A method of repairing a gear end tooth

Abstract

The present application relates to the technical field of aero-engine, disclose a kind of gear end tooth repair method, comprising the following steps: S1, preparation package, after filling alloy disc powder in package, package is set on the end tooth of gear;S2, by pressure device let the end tooth of gear and package between vacuum after package brazing sealing;S3, to gear heat isostatic pressing;S4, to gear heat treatment;S5, using circular arc end tooth grinder to gear grinding processing.The alloy disc powder can be realized with the same mechanics of gear parent alloy, anti creep fatigue, no metallurgical defect connection, can effectively solve the problem of crack, poor mechanical properties, poor creep performance, poor wear resistance and so on.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engine, in particular to a gear end tooth repairing method. BACKGROUND

[0002] In order to meet the service safety of aero-engine turbine under extreme harsh conditions, powder metallurgy disc is often selected, which has the characteristics of high density, high strength and high temperature resistance. The aluminum and titanium content of the disc reaches 7%, which is extremely difficult to weld. After a long period of service, the end teeth have different degrees of wear Figure 4 The conventional welding methods such as welding, brazing and hot deposition cannot meet the requirements: cracks are easy to produce, mechanical properties, creep properties and wear resistance are poor, and they are difficult to work under such extreme conditions. SUMMARY

[0003] To solve the above problems, the technical scheme adopted by the present application is as follows:

[0004] A gear end tooth repairing method, comprising the following steps:

[0005] S1, a sleeve is prepared, and the sleeve is sleeved on the end tooth of the gear after filling the alloy disc powder in the sleeve;

[0006] S2, the sleeve is brazed and sealed after vacuum between the end tooth of the gear and the sleeve through a pressure device;

[0007] S3, the gear is subjected to hot isostatic pressing treatment;

[0008] S4, the gear is subjected to heat treatment;

[0009] S5, the gear is subjected to grinding processing using a circular arc end tooth grinder.

[0010] Further, in the step S1, the sleeve is a hollow rectangular body with a U-shaped cross section and an interference fit with the end tooth of the gear.

[0011] Further, the sleeve is integrally formed by forging.

[0012] Further, in the step S2, the pressure device comprises a mounting base, a plurality of placement grooves are formed in the upper end face of the mounting base, the shape of the placement grooves is adapted to the shape of the sleeve for placing the sleeve, a support column is arranged on the upper end face of the mounting base, a drive motor is mounted on the top end of the support column, the output shaft of the drive motor is parallel to the support column and vertically downward, a transmission screw is connected to the output shaft of the drive motor, one end of the transmission screw is fixedly connected to the output shaft of the drive motor through a shaft coupling, the other end is rotatably connected to the upper end face of the mounting base through a bearing, a moving seat is threadedly adapted to the transmission screw, the moving seat is used for mounting the gear and driving the gear to move up and down.

[0013] Further, the placing grooves are circumferentially arranged, the circumferential arrangement radius of the placing grooves is matched with the radius of the gear, the number of the placing grooves is same as the number of the gear end teeth, and the interval between the adjacent placing grooves is matched with the interval between the adjacent gear end teeth.

[0014] Further, the support column, the driving motor and the transmission screw rod are all provided with four.

[0015] Further, a threaded connecting hole is formed at the center of the moving seat, the threaded connecting hole is used for threaded connection with a connecting column, the radius of the connecting column is same as the radius of the shaft hole at the center of the gear, the connecting column is used for fixing the gear, when the gear is fixed, the middle part of the connecting column is located in the threaded connecting hole, the upper end and the lower end of the connecting column respectively extend out of the upper end face and the lower end face of the moving seat, the gear is inserted into the lower end of the connecting column, and the upper end and the lower end of the connecting column are both provided with a locking nut.

[0016] Further, the hot isostatic pressing in the step S3 is under the temperature of 1180 DEG C and the pressure of 175 MPa, and the pressure is kept for 2 hours.

[0017] Further, the heat treatment in the step S4 is under the temperature of 650 DEG C for 16 hours.

