CN115555681A

CN115555681A - Pre-deformation connection method for thin-wall corner joint structure with different thicknesses

Info

Publication number: CN115555681A
Application number: CN202211306510.2A
Authority: CN
Inventors: 韩颖杰; 黄振宁; 付和国; 谢洪志; 李明; 赵兴旺
Original assignee: Shenyang Aircraft Industry Group Co Ltd
Current assignee: Shenyang Aircraft Industry Group Co Ltd
Priority date: 2022-10-25
Filing date: 2022-10-25
Publication date: 2023-01-03

Abstract

The invention relates to a predeformation connecting method of a thin-wall angle joint structure with different thicknesses, belonging to the technical field of metal material machining. By using the novel process technology, the invention realizes the connection and manufacture of the angle joint structures with different thicknesses, expands the application principle of the welding process, and applies the lower cost to more simply and efficiently process the L-shaped section thin-wall angle joint welding. By means of the universal welding fixture for the symmetrical parts and the design of the eccentric load prevention clamping mechanism, the technical requirements for processing typical bulkhead type parts are reduced, the technological parameter requirements, the equipment capacity requirements and the special tool structure requirements are reduced to different degrees, and finally, the deformation accumulation of the thin-wall angle joint structure after welding can be greatly reduced by means of the measures of the reversible deformation internal stress of the edge strip parts, so that the heat treatment correction is easier. The method has strong popularization characteristic, can be implemented for the thin-wall angle joint structure type bulkhead parts, has high production efficiency, and has wide application prospect in the aircraft manufacturing industry.

Description

Pre-deformation connection method for thin-wall corner joint structure with different thicknesses

Technical Field

The invention relates to a predeformation connecting method of a thin-wall angle joint structure with different thicknesses, belonging to the technical field of metal material machining.

Background

The most common airframe structure for modern aircraft is an all-metal semi-monocoque structure to provide high load carrying while at the same time providing a minimal weight penalty. For a type of secondary bearing structure of thin-wall sheet metal in an airplane, the secondary bearing structure is generally connected with a skin to form a T-shaped section, so that an angle joint structure is formed between two sides of a stud and the skin, the rigidity of a wall plate can be greatly improved, and the weight of the structure can be reduced.

The titanium alloy material is widely applied to manufacturing parts at the engine cabin part of the rear fuselage due to the characteristics of small density, high specific strength, corrosion resistance, good high-temperature performance and the like, and meanwhile, the welding performance is superior, and the T-shaped structure is reinforced by the stud in the skin, such as: the stringer, bulkhead, etc. components are preferably manufactured by welding. The bulkhead type part is mainly used for forming the transverse section shape of an airplane, a TC2M delta 0.8 plate is generally selected as a material, a sheet metal weak frame distributed between machine reinforcing frames is required by strength and rigidity, a thickening design delta 1.5 is adopted for the bent edge at the top end of a stud, and meanwhile, a high-strength titanium alloy TA15M is selected as the material.

As shown in figure 1, a web plate 1.1 is made of TC2M delta 0.8, a flange strip 1.2 is made of TA15M delta 1.5, and in order to achieve connection manufacturing of different thicknesses and different materials, a through argon arc welding process is selected as a manufacturing process, namely, the flange strip 1.2 is horizontally placed and vertically welded on the upper portion of the flange strip corresponding to the web plate 1.1, and fillet welds at two sides of a stud and a bottom plate can be formed simultaneously. In order to form an effective connection effect, the argon arc welding connection needs to be carried out by adopting larger current parameters under the influence of the thickness of the edge strip 1.2, so that a series of adverse effects are caused: firstly, the operation on the upper surface of the edge strip 1.2 has certain blindness, the control precision is lower, the simple method adopts the increased current parameter to carry out welding, and the web plate 1.1 is ensured to be effectively heated, melted and connected into a whole; secondly, because the edge strip 1.2 has radian change in a horizontal plane, the flow of molten pool materials is influenced by the execution speed of the tail end of a welding gun and gravity factors during welding, welding defects are easily generated due to uneven cooling, and further the radian change of the edge strip 1.2 is limited to a certain extent; under the combined action of the above adverse factors, although effective connection between the two is realized, the welding residual stress is large, the accumulated deformation of the structure is large, particularly, the deformation degree is aggravated due to the relatively large thickness of the edge strip 1.2, the size of the corner joint structure is difficult to correct, a useless side edge strip material needs to be removed after welding, and the total workload is complex.

