rate. Now, the most important thing here is that the amount of penetration is closely related to the plasma generated during welding. That is, the larger the plasma generated to some extent, the greater the absorption of laser light, and the more energy that contributes to welding is taken away. Also, if plasma is formed at a certain distance from the TIG electrode, the melted part caused by TIG will solidify before absorbing the laser energy.
The combined effect is reduced. So D _I , D _O , l, f _C , f _S
We will consider realizing various gas pressure distributions in the weld zone by changing the , and thereby controlling the position and size of the plasma. Based on the above idea, we conducted an experiment and found the following.

When we investigated the relationship between the inner diameter D _I of the laser nozzle, the plasma, and the penetration depth, we found that as D _I increases, the plasma size decreases monotonically, and the penetration tends to become deeper. Both are stable.

We investigated the relationship between the outer diameter D _O of the laser nozzle, the plasma, and the penetration depth, and found that when the D _O is less than 15 mm, the plasma size varies;
Above, the size decreases monotonically and the penetration tends to become deeper, and both become stable when D _O =20 mm or more.

When we investigated the relationship between the horizontal distance l between the center of the laser nozzle and the tip of the TIG electrode and the plasma penetration depth, we found that when l = 2 to 5 mm, the plasma is drawn toward the TIG electrode, and when l exceeds 5 mm, the plasma tends to move away from the TIG electrode. It is in. On the other hand, the penetration depth decreases as the plasma moves away.

When the TIG gas flow rate f _S exceeds 20/min
As the plasma leaves the TIG electrode, the penetration depth decreases.

Note that this result is based on a laser power of 8kW (constant).
TIG current 100A (constant), welding speed 8m/min (constant)
Although the results were obtained under conditions such as a distance of 10 mm from the nozzle tip to the workpiece, it has been confirmed that similar results can be obtained under other conditions.
The evaluation of penetration was performed using a 3 mm thick SUS304 flat plate, and helium gas was used as the processing gas for both laser gas and TIG gas.

Based on the above knowledge, the inner diameter of the laser nozzle was set to 4
It was set to mm or more. Furthermore, in consideration of gas loss caused by making the nozzle inner diameter too large, the upper limit was set to 8 mm or less. Furthermore, based on the above facts, the outer diameter D _O of the laser nozzle was set to 15 mm or more. There is no particular upper limit as long as there is no contact with other devices. Based on the above facts, the distance l between the center of the laser nozzle and the tip of the TIG electrode was set to 2 mm or more and 5 mm or less. Furthermore, based on the above facts, the TIG shielding gas flow rate was set to 20/min or less. In addition, the lower limit was set at 5/min in consideration of the wear and tear of the TIG electrode caused by reducing the gas flow rate too low.

(Example) Below, an example of pipe making using the present invention will be shown.

FIG. 2 is a schematic diagram of the pipe production line. The laser beam emitted from the laser oscillator 3 is used for mirror welding 8
After changing its direction by _-1 and 8 _-4 , the light is focused by a lens 6 and irradiated from the laser nozzle 1 to the welding part.

FIG. 3 is an enlarged view of the laser nozzle portion. The laser nozzle part is integrated with the tip of the TIG torch 2, and the positional relationship between the two and the inner and outer diameters of the laser nozzle are set based on the present invention.
It is designed to irradiate the melted part. On the other hand, in FIG. 2, the pipe to be welded 9 has a slit 10 in the pipe manufacturing direction.

During welding, squeeze rolls 5 _-1 and 5 _-2 are used to press from the left and right to bring both sides of the slit into close contact, and then a laser beam and a laser beam are applied to the contact area from directly above.
Welding was performed by irradiating TIG arc.

The welding conditions are as follows: Pipe to be welded: Slit pipe material SUS304, outer diameter 30mm, thickness 3mm Laser oscillator: Ring mode (M = .5) Power 8kW Laser nozzle: Inner diameter 4mm, Outer diameter 2mm, Laser gas He40/min TIG welding machine: TIG current 100A, TIG gas He10/min Pipe forming speed: 8m/min Distance from nozzle tip to pipe surface 10mm Horizontal distance between laser nozzle center and TIG electrode tip 3mm or more A weld bead with free welding was obtained quickly and stably.

(Effects of the Invention) As described above, by using the present invention, the position and size of the plasma can be set so that the laser energy makes the largest contribution to the welded part and the combined effect becomes the largest.

When welding is performed under such optimal combined conditions, there are remarkable effects such as maximum penetration and a dramatic improvement in the quality of the welded part.

[Brief explanation of the drawing]

Fig. 1 is a side view showing the tip of the laser nozzle and the tip of the TIG torch, Fig. 2 is a schematic diagram showing an embodiment of the present invention, and Fig. 3 is a nozzle when the present invention is implemented. FIG. 1... Laser nozzle, 2... TIG torch, 3... Laser oscillator, 4... TIG welding machine, 5... Squeeze roll, 6... Lens, 7... Optical path duct, 8... Transmission mirror, 9... Welding pipe, 10... Slit, 11 ...Laser beam, 12...TIG arc, 13...Workpiece,
14...Moving direction of the material to be welded.

Claims (1)

[Claims] 1. In welding steel materials using a combination of laser and TIG,
The inner diameter D _I of the laser emission hole of the laser nozzle should be 4 mm or more and 8 mm or less, and the outer diameter D _O should be 15 mm or more, and the distance l between the center of the laser nozzle and the tip of the TIG electrode.
A combined laser and TIG welding method characterized by welding with a diameter of 2 mm or more and 5 mm or less. 2 Increase the flow rate of TIG shielding gas to 5/min or more20
2. The combined laser and TIG welding method according to claim 1, wherein the welding speed is less than /min.