Machining method for hollow blade of aero-engine

Abstract

The invention discloses a machining method for a hollow blade of an aero-engine. The machining method comprises the steps of hollow blade blank designing, forging, parting surface and profile groove machining, hollow blade profile contour welding and hollow blade profile contour machining. The finished blade is split along the middle of the front edge and the rear edge, and then blanks are designed for the split blade basin and the blade back respectively. The subsequent welding and flaw detection requirements are considered when the hollow blade blank is designed, the allowance of each part of the blank is adjusted, and finally the shape and the size of the blank are obtained. Through reasonable blank design, the blade can be smoothly combined, welded and machined, and the size and quality of the cavity and the surface of the hollow blade are guaranteed.

Description

Technical Field

[0001] The invention belongs to the field of forging rough material design of hollow blades of aircraft engines, and in particular, relates to a rough material design method and a processing method of hollow blades of aircraft engines. Background Art

[0002] Aircraft engine compressor and fan blades are generally produced by die forging. The rationality and scientificity of the raw material design are related to the efficiency and cost of subsequent machining. When designing the raw material of the blade, a machining allowance of 0.4 to 2.5 mm is generally added to the blade body of the finished blade. If the structure of the tenon is complex, the maximum size is taken to increase the machining allowance by 1.5 to 2.5 mm; if the structure is simple, the machining allowance is evenly increased by 1.5 to 2.5 mm. The blade body and tenon with increased machining allowance are combined, and the transition between the two is appropriately processed to obtain the desired raw material shape.

[0003] like Figure 1 The figure shows a hollow adjustable guide vane. The blade is made of TC4 titanium alloy, with a length of 303mm and a width of 88mm. According to production experience, the blade body will have a rebound deformation of 1.5 to 2.5mm after forging. Therefore, the blade body machining allowance should be designed to be 2.5 to 3.0mm, and the mounting plate design allowance should be 2.5mm. However, the blade is a hollow blade, and there are five independent and closed cavities distributed along the longitudinal direction of the blade body inside the blade. The cavity cannot be forged, and the cavity is in a closed form and cannot be formed by mechanical processing. Summary of the invention

[0004] In view of the problems described in the background technology, the present invention aims to provide a method for processing hollow blades of aircraft engines. Through reasonable rough material design, the blades can be smoothly processed during combined diffusion welding and mechanical processing, thereby ensuring the size and quality of the blade cavity and surface.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for processing a hollow blade of an aeroengine, comprising:

[0007] Step 1, designing a hollow blade rough material, dividing the hollow blade into two parts along the Z-axis direction of the hollow blade, and the dividing surface passes through all the cavities inside the hollow blade and divides all the cavities into the aforementioned two parts, the portion between the blade basin surface and the dividing surface of the hollow blade is used as the blade basin rough material, and the portion between the blade back surface and the dividing surface of the hollow blade is used as the blade back rough material, the blade basin rough material and the blade back rough material each contain the same number of cavities, and then the blade basin surface and the dividing surface of the blade basin rough material are adjusted to a pair of parallel planes, and the blade back surface and the dividing surface of the blade back rough material are adjusted to a pair of parallel planes, and all surfaces of the blade basin rough material and the blade back rough material have processing allowances;

[0008] Step 2: forging, using die forging to forge the blade base raw material and blade back raw material designed in step 1;

[0009] Step 3: Processing the dividing surface and the groove: the dividing surface in step 1 and the groove corresponding to the hollow blade cavity on the dividing surface are respectively processed on the blade base raw material forging and the blade back raw material forging by machining;

[0010] Step 4: welding: welding the blade base material and the blade back material together along the dividing surface to form a hollow blade semi-finished product, wherein the grooves on the blade base material and the blade back material are spliced ​​to form a cavity of the hollow blade;

[0011] Step five, processing the hollow blade profile, referring to the hollow blade drawing, using machining to remove the excess on the hollow blade semi-finished product, and obtaining the profile of the hollow blade including the blade basin profile, blade back profile, leading edge, trailing edge and journal.

