Aeroengine fuel accessories key parts composite processing

Chen Jianxin (left) and Yan Qi (right), First Class Experts from Xi'an Aerospace Power Control Co., Ltd. of the AVIC Engine Group

Aero engine fuel accessories play a crucial role in supplying and dynamically adjusting the fuel required by the engine based on its operational state and the aircraft's flight conditions. This ensures the aircraft’s maneuverability, accuracy, and safety. Modern aero engine fuel systems typically consist of several key components, including the main fuel system, afterburner system, flow regulation system, emergency oil drain system, and drain system. Due to the complexity and critical nature of these components, advanced technologies such as special processing and composite machining are essential to overcome manufacturing challenges and reduce overall costs. Composite machining offers significant advantages, such as shortening the processing cycle, reducing work-in-progress inventory, and supporting just-in-time manufacturing with zero inventory. It also minimizes the number of setups, reduces installation errors, improves processing accuracy and stability, and enhances the control of fuel accessories. These improvements ensure safe and reliable engine operation while maximizing performance. The following example illustrates the machining of an induction wheel using the S191 Linear Turn-Milling Machining Center.

Part Structure and Material

The material used is TC4 titanium alloy, known for its high strength, hardness, toughness, and elongation, but it has poor thermal conductivity, significant work hardening, and challenging cutting properties. The induction wheel is part of the impeller fuel pump and is located at the front end of the impeller. Its inner surface is a rotating body that is finished through turning, while the outer surface features evenly distributed blades that are milled. At both ends, there are end face grooves and radial square holes, making this a typical part for turn-mill composite machining (see Figure 1).

Figure 1: Three-Dimensional Model of the Induction Wheel

2. Equipment Selection

The S191 Linear Turn-Milling Machining Center was selected for this task. This seven-axis CNC machine combines the benefits of a five-axis machining center and a two-spindle turning center. It allows for five-axis linkage processing of both front and back parts. The Y and Z axes are driven by linear motors in a horizontal plane, and the rear spindle can be rotated vertically or horizontally, enabling high-precision machining in both horizontal and vertical positions (see Figure 2).

Figure 2

3. Machining Process

Through process analysis, it was found that the part has a large machining allowance, and the blade thickness is only 2mm. Large margin processing can lead to significant deformation. Therefore, stress relief and angular orientation must be carefully considered during the process. Since the device has a dual-spindle function with an extended head at the small outer circumference, the positioning hole is placed here to prevent errors caused by secondary clamping. Based on the principle of completing multiple processing steps under one clamping, the machining route was determined as follows: rough turning, boring, drilling the positioning hole, deburring, rough milling, stabilization, grinding the hole, fine turning, fine milling, milling the square hole, turning the tool head, turning the conical surface, and milling the groove, followed by final inspection. Roughing is performed on the lathe and CNC machine. However, due to cost and precision considerations, roughing cannot be done on this equipment. Finishing, including deburring, turning the cone surface, and milling, is alternately performed using the dual-spindle of the turn-milling machining center, with all positioning completed in one setup. This approach fully utilizes the machine's capabilities, shortens the process route, ensures reliable processing, significantly improves efficiency, reduces costs, and guarantees quality. Advanced materials and modern manufacturing technologies are fundamental to aerospace development. As the demand for better processing quality and higher productivity increases, it becomes essential to research and implement efficient and diverse composite machining technologies.

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