A device for welding a metal dewar feed insulator for an infrared detector

Abstract

A device for welding of infrared detector metal dewar feed insulator, comprising: base, positioning block, metal tube shell, anti-rotation fixing sheet, ceramic insulator, solder short circuit prevention fixing ring, solder ring and ceramic insulator position adjusting screw. The present application keeps concentric after assembling the screw holes of two position adjusting screws, ensures that the upper and lower ceramic insulators are not skewed on the same axis during welding, and realizes independent and accurate control of the height of the insulators on the upper and lower sides; by setting an independent cylindrical graphite solder short circuit prevention fixing ring, solder short circuit between the tube shell and the feed metal needle is prevented; the positioning block is processed with a slope to reduce the tool heat capacity, improve temperature uniformity and improve welding quality. The present application can be compatible with different models, different shapes and different sizes of products, while ensuring accurate positioning of the upper and lower insulators on the same axis and preventing solder short circuit, solving the problems of poor universality, long changeover period and high cost of existing special tooling.

Description

Technical Field

[0001] This invention relates to the fields of metal / ceramic packaging structures and electro-vacuum device manufacturing, and specifically provides a device for welding miniature metal Dewar feed insulators for infrared detectors. Background Technology

[0002] Dewar products for cooled infrared focal plane detector assemblies are vacuum-insulated devices, and the long-term maintenance of the vacuum in the Dewar is a crucial performance indicator for infrared focal plane detector assemblies. Typically, Dewar products achieve long-term vacuum maintenance by using an internal getter. The internal getter is connected to an external activation power source via a vacuum activation electrode, and is electrically fed through the vacuum activation electrode. When electricity is applied, a heating wire is heated to activate the getter.

[0003] Vacuum activation electrodes typically employ a structure consisting of a ceramic insulating ring and a feeding metal needle. In the fabrication of the vacuum activation electrode for Dewar products, both the inner and outer cylindrical surfaces of the ceramic insulating ring are coated with a nickel metallized layer. The inner cylindrical surface and the feeding metal needle are then brazed together to form a ceramic insulator. The outer ring is brazed to the Dewar metal shell, thereby achieving electrical insulation between the feeding metal needle and the Dewar shell.

[0004] Currently, specialized tooling is used for sealing ceramic insulators with metal tube shells. Each tooling can only be used for a single product and cannot be compatible with other models. After a product is modified, the tooling is easily scrapped and needs to be redesigned and manufactured. The preparation cycle for new tooling is long, and there are many types of tooling, which are inconvenient to store and maintain. This results in a long product preparation cycle, low efficiency, and high iteration costs. In some urgent research projects, the specialized tooling only arrives when the project is almost over. Therefore, there is an urgent need for a welding tooling that is versatile, flexible in adjustment, and reusable. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a device for welding metal Dewar feed insulators for infrared detectors. This device addresses the problem of time constraints and lack of time to prepare tooling fixtures for certain projects, ensuring timely delivery within the planned timeframe, reducing fixture costs, enhancing corporate reputation, and improving economic efficiency.

[0006] An apparatus for welding metal Dewar feed insulators for infrared detectors, the apparatus comprising: a base, a positioning block, a fixing screw, a metal tube shell, an anti-rotation fixing plate, a ceramic insulator, an anti-solder short-circuit fixing ring, a solder ring, and a ceramic insulator position adjustment screw.

[0007] The base is manufactured in an L-shape, with a first boss machined at the bottom for installing an anti-rotation fixing plate. A first threaded hole of M3 is machined at a suitable position on the center line of the boss for installing a ceramic insulator position adjustment screw. A concentric support platform with a diameter of about 6mm and a depth of 1mm is machined at both ends of the first threaded hole. The rear square bar is 60mm high, and a sliding groove is machined on the square bar for the positioning block to adjust the height. A square groove for fixing screws to move up and down is machined in the middle of the groove.

[0008] The positioning block is machined into an L shape, with an M3 threaded through hole machined at the top for installing the ceramic insulator position adjustment screw, and a second boss machined at the tail. The outline dimensions of the boss should correspond one-to-one with the groove dimensions of the base 1. An M3 second threaded hole with a depth of 5mm should also be machined at the top of the boss.

