Size control method for vacuum brazing of cantilever structure stator assembly

Abstract

The invention relates to a size control method for vacuum brazing of a cantilever structure stator assembly. The size control method comprises the following steps that S1, corresponding blade-shaped holes are machined in an outer ring through laser cutting; s2, the blades of the stator are combined with the outer ring and the inner ring through a combination clamp; firstly, an outer ring is fixed to the low end face of a step base of the combined clamp, then a blade is inserted into an inner ring, and the inner ring is placed on a groove in the top of the step base; the large ends of the blades penetrate out of the inner wall of the outer ring to the outer wall of the outer ring through the blade-shaped holes, meanwhile, the small ends of the blades are limited through the movable blocks on the step base, and the radial size of the blades is guaranteed. The inner ring is rotated, the blades are attached to the bottoms and the side faces of the mortises of the movable blocks, and accurate positioning of the blades is achieved; s3, positioning and welding; and S4, the stator assembly is placed in an effective heating area in a vacuum brazing furnace, and vacuum brazing is completed. According to the method, the size precision of vacuum brazing of the stator assembly can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical processing, and more specifically to a dimension control method for vacuum brazing of a cantilever structure stator assembly. Background Art

[0002] The stator assembly of an aircraft engine consists of blades and inner and outer rings, with more than 40 blades. The blades and outer ring are required to be connected by vacuum brazing, while the inner ring and blades are combined in a non-contact manner, and the blades are cantilevered. Each single piece is independent of each other and has no self-limiting structure. The material of the stator assembly is martensitic stainless steel, which is affected by high temperature during vacuum brazing and has a large amount of deformation. At present, the dimensional tolerance rate of the stator assembly after welding is more than 70%.

[0003] Prior art CN105171260A discloses a processing method for an engine stator assembly, which is used for welding a stator blade to a stator ring with the assistance of a positioning fixture, wherein the positioning fixture includes a support seat, a pressing piece and a connecting piece, and includes the following steps: a boss extending along the blade profile of the stator blade is provided at the head end of the stator blade; a plurality of positioning grooves for cooperating with the boss are provided on the support seat, and the plurality of positioning grooves are evenly distributed on the circumference; the lower edge of the stator ring is sleeved on the support seat, and the tail ends of the plurality of stator blades are connected to the wall of the stator ring and the boss is inserted into the positioning groove, the pressing piece is covered on the upper edge of the stator ring, and the stator ring is clamped by connecting the pressing piece to the support seat; the stator blade and the stator ring are welded and positioned; the stator blade and the stator ring are vacuum brazed, the boss is removed by mechanical processing, and the positioning fixture is removed.

[0004] The technical solution disclosed in the prior art fixes the stator assembly by means of a positioning fixture. This method is only applicable to the processing of stator assemblies with smaller sizes and relatively simple blade profiles, and can only control the consistency of the processing dimensions, but cannot improve the processing accuracy of the stator dimensions. Summary of the invention

[0005] The invention provides a dimension control method for vacuum brazing of a cantilever structure stator component, which can improve the dimension processing accuracy of the stator component.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A method for controlling the size of a cantilever structure stator assembly by vacuum brazing, comprising the following steps:

[0008] Step S1: according to the profile data of the blade-shaped hole, the corresponding blade-shaped hole is processed on the outer ring by laser cutting; and the blade-shaped hole is checked by a gauge;

[0009] Step S2: Combine the blades of the stator with the outer ring and the inner ring by using a combined fixture; first fix the outer ring on the lower end surface of the step base of the combined fixture, then insert the blade into the inner ring, and then place the inner ring in the groove on the top of the step base; the large end of the blade passes through the inner wall of the outer ring through the blade-shaped hole to the outer wall of the outer ring, and at the same time, put the small end of the blade into the tenon of the movable block to preliminarily position the small end of the blade; rotate the inner ring to make the blade fit with the bottom and side of the tenon of the movable block to achieve accurate positioning of the blade, and ensure the radial size of the blade and the installation angle between the blade and the stacking shaft of the engine;

[0010] S3: Connect the outer ring and the blade to the negative pole of the ball spot welding positioning device, and test on the test piece. When the feedback current of the welding point is ≥800A, apply pressure to ensure that the nickel-chromium ball is in contact with the blade and the outer ring, and the nickel-chromium ball melts to achieve positioning welding;

[0011] S4: Place the stator assembly into the effective heating zone of the vacuum brazing furnace to complete vacuum brazing.

