阅读说明：本技术 用于蒙皮-桁条t型接头的蒙皮预置双凸台方法及其焊接工艺 (Skin pre-arrangement double-boss method for skin-stringer T-shaped joint and welding process thereof ) 是由 占小红 刘婷 赵艳秋 吴友发 龚星如 郑权 史立涛 于 2019-03-28 设计创作，主要内容包括：本发明公开了一种用于T型接头的蒙皮预置双凸台结构及其焊接工艺,其特点在于,在蒙皮与桁条的连接处预置了双凸台。通过设计合适的凸台间距与凸台高度,使凸台代替填充焊丝的同时便于桁条的装夹。对于蒙皮预置双凸台T型接头结构的焊接工艺,具体步骤如下：将蒙皮预置双凸台的T型结构进行焊前处理；将桁条置于蒙皮的双凸台之间并使用专用夹具进行固定；调整激光光束入射和保护气喷嘴的位置,保证桁条两侧激光束分别聚焦在双凸台外侧棱边上；开展双激光束双侧同步焊接。使用该结构与工艺对蒙皮-桁条T型接头进行焊接,使复杂的双激光束双侧同步填丝焊接过程简单化,从而大大提高焊接效率。(The invention discloses a skin preset double-boss structure for a T-shaped joint and a welding process thereof. Through designing proper boss spacing and boss height, the clamping of the stringer is convenient while the boss replaces the filler wire. The welding process for the skin preset double-boss T-shaped joint structure comprises the following specific steps: performing pre-welding treatment on the T-shaped structure with the skin provided with the double bosses in advance; placing a stringer between the double bosses of the skin and fixing the stringer by using a special clamp; adjusting the positions of laser beam incidence and a shielding gas nozzle to ensure that laser beams on two sides of the stringer are respectively focused on edges on the outer sides of the double bosses; and carrying out double-laser-beam bilateral synchronous welding. The structure and the process are used for welding the skin-stringer T-shaped joint, so that the complicated double-laser-beam bilateral synchronous wire filling welding process is simplified, and the welding efficiency is greatly improved.)

1. A preset double-boss structure for a skin-stringer T-shaped joint is characterized in that two cuboid bosses are processed on the skin and are positioned at the joint of a stringer and the skin.

2. A welding process for a skin preset double-boss T-shaped joint structure is characterized by comprising the following specific steps:

step 1, performing surface treatment before welding on a T-shaped joint structure with a skin preset with double bosses;

step 2, placing the stringer subjected to surface treatment before welding between the skin double bosses and fixing the stringer by using a special clamp;

step 3, adjusting the positions and angles of the laser beams and the protective gas nozzles to ensure that the laser beams on the two sides of the stringer are respectively focused on the outer edges of the double bosses;

and 4, after confirming that no error exists, carrying out a double-laser-beam double-side synchronous welding process, namely completing welding.

3. The skin double boss structure of claim 1, wherein the double bosses are located on both sides of the stringer, and the spacing is 1.25% -2.5% greater than the thickness of the stringer.

4. The skin double boss structure of claim 1, wherein the height and width of the double boss are the same, and the height is 30% -37.5% of the thickness of the stringer.

5. The welding process for the skin pre-arranged double-boss T-shaped structure according to claim 2, wherein the step 1 specifically comprises the following steps:

(a) polishing the surface of the area where the skin is connected with the stringer by using an electric grinder, and removing a surface oxide film;

(b) wiping the skin and the stringer by using acetone and alcohol, removing impurities such as oil stains on the surface, and drying by using an oven;

(c) and packaging the dried and cooled skin and the stringer by using a preservative film to prevent secondary oxidation.

6. The welding process for the skin pre-arranged double-boss T-shaped structure according to claim 2, wherein the step 3 specifically comprises the following steps:

(a) adjusting the position and angle of the laser beam to focus the laser beams on the two sides of the stringer on the edges of the outer sides of the double bosses respectively, and ensuring that the bosses are completely melted in the synchronous welding process of the two sides of the double laser beams so as to form a combined molten pool;

(b) and adjusting the position of the protective gas nozzle to align the protective gas nozzle to the double bosses on the skin, so as to ensure that the welding line is always in the protective gas atmosphere in the double-laser-beam double-side synchronous welding process.

7. The welding process for the skin pre-arranged double-boss T-shaped structure according to claim 2, wherein the step 4 specifically comprises the following steps:

(a) teaching by using a welding robot, checking a welding path, and checking whether the center of a laser beam is always aligned with the edge at the outer side of the double bosses and whether a shielding gas nozzle is always aligned with the double bosses in the teaching process;

(b) and the double-laser-beam double-side synchronous welding is performed on the premise that the welding path is correct.

Technical Field

The invention belongs to the field of laser welding processes, and particularly relates to a skin preset double-boss structure for a T-shaped joint and a welding process thereof.

