Electric spark method for front diffuser blade profile of aero-engine combustion chamber

Abstract

The invention provides an electric spark method for a front diffuser blade profile of an aero-engine combustion chamber, which comprises the following steps of: sequentially performing electric spark machining on the profile and the runner surface of a blade through a rough machining profiling electrode, a blade back finish machining profiling electrode and a blade basin finish machining profiling electrode respectively; and finally, the thickness of the remelting layer on the surface of the electrosparking material is removed through abrasive particle flow equipment, the number of procedures is small, the machining precision can be guaranteed, and the machining efficiency and precision are effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of engine parts processing methods, in particular to an electric spark method for blade profiles of a pre-diffuser of an aero-engine combustion chamber. Background Art

[0002] Aircraft engine combustion chamber pre-diffuser, such as Figure 8 As shown in Figure 9, it is a high-temperature alloy impeller with a total of 88 blades. The flow path of the blades is relatively deep and narrow. At present, the front diffuser blade profile is milled by Liechti 600 five-axis machining center. The blade profile rough and fine milling cycle is 12 days, and more than 450 milling cutters of various types are used, and the processing cost is relatively high. At the same time, the diffuser adopts high-temperature alloy material GH4169D, and the spacing between the blades is small, the tool extends out of the tool handle for a long overhang, the tool chip processing wear stability is poor, the processing difficulty is large, and the blade pass rate after processing is low. The blade profile needs to be repaired by pliers to remove the blade surface, the flow path surface and the transition R angle. The blade profile area is polished to ensure the roughness requirements. It is necessary to go through multiple processes to achieve the design size requirements, and the processing efficiency is also low. Summary of the invention

[0003] In view of the problems that the existing front diffuser blades are processed by CNC machine tools, the processing cost is high, the qualified rate is low and the process is complicated, the present invention provides an electric spark method for the front diffuser blade profile of an aircraft engine combustion chamber, which adopts the electric spark machining method, reduces the processing steps, and improves the qualified rate and work efficiency.

[0004] The technical solution is as follows: an electric spark method for the blade profile of a pre-diffuser of an aircraft engine combustion chamber, comprising the following steps: S1, drilling a through hole in the area of ​​the blade to be processed along the circumferential direction of the impeller to remove the local excess; S2, rough machining, using a CNC EDM machine to control a rough machining profiling electrode to perform EDM rough machining on the drilling position. During the EDM rough machining, firstly, slots are opened between the blades, and then the inner and outer flow channel surfaces are rough machined. A single-side margin of 0.25 mm is reserved for rough machining; S3, finishing, using blade back finishing profiling electrode and blade basin finishing profiling electrode to electro-spark finish the blade inner, back arc blade shape and flow path surface, and reserve 0.05mm margin on one side for finishing; S4. Use abrasive flow equipment to squeeze the upper and lower hydraulic cylinders to make the soft abrasive flow through the blade surface of the blade to remove the EDM re-dissolved layer, chamfer and grind, and perform mirror processing by reciprocating motion.

[0005] It is further characterized in that: the CNC EDM machine tool is Taiwan Sinjet five-axis linkage S860CMAX, and the EDM machining method is oil flushing machining or oil immersion machining; The rough machining profiling electrode, the blade back finishing profiling electrode, and the blade basin finishing profiling electrode respectively include a positioning portion at the upper end and an electrode portion at the lower end, the length of the electrode portion is greater than the length of the blade, the electrode portion is arc-shaped, and its width is adapted to the width of the flow path surface of the blade, and the bending arc of the electrode portion of the rough machining profiling electrode is greater than the bending arc of the blade back finishing profiling electrode and the blade basin finishing profiling electrode; In S4, the discharge current of the abrasive flow device is 8A, the pulse width is 160μs, the pulse frequency is 5000Hz, the pulse interval is 80μs, and the voltage is 80V.

[0006] After adopting the above structure, the blade profile and flow path surface are electro-spark machined in sequence through specially made rough machining profiling electrodes, blade back finishing profiling electrodes, and blade basin finishing profiling electrodes, and finally the abrasive flow equipment is used to remove the thickness of the remelted layer on the surface of the electro-spark machined material to complete the processing. Not only does it reduce the number of steps but it can also ensure the processing accuracy, effectively improving the processing efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a schematic diagram of the rough machining profiling electrode structure of the present invention; Figure 2 This is a schematic diagram of the blade back finishing profiling electrode structure of the present invention; Figure 3 This is a schematic diagram of the blade basin finishing profiling electrode structure of the present invention; Figure 4 This is a schematic diagram of the rough machining structure of the rough machining profiling electrode of the present invention; Figure 5 This is a schematic diagram of the structure of a blade basin processed by a blade back finishing profiling electrode of the present invention; Figure 6 This is a schematic diagram of the structure of machining the back of a blade by a contour electrode for finishing the blade basin of the present invention; Figure 7 It is a schematic diagram of the drilling structure on the diffuser blade of the present invention; Figure 8 This is a schematic diagram of the structure of the finished diffuser of the present invention; Fig. 9 It is a partial structural schematic diagram of the finished diffuser of the present invention; DETAILED DESCRIPTION

