CN111545905A

CN111545905A - Pulse laser preheated double-laser-beam bilateral synchronous welding system and method

Info

Publication number: CN111545905A
Application number: CN202010404930.9A
Authority: CN
Inventors: 占小红; 綦娜; 王磊磊; 陈帅
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2020-05-13
Filing date: 2020-05-13
Publication date: 2020-08-18

Abstract

The invention discloses a pulse laser preheated double-laser-beam bilateral synchronous welding system and method. The method comprises two pulse laser auxiliary devices and a double-laser-beam double-side synchronous welding device. The laser welding device is characterized in that spot welding and preheating are carried out by the auxiliary pulse laser, and the main laser head starts welding after preheating, so that the welding is carried out while preheating in the welding process. The method comprises the following steps: 1. before welding, acetone is used for cleaning a welding area, oil stains on the surface are removed, a stainless steel brush is used for polishing the surface, an oxidation film on the surface of the welding is removed, the weldment is ensured to be clean and dry, and then the weldment is correctly assembled. 2. And adjusting the positions and angles of the main laser head and the auxiliary laser head, and demonstrating the welding robot. 3. And starting to perform double-laser-beam bilateral synchronous welding, wherein the auxiliary laser head firstly performs spot welding on the weldment, then preheats the weldment, and the main laser head starts to weld after preheating for 5 seconds, so that the preheating and welding of the weldment are performed simultaneously.

Description

Pulse laser preheated double-laser-beam bilateral synchronous welding system and method

Technical Field

The invention belongs to the technical field of laser welding manufacturing, and particularly relates to a pulse laser preheating double-laser-beam bilateral synchronous welding system and method.

Background

The T-shaped structural joint of the skin stringer of the traditional aircraft panel is mostly connected by adopting a riveting method. The double-laser-beam double-side synchronous welding method has great advantages over the riveting method, and has gradually replaced the riveting method to become the main connecting method of the T-shaped structural joint of the skin-stringer of the aircraft panel. The welded structural member produced by the welding method can greatly reduce the structural weight, has high production efficiency and good air tightness, and can improve the quality of a welding seam. The aluminum alloy has excellent performance, small density, high specific strength and corrosion resistance, and is widely applied to structural members of airplanes.

The welding process for connecting the T-shaped structure of the skin stringer of the aircraft panel by the double-laser-beam double-side synchronous welding method is complex, the welded material is generally aluminum alloy, the thermal expansion coefficient is large, the elastic modulus is small, and the welded plate is large in size and thin in thickness. The above factors can cause the problems of cracks, air holes and defects in the welding process, reduce the assembly precision of products, cause the performance reduction of joints and reduce the quality of the products. The pulse laser assisted double-laser-beam bilateral synchronous welding method can reduce the generation of welding cracks, air holes and defects, improve the assembly precision of products, improve the performance of joints and improve the quality of the products.

The pulse laser is added for assisting in laser welding, continuous laser is focused on the surface of a workpiece, a keyhole is generated in welding, spot welding and preheating are carried out on a welding seam by the pulse laser, the cooling speed of a welding pool in a certain range can be controlled, welding of high-crack sensitive materials is facilitated, and the toughness of the welding seam is improved. The parallel arrangement of the laser beams in the system changes the flow mode of the liquid metal, is beneficial to preventing the defects of undercut, weld bead protrusion and the like, and improves the weld forming. In addition, the laser beams are coupled in three arrangement modes, so that the bridging capacity can be improved, and the quenching tendency of welding seams and the generation of pores can be reduced.

