Machining method for precisely-forged blade root of outlet guide blade

Abstract

The invention relates to the technical field of machining of blade roots of outlet guide blades, in particular to a machining method for precisely forging the blade roots of the outlet guide blades, an initial machining original point is found through three-coordinate fitting, the initial states of all parts are close to a theoretical state as much as possible, and machining deformation is greatly reduced; through the design scheme that the two ends of the clamp are separated in a sliding mode, the distance difference between the two ends of a precision forge piece blank and workpiece deformation caused by pressing force in the clamping process are effectively and automatically released, and the blade machining precision is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of machining technology for the blade root of an outlet guide vane, specifically a machining method for precision-forged blade root of an outlet guide vane. Background Technology

[0002] Exit guide vanes are widely used in various aero-engines, playing a crucial role in improving engine performance and efficiency. With the continuous development of the aviation industry, the requirements for aero-engines are becoming increasingly stringent. To meet the demands for higher performance, greater reliability, and greater economy, exit guide vanes typically consist of a blade body and a root, welded together to form a complete blade. The root of the exit guide vane is a precision-forged part, with localized milling. Its structure is characterized by a wide chord length and thin walls, resulting in extremely poor machining rigidity. Precision forgings are prone to lateral and rotational misalignment, making it impossible to guarantee the consistency of blade condition for each batch. The surface precision of the precision forging directly affects the machining surface precision, leading to clamping deformation problems during root milling. The thinner the root, the more severe the clamping deformation. These deformations result in low machining accuracy for such blades, which to some extent restricts the performance of aero-engines.

[0003] The processing of the blade root of this type of blade includes two processes: precision milling of both ends and precision milling of the flash. The precision milling of both ends is performed using the six-point positioning of the precision forging, and the precision milling of the flash is performed using the precision milling of the machined surfaces at both ends. The advantage of this method is that it ensures the consistency between the six-point positioning of the precision forging and the milling positioning points, theoretically eliminating or reducing the datum conversion error. The disadvantage is that it has high requirements for blade clamping, that is, the blade cannot be compressed or deformed during clamping. Differences in the contour of the precision forging can easily lead to clamping deformation, which in turn leads to out-of-tolerance dimensional problems after milling. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for machining the precision-forged blade root of an outlet guide vane. Through innovative tooling design and machining methods, it solves the problems of clamping deformation and machining deformation caused by differences in the surface contour of the precision-forged blade root. The technical solution includes the following steps: Step 1: Based on the three-coordinate scanning analysis of precision forgings, multiple cross-sectional lines on the surface of the precision forgings are used as the overall fitting of the analysis object to automatically obtain the surface contour of the precision forgings in the best state. The three-coordinate system is used to automatically simulate the current optimal machining origin and output the analysis results as origin fitting data. Step 2: Use the theoretical 3D model to complete the CNC programming for finish milling both ends and finish milling the flash edges in CAM software; Step 3: Import the origin fitting data into the machining program to generate a machining program suitable for the precision milling of both ends of the current blade; Step 4: Complete the tooling design in CAM software using the theoretical 3D model; adopt digital modeling to machine modular positioning elements, with the positioning block and clamping force completely collinear, and the fixture adopts a two-end sliding separation design; Step 5: Perform precision milling on both ends. After precision milling, perform coordinate measuring machine (CMM) inspection on the blade. If it meets the drawing requirements, proceed with subsequent feature machining. If it does not meet the requirements, return to Step 1 to correct the machining origin. Step 6: Use the theoretical 3D model to complete the design of the precision milling flash edge tooling in CAM software. Use two pins for positioning, align the blade root hole with the pins to achieve precise blade positioning, and design a spring on the bottom surface of the pins. Step 7: Perform precision milling on the blades that passed the determination in Step 5 to remove the flash. After precision milling, perform subsequent blade processing. After completing all processes, use a coordinate measuring machine to check all dimensions.

[0005] Preferably, in step 1, 12 fitted cross-sectional lines are used to cover the surface of all precision forgings, that is, the horizontal scanning line spacing D is 15~20mm and the vertical scanning line spacing L is 45~50mm. Preferably, the smaller positioning surface in step 4 is typically selected as 5x5mm or 3x3mm; Preferably, the coordinate measuring machine (CMM) software used is Zeiss, and the CAM software used is RCS and UG.

[0006] By adopting this invention, the initial machining origin is found through three-coordinate fitting, so that the initial state of all parts is as close as possible to the theoretical state, and machining deformation is greatly reduced. Through the sliding separation design of the two ends of the fixture, the distance difference between the two ends of the precision forging blank and the deformation of the workpiece caused by the clamping force during the clamping process are effectively released automatically, which significantly improves the machining accuracy of the blade. Attached Figure Description

[0007] Figure 1 Flowchart of leaf and root processing method; Figure 2 This is a longitudinal section view of the leaf root; Figure 3 This is a cross-sectional view of the leaf root. Figure 4 A schematic diagram of the tooling structure for milling both ends; Figure 5 This is a schematic diagram of the milling tooling structure for milling in and out of flash. Detailed Implementation

