CN116986009A - Flexible aircraft assembling method for accommodating manufacturing errors of parts - Google Patents

Abstract

The invention provides an aircraft flexible assembly method for accommodating manufacturing errors of parts, belongs to the field of aviation manufacturing engineering/aircraft assembly, and is suitable for an assembly process design under the condition that the manufacturing precision of aircraft parts meets design indexes but does not meet assembly positioning requirements, so that the positioning precision of the parts is ensured. The method comprises the following steps: designing a part positioning scheme, and adopting point characteristics to replace surface and hole characteristics; designing a flexible assembly tool according to a positioning scheme; scanning point cloud of the part, virtually assembling and analyzing an assembling gap; virtually assembling the parts and the parts assembled with the parts; packaging and modeling an assembly gap, and 3D printing a compensation gasket; adjusting positioning parts of the flexible assembly tool; and (3) eliminating assembly gaps by adopting a solid-liquid mixing mode, and completing the coordinated assembly of parts. The invention solves the problems that complex parts cannot be accurately positioned on a tool and the compensation gasket is difficult to manually assemble, shortens the assembly period, greatly improves the assembly precision and ensures the assembly quality of an airplane.

Description

Flexible aircraft assembling method for accommodating manufacturing errors of parts

Technical Field

The invention belongs to the field of aviation manufacturing engineering/aircraft assembly, and relates to an aircraft flexible assembly method for accommodating part manufacturing errors, which is suitable for an assembly process design under the condition that the aircraft part manufacturing precision meets design indexes but does not meet assembly positioning requirements, and ensures the part positioning precision.

Background

As the performance of aircraft has increased, the integration has increased in aircraft design, and thus complex parts, particularly those containing aerodynamic profile features, have been designed to serve to join different integration structures, as shown in fig. 2 (a) through 2 (c). Based on the multiple functions of the parts, the outstanding characteristics of the parts are that the curvature of the appearance is changed greatly and discontinuously, and the assembly area is mainly sunk. The processing or forming method of the parts is complex, the precision is unstable, and the assembly problems caused by the complex processing or forming method are as follows:

1) The appearance curvature characteristic of part leads to unable design assembly technology hole in the structure, causes the frock unable location.

2) The appearance manufacturing precision of the part meets the pneumatic appearance requirement, but does not meet the precision requirement of the positioning characteristic of the tool, and the appearance cannot be utilized for positioning.

3) The sagging features of the part are more and a design compensation amount of 1-2 mm is left over the sagging depth for adding a compensation spacer to eliminate manufacturing cumulative errors, as shown in the isometric view E of fig. 2 (a). However, the actual compensation clearance value is not easy to measure, the processing precision of the gasket is difficult to ensure, the cycle time for preparing the gasket is long, the precision is not high, the assembly stress is generated after the fastening pieces are connected, and the assembly quality of the aircraft is affected.

The conventional assembly method cannot solve the above problems. Therefore, a flexible assembly method for accommodating the manufacturing errors of the parts is required to be designed, the structural characteristics of the parts are suitable, the design intention is achieved, the functions of the parts are exerted, and the design level of the aircraft assembly process is improved.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides an aircraft flexible assembly method for accommodating part manufacturing errors, which comprises a flexible assembly process for accommodating part manufacturing errors, product positioning realized by utilizing point characteristics, flexible assembly tooling design, assembly gap model encapsulation and assembly gap elimination in a solid-liquid mixing mode.

The invention adopts the technical scheme that:

an aircraft flexible assembly method for accommodating manufacturing errors of parts, which comprises 10 steps including comprehensive digital measurement, positioning direction definition, reverse and 3D printing, and referring to FIG. 1, the flexible assembly method comprises the following steps:

step 1, designing a part positioning scheme: according to the shape design positioning scheme of the part, the positioning scheme comprises the positioning characteristics and the clamping modes of the part, namely the positioning point and the vector direction of the part, and when the positioning scheme is used for designing a flexible assembly tool, the position of the positioner, the flexible adjustment direction and the adjustment amount of the positioner are determined, as shown in fig. 3.

Step 2, designing a flexible assembly tool: according to the flexible assembly fixture designed according to the part positioning scheme, the flexibility of the flexible assembly fixture is reflected in the adjustment function of the positioner in the positioning point vector direction, and the positioner is adjusted according to the actual space position of the positioning point of the part, so that the problem that the positioning point of the part cannot be smoothly positioned on the flexible assembly fixture due to too large manufacturing deviation after the positioner is installed according to the position of the theoretical model is avoided, as shown in fig. 4 (a) and fig. 4 (b).

