A size control method for vacuum brazing of a cantilever structure stator assembly

Abstract

The present application relates to a kind of size control methods of cantilever structure stator assembly vacuum brazing, comprising the following steps: step S1: corresponding blade hole is processed on outer ring using laser cutting;Step S2: the blade of stator is combined with outer ring and inner ring using combination fixture;First, outer ring is fixed on the low end surface of step base of combination fixture, then blade is inserted into inner ring, and then inner ring is placed on the recess on the top of step base;Large end of blade passes through blade hole from the inner wall of outer ring to the outer wall of outer ring, while small end of blade is limited by movable block on step base, to ensure the radial dimension of blade;Rotate inner ring, blade is attached to the bottom of mortise and groove of movable block and side surface, to realize accurate positioning of blade;S3: positioning welding;S4: stator assembly is placed in effective heating zone in vacuum brazing furnace to complete vacuum brazing.The present application can improve the size accuracy of stator assembly vacuum brazing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mechanical processing, more particularly, to a size control method for vacuum brazing of a cantilever structure stator assembly. BACKGROUND

[0002] An aero-engine stator assembly is composed of blades and inner and outer rings, the number of blades reaches more than 40, the blades and the outer ring are required to be connected by vacuum brazing, the inner ring and the blades are combined in a non-contact manner, the blades are in a cantilever structure, each single piece is independent of each other and has no self-limiting structure, the material of the stator assembly is martensitic stainless steel, the deformation is large when vacuum brazing under the influence of high temperature, and the post-welding size of the stator assembly is more than 70% out of tolerance.

[0003] The prior art CN105171260A discloses a processing method for an engine stator assembly, which is used for welding stator blades on a stator ring under the assistance of a positioning clamp, the positioning clamp comprises a support seat, a pressing piece and a connecting piece, and comprises the following steps: a boss extending along the blade profile of the stator blade is arranged at the first end of the stator blade; a plurality of positioning grooves for cooperating with the boss are arranged on the support seat, and the plurality of positioning grooves are uniformly distributed in a circle; the stator ring is sleeved on the support seat, the tail ends of the plurality of stator blades are connected with the wall body of the stator ring, the boss is clamped into the positioning groove, the pressing piece is covered on the stator ring, and the stator ring is clamped by the support seat through the connecting piece; the stator blades and the stator ring are welded and positioned; the stator blades and the stator ring are vacuum brazed, the boss is removed by machining, and the positioning clamp is removed.

[0004] The technical solution disclosed by the prior art fixes the stator assembly by the positioning clamp, which is only suitable for processing of the stator assembly with small size and relatively simple blade profile, and can only control the consistency of the processing size, and cannot improve the processing precision of the stator size. SUMMARY

[0005] The present application provides a size control method for vacuum brazing of a cantilever structure stator assembly, which can improve the processing precision of the stator assembly size.

[0006] To solve the above technical problems, the technical solution of the present application is as follows:

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

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

[0009] Step S2: combining the blade of the stator with the outer ring and the inner ring by using the combination clamp; first, fix the outer ring on the low end face of the step base of the combination clamp, 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 to the outer wall of the outer ring through the airfoil hole, and at the same time, the small end of the blade is placed into the mortise of the movable block to preliminarily position the small end of the blade; rotate the inner ring to make the blade fit the bottom and the side of the mortise of the movable block to realize accurate positioning of the blade and ensure the radial dimension of the blade and the installation angle between the blade and the accumulation shaft of the engine;

[0010] S3: connect the blade and the outer ring with the negative pole of the ball spot welding positioning device respectively, test on the test piece, when the welding point feedback current is greater than or equal to 800 A, apply pressure to ensure that the nickel-chromium ball contacts the blade and the outer ring, and the nickel-chromium ball melts to realize the positioning welding;

[0011] S4: place the stator assembly into the effective heating area in the vacuum brazing furnace to complete the vacuum brazing.

[0012] Preferably, the step S1 further comprises removing burrs and re-cast layers in the airfoil hole by using a grinding needle until the metal luster is exposed.

[0013] Preferably, in the step S2, when the outer ring is placed on the low end face 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, the outer ring and the step base are fastened by using a pressing plate and a screw.

[0015] Preferably, after the outer ring and the step base are fixed, the fit gap between the outer ring and the step base is checked by using a feeler gauge, and the fit gap is controlled within 0.05 mm.

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

[0017] Preferably, in the step S4, the brazing temperature is 1000±10℃, and after the brazing cycle is completed, the furnace is cooled to below 70℃ and then discharged.

[0018] Preferably, the control method further comprises a step S5: after being discharged, the stator assembly is subjected to tempering treatment.

