Aircraft pull rod structure and welding manufacturing method thereof

Abstract

The invention provides an aircraft pull rod structure and a welding manufacturing method thereof, a pull rod assembly comprises three welding parts, a butt joint and lap joint combined joint is formed, and the assembly is welded by adopting a welding method of three electron beams with equal energy. A two-component structure adopted by an early pull rod is improved, a three-component welding method is adopted, large forgings and a large number of numerical control machining processes are omitted, and the manufacturing cost is reduced. A three-beam electron beam welding technology is provided, arcs are started at the positions, spaced by 120 degrees, on the same circumference at the same time, welding stress is evenly distributed, and the purpose of reducing welding deformation is achieved. A butt joint and lap joint combined joint form is adopted, the advantage of large fusion depth of electron beam welding is utilized, three assemblies are thoroughly welded at a time, and the production efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the field of structural design of tie rod parts in aviation manufacturing, and in particular relates to an aircraft tie rod structure and a welding manufacturing method thereof. Background Art

[0002] A large number of steel tie rod parts are used in aircraft to fold the leading and trailing edges of wings, retract landing gear, and push and pull aerodynamic wing surfaces, etc., to achieve aircraft take-off, steering, lifting and lowering functions. Tie rods are very important components of aircraft systems and are widely used in aircraft take-off and landing, flight attitude adjustment, flight balance and stability systems. The function of the tie rod is to transmit force, reciprocate along a straight line in a sleeve with extremely high precision, push components or assemblies to reach the specified position at a certain speed and force, and withstand huge hydraulic damping for a long time. Therefore, the structure requires extremely high processing accuracy, based on the verticality of the piston rod end face and the center axis must be less than 0.05mm / 300mm.

[0003] Tie rods with unqualified verticality cannot withstand high-frequency, high-intensity and high-load flight tests, which will inevitably cause damage defects at the root of the tie rod, resulting in tie rod breakage and mechanism jamming. At the least, the function will fail and the aircraft will not be able to operate normally; at the worst, the landing gear will not be able to be retracted or locked during retraction, causing serious flight accidents. These are all lessons learned from blood. Therefore, in the manufacturing process, ensuring the verticality of the tie rod assembly is a very important link, and various aviation manufacturers also use a variety of methods to ensure the verticality of the tie rod.

[0004] After long-term development and improvement, there are two main methods for manufacturing tie rods: machining and welding. Machining is rarely used due to its high cost and long cycle. Welding is widely used, but there are still problems such as large deformation and short life that need to be improved to meet the requirements of small deformation, high efficiency and low cost.

[0005] Machining is to forge an integral forging with an outer dimension similar to that of the tie rod, and then use mechanical processing to remove excess material to form the final structure. The tie rod is manufactured by machining, which has high precision and good integrity, but the production cycle is too long and the manufacturing cost is extremely high. It cannot meet the engineering needs and has been eliminated. The welding method is to decompose the tie rod into two parts: a circular cover plate and a cylindrical piston rod, and process them separately. The cover plate is made of sheet metal and the piston rod is made of forgings. Then, the two parts are welded together along the circumference by manual fusion welding. The weld is a closed circle, and the arc start end and arc end coincide. Then, the outer surface of the tie rod is machined again based on the end face of the piston rod to ensure the verticality of the tie rod. Compared with the machining method, the welding method has a greatly shortened production cycle and a sharp reduction in manufacturing costs due to the abandonment of large forgings and the elimination of forging and machining processes. It can meet engineering needs and is widely used.

[0006] However, the welding method has two difficult-to-overcome problems: deformation and cracking of the tie rod and uneven wall thickness of the rod body, which ultimately lead to poor movement and breakage of the tie rod. When the tie rod is manufactured by welding, the weld is a closed circle. In order to ensure the welding quality, the arc-ending end must cover the arc-starting end. Repeated heating at the same point causes the longitudinal axis of the tie rod to deflect in the overlapping direction, and the center axis is no longer perpendicular to the piston rod end face, resulting in accuracy that cannot meet the requirements. In order to correct the welding deformation problem, turning and shaping the outer surface of the tie rod are continued. Based on the piston rod end face, after turning the tie rod surface, the tie rod wall thickness is seriously uneven, causing the rotation axis and the center axis of the tie rod to not coincide, and an angle appears between the two axes. With the continuous increase in service time, the uneven release of welding residual stress leads to a continuous increase in the angle between the rotation axis and the center axis. The center axis of the tie rod continuously deflects toward the coincidence point of the welding arc-ending and arc-starting, causing the verticality of the piston rod end face and the center axis of the tie rod to continue to decrease, hindering the straight-line movement of the tie rod.

