CN111673280B - Double-beam parallel laser welding device and method for T-shaped joint lap welding - Google Patents

Abstract

A double-beam parallel laser welding device and method for T-shaped joint lap welding comprises two laser emitters arranged in tandem along a welding direction; the laser beam emitted by each laser emitter is divided into two parallel laser beams by the spectroscope, two laser spots of the two parallel laser beams in front melt the panel to form a keyhole, the energy of the two laser spots is insufficient to support the panel to melt the web, and the spots of the laser beams in rear melt the panel to form a rear keyhole on the web. The laser is divided into two parallel laser beams by the spectroscope, spots formed by the two laser beams on the panel have gaps, and a diffused keyhole is formed when the laser beams irradiate the panel, so that the opening size of the keyhole is increased, the stability of the keyhole is improved, and the generation of welding bubbles is reduced; meanwhile, the double parallel laser beams can increase the welding seam overlapping area of the T-shaped overlapping joint and improve the shearing strength of the T-shaped overlapping joint.

Description

A dual-beam parallel laser welding device and method for T-joint lap welding

technical field

The invention relates to the field of laser welding, in particular to a dual-beam parallel laser welding device and method for lap welding of T-shaped joints.

Background technique

In recent years, T-lap welding technology has been applied in aerospace, marine and other fields. Laser welding has been widely used in the welding of T-type lap joints due to its advantages of fast welding speed, small stress and deformation. Laser welding T-type lap joint, the process is to select a panel and a web to lap to form a T-type, and then apply a laser heat source to the panel to melt and penetrate the panel material in the action area, further The web is partially melted, and the panel and web are melted and combined to form a T-shaped lap joint after cooling and solidification.

Dr. Meng Wei from Shanghai Jiaotong University's doctoral dissertation "Research on the Dynamic Process and Forming Characteristics of Laser Welding of High Strength Steel T-lap Joints", which discusses the most important feature of the single-beam laser welding process of T-lap joints is that with the increase of the gap, The main reason for the increase of bubbles is that when the gap is small, the web at the gap melts to form a molten pool. Under the action of surface tension, the molten metal of the web and the panel is combined together, and the molten metal at the gap can connect the upper and lower molten pools. , forming a complete keyhole for the connection between the web and the panel. However, as the gap increases, the continuity of the molten pool is cut off, and the gap between the panel and the web causes the front wall of the keyhole to collapse, and the plasma escapes from the collapsed front wall of the keyhole, resulting in a weakening of the vapor pressure inside the keyhole. As a result, the size of the opening of the keyhole is reduced, the vibration of the tip of the keyhole is intensified, and a large number of air bubbles are generated.

SUMMARY OF THE INVENTION

In order to solve the problems of the collapse of the front wall of the keyhole and the increase in the number of welding seam pores caused by the gap between the panel and the web cutting the continuity of the molten pool when the T-shaped lap joint is welded, the present invention provides a T-shaped lap welding Using a dual-beam parallel laser welding device and method, the method consists of setting two laser beams before and after, and the two laser beams are divided into two parallel laser beams by a beam splitter, and there is a gap between the two parallel laser beams formed by the same laser beam. When it is on the panel, a diffused keyhole is formed, which is beneficial to improve the stability of the keyhole while increasing the opening size of the keyhole, and also increases the overlap area of the weld seam and improves the resistance of the T-shaped lap joint. Shear strength.

The technical solution adopted by the present invention to solve the above technical problems is: a double beam parallel laser welding device for lap welding of T-shaped joints, wherein the T-shaped joint is composed of a vertical web and a horizontally arranged web on the web. The panels are formed by overlapping, and there is a gap between the web and the panel. The dual-beam parallel laser welding device includes two laser emitters, two beam splitters and a shielding gas nozzle, wherein the two laser emitters are along the welding The direction is set in tandem;

The laser beam emitted by the laser transmitter located in the front is divided into two parallel front laser beams by a beam splitter. The two laser spots formed by the two parallel front laser beams on the panel melt the panel to form a front keyhole, and the front The energy of the laser beam is not enough to support it to melt the web;

The laser beam emitted by the laser transmitter located at the rear is divided into two parallel rear laser beams by another beam splitter. The two parallel rear laser beams form two laser spots on the panel, which are formed on the web after the panel is fused through. a rear keyhole;

The front keyhole and the rear keyhole together form a molten pool, and the protective gas spray head communicated with the protective gas source sprays the protective gas onto the molten pool.

As an optimized solution of the above-mentioned dual-beam parallel laser welding device, the distance between the front laser beam and the rear laser beam is 0.5-2.0mm, the distance between the laser spots formed by the two front laser beams is 0.05-0.3mm, and the two beams The spacing of the laser spots formed by the rear laser beam is 0.05-0.3 mm.

