Near-net forming manufacturing method of wear-resistant transmission gear for aerospace

Abstract

The invention relates to the technical field of aerospace part manufacturing, in particular to an aerospace wear-resistant transmission gear near-net forming manufacturing method which comprises the following steps: S1, upsetting: firstly, a blank is longitudinally placed for upsetting, and then the blank is upset again after being turned around; s2, die forging; s3, correction is carried out; s4, annealing is conducted; according to the near-net forming manufacturing method, raw material consumption can be effectively reduced, the machining cost is reduced, the size allowance of the machined transmission gear is smaller than or equal to 1 mm, and the mechanical performance is stable.

Description

Technical Field

[0001] The invention relates to the technical field of aerospace component manufacturing, and in particular to a near-net-shape manufacturing method for aerospace wear-resistant transmission gears. Background Art

[0002] Transmission gears are widely used in mechanical devices in various industries, such as automobiles, aerospace, machinery manufacturing, metallurgy, mining and other fields. In the automotive industry, transmission gears are used in engines, transmissions, differentials and other components to achieve the matching of different speeds and torques and provide power output. In the aerospace field, transmission gears are used in important parts such as aircraft landing gears and engine transmission systems to ensure the safe and stable operation of aircraft.

[0003] Powder metallurgy high-speed steel is currently being widely used in the field of aerospace transmission parts due to its excellent wear resistance. However, due to the limitations of its forming process, most parts are directly processed from bars. The raw material consumption, production cost, time and equipment consumption in the machining process are huge. Therefore, the design of this near-net-shape manufacturing method can effectively reduce raw material consumption and reduce machining costs. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a near-net-shape manufacturing method for wear-resistant transmission gears for aerospace.

[0005] A near-net-shape manufacturing method for wear-resistant transmission gears for aerospace, comprising the following steps:

[0006] S1. Upset forging:

[0007] The blank is heated to 1110-1130℃ as the initial forging temperature, and after keeping the temperature for 20-80min, the blank is subjected to upsetting: the blank is placed longitudinally for upsetting, and then the blank is turned around and upsetting again. The impact energy of the two upsettings is 40-60%, the deformation of the two upsettings is 25-35%, the final forging temperature is 900-1000℃, and gray cooling is performed after the upsetting is completed;

[0008] S2. Die forging:

[0009] The blank obtained in step S1 is heated to 1110-1130° C. as the initial forging temperature, and after keeping the temperature for 30-90 minutes, the blank is die forged, the striking energy is 40-60%, the deformation is 25-35%, the final forging temperature is 900-1000° C., and the blank is gray-cooled after the die forging is completed;

[0010] S3. Calibration:

[0011] The blank obtained in step S2 is heated to 890-910°C, kept warm for 8-20 minutes, and then calibrated with a striking energy of 10-30%, a deformation of 0-1.5%, and a final forging temperature of 850-910°C. After calibration, the blank is cooled;

[0012] S4, Annealing:

[0013] The blank obtained in step S3 is annealed to complete the near net shape.

[0014] Furthermore, before starting step S1, both ends of the blank are firstly rounded to R3, and then rough-machined to the end surface roughness of both ends ≤ Ra3.2.

[0015] Note: Chamfering to R3 can avoid stress concentration caused by right angles at both ends of the billet during the upset forging process. During upset forging, the billet is subjected to greater pressure. If the ends are right angles, stress will gather at the corners, which can easily cause the billet to crack. Reducing the roughness makes the two end surfaces smoother and smoother, which can better position and cooperate with the mold during upset forging. Accurate positioning can ensure the position accuracy of the billet in the mold.

[0016] Furthermore, after step S1 is completed and before step S2 is started, the blank is shot blasted and polished.

[0017] Description: Remove oil stains, dirt and residual coating on the surface of forgings by shot blasting and grinding; grind away defects such as cracks, pinch marks, folds, etc. on the surface of forgings, and pay attention to the smooth transition between the defective parts and the surrounding areas after grinding.

[0018] Furthermore, after step S2 is completed and before step S3 is started, the blank is trimmed, sandblasted, polished and shot blasted, and the residual burrs and overcutting amount of the blank after trimming are ≤0.3 mm.

