Vacuum brazing positioning tool for fuel oil manifold

Abstract

This invention relates to the field of welding positioning fixture technology, and discloses a vacuum brazing positioning fixture for a fuel main pipe, comprising: a base fixedly connected to the bottom of a vacuum brazing chamber; a fuel pipe to be brazed and several nozzles located above the base; the nozzles being located on the side of the fuel pipe away from the base; and the fuel pipe having an annular cross-section on its first surface, which is parallel to the plane of the base. This vacuum brazing positioning fixture for a fuel main pipe, by setting a moving mechanism, allows a fourth plate supporting the pipe to smoothly slide outwards along the fourth plate when the fuel pipe expands radially in a high-temperature environment, carrying the third plate with it. This structure provides ample clearance for the fuel pipe, avoiding the reverse compression caused by traditional rigid clamps on the softened pipe at high temperatures, and preventing irreversible collapse or twisting of the thin-walled pipe.

Description

Technical Field

[0001] This invention relates to the field of welding positioning fixture technology, specifically a vacuum brazing positioning fixture for a fuel main pipe. Background Technology

[0002] The fuel main of aircraft engines and gas turbines is typically a complex annular thin-walled pipe with multiple nozzle seats and branch pipes. In actual manufacturing, vacuum brazing is required to weld the nozzle seats and other parts to the main body of the annular main pipe. Vacuum brazing is usually carried out in an extreme high-temperature environment above 1000 °C.

[0003] In existing technologies, brazing positioning clamps for such complex annular thin-walled tubular fittings typically employ rigid limiting blocks or high-temperature resistant spring assemblies to radially and axially clamp and fix the nozzle seat. However, this conventional clamping structure has the following problems in practical applications at extremely high temperatures: When the main body of the fuel manifold is heated to around 1000 °C, it will expand significantly radially outward due to thermodynamic properties. At this time, the yield strength of the stainless steel or high-temperature alloy thin-walled tube decreases exponentially, and the tube wall becomes extremely soft. Traditional rigid clamps or spring assemblies with uncontrollable preload cannot provide smooth radial clearance space, causing the tube body to be squeezed in the opposite direction by the clamps when it expands. This "thermal deformation resistance" can easily cause the soft thin-walled tube to undergo irreversible plastic compression or twisting. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a vacuum brazing positioning fixture for the fuel main pipe, which can prevent the fuel pipe from being plastically crushed or twisted.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a vacuum brazing positioning fixture for a fuel main pipe, comprising: The base is fixedly connected to the bottom of the vacuum brazing box. The fuel pipe to be brazed and several nozzles are located above the base, and the nozzles are located on the side of the fuel pipe away from the base. The cross-section of the fuel pipe on the first surface is annular, and the first surface is parallel to the plane of the base. Several moving mechanisms are capable of moving along with the expanding fuel pipe body during the heating and welding process of the fuel pipe body and several nozzles in the vacuum brazing box; and these moving mechanisms are also capable of ensuring that the annular center position of the fuel pipe body remains unchanged during the expansion process of the fuel pipe body. The pressure mechanism, which has the same number of moving mechanisms, can restrict the brazing positions of several nozzles on the surface of the fuel line during the expansion of the fuel line.

[0006] Furthermore, it also includes positioning mechanisms in the same number as the pressure mechanism. These positioning mechanisms can physically hover when the solid brazing filler metal between the fuel line and the nozzle softens and melts, and allow for capillary filling gaps in the liquid brazing filler metal.

[0007] Furthermore, a moving mechanism, a pressure mechanism, and a positioning mechanism form a group, and the moving mechanism, pressure mechanism, and positioning mechanism in the same group are connected. Several groups of moving mechanisms, pressure mechanisms, and positioning mechanisms are distributed equidistantly around the annular cross section of the fuel pipe, and several groups of pressure mechanisms abut against several nozzles respectively.

