Laser welding device and method for infrared detector assembly

Abstract

The present invention provides a laser welding device and method for an infrared detector assembly, comprising: a device body having an internal cavity for placing a component to be welded; a first end of the device body being a first opening; a second end of the device body being a second opening; a stopper neck communicating between the internal cavity of the device body and the second opening; a cover plate for covering the first opening of the device body and securing the first end of the component to be welded; the stopper neck accommodating the second end of the component to be welded; and a vacuum pump connected to the second opening via a hose. The laser welding device of the present invention is simple to operate, effectively reduces production steps, and improves production efficiency. Laser welding in a vacuum environment avoids spatter during welding, contamination of the Dewar assembly during processing, and the formation of a large number of pores in the weld. This increases the weld penetration depth and reduces the heat-affected zone of the weld, thereby improving welding performance.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared detector assembly welding, and in particular to a laser welding device and method for an infrared detector assembly. Background Art

[0002] Refrigerated infrared detector components are widely used in many fields such as military, civilian, aerospace, etc. The environment faced in the application scenarios is more complex and changeable, so the test of environmental adaptability will be more stringent. The development of high-reliability refrigerated infrared detection is particularly important. Refrigerated infrared detectors designed to withstand overload, vibration, and shock have high welding quality requirements, making detector reliability particularly important. Highly sensitive and stable dewar components must be developed to withstand the extreme vibration, shock, and acceleration experienced during rocket launches. Overload, vibration, and shock resistance also place increasing demands on the structural strength of detector components, particularly weld strength and weld pool depth. High weld penetration requires high energy. Currently, infrared detector components are primarily welded using YAG lasers, which have relatively low power and are primarily used for small, thin parts, making weld penetration difficult to achieve. Direct fiber laser welding, however, can produce welds with greater weld penetration due to the high laser power density and rapid metal melting in the laser radiation zone. However, deep weld penetration with fiber lasers poses significant challenges, including spatter (a large amount of weld residue (excess material from the detector body)) and the formation of numerous pores in the weld. While reducing the welding speed can mitigate weld porosity, spatter is unavoidable. This also results in a larger weld depth and width, overheating the base metal, a larger heat-affected zone, and compromised airtightness and structural strength of the welded (brazed) parts, directly impacting the mechanical properties of the weld. Summary of the Invention

[0003] Based on the above problems, the present invention provides a laser welding device and method for an infrared detector assembly, aiming to solve technical problems in the prior art such as difficulty in ensuring welding penetration and contamination of the Dewar assembly during the processing of the pore control detector assembly.

[0004] A laser welding device for an infrared detector assembly, comprising:

[0005] The device body has an internal cavity for placing the components to be welded;

[0006] The first end of the device body is a first opening;

[0007] The second end of the device body is a second opening;

[0008] The internal cavity of the device body and the second opening are connected to a limiting neck;

[0009] a cover plate, used to cover the first opening of the device body and fix the first end of the assembly to be welded;

[0010] The limiting neck accommodates the second end of the component to be welded;

[0011] A vacuum pump is connected to the second opening via a hose.

[0012] Furthermore, the outer surface of the device body is coated with an anti-reflection film.

[0013] Furthermore, the thickness of the device body does not exceed 2.5 mm.

[0014] Furthermore, it also includes:

[0015] The inner surface of the cover plate is provided with a first positioning pin, and the first positioning pin cooperates with the first end of the assembly to be welded to limit the first end of the assembly to be welded;

[0016] The end surface of the limiting neck is provided with a second positioning pin, and the second positioning pin cooperates with the second end of the assembly to be welded to limit the second end of the assembly to be welded.

[0017] Furthermore, the inner surface of the cover plate has an annular protrusion to seal the opening of the second end of the assembly to be welded;

[0018] The first positioning pin is arranged on the outer periphery of the annular protrusion.

[0019] Furthermore, the device body is made of fused quartz or organic glass.

[0020] Furthermore, the device body is a hollow cylindrical structure.

