Method for calculating optimal assembly tolerance after deformation of components

Abstract

The invention belongs to the technical field of auxiliary assembly, and discloses a method for calculating the optimal assembly tolerance after deformation of components, and the method comprises the following steps: S10, a preparation stage before measurement: determining a measurement point location according to the structural feature requirement of each component, each measurement point location is distributed to a corresponding weight set; and S20, a measurement and attitude adjustment stage: measuring measured values of the measurement points in the weight sets, fitting and calculating an optimal state which can be reached by assembly in the measured state, calculating an assembly attitude adjustment path from a current state to the optimal state, adjusting the attitude according to a calculation result, and performing re-test verification on the measurement points. According to the calculation method for the optimal assembly tolerance after the deformation of the components, the optimal solution which can be achieved during the attitude adjustment of the general assembly wing box can be calculated based on the sizes of the deformed components, and the optimal solution is used as a control target of field attitude adjustment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of auxiliary assembly, in particular to a calculation method of optimal assembly tolerance after deformation of components. BACKGROUND

[0002] In the field of aerospace technology, during the assembly process of large components such as central wing boxes, due to the large size of each component, and most of the components are made of thick plates by machining process, there may be a certain deformation after forming, which brings adverse effects on the subsequent assembly of the central wing box. Moreover, the central wing box is an axisymmetric and closed structure, and during the assembly process, the tolerances of each component need to be offset to each other to improve the final assembly accuracy of the wing box.

[0003] The traditional assembly method for the central wing box is to use a hard tooling, which directly positions each component to the theoretical position for assembly; however, this method introduces assembly stress, and after the removal of the assembly tooling, the central wing box may deform during assembly, resulting in assembly accuracy out of tolerance.

[0004] Currently, there is also a method of using tolerance allocation and digital measurement to adjust the posture for assembly, which allocates the tolerances on the component drawings again, controls the assembly process of the central wing box, allocates tolerances to the previous process, and finally performs digital measurement to adjust the posture to determine the final shape of the wing box. The specific measures are as follows: first, a commercial tolerance analysis software is used to establish a simulation analysis model by using the calculation method of optimal assembly tolerance after deformation of components, and then an assembly structure tree is established according to the actual assembly positioning mode, the dimensional tolerances in the engineering drawings are input, and the tolerance influence on the control target is calculated. However, the biggest disadvantage of this method is that each component can only be treated as a rigid body, and the influence of the deformation of the component on the final control target cannot be simulated, and thus the optimal solution that the control target can achieve during the assembly of the wing box after the deformation of the component with multiple factors and nonlinear coupling cannot be calculated.

[0005] Therefore, there is an urgent need for a calculation method of optimal assembly tolerance after deformation of components to solve the above technical problems. SUMMARY

[0006] The purpose of the present application is to provide a calculation method of optimal assembly tolerance after deformation of components, which can calculate the optimal solution that can be achieved during the posture adjustment of the assembled wing box based on the size of the deformed component, and use it as the control target for on-site posture adjustment.

[0007] To achieve this purpose, the present application adopts the following technical solutions:

[0008] The calculation method of optimal assembly tolerance after deformation of components comprises the following steps:

[0009] S10, a measurement preparation stage: according to the structure characteristic requirements of each component, determine the measurement points, and distribute each measurement point to the corresponding weight set;

[0010] S20, a measurement adjustment stage: measure the measured values of the measurement points in each weight set, fit and calculate the best state that the assembly can reach in the measured state, calculate the assembly adjustment path from the current state to the best assembly state, adjust according to the calculation result, and retest the measurement points.

[0011] Optionally, step S10 includes the following steps:

[0012] S11, according to the structure characteristic requirements of each component, a corresponding number of measurement points are arranged on the surface of each component;

[0013] S12, analyze the structure requirements of each component, and give each measurement point a corresponding weight coefficient;

[0014] S13, according to the level of the weight coefficient, distribute each measurement point to the corresponding weight set.

[0015] Optionally, in step S13, the weight coefficient of the measurement point is confirmed according to the data error of the measurement point of the component and the influence on the subsequent work.