[0008] Furthermore, the moving mechanism includes a third block, a fourth plate, and a fourth block. The fourth block has a V-shaped cross-section on the second surface, and the second surface is perpendicular to the plane of the base. The bottom surface of the fourth plate is fixedly connected to the upper surface of the base. The outer wall of the fourth plate is connected to the lower end of the third block. The upper surface of the third block is fixedly connected to the lower end of the V-shape of the fourth block. The fuel pipe is located inside the opening of the V-shape of the fourth block. One side of the upper end of the third block is connected to the pressure mechanism.

[0009] Furthermore, a first groove is formed on the bottom surface of the third block, and a second groove is formed on both sides of the middle part of the fourth plate. The inner wall of the first groove is slidably connected to the outer wall of the fourth plate and the inner walls of the two second grooves. The cross-section of the first groove on the third surface and the cross-section of the fourth plate on the third surface are both T-shaped. The third surface is perpendicular to the plane of the second surface and the base.

[0010] Furthermore, the top surface of the first groove and the inner walls on both sides are each fitted with and rolled with a number of balls. The balls are divided into three groups, and the ball surfaces of the three groups of balls roll against the upper surface and both sides of the fourth plate respectively. The fourth plate has an angle with the base, and the end of the fourth plate closer to the center of the base is lower on the second surface.

[0011] Furthermore, the pressure mechanism includes a rotating assembly, a first plate, and a second block. One end of the rotating assembly is connected to one side of the upper end of the third block, and the other end of the rotating assembly is connected to one end of the first plate. The other end of the first plate is fixedly connected to the upper end of the second block. The bottom surface of the first plate near the second block abuts against the end of the nozzle away from the fuel line. The rotating assembly and the second block are located on both sides of the nozzle, and the cross-section of the first plate on the second surface is L-shaped.

[0012] Furthermore, the rotating assembly includes a first rod and at least one first block. One end of the first block is fixedly connected to one side of the upper end of the third block, and the other end of the first block is fixedly connected to one end of the first rod. The middle part of the first rod is rotatably connected to the end of the first plate away from the second block through a full ceramic bearing. The second block is a high-density counterweight.

[0013] Furthermore, the positioning mechanism includes a second plate, a second rod, and a third plate. The third plate has an arc-shaped cross-section on the second surface. One end of the second plate is fixedly connected to the side wall of the first plate near the nozzle end. The bottom surface of the other end of the second plate is fixedly connected to the upper end of the second rod. The other end of the second rod is fixedly connected to the outer arc surface of the arc of the third plate. The inner arc surface of the arc of the third plate faces the fuel pipe.

