Helicopter driveshaft mounting bracket positioning tooling and application method

Abstract

This invention discloses a positioning fixture and application method for helicopter drive shaft mounting supports, comprising: a locator that mates with each mounting support on the helicopter drive shaft; a support screw threaded onto the locator to spatially connect the mounting supports into an integral structure; wherein the support screw has multiple threaded segments spaced at predetermined intervals, and each mounting support is fixed in position by adjusting nuts corresponding to the threaded segments; the locator and each mounting support are respectively provided with positioning holes, so as to connect the locator and each mounting support into an integral structure by a fixing mechanism that mates with the positioning holes. This invention provides a positioning fixture and application method for helicopter drive shaft mounting supports, and designs a dedicated positioning fixture to ensure accurate positioning of the helicopter drive shaft mounting supports, guarantee the concentricity of the drive shaft, and effectively control maintenance cycle and cost.

Description

Technical Field

[0001] This invention relates to the field of helicopter maintenance. More specifically, this invention relates to a helicopter driveshaft mounting bracket positioning fixture and its application method used in maintenance of helicopter driveshaft mounting brackets. Background Technology

[0002] Helicopter driveshaft mounting brackets are prone to wear and cracking due to the centrifugal force of the driveshaft during use. Repair requires replacement of the driveshaft mounting brackets. However, due to the high requirements for the installation position and positioning of the driveshaft mounting brackets, the current replacement method relies on the manufacturer or repair shop to replace the entire tail structure of the helicopter to replace the driveshaft mounting brackets. This maintenance method is costly, and as helicopter use and training increase, the maintenance cycle shortens and the maintenance workload increases. Therefore, how to conduct in-depth field repairs and structural positioning has become a technical problem that helicopter maintenance companies urgently need to solve.

[0003] Therefore, in the current helicopter maintenance field, due to the lack of specialized field drive shaft support positioning fixtures, replacement requires transporting the entire aircraft to the manufacturing plant or repair shop. The disadvantages include:

[0004] 1) Lack of installation fixtures that match the helicopter drive shaft support and have positioning function;

[0005] 2) There is a lack of installation methods that match the positioning fixtures for helicopter drive shaft supports. Summary of the Invention

[0006] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0007] To achieve these objectives and other advantages of the present invention, a positioning fixture for a helicopter drive shaft mounting support is provided, comprising:

[0008] Positioners that mate with the mounting brackets on the helicopter drive shaft;

[0009] A support screw is threaded onto the locator to spatially connect the various mounting supports into a single integrated structure;

[0010] The support screw has multiple thread segments spaced at predetermined intervals, and each mounting bracket is fixed in position by adjusting nuts that are relatively set on the corresponding threads;

[0011] The positioner and each mounting bracket are respectively provided with matching positioning holes, so that the positioner and each mounting bracket can be connected into one unit by a fixing mechanism that matches the positioning holes.

[0012] Preferably, the locator is provided with a positioning target center corresponding to the laser rangefinder.

[0013] A method for applying a positioning fixture for a helicopter drive shaft mounting support includes:

[0014] S1. Insert the positioner onto each section of the thread of the support screw, and ensure that each positioner has an independent adjusting nut at both ends;

[0015] S2. Based on the calibrated target center on each locator, the distance y between adjacent locators is obtained using a ranging device. i ;

[0016] S3, y i As input to the prediction model, obtain the adjustment value x for each positioner. i The adjustment amount based on the rotation of the adjusting nut one revolution and the adjustment value x output by the prediction model. i The conversion is performed to obtain the rotation values ​​of each adjusting nut;

[0017] S4. Adjust the position of the positioner according to the rotation value obtained above, and check it after adjustment. If the adjusted position accuracy does not meet the usage requirements, repeat S2-S3; otherwise, proceed to S5.

[0018] S5. Connect each mounting bracket and the corresponding positioner together through the fixing mechanism. Place the positioning fixture with the mounting brackets into the lower part of the helicopter drive shaft. After fixing each mounting bracket, separate the fixing mechanism from the mounting bracket.

[0019] Preferably, in S3, the prediction model adopts the idea of ​​linear regression and is implemented based on the least squares method. In the prediction model, the xy curve is fitted by the following linear equation:

[0020] y = k*x + b

[0021] The least squares method is used to solve for k and b, and the sum of squared residuals R is made so that SS If the minimum is:

[0022]

[0023]

[0024]

[0025] Make R SS If the minimum is:

[0026]

[0027] Given k = 2.5591 and b = 500, the prediction function is:

[0028] y = 2.5591x + 500

[0029] When there are multiple adjusting nuts, the formula for predicting the adjustment amount of each adjusting nut is:

[0030]

[0031] In the above formula, y i x represents the nut to be adjusted on the i-th positioner. i x represents the adjustment amount of the nut to be adjusted on the i-th positioner. i-1 This represents the adjustment amount of the nut to be adjusted on the (i-1)th positioner, and n represents the number of positioners from left to right or from right to left.