[0012] Preferably, the step S1 further comprises using a grinding needle to remove burrs in the blade-shaped hole and the recast layer until the metallic luster is exposed.

[0013] Preferably, in step S2, when the outer ring is placed on the lower end surface of the step base, the latch passes through the positioning hole on the outer ring to position the outer ring and the step base.

[0014] Preferably, after the outer ring and the step base are positioned, a pressure plate and screws are used to fasten the outer ring and the step base.

[0015] Preferably, after the outer ring is fixed to the step base, the fitting clearance between the outer ring and the step base is checked by a feeler gauge, and the fitting clearance is controlled within 0.05 mm.

[0016] Preferably, in step S4, the stator assembly is assembled with the brazing fixture, the stator assembly is limited by the A surface of the brazing fixture, and the stator assembly is supported by the B surface of the brazing fixture.

[0017] Preferably, in S4, the brazing temperature is 1000±10°C, and after the brazing cycle is completed, the brazing material is cooled to below 70°C and then taken out of the furnace.

[0018] Preferably, the control method further comprises step S5: tempering the stator assembly after it is taken out of the furnace.

[0019] Preferably, the tempering parameters are: raising the temperature to 530-580°C at a rate of 15-25°C / min, maintaining the temperature for 2.5 hours, then filling with argon at 1.5 bar and rapidly cooling to below 100°C before taking out of the furnace.

[0020] Preferably, the control method further comprises step S6: performing dimensional inspection on the stator assembly after the tempering treatment.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Use a combination fixture to fix the outer ring and the inner ring, determine the height between the two to ensure their position, and accurately position the blades to ensure the radial size of the blades and the installation angle between the blades and the engine stacking shaft. Finally, positioning welding is achieved to ensure that the dimensions after vacuum brazing meet the requirements.

[0023] 2. After brazing, tempering treatment is performed to ensure the microstructure and performance of the stator component material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A simplified flow chart of a dimension control method for vacuum brazing of a cantilever structure stator assembly of the present invention;

[0025] Figure 2 A top view of a combined fixture in a dimension control method for vacuum brazing of a cantilever structure stator assembly of the present invention;

[0026] Figure 3 It is a schematic diagram of assembling a stator assembly and a brazing fixture in a dimension control method for vacuum brazing of a cantilever structure stator assembly of the present invention;

[0027] Figure 4 The present invention is a detailed flow chart of a method for controlling the dimensions of a cantilever structure stator assembly by vacuum brazing. DETAILED DESCRIPTION

[0028] In order to clearly illustrate the technical features of the present solution, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0030] In addition, in the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0031] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] In the present application, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0033] Example 1

[0034] like Figures 1-2 As shown, a method for controlling the size of a cantilever structure stator assembly by vacuum brazing is disclosed, comprising the following steps:

[0035] Step S1: according to the profile data of the blade-shaped hole, the corresponding blade-shaped hole is processed on the outer ring by laser cutting; and the blade-shaped hole is checked by a gauge;

[0036] Step S2: Combine the blades of the stator with the outer ring and the inner ring by using a combined fixture; first fix the outer ring on the lower end surface of the step base of the combined fixture, then insert the blade into the inner ring, and then place the inner ring in the groove on the top of the step base; the large end of the blade passes through the inner wall of the outer ring through the blade-shaped hole to the outer wall of the outer ring, and at the same time, put the small end of the blade into the tenon of the movable block to preliminarily position the small end of the blade; rotate the inner ring to make the blade fit with the bottom and side of the tenon of the movable block to achieve accurate positioning of the blade, and ensure the radial size of the blade and the installation angle between the blade and the stacking shaft of the engine;

[0037] S3: Connect the outer ring and the blade to the negative pole of the ball spot welding positioning device, and test on the test piece. When the feedback current of the welding point is ≥800A, apply pressure to ensure that the nickel-chromium ball is in contact with the blade and the outer ring, and the nickel-chromium ball melts to achieve positioning welding;

[0038] S4: Place the stator assembly into the effective heating zone of the vacuum brazing furnace to complete vacuum brazing.

