CN113403557B

CN113403557B - Forming method of aluminum alloy rear bottom and top cover component

Info

Publication number: CN113403557B
Application number: CN202110689639.5A
Authority: CN
Inventors: 湛利华; 余汶芳; 徐永谦
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2022-01-11
Anticipated expiration: 2041-06-22
Also published as: CN113403557A

Abstract

The invention provides a method for forming an aluminum alloy rear bottom cover component. The aluminum alloy rear floor top member having one or more raised apertures, the method comprising the steps of: step one, blanking; step two, flat plate stamping; step three, solution treatment; step four, creep aging forming. The invention adopts the composite process of stamping and creep aging forming to form the rear bottom and top cover with the convex hole, thereby not only solving the problems of low forming precision and the like of the stamping process, but also overcoming the defect that the creep aging process is difficult to form a large-curvature member. The invention has the advantages of high forming precision, good process repeatability, low residual stress, good dimensional stability and the like.

Description

Forming method of aluminum alloy rear bottom and top cover component

Technical Field

The invention belongs to the field of forming of aluminum alloy top cover components, and particularly relates to a forming method of an aluminum alloy rear bottom top cover component.

Background

The creep aging forming technology is a technology which is produced for solving the problem of high-performance and high-precision manufacturing of large complex integral components of aerospace, has the advantages of high forming precision, low residual stress, good process repeatability and the like, and is successfully applied to manufacturing of aerospace structural components such as upper and lower skins of airplane wings and the like.

The large-scale top cover with the convex holes and the small flanging holes at the periphery of the large-scale top cover with the large holes at the middle part is a main structure component of a fuel storage tank of an aerospace carrier rocket, and the traditional forming method of the component is punch forming.

The carrier rocket propellant storage tank comprises structural components such as a front bottom top cover, a rear bottom top cover and the like, the curvature and the chord height of the front bottom top cover are small, the creep aging forming technology with the characteristic of forming and forming collaborative manufacturing can well realize the integrated forming of the front bottom top cover, the section line of the rear bottom top cover in the radial direction is formed by connecting two elliptic curves, the curvature change and the chord height are large, when the rear bottom top cover is formed by simply applying the creep aging forming technology, the component cannot be deformed to a preset shape under the action of external force, and after the external force is unloaded and rebounds, the component cannot meet the requirement on the precision of the molded surface.

In addition, the die is a tool required by creep aging molding, and in the existing creep aging die equipment technology, one set of die can only mold a component with a certain fixed shape and size, but cannot realize the production of components with various specifications. The number, the size and the position of the convex holes related to the components with the convex holes of different specifications are different, and the corresponding design of the creep aging forming device capable of forming the components with various specifications has important significance for reducing the production cost.

Therefore, in order to solve the above problems, there is a need in the art for a new apparatus and method for forming an aluminum alloy rear undercover member with a protruding hole.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides a stamping creep composite forming method capable of realizing high-performance and high-precision forming of a large-size rear bottom and top cover with a convex hole.

Accordingly, the present invention provides a method of forming an aluminum alloy rear floor top member with one or more raised apertures, the method comprising the steps of:

step one, blanking;

step two, flat plate stamping;

step three, solution treatment;

step four, creep aging forming.

In one embodiment, in the first step, a planar development of the component is obtained, and then the component blank is cut according to the size of the planar development; in the second step, the plate stamping comprises the step of performing local preforming on the component blank obtained in the first step, namely performing preforming on the positions of the convex holes, wherein the convex holes comprise a central hole which is a large hole in the middle of the top cover component and peripheral flanging holes which are peripheral holes; in the third step, the preformed component in the second step is rapidly cooled after being heated and kept warm in the solution furnace for a period of time, the transfer time of the component from the solution furnace to the cooling device is within 30s, and the second phase can be fully dissolved into the solid solution at the high temperature of the solution treatment.

