Aerospace 2195 aluminum-lithium alloy profile extrusion die with asymmetric section

Abstract

The utility model discloses an extrusion die for an asymmetric-section 2195 aluminum-lithium alloy section for aerospace. The extrusion die is provided with a pre-deformation cavity, a flow guide cavity and a working belt, wherein the pre-deformation cavity is used for preliminarily deforming a blank towards the section of the section; the flow guide cavity is used for adjusting metal flow in different areas; the pre-deformation cavity and the flow guide cavity are arranged in a stepped mode in the direction of the working belt, the cavity walls of the flow guide cavity are provided with different offsets and flow guide inclination angles according to the section characteristics of the sectional materials and the flowing characteristics of metal, the purpose of directly extruding the straight sectional materials can be achieved through the working belt arranged in a two-stage mode, the product has good perpendicularity, the appropriate section size is obtained, and the production efficiency is improved. And the twisting defect is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of molds, in particular to an asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion mold for aerospace. Background Art

[0002] 2195 aluminum-lithium alloy is an aluminum alloy with aluminum as the main element and trace elements such as copper, lithium, magnesium, and zirconium added. It has broad application prospects in the aerospace field due to its low density, fatigue cracks that are not easy to expand, and good comprehensive mechanical properties. NASA used 2195 aluminum-lithium alloy for the first time when developing the external fuel tank of the "Endeavour" space shuttle. By replacing the original aluminum material, the structural weight of the cryogenic fuel tank was reduced by 3405kg, becoming a symbol of the substantial application of aluminum-lithium alloy. In addition, 2195 aluminum-lithium alloy is also used in the fuselage long stringers and floor beam profiles of the C919 large passenger aircraft, which can significantly reduce the structural weight while improving the structural stiffness.

[0003] Asymmetric cross-section profiles are widely used in aerospace equipment to bear or transfer loads. The profiles need to undergo rigorous verification and testing during the design and manufacturing process to ensure their performance and reliability. Asymmetric cross-section profiles for aerospace have the characteristics and difficulties of large-scale, integrated, lightweight, precise cross-sectional dimensions and geometric tolerances, uniform and high-quality organizational properties. The optimized design and material selection of this type of profile are of great significance to the performance and safety of aerospace equipment. Based on functional needs, the relevant technical indicators of the geometric and dimensional accuracy requirements of asymmetric cross-section profiles for aerospace must meet the high-precision or ultra-high-precision requirements of GB / T14846 "Dimensional Deviations of Aluminum and Aluminum Alloy Extruded Profiles".

[0004] Although the industry has achieved significant results in the research and application of 2195 aluminum-lithium alloy, there are still many deficiencies in the manufacturing and application of aerospace asymmetric cross-section profile products. For example, due to the influence of extrusion dies and process parameters, there are disadvantages such as high extrusion difficulty, uneven metal flow, uneven organizational properties, and low yield rate. These defects and disadvantages need to be improved in further research and application. Under the special service conditions in the aerospace field, asymmetric cross-section profile components require better comprehensive mechanical properties and dimensional accuracy.

[0005] like Figure 1 The figure shows a typical asymmetric cross-section profile for aerospace. According to the technical goal of lightweight, this type of component is generally made of 2195 aluminum-lithium alloy material, and its tensile strength is greater than 580MPa. Its plasticity is relatively lower than that of 6xxx aluminum alloy. This is because lithium and copper are added to 2195 aluminum-lithium alloy. These elements can enhance the strength of the alloy, but at the same time reduce the plasticity of the alloy.

[0006] At present, the processing of asymmetric cross-section profiles is mainly based on extrusion molding, and the formulation of the extrusion process directly affects the final forming of the profile product. Therefore, the influence of the extrusion die structure and the setting of extrusion process parameters on the extrusion forming structure and performance of the profile, as well as the precision forming of such components, has important theoretical and practical significance.

[0007] Reasonable design of die structure is the premise to ensure the forming quality of aluminum alloy profiles and extend the service life of the die. It is also the key to improve extrusion processing efficiency and reduce costs. It can not only improve the product quality, production efficiency and yield rate of extruded products, but also reduce the consumption of die steel and reduce production costs. Different die structures and extrusion process parameters will affect the flow of metal. During the extrusion process, the flow state of metal has always been very complex, which has a great influence on the surface quality, dimensional accuracy, mechanical properties and microstructure of the extruded products. Material properties, extrusion methods, billet and die preheating state, die structure, extrusion temperature and extrusion speed will affect the flow of metal, thereby affecting the quality of the profile.