[0018] The beneficial effects of the present application are as follows:

[0019] 1. The alloy disc powder can realize the same mechanical, creep fatigue resistance and non-metallurgical defect connection as the gear base alloy, and can effectively solve the problems of crack, poor mechanical property, poor creep property and poor wear resistance.

[0020] 2. The sleeve is made of stainless steel material and is integrally formed by forging and pressing, the forging and pressing integrally formed material uniformly flows through three-way compressive stress, and the metal flow line is continuous and dense in the forging and pressing process, the weak points possibly existing in the traditional welding or splicing process are eliminated, the overall structure of the U-shaped groove is ensured to be defect-free, and the interface leakage risk is avoided.

[0021] 3. The brazing can improve the sealing between the sleeve and the end tooth, and ensure that the alloy powder is in an air-free state. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and serve to explain the principles of the application together with the specification.

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0024] Figure 1 is a sectional view of a pressure device;

[0025] Figure 2 is a top view of a pressure device;

[0026] Figure 3 is a sectional view of a gear;

[0027] Figure 4 is a wear diagram of a gear.

[0028] In the figure: 1, mounting base plate; 2, placing groove; 3, support column; 4, driving motor; 5, transmission screw rod; 6, moving seat; 7, threaded connection hole; 8, connecting column; 9, locking nut. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without any creative effort fall within the scope of protection of the present disclosure.

[0030] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood as the usual meanings understood by those of ordinary skill in the art to which the present disclosure belongs. The terms "first", "second" and the like used in the present disclosure do not represent any order, number or importance, but are only used to distinguish different components. The terms "include" or "contain" and the like mean that the elements or objects before the terms cover the elements or objects listed after the terms and their equivalents, without excluding other elements or objects. "Up", "down", "left", "right" and the like are only used to represent relative positional relationships, and when the absolute positions of the described objects change, the relative positional relationships may also change accordingly.

[0031] As shown in Figures 1-3 A gear end tooth repair method, comprising the following steps:

[0032] S1, preparing a sleeve, filling alloy disc powder in the sleeve, and then sleeving the sleeve on the end tooth of the gear;

[0033] S2. After creating a vacuum between the end teeth of the gear and the sleeve using a pressure device, the sleeve is brazed and sealed.

[0034] S3. Perform hot isostatic pressing on the gears;

[0035] S4. Perform heat treatment on the gears;

[0036] S5. Gears are ground using a circular arc end gear grinding machine.

[0037] In step S1, the sleeve is a hollow rectangular body with a U-shaped cross-section that is interference-fitted with the end teeth of the gear. The U-shaped groove is used to fill alloy disk powder. The sleeve is made of stainless steel and is integrally formed by forging. The integral forging process uses triaxial compressive stress to make the material flow uniformly. Furthermore, the metal flow lines are continuous and dense during the forging process, eliminating the weak points that may exist in traditional welding or splicing processes. This ensures that the overall structure of the U-shaped groove is defect-free and avoids the risk of interface leakage.

[0038] In step S2, the pressure device includes a mounting base plate 1, which can be a large-area rectangular metal plate. The mounting base plate 1 is fixedly installed on the ground, specifically by anchor bolts, to ensure the overall stability of the mounting base plate 1. The upper surface of the mounting base plate 1 has several placement grooves 2. The shape of the placement grooves 2 is adapted to the shape of the sleeve and is used to place the sleeve. The several placement grooves 2 are arranged in a circle, and the radius of the circle is adapted to the radius of the gear. The number of placement grooves 2 is the same as the number of teeth on the gear end. The spacing between adjacent placement grooves 2 is adapted to the spacing between adjacent teeth on the gear end, so that all teeth on the gear can be moved into the placement grooves 2 one by one, ensuring the flatness of the gear when placed on the upper surface of the mounting base plate 1.