[0012] As a solution, in step one, the dividing surface passes through the midpoint of the leading edge and the midpoint of the trailing edge of the hollow blade profile section, that is, the blade profile sections at multiple different height positions on the Z axis of the hollow blade are taken to obtain its blade profile line, and the midpoint positions corresponding to the leading edge and the trailing edge in the blade profile line are taken, and then a curve is drawn through these two midpoint positions, and the curve divides the blade profile section into two parts.

[0013] As a scheme, in the step one, the blade basin curved surface and the dividing surface of the blade basin raw material, and the blade back curved surface and the dividing surface of the blade back raw material are respectively adjusted to a pair of parallel planes and a processing allowance is obtained by thickening the end face of the hollow blade shaft neck in the Y-axis direction, or, the blade basin curved surface and the dividing surface of the blade basin raw material, and the blade back curved surface and the dividing surface of the blade back raw material are respectively adjusted to a pair of parallel planes and a processing allowance is obtained by thickening the end face of the hollow blade shaft neck in the Y-axis direction.

[0014] As a solution, in the step 1, the machining allowance of the positioning groove is obtained by increasing the size of the blade base material and the blade back material in the X-axis direction.

[0015] As a solution, the step three also includes machining positioning grooves on the edges of the blade base material and the blade back material respectively.

[0016] As a solution:

[0017] In the step 1, the size of the blade base wool material and the blade back wool material is increased along the Z-axis direction, and a margin is reserved outside the corresponding hollow blade journal position;

[0018] The step three also includes machining fastening holes in the reserved margin area outside the hollow blade journal position corresponding to the step one, and the fastening holes are used to fix the relative positions of the blade basin raw material and the blade back raw material during welding in the step four.

[0019] As a solution, in step four, the blade basin wool and the blade back wool are welded together by diffusion welding, and the pressure surface during diffusion welding is the flat surface on the blade basin wool and the blade back wool.

[0020] As a solution:

[0021] In the step 1, before adjusting the blade basin curved surface and the split surface of the blade basin raw material into a pair of parallel planes and adjusting the blade back curved surface and the split surface of the blade back raw material into a pair of parallel planes, a section of machining allowance for flaw detection is added to the blade basin curved surface, the blade back curved surface and the split surface;

[0022] Ultrasonic flaw detection is also included between step 2 and step 3. The surfaces of the blade basin rough forging and the blade back rough forging obtained by forging in step 2 are first polished, and then ultrasonic flaw detection is performed to obtain forging defect information of the blade basin rough forging and the blade back rough forging.

[0023] Compared with the prior art, the present invention splits the hollow blade into two parts, designs the blade base and the blade back respectively, exposes the cavity inside the blade, and first processes the cavity part into shape, and then welds the two halves of the blank together to form a complete and closed cavity inside the blade. The present invention changes the traditional blank design method to obtain different processing allowances, and uses these allowances for positioning, clamping, flaw detection and surface processing, so that the closed and independent cavity inside the blade that cannot be produced by the traditional design method can be realized.

[0024] The present invention splits the finished blade along the middle of the front and rear edges and designs the rough stock for the blade basin and blade back after the split. The requirements of subsequent diffusion welding and flaw detection are taken into consideration during the design, and the margins of each part of the rough stock are adjusted to finally obtain the shape and size of the rough stock. The rough stock margin design of the present invention not only takes into consideration the processing cost (cutting amount) of the material, but also takes into consideration the functionality (including flaw detection, deformation, clamping and positioning, etc.) in the subsequent forging, machining and welding processes, to ensure the finished product quality of the hollow blade.

[0025] The rough material design method of the present invention has been used for processing hollow adjustable guide vanes and support plate blades, and the rough material has been forged and formed and the subsequent mechanical processing has been completed. At present, it has been verified that the rough material design scheme and processing method of the present invention are scientific and feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of hollow adjustable guide vanes;

[0027] Figure 2 A schematic diagram of the blade basin and blade back wool processing cavity and the dividing surface designed for the present invention;

[0028] Figure 3 Schematic diagram of the leaf basin and leaf back wool designed for the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to the common technical knowledge and customary means in the field are included in the scope of the present invention.

