Method and die for forming Y-shaped connecting piece of airplane fuselage

Abstract

The invention belongs to the technical field of aircraft part forming and manufacturing, and relates to an aircraft fuselage Y-shaped connecting piece forming method which comprises the following steps: preparing an annular blank; an annular die is adopted for conducting precise special-shaped ring rolling on the annular blank, a special-shaped ring forging is obtained, the cross section of the special-shaped ring forging is of a double-Y-shaped structure which is vertically symmetrical and connected into a whole, and the double Y shapes are connected through short branches; the special-shaped ring forging is taken out of the annular die and symmetrically cut in the axial direction to obtain two circular ring pieces with Y-shaped cross sections, each circular ring piece is subjected to rough machining and then evenly divided into three sections, and six Y-shaped connecting pieces with the same shape and size are obtained in total. The invention further provides a forming die applied to the method. The Y-shaped connecting piece of the aircraft fuselage prepared by the method and the mold is high in precision, high in efficiency and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft parts manufacturing, and in particular relates to a forming method and a mold for a Y-shaped connecting piece of an aircraft fuselage. Background Art

[0002] Y-type connectors are key load-bearing components on large aircraft, and their manufacturing technology affects the aircraft assembly accuracy, overall aerodynamic shape and service life. The cross section of the Y-type connector is "Y" shaped, and the length direction is one-third of an arc. For example, the Y-type connector of the C919 aircraft frame is one-third of an arc with an outer diameter of about 2850mm. The material is generally made of lightweight and high-strength titanium alloy / aluminum alloy.

[0003] Y-type connectors have complex shapes, large sizes, thin walls, weak rigidity, and are prone to deformation during the forming and manufacturing process. Precise forming and manufacturing are difficult, and it was impossible to break through localization in the early stages. The connectors have always relied on foreign imports, which has high costs and uncontrollable technology.

[0004] In recent years, domestic enterprises and universities have tried to break through the Y-type connector forming and manufacturing technology, and developed two Y-type connector forming and manufacturing technologies: 1) An extrusion process is used to obtain an extruded part that follows the shape of the Y-type connector cross section, and the extruded part is hot-drawn to obtain an arc-shaped Y-type connector. However, due to its weak rigidity and complex shape, it is difficult to control the stress and deformation behavior during the bending process along the Y-type cross section, and dimensional deviation problems are prone to occur; 2) China Second Heavy Industries reported that the Y-type connector was formed and manufactured through a die forging process, but the Y-type connector is long. The Y-type connector reported by China Second Heavy Industries is 3.4 meters long, with a large forming load, requiring forging equipment of more than 20,000 tons, and the die size is large, resulting in high manufacturing costs.

[0005] The patent with publication number CN110834178A discloses a method for manufacturing a Y-shaped connector for an aircraft spherical frame, the method comprising: obtaining a rod-shaped blank; after rough-forming the rod-shaped blank, bending the rod-shaped blank into an arc structure with a preset curvature to obtain a rough-shaped material; forging the rough-shaped blank using a preset forging die to obtain a forged part, wherein the forged part can be cut into two identical parts to be processed; cutting the forged part to obtain two identical parts to be processed; machining the parts to be processed to obtain a Y-shaped connector. The above method has a complex process, low manufacturing efficiency, and the obtained product has low precision. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a low-cost and high-precision aircraft fuselage Y-type connector forming method and mold.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is: a method for forming a Y-shaped connector of an aircraft fuselage, comprising the steps of: preparing a ring-shaped blank; The circular ring blank is subjected to precision special-shaped ring rolling by using a ring die to obtain a special-shaped ring forging, wherein the cross section of the special-shaped ring forging is a double Y-shaped structure that is symmetrical and connected as one, and the double Y-shaped structure is connected by a shorter branch; The special-shaped ring forging is taken out from the annular die, and two circular ring pieces with Y-shaped cross sections are obtained by axial symmetry cutting. Each circular ring piece is then roughly machined and divided into three sections, obtaining a total of six Y-shaped connectors with the same shape and size.

[0008] In one embodiment, after taking out the special-shaped ring forging from the annular die, the process further includes: heat treating the special-shaped ring forging, and after the heat treatment, putting the special-shaped ring forging back into the annular die for ring rolling and shaping.

[0009] In one embodiment, the method of using an annular die to perform precision profiled ring rolling on a ring-shaped blank comprises the following steps: The circular ring-shaped blank is placed in the ring mold at room temperature, heated to the forging temperature along with the ring mold, and then lifted out of the ring mold to the ring rolling machine for precision ring rolling to fill the cavity with the blank to obtain a double Y-shaped special-shaped ring forging structure with a symmetrical cross-section.