In one embodiment, in step four, the creep age forming comprises the following steps:

b, positioning and placing the plates: placing the aluminum alloy plate which is subjected to solution treatment and provided with a central hole and peripheral holes on the mold surface, so that the central point of the central hole of the aluminum alloy plate and the central point of the mold main body are on the same vertical line, and the projection of the peripheral holes of the aluminum alloy plate on the mold surface falls on the connecting line of the central point of the mold main body and the central point of the concave hole of the mold;

step C, applying an external load: gradually attaching the aluminum alloy plate to the molded surface of the mold by using a vacuum loading or mechanical loading method, and enabling peripheral holes of the aluminum alloy plate, namely component convex holes, to fall into the concave holes of the mold;

step D, creep aging: placing the aluminum alloy top cover component raw material and the die into an autoclave together, and enabling the aluminum alloy material to generate plastic flow under certain temperature, pressure and time;

e, unloading the external load: and (4) removing the external load to enable the aluminum alloy top cover member to rebound, so as to obtain the aluminum alloy top cover member with the convex hole, which meets the target profile precision.

In a specific embodiment, in the fourth step, the creep age forming comprises using a forming device of an aluminum alloy roof member with a convex hole, the forming device comprises a die main body (1), an embedded ring (4) and a lifting lug bolt (6), the die main body (1) comprises a die main body forming surface (11) recessed downwards, a top plate (12) arranged at the periphery of the die main body forming surface (11), a positioning part A (15), an annular groove (16) and a supporting structure for supporting the die main body forming surface (11) and the top plate (12), the annular groove (16) is recessed downwards from the upper surface of the die main body forming surface (11), the annular groove (16) is used for the embedded ring (4) to be arranged in an embedded manner, the positioning part A (15) is arranged in a structure protruding or recessed radially at least at a certain position on the inner ring or the outer ring of the annular groove for positioning the embedded ring (4), the embedded ring (4) comprises an embedded ring forming surface (41), one or more concave holes (42) matched with the convex holes of the aluminum alloy top cover component, a positioning part B (43) which is arranged at least at a certain position on an inner ring or an outer ring of the embedded ring (4) and is radially recessed or protruded for being matched and positioned with the positioning part A (15), and a first threaded hole (44) which is arranged on the embedded ring forming surface (41) and is used for screwing a lifting lug bolt (6); the mould at least comprises a mould main body forming surface (11) and an embedded ring forming surface (41) which jointly form a mould surface (3) of the forming device; and the molding method in the fourth step further comprises the step A before the step B;

step A, replacing or determining an inlaid ring: the correct embedded ring is replaced or determined according to the model of the target component, namely according to the number, the size and the position of the convex holes on the target component.

In one specific embodiment, the positioning component a (15) is a positioning block which is arranged at the lower part of the annular groove (16) and is used for positioning the embedded ring (4), the positioning component B (43) is a positioning groove which is arranged at the lower part of the embedded ring (4) and is used for matching and positioning with the positioning block; preferably, the positioning block (15) is a V-shaped positioning block, and the positioning groove is a V-shaped positioning groove; the first threaded holes (44) are more than three and are circumferentially and uniformly distributed on the embedded ring (4), and preferably, each threaded hole is equal to the distance between the inner ring and the outer ring of the embedded ring.

In a specific embodiment, the annular groove (16) is a sunken groove structure arranged on the die body, and the concave hole (42) is a through hole structure arranged on the embedded ring (4); a gap is formed between the die main body (1) and the embedding ring (4), the matching system is in clearance fit, and the preferred matching gap is smaller than 1 mm; the supporting structure comprises side plates (13) vertically arranged at the periphery of the mould main body and a clamping plate (18) used for connecting the side plates, and hollow holes (20) used for reducing the weight of the mould are formed in the side plates and the clamping plate; preferably, the positioning component A (15) is arranged at more than two circumferential different positions of the annular groove (16), the positioning component B (43) is arranged at more than two circumferential different positions of the embedded ring (4), and preferably, the plurality of positioning components A (15) and the plurality of positioning components B (43) are uniformly arranged in the circumferential direction.

