Machining method for titanium alloy special-shaped part of aero-engine

Abstract

The invention relates to the technical field of aero-engine part machining, in particular to a machining method of an aero-engine titanium alloy special-shaped part, which comprises the following steps: step S1, manufacturing a blank, dividing the blank into two symmetrical parts along a long axis according to the titanium alloy special-shaped part, unfolding the two symmetrical parts, performing single-side margin-reserved blanking, and performing rounding to obtain a blank before hot forming; s2, coating a protective coating, namely brushing boron nitride protective paint on two surfaces of the blank, brushing boron nitride protective paint on a forming male die and a forming female die of the die, and naturally drying at normal temperature; s3, hot forming is conducted, specifically, a mold is heated to a set value along with equipment, the blank is put into the mold to be subjected to hot forming, a semi-finished product blank which is separated along the long axis and provided with reinforcing ribs is obtained, and the profile and size precision of the semi-finished product blank are guaranteed; s4, the protective coating is cleaned, boron nitride on the surface of the semi-finished blank is wiped with a scouring pad in clear water, and no stain is left; s5, the appearance is cut, the part is positioned and aligned through reinforcing ribs, the semi-finished product blank is cut, and a halved part is obtained; s6, removing an oxide layer; and S7, the two halved parts are welded through laser welding, and the complete titanium alloy special-shaped part is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of aviation engine parts processing, and in particular to a processing method for aviation engine titanium alloy special-shaped parts. Background Art

[0002] Aircraft engines need to work for a long time and with high reliability under high temperature, high pressure, high speed and high load conditions. Figure 1 The figure shows the structure diagram of titanium alloy special-shaped parts on aircraft engines. It is made of TA15 sheet. TA15 is a difficult-to-process material with high tensile strength and yield limit, requiring a large impact force. Due to the low elastic modulus E value, the cold forming rebound is large and irregular; the elongation δ5 and the cross-sectional shrinkage ψ are both relatively low, which is not conducive to stamping. The material thickness is 2.5, and the forming difficulty is greater. The part is a variable-section special-shaped structure that changes from a "big belly" spline curve ellipse to a "small belly" spline curve ellipse in the axial direction. Two longitudinal welds are allowed along the generatrix, and there is a negative angle in the axial direction. The total height is 198mm, the major axis is transferred from 768.3mm to 837.5mm, and the minor axis is transferred from 540.5mm to 421.3mm. The size tolerance of the major and minor axes is 0.4, and the overall surface profile is 2. For this titanium alloy special-shaped part, superplastic forming has high requirements on the material grain, and it is difficult to ensure the mechanical properties of the material, and the processing cost is high. Therefore, it is necessary to propose a processing method for special-shaped titanium alloy parts of aircraft engines to meet the quality requirements of part shape and dimensional accuracy. Summary of the invention

[0003] The main purpose of the present invention is to provide a processing method for titanium alloy special-shaped parts of aircraft engines, aiming to solve the above technical problems.

[0004] To achieve the above object, the present invention provides a method for processing titanium alloy special-shaped parts of aircraft engines, the steps comprising:

[0005] Step S1: making a blank, dividing the blank into two symmetrical parts along the long axis according to the titanium alloy special-shaped part and unfolding them, leaving a margin on one side and then rounding them to serve as the blank before hot forming;

[0006] Step S2: applying a protective coating, brushing boron nitride protective coating on both sides of the blank, and brushing boron nitride protective coating on the forming convex and concave dies of the mold, and drying naturally at room temperature;

[0007] Step S3: hot forming, the mold is heated to a set value along with the equipment, the blank is placed in the mold for hot forming, and a semi-finished blank with reinforcing ribs separated along the long axis is obtained, and the surface and dimensional accuracy of the semi-finished blank are ensured;

[0008] Step S4: Clean the protective coating, wipe the boron nitride on the surface of the semi-finished blank with a scouring pad in clean water, and no stains remain;

[0009] Step S5: cutting the outer shape, positioning and aligning the parts with the reinforcement ribs, and cutting the semi-finished blank to obtain half parts;

[0010] Step S6: removing the oxide layer;

[0011] Step S7: The two halves are welded by laser welding to obtain a complete titanium alloy special-shaped part.