[0007] During service, the tie rod moves back and forth in the sleeve at high speed along a straight line for a long time. The rigidity of the sleeve is much higher than that of the tie rod, and the tie rod is constrained in the straight line direction. The arc-shaped tie rod with severe deformation and uneven wall thickness, running in the extremely rigid linear sleeve, is subjected to alternating tensile and compressive loads for a long time, which will inevitably cause cracks at the root of the tie rod, and eventually the tie rod will break and the mechanism will be stuck. Through the analysis of several examples of tie rod breakage, it is proved that after long-term use, the tie rod will inevitably deviate to the overlap direction of welding arc closing and arc starting, and a crack source will appear at the corresponding position. As the service time increases, it gradually expands and penetrates the tie rod wall thickness, and finally breaks completely.

[0008] Therefore, how to solve the problem of uneven deformation after welding has become a difficult problem to be solved in manufacturing tie rods, while reducing manufacturing costs and continuing to shorten the manufacturing cycle. With the continuous development of aviation manufacturing technology, titanium alloy materials are used to manufacture tie rods, but the problem still exists. In addition, the elastic modulus of titanium alloy is much higher than that of steel, resulting in greater welding residual stress and welding deformation. The tie rod structure needs to solve the problems of post-weld deformation and uneven wall thickness. Summary of the invention

[0009] The invention provides an aircraft tie rod structure and a welding manufacturing method thereof, which solves the problems of deformation and uneven wall thickness after welding.

[0010] A first aspect of the present invention provides an aircraft tie rod structure, comprising: a cover plate 1, a rod body 2, and a sealing sleeve 3;

[0011] The rod body 2 is cylindrical, with a central through hole in the center, an inner diameter of d1, and an outer diameter of d2;

[0012] The cover plate 1 is a cylinder, and a first convex ring is arranged on the top outer ring. The cover plate 1 is sleeved in the central through hole of the rod body 2, and the first convex ring is arranged on the end surface of the rod body 2. The outer diameter of the cover plate 1 is consistent with the inner diameter of the central through hole of the rod body 2, and the outer diameter of the first convex ring is d3, d3 is greater than d1, and d3 is smaller than d2.

[0013] The sealing sleeve 3 is a circular sleeve, with a reducing through hole at the center, a second convex ring at the middle of the reducing through hole, the reducing through hole on one side of the second convex ring has an inner diameter of d4, the reducing through hole on the other side has an inner diameter of d2, and the inner diameter of the second convex ring is d3; d4 is greater than d2; the sealing sleeve 3 is sleeved on the outside of the cover plate 1 and the rod body 2; the second convex ring fits the first convex ring, and the contact parts of the cover plate 1, the rod body 2 and the sealing sleeve 3 constitute a welded butt joint and lap joint;

[0014] The butt joint and lap joint are connected by electron beam welding. Three electron beams are used for welding. The arc is started at the same time at positions 120° apart on the contact circumference of a cover plate 1 and a sealing sleeve 3, and the arc is closed at the same time after welding around the circumference to form an annular weld.

[0015] Optionally, a welding filling material in contact with the rod body 2 is provided on the bottom end surface of the cover plate 1 .

[0016] Optionally, a welding filler material in contact with the rod body 2 is provided on the end surface of the sealing sleeve 3 at one end with an inner diameter d2.

[0017] Optionally, the second convex ring has the same thickness as the first convex ring.

[0018] Optionally, the thickness of the region of the cover plate 1 with an outer diameter of d2 and the thickness of the region of the sealing sleeve 3 with an inner diameter of d2 are the same.

[0019] Optionally, the rod body 2 is made of a conduit, and the cover plate 1 and the sealing sleeve 3 are made of a plate.

[0020] A second aspect of the present invention provides a welding manufacturing method for an aircraft tie rod structure as described in any one of the first aspects, comprising:

[0021] S1, place the rod body 2 at the plumb bob position and firmly position it, install the cover plate 1 at the top center of the rod body 2, install the sealing sleeve 3 on the top of the rod body 2, and simultaneously sleeve the cover plate 1 and the rod body 2 to obtain an assembled pull rod assembly;

[0022] S2. Fix the assembled tie rod assembly in the vacuum chamber and keep the tie rod assembly in the plumb bob position, adjust the height, beam splitting and position of the electron beam welding gun, split the electron beam to form three electron beams with equal energy, namely beam A, beam B and beam C, and the beam landing points are all on the contact circumference of the cover plate 1 and the sealing sleeve 3, and form an angle of 120°;

[0023] S3. Use preset welding parameters to weld the pull rod assembly in a counterclockwise direction along the contact circular path. The three beams rotate at the same speed at the same time. After continuous welding for 120°, they are interconnected to form an annular weld.