As another optimization solution of the above-mentioned dual-beam parallel laser welding device, the energy ratio of the two front laser beams divided by the beam splitter is 1:1, and the energy ratio of the two rear laser beams is also 1:1.

As another optimized solution of the above-mentioned dual-beam parallel laser welding device, the gap between the web and the panel is 0.2-0.8 mm.

The welding method of the double-beam parallel laser welding device used for the above-mentioned T-joint lap welding comprises the following steps:

1) The web and the panel are surface-treated, and then the panel is lapped on the web and a gap is reserved. Both ends of the panel and the web are fixed by laser spot welding to form a T-joint prototype and fixed with a welding fixture;

2) Along the welding direction, place the two laser emitters in tandem, and then place the two beam splitters on the laser paths of the two laser emitters, so that when the two laser emitters emit laser light, Divided into two parallel front and rear laser beams;

3) Activate the two laser transmitters so that the two parallel front and rear laser beams form a molten pool on the panel;

4) Start the protective gas nozzle to spray protective gas to the molten pool to protect it with gas.

As an optimization scheme of the above welding method, the power of the laser transmitter in front of the welding direction is 600-5000W, the power of the laser transmitter in the rear is 800-10000W, and the welding speed is 0.5-10m/min.

As another optimized solution of the above welding method, the distance between the front laser beam and the rear laser beam is 0.5-2.0mm, and the distance between the two front laser beams or the distance between the two rear laser beams is equal to 0.05-0.3mm.

Compared with the prior art, the present invention has the following beneficial effects:

1) The present invention divides the laser into two parallel laser beams through a beam splitter, and the spots formed by the two laser beams on the panel have a gap. When irradiated on the panel, a diffused keyhole is formed, which increases the size of the keyhole opening. At the same time, it is beneficial to improve the stability of the keyhole and reduce the generation of welding bubbles; at the same time, the double parallel laser beams can increase the welding seam lap area of the T-shaped lap joint and improve the shear resistance of the T-shaped lap joint. Strength (because the larger the overlap area of the weld, the greater the shear strength of the T-lap joint);

2) The present invention adopts two parallel laser beams at the front and the rear. The two parallel laser beams in the front of the welding direction only penetrate the panel without melting the web, and the two parallel laser beams at the rear of the welding direction penetrate the panel and melt the web at the same time. plate, so that the parallel laser beam in the front can provide liquid metal for the laser beam keyhole at the rear (because the panel is melted), which not only ensures the continuity of the molten pool formed by the laser beam at the rear, but also avoids the front wall of the keyhole Collapse occurs, allowing the steam pressure inside the keyhole to escape from the opening of the keyhole.

Description of drawings

Fig. 1 is the working principle diagram of the present invention;

Fig. 2 is the schematic diagram of the keyhole and molten pool of the existing single-beam laser welding T-shaped lap joint gap;

3 is a schematic diagram of a keyhole and a molten pool of the double-beam parallel laser welding T-shaped lap joint gap of the present invention;

FIG. 4 is a schematic diagram of a cross-sectional view of a welding seam of an existing single-beam laser welding T-shaped lap gap;

FIG. 5 is a schematic diagram of the longitudinal section of the weld of the existing single-beam laser welding T-shaped lap joint gap;

6 is a schematic diagram of the cross-sectional view of the weld of the dual-beam parallel laser welding of the T-shaped lap joint gap according to the present invention;

FIG. 7 is a schematic diagram of the longitudinal section of the weld of the dual beam parallel laser welding of the T-shaped lap joint gap according to the present invention;

Reference numerals: 1. Front laser beam, 2. Rear laser beam, 3. Front keyhole, 4. Back keyhole, 5. Weld pool, 6. Protective gas nozzle, 7. Panel, 8. Web, 9. Beamsplitter.

Detailed ways

The technical solutions of the present invention will be further elaborated below in conjunction with specific embodiments. The parts not described in the following embodiments of the present invention, such as the laser transmitter, the beam splitter 9, the protective gas nozzle 6 and the protective gas source, are all Existing technology, and therefore will not be described in detail.

