Extrusion forming die, preparation method of alloy bar and preparation device of alloy bar

Abstract

The invention provides an extrusion forming die, and a preparation method and a preparation device of an alloy bar, which can solve the problem of non-uniform structure of a large-size alloy bar while avoiding generation of serious coarse grains. The extrusion forming die is provided with: an extrusion hole; a shaping hole having a circular cross section; the forming channel extends from the extrusion hole to the shaping hole, and the forming channel is divided into a deformation section and a contraction section in the extending direction; the deformation section is provided with a polygonal cross section, and the deformation section rotationally extends to the contraction section from the extrusion hole to form a rotating channel directly communicated with the extrusion hole; the contraction section gradually contracts and extends to the shaping hole from the deformation section so as to form a variable cross-section channel directly communicated with the shaping hole.

Description

Technical Field

[0001] The present application relates to the technical field of alloy manufacturing, and particularly to an extrusion forming die, a preparation method of an alloy bar, and a preparation device thereof. Background Art

[0002] In recent years, with the rapid development of the aerospace and transportation industries, there is a higher demand for energy consumption, and at the same time, it brings great pressure to environmental protection. Therefore, the lightweighting of aircraft or automobiles is an inevitable choice. Since the Al-Zn-Mg-Cu alloy has a series of advantages such as low density, high specific strength, high specific stiffness, and good corrosion resistance, it can reduce the product weight and energy consumption while ensuring the product quality. Therefore, the Al-Zn-Mg-Cu alloy has broad application prospects and an irreplaceable position in the fields of aerospace, transportation, 3C electronics industry, advanced equipment, etc.; especially with the technological innovation and product material upgrade, the demand for high-strength and excellent comprehensive performance Al-Zn-Mg-Cu alloy bars is increasing day by day.

[0003] In order to avoid severe coarse grains, a relatively small extrusion ratio is usually selected for the traditional aluminum alloy bars during extrusion forming. However, although this traditional extrusion process of using a relatively small extrusion ratio to prepare aluminum alloy bars can reduce the coarse grain defects to a certain extent, it is easy to have insufficient deformation during the extrusion process, resulting in some as-cast structures remaining in the core of the aluminum alloy bar product, leading to uneven product structure and having an adverse effect on the comprehensive performance of the product. Summary of the Invention

[0004] One advantage of the present application is to provide an extrusion forming die, a preparation method of an alloy bar, and a preparation device thereof, which can avoid severe coarse grains and improve the problem of uneven structure of large-sized alloy bars.

[0005] Another advantage of the present application is to provide an extrusion forming die, a preparation method of an alloy bar, and a preparation device thereof. In one embodiment of the present application, the extrusion forming die can cause the core of the ingot to deform during the extrusion process, so as to eliminate the as-cast structure retained due to insufficient core deformation and improve the structure uniformity of the alloy bar.

[0006] Another advantage of the present application is to provide an extrusion forming die, a preparation method of an alloy bar, and a preparation device thereof. In one embodiment of the present application, the preparation method of the alloy bar can not only reduce the residual phases inside the ingot, avoid overburning of some low melting point phases, but also avoid the solution strengthening effect during the cooling process of the ingot, further reduce the deformation resistance, and is beneficial to enhancing the extrudability of the ingot.

[0007] Another advantage of the present application lies in providing an extrusion forming die, a preparation method and a preparation device for an alloy bar. Among them, in one embodiment of the present application, the preparation device for the alloy bar can use the backward extrusion method and the above extrusion forming die to prepare a large-sized alloy bar with uniform structure, which not only avoids the formation of severe coarse grains on the surface of the alloy bar, but also refines the structure of the alloy bar and improves the mechanical properties.

[0008] Another advantage of the present application lies in providing an extrusion forming die, a preparation method and a preparation device for an alloy bar. To achieve the above object, expensive materials or complex structures are not required in the present application. Therefore, the present application successfully and effectively provides a solution, not only providing a simple extrusion forming die, a preparation method and a preparation device for an alloy bar, but also increasing the practicability and reliability of the extrusion forming die, the preparation method and the preparation device for the alloy bar.

[0009] To achieve at least one of the above advantages or other advantages and objects of the present application, the present application provides an extrusion forming die, which is provided with: An extrusion hole; A shaping hole, having a circular cross-section; and A forming channel, wherein the forming channel extends from the extrusion hole to the shaping hole, and the forming channel is divided into a deformation section and a contraction section along the extending direction; the deformation section has a polygonal cross-section, and the deformation section extends rotationally from the extrusion hole to the contraction section to form a rotating channel directly communicating with the extrusion hole; the contraction section extends gradually from the deformation section to the shaping hole to form a variable cross-section channel directly communicating with the shaping hole.

[0010] According to one embodiment of the present application, the deformation section extends from the extrusion hole with a constant cross-section to the contraction section to form a rotating constant cross-section channel.