[0019] Note: Remove grease, dirt, etc. from the surface of forgings. When the oxide scale is difficult to remove, perform shot blasting. Remove all cracks, delamination and folds on the machined surface of forgings by grinding, but ensure that the forgings have no less than 1 / 3 of the nominal machining allowance. Pits, notches, scars and scratches and wrinkles with a depth not exceeding the single-sided negative deviation on the non-machined surface of forgings are allowed to exist. Cracks, inclusions, wrinkles, oxide scale and other defects should be completely removed, and the single-sided minimum limit size of the forgings must be ensured.

[0020] Furthermore, after step S3 is completed and before step S4 is started, the blank is sandblasted, polished and sandblasted.

[0021] Note: Pits, notches, scars and scattered defects such as scratches and wrinkles with a depth not exceeding the single-sided negative deviation on the non-machined surface of the forging are allowed to exist. Cracks, inclusions, wrinkles, oxide scale and other defects should be completely removed to ensure the single-sided minimum limit size of the forging.

[0022] Furthermore, in step S4, the annealing treatment temperature is 860-880° C., and the holding time is 175-185 min.

[0023] Note: Under this annealing condition, the grain structure of the gear can be refined; high temperature accelerates the diffusion rate of metal atoms, making it easier to form new crystal nuclei, while inhibiting the growth of grains; annealing treatment can promote the diffusion of alloy elements more fully, making the chemical composition and structure inside the gear more uniform, thereby improving the consistency and stability of gear performance.

[0024] Furthermore, in steps S1, S2 and S3, the transfer time of transferring the blank obtained in each step to the next step after the ash cooling is completed is ≤10s.

[0025] Note: Limiting the transfer time prevents the blank from cooling down during the transfer process and oxidizing in the air, which can cause processing difficulties.

[0026] Furthermore, the shot blasting uses steel shots with a diameter of 0.6 mm.

[0027] Description: The hardness of the blank is relatively high. The above-mentioned steel shot can quickly remove impurities such as rust, scale, old coating, etc. on the surface of the blank, with high processing efficiency.

[0028] Furthermore, the method further includes immersing the blank after the S3 correction in a chemical milling liquid in stages to perform a rotational chemical milling process;

[0029] The blank comprises a circular tooth groove processing portion and a shaft portion connecting two ends of the tooth groove processing portion, wherein the tooth groove depth required to be processed on the side wall of the tooth groove processing portion is a,

[0030] The rotary milling processing method is:

[0031] The first stage: first, 1 / 3 to 1 / 2a of the diameter of the tooth groove processing part is used as the maximum immersion depth, the blank is immersed in the first chemical milling liquid, and the blank is rotated around its own axis at a speed of 20 to 25 r / min, the temperature is 60 to 70°C, the chemical milling rate is 0.05 to 0.06 mm / min, and the first chemical milling liquid includes hydrochloric acid and hydrofluoric acid in a mass ratio of 1:1 to 1.2;

[0032] The second stage: 2 / 3 to 3 / 4a of the diameter of the tooth groove processing part is used as the maximum immersion depth, the blank is immersed in the second milling liquid, the blank is rotated around its own axis at a speed of 10 to 15 r / min, the temperature is 25 to 35 ° C, the milling rate is 0.03 to 0.04 mm / min, and the second milling liquid includes hydrochloric acid, hydrofluoric acid and ammonium chloride in a mass ratio of 1:1.2:1.8 to 2.4;

[0033] The third stage: Finally, the blank is completely immersed in the third milling liquid, and the blank is rotated around its own axis at a speed of 15-20r / min, the temperature is 60-70°C, the milling rate is 0.01-0.02mm / min, and the third milling liquid includes hydrochloric acid, hydrofluoric acid and ammonium chloride in a mass ratio of 1:1:2.5-3;

[0034] The mass concentration of the hydrochloric acid is 8-10%, the mass concentration of the hydrofluoric acid is 2.5-4%, and the mass concentration of the ammonium chloride is 2-5%.

