An efficient processing method for an integral blade disk of an aero-engine

Abstract

An efficient processing method for an integral blade disk of an aircraft engine, wherein the first rough processing allowance is 1-4 mm, and then milling is performed. The processing method is all from top to bottom, layered processing to the bottom of the blade, i.e., the root, and the blade is layered in the length direction of the blade, with at least 20 layers. After each layer in the length direction of the blade is processed, the next layer is processed, and each layer is processed with 2-4 cuts. The allowance within 1-4 mm is removed in layers, and the height of each layer is 0.3-0.8 mm. The machining center of the present invention can ensure the accuracy of the layered milling processing of the blade from top to root. It is necessary to select cutting tools and reasonable cutting parameters, and after uniform rough processing with large removal (or similar alloy forgings of suitable shape), the cutting stress generated during the processing is completely controllable, will not affect the accuracy, and the part structure is positioned once with high positioning accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of engines, and in particular to a method for manufacturing a large-diameter integral blade disk in an aero-engine. Background Art

[0002] The large-diameter integral blade disk in the aircraft engine is a rotating disk with evenly distributed blades without a flange mounting structure. The integral blade disk is a new type of structural component designed to meet the needs of high-performance aircraft engines. It integrates the engine rotor blades and the wheel disk, eliminating the tenon, tenon groove and locking device in the traditional connection, reducing the structural weight and the number of parts, avoiding the tenon airflow loss, improving the aerodynamic efficiency, and greatly simplifying the engine structure. It has now been widely used in aircraft engines. The wheel rim does not need to be machined with a tenon groove for installing blades, so the radial size of the wheel rim can be greatly reduced, thereby reducing the rotor mass and significantly improving the engine's thrust-to-weight ratio.

[0003] The integral blade disk structure eliminates the locking device structure of the blades, which greatly reduces the number of engine parts. This not only reduces costs, but also facilitates assembly and balancing, improves engine reliability, and extends the life of the rotor.

[0004] After adopting the integral blade disc, the air flow path becomes smooth, eliminating the loss caused by the leakage of air flow in the gap between the tenon root and the tenon groove in the disc separation structure, improving the aerodynamic performance and working efficiency, and at the same time avoiding failures caused by improper assembly or abrasion of the tenon, especially micro-wear, cracks and lock plate damage, thereby reducing the number of maintenance times and costs.

[0005] With the continuous improvement of the requirements for the bypass ratio, thrust-to-weight ratio and service life of aircraft engines, the integral blisk has adopted new technologies such as new wide chord, swept blades and narrow flow channels in the aerodynamic layout, thereby further improving the aerodynamic efficiency.

[0006] The integral blade disk is difficult to process. Therefore, the application of the integral blade disk becomes possible only after the manufacturing technology has developed to a certain level. Due to the complex blade shape of the integral blade disk, high precision requirements, thin blade shape, and large deformation after force, the processing volume is very large.

[0007] The main manufacturing technologies of the integral blade disk include: welding technology, milling technology, precision forging technology, electrolytic processing technology, etc. The adopted process flow is: precision forging + CNC processing; precision welding + CNC processing; high temperature alloy precision casting blank + hot isostatic pressing treatment, etc.

[0008] The diameter of the integral blade disk will be 400-900mm, and the thickness distribution and shape of the blades are designed separately. The thinnest part of the blade is only 0.3mm, and milling can ensure accuracy. Then, in the processing of integral blade disks in the existing technology, the common problem is that the support force of the workpiece is insufficient when the single blade is processed thinner and thinner in the later process; there is a phenomenon of tool letting-down in the finishing process (due to the deformation of the processed part, the milling cutter does not cut in place), and it is not easy to process to the tolerance required by the workpiece itself.