[0010] In one embodiment, near-isothermal ring rolling is achieved by online temperature supplementation using an induction heating device.

[0011] In one embodiment, the annular mold includes an inner ring mold and an outer ring mold that are used in conjunction with each other. After the precision ring rolling, air cooling is first performed to separate the special-shaped ring forging from the annular mold and form a gap. When demolding, the inner ring mold and the special-shaped ring forging are taken out as a whole along the axial direction.

[0012] In one embodiment, the inner ring mold is a split structure, and the inner ring mold includes multiple sections of detachably connected circular rings. After demolding, the multiple sections of circular rings of the inner ring mold are disassembled along the circumferential direction to take out the special-shaped ring forgings.

[0013] In one embodiment, the annular blank is made of aluminum alloy or titanium alloy.

[0014] In one embodiment, preparing the toroidal blank comprises the steps of: Multi-directional forging: The ingot is heated to a preset temperature, and multi-directionally forged to obtain a solid cylindrical ingot, and a hole is punched in the center of the solid cylindrical ingot to obtain a hollow cylindrical ingot; Horse rack expansion: The hollow cylindrical blank is expanded by the horse rack process to obtain a rectangular cross-section ring blank; Rectangular ring rolling: Ring rolling technology is used to reduce the wall thickness, height and diameter of rectangular cross-section ring blanks; Car skin: The rectangular ring is rolled into a blank and machined to obtain a circular ring blank that meets the size requirements.

[0015] Based on a general inventive concept, the present invention also provides a Y-shaped connector forming mold for an aircraft fuselage, which is applied to the forming method described above in the claim, and includes an inner ring mold and an outer ring mold used in conjunction with each other, a core roller, a main roller, a guide roller and a cone roller used in conjunction with the inner ring mold and the outer ring mold, the inner ring mold is a split structure, including multiple sections of detachably connected circular rings, the multiple sections of the circular rings are detachably connected by connecting keys, and each section of the circular ring is connected to the outer ring mold by a connecting piece.

[0016] In one embodiment, an induction heating device is also included for performing online temperature compensation during the ring rolling process to achieve near-isothermal ring rolling.

[0017] Compared with the prior art, the invention has the following beneficial effects: the Y-type connector has a complex shape, a large size, generally greater than 2.8m, and a thin wall thickness and weak rigidity. The prior art usually adopts an extrusion-drawing forming method, which is prone to deformation during the forming and manufacturing process, and is difficult to accurately form and manufacture, and the material utilization rate is low, generally around 10%. In the present application, an annular die constraint is used for special-shaped ring rolling. During the ring rolling forming, the blank is gradually filled and formed in the cavity composed of the annular die and the core roller to obtain a special-shaped ring forging with a precise shape. The cross section of the special-shaped ring forging is a double Y-shaped structure that is symmetrical and connected in one piece, and the double Y-shaped structure is connected by a shorter branch. Since the cross section of the special-shaped ring forging is a symmetrical structure up and down, the axial side load can be eliminated during the forming process, and the forming stability is high. One precision ring rolling forming can achieve six pieces in one mold, which can greatly improve the manufacturing efficiency; the special-shaped ring forging is filled and formed in the cavity composed of the ring mold and the core roller. After the solid solution heat treatment, the special-shaped ring forging is put into the ring mold again for ring rolling correction and residual stress reduction. The forming accuracy is high, the single-side margin is 3-5mm, and the material utilization rate is about 25%, which is doubled compared with the conventional "extrusion + bending" process; the ring mold is used for special-shaped ring rolling, and the material extends and fills in the closed cavity to form a multi-directional streamline, and the obtained special-shaped ring forging has stable and reliable performance. And ring rolling is a kind of local continuous progressive deformation, the equipment tonnage capacity requirement is small, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 is a process flow chart of a method for forming a Y-shaped connector of an aircraft fuselage according to an embodiment; Figure 2 (a) and (b) are schematic diagrams of a special-shaped ring forging before and after forming according to an embodiment; Figure 3 is a schematic cross-sectional view of a special-shaped ring forging according to one embodiment; Figure 4 This is a schematic diagram of a mold structure for forming a Y-shaped connector for an aircraft fuselage according to an embodiment; Figure 5 The present invention is a schematic structural diagram of the cooperation between the inner ring mold and the outer ring mold of a Y-shaped connector forming mold for an aircraft fuselage according to one embodiment. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0021] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0022] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0023] See also Figure 1-5 , a method for forming a Y-shaped connector of an aircraft fuselage, comprising the following steps: S10, preparing a ring-shaped blank.