In one specific embodiment, the forming device further comprises an insert (2) matched with one or more concave holes (42), and a positioning component C (45) is radially arranged on at least one position of one concave hole in a protruding or concave mode, the insert (2) comprises an insert forming surface (21), a positioning component D (22) which is radially arranged on one position of the insert in a protruding or concave mode and used for matching and positioning with the positioning component C (45), and a second threaded hole (23) which is arranged on the insert forming surface (21) and used for screwing in an ear bolt (6); the die main body molding surface (11), the insert ring molding surface (41) and the insert molding surface (21) of a part of inserts jointly form a die molding surface (3) of the molding device; preferably, the positioning component C (45) is a V-shaped block, the V-shaped block is arranged at the lower part of the concave hole, the positioning component D (22) is a V-shaped groove, and the V-shaped groove is arranged at the lower part of the insert; preferably, the second threaded hole (23) is arranged at the center of the insert molding surface (21), the positioning parts C (45) are arranged at more than two positions in the circumferential direction of the concave hole, the positioning parts D (22) are arranged at more than two positions in the circumferential direction of the insert, and preferably, the plurality of positioning parts C (45) and the plurality of positioning parts D (22) are uniformly arranged in the circumferential direction; a forming fillet (46) matched with an arc transition angle of the convex hole of the aluminum alloy top cover member is further arranged at the concave hole (42) of the embedding ring (4), and an embedding block fillet (24) matched with the forming fillet (46) is arranged between the side surface of the embedding block (2) and the embedding block forming surface (21); preferably, the method further comprises designing a mold matched with the target aluminum alloy top cover member through computer simulation before the step A.

In a specific embodiment, the die design comprises the steps of firstly, carrying out component forming finite element simulation and die profile springback compensation by using a computer to obtain a final die profile, then carrying out plane expansion on a target aluminum alloy top cover component and the die profile to obtain a plane expansion diagram of the component and the die profile, wherein the position of a central point of a concave hole or an insert is the position of the central point of a convex hole after the component with the convex hole is expanded; and the width of the embedding ring is determined according to the diameter of the convex hole of the aluminum alloy top cover component.

In a specific embodiment, according to the type of the aluminum alloy top cover component, as many concave holes as possible are formed in one embedding ring, and partial concave holes are filled with the embedding blocks during forming, so that the same embedding ring can form as many different types of components with convex holes as possible.

In one embodiment, step a further comprises replacing or determining the insert, that is, replacing or determining the correct insert ring and insert according to the number, size and position of the convex holes of the target member, so that the number, size and position of the concave holes on the die which are not filled with the insert are consistent with the convex holes of the target aluminum alloy top cover member; and D, forming the top cover component with the convex holes with different thicknesses by controlling creep aging process parameters including temperature, pressure and time.

Compared with the prior art, the invention has at least the following effects:

1) the invention adopts the composite process of stamping and creep aging forming to form the rear bottom and top cover with the convex hole, thereby not only solving the problems of low forming precision and the like of the stamping process, but also overcoming the defect that the creep aging process is difficult to form a large-curvature member. The invention has the advantages of high forming precision, good process repeatability, low residual stress, good dimensional stability and the like.

2) Meanwhile, the invention fully utilizes the material characteristics of different heat treatment states, realizes local and integral molding step by step, and utilizes the heat treatment process to synchronously strengthen the performance, thereby realizing the high-efficiency integrated manufacturing of the rear bottom and top cover with the convex hole and shortening the manufacturing period.

3) According to the creep aging forming device, the modular creep aging forming die is adopted, the die insert ring and the insert are correspondingly replaced and adjusted according to the size and position conditions of the convex hole in the component, and the forming of the top cover components of different models is realized by adjusting the technological parameters of creep aging, so that the flexibility of convex hole forming is improved, the problem of compatibility of the creep forming die for different convex hole characteristics is solved, namely, one set of creep forming die can realize the forming of components with different structural characteristics, and the production cost is greatly reduced. The aluminum alloy rear bottom and top cover member prepared by the forming method has the advantages of high shape and size precision, short processing period and low production cost.

Drawings

In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention will become apparent from the following detailed description of the invention which refers to the accompanying drawings.