[0009] CN110465687B is a method for processing integral blades of an aero-engine that was previously applied for and approved by the present application. Aiming at the structure of evenly distributed blades on the integral disc, the processing parameters are set in a multi-axis milling machining center. All odd-numbered blade gaps on the integral disc are first processed in sequence. After all odd-numbered blade gaps are completed, hot melt wax is filled in the wrapping mold for all odd-numbered blade gaps. After the hot melt wax solidifies, all even-numbered blade gaps on the integral disc are processed in sequence in the multi-axis milling machining center. If the entire blade gap is an even number, then a circle of blades is also an even number. In this way, all odd-numbered blade gaps on the integral disc are first processed in sequence. After all odd-numbered blade gaps are completed, hot melt wax is filled in the wrapping mold for all odd-numbered blade gaps. After the hot melt wax solidifies, all even-numbered blade gaps on the integral disc are processed in sequence in the multi-axis milling machining center. In this way, the processing of the entire blade can be completed.

[0010] The existing technology can put an appropriate margin for direct finishing of the blade disk with small diameter blades (short blades). When making larger blade disks, that is, shorter blades, we will use the above-mentioned roughing and layer-by-layer thinning of the entire blade, and then use the last one or two layers of fixed anti-seismic materials made of filling wax, rosin, etc. for finishing. Anti-seismic materials include paraffin, gypsum, resin, etc. The use of anti-seismic materials generally has a better effect. However, it is not completely stable. For example, the heating, cooling, solidification, removal and cleaning of filling materials and other materials actually delays a lot of processing cycles, which greatly affects production efficiency. In addition, the processed fixed anti-seismic materials will be mixed into the cutting fluid. The cutting fluid becomes turbid, the service life of the cutting fluid is greatly shortened, and environmental pollution is prone to occur.

[0011] The integral blade disk is more difficult to process and manufacture due to its larger volume (large diameter and thin wall). The diameter can even reach φ1000mm, and a highly efficient processing method is required for batch production. Summary of the invention

[0012] The purpose of the present invention is to propose an overall high-efficiency processing method for an integral blade disk of an aero-engine, select a suitable chip cutting tool and reasonable cutting parameters; it can reduce the cutting stress generated by the parts during the processing, control and reduce the deformation of the parts, and achieve the final compliant parts.

[0013] The technical solution of the present invention is: an efficient processing method for an integral blade disk of an aero-engine, with a rough processing allowance of 1-4mm (a small area less than 1mm is also acceptable), followed by semi-finishing and finishing (milling), and the processing method is all layered from top to bottom to the bottom of the blade, i.e., the root, and the blade is layered in the length direction of the blade, with at least 20 layers. After each layer in the length direction of the blade is processed, the next layer is processed, and each layer is processed with 2-4 cuts, and 3 cuts are processed for rough processing, semi-finishing, and finishing continuously until the bottom of the blade, i.e., the root layer, is completed. The processing method of the present invention is characterized in that, even though the tip part (upper layer) of the blade is often designed to be the thinnest size of the blade, which can be only about 2mm, because the lower layer of the blade has not been processed yet, there is a thicker size to support the processing of the upper layer, so that it will not be deformed during milling until the processing is completed.

[0014] During two-cut machining, when the required machining allowance is 0.8-1.5mm, semi-finishing and finishing are 85±8% and 15±8% of the machining allowance respectively; especially 83-90% and 10-17%; semi-finishing and finishing can be completed quickly with one milling cutter;

[0015] When three-cut machining is performed, when the required machining allowance is 1.5-2.5mm, the rough machining, semi-finishing and finishing are 50±8%, 40±8% and 10±8% of the machining allowance respectively; especially 48-55%, 37-43% and 2±15%; rough machining, semi-finishing and finishing can be completed quickly with one milling cutter;

[0016] When machining with four cutters, when the required machining allowance is 2.5-4mm, the rough machining, first semi-finishing, second semi-finishing, and finishing are 40%, 27.5%, 27.5%, and 5% of the machining allowance respectively; one milling cutter can be used to quickly complete the rough machining, first and second semi-finishing, and finishing;

[0017] In order to process the blade disc efficiently, accurately and stably, the processing scheme of the present invention is changed to a mixed method from the original rough machining, semi-finishing and finishing division processing mode, which is all processed from top to bottom. Now it is changed to the rough machining, semi-finishing and finishing of each layer continuously, and the processing is carried out layer by layer from top to bottom to the bottom of the blade.