[0021] A laser welding method for an infrared detector assembly, using the aforementioned laser welding device for an infrared detector assembly, comprises:

[0022] Step A1, placing the component to be welded inside the laser welding device;

[0023] Step A2, using a vacuum pump to evacuate the laser welding device;

[0024] Step A3, adjusting the laser focal length;

[0025] Step A4: Use laser to penetrate the device body to weld the to-be-welded position of the assembly to be welded.

[0026] Furthermore, in step A1, the distance between the device body and the position to be welded is 3 to 7 mm.

[0027] Furthermore, the cover plate has a first positioning pin;

[0028] In step A1, a first positioning pin is used to position the first end of the component to be welded, and a limiting neck is used to limit the second end of the component to be welded, thereby fixing the component to be welded inside the device body.

[0029] The beneficial effects of the present invention are: simple tooling operation, effective reduction of production processes, improved production efficiency, use of vacuum environment laser welding, avoidance of spatter during welding, avoidance of contamination of the Dewar assembly during processing and the appearance of a large number of pores in the weld, increased weld penetration, reduced weld heat-affected zone, and thus improved welding performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the overall structure of a laser welding device for an infrared detector assembly of the present invention;

[0031] Figure 2-3 This is a schematic structural diagram of a device body of a laser welding device for an infrared detector assembly according to the present invention;

[0032] Figure 4 This is a schematic structural diagram of the outer surface of a device body of a laser welding device for an infrared detector assembly of the present invention;

[0033] Figure 5 This is a schematic structural diagram of the inner surface of a device body of a laser welding device for an infrared detector assembly according to the present invention;

[0034] Figure 6 The present invention is a flowchart of the steps of a laser welding method for an infrared detector assembly. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0038] See also Figure 1 -,5. The present invention provides a laser welding device for an infrared detector assembly, comprising:

[0039] The device body (1) has an internal cavity (11) for placing the components to be welded;

[0040] The first end of the device body (1) is a first opening;

[0041] The second end of the device body (1) is a second opening;

[0042] The internal cavity (11) of the device body (1) and the second opening are connected to the limiting neck (3);

[0043] A cover plate (2) is used to cover the first opening of the device body (1) and fix the first end of the component to be welded;

[0044] The limiting neck (3) accommodates the second end of the component to be welded;

[0045] The vacuum pump (4) is connected to the second opening via a hose so as to communicate with the internal cavity (11).

[0046] Furthermore, the outer surface of the device body (1) is coated with an anti-reflection film, which is used to increase the transmittance of laser light.

[0047] Furthermore, the thickness of the device body (1) does not exceed 2.5 mm.

[0048] Furthermore, it also includes:

[0049] The inner surface of the cover plate (2) is provided with a first positioning pin (22), and the first positioning pin (22) cooperates with the first end of the assembly to be welded to limit the first end of the assembly to be welded;

[0050] The end surface of the limiting neck (3) is provided with a second positioning pin (31), and the second positioning pin cooperates with the second end of the assembly to be welded to limit the second end of the assembly to be welded.

[0051] Since the lead rings of the components to be welded are sintered by powder and their dimensional accuracy cannot be controlled, the positioning pins are mainly used to coaxially fix the lead rings.

[0052] The end surface of the limiting neck (3) has a second positioning pin (31), and the second end of the assembly to be welded is not only accommodated in the limiting neck (3), but is also further restricted in position by the second positioning pin (31). In this way, the first end of the assembly to be welded is fixed by the cover plate, and the second end is fixed by the limiting neck (3), thereby being fixed to the device body (1).

[0053] Furthermore, a quick-connect plug (32) is provided at the second opening of the limiting neck (3) for connecting a hose.

[0054] The quick-connect plug (32) allows the hose to be directly and quickly connected to the device body (1).

[0055] Furthermore, the quick-connect plug (32) is provided with a vacuum gauge.

[0056] When the vacuum pump (4) is evacuating the vacuum, the vacuum gauge measures the vacuum degree inside the device body (1).