As shown in fig. 1, the welding lines of the bulkhead with the common fillet structure are all arc-shaped, and the cooling shrinkage process of the welding lines after welding can generate arc shrinkage change, so that the arc radius of the flange strip 1.2 is reduced, the stress is eliminated in the subsequent vacuum heat treatment and reverse correction is forced, the deformation resistance is large, the one-time correction is difficult, the final size requirement needs to be gradually met for many times, and the period is long and the cost is high.

Disclosure of Invention

In order to overcome the technical problems, the invention provides a novel connecting method, which innovatively changes the welding angle of a fillet weld, changes the fillet weld on two sides of a T-shaped structure into the fillet weld on one side of an L-shaped joint, and horizontally places web parts to enable curve weld to be in the same horizontal plane, thereby greatly simplifying the operation difficulty of equipment, omitting the secondary edge strip removing process, having high overall production efficiency and simple and convenient operation and being suitable for mass production.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the method for pre-deforming and connecting the thin-wall angle joint structures with different thicknesses comprises the following steps:

the first step is as follows: as shown in fig. 1, the web plate part is manufactured according to a sample plate, the theoretical shape requirement is met after stamping or hydraulic bending forming, 1-2 mm of pre-welding repair allowance is reserved on one side of the edge to be welded, 10-20 mm of welding arc starting and arc ending allowance is reserved along two ends of a welding line, and a 2-phi 5.2 positioning hole is manufactured; unfolding the edge strip according to a digital model, cutting a flat plate material by laser, increasing the width of the part by 0.5-1 mm of welding shrinkage allowance, and reserving welding arc starting and arc stopping allowances of 10-20 mm along two ends of a welding line;

the second step: performing surface pickling treatment on the web plate and the edge strip, and wrapping and storing the web plate and the edge strip by kraft paper after the surface pickling treatment is finished;

the third step: as shown in fig. 4, the clamp is cancelled to press, the pressing strip is taken down, as shown in fig. 5, the web plate is positioned according to the positioning holes with the diameter of 2-phi 5.2 at the two ends, and is arranged on the base body by using positioning pins;

the fourth step: as shown in fig. 6, the edge strip is pressed into the middle of the pressing strip and the base body through pre-bending, a clamp screw is used for gradually screwing until the edge strip and the base body are tightly attached, the welding edge is repaired according to the state, the edge margin is removed by adopting a mechanical method, the operations of the steps 3 and 4 are repeated until the repair is completed, the repair gap before welding is ensured not to be more than 0.2 mm, and batch operation is completed according to the method;

the fifth step: taking the web plate and the edge strip off the fixture, polishing the areas to be welded of the web plate and the edge strip by a mechanical method, polishing the metal luster, and finishing batch operation according to the method;

and a sixth step: cleaning a part web plate, a part edge strip, a clamp copper plate, a clamp pressing strip and a clamp pressing plate by using an organic solvent, and finishing batch operation according to the method;

the seventh step: as shown in fig. 7, the web plate and the edge strip are remounted after cleaning, the nozzle is connected with an argon hose of the equipment, protective gas is introduced, the web plate and the edge strip are pre-connected through manual argon arc welding positioning welding, the distance between welding points is about 50-100 mm, the welded parts are disassembled after finishing, and batch operation is finished according to the method;

the eighth step: as shown in fig. 7, the web and the bead after the tack welding are clamped again, the pressing plate is pressed tightly, the nozzle is connected with an argon hose of the equipment, protective gas is introduced, the clamped special welding fixture is placed into the equipment, the pressing plate is pressed tightly by using a pneumatic pressing device, the fixing of the parts before welding is completed, and the welding conditions are met;

the ninth step: carrying out welding manufacture according to the optimized technological parameters, wherein the welding parameters are as follows: current is 70-85A, voltage is 9-10V, speed is 0.1-0.2 m/min, protective argon is 8-20L/min, after the completion, the special welding fixture is taken out of the equipment, the welded bulkhead part is dismounted, steps 6 and 7 are repeated, and the operation is circulated until the whole batch of part manufacturing is completed;

the tenth step: the clamp is removed and installed on the reverse side, and then welding batch processing of the symmetric partition frames can be carried out;

the eleventh step: after the welding of the partition frame is finished, carrying out vacuum heat treatment to remove welding stress, and correcting welding deformation by using a special welding fixture;

the twelfth step: and (4) after the heat treatment is finished, acid washing is carried out to clean surface oxidation color, and finally the connection manufacturing of the thin-wall corner joint structure with different thicknesses is finished.