[0039] In this embodiment, the corresponding blade-shaped hole is processed on the outer ring using a mechanical cutting device according to the position of the blade-shaped hole relative to the outer ring and the diameter of the blade-shaped hole. In order to improve the processing quality of the blade-shaped hole, the outer ring can be fixed on a base, and then the laser cutting device can align the B reference of the outer ring, and the symmetrical four-point runout is not greater than 0.03. The blade-shaped hole after laser cutting needs to be checked with a gauge, and the single-side clearance between the gauge and the blade-shaped hole is ≤0.05mm, and the total contour clearance is ≤0.1mm.

[0040] The combined fixture mainly includes a step base, which includes two fixed layers of different heights, namely a lower fixed layer and a higher fixed layer. The outer ring is placed on the lower fixed layer, that is, on the lower end surface of the step base. The alignment holes on the outer ring are aligned with the positioning holes on the lower fixed layer, and the positioning holes of the outer ring and the step base are connected by a latch to ensure the installation accuracy of the outer ring. The blades are inserted into the inner ring in sequence, and after all the blades are assembled, the inner ring is placed in the upper fixed layer of the step base, that is, in the top groove of the step base. The blade is an irregular shape, with the end with a larger width as the large end and the end with a smaller width as the small end. The large end of the blade passes through the leaf-shaped hole from the inner wall of the outer ring to the outer wall of the outer ring, and the small end of the blade is preliminarily positioned by the movable block on the step base. At this time, the inner ring is rotated to make the blade fit with the bottom and side of the mortise of the movable block, so as to achieve accurate positioning of the blade and ensure the radial size of the blade and the installation angle between the blade and the stacking shaft of the engine. The number of movable blocks is consistent with the number of blades, and the movable blocks are installed on the step base accordingly. The movable block and the step base can be connected in a sliding manner.

[0041] Then, after turning on the ball spot welding positioning equipment, connect the blade and the outer ring to the negative pole of the ball spot welding positioning device respectively, and set the discharge energy to 50±15WS. To ensure the welding quality, first test on the test piece, and start positioning when the welding point feedback current is ≥800A. The diameter of the nickel-chromium ball is 1mm. After the equipment electrode uses negative pressure to absorb the nickel-chromium ball, a certain pressure is used to make the nickel-chromium ball contact with the blade and the outer ring. At this time, the electrical energy in the equipment energy storage capacitor is quickly released to the joint, so that the nickel-chromium ball is instantly heated and melted to achieve positioning. The symmetrical positioning method is used for positioning.

[0042] Finally, the stator assembly after positioning welding is placed in a vacuum brazing furnace to complete the vacuum brazing.

[0043] The outer ring and the inner ring are fixed by a combined fixture to determine the height between the two to ensure their positions, and at the same time limit the height, angle and uniformity of the blades. This enables positioning welding and ultimately improves the dimensional accuracy after vacuum brazing. Moreover, this control method can meet the requirements of large-sized blades or stator assembly size processing with complex curved surfaces.

