Method for preventing welding deformation of wing framework and skin

Abstract

The invention relates to a method for preventing welding deformation of a wing framework and a skin, belongs to the technical field of welding, and solves the problem that the welding deformation is easy to occur when the existing laser welding technology is used for welding the wing framework and the skin. The invention discloses a method for preventing welding deformation of a wing framework and a skin. The method comprises the following steps that S1, a tool clamp used for welding the wing framework and the wing framework and the skin is designed; s2, parts of the wing framework to be welded are assembled on the base plate; s3, after assembly, chord plane measurement is carried out; s4, the joints of the wing framework are welded in a laser welding mode; and S5, chord plane measurement and shape correction are carried out on the wing framework obtained through welding. By optimizing the tool clamp, the assembly procedure, the welding sequence, chord plane measurement and shape correction, the deformation problem of the wing framework and the skin in the laser welding process is effectively controlled and reduced, and the welding deformation can be controlled to be + / -0.5% or below.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a method for preventing welding deformation of a wing frame and a skin. Background Art

[0002] As an advanced welding technology, laser welding has many advantages in wing manufacturing, such as high energy density, precise heat input control and small heat affected zone, etc. However, this technology also has some difficulties in the wing laser welding process, especially the problem of welding deformation.

[0003] The welding deformation of laser welding when applied to wing manufacturing mainly comes from the following reasons: (a) High energy density: Laser welding has high energy density, and the energy is concentrated in a small area, which will cause the temperature of the welding point and its surrounding area to rise rapidly, thereby generating thermal expansion; (b) Temperature gradient: During the welding process, due to the action of the laser beam, the temperature distribution of the welding area and the surrounding materials is uneven, forming a significant temperature gradient; this uneven temperature field will lead to uneven thermal expansion of the material, and then generate thermal stress and thermal deformation; (c) Structural and material properties: Materials commonly used in wing manufacturing, such as titanium alloy and aluminum alloy, have lower thermal conductivity and higher thermal expansion coefficient, which makes them more prone to deformation during laser welding; and the wing skeleton is usually composed of criss-cross beams and ribs and are all thin-walled parts. There are many welding joints and the rigidity of thin-walled parts is poor, resulting in an increase in key positions prone to welding deformation.

[0004] It can be seen that welding deformation is a common problem in the wing welding process, which may bring a series of hazards to the performance and safety of the aircraft. Therefore, it is urgent to provide a method that can effectively control and prevent welding deformation of the wing frame and skin, which is of great significance for ensuring the welding quality of the aircraft wing and ensuring the safety and reliability of the aircraft. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a method for preventing welding deformation of the wing frame and skin, so as to solve the problem that welding deformation is prone to occur when the existing laser welding technology is used to weld the wing frame and skin.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The present invention provides a method for preventing welding deformation of a wing frame and a skin, comprising the following steps:

[0008] S1. Design of fixtures for welding wing frames and wing frames and skins;

[0009] The wing skeleton comprises: M longitudinal members distributed in parallel along a first direction and N transverse members distributed in parallel along a second direction, each transverse member comprises M-1 transverse ribs, the M longitudinal members and N×(M-1) transverse ribs are connected by 2×N×(M-1) joints to form a grid structure, M≥3, N≥3; the first direction is different from the second direction;

[0010] The fixture of the wing frame includes: a base plate, a positioning mechanism and a clamping mechanism arranged on the base plate; the clamping mechanism includes three types: a pressing mechanism, a side pressure mechanism, and a pushing mechanism;

[0011] S2. Assemble the parts of the wing frame to be welded on the base plate, and control the relative position and welding deformation of each part through a reasonably designed positioning mechanism, a clamping mechanism, a side pressure mechanism, and a pushing mechanism; specifically, the following steps are included:

[0012] S21: Coordinate the first longitudinal member with the positioning mechanism to position the first longitudinal member; respectively set a side pressure mechanism in the 1 / 5 to 2 / 5 and 3 / 5 to 4 / 5 sections between any two adjacent joints of the first longitudinal member, and set a clamping mechanism in the 2 / 5 to 3 / 5 section;

[0013] S22: assembling N transverse ribs on the base plate in sequence from one end to the other end of the first longitudinal member, and setting two side pressure mechanisms in the 1 / 3 to 2 / 3 section of each transverse rib;

[0014] S23: assembling the second longitudinal member on the base plate, and providing a side pressure mechanism at a 1 / 5 to 4 / 5 section of the second longitudinal member between any two adjacent joints;

[0015] Repeat S22 and S23 alternately to assemble the remaining M-3 longitudinal members and N×(M-2) transverse bars;

[0016] S24: assembling the Mth longitudinal member on the base plate, respectively providing a side pressure mechanism at the 1 / 5 to 2 / 5 and 3 / 5 to 4 / 5 sections of the Mth longitudinal member between any two adjacent joints, providing a clamping mechanism at the 2 / 5 to 3 / 5 section, and providing a push mechanism at the outside of the Mth longitudinal member and directly facing each joint;

[0017] S3. After assembly, measure the chord plane;

[0018] S4. Using laser welding, 2×N×(M-1) joints of the wing frame are welded in sequence: from one end to the other end along the first direction and from one side to the other side along the second direction to control welding deformation;

[0019] S5. Measure the chord plane of the welded wing frame and adjust its shape.

[0020] Furthermore, each clamping mechanism includes a clamping strip, and the two ends of the clamping strip are respectively placed on both sides of the first longitudinal member or the Mth longitudinal member to clamp and fix the first longitudinal member or the Mth longitudinal member on the base plate.

[0021] Furthermore, each side pressure mechanism includes a pressing plate, one end of which is pressed on the surface of any longitudinal member or transverse rib, and the other end is fixed on the base plate, thereby pressing and fixing the longitudinal member or transverse rib on the base plate.

[0022] Furthermore, each pushing mechanism includes a pushing block and a mounting seat, the pushing block includes a push rod and an end pressure portion connected to each other, the mounting seat is fixed on the base plate, the push rod is fixed in the mounting seat by a rotating connection, and the end pressure portion is driven to abut against the side wall of the Mth longitudinal member by rotating the push rod.

[0023] Further, the positioning mechanism includes W positioning pins, and the W lugs included in the first longitudinal member are matched with the W positioning pins to define a position of the first longitudinal member relative to the substrate along the first direction; W≥2.

[0024] Furthermore, it also includes:

[0025] In S1, the fixture for the wing frame and skin includes: a base plate, a frame side pressing mechanism and a skin pressing mechanism arranged on the base plate;

[0026] S6, assembling the wing frame and skin to be welded on the fixture of the wing frame and skin, and controlling the relative position and welding deformation of the wing frame and skin through the frame side pressure mechanism and the skin pressing mechanism; specifically comprising the following steps:

[0027] S61: assembling the wing frame on the base plate, and respectively providing a frame side pressure mechanism at the 1 / 5 to 2 / 5 and 3 / 5 to 4 / 5 sections of the first longitudinal member and the Mth longitudinal member of the wing frame located between any two adjacent joints;

[0028] S62: Cover the upper skin and the lower skin on the front and back surfaces of the wing frame, and set 2×(M+N-4) skin pressing mechanisms on the outer sides of the upper skin and the lower skin and along the contact portions of the M-2 longitudinal members and the N-2 transverse members in the wing frame with the upper skin and the lower skin;

[0029] S7. Measure the chord plane of the assembled wing frame and skin;

[0030] S8. A combination of the wing frame and the upper and lower skins is obtained by laser welding. Specifically, the welding sequence is as follows to control welding deformation:

[0031] S81: weld the contact parts of the second transverse member, the third transverse member, ... the N-1th transverse member and the skin in sequence from one end to the other end along the first direction; for each transverse member, weld in the same direction from one side to the other side along the second direction;

[0032] S82: weld the second longitudinal member, the M-1 longitudinal member, the third longitudinal member, the M-2 longitudinal member, etc. in sequence from both sides to the middle along the second direction to the contact portion between the 1 / 2*M longitudinal member or the 1 / 2*(M+1) longitudinal member and the skin, and for each of the longitudinal members, weld symmetrically from both ends to the middle along the first direction;

[0033] S83: performing bottom locking welding on the contact portions of the first longitudinal member, the Mth longitudinal member, the first transverse member and the Nth transverse member on the outer side of the wing frame and the skin;

[0034] S9. Measure the chord plane of the assembly and calibrate its shape.