[0011] According to one embodiment of the present application, the polygonal cross-section of the deformation section rotates 90° from the extrusion hole to the contraction section.

[0012] According to one embodiment of the present application, the polygonal cross-section of the deformation section is a square cross-section.

[0013] According to one embodiment of the present application, the ratio between the side length of the cross-section of the forming channel in the deformation section and the diameter of the shaping hole ranges from 1 to 1.8.

[0014] According to one embodiment of the present application, the contraction section extends from the deformation section by lofting to the shaping hole.

[0015] According to an embodiment of the present application, the squeezing hole has a polygonal cross-section; the end cross-section corresponding to the squeezing hole on the deformation section coincides with the cross-section of the squeezing hole.

[0016] According to an aspect of the present application, the present application further provides a device for preparing an alloy bar, including: An extrusion cylinder for holding an ingot; Any of the above-mentioned extrusion forming dies that can be slidably inserted into the extrusion cylinder; and An extrusion rod, which is drivingly connected to the extrusion forming die and is used to drive the extrusion forming die to slide relative to the extrusion cylinder so as to reversely extrude the ingot into an alloy bar.

[0017] According to an embodiment of the present application, the extrusion forming die has an outer peripheral surface that matches the inner wall of the extrusion cylinder; the extrusion rod has a hollow structure.

[0018] According to an aspect of the present application, the present application further provides a method for preparing an alloy bar, including the steps of: Performing a homogenization precipitation treatment on the ingot to obtain an ingot to be extruded; Preheating the ingot to be extruded and any of the above-mentioned extrusion forming dies; and Reversely extruding the pre-set ingot to be extruded in the extrusion cylinder through the extrusion forming die to obtain an alloy bar.

[0019] According to an embodiment of the present application, the step of reversely extruding the pre-set ingot to be extruded in the extrusion cylinder through the extrusion forming die to obtain an alloy bar includes the steps of: Performing a pre-deformation treatment on the ingot to be extruded through the squeezing hole of the extrusion forming die, so that the metal material of the squeezing die is converted from a circular cross-section to a polygonal cross-section; Rotating the metal in the die through the deformation section in the forming channel of the extrusion forming die, so that the metal core deforms; and Shrinking the metal cross-section in the die through the shrinking section in the forming channel, so that an alloy bar meeting the product target size is extruded from the sizing hole of the extrusion forming die.

[0020] According to an embodiment of the present application, the extrusion speed of the alloy bar is between 1.5 m / min and 2.5 m / min; the extrusion ratio of the extrusion forming die is between 7 and 9.

[0021] According to an embodiment of the present application, the step of preheating the ingot to be extruded and any of the above-mentioned extrusion forming dies includes the steps of: Preheating the ingot to be extruded to a first preset extrusion temperature; and Preheat the extrusion die to a second preset extrusion temperature and hold for a first preset holding time.

[0022] According to an embodiment of the present application, the first preset extrusion temperature ranges from 400°C to 420°C; the second preset extrusion temperature ranges from 450°C to 470°C; and the first preset holding time ranges from 4 h to 6 h.

[0023] According to an embodiment of the present application, the step of subjecting the ingot to homogeneous precipitation treatment to obtain the ingot to be extruded includes the steps of: First, heat the ingot to a first preset homogeneous temperature and hold for a second preset holding time; then increase the temperature to a second preset homogeneous temperature at a preset heating rate and hold for a third preset holding time to obtain a homogenized ingot; and First, cool the homogenized ingot in the furnace to a preset precipitation temperature, and then take it out and air-cool it to obtain the ingot to be extruded.

[0024] According to an embodiment of the present application, the first preset homogeneous temperature ranges from 420°C to 440°C; the second preset holding time ranges from 10 h to 12 h; the preset heating rate ranges from 10°C / h to 15°C / h; the second preset homogeneous temperature ranges from 470°C to 485°C; the third preset holding time ranges from 10 h to 12 h; and the preset precipitation temperature ranges from 340°C to 360°C. Description of the Drawings