FIG. 1 is a schematic view of a creep age forming apparatus for an aluminum alloy rear undercover member;

FIG. 2 is a schematic view of a creep age forming apparatus in another state;

FIG. 3 is an exploded view of a creep age forming apparatus;

FIG. 4 is a cross-sectional view of a creep age forming apparatus;

FIG. 5 is a schematic structural view of a mold body;

FIG. 6 is a schematic illustration of an insert;

FIG. 7 is a schematic view of a damascene ring;

FIG. 8 is a three-dimensional simulation of a creep age forming apparatus for an aluminum alloy rear undercover member;

FIG. 9 is a pictorial view of a creep age forming apparatus for an aluminum alloy rear floor cap member;

FIG. 10 is a pictorial illustration of the physical effect of an aluminum alloy rear bottom cap member formed using the apparatus of the present invention;

FIG. 11 is a flow chart of a method of forming an aluminum alloy rear floor cap member in accordance with the present invention;

FIG. 12 is a diagram of a blank prior to forming a sheet of an aluminum alloy rear undercover member in accordance with the present invention;

FIG. 13 is a schematic view of the member of FIG. 12 after flat stamping;

FIG. 14 is a schematic representation of the component of FIG. 13 after creep age forming.

Wherein, 1-a mold body; 2-an insert; 3-molding surface of the mold; 4-embedding a ring; 6-a lug bolt; 11-a mould body forming surface; 12-a top plate; 13-side plate; 14-a cushion block; 15-positioning part a; 16-an annular groove; 17-a positioning column; 18-a card board; 19-a base plate; 20-hollow holes; 21-insert molding surface; 22-positioning means D; 23-a second threaded hole; 24-insert fillet; 41-embedding ring forming surface; 42-concave holes; 43-positioning part B; 44-a first threaded hole; 45-positioning part C; 46-forming a fillet; 2.1-a first insert; 2.2-second insert; 2.3-third insert.

Detailed Description

The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention and do not constitute a limitation of the invention.

Referring to fig. 11 to 14, the present invention provides a method for forming an aluminum alloy rear undercover member, and a flow chart thereof is shown in fig. 11. The incoming material related to the embodiment of the invention is O-state 2219 aluminum alloy.

The molding method comprises the following steps:

step one, blanking: firstly, obtaining a plane development view of a target aluminum alloy top cover component, and then cutting a component blank shown in the figure 12 by using water cutting equipment according to the plane development size;

step two, plate stamping: and the flat plate stamping is to perform local preforming on the component blank obtained in the step one, wherein the local forming of a large hole in the middle of the top cover component and the flanging forming of a flanging hole around the large hole are included. The method comprises the steps of firstly, taking three holes on the periphery of a blank as positioning holes, drawing a large hole in the middle of a component, then positioning the middle hole of the drawn component, and flanging the three holes on the periphery. A schematic of the flat stamped component is shown in fig. 13.

Step three, solution treatment: the purpose of the solution treatment is to dissolve the second phase into the solid solution sufficiently and then to cool it rapidly to obtain a supersaturated solid solution in preparation for subsequent creep age forming. The equipment used in the solution treatment test is a roller-hearth solution furnace, and the technological parameters are as follows: the temperature is kept at 535 ℃ for 70 minutes, then water cooling is carried out immediately, and the transfer time of the component from the solution furnace to the water cooling device is less than 30 s.

Step four, creep aging forming: in order to obtain the rear bottom cover component with the convex hole and the target profile precision, creep aging forming is carried out on the component after solution treatment. The steps of creep age forming are as follows:

and B, positioning and placing the plates. Placing an aluminum alloy plate provided with a central hole and peripheral holes on the molded surface of the mold, so that the central point of the central hole of the aluminum alloy plate and the central point of the mold main body are on the same vertical line, and the projection of the peripheral holes of the aluminum alloy plate on the molded surface of the mold falls on the connecting line of the central point of the mold main body and the central point of the concave hole of the mold;

and step C, vacuum loading. And integrally wrapping the component by using an air felt, covering the surface of the mold by using a vacuum bag, exhausting air in the bag after sealing is finished, maintaining the pressure for 10 minutes, and gradually attaching the component to the molded surface of the mold.