[0008] Figure 1 The figure shows a typical asymmetric cross-section profile for aerospace applications. The profile has the following characteristics: the maximum circumscribed circle of the profile section is 138 mm, the maximum wall thickness is 40 mm, and it can be considered to be composed of a short flange, a long flange, and an L-shaped web with a reinforcement portion. Figure 1 The cross section of the profile shown is extremely asymmetric, the lengths of the short flange and the long flange of the profile are inconsistent, and the web between the two is also an L-shaped asymmetric structure with a reinforced part. This results in different amounts of metal flowing into different parts of the die hole on the same horizontal line at the same time when the profile is extruded, so it cannot ensure that the metal flow rate is the same on the same horizontal plane during extrusion.

[0009] Due to the extreme asymmetry of the profile cross section, the imbalance of metal flow rate during extrusion will cause the metal flow rate to be faster on the side of the profile with the reinforcement part; and the inconsistent lengths of the short and long flanges on the upper and lower sides of the profile will also cause the imbalance of metal flow rate during extrusion, making the metal flow rate of the lower long flange part faster. The profile will deflect in the lateral direction and twist in the circumferential direction, resulting in severe knife-shaped bending and twisting deformation, such as Figure 2 As shown. As a result, it is not easy to effectively straighten the profile through subsequent straightening operations to meet the technical requirements. Secondly, during extrusion, the profile product flows out of the die hole unbalancedly, and lateral deflection or circumferential torsion will cause the extruded profile to rub the discharge channel of the die system, causing die blockage, and production cannot continue, leading to serious production accidents. In addition, the alloy used in this profile used as an aviation structural material is 2195 aluminum-lithium alloy. The metal fluidity is much lower than that of 6xxx series aluminum alloys, and the extrusion performance is extremely poor, which increases the difficulty of its extrusion molding.

[0010] At present, during the extrusion process of asymmetric cross-section profiles for aerospace, the extruded and bent profiles are usually straightened. This processing method has the disadvantages of long process cycle and high equipment cost. Straightening of 2xxx aluminum-lithium alloys can easily lead to defects such as cracking, buckling, deformation, and material damage, which affect the performance of components and restrict the yield rate. In order to overcome the above shortcomings, it is necessary to make the extrusion die automatically correct during the extrusion process.

[0011] Usually, in order to achieve the purpose of automatic correction during the extrusion of asymmetric cross-sections, the metal flow rate balance is considered when designing the mold, and the profile section is designed to be symmetrical to reduce or eliminate lateral bending and twisting deformation during extrusion. In the later stage of part processing, the auxiliary short edge is mechanically removed. However, adding auxiliary short edges will greatly increase production costs, especially as aerospace aluminum alloy materials are expensive. For asymmetric cross-section profiles, the use of a manufacturing method without other processing methods has significant economic value.

[0012] In this case, the design and manufacture of the extrusion die plays a vital role in whether the geometric dimensions of the profile can meet the requirements of technical conditions or whether normal extrusion production can be achieved. Therefore, how to design a self-correcting extrusion die for asymmetric cross-section profiles through a reasonable die design scheme, and make the product have good verticality, obtain appropriate cross-sectional dimensions, and reduce twisting defects is a problem that needs to be solved in production practice. Utility Model Content

[0013] The purpose of the utility model is to address the deficiencies of the prior art and provide an asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die for aerospace use, so as to solve the problems of long process cycle, high preparation cost, easy defects and low yield in the current manufacturing of asymmetric cross-section profiles.

[0014] The utility model provides an asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die for aerospace, wherein the profile comprises a short flange, a long flange and an L-shaped web, wherein the short flange is vertically connected to the top of the L-shaped web, the long flange is parallel to the short flange and connected to one side of the bottom of the L-shaped web, and a reinforcement part is arranged on the other side of the L-shaped web. The extrusion die comprises:

[0015] The mold is a columnar structure with a circular cross-section; the mold is provided with a pre-deformation cavity for initial deformation of the blank, a guide cavity for guiding the uniform flow of the blank during extrusion, a working belt for ensuring the shape, size and surface quality of the extruded part, a die hole running through the mold, and an empty knife arranged at the discharge end of the mold to support the working belt; the pre-deformation cavity, the guide cavity, the die hole and the empty knife are all designed according to the size and shape of the profile.

[0016] Furthermore, the center position of the die hole is offset to the lower side and right side of the center position of the mold; the contour corners of the pre-deformation cavity, the guide cavity, the die hole and the empty knife are all transitioned through arcs, and their respective transverse cross-sectional contour lines and corresponding covering areas are different;

[0017] The transverse cross-sectional area of ​​the pre-deformation cavity is larger than the transverse cross-sectional area of ​​the guide cavity; the transverse cross-sectional contour line of the guide cavity is at least partially the same as the transverse cross-sectional contour line of the profile, and is larger than the area covered by the transverse cross-sectional contour line of the profile end.