[0035] Furthermore, each skin clamping mechanism includes a clamping strip, on which is opened a groove having a size sufficient to accommodate the contact surface between the longitudinal members or transverse members inside the wing frame and the skin and which passes through the upper and lower surfaces of the clamping strip. The clamping strip is moved along the first direction or the second direction to fix and clamp the wing frame together with the upper skin or lower skin covering the surface of the wing frame onto the base plate.

[0036] Furthermore, it also includes comparing the chord plane measurement results of S5 with those of S3, and comparing the chord plane measurement results of S9 with those of S7, to obtain the position and amount of deformation point, calibrate the wing skeleton and assembly, further eliminate minor deformations during laser welding, and ensure dimensional accuracy.

[0037] Further, the device for measuring the chord plane includes at least one of a laser scanner and a laser tracker; and / or,

[0038] Furthermore, the shaping method includes one or a combination of mechanical shaping, thermal shaping, cold shaping, and CNC shaping.

[0039] Further, the tooling fixture for welding the wing frame and the wing frame and the skin also includes a rotating mechanism coaxially arranged on both sides of the base plate;

[0040] S4 also includes welding the front weld of each joint of the wing frame first; then flipping the fixture through the rotating mechanism to weld the back weld of each joint; and then adjusting the fixture through the rotating mechanism to weld the side weld of each joint to reduce welding deformation.

[0041] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0042] The present invention provides a method for preventing welding deformation of wing frame and skin, which is optimized from multiple aspects (tooling fixture, assembly process, welding sequence, chord plane measurement and shape correction), effectively controlling and significantly reducing the deformation of wing frame and skin during laser welding, and the welding deformation can be controlled below ±0.5%;

[0043] (1) The present invention effectively controls the movement and dislocation during welding and significantly reduces welding deformation by optimizing the fixture and assembly process, including the positioning scheme and the clamping scheme (clamping mechanism type, clamping point location and number, and assembly sequence);

[0044] a. Positioning scheme: When assembling the parts of the wing frame, firstly, the positioning mechanism on the fixture cooperates with the first longitudinal member to determine its position relative to the base plate along the first direction, and this position is used as the reference position when installing other components to ensure the relative position of each component during assembly;

[0045] b. Clamping scheme: By selecting the appropriate type of clamping mechanism (including clamping mechanism, side pressure mechanism, pushing mechanism, frame side pressure mechanism, and skin clamping mechanism), and setting an appropriate number of clamping mechanisms at appropriate positions, and using a suitable assembly sequence to rigidly fix each part, ensure that the clamping force is evenly distributed and avoid unnecessary constraints in the welding area; at the same time, the base plate provides suitable support points for the parts to be welded, effectively controlling the movement and dislocation during welding, and significantly reducing welding deformation.

[0046] (2) The present invention reduces welding stress accumulation and deformation by optimizing the welding sequence;

[0047] Specifically, when welding the parts of the wing frame, a preferred welding sequence is adopted (including welding in sequence from one end to the other end along the first direction and from one side to the other side along the second direction); when welding the wing frame and the skin, a preferred welding sequence is first adopted (including welding M-2 longitudinal components from both sides to the middle along the second direction, and each longitudinal component is symmetrically welded from both ends to the middle along the first direction) for penetration welding, and then a preferred welding sequence is adopted (including welding the outermost longitudinal components first and then welding the outermost transverse components) for bottom lock welding; the above welding sequence can enable the weld to shrink more freely, reduce the accumulation of welding stress, and thus prevent deformation, cracking and other problems caused by residual stress generated during the welding process.

[0048] (3) The present invention further eliminates minor deformations during welding by measuring and correcting the chord plane;

[0049] Specifically, the chord plane is measured on the wing frame and the combination of the wing frame + upper and lower skins before and after welding, the deformation point positions and deformation amounts are compared, and the wing frame and the combination of the wing frame + upper and lower skins are calibrated to ensure the dimensional accuracy of the wing frame and skin after welding.

[0050] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0052] Figure 1 A schematic diagram (partial) of a wing skeleton provided by an embodiment of the present invention;

[0053] Figure 2 A schematic diagram (partial) of a wing frame on a fixture provided by an embodiment of the present invention;

[0054] Figure 3 In (a), Figure 2 The enlarged three-dimensional schematic diagram of part A in the middle, (b) Figure 2 The enlarged three-dimensional schematic diagram of part B in the middle, (c) Figure 2 The enlarged three-dimensional schematic diagram of the middle C part, (d) Figure 2 The enlarged three-dimensional schematic diagram of the D part in the middle, (e) Figure 2 The enlarged three-dimensional schematic diagram of the middle E part;

[0055] Figure 4 A schematic diagram (partial) of a wing frame and skin provided by an embodiment of the present invention;

[0056] Figure 5 A schematic diagram (partial) of a wing frame and skin on a fixture provided by an embodiment of the present invention;

[0057] Figure 6 A site map of welding deformation obtained by comparing the chord plane three-dimensional model of the wing skeleton before and after welding provided by an embodiment of the present invention;

[0058] Figure 7 A photo (partial) of the weld seam of the wing frame and skin lock bottom weld provided in an embodiment of the present invention;

[0059] Figure 8A photograph (partial) of an X-ray nondestructive test of the weld of the wing frame and skin lock bottom weld provided in an embodiment of the present invention;

[0060] Reference numerals:

[0061] 100-wing frame; 11-first main beam; 12-second main beam; 13-third main beam; 14-first transverse rib; 15-second transverse rib; 16-third transverse rib; 17-fourth transverse rib; 18-vent; 200-fixture for wing frame; 21-locating pin; 22a-clamping mechanism; 22b-side pressure mechanism; 22c-pushing mechanism; 23a-first rotating mechanism; 23b-second rotating mechanism; 24-connecting end; 25-butt joint; 26-step groove; 300-skin; 400-fixture for wing frame and skin; 41-skin clamping mechanism; 42-frame side pressure mechanism; 43a-first fixture rotating mechanism; 43b-second fixture rotating mechanism. DETAILED DESCRIPTION

[0062] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0063] The present invention provides a method for preventing welding deformation of a wing frame and a skin, comprising the following steps:

[0064] Step S1, designing a fixture for welding the wing frame and the wing frame and the skin;

[0065] The wing skeleton comprises: M longitudinal members distributed in parallel along a first direction and N transverse members distributed in parallel along a second direction, each transverse member comprises M-1 transverse ribs, the M longitudinal members and N×(M-1) transverse ribs are connected by 2×N×(M-1) joints to form a grid structure, M≥3, N≥3; the first direction is different from the second direction;

[0066] The tooling fixture of the wing frame includes: a base plate, a positioning mechanism arranged on the base plate, and a clamping mechanism; wherein the clamping mechanism includes three types: a pressing mechanism, a side pressure mechanism, and a pushing mechanism.

[0067] Preferably, the angle between the first direction and the second direction is 85° to 95°; illustratively, the angle between the first direction and the second direction is a right angle.

[0068] Preferably, the longitudinal members and the transverse ribs are rod-shaped members; more preferably, the longitudinal members and the transverse ribs are rod-shaped members with hollow structures.

[0069] Optionally, the cross-sectional shape of the longitudinal member and the transverse rib may be, but is not limited to, an I-shaped, a Π-shaped, or a combination thereof.

[0070] Preferably, the wall thickness of the longitudinal members and the transverse ribs is 2 mm to 10 mm; more preferably, the wall thickness of the longitudinal members and the transverse ribs is 2 mm to 3 mm.

[0071] Preferably, the longitudinal members and transverse ribs are made of titanium alloy, aluminum alloy, steel or a combination of the two.