[0025] Figure 1 is a schematic structural diagram of a device for preparing an alloy bar according to an embodiment of the present application; Figure 2 shows a three-dimensional schematic diagram of an extrusion die in the device for preparing an alloy bar according to the above embodiment of the present application; Figure 3 shows a top view schematic diagram of the extrusion die according to the above embodiment of the present application; Figure 4 shows Figure 3 a sectional view taken along line A-A of the extrusion die shown; Figure 5 shows Figure 3 a sectional view taken along line B-B of the extrusion die shown; Figure 6 shows a front view schematic diagram of the extrusion die according to the above embodiment of the present application; Figure 7 shows Figure 6 a sectional view taken along line C-C of the extrusion die shown; Figure 8 showsFigure 6 Schematic cross-sectional view of the extrusion forming die taken along the D-D line; Figure 9 Shows Figure 6 Schematic cross-sectional view of the extrusion forming die taken along the E-E line; Figure 10 Shows Figure 6 Schematic cross-sectional view of the extrusion forming die taken along the F-F line; Figure 11 Shows Figure 6 Schematic cross-sectional view of the extrusion forming die taken along the G-G line; Figure 12 Schematic flow chart of the method for preparing an alloy bar according to an embodiment of the present application; Figure 13 Schematic flow chart of the backward extrusion step in the method for preparing an alloy bar according to the above embodiment of the present application; Figure 14 Schematic flow chart of the preheating step in the method for preparing an alloy bar according to the above embodiment of the present application; Figure 15 Schematic flow chart of the homogeneous precipitation step in the method for preparing an alloy bar according to the above embodiment of the present application; Figure 16 Schematic polarized light detection view of the alloy bar prepared by the method for preparing an alloy bar according to Embodiment 1 of the present application; Figure 17 Schematic polarized light detection view of the alloy bar prepared by the method for preparing an alloy bar according to Embodiment 2 of the present application; Figure 18 Schematic polarized light detection view of the alloy bar prepared by the method for preparing an alloy bar according to Embodiment 3 of the present application; Figure 19 Schematic polarized light detection view of the alloy bar prepared by the method for preparing an alloy bar according to Embodiment 4 of the present application; Figure 20 Schematic polarized light detection view of the alloy bar prepared by the method for preparing an alloy bar in Comparative Example 1; Figure 21 Schematic polarized light detection view of the alloy bar prepared by the method for preparing an alloy bar in Comparative Example 2.

[0026] Description of main component symbols: 1. Extrusion forming die; 10. Injection hole; 20. Shaping hole; 30. Forming channel; 31. Deformation section; 32. Contraction section; 2. Extrusion cylinder; 3. Extrusion rod; 4. Ingot; 5. Alloy bar.

[0027] The above descriptions of the main component symbols will further elaborate on the present application in conjunction with the accompanying drawings and specific embodiments. Specific Embodiment

[0028] The following description is used to disclose the present application so that those skilled in the art can implement the present application. The preferred embodiments in the following description are only examples, and those skilled in the art can think of other obvious variations. The basic principles defined in the following description of the present application can be applied to other implementation schemes, variant schemes, improvement schemes, equivalent schemes, and other technical schemes that do not depart from the spirit and scope of the present application.

[0029] Those skilled in the art should understand that in the disclosure of the present application, the orientation or positional relationships indicated by the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings. These are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on the present application.

[0030] In the present application, the term "a" in the claims and the specification should be understood as "one or more". That is, in one embodiment, the number of an element can be one, while in other embodiments, the number of this element can be multiple. Unless it is clearly indicated in the disclosure of the present application that the number of the element is only one, the term "a" should not be understood as being unique or single, and the term "a" should not be construed as a limitation on the quantity.

[0031] In the description of the present application, it should be understood that terms such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through a medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0032] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0033] Considering that although for small-sized alloy bars, the defect of uneven microstructure can be improved by appropriately increasing the extrusion ratio, for large-sized alloy bars, limited by the current ingot specifications and the tonnage of extrusion equipment, it is very difficult to effectively solve the defect of uneven microstructure using traditional extrusion processes. Therefore, this application creatively proposes an extrusion forming die, a preparation method of an alloy bar, and its preparation device, which can improve the problem of uneven microstructure of large-sized alloy bars while avoiding the generation of severe coarse grains.

[0034] Specifically, referring to the accompanying drawings of this application Figure 1 , according to an embodiment of this application, a preparation device for an alloy bar is provided, which may include an extrusion cylinder 2 for containing an ingot 4, an extrusion forming die 1 that can be slidably inserted into the extrusion cylinder 2, and an extrusion rod 3 drivingly connected to the extrusion forming die 1, such that the extrusion forming die 1 slides relative to the extrusion cylinder 2 under the drive of the extrusion rod 3 to reverse-extrude the ingot 4 into an alloy bar 5. It can be understood that the ingot 4 mentioned in this application can be, but is not limited to, implemented as an Al-Zn-Mg-Cu ingot to obtain an Al-Zn-Mg-Cu alloy bar. In addition, in other embodiments of this application, the extrusion rod 3 and the extrusion forming die 1 can also be fixed, but directly drive the extrusion cylinder 2 to slide relative to the extrusion forming die 1, and still be able to make the extrusion forming die 1 slide relative to the extrusion cylinder 2 to achieve the required reverse extrusion effect, which will not be elaborated in this application.

[0035] More specifically, as Figures 2 to 11As shown, the extrusion forming die 1 can be provided with an extrusion hole 10, a shaping hole 20 with a circular cross-section, and a forming channel 30 extending from the extrusion hole 10 to the shaping hole 20. The forming channel 30 is divided into a deformation section 31 and a contraction section 32 along the extending direction. The deformation section 31 has a polygonal cross-section, and the deformation section 31 extends rotationally from the extrusion hole 10 to the contraction section 32 to form a rotating channel directly communicating with the extrusion hole 10. The contraction section 32 extends taperingly from the deformation section 31 to the shaping hole 20 to form a variable cross-section channel directly communicating with the shaping hole 20.

