Vacuum laser welding apparatus and method

Abstract

This invention provides a vacuum laser welding apparatus and method. The apparatus includes a vacuum chamber, a worktable, a spatter shielding device, a laser welding head, a protective lens, a rotation drive mechanism, and a displacement mechanism. The laser welding head is located outside the vacuum chamber, and the laser beam emitted by it passes sequentially through a light-transmitting window at the top of the vacuum chamber, the protective lens, and a through-hole in the spatter shielding device before reaching the worktable. The method includes: clamping the workpiece on the worktable and planning the weld seam trajectory; evacuating the vacuum chamber to a vacuum state; driving the protective lens to rotate, causing the laser beam to move relative to the through-hole; performing welding; when the contamination of the protective lens reaches a threshold, the displacement mechanism drives the protective lens to move a preset distance along the displacement direction to continue welding. This invention, through the synergy of spatter shielding, lens rotation dispersion, and step-by-step displacement, significantly reduces the frequency of protective lens replacement, extends the continuous welding working time after one vacuum evacuation, and improves production reliability and efficiency.

Description

Technical Field

[0001] This invention relates to the field of vacuum laser welding technology, and more specifically, to a vacuum laser welding apparatus and method. Background Technology

[0002] As the demand for high-quality welding of difficult-to-weld materials, irregular structures, and thick-walled structures in the aerospace field increases, vacuum laser welding technology has gained widespread attention due to its many advantages.

[0003] The advantages of vacuum laser welding are mainly reflected in the following aspects: First, it can effectively suppress plasma plume and improve laser energy utilization. Under vacuum (10~1000Pa) conditions, plasma plume is significantly attenuated and almost disappears, and laser energy directly reaches the keyhole. The coupling efficiency between the laser and the material is significantly improved, the keyhole shape is more stable, and the molten pool flow is smoother. Second, the weld formation capability is greatly improved. Under the same laser power, the penetration depth can reach 2 to 3 times that of laser welding under atmospheric conditions; a larger depth-to-width ratio is achieved, and the weld sidewalls are nearly parallel, reducing the "nail head effect". Third, the defect suppression capability is stronger. The vacuum environment provides excellent degassing conditions for the molten pool, and hydrogen and metal vapors can easily escape; common chain pores and keyhole pores in aluminum alloys and stainless steel are fundamentally suppressed, making it easy to achieve low-porosity and pore-free welds, meeting high airtightness indicators such as helium inspection. At the same time, welding spatter is significantly reduced, keyhole fluctuations are weakened, and molten metal spatter is less; it reduces workpiece surface contamination, reduces subsequent grinding and cleaning processes, and can also effectively reduce the risk of foreign matter in aerospace products. It can also prevent high-temperature oxidation, simplify welding protection, and has significant engineering significance for the surface protection of welds with irregular shapes and materials that are sensitive to oxidation.

[0004] However, the keyhole of vacuum laser welding still emits metallic fumes and a small amount of spatter and other waste. When using high-power laser welding and multi-seam welding, these wastes can accumulate and contaminate the protective lens, affecting welding stability and even the safety of the vacuum pressure chamber. Conventional fixed, small-sized protective lenses are inadequate in dealing with these problems, requiring frequent replacements. Sometimes, the protective lens must be replaced after the machine is stopped and depressurized before the welds inside the chamber are completed. This not only affects production efficiency but also increases the difficulty of controlling the welding process and drives up production costs. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the purpose of this invention is to provide a vacuum laser welding apparatus and method.

[0006] The vacuum laser welding apparatus provided by the present invention includes a vacuum chamber, a worktable, a spatter shielding device, a laser welding head, a protective lens, a rotary drive mechanism, and a displacement mechanism. The worktable is disposed inside the vacuum chamber and is used to clamp workpieces. The displacement mechanism is installed in the vacuum chamber. One end of the rotary drive mechanism is installed on the displacement mechanism, and the other end of the rotary drive mechanism is installed on the protective lens. The rotary drive mechanism is used to drive the protective lens to rotate, and the displacement mechanism is used to drive the rotary drive mechanism and the protective lens to move along the displacement direction. The top of the vacuum chamber is provided with a light-transmitting window, and the splash shielding device is located inside the vacuum chamber and between the protective lens and the worktable. The splash shielding device is provided with a through hole corresponding to the light-transmitting window. The laser welding head is located outside the vacuum chamber. The laser beam emitted from the laser welding head passes through the light-transmitting window, the protective lens, and the through hole in sequence before reaching the worktable.