[0072] Preferably, all longitudinal members and transverse ribs of the wing skeleton are manufactured by 3D printing; wherein, when establishing a 3D printed model, the M longitudinal members are designed to include 2×N×(M-1) connection ends along the second direction, so as to accurately butt with the two end faces of each transverse rib to form 2×N×(M-1) butt joints; the inner side edges of the longitudinal members and transverse members located at the outermost side of the wing skeleton are designed to include step grooves with the same thickness as the skin; ventilation holes are reserved on the longitudinal members and transverse ribs located inside the wing skeleton to connect each grid structure;

[0073] Preferably, the above 3D printing method further includes: after the 3D printing is completed, all longitudinal members and transverse ribs (mainly the surfaces to be welded) are machined and finished to further improve the accuracy of the alignment of the butt joints between the longitudinal members and transverse ribs, and between the outermost longitudinal members and transverse members of the wing skeleton and the skin. The machining finishing method can be selected as needed, including but not limited to one or a combination of milling, grinding, scraping, lapping, super finishing, and polishing.

[0074] For example, see Figure 3 (d) The third main beam 13 includes a connecting end 24 along the second direction to accurately butt with the left end surface of the fourth transverse reinforcement 17 to form a butt joint 25.

[0075] It is worth noting that compared with the T-joint between the longitudinal member and the transverse rib, the longitudinal member obtained by 3D printing and machining in the present invention forms a butt joint by connecting the end head with the two ends of the transverse rib one by one, which achieves at least the following beneficial effects: (1) Due to the symmetry of the butt joint formed at both ends of the transverse rib, it can provide a more uniform stress distribution in the welding area and reduce the risk of cracks and other welding defects caused by stress concentration; (2) The heat distribution during the welding of the butt joint is relatively uniform, which helps to reduce the occurrence of welding defects such as pores and lack of fusion; (3) The welding strength of the butt joint is higher and the weld width is smaller. No additional filling material or special edge design is required, which may be more economical in material use and is conducive to achieving the requirements of both lightweight and high strength of the wing.

[0076] For example, see Figure 3(e) The inner sides of the transverse member at the uppermost end of the wing frame and the longitudinal member at the rightmost end include a step groove 26, the height of which is the same as the thickness of the skin, so that the upper and lower skins overlap on the step groove 26 to form a butt joint with a flush surface.

[0077] It is worth noting that, compared with the case where the upper and lower skins are directly placed on the surface of the wing frame to form a lap joint, the present invention achieves at least the following beneficial effects by designing step grooves along the outermost sides of the wing frame for the skin to overlap on the step grooves to form a butt joint with a flush surface: (1) The contact area of ​​the welds around the wing frame and the skin is larger, which is beneficial to improving the welding strength of the bottom lock welds around the wing frame, and the weld width is smaller, which is beneficial to achieving a balance between light weight and high strength; (2) Since the contact area around the wing frame and the skin is larger, the heat distribution during welding is relatively uniform, which helps to reduce the occurrence of welding defects such as pores and unfused welds; (3) By utilizing the positioning function of the step groove, the positioning of the skin and the wing frame can be quickly achieved without the need for an additional positioning mechanism, and the relative position and structural stability of the skin and the wing frame can be maintained during the welding process, reducing the risk of cracks and other welding defects caused by stress concentration.

[0078] For example, see Figure 1 Ventilation holes are reserved on all longitudinal members and transverse ribs (such as the second main beam 12 and the third transverse rib 16) inside the wing frame to allow each grid structure to be connected.

[0079] It is understandable that the shape of the substrate depends on the shape of the wing frame and can be designed as needed, as long as it can support and support the parts to be welded of the wing frame. Figure 2 The substrate is in the shape of a grid-like thin plate, and each grid includes a hollow structure.

[0080] It should be noted that the positioning mechanism on the substrate includes W positioning pins, W ≥ 2; the W lugs included in the first longitudinal member are matched with the W positioning pins to limit the position of the first longitudinal member relative to the substrate along the first direction, and this position will serve as the reference position when other components are installed, thereby ensuring the relative position of each component during assembly.

[0081] Preferably, the positioning mechanism is arranged outside the area to be welded, avoiding the weld position and ensuring the accessibility of the welding tool; in a possible design, see Figure 2 The outer side of the first longitudinal member (i.e., the first main beam 11) includes two lugs spaced apart along the first direction, and each lug cooperates with a locating pin 21 on the base plate, i.e., the locating pin 21 passes through the inner hole on the lug to accurately position the first longitudinal member along the first direction at the position where the locating pin on the base plate is located.

[0082] It should be noted that the clamping mechanism on the substrate includes one or a combination of three types: a pressing mechanism, a side pressure mechanism, and a pushing mechanism, and the number and position of each type of clamping mechanism can be designed as needed.

[0083] Preferably, the clamping mechanism comprises a combination of three types: a clamping mechanism, a side pressure mechanism, and a pushing mechanism.

[0084] Preferably, each clamping mechanism includes a clamping strip, the two ends of which can be located on both sides of the same longitudinal member or transverse rib, and the longitudinal member or transverse rib is fixed and clamped on the substrate along the entire width direction to control the relative position of the parts to be welded in the wing frame and the thermal deformation during welding.

[0085] As an optional embodiment, the two ends of the compression strip are fixed to the base plate by threaded connection; for example, see Figure 2 and Figure 3 (a) The clamping mechanism 22a includes a clamping strip with inner holes at both ends for screws or bolts to pass through and be screwed into the base plate.

[0086] Preferably, each side pressure mechanism includes a clamping plate, one end of which may be located on the surface of the longitudinal member or transverse rib, and the other end of which is fixed to the base plate, and is used to fix and clamp the longitudinal member or transverse rib to the base plate along part or all of the width, so as to control the relative position of the parts to be welded in the wing frame and the thermal deformation during welding.

[0087] As an optional embodiment, the pressing sheet is fixed to the base plate by threaded connection; for example, see Figure 2 and Figure 3 (b) The side pressure mechanism 22b includes a pressure plate whose portion not in contact with the longitudinal member or the transverse rib has an inner hole for a screw or a bolt to pass through and be screwed into the base plate.

[0088] It is understandable that the number of inner holes on the clamping plate can be designed as needed; illustratively, the clamping plate includes two inner holes to achieve effective fixation while ensuring that the clamping force is evenly distributed to avoid deformation due to local over-tightening.

[0089] In a possible design, a blind groove is also provided on the clamping plate to accommodate the protrusion on the longitudinal member or the transverse rib to adapt to the non-planar shape of the parts to be welded in the wing frame and facilitate installation operations; the shape of the blind groove depends on the shape of the protrusion on the longitudinal member or the transverse rib.

[0090] Preferably, each pushing mechanism includes a pushing block and a mounting seat, the pushing block includes a push rod and an end pressure portion which are connected to each other, the mounting seat is fixed on the base plate, the push rod is fixed in the mounting seat by a rotating connection, and the end pressure portion can be driven to abut against the side wall of the longitudinal member or the transverse rib by rotating the push rod to control the relative position of the parts to be welded in the wing frame and the thermal deformation during welding.

[0091] Preferably, the push rod and the mounting seat are rotatably connected via threads; for example, see Figure 2 and Figure 3 (c) The push mechanism 22c cooperates with the threads of the inner hole of the mounting seat through the threads on the outer surface of the push rod.

[0092] The tooling fixture for the wing frame and skin includes: a base plate, a frame side pressing mechanism and a skin pressing mechanism arranged on the base plate;

[0093] Preferably, each frame side pressure mechanism includes a pressing plate, one end of which can be pressed on the surface of the outermost longitudinal member or transverse member of the wing frame, and the other end is fixed on the base plate; thereby controlling the relative position and thermal deformation of the wing frame and the fixture; see Figure 5 The frame side pressing mechanism 42 is used to fix and press the wing frame onto the base plate.