[0044] Example 2

[0045] Disclosed is a method for controlling the size of a cantilever structure stator assembly during vacuum brazing, comprising the following steps:

[0046] Step S1: according to the profile data of the blade-shaped hole, the corresponding blade-shaped hole is processed on the outer ring by laser cutting; and the blade-shaped hole is checked by a gauge;

[0047] Step S2: Combine the blades of the stator with the outer ring and the inner ring by using a combined fixture; first fix the outer ring on the lower end surface of the step base of the combined fixture, then insert the blade into the inner ring, and then place the inner ring in the groove on the top of the step base; the large end of the blade passes through the inner wall of the outer ring through the blade-shaped hole to the outer wall of the outer ring, and at the same time, put the small end of the blade into the tenon of the movable block to preliminarily position the small end of the blade; rotate the inner ring to make the blade fit with the bottom and side of the tenon of the movable block to achieve accurate positioning of the blade, and ensure the radial size of the blade and the installation angle between the blade and the stacking shaft of the engine;

[0048] S3: Connect the outer ring and the blade to the negative pole of the ball spot welding positioning device, and test on the test piece. When the feedback current of the welding point is ≥800A, apply pressure to ensure that the nickel-chromium ball is in contact with the blade and the outer ring, and the nickel-chromium ball melts to achieve positioning welding;

[0049] S4: Place the stator assembly into the effective heating zone of the vacuum brazing furnace to complete vacuum brazing.

[0050] The difference between this embodiment and embodiment 1 is that step S1 further includes using a grinding needle to remove burrs in the blade-shaped hole and the recast layer until the metallic luster is exposed.

[0051] In order to improve the connection stability between the outer ring and the step base, the two can be fastened by using a pressure plate and screws.

[0052] After the outer ring and the step base are fixed, the fitting gap between the outer ring and the step base is checked with a feeler gauge, and the fitting gap is controlled within 0.05mm. The purpose of this design is to accurately control the gap between the outer ring and the step base, so as to ensure the size of the stator assembly after assembly.

[0053] Example 3

[0054] like Figures 3-4 As shown, a method for controlling the size of a cantilever structure stator assembly by vacuum brazing is disclosed, comprising the following steps:

[0055] Step S1: according to the profile data of the blade-shaped hole, the corresponding blade-shaped hole is processed on the outer ring by laser cutting; and the blade-shaped hole is checked by a gauge;

[0056] Step S2: Combine the blades of the stator with the outer ring and the inner ring by using a combined fixture; first fix the outer ring on the lower end surface of the step base of the combined fixture, then insert the blade into the inner ring, and then place the inner ring in the groove on the top of the step base; the large end of the blade passes through the inner wall of the outer ring through the blade-shaped hole to the outer wall of the outer ring, and at the same time, put the small end of the blade into the tenon of the movable block to preliminarily position the small end of the blade; rotate the inner ring to make the blade fit with the bottom and side of the tenon of the movable block to achieve accurate positioning of the blade, and ensure the radial size of the blade and the installation angle between the blade and the stacking shaft of the engine;

[0057] S3: Connect the outer ring and the blade to the negative pole of the ball spot welding positioning device, and test on the test piece. When the feedback current of the welding point is ≥800A, apply pressure to ensure that the nickel-chromium ball is in contact with the blade and the outer ring, and the nickel-chromium ball melts to achieve positioning welding;

[0058] S4: Place the stator assembly into the effective heating zone of the vacuum brazing furnace to complete vacuum brazing.

[0059] The difference between this embodiment and the above-mentioned embodiment is that the stator assembly is assembled with the brazing fixture 1, and the stator assembly is limited by the A surface of the brazing fixture 1, and the stator assembly is supported by the B surface of the brazing fixture 1. The dimensions of the A surface and the B surface of the brazing fixture 1 are obtained by calculating the deformation of the part at the brazing temperature based on the thermal expansion coefficient of the part material in the material manual. After clamping, the part and the fixture are placed together in the effective heating zone of the vacuum brazing furnace. The A surface and the B surface of the brazing fixture 1 are common knowledge in the industry and will not be elaborated here.

[0060] After loading the furnace, set the parameters according to the specified brazing cycle curve and perform vacuum brazing on the parts. The brazing temperature is 1000±10℃. After the brazing cycle is completed, the parts are cooled to below 70℃ and then taken out of the furnace.