And D, creep aging. And pushing the component and the tooling thereof into the autoclave, and arranging thermocouples on the component and the tooling to detect the temperature condition of each area in the molding process. The creep age forming process comprises the following steps: keeping the air pressure in the autoclave at 2MPa, the aging temperature at 170 ℃ and the heat preservation time at 12 h.

And E, unloading the external load, and discharging and finishing. And after the aging forming is finished, taking out the test component and the tooling thereof, removing the vacuum bag and unloading the vacuum pressure.

A schematic of the creep age formed component is shown in FIG. 14.

In addition, the invention also provides a forming device in the fourth step of the forming method.

Referring to fig. 1 to 4, the apparatus for creep age forming provided by the invention comprises a die body 1, an insert ring 4 embedded in an annular groove of the die body, an insert 2 embedded in the insert ring, and an eye bolt 6.

Referring to fig. 5 to 7, the mold main body comprises a mold main body molding surface 11, a top plate 12 arranged on the periphery of the mold main body molding surface, a side plate 13 positioned on the periphery of the mold main body, a clamping plate 18 connected with the side plate, a bottom plate 19 at the bottom of the mold main body, and a cushion block 14 arranged below the bottom plate for increasing the heat transfer area of the bottom plate and improving the ventilation rate, wherein an annular groove 16 and two positioning blocks 15 which are symmetrically distributed in the annular groove for positioning are arranged in the mold main body molding surface, and two positioning columns 17 which are symmetrical to each other are welded above the top plate; the embedded ring comprises an embedded ring forming surface 41, a through hole formed in the embedded ring, four threaded holes with the same diameter, uniform distribution and the same distance with the inner diameter and the outer diameter of the embedded ring, and a V-shaped block arranged in the through hole; the insert comprises an insert forming surface 21, two uniform and symmetrical V-shaped grooves at the bottom of the insert, a threaded hole 23 arranged at the center of the insert, and an insert round angle 24 with a transition effect between the side surface of the insert and the forming surface.

The die body 1, the embedding ring 4 and the insert 2 are separate parts, the embedding ring 4 is placed in an annular groove 16 in the die body, and the insert is embedded in a through hole in the embedding ring. The die main body molding surface 11, the insert ring molding surface 41 and the insert molding surface 21 form a die molding surface 3.

In the embodiment, the positions of the insert 2 and the insert ring 4 are determined according to the positions and the sizes of the convex holes of the components, and the distance from the center point of the insert to the center position of the die is obtained by performing plane expansion calculation on the top cover component and the die profile, wherein the distance from the center point of the insert to the center position of the die is 450mm, and the width of the insert ring is 260 mm. The die body 1 and the embedding ring 4 are in clearance fit, the outer circle of the embedding ring is matched with the die body in a base hole mode, the inner circle of the embedding ring is matched with the die body in a base shaft mode, and the clearance between the inner circle of the embedding ring and the die body is smaller than 1 mm.

Referring to fig. 4, in order to realize uniform heat transfer of the mold, reduce the weight of the mold and the manufacturing cost of the mold, a plurality of vent holes are formed in the side plate, the clamping plate and the bottom plate, the total area of the vent holes of the side plate is larger than 60% of the total area of the side plate, the total area of the vent holes of the clamping plate is larger than 30% of the total area of the clamping plate, and the total area of the vent holes of the bottom plate is larger than 65% of the total area of the bottom plate.

Referring to fig. 7, the bottom of the embedded ring 4 is provided with two positioning grooves matched with the positioning blocks 15, the top of the concave hole 42 is provided with four molding fillets 46 with the radius equal to that of the transition fillet of the convex hole of the component, and the bottom of the embedded ring is provided with a chamfer, so that the embedded ring can smoothly enter the annular groove when being placed, the placing speed of the embedded ring is improved, and the chamfer size is C5.

In this embodiment, a vacuum loading method is used to form a large top cover member with a convex hole, and the specific steps are as follows:

step A, module replacement: and screwing the lug bolt into a threaded hole in the insert 2.1 shown in the figure 1, and using external lifting force to act on the lug bolt to take away the insert 2.1, reserving the insert 2.2 and the insert 2.3 shown in the figure 1 and also reserving the insert ring 4, and taking away all the lug bolts in the figure 1 to obtain the creep age forming die with two die concave holes shown in the figure 2.