Disclosure of Invention

A pulse laser preheated double-laser-beam bilateral synchronous welding system and method are characterized in that: comprising two pulsed laser assist devices. The laser head and the pulse auxiliary device which enable the double laser beams to synchronously weld one side of the T-shaped structure on two sides are in a front-back relationship, namely, two laser heads are arranged on one side of the T-shaped structure, one laser head is mainly used for emitting continuous laser and located on the rear side of the auxiliary laser head, the other laser head is used for assisting and emitting pulse laser and located on the front side of the main laser head, the other laser head of the T-shaped structure is also distributed in the same manner, and two sides of the T-shaped structure are in. The auxiliary laser head performs spot welding and preheating, the main laser head starts welding after preheating for 5s, and the welding is performed while preheating, so that the crack sensitivity in the double-laser-beam double-side synchronous welding process of the skin-stringer T-shaped structure is reduced, the toughness of a welding line is improved, the hardenability tendency and the generation of air holes are reduced, and the formation of the welding line is improved.

Further, the skin-stringer T-shaped structural material synchronously welded on two sides of the double laser beams is made of aluminum alloy, the welding area is cleaned by acetone before welding, oil stains on the surface are removed, the surface is polished by a stainless steel brush, an oxidation film on the welding surface is removed, the weldment is ensured to be clean and dry, and then the weldment is correctly assembled.

Furthermore, the positions and angles of the main laser head and the auxiliary laser head are adjusted, and the welding robot is taught.

Furthermore, in the double-laser-beam double-side synchronous welding process, the auxiliary laser head firstly performs spot welding on the weldment, then preheats the weldment, and the main laser head starts welding after preheating for 5 seconds, so that the preheating and welding of the weldment are performed simultaneously.

Furthermore, in the double-laser-beam double-side synchronous welding process, the main laser head and the auxiliary laser head both use protective gas to prevent oxidation, the protective gas is He or Ar, the flow of the protective gas is 10-20L/min, the two laser heads are arranged in a single row mode, and the protective gas range is larger.

Further, the weld pool condition in the welding direction is: the continuous laser has higher energy density, is focused on the surface of a workpiece to generate a keyhole in a weldment, has lower energy density of pulse laser, and is only used as a preheating heat source before welding.

Further, the weld pool condition in the vertical welding direction is: the distance between two continuous laser beams is small, and the same keyhole is generated in the welding molten pool.

Furthermore, in the double-laser-beam double-side synchronous welding process, the main laser head and the auxiliary laser head simultaneously realize three laser beam arrangements in one welding process, namely a serial arrangement, a parallel arrangement and a cross arrangement, wherein the serial arrangement means that the double laser beams are arranged in front and at the back of one side of a welding seam, the parallel arrangement means that the double laser beams are symmetrically arranged at the two sides of the welding seam, and the cross arrangement means that the double laser beams are arranged in opposite angles at the two sides of the welding seam.

The invention has the beneficial effects that:

the invention provides a pulse-preheated double-laser-beam bilateral synchronous welding system and method, which can realize simultaneous preheating and welding in the double-laser-beam bilateral synchronous welding process by spot welding and preheating of an auxiliary laser head through the synergistic effect of a main laser head and the auxiliary laser head, control the cooling speed of a welding pool within a certain range, reduce the possibility of crack generation and simultaneously improve the toughness of a welding seam; the laser beam arrangement is the combination of three arrangement modes, thereby not only improving the bridging capacity, but also reducing the cooling speed of a molten pool, reducing the hardenability tendency and the air holes of the welding seam, improving the welding seam formation and obtaining the continuous and uniform welding seam.

Drawings

FIG. 1 is a schematic diagram of pulse preheating dual laser beam double-side synchronous welding;

FIG. 2 is a schematic view of weld puddle conditions in the weld direction;

FIG. 3 is a schematic view of the weld puddle perpendicular to the weld direction;

fig. 4 is a schematic diagram of a two-beam arrangement.

Wherein, 1 is auxiliary laser head, 2 is main laser head, 3 is covering, 4 is stringer, 5 is keyhole, 6 is continuous laser, 7 is pulse laser.

Detailed Description

The invention provides a pulse laser preheating double-laser-beam double-side synchronous welding system and a pulse laser preheating double-laser-beam double-side synchronous welding method, which are described in detail with reference to the attached drawings and examples in order to make the technical scheme of the invention more vivid and understandable. It should be noted that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The present invention will be described in detail below with reference to the accompanying drawings.