[0014] Furthermore, the distance between the inner arc surface of the third plate and the fuel pipe body is less than the thickness of the solid brazing filler metal, and the distance between the inner arc surface of the third plate and the fuel pipe body is also greater than the height of the minimum gap for liquid brazing filler metal between the fuel pipe body and the nozzle.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This vacuum brazing positioning fixture for the fuel main pipe, through the setting of a moving mechanism, allows the fourth block supporting the pipe to smoothly slide outward along the fourth plate when the fuel pipe body undergoes radial expansion in a high-temperature environment. This structure provides ample clearance space for the fuel pipe body, avoiding the reverse compression caused by traditional rigid clamps on the high-temperature softened pipe body, and preventing irreversible collapse or twisting of thin-walled pipes. At the same time, the synchronous guidance of multiple moving mechanisms ensures that the fuel pipe body maintains a concentric circle state throughout the expansion process, greatly improving the dimensional accuracy of the finished product. This vacuum brazing positioning fixture for the fuel main pipe utilizes the weight of the second high-density counterweight block, combined with the lever principle, to firmly press the nozzle onto the fuel pipe body. Since gravity is absolutely constant under any extreme high temperature and vacuum environment, it fundamentally solves the industry pain point that traditional high-temperature springs are prone to creep failure after repeated heating, resulting in loss of clamping force, and ensures the absolute firmness of the nozzle during the heating process. This type of vacuum brazing positioning fixture for fuel main pipe, through the setting of a positioning mechanism, when the solid brazing filler melts and the nozzle loses its bottom support and sinks with the first plate, the inner arc surface of the third plate will precisely abut against the surface of the fuel pipe to form a physical suspension. This not only accurately preserves the tiny capillary gap required by the liquid brazing filler, preventing poor welding and insufficient welding, but also effectively transfers the gravity of the first plate pressing down, avoiding the nozzle pressing out pits on the surface of the fuel pipe that softens at high temperature. This vacuum brazing positioning fixture for the fuel main pipe greatly reduces friction during structural sliding by incorporating ball bearings in the first groove, enabling "zero-stress" pushing of the fuel pipe during expansion. Simultaneously, by setting a certain angle of inclination on the fourth plate, the slider assembly can automatically and smoothly reset along the slope with the help of gravity during the cooling and shrinkage phase after welding, eliminating the need for manual hammering and adjustment, thus extending the service life of the fixture and improving turnover efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall appearance of the present invention; Figure 2 This is a detailed connection diagram of the base and the fourth plate of the present invention; Figure 3 This is a detailed connection diagram of the pressure mechanism, moving mechanism, and fuel pipe body of the present invention; Figure 4 This is a detailed connection diagram of the moving mechanism, fuel pipe body, and nozzle of the present invention; Figure 5 For the present invention Figure 4 Explosion diagrams of various components; Figure 6 For the present invention Figure 5 Enlarged view of point A in the middle; Figure 7 This is a detailed connection diagram of the pressure mechanism, positioning mechanism, and moving mechanism of the present invention; Figure 8 For the present invention Figure 7 Explosion diagram of each component.

[0017] In the picture: 1. Base; 2. Pressure mechanism; 21. Rotating assembly; 211. First block; 212. First rod; 22. First plate; 23. Second block; 3. Positioning mechanism; 31. Second plate; 32. Second rod; 33. Third plate; 4. Moving mechanism; 41. Third block; 411. First groove; 412. Ball bearing; 42. Fourth plate; 421. Second groove; 43. Fourth block; 5. Fuel pipe body; 51. Injector. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] Please see Figures 1-8 A vacuum brazing positioning fixture for a fuel main pipe, comprising: The base 1 is fixedly connected to the bottom of the vacuum brazing box. The fuel pipe body 5 to be brazed and several nozzles 51 are located above the base 1, and the several nozzles 51 are located on the side of the fuel pipe body 5 away from the base 1. The cross-section of the fuel pipe body 5 on the first surface is annular, and the first surface is parallel to the plane of the base 1. Several moving mechanisms 4 are able to move together with the expanding fuel pipe body 5 during the process of heating and welding fuel pipe body 5 and several nozzles 51 in the vacuum brazing box; and several moving mechanisms 4 can also ensure that the annular center position of fuel pipe body 5 remains unchanged during the expansion of fuel pipe body 5. The pressure mechanism 2 is the same number as the moving mechanism 4. The pressure mechanism 2 can restrict the brazing position of several nozzles 51 on the surface of the fuel pipe body 5 during the expansion process of the fuel pipe body 5. It also includes positioning mechanisms 3, which are the same number as pressure mechanisms 2. Positioning mechanisms 3 can physically hover when the solid brazing filler metal between the fuel pipe body 5 and the nozzle 51 softens and melts, and leave a gap for capillary filling of the liquid brazing filler metal.

[0020] First, it should be noted that the fuel pipe body 5 and the nozzle 51 are the workpieces to be brazed in this invention. For ease of description and understanding, their approximate shape is shown in the accompanying drawings, and they are not actual products. In addition, since the fuel pipe body 5 and the nozzle 51 are existing technologies, their materials will not be described in detail here.

[0021] Furthermore, it should be specifically noted that, such as Figures 1-3 As shown, a moving mechanism 4, a pressure mechanism 2, and a positioning mechanism 3 form a group. The moving mechanism 4, pressure mechanism 2, and positioning mechanism 3 in the same group are connected, and several groups of moving mechanisms 4, pressure mechanisms 2, and positioning mechanisms 3 are distributed equidistantly around the annular cross section of the fuel pipe body 5. Several groups of pressure mechanisms 2 abut against several nozzles 51 respectively.

