Precision forging method for adjustable blade of aero-engine based on titanium alloy

Abstract

The invention provides a precision forging method for an adjustable blade of an aero-engine based on titanium alloy, which can realize precision forging forming of the blade of the titanium alloy aero-engine, enables the blade profile size of a blade forging to directly reach the size of a finished product, does not need to be machined again, is high in product percent of pass and good in air passage consistency, also can keep the continuity of a metal flow line, and is suitable for large-scale production. The mechanical property and the aerodynamic performance are high, and the surface integrity and the metallographic structure meet the design requirements. The method comprises the following steps of blanking, surface cleaning, glass lubricant spraying, heating blank making, surface cleaning, glass lubricant spraying and forging, and is characterized in that the forging procedure comprises heating upsetting, heating pre-forging and heating finish forging, and the surface cleaning and glass lubricant spraying are respectively carried out after each procedure of heating upsetting, heating pre-forging and heating finish forging.

Description

Technical Field

[0001] The invention relates to the field of blade forging, and in particular to a precision forging method for adjustable blades of an aero-engine based on titanium alloy. Background Art

[0002] Titanium alloy materials have excellent comprehensive properties, with a series of advantages such as low density, high specific strength, good toughness and weldability. Titanium alloy is mainly used in aircraft engines to manufacture fan and compressor discs, blades, casings and other parts, as well as various types of fasteners. Its usage in the aerospace industry exceeds 70%. Replacing structural steel with titanium alloy can reduce the weight of parts by about 30%. As one of the key parts of aircraft engines, compressor blades have complex structures, high precision, complex processing technology, and large quantities. Generally speaking, the processing workload of blades accounts for 30% to 40% of the entire engine processing workload. Compressor blades must have excellent metallurgical properties, precise dimensions, and excellent surface integrity. Therefore, compressor blade manufacturing technology is one of the most complex technologies in the manufacturing industry.

[0003] At present, the manufacture of titanium alloy aircraft engine adjustable blades mostly adopts ordinary die forging process, and the blade forgings after forging have machining allowances, especially the four edge plate air passages need to be removed by machining to obtain the finished blades. For the blade body profile of the blade forging, due to the complexity of the profile, the blade shape is easily deformed by machining to remove the allowance, and the profile cannot meet the blade design tolerance requirements after manual polishing, and the product qualification rate and consistency are poor. The machining profile will destroy the continuity of the metal streamline and the surface integrity of the finished blade, thereby reducing the mechanical properties of the finished blade. In addition, the four edge plates are milled and polished, which destroys the consistency of the air passages and reduces the aerodynamic performance of the blade. Summary of the invention

[0004] In view of the problem that the existing forging process for adjustable blades of titanium alloy aircraft engines is an ordinary die forging process, which requires machining to remove the machining allowance on the blade body surface, the product qualification rate and consistency are poor, and the machined surface will destroy the continuity of the metal streamline and the surface integrity of the finished blade. The four-edge plate is milled and polished, and the airway consistency is poor. The present invention provides a precision forging method for adjustable blades of aircraft engines based on titanium alloys. The method can realize the precision forging of titanium alloy aircraft engine blades, so that the blade size of the blade forging can directly reach the finished product size without further machining. The product qualification rate is high, the airway consistency is good, the continuity of the metal streamline can be retained, the mechanical properties and aerodynamic performance are high, and the surface integrity and metallographic structure meet the design requirements.

[0005] The technical scheme is as follows: it includes the following steps: blanking, surface cleaning, spraying glass lubricant, heating blanking, surface cleaning, spraying glass lubricant, forging, and is characterized in that: the forging process includes heated upset forging, heated pre-forging, and heated final forging, and surface cleaning and spraying glass lubricant are performed after each process of heated upset forging, heated pre-forging, and heated final forging.