[0036] In this way, when the preparation device of the alloy bar extrudes the preheated ingot 4 through the extrusion forming die 1, the alloy material extruded from the extrusion hole 10 will first enter the deformation section 31 of the forming channel 30 and rotate along the rotating channel, so that the alloy material generates core deformation during rotation; then enter the contraction section 32 of the forming channel 30 and contract along the variable cross-section channel, so that the alloy material generates cross-section contraction during contraction, and then is extruded in a shaped manner from the shaping hole 20 to form an alloy bar 5 with a circular cross-section.

[0037] It should be noted that, on the one hand, since the deformation section 31 of the forming channel 30 has a polygonal cross-section rotating along the extending direction to form a rotating channel directly communicating with the extrusion hole 10, the alloy material extruded from the extrusion hole 10 will rotate along the rotating channel, so that the alloy core generates deformation during rotation, thereby eliminating the retention of the original as-cast structure due to insufficient core deformation amount, which is beneficial to obtaining an alloy bar 5 with uniform structure. On the other hand, since the contraction section 32 of the forming channel 30 extends taperingly to form a variable cross-section channel directly communicating with the shaping hole 20, the alloy material extruded from the rotating channel will contract along the variable cross-section channel, so that the alloy cross-section generates deformation during contraction, thereby gradually shaping into the circular cross-section of the shaping hole 20, so as to ensure that the alloy bar 5 extruded from the shaping hole 20 is shaped to the target size of the product.

[0038] In addition, since the extrusion forming die 1 in the preparation equipment of the alloy bar slides relative to the extrusion cylinder 2 under the drive of the extrusion rod 3 to extrude the ingot 4 placed in the extrusion cylinder 2, the ingot 4 placed in the extrusion cylinder 2 is fixed relative to the extrusion cylinder 2 during the extrusion forming process and will not rub against the inner wall of the extrusion cylinder 2. Therefore, the extrusion force required for the preparation equipment of the alloy bar can be significantly reduced, will not exceed the upper limit of the extruder, and is also beneficial to improving the service life of the die; at the same time, the surface metal of the ingot 4 will not be severely deformed due to no friction with the inner wall of the extrusion cylinder 2, and will not store energy violently, which can well avoid the formation of a serious coarse grain ring on the surface of the alloy bar.

[0039] In other words, when preparing large-sized alloy bars, the preparation equipment for the alloy bars of the present application not only uses backward extrusion (i.e., the extrusion direction of the alloy bar is opposite to the extrusion direction of the extrusion rod 3) to reduce the required extrusion force and avoid the generation of coarse grains, but also uses the rotating channel of the extrusion forming die 1 to make the alloy material rotate and deform, so as to improve the problem that the deformation degree of the core of the large-sized alloy bar is small, thereby refining the structure of the alloy bar and improving its mechanical properties. It can be understood that, compared with conventional dies, the inner cavity area of the extrusion forming die 1 of the present application is significantly increased. If forward extrusion is used (i.e., the extrusion direction of the alloy bar is the same as the extrusion direction of the extrusion rod 3), the ingot 4 will slide relative to the extrusion cylinder 2 under the extrusion of the extrusion rod 3, resulting in severe friction between the skin metal of the ingot 4 and the inner wall of the extrusion cylinder 2. Coupled with the severe friction between the metal skin in the die and the inner cavity of the die, a large amount of energy is stored, causing a severe coarse grain ring to form on the surface of the alloy bar.

[0040] Exemplarily, as Figures 3 to 9 shown, the polygonal cross-section of the deformation section 31 is preferably implemented as a square cross-section, so as to reduce the deformation difference at different positions during cross-section contraction when reducing the cross-section from a square cross-section to a circular cross-section in the variable cross-section channel while generating a twisting effect on the alloy material in the rotating channel, and reduce the anisotropy of the alloy bar.

[0041] It should be noted that in other examples of the present application, the polygonal cross-section of the deformation section 31 can also be implemented as a regular polygonal cross-section such as an equilateral triangle cross-section or a regular pentagon cross-section. Or, in other examples of the present application, the polygonal cross-section of the deformation section 31 can also be implemented as a rectangular cross-section with a small difference between the length and the width. It can be understood that the more sides the cross-section of the deformation section 31 has, the closer it is to a circle, and the smaller the frictional force between the metal in the die and the inner wall of the deformation section 31, which is less conducive to rotational deformation.

[0042] Optionally, as Figures 7 to 9 shown, the deformation section 31 extends from the extrusion hole 10 with a constant cross-section to the contraction section 32 to form a rotating constant cross-section channel; that is, all the cross-sectional areas on the deformation section 31 are equal, so as to ensure that the alloy material extruded into the forming channel 30 only rotates on the deformation section 31 without changing the cross-sectional area. This can not only reduce the risk of grain breakage on the surface of the alloy, avoid the generation of coarse grains on the surface of the extruded alloy bar, but also reduce the extrusion resistance (i.e., reduce the frictional force between the alloy material and the die), which is beneficial to extending the die life.

