JP7302771B1 - High quality vacuum laser welding method and system for thick dissimilar materials - Google Patents

Abstract

A method and system for vacuum oscillating laser welding of plate materials of unequal thickness for realizing primary forming of a weld bead with a large penetration depth and large penetration and improving welding efficiency. The present invention discloses a vacuum laser welding method and system in which a base layer plate and a cover layer plate are placed on an operating stage in a vacuum chamber to assemble and chuck the composite plate to be welded. , the air in the vacuum chamber is evacuated, the inert gas is introduced, the welding parameters are set according to the actual needs, and the traveling mechanism installed in the vacuum chamber makes the welding bead follow the relative movement trajectory of the spot. move the operating stage so that it is covered with the laser remelting in a vacuum environment to modify the surface of the weld bead, increase the penetration depth, improve the strength of the weld bead, and pass the inert gas after the welding is completed. Continue to introduce, keep the pressure unchanged within a certain time, open the chamber door after introducing air, complete the welding operation. [Selection drawing] Fig. 1

Description

The present invention belongs to the technical field of welding, and more particularly to a method and system for high quality vacuum laser welding of thick dissimilar materials.

Welding and then rolling thick dissimilar materials is a commonly used method for manufacturing thick composite plates, and is widely used in chemical tankers, pressure vessels, pipes and other fields. This connection method can make different materials exhibit their respective advantages, but the weld bead that welds such composite plates is generally deep and has a complicated structure, making it difficult to weld. It is difficult to guarantee its quality and efficiency. Therefore, how to improve the weld bead quality and welding efficiency of composite plates is a relatively complex system process.

Chinese patent CN105127566A discloses a full penetration welding method for thick carbon steel-stainless steel composite plates, which uses submerged arc welding to perform multi-layer multi-pass welding, thereby reducing such Solve quality problems such as cracks in the middle layer when welding thick plates, difficult to clean the root of the base layer, welded joints not fused and not strong, etc. The steel-stainless steel composite steel plate is realized, and the quality of the welded joint is excellent. Chinese patent CN112008194A discloses a welding process of composite steel plate, which uses manual arc multi-layer welding method for base material and processed double-sided U-groove, so that carburization phenomenon occurs in the base material of the coating layer. and meet the requirements of multi-layer intergranular corrosion to ensure the quality of the weld bead. However, both of the above two methods belong to multi-layer multi-pass welding and require beveling, so the welding efficiency is very low. Chinese patent CN11260916A discloses a composite steel plate and its explosion welding production method. and the production method is simple, practical, efficient and convenient. However, explosion welding has certain risks, requires special site requirements, is not suitable for connecting composite steels with complex structures, and is difficult to guarantee welding quality.

As a kind of high-energy beam, laser has strong penetrability, low heat input, small welding deformation, high welding speed, no groove processing, and high welding efficiency. , It can replace welding methods such as ordinary explosion welding, manual arc welding and submerged arc automatic welding, but in the field of large-thickness welding, the laser welding process is still very unstable, causing violent plume and The difficulty in achieving the ideal weld bead depth limits the widespread use of laser welding techniques because the metal vapor does not allow the laser energy to be stably and efficiently absorbed by the weld material.

In the field of large-thickness welding, the conventional laser welding technology is unstable and difficult to achieve the ideal weld bead depth. The method achieves deeper penetration depth by oscillating laser means under vacuum environment, increases the regularity of the weld bead, improves the stability of the full size weld bead, and improves the stability of the laser welding technology. Achieved a breakthrough in use for welding of thick dissimilar materials.

To achieve the above objectives, the present invention provides a high-quality vacuum laser welding method for thick dissimilar materials, which method comprises:
S1: Welding pretreatment of dissimilar materials in which the weld contact surfaces of the dissimilar materials to be welded are polished, pickled or laser-cleaned;
S2: The dissimilar materials are placed on the operation stage in the vacuum chamber and chucked, the size and shape of the output spot of the laser device are adjusted, the spot is aligned with the starting point of the weld bead, and the traveling mechanism connected to the operation stage is moved. dynamic adjustment of the chuck and the welding mechanism to ensure that the running trajectory of the spot covers the entire weld bead while realizing relative movement of the fixed trajectory of the spot and the composite plate by setting;
S3: After the vacuum chamber is evacuated until the weld penetration of the corresponding dissimilar materials reaches a specified degree of vacuum, at the same time, the vacuum chamber is filled with high-purity inert gas, and the movement of air intake and bleed in the chamber. a high-vacuum environment treatment that adjusts the target balance and obtains a vacuum environment of 1000 Pa or less;
S4: Determining the welding process parameters according to the actual weld bead shape, size and performance requirements, setting the corresponding laser processing parameters, the laser processing parameters include processing speed, laser power, defocus amount, spot shape , including the oscillation amplitude and oscillation frequency, where oscillation amplitude and low oscillation frequency increase the size of the keyhole opening to allow the laser to better reach the bottom of the keyhole without affecting the penetration depth. Determining welding process parameters to ensure contact;
S5: After the parameter setting operation is completed, start the vacuum laser remelting surface modification. Keep the pressure unchanged within a certain time, then close the protective gas intake valve, the pump group, the flapper valve, open the air intake valve until the atmospheric pressure, open the chamber door, and weld It includes the penetration and welding of high aspect ratio weld beads to complete high quality welding of thick composite plates in a vacuum environment.