[0006] It is further characterized by: In the heating upsetting, the blank obtained by spraying glass lubrication treatment is charged into a furnace for heating, the heating temperature is 30°C to 50°C at the material β phase transition temperature, and the temperature is kept until the extruded part is evenly heated; the evenly heated blank is quickly taken out from the furnace, put into the lower die of the upsetting die 1, and quickly struck to obtain the upsetting die 1, and quickly transferred to the upsetting die 2 to obtain the upsetting die 2, the aggregation ratio during upsetting is generally within 3.6, and the diameter size and total length of the small head of the upsetting die are measured after the upsetting die is cooled, and the surface quality is checked for defects; the glass lubricant and oxide scale remaining on the surface of the upsetting die are cleaned by a sandblasting process to improve the surface quality, and quartz sand or white corundum sand is generally used; after the surface of the workpiece is cleaned, the surface of the upsetting die is visually inspected, the parting burrs are removed by sand belt polishing, and the polishing wire is removed by a finishing process to improve the surface finish; then the surface of the upsetting die is sprayed with glass lubricant by a spraying process; The heated pre-forging is to heat the top forging piece in a furnace, wherein the heating temperature is 30°C to 50°C at the β phase transition temperature of the material, and the top forging piece is kept warm until the top forging piece is evenly heated; the evenly heated top forging piece is quickly taken out from the furnace, placed in the lower die of the pre-forging die, and quickly struck to obtain the pre-forging piece, wherein the deformation of the large and small heads during the pre-forging is 10% to 30%, and the deformation of the blade body is 40% to 70%. After the pre-forging piece is cooled, the blade body thickness dimension parameters are measured, and the surface quality is checked to be defect-free; then, the glass lubricant and oxide scale remaining on the surface of the top forging piece are cleaned by a sandblasting process to improve the surface quality, and generally quartz sand or white corundum sand is selected; after the surface of the workpiece is cleaned, the surface of the pre-forging piece is visually inspected, and pits and oxidation points are removed by polishing with a sand belt; and a finishing process is used to remove the polishing wire to improve the surface finish; then, the surface of the obtained top forging piece is sprayed with glass lubricant by a spraying process; The heating final forging comprises charging the pre-forging into a furnace for heating, wherein the heating temperature is 30°C to 50°C at the material β phase transition temperature, and keeping the temperature until the pre-forging is evenly heated; the evenly heated pre-forging is quickly taken out from the furnace, placed into the lower die of the final forging die, and quickly struck to obtain the final forging; during the final forging, the deformation of the large and small heads is 10% to 30%, and the deformation of the blade body is 30% to 50%. After the final forging is cooled, the dimensional parameters of the blade body and the inner edge plate are measured using a CMM to check whether the surface quality is defective; and the glass lubricant and oxide scale remaining on the surface of the final forging are cleaned; The specific steps of the four-edge plate precision forging method are as follows: Step 1: Cutting the titanium alloy bar stock according to the required part size. The bar stock diameter tolerance is controlled within ±0.2mm, and the bar stock weight is controlled within ±2g. Step 2: Surface cleaning: Use vibration finishing or centrifugal finishing to remove dirt and burrs on the surface of the bar and improve the surface finish; Step 3, spraying glass lubricant, using a spraying process to evenly spray the glass lubricant on the surface of the rod; Step 4, heating and blanking, charging the bar obtained in step 2 into a furnace for heating, the heating temperature is 30°C to 50°C at the material β phase transition temperature, and keeping the temperature until the bar is evenly heated; the evenly heated bar is quickly taken out of the furnace, put into blanking die 1, and quickly struck to obtain an extruded part, and quickly transferred to blanking die 2 to obtain a head part, and after the workpiece is cooled, the rod size and head height are measured, and the surface quality is checked for defects; Step 5: Surface cleaning: First, use the sandblasting process to remove the residual glass lubricant and oxide skin on the surface of the blank to improve the surface quality. Generally, quartz sand or white corundum sand is used. After the surface of the workpiece is cleaned, visually inspect the surface of the blank, and use abrasive belt polishing to remove the parting burrs. Step 6, spraying glass lubricant, using a spraying process to coat the surface of the blank obtained in step 5 with the glass lubricant; Step 7: Heating and upsetting; Step 8, heating pre-forging; Step 9, heating for final forging; Step 10: trimming. After trimming, the margin between the inlet and outlet edges of the final forged blade and the finished blade is 2mm to 3mm. Step 11, pre-milling, pre-milling the trimmed pieces obtained in step 10, and thinning the single-side thickness of the profile of the final forging by 0.08 mm to 0.15 mm; Step 12, vibration finishing, putting the workpiece obtained in step 11 into a finishing machine, mixing ceramic or brown corundum medium and finishing liquid to grind and remove defects on the workpiece surface; Step 13: Visual inspection: After the polished workpiece is pickled and cleaned, visually inspect the surface of the workpiece. If there are defects such as pits and pits that have not been removed, remove them by polishing with abrasive belts, fiber wheels, and polishing; Step 14, heat treatment, performing one or more heat treatments on the forging according to different titanium alloy materials. When multiple heat treatments are performed, the calibration process is set to be performed between the multiple heat treatments; Step 15: Thickness grouping: use an inductance meter to group the workpieces into thickness groups with different milling amounts; Step 16, chemical milling, chemical milling the final forging obtained in step 15, so that the profile thickness of the final forging meets the thickness requirement of the final finished blade; Step 17, torsion correction, using a precision forging blade correction wrench and a correction tool to correct the blade bending, torsion angle and edge plate size of the milled part obtained in step 21 at room temperature, so that the blade bending, torsion angle and edge plate size of the forging meet the required process requirements; Step 18: After the calibration is completed, the forging is de-stressed to remove the mechanical stress generated by the calibration; Step 19: Final inspection: In accordance with the final inspection requirements, the metallographic and mechanical properties of the blades are tested, and the surface quality, blade shape, profile size and inner side of the edge plate of the blades are checked one by one. Forgings that meet the requirements of the finished blade drawings are selected to complete the forging process.

[0007] The surface cleaning methods in step 2 and step 5 are one or more of sand blasting, polishing, vibration finishing, and acid corrosion.

[0008] In step 3 and step 6, the process of spraying the glass lubricant is as follows: placing the rod or workpiece into a heating box, heating the rod or workpiece to a temperature of 100° C. to 200° C. for a heating time of 30 to 120 min, then taking the rod or workpiece out of the heating box, and spraying the prepared glass lubricant solution evenly on the surface of the rod or workpiece using a spray gun, the spray gun being 25 cm to 40 cm away from the rod or pre-forging, the coating thickness being controlled to be 0.04 mm to 0.08 mm, checking that the surface coating color is uniform and there is no leakage of the original metal color, and placing the rod or workpiece in a ventilated place at room temperature for more than 1 hour after spraying to obtain a rod or workpiece whose glass lubricant thickness and surface meet the requirements.

[0009] In step 4, step 7, step 8 and step 9, the time from when the bar is taken out of the furnace and placed in the blank making die 1 to when the blank making die 2 is completed shall not exceed 10 seconds, the time from when the blank is taken out of the furnace and placed in the top forging die 1 to when the top forging die 2 is completed shall not exceed 10 seconds, the transfer time from when the top forging is taken out of the furnace and placed in the lower die of the pre-forging die shall not exceed 7 seconds, and the transfer time from when the pre-forging is taken out of the furnace and placed in the lower die of the final forging die shall not exceed 7 seconds; 13. Because the four edge plates of the adjustable blade are designed with undercuts of 0.1~3.2mm, when the undercut of a single edge plate of the lower die is less than 1.5mm, the die can be stably removed by adjusting the draft angle; however, when the double edge plates have undercuts and are greater than 1.5mm, it is necessary to use the bending of the blade shape through the design of the final forging die to rotate the angle of the small head cavity to ensure that only the single edge plate surface of the large head of the lower die has an undercut of less than 1.5mm. By adjusting the draft die of the rear edge plate of the large head, the small head can be removed from the cavity first and then the large head can be removed from the die.