[0024] Optionally, the method further includes:

[0025] S4. After the annular weld is formed, continue to weld forward at least 20° to form three weld overlap areas with a mutual angle of 120° and evenly distributed.

[0026] The beneficial effects of the present invention are as follows: the present invention provides an aircraft tie rod structure and a welding manufacturing method thereof, 1) in the tie rod structure design, the number of components is increased from 2 to 3, the forgings and the corresponding machining processes are omitted, and the commonly used specifications of sheet and pipe materials are used to achieve the purpose of reducing manufacturing costs. 2) The advantage of using electron beam welding in a vacuum environment is used, and a 3-beam electron beam welding process is adopted to start the arc at three different positions, and the overlap points of the arc start end and the arc end are evenly arranged, thereby reducing welding deformation. 3) The butt and lap joint joint form is adopted to weld three components at one time, thereby improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1a This is the front schematic diagram of the cover plate 1;

[0028] Figure 1b is a second schematic diagram of a cross section of a cover plate;

[0029] Figure 1c This is the third schematic diagram of the cover plate axis side;

[0030] Figure 2a Schematic diagram of the rod body from the side;

[0031] Figure 2b A schematic diagram of the rod body in the forward direction;

[0032] Figure 2c Schematic diagram of the cross section of the rod body;

[0033] Figure 3a Front view of the sealing sleeve;

[0034] Figure 3b Schematic diagram of the sealing sleeve cross section;

[0035] Figure 3c Axial schematic diagram of the sealing sleeve;

[0036] Figure 4a Overall schematic diagram of tie rod assembly;

[0037] Figure 4b Schematic diagram of the pull rod assembly position;

[0038] Figure 4cSchematic diagram of the position of the tie rod assembly weld;

[0039] Figure 5a Front view of electron beam split welding;

[0040] Figure 5b Schematic diagram of electron beam split welding position;

[0041] Figure 6a Schematic diagram of the starting position of the welding process;

[0042] Figure 6b Schematic diagram of the end position of the welding process;

[0043] Figure 7a Schematic diagram of the process of metal melting to form the position of components before the joint;

[0044] Figure 7b Schematic diagram of the process of the weld position after the metal melts to form the joint;

[0045] Description of reference numerals:

[0046] 1 cover plate, 2 rod body, 3 sealing sleeve, 4 joint, 5 electron gun, 6 beam A, 7 beam B, 8 beam C, 9 weld A, 10 weld B, 11 weld C, 12 annular weld, 13 weld A overlapping area, 14 weld B overlapping area, 15 weld C overlapping area, 16 adjacent area. DETAILED DESCRIPTION

[0047] The present application is further described in detail below in conjunction with a manufacturing example of a titanium alloy pull rod and accompanying drawings.

[0048] The present invention aims at the problems of large welding deformation, high production cost and long manufacturing cycle in the manufacturing process of tie rod parts, optimizes the tie rod structure, and proposes an aircraft tie rod structure and its welding manufacturing method. After the optimized design, the components of the tie rod are changed from 2 to 3, forgings and their processing are abandoned, and pipes and sheets are used for production, which improves production efficiency and reduces manufacturing costs. The electron beam welding method with three equal beam energies is adopted, the overlap points of the arc start and arc end positions are evenly arranged, and three components are welded at one time, which reduces the welding deformation of the tie rod and increases the service life of the tie rod.

[0049] The present invention mainly includes the following contents: 1) abandoning the structure consisting of a cover plate and a piston rod in the traditional design, and adopting a design structure consisting of a cover plate, a rod body and a sealing sleeve in three parts, all of which use plate and pipe materials, and abandon the use of forging materials, so as to achieve the purpose of reducing manufacturing costs; 2) abandoning the traditional manual arc welding connection method, and adopting three-beam electron beam welding technology, starting arcs at positions 120° apart on a circle at the same time, and closing arcs at the same time after welding for 120°, so as to evenly distribute welding stress and achieve the purpose of reducing welding deformation; 3) adopting the butt and lap joint joint form, using the advantage of the large penetration depth of electron beam welding, three components are welded through at one time, and production efficiency is improved.