[0057] Furthermore, the inner surface of the cover plate has an annular protrusion (21) for sealing the opening of the second end of the assembly to be welded;

[0058] The first positioning pin (22) is arranged on the outer periphery of the annular protrusion (21).

[0059] The annular protrusion (21) seals the opening of the second end of the assembly to be welded to protect the internal components of the assembly to be welded.

[0060] Preferably, there are four first positioning pins (22) evenly distributed on the periphery of the annular protrusion (21).

[0061] Furthermore, the cover plate (2) seals the first opening via a first sealing ring.

[0062] The first sealing ring is an elastic sealing ring.

[0063] Furthermore, a second sealing ring is provided between the annular protrusion (21) and the opening of the second end of the assembly to be welded.

[0064] The second sealing ring is a metal sealing ring or an elastic sealing ring.

[0065] Furthermore, the outer surface of the cover plate (2) is provided with a positioning scale line (23). The positioning scale line (23) is used to align with the lead ring of the assembly to be welded.

[0066] Because the cover plate is made of transparent quartz glass, the positioning scale line (23) is further used to center the lead ring position during assembly, eliminating the need for spot welding and tooling disassembly testing, thereby avoiding tooling wear caused by frequent tooling disassembly.

[0067] Furthermore, the positioning scale line (23) is in the shape of a cross.

[0068] Furthermore, the outer surface of the cover is provided with fixing screws (24) for fixing to the device body (1).

[0069] Furthermore, the assembly to be welded is a Dewar assembly of an infrared detector.

[0070] The first end base of the Dewar assembly has a cold finger support rod groove position, and the first positioning pin (21) and the groove position realize the positioning between the Dewar assembly and the cover plate, ensuring the welding coaxiality and avoiding the cold finger support rod assembly imbalance after welding.

[0071] Furthermore, the device body is made of fused quartz or organic glass.

[0072] Furthermore, the device body (1) is a hollow cylindrical structure, and its internal cavity (11) is cylindrical.

[0073] See also Figure 6The present invention also provides a laser welding method for an infrared detector assembly, using the aforementioned laser welding device for an infrared detector assembly, comprising:

[0074] Step A1, placing the component to be welded inside the laser welding device;

[0075] Step A2, using a vacuum pump to evacuate the laser welding device;

[0076] Step A3, adjusting the laser focal length;

[0077] Step A4: Use laser to penetrate the device body to weld the to-be-welded position of the assembly to be welded.

[0078] Furthermore, in step A1, the distance between the device body and the position to be welded is 3 to 7 mm. The distance between the device body and the weld must be controlled within 3 to 7 mm.

[0079] Step A1 includes:

[0080] Accommodate the second end of the assembly to be welded in the limiting neck;

[0081] Fixing the first end of the assembly to be welded to the cover plate;

[0082] Secure the cover to the device body.

[0083] Step A1 also includes:

[0084] The second opening of the device body

[0085] Furthermore, the cover plate has a first positioning pin;

[0086] In step A1, a first positioning pin is used to position the first end of the component to be welded, and a limiting neck is used to limit the second end of the component to be welded, thereby fixing the component to be welded inside the device body.

[0087] Furthermore, the inner surface of the cover plate is provided with an annular protrusion;

[0088] In step A1, the annular protrusion on the inner surface of the cover plate seals the opening of the second end of the assembly to be welded.

[0089] In step A1, the device body, constructed of fused quartz or plexiglass, serves as a fixture to directly secure the component to be welded, such as the infrared detector's Dewar assembly. Laser brazing is then performed directly, effectively avoiding the need for spot welding prior to ring welding. A first locating pin is positioned on the cover plate to locate the end of the component to be welded, for example, by matching the cold finger support grooves on the Dewar assembly's end base to ensure assembly accuracy. Once the welded component is installed in the device body, assembly accuracy can be directly measured.