[0010] In step 16, before chemical milling, the profile thickness of the final forging is quickly checked using an inductance meter and a thickness grouping measuring tool, and the final forgings are grouped according to the profile thickness difference of 0.02mm~0.05mm and the chemical milling removal of the edge plate air duct is taken into consideration. The grouped final forgings are then placed in chemical milling tank liquids with different corrosion rates for chemical milling, so that the profile thickness of the final forging and the edge plate air duct can meet the thickness requirements of the final finished blade.

[0011] In step 17, during calibration, the blade profile twist angle, bend and edge plate size of the forging are first detected using an inductance meter, and then the large and small head edge plates are calibrated using a calibration tool. Finally, the blade twist angle and bend are calibrated using a precision forged blade calibration wrench to meet the twist angle, bend and edge plate profile requirements of the final finished blade.

[0012] The beneficial effects of the present invention are: 1. The forging process of the titanium alloy aviation compressor adjustable blade of the present invention is different from the existing ordinary die forging process. Through the design of the main forming processes such as blank making, top forging, pre-forging and final forging, as well as the heat treatment, surface treatment, chemical milling and other steps after final forging, the precision forging of the blade is realized, so that the blade shape, blade body profile size, four edge plate surfaces and surface quality of the blade forging directly meet the drawing requirements of the finished blade. Firstly, it can better meet the high-precision design requirements of the blade shape, avoid the difficulties of traditional die forging CNC machining blade deformation and manual polishing profile that cannot meet the blade design tolerance requirements, better improve the process quality of high-performance compressor blades with three-dimensional design, and ensure the product qualification rate and consistency; Second, the blade profile and four edge plate surfaces can directly achieve the dimensional accuracy and surface roughness required by the part design drawings through precision forging, without the need for further machining, with higher material utilization and lower costs. The cost of raw materials alone can be reduced by about 30%; less machining allowance, higher machining efficiency, and more complete maintenance of the continuity of metal streamlines and improved aerodynamic performance; Third, precision forged blades have good profile surface integrity and better fatigue resistance, higher strength and load-bearing capacity, small blade vibration frequency deviation, good blade profile and airway consistency, improved fatigue life and aerodynamic performance of the blade, and can meet the high requirements of aircraft engines for blade performance and strength; 2. The present invention can obtain high-quality forgings with fine and uniform grains, obtain excellent organizational properties, and improve the qualified rate of finished forgings by strictly controlling the heating temperature, transfer time and deformation amount of blank making, upset forging, pre-forging and final forging; 3. The present invention applies glass lubricant four times in the whole process, which not only greatly reduces the friction resistance during forging, but also prevents oxidation of the forging blank, reduces the depletion of surface alloy elements during heating, and keeps the workpiece warm, so that the forging obtains stable and excellent organizational properties and surface quality; 4. The titanium alloy precision forged adjustable blades produced by the present invention have been tested for the surface quality of the blade forgings. The appearance is complete, without surface defects such as cracks, folds and scratches; after low-power organization inspection, the metal streamlines are continuous, and no obvious through-flow and serious eddy currents are found; after high-power organization inspection, the organization is uniform and meets the requirements of the specification atlas; the mechanical properties meet the use requirements; after three-coordinate dimensional inspection, the blade shape size and edge plate size meet the requirements of the drawings, and can be produced in batches stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a macrostructure and streamline distribution morphology diagram of a forging produced in Example 1 of the present invention; Figure 2 This is a high-magnification microstructure image of a forging produced in Example 1 of the present invention; Figure 3 The airfoil and flange dimension data of the forging produced in Example 1 of the present invention. DETAILED DESCRIPTION