[0030] against Figure 1 The present invention solves the problem of forming hollow blades (hollow adjustable guide vanes) by equally dividing the hollow blades into two halves, a blade basin and a blade back, from the middle of the front and rear edges, and designing machining rough materials for the two halves of the blade basin and the blade back. Since the blade is a hollow adjustable guide vane, the blade body twist angle is small, and after being divided into two halves, the blade has a smaller size in the Y-axis direction of the blade section (or the Y-axis direction of the hollow blade shaft neck end face), and the surface that is required to apply pressure during subsequent welding should be designed as a plane. Therefore, the rough material is designed to be a flat plate, such as Figure 3 , the two end faces of the rough material in the figure are both flat. After the rough material is processed into the cavity, the upper and lower surfaces of the combined body are both flat when the two rough materials are combined into a whole, which is convenient for applying pressure to the flat surface during subsequent diffusion welding. The rough material is lengthened by 20 to 25 mm in the Z-axis direction for processing fastening holes (such as Figure 2 As shown in the figure, two fastening holes are machined on the upper large journal side, and one fastening hole is machined on the lower small journal side). Add 5 to 15 mm in the X-axis direction of the rough material to machine the positioning groove (such as Figure 2 As shown in the figure, there are two grooves in the front and rear directions, both of which are used for clamping and positioning). To ensure the accuracy of flaw detection, a flaw detection distance of 3mm must be guaranteed. Therefore, a machining allowance of 3mm is added at the highest and lowest points of the rough material, and finally the final shape and size of the rough material are obtained, as shown in the figure. Figure 3 shown.

[0031] It should be noted that the above-mentioned X-axis and Z-axis of the raw material refer to Figure 3 The coordinate system of the middle rough material, that is, the direction of downward pressure during die forging is the Y axis, corresponding to Figure 3 The X-axis is perpendicular to the Y-axis and corresponds to the width of the material. Figure 3 The Z axis is perpendicular to the XY axis plane and corresponds to the length direction of the raw material ( Figure 3 can be regarded as up and down directions).

[0032] The present invention adopts a non-traditional raw material design method to achieve the production of blades with a closed and independent cavity structure.

[0033] The processing idea of ​​the present invention is to process the blade in blocks, forge and machine it, and then assemble it to form a closed and independent cavity inside the finished blade. Therefore, when designing the raw material, the blade raw material needs to be divided into two pieces, which are used as the machining raw materials for the blade base and the blade back (such as Figure 2 , different gray levels in the figure represent the size of the machining allowance). The blade basin and blade back raw materials are respectively processed into cavity grooves, and then the cavity parts are butt-jointed and the blade basin and blade back are welded together by diffusion welding, and finally the outer contour dimensions of the blade are machined. When diffusion welding the blade basin and blade back combination, huge pressure and high temperature need to be applied to the components. In order to make the pressure evenly distributed, the force application position should be designed to be flat. In order to ensure that the components do not dislocate and deform under the action of pressure, the components need to be tightened. For this purpose, the length (Z-axis dimension) and width (X-axis dimension) of the raw material need to be increased for the design of fastening holes and positioning grooves (such as Figure 2 , 3 ). In order to prevent forging defects from being generated during the forging process, and defects not removed during machining and remaining in the finished blades, the forgings need to be polished before ultrasonic testing. According to the requirements of ultrasonic testing, the size of the finished forging from the edge of the rough material should be 3mm.

