A whole machining method for an aero-engine ultra-thin-wall and easy-to-deform aluminum alloy multi-segment splitter ring

Abstract

A kind of overall processing method of aero-engine aluminum alloy split flow ring, select the circular column aluminum alloy blank with diameter and thickness leaving more than 10mm allowance, after heat treatment, select the cutting tool and cutting parameters for aluminum alloy;Remove the allowance of the inner and outer circle of the circular column blank, when the outer circle of the circular column workpiece is machined to 2mm allowance on single side, the inner circle hole size is precisely machined in place under the condition that the allowance is left on the outer circle surface to ensure that the workpiece has a certain rigidity, and evenly distributed holes are machined on the side surface of the circular column workpiece;Prepare the special fixture for the inner lining of engine aluminum alloy split flow ring workpiece machining, the positioning point on the cone platform shape is in close fit with the inner edge of the engine aluminum alloy split flow ring;The circular column workpiece with accurate inner and outer circle is cut into segments by slow wire cutting method, the angular precision control machining parameter is ensured to prevent the deformation of the part;Finally, the workpiece profile is precisely machined on the fixture.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engines, in particular to a manufacturing method of a split casing of a large-diameter thin-wall aluminum alloy part of an aero-engine. BACKGROUND

[0002] The ultra-thin-wall and easily-deformed aluminum alloy multi-part split flow ring is a double-duct split flow ring of a turbofan engine, which is used for the split flow of the inner and outer ducts of a low-pressure compressor inlet duct, and can make the engine more energy-saving, environment-friendly and efficient.

[0003] The part is an aluminum alloy large-diameter thin-wall structure, which is designed as a part of a circular arc conical ring shape of six identical split flow rings for quick and convenient assembly, and then is assembled into a whole conical ring or circular truncated cone ring, so generally the whole ring is cut into six parts, and the whole ring has a larger volume (large diameter and thin wall thickness), and therefore has a higher difficulty in machining and manufacturing, and the problem of large deformation of the inner and outer circles after being cut into six parts is a key difficulty in machining.

[0004] The machining difficulty of the part is that the part has a large volume, a diameter of more than φ1650mm, a thinnest wall thickness of 2.5mm at the two port portions, a cylindricality requirement of 0.1 (an error of any one circular surface is less than 0.1mm), and the aluminum alloy part is assembled into a whole ring by six identical parts (see Figure 1 ); the control of the deformation of the inner and outer circles after being cut into six parts is a core difficulty in machining, and a special jig is needed to assist in manufacturing. At present, there is no report on the machining of such a material part. SUMMARY

[0005] The purpose of the present application is to provide a whole machining method of an aluminum alloy split flow ring of an aero-engine, select a special chip cutter for aluminum alloy and reasonable cutting parameters; reduce the cutting stress of the part in the machining process to control and reduce the deformation of the part, and achieve the final circular truncated cone part.

[0006] The technical scheme of the present application is: a whole machining method of an aluminum alloy split flow ring of an aero-engine, the diameter of the aluminum alloy split flow ring of the aero-engine is more than φ1650mm, and the thinnest wall thickness of the two port portions is 2.5mm; a circular ring cylindrical aluminum alloy blank with a diameter and a thickness of more than 10mm is selected, heat treated, and after heat treatment, a special chip cutter for aluminum alloy and cutting parameters are selected; the inner and outer circle excess of the circular ring cylindrical blank is removed, the cutting stress of the part in the machining process is reduced to control and reduce the deformation of the part, and the final circular truncated cone workpiece is achieved.