[0012] Preferably, in step S1, when making the blank, the titanium alloy special-shaped part is divided symmetrically along the long axis into two completely identical parts. After the parts are unfolded, a margin of 80-100 mm is added on one side along the long axis direction, and a margin of 50-80 mm is left on one side along the height direction of the parts to unfold the material in a fan shape.

[0013] Preferably, in step S1, the blank is in a semi-conical cylinder shape, and after the blank is cut to obtain a fan-shaped expanded material, a three-axis rolling machine is used to roll the fan-shaped expanded material into a semi-conical cylinder shape.

[0014] Preferably, in step S2, the boron nitride protective coating is a mixture of boron nitride powder and alcohol, and the solvent ratio is 1:1.

[0015] Preferably, when hot forming is performed in step S3, the mold material used is 1Cr18NiTi, the mold concave surface is 0.998 times the outer surface of the part, and the width extends along both sides of the mold; the punch is 0.998 times the inner surface of the part, and the width is consistent with that of the concave mold; the mold is heated to 750℃±10℃ with the equipment before the blank is loaded.

[0016] Preferably, the semi-finished blank is divided into two halves, each of which extends 60-70 mm upward and downward at both ends, and a reinforcing rib with a length of 150-200 mm is provided at a position extending 10-15 mm.

[0017] Preferably, the reinforcing rib is a groove-shaped structure with a width of 5 mm; in the step S5, a laser cutting machine is used for cutting, and the reinforcing rib is used for alignment and positioning during cutting.

[0018] Preferably, in step S3, the hot forming temperature is 750°C±10°C, the equipment pressure is 20-30T, and the heat preservation and pressure holding time is 15-18min.

[0019] Preferably, in step S6, when removing the oxide layer, sand blasting is first used to remove the thicker oxide layer on the surface of the half part, and then pickling is performed to accurately remove the oxide layer on the surface of the half part to ensure the surface roughness of the half part.

[0020] Preferably, in step S7, after welding, the gap between the two halves is required to be no greater than 0.2 mm, and the misalignment is no greater than 0.1 mm; before laser welding, the surface to be welded of the halves needs to be cleaned by pickling or polishing. The effective period of pickling is 120 hours, and the effective period of polishing is 8 hours. Before welding, the halves within the effective period need to be cleaned with alcohol or acetone, and no stains are allowed; before laser welding, argon gas protection is required, and the argon gas passing time is not less than 1 minute. The equipment uses a power of 3050-3100 W, a welding speed of 0.01-0.05 m / s, a defocus of 0-3 mm, a laser deflection angle of 0-5°, a frequency of 4-45 Hz, and a peak ratio of 50%.

[0021] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0022] (1) The processing method provided by the present invention adopts reasonable parting and scientific blank structure, realizes the accuracy of the semi-finished blank surface through reasonable process parameters, reasonable welding method and welding parameters, and greatly improves work efficiency and part quality.

[0023] (2) In the present invention, a hot pressing method with reinforcing ribs is used for half forming. The reinforcing ribs are used as the datum for the shape processing technology to ensure that the shape processing and forming of the part are coaxial, so as to achieve precise processing of the shape of the part. The processing method of first sandblasting and then pickling to remove the oxide layer on the surface of the hot forming is used to shorten the time for removing the oxide layer from 72 hours to 2 hours. The pulse welding of laser welding is used for welding to achieve small deformation welding in the atmosphere, so as to meet the quality requirements of the size and shape accuracy of the part, greatly improve the work efficiency, and reduce the processing cost of the part.

[0024] (3) The processing method has been used on site and has achieved the requirements of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0026] Figure 1 This is a schematic diagram of the structure of titanium alloy special-shaped parts on aircraft engines;

[0027] Figure 2 This is the front view of the semi-finished product blank;

[0028] Figure 3 It is a top view of the semi-finished blank;

[0029] Figure 4 Schematic diagram of the cross section of the reinforcement rib.

[0030] Explanation of the accompanying figures: 1. Titanium alloy special-shaped parts; 2. Semi-finished blank; 2a. Reinforcing ribs. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0033] Combination Figures 1 to 4 As shown, a method for processing special-shaped titanium alloy parts of aircraft engines comprises the following steps:

[0034] Step S1: Make a blank. The blank is divided into two symmetrical parts along the long axis according to the titanium alloy special-shaped part 1 and unfolded. After leaving a margin on one side, the blank is rounded to serve as the blank before hot forming. Figure 1 The cutting line A in the figure is used for segmentation.

