A machining method for a titanium alloy special-shaped part of an aero-engine

Abstract

The present application relates to the technical field of aircraft engine part processing, and particularly relates to a processing method of an aircraft engine titanium alloy special-shaped part, which comprises the following steps: step S1: blank making, the blank is divided into two symmetrical parts along the long axis of the titanium alloy special-shaped part and is expanded, and then is rolled into a circle with a single side allowance, serving as a blank before hot forming; step S2: protective coating, boron nitride protective paint is brushed on both sides of the blank, and the convex and concave dies are also brushed with boron nitride protective paint, and then are naturally dried at room temperature; step S3: hot forming, the mold is heated to a set value with the equipment, the blank is put into the mold for hot forming, a half-finished blank with a reinforcing rib along the long axis is obtained, and the profile and size accuracy of the half-finished blank are ensured; step S4: cleaning of the protective paint, the surface of the half-finished blank is wiped with a scouring pad in clean water, and no stain is left; step S5: cutting of the shape, the half-finished blank is cut to obtain a half part, with the reinforcing rib serving as a positioning reference; step S6: removal of the oxide layer; and step S7: laser welding of the two half parts to obtain a complete titanium alloy special-shaped part.

Description

A method for machining irregularly shaped titanium alloy parts for aero engines Technical Field

[0001] This invention relates to the field of aero-engine parts processing technology, and in particular to a method for processing irregular titanium alloy parts for aero-engines. Background Technology

[0002] Aero engines need to operate reliably for extended periods under conditions of high temperature, high pressure, high speed, and high load. Figure 1 shows a schematic diagram of a titanium alloy irregularly shaped component on an aero engine. It is manufactured using TA15 sheet metal. TA15 is a difficult-to-machine material with high tensile strength and yield strength, requiring significant impact force. Furthermore, due to its low elastic modulus E, it exhibits large and irregular springback during cold forming. Its low elongation δ5 and reduction of area ψ are also unfavorable for stamping. The material thickness of 2.5 mm further complicates the forming process. The part has a variable cross-section irregular shape that changes from a "large belly" spline curve ellipse to a "small belly" spline curve ellipse in the axial direction. Two longitudinal welds are permitted along the generatrix, with a negative angle in the axial direction. The total height is 198 mm, with the major axis transitioning from 768.3 mm to 837.5 mm and the minor axis transitioning from 540.5 mm to 421.3 mm. The dimensional tolerances for the major and minor axes are 0.4, and the overall surface profile is 2. Superplastic forming of this titanium alloy irregular part requires high material grain size, making it difficult to guarantee the material's mechanical properties and resulting in high processing costs. Therefore, a processing method for titanium alloy irregular parts for aero-engines is needed to meet the quality requirements for part shape and dimensional accuracy. Summary of the Invention

[0003] The main objective of this invention is to propose a processing method for titanium alloy irregular-shaped parts for aero-engines, aiming to solve the aforementioned technical problems.

[0004] To achieve the above objectives, this invention proposes a method for processing irregularly shaped titanium alloy parts for aero-engines, comprising the following steps:

[0005] Step S1: Make a blank. The blank is divided into two symmetrical parts along the long axis according to the titanium alloy irregular part and unfolded. After cutting the material with a single-sided allowance, it is rolled into a round shape as a blank before hot forming.

[0006] Step S2: Apply a protective coating. Apply boron nitride protective coating to both sides of the blank, and at the same time apply boron nitride protective coating to the forming punch and die of the mold. Allow it to dry naturally at room temperature.

[0007] Step S3: Thermoforming. The mold is heated to the set value by the equipment. The blank is placed into the mold for thermoforming to obtain a semi-finished blank with reinforcing ribs that are separated along the long axis, ensuring the surface and dimensional accuracy of the semi-finished blank.

[0008] Step S4: Clean the protective coating. Wipe the boron nitride surface of the semi-finished blank with a scouring pad in clean water until no stains remain.

[0009] Step S5: Cut the outline, use reinforcing ribs to position and align the parts, cut the semi-finished blank to obtain the split parts;

[0010] Step S6: Remove the oxide layer;

[0011] Step S7: Use laser welding to weld the two half parts together to obtain a complete titanium alloy irregular part.

[0012] Preferably, in step S1, when making the blank, the titanium alloy irregular part is symmetrically divided into two identical parts along the long axis. After unfolding the parts, an allowance of 80-100mm is added on one side along the long axis, and an allowance of 50-80mm is left on one side along the height of the parts, and the lower fan-shaped unfolded material is formed.

[0013] Preferably, in step S1, the blank is in the shape of a semi-conical cylinder. After the fan-shaped unfolded material is obtained by cutting, a three-axis rolling machine is used to roll the fan-shaped unfolded 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, with a solvent ratio of 1:1.

[0015] Preferably, in the thermoforming process of 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 direction; the punch is 0.998 times the inner surface of the part, and the width is the same as the concave surface; the blank is inserted into the mold after the equipment is heated to 750℃±10℃.

