A method for manufacturing a seamless composite pipe of dissimilar aluminum alloys

Abstract

The present application relates to a kind of preparation methods of dissimilar aluminum alloy seamless composite pipe, including the step of making extrusion billet into seamless composite pipe billet by extrusion, extrusion billet includes core layer, seamless sleeve set in the periphery of core layer and end plate;End plate is located in the side of the end of core layer and sleeve, and the end surface of core layer, the end surface of sleeve all contact with the side of end plate;Or, end plate is embedded in the inside of the end of sleeve, and the end surface of core layer contact with the side of end plate, and the outer peripheral surface of end plate contact with the inner peripheral surface of sleeve.Aluminum alloy seamless composite pipe is prepared according to the method of the present application, the yield rate is significantly improved compared with prior art, at the same time, it is completely unnecessary to use chemical cleaning or mechanical removal core layer backflow layer, process is reduced, cost is greatly reduced, therefore, the method of the present application has obviously greater economic benefit than prior art.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy tube processing technology, specifically relating to a method for preparing a seamless composite tube of dissimilar aluminum alloys. Background Technology

[0002] Under the dual-carbon background, the application of all-aluminum microchannel heat exchangers has achieved significant development due to the advantages of aluminum alloys, such as being green, environmentally friendly, and easy to recycle. The manifold of an all-aluminum microchannel heat exchanger is an aluminum alloy composite tube, with the core layer typically made of 3-series aluminum alloy and the sleeve typically made of 4-series aluminum alloy. Therefore, it can possess excellent mechanical properties, corrosion resistance, and brazing performance.

[0003] Traditional aluminum alloy composite pipes are high-frequency welded aluminum alloy composite pipes. Due to the presence of weld seams, problems such as porosity leakage, microcrack leakage, and oxide inclusion leakage easily occur at the weld seams. To overcome the adverse effects of weld seams, Chinese patent CN101829704A discloses a processing method for aluminum alloy composite pipes. This method involves first extruding molten aluminum ingots into sleeves, then assembling the sleeves and mandrels into an extruded blank, and finally using reverse extrusion and drawing processes to produce a seamless composite pipe. This patent can effectively avoid weld seam problems.

[0004] However, during the extrusion process of aluminum alloy seamless composite tubes, it was found that about 70% of the length of each composite tube has a 3-series aluminum alloy backflow layer on its surface. This 3-series aluminum alloy backflow layer on the surface will lead to poor brazing performance, resulting in a low yield of aluminum alloy seamless composite tubes. Currently, the yield of aluminum alloy seamless composite tubes is less than 30%, and for some aluminum alloy seamless composite tubes with thinner sleeve walls, the yield is even less than 20%.

[0005] In existing technologies, the conventional methods for removing the 3-series aluminum alloy backflow layer from the surface of seamless aluminum alloy composite pipes mainly include chemical cleaning and mechanical removal. Chemical cleaning, such as alkaline washing, can effectively remove the 3-series aluminum alloy backflow layer, but it increases the number of processes, costs, and is not environmentally friendly. Mechanical removal, such as turning, can also effectively remove the 3-series aluminum alloy backflow layer, but it also increases the number of processes, costs, and reduces production efficiency. This makes the cost of seamless aluminum alloy composite pipes remain high. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for preparing a seamless composite tube of dissimilar aluminum alloy with higher yield and lower processing cost.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a seamless composite tube of dissimilar aluminum alloys includes the step of extruding an extrusion billet to form a seamless composite tube billet, wherein the extrusion billet includes a core layer and a seamless sleeve sleeved around the core layer, and the extrusion billet also includes an end plate;

[0009] The end plate is located to the side of one end of the core layer and the sleeve, and the end face of the core layer and the end face of the sleeve are in contact with the side of the end plate;

[0010] Alternatively, the end plate is embedded inside one end of the sleeve, and the end face of the core layer is in contact with the side of the end plate, and the outer peripheral surface of the end plate is in contact with the inner peripheral surface of the sleeve.

[0011] The core layer and the sleeve are made of different series of aluminum alloys. The sleeve and the end plate are made of the same series of aluminum alloys, or the sleeve and the end plate are made of the same material.

[0012] When the extrusion step is performed on the extruded billet, the end of the extruded billet having the end plate is extruded first.

[0013] Preferably, the phase contact is a zero-gap phase contact.

[0014] According to some embodiments of the present invention, the method for preparing the dissimilar aluminum alloy seamless composite tube further includes the step of preparing an extruded billet, wherein the extruded billet is prepared in one of the following ways:

[0015] Method a: Melt the raw materials of the sleeve and the raw materials of the core layer separately, and then composite cast them to obtain a composite casting billet. Remove part of the core layer inside one end of the composite casting billet, and then embed the end plate into the interior of the one end of the composite casting billet to obtain the extruded billet.

