A machining method for flange edges of large thin-walled parts

Abstract

This invention discloses a machining method for flange edges of large thin-walled parts, comprising the following steps: rough turning of the outer diameter of the flange edge, leaving a diameter allowance; rough turning of the upper end face of the flange edge, leaving an end face allowance; rough turning of the lower end face of the flange edge, leaving an end face allowance; finish turning of the outer diameter of the flange edge to the final design size; semi-finish turning of the upper end face of the flange edge, and then measuring the radial deformation of the upper end face of the flange edge; using a slanted tool path to eliminate the measured deformation, and finish turning the upper end face of the flange edge to the final design size; semi-finish turning of the lower end face of the flange edge, and then measuring the radial deformation of the lower end face of the flange edge; using a slanted tool path to eliminate the measured deformation, and finish turning the lower end face of the flange edge to the final design size. This invention achieves the goal of ensuring that the flatness and thickness tolerance of the flange edge meet the requirements without using special fixtures to assist in supporting the inner cavity of large thin-walled parts.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of machining, and particularly relates to a machining method for a flange edge of a large thin-walled part. BACKGROUND

[0002] A large thin-walled part of an aero-engine is generally welded from a front flange edge, a rear flange edge, a cylinder, a mounting seat and the like, as shown in the figure, after being combined and welded, the large thin-walled part needs to be machined through turning, milling and the like, and first of all, the flange edge is machined. Figure 1 The radial width of the flange edge is large, generally 20-40 mm, the thickness of the flange edge is only 3-5 mm, the machining ensures that the flatness of the end face of the flange edge is not greater than 0.02 mm, and the thickness tolerance is not greater than 0.05 mm.

[0003] Since the wall thickness of the cylinder of the large thin-walled part is generally 1-2 mm, the rigidity of the part is poor, and the part is easy to deform in machining, a machining deformation diagram is shown by a dashed line in the figure, and the parallelism and thickness of the flange edge are difficult to ensure. Figure 2 In order to meet the size requirements, a special auxiliary clamp is often used to support the inner profile of the thin-walled part to enhance the rigidity of the part and reduce the deformation amount in machining, but tool letting still exists in machining, and the part needs to be walked through multiple times to reduce the tool letting amount to meet the machining requirements, and the machining efficiency is not high. SUMMARY

[0004] In order to solve the above technical problems, the present application aims to provide a machining method for a flange edge of a large thin-walled part, which can meet the flatness and thickness tolerance requirements of the flange edge in the machining process without using a special auxiliary supporting clamp, and further, can realize high-efficiency machining of the flange edge of the large thin-walled part.

[0005] The present application adopts the following technical scheme:

[0006] A machining method for a flange edge of a large thin-walled part, comprising the following steps,

[0007] Step 1, rough turning of the outer circle of the flange edge, with a diameter allowance;

[0008] Step 2, rough turning of the upper end face of the flange edge, with an end face allowance;

[0009] Step 3, rough turning of the lower end face of the flange edge, with an end face allowance;

[0010] Step 4, fine turning of the outer circle of the flange edge to the final design size;

[0011] Step 5, semi-finish the upper end face of the flange, and then measure the radial deformation of the upper end face of the flange;

[0012] Step 6, eliminate the deformation measured in step 5 by adopting the oblique line tool path, and finish the upper end face of the flange to the final design size;

[0013] Step 7, semi-finish the lower end face of the flange, and then measure the radial deformation of the lower end face of the flange;

[0014] Step 8, eliminate the deformation measured in step 7 by adopting the oblique line tool path, and finish the lower end face of the flange to the final design size.

[0015] Further, the step 1 further comprises,

[0016] Clamp the large thin-walled part to be machined on the workbench of the numerical control lathe, align the center of the flange with the center of the workbench, and press the large thin-walled part on the workbench.

[0017] Further, when the center of the flange is aligned with the center of the workbench and the large thin-walled part is pressed, the workpiece coordinate system is set.

[0018] As an option, in steps 5 and 7, the radial deformation of the upper end face of the flange and the lower end face of the flange is measured by using a dial gauge.

[0019] As an option, in steps 5 and 7, the height difference between the two end points in the radial direction of the flange is used as the radial deformation. When the radial length of the flange is short, the above method is used.

[0020] As an option, in steps 5 and 7, a radial line is obtained by connecting the two end points in the radial direction of the flange, the radial line is divided into several equal length line segments, and the height difference between one end point and each division point to the other end point is used as the radial deformation to form a sequence of radial deformations. When the radial length of the flange is long, the above method is more accurate and avoids the case that the deformation is inconsistent in the same radial length, which is closer to the actual deformation.

[0021] As an option, in steps 2, 3, 5, 6, 7 and 8, the tool path is from the outside to the inside of the flange. When machining, the cutting force on the part is towards the center of the part, avoiding machining shock, which is more beneficial to the machining of the flange.