[0061] The vacuum brazing temperature is too high, which destroys the structure of the material. In order to ensure the structure of the material, the parts are tempered, raised to 530-580℃ at a rate of 15-25℃ / min, kept for 2.5h, then filled with argon 1.5bar and quickly cooled to below 100℃ before being taken out of the furnace to ensure the hardness of the material.

[0062] In order to control the size of the stator components, all stator components after tempering are subjected to metrological inspection to strictly control product quality.

[0063] Obviously, the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for controlling the size of a cantilever structure stator assembly by vacuum brazing, characterized in that: The control method comprises the following steps: Step S1: according to the profile data of the blade-shaped hole, the corresponding blade-shaped hole is processed on the outer ring by laser cutting; and the blade-shaped hole is checked by a gauge; Step S2: Combine the blades of the stator with the outer ring and the inner ring by using a combined fixture; first fix the outer ring on the lower end surface of the step base of the combined fixture, then insert the blade into the inner ring, and then place the inner ring in the groove on the top of the step base; the large end of the blade passes through the inner wall of the outer ring through the blade-shaped hole to the outer wall of the outer ring, and at the same time, put the small end of the blade into the tenon of the movable block to preliminarily position the small end of the blade; rotate the inner ring to make the blade fit with the bottom and side of the tenon of the movable block to achieve accurate positioning of the blade, and ensure the radial size of the blade and the installation angle between the blade and the stacking shaft of the engine; S3: Connect the outer ring and the blade to the negative pole of the ball spot welding positioning device, and test on the test piece. When the feedback current of the welding point is ≥800A, apply pressure to ensure that the nickel-chromium ball is in contact with the blade and the outer ring, and the nickel-chromium ball melts to achieve positioning welding; S4: Place the stator assembly into the effective heating zone of the vacuum brazing furnace to complete vacuum brazing.

2. The dimension control method for vacuum brazing of a cantilever structure stator assembly according to claim 1 is characterized in that: The step S1 also includes using a grinding needle to remove burrs in the blade hole and the recast layer until the metallic luster is exposed.

3. The dimension control method for vacuum brazing of a cantilever structure stator assembly according to claim 1 is characterized in that: In step S2, when the outer ring is placed on the lower end surface of the step base, the latch passes through the positioning hole on the outer ring to position the outer ring and the step base.

4. The dimension control method for vacuum brazing of a cantilever structure stator assembly according to claim 3 is characterized in that: After the outer ring and the step base are positioned, the outer ring and the step base are fastened using a pressure plate and screws.

5. The dimension control method for vacuum brazing of a cantilever structure stator assembly according to claim 4 is characterized in that: After the outer ring is fixed to the step base, use a feeler gauge to check the fitting gap between the outer ring and the step base. The fitting gap should be controlled within 0.05mm.

6. The dimension control method for vacuum brazing of a cantilever structure stator assembly according to claim 1 is characterized in that: In the step S4, the stator assembly is assembled with the brazing fixture, the stator assembly is limited by the A surface of the brazing fixture, and the stator assembly is supported by the B surface of the brazing fixture.

7. The dimension control method for vacuum brazing of a cantilever structure stator assembly according to claim 1 is characterized in that: In S4, the brazing temperature is 1000±10°C, and after the brazing cycle is completed, the brazing temperature is cooled to below 70°C and then taken out of the furnace.

8. The method for controlling the size of a cantilever structure stator assembly by vacuum brazing according to claim 1, characterized in that: The control method further comprises step S5: performing tempering treatment on the stator assembly after being taken out of the furnace.

9. The method for controlling the size of a cantilever structure stator assembly by vacuum brazing according to claim 8, characterized in that: The tempering parameters are: heating to 530-580°C at a rate of 15-25°C / min, keeping the temperature for 2.5 hours, then filling with argon at 1.5 bar and rapidly cooling to below 100°C before taking out of the furnace.

10. The method for controlling the size of a cantilever structure stator assembly by vacuum brazing according to claim 8, characterized in that: The control method further comprises step S6: performing dimensional inspection on the stator assembly after the tempering treatment.

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