[0019] Preferably, the tempering parameters are: increase the temperature to 530-580℃ at a rate of 15-25℃ / min, keep the temperature for 2.5h, then fill argon at 1.5bar, fast cool to below 100℃, and then discharge.

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

[0021] Compared with the prior art, the present application has the following advantages:

[0022] 1. The outer ring and the inner ring are fixed by the combined fixture, the height between the two is determined to ensure the positions of the two, and the blade is precisely positioned to ensure the radial size of the blade and the installation angle between the blade and the engine stacking shaft. Finally, the positioning welding is realized, and finally the size after vacuum brazing is ensured to meet the requirements.

[0023] 2. The tempering treatment is performed after brazing to ensure the microstructure and performance of the stator assembly material. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A simple flowchart of the size control method of the cantilever structure stator assembly vacuum brazing of the present application;

[0025] Figure 2 A top view of the combined fixture in the size control method of the cantilever structure stator assembly vacuum brazing of the present application;

[0026] Figure 3 An assembly schematic view of the stator assembly and the brazing fixture in the size control method of the cantilever structure stator assembly vacuum brazing of the present application;

[0027] Figure 4 A detailed flowchart of the size control method of the cantilever structure stator assembly vacuum brazing of the present application. DETAILED DESCRIPTION

[0028] In order to clearly illustrate the technical features of the present application, the present application will be described in detail below with specific embodiments, and combined with the accompanying drawings.

[0029] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be practiced in other ways different from those described herein, therefore, the scope of protection of the present application is not limited by the specific embodiments disclosed below.

[0030] In addition, in the description of the present application, it needs to 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 the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0031] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection, or communication; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. In the description of the present application, the description referring 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 the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0033] Embodiment 1

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

[0035] Step S1: According to the profile data of the blade type hole, the corresponding blade type hole is machined on the outer ring by laser cutting; and the blade type hole is checked by using a gauge;

[0036] Step S2: combining the stator blade with the outer ring and the inner ring by using the combination fixture; first, fixing the outer ring on the low end surface of the stepped base, then inserting the blade into the inner ring, and then placing the inner ring in the groove on the top of the stepped base; the large end of the blade passes through the airfoil hole from the inner wall of the outer ring to the outer wall of the outer ring, while the small end of the blade is placed into the mortise of the movable block for preliminary positioning; rotating the inner ring to make the blade fit the bottom and side of the mortise of the movable block, thus realizing accurate positioning of the blade and ensuring the radial dimension of the blade and the installation angle between the blade and the engine;

[0037] S3: connecting the blade and the outer ring with the negative pole of the ball spot welding positioning device, testing on the test piece, and when the welding spot feedback current is greater than or equal to 800 A, applying pressure to ensure that the nickel-chromium ball contacts the blade and the outer ring, and the nickel-chromium ball melts to realize the positioning welding;

[0038] S4: placing the stator assembly into the effective heating area in the vacuum brazing furnace to complete the vacuum brazing.

[0039] In the embodiment, according to the position of the airfoil hole relative to the outer ring and the diameter of the airfoil hole, a corresponding airfoil hole is machined on the outer ring by using a mechanism cutting device. In order to improve the machining quality of the airfoil hole, the outer ring can be fixed on a base, and then the B reference of the outer ring is aligned by the laser cutting device, and the symmetrical four-point runout is not greater than 0.03. After laser cutting machining, the airfoil hole needs to be checked by using a gauge, and the single-side gap between the gauge and the airfoil hole is less than or equal to 0.05 mm, and the total profile gap is less than or equal to 0.1 mm.

[0040] The combination fixture mainly includes a stepped base, and the stepped base includes two fixed layers with different heights, i.e., a low fixed layer and a high fixed layer. The outer ring is placed on the low fixed layer, i.e., the low end surface of the stepped base. The alignment hole on the outer ring is aligned with the positioning hole on the low fixed layer, and the outer ring is connected with the positioning hole of the stepped base through a pin, so as to ensure the installation accuracy of the outer ring. The blade is sequentially inserted into the inner ring, and then the inner ring is placed in the groove on the top of the stepped base after the blade is completely assembled. The blade has an irregular shape, and the wide end is the large end and the narrow end is the small end. The large end of the blade passes through the airfoil 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 stepped base. At this time, the inner ring is rotated to make the blade fit the bottom and side of the mortise of the movable block, thus realizing accurate positioning of the blade and ensuring the radial dimension of the blade and the installation angle between the blade and the engine. The number of movable blocks is consistent with the number of blades, and the movable blocks are correspondingly installed on the stepped base. The movable block and the stepped base can be connected in a sliding manner.