[0016] Alternatively, the raw materials of the sleeve and the raw materials of the core layer are melted separately, and then composite casting is performed to obtain a composite casting billet. During the extrusion step, the end plate is placed to the side of one end of the composite casting billet and the end plate is in contact with the end face of the composite casting billet to obtain the extruded billet.

[0017] Method b: Stamping a sheet of the same material as the sleeve to obtain the sleeve and at least a portion of the end plate integrally formed with the sleeve, heating, and then combining with the core layer to obtain the extruded blank;

[0018] Method c: After heating the sleeve, combine it with the core layer and the end plate to obtain the extruded billet;

[0019] Alternatively, after heating the sleeve, it can be combined with the core layer, making the end faces of the sleeve and the core layer flush. During the extrusion step, the end plate is placed to the side of one end of the sleeve and the core layer and the end plate is in contact with the sleeve and the core layer to obtain the extruded blank.

[0020] Furthermore, in method c, the method for preparing the dissimilar aluminum alloy seamless composite tube further includes the step of preparing a sleeve, wherein the method for preparing the sleeve includes melting, casting, and extruding the raw materials of the sleeve to obtain the sleeve.

[0021] Furthermore, in methods b and c, the preparation method of the dissimilar aluminum alloy seamless composite tube further includes the step of preparing a core layer. The preparation method of the core layer includes melting, casting, and peeling the raw materials of the core layer to obtain the core layer, or the preparation method of the core layer includes melting, casting, and extruding the raw materials of the core layer to obtain the core layer.

[0022] Furthermore, in methods a and c, the preparation method of the dissimilar aluminum alloy seamless composite tube further includes the step of preparing an end plate. The preparation method of the end plate includes melting, casting, peeling, and slicing the raw material of the end plate to obtain the end plate, or the preparation method of the end plate includes melting, casting, extruding, and slicing the raw material of the end plate to obtain the end plate, or the preparation method of the end plate includes punching or machining a sheet material of the same material as the end plate to obtain the end plate.

[0023] Furthermore, in method b, the end plate includes an end plate body, and the end plate may optionally include an end plate attachment. When the end plate also includes the end plate attachment, the end plate body and the sleeve are formed by stamping the sheet metal. The end plate attachment is located between the end face of the core layer and the side face of the end plate body, and the opposite two sides of the end plate attachment are in contact with the core layer and the end plate body, respectively.

[0024] According to some preferred embodiments of the invention, in methods b and c, the core layer and the sleeve are subjected to interference heat bonding.

[0025] According to some embodiments of the present invention, the core layer is a 3-series aluminum alloy or an aluminum alloy of a different material from the sleeve and the end plate, wherein the sleeve and the end plate are respectively a 4-series aluminum alloy or an aluminum alloy of a different material from the core layer.

[0026] According to some embodiments of the present invention, the extrusion of the extruded billet is either forward extrusion or reverse extrusion.

[0027] Further, the thickness of the end plate is denoted as D1, and the wall thickness of the sleeve is denoted as D2. When the forward extrusion is performed, D1 is greater than or equal to D2; when the reverse extrusion is performed, D1 is greater than or equal to 0.02 times D2.

[0028] Furthermore, when performing the forward extrusion, D1 is greater than or equal to D2 and less than or equal to 10 times D2; when performing the reverse extrusion, D1 is greater than or equal to 0.02 times D2 and less than or equal to 10 times D2.

[0029] More preferably, when performing the forward extrusion, D1 is greater than or equal to 3 times D2 and less than or equal to 8 times D2; when performing the reverse extrusion, D1 is greater than or equal to 0.1 times D2 and less than or equal to 9 times D2.

[0030] Furthermore, the wall thickness of the sleeve is 0.5-10 mm.

[0031] Furthermore, when performing the forward extrusion, the extrusion process parameters are: die temperature 350-480℃, extruded billet temperature 350-480℃, and extruder main cylinder speed 0.5-5mm / s; when performing the reverse extrusion, the extrusion process parameters are: die temperature 350-480℃, extruded billet temperature 350-480℃, and extruder main cylinder speed 0.5-5mm / s.

[0032] According to some preferred embodiments of the invention, when the end plate is embedded inside one end of the sleeve, the other side of the end plate is flush with the end face of the sleeve.

[0033] According to some embodiments of the present invention, the method for preparing the dissimilar aluminum alloy seamless composite tube further includes the step of drawing the seamless composite tube blank to produce the finished aluminum alloy seamless composite tube.

[0034] In this invention, the end plate is embedded inside one end of the sleeve. The end plate and the sleeve can be independent components that are then assembled together; or the end plate and the sleeve can be integrally formed.

[0035] In this invention, the material of the sleeve and the end plate being the same series of aluminum alloys means that they are alloys of the same series, but the specific grades or raw material formulas are different. For example, both are 4-series aluminum alloys, specifically, the sleeve is 4045 alloy and the end plate is 4043 alloy. The material of the sleeve and the end plate being the same material means that they are aluminum alloys of the same grade, such as both the sleeve and the end plate being 4045 alloy, or both being 4043 alloy.