[0043] Optionally, as Figure 4 and Figure 5As shown, the polygonal cross-section of the deformation section 31 rotates 90° from the extrusion hole 10 to the contraction section 32, so as to ensure sufficient deformation of the core while preventing the grains of the core from being severely broken due to excessive rotation angle and finally forming coarse grains, and ensuring that the extruded alloy bar has high mechanical properties.

[0044] Optionally, as Figure 4 shown, the ratio K between the side length L of the cross-section of the forming channel 30 in the deformation section 31 and the diameter D of the sizing hole 20 takes values between 1 and 1.8, that is, 1 ≤ K = L / D ≤ 1.8, so as to ensure an appropriate degree of deformation of the ingot 4 during extrusion while preventing the mold wall thickness from being too thin due to the relatively large cross-sectional area of the deformation section 31, which is beneficial to ensuring that the extrusion forming die 1 has good strength and stiffness.

[0045] Optionally, as Figures 4 to 10 shown, the contraction section 32 extends from the deformation section 31 in a lofting manner to the sizing hole 20, so that the cross-sections at both ends of the contraction section 32 coincide with the corresponding end cross-section of the deformation section 31 and the cross-section of the sizing hole 20 respectively (that is, the end cross-section of the contraction section 32 corresponding to the deformation section 31 and the end cross-section of the deformation section 31 corresponding to the contraction section 32 completely coincide, and the end cross-section of the contraction section 32 corresponding to the sizing hole 20 completely coincides with the cross-section of the sizing hole 20), so that the alloy material enters the contraction section 32 without deformation from the deformation section 31 and enters the sizing hole 20 without deformation from the contraction section 32. It can be understood that the lofting mentioned in this application refers to smoothly converting the polygonal cross-section into a circular cross-section along the extension direction of the contraction section 32, so that the alloy material is smoothly extruded and shaped in the contraction section 32, avoiding the generation of coarse grains on the surface of the alloy material due to mutation.

[0046] It should be noted that, as Figures 2 to 5 shown, the extrusion hole 10 can have a polygonal cross-section, so that the ingot 4 is pre-deformed into alloy material with a polygonal cross-section when being extruded from the extrusion hole 10, so as to be able to rotate along the rotation channel when entering the deformation section 31.

[0047] Optionally, as Figure 2 and Figure 5 shown, the end cross-section of the deformation section 31 corresponding to the extrusion hole 10 coincides with the cross-section of the extrusion hole 10, so that the alloy material enters the deformation section 31 from the extrusion hole 10 without deformation. For example, the side length of the cross-section of the extrusion hole 10 is equal to the side length of the cross-section of the deformation section 31, and the cross-section corners of the extrusion hole 10 are aligned with the cross-section corners of the end cross-section of the deformation section 31 corresponding to the extrusion hole 10.

[0048] According to the above embodiments of the present application, as Figure 1 and Figure 2As shown, the extrusion forming die 1 has an outer peripheral surface that matches the inner wall of the extrusion cylinder 2, so as to better extrude the ingot 4 contained in the extrusion cylinder 2 when sliding relative to the extrusion cylinder 2, and prevent the alloy material from being extruded from the gap between the inner wall of the extrusion cylinder 2 and the outer peripheral surface of the extrusion forming die 1. Preferably, the extrusion forming die 1 has a cylindrical structure, and the forming channel 30 extends along the axial direction of the die to communicate the inlet hole 10 and the shaping hole 20.

[0049] Optionally, as Figure 1 shown, the extrusion rod 3 has a hollow structure, so that when the extrusion forming die 1 is pushed through the extrusion rod 3, the alloy bar extruded through the shaping hole 20 of the extrusion forming die 1 is allowed to pass through the extrusion rod 3, avoiding structural interference between the extruded alloy bar and the extrusion rod 3, and realizing the required backward extrusion.

[0050] It is worth mentioning that, according to another aspect of the present application, as Figure 12 shown, an embodiment of the present application further provides a method for preparing an alloy bar, which may include the steps of: S100: Perform a homogenization precipitation treatment on the ingot to obtain an ingot to be extruded; S200: Preheat the ingot to be extruded and the above-mentioned extrusion forming die; and S300: Backward extrude the preheated ingot to be extruded in the extrusion cylinder through the extrusion forming die to obtain an alloy bar.

[0051] Optionally, as Figure 13 shown, step S300 in the method for preparing an alloy bar of the present application includes the steps of: S310: Perform a pre-deformation treatment on the ingot to be extruded through the inlet hole of the extrusion forming die, so that the metal material extruded into the die is converted from a circular cross-section to a polygonal cross-section; S320: Rotate the metal in the die through the deformation section in the forming channel of the extrusion forming die, so that the metal core deforms; and S330: Shrink the metal cross-section in the die through the contraction section in the forming channel, so that an alloy bar meeting the product target size is extruded from the shaping hole of the extrusion forming die.