[0041] Then, the ball spot welding positioning device is started, the blade and the outer ring are respectively connected with the negative electrode of the ball spot welding positioning device, and the discharge energy is set to 50±15 WS. In order to ensure the welding quality, the test is first carried out on the test piece, and when the welding point feedback current is greater than or equal to 800 A, the positioning is started. The diameter of the nickel-chromium ball is 1 mm. After the electrode of the device adsorbs the nickel-chromium ball by using negative pressure, a certain pressure is used to make the nickel-chromium ball contact with the blade and the outer ring. At this time, the electric energy in the energy storage capacitor of the device is rapidly released to the joint, so that the nickel-chromium ball is instantaneously heated and melted, thereby realizing positioning. The symmetric positioning method is adopted during positioning.

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

[0043] The outer ring and the inner ring are fixed by using the combined clamp to determine the height between the two and thereby ensure the positions of the two. The height, angle and uniform distribution of the blade are limited, thereby realizing positioning welding and finally improving the dimensional accuracy after vacuum brazing. Moreover, the size machining of the stator assembly with large-size blades or complex curved surfaces can be met by using the control method.

[0044] Embodiment 2

[0045] A size control method for vacuum brazing of a cantilever structure stator assembly is disclosed, which comprises the following steps:

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

[0047] Step S2: the blade of the stator is combined with the outer ring and the inner ring by using a combined clamp; first, the outer ring is fixed on the low end surface of the stepped base of the combined clamp, then the blade is inserted into the inner ring, and the inner ring is placed in the groove on the top of the stepped base; the large end of the blade passes through the inner wall of the outer ring to the outer wall of the outer ring through the blade hole, and the small end of the blade is placed into the mortise of the movable block to preliminarily position the small end of the blade; the inner ring is rotated to make the blade fit with the bottom and the side surface of the mortise of the movable block, thereby realizing accurate positioning of the blade and ensuring the radial dimension of the blade and the installation angle between the blade and the accumulation shaft of the engine;

[0048] S3: the outer ring and the blade are connected with the negative electrode of the ball spot welding positioning device, and when the welding point feedback current is greater than or equal to 800 A, pressure is applied to ensure that the nickel-chromium ball contacts with the blade and the outer ring, and the nickel-chromium ball is melted to realize positioning welding;

[0049] S4: the stator assembly is placed into the effective heating area of the vacuum brazing furnace to complete vacuum brazing.

[0050] The difference between the embodiment and embodiment 1 is that step S1 further comprises removing burrs and recast layers in the blade hole by using a polishing needle until the metal luster is exposed.

[0051] In order to improve the connection stability of the outer ring and the stepped base, the plate and the screw can be used to fasten the two.

[0052] After the outer ring and the stepped base are fixed, the fit gap of the outer ring and the stepped base is checked by a plug gauge, and the fit gap is controlled within 0.05 mm. The purpose of this design is to accurately control the gap between the outer ring and the stepped base, thereby ensuring the size of the stator assembly after combination.

[0053] Embodiment 3

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

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

[0056] Step S2: the blades of the stator are combined with the outer ring and the inner ring by using a combination clamp; first, the outer ring is fixed on the low end surface of the stepped base of the combination clamp, then the blade is inserted into the inner ring, and the inner ring is placed in the groove on the top of the stepped base; the large end of the blade passes through the inner wall of the outer ring to the outer wall of the outer ring through the blade hole, and at the same time, the small end of the blade is placed in the mortise of the movable block to preliminarily position the small end of the blade; the inner ring is rotated to make the blade fit with the bottom and side surface of the mortise of the movable block, thereby realizing accurate positioning of the blade and ensuring the radial size of the blade and the installation angle between the blade and the accumulation shaft of the engine;

[0057] S3: the outer ring and the blade are connected with the ball point welding positioning device, and the test is carried out on the test piece; when the welding point feedback current is greater than or equal to 800 A, pressure is applied to ensure that the nickel-chromium ball contacts the blade and the outer ring, and the nickel-chromium ball is melted to realize positioning welding;

[0058] S4: the stator assembly is placed in the effective heating area of the vacuum brazing furnace to complete the vacuum brazing.

[0059] The difference between this embodiment and the above-mentioned embodiments is that the stator assembly is assembled with the brazing clamp 1, the A surface of the brazing clamp 1 limits the stator assembly, and the B surface of the brazing clamp 1 supports the stator assembly. The sizes of the A surface and the B surface of the brazing clamp 1 are calculated according to the thermal expansion coefficient of the material of the parts in the material manual to obtain the deformation amount of the parts at the brazing temperature. After clamping, the parts and the clamp are placed in the effective heating area of the vacuum brazing furnace. The A surface and the B surface of the brazing clamp 1 are well known in the industry, and will not be described in detail here.