[0035] Step S2: Apply protective coating, brush boron nitride protective coating on both sides of the blank, and brush boron nitride protective coating on the forming convex and concave dies of the mold, and dry naturally at room temperature. The boron nitride protective coating is a mixture of boron nitride powder and alcohol, and the solvent ratio is 1:1.

[0036] Step S3: Hot forming, the mold is heated to the set value with the equipment, the blank is placed in the mold for hot forming, and a semi-finished blank 2 with reinforcing ribs 2a separated along the long axis is obtained to ensure the profile and dimensional accuracy of the semi-finished blank 2. The equipment used for hot forming is hot forming equipment, the mold material used is 1Cr18NiTi, the mold concave mold surface is 0.998 times the outer surface of the part, and the width extends along the two sides of the mold; the punch is 0.998 times the inner surface of the part, and the width is consistent with the concave mold; the mold is heated to 750℃±10℃ with the equipment before the blank is loaded. The hot forming temperature is 750℃±10℃, the equipment pressure is 20-30T, and the heat preservation and pressure holding time is 15-18min.

[0037] Step S4: Clean the protective coating and wipe the boron nitride on the surface of the semi-finished blank 2 with a scouring pad in clean water to ensure that no stains remain.

[0038] Step S5: Cut the shape, use the reinforcing rib 2a to locate and align the part, and cut the semi-finished blank 2 to obtain the half part. Figure 3 Cut along the cutting line B in the figure.

[0039] Step S6: removing the oxide layer, firstly using sand blasting to remove the thicker oxide layer on the surface of the split part, and then performing pickling to accurately remove the oxide layer on the surface of the split part to ensure the surface roughness of the split part.

[0040] Step S7: The two halves are welded by laser welding to obtain a complete titanium alloy special-shaped part 1.

[0041] In the step S1, when making the blank, the titanium alloy special-shaped part 1 is symmetrically divided into two completely identical parts along the long axis, and after the parts are unfolded, a margin of 80-100 mm is added to one side along the long axis direction, and a margin of 50-80 mm is left on one side along the height direction of the parts, and the fan-shaped unfolded material is laid. Specifically, the blank is in the shape of a semi-conical cylinder, and after the fan-shaped unfolded material is laid, a three-axis rolling bed is used to roll the fan-shaped unfolded material into a semi-conical cylinder shape.

[0042] Combination Figure 3 , Figure 4 As shown, in this embodiment, the semi-finished blank 2 is divided into two halves, each extending 60-70 mm upward and downward to both ends, and a reinforcing rib 2a with a length of 150-200 mm is set at the position of extending 10-15 mm. The reinforcing rib 2a is a groove structure with a width of 5 mm; in the step S5, a laser cutting machine is used for cutting, and the reinforcing rib 2a is used for alignment and positioning during cutting. Furthermore, the bottom of the reinforcing rib 2a is R5 mm, and the two side walls of the reinforcing rib 2a and the bottom R5 are transitioned by R2, and the reinforcing rib 2a and the part body are transitioned by R2, and the reinforcing rib depth is 6-7 mm.

[0043] In step S7, after welding, the gap between the two halves is required to be no more than 0.2mm, and the misalignment is no more than 0.1mm. Furthermore, before laser welding, the surface to be welded of the half parts needs to be cleaned by pickling or polishing. The effective period of pickling is 120h, and the effective period of polishing is 8h. Before welding, the half parts within the validity period need to be cleaned with alcohol or acetone. No stains are allowed. Before laser welding, argon gas must be passed for protection, and the argon gas passing time is not less than 1min. The equipment uses a power of 3050-3100W, a welding speed of 0.01-0.05m / s, a defocus of 0-3mm, a laser deflection angle of 0-5°, a frequency of 4-45HZ, and a peak ratio of 50%.