[0035] Description: Through phased milling treatment, different milling temperatures and rates in each stage help improve the surface quality of gear tooth grooves. At the higher temperature and milling rate in the first stage, a certain microscopic rough structure will be formed on the material surface; as it enters the second stage, the temperature and milling rate will also decrease, and this change can make the corrosion process of the material surface smoother; the ammonium chloride in the second milling fluid can also form some protective films on the material surface or change the morphology of the reaction products, thereby reducing surface defects. In the third stage, the temperature is increased again but the milling rate is reduced, which can perform the final fine treatment on the surface and make the tooth groove surface smoother.

[0036] Compared with the existing near-net-shape manufacturing method for transmission gears, the beneficial effects of the present invention are:

[0037] The near-net-shape manufacturing method designed in the present application can effectively reduce the consumption of raw materials and lower the machining cost. The transmission gear obtained by machining has a size margin of ≤1mm and stable mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a top view of the transmission gear processed by the present invention;

[0039] Figure 2 It is a side view of the transmission gear processed by the present invention. DETAILED DESCRIPTION

[0040] In order to further illustrate the method adopted by the present invention and the effect achieved, the technical solution of the present invention will be clearly and completely described in combination with experiments below.

[0041] Embodiment 1: A near-net-shape manufacturing method for wear-resistant transmission gears for aerospace, comprising the following steps:

[0042] S1. Upset forging:

[0043] First, the two ends of the HOP10V billet are rounded to R3, and then rough-machined to Φ40×160mm, with the end surface roughness of both ends being Ra3.2. Then, the billet is heated to 1120℃ as the initial forging temperature. After keeping the temperature for 50 minutes, the billet is subjected to upsetting: the billet is placed longitudinally for upsetting, and then the billet is turned around and upsetting again. The impact energy of the two upsettings is 50%, and the deformation of the two upsettings is 30%. The final forging temperature is 950℃, and the deformation of the upsetting is 30%. After the upsetting is completed, gray cooling is performed; then the billet is shot blasted and polished with φ0.6mm steel shot for 10 minutes;

[0044] S2. Die forging:

[0045] The blank obtained in step S1 is heated to 1120°C as the initial forging temperature, and after keeping the temperature for 60 minutes, the blank is die forged with an impact energy of 50%, a deformation of 30%, and a final forging temperature of 950°C. After die forging, the blank is cooled;

[0046] The blank is trimmed, sandblasted, polished and shot blasted. The residual burrs and overcut amount of the blank after trimming are 0.3 mm. Shot blasting uses φ0.6 mm steel shots for 10 minutes.

[0047] S3. Calibration:

[0048] The blank obtained in step S2 is heated to 900°C, kept at this temperature for 14 minutes, and then calibrated with a striking energy of 20%, a final forging temperature of 880°C, and a deformation of 1%. After the calibration is completed, the blank is ash cooled; and then the blank is sandblasted and polished;

[0049] In steps S1, S2 and S3, after the ash cooling is completed, the transfer time of transferring the blank obtained in each step to the next step is 10 seconds;

[0050] S4, Annealing:

[0051] The blank obtained in step S3 is annealed at a temperature of 870° C. for a holding time of 180 min, and the near-net-shape forming is completed.

[0052] Example 2: This example is different from Example 1 in that the blank is heated to 1110°C as the initial forging temperature, kept at that temperature for 20 minutes, and the final forging temperature is 900°C.

[0053] Example 3: This example is different from Example 1 in that the blank is heated to 1130°C as the initial forging temperature, kept at that temperature for 80 minutes, and the final forging temperature is 1000°C.

[0054] Example 4: This example is different from Example 1 in that the striking energy of the two top forgings is 40%, the striking energy of the die forging is 40%, the deformation of the two top forgings and one die forging is 25%, the corrected striking energy is 10%, and the corrected deformation is 0.2%.

[0055] Example 5: This example is different from Example 1 in that the striking energy of the two top forgings is 60%, the striking energy of the die forging is 60%, the deformation of the two top forgings and one die forging is 35%, the corrected striking energy is 30%, and the corrected deformation is 1.5%.

[0056] Example 6: This example is different from Example 1 in that the blank obtained in step S1 is heated to 1110°C as the initial forging temperature, kept at this temperature for 30 minutes, and the final forging temperature is 900°C.