Furthermore, the range of the specified degree of vacuum is 100-1000Pa.

Furthermore, the high-purity inert gas has a water content of 1000 ppm or less, a purity of 99.9% or more, and a flow rate of 10 L/min or less.

Furthermore, some of the process parameters of the laser are welding speed of 0.1 m/min to 1 m/min, welding power of 5 to 50 kW, defocus amount of -30 mm to 0 mm, and spot swing width of 0.1. ˜1 mm, and the oscillation frequency is configured to be 20-150 Hz.

The welding speed is 0.6 m/min, the laser power is 5 kW, the defocus amount is 0 mm, the spot shape is a figure 8 spot perpendicular to the welding direction, the swing width is 0.5 mm, and the swing frequency is 100 Hz.

Furthermore, after the redissolution is completed, the inert gas is continuously introduced to keep the pressure in the vacuum chamber 3 from changing, and the duration is 3 minutes or more.

According to another aspect of the present invention, there is further provided a high quality vacuum laser welding system for thick dissimilar materials, the system comprising:
A vacuuming mechanism for vacuuming and an inert gas introduction mechanism for introducing an inert gas;
A vacuum chamber for providing a high-vacuum welding environment, wherein an operation stage is provided in the vacuum chamber for sandwiching a thick dissimilar material to be welded, and the vacuum chamber is provided with the vacuum. An electronically controlled flapper valve connected to the mechanism for turning on or off the airflow in the vacuum line and a protective gas intake valve connected to the inert gas introduction mechanism for turning on or off the introduction of the inert gas. and an air intake valve for turning on or off the introduction of air into the vacuum chamber from the external environment;
a traveling mechanism for realizing motion of the thick dissimilar materials to be welded, the traveling mechanism being coupled to the operating stage and moving the operating stage to perform a plurality of types of driving motions; ,
A laser welding unit matching the weld bead of thick dissimilar materials to be welded, comprising a laser device, a laser welding head and a robot, wherein the robot controls the oscillation of the laser welding head and the traveling mechanism and a laser welding unit that outputs matched power by the laser device to achieve primary forming of a weld bead with high penetration into the thick dissimilar materials to be welded.

Furthermore, an air pressure sensor is provided within the vacuum chamber.

Furthermore, the welding parameters of the laser welding unit are such that the welding power is 5 to 50 kW, the defocus amount is -30 mm to 0 mm, the spot swing width is 0.1 to 1 mm, and the swing frequency is 20 to 150 Hz. Configured.

In general, the above technical solution envisioned by the present invention can obtain the following beneficial effects compared with the prior art.

1. The high-quality vacuum laser welding method for thick dissimilar materials of the present invention provides a vacuum environment of 1000 Pa or less, so that the penetration of the weld bead is double that in the normal pressure environment, and the same laser power It can achieve a deeper penetration depth under the conditions, achieve the primary forming of the weld bead with large penetration, greatly improve the welding efficiency, and the aspect ratio of the weld bead is higher, reaching 3:1. Compared to arc and conventional laser welding, it promotes the growth of equiaxed grains with a smaller heat input, improves the strength of the weld bead, and has a low welding speed, high laser power, and a certain range of depletion. Select the amount of focus to increase the penetration depth. By adding an oscillating laser means in a vacuum environment, breaking the constraint of the penetration ability of the conventional oscillating laser welding, the keyhole can be opened with a small oscillating width and low oscillating frequency without affecting the penetration depth. The size can be increased to make the laser contact the bottom of the keyhole better, achieving the effect of increasing penetration, and the oscillating laser also increases the regularity of the weld bead, making the full size Improve the stability of the weld bead and realize the breakthrough in the use of laser welding technology for welding thick dissimilar materials.

2. The high-quality vacuum laser welding method for thick dissimilar materials of the present invention reduces the oxygen content in the environment, suppresses the oxidation reaction of metal, and effectively prevents the generation of pores by welding in a vacuum environment. can be suppressed to In addition, the vacuum environment suppresses the plasma plume and metal splattering during the welding process, stably absorbs the laser energy into the composite steel plate, and increases the weldable depth.