[0016] Preferably, the semi-finished blank is a half part that extends 60-70mm from both ends vertically, and a reinforcing rib with a length of 150-200mm is provided at a position 10-15mm from the extension.

[0017] Preferably, the reinforcing rib is a groove-shaped structure with a width of 5mm; in 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 thermoforming temperature is 750℃±10℃, the equipment pressure is 20-30T, and the heat and pressure holding time is 15-18min.

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

[0020] Preferably, 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 surfaces of the halves to be welded need to be cleaned by pickling or polishing. The pickling validity period is 120h, and the polishing validity period is 8h. Before welding, the halves to be welded 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 circulation time should not be less than 1min. The equipment should have a power of 3050-3100W, a welding speed of 0.01-0.05m / s, a defocusing amount of 0-3mm, a laser deflection angle of 0-5°, a frequency of 4-45HZ, and a peak coverage 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) By adopting the processing method provided by the present invention, reasonable parting and scientific blank structure are used to achieve the accuracy of the semi-finished blank surface through reasonable process parameters, reasonable welding methods and welding parameters, which greatly improves work efficiency and part quality.

[0023] (2) In this invention, the hot pressing method with reinforcing ribs is used to form parts in half. The reinforcing ribs serve as the reference for the shape processing process, ensuring that the shape processing and forming of the parts are coaxial, thus achieving precise processing of the parts' shape. The processing method of removing the oxide layer on the hot-formed surface by first blowing sand and then pickling shortens the oxide layer removal time from 72 hours to 2 hours. Welding is carried out by pulse welding of laser welding, achieving small deformation welding under atmospheric conditions, so as to meet the quality requirements of the size and shape accuracy of the parts, greatly improving work efficiency and reducing the processing cost of the parts.

[0024] (3) The processing method is currently in use on site and has achieved the purpose of the invention. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0026] Figure 1 is a schematic diagram of the titanium alloy irregular-shaped component structure on an aero-engine;

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

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

[0029] Figure 4 is a schematic diagram of the cross-section of the reinforcing rib.

[0030] Explanation of reference numerals: 1. Titanium alloy irregular part; 2. Semi-finished blank; 2a. Reinforcing rib. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

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

[0033] Referring to Figures 1 to 4, a method for machining irregularly shaped titanium alloy parts for aero-engines includes the following steps:

[0034] Step S1: Prepare the blank. The blank is divided into two symmetrical parts along the long axis according to the titanium alloy irregular part 1. After unfolding, allowance is left on one side, and the blank is rolled into a round shape to serve as the blank before hot forming. Specifically, the cutting is carried out along the cutting line A in Figure 1.

[0035] Step S2: Apply a protective coating. Apply boron nitride protective coating to both sides of the blank, and simultaneously apply boron nitride protective coating to the forming punch and die of the mold. Allow it to dry naturally at room temperature. The boron nitride protective coating is a mixture of boron nitride powder and alcohol, with a solvent ratio of 1:1.

[0036] Step S3: Thermoforming. The mold is heated to the set temperature by the equipment. The blank is placed into the mold for thermoforming to obtain a semi-finished blank 2 with reinforcing ribs 2a separated along the long axis, ensuring the surface and dimensional accuracy of the semi-finished blank 2. The equipment used for thermoforming is a thermoforming machine. The mold material is 1Cr18NiTi. The concave mold surface is 0.998 times the outer surface of the part, and its width extends along both sides of the mold direction. The convex mold is 0.998 times the inner surface of the part, and its width is consistent with that of the concave mold. The mold is heated to 750℃±10℃ by the equipment before the blank is placed in. The thermoforming temperature is 750℃±10℃, the equipment pressure is 20-30T, and the holding time is 15-18min.

[0037] Step S4: Clean the protective coating. Wipe the boron nitride surface of the semi-finished blank 2 with a scouring pad in clean water until no stains remain.

[0038] Step S5: Cut the outline, use the reinforcing rib 2a to position and align the part, and cut the semi-finished blank 2 to obtain the split part. Specifically, the cutting is performed along the cutting line B in Figure 3.

[0039] Step S6: Remove the oxide layer. First, use sandblasting to remove the thicker oxide layer on the surface of the split part, and then perform pickling to accurately remove the oxide layer on the surface of the split part and ensure the surface roughness of the split part.

[0040] Step S7: Use laser welding to weld the two half parts together to obtain a complete titanium alloy irregular part 1.

[0041] In step S1, during the blank preparation, the titanium alloy irregular part 1 is symmetrically divided into two identical parts along its long axis. After unfolding the parts, an allowance of 80-100mm is added to one side along the long axis, and an allowance of 50-80mm is left on one side along the height direction of the parts, resulting in a fan-shaped unfolded material. Specifically, the blank is a semi-conical shape. After the fan-shaped unfolded material is obtained, it is rolled into a semi-conical shape using a three-axis rolling machine.