[0007] When the outer circle of the circular column workpiece is machined to a single side 2mm allowance, the inner hole size is precisely machined in place under the condition that the outer circle surface is left with allowance to ensure that the workpiece has a certain rigidity, and uniform distribution holes (circumferential holes) are machined on the side surface of the circular column workpiece; a special fixture for machining the inner lining of the engine aluminum alloy split flow ring workpiece is prepared, the special fixture is provided with a taper outer shape positioning point which is tightly fitted with the inner edge of the engine aluminum alloy split flow ring; therefore, the workpiece is fixed by using a bolt which passes through the uniform distribution holes on the side surface of the circular column (circular truncated cone) workpiece which have been drilled and milled in place and the taper outer shape positioning point (nut hole), so that the workpiece and the fixture form a precise multi-fixed-point positioning tool fixture after being fixed, and only the outer circle (column side) of the circular column is exposed after the workpiece is installed on the special tool fixture, and the shape and position tolerance of the workpiece is adjusted to ensure that it meets the design requirements; the outer circle is precisely turned, and the outer circle cannot be tightly fixed during precise turning; the circular column workpiece with accurate inner and outer circles is cut in sections by using a slow wire cutting method, the angular accuracy is controlled by processing parameters, and the deformation of the part is prevented; finally, the outer shape of the workpiece is precisely machined on the special fixture, and the dimensions are detected online to ensure that the drawings meet the requirements.

[0008] Further, the tip R of the chip cutting tool is 0.4-0.8.

[0009] Further, the 10mm allowance is removed in layers, and the removal amount of each layer is 2mm respectively.

[0010] Further, after the outer shape is roughly turned to leave a 10mm allowance on one side, stress relief heat treatment is carried out: vacuum furnace 160℃ for 3 hours, air cooling; 150-180℃ for 60-600min.

[0011] The flow ring machining process route is: A10 rough turning of the outer shape, leaving a 10mm allowance on one side → A20 stress relief heat treatment (vacuum furnace 160℃ for 3 hours, air cooling, heat treatment range 150-180℃ for 60-600min) → A30 turning of the reference → A40 semi-precision turning of the inner and outer circles (leaving an 8mm-6mm allowance on one side) → A50 semi-precision turning of the inner and outer circles (leaving a 4mm-2mm allowance on one side) → A60 turning of the reference → A70 precision turning of the inner hole to the drawing requirement, i.e. 0 allowance → A80 drilling and milling of the circumferential holes and scribing → A90 semi-precision turning of the outer circle on the tool (leaving a 2mm allowance on one side) → A100 scribing → A110 wire cutting → A120 precision turning of the flange and the outer circle on the tool to place, i.e. 0 allowance → A130 trimming → A140 fluorescent inspection → A150 marking → A160 sulfuric acid anodizing → A170 final inspection.

[0012] Further, the workpiece speed during turning is 12-13 / min, and the feed is 0.10-0.12mm / r.

[0013] Beneficial effect: the overall machining method of the aluminum alloy split flow ring, deformation and sticking of the cutter are prone to occur in the aluminum (titanium) alloy machining process, special chip cutters for aluminum alloy and reasonable cutting parameters need to be selected, uniform removal is needed for aluminum alloy machining, and cutting stress generated in the machining process of the part is reduced as much as possible, because the final part structure cannot be flanged, a precise multi-positioning point model tooling is adopted, multi-point positioning, the contact area is small, the positioning accuracy is high, the heat treatment plus layer-by-layer turning eliminates the error of workpiece machining deformation, the fastening is convenient and more reliable, and the compression force is strong. Mainly the overall machining plus wire cutting and then fine turning, the use of special fixtures leaves space for the workpiece to release stress at the local stress concentration during machining, which effectively distributes the workpiece deformation caused by uneven stress distribution due to machining stress. This is the key to the success of the thin-walled part machining. Through verification, it is concluded that the workpiece fully meets the design requirements, the scheme is feasible, and the high precision and non-deformation requirements of the drawing are fully met. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a structure diagram of the workpiece of the present application;

[0015] Figure 2 is a structure diagram of the workpiece of the present application;

[0016] Figure 3 is Figure 2 a longitudinal sectional view;

[0017] Figure 4 is a main process diagram of the present application. The hatched area in the machining process diagram is the excess amount area. DETAILED DESCRIPTION

[0018] The machining implementation process scheme of the aluminum alloy split flow ring of the aero-engine is as follows: the workpiece 1, the clamp cylinder 2, the (M8) bolt 3, and the nut hole 4 on the clamp cylinder.

[0019] The typical material of the part is aluminum alloy with the brand 2219, and the material characteristics are prone to deformation during machining. Special chip cutters for aluminum alloy and reasonable cutting parameters need to be selected. In order to reduce the cost, the blank allowance and the product shape are not uniform, so the programming difficulty is increased, and a special program needs to be prepared to uniformly remove the inner and outer cylindrical allowance of the cylindrical blank during machining, and the cutting stress generated in the machining process of the part is reduced as much as possible to control and reduce the part deformation, so as to meet the drawing requirements (see Table 1).