[0022] As an option, in steps 6 and 8, the flatness of the upper end face of the flange and the lower end face of the flange is controlled to be less than the design requirement, and the thickness tolerance of the flange is less than the design requirement.

[0023] Compared with the prior art, the present application has the following characteristics:

[0024] (1) Without using special fixtures to support the inner surface of large thin-walled parts, the flange edge processing method of the present invention solves the problems of poor part rigidity and deformation during processing when processing flange edges of large thin-walled parts, saves the investment of special fixtures in the development of new products, and speeds up the development of new products.

[0025] (2) Since no special fixtures are used, the scope of application of the present invention is wider and can be extended to the precision machining of the contours of large thin-walled parts, thereby improving machining efficiency and stability. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a large thin-walled part in this invention;

[0027] Figure 2 This is a schematic diagram of flange edge machining deformation;

[0028] Figure 3 This is a schematic diagram of the tool path for roughing and semi-finishing.

[0029] Figure 4 This is a schematic diagram illustrating the radial deformation of the flange edge in this invention.

[0030] Figure 5 This is a schematic diagram of the tool path for the upper and lower oblique lines in the precision machining of the flange edge according to the present invention;

[0031] In the diagram: 1. Front flange edge; 2. Thin-walled cylinder; 3. Rear flange edge; 4. Upper end face of flange edge; 5. Lower end face of flange edge. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0033] like Figure 1 As shown, a large thin-walled part with a flange structure is shown. The part includes a thin-walled cylinder 2, with a front flange 1 and a rear flange 3 at both ends along the axial direction of the thin-walled cylinder 2. Both the front flange 1 and the rear flange 3 include an upper flange face 4 and a lower flange face 5 to be processed.

[0034] like Figure 2 As shown, for Figure 1 For large, thin-walled parts, through sample production and theoretical analysis, it can be determined that the upper end face 4 and lower end face 5 of the front flange 1 (or rear flange 3) will exhibit defects during machining. Figure 2 The deformation is shown by the dashed line. (Borrowing...)Figure 4 To illustrate, Figure 4 In the prior art, compared with point A, point D on the front flange edge 1 is far away from the thin-walled cylinder 2, and the rigidity of point D is poor relative to that of point A. When machining, the relief amount of point D is larger than that of point A. The deformation of the upper and lower end faces of the flange edge must occur in the manner shown by the dashed line in the figure, which can be verified by test. Figure 2 In the prior art, compared with point A, point D on the front flange edge 1 is far away from the thin-walled cylinder 2, and the rigidity of point D is poor relative to that of point A. When machining, the relief amount of point D is larger than that of point A. The deformation of the upper and lower end faces of the flange edge must occur in the manner shown by the dashed line in the figure, which can be verified by test.

[0035] To solve the above problems, the present application designs a machining method for controlling the flatness and thickness of the front flange edge 1 and the rear flange edge 3 without using special fixtures to support the thin-walled cylinder 2.

[0036] The basic idea of the present application is as follows: the large thin-walled part is clamped on the worktable of a numerical control lathe, and the turning process is divided into rough machining, semi-finish machining and finish machining. The outer circle of the flange edge is first rough-turned, then the upper end face 4 of the flange edge is rough-turned, and finally the lower end face 5 of the flange edge is rough-turned. The outer circle of the flange edge is finish-turned, and the upper end face 4 and the lower end face 5 of the flange edge are semi-finish-turned. The deformation amounts of the upper end face 4 and the lower end face 5 of the flange edge along the radial direction are measured, the upper end face 4 of the flange edge is finish-turned by using the inclined line feed method, and the lower end face 5 of the flange edge is finish-turned by using the inclined line feed method.

[0037] The machining methods of the front flange edge 1 and the rear flange edge 3 are the same, and the specific machining method steps are as follows:

[0038] Step 1. The large thin-walled part to be machined is clamped on the worktable of a numerical control lathe, the center of the flange edge is aligned with the center of the worktable, and the large thin-walled part is pressed tightly on the worktable (when the front flange edge 1 is to be machined first, the unprocessed rear flange edge 3 is pressed tightly on the lathe worktable, and after the front flange edge 1 is machined, the front flange edge 1 is pressed tightly on the lathe worktable. The pressing operation does not cause the flatness and thickness tolerance of the machined flange edge to change);

[0039] Step 2. Set the machining workpiece coordinate system;

[0040] Step 3. Rough-turn the outer circle of the flange edge, leaving a 1mm allowance;

[0041] Step 4. Rough-turn the upper end face 4 of the flange edge, leaving a 0.4mm allowance;

[0042] Step 5. Rough-turn the lower end face 5 of the flange edge, leaving a 0.4mm allowance;

[0043] Step 6. Finish-turn the outer circle to the final design size;