[0044] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for processing special-shaped titanium alloy parts of aircraft engines, characterized in that the steps include: Step S1: making a blank, dividing the blank into two symmetrical parts along the long axis according to the titanium alloy special-shaped part (1) and unfolding them, leaving a margin on one side and then rounding them to serve as the blank before hot forming; Step S2: applying a protective coating, brushing boron nitride protective coating on both sides of the blank, and brushing boron nitride protective coating on the forming convex and concave dies of the mold, and drying naturally at room temperature; Step S3: hot forming, the mold is heated to a set value along with the equipment, the blank is placed in the mold for hot forming, and a semi-finished blank (2) with reinforcing ribs (2a) separated along the long axis is obtained, and the profile and dimensional accuracy of the semi-finished blank (2) are ensured; Step S4: Clean the protective coating, wipe the boron nitride on the surface of the semi-finished blank (2) with a scouring pad in clean water, and no stains remain; Step S5: cutting the outer shape, positioning and aligning the parts with the reinforcing ribs (2a), cutting the semi-finished blank (2) to obtain half parts; Step S6: removing the oxide layer; Step S7: laser welding the two halves to obtain a complete titanium alloy special-shaped part (1).

2. The method for processing special-shaped titanium alloy parts of aircraft engines according to claim 1, characterized in that: In step S1, when making the blank, the titanium alloy special-shaped part (1) is symmetrically divided into two completely identical parts along the long axis. After the parts are unfolded, a margin of 80-100 mm is added on one side along the long axis direction, and a margin of 50-80 mm is left on one side along the height direction of the parts, and the material is unfolded in a fan shape.

3. A method for processing special-shaped titanium alloy parts for aircraft engines as claimed in claim 2, characterized in that: In step S1, the blank is in a semi-conical cylinder shape. After the blank is cut to obtain a fan-shaped expanded material, a three-axis rolling machine is used to roll the fan-shaped expanded material into a semi-conical cylinder shape.

4. The method for processing a titanium alloy special-shaped part of an aircraft engine according to claim 1, characterized in that: In step S2, the boron nitride protective coating is a mixture of boron nitride powder and alcohol, and the solvent ratio is 1:

1.

5. The method for processing special-shaped titanium alloy parts of aircraft engines according to claim 1, characterized in that: When hot forming is performed in step S3, the mold material used is 1Cr18NiTi, the mold concave surface is 0.998 times the outer surface of the part, and the width extends along both sides of the mold; the punch is 0.998 times the inner surface of the part, and the width is consistent with that of the concave mold; the mold is heated to 750℃±10℃ with the equipment before the blank is loaded.

6. The method for processing special-shaped titanium alloy parts of aircraft engines according to claim 1, characterized in that: The semi-finished blank (2) is divided into two halves, each of which extends 60-70 mm upward and downward at both ends, and a reinforcing rib (2a) with a length of 150-200 mm is provided at a position of 10-15 mm extension.

7. The method for processing special-shaped titanium alloy parts of aircraft engines according to claim 1, characterized in that: The reinforcing rib (2a) is a groove-shaped structure with a width of 5 mm. In the step S5, a laser cutting machine is used for cutting, and the reinforcing rib (2a) is used for alignment and positioning during cutting.

8. The method for processing special-shaped titanium alloy parts of aircraft engines according to claim 1, characterized in that: In step S3, the hot forming temperature is 750°C±10°C, the equipment pressure is 20-30T, and the heat preservation and pressure holding time is 15-18min.

9. The method for processing special-shaped titanium alloy parts of aircraft engines according to claim 1, characterized in that: In step S6, when removing the oxide layer, sand blasting is first used to remove the thicker oxide layer on the surface of the half part, and then pickling is performed to accurately remove the oxide layer on the surface of the half part to ensure the surface roughness of the half part.

10. The method for processing special-shaped titanium alloy parts of aircraft engines according to claim 1, characterized in that: In step S7, After welding, the gap between the two halves should not exceed 0.2mm, and the misalignment should not exceed 0.1mm. Before laser welding, the surface of the split parts to be welded needs to be cleaned by pickling or polishing. The effective period of pickling is 120 hours, and the effective period of polishing is 8 hours. Before welding, the split parts within the validity period need to be cleaned with alcohol or acetone. No stains are allowed. Before laser welding, argon gas must be passed for protection, and the argon gas passing time should not be less than 1 minute. The equipment uses a power of 3050-3100W, a welding speed of 0.01-0.05m / s, a defocus of 0-3mm, a laser deflection angle of 0-5°, a frequency of 4-45HZ, and a peak ratio of 50%.

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