[0052] It should be noted that in step S300 of the method for preparing an alloy bar of the present application: the extrusion speed of the alloy bar can be between 1.5 m / min and 2.5 m / min. In addition, the extrusion ratio of the extrusion forming die can be between 7 and 9.

[0053] According to the above embodiments of the present application, as Figure 14As shown, step S200 in the method for preparing the alloy bar can include the steps: S210: Preheating the ingot to be extruded to a first preset extrusion temperature; and S220: Preheating the extrusion die to a second preset extrusion temperature and holding for a first preset holding time.

[0054] Optionally, the first preset extrusion temperature ranges from 400°C to 420°C; the second preset extrusion temperature ranges from 450°C to 470°C; correspondingly, the first preset holding time ranges from 4 h to 6 h.

[0055] It should be noted that due to the large deformation resistance of conventional Al-Zn-Mg-Cu cast bars, the method for preparing the alloy bar of the present application can adopt a two-stage strengthening homogenization process and a slow cooling precipitation process to perform homogenization precipitation treatment on the ingot, so as to significantly reduce the deformation resistance of the Al-Zn-Mg-Cu cast bar. It can be understood that the two-stage strengthening homogenization process mentioned in the present application can reduce the residual phases inside the ingot; the slow cooling precipitation process mentioned in the present application can avoid the solution strengthening effect that occurs during the cooling process of the ingot, further reducing the deformation resistance and enhancing the extrudability of the ingot.

[0056] Specifically, as Figure 15 shown, step S100 in the method for preparing the alloy bar of the present application can include the steps: S110: First heating the ingot to a first preset homogenization temperature and holding for a second preset holding time; then raising the temperature to a second preset homogenization temperature at a preset heating rate and holding for a third preset holding time to obtain a homogenized ingot; and S120: First cooling the homogenized ingot in the furnace to a preset precipitation temperature, and then taking it out for air cooling to obtain the ingot to be extruded.

[0057] More specifically, in step S110 of the present application: the first preset homogenization temperature can range from 420°C to 440°C; the second preset holding time can range from 10 h to 12 h; the preset heating rate can range from 10°C / h to 15°C / h; the second preset homogenization temperature can range from 470°C to 485°C; the third preset holding time can range from 10 h to 12 h. It can be understood that the present application controls the preset heating rate between 10°C / h and 15°C / h, that is, the two-stage strengthening homogenization process of the present application can avoid overburning of some low melting point phases through a slower heating rate.

[0058] In addition, in the above-mentioned step S120 of the present application: the preset precipitation temperature can be set between 340°C and 360°C. It can be understood that in the slow cooling precipitation process of the present application, the homogenized ingot is first slowly cooled in the furnace to 340°C to 360°C, and then taken out for air cooling, which can slow down the cooling precipitation rate of the ingot, so as to avoid the solution strengthening effect that occurs during the cooling process of the ingot, further reduce the deformation resistance, and enhance the extrudability of the ingot.

[0059] The following will describe in more detail some specific but non-limiting embodiments of the above-mentioned embodiments of the present application with reference to the accompanying drawings, and take 7075 alloy ingots as the ingot material for preparing Al-Zn-Mg-Cu alloy bars for experiments.

[0060] Example 1 A method for preparing an alloy bar, using a 7075 alloy ingot as the extruded bar, with an extrusion ratio of 9; specifically including the following steps: 1) First, keep the temperature at 420°C for 10 h, and then raise the temperature to 470°C in 5 h and keep it for 10 h to complete the double-stage strengthening homogenization process of the ingot; 2) After homogenization, first cool it in the furnace to 360°C, and then take it out for air cooling to complete the slow cooling precipitation process of the ingot; 3) First heat the ingot to 420°C, heat the extrusion die to 470°C and keep it for 6 h, then use the backward extrusion method for trial production, and control the extrusion speed of the alloy bar at 1.5 m / min to complete the high-temperature slow extrusion process of the alloy bar.

[0061] Finally, after cutting off the head and tail waste of the alloy bar extruded in Example 1, first take a 50-mm-long sample for heat treatment, and then conduct polarized light detection to obtain Figure 16 the schematic diagram of polarized light detection shown.

[0062] Example 2 A method for preparing an alloy bar, using a 7075 alloy ingot as the extruded bar, with an extrusion ratio of 9; specifically including the following steps: 1) First, keep the temperature at 440°C for 12 h, and then raise the temperature to 485°C in 4.5 h and keep it for 12 h to complete the double-stage strengthening homogenization process of the ingot; 2) After homogenization, first cool it in the furnace to 340°C, and then take it out for air cooling to complete the slow cooling precipitation process of the ingot; 3) First heat the ingot to 400°C, heat the extrusion die to 450°C and keep it for 4 h, then use the backward extrusion method for trial production, and control the extrusion speed of the alloy bar at 2.5 m / min to complete the low-temperature rapid extrusion process of the alloy bar.