[0036] Due to the application of the above-mentioned technical solution, the present invention has the following advantages compared with the prior art:

[0037] Through extensive experimental research, the inventors unexpectedly discovered that in the preparation of seamless aluminum alloy composite tubes with a core layer of 3-series aluminum alloy and a sleeve of 4-series aluminum alloy, using extruded blanks with end plates, and ensuring that the end plates are made of the same series or the same material as the sleeve, can completely solve the problem of the 3-series aluminum alloy backflow layer. The seamless aluminum alloy composite tube blank is free of the 3-series aluminum alloy backflow layer along its entire length, avoiding the need for chemical cleaning or mechanical removal of the 3-series aluminum alloy backflow layer, significantly reducing processes and costs. Simultaneously, the yield of the finished seamless aluminum alloy composite tube is significantly improved compared to existing technologies. Based on this discovery, further research led to the development and proposal of this invention.

[0038] The method of this invention for preparing seamless aluminum alloy composite tubes significantly improves the yield compared to existing technologies (existing studies have shown that the yield can be doubled). At the same time, it completely eliminates the need for chemical cleaning or mechanical removal of the core reflux layer, reducing the number of processes and greatly lowering costs. Therefore, the method of this invention obviously has greater economic benefits than existing technologies. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the process for preparing the extruded billet in Example 1;

[0040] Figure 2 Metallographic photograph of the seamless composite tube blank of Example 1;

[0041] Figure 3 This is a schematic diagram of the process for preparing the extruded billet in Example 3;

[0042] Figure 4 Metallographic photograph of the seamless composite tube blank for Comparative Example 1;

[0043] Figure 5 This is a schematic diagram of the process for preparing the extruded billet in Example 10;

[0044] Figure 6 Metallographic photograph of the seamless composite tube blank of Example 10;

[0045] Figure 7 This is a schematic diagram of the process for preparing the extruded billet in Example 11;

[0046] Figure 8 Metallographic photograph of the seamless composite tube blank in Comparative Example 3;

[0047] Figure 9 This is a schematic diagram of the process for preparing the extruded billet in Example 19;

[0048] Figure 10 Metallographic photograph of the seamless composite tube blank of Example 19;

[0049] Figure 11 This is a schematic diagram of the process for preparing the extruded billet in Example 20;

[0050] Figure 12 Metallographic photograph of the seamless composite tube blank in Comparative Example 5;

[0051] In the diagram: 1. Sleeve; 2. Core layer; 3. End plate; 3a. End plate body; 3b. End plate auxiliary plate. Detailed Implementation

[0052] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications or alterations to the invention, such as adjusting the composition, specifications, and shape of the core layer, sleeve, and end plate. These equivalent forms also fall within the scope defined by the appended claims.

[0053] The following Examples 1 to 9 use method a of the present invention to prepare extruded billets. All composite casting billets involved are prepared by peeling and sawing composite casting rods.

[0054] Example 1

[0055] The method for preparing dissimilar aluminum alloy seamless composite tubes provided in this embodiment, wherein,

[0056] For the extruded blanks used in seamless composite tubes made of dissimilar aluminum alloys, see [link / reference]. Figure 1 As shown, the extruded blank includes a core layer 2 and a seamless sleeve 1 and an end plate 3 sleeved around the core layer 2. The end plate 3 is located on the side of one end of the core layer 2 and the sleeve 1, and the end face of the core layer 2 and the end face of the sleeve 1 are in contact with the side of the end plate 3 without gap, so as to avoid the generation of air bubbles during the processing and affect the quality of the composite pipe.

[0057] The preparation method of dissimilar aluminum alloy seamless composite tubes includes the following steps:

[0058] 1) The core layer 2 is made of 3003 aluminum alloy; the sleeve 1 is made of 4045 aluminum alloy; the end plate 3 is made of the same material as the sleeve 1.

[0059] 2) The raw materials of core layer 2 and sleeve 1 are melted and smelted separately, then conventionally composite cast, peeled, and sawn to obtain composite casting billets. The dimensional parameters of the composite casting billets are shown in Table 1.

[0060] 3) The raw material of end plate 3 is melted, cast into rods, peeled, and sliced ​​to obtain end plate 3. The dimensional parameters of end plate 3 are shown in Table 1.

[0061] 4) Place the end plate 3 and the composite casting billet in the extrusion cylinder of the extrusion press in sequence, so that the end plate 3 is located to the side of one end of the composite casting billet and one side of the end plate 3 is in contact with the end face of the composite casting billet with zero gap to obtain the extruded billet. At the same time, the other side of the end plate 3 needs to be in contact with the extrusion die, pierced and then extruded in reverse to obtain the composite tube billet. The extrusion process parameters are: die temperature 450℃, extruded billet temperature 450℃, and extrusion cylinder speed 1.0mm / s.

[0062] 5) Place the composite tube blank in the drawing die and draw it into the finished composite tube.

[0063] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 1. Figure 2 Metallographic photograph of example composite tube blank at 10m.