Step B, placing the plate: placing a circular plate with a large hole in the middle and two small holes in the periphery on the molded surface of a mold, adjusting the relative positions of the plate and the mold to ensure that the center point of the large hole in the middle of the plate is superposed with the projection of the center point of the main body of the mold on the horizontal plane, and ensuring that the projections of the two small holes in the periphery on the molded surface of the mold fall on the connecting line of the center point of the main body of the mold and the center point of the concave hole of the mold.

Step C, applying an external load: and integrally wrapping the component by using an air felt, covering the surface of the mold by using a vacuum bag, exhausting air in the bag after sealing is finished, maintaining the pressure for 5-20 minutes, gradually attaching the component to the molded surface of the mold, and enabling the convex hole of the component to fall into the concave hole of the mold.

Step D, creep aging stage: and pushing the component and the tooling thereof into the autoclave, and arranging thermocouples on the component and the tooling to detect the temperature condition of each area in the molding process. The creep age forming process comprises the following steps: keeping the air pressure in the tank at 1.5-2MPa, the aging temperature at 150-.

Step E, an unloading stage: and after the creep aging stage is finished, taking out the test component and the tooling thereof, removing the vacuum bag, unloading the vacuum pressure, and rebounding the component to obtain the top cover component with the convex hole, which meets the target profile precision.

Fig. 10 is a real view of the large-sized lid member with protruding holes obtained in this embodiment.

In the invention, because the first threaded hole and the second threaded hole are small in size, the forming precision of the aluminum alloy top cover component cannot be influenced by the existence of the threaded holes during creep age forming, and M12 bolts are selected as the corresponding lifting lug bolts, namely the diameter of the bolts is 12 mm.

In the invention, the embedding ring and the embedding block can be replaced correspondingly according to the number, the size and the position of the convex holes on the target component.

Preferably, be clearance fit between mould main part and the ring of inlaying to guarantee that both clearances are less than 1mm, in order to ensure that the ring of inlaying changes conveniently, and do not influence the shaping precision of component.

Preferably, the inner part of the mosaic ring is provided with four threaded holes with the same diameter and uniform distribution, and the distances between the threaded holes and the outer diameter of the mosaic ring are equal; the insert is characterized in that a threaded hole is formed in the center of the insert and used for connecting the lug bolt, when the insert ring or the insert is replaced, external lifting force acts on the lug bolt firstly, and then the lug bolt acts on the insert ring and the insert, so that the effect of convenient replacement is achieved.

Preferably, two symmetrical positioning blocks are arranged in the annular groove, the bottom of the embedding ring is provided with corresponding positioning grooves, and the positioning blocks are matched with the positioning grooves and used for positioning the embedding ring in the placing process and preventing the embedding ring from moving under the action of an external load in the using process so as to avoid the profile precision and the convex hole position precision error of the component.

Preferably, the top of shrinkage pool is provided with the shaping fillet, when the shrinkage pool department does not lay and inserts, this shrinkage pool is the mould shrinkage pool to hold the component bulge, and the transition department of component bulge and component profile is with certain fillet transition, for the shaping precision of realizing the component bulge, the radius of shaping fillet equals with the transition fillet radius of component bulge.

Preferably, the concave hole in be provided with two symmetrical V type pieces insert the bottom open have with V type piece assorted V type groove to realize that the location of inserting is accurate, and prevent that insert from taking place rotary motion in creep age forming process.

Preferably, the bottom of the embedding ring is provided with a chamfer so that the embedding ring can smoothly enter the annular groove when the embedding ring is placed, and the placing speed of the embedding ring is improved.

Preferably, the side plates, the clamping plate and the bottom plate are all provided with vent holes so as to realize uniform heat transfer of the die, reduce the weight of the die and reduce the manufacturing cost of the die.

Preferably, an insert fillet is arranged between the side surface of the insert and the insert molding surface, and the size of the fillet is consistent with that of the fillet molded in the insert ring and is also equal to the radius of the transition fillet corresponding to the convex hole of the component to be molded.