[0032] The present invention has at least the following beneficial effects: First, the present invention designs a special positioning fixture to ensure accurate positioning of the helicopter drive shaft mounting bracket, guarantee the concentricity of the drive shaft and other requirements, while effectively controlling the maintenance cycle and cost.

[0033] Secondly, when the positioning fixture of this invention is used in conjunction with a laser ranging device, it can achieve rapid positioning, save adjustment time, and meet the assembly accuracy requirements.

[0034] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure after the positioning tool and the mounting support are engaged in one embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the helicopter drive shaft mounting support structure of the present invention;

[0037] Figure 3 This is a fitted curve of the prediction model of this invention. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0039] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not imply the presence or addition of one or more other elements or combinations thereof.

[0040] It should be noted that in the description of this invention, the orientation or positional relationship indicated by the terms is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. It does not 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 this invention.

[0041] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed", "equipped", "sleeved / connected", "connected", etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0042] like Figure 1-2 As shown, a positioning fixture for a helicopter drive shaft mounting support includes an adjusting screw (1) for support, an adjusting nut (2) for positioning, a positioning device I (3), a positioning device II (8), a positioning device III (9) that cooperate with the mounting support (5), a laser positioning calibration target (4), a mounting support (5) that cooperates with the helicopter drive shaft, a positioning hole I (6) on the positioning device, and a positioning hole II (7) on the mounting support.

[0043] Among them, two support adjusting screws (1) pass through three positioners (3), and the positioners (3) and the mounting brackets (5) are fixedly connected by positioning pins through positioning holes (6) on the positioners and positioning holes II (7) on the mounting brackets.

[0044] In practical applications, the precise distance between the mounting supports (5) can be measured according to the laser measurement and positioning method and the calibration target on the locator. The positioning adjustment nut (2) can then be adjusted to move the locator (3) and the mounting support (5) together to the installation position for fixed installation.

[0045] Furthermore, in practical applications, the adjusting screw (1) has a total length of 1900mm and is provided with 3 sections of thread, each section of thread being about 200mm long, for adjusting the positioning adjusting nut (2).

[0046] The aforementioned tooling allows for unified installation after field positioning, effectively ensuring installation accuracy. It also eliminates the need for transporting the entire machine for maintenance, saving maintenance costs and effectively shortening the maintenance cycle.

[0047] For the above-mentioned tooling, if the traditional adjustment method is used, that is, by adjusting the positioning adjustment nut (2) to change the distance between the drive shaft mounting supports (5), after one adjustment, the distance between the drive shaft mounting supports (5) needs to be measured. If it does not meet the requirements, it needs to be adjusted again and measured again. When the distance between the drive shaft mounting supports (5) meets the process requirements, the adjustment is stopped, and then the next positioning seat is adjusted. The adjustment cycle is still long. That is, if the above-mentioned tooling adopts the above-mentioned traditional adjustment method, except for the first positioning seat, any other positioning seat still needs to be adjusted multiple times to meet the process requirements, which makes the work efficiency low. Therefore, an application method of helicopter drive shaft mounting support positioning tooling is proposed, that is, by setting a prediction model to give the adjustment amount of each positioning seat, and rotating the corresponding nut a number of turns according to the adjustment amount, the adjustment cycle and verification cycle are effectively shortened. Specifically, the prediction model of this invention is based on the least squares method to find the functional relationship between the adjustment amount of the adjustment nut and the distance between the drive shaft mounting supports (5), so as to shorten the number of adjustments and improve the work efficiency.

[0048] Let the distance between the drive shaft mounting supports (5) be y (the standard process distance), and the adjustment amount of the adjusting nut be X. The actual adjustment data is as follows:

[0049] x / mm 0 +4 -4 +8 -8 +12 -12 +16 -16 +20 -20 y / mm 500 510 490 519 481 525 470 548 460 555 450

[0050] A prediction model for the relationship between the distance between drive shaft mounting supports and the adjustment amount of the nut, based on the least squares method.

[0051] In order to scientifically study the relationship between the distance between the drive shaft mounting supports and the adjustment amount of the adjusting nut, this patent adopts the idea of ​​linear regression and proposes a prediction model of the distance between the drive shaft mounting supports and the adjustment amount of the adjusting nut based on the least squares method.

[0052] Given that the adjustment amount of the adjusting nut is the independent variable x, and the distance between the drive shaft mounting supports is the dependent variable y, y and x satisfy the following linear equation.

[0053] y = a n x n +a n-1 x n-1 +…+a0

[0054] In the formula, a n These are the undetermined coefficients. Solving the equation y involves solving for each undetermined coefficient a in the above equation. n For each independent variable x, there exists an observed value y. For m sets of independent variables x, the following equation should be satisfied:

[0055] Ab = Y

[0056] In the formula, A, b, and Y are the construction matrices, and their specific expressions are as follows.

[0057]

[0058] b = [a0 … a] n ] T

[0059] Y = [y0 … y m ] T

[0060] For matrix A, if it is full rank, then:

[0061] b = YA -1

[0062] For matrix A, if it is rank deficient, then:

[0063] b = C -1 Y

[0064] In the formula, C is the construction matrix, which is expressed as follows.