[0014] A precision forging method for an adjustable blade of an aero-engine based on titanium alloy comprises the following steps: Step 1: Cutting: Use CNC lathe equipment and high-quality tools or high-speed circular saw machine and high-quality circular saw blades, select high-quality, qualified titanium alloy round bars, and cut the bars according to the required part size requirements. The diameter tolerance is controlled within ±0.2mm, and the weight of the cut parts is controlled within ±2g. The weight of the cut parts is controlled; Step 2: Surface cleaning: Use vibration finishing or centrifugal finishing to remove dirt and burrs on the surface of the bar, and clean the surface of the bar by the principle of chemical corrosion to remove residual stains on the surface and improve the surface finish; Step 3, spraying glass lubricant, using a spraying process to evenly spray the glass lubricant on the surface of the rod; Step 4, heating and blanking, charging the bar material in step 2 into the furnace for heating, the heating temperature is 30℃~50℃ under the material β phase transition temperature, the optimal temperature is 40℃, and the temperature is kept until the bar material is evenly heated; the converter temperature accuracy meets the GJB standard Class 3 furnace or AMS2750 standard Class 4 furnace, and the furnace temperature uniformity requirement is ±10℃; using a hydraulic flat forging machine, adjust the offset and mold closing height of the blanking mold 1 according to the size requirements of the blanking process 1, after the blanking mold 1 is adjusted in place, use pliers to quickly take out the evenly heated bar material from the converter hearth, put it into the blanking mold 1 and quickly strike it to obtain an extruded part, the transfer time does not exceed 5 seconds, and the extrusion ratio is within 11; then quickly transfer the extruded part to the blanking mold 2 to obtain a head part, and the transfer time does not exceed 5 seconds; after the workpiece is cooled, measure its rod size and head height, and check the surface quality for defects; Step 5: Surface cleaning: First, use the sandblasting process to remove the residual glass lubricant and oxide skin on the surface of the blank to improve the surface quality. Generally, quartz sand or white corundum sand is used. After the surface of the workpiece is cleaned, visually inspect the surface of the blank, and use abrasive belt polishing to remove the parting burrs. Step 6, spraying glass lubricant, coating the surface of the blank in step 6 with glass lubricant by a spraying process; Step 7, heating upsetting, charging the blank in step 6 into a furnace for heating, the heating temperature is 30℃~50℃ under the material β phase transition temperature, the optimal temperature is 40℃, the optimal β phase transition temperature is 40℃, and the temperature is kept until the extruded part is evenly heated; using a hydraulic flat forging machine, adjust the displacement and die closing height of the upsetting die 1 according to the size requirements of the upsetting 1 process, after the upsetting die 1 is adjusted in place, use pliers to quickly take out the evenly heated bar from the converter hearth, put it into the upsetting die 1 and quickly strike it to obtain the upsetting part 1, and the transfer time does not exceed 5 seconds; then quickly transfer the upsetting part 1 to the upsetting die 2 to obtain The transfer time of the top forging shall not exceed 5 seconds; the small head aggregation ratio during top forging is generally within 3.6. After the top forging is cooled, the diameter and total length of the small head are measured to check the surface quality. The glass lubricant and oxide scale remaining on the surface of the top forging are removed by sandblasting to improve the surface quality. Generally, quartz sand or white corundum sand is used. After the surface of the workpiece is cleaned, the surface of the top forging is visually inspected. The parting burrs are removed by sanding with abrasive belts, and the polishing process is used to remove the polishing wire to improve the surface finish. The surface of the top forging in step 8 is sprayed with glass lubricant by spraying. Step 8, heating pre-forging, the top forging in step 7 is charged into a furnace for heating, the heating temperature is 30°C~50°C at the material β phase transition temperature, the optimal temperature is 40°C, and the top forging is kept warm until the top forging is evenly heated; using an electric screw press, the evenly heated top forging is quickly taken out of the furnace and placed in the lower die of the pre-forging die, and the button of the electric screw press is quickly pressed to strike the pre-forging. During pre-forging, the deformation of the large and small heads is 10%~30%, the optimal deformation is 20%, the deformation of the blade body is 40%~70%, and the optimal blade body deformation is 55%, take the pre-forging out of the pre-forging die and after cooling, measure the blade thickness dimension parameters, and check the surface quality for defects; use the sand blasting process to clean the glass lubricant and oxide scale remaining on the surface of the top forging to improve the surface quality, generally using quartz sand or white corundum sand; after the workpiece surface is cleaned, visually inspect the surface of the pre-forging, and use abrasive belt polishing to remove pits and oxidation points; and use a finishing process to remove the polishing wire to improve the surface finish; use a spraying process to spray the surface of the top forging in step 11 with glass lubricant; Step 9, heating for final forging, the pre-forgings in step 8 are charged into a furnace for heating, the heating temperature is 30°C~50°C at the material β phase transition temperature, the optimal temperature of the material β phase transition is 40°C, and the pre-forgings are kept warm until the pre-forgings are evenly heated; using an electric screw press, the evenly heated pre-forgings are quickly taken out of the furnace and placed in the lower die of the final forging die and quickly struck to obtain the final forgings, the deformation of the large and small heads during final forging is 10%~30%, the optimal deformation is 20%, the deformation of the blade body is 30%~50%, and the optimal deformation is 40%, after the final forgings are cooled, the blade body and inner edge plate size parameters are measured using CMM, including the thickness of the profile, contour, torsion angle, bend, edge plate and other characteristic values, wherein the blade body profile thickness is 0.15mm~0.25mm on one side, and the optimal milling amount is 0.02mm, and the surface quality is checked for defects; the glass lubricant and oxide scale remaining on the surface of the final forgings are cleaned; Step 10: trimming. After trimming, the margin between the inlet and outlet edges of the final forged blade and the finished blade is 2mm~3mm, and the optimal margin is 2.5mm. Step 11, pre-milling, pre-milling the trimmed pieces in step 10, thinning the single-side thickness of the profile of the final forging by 0.08mm-0.15mm, and the optimal thinning amount of the single-side thickness of the profile is 0.115mm, so as to achieve the purpose of removing the oxidized hard α layer on the surface of the final forging; Step 12, vibration finishing, put the workpiece in step 11 into the finishing machine, mix the ceramic or brown corundum medium and the finishing liquid to grind and remove the defects on the surface of the workpiece, the finishing time is 2h~10h, the best time is 6h, the frequency is set to 40Hz~50Hz, the best frequency is 45Hz, after finishing, wash the parts with water to remove the finishing liquid remaining on the surface of the parts; Step 13: Visual inspection: After the polished workpiece is pickled and cleaned, visually inspect the surface of the workpiece. If there are defects such as pits and pits that have not been removed, remove them by polishing with abrasive belts, fiber wheels, and polishing; Step 14, heat treatment, performing one or more heat treatments on the forging according to different titanium alloy materials. When multiple heat treatments are performed, the calibration process is set to be performed between the multiple heat treatments; Step 15: Thickness grouping: use an inductance meter to group the workpieces into thickness groups with different milling amounts; Step 16, chemical milling. For the convenience of control, the surface thickness of the final forgings should be quickly checked by using an inductance meter and a thickness grouping tool. The thickness of the final forgings is grouped based on the difference of 0.02mm~0.05mm (the best surface thickness difference is 0.035mm) in profile thickness and the amount of chemical milling of the edge plate airway as the grouping basis. Then, the grouped final forgings are placed in chemical milling tanks with different corrosion rates for chemical milling, so that the surface thickness of the final forgings and the edge plate airway can meet the thickness requirements of the final finished blade. When the thickness of the forgings cannot meet the process requirements, the thickness grouping and chemical milling operations must be repeated until the surface thickness of the final forgings meets the process requirements. Step 17, calibration, at room temperature, first use the inductance meter to detect the blade torsion angle, bend and edge plate size of the forging, then use the calibration tool to calibrate the small head edge plate, and finally use the precision forging blade calibration wrench to calibrate the blade torsion angle and bend to meet the requirements of the final finished blade torsion angle, bend and edge plate profile, and after calibration, 100% of the measurement is performed on the inductance meter; Step 18: After the calibration is completed, the forging is de-stressed to remove the mechanical stress generated by the calibration; Step 19: Final inspection: In accordance with the final inspection requirements, the metallographic and mechanical properties of the blades are tested, and the surface quality, blade shape, profile size and inner side of the edge plate of the blades are checked one by one. Forgings that meet the requirements of the finished blade drawings are selected to complete the forging process.