Preferably, the bottom plate is provided with a cushion block at the lower side thereof so as to increase the contact area between the mold bottom plate and air, improve the heat transfer and ventilation rate of the mold, increase the heat distribution uniformity of the mold and improve the molding precision of the component.

According to the invention, the embedding rings (4) are embedded in the annular groove (16), so that different embedding rings (4) can be correspondingly molded into different aluminum alloy top cover components. Furthermore, the invention also provides a plurality of concave holes (42) on the embedded ring (4) and an embedded block (2) matched with the concave holes (42), so that each embedded ring (4) in the forming device can correspondingly form a plurality of different aluminum alloy top cover components; the cost savings of the forming die are further increased. Because the carrier rocket is a space vehicle composed of multiple stages of rockets, each stage of rocket is provided with propellant storage tanks with different types, each propellant storage tank comprises a front bottom top cover and a rear bottom top cover, and parameters such as the number, the position, the size, the thickness of components and the like of convex holes on the front bottom top cover and the rear bottom top cover with different types are different, so that the cost of the mold is overhigh when each set of aluminum alloy top cover component corresponds to one set of forming mold, and the forming cost of the aluminum alloy top cover component is overhigh. Therefore, the forming device provided by the invention can adapt to the forming of different aluminum alloy top cover components with convex holes, thereby obviously saving the forming cost.

In addition, the invention solves the problem of the position precision of the convex hole of the component by the computer simulation design of the die.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions and substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims

1. A method of forming an aluminum alloy rear floor top member having one or more raised apertures, said method comprising the steps of:

step one, blanking;

step two, flat plate stamping;

step three, solution treatment;

step four, creep aging forming;

in the first step, firstly, a plane development drawing of the component is obtained, and then, a component blank is cut according to the size of the plane development drawing; in the second step, the plate stamping comprises the step of performing local preforming on the component blank obtained in the first step, namely performing preforming on the positions of the convex holes, wherein the convex holes comprise a central hole which is a large hole in the middle of the top cover component and peripheral flanging holes which are peripheral holes; in the third step, the pre-formed component in the second step is rapidly cooled after being heated and kept warm in the solution furnace for a period of time, the transfer time of the component from the solution furnace to the cooling device is within 30s, and the second phase can be fully dissolved into the solid solution at the high temperature of the solution treatment; in the fourth step, the creep age forming comprises using a forming device of an aluminum alloy top cover component with a convex hole, the forming device comprises a die main body (1), an embedded ring (4) and a lifting lug bolt (6), the die main body (1) comprises a die main body forming surface (11) recessed downwards, a top plate (12) arranged at the periphery of the die main body forming surface (11), a positioning part A (15), an annular groove (16) and a supporting structure for supporting the die main body forming surface (11) and the top plate (12), the annular groove (16) is recessed downwards from the upper surface of the die main body forming surface (11), the annular groove (16) is used for the embedded ring (4) to be embedded and arranged in, the positioning part A (15) is arranged in a structure which at least one position on the inner ring or the outer ring of the annular groove is radially protruded or recessed so as to be used for positioning the embedded ring (4), the embedded ring (4) comprises an embedded ring forming surface (41), one or more concave holes (42) matched with the convex holes of the aluminum alloy top cover component, a positioning part B (43) which is arranged at least at a certain position on an inner ring or an outer ring of the embedded ring (4) and is radially recessed or protruded for being matched and positioned with the positioning part A (15), and a first threaded hole (44) which is arranged on the embedded ring forming surface (41) and is used for screwing a lifting lug bolt (6); the mould at least comprises a mould main body forming surface (11) and an embedded ring forming surface (41) which jointly form a mould surface (3) of the forming device;

and in the fourth step, the creep age forming comprises the following steps:

step A, replacing or determining an inlaid ring: correspondingly replacing or determining a correct embedding ring according to the model of the target component, namely according to the number, the size and the position of the convex holes on the target component;

2. The molding method according to claim 1, wherein the positioning member a (15) is a positioning block provided at a lower portion of the annular groove (16) for positioning the insert ring (4), and the positioning member B (43) is a positioning groove provided at a lower portion of the insert ring (4) for mating positioning with the positioning block.