[0009] The metal tube shell is the product we need to weld. It is generally processed into a cylindrical shape, which is easy to process and has low manufacturing cost, and the stress is relatively uniform. One or two through holes are opened at appropriate positions in the metal tube shell for welding ceramic insulators.

[0010] The anti-rotation fixing plate is processed into a rectangle, and an anti-rotation fixing plate groove is processed at the bottom end. The outline size of the groove should correspond one-to-one with the size of the first boss of the base 1.

[0011] The anti-short circuit fixing ring is machined into a cylindrical shape, with an outer diameter slightly smaller than the inner diameter of the solder ring and an inner diameter slightly larger than the outer diameter of the ceramic insulator's feed metal needle.

[0012] The ceramic insulator position adjustment screw is used to position the ceramic insulator on the metal tube shell. It is machined into a cylindrical shape, with threads on the outside that match the first screw hole on the base boss and the second screw hole on the top of the positioning block. The inside is machined with a through hole with a diameter of 1.1mm, and one end is provided with a 1mm×1mm screwdriver groove.

[0013] Beneficial effects of the present invention

[0014] This invention ensures that the screw holes of the adjusting screws in two positions remain concentric after assembly, guaranteeing that the upper and lower ceramic insulators are on the same axis and do not skew during welding, thus achieving independent and precise control over the height of the upper and lower insulators. The invention features an independent cylindrical graphite anti-soldering ring, which is fitted onto the feed metal pin and positioned between the solder ring and the feed metal pin, forming a physical isolation to precisely prevent the solder from short-circuiting the tube shell and the feed metal pin, while also reducing the difficulty of solder assembly. The positioning block of this invention is machined with beveled surfaces to reduce the heat capacity of the tooling, improve temperature uniformity, and enhance welding quality; concentric bearings are machined at both ends of the threaded hole in the base to prevent the solder from contacting the base during welding, which could lead to the scrapping of the metal tube shell and the base. Overall, compared to traditional dedicated devices, this invention fully meets the requirements of scientific research and production, has a wide range of applicability, and can quickly adapt to the production of products of different models, shapes, and sizes, without requiring the redesign and machining of dedicated tooling for each new product. When product solutions are adjusted or upgraded, this universal device can continue to be used, greatly reducing the scrapping of tooling and the need for redesign and processing, shortening the production changeover preparation cycle, reducing R&D and manufacturing costs, improving the flexibility and response speed of the production line, and better adapting to the rapid iteration and flexible development needs of modern manufacturing. Attached Figure Description

[0015] Figure 1 These are schematic diagram (a) and cross-sectional view (b) of the device of the present invention.

[0016] Figure 2 is a schematic diagram of the base.

[0017] Figure 3 is a schematic diagram of the positioning block.

[0018] Figure 4 is a schematic diagram of the structure of a ceramic insulator.

[0019] Figure 5 is a schematic diagram of the anti-rotation fixing plate.

[0020] Figure 6(a) is a schematic diagram of the anti-solder short-circuit fixing ring, (b) is a schematic diagram of the solder ring, and (c) is a schematic diagram of the ceramic insulator position adjustment screw.

[0021] In the diagram, 1-base, 2-positioning block, 3-fixing screw, 4-metal tube shell, 5-anti-rotation fixing plate, 6-ceramic insulator, 7-anti-solder short-circuit fixing ring, 8-solder ring, 9-ceramic insulator position adjusting screw; 101-first boss, 102-first threaded through hole, 103-concentric support, 104-sliding groove, 105-square groove, 106-square strip; 201-second boss, 202-first inclined surface, 203-second threaded through hole, 204-second inclined surface, 205-threaded hole; 501-anti-rotation fixing plate groove; 601-ceramic ring, 602-feeding metal pin, 603-outer cylindrical surface of ceramic ring. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the embodiments.

[0023] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the field or according to the product manual. Accessories or instruments whose manufacturers are not specified are all conventional products that can be obtained by purchase.

