A method for controlling the wall thickness of a hollow structural blade

Abstract

The application discloses a kind of hollow structure blade wall thickness control methods, belong to hollow structure blade manufacturing technical field, comprising the following steps: step 1, determine the section position of the profile wall thickness to be detected, and the number of section selection measurement points;Step 2, according to section position and specific measurement point, the wall thickness value of each measurement point is detected and recorded;Step 3, according to the wall thickness value of each measurement point, the wall thickness difference and the wall thickness change rate are calculated;Step 4, according to the wall thickness difference of each measurement point and the change rate of the wall thickness of each measurement point, the position of the original point is corrected when the blade profile is precisely milled, and the blade wall thickness is corrected.The control of blade profile wall thickness is realized, and the problem of wall thickness out-of-tolerance in the processing of closed cavity cavity blade is solved.

Description

Technical Field

[0001] This invention belongs to the field of hollow structure blade manufacturing technology, specifically relating to a method for controlling the wall thickness of hollow structure blades, applicable to the processing of hollow structure blade-like parts for aero engines. Background Technology

[0002] Advances in aero-engine design technology have led to changes in engine blade structure, shifting from solid to hollow designs. This hollow blade structure achieves weight reduction and better meets engine design requirements. Solid blades are manufactured by machining forged blanks, a process with mature datum selection and surface machining techniques, resulting in stable product quality. Hollow blades, on the other hand, have two halves that are machined within the inner cavity and then welded together to form a single hollow blade. Because the inner cavity is a closed space, datum alignment is difficult during outer surface machining, making it challenging to guarantee the wall thickness between the inner and outer surfaces. Furthermore, the wall thickness is difficult to directly measure during outer surface machining, hindering timely adjustments and making it difficult to ensure consistent blade profile wall thickness. Summary of the Invention

[0003] This invention provides a method for controlling the wall thickness of hollow blades, thereby achieving control over the wall thickness of the blade profile and solving the problem of excessive wall thickness during the processing of closed-cavity hollow blades.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for controlling the wall thickness of hollow blades includes the following steps:

[0006] Step 1: Determine the cross section for measuring the wall thickness of the blade profile, and select a measurement point on the cross section;

[0007] Step 2: Measure and record the wall thickness at each measurement point;

[0008] Step 3: Calculate the wall thickness difference and wall thickness change rate of each section based on the wall thickness at each measurement point;

[0009] Step 4: Based on the wall thickness difference of each section and the rate of change of the wall thickness of each section, correct the position of the origin during the finishing of the blade profile, and correct the blade wall thickness.

[0010] Furthermore, in step 1, each cavity in the blade has at least one cross-section that is the cross-sectional position of the detection surface.

[0011] Furthermore, in step 1, there are at least 6 measurement points for each cross section, and at least 3 measurement points for both the blade basin side profile and the blade back side profile.

[0012] Furthermore, in step 2, the wall thickness at each measurement point is detected using ultrasonic testing.

[0013] Furthermore, in step 2, the measurement is performed along the normal of the measurement point.

[0014] Furthermore, in step 3, the formula for calculating the wall thickness difference is: α = H_bowl - H_back, where α is the wall thickness difference, H_bowl is the leaf bowl thickness at the measurement point, and H_back is the leaf back thickness at the measurement point.

[0015] Furthermore, in step 3, the formula for calculating the wall thickness change rate is: β=arc tan(H_bowl-H_back) / L, where β is the wall thickness change rate, H_bowl is the blade bowl thickness at the measurement point, H_back is the blade back thickness at the measurement point, and L is the distance between points on the cross section near both sides of the cavity.

[0016] Furthermore, in step 4, corrections are made using the following method:

[0017] When the wall thickness difference α≤0, the origin of the CNC milling program for the profile is shifted towards the back of the blade by half of the average wall thickness difference of all sections.

[0018] When the wall thickness difference α≥0, the origin of the CNC milling program for the profile is shifted towards the blade head direction by half of the average wall thickness difference of all sections.

[0019] When the wall thickness change rate β≤0, rotate the origin of the CNC milling program around the stacking axis counterclockwise to half the average wall thickness change rate of all sections;

[0020] When the wall thickness change rate β≥0, the average wall thickness change rate of all sections is half of the value when the origin of the CNC milling program is rotated clockwise around the stacking axis.

[0021] Furthermore, after step 4 is completed, the wall thickness is checked.

[0022] Furthermore, if the test results do not meet the requirements, proceed to step 2 until the wall thickness meets the requirements.