Step 3, part appearance scanning: after the part is manufactured, the shape of the part is scanned to form a part point cloud, and meanwhile, another part point cloud which has an assembly relation with the part is generated, and the point cloud is used for subsequent virtual assembly and encapsulation modeling, as shown in fig. 10.

Step 4, virtually assembling the part point cloud and the flexible assembly tool: and (3) taking a theoretical model of the part as a reference, carrying out best fitting on the point cloud of the part, wherein the fitted point cloud gesture is the best mounting gesture of the actual part. And virtually assembling the fitted point cloud and a theoretical model of the flexible assembly tool, measuring the 3D distances between the spherical centers of all the top ends of the positioners and the point cloud of the part, wherein the 3D distances are positive, gaps exist between the positioners and the part, and when the 3D distances are negative, the positioners interfere with the part, as shown in fig. 9, so that the adjustment quantity of the positioners in the flexible assembly tool is calculated.

Step 5, assembly clearance analysis between parts: and virtually assembling the point cloud of the part and the point cloud of the part assembled with the point cloud of the part, measuring the gap of an assembly connection area, namely a part sinking area, and respectively integrating the area larger than 0.5mm and the area smaller than 0.5mm according to the measurement result, as shown in fig. 11.

Step 6, packaging and modeling an assembly gap: and (3) selecting a point cloud with a gap larger than 0.5mm according to the analysis result of the step (5), and packaging the point cloud into a closed curved surface, wherein the closed curved surface is the shape outline of the compensation gasket, so as to obtain a compensation gasket model, as shown in fig. 12 and 13.

Step 7,3D printing of a compensation gasket: and (3) processing the compensation gasket by adopting a 3D printing technology according to the compensation gasket model generated in the step (6). The reason that adopts 3D to print is that compensation gasket is the variable thickness, can't sheet metal forming, and thickness thinnest department reaches 0.5mm, also can't realize through the machine that adds.

Step 8, flexible assembly fixture adjustment: and (3) adjusting the positioners according to the analysis result of the step (4) and the adjustment direction and adjustment quantity of each positioner obtained by calculation, wherein the positioners are used for realizing the accurate positioning of the parts on the flexible assembly tool, and the positions are consistent with the gesture after the virtual assembly of the step (4).

Step 9, positioning parts by using a flexible assembly tool: placing the part on a flexible assembly tool, ensuring that the locator is in contact with the surface of the part, and then fixing the part by using a compactor.

Step 10, eliminating an assembly gap by adopting a solid-liquid mixing mode: and (3) installing the compensation gasket printed in the step (7) in a sinking area of the positioned part, coating the liquid gasket, filling a small gap by utilizing the semi-solid fluidity, extruding the redundant liquid gasket by using a fastener after coating, and curing for 24 hours to finish the coordinated assembly of the part, as shown in fig. 14 and 15.

Further, in the step 1, the part positioning scheme specifically includes: 6 points are selected as positioning points on the surface of the part theoretical model, the 6 points are divided into 3 groups, the first group comprises 3 points, the second group comprises 2 points, and the third group comprises the rest 1 points; the vector directions of the points in each group are kept consistent, and the vector directions among the groups are mutually perpendicular; the 3 points of the first group form a plane for controlling 3 degrees of freedom of the part, the 2 points of the second group form a line for controlling 2 degrees of freedom of the part, and the 1 point of the remaining third group controls 1 degree of freedom, so that 6 degrees of freedom of the part are all controlled without overconstraint.

The traditional plane component positioning selects the surface characteristics and hole characteristics of the parts, and has the advantages of reliable feature precision, easiness in realization, more limited freedom degrees, capability of limiting 3 freedom degrees by the surface, capability of limiting 4 freedom degrees by the hole, over-constraint of a plurality of feature positioning, namely overlapping of the limitation of the freedom degrees. The traditional fixture positioner is designed according to the surface characteristics and the hole characteristics, and adopts the forms of surfaces, grooves, holes and pins. However, when the feature accuracy of the part is low, such design is not practical because the relative positions between the features of the part do not match the relative positions of the features of the fixture positioner, and there is also an over-constraint that the part cannot be positioned by the fixture. Therefore, the invention changes the traditional positioning mode, replaces the hole feature and the surface feature with the point feature of the part, and uniformly coordinates the vector directions of the point feature, thereby avoiding the coordination problem caused by over-constraint, as shown in figure 3.