[0042] Referring to Figures 3 and 4, in this embodiment, the semi-finished blank 2 is a split part extending 60-70mm from both ends vertically, with reinforcing ribs 2a of 150-200mm in length provided at 10-15mm extension positions. The reinforcing ribs 2a are groove-shaped structures with a width of 5mm. In step S5, a laser cutting machine is used for cutting, and the reinforcing ribs 2a are used for alignment and positioning during cutting. Furthermore, the bottom of the reinforcing rib 2a has an radius of 5mm (R5mm), and the two side walls of the reinforcing rib 2a transition to the bottom radius of 5mm (R2mm). The reinforcing rib 2a is also connected to the main body of the part using an R2 transition, and the depth of the reinforcing rib is 6-7mm.

[0043] In step S7, after welding, the gap between the two halves should not exceed 0.2mm, and the misalignment should not exceed 0.1mm. Further, before laser welding, the surfaces of the halves to be welded need to be cleaned using pickling or polishing. Pickling is effective for 120 hours, and polishing for 8 hours. Within the effective period, the halves need to be cleaned with alcohol or acetone before welding, ensuring no stains remain. Before laser welding, argon gas must be used for protection for at least 1 minute. The equipment should have a power of 3050-3100W, a welding speed of 0.01-0.05m / s, a defocusing amount of 0-3mm, a laser deflection angle of 0-5°, a frequency of 4-45Hz, and a peak coverage ratio of 50%.

[0044] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for processing irregularly shaped titanium alloy parts for aero-engines, characterized in that, The steps include: Step S1: Making a blank. The blank is divided into two symmetrical parts along the long axis according to the titanium alloy shaped part (1) and unfolded. After blanking with a single-sided allowance, it is rolled and bent as a blank before hot forming. The blank is a semi-conical shape. After blanking to obtain a fan-shaped unfolded material, the fan-shaped unfolded material is rolled into a semi-conical shape using a three-axis rolling machine. When dividing, it is divided along the cutting line A. Step S2: Applying a protective coating. Boron nitride protective coating is applied to both sides of the blank. At the same time, boron nitride protective coating is applied to the forming punch and die of the mold. It is then dried naturally at room temperature. Step S3: Hot forming. The mold is heated to the set value by the equipment. The blank is placed into the mold for hot forming to obtain a semi-finished blank (2) with reinforcing ribs (2a) separated along the long axis, ensuring the surface and dimensional accuracy of the semi-finished blank (2). Step S4: Cleaning the protective coating. The surface of the semi-finished blank (2) was wiped with a scouring pad in water to remove boron nitride, leaving no stains. Step S5: Cut the shape and use the reinforcing rib (2a) to position and align the parts. Cut the semi-finished blank (2) to obtain the split parts. Cut along the cutting line B. Step S6: Remove the oxide layer. Step S7: Use laser welding to weld the two split parts to obtain a complete titanium alloy irregular part (1). The semi-finished blank (2) is a split part that extends 60-70mm from the top and bottom to both ends, and reinforcing ribs (2a) with a length of 150-200mm are set at the 10-15mm extension position. The reinforcing rib (2a) is a groove structure with a width of 5mm. In step S5, a laser cutting machine is used for cutting. The reinforcing rib (2a) is used for alignment and positioning during cutting.

2. The processing method for aero-engine titanium alloy irregular-shaped parts as described in claim 1, characterized in that, In step S1, when making the blank, the titanium alloy irregular part (1) is symmetrically divided into two identical parts along the long axis. After unfolding the parts, an allowance of 80-100mm is added on one side along the long axis and an allowance of 50-80mm is left on one side along the height of the parts. The lower fan-shaped unfolded material is then used.

3. The processing method for aero-engine titanium alloy irregular-shaped parts as described in claim 1, characterized in that, In the thermoforming process of step S3, the mold material used is 1Cr18NiTi. The concave mold surface is 0.998 times the outer surface of the part, and its width extends along both sides of the mold direction. The punch is 0.998 times the inner surface of the part, and its width is the same as that of the concave mold. The blank is inserted into the mold after it is heated to 750℃±10℃ by the equipment.

4. The processing method for aero-engine titanium alloy irregular-shaped parts as described in claim 1, characterized in that, In step S3, the thermoforming temperature is 750℃±10℃, the equipment pressure is 20-30T, and the heat and pressure holding time is 15-18min.

5. The processing method for aero-engine titanium alloy irregular-shaped parts as described in claim 1, characterized in that, In step S6, when removing the oxide layer, sandblasting is first used to remove the thicker oxide layer on the surface of the split part, and then acid pickling is performed to accurately remove the oxide layer on the surface of the split part and ensure the surface roughness of the split part.

6. The processing method for aero-engine titanium alloy irregular-shaped parts as described in 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 surfaces of the halves to be welded need to be cleaned by pickling or polishing. The pickling validity period is 120h, and the polishing validity period is 8h. Before welding, the halves to be welded need to be cleaned with alcohol or acetone, and no stains are allowed. Argon gas protection is required before laser welding, and the argon gas circulation time should not be less than 1min. The equipment should have a power of 3050-3100W, a welding speed of 0.01-0.05m / s, a defocusing amount of 0-3mm, a laser deflection angle of 0-5°, a frequency of 4-45HZ, and a peak coverage ratio of 50%.

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