[0039] The upper surface of the mounting base plate 1 is provided with a support column 3, which can be fixedly connected to the mounting base plate 1 by welding. A drive motor 4 is installed at the top of the support column 3. The output shaft of the drive motor 4 is parallel to the support column 3 and vertically downward. The output shaft of the drive motor 4 is connected to a transmission screw 5. One end of the transmission screw 5 is fixedly connected to the output shaft of the drive motor 4 through a coupling, and the other end is rotatably connected to the upper surface of the mounting base plate 1 through a bearing. The transmission screw 5 is threadedly fitted with a movable seat 6. The movable seat 6 is used to install gears and drive the gears to move up and down.

[0040] In this invention, the movable seat 6 is a rectangular plate. To ensure the stability of the movable seat 6 when moving up and down, four support columns 3, four drive motors 4, and four transmission screws 5 are provided, each corresponding to one of the four corners of the movable seat 6. It should be noted that when the four drive motors 4 drive the movable seat 6 to move up and down, the four drive motors 4 operate synchronously to ensure that the movable seat 6 can move up and down horizontally and to prevent the movable seat 6 from tilting.

[0041] A threaded connection hole 7 is provided at the center of the movable base 6. The threaded connection hole 7 is used to thread a connecting post 8. The radius of the connecting post 8 is the same as the radius of the shaft hole at the center of the gear. When the gear is installed on the movable base 6, the connecting post 8 is first threaded into the threaded connection hole 7. At this time, the middle part of the connecting post 8 is located in the threaded connection hole 7. The upper and lower ends of the connecting post 8 extend out of the upper and lower end faces of the movable base 6, respectively. Then, a locking nut 9 is first set at the upper end of the connecting post 8 to prevent the connecting post 8 from moving downward. After that, the gear is inserted into the lower end of the connecting post 8 through the shaft hole at its center. A locking nut 9 is set at the lower end of the connecting post 8 to prevent the connecting post 8 from moving downward and to fix the gear, preventing the gear from rotating and ensuring the stability of the gear.

[0042] The vacuum process in step S2 is as follows:

[0043] Place the sleeve into the corresponding placement slot 2 on the mounting base 1, with the opening of the sleeve facing upwards. Place the alloy disc powder into the sleeve. The alloy disc powder is made of the same material as the gear. In order to ensure subsequent processing, the powder mesh size of the alloy disc powder is less than 325, which can improve the uniformity of powder spreading and the interlayer bonding strength. Install the gear onto the moving seat 6. Drive the gear downwards through the drive motor 4, and move the end teeth of the gear into the sleeve. As the end teeth of the gear move slowly in the sleeve, they compress the alloy powder. The air remaining in the sleeve and the alloy powder is squeezed out of the sleeve. Since the sleeve and the end teeth of the gear are interference fit, the sleeve can also be firmly engaged with the end teeth of the gear. The sleeve can be driven out of the placement slot 2 as the gear moves upwards.

[0044] After the sleeve engages with the end teeth of the gear, the gear is removed from the moving seat 6. To further improve the stability of the sleeve and prevent it from falling off, the sleeve is brazed to the end teeth of the gear. Brazing also improves the sealing between the sleeve and the end teeth, ensuring that the alloy powder is in an air-free state.

[0045] In step S3, hot isostatic pressing (HIP) applies uniform pressure to the gear using an inert gas (such as argon or nitrogen) in a sealed container, while simultaneously promoting the sintering of the alloy disk powder at high temperature. In this invention, HIP is completed at 1180°C, 175 MPa, and a holding pressure of 2 hours. 1180°C is close to 70%~80% of the melting point of nickel-based superalloys (such as GH4090). At this temperature, the grain boundary diffusion rate is significantly increased, promoting pore closure and grain rearrangement. The 175 MPa pressure exceeds the material's yield strength, forcing the inner walls of the pores to plastically flow and close, thus eliminating the micron-sized pores remaining in the alloy disk powder metallurgy. The 2-hour holding pressure ensures that the atomic diffusion distance covers the typical pore size, meeting the time required for the steady-state creep stage.