The coordinate values of 6 positioning points on the part theoretical model are the initial positions of the positioners when the flexible assembly tool is designed, and the vector direction of each positioning point is the adjustable direction of the positioners, so that the theoretical model of the flexible assembly tool is designed. After the part is manufactured, the manufacturing error is represented by the displacement of the positions of the 6 positioning points in the vector direction, so that the positioner and the part are interfered or a gap is generated. Because the position change of each positioning point is only displacement in 1 vector direction, the flexible assembly fixture is easy to adjust; if the positioning is not a point, but a surface, the tool is difficult to change shape for adjustment. This is an advantage of the present invention where the dot features are used instead of the face and aperture features.

Further, in the step 2, the flexible assembly fixture includes a positioning plate and 6 positioners fixedly connected to the positioning plate, the positioners are divided into two types, namely a horizontal positioner 2 and a vertical positioner 1, the flexible adjustment direction of the horizontal positioner 2 is parallel to the direction of the positioning plate, the flexible adjustment direction of the vertical positioner 1 is perpendicular to the direction of the positioning plate, and the flexible adjustment direction of each positioner is parallel to the vector direction of the corresponding positioning point, so that the number and the positions of the two types of positioners are determined according to the vector direction and the position of the corresponding positioning point; the locator adopts a spherical locator to realize point contact with the part, so that the problem of locator coordination caused by shape errors of the part is avoided.

The vertical positioner 1 comprises a cylinder with a spherical top end and a plurality of gaskets 3 fixedly installed between a positioning plate and the bottom end of the cylinder, wherein the length of the cylinder is determined according to the height of a corresponding positioning point, the gaskets 3 are made of steel materials, each gasket 3 comprises a series of gaskets 3 with different thickness d, the specification interval of the thickness d is 4mm to 6mm, the thickness interval is 0.05mm, the initial thickness is 5mm, the gaskets 3 are replaced according to specific adjustment quantity requirements, and the adjustment on the direction of the vertical positioning plate is realized, as shown in fig. 7.

The horizontal positioner 2 comprises a positioning column fixedly connected with a positioning plate and a plurality of positioning units 4 fixedly connected to the top end of the positioning column, the length of the positioning column is determined according to the height of a corresponding positioning point, the positioning units 4 are made of steel materials, the structure is that 1 ball head positioning unit is arranged on a base plate, the ball head positioning unit is located at the center of the base plate, two bolt holes with fixed intervals are formed in the base plate, the connecting lines of the two bolt holes are parallel to the symmetrical axis of the base plate, the two bolt holes are symmetrically formed in two sides of the ball head positioning unit, the distance between the connecting lines of the two bolt holes and the symmetrical axis of the base plate is delta, the positioning units 4 with the plurality of specifications comprise a series of positioning units 4 with different distances delta, the distance delta interval is 0 to 1mm, the initial distance is 0.05mm, the proper positioning units 4 are selected according to specific adjustment amount requirements, and adjustment in the direction parallel to the base plate is achieved, meanwhile, the horizontal positioner 2 comprises two mutually perpendicular mounting directions, and adjustment in the mutually perpendicular directions in the plane parallel to the base plate is achieved, as shown in fig. 8.

Further, in the step 4, the adjustment amount and direction calculation method of the positioner is as follows: as shown in fig. 9, after the part point cloud is virtually assembled with the flexible assembly fixture, 6 feature points are created by using the coordinates of the sphere center of the positioner, the positions of the positioner are replaced by the feature points, the 3D distances between all the feature points and the part point cloud are measured, the vector direction of the measured distances is the adjustment direction of the positioner, specifically, when the adjustment quantity of the positioner = the radius r-of the ball head of the positioner is greater than r, the adjustment direction is close to the direction of the part, and when s is less than r, the adjustment direction is far away from the direction of the part.

Further, in the step 6, the assembly gap encapsulation modeling is to construct a compensation spacer model for filling the assembly gap by using the point cloud data after the virtual assembly of the parts, as shown in fig. 12 and 13, and includes the following steps:

and 6.1, integrating the region which is measured to be larger than 0.5mm after virtual assembly in the step 5, reserving the point cloud of the region, deleting all other point clouds, wherein the point cloud is divided into two parts, one part is a sinking region point cloud of the part, the other part is an assembly region point cloud assembled with the sinking region on the other part, and the region point cloud is in an unsealed state.