[0024] The following is in conjunction with the appendix Figure 1 To be continued Figure 6 The invention is described in detail with an example of a general apparatus for welding metal Dewar feed insulators for infrared detectors, but is not limited thereto.

[0025] Example 1

[0026] A device for welding metal Dewar feed insulators for infrared detectors includes: a base 1, a positioning block 2, a fixing screw 3, a metal tube shell 4, an anti-rotation fixing plate 5, a ceramic insulator 6, an anti-solder short-circuit fixing ring 7, a solder ring 8, and a ceramic insulator position adjustment screw 9.

[0027] The base 1 is L-shaped to support the entire general welding device. It is made of stainless steel and has a 36mm square bottom with a thickness of 2mm. A first boss 101 with a length of 36mm, a width of 10mm, and a height of 3mm is machined in the middle of the bottom for installing the anti-rotation fixing plate 5. A first threaded hole 102 with an M3 diameter is machined 10mm from the back to the front on the center line of the boss for installing the ceramic insulator position adjustment screw 9. The function is to weld the ceramic insulator on the lower side of the metal tube shell 4 and to control the height of the ceramic insulator 6 on the lower side of the metal tube shell 4 by adjusting the ceramic insulator position adjustment screw 9. A concentric support 103 with a diameter of about 6mm and a depth of 1mm is machined at both ends of the first threaded hole 102 to prevent the brazing filler metal from contacting the base 1 and welding together, which would cause the metal tube shell 4 and the base 1 to be scrapped. The rear square strip 106 of the base 1 is 10mm long, 4mm wide, and 50mm high. A sliding groove 104, 5mm long and 2mm wide, is machined on the square strip so that the positioning block 2 can slide in the groove. Its function is to adjust the height of the positioning block 2 on the base 1, thereby achieving a rough adjustment of the height of the porcelain insulator 6 on the upper side of the metal tube shell 4. A square groove 105, 35mm long and 3mm wide, should also be machined in the middle of the groove. The positioning block 2 is firmly fixed in the required position of the base 1 by tightening the fixing screw 3.

[0028] The positioning block 2 is machined into an L-shape with external dimensions of 23mm × 6mm × 5mm, made of stainless steel. The front end protrudes 5mm at an angle. This 5mm protrusion is designed to prevent interference during welding and clamping, as some metal tube shells 4 are often designed with a smaller end and a larger middle for functional purposes. The top end is machined into an R10 arc surface and includes an M3 second threaded through hole 203. This ensures that the center of the hole is concentric with the M3 threaded hole on the first boss 101 of the base 1 after assembly, allowing the upper and lower ceramic insulators to be aligned on the same axis during welding of the metal tube shell 4. The first inclined surface 202 and the second inclined surface 204 are machined to facilitate welding irregular metal tube shells 4 and reduce tooling heat capacity, improve temperature uniformity, and enhance welding quality. A 5mm deep M3 threaded hole 205 is machined at the rear for the fixing screw 3 to tighten and secure it. A second boss 201 should also be machined. The outline dimensions of the boss should correspond one-to-one with the dimensions of the square groove 104 at the rear end of the base 1, so that the positioning block 2 can slide stably up and down in the square groove 104 at the rear end of the base 1. The gap between the boss and the groove should be 0.01mm to 0.03mm, and the surface finish of the mating surfaces should not be less than 0.4. This is to prevent the gap from being too large and the tooling precision from being insufficient, which would cause the two ceramic insulators 6 on the metal tube shell 4 to be out of sync and excessively skewed.

[0029] The metal shell 4 is the product we need to weld. The material is generally Kovar, and it is processed into a cylindrical shape. Firstly, it is easy to process and has low manufacturing cost, and secondly, the stress is relatively uniform. The metal shell 4 is processed with one or two through holes according to the design requirements for welding ceramic insulators 6.