The invention has the beneficial effects that:

by using the novel process technology, the invention realizes the connection and manufacture of the angle joint structures with different thicknesses, expands the application principle of the welding process, and applies the lower cost to more simply and efficiently process the L-shaped section thin-wall angle joint welding. By means of the symmetrical piece universal welding fixture and the design of the unbalance loading prevention clamping mechanism, the technical requirements of typical bulkhead type part machining are reduced, the technological parameter requirements, the equipment capacity requirements and the special tool structure requirements are reduced to different degrees, and the deformation accumulation after welding of the thin-wall angle joint structure can be greatly reduced by utilizing the measures of the anti-deformation internal stress of the edge strip part, so that the heat treatment correction is easier. The method has strong popularization characteristics, can be implemented for thin-wall angle joint structure type bulkhead parts, has high production efficiency, and has wide application prospect in the aircraft manufacturing industry.

Drawings

FIG. 1 is a view of a typical corner-joint structure bulkhead of different thicknesses;

FIG. 2 is a schematic view of a welding direction selection of the corner joint structure;

FIG. 3 is a schematic view of a reversible welding fixture;

FIG. 4 is a schematic view showing a state where the jig is disassembled before welding;

FIG. 5 is a schematic view of the assembly of a web part on a jig;

FIG. 6 is a schematic view of the pre-clamping condition of the bead prior to welding;

FIG. 7 is a schematic view showing the web compression and bead clamping state before welding;

FIG. 8 is a top view of a special welding fixture;

FIG. 9 isbase:Sub>A cross-sectional view of the clamp A-A;

FIG. 10 is a cross-sectional view of the clamp B-B.

In the figure: 1.1 a web; 1.2 edge strips; 3.1 a substrate; 3.2 copper plate; 3.3 layering; 3.4 a clamper; 3.5 positioning pins; 3.6 nozzle.

Detailed Description

The following describes the implementation process of the present invention in detail with reference to the technical solutions and the accompanying drawings.

Example 1:

the method for pre-deforming and connecting the thin-wall corner joint structure with different thicknesses comprises the following steps:

the first step is as follows: as shown in fig. 2, the web 1.1 is placed horizontally, the edge strip 1.2 is placed perpendicular to the ground, the welding direction of the equipment is unchanged, but the original welding of the vertical edge strip 1.2 is changed into the end face welding of the vertical edge strip 1.2, and meanwhile, a single-side fillet weld connection is finally formed by melting part of the web 1.1;

the second step is that: because the relative welding direction is changed, the end surface of the edge strip 1.2 and the web plate 1.1 form an open structure, the edge strip 1.2 does not need to be completely welded, the welding current parameter can be reduced, a small part of the material of the edge strip 1.2 is directly melted, the angle joint structure connection is realized, and the welding deformation accumulation is favorably reduced;

designing a special welding fixture, as shown in fig. 3, the special welding fixture comprises a base body 3.1 and a copper plate 3.2, wherein the base body 3.1 and the copper plate 3.2 are assembled in a sleeved mode and fixedly connected through screws, so that a sealing effect is achieved, a pressing strip 3.3 forms clamping fit with the copper plate 3.2 through a clamp 3.4, the outer surface of the pressing strip is in sliding fit with the clamp screws, and a positioning pin 3.5 is in shaft fit with an upper hole of the base body 3.1; the nozzle 3.6 is vertically matched with the base body 3.1 in a threaded manner;

the assembly space position of the bulkhead assembly before welding is changed, the height difference of a welding seam path in a three-dimensional space is greatly reduced, welding in a pure horizontal plane is changed, the technical capability requirements on accessibility of a three-dimensional space of processing equipment, automation complexity and the like are obviously reduced, welding manufacturing can be carried out by using two-dimensional automation/semi-automation equipment in the plane, the structural requirements on a special welding fixture tool are also greatly reduced, and batch processing and manufacturing are easier to realize;