[0065] C = A T A

[0066] It should be noted that deriving the formula through the above linear formula and obtaining the final formula is equivalent to verifying the correctness of this formula through two calculation methods.

[0067] The actual test results show that the distance between the drive shaft mounting supports and the nut adjustment amount have a good linear relationship. Using a linear equation prediction model and substituting the actual test results, we can obtain the following:

[0068] y = 2.5591x + 500

[0069] For multiple adjusting nuts, the formula for predicting each adjustment amount is as follows:

[0070]

[0071] In the above formula, y i x represents the nut to be adjusted on the i-th positioner. i x represents the adjustment amount of the nut to be adjusted on the i-th positioner. i-1 This represents the adjustment amount of the nut to be adjusted on the (i-1)th positioner, and n represents the number of positioners from left to right or from right to left.

[0072] It should be noted that the linear equation prediction model here is a prediction model for this installation obtained from data. It has a certain degree of universality and provides a guideline value for the adjustment amount of the installation nut in practical applications, thereby improving the adjustment efficiency.

[0073] And from R SSThe value of 0 indicates that the model has a good fit and can predict the distance between the drive shaft mounting supports based on the nut adjustment amount.

[0074] Fitting xy curves

[0075] y = k·x + b

[0076] Using the least squares method, solve for k and b to make the sum of squared residuals R SS Minimum, has

[0077]

[0078]

[0079]

[0080] Make R SS If the minimum is:

[0081]

[0082] We obtain k = 2.5591 and b = 500.

[0083]

[0084] like Figure 3 As shown, that is, R SS The value is close to 0, indicating a good fit.

[0085] In practical applications, such as Figure 1 As shown, the distance between positioner I (3) and positioner II (8) is set to L1 (its technical standard is 800±1mm, equivalent to y1), and the distance between positioner II (8) and positioner III (9) is set to L2 (its technical standard is 850±1mm, equivalent to y2). After the position of positioner (3) is determined, in order to ensure that both L1 and L2 meet the technical standards, the initial values ​​of L1 and L2 are first obtained by laser ranging. The formula adjusts L1 and L2, that is, it calculates the adjustment amount x corresponding to each adjusting nut. i This involves predicting the number of rotations of each nut to ensure that L1 and L2 meet technical standards. Furthermore, according to industry standards for this type of nut, if the adjustment amount is 4mm per rotation of the nut, then to meet the target, X... i By converting the adjustment amount of one turn of the nut, the number of turns of each nut can be obtained, reducing adjustment time, shortening the number of adjustments, and improving work efficiency.

[0086] The above solution is merely an illustration of a preferred example and is not limited thereto. When implementing this invention, appropriate substitutions and / or modifications can be made according to the user's needs.

[0087] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0088] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Other modifications can be readily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. An application method of a positioning fixture for a helicopter drive shaft mounting support, characterized in that, The positioning fixture includes: Positioners that mate with the mounting brackets on the helicopter drive shaft; A support screw is threaded onto the locator to spatially connect the various mounting supports into a single integrated structure; The support screw has multiple thread segments spaced at predetermined intervals, and each mounting bracket is fixed in position by adjusting nuts that are relatively set on the corresponding threads; The positioner and each mounting bracket are respectively provided with matching positioning holes, so as to connect the positioner and each mounting bracket into a whole through the fixing mechanism that matches the positioning holes; The locator is equipped with a positioning target center corresponding to the laser rangefinder. The application methods of helicopter drive shaft mounting bracket positioning fixtures include: S1. Insert the positioner onto each section of the thread of the support screw, and ensure that each positioner has an independent adjusting nut at both ends; S2. Based on the calibrated target center on each locator, a ranging device is used to obtain the distance between adjacent locators. y i ; S3, y i As input to the prediction model, obtain the adjustment value x for each positioner. i The adjustment amount based on the rotation of the adjusting nut one revolution and the adjustment value x output by the prediction model. i The conversion is performed to obtain the rotation values ​​of each adjusting nut; S4. Adjust the position of the positioner according to the rotation value obtained above, and check it after adjustment. If the adjusted position accuracy does not meet the usage requirements, repeat S2-S3; otherwise, proceed to S5. S5. Connect each mounting bracket and the corresponding positioner together through the fixing mechanism. Place the positioning fixture with the mounting brackets into the lower part of the helicopter drive shaft. After fixing each mounting bracket, separate the fixing mechanism from the mounting bracket. In S3, the prediction model employs linear regression and is implemented using the least squares method. The prediction model uses the following linear equation to fit the xy curve: y = k × x + b The least squares method is used to solve for k and b, and the sum of squared residuals R is made so that... SS If the minimum is found, then: Make R SS If the minimum is found, then: Given k=2.5591 and b=500, the prediction function is: When there are multiple adjusting nuts, the formula for predicting the adjustment amount of each adjusting nut is: In the above formula, y i x represents the nut to be adjusted on the i-th positioner. i x represents the adjustment amount of the nut to be adjusted on the i-th positioner. i-1 This represents the adjustment amount of the nut to be adjusted on the (i-1)th positioner, and n represents the number of positioners from left to right or from right to left.

Images