[0046] After hot isostatic pressing is completed, the gear undergoes high temperature and high pressure. Although this can eliminate the porosity between alloy disk powders, it may lead to grain coarsening or the formation of metastable phases (such as supercooled austenite). Furthermore, residual stress still exists in the gear. Heat treatment can refine the grains through normalizing, improve the gear's toughness, and also eliminate the gear's residual stress. In this invention, the heat treatment is carried out at 650°C for 16 hours.

[0047] After heat treatment, the gears are ground using a circular arc end gear grinding machine to achieve the required precision.

[0048] (1) Unless otherwise defined, the same reference numerals in the embodiments and drawings of this disclosure have the same meaning.

[0049] (2) The accompanying drawings of the embodiments of this disclosure only involve the structures involved in the embodiments of this disclosure. Other structures can be referred to the general design.

[0050] (3) For clarity, components or areas are enlarged in the drawings used to describe embodiments of the present disclosure. It will be understood that when an element is referred to as being “above” or “below” another element, the element may be “directly” located “above” or “below” the other element, or there may be an intermediate element.

[0051] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for repairing gear end teeth, characterized in that: Includes the following steps: S1. Prepare the sleeve, fill the sleeve with alloy disk powder, and then put the sleeve on the end teeth of the gear. S2. After creating a vacuum between the end teeth of the gear and the sleeve using a pressure device, the sleeve is brazed and sealed. S3. Perform hot isostatic pressing on the gears; S4. Perform heat treatment on the gears; S5. Gears are ground using a circular arc end gear grinding machine; In step S1, the sleeve is a hollow rectangular body with a U-shaped cross section and an interference fit with the end teeth of the gear. The sleeve is integrally formed by forging. In step S2, the pressure device includes a mounting base plate (1). The upper surface of the mounting base plate (1) is provided with several placement slots (2). The shape of the placement slots (2) is adapted to the shape of the sleeve for placing the sleeve. The upper surface of the mounting base plate (1) is provided with a support column (3). A drive motor (4) is installed at the top of the support column (3). The output shaft of the drive motor (4) is parallel to the support column (3) and vertically downward. The output shaft of the drive motor (4) is connected to a transmission screw (5). One end of the transmission screw (5) is fixedly connected to the output shaft of the drive motor (4) through a coupling. The other end is rotatably connected to the upper surface of the mounting base plate (1) through a bearing. The transmission screw (5) is threadedly adapted to a movable seat (6). The movable seat (6) is used to install gears and drive the gears to move up and down.

2. The method for repairing gear end teeth according to claim 1, characterized in that: The placement slots (2) are arranged in a circular pattern, the radius of which is adapted to the radius of the gear, the number of placement slots (2) is the same as the number of gear teeth, and the spacing between adjacent placement slots (2) is adapted to the spacing between adjacent gear teeth.

3. The method for repairing gear end teeth according to claim 2, characterized in that: The support column (3), drive motor (4) and transmission screw (5) are each provided in four parts.

4. The method for repairing gear end teeth according to claim 3, characterized in that: A threaded connection hole (7) is provided at the center of the movable seat (6). The threaded connection hole (7) is used to thread a connecting column (8). The radius of the connecting column (8) is the same as the radius of the shaft hole at the center of the gear. The connecting column (8) is used to fix the gear. When fixing the gear, the middle part of the connecting column (8) is located in the threaded connection hole (7). The upper end and the lower end of the connecting column (8) extend out of the upper end face and the lower end face of the movable seat (6) respectively. The gear is inserted into the lower end of the connecting column (8), and a locking nut (9) is provided at both the upper end and the lower end of the connecting column (8).

5. The method for repairing gear end teeth according to claim 1, characterized in that: In step S3, hot isostatic pressing is performed at a temperature of 1180°C and a pressure of 175 MPa for 2 hours.

6. The method for repairing gear end teeth according to claim 1, characterized in that: In step S4, the heat treatment involves holding the temperature at 650°C for 16 hours.

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