[0018] Further, the guide cavity is composed of multiple sections of guide cavity walls, including: a first cavity wall of a short flange, a second cavity wall of a short flange, a third cavity wall of a short flange, a fourth cavity wall of a short flange, a fifth cavity wall of a short flange, a first cavity wall of a web, a first cavity wall of a long flange, a second cavity wall of a long flange, a third cavity wall of a long flange, a fourth cavity wall of a long flange, a fifth cavity wall of a long flange, a fourth cavity wall of a web, a third cavity wall of a web, and a second cavity wall of a web;

[0019] Among them, the outer contour lines of the first cavity wall of the short flange, the third cavity wall of the long flange, the fourth cavity wall of the long flange, the fifth cavity wall of the long flange, the fourth cavity wall of the web, the third cavity wall of the web, and the second cavity wall of the web are the same as the mold hole contours at their corresponding parts, and are offset to the outside of the mold as a whole, so that the covering area of ​​these seven transverse cross-sectional contour lines is larger than the area of ​​the mold hole.

[0020] Furthermore, the short flange first cavity wall, the short flange second cavity wall, the short flange third cavity wall, the short flange fourth cavity wall, and the short flange fifth cavity wall cooperate together to be responsible for the short flange extrusion molding process of the asymmetric cross-section profile;

[0021] The second cavity wall of the short flange, the third cavity wall of the short flange, the fourth cavity wall of the short flange, the fifth cavity wall of the short flange, the first cavity wall of the web, the first cavity wall of the long flange, and the second cavity wall of the long flange are offset to the outside of the mold and form a guide angle. The first cavity wall of the short flange is a guide cavity part without an inclination angle, and the cavity walls are connected by a transition of circular arc segments.

[0022] Furthermore, the first cavity wall of the long flange, the second cavity wall of the long flange, the third cavity wall of the long flange, the fourth cavity wall of the long flange, and the fifth cavity wall of the long flange cooperate together to be responsible for the extrusion molding process of the long flange of the profile;

[0023] The long-flange first cavity wall and the long-flange second cavity wall are offset toward the outside of the mold and form a guide angle. The long-flange third cavity wall, the long-flange fourth cavity wall and the long-flange fifth cavity wall are guide cavity parts without an angle, and each cavity wall is connected by a transition of circular arc segments.

[0024] Furthermore, the fourth cavity wall of the web, the third cavity wall of the web, the second cavity wall of the web and the first cavity wall of the web cooperate together to form the L-shaped web and its reinforcement part of the profile;

[0025] The first cavity wall of the web is offset to the outside of the mold and forms a guide angle. The fourth cavity wall of the web, the third cavity wall of the web and the second cavity wall of the web are guide cavity parts without an angle. The cavity walls are connected by arc segments.

[0026] Furthermore, the transverse cross-sectional contour line of the working belt is the same as the transverse cross-sectional contour line of the profile, and the working belt is divided into two parts: a primary working belt and a secondary working belt;

[0027] The first-level working belt is set up in such a way that it is added in full section at each cavity wall, and its shape is a closed loop that is completely identical to the cross-sectional shape of the profile; the second-level working belt is set up in such a way that a second-level working belt is added at the corresponding positions of a total of 6 sections, namely, the third cavity wall of the long flange, the fourth cavity wall of the long flange, the fifth cavity wall of the long flange, the fourth cavity wall of the web, the third cavity wall of the web, and the second cavity wall of the web, and its shape is an open loop that is identical to the cross-sectional shape of the corresponding section of the profile; the second-level working belt only increases the length of one side of the reinforced part in the third cavity wall section of the long flange, and is connected with the first-level working belt by means of a circular arc segment transition.

[0028] Furthermore, the empty knife is arranged in a concave shape on one side of the discharge end of the mold, and at least part of the transverse cross-sectional contour line is the same as the transverse cross-sectional contour line of the working belt, and the cross-sectional area is larger than the mold hole.

[0029] The utility model has the following beneficial effects: the utility model provides an aerospace asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die, which is provided with a pre-deformation cavity for initially deforming the blank to the profile cross section, a guide cavity for adjusting the metal flow in different regions, and a working belt for adjusting the extrusion speed of each part of the profile. The pre-deformation cavity and the guide cavity are arranged in a stepped manner in the direction of the working belt, and different offsets and guide angles are arranged on the walls of the guide cavity according to the cross-sectional characteristics of the profile and the metal flow characteristics. The two-stage working belt can achieve the purpose of directly extruding the straight profile, so that the product has a better verticality, obtains a suitable cross-sectional size, and reduces twisting defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a three-dimensional schematic diagram of an asymmetric cross-section 2195 aluminum-lithium alloy profile for aerospace use;

[0032] Figure 2Schematic diagram of severe bending and twisting of asymmetrical cross-section 2195 aluminum-lithium alloy profiles for aerospace applications during extrusion;

[0033] Figure 3 This is a front view of an extrusion die for an asymmetric cross-section 2195 aluminum-lithium alloy profile for aerospace;

[0034] Figure 4 Schematic diagram of the feed end structure of the extrusion die for asymmetric cross-section 2195 aluminum-lithium alloy profiles for aerospace Figure 1 ;

[0035] Figure 5 Schematic diagram of the feed end structure of the extrusion die for asymmetric cross-section 2195 aluminum-lithium alloy profiles for aerospace Figure 2 ;

[0036] Figure 6 Schematic diagram of the feed end structure of the extrusion die for asymmetric cross-section 2195 aluminum-lithium alloy profiles for aerospace Figure 3 ;

[0037] Figure 7 This is a schematic diagram of the discharge end structure of the asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die for aerospace use.