[0016] Optionally, in step S10, the selection principle of the measurement point is to uniformly select the sensitive parts with complex connection relationship in the component.

[0017] Optionally, the selected measurement points include the reference surface of the component, the surface with matching relationship of the component, or the feature hole on the component.

[0018] Optionally, step S20 includes the following steps:

[0019] S21, according to the initial assembly position of each component, establish an assembly coordinate system;

[0020] S22, measure the measured values of each measurement point of each component;

[0021] S23, according to the measured values of each measurement point, fit and calculate the best state that the assembly can reach in the measured state, calculate the assembly adjustment path from the current state to the best assembly state, adjust according to the calculation result, and retest the measurement points.

[0022] Optionally, step S23 includes the following steps:

[0023] S231, respectively, the measured value in different above-mentioned weight set is carried out conformal transformation calculation, and fitting forms the actual best assembly shape, obtains the best assembly state;

[0024] S232, comparing above-mentioned measured state and above-mentioned best assembly state, obtains assembly adjustment path;

[0025] S233, according to above-mentioned assembly adjustment path, each above-mentioned zero component is carried out position fine adjustment;

[0026] S234, the current measurement of each above-mentioned measurement point is measured, whether each above-mentioned current measurement meets the theoretical measurement precision range of above-mentioned best assembly state is judged;If each above-mentioned current measurement meets the theoretical measurement precision range, then end adjustment;If at least one of each above-mentioned current measurement does not meet the theoretical measurement precision range, then return to execute step S231.

[0027] Optionally, in step S232, the calculation method of above-mentioned assembly adjustment path adopts least square method.

[0028] Optionally, in step S234, the method for judging whether each above-mentioned current measurement meets the theoretical measurement precision range of above-mentioned best assembly state comprises: calculating the difference between above-mentioned current measurement and above-mentioned theoretical measurement of each above-mentioned measurement point, and judging whether above-mentioned difference meets the precision tolerance range.

[0029] Optionally, before step S20, it further comprises step S15, each above-mentioned zero component is roughly adjusted to the vicinity of best assembly state.

[0030] The beneficial effects of the present application are as follows:

[0031] The present application provides a kind of calculation method of optimal assembly tolerance of zero component deformation, first according to the structure feature requirement of each zero component of this total assembly structure to determine measurement point, and the data error of each measurement point is distributed to error by the influence size of subsequent work, then the measurement point in each weight set is measured, i.e.to each zero component after deformation is measured, the best state that can be reached under the fitting calculation of measured state assembly, the assembly adjustment path under the calculation of these two states is calculated, according to the result of calculation, adjustment is carried out, and the measurement point is rechecked, i.e.to the adjustment of the assembly attitude of zero component, ensure that the total assembly structure after the assembly of each zero component meets the assembly precision requirement.And, it calculates assembly adjustment path by fitting the measured value, which considers the situation after the deformation of zero component, establishes the corresponding relationship between the zero component after deformation and theoretical shape, improves the precision and efficiency of the assembly of this total assembly structure. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1is a flow chart of the calculation method of the optimal assembly tolerance of the zero component after deformation provided by the embodiment of the present application;

[0033] Figure 2 is a flow chart of the measurement preparation stage provided by the embodiment of the present application;

[0034] Figure 3 is a structural schematic diagram of a No. 1 rib provided by the embodiment of the present application;

[0035] Figure 4 is a flow chart of the measurement and attitude adjustment stage provided by the embodiment of the present application.

[0036] In the figure:

[0037] 1, upper surface; 2, lower surface; 3, front surface; 4, rear surface. EMBODIMENT

[0038] The present application will be further described below in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, only the parts related to the present application are shown in the drawings, but not all the structures.

[0039] In the description of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood in a broad sense, for example, it can be fixedly connected, or detachably connected, or integrated; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] In the present application, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "over", "above" and "on" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "under", "below" and "under" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0041] In the description of the present embodiment, the terms "upper", "lower", "right", "left", and the like, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used to distinguish in the description, and have no special meaning.