[0090] In step A2, the assembled components to be welded, such as the Dewar assembly, are evacuated using a vacuum pump until the vacuum in the device body reaches 10 -2 ~10 -3 Welding under vacuum can effectively reduce the heat dissipation rate, but the vacuum degree cannot be too high. When the vacuum degree is too high, the heat dissipation rate will be reduced and the heat affected zone will be seriously damaged. A vacuum gauge is installed on the device body to detect the vacuum degree of the device body.

[0091] In step A3, the laser welding device with the components to be welded is fixed, and then the focal length is adjusted to maintain the focal length at -3 to -10 mm;

[0092] When the device and method of the present invention are used for welding, the appearance after welding is not oxidized, and the depth-to-width ratio can reach 5:1, thereby effectively increasing the penetration depth and effectively controlling the heat-affected layer.

[0093] In traditional laser welding, the components to be welded are assembled using an aluminum fixture, then spot-welded, the fixture is removed, and the assembly accuracy is tested. Once qualified, welding proceeds. However, the present invention utilizes a transparent fused quartz or plexiglass assembly. The device is then placed directly under the projector for assembly and centering. The device is then evacuated (to a predetermined vacuum), the focus is adjusted (the thickness of the device directly affects the focus), and welding is then performed. Because the device is transparent, assembly accuracy can be directly observed.

[0094] The tooling of the present invention is simple to operate and effectively reduces the production process. The fiber laser welding efficiency is high (circle welding only takes 3 to 10 seconds), and no spot welding or shielding gas is required. It effectively avoids spatter and a large number of pores during the welding process, effectively improves the weld penetration depth, improves the aspect ratio, reduces the heat-affected zone of the weld, and improves the weld quality. Therefore, the infrared detector formed by the fiber laser welding of the present invention has high efficiency, low energy consumption, saves use cost, and has stable power output (stable weld penetration depth).

[0095] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser welding device for an infrared detector assembly, characterized in that: include: The device body has an internal cavity for placing the components to be welded; The first end of the device body is a first opening; The second end of the device body is a second opening; A limiting neck is connected between the internal cavity of the device body and the second opening; a cover plate, used to cover the first opening of the device body and fix the first end of the component to be welded; The limiting neck accommodates the second end of the component to be welded; a vacuum pump connected to the second opening via a hose; The inner surface of the cover plate has a first positioning pin, and the first positioning pin cooperates with the first end of the component to be welded to limit the first end of the component to be welded; The end surface of the limiting neck has a second positioning pin, and the second positioning pin cooperates with the second end of the component to be welded to limit the second end of the component to be welded; The inner surface of the cover plate has an annular protrusion to seal the opening of the second end of the assembly to be welded; The first positioning pin is arranged on the outer periphery of the annular protrusion.

2. A laser welding device for an infrared detector assembly as claimed in claim 1, characterized in that: The outer surface of the device body is coated with an anti-reflection film.

3. The laser welding device for an infrared detector assembly according to claim 1, wherein: The thickness of the device body does not exceed 2.5 mm.

4. The laser welding device for an infrared detector assembly according to claim 1, wherein: The device body is made of fused quartz or organic glass.

5. The laser welding device for an infrared detector assembly according to claim 1, wherein: The device body is a hollow columnar structure.

6. A laser welding method for an infrared detector assembly, characterized in that: A laser welding device using an infrared detector assembly according to any one of claims 1 to 5, comprising: Step A1, placing the component to be welded inside the laser welding device; Step A2, using a vacuum pump to evacuate the laser welding device; Step A3, adjusting the laser focal length; Step A4: using laser to penetrate the device body to weld the to-be-welded position of the to-be-welded component.

7. The laser welding method of an infrared detector assembly according to claim 6, characterized in that: In the step A1, the distance between the device body and the position to be welded is 3-7 mm.

8. The laser welding method of an infrared detector assembly according to claim 6, characterized in that: The cover plate is provided with a first positioning pin; In step A1, the first end of the component to be welded is positioned using the first positioning pin, and the second end of the component to be welded is limited using the limiting neck, thereby fixing the component to be welded inside the device body.

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