[0008] like Figures 1 to 7 As shown, an electric spark method for blade profile of a pre-diffuser of an aircraft engine combustion chamber comprises the following steps: S1, drilling a through hole on the area of ​​the blade to be processed along the circumferential direction of the impeller, since the minimum spacing between the two blade profiles of the finished product is 12.15 mm, the diameter of the through hole is 3.5 mm, and the local margin is removed; S2, rough machining, use CNC EDM machine to control rough machining profiling electrode to perform EDM rough machining at the drilling position. EDM rough machining adopts arc approximation method to design appropriate electrode rough machining blade slot running route and rough machining profiling electrode thickness to eliminate the interference problem of rough machining profiling electrode during operation. During machining, firstly slot between blades, then perform rough machining of inner and outer flow channel surfaces, and reserve 0.25mm margin on one side for rough machining; S3, finishing, using the blade back finishing profiling electrode and the blade basin finishing profiling electrode to respectively perform electrospark finishing of the blade inner and back arc blade profiles and flow path surfaces, and reserve a single-side margin of 0.05mm after finishing. Specifically, during processing, the blade back finishing profiling electrode corresponds to the blade basin portion of the blade, and the blade basin finishing profiling electrode corresponds to the blade back portion of the blade; S4. Use abrasive flow equipment to squeeze the upper and lower hydraulic cylinders to make the soft abrasive flow through the blade surface to remove the excess after electrospark machining, including machining the re-dissolved layer, chamfering and grinding, and perform mirror machining by reciprocating motion.

[0009] Furthermore, the CNC EDM machine tool is Taiwan's Sinjet five-axis linkage S860CMAX, and the EDM machining method adopts oil flushing machining or oil immersion machining.

[0010] Furthermore, the rough machining profiling electrode, the blade back finishing profiling electrode, and the blade basin finishing profiling electrode are all made of copper material, and the rough machining profiling electrode, the blade back finishing profiling electrode, and the blade basin finishing profiling electrode respectively include a positioning portion a1 at the upper end and an electrode portion a2 at the lower end, wherein the positioning portion a1 is a rectangular platform, which can ensure that the clamping surfaces of each electrode after clamping are clamped into a high-precision positioning surface of uniform size. The electrode portion a2 is arc-shaped, and its width is adapted to the width of the flow path surface of the blade. Among them, since the bending radius of the electrode portion of the rough machining profiling electrode is larger than the bending radius of the blade back fine machining profiling electrode and the blade basin fine machining profiling electrode, the electric spark discharge contact surface of the rough machining profiling electrode during grooving is reduced during rough machining, thereby reducing the loss of the rough machining profiling electrode; and the length of the electrode portion a2 of each electrode extends outward by about 2 mm relative to the length of the blade in the height direction. Since the loss of the lower end face of the electrode is large when machining the blade flow channel, while the loss of the side face of the electrode is relatively small when machining the blade shape, the service life of the electrode can be extended by increasing the length of the electrode.

[0011] Furthermore, in S4, the discharge current of the abrasive flow device is 8A, the pulse width is 160μs, the pulse frequency is 5000Hz, the pulse interval is 80μs, and the voltage is 80V.

[0012] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by anyone familiar with the technology within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An aero-engine combustion chamber pre-diffuser blade profile electric spark method, comprising the following steps: S1, drilling through holes in the impeller circumferential direction corresponding to the blade area to be processed to remove local excess; S2, rough machining, using a CNC EDM machine to control a rough machining profiling electrode to perform EDM rough machining on the drilling position. During the EDM rough machining, firstly, slots are opened between the blades, and then the inner and outer flow channel surfaces are rough machined. A single-side margin of 0.25 mm is reserved for rough machining; S3, finishing, using blade back finishing profiling electrode and blade basin finishing profiling electrode to electro-spark finish the blade inner, back arc blade shape and flow path surface, and reserve 0.05mm margin on one side for finishing; S4. Use abrasive flow equipment to squeeze the upper and lower hydraulic cylinders to make the soft abrasive flow through the blade surface of the blade to remove the EDM re-dissolved layer, chamfer and grind, and perform mirror processing by reciprocating motion.

2. The method for producing an aero-engine combustion chamber pre-diffuser blade profile according to claim 1, characterized in that: The CNC EDM machine tool is Taiwan's Sinjet five-axis linkage S860CMAX, and the EDM machining method is oil flushing machining or oil immersion machining.

3. The method for producing an aero-engine combustion chamber pre-diffuser blade profile according to claim 1, characterized in that: The rough machining profiling electrode, the blade back finishing profiling electrode, and the blade basin finishing profiling electrode respectively include a positioning portion at the upper end and an electrode portion at the lower end, the length of the electrode portion is greater than the length of the blade, the electrode portion is arc-shaped, and its width is adapted to the width of the flow path surface of the blade, and the bending curvature of the electrode portion of the rough machining profiling electrode is greater than the bending curvature of the blade back finishing profiling electrode and the blade basin finishing profiling electrode.

4. The method for producing an aero-engine combustion chamber pre-diffuser blade profile according to claim 1, characterized in that: In S4, the discharge current of the abrasive flow device is 8A, the pulse width is 160μs, the pulse frequency is 5000Hz, the pulse interval is 80μs, and the voltage is 80V.

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