[0022] Furthermore, in order to enable the moving mechanism 4 to move along with the expanding fuel pipe 5 during the heating and welding process of the fuel pipe 5 and several nozzles 51 in the vacuum brazing box; and to ensure that the annular center position of the fuel pipe 5 remains unchanged during the expansion process of the fuel pipe 5, as a preferred embodiment of the present invention, the moving mechanism 4 includes a third block 41, a fourth plate 42 and a fourth block 43. The cross-section of the fourth block 43 on the second surface is V-shaped, and the second surface is perpendicular to the plane of the base 1. The bottom surface of the fourth plate 42 is fixedly connected to the upper surface of the base 1. The outer wall of the fourth plate 42 is connected to the lower end of the third block 41. The upper surface of the third block 41 is fixedly connected to the lower end of the V-shape of the fourth block 43. The fuel pipe 5 is located in the opening of the V-shape of the fourth block 43. One side of the upper end of the third block 41 is connected to the pressure mechanism 2. More specifically, the bottom surface of the third block 41 is provided with a first groove 411, and the two sides of the middle part of the fourth plate 42 are provided with second grooves 421. The inner wall of the first groove 411 is slidably connected to the outer wall of the fourth plate 42 and the inner walls of the two second grooves 421. The cross-section of the first groove 411 on the third surface and the cross-section of the fourth plate 42 on the third surface are both T-shaped. The third surface is perpendicular to the second surface and the plane of the base 1. Specifically, such as Figures 4-6 As shown, when brazing the fuel pipe body 5 and the nozzle 51, the fuel pipe body 5 is first placed inside the fourth block 43V shape. Then, several nozzles 51 are respectively connected to the appropriate position of the fuel pipe body 5 (for example, below the pressure mechanism 2) by solid brazing filler metal. Then, the nozzles 51 are pressed onto the surface of the fuel pipe body 5 by the pressure mechanism 2. Then, the entire tooling (including the base 1 and some other parts) is placed into the vacuum brazing box. Then, the fuel pipe body 5 and the nozzle 51 are heated normally through the vacuum brazing box, so that the fuel pipe body 5 and the nozzle 51 are heated from room temperature to about 1000℃. During the heating process of fuel pipe 5, fuel pipe 5 will gradually expand due to thermal expansion and contraction. [This expansion not only increases the inner and outer diameters of fuel pipe 5 (e.g., the inner diameter of fuel pipe 5 originally 10cm expands to 11cm, while the outer diameter of fuel pipe 5 expands from 15cm to 17cm), but also increases the height of fuel pipe 5 (because fuel pipe 5 is annular, and the expansion range of the inner and outer diameters of fuel pipe 5 is not necessarily the same, for example, the difference between the inner and outer diameters of fuel pipe 5 originally 5cm can now expand to 6cm, and the bottom of fuel pipe 5 is supported by the fourth block 43, so fuel pipe 5 will only "get taller")]. However, because the cross-section of the fourth block 43 is V-shaped, the circular outer wall of fuel pipe 5 will not be affected even if it "gets thicker". In addition, when the inner and outer diameters of the fuel pipe body 5 increase, the fuel pipe body 5 located in the fourth block 43 will push the fourth block 43 to move "outward" along the third block 41 on the surface of the fourth plate 42 to accommodate the distance of the expansion of the outer diameter of the fuel pipe body 5. After the processing is completed, the temperature of the fuel pipe body 5 decreases and the expansion ends. Then the fuel pipe body 5 will pull the fourth block 43 back to its original position. Furthermore, because there are multiple sets of fourth blocks 43, and the movement direction of these multiple sets of fourth blocks 43 is restricted by multiple fourth plates 42, the inner and outer diameters of the fuel pipe 5 will always be in a "concentric circle" state during the expansion process, thereby reducing the probability of deformation of the fuel pipe 5 during the expansion process.