[0018] Beneficial effects: Since the blade shape of the integral blade disk is complex, the precision requirement is high, the blade shape is thin, and the deformation is large after being subjected to force, the processing volume is very large, and the integral blade disk is difficult to process. The diameter of the integral blade disk will be 400-900mm, and the thickness distribution and shape of the blades are designed separately. The thinnest part of the blade thickness is even 0.5mm. The processing of the present invention can ensure the accuracy of the milling processing of the blade from top to root. It is necessary to select cutting tools and reasonable cutting parameters, and after uniform rough processing with large amount of removal (or similar alloy forgings of suitable shape), the cutting stress generated during the processing is completely controllable and will not affect the accuracy. The part structure is positioned once and the positioning accuracy is high. If necessary, it will be heated again, and the error of workpiece processing deformation is eliminated by turning layer by layer. Through verification, it is concluded that the workpiece fully meets the design requirements and the scheme is feasible, and the high precision and non-deformation requirements of the drawings are fully met. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the two-knife sequential processing method of the present invention.

[0020] Figure 2 It is a schematic diagram of the three-knife sequential processing method of the present invention. DETAILED DESCRIPTION

[0021] Processing implementation scheme of aircraft engine integral blade disk: As shown in the figure, the diameter of the aircraft engine integral blade disk reaches φ1000mm, and the length of the blade can reach 200mm. The milling method of the present invention can be used to process blades as thin as 0.3mm; the blank is selected from the forged blank, and after the first rough processing, a rough processing piece with a thickness of 1-4mm is left on one side, which can be heat treated. After the heat treatment, a chip cutting tool and cutting parameters are selected for the second rough processing, semi-finishing and finishing of milling (the milling speed of rough processing, semi-finishing and finishing is preferably controlled, and the milling speed of the second rough processing, semi-finishing and finishing is preferably 1:1:1.5); the cutting stress generated during the processing of each layer will not affect the milling accuracy, so as to control the deformation of the parts and achieve a final workpiece that meets the standards;

[0022] After the first rough machining, the blank is left with an allowance, and after the rough turning of the shape to leave an allowance of 3-4mm on one side, stress relief heat treatment is carried out: vacuum furnace 160℃ for 3 hours and air cooling; 150-180℃ for 60-600min.

[0023] To ensure that the workpiece has a certain rigidity, the milling machine (generally a four-axis or five-axis machining center) is used, and the outer diameter of the integral impeller is fine-machined to the machining center.

[0024] Furthermore, the chip cutting tool specifications are R2.5-R10 ball end mills; the larger the disc and blade, the larger the size of the milling cutter, that is, R8-R10 can be used. The cutting amount of the large-size milling cutter also increases accordingly;

[0025] Furthermore, the excess within 1-4 mm is removed in layers, and the height of each layer is 0.3-0.8 mm.

[0026] Furthermore, during milling, the tool speed is 1000-3000 / min and the feed is 600-1000 mm / min.

[0027] Because the blank allowance and product shape are not uniform, and metal processing requires uniform removal, the programming difficulty is increased. It is necessary to compile a program to uniformly remove the blank blades and external allowances during processing, and minimize the cutting stress generated by the parts during processing to control and reduce the deformation of the parts to meet the requirements of the drawings. The wire cutting method is also used to remove the blank blades and external allowances from the workpiece, and finally the parts are rough, semi-finished, and finely processed, and each dimension is detected online to ensure the requirements of the drawings.

[0028] When processing each layer, the workpiece can be milled with rigid support to ensure that the blade accuracy at the processing location meets the requirements. The present invention requires layering from top to bottom and then roughing, semi-finishing and finishing to remove materials uniformly layer by layer, so the 3-4 mm margin on a single side is removed in layers, leaving about 1MM after roughing, leaving 0.15-0.2MM margin after semi-finishing, and finally removing all the margins by finishing.