[0044] Step 7. Semi-finish-turn the upper end face 4 of the flange edge, leaving a 0.2mm finish machining allowance, and measure the radial deformation amount of the upper end face 4 of the flange edge by using a dial indicator;

[0045] Step 8. Finish machining the upper end face 4 of the flange edge, modify the radial deformation value into the finishing program, adopt the slant line feed method to eliminate the deformation in machining, and finish machining the upper end face 4 of the flange edge to the final design size;

[0046] Step 9. Semi-finish machining the lower end face 5 of the flange edge, leave 0.2mm finishing allowance, and measure the radial deformation of the lower end face 5 of the flange edge with a dial gauge;

[0047] Step 10. Finish machining the lower end face 5 of the flange edge, modify the radial deformation value into the finishing program, adopt the slant line feed method to eliminate the deformation in machining, and finish machining the lower end face 5 of the flange edge to the final design size.

[0048] In steps 7 and 9, measure the radial deformation of the upper end face 4 or the lower end face 5 of the flange edge with a dial gauge. If the radial width of the flange edge is less than 20mm, for example, Figure 4 take the point A of the upper end face of the flange edge as the zero point, and measure the height difference value of the point D of the flange edge relative to the point A as R1. If the width of the flange edge is between 20mm and 40mm, divide the flange edge into 3-4 segments with equal length line segments of length L, and measure the height difference values of the points D, C, B relative to the point A as R1, R2, R3.

[0049] In steps 8 and 10, adopt the slant line feed method to eliminate the deformation in machining during finish machining, and the slant line feed value is the height difference data (R1 or R1, R2, R3) measured by the dial gauge in the radial direction of the flange edge.

[0050] In steps 8 and 10 above, the flatness of the finish machined flange edge is controlled to be within 0.01mm, and the thickness tolerance of the flange edge is controlled to be within 0.02mm.

[0051] For example, for the flange edge in Figure 4 , the partial program segment for finishing the upper end face 4 of the flange edge is as follows:

[0052] R1=0.06; the height difference value of the point D relative to the point A;

[0053] R2=0.03; the height difference value of the point C relative to the point A;

[0054] R1=0.01; the height difference value of the point B relative to the point A;

[0055] G01 X D Z=-R1 F0.2;

[0056] X C Z=-R2;

[0057] X B Z=-R3;

[0058] XA Z = 0;

[0059] ...

[0060] The description herein of the application in its detailed form is not intended to limit the application to the particular form described. It will be apparent to those skilled in the art that various modifications can be made within the scope of the application as defined by the appended claims and that the application is not limited to the described embodiments.

Claims

1. A method for machining a flange edge of a large thin-walled part, characterized in that: The large thin-walled part to be processed is clamped on the worktable of the numerical control lathe, the center of the flange edge is aligned with the center of the worktable, and the large thin-walled part is pressed on the worktable, and the pressing position is the front flange edge or the rear flange edge of the large thin-walled part, and the processing method comprises the following steps, Step 1, rough turning the outer circle of the flange edge, leaving a diameter allowance; Step 2, rough turning the upper end face of the flange edge, leaving an allowance on the end face; Step 3, rough turning the lower end face of the flange edge, leaving an allowance on the end face; Step 4, finish turning the outer circle of the flange edge to the final design size; Step 5, semi-finish turning the upper end face of the flange edge, and then measuring the radial deformation of the upper end face of the flange edge; Step 6, using the inclined line feed method to eliminate the deformation measured in step 5, and finish turning the upper end face of the flange edge to the final design size; Step 7, semi-finish turning the lower end face of the flange edge, and then measuring the radial deformation of the lower end face of the flange edge; Step 8, using the inclined line feed method to eliminate the deformation measured in step 7, and finish turning the lower end face of the flange edge to the final design size; In steps 5 and 7, a radial line is obtained by connecting the two end points in the radial direction of the flange edge, the radial line is divided into a plurality of equal length line segments, and the height difference between one end point and each division point to the other end point is taken as the radial deformation, forming a sequence of radial deformations; In steps 2, 3, 5, 6, 7 and 8, the tool is fed from the outside to the inside of the flange edge.

2. The method of claim 1, wherein: After aligning the center of the flange edge with the center of the worktable and pressing the large thin-walled part, the workpiece coordinate system is set.

3. The method of claim 1, wherein: In steps 5 and 7, the radial deformation of the upper end face of the flange edge and the lower end face of the flange edge is measured by using a dial indicator.

4. The method of claim 1, wherein: In steps 5 and 7, the height difference between the two end points in the radial direction of the flange edge is taken as the radial deformation.

5. The method of claim 1, wherein: In steps 6 and 8, the flatness of the upper end face of the flange edge and the lower end face of the flange edge is controlled to be less than the design requirement, and the thickness tolerance of the flange edge is less than the design requirement.

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