3. The high-quality vacuum laser welding method for thick dissimilar materials of the present invention uses laser as a heat source to weld thick composite dissimilar materials. Energy field tuning can be achieved by adjusting various parameters, and the degree of freedom in processing complex structures is higher and more flexible, and the primary forming of large-thickness welding can be achieved. Select a different laser welding head according to the shape of the weld bead, set the laser defocus amount, oscillation method, spot shape, laser wavelength, etc., and adjust the laser power, welding speed and oscillation according to the weld bead depth. By adjusting the moving width, it can be applied to the welding forming of a plurality of different materials with different thicknesses and different structures. Higher efficiency, stronger controllability and higher weld quality than traditional arc welding. It is safer and more environmentally friendly than explosion welding and requires less space. It is less costly and more adaptable to complex structures than electron beam welding.

4. The high-quality vacuum laser welding method for thick dissimilar materials of the present invention guarantees the cleanliness of the overlapping surface of the base layer plate material and the coating layer plate material by pre-welding the composite plate material, and prevents surface stains, oxidation layers, etc. The probability of defects due to factors such as External equipment such as assembly jigs, vacuum chamber sizes, and traveling mechanisms can be flexibly selected according to specific conditions such as the size of the workpiece to be processed, the structure of the workpiece to be processed, and the machining trajectory. It can realize high-quality welding forming of dissimilar materials with structure and thickness.

1 is a flow schematic diagram of a high-quality vacuum laser welding method for thick dissimilar materials in an embodiment of the present invention; FIG. 1 is a structural schematic diagram of a thick dissimilar material high-quality vacuum laser welding system according to an embodiment of the present invention; FIG. FIG. 4 is a cross-sectional comparison diagram of laser welding in a vacuum environment and a normal pressure environment in an embodiment of the present invention; FIG. 4 is a metal phase diagram of a surface weld bead of a composite steel plate vacuum laser welded in an example of the present invention. FIG. 3 is a metal phase diagram of a cross section of a weld bead of a composite steel plate vacuum laser welded in an example of the present invention. FIG. 4 is a metal phase diagram of a longitudinal section of a weld bead of a composite steel plate vacuum laser welded in an example of the present invention.

Explanation of Symbols In all the drawings, the same symbols indicate the same technical features, specifically as follows. 1 - base layer plate, 2 - cover layer plate, 3 - vacuum chamber, 4 - operating stage, 5 - laser welding head, 6 - weld bead.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer and clearer, the present invention will now be further described in detail with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are for the purpose of illustrating the invention only and are not intended to limit the invention. Moreover, the technical features according to the embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

As shown in FIG. 1, the present invention provides a high-quality vacuum laser welding method for thick dissimilar materials, which combines laser and vacuum environment to improve the welding efficiency and quality of thick composite plates. , with the diversification of laser light source adjustment means and other features, it is possible to adjust and control the effects of welding bead joint shaping and its internal crystal structure distribution to achieve high-quality joints of thick composite materials with complex structures. , the method is
S1: Welding pretreatment of dissimilar materials in which the weld contact surfaces of the dissimilar materials to be welded are polished, pickled or laser-cleaned;
S2: The dissimilar material is placed on the operation stage 4 in the vacuum chamber 3 and chucked, the size and shape of the output spot of the laser device is adjusted, the spot is aligned with the starting point of the weld bead 6, and the operation stage 4 is connected. dynamic adjustment of the chuck and the welding mechanism to ensure that the traveling trajectory of the spot covers the entire area of the weld bead 6 while realizing the relative movement of the fixed trajectory of the spot and the composite plate by setting the traveling mechanism;
S3: After evacuating the vacuum chamber 3 until the welding penetration of the corresponding dissimilar materials reaches a specified degree of vacuum, at the same time, the vacuum chamber 3 is filled with a high-purity inert gas, and the inside of the chamber is sucked. , a high-vacuum environment treatment that adjusts the dynamic balance of bleed air and obtains a vacuum environment of 1000 Pa or less;
S4: Determining welding process parameters according to the shape, size and performance requirements of the actual weld bead 6, setting corresponding laser processing parameters, wherein the laser processing parameters include processing speed, laser power, defocus amount, Including spot shape, wobble width and wobble frequency, wobble width and low wobble frequency allow the laser to better penetrate the keyhole by increasing the size of the keyhole opening without affecting the penetration depth. Determining welding process parameters that ensure contact with the bottom;
S5: After the parameter setting operation is completed, start the vacuum laser remelting surface modification, after the remelting is completed, in order to prevent the rapid reaction of the surface of the high temperature welding bead 6 and the air, the vacuum chamber Keep the pressure in 3 unchanged for a certain period of time, then close the protective gas intake valve, pump group, flapper valve, open the air intake valve until the pressure reaches atmospheric pressure, and open the chamber door. , retrieving the welded composite plate material and welding the penetration and high aspect ratio weld bead to complete a high quality weld of the thick composite plate material in a vacuum environment.