[0015] After forging is completed, the qualified blades are transferred to machining, and machining processes such as milling, throwing in and out the exhaust edge, turning and milling the root crown, and fluorescent inspection are carried out to obtain the final finished blades.

[0016] The holding time t in the above steps 4, 7, 8 and 9 is calculated according to the following formula: t=0.5min / mm×H+1~2min, where H is the maximum thickness of the workpiece along the heat conduction direction, in mm.

[0017] The blanking die, top forging die, pre-forging die and final forging die all need to be preheated at a temperature of 190°C~230°C, and graphite lubricant needs to be sprayed on the die surface.

[0018] In the calibration process, the present invention uses an inductance meter for real-time measurement, which can quickly and accurately measure the bending and twist angle characteristic values ​​of the blade and the edge plate size, greatly improving the production efficiency of the precision forged blade. The forging method of the present invention is described in detail below with reference to specific embodiments.

[0019] Example 1 A forging process for an aero-engine blade based on a titanium alloy comprises the following steps: Step 1, blanking, titanium alloy material is selected from Ti-6Al-4V material, blanking bar diameter is Φ38.1±0.2mm, weight is 630±2g; Step 2: Surface cleaning, using centrifugal finishing and acid etching. When centrifugal finishing, put the rod into the finishing machine, the finishing time is 0.5 hours, the frequency is set to 50Hz, and the finishing abrasive medium is selected as brown corundum medium. After finishing, use water to clean the parts to remove the finishing liquid remaining on the surface of the parts; when acid etching, put the polished rod into the configured etching liquid according to the process requirements, clean the surface of the rod by the principle of chemical etching, remove the residual stains on the surface, and improve the surface finish of the rod. The acid etching process is a conventional process; Step 3, spraying glass lubricant, put the bar material in step 2 into a heating box, the heating temperature is 150°C, the heating time is 90 minutes, then take out the bar material from the heating box, use a spray gun to evenly spray the prepared glass lubricant solution on the surface of the bar material, the spray gun is 25cm away from the bar material, the coating thickness is controlled at 0.07mm, check that the surface coating color is uniform and there is no leakage of the original metal color, after spraying, place it in a ventilated place at room temperature for more than 1 hour, and obtain a bar material with glass lubricant thickness and surface that meet the requirements; Step 4, heating and blanking, the bar material in step 3 is loaded into the converter for heating, the heating temperature is 50°C at the material β phase transition temperature, the holding time is 20 min, the converter temperature accuracy meets the AMS2750 standard 4 type furnace, and the furnace temperature uniformity requirement is ±10°C; use hydraulic flat forging machine equipment, extrusion ratio 4.2, adjust the displacement of the extrusion die and the die closing height according to the size requirements of the extrusion process, after the extrusion die is adjusted in place, use pliers to quickly take out the evenly heated bar material from the converter and put it into the blanking die 1 installed on the hydraulic flat forging machine, quickly press the hydraulic press button to strike, the transfer time shall not exceed 5 seconds, and then quickly transfer the extruded part to the blanking die 2 to obtain the upsetting part, and the transfer time shall not exceed 5 seconds; after cooling, measure the rod size and head height of the extruded part, check the surface quality, and obtain the extruded part that meets the extrusion design requirements; Step 5, surface cleaning, using white corundum sand for 30 minutes, cleaning the surface of the blank to make it clean, so as to remove the oxide scale on the surface of the blank. After the surface of the workpiece is cleaned, visually inspect the surface of the blank, and use a sanding belt to polish and remove the parting burrs to improve the surface roughness of the blank; Step 6, spraying glass lubricant, putting the blank in step 5 into a heating box, heating temperature is 150°C, heating time is 90min, then taking out the blank from the heating box, spraying the prepared glass lubricant solution evenly on the surface of the rod with a spray gun, the spray gun is 25cm away from the rod, the coating thickness is controlled at 0.05mm, check that the surface coating color is uniform and there is no leakage of the original metal color, after spraying, place it in a ventilated place at room temperature for more than 1 hour, and obtain the blank with glass lubricant thickness and surface meeting the requirements; Step 7, heating forging, the blank in step 6 is charged into the furnace for heating, the heating temperature is 50℃ under the material β phase transition temperature, the holding time is 20 min, the converter temperature accuracy meets the AMS2750 standard 4 type furnace, and the furnace temperature uniformity requirement is ±10℃; use a hydraulic flat forging machine, adjust the displacement and die closing height of the forging die 1 according to the size requirements of the forging 1 process, after the forging die 1 is adjusted in place, use pliers to quickly take out the evenly heated bar from the converter hearth, put it into the forging die 1 and quickly strike it to obtain the forging 1, and the transfer time does not exceed 5 seconds; then quickly transfer the forging 1 to the forging die 2 to obtain the forging, and the transfer time does not exceed 5 seconds; during forging, the small head aggregation ratio is generally 3.4, and after the forging is cooled, the diameter and total length of the small head are measured to check the surface quality for defects; surface cleaning, using white corundum sand, the time is 30 minutes, the blank is The surface is cleaned to remove the oxide scale on the surface of the blank; after the surface of the workpiece is cleaned, the surface of the top forging is visually inspected, the parting burrs are removed by sanding and polishing, and the polishing wire is removed by a finishing process to improve the surface finish; spraying glass lubricant, the top forging in step 8 is placed in a heating box, the heating temperature is 150°C, the heating time is 90 minutes, and then the top forging is taken out of the heating box, and the prepared glass lubricant solution is sprayed evenly on the surface of the rod with a spray gun, the spray gun is 25cm away from the rod, and the coating thickness is controlled at 0.05mm. Check that the surface coating color is uniform and there is no leakage of the original metal color. After spraying, place it in a ventilated place at room temperature for more than 1 hour to obtain a top forging with glass lubricant thickness and surface that meet the requirements; Step 8, heating pre-forging, the top forging in step 9 is loaded into the converter for heating, the heating temperature is 50℃ under the material β phase transition temperature, the holding time is 20 min, the converter temperature accuracy meets the AMS2750 standard 4 type furnace, and the furnace temperature uniformity requirement is ±10℃; use the electric screw press equipment to debug the displacement and die closing height of the pre-forging die according to the