[0008] The technical solutions of the embodiments of the present invention will now be described with reference to the accompanying drawings. Obviously, the described embodiments are for explanation and illustration only, and not all embodiments. All other embodiments obtained based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0009] like Figure 1 As shown, a method for machining the precision-forged blade root of an outlet guide vane includes the following steps: Step 1: Initial machining origin analysis of precision forgings based on coordinate measuring machine (CMM). Using 12 cross-sectional lines on the surface of the precision forging as the overall analysis object, the optimal state of the precision forging is automatically obtained. The CMM automatically simulates the current optimal machining origin, and the analysis results are output as origin fitting data. The longitudinal and transverse cross-sectional views of the blade root are shown below. Figure 2 and Figure 3 As shown, the horizontal scan line spacing D is 15~20mm, and the vertical scan line spacing L is 45~50mm; Step 2: Use the theoretical 3D model to complete the CNC programming for finish milling both ends and finish milling the flash edges in CAM software; Step 3: Import the origin fitting data into the machining program to generate a machining program suitable for the precision milling of both ends of the current blade; Step 4: Use the theoretical 3D model to complete the tooling design for the finish milling of both ends in CAM software, such as... Figure 4 As shown, positioning blocks 1 and 2 are set on both sides, and floating support component 5 is in the middle; modular positioning elements are machined using digital models. The advantage of this is that the positioning contact surface is small and easy to wear, which can be quickly disassembled and replaced; the clamping forces of positioning blocks 1 and 2 and V-shaped pressure blocks 3 and 4 are completely collinear, which reduces clamping deformation; the fixture adopts a two-end sliding separation design, which effectively and automatically releases the distance difference between the two ends of the precision forging blank and the deformation of the workpiece caused by the clamping force during clamping. Step 5: Perform precision milling on both ends. After precision milling, perform coordinate measuring machine (CMM) inspection on the blade. If it meets the drawing requirements, proceed with subsequent feature machining. If it does not meet the requirements, provide feedback to the operator and return to Step 1 for machining origin correction. Step 6: Use the theoretical 3D model to complete the design of the precision milling tooling for the flash edge in and out of the machine in CAM software, such as... Figure 5 As shown, the device includes a positioning seat 6, positioning pins 7 and 8, a clamping mechanism 9, and a pressing mechanism 10. It employs two-pin positioning, namely positioning pins 7 and 8, with the blade root hole aligned with them to achieve precise blade positioning. A spring is designed on the bottom surface of the pins. The positioning pins 7 and 8, along with the pressing mechanism 10, press the blade towards the positioning seat 6. During the pressing process, the springs compress until the end face is pressed, thus completing the positioning and clamping of the blade. To avoid damaging the blade root, a bakelite board is used for clamping. The clamping mechanisms 9 on both sides increase the rigidity of the clamping plate. Step 7: For the blades that have passed the judgment in Step 5, perform precision milling to remove the flash. After precision milling, perform subsequent blade processing, including etching, pickling, fluorescent flaw detection, etc. After completing all processes, use a coordinate measuring machine to check all dimensions.

[0010] In this example, the drafting software is UG, the CAM software is UG and RCS, and the CNC machine tool is a five-axis linkage milling machine.

Claims

1. A method for machining the precision-forged blade root of an outlet guide vane, characterized in that, Includes the following steps: Step 1: Based on the three-coordinate scanning analysis of precision forgings, multiple cross-sectional lines on the surface of the precision forgings are used as the overall fitting of the analysis object to automatically obtain the surface contour of the precision forgings in the best state. The three-coordinate system is used to automatically simulate the current optimal machining origin and output the analysis results as origin fitting data. Step 2: Use the theoretical 3D model to complete the CNC programming for finish milling both ends and finish milling the flash edges in CAM software; Step 3: Import the origin fitting data into the machining program to generate a machining program suitable for the precision milling of both ends of the current blade; Step 4: Complete the tooling design in CAM software using the theoretical 3D model; adopt digital modeling to machine modular positioning elements, with the positioning block and clamping force completely collinear, and the fixture adopts a two-end sliding separation design; Step 5: Perform precision milling on both ends. After precision milling, perform coordinate measuring machine (CMM) inspection on the blade. If it meets the drawing requirements, proceed with subsequent feature machining. If it does not meet the requirements, return to Step 1 to correct the machining origin. Step 6: Use the theoretical 3D model to complete the design of the precision milling flash edge tooling in CAM software. Use two pins for positioning, align the blade root hole with the pins to achieve precise blade positioning, and design a spring on the bottom surface of the pins. Step 7: Perform precision milling on the blades that passed the determination in Step 5 to remove the flash. After precision milling, perform subsequent blade processing. After completing all processes, use a coordinate measuring machine to check all dimensions.

2. The processing method for the precision forged blade root of the outlet guide vane according to claim 1, characterized in that, In step 1, 12 fitted cross-sectional lines are used to cover the surface of all precision forgings, with the horizontal scanning line spacing D being 15~20mm and the vertical scanning line spacing L being 45~50mm.

3. The processing method for the precision forged blade root of the outlet guide vane according to claim 1, characterized in that, Preferably, the smaller positioning surface in step 4 is typically selected as 5x5mm or 3x3mm.

4. The processing method for the precision forged blade root of the outlet guide vane according to claim 1, characterized in that, Preferably, the coordinate measuring machine (CMM) software used is Zeiss, and the CAM software used is RCS and UG.

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