[0038] Illustrations: 1-mold; 2-working zone; 3-pre-deformation cavity; 4-mold hole; 5-guide cavity; 6-first cavity wall of short flange; 7-second cavity wall of short flange; 8-third cavity wall of short flange; 9-fourth cavity wall of short flange; 10-fifth cavity wall of short flange; 11-first cavity wall of web; 12-first cavity wall of long flange; 13-second cavity wall of long flange; 14-third cavity wall of long flange; 15-fourth cavity wall of long flange; 16-fifth cavity wall of long flange; 17-fourth cavity wall of web; 18-third cavity wall of web; 19-second cavity wall of web; 20-empty knife; 21-short flange; 22-long flange; 23-L-shaped web; 24-reinforcement part; 2-1-primary working zone; 2-2-secondary working zone. DETAILED DESCRIPTION

[0039] It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present utility model will be described in detail below with reference to the accompanying drawings and in combination with the embodiments. It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those of ordinary skill in the art to which the present application belongs.

[0040] Asymmetric cross-section profiles are an important type of component in the field of aerospace equipment, and play an important role in load transfer. At present, the manufacturing of such components has the problem of long production process and high cost. During the extrusion process, the extrusion speed, stress and strain distribution of each part are uneven due to the die structure and extrusion process, which will produce Figure 2 The defects of bending, twisting, etc. shown in the figure. Based on this, the present invention proposes an asymmetric cross-section profile extrusion die and forming method for aerospace.

[0041] In this embodiment, the asymmetric cross-section profile extrusion die for aerospace is used to process the asymmetric cross-section profile. Figure 1 Specifically, it can be seen as consisting of a short flange 21, a long flange 22 and an L-shaped web 23, wherein the L-shaped web 23 has a reinforcing portion 24 for stabilization. The short flange 21 is 85 mm long and 20 mm wide; the long flange 22 is 110 mm long and 20 mm wide; the long side of the L-shaped web 23 is 45 mm long and 15 mm wide, the short side is 40 mm long and 20 mm wide, and all right-angled sides and joints have arc transitions with a radius of 3 mm.

[0042] The asymmetric cross-section 2195 aluminum-lithium alloy profile mentioned in the present application has the characteristics of more complex cross-section and greater difficulty in extrusion compared with the existing aerospace L-shaped cross-section high-strength aluminum alloy curved profile; the existing aerospace L-shaped cross-section high-strength aluminum alloy has an L-shaped cross-section, and the curved profile is obtained by extrusion. During the extrusion process, it is only necessary to adjust the difference in metal flow between the inner and outer sides of the profile to make the metal flow uneven, thereby directly extruding the curved part; and the asymmetric cross-section profile mentioned in the present application, its cross-section can be approximately regarded as a "five" structure, and its upper part is The upper and lower structures are asymmetrical, and the L-shaped web 23 between the short flange 21 and the long flange 22 is completely asymmetrical. Such a combination increases the complexity of profile extrusion, and under the premise that the application requires the extrusion of a straight profile, the difficulty of controlling the metal flow rate during the extrusion process increases, the difference in metal flow is difficult to adjust, the uniformity of the flow in each part is difficult to ensure, and the stability of the metal flowing into the die hole 4 is difficult to ensure, which will eventually affect the quality of the extruded profile due to defects such as twisting and bending.

[0043] In response to the above problems, the present application improves the flow uniformity and feed amount during profile extrusion by increasing the inclination angle of the guide cavity 5 on the basis of designing the eccentric distance according to the cross-section of the profile, optimizes the flow velocity difference of each part and avoids the occurrence of defects by adjusting the length of the working belt 2 and setting a two-stage working belt, and reduces the extrusion load and ensures the strength of the mold by sequentially setting the pre-deformation cavity 3 and the guide cavity 5 to form a multi-stage guide structure. These designs can effectively homogenize the flow rate and stress field, improve the extrusion defects of asymmetric cross-section profiles, enhance the strain and improve the mechanical properties, and finally realize the self-correcting extrusion molding of asymmetric cross-section profiles for aerospace.

[0044] See also Figure 3 and Figure 4 An embodiment of the present invention provides an asymmetric cross-section profile extrusion die for aerospace, comprising: a cylindrical die 1 with a circular cross-section, a pre-deformation cavity 3 for initial deformation of the blank arranged on the die 1 from one side of the feed end, a guide cavity 5 for guiding the uniform flow of the blank during extrusion, a working belt 2 for ensuring the shape, size and surface quality of the extruded part, a die hole 4 running through the die 1, and an empty knife 20 arranged at the discharge end of the die 1 to support the working belt 8.