And 6.2, respectively utilizing the point cloud of the subsidence area and the point cloud of the assembly area to generate stl triangulation grids, respectively generating Nurbs curves, forming a plurality of Nurbs curved surfaces according to the Nurbs curves, respectively connecting the plurality of Nurbs curved surfaces of the subsidence area and the assembly area into 1 Nurbs curved surface to obtain 2 Nurbs curved surfaces, and respectively converting the 2 Nurbs curved surfaces into two Nurbs models, as shown in figure 12.

And 6.3, inserting a cuboid-shaped model between the two Nurbs models, intersecting the two Nurbs curved surfaces, and reserving the part of the cuboid between the two curved surfaces, wherein the reserved part of the cuboid is closed, namely the packaging model with the assembly gap, as shown in fig. 13.

Furthermore, in the step 10, a method of eliminating the assembly gap by mixing solid and liquid is adopted, and the manufacturing error of the sinking area of the part can be eliminated after the compensation gasket is installed, but the manufacturing error cannot be completely eliminated, because the 3D printed compensation gasket has errors, and the assembly gap cannot be eliminated by 100% after the compensation gasket is installed in the sinking area of the part. Meanwhile, the region with the assembly gap smaller than 0.5mm is not filled, and the conventional hard pad has too low strength in the thickness region and can be damaged after being subjected to shearing force. If the gap is not treated, the parts are forced to deform at the position after the bolts are connected, so that larger assembly stress is generated, and the fatigue life of the product is influenced. The method for eliminating the assembly clearance of the solid-liquid mixture is characterized in that a layer of liquid gasket with the thickness of about 1mm is coated on a sinking area under the condition of installing a compensation gasket, the liquid gasket is made of a semi-solid colloidal material, and the material is formed by mixing resin and glass fibers. The excess liquid shim is removed from the depressed assembly area by the compressive force of the assembly, similar to the compressive sealing process, as shown in fig. 13 and 14. The specific steps are as follows:

step 10.1, preparing a liquid gasket by using resin and glass fiber, wherein the weight ratio of the resin to the glass fiber is 20:1, and uniformly mixing at room temperature;

step 10.2, coating a liquid gasket on the sinking area of the positioned part, wherein the thickness of the liquid gasket is 1mm;

step 10.3, assembling the other part with the positioned part, removing redundant liquid gaskets through the extrusion force of the bolts, and cleaning;

and step 10.4, curing for 24 hours, and completing all gasket installation work.

The invention has the beneficial effects that: the invention provides a flexible assembly method for accommodating manufacturing errors of parts, which solves the problems that complex parts cannot be accurately positioned on a tool and the design of a compensation gasket is difficult to manually assemble, shortens the assembly period, greatly improves the assembly precision and ensures the assembly quality of an airplane.

Drawings

FIG. 1 is a process flow diagram of a flexible assembly method.

Fig. 2 (a) is an isometric view of the profile of a complex part, where E is a depression.

Fig. 2 (b) is an a-direction view of fig. 2 (a).

Fig. 2 (c) is a D-view of fig. 2 (b).

Fig. 3 is a schematic view of a part positioning point, wherein (a) is a C-direction view of fig. 2 (B), (B) is an a-direction view of fig. 2 (a), and (C) is a B-direction view of fig. 2 (a), points h, i and j are positioning points of a first group, points k and m are positioning points of a second group, and points n are positioning points of a third group.

Fig. 4 (a) is a schematic structural diagram of the flexible assembly fixture.

Fig. 4 (b) is an assembly schematic diagram of the flexible assembly fixture.

Fig. 5 is a schematic diagram of the direction of adjustment of the positioner.

Fig. 6 is a schematic view of a center of a positioner, wherein (a) is a horizontal positioner and (b) is a vertical positioner, and F represents the center of the positioner.

Fig. 7 is a schematic diagram of a multi-gauge gasket.

FIG. 8 is a schematic diagram of a multi-gauge positioning unit.

Fig. 9 is a schematic diagram of 3D distance measurement, wherein (a) is a schematic diagram of horizontal positioner measurement, and (b) is a schematic diagram of vertical positioner measurement.

Fig. 10 is a schematic view of a point cloud virtual assembly, in which H represents a part sagging area point cloud, I represents another part assembly area point cloud, and J represents an assembly gap.