because the space path of the fillet weld is in the same horizontal plane, the special welding fixture can be designed into a flat plate small-thickness structure, as shown in fig. 3, a web plate 1.1 is fixed with a base body 3.1 through positioning holes at two ends by using positioning pins 3.5, the surface to be welded is on the inner side of an arc, a flange 1.2 is placed in a vertical plane, the thickness of the fixture base body is slightly larger than the maximum width of the flange, the upper edge and the lower edge of a copper plate 3.2 and a pressing strip 3.3, which are close to the weld joint, are in the same chamfer state, the matching holes of the base body 3.1 and a clamp 3.4 are designed into double-sided characteristics, namely, the common processing of left and right symmetrical parts of a bulkhead can be realized, one part can be welded on the upper surface, and the clamp 3.4 can be welded into another symmetrical part after being overturned to form a universal fixture for the left and right parts;

in order to realize smaller welding deformation effect, the edge strip 1.2 is not shaped, manufactured according to a plane part, bent in a forced assembly mode before welding, and cooled shrinkage deformation after welding is counteracted by utilizing the reverse return internal stress of the edge strip, as shown in figure 3, a novel L-shaped fillet welding clamp is utilized, a base body 3.1 and a clamp 3.4 are connected with the base body through a step pin at the end 2, a pressing strip 3.3 is placed on the clamp 3.4, and a tail end screw is utilized to carry out normal gradual pressure test until the edge strip 1.2 is tightly clamped to achieve the gap requirement state before welding;

as shown in fig. 3, because the width of the edge strip 1.2 is changed, the two ends are wider, the middle part is narrower, if the screw axis of the clamp 3.4 is positioned near the middle layer position of the base 3.11/2, the two ends of the corresponding edge strip can be effectively clamped, but the narrower part can cause the deflection of the bead 3.3, in order to prevent the phenomenon, the effective clamping of the bead 3.3 is realized, as shown in fig. 9, the screw axis of the clamp 3.4 is heightened, a bottom hole is formed on the bead 3.3, and the hole-shaft matching can be formed with the end of the screw, so that the effect of the clamp 3.4 effectively compressing the bead 3.3 can be achieved, the clamping effect of the edge strip 1.2 is improved, and the gap guarantee between the web plate 1.1 and the edge strip 1.2 in the welding process is facilitated;

as the welding gun has a coaxial protective gas output function, oxidation protection is only needed to be carried out on the inner corner part of the diagonal joint structure, as shown in figure 10, the copper plate 3.2 and the base body 3.1 are designed to be in close fit, the center of the base body 3.1 is of a hollow structure and is communicated with the nozzle 3.6, 1 x 45-degree chamfers are formed on the two outer edges of the copper plate 3.2 corresponding to the inner corner joint, 0.8 mm through holes are arrayed on the chamfer inclined planes and are communicated with the inside of the base body 3.1, so that after the nozzle 3.6 is connected with an external hose, inert gas can be continuously discharged from the small holes of the copper plate 3.2 to form a protective atmosphere on the material of the inner corner joint part so as to prevent oxidation, and the welding quality is ensured.

Example 2:

the first step is as follows: as shown in fig. 1, a web plate 1.1 part is manufactured according to a sample plate, and after stamping or hydraulic bending forming, the theoretical shape requirement is met, a 1-2 mm pre-welding trimming allowance is reserved on one side of an edge to be welded, a 10-20 mm welding arc starting and arc stopping allowance is reserved along two ends of a welding line, and a 2-phi 5.2 positioning hole is manufactured; unfolding the edge strip 1.2 according to a digital model, carrying out laser cutting to obtain a flat material, increasing the width of the part by 0.5-1 mm of welding shrinkage allowance, and reserving 10-20 mm of welding arc starting and arc closing allowance along two ends of the welding line;

the second step is that: carrying out surface pickling treatment on the web plate 1.1 and the edge strip 1.2, and wrapping and storing the web plate and the edge strip by kraft paper after finishing the surface pickling treatment;

the third step: as shown in fig. 4, the clamp 3.4 is cancelled to press, the batten 3.3 is taken down, as shown in fig. 5, the web 1.1 is positioned according to the positioning holes with two ends of 2-phi 5.2, and is arranged on the base body 3.1 by using the positioning pins 3.5;