[0045] In order to realize the extrusion molding of the asymmetric cross-section 2195 aluminum-lithium alloy profile, the mold 1 has a circular shape, which can improve the strength and stability of the mold, better control the flow rate of the metal, and improve the material utilization rate; Figure 4 In the viewing direction, the center of the die hole 4 is 4.5 mm below the center of the die 1 and is offset 2 mm to the right. ， This offset method can adjust the flow rate at different positions and effectively improve the extrusion effect of the profile. The pre-deformation cavity 3, the flow guide cavity 5, the die hole 4, and the empty knife 20 are all set according to the size and shape of the asymmetric cross-section profile, and the difference is their respective transverse cross-sectional contour lines and corresponding covering areas.

[0046] See also Figure 3 , the pre-deformation cavity 3 and the guide cavity 5 are arranged in a stepped manner toward the working belt 2, and the blank passes through the pre-deformation cavity 3 and the guide cavity 5 in sequence; the pre-deformation cavity 3 is approximately arranged according to the cross-sectional shape of the asymmetric cross-sectional profile, and the transverse cross-sectional area of ​​the pre-deformation cavity 3 is larger than the transverse cross-sectional area of ​​the guide cavity 5. The cross-sectional shape of the guide cavity 5 is closer to the cross-sectional shape of the profile, and its transverse cross-sectional contour line is at least partially similar to the transverse cross-sectional contour line of the profile, and the area covered by the transverse cross-sectional contour line at the end of the guide cavity 5 is larger than the area covered by the transverse cross-sectional contour line at the end of the profile. The contour corners of the pre-deformation cavity 3 and the guide cavity 5 are both transitioned by arcs. By setting the multi-level guide structure of the pre-deformation cavity 3 and the guide cavity 5, it is helpful to extrude the metal evenly, reduce the extrusion load, and at the same time help to improve the strength of the mold and the forming quality of the profile.

[0047] See also Figures 4 to 6 The above-mentioned flow guiding cavity 5 is composed of multiple sections of flow guiding cavity walls. The outer contour lines of the short flange first cavity wall 6, the long flange third cavity wall 14, the long flange fourth cavity wall 15, the long flange fifth cavity wall 16, the web fourth cavity wall 17, the web third cavity wall 18, and the web second cavity wall 19 are the same as the contours of the mold hole 4 at their corresponding parts, and are offset 5mm to the outside of the mold 1 as a whole, so that the coverage area of ​​these 7 transverse cross-sectional contour lines is larger than the area of ​​the mold hole 4.

[0048] The second cavity wall 7 of the short flange, the third cavity wall 8 of the short flange, and the fourth cavity wall 9 of the short flange are offset by 9.7 mm to the outside of the mold 1, and a diversion angle of 9° is formed. The purpose of this setting is to guide more of the upper metal blank to the diversion cavity 5, increase the flow velocity and flow of this part, and thus balance the flow difference with the lower side and other parts; the fifth cavity wall 10 of the short flange, the first cavity wall 11 of the web, the first cavity wall 12 of the long flange, and the second cavity wall 13 of the long flange are offset by 13 mm to the outside of the mold 1, and a diversion angle of 15° is formed. The purpose of this setting is to guide more metal in the center and the left side to the diversion cavity 5, increase the flow velocity and flow of this part, and thus balance the flow difference with the right side and other parts, and because the flow difference between the left and right sides is greater than the flow difference between the upper and lower sides, the parameter settings of the offset and the diversion angle here are greater than the parameter settings of the previous part. Such a setting method can compensate for the metal flow on the side of the asymmetric cross-section profile without the reinforcement portion 24, so that the flow at the same horizontal position on both sides of the profile is uniform and the same.

[0049] The first cavity wall 6 of the short flange, the second cavity wall 7 of the short flange, the third cavity wall 8 of the short flange, the fourth cavity wall 9 of the short flange, and the fifth cavity wall 10 of the short flange cooperate together to be responsible for the extrusion molding process of the short flange 21 of the asymmetric cross-section profile. The first cavity wall 6 of the short flange is a diversion cavity part without an inclination angle, which is different from the inclination angle of the second cavity wall 7 of the short flange, so the two are transitionally connected by a partial arc with a radius of 10mm; the diversion inclination angle of the second cavity wall 7 of the short flange, the third cavity wall 8 of the short flange, and the fourth cavity wall 9 of the short flange is 9°, and they are transitionally connected to each other by a 1 / 4 arc with a radius of 13mm; the diversion inclination angle of the fifth cavity wall 10 of the short flange is 15°, which is different from the inclination angle of the fourth cavity wall 9 of the short flange, so the two are transitionally connected by a partial arc with a radius of 10mm. A 9° guide angle is set on the second cavity wall 7 of the short flange, the third cavity wall 8 of the short flange, and the fourth cavity wall 9 of the short flange, and a 15° guide angle is set on the fifth cavity wall 10 of the short flange, which can increase the feed amount and feed speed of the billet in this part of the extrusion process.