[0023] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0024] This invention provides a method for controlling the wall thickness of the hollow portion during the machining of hollow blades. By analyzing the hollow blade manufacturing process, the key point for wall thickness control is identified as the precision machining of the blade profile. Before the precision machining of the blade's outer profile, selected sections and measurement points are inspected to re-measure the blade's precision machining benchmark. The wall thickness of the blade's base and back sides is measured and analyzed to determine a compensation scheme for the precision milling of the profile, thereby achieving control over the blade profile wall thickness. This method solves the problem of wall thickness deviation during the machining of hollow blades with enclosed internal cavities, effectively improving the wall thickness qualification rate of this type of blade.

[0025] Furthermore, in step 2, the measurement is performed along the normal of the measurement point, which can reduce the measurement error caused by the curvature of the surface. Attached Figure Description

[0026] Figure 1a This is a schematic diagram of the hollow blade's external structure;

[0027] Figure 1b This is a cross-sectional view of a hollow blade;

[0028] Figure 2 This is a schematic diagram of the external shape for precision machining datum inspection;

[0029] Figure 3 This is a schematic diagram of the KK section inspection for precision machining datum checks;

[0030] Figure 4 This is the F-direction view for finishing datum inspection;

[0031] Figure 5 This is a schematic diagram of the blade's external profile requirements;

[0032] Figure 6 This is a schematic diagram showing the distribution of measurement points.

[0033] In the attached diagram: 1. Leaf blade; 2. Cavity; 3. Leaf basin; 4. Leaf underside. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0035] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0036] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or may be interposed with another element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or may be interposed with another element. The terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., used herein to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0038] Reference Figures 1a to 6 A method for controlling the wall thickness of hollow blades is implemented through the following steps:

[0039] (1) Inspection section and measurement points:

[0040] Reference Figures 1a to 3 According to the overall process of blade 1, the wall thickness of relevant sections is measured before the precision milling process. Based on the structural characteristics of hollow blades, the locations of the sections to be inspected are selected, following the principle that at least one section should be measured for each cavity 2; measurement points should be selected for each section. The number of sections to be inspected is 3 to 5; each section has ≥6 measurement points, with two measurement points located near the two sides of the cavity and one measurement point located on the central axis of the cavity. The number of measurement points on both the blade head side and blade back side sections should be no less than 3.

[0041] (2) Ultrasonic testing:

[0042] An ultrasonic wall thickness gauge was used to measure and record the wall thickness at each measurement point according to the cross-sectional location and specific measurement points. Before using the ultrasonic wall thickness gauge, the instrument should be calibrated using a standard block. Since the blade profile is a complex spatial curved surface, measurements should be taken along the normal direction of the measurement point to reduce measurement errors caused by the surface curvature.

[0043] (3) Data Analysis:

[0044] The wall thickness values ​​at each measurement point on the blade cross-section are analyzed, and the wall thickness difference α = (H_plate - H_back), where H_plate is the thickness of blade plate 3 and H_back is the thickness of blade back 4, and the wall thickness change rate β = arc tan(H_plate - H_back) / L, (L is the point on the cross-section closest to both sides of the cavity (i.e., Figure 6 (The distance between midpoint 1 and point 3).

[0045]

[0046] 1) Wall thickness difference α:

[0047] When the wall thickness difference α≤0, that is, the wall thickness of the leaf basin side profile is less than the wall thickness of the leaf back side profile;

[0048] When the wall thickness difference α≥0, that is, the wall thickness of the leaf basin side profile is greater than the wall thickness of the leaf back side profile;

[0049] 2) Wall thickness at various points along the cross-section (Hbasin, Hback):

[0050] When H_bowl1≤H_bowl2≤H_bowl3 and H_back1≥H_back2≥H_back3, that is, when the wall thickness change rate β≤0, the wall thickness of the blade's bowl side profile increases from the leading edge to the trailing edge, and the wall thickness of the back side profile decreases from the leading edge to the trailing edge.

[0051] When H_bowl1≥H_bowl2≥H_bowl3 and H_back1≤H_back2≤H_back3, that is, when the wall thickness change rate β≥0, the wall thickness of the blade's basin side profile decreases from the leading edge to the trailing edge, and the wall thickness of the back side profile increases from the leading edge to the trailing edge.

[0052] (4) Precision milling of the blade profile:

[0053] To address the wall thickness difference α detected by ultrasonic testing and the specific variations in wall thickness at various points, corrections were made during the precision milling of the blade profile by optimizing the CNC machining program. A blade surface roughness of less than 1.6 μm was obtained using a material removal method.

[0054] 1) Wall thickness difference α:

[0055] For a single measurement section:

[0056] When the wall thickness difference α≤0, that is, the wall thickness of the blade basin side profile is less than or equal to the wall thickness of the blade back side profile, the origin of the CNC milling program for the profile is shifted α / 2 towards the blade back direction.

