Method for measuring concavo-convex amount of curved surface countersunk connector

Abstract

This invention discloses a method for measuring the concavity / convexity of a countersunk head connector. A theoretical analysis model for concavity / convexity is established. Based on this model, the relationship between the concavity / convexity of the pin cover profile and the vertical distance between the countersunk edge and the pin cover when the concavity / convexity is zero, the measured value of the vertical distance from the countersunk edge to the pin cover, the slope of the countersunk edge measurement point, and the countersunk angle is obtained. Measurement points are selected on the countersunk edge, and the vertical distance from these points to the pin cover is measured. The concavity / convexity of the countersunk head connector is then calculated based on the aforementioned relationship. This invention employs mathematical modeling to analyze the relationship between the concavity / convexity and the actual measurable value, thereby enabling the measurement of the concavity / convexity. This provides a reliable inspection method for the assembly and inspection of aircraft surface connectors, ensuring the quality of aircraft assembly.

Description

Technical Field

[0001] This invention belongs to the field of measurement technology, specifically relating to a method for measuring the concavity and convexity of a countersunk head connector. Background Technology

[0002] Aircraft surface quality is a high-requirement, highly sensitive, and technically challenging indicator that directly impacts aircraft performance. To meet these surface quality requirements, controlling the unevenness of surface connectors is crucial, especially in areas with strict shape requirements, such as air intakes, lips, and wing surfaces, where the unevenness requirements are higher than in other areas. For countersunk connectors on flat surfaces, workers, through extensive training and the use of tools like countersunk sleeves and automatic feed drills, can generally meet the requirements. Workers can measure unevenness using calipers, unevenness measuring tools, and connector dummy parts to ensure compliance. However, for connectors on curved surfaces, workers lack effective tools to ensure unevenness and lack effective measurement and inspection equipment. Relying entirely on worker skills and experience for control can easily lead to deviations in unevenness. Summary of the Invention

[0003] The purpose of this invention is to provide a method for measuring the concavity and convexity of countersunk head connectors, so as to solve the problem that the concavity and convexity of countersunk head connectors are difficult to measure effectively.

[0004] This invention is achieved through the following technical solution:

[0005] A method for measuring the concavity / convexity of countersunk connectors on curved surfaces, used to measure the concavity / convexity of connector pin caps installed in countersunk holes on curved surfaces relative to the curved surface, includes the following steps:

[0006] A theoretical analysis model for the concavity and convexity of the nail cover profile is established. Based on the theoretical analysis model for the concavity and convexity of the nail cover profile, the relationship between the concavity and convexity of the nail cover profile and the vertical distance between the nail cover and the edge of the nail cover when the concavity and convexity are 0, the measured value of the vertical distance between the edge of the nail cover and the edge of the nail cover, the slope of the edge of the nail cover measurement point, and the angle of the countersink.

[0007] Select a measurement point on the edge of the countersunk hole, measure the vertical distance from the measurement point on the edge of the countersunk hole to the nail cover, and obtain the concave and convex amounts of the curved countersunk head connector according to the aforementioned formula.

[0008] In some embodiments, the theoretical analysis model of the concave-convex amount is to establish a coordinate system on any cross section along the central axis of the countersunk connector under the theoretical assembly state of the countersunk connector, with the nail cover surface when the theoretical concave-convex amount is c as the x-axis and the axis of the countersunk connector as the y-axis.

[0009] In some embodiments, the steps of obtaining the relationship between the concavity / convexity of the nail cap profile and the vertical distance between the recess edge and the nail cap when the concavity / convexity is 0, the measured value of the vertical distance between the recess edge and the nail cap, the slope of the recess edge measurement point, and the countersink angle based on the concavity / convexity theoretical analysis model include:

[0010] Based on the concavity / convexity theory analysis model, the following can be obtained from geometric relationships on any cross section:

[0011]

[0012] Where c is the amount of concavity and convexity of the nail cover profile, and α is half of the countersink angle;

[0013] From equation (1), we get:

[0014] c = dx * cot(α) - dy……(2);

[0015] Since the amount of concavity and convexity is small enough, we get:

[0016]

[0017] Where f′(x) is the derivative of the cross-sectional curve function;

[0018] According to equations (2) and (3), we get:

[0019] c=dx*cot(α)-dx*f'(x)=dx*(cot(α)-f'(x));

[0020] From dx = (T - T0) * tan(α), we get:

[0021] c=(T-T0)*(1-tan(α)*f'(x)).

[0022] In some embodiments, multiple intersection points of cross sections and countersunk edges are selected as measurement points, and the concavity / convexity at the corresponding measurement points is calculated. The average value of the concavity / convexity at each measurement point is taken to obtain the concavity / convexity of the countersunk head connector.

[0023] In some embodiments, the vertical distance from the edge of the socket to the nail cover when the concavity / convexity at each measurement point is 0 is calculated using a concavity / convexity theoretical analysis model.