[0063] Finally, after cutting off the head and tail waste of the alloy bar extruded in the second embodiment, first take a 50-mm-long sample for heat treatment, and then conduct polarized light detection to obtain Figure 17 the schematic diagram of polarized light detection as shown.

[0064] Embodiment 3 A preparation method of an alloy bar uses a 7075 alloy ingot as the extruded bar, and the extrusion ratio is 7; specifically includes the following steps: 1) First, keep the temperature at 420 °C for 10 h, and then raise the temperature to 470 °C in 5 h and keep it for 10 h to complete the double-stage strengthening and homogenization process of the ingot; 2) After homogenization, first cool it in the furnace to 360 °C, and then take it out for air cooling to complete the slow cooling precipitation process of the ingot; 3) First heat the ingot to 420 °C, heat the extrusion die to 470 °C and keep it for 6 h, then use the backward extrusion method for trial production, and control the extrusion speed of the alloy bar at 1.5 m / min to complete the high-temperature slow extrusion process of the alloy bar.

[0065] Finally, after cutting off the head and tail waste of the alloy bar extruded in the third embodiment, first take a 50-mm-long sample for heat treatment, and then conduct polarized light detection to obtain Figure 18 the schematic diagram of polarized light detection as shown.

[0066] Embodiment 4 A preparation method of an alloy bar uses a 7075 alloy ingot as the extruded bar, and the extrusion ratio is 7; specifically includes the following steps: 1) First, keep the temperature at 440 °C for 12 h, and then raise the temperature to 485 °C in 4.5 h and keep it for 12 h to complete the double-stage strengthening and homogenization process of the ingot; 2) After homogenization, first cool it in the furnace to 340 °C, and then take it out for air cooling to complete the slow cooling precipitation process of the ingot; 3) First heat the ingot to 400 °C, heat the extrusion die to 450 °C and keep it for 4 h, then use the backward extrusion method for trial production, and control the extrusion speed of the alloy bar at 2.5 m / min to complete the low-temperature rapid extrusion process of the alloy bar.

[0067] Finally, after cutting off the head and tail waste of the alloy bar extruded in the fourth embodiment, first take a 50-mm-long sample for heat treatment, and then conduct polarized light detection to obtain Figure 19 the schematic diagram of polarized light detection as shown.

[0068] In summary, attached Figures 16 to 19The polarization detection results of the alloy bars prepared in Example 1 to Example 4 are shown in sequence. It can be easily seen from the figure that for the alloy bars produced by using the extrusion forming die and the backward extrusion method of the present application, not only is the core structure uniform without the remaining as-cast structure, but also the grain size of the bars is finer when the extrusion speed is 2.5 m / min. It can be understood that since the special extrusion forming die can cause the metal to rotate inside the die during extrusion, increasing the amount of deformation, the present application can well eliminate the remaining as-cast structure in the core of the bar and improve the structural uniformity of the bar.

[0069] In addition, the present application further provides two sets of comparative examples to demonstrate the superiority of the present application through comparison.

[0070] Comparative Example 1 Compared with the above Example 1, this Comparative Example 1 uses exactly the same ingot material, specifications, and extrusion process parameters as those in Example 1. The only difference is that Comparative Example 1 uses a conventional die and a forward extrusion process. The alloy bar prepared by it is subjected to polarization detection, and the Figure 20 schematic diagram of the polarization detection shown is obtained.

[0071] Comparative Example 2 Compared with the above Example 3, this Comparative Example 2 uses exactly the same ingot material, specifications, and extrusion process parameters as those in Example 3. The only difference is that Comparative Example 2 uses an extrusion forming die and a forward extrusion process. The alloy bar prepared by it is subjected to polarization detection, and the Figure 21 schematic diagram of the polarization detection shown is obtained.

[0072] In summary, the attachments Figure 20 and Figure 21 show the polarization detection results of the alloy bars prepared in Comparative Example 1 and Comparative Example 2 in sequence. It can be easily seen from the figure that for the alloy bars prepared by using a conventional die and a forward extrusion process, there is still some as-cast structure in the core, resulting in non-uniform structure and affecting the comprehensive performance of the material; while for the alloy bars prepared by using the special extrusion forming die and the forward extrusion process of the present application, due to the double severe friction of the inner cavity of the extrusion forming die and the inner wall of the extrusion cylinder on the metal on the surface of the bar, the surface grains of the bar are severely broken, and it is extremely easy to generate coarse grains, resulting in more non-uniform structure and affecting the comprehensive performance of the material.

[0073] In other words, the preparation method of the alloy bar of the present application uses a special extrusion forming die and a backward extrusion process, which can not only ensure that the core structure of the bar is uniform without the remaining as-cast structure, but also avoid the generation of coarse grains, so as to obtain an alloy bar with better structural uniformity.