Example 1

As shown in FIG. 1 , a dual beam parallel laser welding device for lap welding of T-shaped joints, the T-shaped joints are formed by overlapping a vertical web 8 and a panel 7 horizontally arranged on the web 8, And there is a gap between the web 8 and the panel 7, the double beam parallel laser welding device includes two laser emitters, two beam splitters 9 and a shielding gas nozzle 6, wherein the two laser emitters are along the welding direction. Set in tandem;

The laser beam emitted by the laser transmitter located at the front is divided into two parallel front laser beams 1 by a beam splitter 9, and the two parallel front laser beams 1 form two laser spots on the panel 7 to melt the panel 7 to form a front laser beam. Keyhole 3, and the energy of the front laser beam 1 is not enough to support it to melt the web 8;

The laser beam emitted by the laser transmitter located at the rear is divided into two parallel rear laser beams 2 by another beam splitter 9. The two parallel laser beams 2 form two laser spots on the panel 7 after the panel 7 is melted A rear keyhole 4 is formed on the web 8;

The front keyhole 3 and the rear keyhole 4 together form a molten pool 5 , and the protective gas spray head 6 communicated with the protective gas source sprays the protective gas onto the molten pool 5 .

The welding method of the above-mentioned double-beam parallel laser welding device for lap welding of T-shaped joints includes the following steps:

1) Surface treatment of the web 8 and the panel 7 to remove impurities on their surfaces, and then the panel 7 is lapped on the web 8 and a gap is reserved. The ends of the panel 7 and the web 8 are fixed by laser spot welding. A T-joint prototype and fixed with a welding fixture;

2) Along the welding direction, place the two laser emitters in tandem, and then place the two beam splitters 9 on the laser paths of the two laser emitters, so that when the two laser emitters emit laser light, the It is divided into two parallel front laser beam 1 and rear laser beam 2;

3) Start the two laser transmitters, so that the two parallel front laser beams 1 and rear laser beams 2 form a molten pool 5 on the panel 7;

4) Start the protective gas nozzle 6 to spray protective gas to the molten pool 5, so as to carry out gas protection.

In this embodiment, the protective gas generally refers to argon or helium.

In this embodiment, after starting the laser transmitter and the protective gas nozzle 6, welding can be performed according to a conventional laser welding method.

The above are the basic embodiments of the present invention, and further improvements, optimizations and limitations can be made on the above basis, thereby obtaining the following optimized examples:

Example 2

This embodiment is a limitation on the placement of the two laser emitters and the beam splitter 9 in the dual-beam parallel laser welding device. The placement of the two laser emitters enables the front laser beam 1 and the rear laser beam to be placed. The spacing of 2 is 0.5-2.0mm, the placement of the two beam splitters 9 can make the spacing of the laser spots formed by the two front laser beams 1 be 0.05-0.3mm, and the spacing of the laser spots formed by the two rear laser beams 2 is 0.05-0.3mm.

Example 3

The present embodiment is a further limitation of the placement positions of the two beam splitters 9 in the double-beam parallel laser welding device, and the beam splitter 9 can make the energy ratio of the two front laser beams 1 divided into 1 after being placed: 1. The energy ratio of the laser beam 2 after the two beams is also 1:1.

Example 4

In this embodiment, the gap between the web 8 and the panel 7 in the dual-beam parallel laser welding device is defined, and the gap between the web 8 and the panel 7 is 0.2-0.8 mm.

Example 5

This embodiment is the limitation of the power of the two laser transmitters during welding of the dual-beam parallel laser welding device, and the optimization limitation of the welding speed under this power. The power of the laser transmitter located in front of the welding direction is 600-5000W, The power of the rear laser transmitter is 800-10000W, and the welding speed is 0.5-10m/min.

Comparing the present invention with the prior art (T-type lap joint single-beam laser welding method), under the same welding conditions, the cross-sectional schematic diagrams of the keyhole and molten pool formed by the two during the welding process are shown in Figures 3 and 3, respectively. As shown in Figure 2, it can be clearly seen from the figure that the molten pool of the present invention has better continuity, and the opening of the keyhole is larger, which improves the stability of the keyhole, avoids the collapse of the front wall of the keyhole, and is more convenient The vapor pressure inside the keyhole escapes from the opening direction of the keyhole;

4 and 5 are schematic diagrams of the cross-section and the longitudinal section of the welding seam of the existing single-beam laser welding T-shaped lap gap;

Fig. 6 and Fig. 7 are the schematic diagrams of the weld cross section and longitudinal section of the double beam parallel laser welding T-shaped lap gap of the present invention;

It can be found from the comparison of FIG. 4 and FIG. 6 that the lap width of the welding seam of the present invention is obviously larger than the width of the existing single-beam laser welding lap welding seam, which is beneficial to improve the shear strength of the T-shaped lap joint;

It can be found from the comparison between FIG. 5 and FIG. 7 that the number of pores in the longitudinal section of the weld of the present invention is significantly lower than the number of pores in the longitudinal section of the existing single-beam laser welding lap weld. Pre-melting the panel in front of the laser beam of the web can provide liquid metal in front of the keyhole wall of the laser beam that melts the web and panel, thus ensuring the continuity of the molten pool formed by the laser beam melting the web and panel, avoiding keyholes The collapse of the front wall allows the steam pressure inside the keyhole to escape from the opening of the keyhole, reducing the generation of welding pores.