[0057] Example 7: This example is different from Example 1 in that the blank obtained in step S1 is heated to 1130°C as the initial forging temperature, kept at this temperature for 90 minutes, and the final forging temperature is 1000°C.

[0058] Example 8: This example is different from Example 1 in that the billet obtained in step S2 is heated to 890°C and kept at this temperature for 8 minutes, and the final forging temperature is 850°C.

[0059] Example 9: This example is different from Example 1 in that the billet obtained in step S2 is heated to 910°C and kept warm for 20 minutes, and the final forging temperature is 910°C.

[0060] Example 10: This example is different from Example 1 in that the annealing temperature is 860°C and the holding time is 175 minutes.

[0061] Example 11: This example is different from Example 1 in that the annealing temperature is 880°C and the holding time is 185 minutes.

[0062] Embodiment 12: This embodiment differs from Embodiment 1 in that Figure 1 and Figure 2 As shown, it also includes immersing the blank after S3 correction in a chemical milling liquid in stages for rotational chemical milling treatment;

[0063] The blank comprises a circular tooth groove processing portion and a shaft portion connecting two ends of the tooth groove processing portion, wherein the tooth groove depth required to be processed on the side wall of the tooth groove processing portion is a, and a is 4 mm.

[0064] The rotary milling process is as follows:

[0065] The first stage: first, 5 / 12a of the diameter of the tooth groove processing part, i.e. 1.67mm, is used as the maximum immersion depth, the blank is immersed in the first milling liquid, the blank is rotated around its own axis at a speed of 22r / min, the temperature is 65℃, the milling rate is 0.055mm / min, and the first milling liquid includes hydrochloric acid and hydrofluoric acid in a mass ratio of 1:1.1;

[0066] The second stage: 17 / 24a of the diameter of the tooth groove processing part, i.e. 2.83mm, is taken as the maximum immersion depth, the blank is immersed in the second milling liquid, the blank is rotated around its own axis at a speed of 12r / min, the temperature is 30℃, the milling rate is 0.035mm / min, and the second milling liquid includes hydrochloric acid, hydrofluoric acid and ammonium chloride in a mass ratio of 1:1.2:2.1;

[0067] The third stage: Finally, the blank is completely immersed in the third milling liquid, and the blank is rotated around its own axis at a speed of 17r / min, the temperature is 65°C, and the milling rate is 0.015mm / min. The third milling liquid includes hydrochloric acid, hydrofluoric acid and ammonium chloride in a mass ratio of 1:1:2.8;

[0068] The mass concentration of the hydrochloric acid is 9%, the mass concentration of the hydrofluoric acid is 3%, and the mass concentration of the ammonium chloride is 4%.

[0069] Example 13: The difference between this example and Example 12 is that, in the first stage: first, 1 / 3a of the diameter of the tooth groove processing part is taken as the maximum immersion depth, the blank is immersed in the first milling liquid, the blank is rotated around its own axis at a speed of 20r / min, the temperature is 60°C, and the milling rate is 0.05mm / min; in the second stage: 2 / 3a of the diameter of the tooth groove processing part is taken as the maximum immersion depth, the blank is immersed in the second milling liquid, the blank is rotated around its own axis at a speed of 15r / min, the temperature is 25°C, and the milling rate is 0.03mm / min; in the third stage: finally, the blank is completely immersed in the third milling liquid, the blank is rotated around its own axis at a speed of 20r / min, the temperature is 60°C, and the milling rate is 0.01mm / min.

[0070] Example 14: The difference between this example and Example 12 is that, in the first stage: first, 1 / 2a of the diameter of the tooth groove processing part is taken as the maximum immersion depth, the blank is immersed in the first milling liquid, the blank is rotated around its own axis at a speed of 25r / min, the temperature is 70°C, and the milling rate is 0.06mm / min; in the second stage: 3 / 4a of the diameter of the tooth groove processing part is taken as the maximum immersion depth, the blank is immersed in the second milling liquid, the blank is rotated around its own axis at a speed of 10r / min, the temperature is 35°C, and the milling rate is 0.04mm / min; in the third stage: finally, the blank is completely immersed in the third milling liquid, the blank is rotated around its own axis at a speed of 15r / min, the temperature is 70°C, and the milling rate is 0.02mm / min.