[0023] More specifically, because the expansion of the fuel pipe body 5 requires driving the fourth block 43 and the third block 41 to move "outward" on the surface of the fourth plate 42, in order to avoid deformation of the fuel pipe body 5 due to excessive friction, as a preferred embodiment of the present invention, the top surface of the first groove 411 and the inner walls of both sides are embedded with and rolled with a number of balls 412. The balls 412 are divided into three groups, and the ball surfaces of the three groups of balls 412 roll against the upper surface and both sides of the fourth plate 42 respectively. Specifically, by setting three sets of balls 412 inside the first groove 411 that can roll on the upper surface and sides of the fourth plate 42, it is possible to reduce the friction during movement to a greater extent while ensuring the stable support and connection between the third block 41 and the fourth plate 42.

[0024] More specifically, since the fuel pipe body 5 needs to be cooled after brazing, and the fuel pipe body 5 will gradually "shrink" during the cooling process, in order to reduce the probability of the fuel pipe body 5 being deformed due to external force, as a preferred embodiment of the present invention, the fourth plate body 42 and the base 1 have an angle, wherein the end of the fourth plate body 42 near the center of the base 1 is lower on the second surface. Specifically, by setting an angle (such as tilting 2°) between the fourth plate 42 and the base 1, the fuel pipe 5 can be more easily reset after cooling and shrinking through a small tilt. Also, when the fuel pipe 5 expands, the small tilt can ensure that the expansion is more uniform and not uneven.

[0025] Furthermore, in order to enable the pressure mechanism 2 to restrict the brazing positions of several nozzles 51 on the surface of the fuel pipe body 5 during the expansion process of the fuel pipe body 5, as a preferred embodiment of the present invention, the pressure mechanism 2 includes a rotating component 21, a first plate 22, and a second block 23. One end of the rotating component 21 is connected to one side of the upper end of the third block 41, and the other end of the rotating component 21 is connected to one end of the first plate 22. The other end of the first plate 22 is fixedly connected to the upper end of the second block 23. The bottom surface of the first plate 22 near the end of the second block 23 abuts against the end of the nozzle 51 away from the fuel pipe body 5. The rotating component 21 and the second block 23 are respectively located on both sides of the nozzle 51. The cross-section of the first plate 22 on the second surface is L-shaped. More specifically, the rotating assembly 21 includes a first rod 212 and at least one first block 211. One end of the first block 211 is fixedly connected to one side of the upper end of the third block 41, and the other end of the first block 211 is fixedly connected to one end of the first rod 212. The middle part of the first rod 212 is rotatably connected to the end of the first plate 22 away from the second block 23 via a full ceramic bearing. The second block 23 is a high-density counterweight; Specifically, such as Figure 1 , Figure 3 , Figure 7 and Figure 8 As shown, when brazing the fuel pipe body 5 and the nozzle 51, the first plate 22 is first rotated above the nozzle 51 via the first rod 212 and the first block 211. Because a high-density counterweight block 23 is provided at the end of the first plate 22 near the nozzle 51, the end of the first plate 22 near the nozzle 51 will be "heavier". Gravity is absolutely constant under any temperature and vacuum. No matter how the pipe body expands, sinks or undergoes micro-deformation, the counterweight block always applies an absolutely constant and precisely calculable downward pressure to the nozzle through the lever. Therefore, the first plate 22 can always press the nozzle 51 and fix it on the fuel pipe body 5. Thus, no matter whether the solid brazing filler between the fuel pipe body 5 and the nozzle 51 softens or melts, the first plate 22 can stably press the nozzle 51, thereby reducing the probability of the nozzle 51 loosening during brazing.