[0024] In some embodiments, the measured value of the vertical distance from the edge of the socket to the nail cover at each measurement point is obtained by measurement.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] This invention uses mathematical modeling to analyze the relationship between the unevenness and the actual measurable value, thereby realizing the measurement of unevenness and providing a reliable inspection method for the assembly and inspection of aircraft surface connectors, ensuring the quality of aircraft assembly. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the countersunk connector concave-convexity model analysis in an embodiment of the present invention; in the figure, the green horizontal line is the outline of the nail cover surface when the concave-convexity is 0, the green arc line is the outline of the countersunk hole section, and the black horizontal line is the outline of the nail cover surface when the concave-convexity is c.

[0029] Figure 2 This is a schematic diagram of the measurement points in an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of the radius of curvature of the measured curve at the axis of the countersunk connector in an embodiment of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0032] This invention provides a method for measuring the concavity and convexity of countersunk head connectors on curved surfaces, used to check the concavity and convexity of connectors installed on curved surfaces.

[0033] In some embodiments of the present invention, the steps of the method for measuring the concavity and convexity of the countersunk head connector are as follows:

[0034] 1) Measurement Theory Analysis Model

[0035] By cutting the countersunk connector along its central axis, the following can be obtained: Figure 1 The cross-sectional view shown establishes a coordinate system with the intersection of the upper surface of the countersunk connector cap and the section as the x-axis and the axis of the countersunk connector as the y-axis. The theoretical position where the concavity / convexity is 0 is defined as the position where the intersection of the upper surface of the countersunk connector cap and the section is tangent to the curved surface. Figure 1 The position indicated by the green line; based on geometric relationships, we can deduce:

[0036]

[0037] Where c is the amount of concavity and convexity of the nail cover profile, and α is half of the countersink angle.

[0038] From equation (1), we can obtain:

[0039] c = dx * cot(α) - dy……(2).

[0040] Since the amount of concavity and convexity is small enough, we can approximate it as follows:

[0041]

[0042] Where f′(x) is the derivative of the cross-sectional curve function.

[0043] According to equations (2) and (3), we can obtain:

[0044] c=dx*cot(α)-dx*f'(x)=dx*(cot(α)-f'(x))......(4).

[0045] Therefore, by measuring the vertical distance T from the edge of the socket to the nail cap, we can obtain:

[0046] c = T - T0 - dy……(5);

[0047] Wherein, T0 is the vertical distance between the dent edge and the nail cover when the concavity / convexity is 0, which is obtained by measurement from the theoretical model.

[0048] From geometric relations, we can obtain:

[0049] dx=c*tan(α)+dy*tan(α)……(6).

[0050] Substituting equation (5) into equation (6) yields:

[0051] dx=(T-T0)*tan(α)......(7).

[0052] Substituting equation (7) into equation (4) yields:

[0053] c=(T-T0)*(1-tan(α)*f'(x))......(8).

[0054] Equation (8) corresponds to the concavity / convexity c at each point of each cross section. For a single cross section, two concavity / convexity values ​​c1 and c2 can be measured and calculated.

[0055] For a certain measurement point, such as Figure 3At point P1, f'(x) = f1'(x), which is defined as the slope of curve β, the intersection of the current cross-section and the surface, at point P1. Since the dimensions of the countersunk connector are relatively small compared to the overall surface, the curvature changes little near the countersunk connector. Therefore, curve β can be approximated as an arc with a radius of curvature R. R is the radius of curvature of curve β at the axis of the countersunk connector.

[0056] At this point, we can obtain:

[0057]

[0058] In the formula, r = D / 2, where D is... Figure 3 The distance between P1 and P2 is shown.

[0059] 2) Measurement Operation

[0060] Select the hole where the countersink has been completed, insert the connector, and measure the installed connector;

[0061] like Figure 2 As shown, four points (P1, P2, P3, and P4) on two cross sections are selected as measurement objects. Using a planar concave-convex measuring tool, calipers, and other measuring instruments, the vertical distances T1, T2, T3, and T4 from the edge of the notch to the nail cover at each point are measured respectively; and D1 (the distance between points P1 and P2) and D2 (the distance between points P3 and P4) are measured.

[0062] 3) Calculate the concavity / convexity.

[0063] The vertical distance T0 from the edge of the socket to the nail cover at each corresponding point is obtained by analyzing the concave-convexity model, and the slope k = f′(x) of the corresponding point of the socket is obtained.

[0064] Substitute the above measured values ​​T, T0, and f′(x) into equations (8) and (9) to calculate the concavity and convexity of each measurement point.

[0065] The average value of the concavity and convexity at each measurement point is taken to obtain the concavity and convexity of the countersunk head connector.

[0066] The following detailed description of the specific implementation process of the method for measuring the concavity and convexity of the countersunk head connector of the present invention, with reference to specific embodiments, will be provided.

[0067] In this embodiment, the steps for measuring the unevenness of the countersunk head connector include:

[0068] S1. Determine the measurement range based on the curvature value and confirm the measurement points;

[0069] For example, if a 100° countersunk bolt is installed on a certain cap, then α = 50°.