the fourth step: as shown in fig. 6, the edge strip 1.2 is pressed into the middle of the pressing strip 3.3 and the base body 3.1 through pre-bending, a clamp 3.4 is used for gradually screwing a screw until the edge strip is tightly attached, a welding edge is repaired according to the state, a mechanical method is adopted to remove margin, the steps 3 and 4 are repeated until the repairing is completed, the repairing gap before welding is not more than 0.2 mm, and batch operation is completed according to the method;

the fifth step: taking the web 1.1 and the edge strip 1.2 off the fixture, polishing the areas to be welded of the web 1.1 and the edge strip 1.2 by a mechanical method, polishing metallic luster, and finishing batch operation according to the method;

and a sixth step: cleaning a part web 1.1, a flange strip 1.2, a clamp copper plate 3.2, a pressing strip 3.3 and a pressing plate 4 by using an organic solvent, and finishing batch operation according to the method;

the seventh step: as shown in fig. 7, after cleaning, reinstalling a web plate 1.1 and a bead 1.2, connecting a nozzle 3.6 with an argon hose of the equipment, introducing protective gas, pre-connecting the web plate and the bead by manual argon arc welding and tack welding, wherein the spacing between welding points is about 50-100 mm, disassembling welded parts after completion, and completing batch operation according to the method;

eighth step: as shown in fig. 7, the web 1.1 and the edge strip 1.2 after the tack welding are clamped again, the pressing plate 4 is pressed tightly, the pipe mouth 3.6 is connected with an argon hose of the equipment, protective gas is introduced, then the special welding fixture after clamping is placed into the equipment, the pressing plate 4 is pressed tightly by using a pneumatic pressing device, the fixing of the parts before welding is completed, and the welding conditions are met;

the tenth step: the clamp 3.4 is removed from the reverse side for installation, and then the welding batch processing of the symmetric partition frames can be carried out;

a twelfth step: and (4) after the heat treatment is finished, acid washing is carried out to clean surface oxidation color, and finally the connection manufacturing of the thin-wall corner joint structure with different thicknesses is finished.

Claims

1. The method for pre-deforming and connecting the dissimilar-thickness thin-wall angle joint structure is characterized by comprising the following steps of:

the first step is as follows: manufacturing a web plate (1.1) part according to a sample plate, performing stamping or hydraulic bending forming to meet the shape requirement, reserving 1-2 mm of pre-welding repair allowance on one side of an edge to be welded, reserving 10-20 mm of welding arc starting and arc ending allowance along two ends of a welding line, and manufacturing a positioning hole; unfolding the edge strip (1.2) according to a digital model, cutting a flat plate material by laser, increasing the width of a part by 0.5-1 mm of welding shrinkage allowance, and reserving welding arc starting and arc closing allowances of 10-20 mm along two ends of a welding line;

the second step: carrying out surface pickling treatment on the web plate (1.1) and the edge strip (1.2), and wrapping and storing the web plate and the edge strip by kraft paper after finishing the surface pickling treatment;

the third step: the pressing of a clamp (3.4) is cancelled, the pressing strip (3.3) is taken down, the web (1.1) is positioned according to positioning holes at two ends, and the web is arranged on the base body (3.1) by using positioning pins (3.5);

the fourth step: pressing the edge strip (1.2) into the middle of the pressing strip (3.3) and the base body (3.1) through pre-bending, gradually screwing screws by using a clamping device (3.4) until the edge strip is tightly attached, trimming a welded edge according to the state, removing margin by adopting a mechanical method, repeating the third and fourth steps until trimming is finished, ensuring that the trimming gap before welding is not more than 0.2 mm, and finishing batch operation according to the method;

the fifth step: taking the web (1.1) and the edge strip (1.2) down from the fixture, polishing the areas to be welded of the web (1.1) and the edge strip (1.2) by a mechanical method, polishing out metallic luster, and finishing batch operation according to the method;

and a sixth step: cleaning a part web plate (1.1), a flange strip (1.2), a clamp copper plate (3.2), a pressing strip (3.3) and a pressing plate (4) by using an organic solvent, and finishing batch operation according to the method;