Moreover, from the comparison of Figure 5 and Figure 7, it can be found that the bottom of the weld in Figure 5 has a undulating shape, while the bottom of the weld in Figure 7 is relatively flat. The instability of the keyhole in the process results in a large fluctuation in the absorption of the laser energy by the keyhole wall, while the present invention melts the panel in advance of the laser beam for melting the panel and the web, which can be used for melting the web and the panel. Liquid metal is provided in front of the hole wall, which not only ensures the continuity of the molten pool formed by the laser beam that melts the web and the panel and the stability of the keyhole, but also because the two laser beams branched by the spectroscope together form a large keyhole, which also Can improve the stability of the keyhole.

Claims (7)

1. A double-beam parallel laser welding device for T-joint lap welding, wherein the T-joint is formed by overlapping a vertical web (8) and a panel (7) horizontally arranged on the web (8), and a gap is reserved between the web (8) and the panel (7), and the device is characterized in that: the double-beam parallel laser welding device comprises two laser transmitters, two spectroscopes (9) and a protective gas spray head (6), wherein the two laser transmitters are arranged in tandem along the welding direction;

the laser beam emitted by the laser emitter positioned in front is divided into two parallel front laser beams (1) by a spectroscope (9), the two laser spots formed on the panel (7) by the two parallel front laser beams (1) melt the panel (7) to form a front keyhole (3), and the energy of the front laser beam (1) is not enough to support the front laser beam to melt the web (8);

a laser beam emitted by a laser emitter positioned at the rear is divided into two parallel rear laser beams (2) by another spectroscope (9), the two laser spot points formed by the two parallel rear laser beams (2) on the panel (7) melt the panel (7) through, and then a rear key hole (4) is formed on the web (8);

the front key hole (3) and the rear key hole (4) together form a molten pool (5), and the protective gas nozzle (6) communicated with a protective gas source sprays protective gas onto the molten pool (5).

2. The double-beam parallel laser welding device for T-joint lap welding according to claim 1, characterized in that: the distance between the front laser beam (1) and the rear laser beam (2) is 0.5-2.0mm, the distance between laser spots formed by the two front laser beams (1) is 0.05-0.3mm, and the distance between laser spots formed by the two rear laser beams (2) is 0.05-0.3 mm.

3. The double-beam parallel laser welding device for T-joint lap welding according to claim 1, characterized in that: the energy ratio of the two front laser beams (1) divided by the spectroscope (9) is 1:1, and the energy ratio of the two rear laser beams (2) is 1: 1.

4. The double-beam parallel laser welding device for T-joint lap welding according to claim 1, characterized in that: the clearance between the web plate (8) and the panel (7) is 0.2-0.8 mm.

5. The welding method of the double-beam parallel laser welding apparatus for T-joint lap welding according to claim 1, characterized by comprising the steps of:

1) carrying out surface treatment on the web plate (8) and the panel (7), then overlapping the panel (7) on the web plate (8) and reserving a gap, and fixing two ends of the panel (7) and the web plate (8) by using laser spot welding to form a T-shaped joint prototype and fixing the T-shaped joint prototype by using a welding clamp;

2) the method comprises the following steps that two laser transmitters are placed in tandem along a welding direction, and then two spectroscopes (9) are respectively placed on laser paths of the two laser transmitters, so that the lasers emitted by the two laser transmitters are divided into a front laser beam (1) and a rear laser beam (2) which are in parallel;

3) starting two laser emitters so that two parallel front laser beams (1) and rear laser beams (2) form a molten pool (5) on a panel (7);

4) and starting a protective gas spray head (6) to spray protective gas to the molten pool (5) so as to carry out gas protection on the molten pool.

6. The welding method of the double-beam parallel laser welding apparatus for T-joint lap welding according to claim 5, characterized in that: the power of the laser transmitter positioned in the front of the welding direction is 600-5000W, the power of the laser transmitter positioned in the rear is 800-10000W, and the welding speed is 0.5-10 m/min.

7. The welding method of the double-beam parallel laser welding apparatus for T-joint lap welding according to claim 5, characterized in that: the distance between the front laser beam (1) and the rear laser beam (2) is 0.5-2.0mm, and the distance between the two front laser beams (1) or the distance between the two rear laser beams (2) is 0.05-0.3 mm.

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