Background

The laser welding technique is an efficient and precise welding method using a laser beam with high energy density as a heat source. The laser welding has the advantages of high energy density, high welding speed, large depth-to-width ratio of a welding line, narrow heat affected zone and the like. In the laser welding process, the surface of a workpiece is heated by laser radiation to be rapidly heated to a temperature above a melting point, surface heat is diffused inwards by heat conduction, and a molten pool is formed. And forming a welding seam after the liquid metal in the molten pool is solidified, thereby realizing the connection of the two workpieces. By controlling parameters such as laser power, welding speed and protective gas flow, a proper molten pool can be formed on the workpiece, and the optimal connection effect is achieved. Laser welding has been successfully applied in the fields of aerospace, automobile manufacturing, precision welding of miniature parts and the like.

The double-laser-beam double-side synchronous welding process for the skin-stringer T-shaped structure is a brand-new connecting technology, is different from the traditional single-side welding process for the T-shaped structure, and ensures the integrity of the outer surface of the skin, so that the double-laser-beam double-side synchronous welding process is widely applied to structures such as airplane fuselage panels and the like which have high requirements on the integrity of the aerodynamic appearance of the outer surface of the skin.

On the other hand, the laser filler wire welding technology can meet the size limitation of the assembly gap of the butt plate, and the metallurgical adjustment of the welding seam structure of the laser welding can be realized by changing the chemical composition of the welding wire. For complex curved surface welding structures, laser filler wire welding has certain limitations on the feeding direction of welding wires. The stable melting and filling of the welding wire are key factors for ensuring the welding stability, and the feeding of the welding wire has a large influence on the stability of the keyhole, so that the problems of poor welding seam formation in the laser wire filling process are caused, such as uneven welding seams, discontinuous welding seams and the like, and the appearance and the performance of the welding seams are seriously influenced.

In view of the above problems, how to ensure the stability of the double-laser-beam double-side synchronous welding process of the T-shaped connection structure becomes an important issue to be paid attention by people in the related art.

Disclosure of Invention

The invention provides a welding piece structure with a skin preset with double bosses and a double-laser-beam double-side synchronous welding process adapted to the welding piece structure, aiming at the problems in the existing double-laser-beam double-side synchronous welding wire filling technology. The double-boss structure and the double-laser-beam bilateral synchronous welding process are matched with each other, the purposes of improving the weld joint forming and improving the performance of a welding joint are achieved, and the problems of unstable wire filling, poor weld joint forming, difficulty in controlling the wire filling angle and the like in the prior art are solved.

The invention is realized in such a way that a double-boss structure is preset on the skin of the T-shaped joint, and is characterized in that double bosses are processed on the skin and are positioned at the joint of a stringer and the skin.

Furthermore, the double bosses are positioned on two sides of the stringer, and the distance between the double bosses is 1.25% -2.5% larger than the thickness of the stringer.

Further, the height and the width of the double bosses are the same, and the height of the double bosses is 30% -37.5% of the thickness of the stringer.

The invention also discloses a double-laser-beam bilateral synchronous welding process adaptive to the skin preset double bosses, which comprises the following specific steps:

step 1, performing pre-welding treatment on the T-shaped structure with the skin pre-provided with the double bosses. Polishing the surface of the area where the skin is connected with the stringer by using an electric grinder, and removing a surface oxide film; wiping the skin and the stringer by using acetone and alcohol, removing impurities such as oil stains on the surface, and drying by using an oven; and packaging the dried and cooled skin and the stringer by using a preservative film to prevent secondary oxidation.

And 2, placing the stringer which is subjected to the pre-welding treatment between the skin double bosses, and fixing the stringer by using a special clamp.

Step 3, adjusting the position and the angle of the laser beam to enable the laser beams on the two sides of the stringer to be respectively focused on the edges of the outer sides of the double bosses, and ensuring that the bosses are completely melted in the synchronous welding process of the two sides of the double laser beams, thereby forming a combined molten pool; and adjusting the position of the protective gas nozzle to align the protective gas nozzle to the double bosses on the skin, so as to ensure that the welding line is always in the protective gas atmosphere in the double-laser-beam double-side synchronous welding process.

And 4, teaching by using a welding robot, checking a welding path, checking whether the center of a laser beam is always aligned with the edge on the outer side of the double boss and whether a shielding gas nozzle is always aligned with the double boss in the teaching process, and developing a double-laser-beam bilateral synchronous welding process on the premise of correct welding path.