[0071] Example 15: The difference between this example and Example 12 is that the first milling fluid includes hydrochloric acid and hydrofluoric acid in a mass ratio of 1:1, the second milling fluid includes hydrochloric acid, hydrofluoric acid and ammonium chloride in a mass ratio of 1:1.2:1.8, and the third milling fluid includes hydrochloric acid, hydrofluoric acid and ammonium chloride in a mass ratio of 1:1:2.5; the mass concentration of the hydrochloric acid is 8%, the mass concentration of the hydrofluoric acid is 2.5%, and the mass concentration of the ammonium chloride is 2%.

[0072] Example 16: The difference between this example and Example 12 is that the first milling fluid includes hydrochloric acid and hydrofluoric acid in a mass ratio of 1:1.2, the second milling fluid includes hydrochloric acid, hydrofluoric acid and ammonium chloride in a mass ratio of 1:1.2:2.4, and the third milling fluid includes hydrochloric acid, hydrofluoric acid and ammonium chloride in a mass ratio of 1:1:3; the mass concentration of the hydrochloric acid is 10%, the mass concentration of the hydrofluoric acid is 4%, and the mass concentration of the ammonium chloride is 5%.

[0073] Experimental Example: The description of this experimental example is based on the scheme described in Example 1, and is intended to illustrate the practical application effect of the present invention.

[0074] The tensile strength and hardness of the transmission gears obtained in each embodiment were tested, and the average value of three test results of each embodiment was taken as the final experimental result.

[0075] 1. Explore the influence of parameters of each step on the tensile strength and hardness of the transmission gear.

[0076] Table 1 Tensile strength and hardness of Examples 1 to 11

[0077]

[0078] It can be seen from the results in Table 1 that the parameters of top forging are too small or too large, the striking energy of each step is too small or too large, the temperature of die forging is too small or too large, the temperature of correction is too small or too large, and the parameters of annealing treatment are too small, which will reduce the tensile strength and hardness of the transmission gear. The annealing treatment in Example 11 has a high temperature and a long time, which improves the tensile strength but reduces the hardness compared with Example 1. Therefore, from an economic point of view, the parameter effect of Example 1 is relatively better.

[0079] 2. Explore the effect of chemical milling treatment on the hardness of transmission gears after correction.

[0080] Table 2 Hardness of Examples 12 to 16 and Comparative Examples 1 to 3

[0081]

[0082]

[0083] The difference between the comparative example 1 and the example 12 is that the blank is completely immersed in the corresponding chemical milling liquid at each stage;

[0084] The difference between Control Example 2 and Example 12 is that the components and mass concentrations of the chemical milling liquid in each stage are the same;

[0085] The difference between Control Example 3 and Example 12 is that the chemical milling rate in each stage is the same;

[0086] By comparing Examples 12 to 16 and Comparative Examples 1 to 3 with Example 1, it can be seen that the hardness of the gear subjected to chemical milling is further improved, but Comparative Examples 1 and 2 may cause excessive corrosion of the blank, and the surface quality of Comparative Example 3 is reduced, thus affecting the hardness. Therefore, the chemical milling rules of Examples 12 to 16 are helpful to improve the hardness of the transmission gear;

[0087] By comparing Examples 12 to 16, it can be seen that too small or too large changes in the chemical milling rate at each stage and too small or too large differences in the chemical milling liquid concentration at each stage will also reduce the improvement in the hardness of the transmission gear. Therefore, in comprehensive comparison, the parameter effect of Example 12 is relatively better.

