Machining method for axis-bent sheet metal double-layer narrow-gap exhaust nozzle

Abstract

The invention discloses a machining method for a bent-axis sheet metal double-layer narrow-gap exhaust nozzle. The machining method comprises the steps that combined welding of all parts of an inner flow channel assembly, welding of a front support and a rear support on the outer surface of the inner flow channel assembly, parting of an outer cover assembly into an outer cover front wall and an outer cover rear wall and welding of a rear barrel to the outer cover rear wall are conducted in sequence; the inner flow channel assembly is assembled in a cavity of the rear wall of the outer cover with the rear barrel, and the inner flow channel assembly and the rear wall of the outer cover are welded through the front support and the rear support; the outer cover front wall is in butt joint with the outer cover rear wall, and the front support and the rear support are welded to the inner surfaces, corresponding to the inlet and the outlet, of the outer cover front wall; and the butt joint edge of the outer cover front wall and the outer cover rear wall is checked and corrected, and the butt joint side face of the outer cover front wall and the outer cover rear wall is welded. The invention effectively solves the technical problem that the assembling process method after direct processing of a single component in a conventional nozzle is difficult to meet the requirement of steering nozzle assembly combination, ensures that the processing of the nozzle assembly meets various technical requirements, and ensures qualified delivery of the double-layer steering nozzle.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of manufacturing engine sheet metal tail nozzle, in particular to a combined machining method for double-layer thin-wall sheet metal special-shaped fixed tail nozzle. BACKGROUND

[0002] The double-layer special-shaped tail nozzle (as shown in Figure 11 ) is a component formed and welded by high-temperature alloy sheet metal in the assembly of a turboshaft aero-engine, mainly used at the tail outlet of the engine to discharge the airflow of the engine tail along the vertical direction of the engine.

[0003] The tail nozzle is composed of an inner flow passage assembly and an outer cover assembly, and the gap size between the two assemblies is about 30mm, which belongs to a double-layer structure with large size, thin wall and narrow gap. The inner wall of the outer cover assembly is connected and combined with the outer wall of the inner flow passage assembly through multiple arc-shaped supports (such as Figure 2 , Figure 3 and Figure 4 ) distributed along the circumference at the inlet and outlet.

[0004] The inner flow passage assembly has a double-circular ring-shaped inlet composed of an inner circle and an outer circle, and then turns in the vertical direction to a single-layer, nearly rectangular (a long rectangle with four curved sides) outlet structure.

[0005] The outer cover assembly has a single-layer circular inlet, which turns in the vertical direction to a single-layer nearly rectangular (a long rectangle with four curved sides) outlet, and the rear wall of the outer cover has a straight cylinder concentric with the inlet, and the inlet of the outer cover is concentric with the circular ring-shaped inlet of the inner flow passage.

[0006] The conventional double-layer tail nozzle is manufactured by machining the inner and outer cylindrical parts respectively, and then connecting them together through arc-shaped supports. The tail nozzle studied in the present application is a special-shaped nozzle with different shapes of inlet and outlet, vertical turning, and the outer cover assembly containing the inner flow passage assembly structure, with a curved vertical central axis. The conventional process cannot complete the assembly of the components, and a scientific and reasonable parting process design is needed to ensure the process feasibility of the double-layer combined structure, the concentricity of the inlet and outlet end surfaces, and the uniformity of the gap between the inlet and outlet layers.

[0007] The double-layer special-shaped turning tail nozzle receives high-temperature and high-pressure gas discharged by the engine turbine part through the annular channel at the front end, and then forces the gas to turn vertically and discharge. The rear wall of the inner flow channel assembly of the nozzle bears a large axial thrust and transmits it to the outer cover assembly, so the rear wall of the outer cover assembly also bears an axial thrust. When the type is divided, the influence of the strength reduction of the combined weld on the working reliability of the nozzle needs to be considered. Therefore, attention needs to be paid to the method of dividing the structure of the sheet metal double-layer narrow gap tail nozzle with the bending axis, the process of the double-layer structure is finally realized, the assembly and combination machining of the double-layer special-shaped turning nozzle is completed, and the technical requirements of the assembly are ensured. SUMMARY

[0008] The present application aims to provide a sheet metal double-layer narrow gap tail nozzle machining method with a bending axis. By scientifically and reasonably dividing the outer cover assembly, the technical difficulties in the direct machining and assembly process of the single component in the conventional nozzle are effectively solved, the technical requirements of the nozzle assembly machining are ensured, and the qualified double-layer turning nozzle is delivered.