[0007] Preferably, the protective lens is a circular consumable glass and is coaxially arranged with the rotary drive mechanism; The radius R1 of the circular consumable glass satisfies R1=N·R2, where R2 is the radius of the light-transmitting window, and N≥10.

[0008] Preferably, the rotary drive mechanism includes a rotary shaft, one end of which is connected to the displacement mechanism, and the other end of which is connected to the protective lens.

[0009] Preferably, the displacement mechanism includes a stepping guide rail, which is mounted on the top of the vacuum chamber.

[0010] Preferably, the laser welding head is fixed relative to the vacuum chamber.

[0011] According to the vacuum laser welding method provided by the present invention, using any of the vacuum laser welding apparatuses described herein, the method includes the following steps: Step S1: Clamp the workpiece to be welded on the worktable and plan the entire weld seam trajectory; Step S2: Evacuate the vacuum chamber to a vacuum state; Step S3: Activate the rotary drive mechanism to drive the protective lens to rotate, so that the protective lens moves relative to the through hole; Step S4: Start the laser welding head and emit a laser beam. The laser beam passes through the light-transmitting window, the protective lens and the through hole in sequence and reaches the worktable to weld the workpiece. Step S5: When the contamination level of the protective lens reaches a preset threshold, the control displacement mechanism drives the rotation drive mechanism to move the protective lens a preset distance along the displacement direction, so that the laser beam passes through the uncontaminated area of ​​the protective lens and continues welding; Step S6: Repeat step S5 until all usable areas of the protective lens are contaminated, then replace the protective lens.

[0012] Preferably, in step S2, the pressure of the vacuum state is below 1000 Pa.

[0013] Preferably, in step S4, the relative linear velocity between the surface of the protective lens and the spot of the laser beam is V1; In step S5, after the protective lens moves a preset distance along the displacement direction, the relative linear velocity between the surface of the protective lens and the spot of the laser beam is V2, and V1=V2.

[0014] Preferably, in step S5, the displacement mechanism drives the rotary drive mechanism to move the protective lens a distance of 2 along the displacement direction. R3, where R3 is the radius of the through hole.

[0015] Preferably, in step S6, when replacing the protective lens, the splash shielding device is cleaned at the same time.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention sets up a spatter shielding device and arranges the welding head outside the vacuum chamber. The laser beam passes through the light-transmitting window, the protective lens, and the through hole on the spatter shielding device before reaching the workpiece. The spatter generated during the welding process is confined to the through hole area, which greatly reduces the area that needs to be protected, reduces the range of spatter contamination of the protective lens, and avoids direct contamination of the light-transmitting window by spatter, thereby improving the reliability and service life of the device.

[0017] 2. This invention drives the protective lens to rotate through a rotary drive mechanism, causing the laser beam to move along a circular trajectory on the surface of the protective lens. This guides the welding spatter into the annular areas of the protective lens, significantly increasing the usable area of ​​the protective lens in a single operation. This is equivalent to reducing the spatter density per unit area, thereby extending the continuous working time of the protective lens under single vacuum conditions.

[0018] 3. This invention drives the protective lens to move step by step along the displacement direction through a displacement mechanism. When the current annular area of ​​the protective lens is contaminated, it moves to the next annular area, realizing the full utilization of the annular areas from the inside to the outside, which greatly improves the overall utilization rate of the protective lens and reduces the cost of consumables.