FIG. 11 is a schematic illustration of the determination of the mounting area of the compensation spacer, where K represents the point cloud for areas with gaps greater than 0.5 mm.

Fig. 12 is a schematic diagram of a Nurbs surface construction process.

Fig. 13 is a schematic diagram of a process of packaging a compensation gasket model, in which L represents a concave curved surface of a part, M represents an assembled curved surface of another part, N represents a rectangular parallelepiped, O represents an assembled surface of a compensation gasket and another part, and P represents an assembled surface of a compensation gasket and a concave area of a part.

Fig. 14 is a schematic diagram of mounting a compensation spacer, in which Q represents the compensation spacer.

Fig. 15 is a schematic view of a coated liquid shim where R represents the liquid shim.

In the figure: 1 a vertical positioner; 2 a horizontal positioner; 3, a gasket; and 4, positioning units.

Detailed Description

The technical solutions of the present invention will be clearly and completely described below, examples of which are illustrated in the accompanying drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which may be modified or adapted by persons of ordinary skill in the art based on the embodiments of this invention, are within the scope of this invention.

An aircraft flexible assembly method for accommodating part manufacturing errors, the flow of which is shown in fig. 1, the flexible assembly method comprising the following steps:

1) Designing a part positioning scheme according to the appearance and assembly requirements of the part; 6 points are selected as positioning points on the surface of the part theoretical model, the 6 points are divided into 3 groups, the first group comprises 3 points (such as h, i and j points in fig. 3 a), the second group comprises 2 points (such as k and m points in fig. 3 b), and the third group comprises the rest 1 point (such as n points in fig. 3 c); the vector directions of the points in each group are kept consistent, and the vector directions among the groups are mutually perpendicular; the 3 points of the first group form a plane for controlling 3 degrees of freedom of the part, the 2 points of the second group form a line for controlling 2 degrees of freedom of the part, and the 1 point of the remaining third group controls 1 degree of freedom, so that 6 degrees of freedom of the part are all controlled without overconstraint.

2) Designing a flexible assembly tool according to a part positioning scheme; the coordinate values of 6 positioning points on the part theoretical model are the initial positions of the positioners when the flexible assembly tool is designed, and the vector direction of each positioning point is the adjustable direction of the positioners, so that the theoretical model of the flexible assembly tool is designed.

The flexible assembly fixture comprises a locating plate and 6 locators fixedly connected to the locating plate, wherein the locators comprise 3 horizontal locators 2 and 3 vertical locators 1, as shown in fig. 4 (a), and after locating and mounting, the locating plate is shown in fig. 4 (b).

The vertical positioner 1 comprises a spherical column body at the top end and a plurality of specifications of gaskets 3 fixedly installed between a positioning plate and the bottom end of the column body, wherein the length of the column body is determined according to the height of a corresponding positioning point, the gaskets 3 are made of steel materials, the specification is 20 x 8.5 x d (mm), d is the thickness of the gaskets 3, the vertical positioner comprises a series of gaskets 3 with different thickness d, the specification interval of the thickness d is 4mm to 6mm, the thickness interval is 0.05mm, the initial thickness is 5mm, the gaskets 3 are replaced according to specific adjustment quantity requirements, as shown in fig. 7, and the adjustment in the direction of the vertical positioning plate is realized, as shown in fig. 5.

The horizontal positioner 2 comprises a positioning column fixedly connected with a positioning plate and a plurality of positioning units 4 fixedly connected to the top end of the positioning column, the length of the positioning column is determined according to the height of a corresponding positioning point, the positioning units 4 are made of steel materials, the structure is that 1 ball head positioning unit is arranged on a base plate, the ball head positioning unit is located at the center of the base plate, two bolt holes with the fixed distance of 325mm are formed in the base plate, the aperture of 4mm is 9mm thick, the connecting lines of the two bolt holes are parallel to the symmetrical axis of the base plate, the two bolt holes are symmetrically arranged on two sides of the ball head positioning unit, the distance between the connecting lines of the two bolt holes and the symmetrical axis of the base plate is delta, the positioning units 4 with the plurality of specifications comprise a series of positioning units 4 with different distances delta, the distance delta interval is 0 to 1mm, the distance interval is 0.05mm, the initial distance is 0, as shown in fig. 8, the proper positioning units 4 are selected according to specific adjustment quantity requirements, and adjustment in the direction parallel to the base plate is realized, meanwhile, the horizontal positioner 2 comprises two mutually perpendicular installation directions, and the mutually perpendicular directions are used for realizing mutual adjustment in the direction parallel to the plane of the base plate.

