JPS6330193A - Laser welding method - Google Patents

Abstract

PURPOSE:To weld thick plates at a high speed with an inexpensive medium output laser by performing the deep-penetration welding on the surface side of the plate and afterward, performing the MIG welding on its rear side. CONSTITUTION:A groove shape of objects 1 to be welded is worked in an inverted Y type and the surface side is made to a groove part 2 for the laser welding and the rear side is made to a groove part 3 for the MIG welding. Then, the surface side is subjected to the deep-penetration welding by the laser beam 14 and afterward, the rear side is subjected to the MIG welding by generating a MIG welding arc 10. Since a plasma-shaped product by the laser beam 14 is absorbed and eliminated by the arc 10, the laser welding can be performed at a high speed and since the product exists on the rear side, the MIG welding arc is stabilized thereon. As a result, the thick plates with thickness 15mm, for instance, can be welded at a high speed of 1m/min by a 3 KWCO2 laser beam machine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser welding method for thick plates, which is applied when double-stroke welding thick plates by combining a medium-power laser and conventional MIG welding.

[Conventional technology]

Conventional method As shown in Figure 4, a laser beam 14 emitted from an oscillator 13 is transmitted through a lens 16 to a laser beam of 106 to 10" W.
The light is focused on a high energy density spot called /crd,
Melt welding is performed by irradiating the surface of the object 1 to be welded. that time,
A plasma-like product 20 due to the metal vapor is generated, which absorbs the laser beam 14 and reduces the penetration depth in laser welding. As a countermeasure, use helium and argon.

A single gas such as carbon dioxide gas or a mixed gas is supplied from the gas supply port 18 to the nozzle 17 and flowed coaxially with the laser beam 14 to the workpiece 1 to remove plasma-like products 20 generated at the welding part and perform welding. This prevents the parts from being oxidized by atmospheric gases. However, with this method, only the penetration depth corresponding to the laser output can be obtained.
Two lasers are used, and the radius is 14 to 15 mm. In addition, in this case, since the welding is done on one side, the bead on the back side is thin and pores are generated, and there are many problems to be solved in practical use.

[Problem that the invention seeks to solve]

In the conventional laser welding method, as shown in FIG. 4, a plasma-like product is generated near the surface of the workpiece and the laser beam is absorbed by this product, thereby reducing the penetration depth.

For this reason, gas is supplied, but even in that case, the penetration depth can only be obtained in accordance with the beam output, and an expensive 10 nV class high output laser device is required for welding thick plate materials.

[Failure to solve the problem]

In order to solve the above-mentioned problems, the present invention makes it possible to weld thick plate materials by performing double-sided welding using a medium-power laser and MIG welding in combination.

This is a welding method in which the plasma-like products generated in laser welding are sucked in by the MIG welding arc, thereby eliminating the bad writing and improving the stability and concentration of the MIG welding arc.

In other words, in a welding method in which plates are butted together using a laser beam, deep penetration welding is performed with a laser from the front surface of the workpiece, and then MIG welding is performed from the back side of the workpiece to place an arc at the position of the plasma generated by the laser beam. The present invention provides a laser welding method characterized in that a laser beam is generated to perform groove welding and MIO welding is used in combination.

[Effect]

Since the laser welding method of the present invention is the welding method described above, the plasma-like products generated when performing penetration welding with laser welding in advance have grooves not only on the front side but also on the back side. Because of this, it also occurs on the back side. In this case, in order to generate the MIG welding arc from the back side at the laser generation position (the position of the plasma-like product generated by the laser beam),
The plasma-like product on the surface side generated by the laser is this M
It is removed by suction by the IG welding arc, and there is no reduction in penetration depth. In addition, the removed products collect at the plasma-like product on the back side, improving the arc stability and arc concentration of MI (3) welding. Depending on the situation, a combination of laser welding and MIG welding may be used. This allows for good welding.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments shown in the drawings. FIG. 1 is an explanatory diagram showing a welding situation to which a laser welding method according to an embodiment of the present invention is applied. FIG. 2 is a sectional view showing the groove shape of the workpiece according to this embodiment. FIG. 3 is a cross-sectional view of the groove welded part of the workpiece according to this embodiment. Before explaining this welding method, the material to be welded is SUS 3Q4.

Plate thickness: 14 aun, contact surface dimensions: 6 strokes, bevel angle: 6
Butt welding was performed at 0°. The execution conditions are (1) Laser output (downward posture); 3KWCO2v-the; speed 1m/
Minutes.

Shielding gas; Ha, (2) MI (3 welding current (upward posture), 300A, speed i 1 m/e, V
-/Ii degas; L[c.