[0050] The long flange first cavity wall 12, the long flange second cavity wall 13, the long flange third cavity wall 14, the long flange fourth cavity wall 15, and the long flange fifth cavity wall 16 cooperate together to be responsible for the extrusion molding process of the long flange 22 of the asymmetric cross-section profile. The long flange third cavity wall 14, the long flange fourth cavity wall 15 and the long flange fifth cavity wall 16 are the guide cavity parts without inclination angles, and are connected to each other through a 1 / 4 arc transition with a radius of 8mm; the long flange first cavity wall 12 and the long flange second cavity wall 13 are the parts with a 15° guide inclination angle, and are connected through a 1 / 4 arc transition with a radius of 16mm; the long flange second cavity wall 13 and the long flange third cavity wall 14 have different inclination angles, so the two are connected through a partial arc transition with a radius of 10mm. Setting a 15° guide inclination angle between the long flange first cavity wall 12 and the long flange second cavity wall 13 can increase the feed amount and feed speed of the billet during the extrusion process on this side.

[0051] The fourth cavity wall 17 of the web, the third cavity wall 18 of the web, the second cavity wall 19 of the web and the first cavity wall 11 of the web cooperate together to form the L-shaped web 23 and its reinforcement part 24 of the asymmetric cross-section profile. The fourth cavity wall 17 of the web, the third cavity wall 18 of the web and the second cavity wall 19 of the web do not have a diversion angle, and the first cavity wall 11 of the web has a diversion angle of 15°. Among them, the fourth cavity wall 17 of the web and the third cavity wall 18 of the web are connected by a 1 / 4 arc transition with a radius of 8mm; the third cavity wall 18 of the web and the second cavity wall 19 of the web, the fourth cavity wall 17 of the web and the fifth cavity wall 16 of the long flange, and the second cavity wall 19 of the web and the first cavity wall 6 of the short flange are all connected by a 1 / 4 arc transition with a radius of 3mm; the first cavity wall 11 of the web and the fifth cavity wall 10 of the short flange and the first cavity wall 12 of the long flange are each connected by a 1 / 4 arc transition with a radius of 2.5mm. The first cavity wall 11 of the web is provided with a flow guide angle of 15°, so as to increase the feed amount and feed speed of the blank during the extrusion process on this side.

[0052] Working belt 2 is responsible for ensuring the shape, size and surface quality of the profile, and its transverse cross-sectional contour line is the same as the transverse cross-sectional contour line of the profile. Working belt 2 can be specifically divided into two parts: a primary working belt 2-1 and a secondary working belt 2-2; the primary working belt 2-1 is a closed loop with a shape that is completely similar to the cross-sectional shape of the asymmetric cross-sectional profile, and its length is 20mm; the secondary working belt 2-2 is an open loop with a shape that is partially similar to the cross-sectional shape of the asymmetric cross-sectional profile, and its length is 15mm. Because the asymmetric cross-sectional profile is an irregular shape that is asymmetrical from top to bottom and left to right during the extrusion process, the extrusion flow rate between the short flange 21, the long flange 22, the L-shaped web 23 and its reinforcement part 24 during the extrusion process is uneven, which ultimately causes the following Figure 2The extruded profile shown in the figure forms defects such as twisting and bending, and the uniformity of the internal structure of the profile is also greatly affected and becomes waste; so while the flow rate is adjusted by the inclination of the guide cavity, the friction resistance in the extrusion process of this section is increased by increasing the length of the working belt corresponding to the section with fast flow rate, and finally the purpose of reducing the extrusion flow rate of this section is achieved. In the present invention, the working belt length is increased by 15mm at the corresponding positions of the three chamber walls 14 of the long flange, the fourth chamber wall 15 of the long flange, the fifth chamber wall 16 of the long flange, the fourth chamber wall 17 of the web, the third chamber wall 18 of the web, and the second chamber wall 19 of the web to balance the flow rate of each section during the extrusion process; in the section of the third chamber wall 14 of the long flange, only the length of the working belt on one side of the reinforcement part 24 is increased, and it is connected with the primary working belt 2-1 by a transition method of a circular arc section with a radius of 10mm, and the length of the working belt is increased for the entire section in the remaining sections.