[0050] The traditional tie rod structure is welded from the cover plate and the piston rod. The weld is a closed circle along the edge of the cover plate, and the arc start and arc end of the welding process overlap. In order to ensure full penetration, a 90° groove is opened in the area to be welded, and manual welding is used to weld along the circle. Since the overlap point is heated and melted twice, the heat input at the overlap point is greater than that of other parts of the weld, which eventually leads to uneven welding residual stress and deformation, causing the tie rod to deform and break in the later stage, and the system to get stuck. At the same time, since the piston rod is manufactured by forging and machining methods, the material utilization is less than 40%, the processing cycle is long, and the manufacturing cost is greatly increased.

[0051] The improved tie rod structure no longer uses forgings, but conventional pipes and plates, which shortens the manufacturing cycle and saves manufacturing costs. The components are improved from two pieces (cover plate and piston rod) to three pieces (cover plate, rod body and sealing sleeve), and the joints are in the form of butt joints and lap joints. They are welded in one go using vacuum electron beam welding. Three pieces of equipment can be used for separate processing and then assembled and welded in one go, which improves production efficiency. Using three-beam electron beam welding technology, welding is completed in three sections at the same time. The three welding overlap points are evenly distributed on the circumference, and the welding stress is evenly distributed along the circumference, eliminating the phenomenon of central axis deflection. The wall thickness of the tie rod is guaranteed to be uniform in the later stage, and the straightness of the tie rod and sleeve is ensured, which ultimately eliminates the deformation and breakage of the tie rod.

[0052] Electron beam welding is a welding process in which the base metal is bombarded by electron beams in a vacuum environment and then melted to form a weld. The vacuum degree of the welding chamber is less than 5×10 －2 Pa, the air content is extremely low, avoiding atmospheric pollution to the welding process, and the weld quality can meet the requirements of aviation level I (HB5363-1995). The three-beam electron beam welding technology is to divide the original electron beam into three beams with equal energy, and start arc welding at different parts of the circular joint at the same time, and connect the end to end to form a closed weld. The speed of three-beam electron beam welding is 3 times that of conventional electron beam welding. It can choose three different positions to start arc at the same time, the welding residual stress is evenly distributed, and the welding deformation offsets each other.

[0053] For example, as shown in Figures 1-7, in one embodiment of the present invention, the improved pull rod is welded by a cover plate 1, a rod body 2 and a sealing sleeve 3. After decomposition, the rod body 2 is made of a conduit, and the sealing sleeve 3 is made of a plate, which are respectively made by three devices in a division of labor. The structure of the cover plate 1 is unchanged, such as Figure 1a , Figure 1b and Figure 1c As shown; the rod body 2 is a long tubular structure, such as Figure 2a , Figure 2b and Figure 2c As shown; the sealing sleeve 3 is a circular sleeve with a hole at the bottom, such as Figure 3a , Figure 3b and Figure 3c shown.

[0054] Figure 4a and Figure 4b The following is an assembly diagram of the tie rod, with the three components forming a butt and lap joint. Using a special assembly fixture, the rod body 2 is placed in the plumb position and firmly positioned. The cover plate 1 is installed at the top center of the rod body 2, ensuring that the cover plate 1 partially covers the end of the rod body 2. The sealing sleeve 3 is then installed on the top of the rod body 2 and located around the cover plate 1. After assembly, the rod body 2 and the sealing sleeve 3 form a joint 4.

[0055] Move the assembled tie rod assembly and the fixture into the vacuum chamber, adjust the beam splitting and position of the electron beam welding gun 5, and ensure that the tie rod is in the plumb position ready for welding. Figure 5a and Figure 5b As shown. Fix the installed pull rod assembly in the vacuum chamber and ensure that it is in the plumb bob position, and carry out vacuuming and parameter calling according to the vacuum electron beam welding process. Adjust the height of the welding gun 5 and split the electron beam to form three electron beams with equal energy, namely beam A 6, beam B 7 and beam C 8, and ensure that the deflected beams all land on the joint 4 at an angle of 120° and are evenly distributed.

[0056] After adjusting the welding gun, call the confirmed welding parameters, weld the tie rod assembly in a counterclockwise direction along the joint 4 path, and the three beams rotate at the same speed to complete the welding. Figure 6a and Figure 6b As shown. According to the confirmed welding parameters and paths, the three beams start welding at the same time at positions 120° apart from each other, forming three independent welds, weld A 9, weld B 10, and weld C 11. After continuous welding for 120°, they are interconnected to form a circular weld 12. In order to ensure the quality of the joint, continue to weld forward for at least 20° to form weld A overlap area 13, weld B overlap area 14, and weld C overlap area 15 with an angle of 120°, which are evenly distributed.