[0074] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0075] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application.

Claims

1. Extrusion forming die, characterized in that: The following facilities are available: squeeze into the hole; A shaped hole having a circular cross section; as well as A forming channel, wherein the forming channel extends from the extrusion hole to the shaping hole, and the forming channel is divided into a deformation section and a contraction section along the extension direction; The deformation section has a polygonal cross-section, and the deformation section rotationally extends from the extrusion hole to the contraction section to form a rotation channel directly connected to the extrusion hole; the contraction section gradually extends from the deformation section to the shaping hole to form a variable-section channel directly connected to the shaping hole.

2. The extrusion die according to claim 1, characterized in that: The deformation section extends from the extrusion hole to the contraction section with a constant cross-section to form a rotating channel with a constant cross-section.

3. The extrusion die according to claim 2, characterized in that: The polygonal cross section of the deformation section is rotated 90° from the extrusion hole to the contraction section.

4. The extrusion forming die according to claim 1, characterized in that: The polygonal cross section of the deformation section is a square cross section.

5. The extrusion die according to claim 4, characterized in that: The ratio of the cross-sectional side length of the forming channel in the deformation section to the diameter of the forming hole is between 1 and 1.

8.

6. The extrusion die according to any one of claims 1 to 5, characterized in that: The contraction section extends from the deformation section to the shaped hole in a lofted manner.

7. The extrusion die according to any one of claims 1 to 5, characterized in that: The extrusion hole has a polygonal cross section; the end cross section of the deformation section corresponding to the extrusion hole coincides with the cross section of the extrusion hole.

8. A device for preparing alloy bars, characterized in that: include: An extrusion cylinder for holding the ingot; The extrusion forming die according to any one of claims 1 to 7, capable of being slidably loaded into the extrusion barrel; as well as The extrusion rod is drivingly connected to the extrusion forming die and is used for driving the extrusion forming die to slide relative to the extrusion barrel so as to reversely extrude the ingot into an alloy rod.

9. The alloy rod manufacturing device according to claim 8, characterized in that: The extrusion forming die has an outer peripheral surface matched with the inner wall of the extrusion cylinder; and the extrusion rod has a hollow structure.

10. A method for preparing an alloy bar, characterized in that: Includes steps: Performing homogenization and precipitation treatment on the ingot to obtain an ingot to be extruded; Preheating the ingot to be extruded and the extrusion forming die as claimed in any one of claims 1 to 7; as well as The preset ingot to be extruded is reversely extruded in the extrusion barrel by the extrusion forming die to obtain the alloy rod.

11. The method for preparing the alloy rod according to claim 10, characterized in that: The step of reversely extruding the preset ingot to be extruded in the extrusion barrel through the extrusion forming die to obtain the alloy rod comprises the steps of: The ingot to be extruded is pre-deformed through the extrusion hole of the extrusion forming die, so that the metal material extruded into the die is transformed from a circular cross-section to a polygonal cross-section; The metal in the die is rotated by a deformation section in a forming channel of the extrusion forming die, so that the metal core is deformed; as well as The metal cross section in the die is contracted by the contraction section in the forming channel, so that the alloy rod that meets the target size of the product is extruded from the shaping hole of the extrusion forming die; Wherein: the extrusion speed of the alloy rod is between 1.5m / min and 2.5m / min; the extrusion ratio of the extrusion forming die is between 7 and 9.

12. The method for preparing the alloy rod according to claim 10, characterized in that: The step of preheating the ingot to be extruded and the extrusion forming die as claimed in any one of claims 1 to 7 comprises the steps of: preheating the ingot to be extruded to a first preset extrusion temperature; and preheating the extrusion forming die to a second preset extrusion temperature and maintaining the temperature for a first preset holding time; Among them: the first preset extrusion temperature is between 400°C and 420°C; the second preset extrusion temperature is between 450°C and 470°C; the first preset insulation time is between 4h and 6h.

13. The method for preparing the alloy rod according to claim 10, characterized in that: The step of subjecting the ingot to homogenization precipitation treatment to obtain the ingot to be extruded comprises the steps of: Firstly, the ingot is heated to a first preset homogenization temperature and kept at the temperature for a second preset holding time; Then, the temperature is raised to a second preset homogenization temperature at a preset heating rate, and kept at the temperature for a third preset holding time to obtain a homogenized ingot; and The homogenized ingot is first cooled in a furnace to a preset precipitation temperature, and then taken out and air-cooled to obtain the ingot to be extruded; Among them: the first preset homogenization temperature is between 420℃ and 440℃; the second preset insulation time is between 10h and 12h; the preset heating rate is between 10℃ / h and 15℃ / h; the second preset homogenization temperature is between 470℃ and 485℃; the third preset insulation time is between 10h and 12h; the preset precipitation temperature is between 340℃ and 360℃.

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