[0026] Furthermore, in order to enable the positioning mechanism 3 to physically hover when the solid brazing filler metal between the fuel pipe body 5 and the nozzle 51 softens and melts, and to reserve a capillary gap for the liquid brazing filler metal, as a preferred embodiment of the present invention, the positioning mechanism 3 includes a second plate 31, a second rod 32 and a third plate 33. The cross-section of the third plate 33 on the second surface is arc-shaped. One end of the second plate 31 is fixedly connected to the side wall of the first plate 22 near the nozzle 51. The bottom surface of the other end of the second plate 31 is fixedly connected to the upper end of the second rod 32. The other end of the second rod 32 is fixedly connected to the outer arc surface of the arc-shaped third plate 33. The inner arc surface of the arc-shaped third plate 33 faces the fuel pipe body 5. More specifically, the distance between the inner arc surface of the third plate 33 and the fuel pipe 5 is less than the thickness of the solid brazing filler metal, and the distance between the inner arc surface of the third plate 33 and the fuel pipe 5 is also greater than the height of the minimum gap between the fuel pipe 5 and the nozzle 51 for supplying liquid brazing filler metal. Specifically, such as Figure 1 , Figure 3 , Figure 7 and Figure 8 As shown, during use, the first plate 22 will press down on the upper end of the nozzle 51 due to gravity, while at this time, the inner arc surface of the third plate 33 does not contact the surface of the fuel pipe 5. During the heating process, the fuel pipe 5 will deform normally. During the deformation process, the nozzle 51 will rise and push the first plate 22 to rise together (the first plate 22 will rotate on its own through the first rod 212 and the first block 211 to adapt to this action). When the temperature rises to 900℃, the solid brazing filler metal may soften and melt. Since the gravity of the first plate 22 is constant, the nozzle 51 can no longer rise against the first plate 22 (this can be understood as the positions of the first plate 22 and the nozzle 51 relative to the base 1 remaining unchanged). However, the fuel pipe 5 will continue to expand. To prevent the first plate 22 from completely pressing the nozzle 51 into the fuel pipe 5 and blocking the minimum gap for liquid brazing filler metal between the fuel pipe 5 and the nozzle 51, the distance between the fuel pipe 5 and the nozzle may change slightly (e.g., 0.1mm) when the temperature expands from 900℃ to 1000℃. At this time, the inner arc surface of the third plate 33 presses against the surface of the fuel pipe 5. As the fuel pipe 5 continues to expand, the first plate 22 will move along with the third plate 33, thus no longer putting pressure on the nozzle 51 and preventing the blocking of the minimum gap for liquid brazing filler metal between the fuel pipe 5 and the nozzle 51.

[0027] Finally, it is particularly important to emphasize that, considering the high temperature environment of vacuum brazing above 1000 °C, the contact surfaces of the ball bearing 412, the third plate 33, and the fourth block 43 in contact with the fuel pipe body are preferably made of special ceramic materials such as zirconium oxide or silicon nitride, so as to prevent the diffusion cold welding phenomenon of dissimilar metals in vacuum. In addition, the second block 23 is preferably made of high-temperature resistant tungsten alloy to ensure the optimal ratio of counterweight volume to pressure; Finally, the remaining main components of the tooling (such as the frame of base 1, first groove 411, fourth plate 42, first plate 22, etc.) can be made of Inconel high-temperature alloy (such as nickel-based alloy or molybdenum alloy) or 310S heat-resistant stainless steel.