[0042] Reference will now be made to Figures 1 to 3 The optimal assembly tolerance calculation method of the deformed components in the present embodiment is introduced.

[0043] Reference will now be made to Figure 1 In the present embodiment, the optimal assembly tolerance calculation method of the deformed components includes the following steps: S10, preparation stage before measurement: determining the measurement points according to the structure feature requirements of each component, and distributing each measurement point to the corresponding weight set; S20, measurement and pose adjustment stage: measuring the measured values of the measurement points in each weight set, fitting and calculating the best state that can be achieved in the measured state, calculating the assembly pose adjustment path from the current state to the best assembly state, adjusting the pose according to the calculation result, and re-measuring and verifying the measurement points.

[0044] It should be noted that the measured state described above is the assembly position state of the components after actual manufacturing with a certain degree of deformation.

[0045] The optimal assembly tolerance calculation method of the deformed components in the present embodiment first determines the measurement points according to the structure feature requirements of each component of the assembly structure, and then distributes the error weights according to the influence of the data error of each measurement point on the subsequent work, and then measures the measurement points in each weight set, i.e. measures each deformed component, fits and calculates the best state that can be achieved in the measured state, calculates the assembly pose adjustment path in the two states, adjusts the pose according to the calculation result, and re-measures and verifies the measurement points to ensure that the assembly structure after assembly of each component meets the assembly accuracy requirements. Moreover, it calculates the assembly pose adjustment path by fitting the measured values, considers the situation after deformation of the components, establishes the corresponding relationship between the deformed components and the theoretical shape, and improves the assembly accuracy and efficiency of the assembly structure.

[0046] Reference will now be made to Figure 2Specifically, the step S10 comprises the following steps: S11, setting a corresponding number of measuring points on the surface of each component according to the structural feature requirements of each component; S12, analyzing the structural requirements of each component, and assigning corresponding weight coefficients to each measuring point; S13, distributing each measuring point to the corresponding weight set according to the level of the weight coefficient. Through the above steps, the confirmation of each component measuring point and the assignment of weight coefficients can be realized to facilitate measurement.

[0047] Optionally, the structural feature requirements of the component can be determined according to the tolerance requirements on the design drawing.

[0048] Specifically, in step S10, the selection principle of the measuring point is to uniformly select the sensitive parts with complex connection relationship in the component. That is, the position of the assembly of the component and other components is selected, and the accuracy requirement of this position is generally high. The measuring point is selected at this position to better ensure that the actual measurement value of each component after subsequent pose adjustment meets the accuracy tolerance.

[0049] Optionally, the selected measuring point includes the reference surface of the component, the surface with a matching relationship of the component, or the feature hole position on the component; all of them are parts that match with external structures, and the accuracy requirement is high.

[0050] Optionally, the above feature workstations can be positioning holes, assembly holes and other important hole positions in the assembly process.

[0051] Specifically, the weight coefficient of the measuring point is determined according to the influence of the data error of the component measuring point on the subsequent work. That is, after the component is delivered, the sizes are often checked, or the re-measurement is performed after the previous stage pose adjustment to determine the measuring position with larger error, and a larger weight coefficient is assigned to the position to perform actual measurement and pose adjustment, so as to ensure that the accuracy of the total assembly structure meets the requirements.

[0052] Optionally, the weight coefficient can be set as high, medium, low or high, low or first weight, second weight…Nth weight distribution, so as to distribute each weight coefficient according to the level.

[0053] Please refer to Figure 3 The following describes a first rib of a central wing box. The first rib has four surfaces, namely an upper surface 1, a lower surface 2, a front surface 3 and a rear surface 4. The four surfaces are arranged in different components respectively, and then the components are assembled so that the four surfaces meet the requirements.

[0054] Please refer to Figure 3It can be seen that the opening position of the first rib and the assembly position of the four faces of the first rib are respectively the double curved surface of the upper surface 1 and the lower surface 2, and the measurement data is generally poor, so the high weight is set; the front surface 3 and the rear surface 4 are planes, and if there is deviation, the subsequent work station can be adjusted by adding shims, and the like, so the low weight is set.

