Shot blasting method for fairing

Abstract

The invention belongs to the technical field of metal surface strengthening, and particularly relates to a shot blasting machining method for a fairing. According to the technical scheme, the shot blasting machining method for the fairing comprises the steps that a plurality of test pieces are prepared, clamps are simulated through a plurality of positions, the diameter, height and angle of the placed test pieces correspond to those of a fairing part, shot blasting is conducted on the test pieces, a saturation curve of each test piece is drawn, and on the premise that the shot blasting strength consistency is guaranteed, shot blasting time is shortened. Shot blasting parameters are determined; a fairing part is divided into a plurality of areas, through multiple shot blasting tests, a shot blasting coverage rate map is drawn, a shot blasting path and the nozzle moving speed and shot blasting time on the corresponding path are determined, and the uniformity of the shot blasting coverage rate of each area is guaranteed. According to the shot peening machining method for the fairing, the shot peening strength and the coverage rate can be prevented from being too high or too low, the shot peening strength consistency and the coverage rate uniformity of the fairing part are guaranteed, deformation of the part after shot peening is reduced, and the service life of the fairing part is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface strengthening, and in particular relates to a fairing shot peening method. Background Art

[0002] With the vigorous development of the aviation manufacturing industry, especially the increasingly high technical requirements for aircraft engine manufacturing, parts are also facing the dual pressure of reducing weight and extending service life. The use of reasonable surface treatment technology (shot peening) will effectively solve the above pressure problems. The fairing is a high-speed rotating part at the front end of the engine. It faces huge wind force and air corrosion during operation, and is prone to fatigue cracks and corrosion cracking. The fairing after strict and correct shot peening will greatly increase its service life and reduce the cost of maintenance and replacement of parts.

[0003] The aircraft engine fairing is made of aluminum alloy. In order to reduce the weight of the engine, the fairing wall thickness is only 1.1 mm. If the shot peening intensity is too high or the coverage is too high, plastic deformation will occur after shot peening. If the intensity is too low, the compressive stress after shot peening will be insufficient, and the external force will not be offset during flight. If the coverage is too low, the surface compressive stress will be uneven, which will cause stress concentration and premature cracks in the parts. The part is conical in shape, and the diameter size changes with the axial change of the part. Therefore, it is crucial to ensure the consistency of shot peening intensity and uniformity of coverage during the shot peening process. Summary of the invention

[0004] The present invention provides a fairing shot peening method, which can prevent the shot peening intensity and coverage from being too high or too low, ensure the consistency of the shot peening intensity and the uniformity of the coverage of the fairing parts, reduce the deformation of the parts after shot peening, and increase the service life of the fairing parts.

[0005] The technical solution of the present invention is as follows:

[0006] A fairing shot peening method comprises the following steps: preparing a plurality of test pieces, simulating fixtures at multiple positions, placing the test pieces at diameters, heights and angles corresponding to fairing parts, performing shot peening on the test pieces, drawing a saturation curve for each test piece, and determining shot peening parameters on the premise of ensuring shot peening intensity consistency; dividing the fairing parts into a plurality of regions, drawing a shot peening coverage diagram through multiple shot peening tests, determining a shot peening path and a nozzle moving speed and shot peening time on the corresponding path, and ensuring uniformity of shot peening coverage in each region.

[0007] Furthermore, in the fairing shot peening method, the characteristics of the fixture positioning surface and shielding the difficult-to-shot peening area are maintained within 1.52 mm compared with the original shape of the fairing part or the fixture contour.

[0008] Furthermore, in the fairing shot peening method, the saturation point of the saturation curve is guaranteed to be within the design requirement range, and the arc height value of the saturation point is close, thereby ensuring the consistency of the entire shot peening intensity.

[0009] Furthermore, in the fairing shot peening method, the shot peening coverage rate of each area is 100%-400%.

[0010] Furthermore, in the fairing shot peening method, the shot peening parameters are as follows: part outer surface: pressure (0.8±0.08) bar, flow rate (7±1.4 kg) / min; part inner surface: pressure (0.7±0.07) bar, flow rate (5±0.75) kg / min; part end surface: pressure (1±0.1) bar, flow rate (7±1.4) kg / min.