In step S1, the dissimilar materials include the base layer plate 1 and the cover layer plate 2, and during processing, the surface of the base layer plate 1 and the cover layer plate 2 to be welded will not have oil film, dirt, oxidation, etc. on the surface of the laser welding. Remove interfering impurities to avoid affecting the welding effect by reducing the absorption effect for the laser energy in the welding area.

In step S2, not only flat plates but also relatively complex structures such as rectangular parallelepipeds, cylinders, thickness changes, etc. are matched, and both are chucked and fixed by corresponding jigs provided on the operation stage 4. , the following welding operations may be performed: The traveling mechanism connected to the operation stage 4 is adaptable to a plurality of types of processing methods, and performs driving operations including three-dimensional cooperative linear displacement, rotation, reversal, etc. The relative movement of the motion trajectory and the laser spot can be realized, and the welding bead 6 can be covered by the relative motion trajectory of the spot from the starting point to the end point. In step S3, the size and type of the vacuum chamber 3 can be adjusted according to actual needs, and the designated vacuum degree should be 100-1000Pa, preferably 300-800Pa. Yes, preferably, the specified degree of vacuum is in the range of 500-700Pa. The dry high-purity inert gas should have a moisture content of 1000 ppm or less, a purity of 99.9% or more, and a flow rate of 10 L/min or less.

In step S4, some of the process parameters of the laser are configured as follows.
The welding speed is 0.1 m/min to 1 m/min, preferably the welding speed is 0.3 m/min to 0.8 m/min, preferably the welding speed is 0.5 m/min to 0.7 m/min and
The welding power is 5-50 kW, preferably the welding power is 5-30 kW, preferably the welding power is 5-20 kW, preferably the welding power is 5-10 kW,
The defocus amount is -30 mm to 0 mm, preferably the defocus amount is -20 mm to 0 mm, preferably the defocus amount is -10 mm to 0 mm, preferably the defocus amount is -5 mm to -0 mm. ,
The spot swing width is 0.1 to 1 mm, preferably the spot swing width is 0.3 to 0.8 mm, preferably the spot swing width is 0.3 to 0.5 mm,
The oscillation frequency is 20 to 150 Hz, preferably the oscillation frequency is 40 to 130 Hz, preferably the oscillation frequency is 60 to 120 Hz, preferably the oscillation frequency is 80 to 110 Hz,
Other parameters are independently selectable depending on the capabilities of the laser welding head and the requirements of the weld bead.

In step S5, in order to avoid a decrease in welding strength due to air oxidation of the surface of the high-temperature weld bead 6, inert gas is continuously introduced into the vacuum chamber 3 to keep the pressure unchanged. The duration for which is not changed is 3 min or longer.

In the embodiment of the present invention, by providing a vacuum environment of 1000 Pa or less, the weld bead penetration is doubled compared to the weld bead penetration in a normal pressure environment, resulting in a greater penetration depth under limited laser power conditions. The laser welding mechanism controls the laser welding head with high precision by a robot to achieve the primary forming of a weld bead with a large penetration and greatly improves the welding efficiency. The oscillation in the direction perpendicular to the movement direction of the dissimilar materials can be realized, and the oscillation width can be adaptively adjusted according to the types of dissimilar materials and the thickness of the plate, so that the welding bead can be welded. Wider width, suitable for high vacuum environment, higher weld bead aspect ratio, can reach 3:1, less heat input than arc and ordinary laser welding Promote growth and improve weld bead strength. In addition, the movement of the traveling mechanism and the vacuum laser welding mechanism of the present invention is synchronously controlled by the control system, especially for different types of dissimilar materials and different thickness materials, the rotational speed is determined by computational analysis, and different The means of matching the value of the laser oscillation amplitude and applying the oscillation laser in a vacuum environment breaks the constraint of the penetration ability of the traditional oscillation laser welding, and the small oscillation amplitude and low oscillation frequency reduce the penetration depth. The size of the keyhole opening can be increased to allow the laser to better contact the bottom of the keyhole without affecting the , achieving the effect of increasing penetration.