[0020] Because the part deformation is large after the whole ring is split, the inner and outer circular position precision is high, so the workpiece material needs to be removed many times uniformly, so the single side 10mm allowance is removed layer by layer, and the single side allowance of 10mm, 8mm, 6mm, 4mm and 2mm is left respectively (the single side allowance refers to the superimposed amount of double sides, which is the common saying in the industry, that is, 1mm allowance of the inner face and the outer face is turned respectively each time). When the inner and outer circles of the part are machined to the single side 2mm state, the outer circle allowance ensures that the workpiece has a certain rigidity, and the inner hole sizes are finished in place and uniformly distributed circumferential holes (bolt holes) are machined. Because the workpiece cannot be tightly fixed when the outer circle is finally finished, a special precision multi-control point positioning fixture is used, which is seen in Figure 2 After the workpiece is installed on the special fixture, the shape and position tolerances of the workpiece are adjusted to meet the drawing requirements, which is seen in Figure 3 .

[0021] The workpiece is cut into segments by the slow wire cutting method, the angular precision is controlled, and the machining parameters are prevented from deforming the part. Finally, the outer shape of the part is finished, and the dimensions are detected to meet the drawing requirements.

[0022] The important node is that when the outer circle of the part is machined to the single side 2mm allowance, the outer circle surface is left with 1mm allowance to ensure that the workpiece has a certain rigidity, and then the inner hole sizes are finished in place, and the circumferential holes (distributed holes required by the design drawing) are machined on the side surface of the cylindrical workpiece. When the outer circle is finally finished, the inner lining special fixture (vertical lathe) of the engine aluminum alloy split flow ring is tightly fixed; the conical outer shape of the special fixture is tightly fitted with the fixed control points (nut holes) of the inner cavity of the engine aluminum alloy split flow ring. Therefore, the positioning fixture with precise multi-fixed control points (screw nuts on the fixture) is formed by using bolts passing through the uniformly distributed holes which have been milled in place on the side surface of the cylinder (conical cylinder), and the workpiece is installed on the special fixture. After the adjustment, the shape and position tolerances of the workpiece after positioning meet the process requirements. The principle and characteristics of the special tooling: precise multi-positioning point model tooling, the characteristics of multi-point positioning are small contact area, high positioning accuracy, elimination of workpiece machining deformation error, convenient and reliable fastening, strong pressing force, and reliable fixation of the workpiece.

[0023] The fixture (tooling) leaves space for the workpiece to release deformation in local stress concentration during machining, which effectively disperses the uneven stress distribution caused by machining stress and forms workpiece deformation. This is the key to the success of the thin-walled part machining. Especially for the support and accuracy of the flangeless part of the present application (the outer side of the tooling has several fixed control nut holes distributed on three or more side planes, the nut holes 4 on the side plane of the fixture cylinder are matched with bolts, and the turning accuracy of the inner hole of the workpiece of the present application is matched). Through verification, it is concluded that the tooling design is effective, and the workpiece fully meets the design requirements. The plan is feasible. The inner side plane of the fixture cylinder nut hole 4 is completely matched with the plane. Thus, the positioning is accurate.

[0024] The workpiece is cut into segments by the slow wire cutting method, the angular accuracy is controlled, and the machining parameters are controlled to prevent part deformation; finally, the part shape is finished, the matching uniformly distributed bolts are countersunk bolts, which can ensure that each petal is fixed, and the final precision of the finish turning can be guaranteed. The subsequent feed is less, and the R of the tool tip is smaller.

[0025] The tool tip R of the turning tool is 0.4-0.8, and each dimension is detected by an online detector after turning to ensure that it meets the drawing requirements;

[0026] 10mm single-sided allowance is removed in layers, with a removal amount of 2mm per layer, divided into 5 times. Single-sided allowance refers to the superimposed amount of both sides, which is a common term in the industry, that is, the inner surface and the outer surface are turned 1mm in each time.