[0011] Furthermore, in the fairing shot peening processing method, the shot peening equipment performs shot peening medium screening and shot peening medium crushing inspection every 8 hours of operation; the shot peening medium satisfies that the 35# sieve fully passes, the 40# sieve has no more than 2% of the screened material, the 45# sieve has no more than 50% of the screened material, the 50# sieve has no less than 90% of the screened material, and the 80# sieve has no less than 98% of the screened material; in terms of shot peening medium crushing, under a binocular microscope with at least 20 times magnification and top lighting, the number of broken and deformed shots on an area of ​​6.35×6.35 square centimeters is no more than 32.

[0012] Furthermore, in the fairing shot peening method, the shot peening equipment is provided with a shot peening pressure and medium flow alarm shutdown function. If the actual parameter range is exceeded, the equipment will alarm and shut down, thereby ensuring the accuracy of the shot peening parameters in actual work, thereby ensuring the stability of the shot peening intensity, and preventing deformation of parts due to excessive strength or insufficient surface compressive stress of parts due to low strength, affecting the service life.

[0013] The beneficial effects of the present invention are as follows: the present invention can prevent the shot peening intensity and coverage from being too high or too low, ensure the consistency of the shot peening intensity and the uniformity of the coverage of the fairing parts, reduce the deformation of the parts after shot peening, and increase the service life of the fairing parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the parts diagram of the fairing;

[0015] Figure 2 It is a saturation curve diagram of a test piece;

[0016] Figure 3 It is a coverage map, including a coverage area division map and a coverage data table. DETAILED DESCRIPTION

[0017] A fairing shot peening method comprises the following steps:

[0018] ①Shot peening equipment functional stability test

[0019] Pressure and medium flow out-of-range alarm and shutdown function test: add "G102A0.7F5I10J15H5R5S30000" in the CNC program statement, where "I10" means that the equipment will alarm and shut down when the pressure exceeds 10%, and "J15" means that the equipment will alarm and shut down when the flow exceeds 15%. However, in actual work, the pressure and flow cannot exceed this value when the equipment is in good condition. Therefore, "I10" is adjusted to "I1" and "J15" is adjusted to "J1" in sequence. If the equipment is alarmed and shut down during operation, it proves that the equipment pressure and medium flow alarm functions are effective. This test is to ensure the stability of the pressure and medium flow of the equipment during operation.

[0020] ②Shot peening media screening test method:

[0021] a. Place the qualified sieve on the flat disc at the bottom of the vibrating screen.

[0022] b. Check the screen to make sure it is not damaged and clean.

[0023] c. Take a 100-gram representative sample of the projectiles. The medium in the equipment should be the projectiles ejected from the nozzle.

[0024] d. Select a group of sieves in order according to the size of the opening of the sieve mouth, with the larger opening on the top and the smaller opening on the bottom, and arrange them in sequence. The assembly is completed by the collection plate under the bottom sieve.

[0025] e. Place 100g of the pellet sample on the top sieve of the sieve shaker and cover it with a solid lid. Fix the sieve set firmly on the sieve shaker and place the flapping arm on the lid.

[0026] d. Turn on the power of the vibrating screen machine and set the screening time to 10 minutes.

[0027] e. Press the start button to start pellet screening.

[0028] f. After screening, remove the group of screens from the vibrating screen to ensure that the pellets in the screens do not fall out and the screens should be kept stacked as they are.

[0029] g. Take out the sieve with the largest opening (the top sieve) from the sieve group, gently knock the pellets in the sieve into a receiving container, use a soft brush to brush any material stuck to the bottom of the sieve and the edge of the frame into the next finer sieve, then turn the sieve upside down and use a brush to brush off any pellets that may be stuck in the filter opening on the back, weigh it on a scale or balance that can read 0.01g (the minimum range of the scale or balance is required to be 150g), and the measurement result must be retained to 0.1g and as close to 0.1g as possible.