[0030] The anti-rotation fixing plate 5 is machined into a rectangle with a length of 36mm, a width of 3mm, and a height of 15mm. Its function is to prevent the metal tube shell 4 from rotating left and right on the first boss 101 of the base 1, thereby increasing the stability during assembly and welding. The material is stainless steel, and a groove 501 is machined at the bottom end. The outline dimensions of the groove should correspond one-to-one with the dimensions of the first boss 101 of the base 1. Two anti-rotation fixing plates 5 are machined. One plate has a 3mm diameter through hole and the other plate has an M3mm threaded hole, which are used to install and fix the screw 3 to clamp the metal tube shell 4. Alternatively, a row of through holes and threaded holes can be machined along this center line to improve versatility.

[0031] The anti-short circuit fixing ring 7 is machined into a cylindrical shape and made of graphite. Its function is to prevent the solder from short-circuiting the metal tube shell 4 and the feed metal pin 602 of the ceramic insulator 6 due to the vibration of the welding equipment during the brazing process. At the same time, it can reduce the difficulty of solder assembly. The outer diameter is 2.8mm and the height is 3mm. A through hole with a diameter of 1.1mm is machined on the inner side for assembly with the feed metal pin 602 of the ceramic insulator 6.

[0032] The ceramic insulator position adjusting screw 9 is made of stainless steel. Its function is to adjust the height of the ceramic insulator on the metal tube shell 4. It is machined into a cylindrical shape of M3mm×5mm. The outer side is machined with threads to match the first threaded through hole 102 on the first boss 101 of the base 1 and the second threaded through hole 203 on the protruding top of the positioning block 2. The inner side is machined with a through hole with a diameter of 1.1mm for placing the feed metal pin 602 of the ceramic insulator 6. One end is provided with a 1mm×1mm screwdriver groove.

[0033] Example 2

[0034] The specific clamping process using the device of Example 1 is as follows:

[0035] 1. For example Figure 1 As shown, the two ceramic insulator position adjustment screws 9 are respectively installed in the first threaded through hole 102 of the base 1 and the second threaded through hole 203 of the positioning block 2, with the top end flush with the outer side of the two parts.

[0036] 2. Install the positioning block 2 into the sliding groove 104 of the base 1 using the fixing screws 3, and ensure that the positioning block 2 can be slid up and down to adjust its height on the base 1;

[0037] 3. Place the two ceramic insulators 6 into the small holes of the two ceramic insulator position adjusting screws 9 (if the metal tube shell 4 to be welded has only one hole, then only one ceramic insulator needs to be placed).

[0038] 4. Place the metal tube shell 4 between the two ceramic insulators 6, allowing the ceramic insulators to pass through the small holes of the insulators to be welded in the metal tube shell 4. Adjust the position adjusting screws 9 of the ceramic insulators respectively to ensure that the end face of the insulating ring of the upper ceramic insulator 6 is not higher than the outer surface of the metal tube shell and is kept as flush as possible; the end face of the insulating ring of the lower ceramic insulator 6 is slightly higher than the inner surface of the metal tube shell to ensure that the lower end face of the insulating ring on this side is flush with the outer surface of the metal tube shell after welding.

[0039] 5. Install the two anti-rotation fixing plates 5 on both sides of the metal tube shell 4, ensuring that the bottom groove of the anti-rotation fixing plate 5 is placed on the boss of the base 1 and pressed tightly with the fixing screw 3;

[0040] 6. Place the two anti-solder short-circuit fixing rings 7 onto the feed metal pins 602 of the ceramic insulator 6;

[0041] 7. Place the solder ring 8 on the outside of the anti-solder short-circuit fixing ring 7 at the weld position, with the center of the solder directly above the weld. Ensure that the lower end of the solder ring is tightly fitted to the weld. The entire clamping process is now complete.

[0042] The assembled ceramic insulator metal tube shell is placed in an atmosphere-protected furnace or vacuum furnace and welded according to the set parameters to obtain a double ceramic insulator metal tube shell formed in one welding process.