[0024] Specifically, the preparation of the ring-shaped blank comprises the following steps: S110, multi-directional forging: heating the ingot to a preset temperature, performing multi-directional forging on the ingot to obtain a solid cylindrical ingot, and punching a hole in the center of the solid cylindrical ingot to obtain a hollow cylindrical ingot.

[0025] Specifically, the raw material of the ingot can be an aluminum alloy or a titanium alloy. The ingot is heated to a preset temperature as the forging temperature, the forging temperature of the titanium alloy is 800-950°C, and the forging temperature of the aluminum alloy is 400-510°C. Preferably, the blanking burrs of the ingot are removed, and a release agent is evenly coated on the surface of the ingot. Casting defects are eliminated by multi-directional forging of the ingot.

[0026] S120, horse rack expansion: the hollow cylindrical blank is expanded by horse rack process to obtain a rectangular cross-section ring blank.

[0027] S130, rectangular ring rolling: The ring rolling process is used to reduce the wall thickness, height and diameter of the rectangular cross-section ring blank.

[0028] S140, Car skin: Machining the rectangular ring rolled blank to obtain a circular ring blank that meets the size requirements.

[0029] S20, using an annular die to constrain the circular ring blank to perform precision special-shaped ring rolling to obtain a special-shaped ring forging, the cross section of which is a double Y-shaped structure that is symmetrical and connected in one piece, and the double Y-shaped structure is connected by a shorter branch. That is, the cross section of the special-shaped ring forging can be regarded as two Y-shaped structures connected by a shorter branch to form a double Y-shaped cross section (see Figure 3 ). The connection is close to an arc shape, which is conducive to the smooth flow of materials during forming.

[0030] Specifically, in one embodiment, the use of an annular die for special-shaped ring rolling includes the following steps: The circular ring-shaped blank of the car body is placed in the ring mold at room temperature, heated to the forging temperature with the ring mold, and then hoisted out of the ring mold to the ring rolling machine for precision ring rolling. On the ring rolling machine, the ring mold is driven by the driving roller to rotate and the core roller is radially fed, so that the blank gradually fills the cavity, realizes the precise forming of the special-shaped cross-section ring, and obtains a double Y-shaped special-shaped ring forging with a symmetrical structure up and down and connected as one. The material extends and fills in the cavity composed of the ring mold and the core roller, forming a multi-directional streamline. The special-shaped ring forging is a double Y-shaped cross-section that is symmetrical up and down, eliminating the unbalanced load during the forming process and improving production efficiency.

[0031] Preferably, the annular mold forming mold includes an inner ring mold 10 and an outer ring mold 20 used in conjunction with each other, and a core roller 30, a main roller 40, a guide roller 50 and a tapered roller 60 used in conjunction with the inner ring mold 10 and the outer ring mold 20. Specifically, in one embodiment, the inner ring mold 10 is a split structure, and the inner ring mold 10 includes multiple sections of detachably connected circular rings 110, and the multiple sections of the circular rings are detachably connected by connecting keys 120. The inner ring mold 10 is a split structure, and the inner ring mold 10 includes multiple sections of detachably connected circular rings 110. After demolding, the multiple sections of circular rings 110 of the inner ring mold 10 are disassembled in the circumferential direction, and the special-shaped ring forging is taken out. In one embodiment, the inner ring mold 10 is composed of 4 arcs, and each arc is connected to the outer ring mold by a connector 130 to prevent the inner ring mold from sliding due to circumferential force during the forming process. It can also be a 3-segment or 2-segment circular ring. After precision ring rolling, since the expansion coefficient of the double Y-shaped special-shaped ring forging is greater than that of the annular mold, it is separated from the annular mold after air cooling and a gap is formed. When demolding, the inner ring mold 10 and the special-shaped ring forging are taken out as a whole along the axial direction. And the inner ring mold 10 is a split structure, so that the multi-segment circular ring 110 of the inner ring mold 10 can be disassembled in the circumferential direction to achieve smooth demolding of the special-shaped ring forging. Preferably, the multi-segment circular ring 110 is connected by a connecting key 120. Specifically, the two ends of the connecting key 120 are connected to two adjacent circular rings 110, and one end of the connecting key 120 is provided with a screw ejection hole 122, and a screw matching the screw ejection hole 122 is provided at the corresponding position of the circular ring 110 to achieve a detachable connection. Of course, in other embodiments, other detachable connection methods such as snap connections can also be used.