[0094] Preferably, each skin clamping mechanism includes a clamping strip, on which a groove is provided that can accommodate the contact surface between the longitudinal member or transverse member inside the wing frame and the skin and that passes through the upper and lower surfaces of the clamping strip; the skin clamping mechanism is used to fix and clamp the wing frame together with the upper skin and / or lower skin covering the surface of the wing frame on the base plate along the first direction and / or the second direction. The skin clamping mechanism can control the relative position of the wing frame and the upper and lower skins on the base plate, and at the same time, for such long weld penetration welding, the skin clamping mechanism is arranged along the weld between the wing frame and the upper and lower skins, which can effectively control and reduce the thermal deformation of the wing frame and the skin during welding.

[0095] As an optional embodiment, the clamping strip is fixed to the base plate by a threaded connection; exemplarily, a plurality of holes are provided at the end of the clamping strip and / or along both sides of the groove for screws or bolts to pass through and be screwed into the base plate and / or the skin.

[0096] Preferably, the tooling fixture used for welding the wing frame and the wing frame and the skin also includes a rotating mechanism coaxially arranged on both sides of the base plate; the two rotating mechanisms are connected to the welding workbench, and by rotating the tooling fixture, different angles of the wing frame and the skin can be welded conveniently, thereby improving the accessibility of the welding gun.

[0097] Preferably, the two rotating mechanisms ( Figure 2The first rotating mechanism 23a and the second rotating mechanism 23b, Figure 5 The first clamp rotating mechanism 43a and the second clamp rotating mechanism 43b) are coaxially arranged on both sides of the substrate and the rotation axis is perpendicular to the first direction; more preferably, the two rotating structures are coaxially arranged at the middle position of both sides of the substrate and the rotation axis is perpendicular to the first direction.

[0098] Step S2, assembling the parts of the wing frame to be welded on the base plate, and controlling the relative position and welding deformation of each part through a reasonably designed positioning mechanism, a clamping mechanism, a side pressure mechanism, and a pushing mechanism; specifically comprising the following steps:

[0099] S21: Coordinate the first longitudinal member with the positioning mechanism to position the first longitudinal member; respectively set a side pressure mechanism at the 1 / 5 to 2 / 5 and 3 / 5 to 4 / 5 sections of the first longitudinal member between any two adjacent joints (based on any one of the two adjacent joints), and set a clamping mechanism at the 2 / 5 to 3 / 5 section;

[0100] In a possible design, W lugs included in the first longitudinal member are matched with W positioning pins on the substrate and positioned to define a position of the first longitudinal member relative to the substrate along the first direction; W≥2.

[0101] Preferably, a side pressure mechanism is provided at 1 / 4 and 3 / 4 of the first longitudinal member between any two adjacent joints (based on any one of the two adjacent joints), and a clamping mechanism is provided at 1 / 2.

[0102] S22: assemble N transverse ribs on the base plate in sequence from one end to the other end of the first longitudinal member, and set two side pressure mechanisms at a 1 / 3 to 2 / 3 section of each transverse rib (based on any one end of each transverse rib);

[0103] Preferably, a side pressure mechanism is provided at 1 / 3 and 2 / 3 of each transverse rib (based on any one of the two ends of each transverse rib).

[0104] S23: assembling the second longitudinal member on the base plate, and providing a side pressure mechanism at a 1 / 5 to 4 / 5 section of the second longitudinal member between any two adjacent joints (based on any one of the two adjacent joints);

[0105] Specifically, the second longitudinal member is placed on the base plate and abutted against the ends of the N transverse ribs in S22, and a side pressure mechanism is provided in a 1 / 5 to 4 / 5 section of the second longitudinal member between any two adjacent joints;

[0106] In a possible design, a side pressure mechanism is provided in a 2 / 5 to 3 / 5 section of the second longitudinal member between any two adjacent joints (based on any one of the two adjacent joints);

[0107] In a possible design, a side pressure mechanism is respectively provided in the 1 / 5 to 2 / 5 and 3 / 5 to 4 / 5 sections of the second longitudinal member located between any two adjacent joints (with any one of the two adjacent joints as a reference).

[0108] Repeat S22 and S23 alternately to assemble the remaining M-3 longitudinal members and N×(M-2) transverse bars;

[0109] Specifically, the third longitudinal member is assembled according to S23, and N transverse bars between the third longitudinal member and the fourth longitudinal member are assembled according to S22...; the M-1th longitudinal member is assembled according to S23, and N transverse bars between the M-1th longitudinal member and the Mth longitudinal member are assembled according to S22.

[0110] S24: Assemble the Mth longitudinal member on the base plate, respectively set a side pressure mechanism at the 1 / 5 to 2 / 5 and 3 / 5 to 4 / 5 sections of the Mth longitudinal member between any two adjacent joints (based on any one of the two adjacent joints), set a clamping mechanism at the 2 / 5 to 3 / 5 section, and set a push mechanism at the outside of the Mth longitudinal member and directly opposite to each joint;

[0111] More preferably, a side pressure mechanism is provided at 1 / 4 and 3 / 4 of the Mth longitudinal member between any two adjacent joints (based on any one of the two adjacent joints), and a clamping mechanism is provided at 1 / 2.

[0112] See also Figure 2 A push mechanism 22c is arranged on the outside of the Mth longitudinal member and directly opposite to each joint.

[0113] In S2, each pressing mechanism includes a pressing strip, and the two ends of the pressing strip are respectively placed on both sides of the first longitudinal member or the Mth longitudinal member to press and fix the first longitudinal member or the Mth longitudinal member on the substrate;

[0114] Each side pressure mechanism includes a pressing piece, one end of which is pressed on the surface of any longitudinal member or transverse rib, and the other end is fixed on the base plate, so as to press and fix the longitudinal member or transverse rib on the base plate;

[0115] Each pushing mechanism includes a pushing block and a mounting seat, the pushing block includes a push rod and an end pressure portion connected to each other, the mounting seat is fixed on the base plate, the push rod is fixed in the mounting seat by a rotating connection, and the end pressure portion is driven to abut against the side wall of the Mth longitudinal member by rotating the push rod.

[0116] Step S3: after assembly, perform chord plane measurement;

[0117] S31: Select a suitable chord plane measurement device;

[0118] Preferably, the chord plane measuring device includes at least one of a laser scanner and a laser tracker.

[0119] S32: Use the chord plane measurement device to scan along the chord length direction of the wing frame and record the data points.

[0120] S33: Input the collected data into computer-aided design (CAD) software, perform data analysis, and generate a chord plane three-dimensional model of the wing frame before welding.

[0121] Step S4, using laser welding, in accordance with the welding sequence: welding 2×N×(M-1) joints of the wing skeleton in sequence from one end to the other end along the first direction and from one side to the other side along the second direction to control welding deformation; specifically comprising the following steps:

[0122] Step S41: using inert gas to protect the front and back of the weld;

[0123] Specifically, a fixture equipped with wing skeleton parts to be welded is placed on a laser welding platform and fixed, and an inert gas is used to protect the front and back sides of the weld. In a possible design, the fixture is assembled and fixed to the laser welding platform through rotating mechanisms on both sides. Among them, the front protection can adopt the drag hood protection method in the prior art (nozzle + drag hood, inert gas is sprayed from the drag hood).

[0124] Preferably, a sealing cover is constructed in situ on the back side of each weld using a flexible sealing material, and an inert gas inlet and outlet are provided on the sealing cover to protect the back side of the weld.

[0125] In one possible design, a sealing tape is bonded to the longitudinal member and / or transverse rib near the back of each weld to form a sealing cover, and holes are opened in the sealing cover to form an inlet and outlet for the inert gas. This method has easy-to-obtain materials, simple operation, good back gas protection effect, and the tape can be quickly removed after welding.

[0126] Furthermore, the positions of the gas inlet and outlet are designed according to the specific gravity of the selected inert gas and air; preferably, the inert gas is argon, the gas inlet is located at the lower part of the sealing cover, and the gas outlet is located at the upper part of the sealing cover; argon is heavier than air, and it is easy to obtain a higher concentration by filling argon from a lower position, and the argon filling protection effect is better.