[0060] After loading, the parts are vacuum brazed according to the parameters of the specified brazing cycle curve, the brazing temperature is 1000±10℃, and after the brazing cycle is completed, the furnace is cooled to below 70℃ and discharged.

[0061] In order to ensure the material organization, the parts are tempered at the rate of 15-25℃ / min to 530-580℃ for 2.5h, then argon is filled at 1.5bar, and the parts are quickly cooled to below 100℃ and discharged, so as to ensure the hardness of the material.

[0062] In order to control the size of the stator assembly, all the stator assemblies after tempering are measured and inspected, so as to strictly control the product quality.

[0063] Obviously, the above-mentioned embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above-mentioned description. Here, all the embodiments are not required to be exhausted. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method of dimensional control of vacuum brazing of a cantilevered structure stator assembly, characterized by, The control method comprises the following steps: S1: according to the profile data of the blade hole, the corresponding blade hole is machined on the outer ring by laser cutting; and the blade hole is checked by a gauge; S2: the stator blade is combined with the outer ring and the inner ring by using a combined clamp; the combined clamp mainly comprises a stepped base, the stepped base comprises two layers of fixed layers with different heights, namely a low fixed layer and a high fixed layer; the outer ring is placed on the low fixed layer, that is, the low end surface of the stepped base; the positioning hole on the outer ring is aligned with the positioning hole on the low fixed layer, and the outer ring is connected with the positioning hole of the stepped base through a pin, so that the installation accuracy of the outer ring is ensured; the blade is inserted into the inner ring in sequence, and after the blade is assembled, the inner ring is placed in the high fixed layer of the stepped base, that is, the top groove of the stepped base; the blade is irregularly shaped, the wide end is the large end, and the narrow end is the small end; the large end of the blade passes through the blade 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 stepped base at this time; at this time, the inner ring is rotated, so that the blade is attached to the bottom and side of the mortise groove of the movable block, the accurate positioning of the blade is realized, and the radial size of the blade and the installation angle between the blade and the accumulation shaft of the engine are ensured; S3: the blade and the outer ring are respectively connected with the negative electrode of the ball spot welding positioning device, and the test is carried out on the test piece; when the welding point feedback current is greater than or equal to 800 A, pressure is applied to ensure that the nickel-chromium ball is in contact with the blade and the outer ring, and the nickel-chromium ball is melted to realize the positioning welding; S4: the stator assembly is placed in the effective heating area in the vacuum brazing furnace to complete the vacuum brazing.

2. The method of claim 1, wherein the method is used for a shroud assembly of a cantilevered structure vacuum brazing, and the method comprises the steps of: The step S1 further comprises removing burrs and recast layers in the blade hole by using a polishing needle until the metal luster is exposed. ​ 3. The method of claim 1, wherein the method further comprises: In the step S2, when the outer ring is placed on the low end surface of the stepped base, the pin passes through the positioning hole on the outer ring to position the outer ring and the stepped base.

4. The method of claim 3, wherein the method further comprises: After the outer ring and the stepped base are positioned, the outer ring and the stepped base are fastened by using a pressing plate and a screw.

5. The method of claim 4, wherein the method further comprises: After the outer ring and the stepped base are fixed, the fitting gap between the outer ring and the stepped base is checked by using a feeler gauge, and the fitting gap is controlled to be less than or equal to 0.05 mm.

6. The method of claim 1, wherein the method further comprises: In the step S4, the stator assembly is assembled with a brazing clamp, the stator assembly is limited by the A surface of the brazing clamp, and the stator assembly is supported by the B surface of the brazing clamp.

7. The method of claim 1, wherein the method is used for a shroud assembly of a cantilevered structure. In the step S4, the brazing temperature is 1000±10℃, and after the brazing cycle is completed, the furnace is cooled to below 70℃ and the furnace is discharged.

8. The method of claim 1, wherein the method is used for a shroud assembly of a cantilevered structure. The control method further comprises a step S5: after the stator assembly is discharged, the stator assembly is tempered.

9. The method of claim 8, wherein the method further comprises: The parameters of the tempering treatment are as follows: the temperature is increased to 530-580℃ at a rate of 15-25℃ / min, the temperature is maintained for 2.5h, argon is filled to 1.5bar, the temperature is quickly cooled to below 100℃, and the furnace is discharged.

10. The method of claim 8, wherein the method further comprises: The control method further comprises a step S6: the stator assembly after the tempering treatment is subjected to size detection.

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