[0064] Example 2

[0065] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0066] In step 2), the dimensional parameters of the composite casting billet are shown in Table 1.

[0067] In step 3), the raw material of end plate 3 is melted, cast, extruded and sliced ​​to obtain end plate 3. The dimensional parameters of end plate 3 are shown in Table 1.

[0068] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 1.

[0069] Example 3

[0070] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0071] For the extruded blanks used in seamless composite tubes made of dissimilar aluminum alloys, see [link / reference]. Figure 3 As shown, the end plate 3 is embedded inside one end of the sleeve 1, and the end face of the core layer 2 is in close contact with the side of the end plate 3 without any gap. The outer circumferential surface of the end plate 3 is in close contact with the inner circumferential surface of the sleeve 1 without any gap, thus avoiding the generation of air bubbles during processing and affecting the quality of the composite tube. The other side of the end plate 3 is flush with the end face of the sleeve 1, which facilitates the direct and good fit between the end plate 3 and the extrusion die during the extrusion of the blank.

[0072] In step 2), the raw materials of core layer 2 and sleeve 1 are melted and smelted separately, then conventionally composite cast, peeled, and sawn to obtain composite casting billet. At the same time, part of the core layer 2 inside one end of the composite casting billet is removed. The dimensional parameters of the composite casting billet are shown in Table 1.

[0073] In step 3), the end plate 3 is made by stamping aluminum plate with the same material as the end plate 3. The dimensional parameters of the end plate 3 are shown in Table 1.

[0074] In step 4), the end plate 3 is embedded into the end of the composite casting billet to obtain the extruded billet. Then the extruded billet is placed in the extrusion cylinder, and the side of the end plate 3 is made to fit with the extrusion die. After perforation, reverse extrusion is performed to obtain the composite tube billet.

[0075] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 1.

[0076] Example 4

[0077] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 3, except that:

[0078] In step 3), the dimensional parameters of end plate 3 are shown in Table 1.

[0079] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 1.

[0080] Example 5

[0081] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 3, except that:

[0082] In step 3), the dimensional parameters of end plate 3 are shown in Table 1.

[0083] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 1.

[0084] Example 6

[0085] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 3, except that:

[0086] In step 3), the dimensional parameters of end plate 3 are shown in Table 1.

[0087] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 1.

[0088] Example 7

[0089] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 3, except that:

[0090] In step 3), the raw material of end plate 3 is melted, cast, extruded and sliced ​​to obtain end plate 3. The dimensional parameters of end plate 3 are shown in Table 1.

[0091] In step 4), forward extrusion is performed to obtain composite tube blank. The extrusion process parameters are: die temperature 420℃, extrusion blank temperature 420℃, and extrusion main cylinder speed 1.5mm / s.

[0092] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 1.

[0093] Example 8

[0094] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0095] In step 3), the raw material of end plate 3 is melted, cast, extruded and sliced ​​to obtain end plate 3. The dimensional parameters of end plate 3 are shown in Table 1.

[0096] In step 4), forward extrusion is performed to obtain composite tube blank. The extrusion process parameters are: die temperature 420℃, extrusion blank temperature 420℃, and extrusion main cylinder speed 1.5mm / s.

[0097] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 1.

[0098] Example 9

[0099] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 3, except that:

[0100] In step 4), forward extrusion is performed to obtain composite tube blank. The extrusion process parameters are: die temperature 400℃, extrusion blank temperature 400℃, and extrusion main cylinder speed 1.5mm / s.

[0101] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 1.

[0102] Comparative Example 1

[0103] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this comparative example is basically the same as that in Example 1, except that: no end plate is set, but the composite casting billet is directly used as the extrusion billet for reverse extrusion. The dimensions of the composite casting billet are shown in Table 1.

[0104] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 1. Figure 4 Metallographic photograph of example composite tube blank at 10m.

[0105] Comparative Example 2

[0106] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this comparative example is basically the same as that in Example 7, except that:

[0107] Instead of using end plates, the composite casting billet is directly used as the extrusion billet for forward extrusion. The dimensions of the composite casting billet are shown in Table 1.

[0108] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 1.

[0109] Table 1 shows the processing technology and test results of the composite tube blanks for Examples 1-9 and Comparative Examples 1-2.

[0110]

[0111] As shown in Table 1, the composite tube blanks prepared in Examples 1-9 do not have a 3-series aluminum alloy backflow layer along their entire length. In Comparative Example 1, without end plates 3, the extruded blank was extruded in reverse, and the composite tube blank was 20m long, with a 3-series aluminum alloy backflow layer present for the first 14m. In Comparative Example 2, without end plates 3, the extruded blank was extruded in forward, and the composite tube blank had a 3-series aluminum alloy backflow layer throughout its 20m length, severely affecting the yield.

[0112] The following Examples 10-18 use method b of the present invention to prepare extruded billets.