[0019] 4. This invention significantly reduces the replacement frequency of the protective lens by combining the protection of the spatter shielding device, the rotation and dispersion of the protective lens, and the area switching of the step-shifting mechanism. It also significantly improves the protective lens's ability to withstand spatter during high-power welding, avoids the situation where the machine is forced to stop and depressurize to replace the protective lens before the weld is completed in the vacuum chamber due to contamination, and greatly extends the continuous welding working time after one vacuuming, thereby improving production reliability and efficiency. Attached Figure Description

[0020] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0021] The diagram shows: Detailed Implementation

[0022] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0023] This invention provides a vacuum laser welding apparatus, such as... Figure 1 As shown, the device includes a vacuum chamber 1, a worktable 2, a spatter shielding device 3, a laser welding head 4, a protective lens, a rotary drive mechanism, and a displacement mechanism. The worktable 2, located inside the vacuum chamber 1, is used to clamp the workpiece; the workpiece's position on the worktable 2 ensures the weld seam is reached. The core innovation of the entire device lies in the synergistic effect of the spatter shielding device, the rotational movement of the protective lens, and the stepping displacement, which confines welding spatter within a controllable range and evenly disperses it into a large annular area of ​​the protective lens.

[0024] A displacement mechanism is installed in the vacuum chamber 1. One end of the rotary drive mechanism is mounted on the displacement mechanism, and the other end is fitted with a protective lens. The rotary drive mechanism drives the protective lens to rotate around its own axis, and the displacement mechanism drives the rotary drive mechanism and the protective lens to move along the displacement direction. A light-transmitting window 11 is provided on the top of the vacuum chamber 1, which serves as the optical channel for the laser beam 41 to enter the interior of the vacuum chamber 1 from the atmospheric environment. A spatter shielding device 3 is located inside the vacuum chamber 1, between the protective lens and the worktable 2. The spatter shielding device 3 has a through hole 31 corresponding to the light-transmitting window 11. The spatter shielding device 3 restricts the spatter generated during welding to the area within the through hole 31, significantly reducing the area requiring protection and preventing spatter from directly contaminating the entire surface of the protective lens. A laser welding head 4 is located outside the vacuum chamber 1 and is fixed relative to the vacuum chamber 1. The laser beam 41 emitted by the laser welding head 4 passes sequentially through the light-transmitting window 11, the protective lens, and the through hole 31 to reach the worktable 2, where it welds the workpiece clamped on the worktable 2. Throughout the optical path, the laser welding head 4 and the light-transmitting window 11 are fixed in space, while only the protective lens moves relative to the fixed optical path under the drive of the rotation and displacement mechanisms.

[0025] In a preferred embodiment, the protective lens is a circular consumable glass 5, coaxially arranged with the rotary drive mechanism. The radius R1 of the circular consumable glass 5 satisfies R1=N·R2, where R2 is the radius of the light-transmitting window 11, and N≥10. In a specific embodiment, R2=25mm, R1=250mm (N=10). The radius R2 of the light-transmitting window 11 is equal to the radius R3 of the through hole 31, i.e., R2=R3=25mm. During welding, most of the spatter generated is intercepted by the spatter shielding device 3 after passing through the through hole 31, with only a small portion reaching the surface of the protective lens. Since the radius of the protective lens is much larger than the radius of the light-transmitting window (N≥10), the actual usable protective area is much larger than the area of ​​the through hole. This effectively guides the welding spatter into the annular areas of the large-diameter protective glass, significantly reducing the spatter density on the actual usable protective area and greatly improving the utilization rate of the large-diameter protective lens.

[0026] In a preferred embodiment, the rotary drive mechanism includes a rotary shaft 6, one end of which is connected to a displacement mechanism, and the other end of which is connected to a protective lens. The rotation of the rotary shaft 6 drives the protective lens to rotate uniformly around its own axis. The displacement mechanism includes a stepping guide rail 7, which is mounted on the top of the vacuum chamber 1 and can drive the rotary shaft 6 and the protective lens to move precisely a preset distance along the stepping direction.