[0009] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: A sheet metal double-layer narrow gap tail nozzle machining method with a bending axis, comprising: Step one, complete the combined welding of all parts of the inner flow channel assembly to form a turning inner flow channel structure including a double-layer circular inlet and a single-layer nearly square outlet; Step two, weld a plurality of front supports on the outer surface edge of the inner flow channel assembly along the circumferential direction of the double-layer circular inlet of the inner flow channel assembly, and weld a rear support on the outer surface edge of the inner flow channel assembly along the circumferential direction of the single-layer nearly square outlet of the inner flow channel assembly; Step three, divide the outer cover assembly into an outer cover front wall and an outer cover rear wall, and the dividing boundary of the outer cover front wall and the outer cover rear wall starts from two corners of the four corners of the nearly square outlet of the outer cover assembly corresponding to the side of the circular inlet of the outer cover assembly, and transitions to the boundary of the circular inlet of the outer cover assembly along the profile of the outer cover assembly. The method for obtaining the dividing boundary line is as follows: A vertical plane and a perpendicular line are made perpendicular to the end face of the circular inlet of the outer cover assembly and the near rectangular outlet of the outer cover assembly, a point on the perpendicular line is taken as the center of the circle, and a radius R circular arc and a straight line are drawn in the vertical plane, wherein the tangent of the first end of the circular arc is perpendicular to the end face of the circular inlet of the outer cover assembly, the straight line is tangent to the second end of the circular arc and points to the near rectangular outlet of the outer cover assembly, and a curve is obtained by translating the circular arc and the straight line with a radius R along the normal direction of the vertical plane. The curve intersects the profile of the outer cover assembly to obtain two intersection lines, and the intersection points of the two intersection lines with the circular inlet of the outer cover assembly are respectively points A and A', and the intersection points with the near rectangular outlet of the outer cover assembly are respectively points B and B'. Connecting points A and A' obtains a line segment AA' with a length of W1, and connecting points B and B' obtains a line segment BB' with a length of W2. Adjust the distance H from the line segment AA' to the center of the circular hole of the circular inlet of the outer cover assembly and the distance L from the line segment BB' to the end face of the circular inlet of the outer cover assembly. When the length W1 and the length W2 are both greater than the maximum width of the inner flow channel assembly, the two intersection lines are the parting boundary lines of the two parts of the outer cover front wall and the outer cover rear wall. Step four, butt the flange curved surface of the rear cylinder body to the edge of the special-shaped hole of the outer cover rear wall, and connect the rear cylinder body and the outer cover rear wall by butt argon arc welding; Step five, assemble the inner flow channel assembly into the cavity of the outer cover rear wall with the rear cylinder body, and weld the inner flow channel assembly and the outer cover rear wall through the front support and the rear support; Step six, butt the two side parting boundary lines of the outer cover front wall with the two side parting boundary lines of the outer cover rear wall, and weld the front support and the rear support to the inner surface of the two end edges of the outer cover front wall corresponding to the inlet and the outlet; Step seven, check and correct the edges of the outer cover front wall and the outer cover rear wall, and weld the side surfaces of the outer cover front wall and the outer cover rear wall.

[0010] Further, the step four further includes checking and correcting the center of the rear cylinder body to ensure that the center of the rear cylinder body is concentric with the circumference corresponding to the circular inlet of the outer cover assembly.

[0011] Further, the step five uses a caliper type welding device to weld the inner flow channel assembly and the outer cover rear wall through the front support and the rear support on the outer surface of the double-layer circular inlet and the near rectangular outlet of the inner flow channel assembly.

[0012] Further, the step six uses contact welding.

[0013] Further, the step seven uses argon arc welding.