As shown in FIG. 2, according to one aspect of the present invention, a thick dissimilar materials high quality vacuum laser welding system is further provided for implementing and formulating a high quality vacuum laser welding method for thick dissimilar materials. The system includes a vacuum chamber 3 and a laser welding unit, the vacuum chamber 3 is provided with a chamber door for loading and unloading the composite plate, an operation table is provided in the vacuum chamber 3, and the operation table is A jig is provided for clamping the base layer plate material 1 and the covering layer plate material 2 welded to the base layer plate material 1, and the operation platform is connected to a traveling mechanism, and is moved by the traveling mechanism so as to perform a plurality of types of operation operations. The vacuum chamber 3 is further provided with an air intake valve, an electronically controlled flapper valve, a protective gas intake valve and an air pressure sensor, said air valve being used to turn on or off the introduction of air into the vacuum chamber 3 from the external environment. The electronically controlled flapper valve is used to turn on or off the airflow in the vacuum line, and the vacuum mechanism can draw out the vacuum chamber 3 to a vacuum state by the electronically controlled flapper valve, and the protective gas intake The valve can be used to introduce inert gas, under the control of the control system the inert gas introduction mechanism introduces the inert gas at a flow rate set in the vacuum chamber 3 by the protective gas inlet valve, and the pressure sensor detects the internal pressure of the vacuum chamber 3 to control the vacuum mechanism and vacuum until the pressure value of the vacuum chamber 3 is within the required range, while the inert gas is introduced by the protective gas intake valve. , intake, and bleed air in the vacuum chamber 3. Said laser equipment unit includes laser equipment, laser welding head 5 and robot, laser equipment can choose different laser equipment according to actual needs, including fiber laser, semiconductor laser, _CO2 and other types, laser equipment welding The head 5 is provided on a robot, and the robot adjusts the welding angle and posture to weld the composite material, and the laser device welding head may be provided inside or outside the vacuum chamber 3 as required. , single laser head, oscillating laser head, pulse laser head and other types may be selected. By combining the robot and the laser device welding head, the laser welding head 5 can adjust the spot shape and size of the emitted laser beam while matching the welding bead 6, and combine with the vacuum environment and inert gas. , overcome the high reflectivity of materials such as copper, aluminum, etc., thereby forming a stable state with a wide processing window, can effectively suppress the metal vapor generated during welding, and reduce the plasma plume phenomenon contributes to controlling the occurrence of slag scattering. During welding, by setting the oscillation width and frequency of the laser beam, the robot can change the welding width and penetration by oscillating the welding head 5 of the laser device. The shape of the weld bead is rectangular from that of a traditional nail tip, creating a large weld contact area, reducing resistance in the weld joint and providing good mechanical connection performance. Conventional laser welding requires high-precision jigs, but by combining the welding head of a laser device with a robot to perform oscillating welding, chuck requirements for the materials to be welded are greatly reduced. , the allowable weld bead clearance and deviation is two to three times the typical laser welding requirements.

Example 1
In the specific embodiment 1 of the present invention, the thickness of the dissimilar materials prepared is 20 mm for carbon steel and 60 mm for stainless steel, the required weld bead depth is 10 mm or more, and the welding method is as follows. be.
S1: Welding pretreatment of dissimilar materials: The surface of the area to be welded between the base layer plate material (carbon steel) 1 and the coating layer steel plate (stainless steel) 2 is laser-cleaned to remove surface oil stains, oxide layers and rust. ,
S2: dynamic adjustment of the chuck and welding mechanism: dissimilar materials are placed on the operation stage 4 in the vacuum chamber 3 and chucked, the size and shape of the output spot of the laser device are adjusted, and the spot is the starting point of the weld bead 6; , by setting the traveling mechanism connected to the operation stage 4, while realizing relative movement of the fixed trajectory of the spot and the composite plate material, ensuring that the traveling trajectory of the spot covers the entire area of the weld bead 6,
S3: High-vacuum environment treatment: After the vacuum chamber 3 is evacuated until the welding penetration of the corresponding dissimilar materials reaches a specified vacuum, at the same time, the vacuum chamber 3 is filled with a high-purity inert gas, Adjust the dynamic balance of intake air and bleed air in the chamber to obtain a vacuum environment of 1000 Pa,
S4: Determining welding process parameters: according to the actual shape, size and performance requirements of the weld bead 6, set the corresponding laser processing parameters, welding speed 0.6 m/min, laser power 5 kW, defocus amount 0 mm, the spot shape is a figure-8 spot that is perpendicular to the welding direction, the oscillation width is 0.5 mm, the oscillation frequency is 100 Hz, and the size of the keyhole opening is increased without affecting the penetration depth. to ensure better contact of the laser with the bottom of the keyhole,
S5: Welding a weld bead with a large penetration and aspect ratio: After the parameter setting operation is completed, the vacuum laser remelting surface modification is started, and after the remelting is completed, the surface of the high temperature weld bead 6 and the air In order to prevent a rapid reaction, the pressure in the vacuum chamber 3 is kept unchanged within a certain period of time, after which the protective gas intake valve, the pump group, and the flapper valve are closed, and the air pressure reaches atmospheric pressure. Open the intake valve, open the chamber door, take out the welded composite plate, and complete the high-quality welding of the thick composite plate in the vacuum environment.