Claims

1. A near-net-shape manufacturing method for wear-resistant transmission gears for aerospace, characterized in that: The following steps are involved: S1. Upset forging: The blank is heated to 1110-1130℃ as the initial forging temperature, and after keeping the temperature for 20-80min, the blank is subjected to upsetting: the blank is placed longitudinally for upsetting, and then the blank is turned around and upsetting again. The impact energy of the two upsettings is 40-60%, the deformation of the two upsettings is 25-35%, the final forging temperature is 900-1000℃, and gray cooling is performed after the upsetting is completed; S2. Die forging: The blank obtained in step S1 is heated to 1110-1130° C. as the initial forging temperature, and after keeping the temperature for 30-90 minutes, the blank is die forged, the striking energy is 40-60%, the deformation is 25-35%, the final forging temperature is 900-1000° C., and the blank is gray-cooled after the die forging is completed; S3. Calibration: The blank obtained in step S2 is heated to 890-910°C, kept warm for 8-20 minutes, and then calibrated with a striking energy of 10-30%, a deformation of 0-1.5%, and a final forging temperature of 850-910°C. After calibration, the blank is cooled; S4, Annealing: The blank obtained in step S3 is annealed to complete the near net shape.

2. A near-net-shape manufacturing method for wear-resistant transmission gears for aerospace according to claim 1, characterized in that: Before starting step S1, both ends of the blank are first rounded to R3, and then rough-machined to the end surface roughness of both ends ≤ Ra3.

2.

3. The near-net-shape manufacturing method for wear-resistant transmission gears for aerospace according to claim 1, characterized in that: After step S1 is completed and before step S2 is started, the blank is shot blasted and polished.

4. A near-net-shape manufacturing method for wear-resistant transmission gears for aerospace according to claim 3, characterized in that: After step S2 is completed and before step S3 is started, the blank is trimmed, sandblasted, polished and shot blasted, and the residual burrs and overcut amount of the blank after trimming are ≤0.3 mm.

5. A near-net-shape manufacturing method for wear-resistant transmission gears for aerospace according to claim 4, characterized in that: After step S3 is completed and before step S4 is started, the blank is sandblasted and polished.

6. A near-net-shape manufacturing method for wear-resistant transmission gears for aerospace according to claim 1, characterized in that: In step S4, the annealing treatment temperature is 860-880° C., and the holding time is 175-185 min.

7. A near-net-shape manufacturing method for wear-resistant transmission gears for aerospace according to claim 1, characterized in that: In steps S1, S2 and S3, after the ash cooling is completed, the transfer time of transferring the blank obtained in each step to the next step is ≤10s.

8. The near-net-shape manufacturing method for wear-resistant transmission gears for aerospace according to claim 1, characterized in that: The shot blasting adopts Steel shot.

9. A near-net-shape manufacturing method for wear-resistant transmission gears for aerospace use as claimed in claim 1, characterized in that: The process also includes immersing the blank after S3 correction in a chemical milling liquid in stages to perform a rotational chemical milling process; The blank comprises a circular tooth groove processing portion and a shaft portion connecting two ends of the tooth groove processing portion, wherein the tooth groove depth required to be processed on the side wall of the tooth groove processing portion is a, The rotary milling processing method is: The first stage: first, 1 / 3 to 1 / 2a of the diameter of the tooth groove processing part is used as the maximum immersion depth, the blank is immersed in the first chemical milling liquid, and the blank is rotated around its own axis at a speed of 20 to 25 r / min, the temperature is 60 to 70°C, the chemical milling rate is 0.05 to 0.06 mm / min, and the first chemical milling liquid includes hydrochloric acid and hydrofluoric acid in a mass ratio of 1:1 to 1.2; The second stage: 2 / 3 to 3 / 4a of the diameter of the tooth groove processing part is used as the maximum immersion depth, the blank is immersed in the second milling liquid, the blank is rotated around its own axis at a speed of 10 to 15 r / min, the temperature is 25 to 35 ° C, the milling rate is 0.03 to 0.04 mm / min, and the second milling liquid includes hydrochloric acid, hydrofluoric acid and ammonium chloride in a mass ratio of 1:1.2:1.8 to 2.4; The third stage: Finally, the blank is completely immersed in the third milling liquid, and the blank is rotated around its own axis at a speed of 15-20r / min, the temperature is 60-70°C, the milling rate is 0.01-0.02mm / min, and the third milling liquid includes hydrochloric acid, hydrofluoric acid and ammonium chloride in a mass ratio of 1:1:2.5-3; The mass concentration of the hydrochloric acid is 8-10%, the mass concentration of the hydrofluoric acid is 2.5-4%, and the mass concentration of the ammonium chloride is 2-5%.

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