[0032] Preferably, in one embodiment, the ring rolling is performed on a ring rolling machine, and online temperature supplementation is performed by an induction heating device 70 to achieve near-isothermal ring rolling, thereby preventing incomplete forming due to excessively rapid temperature drop.

[0033] S30, taking out the special-shaped ring forging from the annular die, cutting it symmetrically along the axial direction to obtain two circular ring pieces with Y-shaped cross sections, and then roughly processing each circular ring piece and dividing it into three sections, so as to obtain six Y-shaped connectors with the same shape and size.

[0034] Specifically, in one embodiment, the removed special-shaped ring forging is machined, first axially symmetrically cut into two full circles, then each full circle is rough-machined, then the two full circles are evenly divided into three sections along the circumference, and finally fine-machined to obtain six Y-shaped connectors with the same shape and size. The single-side margin in the Y-shaped connector forming is 3-5mm, and the material utilization rate is about 25%. Compared with the general forming method, the material utilization rate is doubled.

[0035] In one embodiment, after the special-shaped ring forging is taken out from the annular die, the process further includes: heat treating the special-shaped ring forging, placing the special-shaped ring forging in the annular die again for ring rolling and shaping after solution quenching, and aging together with the die, and finally taking out the special-shaped ring forging. After the special-shaped ring forging is precision ring-rolled, it is necessary to perform solution quenching and aging heat treatment. In order to prevent the special-shaped ring forging from quenching deformation, the special-shaped ring forging is placed in the annular die again for shaping, which can improve the dimensional accuracy of the special-shaped ring forging, reduce residual stress, and weaken subsequent processing deformation.

[0036] Based on a general inventive concept, the present invention also provides a Y-type connector forming mold for an aircraft fuselage, and the forming mold is applied to the above-mentioned forming method. The forming mold includes an inner ring mold 10 and an outer ring mold 20 used in conjunction with each other, and a core roller 30, a main roller 40, a guide roller 50 and a tapered roller 60 used in conjunction with the inner ring mold 10 and the outer ring mold 20. Specifically, in one embodiment, the inner ring mold 10 is a split structure, and the inner ring mold 10 includes a plurality of sections of detachably connected circular rings 110, and the plurality of sections of the circular rings are detachably connected through a connecting key 120, and are connected to the outer ring mold through a connecting piece 130 to prevent circumferential displacement. In one embodiment, the inner ring mold is composed of 4 arcs. Of course, it can also be a 3-section or 2-section circular ring. Preferably, the two ends of the connecting key 120 are connected to two adjacent circular rings 110, and one end of the connecting key 120 is provided with a screw ejection hole 122, and a screw matching the screw ejection hole is provided at the corresponding position of the circular ring 110 to achieve a detachable connection. Of course, in other embodiments, other detachable connection methods such as snap connections may also be used.

[0037] In one embodiment, an induction heating device 70 is also included for performing online temperature compensation during the ring rolling process to achieve near-isothermal ring rolling.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows: the Y-type connector has a complex shape and a large size, generally greater than 2.8m, and has a thin wall thickness and weak rigidity. The prior art usually adopts an extrusion-drawing forming method, which is prone to deformation during the forming process, and precise forming and manufacturing is difficult, and the material utilization rate is generally around 10%.

[0039] In the present application, the annular die is used to constrain the special-shaped ring rolling. During the ring rolling forming, the blank is gradually filled and formed in the cavity composed of the annular die and the core roller. The obtained special-shaped ring forging has an accurate shape. The cross section of the special-shaped ring forging is a double Y-shaped structure that is symmetrical and connected in one piece, and the double Y-shaped structure is connected by a shorter branch. Since the cross section of the special-shaped ring forging is a symmetrical structure, the axial load can be eliminated during the forming process, the forming stability is high, and one-time precision ring rolling forming can achieve one mold six pieces, which can greatly improve the manufacturing efficiency; the special-shaped ring forging is filled and formed in the cavity composed of the annular die and the core roller, and the special-shaped ring forging is placed in the annular die again after the solid solution heat treatment for ring rolling correction and residual stress reduction, with high forming accuracy, unilateral margin of 3-5mm, and material utilization rate of about 25%, which is doubled compared with the conventional "extrusion + bending" process; the annular die is used for special-shaped ring rolling, and the material extends and fills in the closed cavity to form a multi-directional streamline, and the obtained special-shaped ring forging has stable and reliable performance. Moreover, ring rolling is a kind of local continuous progressive deformation, which requires small equipment tonnage capacity and low cost.