Example 2
In the specific embodiment 2 of the present invention, the thickness of the dissimilar materials prepared is 60 mm for carbon steel and 160 mm for stainless steel, and the required weld bead depth is 50 mm, and the welding method is as follows.
S1: Welding pretreatment of dissimilar materials: The surface of the area to be welded between the base layer plate material (carbon steel) 1 and the coating layer steel plate (stainless steel) 2 is laser-cleaned to remove surface oil stains, oxide layers and rust. ,
S2: dynamic adjustment of the chuck and welding mechanism: dissimilar materials are placed on the operation stage 4 in the vacuum chamber 3 and chucked, the size and shape of the output spot of the laser device are adjusted, and the spot is the starting point of the weld bead 6; , by setting the traveling mechanism connected to the operation stage 4, while realizing relative movement of the fixed trajectory of the spot and the composite plate material, ensuring that the traveling trajectory of the spot covers the entire area of the weld bead 6,
S3: High-vacuum environment treatment: After the vacuum chamber 3 is evacuated until the welding penetration of the corresponding dissimilar materials reaches the specified vacuum, at the same time, the vacuum chamber 3 is filled with a high-purity inert gas, Adjust the dynamic balance of intake air and bleed air in the chamber to obtain a vacuum environment of 100 Pa,
S4: Determining welding process parameters: according to the actual shape, size and performance requirements of the weld bead 6, set the corresponding laser processing parameters, welding speed 0.1 m/min, laser power 25 kW, defocus amount is -20 mm, the spot shape is a figure-8 spot that is perpendicular to the welding direction, the oscillation width is 1 mm, the oscillation frequency is 100 Hz, and the size of the keyhole opening is increased without affecting the penetration depth. Ensure that the laser is in better contact with the bottom of the keyhole,
S5: Welding of a weld bead with a large penetration and aspect ratio: After the parameter setting operation is completed, the vacuum laser remelting surface modification is started, and after the remelting is completed, the surface of the high temperature weld bead 6 and the air In order to prevent a rapid reaction, the pressure in the vacuum chamber 3 is kept unchanged within a certain period of time, after which the protective gas intake valve, the pump group, and the flapper valve are closed, and the air pressure reaches atmospheric pressure. Open the intake valve, open the chamber door, take out the welded composite plate, and complete the high-quality welding of the thick composite plate in the vacuum environment.

Example 3
In the specific embodiment 3 of the present invention, the thickness of the dissimilar materials prepared is 30 mm for carbon steel and 100 mm for stainless steel, the required weld bead depth is 30 mm, and the welding method is as follows.
S1: Welding pretreatment of dissimilar materials: The surface of the area to be welded between the base layer plate material (carbon steel) 1 and the coating layer steel plate (stainless steel) 2 is laser-cleaned to remove surface oil stains, oxide layers and rust. ,
S2: dynamic adjustment of the chuck and welding mechanism: dissimilar materials are placed on the operation stage 4 in the vacuum chamber 3 and chucked, the size and shape of the output spot of the laser device are adjusted, and the spot is the starting point of the weld bead 6; , by setting the traveling mechanism connected to the operation stage 4, while realizing relative movement of the fixed trajectory of the spot and the composite plate material, ensuring that the traveling trajectory of the spot covers the entire area of the weld bead 6,
S3: High-vacuum environment treatment: After the vacuum chamber 3 is evacuated until the welding penetration of the corresponding dissimilar materials reaches the specified vacuum, at the same time, the vacuum chamber 3 is filled with a high-purity inert gas, Adjust the dynamic balance of intake air and bleed air in the chamber to obtain a vacuum environment of 600 Pa,
S4: Determining welding process parameters: according to the actual shape, size and performance requirements of the weld bead 6, set the corresponding laser processing parameters, welding speed 0.3 m/min, laser power 15 kW, defocus amount is -15 mm, the spot shape is an eight-shaped spot that is perpendicular to the welding direction, the oscillation width is 0.6 mm, the oscillation frequency is 80 Hz, and the size of the keyhole opening is increased without affecting the penetration depth. to ensure better contact of the laser with the bottom of the keyhole,
S5: Welding of a weld bead with a large penetration and aspect ratio: After the parameter setting operation is completed, the vacuum laser remelting surface modification is started, and after the remelting is completed, the surface of the high temperature weld bead 6 and the air In order to prevent a rapid reaction, the pressure in the vacuum chamber 3 is kept unchanged within a certain period of time, after which the protective gas intake valve, the pump group, and the flapper valve are closed, and the air pressure reaches atmospheric pressure. Open the intake valve, open the chamber door, take out the welded composite plate, and complete the high-quality welding of the thick composite plate in the vacuum environment.