[0113] Example 10

[0114] The method for preparing dissimilar aluminum alloy seamless composite tubes provided in this embodiment, wherein,

[0115] For the extruded blanks used in seamless composite tubes made of dissimilar aluminum alloys, see [link / reference]. Figure 5 As shown, the extruded billet includes a core layer 2 and a seamless sleeve 1 and an end plate 3 surrounding the core layer 2. The sleeve 1 and the end plate 3 are stamped from 4-series aluminum alloy sheets, and the end face of the core layer 2 is in close contact with the side face of the end plate 3 without any gap. The materials of the sleeve 1 and the end plate 3, and the core layer 2 are the same as in Example 1.

[0116] The preparation method of dissimilar aluminum alloy seamless composite tubes includes the following steps:

[0117] 1) The sleeve 1 and the end plate 3 integrally formed with the sleeve 1 are obtained by stamping, stretching and thinning of 4 series aluminum alloy sheet. The dimensional parameters are shown in Table 2.

[0118] 2) Melt the raw material of core layer 2, cast it into a rod, peel it, and saw it to obtain core layer 2. The dimensional parameters of core layer 2 are shown in Table 2.

[0119] 3) After heating the sleeve 1 and end plate 3 obtained in step 1), combine them with the core layer 2 and make the end face of the core layer 2 and the side face of the end plate 3 in close contact without gap to obtain the extruded blank. Then place the extruded blank in the extrusion cylinder and make the side face of the end plate 3 fit with the extrusion mold, pierce it and then perform reverse extrusion to obtain the composite tube blank. The reverse extrusion process parameters are the same as in Example 1.

[0120] 4) The composite pipe blank is drawn to produce the finished composite pipe.

[0121] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 2. Figure 6 Metallographic photograph of example composite tube blank at 10m.

[0122] Example 11

[0123] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 10, except that:

[0124] See Figure 7 As shown, the extruded blank includes a core layer 2 and a seamless sleeve 1 and an end plate 3 sleeved around the core layer 2. The end plate 3 includes an end plate body 3a integrally stamped with the sleeve 1 and an end plate attachment 3b located between the end face of the core layer 2 and the side face of the end plate body 3a.

[0125] The end plate attachment 3b is made by peeling and slicing a cast rod of the same material as the sleeve 1. The diameter of the end plate attachment 3b is 172.5 mm and the thickness is 15 mm.

[0126] In step 1), the dimensional parameters of the sleeve 1 and the end plate body 3a integrally stamped with the sleeve 1 are shown in Table 2.

[0127] In step 3), the sleeve 1 and the end plate body 3a are heated and then combined with the end plate attachment 3b and the core layer 2, and the end plate attachment 3b is located between the core layer 2 and the end plate body 3a, and the three are in contact without gaps to obtain the extruded billet.

[0128] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 2.

[0129] Example 12

[0130] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 11, except that:

[0131] The diameter of the end plate attachment 3b is 172mm and the thickness is 25mm.

[0132] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 2.

[0133] Example 13

[0134] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 10, except that:

[0135] In step 1), a 4-series aluminum alloy sheet is used to obtain a sleeve 1 and an end plate 3 integrally formed with the sleeve 1 by stamping, stretching, thinning, turning and milling. The dimensional parameters are shown in Table 2.

[0136] In step 2), the raw material of core layer 2 is melted, cast into a rod, extruded, and sawn to obtain core layer 2. The dimensional parameters of core layer 2 are shown in Table 2.

[0137] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 2.

[0138] Example 14

[0139] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 13, except that:

[0140] In step 1), the sleeve 1 and the end plate 3 integrally formed with the sleeve 1 are obtained, and the dimensional parameters are shown in Table 2.

[0141] In step 2), the dimensions of the core layer 2 are shown in Table 2.

[0142] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 2.

[0143] Example 15

[0144] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 13, except that:

[0145] In step 1), the dimensional parameters of the sleeve 1 and the end plate 3 integrally formed with the sleeve 1 are shown in Table 2.

[0146] In step 2), the dimensional parameters of the core layer 2 are shown in Table 2.

[0147] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 2.

[0148] Example 16

[0149] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 12, except that:

[0150] In step 2), the raw material of core layer 2 is melted, cast into a rod, extruded, and sawn to obtain core layer 2. The dimensions of core layer 2 are shown in Table 2.

[0151] In step 3), the extruded billet is subjected to forward extrusion, wherein the forward extrusion process parameters are the same as in Example 7.

[0152] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 2.

[0153] Example 17

[0154] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 11, except that:

[0155] In step 3), the extruded billet is subjected to forward extrusion, wherein the forward extrusion process parameters are the same as in Example 7.

[0156] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 2.

[0157] Example 18

[0158] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 10, except that:

[0159] In step 3), the extruded billet is subjected to forward extrusion, wherein the forward extrusion process parameters are the same as in Example 7.

[0160] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 2.

[0161] Comparative Example 3

[0162] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this comparative example is basically the same as that in Example 13, except that:

[0163] In step 1), the dimensional parameters of the sleeve 1 and the end plate 3 integrally formed with the sleeve 1 are shown in Table 2 (i.e., no end plate is set).