[0040] In addition, the ring rolling method is adopted to constrain the ring die, and the temperature field during the ring rolling process is controlled by the online induction heating system. The rheological field and temperature field are controllable, the ring size is consistent with the ring die, and the forming accuracy is high. The inner ring die is a split structure, and the inner ring die includes multiple sections of detachably connected rings, so that the multiple sections of the inner ring die can be disassembled along the circumferential direction to achieve smooth demoulding of the special-shaped ring forging.

Claims

1. A method for forming a Y-shaped connector of an aircraft fuselage, characterized in that: The following steps are involved: preparing a ring-shaped blank; The circular ring blank is subjected to precision special-shaped ring rolling by using a ring die to obtain a special-shaped ring forging, wherein the cross section of the special-shaped ring forging is a double Y-shaped structure that is symmetrical and connected as one, and the double Y-shaped structure is connected by a shorter branch; The special-shaped ring forging is taken out from the annular die, and two circular ring pieces with Y-shaped cross sections are obtained by axial symmetry cutting. Each circular ring piece is then roughly machined and divided into three sections, obtaining a total of six Y-shaped connectors with the same shape and size.

2. A method for forming a Y-shaped connector for an aircraft fuselage according to claim 1, characterized in that: After the special-shaped ring forging is taken out from the annular die, the method further includes: heat treating the special-shaped ring forging, and after the heat treatment, putting the special-shaped ring forging into the annular die again for ring rolling and shaping.

3. The method for forming a Y-shaped connector of an aircraft fuselage according to claim 1, characterized in that: The process of precision profiled ring rolling of a ring-shaped blank using a ring die includes the following steps: The circular ring-shaped blank is placed in the ring mold at room temperature, heated to the forging temperature along with the ring mold, and then lifted out of the ring mold to the ring rolling machine for precision ring rolling to fill the cavity with the blank to obtain a double Y-shaped special-shaped ring forging structure with a symmetrical cross-section.

4. A method for forming a Y-shaped connector for an aircraft fuselage according to claim 3, characterized in that: Near-isothermal ring rolling is achieved by online temperature supplementation through induction heating device.

5. The method for forming a Y-shaped connector of an aircraft fuselage according to claim 3, characterized in that: The annular die comprises an inner ring die and an outer ring die which are used together. After the precision ring rolling, air cooling is first performed to separate the special-shaped ring forging from the annular die and form a gap. When demolding, the inner ring die and the special-shaped ring forging are taken out as a whole along the axial direction.

6. A method for forming a Y-shaped connector for an aircraft fuselage according to claim 5, characterized in that: The inner ring die is a split structure, and the inner ring die comprises multiple sections of detachably connected circular rings. After demoulding, the multiple sections of circular rings of the inner ring die are disassembled along the circumferential direction to take out the special-shaped ring forging.

7. The method for forming a Y-shaped connector of an aircraft fuselage according to claim 1, characterized in that: The annular blank is made of aluminum alloy or titanium alloy.

8. The method for forming a Y-shaped connector of an aircraft fuselage according to claim 1, characterized in that: The preparation of the ring-shaped blank comprises the following steps: Multi-directional forging: The ingot is heated to a preset temperature, and multi-directionally forged to obtain a solid cylindrical ingot, and a hole is punched in the center of the solid cylindrical ingot to obtain a hollow cylindrical ingot; Horse rack expansion: The hollow cylindrical blank is expanded by the horse rack process to obtain a rectangular cross-section ring blank; Rectangular ring rolling: Ring rolling technology is used to reduce the wall thickness, height and diameter of rectangular cross-section ring blanks; Car skin: The rectangular ring is rolled into a blank and machined to obtain a circular ring blank that meets the size requirements.

9. A Y-shaped connector forming die for an aircraft fuselage, characterized in that: The forming mold is applied to the forming method described in any one of claims 1 to 8, and the forming mold includes an inner ring mold and an outer ring mold used in conjunction with each other, a core roller, a main roller, a guide roller and a cone roller used in conjunction with the inner ring mold and the outer ring mold. The inner ring mold is a split structure, including multiple sections of detachably connected circular rings, and the multiple sections of the circular rings are detachably connected by connecting keys, and each section of the circular ring is connected to the outer ring mold through a connecting piece.

10. The aircraft fuselage Y-shaped connector forming die according to claim 9, characterized in that: It also includes an induction heating device for online temperature compensation during the ring rolling process to achieve near-isothermal ring rolling.

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