size requirements of the pre-forging process. After the pre-forging die is debugged in place, the hot extruded top forging is quickly taken out of the converter and placed in the lower die of the pre-forging die installed on the electric screw press. The transfer time shall not exceed 7 seconds. Quickly press the button of the electric screw press to strike to obtain the pre-forging. During pre-forging, the deformation of the blade root is 16%, and the deformation of the blade body is 65%. Take the pre-forging out of the pre-forging die, measure the thickness of the section at the corresponding position of the blade body after cooling, check the surface quality, and obtain the pre-forging that meets the pre-forging design requirements; surface cleaning, use white corundum sand, time is 3 0min, clean the surface of the blank to make it clean, so as to remove the oxide scale on the surface of the blank; after the surface of the workpiece is cleaned, visually inspect the surface of the pre-forged part, and use abrasive belt polishing to remove pits and oxidation points; and use a finishing process to remove the polishing wire to improve the surface finish; spray glass lubricant, put the pre-forged part in step 8 into a heating box, the heating temperature is 120℃, the heating time is 90min, and then take out the pre-forged part from the heating box, and use a spray gun to evenly spray the prepared glass lubricant solution on the surface of the pre-forged part, the spray gun is 25cm away from the pre-forged part, and the coating thickness is controlled at 0.04mm. Check that the surface coating color is uniform and there is no leakage of the original metal color. After spraying, place it in a ventilated place at room temperature for more than 1 hour to obtain a pre-forged part with glass lubricant thickness and surface that meet the requirements; Step 9, heating for final forging, the pre-forged parts in step 8 are loaded into the converter for heating, the heating temperature is 50℃ under the material β phase transition temperature, the holding time is 15min, the converter temperature accuracy meets the AMS2750 standard 4 type furnace, and the furnace temperature uniformity requirement is ±10℃; use the electric screw press equipment, adjust the displacement and die closing height of the final forging die according to the size requirements of the final forging process, after the final forging die is adjusted in place, the evenly heated pre-forged parts are quickly taken out of the converter and placed in the positioning boss of the lower die of the final forging die installed on the electric screw press, the transfer time shall not exceed 7 seconds, and the button of the electric screw press is quickly pressed to strike to obtain the final forging parts, and the deformation of the blade root during final forging is 15% The deformation of the blade body is 44%. First, the small head is taken out of the mold cavity and then the large head is removed from the mold (the edge plate of this product is undercut to 3.2mm. After the small head is turned by the blade bending, the undercut of the large head lower mold is designed to be 1.4mm). The blade body profile size parameters of the final forging are measured using a three-coordinate measuring machine, including the thickness of the profile, contour, torsion angle, bending and other characteristic values. The blade body profile thickness is left with a milling amount of 0.20mm on one side. The surface quality is checked for defects such as folding, stretching, cracks, and incompleteness, and the final forging that meets the final forging design requirements is obtained; surface cleaning, using white corundum sand for 30 minutes, the surface of the blank is cleaned to make it clean, so as to remove the oxide scale on the surface of the blank; Step 10: trimming: use a laser trimming machine that meets the power requirements to trim the final forging according to the trimming process requirements of the final forging. After trimming, the margin between the inlet and exhaust edges of the blade body and the finished blade is 3 mm. Check to obtain the final forging that meets the requirements after trimming. Step 11, pre-milling, pre-milling the final forging in step 10, and put it into the configured pre-milling slot liquid according to the process requirements, and control the corrosion rate of the slot liquid to reduce the single-side thickness of the profile of the final forging by 0.10 mm, so as to achieve the purpose of removing the oxidized hard α layer on the surface of the final forging; Step 12, vibration finishing, put the final forging into the vibration finishing machine, the finishing time is 10 hours, the frequency is set to 40Hz, the finishing abrasive medium is selected as brown corundum medium, and the parts are washed with water after finishing to remove the finishing liquid remaining on the surface of the parts; Step 13: Visual inspection: After the polished workpiece is pickled and cleaned, visually inspect the surface of the workpiece. If there are defects such as pits and pits that have not been removed, remove them by polishing with abrasive belts, fiber wheels, and polishing; Step 14, annealing treatment, placing the final forging into a vacuum heat treatment furnace, heating to 700±10°C, holding time 120min, cooling to below 60°C with argon gas, and then air cooling to room temperature; Step 15, thickness grouping, use an inductance meter to group the workpieces by thickness, and divide them into groups with different milling amounts based on the difference of 0.02mm~0.05mm in profile thickness; Step 16, chemical milling. For the convenience of control, the surface thickness of the final forgings should be quickly checked by using an inductance meter and a thickness grouping tool. The thickness of the final forgings is grouped based on the difference of 0.02mm~0.05mm in the surface thickness and the amount of chemical milling of the edge plate airway. The grouped final forgings are then placed in chemical milling tanks with different corrosion rates for chemical milling, so that the surface thickness of the final forgings and the edge plate airway can meet the thickness requirements of the final finished blade. When the thickness of the forgings cannot meet the process requirements, the thickness grouping and chemical milling operations must be repeated until the surface thickness of the final forgings meets the process requirements. Step 17, calibration, at room temperature, first use the inductance meter to detect the blade torsion angle, bend and edge plate size of the forging, then use the calibration tool to calibrate the small head edge plate, and finally use the precision forging blade calibration wrench to calibrate the blade torsion angle and bend to meet the requirements of the final finished blade torsion angle, bend and edge plate profile, and after calibration, 100% of the measurement is performed on the inductance meter; Step 18, vacuum stress relief, placing the final forging in a vacuum heat treatment furnace, heating to 500±10°C, holding time 240min, cooling to below 60°C with argon gas, and then air cooling to room temperature; Step 19: Final inspection: Use a 10x magnifying glass to conduct 100% inspection on the forgings to check if there are any visual defects such as cracks, folds, scratches, dents, pits, etc. on the surface of the forgings. Check that the forging edge plate, bend, torsion angle, contour, thickness and other dimensions meet the requirements of the finished blade drawing to complete the forging process.