Example 4
In specific embodiment 4 of the present invention, the thickness of the dissimilar materials prepared is 40mm for carbon steel and 140mm for stainless steel, and the required weld bead depth is 20mm, and the welding method is as follows.
S1: Welding pretreatment of dissimilar materials: The surface of the area to be welded between the base layer plate material (carbon steel) 1 and the coating layer steel plate (stainless steel) 2 is laser-cleaned to remove surface oil stains, oxide layers and rust. ,
S2: dynamic adjustment of the chuck and welding mechanism: dissimilar materials are placed on the operation stage 4 in the vacuum chamber 3 and chucked, the size and shape of the output spot of the laser device are adjusted, and the spot is the starting point of the weld bead 6; , by setting the traveling mechanism connected to the operation stage 4, while realizing relative movement of the fixed trajectory of the spot and the composite plate material, ensuring that the traveling trajectory of the spot covers the entire area of the weld bead 6,
S3: High-vacuum environment treatment: After the vacuum chamber 3 is evacuated until the welding penetration of the corresponding dissimilar materials reaches the specified vacuum, at the same time, the vacuum chamber 3 is filled with a high-purity inert gas, Adjust the dynamic balance of intake air and bleed air in the chamber to obtain a vacuum environment of 1000 Pa,
S4: Determining welding process parameters: according to the actual shape, size and performance requirements of the weld bead 6, set the corresponding laser processing parameters, welding speed 0.6m/min, laser power 10kW, defocus amount -8 mm, the spot shape is a figure-8 spot that is perpendicular to the welding direction, the oscillation width is 0.3 mm, the oscillation frequency is 100 Hz, and the size of the keyhole opening is increased without affecting the penetration depth. to ensure better contact of the laser with the bottom of the keyhole,
S5: Welding of weld beads with large penetration and aspect ratio: After the parameter setting operation is completed, vacuum laser remelting surface modification is started. In order to prevent an undesired reaction, the pressure inside the vacuum chamber 3 is kept unchanged for a certain period of time, and then the protective gas intake valve, pump group, and flapper valve are closed, and air is sucked until the pressure reaches atmospheric pressure. Open the valve, open the chamber door, remove the welded composite plate, and complete the high quality welding of the thick composite plate in the vacuum environment.

As shown in FIG. 3, under a vacuum environment, when the welding speed is 0.6 m/min, a welding bead depth of 12 mm can be achieved with a laser power of 6 kW. The depth is nearly three times that of normal pressure laser welding.

As shown in FIGS. 4 to 6, in the embodiment of the present invention, from the metallographic photographs of the surface, cross section and longitudinal section of the vacuum laser welded weld bead of the composite steel plate, the surface of the weld bead exhibits a metallic luster, and It was found to be continuously stable. The aspect ratio of the cross section of the weld bead by the oscillating laser reaches 3:1 or more, the average depth of the weld bead longitudinal section can reach 10 mm or more, and the weld bead is stable, continuous, and pore-free. rice field. This method realized high-quality primary welding forming of composite steel plates and greatly improved welding efficiency.

In the embodiment of the present invention, the pre-welding treatment of the composite plate ensured the cleanliness of the overlapping surface of the base layer plate and the cover layer plate, and reduced the probability of defects due to factors such as surface contamination and oxide layer. External equipment such as assembly jigs, vacuum chamber sizes, and traveling mechanisms can be flexibly selected according to specific conditions such as the size of the workpiece to be processed, the structure of the workpiece to be processed, and the machining trajectory. A high-quality connection of dissimilar materials with a thick structure can be realized.

In the embodiment of the present invention, welding in a vacuum environment can reduce the oxygen content in the environment, suppress the oxidation reaction of the metal, and effectively suppress the generation of pores. At the same time, the vacuum environment suppresses the generation of plasma plume and metal splatter during the welding process, allows the laser energy to be stably absorbed by the composite steel plate, and improves the weldable depth. A decrease in pressure in a vacuum environment leads to changes in the basic properties of materials, including a decrease in boiling point and an increase in recoil pressure. , and tends to cause the weld bead structure to grow equiaxed.

In the embodiment of the present invention, laser is used as a heat source to weld thick composite dissimilar materials. It can perform field tuning, has a higher degree of freedom in processing complex structures, is more flexible, can achieve the primary forming of large-thickness welding, and has different laser welding heads according to the shape requirements of the weld bead. can be selected to design the laser defocus amount, oscillation method, spot shape, laser wavelength, etc., and the laser power, welding speed, oscillation width, etc. can be adjusted according to the depth of the weld bead. The temperature field can be adjusted with an oscillating laser or otherwise to affect tissue structure and size as required by tissue structure or size. This allows for welded joints of specific size, shape and performance requirements. Higher efficiency, stronger controllability and higher weld quality than traditional arc welding. It is safer and more environmentally friendly than explosion welding and requires less space. It is less costly and more adaptable to complex structures than electron beam welding.

Those skilled in the art will appreciate that the above is merely a preferred embodiment of the present invention and is not intended to limit the present invention, and any modifications, equivalent substitutions and improvements, etc. made within the spirit and principle of the present invention. , should be included in the protection scope of the present invention.