[0055] Please refer to Figure 4 In some embodiments, the step S20 comprises the following steps: S21, establishing an assembly coordinate system according to the initial assembly position of each component; S22, measuring the measured values of each measurement point of each component; S23, fitting and calculating the best state that can be reached in the assembly according to the measured values of each measurement point, calculating the assembly adjustment path from the current state to the best assembly state, adjusting according to the calculation result, and re-measuring and verifying the measurement points. Through the above steps, the assembly attitude of each component can be continuously adjusted until the best assembly state is reached.

[0056] Optionally, in step S21, the coordinate system is established according to the laser tracker, which is convenient, fast and high in precision.

[0057] Specifically, step S23 comprises the following steps: S231, respectively performing conformal transformation calculation on the measured values in different weight sets, and fitting to form the best assembly shape that can be actually reached, to obtain the best assembly state; S232, comparing the measured state and the best assembly state to obtain the assembly adjustment path; S233, performing position fine adjustment on each component according to the assembly adjustment path; S234, measuring the current measurement values of each measurement point, and judging whether each current measurement value meets the theoretical measurement value precision range of the best assembly state; if each current measurement value meets the theoretical measurement value precision range, the adjustment is ended; if at least one of the current measurement values does not meet the theoretical measurement value precision range, step S231 is performed. Through the above steps, the adjustment of each component can be realized until the required precision is met.

[0058] It should be noted that the weights are generally divided into high weights and low weights, and the shape calculated by the measurement points with high weights is the basic assembly shape, and the shape calculated by the measurement points with low weights is the correction value.

[0059] Optionally, in step S231, the conformal transformation calculation on the measured values in different weight sets and the fitting to form the actual assembly shape are performed by computer software to improve the measurement accuracy and calculation rate. Optionally, the computer software comprises MATLAB, etc. Of course, in other embodiments, the above calculation can also be realized by other operations, which are not limited here.

[0060] It should be noted that the conformal transformation calculation is performed by using a conformal transformation method. The conformal transformation method is as follows: it is assumed that the zero components have been deformed to a certain extent before the attitude adjustment, and the measured values and the theoretical values of the same measurement points after the deformation satisfy the conformal transformation rule; z = ω (ζ) is taken, where ζ = ξ + iη, and then each point (ξ, η) on the image plane ζ corresponds to a point (x, y) on the physical plane z. It is assumed that S is a curve on the ζ plane, and if a point moves along S, then the corresponding point z draws a curve S' on the z plane. This corresponding relationship is called mapping or transformation. If ω (ζ) is analytic and ω' (ζ) ≠ 0, then the angle between two curves S1 and S2 on the ζ plane is ɑ, and after the transformation, the angle between the two curves S1' and S2' drawn on the z plane is still ɑ. The transformation z = ω (ζ) is called conformal transformation. Before and after the transformation, the shape of the figure is rotated and scaled, but the angle between the two curves remains unchanged. The complex boundary on the z plane can be transformed into the relatively easy-to-solve boundary on the w plane.

[0061] It should be noted that in step S232, the calculation of the assembly attitude adjustment path is achieved by subtracting the shortest distance between the actual assembly shape of each measurement point and the optimal assembly state, so as to adjust the position of each zero component according to the assembly attitude adjustment path in step S233.

[0062] Optionally, in step S232, the calculation method of the assembly attitude adjustment path adopts the least square method, that is, the shortest distance from each measurement point to its own theoretical value is the fine adjustment path, and the assembly attitude adjustment path vector can be obtained.

[0063] Optionally, in step S234, the method for judging whether the current measurement value meets the accuracy range of the theoretical measurement value of the optimal assembly state comprises: calculating the difference between the current measurement value and the theoretical measurement value of each measurement point, and judging whether the difference meets the accuracy tolerance range. When the accuracy tolerance range is met, the attitude adjustment is ended; if not, it returns to step S231.