3. The molding method according to claim 2, wherein the positioning block (15) is a V-shaped positioning block, and the positioning groove is a V-shaped positioning groove; the number of the first threaded holes (44) is more than three, and the first threaded holes are uniformly distributed on the embedding ring (4) in the circumferential direction.

4. The molding method according to claim 1, wherein the annular groove (16) is a sink groove structure provided on the mold body, and the recessed hole (42) is a through hole structure provided on the insert ring (4); a gap is formed between the die main body (1) and the embedding ring (4), and the matching system is in clearance fit; the supporting structure comprises side plates (13) vertically arranged at the peripheral positions of the die main body and clamping plates (18) used for connecting the side plates, and hollow holes (20) used for reducing the weight of the die are formed in the side plates and the clamping plates.

5. Moulding method according to claim 4, characterized in that the fit clearance between the mould body (1) and the inlay ring (4) is less than 1 mm.

6. The molding method according to claim 5, wherein the positioning member A (15) is provided at two or more circumferentially different positions of the annular groove (16), the positioning member B (43) is provided at two or more circumferentially different positions of the insert ring (4), and the plurality of positioning members A (15) and the plurality of positioning members B (43) are all circumferentially uniformly provided.

7. The molding method according to claim 1, wherein the molding apparatus further comprises an insert (2) disposed in mating relation with one or more pockets (42), and a positioning member C (45) is disposed in a radially protruding or recessed relation at least at a position of one pocket, the insert (2) comprising an insert molding surface (21), a positioning member D (22) disposed in a radially recessed or protruding relation at a position of the insert and adapted to be positioned in mating relation with the positioning member C (45), and a second threaded hole (23) disposed in the insert molding surface (21) and adapted to be threaded into the lug bolt (6); the die main body molding surface (11), the insert ring molding surface (41) and the insert molding surface (21) of a part of inserts jointly form a die molding surface (3) of the molding device; the positioning component C (45) is a V-shaped block, the V-shaped block is arranged at the lower part of the concave hole, the positioning component D (22) is a V-shaped groove, and the V-shaped groove is arranged at the lower part of the insert; the second threaded hole (23) is formed in the center of the insert forming surface (21), the positioning parts C (45) are arranged at more than two different positions in the circumferential direction of the concave hole, the positioning parts D (22) are arranged at more than two different positions in the circumferential direction of the insert, and the plurality of positioning parts C (45) and the plurality of positioning parts D (22) are uniformly arranged in the circumferential direction; a forming fillet (46) matched with an arc transition angle of the convex hole of the aluminum alloy top cover member is further arranged at the concave hole (42) of the embedding ring (4), and an embedding block fillet (24) matched with the forming fillet (46) is arranged between the side surface of the embedding block (2) and the embedding block forming surface (21); step A is also preceded by designing a mold matching the target aluminum alloy cap member by computer simulation.

8. The molding method according to claim 7, wherein the mold design comprises firstly using a computer to perform member molding finite element simulation and mold profile springback compensation to obtain a final mold profile, then performing planar expansion on the target aluminum alloy top cover member and the mold profile to obtain a planar expansion diagram of the member and the mold profile, wherein the position of the central point of the concave hole or the insert is the position of the central point of the convex hole after the member with the convex hole is expanded; and the width of the embedding ring is determined according to the diameter of the convex hole of the aluminum alloy top cover component.

9. The molding method according to claim 8, wherein, according to the type of the aluminum alloy top cover member, as many recesses as possible are provided in one insert ring, and a part of the recesses are filled with the inserts during molding, so that as many different types of components with convex holes as possible can be molded by the same insert ring.

10. The molding method according to any one of claims 1 to 6, wherein the step A further comprises replacing or determining the insert, namely replacing or determining the correct insert ring and insert according to the number, size and position of the convex holes of the target member, so that the number, size and position of the concave holes on the mold which are not filled with the insert are consistent with the convex holes of the target aluminum alloy top cover member; and D, forming the top cover component with the convex holes with different thicknesses by controlling creep aging process parameters including temperature, pressure and time.