[0027] The present invention also provides a vacuum laser welding method, which uses the above-mentioned vacuum laser welding apparatus and specifically includes the following steps: Step S1: Clamp the cleaned workpiece to be welded onto worktable 2 and plan the entire weld path. Based on the weld distribution of the workpiece, pre-plan the welding sequence and path parameters of all welds in the control system to ensure that the workpiece can be clamped in the vacuum chamber and all welds can be completed in one go.

[0028] Step S2: Evacuate vacuum chamber 1 to a vacuum state. In this embodiment, the internal pressure of vacuum chamber 1 is evacuated to 100 Pa. The vacuum environment can effectively suppress plasma plume, improve laser energy utilization, and at the same time facilitate molten pool degassing, reduce porosity defects, and ensure weld quality.

[0029] Step S3: Activate the rotary drive mechanism to drive the protective lens to rotate, causing relative motion between the protective lens and the through hole 31. The linear velocity of the laser beam 41 spot relative to the protective lens is V1. In this embodiment, the linear velocity V1 = 1 m / min. The rotation of the protective lens causes the point of action of the laser beam 41 on the surface of the protective lens to move continuously along a circular trajectory, dispersing welding spatter into a ring-shaped area of ​​the protective lens.

[0030] Step S4: The laser welding head 4 is activated, emitting a laser beam 41. The laser beam 41 passes sequentially through the light-transmitting window 11, the protective lens, and the through-hole 31 before reaching the worktable 2, where it welds the workpiece clamped on the worktable 2. Because the protective lens rotates continuously, the laser beam 41 moves along a circular trajectory on the surface of the protective lens, dispersing welding spatter into a ring-shaped area around the lens, preventing spatter from accumulating in a fixed position. Simultaneously, the long-focal-length laser welding head 4 is fixed; the workpiece reaches the weld seam trajectory through the displacement of the worktable 2. The rotation and stepping motion of the protective lens are independent of the welding head's movement, thus not affecting the stability of the welding process or the weld seam tracking accuracy.

[0031] Step S5: At regular intervals during welding operations, observe the contamination status of the protective lens. When the protective lens becomes contaminated to the point where welding is no longer suitable, control the displacement mechanism to drive the rotation drive mechanism and the protective lens to move a preset distance along the displacement direction, allowing the laser beam 41 to pass through the uncontaminated area of ​​the protective lens and continue welding. In one embodiment, the distance the protective lens moves along the displacement direction is 2·R3 = 50 mm (R3 is the radius of the through hole 31). After moving, the circular trajectory of the laser beam 41 on the surface of the protective lens falls into a new annular area, which has not yet been contaminated by spatter and can continue to be used for laser transmission welding. After moving along the displacement direction, the protective lens continues to rotate, so that the linear velocity of the laser beam 41 relative to the spatter shielding device 3 is V2. In this embodiment, V2 = 1 m / min, i.e., V2 = v1. Maintaining a consistent linear velocity ensures that the heat distribution and spatter adhesion characteristics on the surface of the protective lens remain consistent during welding, which is beneficial to the stability of welding quality.

[0032] Step S6: Repeat step S5 until all usable areas of the protective lens are contaminated, then stop the machine and replace it with a new protective lens. In a preferred embodiment, while replacing the protective lens, the spatter shielding device 3 is cleaned to remove spatter adhering to its surface, restoring its good shielding effect and ensuring protective performance for the next welding cycle.

[0033] This invention confines welding spatter within the area of ​​the through-hole 31 using the spatter shielding device 3, reducing the area of ​​welding spatter protection. Furthermore, the rotational movement of the protective lens guides the welding spatter into the concentric rings of the lens, significantly increasing the usable protection area and effectively reducing spatter density. Combined with the step-by-step adjustment of the displacement mechanism, it achieves full utilization of the concentric rings from the inside out, greatly improving the utilization rate of large-diameter protective lenses and reducing operating costs. The entire protective mechanism significantly reduces the replacement frequency of the protective lens, significantly improves its ability to withstand spatter during high-power welding, and significantly extends the continuous welding time after a vacuum extraction. It avoids situations where the weld is not completed in the vacuum chamber due to protective lens contamination, forcing a shutdown for pressure relief and replacement, thus improving production reliability and efficiency.