[0064] In some embodiments, before step S20, there is further a step S15 of coarsely adjusting each zero component to the vicinity of the optimal assembly state. Such a setting can reduce the calculation steps, that is, each zero component is placed in the vicinity of the optimal assembly state, and the subsequent adjustment value is not too large, and the number of attitude adjustment times is also reduced, thereby accelerating the calculation rate of the method.

[0065] Obviously, the above embodiments of the present application are merely exemplary but not intended to limit the embodiments of the present application. Various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the scope of the present application. It is not necessary or possible to enumerate all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for calculating the optimal assembly tolerance after component deformation, characterized in that: The following steps are involved: S10, pre-measurement preparation stage: determining measurement points according to the structural characteristics of each component, and assigning each measurement point to a corresponding weight set; S20, measurement and posture adjustment stage: measuring the measured values ​​of the measurement points in each of the weight sets, fitting and calculating the optimal state that can be achieved by the assembly under the measured state, calculating the assembly posture adjustment path from the current state to the optimal assembly state, adjusting the posture according to the calculation results, and re-measuring and verifying the measurement points.

2. The method for calculating the optimal assembly tolerance of a component after deformation according to claim 1, characterized in that: Step S10 includes the following steps: S11. Setting a corresponding number of measurement points on the surface of each component according to the structural feature requirements of each component; S12, analyzing the structural requirements of each component, and assigning a corresponding weight coefficient to each measurement point; S13. Allocate each of the measurement points to a corresponding weight set according to the level of the weight coefficient.

3. The method for calculating the optimal assembly tolerance of a component after deformation according to claim 2, characterized in that: In step S13, the weight coefficients assigned to the measurement points are determined based on the impact of the data errors of the component measurement points on subsequent work.

4. The method for calculating the optimal assembly tolerance of a component after deformation according to claim 1, wherein: In step S10, the principle for selecting the measuring points is to evenly select sensitive parts with complex connection relationships in the components.

5. The method for calculating the optimal assembly tolerance of a component after deformation according to claim 4, characterized in that: The selected measurement points include the reference surface of the component, the surface of the component with which the component has a matching relationship, or the characteristic hole position on the component.

6. The method for calculating the optimal assembly tolerance of a component after deformation according to claim 1, wherein: Step S20 includes the following steps: S21, establishing an assembly coordinate system according to the initial assembly positions of the components; S22, measuring the actual value of each of the measurement points of each of the components; S23. Calculate the optimal state that can be achieved by the assembly under the measured state based on the measured values ​​of each of the measurement points, calculate the assembly posture adjustment path from the current state to the optimal assembly state, adjust the posture according to the calculation results, and remeasure and verify the measurement points.

7. The method for calculating the optimal assembly tolerance of a component after deformation according to claim 6, wherein: Step S23 includes the following steps: S231, performing conformal transformation calculations on the measured values ​​in different weight sets respectively, and fitting to form an optimal assembly shape that can actually be achieved, to obtain an optimal assembly state; S232, comparing the measured state with the optimal assembly state to obtain an assembly posture adjustment path; S233, fine-adjusting the position of each component according to the assembly posture adjustment path; S234. Measure the current measurement value of each measurement point and determine whether each current measurement value meets the theoretical measurement value accuracy range of the optimal assembly state; if each current measurement value meets the theoretical measurement value accuracy range, end the posture adjustment; if at least one of the current measurement values ​​does not meet the theoretical measurement value accuracy range, return to step S231.

8. The method for calculating the optimal assembly tolerance of a component after deformation according to claim 7, wherein: In step S232, the least squares method is used to calculate the assembly posture adjustment path.

9. The method for calculating the optimal assembly tolerance of a component after deformation according to claim 7, wherein: In step S234, the method for determining whether each of the current measurement values ​​meets the accuracy range of the theoretical measurement value of the optimal assembly state includes: calculating the difference between the current measurement value and the theoretical measurement value of each of the measurement points, and determining whether the difference meets the accuracy tolerance range.

10. The method for calculating the optimal assembly tolerance of a component after deformation according to any one of claims 1 to 9, characterized in that: Before step S20, the method further includes step S15 of roughly adjusting each of the components to near an optimal assembly state.

Images