[0164] In step 2), the raw material of core layer 2 is melted, cast into a rod, peeled, and sawn to obtain core layer 2. The dimensions of core layer 2 are shown in Table 2.

[0165] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 2. Figure 8 Metallographic photograph of example composite tube blank at 10m.

[0166] Comparative Example 4

[0167] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this comparative example is basically the same as that in Comparative Example 3, except that:

[0168] In step 3), the extruded billet is subjected to forward extrusion, wherein the forward extrusion process parameters are the same as in Example 7.

[0169] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 2.

[0170] Table 2 shows the processing technology and test results of the composite tube blanks for Examples 10-18 and Comparative Examples 3-4.

[0171]

[0172]

[0173] As shown in Table 2, the composite tube blanks prepared in Examples 10-18 do not have a 3-series aluminum alloy backflow layer along their entire length. In Comparative Example 3, no end plate was provided, and the extruded blank was extruded in reverse. The composite tube blank was 20m long, and a 3-series aluminum alloy backflow layer was present for the first 14m. In Comparative Example 4, no end plate was provided, and the extruded blank was extruded in forward. The composite tube blank had a 3-series aluminum alloy backflow layer for the entire 20m length, which seriously affected the yield.

[0174] The following Examples 19-27 use the method c of the present invention to prepare extruded billets, and the sleeves are all prepared by sawing extruded tubes.

[0175] Example 19

[0176] The method for preparing dissimilar aluminum alloy seamless composite tubes provided in this embodiment, wherein,

[0177] For the extruded blanks used in seamless composite tubes made of dissimilar aluminum alloys, see [link / reference]. Figure 9 As shown, the extruded billet includes a core layer 2 and a seamless sleeve 1 and an end plate 3 sleeved around the core layer 2. The end plate 3 is located on the side of one end of the core layer 2 and the sleeve 1, and the end face of the core layer 2 and the end face of the sleeve 1 are in close contact with the side of the end plate 3 without any gap. The materials of the sleeve 1 and the end plate 3, and the core layer 2 are the same as in Example 1.

[0178] The preparation method of dissimilar aluminum alloy seamless composite tubes includes the following steps:

[0179] 1) The raw material of sleeve 1 is melted, cast into a rod, extruded, and sawn to obtain sleeve 1. The dimensional parameters are shown in Table 3.

[0180] 2) Melt the raw material of core layer 2, cast it into a rod, peel it, and saw it to obtain core layer 2. The dimensional parameters of core layer 2 are shown in Table 3.

[0181] 3) Melt the raw material of end plate 3, cast it into a rod, peel it, and saw it to obtain end plate 3. The dimensional parameters of end plate 3 are shown in Table 3.

[0182] 4) After heating the sleeve 1, combine it with the core layer 2, and then place it and the end plate 3 in the extrusion cylinder of the extrusion press in sequence, so that the end plate 3 is located on the side of one end of the sleeve 1 and the core layer 2 and one side of the end plate 3 is in zero-gap contact with the end face of the sleeve 1 and the core layer 2 to obtain the extruded blank. At the same time, the other side of the end plate 3 needs to be in contact with the extrusion die, perforated and then extruded in reverse to obtain the composite tube blank. The extrusion process parameters are the same as in Example 1.

[0183] 5) Place the composite tube blank in the drawing die and draw it into the finished composite tube.

[0184] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 3. Figure 10 Metallographic photograph of example composite tube blank at 10m.

[0185] Example 20

[0186] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 19, except that:

[0187] For the extruded blanks used in seamless composite tubes made of dissimilar aluminum alloys, see [link / reference]. Figure 11 As shown, the end plate 3 is embedded inside one end of the sleeve 1, and the end face of the core layer 2 is in close contact with the side of the end plate 3 without any gap. The outer circumferential surface of the end plate 3 is in close contact with the inner circumferential surface of the sleeve 1 without any gap, thus avoiding the generation of air bubbles during processing and affecting the quality of the composite tube. The other side of the end plate 3 is flush with the end face of the sleeve 1, which facilitates the direct and good fit between the end plate 3 and the extrusion die during the extrusion of the blank.

[0188] The dimensional parameters of sleeve 1, core layer 2, and end plate 3 are shown in Table 3.

[0189] In step 4), the sleeve 1 is heated and combined with the core layer 2 and the end plate 3, so that one side of the end plate 3 is in close contact with the end face of the core layer 2 without gap, and the other side of the end plate 3 is flush with the end face of the sleeve 1 to obtain the extruded blank.

[0190] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 3.

[0191] Example 21

[0192] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 20, except that:

[0193] The dimensional parameters of sleeve 1 and core layer 2 are shown in Table 3.

[0194] End plate 3 is made of aluminum sheet by stamping, and the dimensional parameters are shown in Table 3.

[0195] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 3.

[0196] Example 22

[0197] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 21, except that:

[0198] The dimensional parameters of sleeve 1, core layer 2, and end plate 3 are shown in Table 3.