[0014] Compared with the prior art, the application provides a thin-walled tail nozzle with a double-layer structure and an axis vertically turned, and a parting processing method thereof. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic view of an inner flow channel assembly; Figure 2 is a schematic view of a front support; Figure 3 is a schematic view of a rear support; Figure 4 is a schematic view of a flow channel assembly with a support; Figure 5 is a parting view of an outer cover; Figure 6 is a schematic view of a front wall of the outer cover; Figure 7 is a schematic view of a rear wall of the outer cover; Figure 8 is a schematic view of a rear cylinder body; Figure 9 is a schematic view of an outer wall of the rear cover with a cylinder; Figure 10 is a schematic view of a flow channel assembly with a rear wall; Figure 11 is a schematic view of a tail nozzle with a double-layer wall of a cylinder. DETAILED DESCRIPTION

[0016] The application will be further described below in combination with specific embodiments, but should not be understood as limiting the scope of the subject matter described herein to the following embodiments. Any modifications, replacements and changes made according to the ordinary technical knowledge and common practices in the art without departing from the technical idea of the application are included in the scope of the application.

[0017] To solve the process technical problems caused by the mutual interference of the vertical turning and the transition from a circular shape to a nearly rectangular shape in the double-layer structure of the tail nozzle and the direct assembly of the components, the application analyzes the structure of the double-layer variable cross-section turning nozzle, studies the structural features of the inner flow channel assembly and the outer cover assembly, formulates the parting structure and parting method of the front and rear walls of the outer cover, realizes the assembly of the nozzle, and makes the indexes meet the technical requirements of the component design.

[0018] Specifically, the present application adopts the following processing ideas: The parting method of the sheet metal double-layer narrow gap tail nozzle structure with the bending axis needs to be implemented under the premise of following the design drawing requirements, wherein the outer wall surface in the double-layer structure of the inner flow channel assembly and the inner wall surface of the outer cover assembly need to be connected through the arc-shaped supports (the front support and the rear support shown in Figure 2 and Figure 3 ). Therefore, the present application first completes all the structural processing of the inner flow channel assembly according to the design drawing requirements, and leaves the axial and radial allowance at the inner ring and the outer ring installation edge (the left end of the circular inlet in Figure 1 and Figure 4 ) of the double-layer circular inlet, welds the arc-shaped supports for connection at the specified positions (the outer surface) of the double-layer circular inlet and the single-layer nearly rectangular outlet, corrects the height of the arc-shaped supports, and ensures that the inner wall surface of the outer cover assembly and the outer wall surface of the outer layer of the inner flow channel assembly can obtain the support height and the passage gap of the double-layer wall of the tail nozzle combination (the annular gap containing the arc-shaped supports at the left end of the circular inlet in Figure 11 ).

[0019] On this basis, the parting process design of the outer cover assembly is carried out. Through analysis, the side wall and the rear wall are most likely to produce overload failure when the high-speed airflow washes the inner side surface of the side wall and the rear wall during the operation of the tail nozzle. Therefore, the outer cover assembly is parted on the inner side surface edge of the outer cover assembly perpendicular to the direction and close to the smooth edge of the left and right side walls, and the outer cover assembly is divided into the outer cover rear wall and the outer cover front wall. This parting structure not only ensures that the inner flow channel assembly of the tail nozzle can be installed into the cavity of the outer cover rear wall, but also ensures the process feasibility of the welding when the outer cover front wall is combined with the outer cover rear wall. Since the side wall and the rear wall are integrated, the overall strength will not be affected by the welding seam, and the overload failure caused by the existence of the welding seam is avoided. In addition, a more reasonable welding operation space is provided in the process of connecting the arc-shaped supports of the inner flow channel assembly wall and the outer cover assembly wall, which provides the best process technical approach for the combination processing of the tail nozzle.