[0034] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0035] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A vacuum laser welding apparatus, characterized in that, It includes a vacuum chamber (1), a worktable (2), a spatter shielding device (3), a laser welding head (4), a protective lens, a rotary drive mechanism, and a displacement mechanism. The worktable (2) is located inside the vacuum chamber (1) and is used to clamp workpieces. The displacement mechanism is installed in the vacuum chamber (1), one end of the rotary drive mechanism is installed on the displacement mechanism, and the other end of the rotary drive mechanism is installed on the protective lens. The rotary drive mechanism is used to drive the protective lens to rotate, and the displacement mechanism is used to drive the rotary drive mechanism and the protective lens to move along the displacement direction. The top of the vacuum chamber (1) is provided with a light-transmitting window (11), and the splash shielding device (3) is located inside the vacuum chamber (1) and between the protective lens and the worktable (2). The splash shielding device (3) is provided with a through hole (31) corresponding to the light-transmitting window (11). The laser welding head (4) is located outside the vacuum chamber (1). The laser beam (41) emitted by the laser welding head (4) passes through the light-transmitting window (11), the protective lens and the through hole (31) in sequence and reaches the worktable (2).

2. The vacuum laser welding apparatus according to claim 1, characterized in that, The protective lens is a circular consumable glass (5) and is coaxially arranged with the rotary drive mechanism; The radius R1 of the circular consumable glass (5) satisfies R1=N·R2, where R2 is the radius of the light-transmitting window (11), and N≥10.

3. The vacuum laser welding apparatus according to claim 1, characterized in that, The rotary drive mechanism includes a rotary shaft (6), one end of which is connected to the displacement mechanism, and the other end of which is connected to the protective lens.

4. The vacuum laser welding apparatus according to claim 1, characterized in that, The displacement mechanism includes a stepping guide rail (7), which is mounted on the top of the vacuum chamber (1).

5. The vacuum laser welding apparatus according to claim 1, characterized in that, The laser welding head (4) is fixed relative to the vacuum chamber (1).

6. A vacuum laser welding method, characterized in that, The vacuum laser welding apparatus according to any one of claims 1-5 comprises the following steps: Step S1: Clamp the workpiece to be welded on the worktable (2) and plan the entire weld trajectory; Step S2: Evacuate the vacuum chamber (1) to a vacuum state; Step S3: Start the rotary drive mechanism to drive the protective lens to rotate, so that the protective lens moves relative to the through hole (31); Step S4: Start the laser welding head (4) and emit a laser beam (41). The laser beam (41) passes through the light-transmitting window (11), the protective lens and the through hole (31) in sequence and reaches the worktable (2) to weld the workpiece. Step S5: When the contamination level of the protective lens reaches a preset threshold, the control displacement mechanism drives the rotation drive mechanism and the protective lens to move a preset distance along the displacement direction, so that the laser beam (41) passes through the uncontaminated area of ​​the protective lens and continues welding; Step S6: Repeat step S5 until all usable areas of the protective lens are contaminated, then replace the protective lens.

7. The vacuum laser welding method according to claim 6, characterized in that, In step S2, the pressure of the vacuum state is below 1000 Pa.

8. The vacuum laser welding method according to claim 6, characterized in that, In step S4, the relative linear velocity between the surface of the protective lens and the spot of the laser beam (41) is V1; In step S5, after the protective lens moves a preset distance along the displacement direction, the relative linear velocity between the surface of the protective lens and the spot of the laser beam (41) is V2, and V1=V2.

9. The vacuum laser welding method according to claim 6, characterized in that, In step S5, the displacement mechanism drives the rotary drive mechanism and the protective lens to move a distance of 2 along the displacement direction. R3, where R3 is the radius of the through hole (31).

10. The vacuum laser welding method according to claim 6, characterized in that, In step S6, while replacing the protective lens, the splash shielding device (3) is cleaned at the same time.

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