3) And manufacturing and installing the flexible tool, and recording initial values of the sphere centers (F in figure 6) of the 6 positioners for subsequent adjustment calculation, as shown in figure 6.

4) And manufacturing the part to be installed.

5) Erecting digital scanning equipment, scanning the appearance of the part to be installed, ensuring the scanning accuracy to be within +/-0.1 mm, and forming the point cloud of the part to be positioned.

6) By adopting the method, the other assembly part which is in assembly relation with the part to be assembled is measured, and the point cloud of the part is also generated.

7) The part point cloud is virtually assembled with the assembly fixture, and the part point cloud is best fit by taking a theoretical model of the part as a reference, as shown in fig. 9. Virtually assembling the fitted point cloud and the theoretical model of the flexible assembly tool, importing the numerical values recorded in the step 3), creating 6 characteristic points, replacing the positions of the locators with the points, measuring the 3D distances between all locators and the point cloud of the part, wherein the vector direction of the measured distances is the adjustable direction of the locators, the radius of the locator sphere is 4mm assuming that the measured distances are s, the adjustment quantity of the locators is 4-s, when s is greater than 4, the adjustment direction is close to the direction of the part, and when s is less than 4, the adjustment direction is far away from the direction of the part.

8) And analyzing the assembly gap between the parts, and virtually assembling the point cloud of the part to be installed and the point cloud of the assembled part, as shown in fig. 10. The gap of the fitting connection region (shown as J in fig. 10) including the part to be mounted sagging region (region H in fig. 10), the fitting part fitting region (region I in fig. 10), and the region greater than 0.5mm and the region less than 0.5mm are respectively integrated according to the measurement result, as shown in fig. 11, is measured.

9) The assembly gap package for the depressed area is modeled according to the analysis result of step 8, as shown in fig. 12 and 13. A point cloud with a gap greater than 0.5mm is selected (shown as K in fig. 11) and packaged into a closed curved surface, which is the shape contour of the compensation pad. The point cloud is currently divided into two parts, one part is the sinking point cloud of the part to be positioned, and the other part is the part of the point cloud on the other part assembled with the sinking. The current point cloud is still in an unsealed state. The stl triangulation grid is generated by utilizing the two part point clouds, then Nurbs curves are generated respectively, a plurality of Nurbs curved surfaces are formed according to the Nurbs curves, and then the plurality of Nurbs curved surfaces are connected into 1 Nurbs curved surface respectively. In this way, the two part point clouds are changed into 2 Nurbs curved surfaces (L is a sinking curved surface of the part to be installed in fig. 13, M is an assembling curved surface of the assembling part), and then the Nurbs curved surfaces are respectively converted into two Nurbs models, and the model format is igs, as shown in fig. 12. At this time, the igs file having two curved surfaces is still not in a packaged state, the igs file is now imported into CATIA software, a model in a cuboid shape (e.g., N in fig. 13) is inserted between the two curved surfaces, the two curved surfaces intersect with the CATIA software, the cuboid is cut by the two curved surfaces, a portion between the two curved surfaces of the cuboid is reserved, at this time, the remaining portion of the cuboid is closed, the portion is a packaging model of an assembly gap (e.g., O is an assembly profile of a compensation gasket and an assembly part, P represents an assembly profile of the compensation gasket and a subsidence area of the part to be assembled, and the format of the model is converted into stl, so that the 3D printing device can be processed and molded.

10 3D print compensation pad: and (3) processing the compensation gasket by adopting a 3D printing technology according to the packaging model of the assembly gap generated in the step (9).

9) According to the step 7), adjusting the positioner of the flexible assembly tool, firstly, detaching the 5mm spacer 3 on the vertical positioner 1, replacing the 5+4-s spacer 3 when the distance needs to be reduced, and replacing the 5- (4+s) spacer 3 when the distance needs to be increased; and then the positioning unit 4 with the distance of 0 between the connecting line of the bolt hole of the upper bottom plate of the horizontal positioner 2 and the symmetrical axis of the bottom plate is detached, the positioning unit 4 with the specification of 4-s is replaced when the distance needs to be increased, and the positioning unit 4 with the specification of- (4-s) is replaced when the distance needs to be reduced.

12 Placing the parts to be mounted on a flexible assembly tool, ensuring that each locator is in surface contact with the parts to be mounted, and then fixing the parts to be mounted by using a compactor.