[0057] When the wall thickness difference α≥0, that is, the wall thickness of the blade basin side profile is greater than or equal to the wall thickness of the blade back side profile, the origin of the CNC milling program for the profile is shifted α / 2 towards the blade basin direction.

[0058] Taking into account the measurement results of all sections, half of the average wall thickness difference of all sections is used as the correction value for program translation.

[0059] 2) The rate of change of wall thickness β at each point on the cross section, for a single measurement cross section:

[0060] When the wall thickness change rate β≤0, the wall thickness of the blade basin side profile increases from the leading edge to the trailing edge, and the wall thickness of the back side profile decreases from the leading edge to the trailing edge; rotate the origin of the CNC milling program of the profile counterclockwise by β / 2 around the stacking axis.

[0061] When the wall thickness change rate β≥0, the wall thickness of the blade basin side profile decreases from the leading edge to the trailing edge, while the wall thickness of the back side profile increases from the leading edge to the trailing edge. Rotate the origin of the CNC milling program around the stacking axis clockwise by β / 2.

[0062] Taking into account the measurement results of all sections, half of the average value of the wall thickness change rate of all sections is used as the correction value for program rotation.

[0063] (5) Inspection

[0064] An ultrasonic wall thickness gauge is used to test the specified cross-section and the measured wall thickness. If the test results meet the requirements, the process ends; otherwise, proceed to step 2 until the wall thickness meets the requirements.

[0065] The following are specific embodiments. It should be noted that these embodiments are preferred examples of the present invention and are intended for those skilled in the art to understand the present invention, but the present invention is not limited to these embodiments.

[0066] Example 1

[0067] The method for controlling the wall thickness of hollow blades is achieved through the following steps:

[0068] (1) Inspection section and measurement points:

[0069] According to the overall blade manufacturing process, the wall thickness of relevant sections is measured before the precision milling process (the final wall thickness requirement is 1.2 ± 0.1 mm, and the blade profile allowance is 0.5 mm). Based on the structural characteristics of the hollow blade, the locations of the sections to be inspected are selected; the number of measurement points for each section is determined. Five sections are inspected for this blade; six measurement points are taken for each section, with three measurement points each for the blade head and blade back side profiles.

[0070] (2) Ultrasonic testing:

[0071] An ultrasonic wall thickness gauge was used to measure the wall thickness at each cross-sectional location and specific measurement point, and the values ​​were recorded sequentially. When using an ultrasonic wall thickness gauge, the instrument should be calibrated using a standard block first. Since the blade profile is a complex spatial curved surface, measurements should be taken along the normal direction of the measurement point to reduce measurement errors caused by the surface curvature.

[0072] (3) Data Analysis:

[0073] Reference Figure 6 The wall thickness values ​​at each cross-section of the blade are analyzed, and the wall thickness difference α = (H_bowl - H_back) and the wall thickness change rate β = arc tan(H_bowl - H_back) / L are calculated (L is the distance between point 1 and point 3, which is 20 mm).

[0074]

[0075] 1) Wall thickness difference α:

[0076] The wall thickness difference α at each cross-section measurement point of the blade is detailed in the table above, where:

[0077] When the wall thickness difference α≤0, that is, the wall thickness of the leaf basin side profile is less than the wall thickness of the leaf back side profile;

[0078] When the wall thickness difference α≥0, that is, the wall thickness of the leaf basin side profile is greater than the wall thickness of the leaf back side profile;

[0079] 2) Wall thickness at various points along the cross-section (Hbasin, Hback):

[0080] The variation of the blade wall thickness at various points is detailed in the table above.

[0081] H_bowl1≤H_bowl2≤H_bowl3, and H_back1≥H_back2≥H_back3, that is, when the wall thickness change rate β≤0, the wall thickness of the blade's bowl side profile increases from the leading edge to the trailing edge, and the wall thickness of the back side profile decreases from the leading edge to the trailing edge.

[0082] (4) Precision milling of the blade profile:

[0083] Precision milling of the blade outer surface to meet the following requirements: Figures 2 to 4 The baseline checks and blade profile requirements shown (see...) Figure 5 Regarding the thickness difference α detected by ultrasonic wall thickness measurement and the specific situation of the wall thickness variation β at various points, it can be corrected by optimizing the CNC machining program of the blade profile during precision milling, mainly by adjusting the origin position of the program accordingly.

[0084] 1) Wall thickness difference α:

[0085] When the wall thickness difference α≤0, that is, the wall thickness of the leaf basin side profile is less than the wall thickness of the leaf back side profile;

[0086] Since the blade profile includes the aforementioned five detection sections, the average wall thickness difference among these five sections is used as the correction value for program translation. The specific value is:

[0087] (α1+α2+α3+α4+α5)=(-0.183-0.167-0.223-0.193-0.196) / 5=-0.193

[0088] The origin of the CNC milling program for the profile is shifted 0.193 / 2 = 0.965 towards the back of the blade.