[0127] Step S42: performing tack welding on all welding joints while the weld is protected on the front and back by inert gas;

[0128] Preferably, the welding joint is in the form of a butt joint; the M longitudinal members include 2×N×(M-1) connecting ends along the second direction, which can be butted one by one with the two end faces of the N×(M-1) transverse reinforcements to form 2×N×(M-1) butt joints; the butt joint has high strength and a small weld, which can reduce welding heat input, thereby reducing welding thermal deformation.

[0129] Specifically, first find the welding trajectory, that is, ensure that the laser spot is located in the middle of the weld; then perform positioning welding on all welding joints of the wing frame.

[0130] Preferably, the middle part of the welding joint is selected for tack welding; since the length of the welding joints of the longitudinal members and transverse ribs of the wing frame is short, selecting the middle part of the joint for tack welding can effectively ensure uniform heat input and reduce welding deformation and stress concentration.

[0131] The length of the tack weld can be determined according to the length of the weld joint; preferably, the length of the tack weld is 1 / 5 to 1 / 3 of the length of the weld joint; for example, the length of the weld joint is 30 mm and the tack weld length is 10 mm. If the tack weld is too long, it may cause overheating and excessive melting of the weld area, while if the length is insufficient, it may cause the weld joint to be loose.

[0132] Optionally, the process parameters of positioning welding are: laser power of 700W to 900W, defocus of -1.0mm to -3.0mm, and welding speed of 0.5m / min to 2.5m / min; preferably, the process parameters of positioning welding are: laser power of 750W to 850W, defocus of -1.5mm to -2.5mm, and welding speed of 1.0m / min to 2.0m / min; exemplarily, the laser power is 800W, the defocus is -2mm, and the welding speed is 1.5m / min.

[0133] Step S43: Perform formal welding on all welding joints under the condition that the inert gas is used to protect the front and back of the weld;

[0134] Preferably, according to the welding sequence: 2×N×(M-1) joints of the wing frame are welded in sequence from one end to the other end along the first direction and from one side to the other side along the second direction to control welding deformation;

[0135] The above welding sequence allows the weld to shrink more freely, reducing the accumulation of welding stress, thereby minimizing the welding deformation that may be caused by the residual stress generated during the laser welding process; at the same time, it facilitates the welding operation and effectively ensures the straightness of the welding joints located in the same straight line.

[0136] For example, see Figure 1 , the eight welding joints are welded in sequence (①-⑧). That is, from top to bottom, along the second cross beam (including the second cross rib 15 and the first cross rib 14) from left to right, first weld the butt joint ① between the second cross rib 15 and the third main beam 13, and the butt joint ② between the second cross rib 15 and the second main beam 12 in sequence; then weld the butt joint ③ between the first cross rib 14 and the second main beam 12, and the butt joint ④ between the first cross rib 14 and the first main beam 11 in sequence; then, along the third cross beam (including the fourth cross rib 17 and the third cross rib 16) from left to right, first weld the butt joint ⑤ between the fourth cross rib 17 and the third main beam 13, and the butt joint ⑥ between the fourth cross rib 17 and the second main beam 12 in sequence; then weld the butt joint ⑦ between the third cross rib 16 and the second main beam 12, and the butt joint ⑧ between the third cross rib 16 and the first main beam 11 in sequence.

[0137] If ① and ④ are welded first, ② and ③ may not be able to be connected in a straight line due to different directions of thermal deformation.

[0138] Preferably, the welding sequence of step S43 is the same as that of step S42. By following a consistent welding sequence for positioning welding and formal welding, it is helpful to better control the heat input and heat distribution during the welding process, thereby reducing welding deformation.

[0139] Preferably, the arc starting and arc extinguishing distances during formal welding are 3mm to 7mm; more preferably, the arc starting and arc extinguishing distances are 5mm; on the one hand, if the arc starting and arc extinguishing distances are too short, the distance between the laser welding gun nozzle and the workpiece surface will be reduced, and the heat of the laser will be transferred to the workpiece more concentratedly, which will cause overheating in local areas and increase the risk of welding deformation; on the other hand, if the arc starting and arc extinguishing distances are too short, the stability of the laser may be reduced and the laser swing may increase, which will cause uneven weld formation and increase the risk of welding deformation.

[0140] Optionally, the process parameters of formal welding are: laser power of 1700W to 2100W, defocus of -3.5mm to -6.5mm, and welding speed of 0.5m / min to 2.5m / min; preferably, the process parameters of formal welding are: laser power of 1850W to 1950W, defocus of -4.5mm to -5.5mm, and welding speed of 1.0m / min to 2.0m / min. Exemplarily, the laser power is 1900W, the defocus is -5mm, and the welding speed is 1.5m / min.

[0141] As an optional implementation, step S4 may adopt the following welding sequence: first weld the front weld of each joint of the wing frame; then flip the fixture through the rotating mechanism to weld the back weld of each joint; then adjust the fixture through the rotating mechanism to weld the side weld of each joint to reduce welding deformation.

[0142] In one possible design, for areas that are difficult to reach or observe during the welding process, that is, processing dead corners, nonlinear programming or flexible welding equipment, such as welding robots, can be used to adjust the welding gun angle according to actual conditions to ensure the accessibility of the welding gun.

[0143] Step S5: measuring the chord plane of the welded wing frame and calibrating the shape.

[0144] The chord plane measurement device and steps mentioned in S3 above are used to measure the chord plane of the wing skeleton.

[0145] The chord plane measurement results of S5 and S3 are compared to obtain the deformation point position and deformation amount, and the wing frame is calibrated to further eliminate the slight deformation during laser welding and ensure dimensional accuracy.

[0146] Optionally, the shaping method includes one or a combination of mechanical shaping, thermal shaping, cold shaping, and CNC shaping. Among them, mechanical shaping includes but is not limited to manual shaping, pressure shaping, and stretching shaping; thermal shaping includes but is not limited to local heating and overall heating; cold shaping includes but is not limited to cooling shrinkage and cold stretching; CNC shaping includes but is not limited to CNC shaping and robot shaping.

[0147] Step S6, assembling the wing frame and skin to be welded on the fixture of the wing frame and skin, and controlling the relative position and welding deformation of the wing frame and skin through the frame side pressure mechanism and the skin pressing mechanism; specifically comprising the following steps:

[0148] S61: Assemble the wing frame on the base plate, and respectively set a frame side pressure mechanism at the 1 / 5 to 2 / 5 and 3 / 5 to 4 / 5 sections of the first longitudinal member and the Mth longitudinal member of the wing frame located between any two adjacent joints (based on any one of the two adjacent joints);

[0149] S62: Cover the upper skin and the lower skin on the front and back sides of the wing frame, and set 2×(M+N-4) skin clamping mechanisms on the outside of the upper skin and the lower skin and along the contact parts of the M-2 longitudinal members and N-2 transverse members in the wing frame with the upper skin and the lower skin.

[0150] In one possible design, each skin clamping mechanism includes a clamping strip, on which is formed a groove having a size sufficient to accommodate the contact surface between the corresponding longitudinal members or transverse members inside the wing frame and the skin and which passes through the upper and lower surfaces of the clamping strip. The clamping strip is used to fix and clamp the wing frame together with the upper skin and / or lower skin covering the surface of the wing frame onto the base plate along the first direction and / or the second direction.

[0151] Step S7, measuring the chord plane of the assembled wing frame and skin;

[0152] The chord plane measurement device and steps mentioned in S3 above are used to measure the chord plane of the wing frame and skin.