Claims

1. A device for welding metal Dewar feed insulators for infrared detectors, characterized in that, include: The base (1) is L-shaped and has a first boss (101) at its bottom end for mounting the anti-rotation fixing plate (5). The first boss (101) has a first threaded through hole (102) and concentric support platforms (103) at both ends of the first threaded through hole (102). The rear part of the base (1) has a square bar (106) and a sliding groove (104) on the square bar (106). The middle part of the sliding groove (104) has a square groove (105). Positioning block (2), the positioning block (2) is L-shaped and has a second boss (201) at its tail end. The second boss (201) is slidably disposed in the sliding groove (104). The upper end of the positioning block (2) is provided with a second threaded through hole (203). Fixing screw (3), the fixing screw (3) passes through the square groove (105) and is connected to the threaded hole (205) at the top of the second boss (201) for locking the positioning block (2) on the base (1). Anti-rotation fixing plate (5), the bottom end of the anti-rotation fixing plate (5) is provided with a groove (501), the groove (501) cooperates with the first boss (101) to prevent the metal tube shell (4) to be welded from rotating; Two ceramic insulator position adjustment screws (9) are installed in the first threaded through hole (102) and the second threaded through hole (203) respectively, for positioning the ceramic insulator (6) from the inside and outside of the metal tube shell (4) to be welded; as well as A short-circuit protection ring (7) is used to be fitted onto the feed metal pin (602) of the ceramic insulator (6) to physically isolate the solder ring (8) from the feed metal pin (602).

2. The apparatus according to claim 1, characterized in that, The center of the second threaded through hole (203) and the center of the first threaded through hole (102) are on the same axis.

3. The apparatus according to claim 1, characterized in that, The second boss (201) and the sliding groove (104) are in clearance fit, with a clearance of 0.01mm to 0.03mm, and the surface finish of the mating surfaces is not less than 0.

4.

4. The apparatus according to claim 1, characterized in that, The front end of the positioning block (2) has an inclined protrusion to avoid the metal tube shell (4) to be welded, which is large at both ends and small in the middle.

5. The apparatus according to claim 1, characterized in that, The positioning block (2) is also provided with at least one inclined surface (202, 204) to reduce the heat capacity of the tooling and improve temperature uniformity.

6. The apparatus according to claim 1, characterized in that, The anti-solder short-circuit fixing ring (7) is cylindrical, with its outer diameter being smaller than the inner diameter of the solder ring (8) and its inner diameter being larger than the outer diameter of the feed metal pin (602) of the ceramic insulator (6).

7. The apparatus according to claim 6, characterized in that, The material of the anti-solder short-circuit fixing ring (7) is graphite.

8. The apparatus according to claim 1, characterized in that, The ceramic insulator position adjusting screw (9) is cylindrical, with threads on its outer side that match the first threaded through hole (102) and the second threaded through hole (203) respectively, and through holes on its inner side for placing the ceramic insulator (6) power supply metal pin (602).

9. The apparatus according to claim 1, characterized in that, The concentric support (103) is used to prevent the brazing filler metal from contacting the base (1) during welding.

10. A method for welding feeder insulators using the apparatus according to any one of claims 1-9, characterized in that, Includes the following steps: S1, install the two ceramic insulator position adjusting screws (9) into the first threaded through hole (102) of the base (1) and the second threaded through hole (203) of the positioning block (2), respectively; S2, the second boss (201) of the positioning block (2) is inserted into the sliding groove (104) of the base (1) and pre-tightened by the fixing screw (3); S3, place the feeding metal pin (602) of the ceramic insulator (6) into the inner through hole of the ceramic insulator position adjusting screw (9); S4, place the metal tube shell (4) to be welded on the bottom ceramic insulator (6), adjust the two ceramic insulator position adjusting screws (9) so that the ceramic insulator (6) passes through the through hole of the metal tube shell (4) and reaches the predetermined height; S5, use the anti-rotation fixing plate (5) to clamp the metal tube shell (4) and make its bottom groove (501) engage with the first boss (101) of the base (1), and then press it with the fixing screw (3); S6, put the anti-solder short-circuit fixing ring (7) on the feed metal pin (602) of the ceramic insulator (6), and then place the solder ring (8) on the weld position outside the anti-solder short-circuit fixing ring (7); S7, complete clamping and proceed with welding.

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