[0030] h. Repeat the operation in item g for each sieve, and then analyze it to ensure that all the pellets on the 35# sieve pass through, the pellets on the 40# sieve do not exceed 2%, the pellets on the 45# sieve do not exceed 50%, the pellets on the 50# sieve do not exceed 90%, and the pellets on the 80# sieve do not exceed 98%. Qualified pellets can continue to be used, and unqualified pellets must be replaced as a whole. It is not allowed to change the proportion of unqualified pellets by adding new pellets for dilution.

[0031] i. Collect the pellets and the sum of the masses obtained shall not be less than 99% of the mass of the test part. If it is less than 99%, check the sieve and the container containing the pellets, and check for possible errors in weighing, whether the stacking of the sieves and the fit of the lid are tight during screening, etc. If the error still exists, repeat the test.

[0032] ③ Shot peening medium shape detection method:

[0033] a. Stick a layer of tape under the 6.35mm×6.35mm measuring tool.

[0034] b. Take the pellet sample from the nozzle and place it in the square frame of the measuring tool. Press it firmly with your hands. Then a layer of pellets will stick to the tape, and the tape will be covered with a layer of shot peening medium.

[0035] c. Place the measuring tool covered with media under a microscope with top lighting at least 20 times for observation. If the measuring tool frame is not fully covered with media, add representative media to the measuring tool and press it firmly until the measuring tool is fully covered with a layer of shot peening media. Observe it under the microscope again. If the number of unqualified media is not more than 32 pellets, it can continue to be used. If the media fails the inspection, it must be replaced as a whole. It is not allowed to change the proportion of unqualified pellets by adding new pellets for dilution.

[0036] ④Use the simulated test piece fixture to perform shot peening on the test piece, and draw a saturation curve for each position separately, such as Figure 2As shown, the arc height value of the saturation point (i.e., shot peening intensity) is within the required range of shot peening intensity, and the intensity of each position should be as close as possible to ensure the consistency of the shot peening intensity of the entire fairing part, thereby improving the service life of the parts. At this time, the determined shot peening parameters are frozen. In order to ensure the shot peening intensity of the parts during batch production, each batch of parts must be strength verified before shot peening. At least two test pieces are shot peened at the saturation point (one test piece is the pre-determined saturation point 1T, and the other is twice the saturation time 2T. The arc height value increased by 2T relative to 1T does not exceed 10% of the arc height value of 1T). After the test piece is verified to be qualified, the part is shot peened. After the part is shot peened, each test piece shot peening position continues to verify the shot peening intensity 1T. The strength verification value does not exceed the saturation point arc height value by 0.025 mm. The strength verification of the part before and after shot peening is qualified, which means that the shot peening intensity of the part is qualified.

[0037] ⑤ Shot peening coverage test: Figure 3 As shown, the fairing parts are divided into 10 areas, the shot peening time per unit time is set, and the coverage rate is tested once per unit time. The coverage rate value is recorded, and a coverage rate graph is drawn. The shot peening coverage rate test of the parts is carried out many times using the coverage rate graph. Finally, the shot peening path and the nozzle moving speed and shot peening time on the corresponding path are determined to ensure that the coverage rate value of each area of ​​the parts is close, improve the uniformity of the part coverage rate, and thus increase the service life of the parts. During the shot peening process, the parts cannot be subjected to external forces, because external forces will affect the surface compressive stress after shot peening.

[0038] ⑥ Parts coverage inspection: The outer surface of the fairing is inspected with a 20x ordinary magnifying glass. For shot peening surfaces that are difficult to reach by direct visual inspection, such as grooves, holes, bolt holes, etc., an endoscope with at least 20x magnification and lighting is used for inspection to ensure the accuracy of coverage inspection. Too high coverage will cause plastic deformation of parts after shot peening, and too low coverage will cause stress concentration on the surface of the parts, resulting in premature cracks or corrosion cracking.