[0153] Step S8: using laser welding to obtain a combination of the wing frame and the upper and lower skins; specifically including the following welding sequence to control welding deformation:

[0154] S81: weld the contact parts of the second transverse member, the third transverse member, ... the N-1th transverse member and the skin in sequence from one end to the other end along the first direction; for each transverse member, weld in the same direction from one side to the other side along the second direction;

[0155] S82: weld the second longitudinal member, the M-1 longitudinal member, the third longitudinal member, the M-2 longitudinal member, etc. in sequence from both sides to the middle along the second direction to the contact portion between the 1 / 2*M longitudinal member or the 1 / 2*(M+1) longitudinal member and the skin, and for each of the longitudinal members, weld symmetrically from both ends to the middle along the first direction;

[0156] S83: performing bottom locking welding on the contact portions of the first longitudinal member, the Mth longitudinal member, the first transverse member and the Nth transverse member on the outer side of the wing frame and the skin;

[0157] Preferably, the first longitudinal member and the Mth longitudinal member are welded first, and then the first transverse member and the Nth transverse member are welded. The longitudinal member with greater rigidity is welded first, and then the transverse member with less rigidity is welded, so as to ensure the stability and accuracy of the overall structure.

[0158] Preferably, in S8, an inert gas is used to provide front and back protection for the weld; wherein, by means of a closed and connected air path environment formed by the wing frame and the upper and lower skins with ventilation holes, the inert gas enters from one end of the wing frame and is discharged from the other end of the wing frame, thereby providing back protection for the weld.

[0159] In S8, the front protection can adopt the drag hood protection method in the prior art (nozzle + drag hood, inert gas is sprayed out from the drag hood).

[0160] Preferably, the following process parameters are adopted:

[0161] In S81 and S82, the laser power is 2000W to 2200W, the defocus is -4mm to -6mm, and the welding speed is 0.02m / min to 0.03m / min; illustratively, the laser power is 2100W, the defocus is -5mm, and the welding speed is 0.025m / min;

[0162] In S83, the lock bottom welding includes positioning welding and formal welding;

[0163] Positioning welding: laser power is 700W~900W, defocus is -1.0mm~-3.0mm, and welding speed is 0.5m / min~2.5m / min; preferably, laser power is 750W~850W, defocus is -1.5mm~-2.5mm, and welding speed is 1.0m / min~2.0m / min; exemplarily, laser power is 800W, defocus is -2mm, and welding speed is 1.5m / min.

[0164] The length of the tack weld is 5 mm to 15 mm, and the weld spacing is 25 mm to 35 mm; for example, the length of the tack weld is 10 mm, and the weld spacing is 30 mm;

[0165] Formal welding: laser power is 900W~1100W, defocus is -3mm~-7mm, and welding speed is 0.5m / min~2.5m / min; preferably, the process parameters of formal welding are: laser power is 950W~1050W, defocus is -4mm~-6mm, and welding speed is 1.0m / min~2.0m / min; exemplarily, the laser power is 1000W, the defocus is -5mm, and the welding speed is 1.5m / min.

[0166] Preferably, in S4 and S8, the gas flow rate for front protection is 20L / min to 40L / min, and the gas flow rate for back protection is 4L / min to 6L / min; more preferably, the gas flow rate for front protection is 20L / min to 30L / min; illustratively, the gas flow rate for the front protection hood is 25L / min; and the gas flow rate for back protection is 5L / min.

[0167] Preferably, in S4 and S8, after welding is completed, the inert gas protection is stopped after cooling for 15 minutes to 20 minutes; after welding is completed, gas protection (mainly back gas protection) can protect the weld metal from erosion by harmful gases in the air during the cooling process, maintaining the purity and performance of the weld metal.

[0168] It is worth noting that in S4 and S8, the use of the above-mentioned preferred welding parameters and inert gas flow rate has a positive effect on reducing welding deformation;

[0169] Regarding welding parameters, (a) when the laser power is too large, the heat affected zone of the welding area will increase, resulting in more heat input into the material, increasing the risk of welding deformation; too small a laser power may lead to insufficient welding and decreased weld performance; (b) when the defocus is too large, the energy of the laser beam may not be concentrated in the welding area, resulting in uneven heat input; this uneven heat distribution may cause an increase in the temperature gradient in the welding area and its surrounding areas and generate greater thermal stress, thereby increasing the risk of welding deformation; and too small a defocus may affect the welding quality and efficiency; (c) welding speed: too slow a welding speed will lead to excessive heat input in the welding area, which may cause excessive thermal effects and increase the risk of welding deformation; too fast a welding speed may lead to insufficient heat input per unit area, which may prevent the weld from being fully melted, affecting the formation of the weld and the welding quality.

[0170] Regarding the inert gas flow rate, (a) when the gas flow rate is too large, the cooling effect of the gas on the molten pool will be enhanced. This enhanced cooling effect may cause the molten pool temperature to be too low, making the fluidity of the welding material worse and increasing the risk of welding deformation; excessive gas flow may cause the shielding gas flow to be turbulent, destroying the protective effect. In this case, the molten pool may be invaded by oxygen, nitrogen, etc. in the air, increasing the risk of welding defects such as porosity, and indirectly affecting welding deformation; (b) when the gas flow rate is too small, the gas in the molten pool may not be able to completely overflow, and holes will be formed on the surface or inside of the weld after the molten pool solidifies. These porosity defects cause local stress concentration in the welded structure and increase the risk of deformation; when the gas flow rate is too small, the stiffness of the shielding gas is insufficient, which may cause the molten pool to be invaded by oxygen, nitrogen, etc. in the air, increasing the risk of welding defects such as porosity, and indirectly affecting welding deformation.

[0171] Step S9: measure the chord plane of the assembly and calibrate the shape.

[0172] The chord plane measurement device and steps mentioned in S3 above are used to measure the chord plane of the assembly.

[0173] The chord plane measurement results of S9 and S7 are compared to obtain the deformation point position and deformation amount, and the combination of the wing frame and skin is calibrated to further eliminate the slight deformation during the laser welding process and ensure dimensional accuracy.

[0174] Preferably, in steps S2 and S6, the assembly includes: trial assembly, repair and trial assembly to meet the assembly tolerance requirements, and marking matching marks on each component; pickling to remove oxide scale and improve welding quality; formal assembly: after pickling, assemble each component in sequence according to the matching marks on each component, and clamp them with tooling fixtures to ensure that the assembly tolerance requirements are met.

[0175] Preferably, in steps S2 and S6, the assembly tolerance requirements include: the butt joint gap and step difference at each point of each joint are not greater than 0.1 mm, and the butt joint gap and step difference with a cumulative length of no more than 30 mm within any local 100 mm are not greater than 0.2 mm.

[0176] Preferably, before trial assembly, the area to be welded is pretreated until the metallic luster is exposed and the surface roughness of the surface to be welded is Ra≤3.2 μm.

[0177] Specifically, the pretreatment mainly includes processing the area to be welded by machining finishing; specifically, the surface to be welded is processed by mechanical processing method to ensure flatness, smoothness, burr-free, and maintain edges and corners. The surface roughness of the surface to be welded after processing is Ra≤3.2μm; the area to be welded is cleaned by mechanical processing method to remove surface oil, non-metallic impurities, etc. until the metallic luster is exposed; wherein, the area to be welded includes the surface to be welded and both sides of the weld; non-metallic impurities include oxides.

[0178] Optionally, the area to be welded includes 10 mm to 30 mm on both sides of the weld; preferably, 20 mm on both sides of the weld.

[0179] Optionally, the above-mentioned machining methods include but are not limited to milling, grinding, scraping, lapping, super finishing, and polishing.

[0180] Optionally, the mechanical treatment method includes mechanical grinding. Exemplarily, the tools for mechanical grinding include but are not limited to wire brushes, sandpaper, and files.

[0181] It can be understood that by pre-treating the area to be welded (including the surface to be welded), the quality and reliability of the welded joint can be ensured.

[0182] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments.

[0183] Embodiment 1:

[0184] This embodiment provides a method for preventing welding deformation of a TA15 titanium alloy wing frame and skin, comprising the following steps:

[0185] Step S1, designing a fixture for welding the wing frame and the wing frame and the skin;

[0186] See also Figure 1-Figure 5The wing skeleton 100 includes a first main beam 11, a second main beam 12, and a third main beam 13 distributed in parallel along a first direction, and a first cross beam (not shown in the figure), a second cross beam, a third cross beam, and a fourth cross beam (not shown in the figure) distributed in parallel along a second direction; wherein the second cross beam includes a first cross rib 14 and a second cross rib 15 distributed in a straight line, and the third cross beam includes a third cross rib 16 and a fourth cross rib 17 distributed in a straight line; the angle between the first direction and the second direction is 87°.