[0028] Working principle: When in use, first place the fuel pipe body 5 to be processed steadily in the V-shaped opening of the fourth block 43 at the bottom to support it. Then, place the nozzle 51 coated with solid brazing filler metal on the fuel pipe body 5. Then, rotate the first rod 212 to turn the first plate 22 over and press it on the top of the nozzle 51. Because the other end of the first plate 22 is connected to the second counterweight 23, the weight of the counterweight can steadily apply a constant downward pressure to the nozzle 51 and press it tight. In this assembled state, the inner arc surface of the third plate 33 fixed on the side of the first plate 22 is slightly suspended from the fuel pipe body 5 and does not touch. After all is assembled, the entire tooling connected to the base 1 can be pushed into the vacuum brazing furnace for heating. Afterwards, as the temperature in the furnace gradually rises to about 1000 degrees, the fuel pipe 5 will inevitably expand after being heated, becoming thicker and larger. When the fuel pipe 5 expands outwards, it will push the fourth block 43 below it outwards. The fourth block 43, along with the third block 41, moves outwards along the fourth plate 42, relying on the smooth ball bearings 412 inside. In this way, the fuel pipe 5 will not be stuck by the tooling and deformed when it expands. Moreover, because the fourth plate 42 provides directional guidance, the fuel pipe 5 can still maintain a perfect concentric ring shape when it expands. At the same time, the fuel pipe 5 not only becomes thicker, but its height will also increase slightly. At this time, the first plate 22 will rise slightly accordingly, but the second block 23 will always provide downward pressure, pressing down firmly on the nozzle 51 to prevent it from deviating. Subsequently, when the furnace temperature reaches the point where the solid brazing filler metal begins to soften and melt into a liquid state, the volume of the solid brazing filler metal that was originally placed under the nozzle 51 shrinks. The nozzle 51 instantly loses its bottom support and falls down under the heavy pressure of the first plate 22 above. However, the ingenious part of this fixture is that the first plate 22 only falls down a tiny distance, and the inner arc surface of the third plate 33 fixed to its side just hits the surface of the fuel pipe 5, directly supporting the first plate 22. In this way, the heavy pressure of the first plate 22 is transferred to the fuel pipe 5 by the third plate 33, and no longer continues to press down on the nozzle 51. At this time, a very small but extremely precise gap is left between the nozzle 51 and the fuel pipe 5, allowing the molten liquid brazing filler metal to be steadily absorbed in this gap by capillary action, avoiding the failure of soldering caused by the brazing filler metal being squeezed out completely. Finally, when the brazing is completed and the furnace begins to cool down, the fuel pipe 5 will shrink back due to thermal expansion and contraction. Because the fourth plate 42 at the bottom is designed with a slightly lower end near the center of the base 1, it has a small slope. So when it cools and shrinks, the third plate 41 and the fourth plate 43 will naturally follow the gravity of this small slope and move back together with the fuel pipe 5. There will be no extra frictional resistance pulling the pipe. Once it has completely cooled down, the furnace can be opened and the welded product can be removed.

[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended technical solutions and their equivalents.

Claims

1. A vacuum brazing positioning fixture for a fuel main pipe, characterized in that, include: The base (1) is fixedly connected to the bottom of the vacuum brazing box. The fuel pipe (5) to be brazed and several nozzles (51) are located above the base (1), and several nozzles (51) are located on the side of the fuel pipe (5) away from the base (1). The cross section of the fuel pipe (5) on the first surface is annular, and the first surface is parallel to the plane of the base (1). Several moving mechanisms (4) are able to move together with the expanding fuel pipe body (5) during the process of heating and welding the fuel pipe body (5) and several nozzles (51) in the vacuum brazing box; and several moving mechanisms (4) are also able to ensure that the annular center position of the fuel pipe body (5) remains unchanged during the expansion of the fuel pipe body (5). The pressure mechanism (2) is the same number as the moving mechanism (4), and the pressure mechanism (2) is able to restrict the brazing position of several nozzles (51) on the surface of the fuel pipe body (5) during the expansion of the fuel pipe body (5); The moving mechanism (4) includes a third block (41), a fourth plate (42) and a fourth block (43). The fourth block (43) has a V-shaped cross-section on the second surface. The second surface is perpendicular to the plane of the base (1). The bottom surface of the fourth plate (42) is fixedly connected to the upper surface of the base (1). The outer wall of the fourth plate (42) is connected to the lower end of the third block (41). The upper surface of the third block (41) is fixedly connected to the lower end of the V-shape of the fourth block (43). The fuel pipe (5) is located inside the V-shaped opening of the fourth block (43). One side of the upper end of the third block (41) is connected to the pressure mechanism (2).