[0089] 2) The rate of change of wall thickness at each point on the cross section, β:

[0090] The variation of the blade wall thickness at various points is detailed in the table above.

[0091] H_bowl1≤H_bowl2≤H_bowl3, and H_back1≥H_back2≥H_back3, that is, when the wall thickness change rate β≤0, the wall thickness of the blade's bowl side profile increases from the leading edge to the trailing edge, and the wall thickness of the back side profile decreases from the leading edge to the trailing edge.

[0092] Since the blade profile includes the aforementioned five detection sections, the average wall thickness variation rate of these five sections is calculated, and half of this average value is used as the correction value for program rotation. The specific value is:

[0093] Leaf basin: (β1+β2+β3+β4+β5)=(-0.015-0.017-0.016-0.015-0.016) / 5=-0.0158

[0094] Leaf back: (β1+β2+β3+β4+β5)=(0.02+0.019+0.021+0.010+0.019) / 5=0.0178

[0095] Rotate the origin of the CNC milling program around the overlap axis counterclockwise: (0.0158+0.0178) / 2 / 2=0.0084.

[0096] (5) Inspection

[0097] An ultrasonic wall thickness gauge was used to inspect the specified cross-section and the measured wall thickness. The final wall thickness requirement was 1.2 ± 0.1 mm, and the actual measured value was 1.20–1.25 mm, which meets the requirements of the design drawings.

[0098]

[0099] The term "constituting of" in describing a combination should include the identified elements, components, parts, or steps, as well as other elements, components, parts, or steps that do not substantially affect the essential novel features of the combination. The use of the terms "comprising" or "including" to describe combinations of elements, components, parts, or steps herein also contemplates embodiments that are essentially composed of such elements, components, parts, or steps. The use of the term "may" herein is intended to indicate that any described attribute included by "may" is optional.

[0100] Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The use of "a" or "an" to describe an element, component, part, or step does not imply the exclusion of other elements, components, parts, or steps.

[0101] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A method for controlling the wall thickness of hollow blades, characterized in that, Includes the following steps: Step 1: Determine the cross section for measuring the wall thickness of the blade profile, and select a measurement point on the cross section; Step 2: Measure and record the wall thickness at each measurement point; Step 3: Calculate the wall thickness difference and wall thickness change rate of each section based on the wall thickness at each measurement point; Step 4: Based on the wall thickness difference of each section and the rate of change of the wall thickness of each section, correct the position of the origin during the finishing of the blade profile, and correct the blade wall thickness. In step 3, the formula for calculating the wall thickness difference is: α = H_bowl - H_back, where α is the wall thickness difference, H_bowl is the blade bowl thickness at the measurement point, and H_back is the blade back thickness at the measurement point; the formula for calculating the wall thickness change rate is: β = arc tan(H_bowl - H_back) / L, where β is the wall thickness change rate, H_bowl is the blade bowl thickness at the measurement point, H_back is the blade back thickness at the measurement point, and L is the distance between points on the cross section close to both sides of the cavity. In step 4, the correction is made using the following method: When the wall thickness difference α≤0, the origin of the CNC milling program for the profile is shifted towards the back of the blade by half of the average wall thickness difference of all sections. When the wall thickness difference α≥0, the origin of the CNC milling program for the profile is shifted towards the blade head direction by half of the average wall thickness difference of all sections. When the wall thickness change rate β≤0, rotate the origin of the CNC milling program around the stacking axis counterclockwise to half the average wall thickness change rate of all sections; When the wall thickness change rate β≥0, the average wall thickness change rate of all sections is half of the value when the origin of the CNC milling program is rotated clockwise around the stacking axis.

2. The method for controlling the wall thickness of a hollow blade according to claim 1, characterized in that, In step 1, each cavity in the blade has at least one cross-section that is the detection profile.

3. The method for controlling the wall thickness of a hollow blade according to claim 1, characterized in that, In step 1, there are at least 6 measurement points for each cross section, and at least 3 measurement points for both the blade basin side profile and the blade back side profile.

4. The method for controlling the wall thickness of a hollow blade according to claim 1, characterized in that, In step 2, the wall thickness at each measurement point is detected using ultrasonic testing.

5. The method for controlling the wall thickness of a hollow blade according to claim 1, characterized in that, In step 2, the measurement is performed along the normal of the measurement point.

6. The method for controlling the wall thickness of a hollow blade according to claim 1, characterized in that, After step 4 is completed, the wall thickness is checked.

7. The method for controlling the wall thickness of a hollow blade according to claim 6, characterized in that, If the test results do not meet the requirements, proceed to step 2 until the wall thickness meets the requirements.

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