[0020] The purpose of the present application is to ensure the process feasibility of the double-layer structure deflection nozzle, and to provide the welding operability of the combined structure, so as to form the required welding structure by controlling the welding parameters. For this purpose, the present application designs the following specific implementation scheme: 1. First, complete the combination welding of all parts of the inner flow channel assembly to form the deflection inner flow channel structure including the double-layer circular inlet and the nearly rectangular outlet (as shown in Figure 1 ); 2. The arc-shaped supports (the front support in Figure 2 and Figure 3The rear support bracket (as per the drawings) is welded to the edges of the double-layer circular inlet and single-layer near-rectangular outlet of the inner flow channel assembly, respectively (e.g., Figure 4 (Welding along the circumferential surface) 3. The outer casing assembly is divided into two parts: the front wall and the rear wall. The parting line starts from the lower left and lower right corners of the outer casing assembly near the rectangular exit. Figure 5 (Lower left and lower right corners of the middle right figure), transitioning along the profile of the outer casing assembly to the circular inlet boundary of the outer casing assembly ( Figure 5 The circular inlet parting line of the outer casing assembly is offset downwards by a dimension H from the center of the circular hole, and the near-rectangular outlet parting line of the outer casing assembly faces backwards from the end where the circular inlet of the outer casing assembly is located. Figure 5 Offset from the center to the right (corresponding to the rear wall direction of the outer casing) by a distance L. (The dimensions of H and L should ensure that the width dimensions W1 and W2 are greater than the maximum installation width of the inner flow channel assembly, which is the maximum width of the inner flow channel assembly). Draw an arc R centered at the circular inlet end face of the outer casing assembly. At a distance L from the circular inlet end face of the outer casing assembly, draw a tangent line from the rectangular outlet section of the outer casing assembly to the end of the arc R (i.e., the tangent line is tangent to the end of the arc R), forming a line like... Figure 5 The curve shown in the middle left figure, the surface passing through this curve and perpendicular to the circular inlet end face of the outer casing assembly (i.e., the curve formed by the arc R and the tangent along the curve) Figure 5 The surface formed by the directional offset of length W1 or length W2 is used to divide the outer casing component profile, with the dividing endpoints as follows: Figure 5 Points A, A', B, and B' shown form the front wall of the outer casing ( Figure 6 ), outer cover rear wall ( Figure 7 The outer casing consists of two parts. The opening width of the rear wall of the outer casing must be greater than the width of the inner flow channel assembly to ensure that the inner flow channel assembly can be assembled into the cavity of the rear wall of the outer casing. 4. The rear cylinder ( Figure 8 The flanged curved surface of the outer casing is joined to the edge of the irregular hole on the rear wall of the outer casing using butt argon arc welding. Figure 9 Check and correct the center of the rear cylinder to ensure that it is concentric with the circumference of the circular inlet of the outer cover assembly (more precisely, concentric with the inlet arc of the rear wall of the outer cover). 5. Assemble the inner flow channel assembly into the cavity of the outer casing rear wall with a cylindrical body. Use a clamp-type welding device to weld the inner flow channel assembly to the outer casing rear wall through the arc-shaped brackets at the inlet and outlet of the outer wall surface of the inner flow channel assembly. Figure 10 ); 6, the two sides of the front wall of the outer cover (corresponding to the parting boundary line) and the two sides of the rear wall of the outer cover (corresponding to the parting boundary line) are butted, the consistency of the butt edge is ensured, meanwhile, the arc of the inlet end of the front wall of the outer cover and the arc of the inlet end of the rear wall of the outer cover are checked and corrected to be on the same arc surface, the inlet end surface of the front wall of the outer cover is flush with the inlet end surface of the rear wall of the outer cover, and the arc-shaped support is welded to the inner wall of the edge of the inlet and outlet end of the front wall of the outer cover by contact welding; 7, the edge consistency of the butt joint of the front wall of the outer cover and the rear wall of the outer cover is checked and corrected, and then the two side surfaces of the front wall of the outer cover and the rear wall of the outer cover are connected by argon arc welding (8) Figure 11 ), and the parting and combined connection of the double-layer turning nested structure tail nozzle are completed.

[0021] The contents not described in detail in the specification of the present application belong to the prior art known to those skilled in the art. Although the above describes the specific embodiments of the present application in a descriptive manner, so as to facilitate the understanding of the present application by those skilled in the art, it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all the inventions utilizing the concept of the present application are included in the protection.