13 The printed compensation spacer is mounted on the depressed area of the part to be mounted as shown by Q in fig. 14. And a liquid shim of about 1mm thickness was applied over the entire depressed area as shown by R in fig. 15. And assembling the part and the other part by using the fastener, extruding redundant liquid gaskets by the extrusion force of the bolts, and cleaning. Wherein, the liquid gasket is configured by resin and glass fiber, the weight ratio of the resin to the glass fiber is 20:1, and the liquid gasket and the glass fiber are uniformly mixed.

14 The redundant liquid gasket is cleaned, and after 24 hours, the liquid gasket is completely solidified, so that the installation of all fasteners is completed.

This description is to be construed as illustrative only and not as a whole and all other embodiments, which may be devised or adapted by those skilled in the art, are intended to fall within the scope of this invention.

Claims (8)

1. An aircraft flexible assembly method for accommodating manufacturing errors of parts, which is characterized by comprising the following steps:

step 1, designing a part positioning scheme: the method comprises the steps of designing a positioning scheme according to the shape of a part, wherein the positioning scheme comprises positioning points and vector directions of the part, and is used for determining the position of a positioner, the flexible adjustment direction and adjustment amount of the positioner when designing a flexible assembly tool;

step 2, designing a flexible assembly tool: designing a flexible assembly tool according to a part positioning scheme, wherein the positioner has an adjusting function in the positioning point vector direction;

step 3, part appearance scanning: after the part is manufactured, carrying out shape scanning on the part to form a part point cloud, and generating another part point cloud with an assembly relation with the part;

step 4, virtually assembling the part point cloud and the flexible assembly tool: taking a theoretical model of the part as a reference, and performing best fitting on the part point cloud; virtually assembling the fitted point cloud and a theoretical model of the flexible assembly tool, measuring 3D distances between the centers of spheres at the top ends of all positioners and the point cloud of the part, and further calculating the adjustment quantity of the positioners in the flexible assembly tool;

step 5, assembly clearance analysis between parts: virtually assembling the point cloud of the part and the point cloud of the part assembled with the point cloud of the part, measuring an assembly connection area, and respectively integrating an area larger than 0.5mm and an area smaller than 0.5mm according to a measurement result;

step 6, packaging and modeling an assembly gap: according to the analysis result of the step 5, selecting point clouds with gaps larger than 0.5mm, and packaging the point clouds into a closed curved surface to obtain a compensation gasket model;

step 7, processing the compensation gasket according to the compensation gasket model generated in the step 6;

step 8, flexible assembly fixture adjustment: according to the analysis result of the step 4 and the adjustment direction and adjustment amount of each positioner obtained by calculation, the positioners are adjusted;

step 9, positioning parts by using a flexible assembly tool: placing the part on a flexible assembly tool, ensuring that the locator is in contact with the surface of the part, and then fixing the part;

step 10, eliminating an assembly gap by adopting a solid-liquid mixing mode: and installing the compensation gasket in the sinking area of the positioned part, coating the liquid gasket, filling a small gap by utilizing the semisolid fluidity, and curing the redundant liquid gasket after coating for 24 hours to finish the coordinated assembly of the part.

2. The aircraft flexible assembly method for accommodating manufacturing errors of parts according to claim 1, wherein in the step 1, the part positioning scheme specifically comprises: 6 points are selected as positioning points on the surface of the part theoretical model, the 6 points are divided into 3 groups, the first group comprises 3 points, the second group comprises 2 points, and the third group comprises the rest 1 points; the vector directions of the points in each group are kept consistent, the vector directions among the groups are mutually perpendicular, and therefore 6 degrees of freedom of the part are all controlled without over constraint.

3. The aircraft flexible assembly method for accommodating manufacturing errors of parts according to claim 1, wherein in the step 2, the flexible assembly fixture comprises a positioning plate and 6 positioners fixedly connected to the positioning plate, the positioners are divided into two types of horizontal positioners (2) and vertical positioners (1), the flexible adjustment direction of the horizontal positioners (2) is parallel to the direction of the positioning plate, the flexible adjustment direction of the vertical positioners (1) is perpendicular to the direction of the positioning plate, the flexible adjustment direction of each positioner is parallel to the vector direction of the corresponding positioning point, and the number and the positions of the two types of positioners are determined according to the corresponding positioning point; the locator adopts a spherical locator;