[0020] In this embodiment, the above process steps are used to successfully produce the first-stage adjustable blade forgings of the aircraft engine compressor made of Ti-6Al-4V material. After 100% visual inspection, the forgings have a complete appearance and no defects such as cracks and folding machine crushing on the surface. Forgings and mechanical property test bars are randomly selected for metallographic structure and mechanical property testing, and the results are as follows: Macrostructure and streamline distribution morphology are shown in Figure 1 There are no defects such as cracks, voids, stratification, segregation bright bands, metal and non-metal inclusions on the surface. The metal streamlines are continuous, without through-flow and severe eddy currents.

[0021] High magnification tissue morphology Figure 2 Its high-magnification microstructure morphology is qualified, the grains are uniform, there is no elongated and continuous α layer, and it meets the customer's forging specifications.

[0022] For forging blade and flange dimensions see Figure 3 The dimensions of the edge plate, bend, twist angle, profile, thickness, etc. meet the requirements of the finished blade drawing.

[0023] The mechanical properties are shown in Table 1, which are significantly better than the design requirements.

[0024]

[0025] The titanium alloy blade produced by the present invention has blade size, surface integrity, mechanical properties and metallographic structure that fully meet the design requirements of aircraft engine compressor blades.

Claims

1. A precision forging method for an adjustable blade of an aero-engine based on titanium alloy, comprising the following steps: Blanking, surface cleaning, spraying glass lubricant, heating blanking, surface cleaning, spraying glass lubricant, forging, characterized in that: the forging process includes heated upset forging, heated pre-forging, and heated final forging, and surface cleaning and spraying glass lubricant are performed after each process of heated upset forging, heated pre-forging, and heated final forging.

2. The precision forging method for adjustable blades of an aircraft engine based on titanium alloy according to claim 1, characterized in that: In the heating upsetting, the blank obtained by spraying glass lubrication treatment is charged into a furnace for heating, the heating temperature is 30°C to 50°C under the material β phase transition temperature, and the temperature is kept until the extruded part is evenly heated; the evenly heated blank is quickly taken out from the furnace, put into the lower die of the upsetting die 1, and quickly struck to obtain the upsetting die 1, and quickly transferred to the upsetting die 2 to obtain the upsetting die 2, the aggregation ratio during upsetting is generally within 3.6, and the diameter size and total length of the small head of the upsetting die are measured after the upsetting die is cooled, and the surface quality is checked for defects; the glass lubricant and oxide scale remaining on the surface of the upsetting die are cleaned by a sand blowing process to improve the surface quality, and quartz sand or white corundum sand is generally used; after the surface of the workpiece is cleaned, the surface of the upsetting die is visually inspected, the parting burrs are removed by sand belt polishing, and the polishing wire is removed by a finishing process to improve the surface finish; then the surface of the upsetting die is sprayed with glass lubricant by a spraying process.

3. The precision forging method for adjustable blades of an aircraft engine based on titanium alloy according to claim 2, characterized in that: The heated pre-forging comprises charging the top forging into a furnace for heating, wherein the heating temperature is 30°C to 50°C at the β phase transition temperature of the material, and keeping the temperature until the top forging is evenly heated; the evenly heated top forging is quickly taken out from the furnace, placed in the lower die of the pre-forging die, and quickly struck to obtain the pre-forging; during the pre-forging, the deformation of the large and small heads is 10% to 30%, and the deformation of the blade body is 40% to 70%. After the pre-forging is cooled, the blade body thickness dimension parameters are measured, and the surface quality is checked for defects; then the glass lubricant and oxide scale remaining on the surface of the top forging are cleaned by a sand blowing process to improve the surface quality, and generally quartz sand or white corundum sand is selected; after the surface of the workpiece is cleaned, the surface of the pre-forging is visually inspected, and pits and oxidation points are removed by polishing with a sand belt; and a finishing process is used to remove the polishing wire to improve the surface finish; and then the surface of the obtained top forging is sprayed with glass lubricant by a spraying process.

4. The precision forging method for adjustable blades of an aircraft engine based on titanium alloy according to claim 3 is characterized in that: The heating final forging comprises charging the pre-forging into a furnace for heating at a temperature of 30°C to 50°C under the material β phase transition temperature, and keeping the temperature until the pre-forging is evenly heated; quickly taking out the evenly heated pre-forging from the furnace, placing it into a lower die of a final forging die, and quickly striking it to obtain a final forging; during the final forging, the deformation of the large and small heads is 10% to 30%, and the deformation of the blade body is 30% to 50%. After the final forging is cooled, the dimensional parameters of the blade body and the inner edge plate are measured using three coordinates to check whether the surface quality is defective; and the glass lubricant and oxide scale remaining on the surface of the final forging are cleaned.