As shown in figure 1, the pulse laser preheating double-laser-beam bilateral synchronous welding system and the method thereof are characterized in that an auxiliary laser head is arranged in front of the welding motion direction of a main laser head, the auxiliary laser head performs spot welding and welding seam preheating in the welding process, and the main laser head starts welding after the auxiliary pulse laser preheats the welding seam for 5 s. And in the welding process, protective gas is introduced into the protective gas pipes of all the laser heads.

As shown in figure 2, the schematic view of the welding pool along the welding direction, the continuous laser is focused on the surface of the workpiece to generate a keyhole in the weldment, and the pulse laser is only used as a preheating heat source before welding.

As shown in figure 3, the welding pool is schematic in the vertical welding direction, the distance between two continuous lasers is small, the same keyhole is generated in the welding pool, the welding process is more stable, gas is easier to discharge, and the reduction of air holes and splashing is facilitated.

As shown in FIG. 4, the arrangement of laser beams is schematically shown, in the invention, three arrangements can be simultaneously realized, and the serial arrangement can reduce the cooling rate of a molten pool and reduce the hardenability tendency and the air holes of a welding seam; the parallel arrangement can increase the adaptability of the light beams to the gaps and improve the bridging capacity.

The foregoing are only preferred embodiments of the present invention. The invention has wide application, and it should be understood that many changes and modifications can be made by one skilled in the art without departing from the principle of the invention, and therefore, the changes and modifications can be made without departing from the invention.

Claims

1. A pulse laser preheated double-laser-beam bilateral synchronous welding system and a method are disclosed, and the system is characterized in that: including two pulse laser auxiliary device, wherein make the laser head and the pulse auxiliary device of two side synchronous welding T type structure one side of double laser beam be the anteroposterior relation, have two laser heads in one side of T type structure promptly, a laser head is main, sends continuous laser, is located supplementary laser head rear side, and another laser head is for assisting, sends pulse laser, is located main laser head front side, and the opposite side laser head of T type structure also distributes equally, and both sides are the symmetric relation.

2. The pulsed laser preheated double laser beam double-side synchronous welding system and method according to claim 1, the method steps comprising: the method comprises the following steps: cleaning a welding area by using acetone before welding, removing oil stains on the surface, polishing the surface by using a stainless steel brush, removing an oxide film on the surface of the welding, ensuring that a weldment is clean and dry, and then correctly assembling the weldment; step two: adjusting the positions and angles of the main laser head and the auxiliary laser head, and teaching the welding robot; step three: and starting to perform double-laser-beam bilateral synchronous welding, wherein the auxiliary laser head firstly performs spot welding on the weldment, then preheats the weldment, and the main laser head starts to weld after preheating for 5 seconds, so that the preheating and welding of the weldment are performed simultaneously.

3. The pulsed laser preheated double laser beam double-side synchronous welding system and method according to claim 1, wherein the weld puddle condition in the welding direction is: the continuous laser has higher energy density, is focused on the surface of a workpiece to generate a keyhole in a weldment, has lower energy density of pulse laser, and is only used as a preheating heat source before welding.

4. The pulsed laser preheated double-laser beam double-side synchronous welding system and method according to claim 1, wherein the weld puddle condition in the vertical welding direction is as follows: the distance between two continuous laser beams is small, and the key holes on two sides are coupled to form a continuous through key hole.

5. The pulse laser preheated double laser beam double-side synchronous welding system and method as claimed in claim 1, wherein the main laser head and the auxiliary laser head simultaneously achieve three laser beam arrangements in a welding process, which are a serial arrangement, a parallel arrangement and a cross arrangement, wherein the serial arrangement means that the double laser beams are arranged in front and back at one side of the weld, the parallel arrangement means that the double laser beams are arranged symmetrically at two sides of the weld, and the cross arrangement means that the double laser beams are arranged diagonally at two sides of the weld.