Welding wire; MIO wire, SUS 804,
01.2 mark.

Aim position of welding wire; near laser beam irradiation area.

1st. In Fig. 2, the groove shape of the welded material 41JJ1 is machined into an inverted Y shape, the contact surface 2 is welded by the laser welding method, and the back side 3 with the groove is processed by the MIG;@contact method.

Double-sided welding is performed as shown in Figure 1.

That is, V-za welding of the contact surface 2 is preceded by 2 penetration welding, and then a BFL G welding arc 1o is generated at the laser welding part @ (the position of the plasma generated by the laser beam) from the back surface, and welding is performed. Feeding wire 7 to motor 9.
Gases such as Ar, He, and CO2 were automatically and continuously fed by the feed roller 8, and gases such as Ar, He, and CO2 were supplied singly or in a mixture from the shield gas supply port 5, and the welding part was isolated from the atmosphere by the nozzle 4. In this state, use the welding power source 6 to simultaneously move the welding torch 4 in the direction of the laser welding arrow, and as shown in Figure 3, the front side is laser welded and the back side is welded.
This is a method of performing IIj welding.

I performed penetration welding with laser welding in a downward position.

If the MIO welding arc 10 was not generated, the plasma-like product 20 would have been generated on the surface of the stainless steel of the workpiece 1, but when welding above the back surface, the laser beam generation position (plasma-like product generated by the laser beam) position of the object)
When ITU welding arc 10 is generated, this arc 10
As a result, the plasma-like product 20 is attracted and disappears, and the laser beam 14 is no longer absorbed by the plasma-like product 20.

The welding speed could be increased. Furthermore, since the slag and plasma-like products 20 were present on the back side of the groove, a stable arc 10 could be easily obtained in MIG welding, and good welding could be performed.

The welding position is schematically shown in Fig. 3, where the plate thickness 15 mark is 3 mm, and the speed of the VCO2 laser processing machine and MIG welding machine is 1.
High speed welding of n7% was possible.

The welded part had a good bead shape on both the front and back sides, and there were no welding defects such as poor penetration or pores, and good results were obtained.

How to weld a plate with a thickness of 14 mm using a conventional laser alone.

This is an industrially effective method because it requires an expensive CO2 laser with an output of 10 KW, but can be done with inexpensive fx equipment with an output of 1 to 5 KW in rice.

〔Effect of the invention〕

As specifically explained above, in the present invention, high-speed welding of thick plate materials is possible at low cost by using a double-sided welding method using a combination of a medium-power laser and biIG welding, and by using a combination of an inexpensive medium-power laser and iIG welding. It is possible to remove plasma-like products that are a hindrance to laser welding, and to make effective use of this to achieve high-speed welding. , MI from the back side
When the G welding arc is generated, the plasma-like products generated during laser welding are sucked and removed by the 'vfIG welding arc, and in addition to speeding up laser welding, these plasma products are also removed from the back side of the groove. Stay focused, M.I.G.
This stabilizes the welding arc and improves arc concentration, allowing high-speed welding. Also, because it uses a double-sided welding method.

Compared to the conventional single-sided welding method, the bead shape is more stable and the problem of porosity can be prevented by welding two single-sided welds.

[Brief explanation of the drawing]

1 is an explanatory diagram showing a welding situation in which the laser welding method according to the embodiments of the present invention is applied; FIG. 2 is a sectional view showing the groove shape of a workpiece according to the present embodiment; The figure is a cross-sectional view of the groove welding part of the welded object according to the double welding method, and FIG. 4 is an explanatory diagram showing the welding situation of the conventional laser welding method. 1... Workpiece to be welded, 2... Groove for laser welding, 3...
... MIG welding groove, 4...5 [G welding torch,
5... Shield dregs supply port, 6... Welding power source, 7°
゛Welding wire, 8... Wire supply roller, 9... Wire supply motor, 10''... iIG welding arc, 11...
・Laser welding part, 12...ΔfIo bath contact part, 13...
・Laser oscillator. 14...Laser beam, 15...Direction conversion mirror,
16... Condenser lens, 17... Shield nozzle, 1
8... Shield dregs supply port, 19... Heating melting part,
20...Plasma-like product

Claims (1)

[Claims] In a welding method that uses a laser beam to butt plates together, deep penetration welding is performed with a laser from the front surface of the workpiece, and then MIG welding is performed from the back side of the workpiece to generate an arc at the position of the plasma generated by the laser beam. A laser welding method characterized by using a groove welding laser and MIG welding together.