[0187] The main beam and transverse reinforcement are made of TA15 titanium alloy, and both are hollow structure rods with a wall thickness of 3mm and an I-shaped cross-section; the skin is made of TA15 titanium alloy with a wall thickness of 2mm.

[0188] The wing frame fixture 200 includes a base plate, a positioning mechanism, a clamping mechanism, a side pressure mechanism, a pushing mechanism, and two rotating mechanisms 23a and 23b symmetrically and coaxially distributed at the middle positions on both sides of the base plate.

[0189] The substrate is in the shape of a grid-shaped thin plate, and each grid includes a quadrilateral or cross-shaped hollow structure;

[0190] The positioning mechanism includes two positioning pins 21 located on the base plate;

[0191] Each clamping mechanism 22a includes a long clamping strip with inner holes at both ends for screws to pass through and be screwed into the base plate;

[0192] Each side pressure mechanism 22b includes a rectangular pressing piece, and the part of the pressing piece that does not contact the main beam or the transverse rib has two inner holes for screws to pass through and be screwed into the base plate;

[0193] Each push mechanism 22c includes a push block and a mounting seat. The push block includes a push rod and an end pressure portion connected to each other. The mounting seat is fixed on the base plate. The outer surface of the push rod is provided with a thread that matches the thread of the inner hole of the mounting seat. The end pressure portion is driven to abut against the side wall of the main beam by rotating the push rod.

[0194] The fixture 400 for the wing frame 100 and the skin 300 includes a base plate, a skin pressing mechanism, a frame side pressing mechanism, and two fixture rotating mechanisms 43a and 43b coaxially symmetrically distributed in the middle of both sides of the base plate.

[0195] Each skin pressing mechanism 41 comprises a long pressing strip, on which a strip groove is formed which is just large enough to accommodate the contact surface between the main beam or the cross beam and the skin;

[0196] Each frame side pressure mechanism 42 includes a rectangular pressing plate, and two inner holes are provided in the portion of the pressing plate that is not in contact with the wing frame for screws to pass through and be screwed into the base plate.

[0197] Step S2, assembling the parts of the wing frame to be welded on the base plate;

[0198] S21: The two lugs on the right side of the first main beam 11 are matched with the two positioning pins 21 on the base plate to position; a side pressure mechanism 22b is respectively provided at 1 / 4 and 3 / 4 between any two adjacent joints of the first main beam 11, and a clamping mechanism 22a is provided at 1 / 2;

[0199] S22: assemble four transverse ribs on the base plate in sequence from the upper end to the lower end of the first main beam 11, and set a side pressure mechanism 22b at 1 / 3 and 2 / 3 of each transverse rib respectively;

[0200] S23: assembling the second main beam 12 on the base plate, and providing two side pressure mechanisms 22b distributed face to face at a position 2 / 5 between any two adjacent joints of the second main beam 12;

[0201] Repeat S22 to sequentially assemble four transverse ribs between the second main beam 12 and the third main beam 13;

[0202] S24: Assemble the third main beam 13 on the base plate, and respectively set a side pressure mechanism 22b at 1 / 4 and 3 / 4 between any two adjacent joints of the third main beam 13, and set a clamping mechanism 22a at 1 / 2; set a push mechanism 22c on the outside of the third main beam 13 and facing each joint.

[0203] Step S3: After assembly, the wing skeleton is measured in the chord plane using a laser scanner; the collected data is input into Geomagic Control X software to generate a 3D model of the chord plane of the wing skeleton before welding.

[0204] Step S4: Use a laser welding device (device name: large-size three-dimensional multi-layer curved surface high-power high-precision laser welding equipment; manufacturer: Aerospace Sanjiang Laser) to weld 16 joints in sequence from top to bottom and from left to right. Figure 1 The 8 joints shown are welded in sequence (①-⑧);

[0205] During welding, argon gas is used to protect the weld. The front is protected by a drag hood + nozzle, and the back is bonded to the main beam and / or transverse reinforcement near the back of each weld with 3M tape to form a sealing cover. A hole is pierced at the bottom of the sealing cover to introduce argon gas, and a hole is pierced at the top to form an argon gas outlet.

[0206] Position welding: the laser power is 800W, the defocus is -2mm, and the welding speed is 1.5m / min; the middle of each joint is selected for positioning welding, and the positioning welding length is 10mm.

[0207] Formal welding: laser power is 1900W, defocus is -5mm, welding speed is 1.5m / min; arc starting and arc extinguishing distance is 5mm.

[0208] Step S5: measuring the chord plane of the welded wing frame and calibrating the shape.

[0209] According to the above S3, the wing skeleton is measured in the chord plane, and the position of the deformation point and the deformation amount are obtained by comparison. Cold shaping is performed by hot shaping and tapping with tools such as rubber wood hammers to correct the remaining slight deformation.

[0210] Step S6, assembling the wing frame and skin to be welded on the fixture of the wing frame and skin;

[0211] S61: assembling the wing frame obtained in step S5 on the base plate, and respectively setting a frame side pressure mechanism 42 at the 1 / 4 position and the 3 / 4 position between any two adjacent joints of the first main beam 11 and the third main beam 13 of the wing frame;

[0212] S62: Cover the upper skin and the lower skin on the front and back sides of the wing frame, and set 6 skin clamping mechanisms 41 at the contact parts between the second main beam 12, the second cross beam and the third cross beam inside the wing frame and the upper skin and the lower skin.

[0213] Step S7, according to S3, measuring the chord plane of the assembled wing frame and skin;

[0214] Step S8, laser welding is performed according to the following welding sequence to obtain a combination of the wing frame and the upper and lower skins;

[0215] S81 and S82: According to Figure 4 As shown in the sequence ①-⑤, penetration welding is performed on the contact parts between the third cross beam, the second cross beam, the second main beam 12 and the upper skin and the lower skin;

[0216] S83: According to Figure 4 As shown in ⑥-⑦, the third main beam 13 and the first main beam 11 are welded in sequence, and then the upper first cross beam, the lower fourth cross beam (not shown in the figure) and the joints around the upper skin and the lower skin are welded.

[0217] During welding, argon is used to protect the front and back of the weld. The front is protected by a drag hood + nozzle, and the back is protected by a wing frame with reserved vents 18 and upper and lower skins to form a relatively closed and connected gas path environment. Argon enters from the fourth beam at the bottom of the wing frame and is discharged from the first beam at the top of the wing frame to protect the back of the weld.

[0218] In S81 and S82, the laser power was 2100 W, the defocus was -5 mm, and the welding speed was 0.025 m / min;

[0219] In S83, positioning welding: laser power is 800W, defocus is -2mm, welding speed is 1.5m / min, positioning welding length is 10mm, and weld spacing is 30mm; formal welding: laser power is 1000W, defocus is -5mm, welding speed is 1.5m / min. The arc starting and arc extinguishing distance is 5mm.

[0220] In S4 and S8, the gas flow rate of the hood for front protection is 25L / min; the gas flow rate for back protection is 5L / min.

[0221] Step S9: According to S5, the chord plane of the assembly is measured and the shape is corrected.

[0222] Implementation results:

[0223] 1. The results of chord plane measurement show that the welding deformation of the wing frame, wing frame and skin assembly can be controlled below ±0.5%. Figure 6 As shown; this shows that the method provided by the present invention can significantly reduce welding deformation, thereby reducing residual stress and cracking problems, and improving welding quality; and because the welding deformation is very small, little or no correction is required to meet the standard requirements, thereby achieving cost reduction and efficiency improvement.