[0027] Split ring processing process route: (see Figure 4 The number marked is the process number):

[0028] A10 rough turning shape (single-sided allowance of 10-8mm) → A20 stress relief heat treatment → A30 turning reference → A40 half-precision turning one end (single-sided allowance of 6-4mm) → A50 half-precision turning the other end (single-sided allowance of 4-2mm) → A60 turning reference → A70 precision turning inner hole → A80 drilling and milling circumferential holes and scribing → A90 half-precision turning outer circle (single-sided allowance of 2mm) → A100 scribing → A110 wire cutting → A120 precision turning flange and outer circle → A130 trimming → A140 fluorescence inspection → A150 marking → A160 sulfuric acid anodizing → A170 final inspection.

[0029] Control of important node process parameters:

[0030] Table 1

[0031]

[0032]

[0033] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that changes, modifications, substitutions and variations can be made by those skilled in the art without departing from the spirit and scope of the present application.

Claims

1. A method for integral machining of an aluminum alloy split flow ring of an aero-engine, the aluminum alloy split flow ring having a diameter of φ1650mm or more and a wall thickness of 2.5mm at the thinnest part of the two end port portions; characterized in that, The circular column aluminum alloy blank with a diameter and thickness leaving a 10mm or more excess is selected, and after heat treatment, an aluminum alloy chip cutter and cutting parameters are selected; the inner and outer circle excess of the circular column blank is removed to reduce the cutting stress generated in the machining process of the part, thereby controlling and reducing the deformation of the part, and finally achieving the circular truncated column workpiece; When the outer circle of the circular column workpiece is machined to a single side 2mm excess, the inner circle hole size is precisely machined in place under the condition that the excess on the outer circle surface ensures that the workpiece has a certain rigidity, and evenly distributed holes are machined on the side surface of the circular column workpiece; a special fixture for machining the inner lining of the engine aluminum alloy split flow ring workpiece is prepared, the special fixture is provided with a taper outer shape positioning point which tightly fits the inner edge of the engine aluminum alloy split flow ring; the bolt passes through the evenly distributed holes on the side surface of the circular column workpiece which have been drilled and milled in place and the taper outer shape positioning point and is fixed; after fixing, a precise multi-fixed-point positioning fixture is formed, and after the workpiece is installed on the special fixture, only the outer circle of the circular column is exposed, and the shape and position tolerances of the workpiece are adjusted to meet the design requirements; the circular column workpiece with qualified inner and outer circle accuracy is cut in sections by using the slow wire cutting method, the angular accuracy is controlled, the machining parameters are prevented, and the deformation of the part is prevented; finally, the outer shape of the workpiece is precisely machined on the special fixture, and the dimensions are detected online to ensure the drawing requirements.

2. The method of claim 1, wherein the method further comprises, The cutting tool tip R is 0.4-0.

8.

3. The method of claim 1, wherein the method further comprises, The 10mm excess is removed in layers, and each layer is removed by 2mm.

4. The method of claim 1, wherein the method further comprises, After rough turning the outer shape to leave a 10mm excess on one side, stress relief heat treatment is performed: vacuum furnace 150-180℃, 60-600min.

5. The method of claim 1, wherein the method further comprises, The flow ring machining process route is: A10 rough turning the outer shape, leaving a 10mm excess on one side → A20 stress relief heat treatment, vacuum furnace 160℃ for 3 hours, air cooling → A30 turning the reference → A40 semi-precision turning the inner and outer circles, leaving a 8mm-6mm excess on one side → A50 semi-precision turning the inner and outer circles, leaving a 4mm-2mm excess on one side → A60 turning the reference → A70 precision turning the inner hole to the drawing requirements, i.e. 0 excess → A80 drilling and milling the circumferential holes and scribing → A90 semi-precision turning the outer circle on the tooling, leaving a 2mm excess on one side → A100 scribing → A110 wire cutting → A120 precision turning the flange and outer circle on the tooling to place, i.e. 0 excess → A130 trimming → A140 fluorescence inspection → A150 marking → A170 final inspection.

6. The method of claim 1, wherein the method further comprises, The workpiece speed during turning is 12-13r / min, and the feed is 0.10-0.12mm / r.

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