[0057] During the welding process, the adjacent areas of the cover plate 1, the rod body 2 and the sealing sleeve 3 are melted to form a weld to connect the three components, such as Figure 7a and Figure 7b The cover plate 1, the rod body 2 and the sealing sleeve 3 form a butt joint and lap joint, and the metal of the adjacent area 16 is melted by a vacuum electron beam welding process, and the melting depth is not less than the joint thickness to form an annular weld 12 to connect the three components into one.

[0058] The invention has obvious application effect, and can be applied not only to the manufacture of titanium alloy pull rods, but also to steel parts, greatly improving the welding quality. At the same time, it can be extended to the manufacture of other axisymmetric components, and can meet the purpose of reducing welding deformation, improving manufacturing efficiency, and reducing manufacturing costs.

Claims

1. An aircraft tie rod structure, characterized in that: include: Cover plate (1), rod body (2), sealing sleeve (3); The rod body (2) is cylindrical, with a central through hole at the center, an inner diameter of d1, and an outer diameter of d2; The cover plate (1) is a cylinder, and a first convex ring is arranged on the outer ring of the top. The cover plate (1) is sleeved in the central through hole of the rod body (2), and the first convex ring is arranged on the end surface of the rod body (2); the outer diameter of the cover plate (1) is consistent with the inner diameter of the central through hole of the rod body (2), and the outer diameter of the first convex ring is d3, d3 is greater than d1, and d3 is smaller than d2; The sealing sleeve (3) is a circular sleeve, with a reducing through hole at the center, a second convex ring at the middle of the reducing through hole, the reducing through hole on one side of the second convex ring has an inner diameter of d4, the reducing through hole on the other side has an inner diameter of d2, and the inner diameter of the second convex ring is d3; d4 is greater than d2; the sealing sleeve (3) is sleeved on the outer sides of the cover plate (1) and the rod body (2); the second convex ring fits the first convex ring, and the contact parts of the cover plate (1), the rod body (2) and the sealing sleeve (3) form a welded butt joint and lap joint; The butt joint and lap joint are connected by electron beam welding. Three electron beams are used for welding. The arcs are started at the same time at positions 120 degrees apart on the contact circumference of a cover plate (1) and a sealing sleeve (3). The arcs are closed at the same time after welding around the circumference to form an annular weld.

2. The aircraft tie rod structure according to claim 1, characterized in that: A welding filling material in contact with the rod body (2) is arranged on the bottom end surface of the cover plate (1).

3. The aircraft tie rod structure according to claim 1, characterized in that: A welding filling material in contact with the rod body (2) is arranged on the end surface of one end of the sealing sleeve (3) with an inner diameter of d2.

4. The aircraft tie rod structure according to claim 1, characterized in that: The second protruding ring has the same thickness as the first protruding ring.

5. The aircraft tie rod structure according to claim 4, characterized in that: The thickness of the region of the cover plate (1) with an outer diameter d2 and the thickness of the region of the sealing sleeve (3) with an inner diameter d2 are the same.

6. The aircraft tie rod structure according to claim 1, characterized in that: The rod body (2) is made of a conduit, and the cover plate (1) and the sealing sleeve (3) are made of a plate material.

7. A welding manufacturing method for an aircraft tie rod structure according to any one of claims 1 to 7, characterized in that: include: S1. Place the rod body (2) at the plumb bob position and position it firmly, install the cover plate (1) at the top center of the rod body (2), install the sealing sleeve (3) at the top of the rod body (2), and simultaneously sleeve the cover plate (1) and the rod body (2) to obtain an assembled pull rod assembly; S2. Fix the assembled tie rod assembly in the vacuum chamber and keep the tie rod assembly in the plumb bob position, adjust the height, beam splitting and position of the electron beam welding gun, split the electron beam, and form three electron beams with equal energy, namely beam A, beam B and beam C. The beam landing points are all on the contact circumference of the cover plate (1) and the sealing sleeve (3) and form an angle of 120°; S3. Use preset welding parameters to weld the pull rod assembly in a counterclockwise direction along the contact circular path. The three beams rotate at the same speed at the same time. After continuous welding for 120°, they are interconnected to form an annular weld.

8. The welding manufacturing method according to claim 7, characterized in that: The method further comprises: S4. After the annular weld is formed, continue to weld forward at least 20° to form three weld overlap areas with a mutual angle of 120° and evenly distributed.

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