[0053] The two-stage working belt is progressive from the die discharge end to the die feed end, which not only avoids the working belt being too short, resulting in unstable profile dimensions and defects such as corrugations, but also avoids the working belt being too long, resulting in increased friction between the blank and the die, resulting in defects such as concave lines, cracks, and burrs on the profile surface. At the same time, in view of the obvious difference in flow velocity between different parts of the profile, by optimizing the offset distance, the center of the mold is offset from the center of the blank, and the walls of the guide cavity are offset from the contour line of the die hole, so that the flow velocity and flow rate at different positions can be adjusted to make it more uniform, effectively homogenizing the velocity and stress field, and effectively improving the situation where asymmetric cross-section profiles are prone to bending, twisting and other defects. At the same time, the strain is also enhanced, and the mechanical properties of the profile are improved, achieving a better extrusion effect.

[0054] See also Figure 7 , a hollow knife 20 is provided in a concave shape on one side of the discharge end of the die 1 opposite to the guide cavity 5, and at least part of the transverse cross-sectional contour line of the hollow knife 20 is the same as the transverse cross-sectional contour line of the working belt 2, and the cross-sectional area is larger than the die hole 4. The hollow knife 20 is a structural member cantilevered at the outlet end of the lower die working belt 11, which can ensure the quality of the bolster profile and the life of the extrusion die, and prevent the material from violently impacting the die working belt during the extrusion process and causing damage to it.

[0055] The extrusion process of the asymmetric cross-section profile for aerospace can be roughly divided into three stages according to the metal flow characteristics.

[0056] The first stage is the extrusion pre-deformation stage, in which pressure is applied to the metal blank to deform it and gradually fill the pre-deformation cavity 3. The pre-deformation cavity 3 can pre-form the blank in the initial stage of extrusion to make the geometric shapes of the blank and the profile more similar, which plays a role in adjusting the metal flow rate, making complex profiles easier to form, and reducing the twisting and bending deformation of the product.

[0057] The second stage is the basic extrusion stage. The flow of the metal billet is equivalent to the flow of countless concentric thin-walled cylinders. Through the action of the pre-deformation cavity 3, the metal flow is relatively stable and close to the asymmetric cross-sectional shape. In the process of entering the guide cavity 5, due to the effect of the guide angle and offset of different parts, the metal flow rate of each part of the billet remains roughly the same, and no turbulence or staggering occurs. The billet can roughly maintain the cross-sectional shape distribution of the asymmetric cross-sectional profile when entering the working belt 2. By adjusting the inclination and offset of the guide cavity 5, the flow condition of the profile during extrusion is improved, the metal flow rate becomes more uniform, the surface quality of the extruded profile is higher, and the stress and strain conditions are also changed.

[0058] The third stage is the extrusion discharging stage. As the billet enters the working belt 2, the extrusion space continues to shrink. The billet is subjected to two levels of friction resistance in the process of passing through the pre-set two-level working belts. Finally, the metal flow rate of each part of the billet remains consistent. The billet is extruded into the required asymmetric cross-section under the regulation of the working belt 2. In the process of extrusion into a profile, the flow rate of each part is consistent, so the billet is formed into a straight asymmetric cross-section profile without the need for subsequent manual straightening.

[0059] In summary, the present invention can integrate the extrusion-straightening process by reasonably designing the pre-deformation cavity and the guide cavity, and reasonably setting the guide inclination angle, offset distance, working belt length and other structures, and can realize self-straightening extrusion of asymmetric cross-section profiles, thereby overcoming the defects of cracking, damage, wrinkles, etc. that occur when the traditional process first extrudes the profile and then straightens it for the second time, so that the extruded product has good mechanical properties, improves product quality and production efficiency, and reduces production costs.

[0060] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0061] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An aerospace asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die, the profile comprising a short flange (21), a long flange (22) and an L-shaped web (23), the short flange (21) being vertically connected to the top of the L-shaped web (23), the long flange (22) being parallel to the short flange (21) and connected to one side of the bottom of the L-shaped web (23), and a reinforcing portion (24) being provided on the other side of the L-shaped web (23), characterized in that: The extrusion die comprises: A mold (1) is provided, wherein the mold (1) is a columnar structure with a circular cross section; the mold (1) is provided with a pre-deformation cavity (3) for initially deforming a blank, a flow guide cavity (5) for guiding the blank to flow evenly during extrusion, a working belt (2) for ensuring the shape, size and surface quality of the extruded part, a die hole (4) passing through the mold (1), and an empty knife (20) provided at the discharge end of the mold (1) to support the working belt (2); the pre-deformation cavity (3), the flow guide cavity (5), the die hole (4) and the empty knife (20) are all designed according to the size and shape of the profile.

2. The asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die for aerospace according to claim 1, characterized in that: The center position of the die hole (4) is offset to the lower side and right side of the center position of the mold (1); the contour corners of the pre-deformation cavity (3), the guide cavity (5), the die hole (4) and the empty knife (20) are all transitioned through arcs, and their respective transverse cross-sectional contour lines and corresponding covering areas are different; The transverse cross-sectional area of ​​the pre-deformation cavity (3) is larger than the transverse cross-sectional area of ​​the guide cavity (5); the transverse cross-sectional contour line of the guide cavity (5) is at least partially the same as the transverse cross-sectional contour line of the profile, and is larger than the area covered by the transverse cross-sectional contour line of the end of the profile.