[0199] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 3.

[0200] Example 23

[0201] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 21, except that:

[0202] The dimensional parameters of sleeve 1, core layer 2, and end plate 3 are shown in Table 3.

[0203] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 3.

[0204] Example 24

[0205] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 21, except that:

[0206] In step 2), the raw material of core layer 2 is melted, cast into a rod, extruded, and sawn to obtain core layer 2. The dimensional parameters of core layer 2 are shown in Table 3.

[0207] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 3.

[0208] Example 25

[0209] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 24, except that:

[0210] In step 2), the dimensional parameters of the core layer 2 are shown in Table 3.

[0211] In step 3), the raw material of end plate 3 is melted, cast into a rod, extruded, and sliced ​​to obtain end plate 3. The dimensional parameters of end plate 3 are shown in Table 3.

[0212] In step 4), forward extrusion is performed to obtain composite tube blanks. The extrusion process parameters are: die temperature 420℃, extrusion blank temperature 420℃, and extrusion main cylinder speed 1.5mm / s.

[0213] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 3.

[0214] Example 26

[0215] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 19, except that:

[0216] The dimensional parameters of the core layer 2 and the end plate 3 are shown in Table 3.

[0217] In step 4), forward extrusion is performed to obtain composite tube blanks. The extrusion process parameters are: die temperature 420℃, extrusion blank temperature 420℃, and extrusion main cylinder speed 1.5mm / s.

[0218] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 3.

[0219] Example 27

[0220] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this embodiment is basically the same as that in Embodiment 25, except that:

[0221] The dimensional parameters of core layer 2 are shown in Table 3.

[0222] In step 3), the aluminum plate is machined to obtain end plate 3, wherein the dimensional parameters of end plate 3 are shown in Table 3.

[0223] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 3.

[0224] Comparative Example 5

[0225] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this comparative example is basically the same as that in Example 19, except that:

[0226] End plate 3 is not installed.

[0227] The dimensional parameters of sleeve 1 and core layer 2 are shown in Table 3.

[0228] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 3. Figure 12 Metallographic photograph of example composite tube blank at 10m.

[0229] Comparative Example 6

[0230] The preparation method of the dissimilar aluminum alloy seamless composite tube provided in this comparative example is basically the same as that in Example 25, except that:

[0231] End plate 3 is not installed.

[0232] The dimensional parameters of core layer 2 are shown in Table 3.

[0233] Microstructure analysis of the composite pipe blank and calculation of the yield of the finished composite pipe are shown in Table 3.

[0234] Table 3 shows the processing technology and test results of the composite tube blanks for Examples 19-27 and Comparative Examples 5-6.

[0235]

[0236]

[0237] As shown in Table 3, the composite tube blanks prepared in Examples 19-27 do not have a 3-series aluminum alloy backflow layer along their entire length. In Comparative Example 5, no end plates were provided, and the extruded blank was extruded in reverse. The composite tube blank was 20m long, and a 3-series aluminum alloy backflow layer was present for the first 9m. In Comparative Example 6, no end plates were provided, and the extruded blank was extruded in forward. The composite tube blank had a 3-series aluminum alloy backflow layer for the entire 20m length, which seriously affected the yield.

[0238] The yield rate is calculated as follows:

[0239] Yield = Length of the stable zone without core layer and reflux layer ÷ Total length × 100%.

[0240] Under conventional processes, taking Comparative Example 1 as an example, the total length of the extruded pipe is about 20m, of which 0m-14m is the region with a core layer reflux layer, 14m-19m is the region without a core layer reflux layer and with a stable composite rate, and 19m-20m is the region with an unstable composite rate.

[0241] Under conventional processes, the yield rate = (19-14)÷20×100% = 25%.

[0242] Using the technical solution of the present invention, taking Example 2 as an example, the total length of the extruded pipe is about 20m, and there is no core layer or backflow layer throughout the entire length. Among them, 0m-4m is the unstable composite rate zone 1, 4m-19m is the stable composite rate zone, and 19m-20m is the unstable composite rate zone 2.

[0243] At this point, the yield rate = (19-4)÷20×100% = 75%.

[0244] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0245] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for preparing a seamless composite tube of dissimilar aluminum alloys, comprising the step of extruding an extruded billet to form a seamless composite tube billet, wherein the extruded billet comprises a core layer and a seamless sleeve disposed around the core layer, characterized in that: The extruded billet also includes end plates; The end plate is located to the side of one end of the core layer and the sleeve, and the end face of the core layer and the end face of the sleeve are in contact with the side of the end plate; Alternatively, the end plate is embedded inside one end of the sleeve, and the end face of the core layer is in contact with the side of the end plate, and the outer peripheral surface of the end plate is in contact with the inner peripheral surface of the sleeve. The core layer and the sleeve are made of different series of aluminum alloys, while the sleeve and the end plate are made of the same series of aluminum alloys. When the extrusion step is performed on the extruded billet, the end of the extruded billet having the end plate is extruded first.