the vertical positioner (1) comprises a spherical column body with a spherical top end and a plurality of specifications of gaskets (3) fixedly arranged between a positioning plate and the bottom end of the column body, the length of the column body is determined according to the height of a corresponding positioning point, the vertical positioner comprises a series of gaskets (3) with different thickness d, the specification interval of the thickness d is 4mm to 6mm, the thickness interval is 0.05mm, the initial thickness is 5mm, and the gaskets (3) are replaced according to specific adjustment quantity requirements, so that the adjustment in the direction of the vertical positioning plate is realized;

the horizontal positioner (2) comprises a positioning column fixedly connected with a positioning plate and a plurality of positioning units (4) fixedly connected to the top end of the positioning column, the length of the positioning column is determined according to the height of a corresponding positioning point, the positioning units (4) are 1 ball head positioning units arranged on a base plate, the ball head positioning units are positioned at the center of the base plate, two bolt holes with fixed intervals are formed in the base plate, the connecting lines of the two bolt holes are parallel to the symmetrical axis of the base plate, the two bolt holes are symmetrically arranged on two sides of the ball head positioning units, the distance between the connecting lines of the two bolt holes and the symmetrical axis of the base plate is delta, the positioning units (4) with the plurality of specifications comprise a series of positioning units (4) with different distances delta, the distance delta interval is 0 to 1mm, the initial distance is 0.05mm, the proper positioning units (4) are selected according to specific adjustment amount requirements, and adjustment in the direction parallel to the base plate is achieved.

4. A method of aircraft flexible assembly for accommodating manufacturing tolerances of parts according to claim 3, wherein the spacer (3) and the positioning unit (4) are made of steel.

5. The aircraft flexible assembly method for accommodating manufacturing errors of parts according to claim 1, wherein in the step 4, the adjustment amount and direction calculation method of the positioner is as follows: after the part point cloud and the flexible assembly tool are virtually assembled, 6 characteristic points are created by the sphere center of the positioner, the position of the positioner is replaced by the characteristic points, the 3D distance between all the characteristic points and the part point cloud is measured, the vector direction of the measured distance is the adjusting direction of the positioner, specifically, the adjusting quantity of the positioner = the radius r-of the sphere of the positioner-the measured distance s, when s is larger than r, the adjusting direction is close to the direction of the part, and when s is smaller than r, the adjusting direction is far away from the direction of the part.

6. The aircraft flexible assembly method for accommodating manufacturing errors of parts according to claim 1, wherein in the step 6, the assembly gap encapsulation modeling is to construct a compensation gasket model for filling the assembly gap by using point cloud data after virtual assembly of the parts, and the method comprises the following steps:

step 6.1, integrating the area with the thickness of more than 0.5mm measured in the step 5 after virtual assembly, reserving point clouds of the area, deleting all other point clouds, wherein the point clouds are divided into two parts, one part is a sinking area point cloud of a part, the other part is an assembly area point cloud assembled with the sinking area on the other part, and the area point clouds are in an unsealed state;

step 6.2, generating stl triangulation grids by using the point cloud of the subsidence area and the point cloud of the assembly area respectively, then generating Nurbs curves respectively, forming a plurality of Nurbs curved surfaces according to the Nurbs curves, connecting the plurality of Nurbs curved surfaces of the subsidence area and the assembly area respectively into 1 Nurbs curved surface to obtain 2 Nurbs curved surfaces, and converting the 2 Nurbs curved surfaces into two Nurbs models respectively;

and 6.3, inserting a cuboid-shaped model between the two Nurbs models, intersecting the two Nurbs curved surfaces with the cuboid-shaped model, and reserving the part of the cuboid between the two curved surfaces, namely the packaging model of the assembly gap.

7. An aircraft flexible assembly method for accommodating part manufacturing errors according to claim 1, wherein in step 7, the compensation spacer is processed by 3D printing.

8. The aircraft flexible assembly method for accommodating manufacturing errors of parts according to claim 1, wherein the step 10 adopts a solid-liquid mixed assembly clearance elimination method, and the specific steps are as follows:

step 10.1, preparing a liquid gasket by using resin and glass fiber, wherein the weight ratio of the resin to the glass fiber is 20:1, and uniformly mixing at room temperature;

step 10.2, coating a liquid gasket on the sinking area of the positioned part;

step 10.3, assembling the other part with the positioned part, removing redundant liquid gaskets through extrusion force, and cleaning;

and step 10.4, curing for 24 hours, and completing all gasket installation work.