the seventh step: after cleaning, mounting the web plate (1.1) and the edge strip (1.2) again, connecting the nozzle (3.6) with an argon hose of the equipment, introducing protective gas, pre-connecting the web plate (1.1) and the edge strip (1.2) through manual argon arc welding and positioning welding, wherein the distance between welding points is 50-100 mm, disassembling welded parts after completion, and completing batch operation according to the method;

eighth step: re-clamping the web (1.1) and the edge strip (1.2) after the tack welding is finished, pressing the pressing plate (4), connecting the pipe nozzle (3.6) with an argon hose of the equipment, introducing protective gas, then putting the special welding fixture after the clamping is finished into the equipment, pressing the pressing plate (4) by using a pneumatic pressing device, finishing the fixing of the parts before welding and having welding conditions;

the ninth step: carrying out welding manufacture according to technological parameters which are as follows: current is 70-85A, voltage is 9-10V, speed is 0.1-0.2 m/min, protective argon is 8-20L/min, after the welding is finished, the special welding fixture is taken out of the equipment, welded bulkhead parts are dismounted, steps 6 and 7 are repeated, and the operation is circulated until the whole batch of parts are manufactured;

the tenth step: the clamp (3.4) is removed from the reverse side for installation, and then the welding batch processing of the symmetric partition frames can be carried out;

2. The method for pre-deforming and connecting the thin-wall corner joint structures with different thicknesses according to claim 1, wherein the special welding fixture comprises a base body (3.1) and a copper plate (3.2), the base body (3.1) and the copper plate (3.2) are assembled in a sleeved mode and then fixedly connected through screws to achieve a sealing effect, a pressing strip (3.3) is in clamping fit with the copper plate (3.2) through a clamp (3.4), the outer surface of the pressing strip is in sliding fit with the clamp screws, and a positioning pin (3.5) is in shaft fit with an upper hole of the base body (3.1); the nozzle (3.6) is vertically matched with the base body (3.1) in a threaded manner.

3. The method for pre-deforming and connecting the dissimilar thickness thin-wall corner joint structure according to claim 1 or 2, wherein the web (1.1) is fixed with the base body (3.1) through positioning holes at two ends by using positioning pins (3.5), the surface to be welded is positioned on the inner side of an arc, the edge strips (1.2) are placed in a vertical plane, the thickness of the clamp base body is slightly larger than the maximum width of the edge strips, and the upper edge and the lower edge of the copper plate (3.2) and the upper edge and the lower edge of the pressing strip (3.3) close to the welding seam are chamfered in the same state.

4. The method for pre-deforming and connecting the thin-walled corner joint structure with different thicknesses as claimed in claim 1 or 2, wherein the matching holes of the base body (3.1) and the clamping device (3.4) are designed to be double-sided, so that the common processing of the left and right symmetrical parts of the bulkhead can be realized.

5. The method for pre-deforming and connecting a thin-walled corner joint structure with different thicknesses according to claim 3, characterized in that the matching holes of the base body (3.1) and the clamping device (3.4) are designed to be double-sided, so that the common machining of the left and right symmetrical parts of the bulkhead can be realized.

6. The method for the pre-deformation connection of the dissimilar thickness thin-wall corner joint structure according to the claim 1, the claim 2 or the claim 5, characterized in that the screw axis of the clamp (3.4) is heightened, and a bottom hole is formed on the batten (3.3) and can form a hole shaft matching with the screw end.

7. The method for predeformation joining of dissimilar thickness thin wall fillet joint structure according to claim 1, 2 or 5, characterized in that the center of the base body (3.1) is hollow and communicates with the nozzle (3.6), and 1 x 45 ° chamfers are made at two positions of the copper plate (3.2) corresponding to the outer edges of the inner fillet joint.

8. The method for the pre-deformed connection of the dissimilar thickness thin-wall corner joint structure according to claim 3, wherein the center of the base body (3.1) is a hollow structure and is communicated with the nozzle (3.6), and chamfers of 1 x 45 degrees are formed at two positions of the copper plate (3.2) corresponding to the outer edges of the inner corner joint.

9. The method for the predeformation connection of the dissimilar thickness thin-walled fillet joint structure according to claim 4, wherein the center of the base body (3.1) is hollow and is communicated with the nozzle (3.6), and chamfers of 1 x 45 degrees are formed at two positions of the copper plate (3.2) corresponding to the outer edges of the inner fillet joint.