2. The method for preparing a seamless composite tube of dissimilar aluminum alloys according to claim 1, characterized in that: The method for preparing the dissimilar aluminum alloy seamless composite tube further includes the step of preparing an extruded billet, wherein the extruded billet is prepared using one of the following methods: Method a: Melt the raw materials of the sleeve and the raw materials of the core layer separately, and then composite cast them to obtain a composite casting billet. Remove part of the core layer inside one end of the composite casting billet, and then embed the end plate into the interior of the one end of the composite casting billet to obtain the extruded billet. Alternatively, the raw materials of the sleeve and the raw materials of the core layer are melted separately, and then composite casting is performed to obtain a composite casting billet. During the extrusion step, the end plate is placed to the side of one end of the composite casting billet and the end plate is in contact with the end face of the composite casting billet to obtain the extruded billet. Method b: Stamping a sheet of the same material as the sleeve to obtain the sleeve and at least a portion of the end plate integrally formed with the sleeve, heating, and then combining with the core layer to obtain the extruded blank; Method c: After heating the sleeve, combine it with the core layer and the end plate to obtain the extruded billet; Alternatively, after heating the sleeve, it can be combined with the core layer, making the end faces of the sleeve and the core layer flush. During the extrusion step, the end plate is placed to the side of one end of the sleeve and the core layer and the end plate is in contact with the sleeve and the core layer to obtain the extruded blank.

3. The method for preparing a seamless composite tube of dissimilar aluminum alloys according to claim 2, characterized in that: In method c, the preparation method of the dissimilar aluminum alloy seamless composite tube further includes a step of preparing a sleeve, wherein the sleeve preparation method includes melting, casting, and extruding the raw materials for the sleeve to obtain the sleeve; and / or, In methods b and c, the preparation method of the dissimilar aluminum alloy seamless composite tube further includes a core layer preparation step. The core layer preparation method includes melting, casting, and peeling the raw materials to obtain the core layer; or the core layer preparation method includes melting, casting, and extruding the raw materials to obtain the core layer; and / or, In methods a and c, the preparation method of the dissimilar aluminum alloy seamless composite tube further includes the step of preparing an end plate. The preparation method of the end plate includes melting, casting, peeling, and slicing the raw material of the end plate to obtain the end plate, or the preparation method of the end plate includes melting, casting, extruding, and slicing the raw material of the end plate to obtain the end plate, or the preparation method of the end plate includes punching or machining a sheet material of the same material as the end plate to obtain the end plate.

4. The method for preparing a seamless composite tube of dissimilar aluminum alloys according to claim 2, characterized in that: In method b, the end plate includes an end plate body and an end plate attachment. When the end plate also includes the end plate attachment, the end plate body and the sleeve are formed by stamping the sheet metal. The end plate attachment is located between the end face of the core layer and the side face of the end plate body, and the two opposite sides of the end plate attachment are in contact with the core layer and the end plate body, respectively.

5. The method for preparing a seamless composite tube of dissimilar aluminum alloys according to claim 2, characterized in that: In methods b and c, the core layer and the sleeve are subjected to interference heat bonding.

6. The method for preparing a seamless composite tube of dissimilar aluminum alloys according to any one of claims 1 to 5, characterized in that: The core layer is made of 3-series aluminum alloy or an aluminum alloy of a different material than the sleeve and the end plate. The sleeve and the end plate are made of 4-series aluminum alloy or an aluminum alloy of a different material than the core layer.

7. The method for preparing a seamless composite tube of dissimilar aluminum alloys according to any one of claims 1 to 5, characterized in that: The extrusion of the extruded billet is either forward extrusion or reverse extrusion.

8. The method for preparing a seamless composite tube of dissimilar aluminum alloys according to claim 7, characterized in that: When performing the forward extrusion, the extrusion process parameters are: die temperature 350-480℃, extruded billet temperature 350-480℃, and extruder main cylinder speed 0.5-5mm / s; when performing the reverse extrusion, the extrusion process parameters are: die temperature 350-480℃, extruded billet temperature 350-480℃, and extruder main cylinder speed 0.5-5mm / s.

9. The method for preparing a seamless composite tube of dissimilar aluminum alloys according to claim 1, characterized in that: The wall thickness of the sleeve is 0.5-10mm.

10. The method for preparing a seamless composite tube of dissimilar aluminum alloys according to any one of claims 1 to 5, characterized in that: When the end plate is embedded inside one end of the sleeve, the other side of the end plate is flush with the end face of the sleeve.

11. The method for preparing a seamless composite tube of dissimilar aluminum alloys according to any one of claims 1 to 5, characterized in that: The method for preparing the dissimilar aluminum alloy seamless composite tube also includes the step of drawing the seamless composite tube blank to produce the finished aluminum alloy seamless composite tube.

12. The method for preparing a seamless composite tube of dissimilar aluminum alloys according to claim 1, characterized in that: The sleeve and the end plate are made of the same material.

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