[0034] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. Although the illustrative specific embodiments of the present invention are described above to facilitate the understanding of the present invention by the technical personnel in the field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For ordinary technicians in the field of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A method for processing a hollow blade of an aero-engine, characterized in that: include: Step 1, designing a hollow blade rough material, dividing the hollow blade into two parts along the Z-axis direction of the hollow blade, and the dividing surface passes through all the cavities inside the hollow blade and divides all the cavities into the aforementioned two parts, the portion between the blade basin surface and the dividing surface of the hollow blade is used as the blade basin rough material, and the portion between the blade back surface and the dividing surface of the hollow blade is used as the blade back rough material, the blade basin rough material and the blade back rough material each contain the same number of cavities, and then the blade basin surface and the dividing surface of the blade basin rough material are adjusted to a pair of parallel planes, and the blade back surface and the dividing surface of the blade back rough material are adjusted to a pair of parallel planes, and all surfaces of the blade basin rough material and the blade back rough material have processing allowances; Step 2: forging, using die forging to forge the blade base raw material and blade back raw material designed in step 1; Step 3: Processing the dividing surface and the groove: the dividing surface in step 1 and the groove corresponding to the hollow blade cavity on the dividing surface are respectively processed on the blade base raw material forging and the blade back raw material forging by machining; Step 4: welding: welding the blade base material and the blade back material together along the dividing surface to form a hollow blade semi-finished product, wherein the grooves on the blade base material and the blade back material are spliced ​​to form a cavity of the hollow blade; Step five, processing the hollow blade profile, referring to the hollow blade drawing, using machining to remove the excess on the hollow blade semi-finished product, and obtaining the profile of the hollow blade including the blade basin profile, blade back profile, leading edge, trailing edge and journal.

2. The method for processing a hollow blade of an aero-engine according to claim 1, characterized in that: In the step 1, the dividing surface passes through the midpoint of the leading edge and the midpoint of the trailing edge of the hollow blade profile section.

3. The method for processing a hollow blade of an aero-engine according to claim 1, characterized in that: In the step one, the blade basin curved surface and the dividing surface of the blade basin raw material, and the blade back curved surface and the dividing surface of the blade back raw material are adjusted to a pair of parallel planes and a processing allowance is obtained by thickening the end face of the hollow blade shaft neck in the Y-axis direction, or the blade basin curved surface and the dividing surface of the blade basin raw material, and the blade back curved surface and the dividing surface of the blade back raw material are adjusted to a pair of parallel planes and a processing allowance is obtained by thickening the end face of the hollow blade shaft neck in the Y-axis direction.

4. The method for processing a hollow blade of an aero-engine according to claim 1, characterized in that: In the step 1, the machining allowance of the positioning groove is obtained by increasing the size of the blade base material and the blade back material in the X-axis direction.

5. The method for processing a hollow blade of an aero-engine according to claim 1, characterized in that: The step three also includes machining positioning grooves on the edges of the blade base material and the blade back material.

6. The method for processing a hollow blade of an aero-engine according to claim 1, characterized in that: In the step 1, the size of the blade base wool material and the blade back wool material is increased along the Z-axis direction, and a margin is reserved outside the corresponding hollow blade journal position; The step three also includes machining fastening holes in the reserved margin area outside the hollow blade journal position corresponding to the step one, and the fastening holes are used to fix the relative positions of the blade basin raw material and the blade back raw material during welding in the step four.

7. The method for processing a hollow blade of an aero-engine according to claim 1, characterized in that: In the step 4, the blade basin wool and the blade back wool are welded into one body by diffusion welding, and the pressure surface during diffusion welding is the plane surface on the blade basin wool and the blade back wool.

8. The method for processing a hollow blade of an aero-engine according to claim 1, characterized in that: In the step 1, before adjusting the blade basin curved surface and the split surface of the blade basin raw material into a pair of parallel planes and adjusting the blade back curved surface and the split surface of the blade back raw material into a pair of parallel planes, a section of machining allowance for flaw detection is added to the blade basin curved surface, the blade back curved surface and the split surface; Ultrasonic flaw detection is also included between step 2 and step 3. The surfaces of the blade basin rough forging and the blade back rough forging obtained by forging in step 2 are first polished, and then ultrasonic flaw detection is performed to obtain forging defect information of the blade basin rough forging and the blade back rough forging.

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