[0224] 2. Visual inspection or inspection with a magnifying glass of 10 times or less shall be conducted on the weld appearance quality. The results shall show that the weld surface of the wing frame and the combination of the wing frame and the skin obtained by welding shall be free of defects such as oxidation, inclusions, pores, cracks, lack of fusion, undercut, depression, etc. Figure 7 As shown;

[0225] 3. X-ray nondestructive testing shows that the weld quality of the wing frame, wing frame and skin assembly fully meets the requirements of Grade I welds in QJ20465-2016 (Technical requirements for laser welding of titanium and titanium alloys). Figure 8 As shown;

[0226] 4. Take room temperature tensile specimens from the welds and test the mechanical properties of the joints at room temperature. The results show that the room temperature tensile strength of the welds of the wing frame, wing frame and skin combination obtained by welding can reach more than 95% of the base material; for example, Figure 1 The tensile strength of the four joints ①-④ is 900Mpa~912Mpa, and the tensile strength of the base material is about 930Mpa.

[0227] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preventing welding deformation of a wing frame and a skin, characterized in that: The following steps are involved: S1. Design of fixtures for welding wing frames and wing frames and skins; The wing skeleton comprises: M longitudinal members distributed in parallel along a first direction and N transverse members distributed in parallel along a second direction, each transverse member comprises M-1 transverse ribs, the M longitudinal members and N×(M-1) transverse ribs are connected by 2×N×(M-1) joints to form a grid structure, M≥3, N≥3; the first direction is different from the second direction; The fixture of the wing frame includes: a base plate, a positioning mechanism and a clamping mechanism arranged on the base plate; the clamping mechanism includes three types: a pressing mechanism, a side pressure mechanism, and a pushing mechanism; S2. Assemble the parts of the wing frame to be welded on the base plate, and control the relative position and welding deformation of each part through a reasonably designed positioning mechanism, a clamping mechanism, a side pressure mechanism, and a pushing mechanism; specifically, the following steps are included: S21: Coordinate the first longitudinal member with the positioning mechanism to position the first longitudinal member; respectively set a side pressure mechanism in the 1 / 5 to 2 / 5 and 3 / 5 to 4 / 5 sections between any two adjacent joints of the first longitudinal member, and set a clamping mechanism in the 2 / 5 to 3 / 5 section; S22: assembling N transverse ribs on the base plate in sequence from one end to the other end of the first longitudinal member, and setting two side pressure mechanisms in the 1 / 3 to 2 / 3 section of each transverse rib; S23: assembling the second longitudinal member on the base plate, and providing a side pressure mechanism at a 1 / 5 to 4 / 5 section of the second longitudinal member between any two adjacent joints; Repeat S22 and S23 alternately to assemble the remaining M-3 longitudinal members and N×(M-2) transverse bars; S24: assembling the Mth longitudinal member on the base plate, respectively providing a side pressure mechanism at the 1 / 5 to 2 / 5 and 3 / 5 to 4 / 5 sections of the Mth longitudinal member between any two adjacent joints, providing a clamping mechanism at the 2 / 5 to 3 / 5 section, and providing a push mechanism at the outside of the Mth longitudinal member and directly facing each joint; S3. After assembly, measure the chord plane; S4. Using laser welding, 2×N×(M-1) joints of the wing frame are welded in sequence: from one end to the other end along the first direction and from one side to the other side along the second direction to control welding deformation; S5. Measure the chord plane of the welded wing frame and adjust its shape.

2. The method for preventing welding deformation of a wing frame and a skin according to claim 1, characterized in that: Each of the clamping mechanisms includes a clamping strip, and the two ends of the clamping strip are respectively placed on both sides of the first longitudinal member or the Mth longitudinal member to clamp and fix the first longitudinal member or the Mth longitudinal member on the base plate.

3. The method for preventing welding deformation of a wing frame and a skin according to claim 1, characterized in that: Each of the side pressure mechanisms includes a pressing plate, one end of which is pressed on the surface of any longitudinal member or transverse rib, and the other end is fixed on the base plate, thereby pressing and fixing the longitudinal member or transverse rib on the base plate.

4. The method for preventing welding deformation of a wing frame and a skin according to claim 1, characterized in that: Each of the pushing mechanisms includes a pushing block and a mounting seat, and the pushing block includes a push rod and an end pressure portion connected to each other. The mounting seat is fixed on the base plate, and the push rod is fixed in the mounting seat by a rotating connection. The end pressure portion is driven to abut against the side wall of the Mth longitudinal member by rotating the push rod.

5. The method for preventing welding deformation of a wing frame and a skin according to claim 1, characterized in that: The positioning mechanism includes W positioning pins, and the W lugs included in the first longitudinal member are matched with the W positioning pins to limit the position of the first longitudinal member relative to the substrate along the first direction; W≥2.

6. The method for preventing welding deformation of a wing frame and a skin according to claim 1, characterized in that: Also includes: In S1, the fixture for the wing frame and skin includes: a base plate, a frame side pressing mechanism and a skin pressing mechanism arranged on the base plate; S6, assembling the wing frame and skin to be welded on the fixture of the wing frame and skin, and controlling the relative position and welding deformation of the wing frame and skin through the frame side pressure mechanism and the skin pressing mechanism; specifically comprising the following steps: S61: assembling the wing frame on the base plate, and respectively providing a frame side pressure mechanism at the 1 / 5 to 2 / 5 and 3 / 5 to 4 / 5 sections of the first longitudinal member and the Mth longitudinal member of the wing frame located between any two adjacent joints; S62: Cover the upper skin and the lower skin on the front and back surfaces of the wing frame, and set 2×(M+N-4) skin pressing mechanisms on the outer sides of the upper skin and the lower skin and along the contact portions of the M-2 longitudinal members and the N-2 transverse members in the wing frame with the upper skin and the lower skin; S7. Measure the chord plane of the assembled wing frame and skin; S8. A combination of the wing frame and the upper and lower skins is obtained by laser welding. Specifically, the welding sequence is as follows to control welding deformation: S81: weld the contact parts of the second transverse member, the third transverse member, ... the N-1th transverse member and the skin in sequence from one end to the other end along the first direction; for each transverse member, weld in the same direction from one side to the other side along the second direction; S82: weld the second longitudinal member, the M-1 longitudinal member, the third longitudinal member, the M-2 longitudinal member, etc. in sequence from both sides to the middle along the second direction to the contact portion between the 1 / 2*M longitudinal member or the 1 / 2*(M+1) longitudinal member and the skin, and for each of the longitudinal members, weld symmetrically from both ends to the middle along the first direction; S83: performing bottom locking welding on the contact portions of the first longitudinal member, the Mth longitudinal member, the first transverse member and the Nth transverse member on the outer side of the wing frame and the skin; S9. Measure the chord plane of the assembly and calibrate its shape.

7. The method for preventing welding deformation of a wing frame and a skin according to claim 6, characterized in that: Each of the skin clamping mechanisms includes a clamping strip, on which is a groove that can accommodate the contact surface between the longitudinal members or transverse members inside the wing frame and the skin and that passes through the upper and lower surfaces of the clamping strip. The clamping strip is moved along the first direction or the second direction to fix and press the wing frame together with the upper skin or lower skin covering the surface of the wing frame onto the base plate.

8. The method for preventing welding deformation of a wing frame and a skin according to claim 1 or 6, characterized in that: It also includes comparing the chord plane measurement results of S5 and S3, and comparing the chord plane measurement results of S9 and S7, to obtain the deformation point position and deformation amount, to calibrate the wing frame and assembly, to further eliminate minor deformations during laser welding, and to ensure dimensional accuracy.

9. The method for preventing welding deformation of a wing frame and a skin according to claim 1 or 6, characterized in that: The device for measuring the chord plane includes at least one of a laser scanner and a laser tracker; and / or, The shaping method includes one or a combination of mechanical shaping, thermal shaping, cold shaping, and CNC shaping.

10. The method for preventing welding deformation of a wing frame and a skin according to claim 1, characterized in that: The tooling fixture for welding the wing frame and the wing frame and the skin also includes a rotating mechanism coaxially arranged on both sides of the base plate; S4 also includes welding the front weld of each joint of the wing frame first; then flipping the fixture through the rotating mechanism to weld the back weld of each joint; and then adjusting the fixture through the rotating mechanism to weld the side weld of each joint to reduce welding deformation.

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