3. The asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die for aerospace according to claim 1, characterized in that: The guide cavity (5) is composed of a plurality of sections of guide cavity walls, including: a first cavity wall of a short flange (6), a second cavity wall of a short flange (7), a third cavity wall of a short flange (8), a fourth cavity wall of a short flange (9), a fifth cavity wall of a short flange (10), a first cavity wall of a web plate (11), a first cavity wall of a long flange (12), a second cavity wall of a long flange (13), a third cavity wall of a long flange (14), a fourth cavity wall of a long flange (15), a fifth cavity wall of a long flange (16), a fourth cavity wall of a web plate (17), a third cavity wall of a web plate (18), and a second cavity wall of a web plate (19); Among them, the outer contour lines of the short flange first cavity wall (6), the long flange third cavity wall (14), the long flange fourth cavity wall (15), the long flange fifth cavity wall (16), the web fourth cavity wall (17), the web third cavity wall (18), and the web second cavity wall (19) are the same as the mold hole contours at their corresponding positions, and are offset toward the outside of the mold (1) as a whole, so that the coverage area of ​​these seven transverse cross-sectional contour lines is larger than the area of ​​the mold hole (4).

4. The asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die for aerospace according to claim 3, characterized in that: The short flange first cavity wall (6), the short flange second cavity wall (7), the short flange third cavity wall (8), the short flange fourth cavity wall (9), and the short flange fifth cavity wall (10) cooperate together to be responsible for the extrusion molding process of the short flange (21) of the asymmetric cross-section profile; The short flange second cavity wall (7), the short flange third cavity wall (8), the short flange fourth cavity wall (9), the short flange fifth cavity wall (10), the web first cavity wall (11), the long flange first cavity wall (12), and the long flange second cavity wall (13) are offset toward the outside of the mold (1) and form a guide angle, the short flange first cavity wall (6) is a guide cavity part without an angle, and the cavity walls are connected by a transition of circular arc segments.

5. The asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die for aerospace according to claim 3, characterized in that: The long flange first cavity wall (12), the long flange second cavity wall (13), the long flange third cavity wall (14), the long flange fourth cavity wall (15), and the long flange fifth cavity wall (16) cooperate together to be responsible for the extrusion molding process of the long flange (22) of the profile; The long-flange first cavity wall (12) and the long-flange second cavity wall (13) are offset toward the outside of the mold (1) and form a flow guide angle, and the long-flange third cavity wall (14), the long-flange fourth cavity wall (15) and the long-flange fifth cavity wall (16) are flow guide cavity parts without an angle, and the cavity walls are connected by transition of circular arc segments.

6. The asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die for aerospace according to claim 3, characterized in that: The fourth web cavity wall (17), the third web cavity wall (18), the second web cavity wall (19) and the first web cavity wall (11) cooperate with each other to form the L-shaped web (23) and its reinforcement part (24) of the profile; The first cavity wall (11) of the web is offset toward the outside of the mold (1) to form a flow guide angle, and the fourth cavity wall (17), the third cavity wall (18) and the second cavity wall (19) of the web are flow guide cavity parts without an angle, and the cavity walls are connected by a transition of circular arc segments.

7. The asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die for aerospace according to claim 1, characterized in that: The transverse cross-sectional contour line of the working belt (2) is the same as the transverse cross-sectional contour line of the profile, and the working belt (2) is divided into two parts: a primary working belt (2-1) and a secondary working belt (2-2); The primary working belt (2-1) is arranged in such a way that it is added in full section at each cavity wall, and its shape is a closed loop having the same cross-sectional shape as the profile; the secondary working belt (2-2) is arranged in such a way that a secondary working belt (2-2) is added at corresponding positions of a total of 6 sections, namely, the third cavity wall (14) of the long flange, the fourth cavity wall (15) of the long flange, the fifth cavity wall (16) of the long flange, the fourth cavity wall (17) of the web, the third cavity wall (18) of the web, and the second cavity wall (19) of the web, and its shape is an open loop having the same cross-sectional shape as the corresponding section of the profile; the secondary working belt (2-2) only increases the length of one side of the reinforcement part in the section of the third cavity wall (14) of the long flange, and is connected with the primary working belt (2-1) by means of a circular arc transition.

8. The asymmetric cross-section 2195 aluminum-lithium alloy profile extrusion die for aerospace according to claim 1, characterized in that: The hollow knife (20) is arranged in a concave shape on one side of the discharge end of the mold (1), and at least part of the transverse cross-sectional contour line is the same as the transverse cross-sectional contour line of the working belt (2), and the cross-sectional area is larger than the mold hole (4).

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