2. The fuel main pipe vacuum brazing positioning fixture according to claim 1, characterized in that, It also includes positioning mechanisms (3) of the same number as the pressure mechanism (2), which can physically hover when the solid brazing filler metal between the fuel pipe body (5) and the nozzle (51) softens and melts, and leave a gap for capillary filling of the liquid brazing filler metal.

3. The vacuum brazing positioning fixture for a fuel main pipe according to claim 2, characterized in that, A moving mechanism (4), a pressure mechanism (2) and a positioning mechanism (3) are grouped together. The moving mechanism (4), pressure mechanism (2) and positioning mechanism (3) in the same group are connected. Several groups of moving mechanisms (4), pressure mechanisms (2) and positioning mechanisms (3) are distributed equidistantly in the circumferential direction of the annular cross section of the fuel pipe body (5). Several groups of pressure mechanisms (2) respectively abut against several nozzles (51).

4. The vacuum brazing positioning fixture for a fuel main pipe according to claim 3, characterized in that, The bottom surface of the third block (41) is provided with a first groove (411), and the two sides of the middle part of the fourth plate (42) are provided with second grooves (421). The inner wall of the first groove (411) is slidably connected to the outer wall of the fourth plate (42) and the inner walls of the two second grooves (421). The cross section of the first groove (411) on the third surface and the cross section of the fourth plate (42) on the third surface are both T-shaped. The third surface is perpendicular to the plane of the second surface and the base (1).

5. The vacuum brazing positioning fixture for a fuel main pipe according to claim 4, characterized in that, The top surface and the inner walls on both sides of the first groove (411) are fitted with and rolled with a number of balls (412). The balls (412) are divided into three groups, and the ball surfaces of the three groups of balls (412) roll against the upper surface and the sides of the fourth plate (42). The fourth plate (42) has an angle with the base (1), wherein the end of the fourth plate (42) near the center of the base (1) is lower on the second surface.

6. The vacuum brazing positioning fixture for a fuel main pipe according to claim 5, characterized in that, The pressure mechanism (2) includes a rotating assembly (21), a first plate (22), and a second block (23). One end of the rotating assembly (21) is connected to one side of the upper end of the third block (41), and the other end of the rotating assembly (21) is connected to one end of the first plate (22). The other end of the first plate (22) is fixedly connected to the upper end of the second block (23). The bottom surface of the first plate (22) near the second block (23) abuts against the end of the nozzle (51) away from the fuel pipe (5). The rotating assembly (21) and the second block (23) are located on both sides of the nozzle (51). The cross-section of the first plate (22) on the second surface is L-shaped.

7. The vacuum brazing positioning fixture for a fuel main pipe according to claim 6, characterized in that, The rotating assembly (21) includes a first rod (212) and at least one first block (211). One end of the first block (211) is fixedly connected to one side of the upper end of the third block (41), and the other end of the first block (211) is fixedly connected to one end of the first rod (212). The middle part of the first rod (212) is rotatably connected to the end of the first plate (22) away from the second block (23) through a full ceramic bearing. The second block (23) is a high-density counterweight.

8. The vacuum brazing positioning fixture for a fuel main pipe according to claim 7, characterized in that, The positioning mechanism (3) includes a second plate (31), a second rod (32) and a third plate (33). The third plate (33) has an arc-shaped cross-section on the second surface. One end of the second plate (31) is fixedly connected to the side wall of the first plate (22) near the nozzle (51). The bottom surface of the other end of the second plate (31) is fixedly connected to the upper end of the second rod (32). The other end of the second rod (32) is fixedly connected to the outer arc surface of the arc of the third plate (33). The inner arc surface of the arc of the third plate (33) faces the fuel pipe (5).

9. A vacuum brazing positioning fixture for a fuel main pipe according to claim 8, characterized in that, The distance between the inner arc surface of the third plate (33) and the fuel pipe (5) is less than the thickness of the solid brazing filler metal, and the distance between the inner arc surface of the third plate (33) and the fuel pipe (5) is also greater than the height of the minimum gap between the fuel pipe (5) and the nozzle (51) for the liquid brazing filler metal.

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