[0070] S2. Measure the selected countersunk connector;

[0071] a) Refer to Figure 2 Measure the T values ​​corresponding to points P1, P2, P3, and P4, respectively:

[0072] T1=0.205mm, T2=0.207mm;

[0073] T3 = 0.12 mm, T4 = 0.12 mm.

[0074] b) Measure the values ​​of D1 and D2, respectively:

[0075] D1 = 10.904 mm;

[0076] D2 = 10.696 mm.

[0077] c) Measure the curvature 1 / R on the theoretical digital model using 3D software to obtain the radius of curvature, which are as follows:

[0078] R1 = 1 / 0.006075 = 164.61 mm;

[0079] R2=1 / 2.691e-004=3716.09mm.

[0080] d) Measure T0 on the theoretical numerical model using 3D software, as follows:

[0081] T10 = 0.084 mm;

[0082] T20 = 0.087 mm;

[0083] T30 = 0.003 mm;

[0084] T40 = 0.004 mm.

[0085] S3. Substitute the measured values ​​into equations (8) and (9) to calculate the concavity / convexity values ​​c1, c2, c3, and c4 corresponding to each point.

[0086] From equation (9), we can obtain:

[0087]

[0088]

[0089] Substituting into equation (8) yields:

[0090] c1=(0.205-0.084)×(1-tan50°×0.033)=0.1162mm;

[0091] c2=(0.207-0.087)×(1-tan50°×0.033)=0.1153mm;

[0092] c3=(0.12-0.003)×(1-tan50°×0.001439)=0.1168mm;

[0093] c4=(0.12-0.004)×(1-tan50°×0.001439)=0.1158mm.

[0094] S4. Calculate the average concavity / convexity c; expressed as:

[0095] c=(c1+c2+c3+c4) / 4=0.116025mm.

[0096] The unevenness of the countersunk connector at that location can be determined to be 0.116 mm.

[0097] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., used to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of this invention is usually placed in during use. They are only for the convenience of describing this 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. Therefore, they should not be construed as limitations on this invention.

[0098] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of this invention does not imply that the components are required to be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0099] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0100] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for measuring the concavity / convexity of a countersunk connector on a curved surface, used to measure the concavity / convexity of a connector pin cap installed in a countersunk hole on a curved surface relative to the curved surface, characterized in that... Includes the following steps: A theoretical analysis model for the concavity and convexity of the nail cover profile is established. Based on the theoretical analysis model for the concavity and convexity of the nail cover profile, the relationship between the concavity and convexity of the nail cover profile and the vertical distance between the nail cover and the edge of the nail cover when the concavity and convexity are 0, the measured value of the vertical distance between the edge of the nail cover and the edge of the nail cover, the slope of the edge of the nail cover measurement point, and the angle of the countersink. Select measurement points on the edge of the countersunk hole, measure the vertical distance from the measurement point on the edge of the countersunk hole to the nail cover, and obtain the concave and convex amounts of the curved countersunk head connector according to the aforementioned formula; The theoretical analysis model for the concave-convex amount is to establish a coordinate system on any cross section along the central axis of the countersunk connector under the theoretical assembly state of the countersunk connector, with the nail cover surface when the theoretical concave-convex amount is c as the x-axis and the axis of the countersunk connector as the y-axis. The steps for obtaining the relationship between the concavity / convexity of the nail cap profile and the vertical distance between the recess edge and the nail cap when the concavity / convexity is 0, the measured value of the vertical distance between the recess edge and the nail cap, the slope of the recess edge measurement point, and the countersink angle based on the concavity / convexity theoretical analysis model include: Based on the concavity / convexity theory analysis model, the following can be obtained from geometric relationships on any cross section: ……（1）； Where c is the amount of concavity and convexity of the nail cover profile, and α is half of the countersink angle; From equation (1), we get: ……（2）； Since the amount of concavity and convexity is small enough, we get: ……（3）； in, The derivative of the function of the cross-sectional curve; According to equations (2) and (3), we get: ； Depend on ,get: T is the vertical distance from the edge of the socket to the nail cover, and T0 is the vertical distance between the edge of the socket and the nail cover when the concavity / convexity is 0.

2. The method for measuring the concavity and convexity of a countersunk head connector according to claim 1, characterized in that, Multiple intersections of the cross-section and the countersunk edge are selected as measurement points. The concavity and convexity at the corresponding measurement points are calculated. The average value of the concavity and convexity at each measurement point is taken to obtain the concavity and convexity of the curved countersunk head connector.

3. The method for measuring the concavity and convexity of a countersunk head connector according to claim 2, characterized in that, The vertical distance from the edge of the socket to the nail cover when the concavity / convexity at each measurement point is 0 is calculated using the concavity / convexity theoretical analysis model.

4. The method for measuring the concavity and convexity of a countersunk head connector according to claim 2, characterized in that, The measured values ​​of the vertical distance from the edge of the socket to the nail cover at each measurement point were obtained through measurement.

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