5. According to the method for precision forging of adjustable blades of aircraft engines based on titanium alloy as described in claim 4, its characteristics are In: The specific steps are as follows: Step 1: Cutting the titanium alloy bar stock according to the required part size. The bar stock diameter tolerance is controlled within ±0.2mm, and the bar stock weight is controlled within ±2g. Step 2: Surface cleaning: Use vibration finishing or centrifugal finishing to remove dirt and burrs on the surface of the bar and improve the surface finish; Step 3, spraying glass lubricant, using a spraying process to evenly spray the glass lubricant on the surface of the rod; Step 4, heating and blanking, charging the bar obtained in step 2 into a furnace for heating, the heating temperature is 30°C to 50°C at the material β phase transition temperature, and keeping the temperature until the bar is evenly heated; the evenly heated bar is quickly taken out of the furnace, put into blanking die 1, and quickly struck to obtain an extruded part, and quickly transferred to blanking die 2 to obtain a head part, and after the workpiece is cooled, the rod size and head height are measured, and the surface quality is checked to be defect-free; Step 5: Surface cleaning: First, use the sandblasting process to remove the residual glass lubricant and oxide scale on the surface of the blank to improve the surface quality. Generally, quartz sand or white corundum sand is used. After the surface of the workpiece is cleaned, visually inspect the surface of the blank, and use abrasive belt polishing to remove the parting burrs. Step 6, spraying glass lubricant, coating the surface of the blank obtained in step 5 with glass lubricant by a spraying process; Step 7: Heating and upsetting; Step 8, heating pre-forging; Step 9, heating for final forging; Step 10: trimming. After trimming, the margin between the inlet and outlet edges of the final forged blade and the finished blade is 2mm to 3mm. Step 11, pre-milling, pre-milling the trimmed pieces obtained in step 10, and thinning the single-side thickness of the profile of the final forging by 0.08 mm to 0.15 mm; Step 12, vibration finishing, putting the workpiece obtained in step 11 into a finishing machine, mixing ceramic or brown corundum medium and finishing liquid to grind and remove defects on the workpiece surface; Step 13: Visual inspection: After the polished workpiece is pickled and cleaned, visually inspect the surface of the workpiece. If there are defects such as pits and pits that have not been removed, remove them by polishing with abrasive belts, fiber wheels, and polishing; Step 14, heat treatment, performing one or more heat treatments on the forging according to different titanium alloy materials. When multiple heat treatments are performed, the calibration process is set to be performed between the multiple heat treatments; Step 15: Thickness grouping: Use an inductance meter to group the workpieces by thickness and divide them into groups with different milling amounts; Step 16, chemical milling, chemical milling the final forging obtained in step 15, so that the profile thickness of the final forging meets the thickness requirement of the final finished blade; Step 17, torsion correction, using a precision forging blade correction wrench and a correction tool to correct the blade curvature, torsion angle and edge plate size of the milled part obtained in step 16 at room temperature, so that the blade curvature, torsion angle and edge plate size of the forging meet the required process requirements; Step 18: After the calibration is completed, the forging is de-stressed to remove the mechanical stress generated by the calibration; Step 19: Final inspection: In accordance with the final inspection requirements, the metallographic and mechanical properties of the blades are tested, and the surface quality, blade shape, profile size and inner side of the edge plate of the blades are checked one by one. Forgings that meet the requirements of the finished blade drawings are selected to complete the forging process.

6. The precision forging method for adjustable blades of an aircraft engine based on titanium alloy according to claim 5, characterized in that: The surface cleaning methods in step 2 and step 5 are one or more of sand blasting, polishing, vibration finishing, and acid corrosion.

7. The precision forging method for adjustable blades of an aircraft engine based on titanium alloy according to claim 4, characterized in that: In step 3 and step 6, the process of spraying the glass lubricant is as follows: placing the rod or workpiece into a heating box, heating the rod or workpiece to a temperature of 100° C. to 200° C. for a heating time of 30 to 120 min, then taking the rod or workpiece out of the heating box, and spraying the prepared glass lubricant solution evenly on the surface of the rod or workpiece using a spray gun, the spray gun being 25 cm to 40 cm away from the rod or pre-forging, the coating thickness being controlled to be 0.04 mm to 0.08 mm, checking that the surface coating color is uniform and there is no leakage of the original metal color, and placing the rod or workpiece in a ventilated place at room temperature for more than 1 hour after spraying to obtain a rod or workpiece whose glass lubricant thickness and surface meet the requirements.

8. The precision forging method for adjustable blades of an aircraft engine based on titanium alloy according to claim 5, characterized in that: In step 4, step 7, step 8 and step 9, the time from when the bar is taken out of the furnace and placed in the blank making die 1 to when the blank making die 2 is completed shall not exceed 10 seconds, the time from when the blank is taken out of the furnace and placed in the top forging die 1 to when the top forging die 2 is completed shall not exceed 10 seconds, the transfer time from when the top forging is taken out of the furnace and placed in the lower die of the pre-forging die shall not exceed 7 seconds, and the transfer time from when the pre-forging is taken out of the furnace and placed in the lower die of the final forging die shall not exceed 7 seconds; in step 13 Because the four edge plates of the adjustable blade are designed with undercuts of 0.1~3.2mm, when the undercut of a single edge plate of the lower die is less than 1.5mm, the die can be stably removed by adjusting the draft angle; however, when the double edge plates have undercuts and are greater than 1.5mm, it is necessary to use the bending of the blade shape through the design of the final forging die to rotate the angle of the small head cavity to ensure that only the single edge plate surface of the large head of the lower die has an undercut of less than 1.5mm. By adjusting the draft die of the rear edge plate of the large head, the small head is first removed from the cavity and then the large head is removed from the die.

9. The precision forging method for adjustable blades of an aircraft engine based on titanium alloy according to claim 5, characterized in that: In step 16, before chemical milling, the profile thickness of the final forging is quickly checked using an inductance meter and a thickness grouping measuring tool, and the final forgings are grouped according to the profile thickness difference of 0.02mm~0.05mm and the chemical milling removal of the edge plate air duct is taken into consideration. The grouped final forgings are then placed in chemical milling tank liquids with different corrosion rates for chemical milling, so that the profile thickness of the final forging and the edge plate air duct can meet the thickness requirements of the final finished blade.

10. The precision forging method for adjustable blades of an aircraft engine based on titanium alloy according to claim 5, characterized in that: In step 17, during calibration, the blade profile twist angle, bend and edge plate size of the forging are first detected using an inductance meter, and then the large and small head edge plates are calibrated using a calibration tool. Finally, the blade twist angle and bend are calibrated using a precision forged blade calibration wrench to meet the twist angle, bend and edge plate profile requirements of the final finished blade.

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