Claims

1. A method for processing a double-layer narrow-gap tail nozzle with a curved axis, characterized in that, include: Step 1: Complete the assembly and welding of all parts of the inner flow channel assembly to form a turning inner flow channel structure including a double-layer circular inlet and a single-layer near-square outlet; Step 2: Weld multiple front brackets circumferentially to the outer surface edge of the inner flow channel assembly along the double-layer circular inlet of the inner flow channel assembly, and weld the rear bracket circumferentially to the outer surface edge of the inner flow channel assembly along the single-layer near-square outlet of the inner flow channel assembly. Step 3: Divide the outer casing assembly into two parts: the front wall and the rear wall. The parting line between the front and rear walls begins at two corners on the side of the circular inlet of the outer casing assembly, corresponding to the four corners near the rectangular outlet. It transitions along the surface of the outer casing assembly to the circular inlet boundary. The method for obtaining the parting line is as follows: Draw a perpendicular plane and a perpendicular line from the center of the circular inlet of the outer cover assembly to the near rectangular outlet of the outer cover assembly. Take a point on the perpendicular line as the center of a circle and draw an arc and a straight line of radius R within the perpendicular plane. The tangent at the first end of the arc is perpendicular to the end face of the circular inlet of the outer cover assembly, and the straight line is tangent to the second end of the arc and points towards the near rectangular outlet of the outer cover assembly. Translate the arc and straight line of radius R along the normal direction of the perpendicular plane to obtain a curved surface. This curved surface intersects the surface of the outer cover assembly, forming two intersecting lines. Denote the intersection of these two intersecting lines with the circular inlet of the outer cover assembly. The intersection points of the openings are points A and A', and the intersection points with the near rectangular outlet of the outer cover assembly are points B and B'. Connecting points A and A' yields line segment AA' of length W1, and connecting points B and B' yields line segment BB' of length W2. Adjusting the distance H from line segment AA' to the center of the circular hole of the outer cover assembly and the distance L from line segment BB' to the end face of the circular inlet of the outer cover assembly, when both length W1 and length W2 are greater than the maximum width of the inner flow channel assembly, the two intersecting lines are the parting boundary lines of the front wall and rear wall of the outer cover. Step 4: Connect the flanged curved surface of the rear cylinder to the edge of the irregular hole on the rear wall of the outer cover, and connect the rear cylinder and the rear wall of the outer cover by butt argon arc welding. Step 5: Assemble the inner flow channel assembly into the cavity of the rear wall of the outer casing with the rear cylinder, and weld the inner flow channel assembly and the rear wall of the outer casing through the front bracket and the rear bracket. Step 6: Align the parting boundary lines on both sides of the front wall of the outer cover with the parting boundary lines on both sides of the rear wall of the outer cover, and weld the front bracket and the rear bracket to the inner surfaces of the corresponding inlet and outlet edges of the front wall of the outer cover. Step 7: Inspect and correct the edges where the front and rear walls of the outer cover meet, and weld the sides where the front and rear walls of the outer cover meet.

2. The method for processing a double-layer narrow-gap tail nozzle with a curved axis in sheet metal according to claim 1, characterized in that: Step four also includes checking and correcting the center of the rear cylinder to ensure that the center of the rear cylinder is concentric with the circumference corresponding to the circular inlet of the outer cover assembly.

3. The method for processing a double-layer narrow-gap tail nozzle with a curved axis in sheet metal according to claim 1, characterized in that: In step five, a clamp-type welding device is used to weld the inner flow channel assembly to the rear wall of the outer casing through the front and rear supports on the outer surface of the double-layer circular inlet and near-rectangular outlet of the inner flow channel assembly.

4. The method for processing a double-layer narrow-gap tail nozzle with a curved axis in sheet metal according to claim 1, characterized in that: Contact welding is used in step six.

5. The method for processing a double-layer narrow-gap tail nozzle with a curved axis in sheet metal according to claim 1, characterized in that: Argon arc welding is used in step seven.

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