[0039] ⑦The shot peening procedure is as follows:

[0040] %

[0041] O8542

[0042] G94G90G0Z300

[0043] A90B90

[0044] M121

[0045] (#101CYCLE OR TIME)

[0046] #101=8

[0047] (#103C AXIS ROT SPEED RPM)

[0048] #103=15

[0049] (#106NOZZLE MOTION SPEED)

[0050] #106=400

[0051] G102A1F7I10J10H5R5S30000

[0052] X900Y330

[0053] M119

[0054] M104

[0055] (C START UP)

[0056] #102=1

[0057] WHILE[#102LE#103]DO1

[0058] M03S#102

[0059] G04X1

[0060] #102=#102+1

[0061] END1

[0062] (STEADY TIME)

[0063] G04X30

[0064] X925

[0065] Z543

[0066] B45

[0067] #107=1

[0068] WHILE[#107LE#101]DO1

[0069] G01X1005F#106

[0070] X925

[0071] #107=#107+1

[0072] END1G0X680

[0073] B-45

[0074] #108=1WHILE[#108LE#101]DO1G01F#106X760X680

[0075] #108=#108+1

[0076] END1G0A0B-45

[0077] X1011Y413

[0078] #109=1WHILE[#109LE#101]DO1G01F#106X1091X1011

[0079] #109=#109+1

[0080] END1G0B45Y641

[0081] #1110=1

[0082] WHILE[#110LE#101]DO1G01F#106X1091X1011

[0083] #110=#110+1

[0084] END1G0A90B90

[0085] M120Z350

[0086] (C GOES DOWN)

[0087] #102=#102-1

[0088] WHILE[#102GE0]DO1M03S#102

[0089] G04X1

[0090] #102=#102-1

[0091] END1M05M105M30%

[0092] 。

Claims

1. A fairing shot peening method, characterized in that: Prepare multiple test pieces, simulate fixtures at multiple positions, place the test pieces at diameters, heights and angles corresponding to those of the fairing parts, perform shot peening on the test pieces, draw a saturation curve for each test piece, and determine shot peening parameters while ensuring consistency in shot peening intensity; divide the fairing parts into multiple areas, draw a shot peening coverage diagram through multiple shot peening tests, determine the shot peening path and the nozzle movement speed and shot peening time on the corresponding path, and ensure uniformity in shot peening coverage in each area.

2. The fairing shot peening method according to claim 1, characterized in that: The fixture locating surfaces and masking characteristics of hard-to-peen areas are maintained within 1.52 mm of the original fairing part profile or the fixture contour.

3. The shot peening method of the fairing according to claim 1, characterized in that: The saturation point of the saturation curve is guaranteed to be within the design requirements, and the arc height value of the saturation point is close, so as to ensure the consistency of the entire shot peening intensity.

4. The shot peening method of the fairing according to claim 1, characterized in that: Each area has a shot peening coverage of 100%-400%.

5. The fairing shot peening method according to claim 1, characterized in that: Shot peening parameters are as follows: part outer surface: pressure (0.8±0.08) bar, flow rate (7±1.4 kg) / min; part inner surface: pressure (0.7±0.07) bar, flow rate (5±0.75) kg / min; part end surface: pressure (1±0.1) bar, flow rate (7±1.4) kg / min.

6. The fairing shot peening method according to claim 1, characterized in that: For every 8 hours of working time of the shot peening equipment, the screening and crushing of the shot peening media shall be tested; the shot peening media shall meet the requirements that all the 35# sieve passes through, the material on the 40# sieve is not more than 2%, the cumulative material on the 45# sieve is not more than 50%, the cumulative material on the 50# sieve is not less than 90%, and the cumulative material on the 80# sieve is not less than 98%; for the crushing of the shot peening media, under a binocular microscope with at least 20 times of magnification and top lighting, the number of broken and deformed projectiles on an area of ​​6.35×6.35 square centimeters shall not exceed 32.

7. The fairing shot peening method according to claim 1, characterized in that: The shot peening equipment is equipped with a shot peening pressure and medium flow alarm and shutdown function. If the actual parameter range is exceeded, the equipment will alarm and shut down to ensure the accuracy of the shot peening parameters in actual work, thereby ensuring the stability of the shot peening intensity and preventing deformation of parts due to excessive strength or insufficient surface compressive stress of parts due to low strength, affecting the service life.

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