Claims (9)

S1: Welding pretreatment of dissimilar materials in which the weld contact surfaces of the dissimilar materials to be welded are polished, pickled or laser-cleaned;
S2: The dissimilar material is placed on the operation stage (4) in the vacuum chamber (3) and chucked, the size and shape of the output spot of the laser device is adjusted, and the spot is positioned where the weld bead should be formed (6). By setting the traveling mechanism connected to the operation stage (4) in accordance with the starting point, the traveling trajectory of the spot ( 6) Adjustment of the chuck and welding mechanism to ensure that the entire area is covered,
S3: After the vacuum chamber (3) is evacuated until the expected welding depth of the corresponding dissimilar materials reaches the specified vacuum, at the same time, the vacuum chamber (3) is filled with high-purity inert gas. high-vacuum environment treatment for obtaining a vacuum environment of 1000 Pa or less by adjusting the dynamic balance of intake air and bleed air in the chamber;
S4: Determining welding process parameters, setting corresponding laser processing parameters according to the shape, size and performance needs of the weld bead to be formed , wherein the laser processing parameters include processing speed, laser power, defocus The amplitude, spot shape, wobble width and wobble frequency, wobble width and low wobble frequency allow the laser to be better keyed by increasing the size of the keyhole opening without affecting the penetration depth. Determining welding process parameters that ensure contact with the bottom of the hole;
S5: After the parameter setting operation is completed, start the vacuum laser welding , after the welding is completed, the surface of the high temperature welding bead (6) and the air inside the vacuum chamber (3) to prevent rapid reaction Keep the pressure unchanged within a certain time, then close the protective gas intake valve, the pump group, the flapper valve, open the air intake valve until the atmospheric pressure, open the chamber door, and weld removing the composite plate and welding the penetration and high aspect ratio weld bead to complete a high quality weld of the thick composite plate in a vacuum environment;
A high-quality vacuum laser welding method for thick dissimilar materials, characterized by: The high-quality vacuum laser welding method for thick dissimilar materials according to claim 1, characterized in that the range of the specified degree of vacuum is 100-1000Pa. 3. The thick gas according to claim 2, wherein the high-purity inert gas has a moisture content of 1000 ppm or less, a purity of 99.9% or more, and a flow rate of 10 L/min or less. High quality vacuum laser welding method for dissimilar materials. Some of the process parameters of the laser are a welding speed of 0.1 m/min to 1 m/min, a welding power of 5 to 50 kW, a defocus amount of -30 mm to 0 mm, and a spot swing width of 0.1 to 1 mm. , and the rocking frequency is 20-150 Hz. Some of the process parameters of the laser are: welding speed 0.6 m/min, laser power 5 kW, defocus amount 0 mm, spot shape 8-shaped spot perpendicular to the welding direction, swing width 0.5 mm. , the rocking frequency is configured to be 100 Hz. Any one of claims 1 to 4, characterized in that after welding is completed, the inert gas is continuously introduced to keep the pressure in the vacuum chamber (3) from changing, and the duration is 3 minutes or more. 3. A high-quality vacuum laser welding method for thick dissimilar materials according to claim 1. A thick dissimilar material high-quality vacuum laser welding system for realizing the high-quality vacuum laser welding method for thick dissimilar materials according to any one of claims 1 to 6,
A vacuum mechanism for vacuuming, an inert gas introduction mechanism for introducing inert gas,
A vacuum chamber (3) for providing a high-vacuum welding environment, wherein a manipulation stage (4) is provided in said vacuum chamber (3) for clamping a thick dissimilar material to be welded. , to the vacuum chamber (3), an electronically controlled flapper valve connected to the vacuum mechanism for turning on or off the air flow in the vacuum conduit, and an inert gas introduction mechanism for introducing inert gas. a vacuum chamber (3) provided with a protective gas inlet valve for turning on or off the and an air inlet valve for turning on or off the introduction of air into the vacuum chamber (3) from the external environment;
A traveling mechanism for realizing the movement of said thick dissimilar materials to be welded, said traveling mechanism being connected to said operating stage (4), said operating stage (4) being adapted to perform a plurality of kinds of driving motions. ), and a traveling mechanism that moves
A laser welding unit matching the weld bead of thick dissimilar materials to be welded, comprising a laser device, a laser welding head (5) and a robot, wherein the robot controls the oscillation of the laser welding head (5). and a laser welding unit that matches the traveling mechanism and outputs a matching power from the laser device to achieve primary forming of a weld bead with large penetration into thick dissimilar materials to be welded. A high quality vacuum laser welding system for thick dissimilar materials. Thick dissimilar materials high quality vacuum laser welding system according to claim 7, characterized in that an air pressure sensor is provided in the vacuum chamber (3). The welding parameters of the laser welding unit are configured such that the welding power is 5 to 50 kW, the defocus amount is -30 mm to 0 mm, the spot swing width is 0.1 to 1 mm, and the swing frequency is 20 to 150 Hz. 8. The thick dissimilar material high quality vacuum laser welding system of claim 7, wherein:

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