[0029] The milling cutter specifications are as mentioned above. After turning, use an online detector to check the dimensions to ensure that they meet the requirements of the drawing. Processing route of the splitter ring: A10 first step rough milling shape, leaving a 3mm margin on one side → A20 stress relief heat treatment (vacuum furnace 160℃ insulation for 3 hours air cooling, heat treatment range 150-180℃ 60-600min) →

[0030] A30 turning the base → A40 semi-finishing turning the inner and outer circles → A70 finishing turning the inner hole to the drawing requirements, i.e. 0 excess → A80 clamping to the machining center → A90 the first layer of rough, semi-finishing and finishing of all blades to remove materials evenly → A100-500 the 2nd to nth layers of rough, semi-finishing and finishing of all blades to remove materials evenly → A510 clamping → A520 inspection → A530 marking → A540 final inspection.

[0031] Figure 1It is processed in sequence with 2 cuts, and is used for blades with a size of less than 80mm. 1 and 2 are the processing sequence of the first layer, 3 and 4 are the processing sequence of the second layer, and the numbers are the sequence; the conventional processing method is rough processing and fine processing. Mixed processing is not allowed. The present invention interrupts and integrates various programs by developing some plug-ins. As shown in the figure, rough, semi-fine and fine processing are carried out alternately. On the premise that there is enough margin left for the blades. There is support below, and all the blades of this layer are processed downwards layer by layer according to the logic of semi-fine one cut and fine one cut. The margin within 1-2 mm is removed layer by layer, and the height of each layer is 0.3-0.4mm respectively.

[0032] For some blades with particularly large sizes, a large amount of material will be left during rough machining for the sake of support. At this time, two-cut machining may not work. The first cut of each layer has a large amount of cutting, and the tool cannot cut it, so we will combine many tool paths to meet the processing needs. For example, rough machining, first half-finishing, second half-finishing and finishing.

[0033] Figure 2 It is divided into 3 cuts and processed in sequence. For blades with a length of 80-170mm, 1, 2, 3 are the first layer processing sequence, 4, 5, 6 are the second layer processing sequence, and direct rough processing and fine processing are mixed together. In this way, the processing difficulties of filling and insufficient rigidity in conventional blade processing can be effectively avoided. Blades with a length of more than 170mm can be derived to 4 cuts per layer. The excess within 3-4 mm is removed in layers, and the height of each layer is 0.4-0.8mm.

[0034] Control of process parameters of important nodes: Taking a 4-edge R4 ball-end milling cutter as an example, as shown in Table 1.

[0035] Table 1

[0036]

[0037]

[0038] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. An efficient processing method for an integral blade disk of an aero-engine, characterized in that: Leave 1-4mm allowance for the first rough machining, and then carry out milling. The machining method is all from top to bottom, layered to the bottom of the blade, i.e. the root, and layered in the length direction of the blade, at least 20 layers. After each layer in the length direction of the blade is completed, the next layer will be processed. Each layer is processed with 2-4 cuts.

2. The efficient processing method of the integral blade disk of the aircraft engine according to claim 1 is characterized in that: The excess within 1-4 mm is removed in layers, with each layer height being 0.3-0.8 mm.

3. The efficient processing method of the integral blade disk of an aircraft engine according to claim 1 or 2, characterized in that: Each layer is processed with 2 cuts, namely semi-finishing and finishing.

4. The efficient processing method of the integral blade disk of an aircraft engine according to claim 1 or 2, characterized in that: Each layer is processed with 3 cuts, which are rough processing, semi-finishing and finishing continuously until the bottom of the blade, i.e. the root layer, is completed.

5. The efficient processing method of the integral blade disk of an aircraft engine according to claim 1 or 2, characterized in that: The chip cutting tool specifications are R2.5-R10 ball end mills.

6. The efficient processing method of the integral blade disk of an aircraft engine according to claim 1 or 2, characterized in that: The milling speeds for roughing, semi-finishing and finishing, and the milling speeds for the second roughing, semi-finishing and finishing are 1:1:1.

5.

7. The high-efficiency machining method of an aircraft engine integral blade disk according to claim 1, characterized in that: After the first rough machining, the blank is left with an allowance, and after the rough turning of the shape to leave an allowance of 3-4mm on one side, stress relief heat treatment is carried out: vacuum furnace 160℃ for 3 hours and air cooling; 150-180℃, 60-600min.

8. The high-efficiency machining method of an aircraft engine integral blade disk according to claim 1, characterized in that: During milling, the tool speed is 1000-3000 / min and the feed is 600-1000mm / min.

Images