The beneficial results of the invention and the prior art are as follows:

(1) by processing the double-boss structure with reasonable size on the skin, the fixing and clamping of the skin-stringer are facilitated on one hand, and the double-boss structure is used for replacing wire filling welding in laser welding on the other hand, so that the problems of unstable wire filling, unmatched wire filling speed and welding speed, difficulty in controlling wire filling angle and the like are facilitated to be solved;

(2) the double-laser-beam bilateral synchronous welding process adaptive to the skin double-boss structure is developed, on one hand, double-side forming of a welding joint is facilitated, the forming effect is ideal, and the mechanical property of a welding seam is improved to a certain extent; on the other hand, the welding speed is improved, and the production efficiency is greatly improved. Compared with a single-side welding double-side forming and laser filler wire welding process, the double-laser-beam double-side synchronous welding process with the skin preset with the double-boss structure can improve the performance of weld joint forming and welding joint, and improve the welding efficiency and the welding quality.

Drawings

FIG. 1 is a flow chart of a skin pre-installation double boss structure for a T-joint and a welding process thereof;

FIG. 2 is a schematic view of a weldment of a skin pre-fabricated double boss structure of the present invention, including a schematic view of the skin-stringer assembly;

FIG. 3 is a schematic diagram of a dual laser beam double-sided synchronous welding process compatible with a skin pre-set dual boss configuration;

FIG. 4 is a schematic view of a double boss welded by laser beam heating, melting and solidifying.

FIG. 5 is a macroscopic view of a local weld joint at the skin-stringer junction along the weld direction based on the dual-boss configuration of the skin and the dual-laser beam bilateral simultaneous welding process of the present invention;

FIG. 6 is a macro-topography of a skin-stringer T-joint perpendicular to the weld direction under an optical microscope.

Wherein, 1-covering, 2-covering preset double-boss structure, 3-stringer, 4-double laser beam, 5-protective gas nozzle, 6-welding line.

Detailed description of the preferred embodiments

The invention provides a weldment structure with a skin preset with double bosses and a double-laser-beam double-side synchronous welding method adapted to the weldment structure, and in order to make the purpose, the technical scheme and the expected effect of the invention more clear, the invention is further described by the attached drawings in detail and examples. It should be noted that the embodiments described herein are only for explaining the present invention and are not used for limiting the present invention.

The invention discloses a weldment structure with a skin preset with double bosses, as shown in figure 2, the double bosses 2 are positioned at two sides of a stringer, the interval between the double bosses is 4.1mm, the thickness of the stringer is 4mm, and a micro-gap formed by the skin and the stringer is favorable for assembling the skin and the stringer; the height and the width of the double bosses are the same and are 1.5mm, namely the thickness of the stringer is 37.5%, and on the premise of ensuring that the double bosses are fully melted, the welding seam achieves a good forming effect.

The invention also discloses a double-laser-beam bilateral synchronous welding process adaptive to the skin preset double-boss structure, which comprises the following specific steps:

as shown in fig. 2, the skin is preset with a double-boss structure, firstly, an electric grinder is used for grinding the surface of a local area where the skin 1 is connected with a stringer 3, and a surface oxide film is removed; wiping the skin and the stringer by using acetone and alcohol, removing impurities such as oil stains on the surface, and drying by using an oven; and packaging the dried and cooled skin and the stringer by using a preservative film to prevent secondary oxidation.

The stringer 3 is placed perpendicular to the skin 1 between the double bosses 2, where the spacing between the bosses is 4.1mm and the thickness of the stringer is 4 mm. Ensuring that the stringers and the skin are in complete contact and fixing on the workbench by using a special mounting fixture.

As shown in fig. 3, the position and angle of the laser beam 4 are adjusted to align the centers of the laser beams on both sides with the outer edges of the pre-set double bosses 2 on the skin 1, respectively. The welding power is 4300W, the welding angle is 30 degrees, the welding speed is 2.5m/min, the defocusing amount is 1mm, so that the boss 2 is completely melted by the laser beams in the double-laser-beam double-side synchronous welding process. And adjusting the position of the protective gas nozzle 5 to ensure that the protective gas nozzle 5 is aligned to the double bosses 2 on the skin 1, wherein the protective gas is argon, the flow is 15L/min, and the welding seam 6 is always in the protective gas atmosphere in the double-laser-beam double-side synchronous welding process. And checking the welding path by using a welding robot, and developing a double-laser-beam bilateral synchronous welding process on the premise of correct welding path. FIG. 4 is a schematic view of a double boss welded by laser beam heating, melting and solidifying.

After the double-laser-beam bilateral synchronous welding process is carried out, the welding seam 6 is obtained, as shown in fig. 5 and 6, the macroscopic morphology of the welding seam 6 is evaluated, and the macroscopic morphology comprises the flatness and continuity of the formed welding seam, the mechanical properties of a welding joint and the like.

The above description is only a basic process of the present invention, and it should be noted that, for those skilled in the art, several modifications can be made without departing from the principle of the present invention, and these modifications should also be regarded as the protection scope of the present invention.